Attachment #37570 for bug #60462

View | Details | Raw Unified | Return to bug 60462
Collapse All | Expand All

Lines 36-41 Link Here

(-)linux-2.6.8.1_supermount/Documentation/filesystems/00-INDEX (+2 lines)
36	- Description of the ROMFS filesystem.	36	- Description of the ROMFS filesystem.
37	smbfs.txt	37	smbfs.txt
38	- info on using filesystems with the SMB protocol (Windows 3.11 and NT)	38	- info on using filesystems with the SMB protocol (Windows 3.11 and NT)
		39	supermount.txt
		40	- info on using supermount for removable media.
39	sysv-fs.txt	41	sysv-fs.txt
40	- info on the SystemV/V7/Xenix/Coherent filesystem.	42	- info on the SystemV/V7/Xenix/Coherent filesystem.
41	udf.txt	43	udf.txt




Supermount README
=================

Running supermount
------------------

To run supermount, compile and install a kernel with the supermount
patches and select "Y" to the question

	Supermount removable media support (CONFIG_SUPERMOUNT) [Y/n/?] 

when you run "make config".  You mount a supermount filesystem with
the normal mount command, using the syntax

	mount -t supermount -o <superfs-options>,--,<subfs-options> none <mpt>

or by adding correpsonding line to /etc/fstab

	none  <mpt> supermount <superfs-options>,--,<subfs-options> 0 0

where

	<superfs-options> are the options you want to pass to supermount
	itself.  These are described below.

	<subfs-options> are the options you want supermount to pass to the
	dismountable filesystem underneath.

	<mpt> is the mount point where you want your removable media to be
	mounted. 

WARNING: in the above description `none' is literal word. While device
is ignored by supermount itself, using real files in this place (real
device name or mount point directory name) is known to cause problems.
Some programs - fuser is one of them - will try to descend into filesystem
if dev can be statted, thus making supermount to attempt to access media.
This is annoying at best - in the worst case it can take very long time
during startup or shutdown.

Notice that you do not directly specify the block device you are going
to mount on the mount command line.  This is because the supermount
filesystem is NOT connected to a block device; rather, supermount is
responsible for connecting a separate filesystem to the block device.
You specify the sub-filesystem and block device name by providing the
<superfs-options> field, where the following options are currently
recognised:


* fs=<filesystem-type>			[default is "auto"]

	Specify the subfilesystem type. Not every filesystem type has
been tested.  If you use `auto', it will try the following filesystems
in order:
		    	"udf"
			"iso9660"
			"ext2"
			"vfat"
			"msdos"

It is also possible to give list of types separated by `:', like

		fs=ext2:vfat
		    - or -
		fs=udf:iso9660
 

* dev=<block-device>			[no default, mandatory]

	Specify the block device on which the subfs is to be mounted.


* tray_lock={always,onwrite,never}	[default is "onwrite"]

	Specify when supermount is to prevent media removal. `always' means
on every access (it was default in earlier versions), `onwrite' means only
for write access and `never' means never :) `onwrite' and `never' are the
same for ro media like CD-ROM. It is not clear when `never' is actually useful,
it is presented for completeness only.

* debug[=<bitmap>]			[default is no debug]

	Enable debugging code in the supermount filesystem, if
the debug option was enabled at compile time.  By default, debugging
code is compiled into the kernel but is disabled until a debug mount
option is seen. <bitmap> is the combination of debug flags, following
flags are possible:

	0x001 - "generic" debug (used by supermount_debug) - default
	0x002 - trace dentry.c
	0x004 - trace file.c
	0x008 - trace filemap.c
	0x010 - trace mediactl.c
	0x020 - trace namei.c
	0x040 - trace subfs.c
	0x080 - trace super.c

Trace flags turn on tracing of functions in correpsonding files.
"Generic" debug flag is tested in supermount_debug; for compatibility,
if no flags are specified, this flag is set.


* '--'

	All options after the option string '--' will be passed
directly to the subfilesystem when it gets mounted.

Errors
------

In addition to "normal" errors during file operations supermount may
return following error codes:

* No medium found

	You attempt to access supermounted filesystem when there is no
medium inserted

* Wrong medium type

	(Not really generated by supermount) You attempt to mount CD
without data tracks

* Stale NFS file handle

	You attempt to use file handle after medium has been changed.

* No such device or address

	(Not really generated by supermount) device specified in
dev=<device> option does not exist. Also some drivers return this
error instead of "No medium found", one example being floppy driver.

* Device or resource busy

	(Not really generated by supermount) device is already mounted.
Supermount prevents double mount even if kernel otherwise would make it
possible.

* No such file or directory

	(Not really generated by supermount) file name specified by
dev=<device> option does not exist

* Operation not permitted

	You attempt to access subfs that is currently disabled

/proc support
-------------

If kernel has been compiled with procfs support, supermount will provide
/proc interface to read subfs status and to control some aspects of subfs.
The following files are created under /proc/fs/supermount:

* version (ro)
	Shows supermount version.

* subfs (rw)

	Reading this file returns list of all subfs status. One line for
every subfs is returned; the format is
	
	<devname> disabled
		- or -
	<devname> unmounted
		- or -
	<devname> mounted readcount writecount

where <devname> is the string passed in `dev=' parameter during mount.
`readcount' is number of current subfs "users" needing ro access; `writecount'
is the number of "users" needing rw mode. It is mostly the number of open
files, but inode operations also add to these counts. Those operations
are normally short-lived to be seen.

	Writing this file changes subfs status; the following commands are
suported:

	<devname> [disable|enable] [release [force]]

`disable' will disable subfs (i.e. any futher attempt to mount is rejected).
Subfs must be unmounted; use `disable release' or `disable release force' to
unmount and disable at the same time.

`enable' will enable disabled subfs, it has no effect if subfs is already
enabled.

`release' will unmount subfs unless it is busy (opencount > 0). To unmount
busy subfs add `force'; the effect is very much as if media change has been
detected (with the difference that subfs will be cleanly unmounted).

Some basic sanity checks are performed, i.e. it is impossible to specify
both `enable' and `disable' or `force' without `release'.

Internals/Locking
-----------------

THIS SECTION IS PROBABLY INCOMPLETE. CORRECTIONS ARE WELCOME.

Supermount itself is using two locks and relies on two more locking rules
as implemented by kernel.

* supermount_proc_sem

	Global mutex used to protect list of sbi during access to
/proc/fs/supermount/subfs

* sbi->sem

	Per-filesystem mutex that protects subfs state (mounted/unmounted).
Any changes to subfs state (mounting, unmouting, adding or removing file,
dentry or inode) happen under this mutex.

* inode->i_sem (see Documentation/filesystem/Locking)

	Per-inode mutex used by VFS to serialize inode unlink operation.
Supermount relies on the fact that link/unlink for an inode are mutually
locked and thus inode->i_nlink is atomic inside of fs method.

* BKL

	Used to protect device usage count. It is changed in open/release
and referenced in ioctl all of which run under BKL. Supermount adds mediactl
and internally wraps it in BKL as well.

Caveats/BUGS
------------

Inode times are believed to be correctly updated; still it is possible that
I missed some point.

If subfs is not yet mounted, find /mnt/cdrom fails with "find: /mnt/cdrom
changed during execution of find". It is unlikely it can be fixed in
supermount; much more simple is to provide wrapper that will check if subfs
is mounted and do simple "touch  /mnt/cdrom" if not to make sure it is.

Supermount attempts to check for changed media at every operation and
invalidate and umount old subfs to avoid new media corruption in rw case.
Still it is possible that kernel will write out stale information and
it is outside of supermount control.

By default cdrom driver does not check media type i.e. supermount will
try all configured fs types in turn that may be quite time consuming.
Use sysctl -w dev.cdrom.check_media=1 to enable it. Comments in cdrom.c
indicate that some (non conforming) software may have problems with this
settings. YMMV

atime management does not work for special files. There is no hooks from
VFS into fs to indicate when it gets updated

$Id: 4715_supermount-2.0.4-2.6.7.patch,v 1.1 2004/06/22 22:15:04 gregkh Exp $




#include <linux/fcntl.h>
#include <linux/blkdev.h>
#include <linux/times.h>
#include <linux/supermount_media.h>

#include <asm/uaccess.h>


#define CHECKAUDIO if ((ret=check_for_audio_disc(cdi, cdo))) return ret

/* Not-exported routines. */
static int open_for_data(struct cdrom_device_info * cdi, struct block_device *bdev);
static int check_for_audio_disc(struct cdrom_device_info * cdi,
			 struct cdrom_device_ops * cdo);
static void sanitize_format(union cdrom_addr *addr, 

 */
int cdrom_open(struct cdrom_device_info *cdi, struct inode *ip, struct file *fp)
{
	int ret = 0;

	cdinfo(CD_OPEN, "entering cdrom_open\n"); 


	if ((fp->f_flags & O_NONBLOCK) && (cdi->options & CDO_USE_FFLAGS)) {
		ret = cdi->ops->open(cdi, 1);
	} else {
		open_for_data(cdi, ip->i_bdev);
		if (ret)
			goto err;
		if (fp->f_mode & FMODE_WRITE) {

}

static
int open_for_data(struct cdrom_device_info * cdi, struct block_device *bdev)
{
	int ret;
	struct cdrom_device_ops *cdo = cdi->ops;

		cdinfo(CD_OPEN, "open device failed.\n"); 
		goto clean_up_and_return;
	}
	if (CDROM_CAN(CDC_LOCK) && (cdi->options & CDO_LOCK) &&
	    supermount_usage_count(bdev, cdi->use_count) > 0) {
			cdo->lock_door(cdi, 1);
			cdinfo(CD_OPEN, "door locked.\n");
	}

	This ensures that the drive gets unlocked after a mount fails.  This 
	is a goto to avoid bloating the driver with redundant code. */ 
clean_up_and_return:
	cdinfo(CD_OPEN, "open failed.\n"); 
	if (CDROM_CAN(CDC_LOCK) && cdi->options & CDO_LOCK) {
			cdo->lock_door(cdi, 0);
			cdinfo(CD_OPEN, "door unlocked.\n");

		cdi->use_count--;
	if (cdi->use_count == 0)
		cdinfo(CD_CLOSE, "Use count for \"/dev/%s\" now zero\n", cdi->name);
	if (!supermount_usage_count(fp ? fp->f_dentry->d_inode->i_bdev : 0, cdi->use_count) &&
	    (cdo->capability & CDC_LOCK) && !keeplocked) {
		cdinfo(CD_CLOSE, "Unlocking door!\n");
		cdo->lock_door(cdi, 0);

		tracks->cdi, tracks->xa);
}	

#if defined(CONFIG_SUPERMOUNT) || defined(CONFIG_SUPERMOUNT_MODULE)
/*
 * MEDIA_LOCK, MEDIA_UNLOCK
 *   optarg == 0 - do not adjust usage count (compatibility)
 *   optarg == 1 - adjust usage count
 */
int cdrom_mediactl(struct cdrom_device_info *cdi, struct block_device *bdev, int op, int optarg)
{
	struct cdrom_device_ops *cdo = cdi->ops;

	switch (op) {
	case MEDIA_LOCK:
	case MEDIA_UNLOCK:
		if (op == MEDIA_UNLOCK && optarg) {
			cdi->use_count--;
		if (cdi->use_count < 0)
			cdi->use_count = 0;
		}
		if (cdo->capability & ~cdi->mask & CDC_LOCK &&
		    cdi->options & CDO_LOCK &&
			supermount_usage_count(bdev, cdi->use_count) == 0)
			cdo->lock_door(cdi, (op == MEDIA_LOCK));
		if (op == MEDIA_LOCK && optarg)
			cdi->use_count++;
		break;
	default:
		return -EINVAL;
	}
	return 0;
}
#endif

/* Requests to the low-level drivers will /always/ be done in the
   following format convention:


		cdinfo(CD_DO_IOCTL, "entering CDROMEJECT\n"); 
		if (!CDROM_CAN(CDC_OPEN_TRAY))
			return -ENOSYS;
		if (keeplocked ||
		    (supermount_usage_count(ip->i_bdev,cdi->use_count) != 1))
                        return -EBUSY;
		if (CDROM_CAN(CDC_LOCK))
			if ((ret=cdo->lock_door(cdi, 0)))
				return ret;

EXPORT_SYMBOL(cdrom_release);
EXPORT_SYMBOL(cdrom_ioctl);
EXPORT_SYMBOL(cdrom_media_changed);
#if defined(CONFIG_SUPERMOUNT) || defined(CONFIG_SUPERMOUNT_MODULE)
EXPORT_SYMBOL(cdrom_mediactl);
#endif
EXPORT_SYMBOL(cdrom_number_of_slots);
EXPORT_SYMBOL(cdrom_mode_select);
EXPORT_SYMBOL(cdrom_mode_sense);





static int scd_block_release(struct inode *inode, struct file *file)
{
#if defined(CONFIG_SUPERMOUNT) || defined(CONFIG_SUPERMOUNT_MODULE)
        /*
         * This is the same sort of clockload as use in blkdev_get.
         * We need information whether device is supermounted inside
         * of cdrom_release to decide if tray must be unlocked.
         * This information so far is available only by looking
         * up superblock but it needs struct *bdev and it is not
         * available in cdrom_release anymore
         */
        struct dentry t_dentry;
        struct file t_file;

        if (!file) {
                t_file.f_dentry = &t_dentry;
                t_dentry.d_inode = inode;
                file = &t_file;
        }
#endif

	return cdrom_release(&scd_info, file);
}


	return cdrom_media_changed(&scd_info);
}

#if defined(CONFIG_SUPERMOUNT) || defined(CONFIG_SUPERMOUNT_MODULE)
static int scd_block_mediactl(struct block_device *bdev, int op, int arg)
{
	return cdrom_mediactl(&scd_info, bdev, op, arg);
}
#endif

struct block_device_operations scd_bdops =
{
	.owner		= THIS_MODULE,

	.release	= scd_block_release,
	.ioctl		= scd_block_ioctl,
	.media_changed	= scd_block_media_changed,
#if defined(CONFIG_SUPERMOUNT) || defined(CONFIG_SUPERMOUNT_MODULE)
	.mediactl	= scd_block_mediactl,
#endif
};

static struct gendisk *scd_gendisk;





static int cm206_block_release(struct inode *inode, struct file *file)
{
#if defined(CONFIG_SUPERMOUNT) || defined(CONFIG_SUPERMOUNT_MODULE)
        /*
         * This is the same sort of clockload as use in blkdev_get.
         * We need information whether device is supermounted inside
         * of cdrom_release to decide if tray must be unlocked.
         * This information so far is available only by looking
         * up superblock but it needs struct *bdev and it is not
         * available in cdrom_release anymore
         */
        struct dentry t_dentry;
        struct file t_file;

        if (!file) {
                t_file.f_dentry = &t_dentry;
                t_dentry.d_inode = inode;
                file = &t_file;
        }
#endif

	return cdrom_release(&cm206_info, file);
}


	return cdrom_media_changed(&cm206_info);
}

#if defined(CONFIG_SUPERMOUNT) || defined(CONFIG_SUPERMOUNT_MODULE)
static int cm206_block_mediactl(struct block_device *bdev, int op, int arg)
{
	return cdrom_mediactl(&cm206_info, bdev, op, arg);
}
#endif

static struct block_device_operations cm206_bdops =
{
	.owner		= THIS_MODULE,

	.release	= cm206_block_release,
	.ioctl		= cm206_block_ioctl,
	.media_changed	= cm206_block_media_changed,
#if defined(CONFIG_SUPERMOUNT) || defined(CONFIG_SUPERMOUNT_MODULE)
	.mediactl	= cm206_block_mediactl,
#endif
};

static struct gendisk *cm206_gendisk;





static int mcd_block_release(struct inode *inode, struct file *file)
{
#if defined(CONFIG_SUPERMOUNT) || defined(CONFIG_SUPERMOUNT_MODULE)
        /*
         * This is the same sort of clockload as use in blkdev_get.
         * We need information whether device is supermounted inside
         * of cdrom_release to decide if tray must be unlocked.
         * This information so far is available only by looking
         * up superblock but it needs struct *bdev and it is not
         * available in cdrom_release anymore
         */
        struct dentry t_dentry;
        struct file t_file;

        if (!file) {
                t_file.f_dentry = &t_dentry;
                t_dentry.d_inode = inode;
                file = &t_file;
        }
#endif

	return cdrom_release(&mcd_info, file);
}


	return cdrom_media_changed(&mcd_info);
}

#if defined(CONFIG_SUPERMOUNT) || defined(CONFIG_SUPERMOUNT_MODULE)
static int mcd_block_mediactl(struct block_device *bdev, int op, int arg)
{
	return cdrom_mediactl(&mcd_info, bdev, op, arg);
}
#endif

static struct block_device_operations mcd_bdops =
{
	.owner		= THIS_MODULE,

	.release	= mcd_block_release,
	.ioctl		= mcd_block_ioctl,
	.media_changed	= mcd_block_media_changed,
#if defined(CONFIG_SUPERMOUNT) || defined(CONFIG_SUPERMOUNT_MODULE)
	.mediactl	= mcd_block_mediactl,
#endif
};

static struct gendisk *mcd_gendisk;




static int mcdx_block_release(struct inode *inode, struct file *file)
{
	struct s_drive_stuff *p = inode->i_bdev->bd_disk->private_data;
#if defined(CONFIG_SUPERMOUNT) || defined(CONFIG_SUPERMOUNT_MODULE)
        /*
         * This is the same sort of clockload as use in blkdev_get.
         * We need information whether device is supermounted inside
         * of cdrom_release to decide if tray must be unlocked.
         * This information so far is available only by looking
         * up superblock but it needs struct *bdev and it is not
         * available in cdrom_release anymore
         */
        struct dentry t_dentry;
        struct file t_file;

        if (!file) {
                t_file.f_dentry = &t_dentry;
                t_dentry.d_inode = inode;
                file = &t_file;
        }
#endif

	return cdrom_release(&p->info, file);
}


	return cdrom_media_changed(&p->info);
}

#if defined(CONFIG_SUPERMOUNT) || defined(CONFIG_SUPERMOUNT_MODULE)
static int mcdx_block_mediactl(struct block_device *bdev, int op, int arg)
{
	struct s_drive_stuff *p = bdev->bd_disk->private_data;
	return cdrom_mediactl(&p->info, bdev, op, arg);
}
#endif

static struct block_device_operations mcdx_bdops =
{
	.owner		= THIS_MODULE,

	.release	= mcdx_block_release,
	.ioctl		= mcdx_block_ioctl,
	.media_changed	= mcdx_block_media_changed,
#if defined(CONFIG_SUPERMOUNT) || defined(CONFIG_SUPERMOUNT_MODULE)
	.mediactl	= mcdx_block_mediactl,
#endif
};






static int sbpcd_block_release(struct inode *inode, struct file *file)
{
	struct sbpcd_drive *p = inode->i_bdev->bd_disk->private_data;
#if defined(CONFIG_SUPERMOUNT) || defined(CONFIG_SUPERMOUNT_MODULE)
        /*
         * This is the same sort of clockload as use in blkdev_get.
         * We need information whether device is supermounted inside
         * of cdrom_release to decide if tray must be unlocked.
         * This information so far is available only by looking
         * up superblock but it needs struct *bdev and it is not
         * available in cdrom_release anymore
         */
        struct dentry t_dentry;
        struct file t_file;

        if (!file) {
                t_file.f_dentry = &t_dentry;
                t_dentry.d_inode = inode;
                file = &t_file;
        }
#endif

	return cdrom_release(p->sbpcd_infop, file);
}


	return cdrom_media_changed(p->sbpcd_infop);
}

#if defined(CONFIG_SUPERMOUNT) || defined(CONFIG_SUPERMOUNT_MODULE)
static int sbpcd_block_mediactl(struct block_device *bdev, int op, int arg)
{
	struct sbpcd_drive *p = bdev->bd_disk->private_data;
	return cdrom_mediactl(p->sbpcd_infop, bdev, op, arg);
}
#endif

static struct block_device_operations sbpcd_bdops =
{
	.owner		= THIS_MODULE,

	.release	= sbpcd_block_release,
	.ioctl		= sbpcd_block_ioctl,
	.media_changed	= sbpcd_block_media_changed,
#if defined(CONFIG_SUPERMOUNT) || defined(CONFIG_SUPERMOUNT_MODULE)
	.mediactl	= sbpcd_block_mediactl,
#endif
};
/*==========================================================================*/
/*




{
	ide_drive_t *drive = inode->i_bdev->bd_disk->private_data;
	struct cdrom_info *info = drive->driver_data;
#if defined(CONFIG_SUPERMOUNT) || defined(CONFIG_SUPERMOUNT_MODULE)
	/*
	 * This is the same sort of clockload as use in blkdev_get.
	 * We need information whether device is supermounted inside
	 * of cdrom_release to decide if tray must be unlocked.
	 * This information so far is available only by looking
	 * up superblock but it needs struct *bdev and it is not
	 * available in cdrom_release anymore
	 */
	struct dentry t_dentry;
	struct file t_file;

	if (!file) {
		t_file.f_dentry = &t_dentry;
		t_dentry.d_inode = inode;
		file = &t_file;
	}
#endif

	cdrom_release (&info->devinfo, file);
	drive->usage--;

	return  0;
}

#if defined(CONFIG_SUPERMOUNT) || defined(CONFIG_SUPERMOUNT_MODULE)
static int idecd_mediactl(struct block_device *bdev, int op, int arg)
{
	struct gendisk *disk = bdev->bd_disk;
	ide_drive_t *drive = disk->private_data;
	struct cdrom_info *info = drive->driver_data;
	return cdrom_mediactl(&info->devinfo, bdev, op, arg);
}
#endif

static struct block_device_operations idecd_ops = {
	.owner		= THIS_MODULE,
	.open		= idecd_open,
	.release	= idecd_release,
	.ioctl		= idecd_ioctl,
	.media_changed	= idecd_media_changed,
	.revalidate_disk= idecd_revalidate_disk,
#if defined(CONFIG_SUPERMOUNT) || defined(CONFIG_SUPERMOUNT_MODULE)
	.mediactl	= idecd_mediactl,
#endif
};

/* options */

Lines 98-103 Link Here

(-)linux-2.6.8.1_supermount/drivers/ide/ide-floppy.c (-4 / +40 lines)
98	#include <linux/cdrom.h>	98	#include <linux/cdrom.h>
99	#include <linux/ide.h>	99	#include <linux/ide.h>
100		100
		101	#include <linux/supermount_media.h>
		102
101	#include <asm/byteorder.h>	103	#include <asm/byteorder.h>
102	#include <asm/irq.h>	104	#include <asm/irq.h>
103	#include <asm/uaccess.h>	105	#include <asm/uaccess.h>
Lines 1877-1883 Link Here
1877		1879
1878	debug_log(KERN_INFO "Reached idefloppy_open\n");	1880	debug_log(KERN_INFO "Reached idefloppy_open\n");
1879		1881
1880	if (drive->usage == 1) {	1882	if (supermount_usage_count(inode->i_bdev, drive->usage) == 1) {
1881	clear_bit(IDEFLOPPY_FORMAT_IN_PROGRESS, &floppy->flags);	1883	clear_bit(IDEFLOPPY_FORMAT_IN_PROGRESS, &floppy->flags);
1882	/* Just in case */	1884	/* Just in case */
1883		1885
Lines 1924-1930 Link Here
1924		1926
1925	debug_log(KERN_INFO "Reached idefloppy_release\n");	1927	debug_log(KERN_INFO "Reached idefloppy_release\n");
1926		1928
1927	if (drive->usage == 1) {	1929	if (supermount_usage_count(inode->i_bdev, drive->usage) == 1) {
1928	idefloppy_floppy_t *floppy = drive->driver_data;	1930	idefloppy_floppy_t *floppy = drive->driver_data;
1929		1931
1930	/* IOMEGA Clik! drives do not support lock/unlock commands */	1932	/* IOMEGA Clik! drives do not support lock/unlock commands */
Lines 1957-1963 Link Here
1957	prevent = 0;	1959	prevent = 0;
1958	/* fall through */	1960	/* fall through */
1959	case CDROM_LOCKDOOR:	1961	case CDROM_LOCKDOOR:
1960	if (drive->usage > 1)	1962	if (supermount_usage_count(bdev, drive->usage) > 1)
1961	return -EBUSY;	1963	return -EBUSY;
1962		1964
1963	/* The IOMEGA Clik! Drive doesn't support this command - no room for an eject mechanism */	1965	/* The IOMEGA Clik! Drive doesn't support this command - no room for an eject mechanism */
Lines 2025-2037 Link Here
2025	return 0;	2027	return 0;
2026	}	2028	}
2027		2029
		2030	#if defined(CONFIG_SUPERMOUNT) \|\| defined(CONFIG_SUPERMOUNT_MODULE)
		2031	static int idefloppy_mediactl (struct block_device *bdev, int op, int optarg)
		2032	{
		2033	ide_drive_t *drive = bdev->bd_disk->private_data;
		2034	idefloppy_floppy_t *floppy = drive->driver_data;
		2035	idefloppy_pc_t pc;
		2036
		2037	switch (op) {
		2038	case MEDIA_LOCK:
		2039	case MEDIA_UNLOCK:
		2040	if (op == MEDIA_UNLOCK && optarg) {
		2041	drive->usage--;
		2042	if (drive->usage < 0)
		2043	drive->usage = 0;
		2044	}
		2045	/* IOMEGA Clik! drives do not support lock/unlock commands */
		2046	if (!test_bit(IDEFLOPPY_CLIK_DRIVE, &floppy->flags)
		2047	&& supermount_usage_count(bdev, drive->usage) == 0) {
		2048	idefloppy_create_prevent_cmd(&pc, (op == MEDIA_LOCK));
		2049	(void) idefloppy_queue_pc_tail(drive, &pc);
		2050	}
		2051	if (op == MEDIA_LOCK && optarg)
		2052	drive->usage++;
		2053	break;
		2054	default:
		2055	return -EINVAL;
		2056	}
		2057	return 0;
		2058	}
		2059	#endif
		2060
2028	static struct block_device_operations idefloppy_ops = {	2061	static struct block_device_operations idefloppy_ops = {
2029	.owner = THIS_MODULE,	2062	.owner = THIS_MODULE,
2030	.open = idefloppy_open,	2063	.open = idefloppy_open,
2031	.release = idefloppy_release,	2064	.release = idefloppy_release,
2032	.ioctl = idefloppy_ioctl,	2065	.ioctl = idefloppy_ioctl,
2033	.media_changed = idefloppy_media_changed,	2066	.media_changed = idefloppy_media_changed,
2034	.revalidate_disk= idefloppy_revalidate_disk	2067	.revalidate_disk= idefloppy_revalidate_disk,
		2068	#if defined(CONFIG_SUPERMOUNT) \|\| defined(CONFIG_SUPERMOUNT_MODULE)
		2069	.mediactl = idefloppy_mediactl,
		2070	#endif
2035	};	2071	};
2036		2072
2037	static int idefloppy_attach (ide_drive_t *drive)	2073	static int idefloppy_attach (ide_drive_t *drive)

Lines 49-54 Link Here

(-)linux-2.6.8.1_supermount/drivers/scsi/sd.c (-2 / +62 lines)
49	#include <linux/kref.h>	49	#include <linux/kref.h>
50	#include <asm/uaccess.h>	50	#include <asm/uaccess.h>
51		51
		52	#include <linux/supermount_media.h>
		53
52	#include <scsi/scsi.h>	54	#include <scsi/scsi.h>
53	#include <scsi/scsi_cmnd.h>	55	#include <scsi/scsi_cmnd.h>
54	#include <scsi/scsi_dbg.h>	56	#include <scsi/scsi_dbg.h>
Lines 469-475 Link Here
469	if (!scsi_device_online(sdev))	471	if (!scsi_device_online(sdev))
470	goto error_out;	472	goto error_out;
471		473
472	if (!sdkp->openers++ && sdev->removable) {	474	if (supermount_usage_count(inode->i_bdev, sdkp->openers++) == 0 && sdev->removable) {
473	if (scsi_block_when_processing_errors(sdev))	475	if (scsi_block_when_processing_errors(sdev))
474	scsi_set_medium_removal(sdev, SCSI_REMOVAL_PREVENT);	476	scsi_set_medium_removal(sdev, SCSI_REMOVAL_PREVENT);
475	}	477	}
Lines 500-506 Link Here
500		502
501	SCSI_LOG_HLQUEUE(3, printk("sd_release: disk=%s\n", disk->disk_name));	503	SCSI_LOG_HLQUEUE(3, printk("sd_release: disk=%s\n", disk->disk_name));
502		504
503	if (!--sdkp->openers && sdev->removable) {	505	if (supermount_usage_count(inode->i_bdev, --sdkp->openers) == 0 && sdev->removable) {
504	if (scsi_block_when_processing_errors(sdev))	506	if (scsi_block_when_processing_errors(sdev))
505	scsi_set_medium_removal(sdev, SCSI_REMOVAL_ALLOW);	507	scsi_set_medium_removal(sdev, SCSI_REMOVAL_ALLOW);
506	}	508	}
Lines 660-665 Link Here
660	goto not_present;	662	goto not_present;
661		663
662	/*	664	/*
		665	* FIXME HACK
		666	* busy device that is unplugged is SDEV_DEL but online and ioctl
		667	* does not return any error. Oh well, it is likely layering
		668	* violation but for now it enables media checks for supermount
		669	*/
		670
		671	if (sdp->sdev_state == SDEV_DEL)
		672	goto not_present;
		673
		674	/*
663	* For removable scsi disk we have to recognise the presence	675	* For removable scsi disk we have to recognise the presence
664	* of a disk in the drive. This is kept in the struct scsi_disk	676	* of a disk in the drive. This is kept in the struct scsi_disk
665	* struct and tested at open ! Daniel Roche (dan@lectra.fr)	677	* struct and tested at open ! Daniel Roche (dan@lectra.fr)
Lines 682-687 Link Here
682	sd_revalidate_disk(sdkp->disk);	694	sd_revalidate_disk(sdkp->disk);
683	}	695	}
684		696
		697	#if defined(CONFIG_SUPERMOUNT) \|\| defined(CONFIG_SUPERMOUNT_MODULE)
		698	/*
		699	* This function performs media control operations. Currently the
		700	* only functions used are MEDIA_LOCK and MEDIA_UNLOCK, to lock and
		701	* unlock the drive door.
		702	*/
		703
		704	static int sd_mediactl(struct block_device *bdev, int op, int optarg)
		705	{
		706	struct scsi_disk *sdkp = scsi_disk(bdev->bd_disk);
		707	struct scsi_device *sdp = sdkp->device;
		708	int rc = 0;
		709
		710	SCSI_LOG_HLQUEUE(3, printk("sd_mediactl: disk=%s\n",
		711	bdev->bd_disk->disk_name));
		712
		713	if (!sdp->removable)
		714	return 0;
		715
		716	if (!scsi_block_when_processing_errors(sdp))
		717	return -ENODEV;
		718
		719	switch (op) {
		720	case MEDIA_LOCK:
		721	if (supermount_usage_count(bdev, sdkp->openers) == 0)
		722	rc = scsi_set_medium_removal(sdp, SCSI_REMOVAL_PREVENT);
		723	/* FIXME is it the right way? */
		724	if (optarg)
		725	sdkp->openers++;
		726	break;
		727	case MEDIA_UNLOCK:
		728	if (optarg && sdkp->openers > 0)
		729	sdkp->openers--;
		730	if (supermount_usage_count(bdev, sdkp->openers) == 0)
		731	rc = scsi_set_medium_removal(sdp, SCSI_REMOVAL_ALLOW);
		732	break;
		733	default:
		734	rc = -EINVAL;
		735	break;
		736	}
		737
		738	return rc;
		739	}
		740	#endif
		741
685	static struct block_device_operations sd_fops = {	742	static struct block_device_operations sd_fops = {
686	.owner = THIS_MODULE,	743	.owner = THIS_MODULE,
687	.open = sd_open,	744	.open = sd_open,
Lines 689-694 Link Here
689	.ioctl = sd_ioctl,	746	.ioctl = sd_ioctl,
690	.media_changed = sd_media_changed,	747	.media_changed = sd_media_changed,
691	.revalidate_disk = sd_revalidate_disk,	748	.revalidate_disk = sd_revalidate_disk,
		749	#if defined(CONFIG_SUPERMOUNT) \|\| defined(CONFIG_SUPERMOUNT_MODULE)
		750	.mediactl = sd_mediactl,
		751	#endif
692	};	752	};
693		753
694	/**	754	/**




{
	int ret;
	struct scsi_cd *cd = scsi_cd(inode->i_bdev->bd_disk);

#if defined(CONFIG_SUPERMOUNT) || defined(CONFIG_SUPERMOUNT_MODULE)
	/*
	 * This is the same sort of clockload as use in blkdev_get.
	 * We need information whether device is supermounted inside
	 * of cdrom_release to decide if tray must be unlocked.
	 * This information so far is available only by looking
	 * up superblock but it needs struct *bdev and it is not
	 * available in cdrom_release anymore
	 */
	struct dentry t_dentry;
	struct file t_file;

	if (!file) {
		t_file.f_dentry = &t_dentry;
		t_dentry.d_inode = inode;
		file = &t_file;
	}
#endif

	ret = cdrom_release(&cd->cdi, file);
	if(ret)
		return ret;

	return cdrom_media_changed(&cd->cdi);
}

#if defined(CONFIG_SUPERMOUNT) || defined(CONFIG_SUPERMOUNT_MODULE)
static int sr_block_mediactl(struct block_device *bdev, int op, int arg)
{
	struct gendisk *disk = bdev->bd_disk;
	struct scsi_cd *cd = scsi_cd(disk);
	return cdrom_mediactl(&cd->cdi, bdev, op, arg);
}
#endif

struct block_device_operations sr_bdops =
{
	.owner		= THIS_MODULE,

	.release	= sr_block_release,
	.ioctl		= sr_block_ioctl,
	.media_changed	= sr_block_media_changed,
#if defined(CONFIG_SUPERMOUNT) || defined(CONFIG_SUPERMOUNT_MODULE)
	.mediactl	= sr_block_mediactl,
#endif
};

static int sr_open(struct cdrom_device_info *cdi, int purpose)

Lines 937-942 Link Here

(-)linux-2.6.8.1_supermount/fs/Kconfig (+2 lines)
937	To compile this as a module, choose M here: the module will be called	937	To compile this as a module, choose M here: the module will be called
938	ramfs.	938	ramfs.
939		939
		940	source "fs/supermount/Kconfig"
		941
940	endmenu	942	endmenu
941		943
942	menu "Miscellaneous filesystems"	944	menu "Miscellaneous filesystems"

Lines 91-93 Link Here

(-)linux-2.6.8.1_supermount/fs/Makefile (+1 lines)
91	obj-$(CONFIG_XFS_FS) += xfs/	91	obj-$(CONFIG_XFS_FS) += xfs/
92	obj-$(CONFIG_AFS_FS) += afs/	92	obj-$(CONFIG_AFS_FS) += afs/
93	obj-$(CONFIG_BEFS_FS) += befs/	93	obj-$(CONFIG_BEFS_FS) += befs/
		94	obj-$(CONFIG_SUPERMOUNT) += supermount/




{
	struct gendisk *disk = bdev->bd_disk;
	struct block_device_operations * bdops = disk->fops;
#if defined(CONFIG_SUPERMOUNT) || defined(CONFIG_SUPERMOUNT_MODULE)
	struct super_block *sb = NULL;
	int supermounted = 0;
#endif

	if (!bdops->media_changed)
		return 0;
	if (!bdops->media_changed(bdev->bd_disk))
		return 0;

#if defined(CONFIG_SUPERMOUNT) || defined(CONFIG_SUPERMOUNT_MODULE)
	sb = get_super(bdev);
	if (sb) {
		atomic_set(&sb->s_media_changed, 1);
		supermounted = sb->s_flags & MS_SUPERMOUNTED;
		drop_super(sb);
	}

	/*
	 * Supermount used to did invalidate_device followed by
	 * destroy_buffers. invalidate_device hardly does anything
	 * useful here as it won't really invalidate "busy" inodes
	 * and every inode in subfs is busy (at least one reference
	 * from superfs exists). So now it just flushes
	 * buffers so they do not accidentally overwrite newly
	 * inserted media
	 *
	 * FIXME unfortunately during umount VFS may write on its
	 * own, like write_super. Those writes will go to a wrong
	 * media thus corrupting it :(
	 *
	 * There is no error print because supermount warns user
	 * itself.
	 */

	if (supermounted) {
		invalidate_bdev(bdev, 1);
	} else
#endif
	if (__invalidate_device(bdev, 0))
		printk("VFS: busy inodes on changed media.\n");


Lines 303-308 Link Here

(-)linux-2.6.8.1_supermount/fs/ext2/super.c (+6 lines)
303	{Opt_ignore, "noquota"},	303	{Opt_ignore, "noquota"},
304	{Opt_ignore, "quota"},	304	{Opt_ignore, "quota"},
305	{Opt_ignore, "usrquota"},	305	{Opt_ignore, "usrquota"},
		306	#if defined(CONFIG_SUPERMOUNT) \|\| defined(CONFIG_SUPERMOUNT_MODULE)
		307	/* Silently ignore NLS options */
		308	{Opt_ignore, "iocharset"},
		309	{Opt_ignore, "codepage"},
		310	{Opt_ignore, "umask"},
		311	#endif
306	{Opt_err, NULL}	312	{Opt_err, NULL}
307	};	313	};
308		314

Lines 364-369 Link Here

(-)linux-2.6.8.1_supermount/fs/isofs/inode.c (+4 lines)
364	{Opt_ignore, "conv=auto"},	364	{Opt_ignore, "conv=auto"},
365	{Opt_ignore, "conv=a"},	365	{Opt_ignore, "conv=a"},
366	{Opt_nocompress, "nocompress"},	366	{Opt_nocompress, "nocompress"},
		367	#if defined(CONFIG_SUPERMOUNT) \|\| defined(CONFIG_SUPERMOUNT_MODULE)
		368	{Opt_ignore, "codepage=%s"},
		369	{Opt_ignore, "umask=%s"},
		370	#endif
367	{Opt_err, NULL}	371	{Opt_err, NULL}
368	};	372	};
369		373

Lines 1016-1021 Link Here

(-)linux-2.6.8.1_supermount/fs/namespace.c (+9 lines)
1016	if (retval)	1016	if (retval)
1017	goto dput_out;	1017	goto dput_out;
1018		1018
		1019	#if defined(CONFIG_SUPERMOUNT) \|\| defined(CONFIG_SUPERMOUNT_MODULE)
		1020	if (!(flags & (MS_REMOUNT \| MS_MOVE)) &&
		1021	(nd.mnt->mnt_sb->s_type->fs_flags & FS_NO_SUBMNT)) {
		1022	retval = -EPERM;
		1023	path_release(&nd);
		1024	return retval;
		1025	}
		1026	#endif
		1027
1019	if (flags & MS_REMOUNT)	1028	if (flags & MS_REMOUNT)
1020	retval = do_remount(&nd, flags & ~MS_REMOUNT, mnt_flags,	1029	retval = do_remount(&nd, flags & ~MS_REMOUNT, mnt_flags,
1021	data_page);	1030	data_page);

Lines 82-87 Link Here

(-)linux-2.6.8.1_supermount/fs/super.c (-2 / +29 lines)
82	s->dq_op = sb_dquot_ops;	82	s->dq_op = sb_dquot_ops;
83	s->s_qcop = sb_quotactl_ops;	83	s->s_qcop = sb_quotactl_ops;
84	s->s_op = &default_op;	84	s->s_op = &default_op;
		85	#if defined(CONFIG_SUPERMOUNT) \|\| defined(CONFIG_SUPERMOUNT_MODULE)
		86	atomic_set(&s->s_media_changed, 0);
		87	#endif
85	}	88	}
86	out:	89	out:
87	return s;	90	return s;
Lines 527-532 Link Here
527	return 0;	530	return 0;
528	}	531	}
529		532
		533	#ifdef CONFIG_SUPERMOUNT_MODULE
		534	EXPORT_SYMBOL(do_remount_sb);
		535	#endif
		536
530	static void do_emergency_remount(unsigned long foo)	537	static void do_emergency_remount(unsigned long foo)
531	{	538	{
532	struct super_block *sb;	539	struct super_block *sb;
Lines 657-667 Link Here
657	goto out;	664	goto out;
658		665
659	if (s->s_root) {	666	if (s->s_root) {
660	if ((flags ^ s->s_flags) & MS_RDONLY) {	667	if (((flags ^ s->s_flags) & MS_RDONLY)
		668	#if defined(CONFIG_SUPERMOUNT) \|\| defined(CONFIG_SUPERMOUNT_MODULE)
		669	/* disallow double mounting for supermounted device */
		670	\|\| ((flags \| s->s_flags) & MS_SUPERMOUNTED)
		671	#endif
		672	)
		673	{
661	up_write(&s->s_umount);	674	up_write(&s->s_umount);
662	deactivate_super(s);	675	deactivate_super(s);
663	s = ERR_PTR(-EBUSY);	676	s = ERR_PTR(-EBUSY);
664	}	677	}
		678
665	goto out;	679	goto out;
666	} else {	680	} else {
667	char b[BDEVNAME_SIZE];	681	char b[BDEVNAME_SIZE];
Lines 765-770 Link Here
765	if (!type)	779	if (!type)
766	return ERR_PTR(-ENODEV);	780	return ERR_PTR(-ENODEV);
767		781
		782	#if defined(CONFIG_SUPERMOUNT) \|\| defined(CONFIG_SUPERMOUNT_MODULE)
		783	/* sanity checks; supermount relies on these assumptions */
		784	if (flags & MS_SUPERMOUNTED) {
		785	sb = ERR_PTR(-EINVAL);
		786	if (type->fs_flags & FS_ODD_RENAME)
		787	goto out;
		788	if (!(type->fs_flags & FS_REQUIRES_DEV))
		789	goto out;
		790	sb = ERR_PTR(-ENOMEM);
		791	}
		792	#endif
768	mnt = alloc_vfsmnt(name);	793	mnt = alloc_vfsmnt(name);
769	if (!mnt)	794	if (!mnt)
770	goto out;	795	goto out;
Lines 810-816 Link Here
810	return (struct vfsmount *)sb;	835	return (struct vfsmount *)sb;
811	}	836	}
812		837
813	EXPORT_SYMBOL_GPL(do_kern_mount);	838	#ifdef CONFIG_SUPERMOUNT_MODULE
		839	EXPORT_SYMBOL(do_kern_mount);
		840	#endif
814		841
815	struct vfsmount kern_mount(struct file_system_type type)	842	struct vfsmount kern_mount(struct file_system_type type)
816	{	843	{




config SUPERMOUNT
	tristate "Supermount removable media support"
	help
	  Supermount gives you the ability to access CD-ROMs and Floppies
	  without mounting/unmounting them every time you want to access
	  a different disk/floppy. Just eject the media, insert a new one
	  and you are able to access it.

	  Read Documentation/filesystems/supermount.txt for more information.

	  If you want to compile the Supermount support as a module ( = code
	  which can be inserted in and removed from the running kernel whenever
	  you want), say M here and read Documentation/modules.txt. The module
	  will be called supermount.o.

	  If unsure, say N.

config SUPERMOUNT_DEBUG
	bool "Enable supermount debug code"
	depends on SUPERMOUNT
	help
	  If you set this to Y, additional debug code will be compiled in.
	  Debug output is controlled with debug=N mount option. Possible
	  values are listed in Documentation/filesystems/supermount.txt.

	  If unsure, say Y.




#
# Makefile for the linux supermounting routines.
#

supermount-objs :=	dentry.o \
			file.o \
			filemap.o \
			init.o \
			mediactl.o \
			namei.o \
			proc.o \
			subfs.o \
			super.o 

obj-$(CONFIG_SUPERMOUNT) += supermount.o




* ? ? ? Andrey Borzenkov <arvidjaar@mail.ru> ?.?.?

* Sun 18 Jan 2004 Andrey Borzenkov <arvidjaar@mail.ru> 2.0.4

  - yet another attempt to fix detection of USB drive removale
    (explicitly check for SDVE_DEL state in sd.c:sd_media_changed)

  - fixed i18n patch for ext2 and udf (ignored options)

  - ->nopage prototype changed; it makes it incompatible with
    kernel < 2.6.1 (I wonder how it compiled - or did I miss
    warning). Add comments about ->populate and why it won't be
    implemented

  - fix "auto" option. Simplification of option processing turned
    out to be a mess :( Reported by Bart

* Mon 12 Jan 2004 Andrey Borzenkov <arvidjaar@mail.ru> 2.0.3b

  - Fix compilation problem in subfs.c with older GCC - declaration
    after statement in clear_inodes(bug 875009). Pointed by Adrian Punga.

* Wed 07 Jan 2004 Andrey Borzenkov <arvidjaar@mail.ru> 2.0.3a

  - fix Oops during options parsing if no subfs option is
    given after "--" (bug 869863)

* Mon 29 Dec 2003 Andrey Borzenkov <arvidjaar@mail.ru> 2.0.3

  - move test for device offline in sd.c to the top in attempt
    to fix USB removale problem

  - simplify options procesing

  - remove cdrom "open failed" message (it is now under
    CDROM_OPEN flag like all others in cdrom_open).

  - rewrote option parsing to use new lib/parse library

* Sun 26 Oct 2003 Andrey Borzenkov <arvidjaar@mail.ru> 2.0.2a

  - remove some obsolete files that are not used anymore from CVS
    (i.e. from patch)

  - isofs needs extra ignored options now. It rurns out it silently
    ignored any unknown option before new and shiny option parsing
    code

  - consistently use "kernel 2.6" in version print

  - updates for -test8. Change ext2/udf patches to match new options
    parsing code.

* Wed 10 Sep 2003 Andrey Borzenkov <arvidjaar@mail.ru> 2.0.2

  - NODEV is gone, use MKDEV(UNNAMED_MAJOR, 0) instead, it is just
    as good as anything else

* Sat 23 Aug 2003 Andrey Borzenkov <arvidjaar@mail.ru> 2.0.1d

  - rediff against 2.6.0-test4

* Mon 18 Aug 2003 Andrey Borzenkov <arvidjaar@mail.ru> 2.0.1c

  - fix compilation without CONFIG_SUPERMOUNT. Reported by
    Igor Strygin

* Sun 10 Aug 2003 Andrey Borzenkov <arvidjaar@mail.ru> 2.0.1b

  - /proc/fs/supermount/version is read-only, do not set permissions to
    rw

  - remove generic_unplug_queue from ide_do_drive_cmd, apparently
    it is redundant now (fixes bug 785691)

  - rediff for 2.6.0-test3

* Sun 27 Jul 2003 Andrey Borzenkov <arvidjaar@mail.ru> 2.0.1a

  - rediff for 2.6.0-test2

* Sun 13 Jul 2003 Andrey Borzenkov <arvidjaar@mail.ru> 2.0.1

  - hush most unused variables warnings with CONFIG_DEBUG (idea
    suggested by Jeff Garzik)

  - replace ugly SUPERMOUNT_TARCE_{ENTER,LEAVE}[_ARGS] with ENTER/LEAVE
    Use %p throughout for pointer output.

  - send DN_CREATE for root on mount

  - allow open and readdir on mountpoint even if subfs is unmounted.
    This provides for active monitoring by FAM/dnotify and is overall
    less surprising - ls /mnt/cdrom just returns empty directory now
    instead of error. For technical reasons ->flush and ->permissions
    need be aware about it too.

    Files opened while subfs is unmounted are NOT usable for anything
    except readdir even AFTER subfs gets mounted. So application
    has to reopen directory to rescan it. AFAIK all of them do it :)

* Sat 12 Jul 2003 Andrey Borzenkov <arvidjaar@mail.ru> 2.0.0a

  - add struct nameidata * goes into d_revalidate as well

  - add struct nameidata * to some inode methods (introduced in
    2.5.75). Currently it is just passed along - it is not clear if
    local subfs-specific nameidata has to be constructed. Apparently
    it existed in follow_link all the time without any evil done.

  - fix small races in supermount_getattr - do not attempt to
    get subdent if prevent_umount failed

* Mon 23 Jun 2003 Andrey Borzenkov <arvidjaar@mail.ru> 2.0.0

  - added ->getattr; it never fails on both unmounted mountpoint
    and stale open files - to ensure fuser -m /mnt/cdrom still finds them

  - merge 2.5.73; update sd.c to new refcount interface in sd.c

  - fix SUPERMOUNT_BUG_ON_LOCKED without SUPERMOUNT_DEBUG

  - add media management to ide-floppy and those CD-ROM drivers that
    are using standard cdrom_* calls (cdu31a, cm206, mcd, mcdx, sbpcd).
    Testdrive revealed that none of them builds for other reasons :)

  - add (un)mark_media_supermounted; mark after mount, unmark
    before umount. These functions just manipulate bd_disk->scount

  - add scount to struct gendisk to serve as count of total
    supermounted partitions; use everywhere to check if device
    is supermounted

* Tue 17 Jun 2003 Andrey Borzenkov <arvidjaar@mail.ru> 2.0.0test2

  - update kernel patch for 2.5.72 (there was a reject in
    drivers/ide/ide-io.c)

  - move init_inode_info into alloc_inode; use iget_locked
    instead of iget to skip ->read_inode with intent to move
    inode init under if (inode->i_state & I_NEW)

  - polish dentry.c a bit while I am on it

  - ->d_compare is not run under dcache_lock anymore. Pointed by
    Maneesh Soni. As we can't sleep in d_compare, use rwlock to
    protect against races with supermount_clean_dentries until
    I find better solution.

  - remove new_subfs_dentry - it is not used anymore and comments
    there were wrong anyway

* Sun 01 Jun 2003 Andrey Borzenkov <arvidjaar@mail.ru> 2.0.0test1

  - add sr and sd support

  - update sb s_blocksize and s_blocksize_bits on subfs mount

  - use BKL around chek_disk_change; it is not garanteed by VFS now

  - llseek no more updates file readahead pointer

  - used bdev not gendisk in mediactl - it needs it for
    supermount_usage_count. It probably needs redesign. Also some minor
    changes on the way.

  - 2.5 changes. supermount_get_sb, inode alloc/dealloc, use bdev instead
    of dev, Makefile change, add CONFIG_SUPERMOUNT_DEBUG, do_remount_sb
    prototype change, mknod prototype change, UPDATE_ATIME dead,
    dnotify_parent is now true function

* Tue 27 May 2003 Andrey Borzenkov <arvidjaar@mail.ru> 1.2.7

  - (re-)set root inode flags after unmounting subfs

  - fix mounting of ro media on rw filesystem. It was broken  by fix
    in 1.2.4. Remove saved s_mflags and just use real sb->s_flags.
    Reported by Con Kolivas
    
  - do not use MS_MGC_VAL in subfs_real_mount - it is not used anywhere
    in kernel and all lower bits are already taken in 2.5

  - configure help from Marc-Christian Petersen

  - use subsb->s_bdev instead of looking up using s_dev. This also
    fixes problem with O(1) patch (bug 737783)

* Wed 14 May 2003 Andrey Borzenkov <arvidjaar@mail.ru> 1.2.6

  - check for correct inode in attach_subfs_inode - if super inode
    has subinode attached it must be the same as is currently
    resuested. Else it is a bug.

  - use lookup_one_len to lookup subfs dentry in cache; check if
    subfs did not change name and lookup "real" dentry in parent
    cache in this case. This finally puts an end to the attempt to
    control subfs dcache. The only thing we rely upon now is that
    nothing can change directory contents while in lookup method.

  - implement d_hash and d_compare to properly support case-
    insensitive filesystems (vfat & Co).
  
  - reset super inode i_mapping so it does not point to freed
    subinode mapping when unmounting subfs

  - send dnotify_parent on dentry cleanup, not on inode

  - use write_inode_now in ->write_inode. Reading intricated flags
    manipulations in fs/inode.c was just too intimidating. It is not as
    much overhead as it looks like - it is called from sync_one only
    so all dirty pages are scheduled to be flushed anyway.

* Sun 04 May 2003 Andrey Borzenkov <arvidjaar@mail.ru> 1.2.5

  - enable dentries caching; properly use d_add when dentry is first
    looked up and d_instantiate when inode is finally available.

  - first stab at sending notifications on media umount/mount

  - more caveats :(

* Sat 26 Apr 2003 Andrey Borzenkov <arvidjaar@mail.ru> 1.2.4

  - fix write_inode/prepare_inode deadlock. It looked like
  	set I_LOCK
			down(&sbi->sem);
			iget4 -> wait_on_inode
	down(&sbi->sem)

  - MS_ACTIVE was reset on subfs remount

  - print process PID in trace

  - adjust directory structure to make patch generation easier

* Sun 20 Apr 2003 Andrey Borzenkov <arvidjaar@mail.ru> 1.2.3

  - dummy version due to script problems

* Sun 20 Apr 2003 Andrey Borzenkov <arvidjaar@mail.ru> 1.2.2
  
  - remove #ifdef CONFIG_PROC_FS from init.c, it already exists in
    supermount.h

  - no_tray_lock -> TRAY_LOCK_NEVER. Just to make sure it remains
    compatible (even if it is very unlikely anybody is using it).

  - backout kernel stat patch; remove getattr alltogether. It fixed
    fuser -m for stale files. getattr remains uniplemented because
    it does not seem to be used anywhere in kernel at all so I am not
    actually sure how to implement it

    It also backouts 10_readlik and 30_lseek as they are not used
    anymore for a long time.

  - remove bogus check for sub- and superinodes i_count. i_count is
    outside of supermount control; the only thing that we must be
    sure in - inode is free on umount.

  - reset root inode attributes and operations on umount. This fixes
    the problem of attempt to mount media on ls -l /mnt after subfs
    has been mounted once.

  - remove ->stale. For all practical purposes an entity is stale iff
    it does not (yet) have associated subfs entity. Creating yet another
    field that just mirrors this condition does not add a single bit
    of useful information.

  - subfs_is_busy iff subfs mnt_count > 1

* Sat 05 Apr 2003 Andrey Borzenkov <arvidjaar@mail.ru> 1.2.1

  - fixed stupid thinko in mediactl methods (the effect was it was
    impossible to manually eject ro media). It was exposed by recent
    changes. No changes in supermount itself only in driver code

  - replace no_tray_lock with tray_lock={never,onwrite,always} with
    "onwrite" being default. I stil do not quite like resulting code
    but it will do for now.

  - simplified subfs_(get|put)_(write|read) interface; merge both
    read/write in one function; remove subfs_get_atime. To my surprise
    it resulted on more clean interface in the rest of supermount even
    if subfs_(get|put)_access does look a bit weird.

* Sun 30 Mar 2003 Andrey Borzenkov <arvidjaar@mail.ru> 1.2.0

  - changed proc command format to
    <devname> [enable|disable] [release [force]]

  - add /proc/fs/supermount/version; printk version on starup only
    if procfs is not configured.

  - unify media lock rules for thosed drivers using implementing
    mediactl (cdrom, sd, ide-floppy as of this writing). Lock
    media for both manual and software eject; do not unlock media
    that is in used by something else.

  - added show_options method to super.c

  - implemented /proc/fs/supermount/subfs read as seq_file

* Sat 29 Mar 2003 Andrey Borzenkov <arvidjaar@mail.ru> 1.1.4

  - supermount_rename leftover - it does not need new_subfs_dentry.
    It still worked because new dentry was destroyed immediately, but
    let's do it the right way. Also mark target rw if exists

  - propagate S_IMMUTABLE, S_NOATIME and S_APPEND flags from subfs
    to super inode. Filesystems usually rely on VFS to check these
    flags which means it was possible to overwrite immutable file. Also
    needed for atime management (to be added).

  - added atime management. It is based on grep UPDATE_ATIME so it may
    be incomplete; still it gives right results in most obvious cases :)
    It respects no(dir)atime mount flag.

  - Make sure super inode times and sizes are updated to reflect subfs
    inode. Done in preparation to remove stat kernel patch. Only those
    fields needed by stat are updated.

  - remove assertion subi->i_count == 1 from clear_inode. Subfs icache
    is managed independently and there is no lock (as opposed to dentry
    case where we never do cached lookup for subfs).

  - use inode cache for supermount inodes to avoid linear search. This
    moves almost the whole inode creation task into read_inode2 - the
    only place where inode needs to be created is root inode.

    We use inode numbers from subfs; root inode is never cached until
    subfs has been mounted. Stale inodes are removed from cache in
    clean_inodes (just like dentries are in clean_dentries) so aliasing
    problem is solved.

  - add "disabled" state - prevent any attempt to mount media

  - add procfs support. Reading /proc/fs/supermount/subfs will return
    list of subfs and their status. Writing into it allows you to
    control status of subfs (mounted/unmounted, enabled/dusabled)

  - fix race in clear_inode. It was possible that subfs was umounted
    after inode has been removed from list but before its access
    counters were cleared. The code that checkes for that exists only
    for debugging still I'd like it to be useful.

* Sun 16 Mar 2003 Andrey Borzenkov <arvidjaar@mail.ru> 1.1.3

  - add CVS verion Id's to files

  - finally get rid of ugly generation number. It is enough to just
    mark entity obsolete; we do not care actually when it happened.
    Now every entity starts out stale; stale flag is reset when subfs
    object is attached; stale flag is set again for the rest of life
    in subfs_umount

  - as a side effect read/write count is associated with inodes
    exclusively

  - clear_inode and d_iput need prevent/allow umount to avoid "stealing"
    subfs while holding active entities. File release is safe as VFS does
    nou put mnt until _release is finished.

  - subfs_prevent_umount does not need validator. The worst thing that
    can happen is that newly mounted subfs is accessed. That does not
    matter, access to subfs object is checked for validity separately in
    every case.

  - finally clarify dcache management. As we cannot garantee coherency
    between sub- and super- fs caches we ignore subfs cache entirely.
    Super dentry is instantiated in supermount_lookup and passed around
    with subfs dentry attached. It does not matter if it is positive or
    negative. Currently dentries are forced to be deleted in
    supermount_d_delete but I believe it is not really needed.

  - print version number on registering filesystem to facilitate debugging

  - umount subfs as soon as possible in check_disk_change. This eliminates
    zombie state (mounted but inactive due to media change detected).

  - kill subfs_is_active, it is the same as subfs_is_mounted now.

  - kill translations.c it does not do anything special now; move functions
    in file/dentry/namei

  - fix stupid bug in get_supermount_inode again - super inode must
    be inited and attached just once not every time.
    Praise assertions again :)

* 10 Mar 2003 Andrey Borzenkov <arvidjaar@mail.ru> 1.1.2

  - allow fs=type1:type2:...

  - remove supermount_drop_dentries (no more used)

  - add some more assertions to subfs_umount

* 10 Mar 2003 Andrey Borzenkov <arvidjaar@mail.ru> 1.1.1

  - fix stupid bug in subfs inode refcounting. It was visible with
    hardlinks only so CD-ROM users would not ever see it.

  - fix even more stupid bug in unlink - subi was used instead of superi

* 8 Mar 2003 Andrey Borzenkov <arvidjaar@mail.ru> 1.1.0

  - files cannot use inode obsolete flag - it does not work for
    root inodes

  - make file system structure exact mirror of subfs - now there
    is 1-to-1 correspondence between super- and subfs files, dentries
    and inodes. This is needed to properly manage write access without
    too much locking

  - finally realized that subfs cannot be obsolete; use either file
    or inode pointer in all calls into subfs.c to check for freshness

  - debug is now per-mount; added trace of all functions
  
  - move setting of SUPERMOUNT_DEBUG to Makefile instead of supermount_i.h

* 1 Mar 2003 Andrey Borzenkov <arvidjaar@mail.ru> 1.0.0

  - make sure it is always possible umount subfs. It does it by
    keeping list of opened files (in addition to inodes) and closing
    them if media change is detected.

  - make sure subfs can't go away while it is being in use. For
    files it get_file for subfile to ensure subfs mnt is not freed. For
    inode operation it increments usage counter of submnt for duration
    of operation.

  - make sure supermounted device can't be mounted twice (that is
    allowed by kernel) because it relies on being the only "owner" of
    subfs. It does it by checking for MS_SUPERMOUNTED flag on mount.

  - make sure you can't mount over supermounted directory. Allowing
    it is a nightmare and I cannot see any reason for it (if you can
    provide valid one - I may reconsider this part). It does so by
    adding fstype flag and checking it on mounting.

  - reject mount -o remount for the time being (until we can deal
    with it properly)

  - completely change implementation of individual inode methods.
    Instead of calling VFS recursively it calls subfs methods directly.
    It is to ensure we are in full control of subfs (assuming it behaves
    properly :)

  - properly implement VM methods. Currently changing media would
    leave you with vm_area pointing to no more existing inode ...

  - remove many obsolete pieces like flags that just duplicate
    existing information.

  - ensure coherency between super- and subfs dentries. Either we
    have both active in dcache or do not have them at all.

  - fixe the problem with media ejection after direct access to CD-ROM

  - add "just disc change" to all operations to detect media change
    as soon as possible. It is possible to add option to do it just
    for writable media or to completely turn it off.




/*
 *  linux/fs/supermount/dentry.c
 *
 *  Original version:
 *      Copyright (C) 1995
 *      Stephen Tweedie (sct@dcs.ed.ac.uk)
 *
 *  Rewriten for kernel 2.2 & 2.4. (C) 1999, 2000 Alexis Mikhailov
 *                                    (alexis@abc.cap.ru)
 *  Rewritten for kernel 2.4.21 (C) 2003 Andrey Borzenkov
 *                                       (arvidjaar@mail.ru)
 *  Rewritten for kernel 2.5.70 (C) 2003 Andrey Borzenkov
 *                                       (arvidjaar@mail.ru)
 *
 *  $Id: 4715_supermount-2.0.4-2.6.7.patch,v 1.1 2004/06/22 22:15:04 gregkh Exp $
 */

#define S_DBG_TRACE_CURRENT S_DBG_TRACE_DENTRY
#include "supermount.h"

int
init_dentry_info(struct dentry *dentry)
{
	struct super_block *sb = dentry->d_sb;
	struct supermount_dentry_info *sdi;
	int rc;

	ENTER(sb, "dentry=%s", dentry->d_name.name);

	rc = 1;
	sdi = kmalloc(sizeof(*sdi), GFP_KERNEL);
	if (!sdi)
		goto out;

	memset(sdi, 0, sizeof(*sdi));

	INIT_LIST_HEAD(&sdi->list);
	sdi->dentry = 0;
	sdi->host = dentry;
	
	dentry->d_fsdata = sdi;
	dentry->d_op = &supermount_dops;

	rc = 0;
out:
	LEAVE(sb, "dentry=%s rc=%d", dentry->d_name.name, rc);

	return rc;

}

void
attach_subfs_dentry(struct dentry *dentry, struct dentry *subdent)
{
	struct super_block *sb = dentry->d_sb;
	struct supermount_sb_info *sbi = supermount_sbi(sb);
	struct supermount_dentry_info *sdi;

	ENTER(sb, "dentry=%s subd=%p", dentry->d_name.name, subdent);

	sdi = supermount_d(dentry);
	SUPERMOUNT_BUG_LOCKED_ON(sb, sdi->dentry);
	sdi->dentry = dget(subdent);
	list_add(&sdi->list, &sbi->s_dentries);

	LEAVE(sb, "dentry=%s", dentry->d_name.name);
}


struct dentry *
get_subfs_dentry(struct dentry *dentry)
{
	struct super_block *sb = dentry->d_sb;
	struct dentry *err;
	struct supermount_dentry_info *sdi = supermount_d(dentry);

	ENTER(sb, "dentry=%s", dentry->d_name.name);

	subfs_lock(sb);

	err = ERR_PTR(-ENOMEDIUM);
	if (!subfs_is_mounted(sb))
		goto out;

	err = ERR_PTR(-ESTALE);
	if (is_dentry_obsolete(dentry))
		goto out;

	err = dget(sdi->dentry);
	SUPERMOUNT_BUG_LOCKED_ON(sb, !err);
	SUPERMOUNT_BUG_LOCKED_ON(sb, (dentry->d_inode == 0) ^ (err->d_inode == 0));

out:
	subfs_unlock(sb);

	LEAVE(sb, "dentry=%s subd=%p", dentry->d_name.name, err);

	return err;
}

static int
supermount_d_revalidate(struct dentry *dentry, struct nameidata *nd)
{
	struct super_block *sb = dentry->d_sb;
	struct dentry *subd;
	int rc;
	struct vfsmount *mnt;

	ENTER(sb, "dentry=%s", dentry->d_name.name);

	rc = 0;
	mnt = subfs_prevent_umount(sb);
	if (!mnt)
		goto out;
	
	subd = get_subfs_dentry(dentry);

	if (IS_ERR(subd))
		goto allow_umount;

	rc = 1;
	/* FIXME do we need to build proper subfs nd? */
	if (subd->d_op && subd->d_op->d_revalidate)
		rc = subd->d_op->d_revalidate(subd, nd);

	dput(subd);
allow_umount:
	subfs_allow_umount(sb, mnt);
out:

	LEAVE(sb, "dentry=%s rc=%d", dentry->d_name.name, rc);

	return rc;
}

static int
supermount_d_hash(struct dentry *dentry, struct qstr *name)
{
	struct super_block *sb = dentry->d_sb;
	struct dentry *subd;
	int rc;
	struct vfsmount *mnt;

	ENTER(sb, "dentry=%s name=%s", dentry->d_name.name, name->name);

	rc = -ENOMEDIUM;
	mnt = subfs_prevent_umount(sb);
	if (!mnt)
		goto out;
	
	subd = get_subfs_dentry(dentry);
	rc = PTR_ERR(subd);
	if (IS_ERR(subd))
		goto allow_umount;

	rc = 0;
	if (subd->d_op && subd->d_op && subd->d_op->d_hash)
		rc = subd->d_op->d_hash(subd, name);

	dput(subd);
allow_umount:
	subfs_allow_umount(sb, mnt);
out:
	LEAVE(sb, "dentry=%s rc=%d", dentry->d_name.name, rc);

	return rc;
}


rwlock_t d_compare_lock = RW_LOCK_UNLOCKED;

static int
supermount_d_compare(struct dentry *dentry, struct qstr *name1, struct qstr *name2)
{
	struct super_block *sb = dentry->d_sb;
	struct supermount_dentry_info *sdi;
	struct dentry *subd;
	int rc;

	ENTER(sb, "dentry=%s name1=%s name2=%s", dentry->d_name.name, name1->name, name2->name);

	rc = 1; /* fail by default */
	sdi = dentry->d_fsdata;
	SUPERMOUNT_BUG_ON(!sdi);

	/*
	 * HACK - FIXME
	 * this protects against races with supermount_clean_dentries
	 * I cannot use blocking calls (i.e. sbi->sem) here and it is not
	 * protected by dcache_lock anymore
	 */
	read_lock(&d_compare_lock);
	subd = sdi->dentry;
	if (!subd) {
		read_unlock(&d_compare_lock);
		goto out;
	}

	if (subd->d_op && subd->d_op->d_compare)
		rc = subd->d_op->d_compare(subd, name1, name2);
	else { /* based on fs/dcache.c:d_lookup */
		if (name1->len == name2->len)
		     rc = memcmp(name1->name, name2->name, name1->len);
	}
	read_unlock(&d_compare_lock);

out:
	LEAVE(sb, "dentry=%s rc=%d", dentry->d_name.name, rc);
	return rc;
}

static inline void
handle_subdent(struct dentry *dentry)
{
	struct super_block *sb = dentry->d_sb;
	struct vfsmount *mnt;
	struct supermount_dentry_info *sdi = supermount_d(dentry);
	struct dentry *subd = 0;

	mnt = subfs_prevent_umount(sb);
	if (!mnt)
		goto out;

	subfs_lock(sb);
	if (sdi) {
		subd = sdi->dentry;
		list_del_init(&sdi->list);
		sdi->dentry = 0;
	}
	subfs_unlock(sb);

	if (subd)
		dput(subd);

	subfs_allow_umount(sb, mnt);
out:
	return;
}

/*
 * in case of active dentry we must be sure subfs dentry is released
 * before subfs inode to correctly maintain write state
 */
static void
supermount_d_iput(struct dentry *dentry, struct inode *inode)
{
	struct super_block *sb = dentry->d_sb;

	ENTER(sb, "dentry=%s inode=%p", dentry->d_name.name, inode);

	handle_subdent(dentry);
	iput(inode);

	LEAVE(sb, "dentry=%s", dentry->d_name.name);
}
	

/*
 * this duplicated code is due to the lack of common "destroy" method
 * for both negative and positive dentries
 */
static void
supermount_d_release(struct dentry *dentry)
{
	struct super_block *sb = dentry->d_sb;
	struct supermount_dentry_info *sdi = supermount_d(dentry);

	ENTER(sb, "dentry=%s", dentry->d_name.name);

	handle_subdent(dentry);
	kfree(sdi);

	LEAVE(sb, "dentry=%s", dentry->d_name.name);
}

struct dentry_operations supermount_dops = {
	.d_revalidate	= supermount_d_revalidate,
	.d_hash		= supermount_d_hash,
	.d_compare	= supermount_d_compare,
	.d_iput		= supermount_d_iput,
	.d_release	= supermount_d_release,
};




/*
 *  linux/fs/supermount/file.c
 *
 *  Original version:
 *      Copyright (C) 1995, 1997
 *      Stephen Tweedie (sct@dcs.ed.ac.uk)
 *
 *      from
 *
 *      linux/fs/minix/dir.c
 *      Copyright (C) 1991, 1992  Linus Torvalds
 *
 *      and
 *
 *      linux/fs/ext2/dir.c
 *      Copyright (C) 1992, 1993, 1994, 1995  Remy Card
 *
 *  Rewriten for kernel 2.2 & 2.4. (C) 1999, 2000 Alexis Mikhailov
 *                                    (alexis@abc.cap.ru)
 *  Rewriten for kernel 2.4. (C) 2001 MandrakeSoft Inc.
 *                                    Juan Quintela (quintela@mandrakesoft.com)
 *  Rewritten for kernel 2.4.21 (C) 2003 Andrey Borzenkov
 *                                       (arvidjaar@mail.ru)
 *  Rewritten for kernel 2.5.70 (C) 2003 Andrey Borzenkov
 *                                       (arvidjaar@mail.ru)
 *
 *  $Id: 4715_supermount-2.0.4-2.6.7.patch,v 1.1 2004/06/22 22:15:04 gregkh Exp $
 */

#define S_DBG_TRACE_CURRENT S_DBG_TRACE_FILE
#include "supermount.h"

#define DEFAULT_POLLMASK (POLLIN | POLLOUT | POLLRDNORM | POLLWRNORM)

static inline int
init_file_info(struct file *file, unsigned int fake)
{
	struct super_block *sb = file->f_dentry->d_sb;
	struct supermount_file_info *sfi;
	int rc;

	ENTER(sb, "file=%p fake=%d", file, fake);

	rc = 1;
	sfi = kmalloc(sizeof(*sfi), GFP_KERNEL);
	if (!sfi)
		goto out;

	memset(sfi, 0, sizeof(*sfi));

	INIT_LIST_HEAD(&sfi->list);
	sfi->host = file;
	sfi->owner = current->pid;
	sfi->vm_ops = 0;
	sfi->file = 0;
	sfi->fake = fake;
	
	file->f_supermount = sfi;

	rc = 0;
out:
	LEAVE(sb, "file=%p fake=%d rc=%d", file, fake, rc);

	return rc;
}

static inline void
attach_subfs_file(struct file *file, struct file *subfile)
{
	struct super_block *sb = file->f_dentry->d_sb;
	struct supermount_sb_info *sbi = supermount_sbi(sb);
	struct supermount_file_info *sfi;

	ENTER(sb, "file=%p subfile=%p", file, subfile);

	sfi = supermount_f(file);
	sfi->file = subfile;
	list_add(&sfi->list, &sbi->s_files);

	LEAVE(sb, "file=%p subfile=%p", file, subfile);
}

static inline int
prepare_file(struct file *file, struct file *subfile)
{
	struct super_block *sb = file->f_dentry->d_sb;
	int rc;

	ENTER(sb, "file=%p subfile=%p", file, subfile);

	subfs_lock(sb);

	rc = -ENOMEDIUM;
	if (!subfs_is_mounted(sb))
		goto out;

	rc = -ESTALE;
	if (is_dentry_obsolete(file->f_dentry))
		goto out;

	rc = -ENOMEM;
	if (init_file_info(file, 0))
		goto out;

	attach_subfs_file(file, subfile);
	rc = 0;

out:
	subfs_unlock(sb);

	LEAVE(sb, "file=%p subfile=%p", file, subfile);

	return rc;
}

struct file *
get_subfs_file(struct file *file)
{
	struct super_block *sb = file->f_dentry->d_sb;
	struct supermount_file_info *sfi = supermount_f(file);
	struct file *err;

	ENTER(sb, "file=%p", file);

	subfs_lock(sb);
	
	err = ERR_PTR(-ENOMEDIUM);
	if (!subfs_is_mounted(sb))
		goto out;

	err = ERR_PTR(-ESTALE);
	if (is_file_fake(file) || is_file_obsolete(file))
		goto out;

	err = sfi->file;
	SUPERMOUNT_BUG_LOCKED_ON(sb, !err->f_dentry);
	SUPERMOUNT_BUG_LOCKED_ON(sb, !err->f_dentry->d_inode);
	get_file(err);

out:
	subfs_unlock(sb);

	LEAVE(sb, "file=%p subfile=%p", file, err);

	return err;
}

static loff_t
supermount_llseek(struct file *file, loff_t offset, int origin)
{
	struct super_block *sb = file->f_dentry->d_sb;
	struct file *subfile;
	loff_t rc;

	ENTER(sb, "file=%p offset=%lld origin=%d", file, offset, origin);

	rc = -ESTALE;
	if (subfs_check_disk_change(sb))
		goto out;

	subfile = get_subfs_file(file);
	rc = PTR_ERR(subfile);
	if (IS_ERR(subfile))
		goto out;

	if (subfile->f_op && subfile->f_op->llseek)
		rc = subfile->f_op->llseek(subfile, offset, origin);
	else
		rc = default_llseek(subfile, offset, origin);
	file->f_pos = subfile->f_pos;
	file->f_version = subfile->f_version;

	fput(subfile);
out:
	LEAVE(sb, "file=%p rc=%lld", file, rc);

	return rc;
}

static ssize_t
supermount_read(struct file *file, char *buf, size_t count, loff_t * ppos)
{
	struct super_block *sb = file->f_dentry->d_sb;
	struct inode *inode = file->f_dentry->d_inode;
	struct file *subfile;
	int write_on = NEED_WRITE_ATIME(inode);
	int rc;

	ENTER(sb, "file=%p", file);

	rc = -ESTALE;
	if (subfs_check_disk_change(sb))
		goto out;

	subfile = get_subfs_file(file);
	rc = PTR_ERR(subfile);
	if (IS_ERR(subfile))
		goto out;

	rc = -EINVAL;
	if (!subfile->f_op || !subfile->f_op->read)
		goto put_subfile;

	rc = subfs_get_access(inode, write_on);
	if (rc)
		goto put_subfile;

	rc = subfile->f_op->read(subfile, buf, count, ppos);
	subfs_put_access(inode, write_on);
	if (rc < 0)
		goto put_subfile;

	inode->i_atime = subfile->f_dentry->d_inode->i_atime;

	if (rc > 0)
		file->f_pos = subfile->f_pos = *ppos;

put_subfile:
	fput(subfile);
out:
	LEAVE(sb, "file=%p rc=%d", file, rc);

	return rc;
}

static ssize_t
supermount_write(struct file *file, const char *buf,
		 size_t count, loff_t * ppos)
{
	struct super_block *sb = file->f_dentry->d_sb;
	struct file *subfile;
	int rc;

	ENTER(sb, "file=%p", file);

	rc = -ESTALE;
	if (subfs_check_disk_change(sb))
		goto out;

	subfile = get_subfs_file(file);
	rc = PTR_ERR(subfile);
	if (IS_ERR(subfile))
		goto out;

	rc = 0;
	if (subfile->f_op && subfile->f_op->write)
		rc = subfile->f_op->write(subfile, buf, count, ppos);
	if (rc > 0) {
		struct inode *subinode = subfile->f_dentry->d_inode;

		file->f_pos = subfile->f_pos = *ppos;
		file->f_mode = subfile->f_mode;
		file->f_dentry->d_inode->i_size = subinode->i_size;
		file->f_dentry->d_inode->i_blocks = subinode->i_blocks;
		file->f_dentry->d_inode->i_mode = subinode->i_mode;
		file->f_dentry->d_inode->i_ctime = subinode->i_ctime;
		file->f_dentry->d_inode->i_mtime = subinode->i_mtime;
	}

	fput(subfile);
out:
	LEAVE(sb, "file=%p rc=%d", file, rc);

	return rc;
}

int
supermount_readdir(struct file *file, void *buf, filldir_t fill_fn)
{
	struct super_block *sb = file->f_dentry->d_sb;
	struct inode *inode = file->f_dentry->d_inode;
	struct file *subfile;
	int write_on = NEED_WRITE_ATIME(inode);
	int fake_readdir = 1;
	int rc;

	ENTER(sb, "file=%p", file);

	rc = -ESTALE;
	if (subfs_check_disk_change(sb))
		goto out;

	subfile = get_subfs_file(file);
	rc = PTR_ERR(subfile);
	if (IS_ERR(subfile))
		goto out;

	rc = -ENOTDIR;
	if (!subfile->f_op || !subfile->f_op->readdir)
		goto put_subfile;

	rc = subfs_get_access(inode, write_on);
	if (rc)
		goto put_subfile;

	/* FIXME should it go before get_access? */
	fake_readdir = 0;
	rc = subfile->f_op->readdir(subfile, buf, fill_fn);
	subfs_put_access(inode, write_on);
	if (rc)
		goto put_subfile;

	inode->i_atime = subfile->f_dentry->d_inode->i_atime;
	file->f_pos = subfile->f_pos;

put_subfile:
	fput(subfile);
out:
	if (fake_readdir && is_file_fake(file)) {
		/* cf. supermount_open */
		rc = 0;
	}
	LEAVE(sb, "file=%p rc=%d fpos=%lld", file, rc, file->f_pos);

	return rc;
}

static unsigned int
supermount_poll(struct file *file, struct poll_table_struct *table)
{
	struct super_block *sb = file->f_dentry->d_sb;
	struct file *subfile;
	int rc;

	ENTER(sb, "file=%p", file);

	rc = -ESTALE;
	if (subfs_check_disk_change(sb))
		goto out;

	subfile = get_subfs_file(file);
	rc = PTR_ERR(subfile);
	if (IS_ERR(subfile))
		goto out;

	rc = DEFAULT_POLLMASK;
	if (subfile->f_op && subfile->f_op->poll)
		rc = subfile->f_op->poll(subfile, table);

	fput(subfile);
out:
	LEAVE(sb, "file=%p rc=%d", file, rc);

	return rc;
}

static int
supermount_ioctl(struct inode *inode, struct file *file,
		 unsigned int cmd, unsigned long arg)
{
	struct super_block *sb = file->f_dentry->d_sb;
	struct file *subfile;
	struct inode *subinode;
	int rc;

	ENTER(sb, "file=%p cmd=%u arg=%lu", file, cmd, arg);

	rc = -ESTALE;
	if (subfs_check_disk_change(sb))
		goto out;

	subfile = get_subfs_file(file);
	rc = PTR_ERR(subfile);
	if (IS_ERR(subfile))
		goto out;

	rc = -ENOTTY;
	subinode = subfile->f_dentry->d_inode;
	if (subfile->f_op && subfile->f_op->ioctl)
		rc = subfile->f_op->ioctl(subinode, subfile, cmd, arg);

	/* flags may have been changed by ioctl */
	if (!rc)
		set_inode_flags(file->f_dentry->d_inode, subinode);

	fput(subfile);
out:
	LEAVE(sb, "file=%p rc=%d", file, rc);

	return rc;
}

int
supermount_open(struct inode *inode, struct file *file)
{
	struct super_block *sb = inode->i_sb;
	struct dentry *subdent;
	struct file *subfile = 0;
	struct vfsmount *submnt;
	int write_on = file->f_mode & FMODE_WRITE;
	int fake_open = 1;
	int rc;

	ENTER(sb, "inode=%p file=%p", inode, file);

	rc = -ESTALE;
	if (subfs_check_disk_change(sb))
		goto out;

	submnt = subfs_get_mnt(sb);
	if (!submnt)
		goto out;

	subdent = get_subfs_dentry(file->f_dentry);
	rc = PTR_ERR(subdent);
	if (IS_ERR(subdent))
		goto put_submnt;
	
	rc = subfs_get_access(inode, write_on);
	if (rc)
		goto put_subdent;

	/*
	 * the following is used to simplify error processing. dentry_open
	 * automatically does mntput and dput in error case, this may result
	 * in subfs being destroyed
	 * We just make sure we need to do mntput exactly once here;
	 * additionally it guards against accidental remounting of subfs
	 * until we has cleaned up
	 */
	submnt = mntget(submnt);
	subdent = dget(subdent);

	subfile = dentry_open(subdent, submnt, file->f_flags);
	rc = PTR_ERR(subfile);
	if (IS_ERR(subfile))
		goto put_access;
	/*
	 * no need to do extra mntput and dput, it is done automatically in
	 * dentry_open on error
	 */

	rc = prepare_file(file, subfile);
	if (rc)
		goto put_subfile;

	subfile->f_mode = file->f_mode;
	/*
	 * this is needed for mmap to work. In current model vm_area
	 * is associated with superfile; we never explicitly call
	 * any vm method with subfile as pointer. But many drivers
	 * attach private structures to this field and mmap of special
	 * files on supermount fs won't work without it
	 */
	file->private_data = subfile->private_data;
	/*
	 * we have real subfile now, do not fake anything
	 */
	fake_open = 0;

	/*
	 * Now get rid of extra mntget and dget
	 */
	goto put_subdent;

	/*
	 * error cleanup
	 */

put_subfile:
	fput(subfile);
	subfile = 0;
put_access:
	subfs_put_access(inode, write_on);
put_subdent:
	dput(subdent);
put_submnt:
	mntput(submnt);
out:
	if (fake_open && inode == sb->s_root->d_inode) {
		/*
		 * always appear to succeed for root open. It allows active
		 * monitoring of mountpoint using FAM/dnotify and also is less
		 * surprising for other programs
		 */
		rc = init_file_info(file, 1);
		if (rc)
			rc = -ENOMEM;
	}
	LEAVE(sb, "inode=%p file=%p rc=%d subfile=0x%p", inode, file, rc, subfile);

	return rc;
}

static int
supermount_flush(struct file *file)
{
	struct super_block *sb = file->f_dentry->d_sb;
	struct file *subfile;
	int fake_flush = 1;
	int rc;

	ENTER(sb, "file=%p", file);

	rc = -ESTALE;
	if (subfs_check_disk_change(sb))
		goto out;

	subfile = get_subfs_file(file);
	rc = PTR_ERR(subfile);
	if (IS_ERR(subfile))
		goto out;

	rc = 0;
	fake_flush = 0;
	if (subfile->f_op && subfile->f_op->flush)
		rc = subfile->f_op->flush(subfile);

	fput(subfile);
out:
	if (fake_flush && is_file_fake(file)) {
		/* cf. supermount_open */
		rc = 0;
	}
	LEAVE(sb, "file=%p rc=%d fake=%d", file, rc, fake_flush);

	return rc;
}

/*
 * if subfile is NULL it has already been released in supermount_clean_files
 * together with adjusting open/write counters. Else we do it here.
 *
 * The reason is, it may be called long after media has been changed
 * and we definitely do not want this function to mess up the
 * new subfs state.
 */
static int
supermount_release(struct inode *inode, struct file *file)
{
	struct file *subfile = 0;
	struct super_block *sb = inode->i_sb;
	struct supermount_file_info *sfi = file->f_supermount;

	ENTER(sb, "inode=%p file=%p", inode, file);

	subfs_lock(sb);
	/*
	 * FIXME
	 * this sucks. But there does not seem to be any way
	 * to distinguish between ENOMEM on _open (legitimate
	 * case) and anything else (plain bug)
	 */
	if (sfi) {
		list_del(&sfi->list);
		subfile = sfi->file;
		sfi->file = 0;
	} else
		supermount_warning(sb, "no supermount file info attached");
	subfs_unlock(sb);

	if (subfile) {
		int bug = atomic_read(&subfile->f_count) != 1;
		fput(subfile);
		subfs_put_access(inode, file->f_mode & FMODE_WRITE);
		SUPERMOUNT_BUG_ON(bug);
	}

	if (sfi)
		kfree(sfi);

	LEAVE(sb, "inode=%p file=%p", inode, file);

	return 0;

}

static int
supermount_fsync(struct file *file, struct dentry *dentry, int datasync)
{
	struct super_block *sb = file->f_dentry->d_sb;
	struct file *subfile;
	int rc;

	ENTER(sb, "file=%p dentry=%s sync=%d", file, dentry->d_name.name, datasync);

	rc = -ESTALE;
	if (subfs_check_disk_change(sb))
		goto out;

	subfile = get_subfs_file(file);
	rc = PTR_ERR(subfile);
	if (IS_ERR(subfile))
		goto out;

	rc = -EINVAL;
	if (subfile->f_op && subfile->f_op->fsync)
		rc = subfile->f_op->fsync(subfile, subfile->f_dentry, datasync);

	fput(subfile);
out:
	ENTER(sb, "file=%p dentry=%s rc=%d", file, dentry->d_name.name, rc);

	return rc;
}

static int
supermount_fasync(int fd, struct file *file, int on)
{
	struct super_block *sb = file->f_dentry->d_sb;
	struct file *subfile;
	int rc;

	ENTER(sb, "fd=%d file=%p on=%d", fd, file, on);

	rc = -ESTALE;
	if (subfs_check_disk_change(sb))
		goto out;

	subfile = get_subfs_file(file);
	rc = PTR_ERR(subfile);
	if (IS_ERR(subfile))
		goto out;

	rc = -EINVAL;
	if (subfile->f_op && subfile->f_op->fasync)
		rc = subfile->f_op->fasync(fd, subfile, on);

	fput(subfile);
out:
	LEAVE(sb, "fd=%d file=%p rc=%d", fd, file, rc);

	return rc;
}

static int
supermount_lock(struct file *file, int cmd, struct file_lock *fl)
{
	struct super_block *sb = file->f_dentry->d_sb;
	struct file *subfile;
	int rc;

	ENTER(sb, "file=%p cmd=%d", file, cmd);

	rc = -ESTALE;
	if (subfs_check_disk_change(sb))
		goto out;

	subfile = get_subfs_file(file);
	rc = PTR_ERR(subfile);
	if (IS_ERR(subfile))
		goto out;

	rc = 0;
	if (subfile->f_op && subfile->f_op->lock)
		rc = subfile->f_op->lock(subfile, cmd, fl);
	else if (cmd == F_GETLK)
		posix_test_lock(file, fl);

	fput(subfile);
out:
	LEAVE(sb, "file=%p rc=%d", file, rc);

	return rc;
}

/* Fixme:
 * readv: easy, export churnk from vfs
 * writev: easy, export churnk from vfs
 * sendpage: only used for networking, not needed
 * get_unmmapped_area: only used for devices, not needed
 */

struct file_operations supermount_dir_operations = {
	.llseek		= supermount_llseek,
	.read		= supermount_read,
	.readdir	= supermount_readdir,
	.ioctl		= supermount_ioctl,
	.open		= supermount_open,
	.flush		= supermount_flush,
	.release	= supermount_release,
	.fsync		= supermount_fsync,
	.fasync		= supermount_fasync,
};

struct file_operations supermount_file_operations = {
	.llseek		= supermount_llseek,
	.read		= supermount_read,
	.write		= supermount_write,
	.poll		= supermount_poll,
	.ioctl		= supermount_ioctl,
	.mmap		= supermount_file_mmap, /* from filemap.c */
	.open		= supermount_open,
	.flush		= supermount_flush,
	.release	= supermount_release,
	.fsync		= supermount_fsync,
	.fasync		= supermount_fasync,
	.lock		= supermount_lock,
};




/*
 *  linux/fs/supermount/filemap.c
 *
 *  Initial version for kernel 2.4.21 (C) 2003 Andrey Borzenkov
 *                                             (arvidjaar@mail.ru)
 *
 *  $Id: 4715_supermount-2.0.4-2.6.7.patch,v 1.1 2004/06/22 22:15:04 gregkh Exp $
 */

#define S_DBG_TRACE_CURRENT S_DBG_TRACE_FILEMAP
#include "supermount.h"

/*
 * Some rationale and justification for this file
 *
 * We play dirty tricks with mm management for mmaped files on supermount.
 * Address space points to subinode but vm area is associated with superfile.
 * When media change is detected, subinode together with all associated
 * pages goes away as well (at least, I hope so ...) Now we must prevent
 * any attempt to access no more existing address space. To do so we save
 * original vm_ops in private field and replace them with vm_ops in this file.
 * They check if file is stale, if yes, they try to return sensible error.
 * There is some doubt about possibility to block here ... OTOH any write
 * lock on subfs is hold in context where no mm lock is expected.
 */
static void
supermount_vm_open(struct vm_area_struct *area)
{
	struct file *file = area->vm_file, *subfile;
	struct super_block *sb = file->f_dentry->d_sb;
	struct supermount_file_info *sfi;

	ENTER(sb, "vm=%p", area);

	if (subfs_check_disk_change(sb))
		goto out;

	subfile = get_subfs_file(file);
	if (IS_ERR(subfile))
		goto out;

	sfi = supermount_f(file);
	if (sfi->vm_ops && sfi->vm_ops->open)
		sfi->vm_ops->open(area);

	fput(subfile);
out:
	LEAVE(sb, "vm=%p", area);

	return;
}

static void
supermount_vm_close(struct vm_area_struct *area)
{
	struct file *file = area->vm_file, *subfile;
	struct super_block *sb = file->f_dentry->d_sb;
	struct supermount_file_info *sfi;

	ENTER(sb, "vm=%p", area);
	
	if (subfs_check_disk_change(sb))
		goto out;

	subfile = get_subfs_file(file);
	if (IS_ERR(subfile))
		goto out;

	sfi = supermount_f(file);
	if (sfi->vm_ops && sfi->vm_ops->close)
		sfi->vm_ops->close(area);

	fput(subfile);
out:
	LEAVE(sb, "vm=%p", area);

	return;
}

static struct page *
supermount_vm_nopage(struct vm_area_struct *area, unsigned long address, int *type)
{
	struct file *file = area->vm_file, *subfile;
	struct super_block *sb = file->f_dentry->d_sb;
	struct supermount_file_info *sfi;
	struct page *page = 0;

	ENTER(sb, "vm=%p addr=%lx", area, address);
	
	/*
	 * this is called with mm semaphore down read and pagetable
	 * spinlock released. So it _appears_ safe to sleep ...
	 */
	if (subfs_check_disk_change(sb))
		goto out;

	subfile = get_subfs_file(file);
	if (IS_ERR(subfile))
		goto out;

	sfi = supermount_f(file);
	page = sfi->vm_ops->nopage(area, address, type);

	fput(subfile);
out:
	LEAVE(sb, "vm=%p page=%p", area, page);

	return page;
}

int
supermount_file_mmap(struct file *file, struct vm_area_struct *vma)
{

	struct super_block *sb = file->f_dentry->d_sb;
	struct inode *inode = file->f_dentry->d_inode;
	struct supermount_file_info *sfi;
	struct file *subfile;
	int write_on = NEED_WRITE_ATIME(inode);
	int rc;

	ENTER(sb, "file=%p vm=%p", file, vma);
	
	rc = -ESTALE;
	if (subfs_check_disk_change(sb))
		goto out;

	subfile = get_subfs_file(file);
	rc = PTR_ERR(subfile);
	if (IS_ERR(subfile))
		goto out;

	sfi = supermount_f(file);

	rc = -ENODEV;
	if (!subfile->f_op || !subfile->f_op->mmap)
		goto put_subfile;

	rc = subfs_get_access(inode, write_on);
	if (rc)
		goto put_subfile;

	rc = subfile->f_op->mmap(subfile, vma);
	subfs_put_access(inode, write_on);
	if (rc)
		goto put_subfile;
	/*
	 * we cannot deal with anonymous mapping
	 */
	if (!vma->vm_ops || !vma->vm_ops->nopage) {
		rc = -ENOSYS;
		goto put_subfile;
	}

	/*
	 * now do the nasty trick
	 */
	sfi->vm_ops = vma->vm_ops;
	vma->vm_ops = &supermount_vm_ops;

put_subfile:
	fput(subfile);
out:
	LEAVE(sb, "file=%p vm=%p rc=%d", file, vma, rc);

	return rc;
}

/*
 * ->populate:	to properly implement it it should call do_no_page if
 *  		subfs does not provide its own ->populate. Unfortunately
 *  		populate gets different parameters. Translating them into
 *  		what ->nopage expects just does not worth it - currently
 *  		supermount is slow enough to bother about this imaginary
 *  		speed up even if it was possible (which probably is not
 *  		due to how locking is done; see mm/memory.c).
 */
struct  vm_operations_struct supermount_vm_ops = {
	.open		= supermount_vm_open,
	.close		= supermount_vm_close,
	.nopage		= supermount_vm_nopage,
};




/* 
 * linux/fs/supermount/init.c
 *
 *  (C) Copyright 2001-2002 Juan Quintela <quintela@mandrakesoft.com>
 *      Released unde GPL v2.
 *  Rewritten for kernel 2.4.21 (C) 2003 Andrey Borzenkov
 *                                       (arvidjaar@mail.ru)
 *  Rewritten for kernel 2.5.70 (C) 2003 Andrey Borzenkov
 *                                       (arvidjaar@mail.ru)
 *
 *  $Id: 4715_supermount-2.0.4-2.6.7.patch,v 1.1 2004/06/22 22:15:04 gregkh Exp $
 */

#include "supermount.h"

struct file_system_type supermount_fs_type = {
        .owner          = THIS_MODULE,
        .name           = "supermount",
        .get_sb         = supermount_get_sb,
        .kill_sb        = kill_anon_super,
        .fs_flags       = FS_NO_SUBMNT,
};

static int __init
init_supermount_fs(void)
{
	int rc = register_filesystem(&supermount_fs_type);
	
	if (!rc) {
		printk(KERN_INFO "Supermount version %s for kernel 2.6\n", SUPERMOUNT_VERSION);
		supermount_proc_register();
	}

	return rc;
}

static void __exit
exit_supermount_fs(void)
{
	supermount_proc_unregister();
	unregister_filesystem(&supermount_fs_type);
}

MODULE_AUTHOR("Stephen Tweedie, Alexis Mikhailov, Juan Quintela, Andrey Borzenkov and others");
MODULE_DESCRIPTION("Transparent removable media support");
MODULE_LICENSE("GPL");
module_init(init_supermount_fs);
module_exit(exit_supermount_fs);




/*
 *  linux/fs/supermount/mediactl.c
 *
 *  Original version:
 *      Copyright (C) 1995, 1997
 *      Stephen Tweedie (sct@dcs.ed.ac.uk)
 *
 *  Rewriten for kernel 2.2, 2.4. (C) 1999, 2000 Alexis Mikhailov
 *                                    (alexis@abc.cap.ru)
 *  Rewritten for kernel 2.4.21 (C) 2003 Andrey Borzenkov
 *                                       (arvidjaar@mail.ru)
 *  Rewritten for kernel 2.5.70 (C) 2003 Andrey Borzenkov
 *                                       (arvidjaar@mail.ru)
 *
 *  $Id: 4715_supermount-2.0.4-2.6.7.patch,v 1.1 2004/06/22 22:15:04 gregkh Exp $
 */

#define S_DBG_TRACE_CURRENT S_DBG_TRACE_MEDIACTL
#include "supermount.h"

/* 
 * Try to lock the drive door.  This is not guaranteed to work on all
 * hardware, but we try any tricks we know of anyway.  
 */
void
supermount_mediactl(struct super_block *sb, int operation, int opt)
{
	struct block_device *bdev;
	struct super_block *subsb;
	struct block_device_operations *fops = 0;

	if (!subfs_is_mounted(sb))
		return;

	subsb = subfs_sb(sb);
	bdev = subsb->s_bdev;
	if (!bdev->bd_disk)
		return;

	/* FIXME is it enough to use bd_sem here? */
	switch (operation) {
		case SUPERMOUNT_INC_COUNT:
			lock_kernel();
			SUPERMOUNT_BUG_ON(bdev->bd_disk->scount < 0);
			bdev->bd_disk->scount++;
			unlock_kernel();
			return;
		case SUPERMOUNT_DEC_COUNT:
			lock_kernel();
			SUPERMOUNT_BUG_ON(bdev->bd_disk->scount <= 0);
			bdev->bd_disk->scount--;
			unlock_kernel();
			return;
	}

	fops = bdev->bd_disk->fops;
	if (!fops || !fops->mediactl)
		return;
	/*
	 * tray is (un-)locked in open (BKL for bdev), release (BKL for bdev)
	 * and ioctl (BKL). We are in good company.
	 * This must be changed if block devices ever stop using BKL
	 * for open/release. Unfortunately, using just bdev->bd_sem is not
	 * enough due to ioctl.
	 */
	lock_kernel();
	fops->mediactl(bdev, operation, opt);
	unlock_kernel();
}




/*
 *  linux/fs/supermount/namei.c
 *
 *  Original version:
 *      Copyright (C) 1995
 *      Stephen Tweedie (sct@dcs.ed.ac.uk)
 *
 *      from
 *
 *      linux/fs/minix/namei.c
 *      Copyright (C) 1991, 1992  Linus Torvalds
 *
 *      and
 *
 *      linux/fs/ext2/namei.c
 *      Copyright (C) 1992, 1993, 1994, 1995  Remy Card
 *
 *  Rewriten for kernel 2.2 & 2.4. (C) 1999, 2000 Alexis Mikhailov
 *                                    (alexis@abc.cap.ru)
 *  Rewritten for kernel 2.4.21 (C) 2003 Andrey Borzenkov
 *                                       (arvidjaar@mail.ru)
 *  Rewritten for kernel 2.5.70 (C) 2003 Andrey Borzenkov
 *                                       (arvidjaar@mail.ru)
 *
 *  $Id: 4715_supermount-2.0.4-2.6.7.patch,v 1.1 2004/06/22 22:15:04 gregkh Exp $
 */

#define S_DBG_TRACE_CURRENT S_DBG_TRACE_NAMEI
#include "supermount.h"

/**
 * Attach super dentry to sub dentry 
 *
 * @dentry:	super dentry that is being created
 * @subd:	subfs dentry that just has been found
 *
 * It checks whether subfs is still valid using @dentry->d_parent;
 * new supermount_dentry_info is created and set to point to @subd.
 *
 * It is possible that @subd actually has different name (ntfs, vfat or
 * in general any case-insensitive filesystems). Search @dentry->d_parent
 * for a child matching == @subd->d_name. If found, discard @dentry and child
 * (after some validity checks) is returned. Check that child actually points
 * to @subd
 *
 * d_lookup relies on the fact that hash is properly initialized in
 * @subd->d_name and that superfs is using the same compare method as subfs.
 *
 * About ref counting. @subd is dput in supermount_lookup. I.e. in case of
 * error or if we find out it is already connected to superfs the excessive
 * counter gets decremented. @dentry is finally dput in caller of ->lookup
 * if ->lookup returns something != 0.
 */

static struct dentry *
prepare_dentry(struct dentry *dentry, struct dentry *subd)
{
	struct super_block *sb = dentry->d_sb;
	struct dentry *rc;

	ENTER(sb, "dentry=%s subd=%s", dentry->d_name.name, subd->d_name.name);

	subfs_lock(sb);

	SUPERMOUNT_BUG_LOCKED_ON(sb, !subd);
	SUPERMOUNT_BUG_LOCKED_ON(sb, dentry->d_fsdata);

	rc = ERR_PTR(-ENOMEDIUM);
	if (!subfs_is_mounted(sb))
		goto out;

	rc = ERR_PTR(-ESTALE);
	if (is_dentry_obsolete(dentry->d_parent))
		goto out;

	rc = d_lookup(dentry->d_parent, &subd->d_name);
	if (IS_ERR(rc))
		goto out;

	if (rc) {
		SUPERMOUNT_BUG_LOCKED_ON(sb, !rc->d_fsdata);
		SUPERMOUNT_BUG_LOCKED_ON(sb,
		((struct supermount_dentry_info *)rc->d_fsdata)->dentry != subd);
	} else {
		/*
		 * this is theoretically possible. We cannot garantee full
		 * coherency between subfs and superfs cache; i.e. entry
		 * may have been left in one cache but removed from another
		 */
		rc = ERR_PTR(-ENOMEM);
		if (init_dentry_info(dentry))
			goto out;
		attach_subfs_dentry(dentry, subd);
		d_add(dentry, 0);
		rc = 0;
	}

out:
	subfs_unlock(sb);

	LEAVE(sb, "dentry=%p subd=%p rc=%p", dentry, subd, rc);

	return rc;
	/*
	 * subdent is implicitly freed on return if we skip dget here
	 */
}


/**
 * Attach superfs inode to subfs inode 
 *
 * @dentry:	superfs dentry
 * @subd:	subfs dentry
 *
 * This is expected to be called only in cointext that requires
 * negative dentry.
 *
 * FIXME
 * Holding sbi->sem during iget4 creates deadlock with write_inode -
 * write_inode sets I_LOCK abd calls supermount_write_inode at the
 * same moment as iget4 sleeps waiting for I_LOCK to be cleared. So
 * it first acquires inode and then checks if subfs is still valid.
 */

static int
prepare_inode(struct dentry *dentry, struct dentry *subd)
{
	struct super_block *sb = dentry->d_sb;
	struct inode *inode = dentry->d_inode;
	struct inode *subi = subd->d_inode;
	int rc;

	ENTER(sb, "dentry=%s", dentry->d_name.name);

	SUPERMOUNT_BUG_ON(inode);
	SUPERMOUNT_BUG_ON(!subi);

	rc = -ENOMEM;
	inode = iget_locked(sb, subi->i_ino);
	if (!inode)
		goto out;
	else if (inode->i_state & I_NEW)
		unlock_new_inode(inode);

	rc = 0;

	subfs_lock(sb);
	if (!subfs_is_mounted(sb))
		rc = -ENOMEDIUM;
	else if (is_dentry_obsolete(dentry))
		rc = -ESTALE;
	else {
		attach_subfs_inode(inode, subi);
		d_instantiate(dentry, inode);
	}
	subfs_unlock(sb);

	if (rc)
		iput(inode);

out:
	LEAVE(sb, "dentry=%s inode=%p rc=%d", dentry->d_name.name, inode, rc);

	return rc;
}

struct inode *
get_subfs_inode(struct inode *inode)
{
	struct super_block *sb = inode->i_sb;
	struct inode *err;
	struct supermount_inode_info *sii = supermount_i(inode);

	ENTER(sb, "inode=%p", inode);

	subfs_lock(sb);

	err = ERR_PTR(-ENOMEDIUM);
	if (!subfs_is_mounted(sb))
		goto out;

	err = ERR_PTR(-ESTALE);
	if (is_inode_obsolete(inode))
		goto out;

	err = igrab(sii->inode);
	SUPERMOUNT_BUG_LOCKED_ON(sb, !err);

out:
	subfs_unlock(sb);

	LEAVE(sb, "inode=%p subi=%p", inode, err);

	return err;
}

/* inode methods */

static int
supermount_create(struct inode *dir, struct dentry *dentry, int mode, struct nameidata *nd)
{
	struct super_block *sb = dir->i_sb;
	struct dentry *subdent;
	struct inode *subdir;
	int rc;
	struct vfsmount *mnt;

	ENTER(sb, "dir=%p dentry=%s", dir, dentry->d_name.name);

	mnt = subfs_go_online(sb);
	rc = PTR_ERR(mnt);
	if (IS_ERR(mnt))
		goto out;

	subdir = get_subfs_inode(dir);
	rc = PTR_ERR(subdir);
	if (IS_ERR(subdir))
		goto go_offline;

	rc = -EACCES;
	if (!subdir->i_op || !subdir->i_op->create)
		goto put_subdir;
	
	subdent = get_subfs_dentry(dentry);
	rc = PTR_ERR(subdent);
	if (IS_ERR(subdent))
		goto put_subdir;

	rc = subfs_get_access(dir, 1);
	if (rc)
		goto put_subdent;

	/* FIXME build proper nd struct */
	rc = subdir->i_op->create(subdir, subdent, mode, nd);
	subfs_put_access(dir, 1);
	if (rc)
		goto put_subdent;

	rc = prepare_inode(dentry, subdent);
	if (rc)
		goto put_subdent;

	dir->i_mtime = subdir->i_mtime;
	dir->i_ctime = subdir->i_ctime;
	dir->i_nlink = subdir->i_nlink;
	dir->i_size = subdir->i_size;
	dir->i_blocks = subdir->i_blocks;

put_subdent:
	dput(subdent);
put_subdir:
	iput(subdir);
go_offline:
	subfs_go_offline(sb, mnt);
out:
	LEAVE(sb, "dir=%p dentry=%s rc=%d", dir, dentry->d_name.name, rc);

	return rc;
}

/**
 * Search directory for a matching name
 *
 * @dir:	directory that is being searched
 * @dentry:	name to search for (in dentry->d_name)
 *
 * This is (currently :) the only method where we do not call subfs
 * directly. The reason is coherency between subfs and superfs dentry
 * caches. It is impossible to ensure it without modifying the very
 * guts of fs/dcache.c; so we check cache before doing actual lookup.
 * lookup_one_len just avoids duplicating of code.
 *
 * Supermount is in exclusive control of subfs so it is garanteed that
 * dentry cannot magically appear in the middle of lookup.
 *
 * There are filesystems that support multiple forms of file name, like
 * case-insensitive or short-long names on NTFS. In this case cache lookup
 * fails but filesystem may return dentry for different name. In this case
 * we check if dentry with matching name exists in parent and reuse it.
 */
static struct dentry *
supermount_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd)
{
	struct super_block *sb = dir->i_sb;
	struct dentry *rc, *subdent, *subparent;
	struct inode *subdir;
	struct vfsmount *mnt;
	int ret;

	ENTER(sb, "dir=%p dentry=%s", dir, dentry->d_name.name);

	mnt = subfs_go_online(sb);
	rc = (struct dentry *)mnt;
	if (IS_ERR(mnt))
		goto out;

	subdir = get_subfs_inode(dir);
	rc = (struct dentry *)subdir;
	if (IS_ERR(subdir))
		goto go_offline;

	subparent = get_subfs_dentry(dentry->d_parent);
	rc = subparent;
	if (IS_ERR(subparent))
		goto put_subdir;

	ret = subfs_get_access(dir, 0);
	rc = ERR_PTR(ret);
	if (ret)
		goto put_subparent;

	SUPERMOUNT_BUG_ON(subparent->d_inode != subdir);

	/* FIXME usually lookup_one_len is called under i_sem */
	/* FIXME what to do with nd? */
	subdent = lookup_one_len(dentry->d_name.name, subparent,
				 dentry->d_name.len);

	subfs_put_access(dir, 0);
	rc = subdent;
	if (IS_ERR(rc))
		goto put_subparent;

	rc = prepare_dentry(dentry, subdent);
	if (IS_ERR(rc))
		goto put_subdent;

	if (!rc && subdent->d_inode) {
		ret = prepare_inode(dentry, subdent);
		if (ret < 0)
			rc = ERR_PTR(ret);
	}

put_subdent:
	dput(subdent);
put_subparent:
	dput(subparent);
put_subdir:
	iput(subdir);
go_offline:
	subfs_go_offline(sb, mnt);
out:
	LEAVE(sb, "dir=%p dentry=%s rc=%p", dir, dentry->d_name.name, rc);

	return rc;
}

static int
supermount_link(struct dentry *old_dentry, struct inode *dir,
		struct dentry *new_dentry)
{
	struct super_block *sb = dir->i_sb;
	struct dentry *old_subdent, *new_subdent;
	struct inode *subdir;
	int rc;
	struct vfsmount *mnt;

	ENTER(sb, "from=%s dir=%p to=%s", old_dentry->d_name.name, dir, new_dentry->d_name.name);

	SUPERMOUNT_BUG_ON(new_dentry->d_inode);

	mnt = subfs_go_online(sb);
	rc = PTR_ERR(mnt);
	if (IS_ERR(mnt))
		goto out;

	subdir = get_subfs_inode(dir);
	rc = PTR_ERR(subdir);
	if (IS_ERR(subdir))
		goto go_offline;

	rc = -EPERM;
	if (!subdir->i_op || !subdir->i_op->link)
		goto put_subdir;

	old_subdent = get_subfs_dentry(old_dentry);
	rc = PTR_ERR(old_subdent);
	if (IS_ERR(old_subdent))
		goto put_subdir;

	new_subdent = get_subfs_dentry(new_dentry);
	rc = PTR_ERR(new_subdent);
	if (IS_ERR(new_subdent))
		goto put_old_subdent;

	rc = subfs_get_access(dir, 1);
	if (rc)
		goto put_new_subdent;

	rc = subdir->i_op->link(old_subdent, subdir, new_subdent);
	subfs_put_access(dir, 1);
	if (rc)
		goto put_new_subdent;

	rc = prepare_inode(new_dentry, new_subdent);
	if (rc)
		goto put_new_subdent;

	dir->i_mtime = subdir->i_mtime;
	dir->i_ctime = subdir->i_ctime;
	dir->i_nlink = subdir->i_nlink;
	dir->i_size = subdir->i_size;
	dir->i_blocks = subdir->i_blocks;

put_new_subdent:
	dput(new_subdent);
put_old_subdent:
	dput(old_subdent);
put_subdir:
	iput(subdir);
go_offline:
	subfs_go_offline(sb, mnt);
out:
	LEAVE(sb, "from=%s dir=%p to=%s rc=%d", old_dentry->d_name.name, dir, new_dentry->d_name.name, rc);

	return rc;
}

static int
supermount_unlink(struct inode *dir, struct dentry *dentry)
{
	struct super_block *sb = dir->i_sb;
	struct dentry *subdent;
	struct inode *subdir;
	int rc;
	struct vfsmount *mnt;

	ENTER(sb, "dir=%p dentry=%s", dir, dentry->d_name.name);

	mnt = subfs_go_online(sb);
	rc = PTR_ERR(mnt);
	if (IS_ERR(mnt))
		goto out;

	subdir = get_subfs_inode(dir);
	rc = PTR_ERR(subdir);
	if (IS_ERR(subdir))
		goto go_offline;

	rc = -EPERM;
	if (!subdir->i_op || !subdir->i_op->unlink)
		goto put_subdir;

	subdent = get_subfs_dentry(dentry);
	rc = PTR_ERR(subdent);
	if (IS_ERR(subdent))
		goto put_subdir;

	/*
	 * below is not a typo. We have to mark _deleted_ inode
	 * for possible later delete in clear_inode
	 */
	rc = subfs_get_access(dentry->d_inode, 1);
	if (rc)
		goto put_subdent;

	rc = subdir->i_op->unlink(subdir, subdent);
	if (rc)
		goto put_write_access;

	dir->i_mtime = subdir->i_mtime;
	dir->i_ctime = subdir->i_ctime;
	dir->i_nlink = subdir->i_nlink;
	dir->i_size = subdir->i_size;
	dir->i_blocks = subdir->i_blocks;

	dentry->d_inode->i_nlink = subdent->d_inode->i_nlink;
	dentry->d_inode->i_ctime = subdent->d_inode->i_ctime;

put_write_access:
	/*
	 * we can't put write access if there are pending deletes
	 * so we leave it on and let it be put in clear_inode for
	 * i_nlink == 0
	 *
	 * While i_nlink is believed to be atomic here i_count not,
	 * so we cannot check && i_count == 0. It is expected that
	 * deleted files are kept open only rarely.
	 */
	if (dentry->d_inode->i_nlink)
		subfs_put_access(dentry->d_inode, 1);
put_subdent:
	dput(subdent);
put_subdir:
	iput(subdir);
go_offline:
	subfs_go_offline(sb, mnt);
out:
	LEAVE(sb, "dir=%p dentry=%s rc=%d", dir, dentry->d_name.name, rc);

	return rc;
}

static int
supermount_symlink(struct inode *dir, struct dentry *dentry,
		   const char *symname)
{
	struct super_block *sb = dir->i_sb;
	struct dentry *subdent;
	struct inode *subdir;
	int rc;
	struct vfsmount *mnt;

	ENTER(sb, "dir=%p dentry=%s", dir, dentry->d_name.name);

	mnt = subfs_go_online(sb);
	rc = PTR_ERR(mnt);
	if (IS_ERR(mnt))
		goto out;

	subdir = get_subfs_inode(dir);
	rc = PTR_ERR(subdir);
	if (IS_ERR(subdir))
		goto go_offline;

	rc = -EPERM;
	if (!subdir->i_op || !subdir->i_op->symlink)
		goto put_subdir;

	subdent = get_subfs_dentry(dentry);
	rc = PTR_ERR(subdent);
	if (IS_ERR(subdent))
		goto put_subdir;

	rc = subfs_get_access(dir, 1);
	if (rc)
		goto put_subdent;

	rc = subdir->i_op->symlink(subdir, subdent, symname);
	subfs_put_access(dir, 1);
	if (rc)
		goto put_subdent;

	rc = prepare_inode(dentry, subdent);
	if (rc)
		goto put_subdent;

	dir->i_mtime = subdir->i_mtime;
	dir->i_ctime = subdir->i_ctime;
	dir->i_nlink = subdir->i_nlink;
	dir->i_size = subdir->i_size;
	dir->i_blocks = subdir->i_blocks;

put_subdent:
	dput(subdent);
put_subdir:
	iput(subdir);
go_offline:
	subfs_go_offline(sb, mnt);
out:
	LEAVE(sb, "dir=%p dentry=%s rc=%d", dir, dentry->d_name.name, rc);

	return rc;
}

static int
supermount_mkdir(struct inode *dir, struct dentry *dentry, int mode)
{
	struct super_block *sb = dir->i_sb;
	struct dentry *subdent;
	struct inode *subdir;
	int rc;
	struct vfsmount *mnt;

	ENTER(sb, "dir=%p dentry=%s", dir, dentry->d_name.name);

	mnt = subfs_go_online(sb);
	rc = PTR_ERR(mnt);
	if (IS_ERR(mnt))
		goto out;

	subdir = get_subfs_inode(dir);
	rc = PTR_ERR(subdir);
	if (IS_ERR(subdir))
		goto go_offline;

	rc = -EPERM;
	if (!subdir->i_op || !subdir->i_op->mkdir)
		goto put_subdir;

	subdent = get_subfs_dentry(dentry);
	rc = PTR_ERR(subdent);
	if (IS_ERR(subdent))
		goto put_subdir;

	rc = subfs_get_access(dir, 1);
	if (rc)
		goto put_subdent;

	rc = subdir->i_op->mkdir(subdir, subdent, mode);
	subfs_put_access(dir, 1);
	if (rc)
		goto put_subdent;

	rc = prepare_inode(dentry, subdent);
	if (rc)
		goto put_subdent;

	dir->i_mtime = subdir->i_mtime;
	dir->i_ctime = subdir->i_ctime;
	dir->i_nlink = subdir->i_nlink;
	dir->i_size = subdir->i_size;
	dir->i_blocks = subdir->i_blocks;

put_subdent:
	dput(subdent);
put_subdir:
	iput(subdir);
go_offline:
	subfs_go_offline(sb, mnt);
out:
	LEAVE(sb, "dir=%p dentry=%s rc=%d", dir, dentry->d_name.name, rc);

	return rc;
}

static int
supermount_rmdir(struct inode *dir, struct dentry *dentry)
{
	struct super_block *sb = dir->i_sb;
	struct dentry *subdent;
	struct inode *subdir;
	int rc;
	struct vfsmount *mnt;

	ENTER(sb, "dir=%p dentry=%s", dir, dentry->d_name.name);

	mnt = subfs_go_online(sb);
	rc = PTR_ERR(mnt);
	if (IS_ERR(mnt))
		goto out;

	subdir = get_subfs_inode(dir);
	rc = PTR_ERR(subdir);
	if (IS_ERR(subdir))
		goto go_offline;

	rc = -EPERM;
	if (!subdir->i_op || !subdir->i_op->rmdir)
		goto put_subdir;

	subdent = get_subfs_dentry(dentry);
	rc = PTR_ERR(subdent);
	if (IS_ERR(subdent))
		goto put_subdir;

	/* cf. supermount_unlink */
	rc = subfs_get_access(dentry->d_inode, 1);
	if (rc)
		goto put_subdent;

	rc = subdir->i_op->rmdir(subdir, subdent);
	if (rc)
		goto put_write_access;

	dir->i_mtime = subdir->i_mtime;
	dir->i_ctime = subdir->i_ctime;
	dir->i_nlink = subdir->i_nlink;
	dir->i_size = subdir->i_size;
	dir->i_blocks = subdir->i_blocks;

	/* hmm ... hard links to directories are not allowed, are they? */
	dentry->d_inode->i_nlink = subdent->d_inode->i_nlink;
	dentry->d_inode->i_ctime = subdent->d_inode->i_ctime;

put_write_access:
	/* cf. supermount_unlink */
	if (dentry->d_inode->i_nlink)
		subfs_put_access(dentry->d_inode, 1);
put_subdent:
	dput(subdent);
put_subdir:
	iput(subdir);
go_offline:
	subfs_go_offline(sb, mnt);
out:
	LEAVE(sb, "dir=%p dentry=%s rc=%d", dir, dentry->d_name.name, rc);

	return rc;
}

static int
supermount_mknod(struct inode *dir, struct dentry *dentry, int
		 mode, dev_t dev)
{
	struct super_block *sb = dir->i_sb;
	struct dentry *subdent;
	struct inode *subdir;
	int rc;
	struct vfsmount *mnt;

	ENTER(sb, "dir=%p dentry=%s", dir, dentry->d_name.name);

	mnt = subfs_go_online(sb);
	rc = PTR_ERR(mnt);
	if (IS_ERR(mnt))
		goto out;

	subdir = get_subfs_inode(dir);
	rc = PTR_ERR(subdir);
	if (IS_ERR(subdir))
		goto go_offline;

	rc = -EPERM;
	if (!subdir->i_op || !subdir->i_op->mknod)
		goto put_subdir;

	subdent = get_subfs_dentry(dentry);
	rc = PTR_ERR(subdent);
	if (IS_ERR(subdent))
		goto put_subdir;

	rc = subfs_get_access(dir, 1);
	if (rc)
		goto put_subdent;

	rc = subdir->i_op->mknod(subdir, subdent, mode, dev);
	subfs_put_access(dir, 1);
	if (rc)
		goto put_subdent;

	rc = prepare_inode(dentry, subdent);
	if (rc)
		goto put_subdent;

	dir->i_mtime = subdir->i_mtime;
	dir->i_ctime = subdir->i_ctime;
	dir->i_nlink = subdir->i_nlink;
	dir->i_size = subdir->i_size;
	dir->i_blocks = subdir->i_blocks;

put_subdent:
	dput(subdent);
put_subdir:
	iput(subdir);
go_offline:
	subfs_go_offline(sb, mnt);
out:
	LEAVE(sb, "dir=%p dentry=%s rc=%d", dir, dentry->d_name.name, rc);

	return rc;
}

static int
supermount_rename(struct inode *olddir, struct dentry *olddentry,
		  struct inode *newdir, struct dentry *newdentry)
{
	struct super_block *sb = olddir->i_sb;
	struct dentry *oldsubdent, *newsubdent;
	struct inode *oldsubdir, *newsubdir;
	int rc;
	struct vfsmount *mnt;

	ENTER(sb, "olddir=%p olddentry=%s newdir=%p newdentry=%s", olddir, olddentry->d_name.name, newdir, newdentry->d_name.name);

	mnt = subfs_go_online(sb);
	rc = PTR_ERR(mnt);
	if (IS_ERR(mnt))
		goto out;

	oldsubdir = get_subfs_inode(olddir);
	rc = PTR_ERR(oldsubdir);
	if (IS_ERR(oldsubdir))
		goto go_offline;

	rc = -EPERM;
	if (!oldsubdir->i_op || !oldsubdir->i_op->rename)
		goto put_old_subdir;

	oldsubdent = get_subfs_dentry(olddentry);
	rc = PTR_ERR(oldsubdent);
	if (IS_ERR(oldsubdent))
		goto put_old_subdir;

	newsubdir = get_subfs_inode(newdir);
	rc = PTR_ERR(newsubdir);
	if (IS_ERR(newsubdir))
		goto put_old_subdent;

	newsubdent = get_subfs_dentry(newdentry);
	rc = PTR_ERR(newsubdent);
	if (IS_ERR(newsubdent))
		goto put_new_subdir;

	/*
	 * If new file exists it will be implcitly unlinked so
	 * behave like in unlink case.
	 * If it does not exist we have two write accesses - for
	 * both old and new directory, I guess it does not matter
	 * which one is used in this case
	 */
	if (newdentry->d_inode)
		rc = subfs_get_access(newdentry->d_inode, 1);
	else
		rc = subfs_get_access(olddir, 1);
	if (rc)
		goto put_new_subdent;

	rc = oldsubdir->i_op->rename(oldsubdir, oldsubdent,
				     newsubdir, newsubdent);
	if (rc)
		goto put_write_access;

	/*
	 * this is strictly speaking conditional on FS_ODD_RENAME
	 * flag, but as of this writing this flag is set only
	 * for NFS or intermezzo and it hopefully goes away sometimes ...
	 *
	 * Supermount patch adds code to do_kern_mount that checks
	 * for this flag and refuses mounting
	 */
	d_move(oldsubdent, newsubdent);

	olddir->i_mtime = oldsubdir->i_mtime;
	olddir->i_ctime = oldsubdir->i_ctime;
	olddir->i_nlink = oldsubdir->i_nlink;
	olddir->i_size = oldsubdir->i_size;
	olddir->i_blocks = oldsubdir->i_blocks;

	newdir->i_mtime = newsubdir->i_mtime;
	newdir->i_ctime = newsubdir->i_ctime;
	newdir->i_nlink = newsubdir->i_nlink;
	newdir->i_size = newsubdir->i_size;
	newdir->i_blocks = newsubdir->i_blocks;

	olddentry->d_inode->i_nlink = oldsubdent->d_inode->i_nlink;
	olddentry->d_inode->i_ctime = oldsubdent->d_inode->i_ctime;

	if (newdentry->d_inode) {
		newdentry->d_inode->i_nlink = newsubdent->d_inode->i_nlink;
		newdentry->d_inode->i_ctime = newsubdent->d_inode->i_ctime;
	}

put_write_access:
	if (newdentry->d_inode) {
		/* cf. supermount_unlink */
		if (newdentry->d_inode->i_nlink)
			subfs_put_access(newdentry->d_inode, 1);
	} else
		subfs_put_access(olddir, 1);
put_new_subdent:
	dput(newsubdent);
put_new_subdir:
	iput(newsubdir);
put_old_subdent:
	dput(oldsubdent);
put_old_subdir:
	iput(oldsubdir);
go_offline:
	subfs_go_offline(sb, mnt);
out:
	LEAVE(sb, "olddentry=%s newdentry=%s rc=%d", olddentry->d_name.name, newdentry->d_name.name, rc);

	return rc;
}

static int 
supermount_readlink(struct dentry *dentry, char *buffer , int buflen)
{
	struct super_block *sb = dentry->d_sb;
	struct inode *inode = dentry->d_inode;
	struct dentry *subdent;
	int write_on = NEED_WRITE_ATIME(inode);
	int rc;
	struct vfsmount *mnt;

	ENTER(sb, "dentry=%s", dentry->d_name.name);

	mnt = subfs_go_online(sb);
	rc = PTR_ERR(mnt);
	if (IS_ERR(mnt))
		goto out;

	subdent = get_subfs_dentry(dentry);
	rc = PTR_ERR(subdent);
	if (IS_ERR(subdent))
		goto go_offline;

	rc = -EINVAL;
	if (!subdent->d_inode->i_op || !subdent->d_inode->i_op->readlink)
		goto put_subdent;

	rc = subfs_get_access(inode, write_on);
	if (rc)
		goto put_subdent;

	update_atime(subdent->d_inode);
	rc = subdent->d_inode->i_op->readlink(subdent, buffer, buflen);
	subfs_put_access(inode, write_on);
	inode->i_atime = subdent->d_inode->i_atime;

put_subdent:
	dput(subdent);
go_offline:
	subfs_go_offline(sb, mnt);
out:
	LEAVE(sb, "dentry=%s rc=%d", dentry->d_name.name, rc);

	return rc;
}

static int
supermount_follow_link(struct dentry *dentry, struct nameidata *nd)
{
	struct super_block *sb = dentry->d_sb;
	struct inode *inode = dentry->d_inode;
	struct dentry *subdent;
	int write_on = NEED_WRITE_ATIME(inode);
	int rc;
	struct vfsmount *mnt;
	
	ENTER(sb, "dentry=%s", dentry->d_name.name);

	mnt = subfs_go_online(sb);
	rc = PTR_ERR(mnt);
	if (IS_ERR(mnt))
		goto out;

	subdent = get_subfs_dentry(dentry);
	rc = PTR_ERR(subdent);
	if (IS_ERR(subdent))
		goto go_offline;

	rc = subfs_get_access(inode, write_on);
	if (rc)
		goto put_subdent;

	update_atime(subdent->d_inode);
	/* FIXME do we need proper subfs nd here? */
	rc = subdent->d_inode->i_op->follow_link(subdent, nd);
	subfs_put_access(inode, write_on);
	inode->i_atime = subdent->d_inode->i_atime;

put_subdent:
	dput(subdent);	
go_offline:
	subfs_go_offline(sb, mnt);
out:
	LEAVE(sb, "dentry=%s rc=%d", dentry->d_name.name, rc);

	return rc;
}

static int
supermount_permission(struct inode *inode, int mask, struct nameidata *nd)
{
	struct super_block *sb = inode->i_sb;
	struct inode *subi;
	int rc;
	int write_on = !IS_RDONLY(inode) && (mask & MAY_WRITE);
	struct vfsmount *mnt;
	int fake_permissions = 1;

	ENTER(sb, "inode=%p", inode);

	mnt = subfs_go_online(sb);
	rc = PTR_ERR(mnt);
	if (IS_ERR(mnt))
		goto out;

	subi = get_subfs_inode(inode);
	rc = PTR_ERR(subi);
	if (IS_ERR(subi))
		goto go_offline;

	rc = subfs_get_access(inode, write_on);
	if (rc)
		goto put_subi;

	fake_permissions = 0;
	/* FIXME do we need proper subfs nd here */
	if (subi->i_op && subi->i_op->permission)
		rc = subi->i_op->permission(subi, mask, nd);
	else
		rc = vfs_permission(subi, mask);

	subfs_put_access(inode, write_on);

put_subi:
	iput(subi);
go_offline:
	subfs_go_offline(sb, mnt);
out:
	if (fake_permissions && inode == sb->s_root->d_inode) {
		/* cf. file.c:supermount_open() */
		rc = vfs_permission(inode, mask);
	}

	LEAVE(sb, "inode=%p rc=%d fake=%d", inode, rc, fake_permissions);

	return rc;
}

static int
supermount_setattr(struct dentry *dentry, struct iattr *attr)
{
	struct super_block *sb = dentry->d_sb;
	struct inode *subi;
	struct dentry *subdent;
	int rc;
	struct vfsmount *mnt;

	ENTER(sb, "dentry=%s", dentry->d_name.name);

	mnt = subfs_go_online(sb);
	rc = PTR_ERR(mnt);
	if (IS_ERR(mnt))
		goto out;

	subdent = get_subfs_dentry(dentry);
	rc = PTR_ERR(subdent);
	if (IS_ERR(subdent))
		goto go_offline;

	rc = subfs_get_access(dentry->d_inode, 1);
	if (rc)
		goto put_subdent;

	subi = subdent->d_inode;
	if (subi->i_op && subi->i_op->setattr)
		rc = subi->i_op->setattr(subdent, attr);
	else {
		rc = inode_change_ok(subi, attr);
		/*
		 * FIXME
		 * What to do with quota?
		 */
		if (!rc)
			rc = inode_setattr(subi, attr);
	}
	subfs_put_access(dentry->d_inode, 1);
	if (rc)
		goto put_subdent;

	/* 
	 * If it worked, then we need to mark the modification
	 * to the subfs, and we also need to propogate the
	 * change up to the shadowing inode.  
	 */
	attr->ia_mode = subi->i_mode;
	attr->ia_uid = subi->i_uid;
	attr->ia_gid = subi->i_gid;
	attr->ia_size = subi->i_size;
	attr->ia_atime = subi->i_atime;
	attr->ia_mtime = subi->i_mtime;
	attr->ia_ctime = subi->i_ctime;
	attr->ia_valid =
	    ATTR_UID | ATTR_GID | ATTR_MODE | ATTR_SIZE |
	    ATTR_ATIME | ATTR_MTIME | ATTR_CTIME;
	inode_setattr(dentry->d_inode, attr);

put_subdent:
	dput(subdent);
go_offline:
	subfs_go_offline(sb, mnt);
out:
	LEAVE(sb, "dentry=%s rc=%d", dentry->d_name.name, rc);

	return rc;
}

static int
supermount_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
{
	struct super_block *sb = dentry->d_sb;
	struct vfsmount *submnt;
        struct dentry *subdent = 0;
        int rc;

	ENTER(sb, "dentry=%s", dentry->d_name.name);

	/*
	 * do not use subfs_go_online - it will result in ls /mnt
	 * attempting to mount all supermounted directories
	 */
	submnt = subfs_prevent_umount(sb);
	if (submnt)
		subdent = get_subfs_dentry(dentry);

	/*
	 * do not fail stat for stale files - it is needed to
	 * make sure fuser -m /mnt/cdrom lists all processes still
	 * having any (obsolete) file open
	 */
        if (submnt && subdent && !IS_ERR(subdent)) {
                rc = vfs_getattr(submnt, subdent, stat);
		stat->dev = sb->s_dev;
	} else {
		subfs_lock(sb);
		generic_fillattr(dentry->d_inode, stat);
		subfs_unlock(sb);
		rc = 0;
	}

	if (subdent && !IS_ERR(subdent))
		dput(subdent);
	if (submnt)
		subfs_allow_umount(sb, submnt);

	LEAVE(sb, "dentry=%s rc=%d", dentry->d_name.name, rc);

	return rc;
}

/*
 * directories can handle most operations...  supermount/namei.c just
 * passes them through to the underlying subfs, except for lookup().
 */

/* truncate: is not necesary, handled with setattr
 * revalidate: only needed by nfs
 * ->getattr:	FIXME is not appeared to be used anywhere in kernel; so I am
 *  		not sure how to implement it or what to return
 * FIXME: implement accl functions
 */

struct inode_operations supermount_dir_iops = {
	.create		= supermount_create,
	.lookup		= supermount_lookup,
	.link		= supermount_link,
	.unlink		= supermount_unlink,
	.symlink	= supermount_symlink,
	.mkdir		= supermount_mkdir,
	.rmdir		= supermount_rmdir,
	.mknod		= supermount_mknod,
	.rename		= supermount_rename,
	.permission	= supermount_permission,
	.setattr	= supermount_setattr,
	.getattr	= supermount_getattr,
};

struct inode_operations supermount_symlink_iops = {
	.readlink	= supermount_readlink,
	.follow_link	= supermount_follow_link,
	.setattr	= supermount_setattr,
	.getattr	= supermount_getattr,
};

struct inode_operations supermount_file_iops = {
	.setattr	= supermount_setattr,
	.getattr	= supermount_getattr,
};




/*
 *  linux/fs/supermount/proc.c
 *
 *  Initial version for kernel 2.4.21 (C) 2003 Andrey Borzenkov
 *                                             (arvidjaar@mail.ru)
 *  Rewritten for kernel 2.5.70 (C) 2003 Andrey Borzenkov
 *                                       (arvidjaar@mail.ru)
 *
 *  $Id: 4715_supermount-2.0.4-2.6.7.patch,v 1.1 2004/06/22 22:15:04 gregkh Exp $
 */

#include "supermount.h"

#ifdef CONFIG_PROC_FS

/*
 * we use semaphore because we have to lock subfs inside and it can
 * sleep. Unlocking procfs list would mean adding generic usage count
 * management to sbi and this is far too fetching
 */

static DECLARE_MUTEX(supermount_proc_sem);
static struct proc_dir_entry *supermount_proc_root;
static struct proc_dir_entry *supermount_proc_subfs;
static struct proc_dir_entry *supermount_proc_version;
static struct supermount_sb_info *supermount_list_head;

#define SKIP_BLANKS(s)	while(*s == ' ' || *s == '\t' || *s == '\n') s++
#define CHECK_COUNT do { \
	size += n; \
	count -= n; \
	if (count <= 0) { \
		subfs_unlock(sbi->host); \
		break; \
	} \
} while (0)

/* iterator; shamelessly copied over from pci.c */
static void *supermount_seq_start(struct seq_file *sf, loff_t *pos)
{
        struct supermount_sb_info *sbi;
        loff_t n = *pos;

	down(&supermount_proc_sem);

        sbi = supermount_list_head;
        while (n-- && sbi)
                sbi = sbi->next;

        return sbi;
}

static void *supermount_seq_next(struct seq_file *sf, void *v, loff_t *pos)
{
        struct supermount_sb_info *sbi = v;
        (*pos)++;
        return sbi->next;
}

static void supermount_seq_stop(struct seq_file *sf, void *v)
{
	up(&supermount_proc_sem);
}


static int
supermount_show_sbi(struct seq_file *sf, void *v)
{
	struct supermount_sb_info *sbi = v;


	subfs_lock(sbi->host);
	seq_puts(sf, sbi->devname);
	if (sbi->disabled)
		seq_puts(sf, " disabled\n");
	else if (subfs_is_mounted(sbi->host))
		seq_printf(sf, " mounted %d %d\n",
				sbi->readcount, sbi->writecount);
	else
		seq_puts(sf, " unmounted\n");
	subfs_unlock(sbi->host);

	return 0;
}

static struct seq_operations supermount_proc_subfs_op = {
        start:  supermount_seq_start,
        next:   supermount_seq_next,
        stop:   supermount_seq_stop,
        show:   supermount_show_sbi
};

static int supermount_proc_subfs_open(struct inode *inode, struct file *file)
{
        return seq_open(file, &supermount_proc_subfs_op);
}

/*
 * mostly copied over from drivers/scsi/scsi.c:proc_scsi_gen_write()
 */
static int
supermount_proc_subfs_write(struct file *file, const char *buf, size_t length, loff_t *offset)
{
	char *buffer, *s, *dev = 0;
	int disable = 0, enable = 0, release = 0, force = 0;
	struct supermount_sb_info *sbi;
	size_t rc;

	rc = -EINVAL;
	if (!buf || length > PAGE_SIZE)
		goto out;

	rc = -ENOMEM;
	if (!(s = buffer = (char *)__get_free_page(GFP_KERNEL)))
		goto out;

	rc =-EFAULT;
	if(copy_from_user(buffer, buf, length))
		goto free_buffer;

	rc = -EINVAL;
	if (length < PAGE_SIZE)
		buffer[length] = '\0';
	else if (buffer[PAGE_SIZE-1])
		goto free_buffer;

	/*
	 * echo "/dev/cdrom [enable|disable] [release [force]]" > \
	 * 				/proc/fs/supermount/subfs
	 */

	do {
		char *p;

		SKIP_BLANKS(s);
		p = strpbrk(s, " \t\n");
		if (p)
			*p++ = '\0';
		if (!dev)
			dev = s;
		else if (!strcmp(s, "disable"))
			disable = 1;
		else if (!strcmp(s, "enable"))
			enable = 1;
		else if (!strcmp(s, "release"))
			release = 1;
		else if (!strcmp(s, "force"))
			force = 1;
		else
			goto free_buffer;

		s = p;
	} while (s && *s);

	if ((enable && disable) || (force && !release))
		goto free_buffer;

	down(&supermount_proc_sem);
	for(sbi = supermount_list_head; sbi; sbi = sbi->next) {
		if (strcmp(sbi->devname, dev))
			continue;

		subfs_lock(sbi->host);

		rc = length;
		if (release && subfs_is_mounted(sbi->host)) {
			if (!subfs_is_busy(sbi->host) || force)
				subfs_umount(sbi->host, SUBFS_UMNT_USER);
			else
				rc = -EBUSY;
		}
		
		if (disable && subfs_is_mounted(sbi->host))
			rc = -EBUSY;

		if (rc >= 0) {
			if (disable)
				sbi->disabled = 1;
			else if (enable)
				sbi->disabled = 0;
		}

		subfs_unlock(sbi->host);
		break;
	}
	up(&supermount_proc_sem);

free_buffer:
	free_page((unsigned long)buffer);
out:
	return rc;

}

static struct file_operations supermount_proc_subfs_operations = {
        open:           supermount_proc_subfs_open,
        read:           seq_read,
        llseek:         seq_lseek,
        release:        seq_release,
	write:		supermount_proc_subfs_write,
};

static int
supermount_proc_version_read(char *page, char **start, off_t pos, int count, int *eof, void *data)
{
	int rc;

	rc = snprintf(page, count, "Supermount version %s for kernel 2.6\n",
				    SUPERMOUNT_VERSION);
	*eof = 1;
	return rc;
}

void
supermount_proc_register(void)
{
	supermount_proc_root = proc_mkdir("fs/supermount", 0);
	if (!supermount_proc_root) {
		printk(KERN_ERR "SUPERMOUNT failed to create /proc/fs/supermount");
		return;
	}
	supermount_proc_root->owner = THIS_MODULE;

	supermount_proc_version = create_proc_read_entry("version",
                                        S_IFREG | S_IRUGO,
                                        supermount_proc_root,
					supermount_proc_version_read,
					0);

	if (supermount_proc_version)
		supermount_proc_version->owner = THIS_MODULE;
	else
		printk(KERN_ERR
		"SUPERMOUNT failed to create /proc/fs/supermount/version");

	supermount_proc_subfs = create_proc_entry("subfs",
                                        S_IFREG | S_IRUGO | S_IWUSR,
                                        supermount_proc_root);

	if (supermount_proc_subfs) {
		supermount_proc_subfs->proc_fops =
			&supermount_proc_subfs_operations;
		supermount_proc_subfs->owner = THIS_MODULE;
	} else
		printk(KERN_ERR
		"SUPERMOUNT failed to create /proc/fs/supermount/subfs");

}

void
supermount_proc_unregister(void)
{
	remove_proc_entry("fs/supermount/subfs", 0);
	remove_proc_entry("fs/supermount/version", 0);
	remove_proc_entry("fs/supermount", 0);
}

void
supermount_proc_insert(struct supermount_sb_info *sbi)
{

	down(&supermount_proc_sem);

	sbi->next = supermount_list_head;
	supermount_list_head = sbi;

	up(&supermount_proc_sem);
}

void
supermount_proc_remove(struct supermount_sb_info *sbi)
{
	struct supermount_sb_info **p, *q;

	down(&supermount_proc_sem);

	for(p = &supermount_list_head, q = supermount_list_head;
			q; p = &q->next, q = q->next)
		if (q == sbi)
			break;

	if (q)
		*p = q->next;

	up(&supermount_proc_sem);

	SUPERMOUNT_BUG_ON(!q);
}
#endif /* CONFIG_PROC_FS */




/*
 *  linux/fs/supermount/subfs.c
 *
 *  Original version:
 *      Copyright (C) 1995, 1997
 *      Stephen Tweedie (sct@dcs.ed.ac.uk)
 *
 *      from
 *
 *      linux/fs/minix/inode.c
 *      Copyright (C) 1991, 1992  Linus Torvalds
 *
 *      and
 *
 *      linux/fs/ext2/super.c
 *      Copyright (C) 1992, 1993, 1994, 1995  Remy Card
 *
 *  Rewriten for kernel 2.2, 2.4. (C) 1999, 2000 Alexis Mikhailov
 *                                    (alexis@abc.cap.ru)
 *  Rewritten for kernel 2.4.21 (C) 2003 Andrey Borzenkov
 *                                       (arvidjaar@mail.ru)
 *  Rewritten for kernel 2.5.70 (C) 2003 Andrey Borzenkov
 *                                       (arvidjaar@mail.ru)
 *
 *  $Id: 4715_supermount-2.0.4-2.6.7.patch,v 1.1 2004/06/22 22:15:04 gregkh Exp $
 */

#define S_DBG_TRACE_CURRENT S_DBG_TRACE_SUBFS
#include "supermount.h"

/*
 * close all open files on subfs
 */
static void
supermount_clean_files(struct super_block *sb)
{
	struct supermount_sb_info *sbi = supermount_sbi(sb);
	struct list_head *ptr, *n;

	ENTER(sb);

	list_for_each_safe(ptr, n, &sbi->s_files) {
		struct supermount_file_info *sfi;
		struct file *subfile;

		sfi = list_entry(ptr, struct supermount_file_info, list);

		subfile = sfi->file;
		sfi->file = 0;
		list_del_init(&sfi->list);

		SUPERMOUNT_BUG_LOCKED_ON(sb, !subfile);

		fput(subfile);
	}

	LEAVE(sb);

}

/*
 * close all open dentries on subfs
 */
static void
supermount_clean_dentries(struct super_block *sb)
{
	struct supermount_sb_info *sbi = supermount_sbi(sb);
	struct list_head *ptr, *n;

	ENTER(sb);

	list_for_each_safe(ptr, n, &sbi->s_dentries) {
		struct supermount_dentry_info *sdi;
		struct dentry *subdent;

		sdi = list_entry(ptr, struct supermount_dentry_info, list);
		/*
		 * HACK - FIXME
		 * see dentry.c:supermount_d_compare
		 */
		write_lock(&d_compare_lock);
		subdent = sdi->dentry;
		sdi->dentry = 0;
		write_unlock(&d_compare_lock);

		list_del_init(&sdi->list);
		d_drop(sdi->host);
		dnotify_parent(sdi->host, DN_DELETE);

		SUPERMOUNT_BUG_LOCKED_ON(sb, !subdent);

		dput(subdent);
	}

	LEAVE(sb);

}

/*
 * close all open inodes on subfs
 */
static void
supermount_clean_inodes(struct super_block *sb)
{
	struct supermount_sb_info *sbi = supermount_sbi(sb);
	struct list_head *ptr, *n;

	ENTER(sb);

	list_for_each_safe(ptr, n, &sbi->s_inodes) {
		struct supermount_inode_info *sii;
		struct inode *host;
		struct inode *subi;

		sii = list_entry(ptr, struct supermount_inode_info, list);
		host = &sii->vfs_inode;

		subi = sii->inode;
		sii->inode = NULL;
		list_del_init(&sii->list);
		remove_inode_hash(host);
		host->i_mapping = &host->i_data;

		/*
		 * it is possible to have no subi here. clear_inode does
		 * release lock after removing subi but before unlinking
		 * it
		 */
		if (subi)
			iput(subi);

		SUPERMOUNT_BUG_LOCKED_ON(sb, sii->writecount < 0);
		SUPERMOUNT_BUG_LOCKED_ON(sb, sii->readcount < 0);
		while (sii->writecount) {
			sii->writecount--;
			sbi->writecount--;
		}
		while (sii->readcount) {
			sii->readcount--;
			sbi->readcount--;
		}
	}

	LEAVE(sb);
}

/*
 * reason can be
 *   SUBFS_UMNT_NORMAL - normal umount, do not try to release subfs
 *   SUBFS_UMNT_MEDIA  - media change detected, release subfs,
 *   			 do not remount ro (as media is already gone)
 *   SUBFS_UMNT_USER   - user request, release subfs, remount ro before
 *   			 releasing tray lock
 *
 *   unlock_door is always needed to keep device usage count correct
 */
static inline int subfs_remount_ro(struct super_block *sb);
void
subfs_umount(struct super_block *sb, int reason)
{
	struct supermount_sb_info *sbi = supermount_sbi(sb);
	int writecount = sbi->writecount;

	ENTER(sb);

	if (reason != SUBFS_UMNT_NORMAL) {
		/*
		 * we used to did shrink_dcache here. It compicates locking
		 * (clear_inode is called under sbi->sem thus requiring either
		 * recursive lock or separate lock just for inode list).
		 * This is not needed any more to ensure subfs can be umounted
		 * so we let dentries die and rely on dentry_revalidate to
		 * reject stale dentries
		 */

		if (subfs_is_busy(sb))
			supermount_warning(sb, "opened files during media change");

		supermount_clean_files(sb);
		supermount_clean_dentries(sb);
		supermount_clean_inodes(sb);

		if (reason == SUBFS_UMNT_USER && writecount > 0)
			subfs_remount_ro(sb);
		if (sbi->lockcount > 0)
			supermount_unlock_door(sb);
		/*
		 * this is quite ugly but so far I have no idea how to
		 * do it cleanly
		 */
		sbi->lockcount = 0;
	}

	/*
	 * all files are expected to be closed
	 */
	SUPERMOUNT_BUG_LOCKED_ON(sb, sbi->writecount);
	SUPERMOUNT_BUG_LOCKED_ON(sb, sbi->readcount);
	SUPERMOUNT_BUG_LOCKED_ON(sb, sbi->lockcount);
	SUPERMOUNT_BUG_LOCKED_ON(sb, !list_empty(&sbi->s_files));
	SUPERMOUNT_BUG_LOCKED_ON(sb, !list_empty(&sbi->s_dentries));
	SUPERMOUNT_BUG_LOCKED_ON(sb, !list_empty(&sbi->s_inodes));

	unmark_media_supermounted(sb);
	mntput(sbi->s_undermount);
	sbi->s_undermount = NULL;
	if (sbi->rw)
		sb->s_flags &= ~MS_RDONLY;
	sb->s_blocksize = 1024;
	sb->s_blocksize_bits = 10;

	/*
	 * FIXME
	 * again the problem of unmounting subfs from inside of put_super
	 */
	if (sb->s_root)
		supermount_init_root_inode(sb->s_root->d_inode);

	LEAVE(sb);
}

static inline int
subfs_remount_ro(struct super_block *sb)
{
	struct super_block *subsb = subfs_sb(sb);
	int rc;

	ENTER(sb);

	rc = do_remount_sb(subsb, subsb->s_flags | MS_RDONLY, NULL, 0);

	LEAVE(sb);

	return rc;
}

static inline int
subfs_remount_rw(struct super_block *sb)
{
	struct super_block *subsb = subfs_sb(sb);
	int rc;

	ENTER(sb);

	rc = do_remount_sb(subsb, subsb->s_flags & ~MS_RDONLY, NULL, 0);

	LEAVE(sb);

	return rc;
}

static struct vfsmount *
subfs_real_mount(struct super_block *sb, char *type)
{
	struct supermount_sb_info *sbi = supermount_sbi(sb);
	struct vfsmount *mnt;
	char *opts = NULL;

	ENTER(sb, "type=%s", type);

	if (sbi->s_data) {
		opts = strdup(sbi->s_data);
		if (!opts) {
			mnt = ERR_PTR(-ENOMEM);
			goto fail;
		}
	}

	mnt = do_kern_mount(type,
			    (sb->s_flags & MS_RMT_MASK) | MS_SUPERMOUNTED,
			    sbi->devname, opts);
	if (opts)
		kfree(opts);

fail:
	LEAVE(sb, "submnt=%p", mnt);

	return mnt;
}

static int
subfs_real_mount2(struct super_block *sb, char *type)
{
	struct supermount_sb_info *sbi = supermount_sbi(sb);
	struct vfsmount *mnt;
	struct super_block *subsb;
	int rc = 0;

	ENTER(sb, "type=%s", type);

	mnt = subfs_real_mount(sb, type);

	if (IS_ERR(mnt) && PTR_ERR(mnt) == -EROFS) {
		sb->s_flags |= MS_RDONLY;
		mnt = subfs_real_mount(sb, type);
	}
	rc = PTR_ERR(mnt);
	if (IS_ERR(mnt))
		goto out;

	/* paranoid check for double-mounting */
	SUPERMOUNT_BUG_LOCKED_ON(sb, atomic_read(&mnt->mnt_sb->s_active) != 1);

	sbi->s_undermount = mnt;

	if (!(sb->s_flags & MS_RDONLY)) {
		rc = subfs_remount_ro(sb);
		if (rc)
			goto mntput;
	}

	subsb = mnt->mnt_sb;
	sb->s_blocksize = subsb->s_blocksize;
	sb->s_blocksize_bits = subsb->s_blocksize_bits;
	attach_subfs_dentry(sb->s_root, mnt->mnt_root);
	attach_subfs_inode(sb->s_root->d_inode, mnt->mnt_root->d_inode);
	insert_inode_hash(sb->s_root->d_inode);
	dnotify_parent(sb->s_root, DN_CREATE);
	rc = 0;
	goto out;

	/*
	 * error clean up
	 */
mntput:
	sbi->s_undermount = 0;
	mntput(mnt);
out:
	LEAVE(sb, "type=%s rc=%d", type, rc);

	return rc;
}

/*
 * Error values from mount
 *   ENOENT     - no device file (quite possible with devfs)
 *   ENXIO      - device does not exist
 *   ENOMEDIUM  - no medium inserted (surprise, surprise :)
 *   EBUSY      - attempt to mount on already mounted device
 *                we specifically disallow it even when both
 *                file system and mode (ro/rw) are the same
 */
static int
subfs_mount(struct super_block *sb)
{
	struct supermount_sb_info *sbi = supermount_sbi(sb);
	int retval = -ENODEV;
	char *types = strdup(sbi->s_type);

	ENTER(sb);

	if (sbi->disabled)
		retval = -EPERM;
	else if (!types)
	       retval = -ENOMEM;
	else {
		char *p = types, *fs;

		while ((fs = strsep(&p, ":")) != NULL && retval
		       && retval != -ENXIO
		       && retval != -ENOMEDIUM
		       && retval != -ENOENT
		       && retval != -EBUSY)
			retval = subfs_real_mount2(sb, fs);
	}

	if (types)
		kfree(types);

	if (!retval)
		mark_media_supermounted(sb);

	LEAVE(sb, "rc=%d", retval);

	return retval;
}

static int
__subfs_check_disk_change(struct super_block *sb)
{
	struct super_block *subsb = subfs_sb(sb);
	int rc;
	struct block_device *dev = subsb->s_bdev;

	ENTER(sb);

	rc = atomic_read(&subsb->s_media_changed);
	if (!rc) {
		lock_kernel();
		rc = check_disk_change(dev);
		unlock_kernel();
	}

	if (rc)
		subfs_umount(sb, SUBFS_UMNT_MEDIA);

	LEAVE(sb, "rc=%d", rc);

	return rc;
}

/*
 * this must really be called subfs_active ...
 */
int
subfs_check_disk_change(struct super_block *sb)
{
	int rc;

	ENTER(sb);

	subfs_lock(sb);
	if (subfs_is_mounted(sb))
		rc = __subfs_check_disk_change(sb);
	else
		rc = 1;
	subfs_unlock(sb);


	LEAVE(sb, "rc=%d", rc);

	return rc;
}

static int
check_and_remount_subfs(struct super_block *sb)
{
	int rc;

	ENTER(sb);

	if (subfs_is_mounted(sb) && !__subfs_check_disk_change(sb)) {
		rc = 0;
		goto out;
	}

	rc = subfs_mount(sb);

out:
	LEAVE(sb, "rc=%d", rc);

	return rc;
}

static inline void
subfs_tray_lock(struct super_block *sb)
{
	struct supermount_sb_info *sbi = supermount_sbi(sb);

	ENTER(sb);

	SUPERMOUNT_BUG_LOCKED_ON(sb, sbi->lockcount < 0);

	if (!sbi->lockcount++)
		supermount_lock_door(sb);

	LEAVE(sb);
}

static inline void
subfs_tray_unlock(struct super_block *sb)
{
	struct supermount_sb_info *sbi = supermount_sbi(sb);

	ENTER(sb);

	SUPERMOUNT_BUG_LOCKED_ON(sb, sbi->lockcount <= 0);

	if (!--sbi->lockcount)
		supermount_unlock_door(sb);

	LEAVE(sb);
}

static void
subfs_get_read_access(struct super_block *sb)
{
	struct supermount_sb_info *sbi = supermount_sbi(sb);

	ENTER(sb);

	SUPERMOUNT_BUG_LOCKED_ON(sb, sbi->readcount < 0);

	if (!sbi->readcount++ && sbi->tray_lock == TRAY_LOCK_ALWAYS)
		subfs_tray_lock(sb);

	LEAVE(sb);
}

static int
subfs_get_write_access(struct super_block *sb)
{
	struct supermount_sb_info *sbi = supermount_sbi(sb);
	int rc;

	ENTER(sb);

	SUPERMOUNT_BUG_LOCKED_ON(sb, sbi->writecount < 0);

	rc = 0;
	if (!sbi->writecount) {
		if (sb->s_flags & MS_RDONLY)
			rc = -EROFS;
		else
			rc = subfs_remount_rw(sb);
	}

	if (!rc && !sbi->writecount++ && sbi->tray_lock != TRAY_LOCK_NEVER)
		subfs_tray_lock(sb);

	LEAVE(sb, "rc=%d", rc);

	return rc;
}

static void
subfs_put_read_access(struct super_block *sb)
{
	struct supermount_sb_info *sbi = supermount_sbi(sb);

	ENTER(sb);

	SUPERMOUNT_BUG_LOCKED_ON(sb, sbi->readcount <= 0);

	if (!--sbi->readcount && sbi->tray_lock == TRAY_LOCK_ALWAYS)
		subfs_tray_unlock(sb);

	LEAVE(sb);
}

static void
subfs_put_write_access(struct super_block *sb)
{
	struct supermount_sb_info *sbi = supermount_sbi(sb);

	ENTER(sb);

	SUPERMOUNT_BUG_LOCKED_ON(sb, sbi->writecount <= 0);

	if (!--sbi->writecount) {
		/*
		 * no need to fsync, it is done automatically on remount
		 */
		int rc = subfs_remount_ro(sb);
		if (rc)
			supermount_error(sb, "failed to remount ro, error = %d", rc);
		if (sbi->tray_lock != TRAY_LOCK_NEVER)
			subfs_tray_unlock(sb);
	}

	LEAVE(sb);
}

int
subfs_get_access(struct inode *inode, int rw)
{
	struct super_block *sb = inode->i_sb;
	int rc = 0;
	
	ENTER(sb);

	subfs_lock(sb);
	if (is_inode_obsolete(inode))
		rc = -ESTALE;
	else {
		struct supermount_inode_info *sii = supermount_i(inode);

		if (rw) {
			SUPERMOUNT_BUG_LOCKED_ON(sb, sii->writecount < 0);
			rc = subfs_get_write_access(sb);
			if (!rc)
				sii->writecount++;
		} else {
			SUPERMOUNT_BUG_LOCKED_ON(sb, sii->readcount < 0);
			subfs_get_read_access(sb);
			sii->readcount++;
		}
	}
	subfs_unlock(sb);

	LEAVE(sb, "rc=%d", rc);

	return rc;
}

void
subfs_put_access(struct inode *inode, int rw)
{
	struct super_block *sb = inode->i_sb;

	ENTER(sb);

	subfs_lock(sb);
	if (!is_inode_obsolete(inode)) {
		struct supermount_inode_info *sii = supermount_i(inode);

		if (rw) {
			SUPERMOUNT_BUG_LOCKED_ON(sb, sii->writecount <= 0);
			sii->writecount--;
			subfs_put_write_access(sb);
		} else {
			SUPERMOUNT_BUG_LOCKED_ON(sb, sii->readcount <= 0);
			sii->readcount--;
			subfs_put_read_access(sb);
		}

	}
	subfs_unlock(sb);

	LEAVE(sb);
}

struct vfsmount *
subfs_go_online(struct super_block *sb)
{
	int rc;
	struct vfsmount *mnt;

	ENTER(sb);

	subfs_lock(sb);

	rc = check_and_remount_subfs(sb);
	mnt = ERR_PTR(rc);
	if (!rc)
		mnt = mntget(subfs_mnt(sb));
	subfs_unlock(sb);

	LEAVE(sb, "mnt=%p", mnt);

	return mnt;
}

void
subfs_go_offline(struct super_block *sb, struct vfsmount *mnt)
{
	ENTER(sb);

	SUPERMOUNT_BUG_ON(!mnt);
	mntput(mnt);

	LEAVE(sb);

}

struct vfsmount *
subfs_prevent_umount(struct super_block *sb)
{
	struct vfsmount *mnt;

	ENTER(sb);

	subfs_lock(sb);
	mnt = subfs_mnt(sb);
	if (mnt)
		mnt = mntget(mnt);
	subfs_unlock(sb);

	LEAVE(sb, "mnt=%p", mnt);

	return mnt;
}

void
subfs_allow_umount(struct super_block *sb, struct vfsmount *mnt)
{
	ENTER(sb);

	SUPERMOUNT_BUG_ON(!mnt);
	mntput(mnt);

	LEAVE(sb);

}

struct vfsmount *
subfs_get_mnt(struct super_block *sb)
{
	struct vfsmount *mnt = NULL;

	ENTER(sb);

	subfs_lock(sb);
	if (subfs_is_mounted(sb))
		mnt = mntget(subfs_mnt(sb));
	subfs_unlock(sb);

	LEAVE(sb, "mnt=%p", mnt);

	return mnt;
}

struct super_block *
subfs_get_sb(struct super_block *sb)
{
	struct super_block *subsb = NULL;

	ENTER(sb);

	subfs_lock(sb);
	if (subfs_is_mounted(sb))
		subsb = subfs_sb(sb);
	subfs_unlock(sb);

	LEAVE(sb, "subsb=%p", subsb);

	return subsb;
}

/*
 * contrary to its name this function deals with _supermount_ inode
 */
void
subfs_clear_inode(struct inode *inode)
{
	struct super_block *sb = inode->i_sb;
	struct supermount_inode_info *sii = supermount_i(inode);

	ENTER(sb, "inode=%p", inode);

	subfs_lock(sb);

	/*
	 * this is safe. If subfs has been unmounted, counters has been
	 * set to 0 already
	 */
	while(sii->writecount > 0) {
		sii->writecount--;
		subfs_put_write_access(sb);
	}

	while(sii->readcount > 0) {
		sii->readcount--;
		subfs_put_read_access(sb);
	}

	list_del(&sii->list);

	subfs_unlock(sb);

	LEAVE(sb, "inode=%p", inode);
}




/*
 *  linux/fs/supermount/super.c
 *
 *  Original version:
 *      Copyright (C) 1995, 1997
 *      Stephen Tweedie (sct@@dcs.ed.ac.uk)
 *
 *      from
 *
 *      linux/fs/minix/inode.c
 *      Copyright (C) 1991, 1992  Linus Torvalds
 *
 *      and
 *
 *      linux/fs/ext2/super.c
 *      Copyright (C) 1992, 1993, 1994, 1995  Remy Card
 *
 *  Rewriten for kernel 2.2, 2.4. (C) 1999, 2000 Alexis Mikhailov
 *                                    (alexis@@abc.cap.ru)
 *  Rewritten for kernel 2.4.21 (C) 2003 Andrey Borzenkov
 *                                       (arvidjaar@@mail.ru)
 *  Rewritten for kernel 2.5.70 (C) 2003 Andrey Borzenkov
 *                                       (arvidjaar@@mail.ru)
 *
 *  $Id: 4715_supermount-2.0.4-2.6.7.patch,v 1.1 2004/06/22 22:15:04 gregkh Exp $
 */

#define S_DBG_TRACE_CURRENT S_DBG_TRACE_SUPER

#include <linux/statfs.h>
#include <linux/parser.h>
#include "supermount.h"

/*
 * vfat and msdos do not have any valididty checks for superblock and must
 * be the last entries!
 */

static char *default_fs_types = "udf:iso9660:ext2:vfat:msdos";

static struct super_operations supermount_sops;

/* ========================= helpers ================================= */

static inline void
supermount_update_inode(struct inode *superi, struct inode *subi)
{
	struct super_block *sb = superi->i_sb;

	ENTER(sb, "superi=%p subi=%p", superi, subi);

	superi->i_ino = subi->i_ino;
	superi->i_mode = subi->i_mode;
	superi->i_uid = subi->i_uid;
	superi->i_gid = subi->i_gid;
	superi->i_nlink = subi->i_nlink;
	superi->i_size = subi->i_size;
	superi->i_atime = subi->i_atime;
	superi->i_ctime = subi->i_ctime;
	superi->i_mtime = subi->i_mtime;
	superi->i_blksize = subi->i_blksize;
	superi->i_blocks = subi->i_blocks;
	superi->i_rdev = subi->i_rdev;
	superi->i_version++;
	set_inode_flags(superi, subi);

	if (S_ISDIR(superi->i_mode)) {
		superi->i_op = &supermount_dir_iops;
		superi->i_fop = &supermount_dir_operations;
	} else if (S_ISLNK(superi->i_mode)) {
		superi->i_op = &supermount_symlink_iops;
		superi->i_mapping = subi->i_mapping;
	} else {
		superi->i_op = &supermount_file_iops;
		superi->i_fop = &supermount_file_operations;
		superi->i_mapping = subi->i_mapping;
	}

	LEAVE(sb, "superi=%p subi=%p", superi, subi);
}

/* this is also called from subfs_mount to reinstantiate root inode */
void
attach_subfs_inode(struct inode *inode, struct inode *subi)
{
	struct super_block *sb = inode->i_sb;
	struct supermount_sb_info *sbi = supermount_sbi(sb);
	struct supermount_inode_info *sii;

	ENTER(sb, "inode=%p subi=%p", inode, subi);

	sii = supermount_i(inode);
	if (!sii->inode) {
		/*
		 * this can be run concurrently. It is executed under
		 * sbi->sem so only one task would actually instantate
		 * inode. See namei.c:prepare_inode
		 * Another user is subfs.c:subfs_real_mount2
		 */
		sii->inode = igrab(subi);
		supermount_update_inode(inode, subi);
		list_add(&sii->list, &sbi->s_inodes);
	} else
		SUPERMOUNT_BUG_LOCKED_ON(sb, sii->inode != subi);

	LEAVE(sb, "inode=%p subi=%p", inode, subi);
}

char *
strdup(const char *val)
{
	char *tmp;
	tmp = kmalloc(1 + strlen(val), GFP_KERNEL);
	if (tmp)
		strcpy(tmp, val);
	return tmp;
}

static struct supermount_sb_info *
create_sbi(struct super_block *sb)
{
	struct supermount_sb_info *sbi = kmalloc(sizeof (*sbi), GFP_KERNEL);

	if (!sbi)
		return NULL;

	memset(sbi, 0, sizeof (*sbi));

	sbi->s_undermount = NULL;
	sbi->s_type = sbi->devname = sbi->s_data = NULL;
	INIT_LIST_HEAD(&sbi->s_inodes);
	INIT_LIST_HEAD(&sbi->s_files);
	INIT_LIST_HEAD(&sbi->s_dentries);
	init_MUTEX(&sbi->sem);
	sbi->host = sb;
	sbi->tray_lock = TRAY_LOCK_ONWRITE;
	sbi->rw = !(sb->s_flags & MS_RDONLY);

	return sbi;
}

static void
free_sbi(struct supermount_sb_info *sbi)
{
	if (sbi->s_type && sbi->s_type != default_fs_types)
		kfree(sbi->s_type);
	if (sbi->devname)
		kfree(sbi->devname);
	if (sbi->s_data)
		kfree(sbi->s_data);
	kfree(sbi);
}

enum {
	Opt_fs, Opt_fs_auto, Opt_dev, Opt_debug, Opt_debug_old, Opt_subfsopts,
	Opt_tray_lock_always, Opt_tray_lock_never, Opt_tray_lock_onwrite,
	Opt_ignore, Opt_err
};

static match_table_t tokens = {
	{Opt_fs_auto, "fs=auto"},
	{Opt_fs, "fs=%s"},
	{Opt_dev, "dev=%s"},
	{Opt_debug, "debug=%u"},
	{Opt_debug_old, "debug"},
	{Opt_subfsopts, "--"},
	{Opt_tray_lock_always, "tray_lock=always"},
	{Opt_tray_lock_never, "tray_lock=never"},
	{Opt_tray_lock_onwrite, "tray_lock=onwrite"},
	{Opt_ignore, "no_tray_lock"},
	{Opt_ignore, "fail_statfs_until_mount"},
	{Opt_err, NULL}
};

static int
parse_options(char *options, struct super_block *sb)
{
	struct supermount_sb_info *sbi = supermount_sbi(sb);
	int rc;
	char *p;

	if (!options)
		return 0;

	while ((p = strsep(&options, ",")) != NULL) {
		int token;
		substring_t args[MAX_OPT_ARGS];
		int n;

		/* empty option means start of subfs options */
		if (!*p)
			goto copy_subfs_options;

		token = match_token(p, tokens, args);
		switch(token) {
		case Opt_fs:
			sbi->s_type = match_strdup(&args[0]);
			if (!sbi->s_type)
				return -ENOMEM;
			break;
		case Opt_fs_auto:
			sbi->s_type = default_fs_types;
			break;
		case Opt_dev:
			sbi->devname = match_strdup(&args[0]);
			if (!sbi->devname)
				return -ENOMEM;
			break;
		case Opt_debug:
			if ((rc = match_int(&args[0], &n)))
				return rc;
			sbi->s_debug = n;
			break;
		case Opt_debug_old:
			sbi->s_debug = S_DBG_DEBUG;
			break;
		case Opt_tray_lock_always:
			sbi->tray_lock = TRAY_LOCK_ALWAYS;
			break;
		case Opt_tray_lock_onwrite:
			sbi->tray_lock = TRAY_LOCK_ONWRITE;
			break;
		case Opt_tray_lock_never:
			sbi->tray_lock = TRAY_LOCK_NEVER;
			break;
		case Opt_subfsopts:
copy_subfs_options:
			/* mount may have removed options after -- */
			if (options && *options) {
				sbi->s_data = strdup(options);
				if (!sbi->s_data)
					return -ENOMEM;
			}
			return 0;
			break;
		case Opt_ignore:
			break;
		default:
			supermount_error(sb, "Unrecognized mount option \"%s\"",
					 p);
			return -EINVAL;
			break;
		}
	}

	return 0;
}

void
supermount_init_root_inode(struct inode *inode)
{
	inode->i_mode = 0777 | S_IFDIR;
	inode->i_uid = current->fsuid;
	inode->i_gid = current->fsgid;
	inode->i_blksize = inode->i_sb->s_blocksize;
	inode->i_rdev = MKDEV(UNNAMED_MAJOR, 0);
	inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
	inode->i_size = 0;
	inode->i_blocks = 0;
	inode->i_ino = 0;
	inode->i_nlink = 0;

	set_inode_flags(inode, 0);

	inode->i_op = &supermount_dir_iops;
	inode->i_fop = &supermount_dir_operations;
}

static struct inode *
supermount_root_inode(struct super_block *sb)
{
	struct inode *inode = new_inode(sb);

	ENTER(sb);

	if (inode) {
		inode->i_version = 0;
		supermount_init_root_inode(inode);
	}

	LEAVE(sb, "inode=%p", inode);

	return inode;
}

/* ========================== used in fstype declaration ================*/

/* read_super: the main mount() entry point into the VFS layer. */
static int
supermount_read_super(struct super_block *sb, void *data, int silent)
{
	struct inode *root_inode;
	struct dentry *root;
	struct supermount_sb_info *sbi = create_sbi(sb);
	int rc = -ENOMEM;

	if (!sbi)
		goto fail_no_memory;

	sb->s_fs_info = sbi;

	rc = parse_options((char *) data, sb);
	if (rc)
		goto fail_parsing;

	rc = -EINVAL;
	if (!sbi->devname) {
		supermount_error(sb, "no dev=<device> option");
		goto fail_parsing;
	}

	if (!sbi->s_type) {
		sbi->s_type = default_fs_types;
		supermount_warning(sb, "no fs=<filesystem> option, assuming fs=auto");
	}

	rc = -ENOMEM;

	sb->s_blocksize = 1024;
	sb->s_blocksize_bits = 10;
	sb->s_magic = SUPERMOUNT_SUPER_MAGIC;
	sb->s_op = &supermount_sops;

	root_inode = supermount_root_inode(sb);
	if (!root_inode)
		goto fail_allocating_root_inode;

	root = d_alloc_root(root_inode);
	if (!root)
		goto fail_allocating_root_dentry;
	if (init_dentry_info(root))
		goto fail_init_root_info;

	sb->s_root = root;

	supermount_proc_insert(sbi);

	return 0;

fail_init_root_info:
	dput(root);
fail_allocating_root_dentry:
	iput(root_inode);
fail_parsing:
fail_allocating_root_inode:
	free_sbi(sbi);

fail_no_memory:
	return rc;
}

struct super_block *supermount_get_sb(struct file_system_type *fs_type, int flags, const char *dev_name, void *data)
{
        return get_sb_nodev(fs_type, flags, data, supermount_read_super);
}

/* ======================= super_operations methods ==================== */

static struct inode *
supermount_alloc_inode(struct super_block *sb)
{
	struct supermount_inode_info *sii = kmalloc(sizeof(*sii), GFP_KERNEL);
	struct inode *inode = 0;

	ENTER(sb);

	if (sii) {
		INIT_LIST_HEAD(&sii->list);
		sii->inode = 0;
		sii->readcount = 0;
		sii->writecount = 0;
		inode = &sii->vfs_inode;
		inode_init_once(inode);
	}

	LEAVE(sb, "inode=%p", inode);

	return inode;
}

static void
supermount_destroy_inode(struct inode *inode)
{
	struct super_block *sb = inode->i_sb;
	struct supermount_inode_info *sii = supermount_i(inode);

	ENTER(sb, "inode=%p", inode);

	kfree(sii);

	ENTER(sb, "inode=%p", inode);
}

/*
 * FIXME
 * I am still unsure if (or why) this functions is needed; it is likely
 * to go away. So far the only _real_ user seems to be knfsd.
 */
static void
supermount_write_inode(struct inode *inode, int sync)
{
	struct super_block *sb = inode->i_sb;
	struct super_block *subsb;
	struct inode *subi;
	struct vfsmount *submnt;

	ENTER(sb);

	if (subfs_check_disk_change(sb))
		goto out;

	submnt = subfs_prevent_umount(sb);
	if (!submnt)
		goto out;

	subi = get_subfs_inode(inode);
	if (IS_ERR(subi))
		goto allow_umount;

	subsb = subfs_get_sb(sb);
	if (!sb)
		goto put_subi;

	if (subsb->s_op && subsb->s_op->write_inode) {
		if (subfs_get_access(inode, 1))
			goto put_subi;

		write_inode_now(subi, sync);

		subfs_put_access(inode, 1);
	}
put_subi:
	iput(subi);
allow_umount:
	subfs_allow_umount(sb, submnt);
out:
	LEAVE(sb);

	return;
}

/*
 * FIXME
 * subfs_umount has no business here
 * it should be moved into umount_begin; in this case force umount will
 * free subfs (and give false No medium as error ... oh, well)
 */
static void
supermount_put_super(struct super_block *sb)
{
	struct supermount_sb_info *sbi = supermount_sbi(sb);

	ENTER(sb);

	subfs_lock(sb);
	if (subfs_is_mounted(sb))
		subfs_umount(sb, SUBFS_UMNT_NORMAL);
	subfs_unlock(sb);

	supermount_proc_remove(sbi);

	LEAVE(sb);

	sb->s_fs_info = 0;
	free_sbi(sbi);
}

/*
 * The following has to be done in two steps (unfortunately)
 * First make sure iput(subi) is run just once - and then put
 * read/write access and finally remove inode from list
 *
 * We can't do it in one shot because removing inode from list
 * will remove also possibility to mark it stale. It has been 
 * introduced by me :( removing generation numbers. OTOH so far
 * it is the only place that needs extra treatment because of it.
 */
static void
supermount_clear_inode(struct inode *inode)
{
	struct supermount_inode_info *sii = supermount_i(inode);
	struct super_block *sb = inode->i_sb;
	struct inode *subi;
	struct vfsmount *mnt;

	ENTER(sb, "inode=%p", inode);

	mnt = subfs_prevent_umount(sb);
	if (!mnt)
		goto out;

	subfs_lock(sb);
	subi = sii->inode;
	sii->inode = 0;
	subfs_unlock(sb);


	if (subi) {
		/*
		 * we used to check for subi->i_count != 1 here.
		 * This does not actually work - it is quite possible
		 * that inode has been looked up while we were in this
		 * function. So just ignore it (the worst thing that
		 * may happen is that subfs cannot be remounted)
		 */

		iput(subi);

	}
	subfs_allow_umount(sb, mnt);

	/*
	 * This does not has much to do with subfs but I did not want
	 * to export __ functions
	 */
	subfs_clear_inode(inode);
out:
	LEAVE(sb, "inode=%p", inode);
}
/*
 * FIXME why it is needed?
 */

static void
supermount_write_super(struct super_block *sb)
{
	struct vfsmount *mnt;

	ENTER(sb);

	if (subfs_check_disk_change(sb))
		goto out;

	if (subfs_is_rw(sb)) {
		struct super_block *subsb;

		mnt = subfs_prevent_umount(sb);
		if (!mnt)
			goto out;

		subsb = subfs_get_sb(sb);
		if (subsb && subsb->s_op && subsb->s_op->write_super)
			subsb->s_op->write_super(subsb);

		subfs_allow_umount(sb, mnt);
	}

out:
	LEAVE(sb);

	return;
}

static int
supermount_statfs(struct super_block *sb, struct kstatfs *buf)
{
	int rc = 0;
	struct super_block *subsb;
	struct vfsmount *mnt;

	ENTER(sb);

	(void)subfs_check_disk_change(sb);

	mnt = subfs_prevent_umount(sb);
	if (!mnt)
		goto out;

	subsb = subfs_get_sb(sb);
	if (subsb && subsb->s_op && subsb->s_op->statfs)
		rc = subsb->s_op->statfs(subsb, buf);
	if (!rc)
		buf->f_type = SUPERMOUNT_SUPER_MAGIC;

	subfs_allow_umount(sb, mnt);
out:
	LEAVE(sb, "rc=%d", rc);

	return rc;
}

static int
supermount_remount_fs(struct super_block *sb, int *flags, char *data)
{
	return -ENOSYS;
}

/*
 * based on fs/ntfs/inode.c:ntfs_show_options
 */
static int
supermount_show_options(struct seq_file *sf, struct vfsmount *mnt)
{
	struct supermount_sb_info *sbi = supermount_sbi(mnt->mnt_sb);

	seq_printf(sf, ",dev=%s", sbi->devname);
	seq_puts(sf, ",fs=");
	if (sbi->s_type == default_fs_types)
		seq_puts(sf, "auto");
	else 
		seq_puts(sf, sbi->s_type);
	seq_puts(sf, ",tray_lock=");
	if (sbi->tray_lock == TRAY_LOCK_ALWAYS)
		seq_puts(sf, "always");
	else if (sbi->tray_lock == TRAY_LOCK_NEVER)
		seq_puts(sf, "never");
	else if (sbi->tray_lock == TRAY_LOCK_ONWRITE)
		seq_puts(sf, "onwrite");
	else
		SUPERMOUNT_BUG_ON(1);

	if (sbi->s_debug)
		seq_printf(sf, ",debug=0x%lx", sbi->s_debug);
	if (sbi->s_data)
		seq_printf(sf, ",--,%s", sbi->s_data);
	return 0;
}

/*
 * ->read_inode:	not needed
 * ->dirty_inode:	probably not needed. It appears VFS layer never
 *  			calls mark_inode_dirty itself; exception is
 *  			UPDATE_ATIME and it is already handled specially
 *  			FIXME
 *  			It may be needed for knfsd and similar
 * ->put_inode:		not needed
 * ->delete_inode:	not needed
 * ->write_super:	FIXME not needed, we do not have any backing store
 * ->sync_fs:		not needed
 * ->write_super_lockfs:not needed
 * ->unlockfs:		not needed
 * ->umount_begin:	TODO maybe to move subfs_umount aways from put_super
 * ->fh_to_dentry:	TODO may be
 * ->dentry_to_fh:	TODO may be
 */
static struct super_operations supermount_sops = {
	.alloc_inode	= supermount_alloc_inode,
	.destroy_inode	= supermount_destroy_inode,
	.write_inode	= supermount_write_inode,
	.clear_inode	= supermount_clear_inode,
	.put_super	= supermount_put_super,
	.write_super	= supermount_write_super,
	.statfs		= supermount_statfs,
	.remount_fs	= supermount_remount_fs,
	.show_options	= supermount_show_options,
};




#ifndef _SUPERMOUNT_I_H
#define _SUPERMOUNT_I_H

/*
 *  $Id: 4715_supermount-2.0.4-2.6.7.patch,v 1.1 2004/06/22 22:15:04 gregkh Exp $
 */

#include <linux/module.h>
#include <linux/version.h>

#include <linux/slab.h>
#include <linux/sched.h>
#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/list.h>
#include <linux/file.h>
#include <linux/mm.h>
#include <linux/poll.h>
#include <linux/smp_lock.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/dnotify.h>
#include <linux/mount.h>
#include <linux/moduleparam.h>
#include <linux/genhd.h>
#include <linux/namei.h>
#include <linux/supermount_media.h>

#ifdef CONFIG_SUPERMOUNT_DEBUG
#define SUPERMOUNT_DEBUG
#endif
/*
 * The supermount superblock magic number
 */

#define SUPERMOUNT_SUPER_MAGIC	0x9fa1
#define SUPERMOUNT_VERSION		"2.0.4"

#define S_DBG_DEBUG			0x001
#define S_DBG_TRACE_DENTRY		0x002
#define S_DBG_TRACE_FILE		0x004
#define S_DBG_TRACE_FILEMAP		0x008
#define S_DBG_TRACE_MEDIACTL		0x010
#define S_DBG_TRACE_NAMEI		0x020
#define S_DBG_TRACE_SUBFS		0x040
#define S_DBG_TRACE_SUPER		0x080

/*
 * The subfs umount reason
 */
#define SUBFS_UMNT_NORMAL		0 /* normal umount */
#define SUBFS_UMNT_MEDIA		1 /* media change detected */
#define SUBFS_UMNT_USER			2 /* user request */

/*
 * When to lock media
 */
#define TRAY_LOCK_NEVER			0
#define TRAY_LOCK_ONWRITE		1
#define TRAY_LOCK_ALWAYS		2

extern struct file_system_type supermount_fs_type;

#ifdef SUPERMOUNT_DEBUG

#define SUPERMOUNT_BUG_ON(x) BUG_ON(x)
#define SUPERMOUNT_BUG_LOCKED_ON(sb, x) \
do { \
	if (x) { \
		subfs_unlock(sb); \
		BUG(); \
	} \
} while (0)

#define supermount_debug(sb, args...) \
do { \
	struct supermount_sb_info *sbi = supermount_sbi(sb); \
	char *dev = sbi->devname ? sbi->devname : "unknown"; \
\
	if (supermount_dbg(sb, S_DBG_DEBUG)) { \
		printk("%sSUPERMOUNT DEBUG [dev=%s] <%s:%d> ", \
			KERN_DEBUG, dev, __FUNCTION__, __LINE__); \
		printk(args); \
		printk("\n"); \
	} \
} while(0)

#define ENTER(sb, args...) \
do { \
	struct supermount_sb_info *sbi = supermount_sbi(sb); \
	char *dev = sbi->devname ? sbi->devname : "unknown"; \
\
	if (supermount_dbg(sb, S_DBG_TRACE_CURRENT)) { \
		printk("%sSUPERMOUNT TRACE [dev=%s] PID=%lu ENTER %s", \
			KERN_DEBUG, dev, (unsigned long)current->pid, \
			__FUNCTION__); \
		printk(" " args); \
		printk("\n"); \
	} \
} while (0)

#define LEAVE(sb, args...) \
do { \
	struct supermount_sb_info *sbi = supermount_sbi(sb); \
	char *dev = sbi->devname ? sbi->devname : "unknown"; \
\
	if (supermount_dbg(sb, S_DBG_TRACE_CURRENT)) { \
		printk("%sSUPERMOUNT TRACE [dev=%s] PID=%lu LEAVE %s", \
			KERN_DEBUG, dev, (unsigned long)current->pid, \
			__FUNCTION__); \
		printk(" " args); \
		printk("\n"); \
	} \
} while (0)

#else /* SUPERMOUNT_DEBUG */
#define supermount_debug(f, a...) /**/
#define SUPERMOUNT_BUG_ON(x) do { } while (0)
#define SUPERMOUNT_BUG_LOCKED_ON(sb, x) do { } while (0)

#define ENTER(sb, args...) do { (void)sb; } while (0)
#define LEAVE(sb, args...) do { (void)sb; } while (0)
#endif				/* SUPERMOUNT_DEBUG */

#define supermount_warning(sb, ...) \
do { \
	struct supermount_sb_info *sbi = supermount_sbi(sb); \
	char *dev = sbi->devname ? sbi->devname : "unknown"; \
\
	printk("%sSUPERMOUNT WARNING [dev=%s] ", KERN_WARNING, dev); \
	printk(__VA_ARGS__); \
	printk("\n"); \
} while(0)

#define supermount_error(sb, ...) \
do { \
	struct supermount_sb_info *sbi = supermount_sbi(sb); \
	char *dev = sbi->devname ? sbi->devname : "unknown"; \
\
	printk("%sSUPERMOUNT ERROR [dev=%s] ", KERN_ERR, dev); \
	printk(__VA_ARGS__); \
	printk("\n"); \
} while(0)

/*
 * The following is drived from fs/inode.c:update_atime()
 */
#define NEED_WRITE_ATIME(inode) \
	(!(IS_NOATIME(inode) || \
	 (IS_NODIRATIME(inode) && S_ISDIR(inode->i_mode)) || \
	 IS_RDONLY(inode)))


/*
 * supermount super-block data in memory
 */
struct supermount_sb_info;
struct supermount_sb_info {
	/* == options == */
	unsigned long s_debug;	/* debug flags S_DBG_* */
	char *s_type;		/* Type of fs to be sub-mounted */
	char *devname;		/* Where to mount the subfs from */
	char *s_data;		/* Data to pass when mounting subfs */
	/* == end of options == */
	struct vfsmount *s_undermount;
				/* Mount point for subfs */
	int readcount;		/* Refcount of read access
				   on the filesystem */
	int writecount;		/* Refcount of write access
				   on the filesystem */
	int lockcount;		/* Refcount of requests to lock tray */
	struct list_head s_inodes;
				/* list of active inodes */
	struct list_head s_files;
				/* list of active files */
	struct list_head s_dentries;
				/* list of active dentries */
	struct semaphore sem;
	struct super_block *host;
				/* needed for procfs support */
	struct supermount_sb_info *next;
				/* list of all supermount fs */
	unsigned int tray_lock:2;
	unsigned int disabled:1;
	unsigned int rw:1;
};

static inline struct supermount_sb_info *
supermount_sbi(struct super_block *sb)
{
	struct supermount_sb_info *sbi;
	BUG_ON(!sb);
	BUG_ON(sb->s_type != &supermount_fs_type);

	sbi = (struct supermount_sb_info *) (sb->s_fs_info);
	BUG_ON(!sbi);

	return sbi;
}

static inline struct vfsmount *
subfs_mnt(struct super_block *sb)
{
	return supermount_sbi(sb)->s_undermount;
}

static inline struct super_block *
subfs_sb(struct super_block *sb)
{
	struct vfsmount *mnt = subfs_mnt(sb);

	if (mnt) return mnt->mnt_sb;

	return 0;
}

/* this is expected to run under sb->sem */
static inline int
subfs_is_mounted(struct super_block *sb)
{
	struct supermount_sb_info *sbi = supermount_sbi(sb);

	return sbi->s_undermount != 0;
}

/* this is expected to run under sb->sem */
static inline int
subfs_is_busy(struct super_block *sb)
{
	struct vfsmount *mnt = subfs_mnt(sb);

	/*
	 * In "normal" case mnt_count is 2. But we currently do
	 * not insert subfs into task namespace so count is 1
	 * FIXME
	 * This also means we do not do_umount i.e. do not run
	 * either umount_begin or DQUOT_OFF for subfs.
	 */
	if (mnt) return atomic_read(&mnt->mnt_count) > 1;

	return 0;
}

/* this is expected to run under sb->sem */
static inline int
subfs_is_rw(struct super_block *sb)
{
	struct super_block *subsb;

	if (!subfs_is_mounted(sb))
		return 0;
	
	subsb = subfs_sb(sb);
	return !(subsb->s_flags & MS_RDONLY);
}

static inline void
subfs_lock(struct super_block *sb)
{
	struct supermount_sb_info *sbi = supermount_sbi(sb);

	down(&sbi->sem);
}

static inline void
subfs_unlock(struct super_block *sb)
{
	struct supermount_sb_info *sbi = supermount_sbi(sb);

	up(&sbi->sem);
}

/*
 * query debug flags set
 */
static inline int supermount_dbg(struct super_block *sb, unsigned long flags)
{
	struct supermount_sb_info *sbi = supermount_sbi(sb);

	return sbi->s_debug & flags;
}

/*
 * supermount inode info
 */

struct supermount_inode_info {
	struct list_head list;
  	struct inode *inode;	/* subfs inode */
	int readcount;
	int writecount;
	struct inode vfs_inode;	/* superfs inode */
};

static inline int
is_inode_supermounted(struct inode *inode)
{
	return inode && inode->i_sb && inode->i_sb->s_type == &supermount_fs_type;
}

static inline struct supermount_inode_info *
supermount_i(struct inode *inode)
{
	SUPERMOUNT_BUG_ON(!is_inode_supermounted(inode));

	return list_entry(inode, struct supermount_inode_info, vfs_inode);
}

static inline int
is_inode_obsolete(struct inode *inode)
{
	struct supermount_inode_info *sii = supermount_i(inode);

	return sii->inode == 0;
}

static inline void
supermount_list_add_inode(struct inode *inode)
{
	struct supermount_inode_info *sii = supermount_i(inode);

	list_add(&(sii->list), &(supermount_sbi(inode->i_sb)->s_inodes));
}

/*
 * FIXME
 * Should we propagate all flags? *_QUOTA looks very possible candidate
 * We can't just assign them because other flags may be set by VFS
 */
#define SMNT_INODE_FLAGS (S_IMMUTABLE|S_NOATIME|S_APPEND|S_SYNC)
static inline void
set_inode_flags(struct inode *inode, struct inode *subi)
{
	inode->i_flags &= ~SMNT_INODE_FLAGS;
	if (subi)
		inode->i_flags |= (subi->i_flags & SMNT_INODE_FLAGS);
}

/*
 * supermount dentry info
 */

struct supermount_dentry_info {
	struct list_head list;
	struct dentry *dentry;
	struct dentry *host;
};

static inline int
is_dentry_supermounted(struct dentry *dentry)
{
	return (dentry && dentry->d_sb && dentry->d_sb->s_type == &supermount_fs_type);
}

static inline struct supermount_dentry_info *
supermount_d(struct dentry *dentry)
{
	SUPERMOUNT_BUG_ON(!is_dentry_supermounted(dentry));
	SUPERMOUNT_BUG_ON(!dentry->d_fsdata);

	return  (struct supermount_dentry_info *)dentry->d_fsdata;
}

static inline int
is_dentry_obsolete(struct dentry *dentry)
{
	struct supermount_dentry_info *sdi = supermount_d(dentry);

	return sdi->dentry == 0;
}

/*
 * Supermount file info 
 */

struct supermount_file_info {
	struct list_head	list;
	struct file *		host;
	struct file		*file;
	pid_t			owner;
	struct vm_operations_struct *vm_ops;
	unsigned int		fake:1;
};

static inline int
is_file_supermounted(struct file *file)
{
	return file && file->f_dentry && is_dentry_supermounted(file->f_dentry);
}

static inline struct supermount_file_info *
supermount_f(struct file *file)
{
	SUPERMOUNT_BUG_ON(!is_file_supermounted(file));
	SUPERMOUNT_BUG_ON(!file->f_supermount);

	return  file->f_supermount;
}

static inline int
is_file_obsolete(struct file *file)
{
	struct supermount_file_info *sfi = supermount_f(file);

	return sfi->file == NULL;
}

static inline int
is_file_fake(struct file *file)
{
	struct supermount_file_info *sfi = supermount_f(file);

	return sfi->fake;
}

/* dentry.c */
extern rwlock_t d_compare_lock;
extern struct dentry_operations supermount_dops;
extern int init_dentry_info(struct dentry *);
extern void attach_subfs_dentry(struct dentry *, struct dentry *);
extern struct dentry *get_subfs_dentry(struct dentry *dentry);
 
/* file.c */
extern struct file_operations supermount_dir_operations;
extern struct file_operations supermount_file_operations;

/* filemap.c */
extern struct vm_operations_struct supermount_vm_ops;
extern int supermount_file_mmap(struct file *, struct vm_area_struct *);
extern struct file *get_subfs_file(struct file*);

/* mediactl.c */
extern void supermount_mediactl(struct super_block *, int, int);
static inline void
supermount_lock_door(struct super_block *sb)
{
	supermount_mediactl(sb, MEDIA_LOCK, 1);
}
static inline void
supermount_unlock_door(struct super_block *sb)
{
	supermount_mediactl(sb, MEDIA_UNLOCK, 1);
}

static inline void
mark_media_supermounted(struct super_block *sb)
{
	supermount_mediactl(sb, SUPERMOUNT_INC_COUNT, 0);
	supermount_mediactl(sb, MEDIA_UNLOCK, 0);
}

static inline void
unmark_media_supermounted(struct super_block *sb)
{
	supermount_mediactl(sb, SUPERMOUNT_DEC_COUNT, 0);
}

/* namei.c */
extern struct inode_operations supermount_dir_iops;
extern struct inode_operations supermount_file_iops;
extern struct inode_operations supermount_symlink_iops;
extern struct inode *create_supermount_inode(struct super_block *);
extern struct inode *get_subfs_inode(struct inode *inode);

/* proc.c */
#ifdef CONFIG_PROC_FS
extern void supermount_proc_register(void);
extern void supermount_proc_unregister(void);
extern void supermount_proc_insert(struct supermount_sb_info *);
extern void supermount_proc_remove(struct supermount_sb_info *);
#else
#define supermount_proc_register() do { } while(0)
#define supermount_proc_unregister() do { } while(0)
#define supermount_proc_insert(sbi) do { } while(0)
#define supermount_proc_remove(sbi) do { } while(0)
#endif

/* subfs.c */
extern void subfs_umount(struct super_block *sb, int);
extern struct vfsmount *subfs_go_online(struct super_block *);
extern void subfs_go_offline(struct super_block *, struct vfsmount *);
extern int subfs_get_access(struct inode *, int);
extern void subfs_put_access(struct inode *, int);
extern int subfs_check_disk_change(struct super_block *);
extern struct vfsmount *subfs_prevent_umount(struct super_block *);
extern void subfs_allow_umount(struct super_block *, struct vfsmount *);
extern struct vfsmount *subfs_get_mnt(struct super_block *sb);
extern struct super_block *subfs_get_sb(struct super_block *sb);
extern void subfs_clear_inode(struct inode *);

/* super.c */
extern struct super_block *supermount_get_sb(struct file_system_type *, int, const char *, void *);
extern void attach_subfs_inode(struct inode *, struct inode *);
extern void supermount_init_root_inode(struct inode *);
extern char *strdup(const char *);

#endif				/* _SUPERMOUNT_I_H */

Lines 278-284 Link Here

(-)linux-2.6.8.1_supermount/fs/udf/super.c (-1 / +7 lines)
278	Opt_gid, Opt_uid, Opt_umask, Opt_session, Opt_lastblock,	278	Opt_gid, Opt_uid, Opt_umask, Opt_session, Opt_lastblock,
279	Opt_anchor, Opt_volume, Opt_partition, Opt_fileset,	279	Opt_anchor, Opt_volume, Opt_partition, Opt_fileset,
280	Opt_rootdir, Opt_utf8, Opt_iocharset,	280	Opt_rootdir, Opt_utf8, Opt_iocharset,
281	Opt_err	281	Opt_ignore, Opt_err
282	};	282	};
283		283
284	static match_table_t tokens = {	284	static match_table_t tokens = {
Lines 303-308 Link Here
303	{Opt_rootdir, "rootdir=%u"},	303	{Opt_rootdir, "rootdir=%u"},
304	{Opt_utf8, "utf8"},	304	{Opt_utf8, "utf8"},
305	{Opt_iocharset, "iocharset=%s"},	305	{Opt_iocharset, "iocharset=%s"},
		306	#if defined(CONFIG_SUPERMOUNT) \|\| defined(CONFIG_SUPERMOUNT_MODULE)
		307	/* Silently ignore NLS option */
		308	{Opt_ignore, "codepage"},
		309	#endif
306	{Opt_err, NULL}	310	{Opt_err, NULL}
307	};	311	};
308		312
Lines 423-428 Link Here
423	uopt->flags \|= (1 << UDF_FLAG_NLS_MAP);	427	uopt->flags \|= (1 << UDF_FLAG_NLS_MAP);
424	break;	428	break;
425	#endif	429	#endif
		430	case Opt_ignore:
		431	break;
426	default:	432	default:
427	printk(KERN_ERR "udf: bad mount option \"%s\" "	433	printk(KERN_ERR "udf: bad mount option \"%s\" "
428	"or missing value\n", p);	434	"or missing value\n", p);

Lines 987-992 Link Here

(-)linux-2.6.8.1_supermount/include/linux/cdrom.h (+3 lines)
987	extern int cdrom_ioctl(struct file file, struct cdrom_device_info cdi,	987	extern int cdrom_ioctl(struct file file, struct cdrom_device_info cdi,
988	struct inode *ip, unsigned int cmd, unsigned long arg);	988	struct inode *ip, unsigned int cmd, unsigned long arg);
989	extern int cdrom_media_changed(struct cdrom_device_info *);	989	extern int cdrom_media_changed(struct cdrom_device_info *);
		990	#if defined(CONFIG_SUPERMOUNT) \|\| defined(CONFIG_SUPERMOUNT_MODULE)
		991	extern int cdrom_mediactl(struct cdrom_device_info , struct block_device , int, int);
		992	#endif
990		993
991	extern int register_cdrom(struct cdrom_device_info *cdi);	994	extern int register_cdrom(struct cdrom_device_info *cdi);
992	extern int unregister_cdrom(struct cdrom_device_info *cdi);	995	extern int unregister_cdrom(struct cdrom_device_info *cdi);

Lines 96-101 Link Here

(-)linux-2.6.8.1_supermount/include/linux/fs.h (+14 lines)
96	/* public flags for file_system_type */	96	/* public flags for file_system_type */
97	#define FS_REQUIRES_DEV 1	97	#define FS_REQUIRES_DEV 1
98	#define FS_BINARY_MOUNTDATA 2	98	#define FS_BINARY_MOUNTDATA 2
		99	#define FS_NO_SUBMNT 64 /* Prevent mounting over this filesystem */
99	#define FS_REVAL_DOT 16384 /* Check the paths ".", ".." for staleness */	100	#define FS_REVAL_DOT 16384 /* Check the paths ".", ".." for staleness */
100	#define FS_ODD_RENAME 32768 /* Temporary stuff; will go away as soon	101	#define FS_ODD_RENAME 32768 /* Temporary stuff; will go away as soon
101	* as nfs_rename() will be cleaned up	102	* as nfs_rename() will be cleaned up
Lines 119-124 Link Here
119	#define MS_VERBOSE 32768	120	#define MS_VERBOSE 32768
120	#define MS_POSIXACL (1<<16) /* VFS does not apply the umask */	121	#define MS_POSIXACL (1<<16) /* VFS does not apply the umask */
121	#define MS_ONE_SECOND (1<<17) /* fs has 1 sec a/m/ctime resolution */	122	#define MS_ONE_SECOND (1<<17) /* fs has 1 sec a/m/ctime resolution */
		123	#define MS_SUPERMOUNTED (1<<18)
122	#define MS_ACTIVE (1<<30)	124	#define MS_ACTIVE (1<<30)
123	#define MS_NOUSER (1<<31)	125	#define MS_NOUSER (1<<31)
124		126
Lines 587-592 Link Here
587	spinlock_t f_ep_lock;	589	spinlock_t f_ep_lock;
588	#endif /* #ifdef CONFIG_EPOLL */	590	#endif /* #ifdef CONFIG_EPOLL */
589	struct address_space *f_mapping;	591	struct address_space *f_mapping;
		592
		593	#if defined(CONFIG_SUPERMOUNT) \|\| defined(CONFIG_SUPERMOUNT_MODULE)
		594	/* Used by supermount. Use(fullness) unconfirmed */
		595	void *f_supermount;
		596	#endif
590	};	597	};
591	extern spinlock_t files_lock;	598	extern spinlock_t files_lock;
592	#define file_list_lock() spin_lock(&files_lock);	599	#define file_list_lock() spin_lock(&files_lock);
Lines 771-776 Link Here
771	* even looking at it. You had been warned.	778	* even looking at it. You had been warned.
772	*/	779	*/
773	struct semaphore s_vfs_rename_sem; /* Kludge */	780	struct semaphore s_vfs_rename_sem; /* Kludge */
		781	#if defined(CONFIG_SUPERMOUNT) \|\| defined(CONFIG_SUPERMOUNT_MODULE)
		782	atomic_t s_media_changed;
		783	#endif
		784
774	};	785	};
775		786
776	/*	787	/*
Lines 840-845 Link Here
840	int (ioctl) (struct inode , struct file *, unsigned, unsigned long);	851	int (ioctl) (struct inode , struct file *, unsigned, unsigned long);
841	int (media_changed) (struct gendisk );	852	int (media_changed) (struct gendisk );
842	int (revalidate_disk) (struct gendisk );	853	int (revalidate_disk) (struct gendisk );
		854	#if defined(CONFIG_SUPERMOUNT) \|\| defined(CONFIG_SUPERMOUNT_MODULE)
		855	int (mediactl) (struct block_device , int, int);
		856	#endif
843	struct module *owner;	857	struct module *owner;
844	};	858	};
845		859

Lines 108-113 Link Here

(-)linux-2.6.8.1_supermount/include/linux/genhd.h (+3 lines)
108	#else	108	#else
109	struct disk_stats dkstats;	109	struct disk_stats dkstats;
110	#endif	110	#endif
		111	#if defined(CONFIG_SUPERMOUNT) \|\| defined(CONFIG_SUPERMOUNT_MODULE)
		112	int scount; /* number of supermounted partitions */
		113	#endif
111	};	114	};
112		115
113	/*	116	/*




#if defined(CONFIG_SUPERMOUNT) || defined(CONFIG_SUPERMOUNT_MODULE)

/*
 * These are the "op" operation codes for mediactl() media control
 * calls for device special files
 */
enum {
	MEDIA_LOCK = 1234,	/* Lock the drive door */
	MEDIA_UNLOCK,		/* Unlock the drive door */
	SUPERMOUNT_INC_COUNT,
	SUPERMOUNT_DEC_COUNT,
};

static inline int
supermount_usage_count(struct block_device *bdev, int count)
{
	if (bdev) {
		count -= bdev->bd_disk->scount;
		if (count < 0)
			count = 0;
	}
	return count;
}

static inline int
dev_is_supermounted(struct block_device *bdev)
{
	return bdev ? bdev->bd_disk->scount > 0 : 0;
}

#else /* CONFIG_SUPERMOUNT */

static inline int
supermount_usage_count(struct block_device *bdev, int count)
{
	(void)bdev; // make compiler happy
	return count;
}

static inline int
dev_is_supermounted(struct block_device *bdev)
{
	(void)bdev; // make compiler happy
	return 0;
}

#endif /* CONFIG_SUPERMOUNT */

Return to bug 60462

Lines 3173-3178 Link Here

(-)linux-2.6.8.1_supermount/drivers/cdrom/cdu31a.c (+29 lines)
3173		3173
3174	static int scd_block_release(struct inode inode, struct file file)	3174	static int scd_block_release(struct inode inode, struct file file)
3175	{	3175	{
		3176	#if defined(CONFIG_SUPERMOUNT) \|\| defined(CONFIG_SUPERMOUNT_MODULE)
		3177	/*
		3178	* This is the same sort of clockload as use in blkdev_get.
		3179	* We need information whether device is supermounted inside
		3180	* of cdrom_release to decide if tray must be unlocked.
		3181	* This information so far is available only by looking
		3182	* up superblock but it needs struct *bdev and it is not
		3183	* available in cdrom_release anymore
		3184	*/
		3185	struct dentry t_dentry;
		3186	struct file t_file;
		3187
		3188	if (!file) {
		3189	t_file.f_dentry = &t_dentry;
		3190	t_dentry.d_inode = inode;
		3191	file = &t_file;
		3192	}
		3193	#endif
		3194
3176	return cdrom_release(&scd_info, file);	3195	return cdrom_release(&scd_info, file);
3177	}	3196	}
3178		3197
Lines 3187-3192 Link Here
3187	return cdrom_media_changed(&scd_info);	3206	return cdrom_media_changed(&scd_info);
3188	}	3207	}
3189		3208
		3209	#if defined(CONFIG_SUPERMOUNT) \|\| defined(CONFIG_SUPERMOUNT_MODULE)
		3210	static int scd_block_mediactl(struct block_device *bdev, int op, int arg)
		3211	{
		3212	return cdrom_mediactl(&scd_info, bdev, op, arg);
		3213	}
		3214	#endif
		3215
3190	struct block_device_operations scd_bdops =	3216	struct block_device_operations scd_bdops =
3191	{	3217	{
3192	.owner = THIS_MODULE,	3218	.owner = THIS_MODULE,
Lines 3194-3199 Link Here
3194	.release = scd_block_release,	3220	.release = scd_block_release,
3195	.ioctl = scd_block_ioctl,	3221	.ioctl = scd_block_ioctl,
3196	.media_changed = scd_block_media_changed,	3222	.media_changed = scd_block_media_changed,
		3223	#if defined(CONFIG_SUPERMOUNT) \|\| defined(CONFIG_SUPERMOUNT_MODULE)
		3224	.mediactl = scd_block_mediactl,
		3225	#endif
3197	};	3226	};
3198		3227
3199	static struct gendisk *scd_gendisk;	3228	static struct gendisk *scd_gendisk;

Lines 1357-1362 Link Here

(-)linux-2.6.8.1_supermount/drivers/cdrom/cm206.c (+29 lines)
1357		1357
1358	static int cm206_block_release(struct inode inode, struct file file)	1358	static int cm206_block_release(struct inode inode, struct file file)
1359	{	1359	{
		1360	#if defined(CONFIG_SUPERMOUNT) \|\| defined(CONFIG_SUPERMOUNT_MODULE)
		1361	/*
		1362	* This is the same sort of clockload as use in blkdev_get.
		1363	* We need information whether device is supermounted inside
		1364	* of cdrom_release to decide if tray must be unlocked.
		1365	* This information so far is available only by looking
		1366	* up superblock but it needs struct *bdev and it is not
		1367	* available in cdrom_release anymore
		1368	*/
		1369	struct dentry t_dentry;
		1370	struct file t_file;
		1371
		1372	if (!file) {
		1373	t_file.f_dentry = &t_dentry;
		1374	t_dentry.d_inode = inode;
		1375	file = &t_file;
		1376	}
		1377	#endif
		1378
1360	return cdrom_release(&cm206_info, file);	1379	return cdrom_release(&cm206_info, file);
1361	}	1380	}
1362		1381
Lines 1371-1376 Link Here
1371	return cdrom_media_changed(&cm206_info);	1390	return cdrom_media_changed(&cm206_info);
1372	}	1391	}
1373		1392
		1393	#if defined(CONFIG_SUPERMOUNT) \|\| defined(CONFIG_SUPERMOUNT_MODULE)
		1394	static int cm206_block_mediactl(struct block_device *bdev, int op, int arg)
		1395	{
		1396	return cdrom_mediactl(&cm206_info, bdev, op, arg);
		1397	}
		1398	#endif
		1399
1374	static struct block_device_operations cm206_bdops =	1400	static struct block_device_operations cm206_bdops =
1375	{	1401	{
1376	.owner = THIS_MODULE,	1402	.owner = THIS_MODULE,
Lines 1378-1383 Link Here
1378	.release = cm206_block_release,	1404	.release = cm206_block_release,
1379	.ioctl = cm206_block_ioctl,	1405	.ioctl = cm206_block_ioctl,
1380	.media_changed = cm206_block_media_changed,	1406	.media_changed = cm206_block_media_changed,
		1407	#if defined(CONFIG_SUPERMOUNT) \|\| defined(CONFIG_SUPERMOUNT_MODULE)
		1408	.mediactl = cm206_block_mediactl,
		1409	#endif
1381	};	1410	};
1382		1411
1383	static struct gendisk *cm206_gendisk;	1412	static struct gendisk *cm206_gendisk;

Lines 221-226 Link Here

(-)linux-2.6.8.1_supermount/drivers/cdrom/mcd.c (+29 lines)
221		221
222	static int mcd_block_release(struct inode inode, struct file file)	222	static int mcd_block_release(struct inode inode, struct file file)
223	{	223	{
		224	#if defined(CONFIG_SUPERMOUNT) \|\| defined(CONFIG_SUPERMOUNT_MODULE)
		225	/*
		226	* This is the same sort of clockload as use in blkdev_get.
		227	* We need information whether device is supermounted inside
		228	* of cdrom_release to decide if tray must be unlocked.
		229	* This information so far is available only by looking
		230	* up superblock but it needs struct *bdev and it is not
		231	* available in cdrom_release anymore
		232	*/
		233	struct dentry t_dentry;
		234	struct file t_file;
		235
		236	if (!file) {
		237	t_file.f_dentry = &t_dentry;
		238	t_dentry.d_inode = inode;
		239	file = &t_file;
		240	}
		241	#endif
		242
224	return cdrom_release(&mcd_info, file);	243	return cdrom_release(&mcd_info, file);
225	}	244	}
226		245
Lines 235-240 Link Here
235	return cdrom_media_changed(&mcd_info);	254	return cdrom_media_changed(&mcd_info);
236	}	255	}
237		256
		257	#if defined(CONFIG_SUPERMOUNT) \|\| defined(CONFIG_SUPERMOUNT_MODULE)
		258	static int mcd_block_mediactl(struct block_device *bdev, int op, int arg)
		259	{
		260	return cdrom_mediactl(&mcd_info, bdev, op, arg);
		261	}
		262	#endif
		263
238	static struct block_device_operations mcd_bdops =	264	static struct block_device_operations mcd_bdops =
239	{	265	{
240	.owner = THIS_MODULE,	266	.owner = THIS_MODULE,
Lines 242-247 Link Here
242	.release = mcd_block_release,	268	.release = mcd_block_release,
243	.ioctl = mcd_block_ioctl,	269	.ioctl = mcd_block_ioctl,
244	.media_changed = mcd_block_media_changed,	270	.media_changed = mcd_block_media_changed,
		271	#if defined(CONFIG_SUPERMOUNT) \|\| defined(CONFIG_SUPERMOUNT_MODULE)
		272	.mediactl = mcd_block_mediactl,
		273	#endif
245	};	274	};
246		275
247	static struct gendisk *mcd_gendisk;	276	static struct gendisk *mcd_gendisk;

Lines 226-231 Link Here

(-)linux-2.6.8.1_supermount/drivers/cdrom/mcdx.c (+30 lines)
226	static int mcdx_block_release(struct inode inode, struct file file)	226	static int mcdx_block_release(struct inode inode, struct file file)
227	{	227	{
228	struct s_drive_stuff *p = inode->i_bdev->bd_disk->private_data;	228	struct s_drive_stuff *p = inode->i_bdev->bd_disk->private_data;
		229	#if defined(CONFIG_SUPERMOUNT) \|\| defined(CONFIG_SUPERMOUNT_MODULE)
		230	/*
		231	* This is the same sort of clockload as use in blkdev_get.
		232	* We need information whether device is supermounted inside
		233	* of cdrom_release to decide if tray must be unlocked.
		234	* This information so far is available only by looking
		235	* up superblock but it needs struct *bdev and it is not
		236	* available in cdrom_release anymore
		237	*/
		238	struct dentry t_dentry;
		239	struct file t_file;
		240
		241	if (!file) {
		242	t_file.f_dentry = &t_dentry;
		243	t_dentry.d_inode = inode;
		244	file = &t_file;
		245	}
		246	#endif
		247
229	return cdrom_release(&p->info, file);	248	return cdrom_release(&p->info, file);
230	}	249	}
231		250
Lines 242-247 Link Here
242	return cdrom_media_changed(&p->info);	261	return cdrom_media_changed(&p->info);
243	}	262	}
244		263
		264	#if defined(CONFIG_SUPERMOUNT) \|\| defined(CONFIG_SUPERMOUNT_MODULE)
		265	static int mcdx_block_mediactl(struct block_device *bdev, int op, int arg)
		266	{
		267	struct s_drive_stuff *p = bdev->bd_disk->private_data;
		268	return cdrom_mediactl(&p->info, bdev, op, arg);
		269	}
		270	#endif
		271
245	static struct block_device_operations mcdx_bdops =	272	static struct block_device_operations mcdx_bdops =
246	{	273	{
247	.owner = THIS_MODULE,	274	.owner = THIS_MODULE,
Lines 249-254 Link Here
249	.release = mcdx_block_release,	276	.release = mcdx_block_release,
250	.ioctl = mcdx_block_ioctl,	277	.ioctl = mcdx_block_ioctl,
251	.media_changed = mcdx_block_media_changed,	278	.media_changed = mcdx_block_media_changed,
		279	#if defined(CONFIG_SUPERMOUNT) \|\| defined(CONFIG_SUPERMOUNT_MODULE)
		280	.mediactl = mcdx_block_mediactl,
		281	#endif
252	};	282	};
253		283
254		284

Lines 5365-5370 Link Here

(-)linux-2.6.8.1_supermount/drivers/cdrom/sbpcd.c (+30 lines)
5365	static int sbpcd_block_release(struct inode inode, struct file file)	5365	static int sbpcd_block_release(struct inode inode, struct file file)
5366	{	5366	{
5367	struct sbpcd_drive *p = inode->i_bdev->bd_disk->private_data;	5367	struct sbpcd_drive *p = inode->i_bdev->bd_disk->private_data;
		5368	#if defined(CONFIG_SUPERMOUNT) \|\| defined(CONFIG_SUPERMOUNT_MODULE)
		5369	/*
		5370	* This is the same sort of clockload as use in blkdev_get.
		5371	* We need information whether device is supermounted inside
		5372	* of cdrom_release to decide if tray must be unlocked.
		5373	* This information so far is available only by looking
		5374	* up superblock but it needs struct *bdev and it is not
		5375	* available in cdrom_release anymore
		5376	*/
		5377	struct dentry t_dentry;
		5378	struct file t_file;
		5379
		5380	if (!file) {
		5381	t_file.f_dentry = &t_dentry;
		5382	t_dentry.d_inode = inode;
		5383	file = &t_file;
		5384	}
		5385	#endif
		5386
5368	return cdrom_release(p->sbpcd_infop, file);	5387	return cdrom_release(p->sbpcd_infop, file);
5369	}	5388	}
5370		5389
Lines 5381-5386 Link Here
5381	return cdrom_media_changed(p->sbpcd_infop);	5400	return cdrom_media_changed(p->sbpcd_infop);
5382	}	5401	}
5383		5402
		5403	#if defined(CONFIG_SUPERMOUNT) \|\| defined(CONFIG_SUPERMOUNT_MODULE)
		5404	static int sbpcd_block_mediactl(struct block_device *bdev, int op, int arg)
		5405	{
		5406	struct sbpcd_drive *p = bdev->bd_disk->private_data;
		5407	return cdrom_mediactl(p->sbpcd_infop, bdev, op, arg);
		5408	}
		5409	#endif
		5410
5384	static struct block_device_operations sbpcd_bdops =	5411	static struct block_device_operations sbpcd_bdops =
5385	{	5412	{
5386	.owner = THIS_MODULE,	5413	.owner = THIS_MODULE,
Lines 5388-5393 Link Here
5388	.release = sbpcd_block_release,	5415	.release = sbpcd_block_release,
5389	.ioctl = sbpcd_block_ioctl,	5416	.ioctl = sbpcd_block_ioctl,
5390	.media_changed = sbpcd_block_media_changed,	5417	.media_changed = sbpcd_block_media_changed,
		5418	#if defined(CONFIG_SUPERMOUNT) \|\| defined(CONFIG_SUPERMOUNT_MODULE)
		5419	.mediactl = sbpcd_block_mediactl,
		5420	#endif
5391	};	5421	};
5392	/==========================================================================/	5422	/==========================================================================/
5393	/*	5423	/*

Line 0 Link Here

(-)linux-2.6.8.1_supermount/Documentation/filesystems/supermount.txt (+250 lines)
		1	Supermount README
		2	=================
		3
		4	Running supermount
		5	------------------
		6
		7	To run supermount, compile and install a kernel with the supermount
		8	patches and select "Y" to the question
		9
		10	Supermount removable media support (CONFIG_SUPERMOUNT) [Y/n/?]
		11
		12	when you run "make config". You mount a supermount filesystem with
		13	the normal mount command, using the syntax
		14
		15	mount -t supermount -o <superfs-options>,--,<subfs-options> none <mpt>
		16
		17	or by adding correpsonding line to /etc/fstab
		18
		19	none <mpt> supermount <superfs-options>,--,<subfs-options> 0 0
		20
		21	where
		22
		23	<superfs-options> are the options you want to pass to supermount
		24	itself. These are described below.
		25
		26	<subfs-options> are the options you want supermount to pass to the
		27	dismountable filesystem underneath.
		28
		29	<mpt> is the mount point where you want your removable media to be
		30	mounted.
		31
		32	WARNING: in the above description `none' is literal word. While device
		33	is ignored by supermount itself, using real files in this place (real
		34	device name or mount point directory name) is known to cause problems.
		35	Some programs - fuser is one of them - will try to descend into filesystem
		36	if dev can be statted, thus making supermount to attempt to access media.
		37	This is annoying at best - in the worst case it can take very long time
		38	during startup or shutdown.
		39
		40	Notice that you do not directly specify the block device you are going
		41	to mount on the mount command line. This is because the supermount
		42	filesystem is NOT connected to a block device; rather, supermount is
		43	responsible for connecting a separate filesystem to the block device.
		44	You specify the sub-filesystem and block device name by providing the
		45	<superfs-options> field, where the following options are currently
		46	recognised:
		47
		48
		49	* fs=<filesystem-type> [default is "auto"]
		50
		51	Specify the subfilesystem type. Not every filesystem type has
		52	been tested. If you use `auto', it will try the following filesystems
		53	in order:
		54	"udf"
		55	"iso9660"
		56	"ext2"
		57	"vfat"
		58	"msdos"
		59
		60	It is also possible to give list of types separated by `:', like
		61
		62	fs=ext2:vfat
		63	- or -
		64	fs=udf:iso9660
65
66
67	* dev=<block-device> [no default, mandatory]
68
69	Specify the block device on which the subfs is to be mounted.
70
71
72	* tray_lock={always,onwrite,never} [default is "onwrite"]
73
74	Specify when supermount is to prevent media removal. `always' means
75	on every access (it was default in earlier versions), `onwrite' means only
76	for write access and `never' means never :) `onwrite' and `never' are the
77	same for ro media like CD-ROM. It is not clear when `never' is actually useful,
78	it is presented for completeness only.
79
80	* debug[=<bitmap>] [default is no debug]
81
82	Enable debugging code in the supermount filesystem, if
83	the debug option was enabled at compile time. By default, debugging
84	code is compiled into the kernel but is disabled until a debug mount
85	option is seen. <bitmap> is the combination of debug flags, following
86	flags are possible:
87
88	0x001 - "generic" debug (used by supermount_debug) - default
89	0x002 - trace dentry.c
90	0x004 - trace file.c
91	0x008 - trace filemap.c
92	0x010 - trace mediactl.c
93	0x020 - trace namei.c
94	0x040 - trace subfs.c
95	0x080 - trace super.c
96
97	Trace flags turn on tracing of functions in correpsonding files.
98	"Generic" debug flag is tested in supermount_debug; for compatibility,
99	if no flags are specified, this flag is set.
100
101
102	* '--'
103
104	All options after the option string '--' will be passed
105	directly to the subfilesystem when it gets mounted.
106
107	Errors
108	------
109
110	In addition to "normal" errors during file operations supermount may
111	return following error codes:
112
113	* No medium found
114
115	You attempt to access supermounted filesystem when there is no
116	medium inserted
117
118	* Wrong medium type
119
120	(Not really generated by supermount) You attempt to mount CD
121	without data tracks
122
123	* Stale NFS file handle
124
125	You attempt to use file handle after medium has been changed.
126
127	* No such device or address
128
129	(Not really generated by supermount) device specified in
130	dev=<device> option does not exist. Also some drivers return this
131	error instead of "No medium found", one example being floppy driver.
132
133	* Device or resource busy
134
135	(Not really generated by supermount) device is already mounted.
136	Supermount prevents double mount even if kernel otherwise would make it
137	possible.
138
139	* No such file or directory
140
141	(Not really generated by supermount) file name specified by
142	dev=<device> option does not exist
143
144	* Operation not permitted
145
146	You attempt to access subfs that is currently disabled
147
148	/proc support
149	-------------
150
151	If kernel has been compiled with procfs support, supermount will provide
152	/proc interface to read subfs status and to control some aspects of subfs.
153	The following files are created under /proc/fs/supermount:
154
155	* version (ro)
156	Shows supermount version.
157
158	* subfs (rw)
159
160	Reading this file returns list of all subfs status. One line for
161	every subfs is returned; the format is
162
163	<devname> disabled
164	- or -
165	<devname> unmounted
166	- or -
167	<devname> mounted readcount writecount
168
169	where <devname> is the string passed in `dev=' parameter during mount.
170	`readcount' is number of current subfs "users" needing ro access; `writecount'
171	is the number of "users" needing rw mode. It is mostly the number of open
172	files, but inode operations also add to these counts. Those operations
173	are normally short-lived to be seen.
174
175	Writing this file changes subfs status; the following commands are
176	suported:
177
178	<devname> [disable\|enable] [release [force]]
179
180	`disable' will disable subfs (i.e. any futher attempt to mount is rejected).
181	Subfs must be unmounted; use `disable release' or `disable release force' to
182	unmount and disable at the same time.
183
184	`enable' will enable disabled subfs, it has no effect if subfs is already
185	enabled.
186
187	`release' will unmount subfs unless it is busy (opencount > 0). To unmount
188	busy subfs add `force'; the effect is very much as if media change has been
189	detected (with the difference that subfs will be cleanly unmounted).
190
191	Some basic sanity checks are performed, i.e. it is impossible to specify
192	both `enable' and `disable' or `force' without `release'.
193
194	Internals/Locking
195	-----------------
196
197	THIS SECTION IS PROBABLY INCOMPLETE. CORRECTIONS ARE WELCOME.
198
199	Supermount itself is using two locks and relies on two more locking rules
200	as implemented by kernel.
201
202	* supermount_proc_sem
203
204	Global mutex used to protect list of sbi during access to
205	/proc/fs/supermount/subfs
206
207	* sbi->sem
208
209	Per-filesystem mutex that protects subfs state (mounted/unmounted).
210	Any changes to subfs state (mounting, unmouting, adding or removing file,
211	dentry or inode) happen under this mutex.
212
213	* inode->i_sem (see Documentation/filesystem/Locking)
214
215	Per-inode mutex used by VFS to serialize inode unlink operation.
216	Supermount relies on the fact that link/unlink for an inode are mutually
217	locked and thus inode->i_nlink is atomic inside of fs method.
218
219	* BKL
220
221	Used to protect device usage count. It is changed in open/release
222	and referenced in ioctl all of which run under BKL. Supermount adds mediactl
223	and internally wraps it in BKL as well.
224
225	Caveats/BUGS
226	------------
227
228	Inode times are believed to be correctly updated; still it is possible that
229	I missed some point.
230
231	If subfs is not yet mounted, find /mnt/cdrom fails with "find: /mnt/cdrom
232	changed during execution of find". It is unlikely it can be fixed in
233	supermount; much more simple is to provide wrapper that will check if subfs
234	is mounted and do simple "touch /mnt/cdrom" if not to make sure it is.
235
236	Supermount attempts to check for changed media at every operation and
237	invalidate and umount old subfs to avoid new media corruption in rw case.
238	Still it is possible that kernel will write out stale information and
239	it is outside of supermount control.
240
241	By default cdrom driver does not check media type i.e. supermount will
242	try all configured fs types in turn that may be quite time consuming.
243	Use sysctl -w dev.cdrom.check_media=1 to enable it. Comments in cdrom.c
244	indicate that some (non conforming) software may have problems with this
245	settings. YMMV
246
247	atime management does not work for special files. There is no hooks from
248	VFS into fs to indicate when it gets updated
249
250	$Id: 4715_supermount-2.0.4-2.6.7.patch,v 1.1 2004/06/22 22:15:04 gregkh Exp $

Lines 275-280 Link Here

(-)linux-2.6.8.1_supermount/drivers/cdrom/cdrom.c (-9 / +47 lines)
275	#include <linux/fcntl.h>	275	#include <linux/fcntl.h>
276	#include <linux/blkdev.h>	276	#include <linux/blkdev.h>
277	#include <linux/times.h>	277	#include <linux/times.h>
		278	#include <linux/supermount_media.h>
278		279
279	#include <asm/uaccess.h>	280	#include <asm/uaccess.h>
280		281
Lines 333-339 Link Here
333	#define CHECKAUDIO if ((ret=check_for_audio_disc(cdi, cdo))) return ret	334	#define CHECKAUDIO if ((ret=check_for_audio_disc(cdi, cdo))) return ret
334		335
335	/* Not-exported routines. */	336	/* Not-exported routines. */
336	static int open_for_data(struct cdrom_device_info * cdi);	337	static int open_for_data(struct cdrom_device_info * cdi, struct block_device *bdev);
337	static int check_for_audio_disc(struct cdrom_device_info * cdi,	338	static int check_for_audio_disc(struct cdrom_device_info * cdi,
338	struct cdrom_device_ops * cdo);	339	struct cdrom_device_ops * cdo);
339	static void sanitize_format(union cdrom_addr *addr,	340	static void sanitize_format(union cdrom_addr *addr,
Lines 885-891 Link Here
885	*/	886	*/
886	int cdrom_open(struct cdrom_device_info cdi, struct inode ip, struct file *fp)	887	int cdrom_open(struct cdrom_device_info cdi, struct inode ip, struct file *fp)
887	{	888	{
888	int ret;	889	int ret = 0;
889		890
890	cdinfo(CD_OPEN, "entering cdrom_open\n");	891	cdinfo(CD_OPEN, "entering cdrom_open\n");
891		892
Lines 895-901 Link Here
895	if ((fp->f_flags & O_NONBLOCK) && (cdi->options & CDO_USE_FFLAGS)) {	896	if ((fp->f_flags & O_NONBLOCK) && (cdi->options & CDO_USE_FFLAGS)) {
896	ret = cdi->ops->open(cdi, 1);	897	ret = cdi->ops->open(cdi, 1);
897	} else {	898	} else {
898	ret = open_for_data(cdi);	899	open_for_data(cdi, ip->i_bdev);
899	if (ret)	900	if (ret)
900	goto err;	901	goto err;
901	if (fp->f_mode & FMODE_WRITE) {	902	if (fp->f_mode & FMODE_WRITE) {
Lines 923-929 Link Here
923	}	924	}
924		925
925	static	926	static
926	int open_for_data(struct cdrom_device_info * cdi)	927	int open_for_data(struct cdrom_device_info * cdi, struct block_device *bdev)
927	{	928	{
928	int ret;	929	int ret;
929	struct cdrom_device_ops *cdo = cdi->ops;	930	struct cdrom_device_ops *cdo = cdi->ops;
Lines 1006-1012 Link Here
1006	cdinfo(CD_OPEN, "open device failed.\n");	1007	cdinfo(CD_OPEN, "open device failed.\n");
1007	goto clean_up_and_return;	1008	goto clean_up_and_return;
1008	}	1009	}
1009	if (CDROM_CAN(CDC_LOCK) && (cdi->options & CDO_LOCK)) {	1010	if (CDROM_CAN(CDC_LOCK) && (cdi->options & CDO_LOCK) &&
		1011	supermount_usage_count(bdev, cdi->use_count) > 0) {
1010	cdo->lock_door(cdi, 1);	1012	cdo->lock_door(cdi, 1);
1011	cdinfo(CD_OPEN, "door locked.\n");	1013	cdinfo(CD_OPEN, "door locked.\n");
1012	}	1014	}
Lines 1019-1025 Link Here
1019	This ensures that the drive gets unlocked after a mount fails. This	1021	This ensures that the drive gets unlocked after a mount fails. This
1020	is a goto to avoid bloating the driver with redundant code. */	1022	is a goto to avoid bloating the driver with redundant code. */
1021	clean_up_and_return:	1023	clean_up_and_return:
1022	cdinfo(CD_WARNING, "open failed.\n");	1024	cdinfo(CD_OPEN, "open failed.\n");
1023	if (CDROM_CAN(CDC_LOCK) && cdi->options & CDO_LOCK) {	1025	if (CDROM_CAN(CDC_LOCK) && cdi->options & CDO_LOCK) {
1024	cdo->lock_door(cdi, 0);	1026	cdo->lock_door(cdi, 0);
1025	cdinfo(CD_OPEN, "door unlocked.\n");	1027	cdinfo(CD_OPEN, "door unlocked.\n");
Lines 1096-1102 Link Here
1096	cdi->use_count--;	1098	cdi->use_count--;
1097	if (cdi->use_count == 0)	1099	if (cdi->use_count == 0)
1098	cdinfo(CD_CLOSE, "Use count for \"/dev/%s\" now zero\n", cdi->name);	1100	cdinfo(CD_CLOSE, "Use count for \"/dev/%s\" now zero\n", cdi->name);
1099	if (cdi->use_count == 0 &&	1101	if (!supermount_usage_count(fp ? fp->f_dentry->d_inode->i_bdev : 0, cdi->use_count) &&
1100	(cdo->capability & CDC_LOCK) && !keeplocked) {	1102	(cdo->capability & CDC_LOCK) && !keeplocked) {
1101	cdinfo(CD_CLOSE, "Unlocking door!\n");	1103	cdinfo(CD_CLOSE, "Unlocking door!\n");
1102	cdo->lock_door(cdi, 0);	1104	cdo->lock_door(cdi, 0);
Lines 1368-1373 Link Here
1368	tracks->cdi, tracks->xa);	1370	tracks->cdi, tracks->xa);
1369	}	1371	}
1370		1372
		1373	#if defined(CONFIG_SUPERMOUNT) \|\| defined(CONFIG_SUPERMOUNT_MODULE)
		1374	/*
		1375	* MEDIA_LOCK, MEDIA_UNLOCK
		1376	* optarg == 0 - do not adjust usage count (compatibility)
		1377	* optarg == 1 - adjust usage count
		1378	*/
		1379	int cdrom_mediactl(struct cdrom_device_info cdi, struct block_device bdev, int op, int optarg)
		1380	{
		1381	struct cdrom_device_ops *cdo = cdi->ops;
		1382
		1383	switch (op) {
		1384	case MEDIA_LOCK:
		1385	case MEDIA_UNLOCK:
		1386	if (op == MEDIA_UNLOCK && optarg) {
		1387	cdi->use_count--;
		1388	if (cdi->use_count < 0)
		1389	cdi->use_count = 0;
		1390	}
		1391	if (cdo->capability & ~cdi->mask & CDC_LOCK &&
		1392	cdi->options & CDO_LOCK &&
		1393	supermount_usage_count(bdev, cdi->use_count) == 0)
		1394	cdo->lock_door(cdi, (op == MEDIA_LOCK));
		1395	if (op == MEDIA_LOCK && optarg)
		1396	cdi->use_count++;
		1397	break;
		1398	default:
		1399	return -EINVAL;
		1400	}
		1401	return 0;
		1402	}
		1403	#endif
		1404
1371	/* Requests to the low-level drivers will /always/ be done in the	1405	/* Requests to the low-level drivers will /always/ be done in the
1372	following format convention:	1406	following format convention:
1373		1407
Lines 2114-2121 Link Here
2114	cdinfo(CD_DO_IOCTL, "entering CDROMEJECT\n");	2148	cdinfo(CD_DO_IOCTL, "entering CDROMEJECT\n");
2115	if (!CDROM_CAN(CDC_OPEN_TRAY))	2149	if (!CDROM_CAN(CDC_OPEN_TRAY))
2116	return -ENOSYS;	2150	return -ENOSYS;
2117	if (cdi->use_count != 1 \|\| keeplocked)	2151	if (keeplocked \|\|
2118	return -EBUSY;	2152	(supermount_usage_count(ip->i_bdev,cdi->use_count) != 1))
		2153	return -EBUSY;
2119	if (CDROM_CAN(CDC_LOCK))	2154	if (CDROM_CAN(CDC_LOCK))
2120	if ((ret=cdo->lock_door(cdi, 0)))	2155	if ((ret=cdo->lock_door(cdi, 0)))
2121	return ret;	2156	return ret;
Lines 2914-2919 Link Here
2914	EXPORT_SYMBOL(cdrom_release);	2949	EXPORT_SYMBOL(cdrom_release);
2915	EXPORT_SYMBOL(cdrom_ioctl);	2950	EXPORT_SYMBOL(cdrom_ioctl);
2916	EXPORT_SYMBOL(cdrom_media_changed);	2951	EXPORT_SYMBOL(cdrom_media_changed);
		2952	#if defined(CONFIG_SUPERMOUNT) \|\| defined(CONFIG_SUPERMOUNT_MODULE)
		2953	EXPORT_SYMBOL(cdrom_mediactl);
		2954	#endif
2917	EXPORT_SYMBOL(cdrom_number_of_slots);	2955	EXPORT_SYMBOL(cdrom_number_of_slots);
2918	EXPORT_SYMBOL(cdrom_mode_select);	2956	EXPORT_SYMBOL(cdrom_mode_select);
2919	EXPORT_SYMBOL(cdrom_mode_sense);	2957	EXPORT_SYMBOL(cdrom_mode_sense);

Lines 3384-3389 Link Here

(-)linux-2.6.8.1_supermount/drivers/ide/ide-cd.c (-1 / +32 lines)
3384	{	3384	{
3385	ide_drive_t *drive = inode->i_bdev->bd_disk->private_data;	3385	ide_drive_t *drive = inode->i_bdev->bd_disk->private_data;
3386	struct cdrom_info *info = drive->driver_data;	3386	struct cdrom_info *info = drive->driver_data;
		3387	#if defined(CONFIG_SUPERMOUNT) \|\| defined(CONFIG_SUPERMOUNT_MODULE)
		3388	/*
		3389	* This is the same sort of clockload as use in blkdev_get.
		3390	* We need information whether device is supermounted inside
		3391	* of cdrom_release to decide if tray must be unlocked.
		3392	* This information so far is available only by looking
		3393	* up superblock but it needs struct *bdev and it is not
		3394	* available in cdrom_release anymore
		3395	*/
		3396	struct dentry t_dentry;
		3397	struct file t_file;
		3398
		3399	if (!file) {
		3400	t_file.f_dentry = &t_dentry;
		3401	t_dentry.d_inode = inode;
		3402	file = &t_file;
		3403	}
		3404	#endif
3387		3405
3388	cdrom_release (&info->devinfo, file);	3406	cdrom_release (&info->devinfo, file);
3389	drive->usage--;	3407	drive->usage--;
Lines 3418-3430 Link Here
3418	return 0;	3436	return 0;
3419	}	3437	}
3420		3438
		3439	#if defined(CONFIG_SUPERMOUNT) \|\| defined(CONFIG_SUPERMOUNT_MODULE)
		3440	static int idecd_mediactl(struct block_device *bdev, int op, int arg)
		3441	{
		3442	struct gendisk *disk = bdev->bd_disk;
		3443	ide_drive_t *drive = disk->private_data;
		3444	struct cdrom_info *info = drive->driver_data;
		3445	return cdrom_mediactl(&info->devinfo, bdev, op, arg);
		3446	}
		3447	#endif
		3448
3421	static struct block_device_operations idecd_ops = {	3449	static struct block_device_operations idecd_ops = {
3422	.owner = THIS_MODULE,	3450	.owner = THIS_MODULE,
3423	.open = idecd_open,	3451	.open = idecd_open,
3424	.release = idecd_release,	3452	.release = idecd_release,
3425	.ioctl = idecd_ioctl,	3453	.ioctl = idecd_ioctl,
3426	.media_changed = idecd_media_changed,	3454	.media_changed = idecd_media_changed,
3427	.revalidate_disk= idecd_revalidate_disk	3455	.revalidate_disk= idecd_revalidate_disk,
		3456	#if defined(CONFIG_SUPERMOUNT) \|\| defined(CONFIG_SUPERMOUNT_MODULE)
		3457	.mediactl = idecd_mediactl,
		3458	#endif
3428	};	3459	};
3429		3460
3430	/* options */	3461	/* options */

Lines 511-522 Link Here

(-)linux-2.6.8.1_supermount/fs/block_dev.c (+33 lines)
511	{	511	{
512	struct gendisk *disk = bdev->bd_disk;	512	struct gendisk *disk = bdev->bd_disk;
513	struct block_device_operations * bdops = disk->fops;	513	struct block_device_operations * bdops = disk->fops;
		514	#if defined(CONFIG_SUPERMOUNT) \|\| defined(CONFIG_SUPERMOUNT_MODULE)
		515	struct super_block *sb = NULL;
		516	int supermounted = 0;
		517	#endif
514		518
515	if (!bdops->media_changed)	519	if (!bdops->media_changed)
516	return 0;	520	return 0;
517	if (!bdops->media_changed(bdev->bd_disk))	521	if (!bdops->media_changed(bdev->bd_disk))
518	return 0;	522	return 0;
519		523
		524	#if defined(CONFIG_SUPERMOUNT) \|\| defined(CONFIG_SUPERMOUNT_MODULE)
		525	sb = get_super(bdev);
		526	if (sb) {
		527	atomic_set(&sb->s_media_changed, 1);
		528	supermounted = sb->s_flags & MS_SUPERMOUNTED;
		529	drop_super(sb);
		530	}
		531
		532	/*
		533	* Supermount used to did invalidate_device followed by
		534	* destroy_buffers. invalidate_device hardly does anything
		535	* useful here as it won't really invalidate "busy" inodes
		536	* and every inode in subfs is busy (at least one reference
		537	* from superfs exists). So now it just flushes
		538	* buffers so they do not accidentally overwrite newly
		539	* inserted media
		540	*
		541	* FIXME unfortunately during umount VFS may write on its
		542	* own, like write_super. Those writes will go to a wrong
		543	* media thus corrupting it :(
		544	*
		545	* There is no error print because supermount warns user
		546	* itself.
		547	*/
		548
		549	if (supermounted) {
		550	invalidate_bdev(bdev, 1);
		551	} else
		552	#endif
520	if (__invalidate_device(bdev, 0))	553	if (__invalidate_device(bdev, 0))
521	printk("VFS: busy inodes on changed media.\n");	554	printk("VFS: busy inodes on changed media.\n");
522		555

Line 0 Link Here

(-)linux-2.6.8.1_supermount/fs/supermount/Kconfig (+26 lines)
	1	config SUPERMOUNT
	2	tristate "Supermount removable media support"
	3	help
	4	Supermount gives you the ability to access CD-ROMs and Floppies
	5	without mounting/unmounting them every time you want to access
	6	a different disk/floppy. Just eject the media, insert a new one
	7	and you are able to access it.
	8
	9	Read Documentation/filesystems/supermount.txt for more information.
	10
	11	If you want to compile the Supermount support as a module ( = code
	12	which can be inserted in and removed from the running kernel whenever
	13	you want), say M here and read Documentation/modules.txt. The module
	14	will be called supermount.o.
	15
	16	If unsure, say N.
	17
	18	config SUPERMOUNT_DEBUG
	19	bool "Enable supermount debug code"
	20	depends on SUPERMOUNT
	21	help
	22	If you set this to Y, additional debug code will be compiled in.
	23	Debug output is controlled with debug=N mount option. Possible
	24	values are listed in Documentation/filesystems/supermount.txt.
	25
	26	If unsure, say Y.

Line 0 Link Here

(-)linux-2.6.8.1_supermount/fs/supermount/Makefile (+15 lines)
	1	#
	2	# Makefile for the linux supermounting routines.
	3	#
	4
	5	supermount-objs := dentry.o \
	6	file.o \
	7	filemap.o \
	8	init.o \
	9	mediactl.o \
	10	namei.o \
	11	proc.o \
	12	subfs.o \
	13	super.o
	14
	15	obj-$(CONFIG_SUPERMOUNT) += supermount.o

Line 0 Link Here

(-)linux-2.6.8.1_supermount/fs/supermount/changelog (+462 lines)
		1	* ? ? ? Andrey Borzenkov <arvidjaar@mail.ru> ?.?.?
		2
		3	* Sun 18 Jan 2004 Andrey Borzenkov <arvidjaar@mail.ru> 2.0.4
		4
		5	- yet another attempt to fix detection of USB drive removale
		6	(explicitly check for SDVE_DEL state in sd.c:sd_media_changed)
		7
		8	- fixed i18n patch for ext2 and udf (ignored options)
		9
		10	- ->nopage prototype changed; it makes it incompatible with
		11	kernel < 2.6.1 (I wonder how it compiled - or did I miss
		12	warning). Add comments about ->populate and why it won't be
		13	implemented
		14
		15	- fix "auto" option. Simplification of option processing turned
		16	out to be a mess :( Reported by Bart
		17
		18	* Mon 12 Jan 2004 Andrey Borzenkov <arvidjaar@mail.ru> 2.0.3b
		19
		20	- Fix compilation problem in subfs.c with older GCC - declaration
		21	after statement in clear_inodes(bug 875009). Pointed by Adrian Punga.
		22
		23	* Wed 07 Jan 2004 Andrey Borzenkov <arvidjaar@mail.ru> 2.0.3a
		24
		25	- fix Oops during options parsing if no subfs option is
		26	given after "--" (bug 869863)
		27
		28	* Mon 29 Dec 2003 Andrey Borzenkov <arvidjaar@mail.ru> 2.0.3
		29
		30	- move test for device offline in sd.c to the top in attempt
		31	to fix USB removale problem
		32
		33	- simplify options procesing
		34
		35	- remove cdrom "open failed" message (it is now under
		36	CDROM_OPEN flag like all others in cdrom_open).
		37
		38	- rewrote option parsing to use new lib/parse library
		39
		40	* Sun 26 Oct 2003 Andrey Borzenkov <arvidjaar@mail.ru> 2.0.2a
		41
		42	- remove some obsolete files that are not used anymore from CVS
		43	(i.e. from patch)
		44
		45	- isofs needs extra ignored options now. It rurns out it silently
		46	ignored any unknown option before new and shiny option parsing
		47	code
		48
		49	- consistently use "kernel 2.6" in version print
		50
		51	- updates for -test8. Change ext2/udf patches to match new options
		52	parsing code.
		53
		54	* Wed 10 Sep 2003 Andrey Borzenkov <arvidjaar@mail.ru> 2.0.2
		55
		56	- NODEV is gone, use MKDEV(UNNAMED_MAJOR, 0) instead, it is just
		57	as good as anything else
		58
		59	* Sat 23 Aug 2003 Andrey Borzenkov <arvidjaar@mail.ru> 2.0.1d
		60
		61	- rediff against 2.6.0-test4
		62
		63	* Mon 18 Aug 2003 Andrey Borzenkov <arvidjaar@mail.ru> 2.0.1c
		64
65	- fix compilation without CONFIG_SUPERMOUNT. Reported by
66	Igor Strygin
67
68	* Sun 10 Aug 2003 Andrey Borzenkov <arvidjaar@mail.ru> 2.0.1b
69
70	- /proc/fs/supermount/version is read-only, do not set permissions to
71	rw
72
73	- remove generic_unplug_queue from ide_do_drive_cmd, apparently
74	it is redundant now (fixes bug 785691)
75
76	- rediff for 2.6.0-test3
77
78	* Sun 27 Jul 2003 Andrey Borzenkov <arvidjaar@mail.ru> 2.0.1a
79
80	- rediff for 2.6.0-test2
81
82	* Sun 13 Jul 2003 Andrey Borzenkov <arvidjaar@mail.ru> 2.0.1
83
84	- hush most unused variables warnings with CONFIG_DEBUG (idea
85	suggested by Jeff Garzik)
86
87	- replace ugly SUPERMOUNT_TARCE_{ENTER,LEAVE}[_ARGS] with ENTER/LEAVE
88	Use %p throughout for pointer output.
89
90	- send DN_CREATE for root on mount
91
92	- allow open and readdir on mountpoint even if subfs is unmounted.
93	This provides for active monitoring by FAM/dnotify and is overall
94	less surprising - ls /mnt/cdrom just returns empty directory now
95	instead of error. For technical reasons ->flush and ->permissions
96	need be aware about it too.
97
98	Files opened while subfs is unmounted are NOT usable for anything
99	except readdir even AFTER subfs gets mounted. So application
100	has to reopen directory to rescan it. AFAIK all of them do it :)
101
102	* Sat 12 Jul 2003 Andrey Borzenkov <arvidjaar@mail.ru> 2.0.0a
103
104	- add struct nameidata * goes into d_revalidate as well
105
106	- add struct nameidata * to some inode methods (introduced in
107	2.5.75). Currently it is just passed along - it is not clear if
108	local subfs-specific nameidata has to be constructed. Apparently
109	it existed in follow_link all the time without any evil done.
110
111	- fix small races in supermount_getattr - do not attempt to
112	get subdent if prevent_umount failed
113
114	* Mon 23 Jun 2003 Andrey Borzenkov <arvidjaar@mail.ru> 2.0.0
115
116	- added ->getattr; it never fails on both unmounted mountpoint
117	and stale open files - to ensure fuser -m /mnt/cdrom still finds them
118
119	- merge 2.5.73; update sd.c to new refcount interface in sd.c
120
121	- fix SUPERMOUNT_BUG_ON_LOCKED without SUPERMOUNT_DEBUG
122
123	- add media management to ide-floppy and those CD-ROM drivers that
124	are using standard cdrom_* calls (cdu31a, cm206, mcd, mcdx, sbpcd).
125	Testdrive revealed that none of them builds for other reasons :)
126
127	- add (un)mark_media_supermounted; mark after mount, unmark
128	before umount. These functions just manipulate bd_disk->scount
129
130	- add scount to struct gendisk to serve as count of total
131	supermounted partitions; use everywhere to check if device
132	is supermounted
133
134	* Tue 17 Jun 2003 Andrey Borzenkov <arvidjaar@mail.ru> 2.0.0test2
135
136	- update kernel patch for 2.5.72 (there was a reject in
137	drivers/ide/ide-io.c)
138
139	- move init_inode_info into alloc_inode; use iget_locked
140	instead of iget to skip ->read_inode with intent to move
141	inode init under if (inode->i_state & I_NEW)
142
143	- polish dentry.c a bit while I am on it
144
145	- ->d_compare is not run under dcache_lock anymore. Pointed by
146	Maneesh Soni. As we can't sleep in d_compare, use rwlock to
147	protect against races with supermount_clean_dentries until
148	I find better solution.
149
150	- remove new_subfs_dentry - it is not used anymore and comments
151	there were wrong anyway
152
153	* Sun 01 Jun 2003 Andrey Borzenkov <arvidjaar@mail.ru> 2.0.0test1
154
155	- add sr and sd support
156
157	- update sb s_blocksize and s_blocksize_bits on subfs mount
158
159	- use BKL around chek_disk_change; it is not garanteed by VFS now
160
161	- llseek no more updates file readahead pointer
162
163	- used bdev not gendisk in mediactl - it needs it for
164	supermount_usage_count. It probably needs redesign. Also some minor
165	changes on the way.
166
167	- 2.5 changes. supermount_get_sb, inode alloc/dealloc, use bdev instead
168	of dev, Makefile change, add CONFIG_SUPERMOUNT_DEBUG, do_remount_sb
169	prototype change, mknod prototype change, UPDATE_ATIME dead,
170	dnotify_parent is now true function
171
172	* Tue 27 May 2003 Andrey Borzenkov <arvidjaar@mail.ru> 1.2.7
173
174	- (re-)set root inode flags after unmounting subfs
175
176	- fix mounting of ro media on rw filesystem. It was broken by fix
177	in 1.2.4. Remove saved s_mflags and just use real sb->s_flags.
178	Reported by Con Kolivas
179
180	- do not use MS_MGC_VAL in subfs_real_mount - it is not used anywhere
181	in kernel and all lower bits are already taken in 2.5
182
183	- configure help from Marc-Christian Petersen
184
185	- use subsb->s_bdev instead of looking up using s_dev. This also
186	fixes problem with O(1) patch (bug 737783)
187
188	* Wed 14 May 2003 Andrey Borzenkov <arvidjaar@mail.ru> 1.2.6
189
190	- check for correct inode in attach_subfs_inode - if super inode
191	has subinode attached it must be the same as is currently
192	resuested. Else it is a bug.
193
194	- use lookup_one_len to lookup subfs dentry in cache; check if
195	subfs did not change name and lookup "real" dentry in parent
196	cache in this case. This finally puts an end to the attempt to
197	control subfs dcache. The only thing we rely upon now is that
198	nothing can change directory contents while in lookup method.
199
200	- implement d_hash and d_compare to properly support case-
201	insensitive filesystems (vfat & Co).
202
203	- reset super inode i_mapping so it does not point to freed
204	subinode mapping when unmounting subfs
205
206	- send dnotify_parent on dentry cleanup, not on inode
207
208	- use write_inode_now in ->write_inode. Reading intricated flags
209	manipulations in fs/inode.c was just too intimidating. It is not as
210	much overhead as it looks like - it is called from sync_one only
211	so all dirty pages are scheduled to be flushed anyway.
212
213	* Sun 04 May 2003 Andrey Borzenkov <arvidjaar@mail.ru> 1.2.5
214
215	- enable dentries caching; properly use d_add when dentry is first
216	looked up and d_instantiate when inode is finally available.
217
218	- first stab at sending notifications on media umount/mount
219
220	- more caveats :(
221
222	* Sat 26 Apr 2003 Andrey Borzenkov <arvidjaar@mail.ru> 1.2.4
223
224	- fix write_inode/prepare_inode deadlock. It looked like
225	set I_LOCK
226	down(&sbi->sem);
227	iget4 -> wait_on_inode
228	down(&sbi->sem)
229
230	- MS_ACTIVE was reset on subfs remount
231
232	- print process PID in trace
233
234	- adjust directory structure to make patch generation easier
235
236	* Sun 20 Apr 2003 Andrey Borzenkov <arvidjaar@mail.ru> 1.2.3
237
238	- dummy version due to script problems
239
240	* Sun 20 Apr 2003 Andrey Borzenkov <arvidjaar@mail.ru> 1.2.2
241
242	- remove #ifdef CONFIG_PROC_FS from init.c, it already exists in
243	supermount.h
244
245	- no_tray_lock -> TRAY_LOCK_NEVER. Just to make sure it remains
246	compatible (even if it is very unlikely anybody is using it).
247
248	- backout kernel stat patch; remove getattr alltogether. It fixed
249	fuser -m for stale files. getattr remains uniplemented because
250	it does not seem to be used anywhere in kernel at all so I am not
251	actually sure how to implement it
252
253	It also backouts 10_readlik and 30_lseek as they are not used
254	anymore for a long time.
255
256	- remove bogus check for sub- and superinodes i_count. i_count is
257	outside of supermount control; the only thing that we must be
258	sure in - inode is free on umount.
259
260	- reset root inode attributes and operations on umount. This fixes
261	the problem of attempt to mount media on ls -l /mnt after subfs
262	has been mounted once.
263
264	- remove ->stale. For all practical purposes an entity is stale iff
265	it does not (yet) have associated subfs entity. Creating yet another
266	field that just mirrors this condition does not add a single bit
267	of useful information.
268
269	- subfs_is_busy iff subfs mnt_count > 1
270
271	* Sat 05 Apr 2003 Andrey Borzenkov <arvidjaar@mail.ru> 1.2.1
272
273	- fixed stupid thinko in mediactl methods (the effect was it was
274	impossible to manually eject ro media). It was exposed by recent
275	changes. No changes in supermount itself only in driver code
276
277	- replace no_tray_lock with tray_lock={never,onwrite,always} with
278	"onwrite" being default. I stil do not quite like resulting code
279	but it will do for now.
280
281	- simplified subfs_(get\|put)_(write\|read) interface; merge both
282	read/write in one function; remove subfs_get_atime. To my surprise
283	it resulted on more clean interface in the rest of supermount even
284	if subfs_(get\|put)_access does look a bit weird.
285
286	* Sun 30 Mar 2003 Andrey Borzenkov <arvidjaar@mail.ru> 1.2.0
287
288	- changed proc command format to
289	<devname> [enable\|disable] [release [force]]
290
291	- add /proc/fs/supermount/version; printk version on starup only
292	if procfs is not configured.
293
294	- unify media lock rules for thosed drivers using implementing
295	mediactl (cdrom, sd, ide-floppy as of this writing). Lock
296	media for both manual and software eject; do not unlock media
297	that is in used by something else.
298
299	- added show_options method to super.c
300
301	- implemented /proc/fs/supermount/subfs read as seq_file
302
303	* Sat 29 Mar 2003 Andrey Borzenkov <arvidjaar@mail.ru> 1.1.4
304
305	- supermount_rename leftover - it does not need new_subfs_dentry.
306	It still worked because new dentry was destroyed immediately, but
307	let's do it the right way. Also mark target rw if exists
308
309	- propagate S_IMMUTABLE, S_NOATIME and S_APPEND flags from subfs
310	to super inode. Filesystems usually rely on VFS to check these
311	flags which means it was possible to overwrite immutable file. Also
312	needed for atime management (to be added).
313
314	- added atime management. It is based on grep UPDATE_ATIME so it may
315	be incomplete; still it gives right results in most obvious cases :)
316	It respects no(dir)atime mount flag.
317
318	- Make sure super inode times and sizes are updated to reflect subfs
319	inode. Done in preparation to remove stat kernel patch. Only those
320	fields needed by stat are updated.
321
322	- remove assertion subi->i_count == 1 from clear_inode. Subfs icache
323	is managed independently and there is no lock (as opposed to dentry
324	case where we never do cached lookup for subfs).
325
326	- use inode cache for supermount inodes to avoid linear search. This
327	moves almost the whole inode creation task into read_inode2 - the
328	only place where inode needs to be created is root inode.
329
330	We use inode numbers from subfs; root inode is never cached until
331	subfs has been mounted. Stale inodes are removed from cache in
332	clean_inodes (just like dentries are in clean_dentries) so aliasing
333	problem is solved.
334
335	- add "disabled" state - prevent any attempt to mount media
336
337	- add procfs support. Reading /proc/fs/supermount/subfs will return
338	list of subfs and their status. Writing into it allows you to
339	control status of subfs (mounted/unmounted, enabled/dusabled)
340
341	- fix race in clear_inode. It was possible that subfs was umounted
342	after inode has been removed from list but before its access
343	counters were cleared. The code that checkes for that exists only
344	for debugging still I'd like it to be useful.
345
346	* Sun 16 Mar 2003 Andrey Borzenkov <arvidjaar@mail.ru> 1.1.3
347
348	- add CVS verion Id's to files
349
350	- finally get rid of ugly generation number. It is enough to just
351	mark entity obsolete; we do not care actually when it happened.
352	Now every entity starts out stale; stale flag is reset when subfs
353	object is attached; stale flag is set again for the rest of life
354	in subfs_umount
355
356	- as a side effect read/write count is associated with inodes
357	exclusively
358
359	- clear_inode and d_iput need prevent/allow umount to avoid "stealing"
360	subfs while holding active entities. File release is safe as VFS does
361	nou put mnt until _release is finished.
362
363	- subfs_prevent_umount does not need validator. The worst thing that
364	can happen is that newly mounted subfs is accessed. That does not
365	matter, access to subfs object is checked for validity separately in
366	every case.
367
368	- finally clarify dcache management. As we cannot garantee coherency
369	between sub- and super- fs caches we ignore subfs cache entirely.
370	Super dentry is instantiated in supermount_lookup and passed around
371	with subfs dentry attached. It does not matter if it is positive or
372	negative. Currently dentries are forced to be deleted in
373	supermount_d_delete but I believe it is not really needed.
374
375	- print version number on registering filesystem to facilitate debugging
376
377	- umount subfs as soon as possible in check_disk_change. This eliminates
378	zombie state (mounted but inactive due to media change detected).
379
380	- kill subfs_is_active, it is the same as subfs_is_mounted now.
381
382	- kill translations.c it does not do anything special now; move functions
383	in file/dentry/namei
384
385	- fix stupid bug in get_supermount_inode again - super inode must
386	be inited and attached just once not every time.
387	Praise assertions again :)
388
389	* 10 Mar 2003 Andrey Borzenkov <arvidjaar@mail.ru> 1.1.2
390
391	- allow fs=type1:type2:...
392
393	- remove supermount_drop_dentries (no more used)
394
395	- add some more assertions to subfs_umount
396
397	* 10 Mar 2003 Andrey Borzenkov <arvidjaar@mail.ru> 1.1.1
398
399	- fix stupid bug in subfs inode refcounting. It was visible with
400	hardlinks only so CD-ROM users would not ever see it.
401
402	- fix even more stupid bug in unlink - subi was used instead of superi
403
404	* 8 Mar 2003 Andrey Borzenkov <arvidjaar@mail.ru> 1.1.0
405
406	- files cannot use inode obsolete flag - it does not work for
407	root inodes
408
409	- make file system structure exact mirror of subfs - now there
410	is 1-to-1 correspondence between super- and subfs files, dentries
411	and inodes. This is needed to properly manage write access without
412	too much locking
413
414	- finally realized that subfs cannot be obsolete; use either file
415	or inode pointer in all calls into subfs.c to check for freshness
416
417	- debug is now per-mount; added trace of all functions
418
419	- move setting of SUPERMOUNT_DEBUG to Makefile instead of supermount_i.h
420
421	* 1 Mar 2003 Andrey Borzenkov <arvidjaar@mail.ru> 1.0.0
422
423	- make sure it is always possible umount subfs. It does it by
424	keeping list of opened files (in addition to inodes) and closing
425	them if media change is detected.
426
427	- make sure subfs can't go away while it is being in use. For
428	files it get_file for subfile to ensure subfs mnt is not freed. For
429	inode operation it increments usage counter of submnt for duration
430	of operation.
431
432	- make sure supermounted device can't be mounted twice (that is
433	allowed by kernel) because it relies on being the only "owner" of
434	subfs. It does it by checking for MS_SUPERMOUNTED flag on mount.
435
436	- make sure you can't mount over supermounted directory. Allowing
437	it is a nightmare and I cannot see any reason for it (if you can
438	provide valid one - I may reconsider this part). It does so by
439	adding fstype flag and checking it on mounting.
440
441	- reject mount -o remount for the time being (until we can deal
442	with it properly)
443
444	- completely change implementation of individual inode methods.
445	Instead of calling VFS recursively it calls subfs methods directly.
446	It is to ensure we are in full control of subfs (assuming it behaves
447	properly :)
448
449	- properly implement VM methods. Currently changing media would
450	leave you with vm_area pointing to no more existing inode ...
451
452	- remove many obsolete pieces like flags that just duplicate
453	existing information.
454
455	- ensure coherency between super- and subfs dentries. Either we
456	have both active in dcache or do not have them at all.
457
458	- fixe the problem with media ejection after direct access to CD-ROM
459
460	- add "just disc change" to all operations to detect media change
461	as soon as possible. It is possible to add option to do it just
462	for writable media or to completely turn it off.

Line 0 Link Here

(-)linux-2.6.8.1_supermount/fs/supermount/dentry.c (+282 lines)
		1	/*
		2	* linux/fs/supermount/dentry.c
		3	*
		4	* Original version:
		5	* Copyright (C) 1995
		6	* Stephen Tweedie (sct@dcs.ed.ac.uk)
		7	*
		8	* Rewriten for kernel 2.2 & 2.4. (C) 1999, 2000 Alexis Mikhailov
		9	* (alexis@abc.cap.ru)
		10	* Rewritten for kernel 2.4.21 (C) 2003 Andrey Borzenkov
		11	* (arvidjaar@mail.ru)
		12	* Rewritten for kernel 2.5.70 (C) 2003 Andrey Borzenkov
		13	* (arvidjaar@mail.ru)
		14	*
		15	* $Id: 4715_supermount-2.0.4-2.6.7.patch,v 1.1 2004/06/22 22:15:04 gregkh Exp $
		16	*/
		17
		18	#define S_DBG_TRACE_CURRENT S_DBG_TRACE_DENTRY
		19	#include "supermount.h"
		20
		21	int
		22	init_dentry_info(struct dentry *dentry)
		23	{
		24	struct super_block *sb = dentry->d_sb;
		25	struct supermount_dentry_info *sdi;
		26	int rc;
		27
		28	ENTER(sb, "dentry=%s", dentry->d_name.name);
		29
		30	rc = 1;
		31	sdi = kmalloc(sizeof(*sdi), GFP_KERNEL);
		32	if (!sdi)
		33	goto out;
		34
		35	memset(sdi, 0, sizeof(*sdi));
		36
		37	INIT_LIST_HEAD(&sdi->list);
		38	sdi->dentry = 0;
		39	sdi->host = dentry;
		40
		41	dentry->d_fsdata = sdi;
		42	dentry->d_op = &supermount_dops;
		43
		44	rc = 0;
		45	out:
		46	LEAVE(sb, "dentry=%s rc=%d", dentry->d_name.name, rc);
		47
		48	return rc;
		49
		50	}
		51
		52	void
		53	attach_subfs_dentry(struct dentry dentry, struct dentry subdent)
		54	{
		55	struct super_block *sb = dentry->d_sb;
		56	struct supermount_sb_info *sbi = supermount_sbi(sb);
		57	struct supermount_dentry_info *sdi;
		58
		59	ENTER(sb, "dentry=%s subd=%p", dentry->d_name.name, subdent);
		60
		61	sdi = supermount_d(dentry);
		62	SUPERMOUNT_BUG_LOCKED_ON(sb, sdi->dentry);
		63	sdi->dentry = dget(subdent);
		64	list_add(&sdi->list, &sbi->s_dentries);
65
66	LEAVE(sb, "dentry=%s", dentry->d_name.name);
67	}
68
69
70	struct dentry *
71	get_subfs_dentry(struct dentry *dentry)
72	{
73	struct super_block *sb = dentry->d_sb;
74	struct dentry *err;
75	struct supermount_dentry_info *sdi = supermount_d(dentry);
76
77	ENTER(sb, "dentry=%s", dentry->d_name.name);
78
79	subfs_lock(sb);
80
81	err = ERR_PTR(-ENOMEDIUM);
82	if (!subfs_is_mounted(sb))
83	goto out;
84
85	err = ERR_PTR(-ESTALE);
86	if (is_dentry_obsolete(dentry))
87	goto out;
88
89	err = dget(sdi->dentry);
90	SUPERMOUNT_BUG_LOCKED_ON(sb, !err);
91	SUPERMOUNT_BUG_LOCKED_ON(sb, (dentry->d_inode == 0) ^ (err->d_inode == 0));
92
93	out:
94	subfs_unlock(sb);
95
96	LEAVE(sb, "dentry=%s subd=%p", dentry->d_name.name, err);
97
98	return err;
99	}
100
101	static int
102	supermount_d_revalidate(struct dentry dentry, struct nameidata nd)
103	{
104	struct super_block *sb = dentry->d_sb;
105	struct dentry *subd;
106	int rc;
107	struct vfsmount *mnt;
108
109	ENTER(sb, "dentry=%s", dentry->d_name.name);
110
111	rc = 0;
112	mnt = subfs_prevent_umount(sb);
113	if (!mnt)
114	goto out;
115
116	subd = get_subfs_dentry(dentry);
117
118	if (IS_ERR(subd))
119	goto allow_umount;
120
121	rc = 1;
122	/* FIXME do we need to build proper subfs nd? */
123	if (subd->d_op && subd->d_op->d_revalidate)
124	rc = subd->d_op->d_revalidate(subd, nd);
125
126	dput(subd);
127	allow_umount:
128	subfs_allow_umount(sb, mnt);
129	out:
130
131	LEAVE(sb, "dentry=%s rc=%d", dentry->d_name.name, rc);
132
133	return rc;
134	}
135
136	static int
137	supermount_d_hash(struct dentry dentry, struct qstr name)
138	{
139	struct super_block *sb = dentry->d_sb;
140	struct dentry *subd;
141	int rc;
142	struct vfsmount *mnt;
143
144	ENTER(sb, "dentry=%s name=%s", dentry->d_name.name, name->name);
145
146	rc = -ENOMEDIUM;
147	mnt = subfs_prevent_umount(sb);
148	if (!mnt)
149	goto out;
150
151	subd = get_subfs_dentry(dentry);
152	rc = PTR_ERR(subd);
153	if (IS_ERR(subd))
154	goto allow_umount;
155
156	rc = 0;
157	if (subd->d_op && subd->d_op && subd->d_op->d_hash)
158	rc = subd->d_op->d_hash(subd, name);
159
160	dput(subd);
161	allow_umount:
162	subfs_allow_umount(sb, mnt);
163	out:
164	LEAVE(sb, "dentry=%s rc=%d", dentry->d_name.name, rc);
165
166	return rc;
167	}
168
169
170	rwlock_t d_compare_lock = RW_LOCK_UNLOCKED;
171
172	static int
173	supermount_d_compare(struct dentry dentry, struct qstr name1, struct qstr *name2)
174	{
175	struct super_block *sb = dentry->d_sb;
176	struct supermount_dentry_info *sdi;
177	struct dentry *subd;
178	int rc;
179
180	ENTER(sb, "dentry=%s name1=%s name2=%s", dentry->d_name.name, name1->name, name2->name);
181
182	rc = 1; /* fail by default */
183	sdi = dentry->d_fsdata;
184	SUPERMOUNT_BUG_ON(!sdi);
185
186	/*
187	* HACK - FIXME
188	* this protects against races with supermount_clean_dentries
189	* I cannot use blocking calls (i.e. sbi->sem) here and it is not
190	* protected by dcache_lock anymore
191	*/
192	read_lock(&d_compare_lock);
193	subd = sdi->dentry;
194	if (!subd) {
195	read_unlock(&d_compare_lock);
196	goto out;
197	}
198
199	if (subd->d_op && subd->d_op->d_compare)
200	rc = subd->d_op->d_compare(subd, name1, name2);
201	else { /* based on fs/dcache.c:d_lookup */
202	if (name1->len == name2->len)
203	rc = memcmp(name1->name, name2->name, name1->len);
204	}
205	read_unlock(&d_compare_lock);
206
207	out:
208	LEAVE(sb, "dentry=%s rc=%d", dentry->d_name.name, rc);
209	return rc;
210	}
211
212	static inline void
213	handle_subdent(struct dentry *dentry)
214	{
215	struct super_block *sb = dentry->d_sb;
216	struct vfsmount *mnt;
217	struct supermount_dentry_info *sdi = supermount_d(dentry);
218	struct dentry *subd = 0;
219
220	mnt = subfs_prevent_umount(sb);
221	if (!mnt)
222	goto out;
223
224	subfs_lock(sb);
225	if (sdi) {
226	subd = sdi->dentry;
227	list_del_init(&sdi->list);
228	sdi->dentry = 0;
229	}
230	subfs_unlock(sb);
231
232	if (subd)
233	dput(subd);
234
235	subfs_allow_umount(sb, mnt);
236	out:
237	return;
238	}
239
240	/*
241	* in case of active dentry we must be sure subfs dentry is released
242	* before subfs inode to correctly maintain write state
243	*/
244	static void
245	supermount_d_iput(struct dentry dentry, struct inode inode)
246	{
247	struct super_block *sb = dentry->d_sb;
248
249	ENTER(sb, "dentry=%s inode=%p", dentry->d_name.name, inode);
250
251	handle_subdent(dentry);
252	iput(inode);
253
254	LEAVE(sb, "dentry=%s", dentry->d_name.name);
255	}
256
257
258	/*
259	* this duplicated code is due to the lack of common "destroy" method
260	* for both negative and positive dentries
261	*/
262	static void
263	supermount_d_release(struct dentry *dentry)
264	{
265	struct super_block *sb = dentry->d_sb;
266	struct supermount_dentry_info *sdi = supermount_d(dentry);
267
268	ENTER(sb, "dentry=%s", dentry->d_name.name);
269
270	handle_subdent(dentry);
271	kfree(sdi);
272
273	LEAVE(sb, "dentry=%s", dentry->d_name.name);
274	}
275
276	struct dentry_operations supermount_dops = {
277	.d_revalidate = supermount_d_revalidate,
278	.d_hash = supermount_d_hash,
279	.d_compare = supermount_d_compare,
280	.d_iput = supermount_d_iput,
281	.d_release = supermount_d_release,
282	};

Line 0 Link Here

(-)linux-2.6.8.1_supermount/fs/supermount/file.c (+689 lines)
		1	/*
		2	* linux/fs/supermount/file.c
		3	*
		4	* Original version:
		5	* Copyright (C) 1995, 1997
		6	* Stephen Tweedie (sct@dcs.ed.ac.uk)
		7	*
		8	* from
		9	*
		10	* linux/fs/minix/dir.c
		11	* Copyright (C) 1991, 1992 Linus Torvalds
		12	*
		13	* and
		14	*
		15	* linux/fs/ext2/dir.c
		16	* Copyright (C) 1992, 1993, 1994, 1995 Remy Card
		17	*
		18	* Rewriten for kernel 2.2 & 2.4. (C) 1999, 2000 Alexis Mikhailov
		19	* (alexis@abc.cap.ru)
		20	* Rewriten for kernel 2.4. (C) 2001 MandrakeSoft Inc.
		21	* Juan Quintela (quintela@mandrakesoft.com)
		22	* Rewritten for kernel 2.4.21 (C) 2003 Andrey Borzenkov
		23	* (arvidjaar@mail.ru)
		24	* Rewritten for kernel 2.5.70 (C) 2003 Andrey Borzenkov
		25	* (arvidjaar@mail.ru)
		26	*
		27	* $Id: 4715_supermount-2.0.4-2.6.7.patch,v 1.1 2004/06/22 22:15:04 gregkh Exp $
		28	*/
		29
		30	#define S_DBG_TRACE_CURRENT S_DBG_TRACE_FILE
		31	#include "supermount.h"
		32
		33	#define DEFAULT_POLLMASK (POLLIN \| POLLOUT \| POLLRDNORM \| POLLWRNORM)
		34
		35	static inline int
		36	init_file_info(struct file *file, unsigned int fake)
		37	{
		38	struct super_block *sb = file->f_dentry->d_sb;
		39	struct supermount_file_info *sfi;
		40	int rc;
		41
		42	ENTER(sb, "file=%p fake=%d", file, fake);
		43
		44	rc = 1;
		45	sfi = kmalloc(sizeof(*sfi), GFP_KERNEL);
		46	if (!sfi)
		47	goto out;
		48
		49	memset(sfi, 0, sizeof(*sfi));
		50
		51	INIT_LIST_HEAD(&sfi->list);
		52	sfi->host = file;
		53	sfi->owner = current->pid;
		54	sfi->vm_ops = 0;
		55	sfi->file = 0;
		56	sfi->fake = fake;
		57
		58	file->f_supermount = sfi;
		59
		60	rc = 0;
		61	out:
		62	LEAVE(sb, "file=%p fake=%d rc=%d", file, fake, rc);
		63
		64	return rc;
65	}
66
67	static inline void
68	attach_subfs_file(struct file file, struct file subfile)
69	{
70	struct super_block *sb = file->f_dentry->d_sb;
71	struct supermount_sb_info *sbi = supermount_sbi(sb);
72	struct supermount_file_info *sfi;
73
74	ENTER(sb, "file=%p subfile=%p", file, subfile);
75
76	sfi = supermount_f(file);
77	sfi->file = subfile;
78	list_add(&sfi->list, &sbi->s_files);
79
80	LEAVE(sb, "file=%p subfile=%p", file, subfile);
81	}
82
83	static inline int
84	prepare_file(struct file file, struct file subfile)
85	{
86	struct super_block *sb = file->f_dentry->d_sb;
87	int rc;
88
89	ENTER(sb, "file=%p subfile=%p", file, subfile);
90
91	subfs_lock(sb);
92
93	rc = -ENOMEDIUM;
94	if (!subfs_is_mounted(sb))
95	goto out;
96
97	rc = -ESTALE;
98	if (is_dentry_obsolete(file->f_dentry))
99	goto out;
100
101	rc = -ENOMEM;
102	if (init_file_info(file, 0))
103	goto out;
104
105	attach_subfs_file(file, subfile);
106	rc = 0;
107
108	out:
109	subfs_unlock(sb);
110
111	LEAVE(sb, "file=%p subfile=%p", file, subfile);
112
113	return rc;
114	}
115
116	struct file *
117	get_subfs_file(struct file *file)
118	{
119	struct super_block *sb = file->f_dentry->d_sb;
120	struct supermount_file_info *sfi = supermount_f(file);
121	struct file *err;
122
123	ENTER(sb, "file=%p", file);
124
125	subfs_lock(sb);
126
127	err = ERR_PTR(-ENOMEDIUM);
128	if (!subfs_is_mounted(sb))
129	goto out;
130
131	err = ERR_PTR(-ESTALE);
132	if (is_file_fake(file) \|\| is_file_obsolete(file))
133	goto out;
134
135	err = sfi->file;
136	SUPERMOUNT_BUG_LOCKED_ON(sb, !err->f_dentry);
137	SUPERMOUNT_BUG_LOCKED_ON(sb, !err->f_dentry->d_inode);
138	get_file(err);
139
140	out:
141	subfs_unlock(sb);
142
143	LEAVE(sb, "file=%p subfile=%p", file, err);
144
145	return err;
146	}
147
148	static loff_t
149	supermount_llseek(struct file *file, loff_t offset, int origin)
150	{
151	struct super_block *sb = file->f_dentry->d_sb;
152	struct file *subfile;
153	loff_t rc;
154
155	ENTER(sb, "file=%p offset=%lld origin=%d", file, offset, origin);
156
157	rc = -ESTALE;
158	if (subfs_check_disk_change(sb))
159	goto out;
160
161	subfile = get_subfs_file(file);
162	rc = PTR_ERR(subfile);
163	if (IS_ERR(subfile))
164	goto out;
165
166	if (subfile->f_op && subfile->f_op->llseek)
167	rc = subfile->f_op->llseek(subfile, offset, origin);
168	else
169	rc = default_llseek(subfile, offset, origin);
170	file->f_pos = subfile->f_pos;
171	file->f_version = subfile->f_version;
172
173	fput(subfile);
174	out:
175	LEAVE(sb, "file=%p rc=%lld", file, rc);
176
177	return rc;
178	}
179
180	static ssize_t
181	supermount_read(struct file file, char buf, size_t count, loff_t * ppos)
182	{
183	struct super_block *sb = file->f_dentry->d_sb;
184	struct inode *inode = file->f_dentry->d_inode;
185	struct file *subfile;
186	int write_on = NEED_WRITE_ATIME(inode);
187	int rc;
188
189	ENTER(sb, "file=%p", file);
190
191	rc = -ESTALE;
192	if (subfs_check_disk_change(sb))
193	goto out;
194
195	subfile = get_subfs_file(file);
196	rc = PTR_ERR(subfile);
197	if (IS_ERR(subfile))
198	goto out;
199
200	rc = -EINVAL;
201	if (!subfile->f_op \|\| !subfile->f_op->read)
202	goto put_subfile;
203
204	rc = subfs_get_access(inode, write_on);
205	if (rc)
206	goto put_subfile;
207
208	rc = subfile->f_op->read(subfile, buf, count, ppos);
209	subfs_put_access(inode, write_on);
210	if (rc < 0)
211	goto put_subfile;
212
213	inode->i_atime = subfile->f_dentry->d_inode->i_atime;
214
215	if (rc > 0)
216	file->f_pos = subfile->f_pos = *ppos;
217
218	put_subfile:
219	fput(subfile);
220	out:
221	LEAVE(sb, "file=%p rc=%d", file, rc);
222
223	return rc;
224	}
225
226	static ssize_t
227	supermount_write(struct file file, const char buf,
228	size_t count, loff_t * ppos)
229	{
230	struct super_block *sb = file->f_dentry->d_sb;
231	struct file *subfile;
232	int rc;
233
234	ENTER(sb, "file=%p", file);
235
236	rc = -ESTALE;
237	if (subfs_check_disk_change(sb))
238	goto out;
239
240	subfile = get_subfs_file(file);
241	rc = PTR_ERR(subfile);
242	if (IS_ERR(subfile))
243	goto out;
244
245	rc = 0;
246	if (subfile->f_op && subfile->f_op->write)
247	rc = subfile->f_op->write(subfile, buf, count, ppos);
248	if (rc > 0) {
249	struct inode *subinode = subfile->f_dentry->d_inode;
250
251	file->f_pos = subfile->f_pos = *ppos;
252	file->f_mode = subfile->f_mode;
253	file->f_dentry->d_inode->i_size = subinode->i_size;
254	file->f_dentry->d_inode->i_blocks = subinode->i_blocks;
255	file->f_dentry->d_inode->i_mode = subinode->i_mode;
256	file->f_dentry->d_inode->i_ctime = subinode->i_ctime;
257	file->f_dentry->d_inode->i_mtime = subinode->i_mtime;
258	}
259
260	fput(subfile);
261	out:
262	LEAVE(sb, "file=%p rc=%d", file, rc);
263
264	return rc;
265	}
266
267	int
268	supermount_readdir(struct file file, void buf, filldir_t fill_fn)
269	{
270	struct super_block *sb = file->f_dentry->d_sb;
271	struct inode *inode = file->f_dentry->d_inode;
272	struct file *subfile;
273	int write_on = NEED_WRITE_ATIME(inode);
274	int fake_readdir = 1;
275	int rc;
276
277	ENTER(sb, "file=%p", file);
278
279	rc = -ESTALE;
280	if (subfs_check_disk_change(sb))
281	goto out;
282
283	subfile = get_subfs_file(file);
284	rc = PTR_ERR(subfile);
285	if (IS_ERR(subfile))
286	goto out;
287
288	rc = -ENOTDIR;
289	if (!subfile->f_op \|\| !subfile->f_op->readdir)
290	goto put_subfile;
291
292	rc = subfs_get_access(inode, write_on);
293	if (rc)
294	goto put_subfile;
295
296	/* FIXME should it go before get_access? */
297	fake_readdir = 0;
298	rc = subfile->f_op->readdir(subfile, buf, fill_fn);
299	subfs_put_access(inode, write_on);
300	if (rc)
301	goto put_subfile;
302
303	inode->i_atime = subfile->f_dentry->d_inode->i_atime;
304	file->f_pos = subfile->f_pos;
305
306	put_subfile:
307	fput(subfile);
308	out:
309	if (fake_readdir && is_file_fake(file)) {
310	/* cf. supermount_open */
311	rc = 0;
312	}
313	LEAVE(sb, "file=%p rc=%d fpos=%lld", file, rc, file->f_pos);
314
315	return rc;
316	}
317
318	static unsigned int
319	supermount_poll(struct file file, struct poll_table_struct table)
320	{
321	struct super_block *sb = file->f_dentry->d_sb;
322	struct file *subfile;
323	int rc;
324
325	ENTER(sb, "file=%p", file);
326
327	rc = -ESTALE;
328	if (subfs_check_disk_change(sb))
329	goto out;
330
331	subfile = get_subfs_file(file);
332	rc = PTR_ERR(subfile);
333	if (IS_ERR(subfile))
334	goto out;
335
336	rc = DEFAULT_POLLMASK;
337	if (subfile->f_op && subfile->f_op->poll)
338	rc = subfile->f_op->poll(subfile, table);
339
340	fput(subfile);
341	out:
342	LEAVE(sb, "file=%p rc=%d", file, rc);
343
344	return rc;
345	}
346
347	static int
348	supermount_ioctl(struct inode inode, struct file file,
349	unsigned int cmd, unsigned long arg)
350	{
351	struct super_block *sb = file->f_dentry->d_sb;
352	struct file *subfile;
353	struct inode *subinode;
354	int rc;
355
356	ENTER(sb, "file=%p cmd=%u arg=%lu", file, cmd, arg);
357
358	rc = -ESTALE;
359	if (subfs_check_disk_change(sb))
360	goto out;
361
362	subfile = get_subfs_file(file);
363	rc = PTR_ERR(subfile);
364	if (IS_ERR(subfile))
365	goto out;
366
367	rc = -ENOTTY;
368	subinode = subfile->f_dentry->d_inode;
369	if (subfile->f_op && subfile->f_op->ioctl)
370	rc = subfile->f_op->ioctl(subinode, subfile, cmd, arg);
371
372	/* flags may have been changed by ioctl */
373	if (!rc)
374	set_inode_flags(file->f_dentry->d_inode, subinode);
375
376	fput(subfile);
377	out:
378	LEAVE(sb, "file=%p rc=%d", file, rc);
379
380	return rc;
381	}
382
383	int
384	supermount_open(struct inode inode, struct file file)
385	{
386	struct super_block *sb = inode->i_sb;
387	struct dentry *subdent;
388	struct file *subfile = 0;
389	struct vfsmount *submnt;
390	int write_on = file->f_mode & FMODE_WRITE;
391	int fake_open = 1;
392	int rc;
393
394	ENTER(sb, "inode=%p file=%p", inode, file);
395
396	rc = -ESTALE;
397	if (subfs_check_disk_change(sb))
398	goto out;
399
400	submnt = subfs_get_mnt(sb);
401	if (!submnt)
402	goto out;
403
404	subdent = get_subfs_dentry(file->f_dentry);
405	rc = PTR_ERR(subdent);
406	if (IS_ERR(subdent))
407	goto put_submnt;
408
409	rc = subfs_get_access(inode, write_on);
410	if (rc)
411	goto put_subdent;
412
413	/*
414	* the following is used to simplify error processing. dentry_open
415	* automatically does mntput and dput in error case, this may result
416	* in subfs being destroyed
417	* We just make sure we need to do mntput exactly once here;
418	* additionally it guards against accidental remounting of subfs
419	* until we has cleaned up
420	*/
421	submnt = mntget(submnt);
422	subdent = dget(subdent);
423
424	subfile = dentry_open(subdent, submnt, file->f_flags);
425	rc = PTR_ERR(subfile);
426	if (IS_ERR(subfile))
427	goto put_access;
428	/*
429	* no need to do extra mntput and dput, it is done automatically in
430	* dentry_open on error
431	*/
432
433	rc = prepare_file(file, subfile);
434	if (rc)
435	goto put_subfile;
436
437	subfile->f_mode = file->f_mode;
438	/*
439	* this is needed for mmap to work. In current model vm_area
440	* is associated with superfile; we never explicitly call
441	* any vm method with subfile as pointer. But many drivers
442	* attach private structures to this field and mmap of special
443	* files on supermount fs won't work without it
444	*/
445	file->private_data = subfile->private_data;
446	/*
447	* we have real subfile now, do not fake anything
448	*/
449	fake_open = 0;
450
451	/*
452	* Now get rid of extra mntget and dget
453	*/
454	goto put_subdent;
455
456	/*
457	* error cleanup
458	*/
459
460	put_subfile:
461	fput(subfile);
462	subfile = 0;
463	put_access:
464	subfs_put_access(inode, write_on);
465	put_subdent:
466	dput(subdent);
467	put_submnt:
468	mntput(submnt);
469	out:
470	if (fake_open && inode == sb->s_root->d_inode) {
471	/*
472	* always appear to succeed for root open. It allows active
473	* monitoring of mountpoint using FAM/dnotify and also is less
474	* surprising for other programs
475	*/
476	rc = init_file_info(file, 1);
477	if (rc)
478	rc = -ENOMEM;
479	}
480	LEAVE(sb, "inode=%p file=%p rc=%d subfile=0x%p", inode, file, rc, subfile);
481
482	return rc;
483	}
484
485	static int
486	supermount_flush(struct file *file)
487	{
488	struct super_block *sb = file->f_dentry->d_sb;
489	struct file *subfile;
490	int fake_flush = 1;
491	int rc;
492
493	ENTER(sb, "file=%p", file);
494
495	rc = -ESTALE;
496	if (subfs_check_disk_change(sb))
497	goto out;
498
499	subfile = get_subfs_file(file);
500	rc = PTR_ERR(subfile);
501	if (IS_ERR(subfile))
502	goto out;
503
504	rc = 0;
505	fake_flush = 0;
506	if (subfile->f_op && subfile->f_op->flush)
507	rc = subfile->f_op->flush(subfile);
508
509	fput(subfile);
510	out:
511	if (fake_flush && is_file_fake(file)) {
512	/* cf. supermount_open */
513	rc = 0;
514	}
515	LEAVE(sb, "file=%p rc=%d fake=%d", file, rc, fake_flush);
516
517	return rc;
518	}
519
520	/*
521	* if subfile is NULL it has already been released in supermount_clean_files
522	* together with adjusting open/write counters. Else we do it here.
523	*
524	* The reason is, it may be called long after media has been changed
525	* and we definitely do not want this function to mess up the
526	* new subfs state.
527	*/
528	static int
529	supermount_release(struct inode inode, struct file file)
530	{
531	struct file *subfile = 0;
532	struct super_block *sb = inode->i_sb;
533	struct supermount_file_info *sfi = file->f_supermount;
534
535	ENTER(sb, "inode=%p file=%p", inode, file);
536
537	subfs_lock(sb);
538	/*
539	* FIXME
540	* this sucks. But there does not seem to be any way
541	* to distinguish between ENOMEM on _open (legitimate
542	* case) and anything else (plain bug)
543	*/
544	if (sfi) {
545	list_del(&sfi->list);
546	subfile = sfi->file;
547	sfi->file = 0;
548	} else
549	supermount_warning(sb, "no supermount file info attached");
550	subfs_unlock(sb);
551
552	if (subfile) {
553	int bug = atomic_read(&subfile->f_count) != 1;
554	fput(subfile);
555	subfs_put_access(inode, file->f_mode & FMODE_WRITE);
556	SUPERMOUNT_BUG_ON(bug);
557	}
558
559	if (sfi)
560	kfree(sfi);
561
562	LEAVE(sb, "inode=%p file=%p", inode, file);
563
564	return 0;
565
566	}
567
568	static int
569	supermount_fsync(struct file file, struct dentry dentry, int datasync)
570	{
571	struct super_block *sb = file->f_dentry->d_sb;
572	struct file *subfile;
573	int rc;
574
575	ENTER(sb, "file=%p dentry=%s sync=%d", file, dentry->d_name.name, datasync);
576
577	rc = -ESTALE;
578	if (subfs_check_disk_change(sb))
579	goto out;
580
581	subfile = get_subfs_file(file);
582	rc = PTR_ERR(subfile);
583	if (IS_ERR(subfile))
584	goto out;
585
586	rc = -EINVAL;
587	if (subfile->f_op && subfile->f_op->fsync)
588	rc = subfile->f_op->fsync(subfile, subfile->f_dentry, datasync);
589
590	fput(subfile);
591	out:
592	ENTER(sb, "file=%p dentry=%s rc=%d", file, dentry->d_name.name, rc);
593
594	return rc;
595	}
596
597	static int
598	supermount_fasync(int fd, struct file *file, int on)
599	{
600	struct super_block *sb = file->f_dentry->d_sb;
601	struct file *subfile;
602	int rc;
603
604	ENTER(sb, "fd=%d file=%p on=%d", fd, file, on);
605
606	rc = -ESTALE;
607	if (subfs_check_disk_change(sb))
608	goto out;
609
610	subfile = get_subfs_file(file);
611	rc = PTR_ERR(subfile);
612	if (IS_ERR(subfile))
613	goto out;
614
615	rc = -EINVAL;
616	if (subfile->f_op && subfile->f_op->fasync)
617	rc = subfile->f_op->fasync(fd, subfile, on);
618
619	fput(subfile);
620	out:
621	LEAVE(sb, "fd=%d file=%p rc=%d", fd, file, rc);
622
623	return rc;
624	}
625
626	static int
627	supermount_lock(struct file file, int cmd, struct file_lock fl)
628	{
629	struct super_block *sb = file->f_dentry->d_sb;
630	struct file *subfile;
631	int rc;
632
633	ENTER(sb, "file=%p cmd=%d", file, cmd);
634
635	rc = -ESTALE;
636	if (subfs_check_disk_change(sb))
637	goto out;
638
639	subfile = get_subfs_file(file);
640	rc = PTR_ERR(subfile);
641	if (IS_ERR(subfile))
642	goto out;
643
644	rc = 0;
645	if (subfile->f_op && subfile->f_op->lock)
646	rc = subfile->f_op->lock(subfile, cmd, fl);
647	else if (cmd == F_GETLK)
648	posix_test_lock(file, fl);
649
650	fput(subfile);
651	out:
652	LEAVE(sb, "file=%p rc=%d", file, rc);
653
654	return rc;
655	}
656
657	/* Fixme:
658	* readv: easy, export churnk from vfs
659	* writev: easy, export churnk from vfs
660	* sendpage: only used for networking, not needed
661	* get_unmmapped_area: only used for devices, not needed
662	*/
663
664	struct file_operations supermount_dir_operations = {
665	.llseek = supermount_llseek,
666	.read = supermount_read,
667	.readdir = supermount_readdir,
668	.ioctl = supermount_ioctl,
669	.open = supermount_open,
670	.flush = supermount_flush,
671	.release = supermount_release,
672	.fsync = supermount_fsync,
673	.fasync = supermount_fasync,
674	};
675
676	struct file_operations supermount_file_operations = {
677	.llseek = supermount_llseek,
678	.read = supermount_read,
679	.write = supermount_write,
680	.poll = supermount_poll,
681	.ioctl = supermount_ioctl,
682	.mmap = supermount_file_mmap, /* from filemap.c */
683	.open = supermount_open,
684	.flush = supermount_flush,
685	.release = supermount_release,
686	.fsync = supermount_fsync,
687	.fasync = supermount_fasync,
688	.lock = supermount_lock,
689	};

Line 0 Link Here

(-)linux-2.6.8.1_supermount/fs/supermount/filemap.c (+182 lines)
		1	/*
		2	* linux/fs/supermount/filemap.c
		3	*
		4	* Initial version for kernel 2.4.21 (C) 2003 Andrey Borzenkov
		5	* (arvidjaar@mail.ru)
		6	*
		7	* $Id: 4715_supermount-2.0.4-2.6.7.patch,v 1.1 2004/06/22 22:15:04 gregkh Exp $
		8	*/
		9
		10	#define S_DBG_TRACE_CURRENT S_DBG_TRACE_FILEMAP
		11	#include "supermount.h"
		12
		13	/*
		14	* Some rationale and justification for this file
		15	*
		16	* We play dirty tricks with mm management for mmaped files on supermount.
		17	* Address space points to subinode but vm area is associated with superfile.
		18	* When media change is detected, subinode together with all associated
		19	* pages goes away as well (at least, I hope so ...) Now we must prevent
		20	* any attempt to access no more existing address space. To do so we save
		21	* original vm_ops in private field and replace them with vm_ops in this file.
		22	* They check if file is stale, if yes, they try to return sensible error.
		23	* There is some doubt about possibility to block here ... OTOH any write
		24	* lock on subfs is hold in context where no mm lock is expected.
		25	*/
		26	static void
		27	supermount_vm_open(struct vm_area_struct *area)
		28	{
		29	struct file file = area->vm_file, subfile;
		30	struct super_block *sb = file->f_dentry->d_sb;
		31	struct supermount_file_info *sfi;
		32
		33	ENTER(sb, "vm=%p", area);
		34
		35	if (subfs_check_disk_change(sb))
		36	goto out;
		37
		38	subfile = get_subfs_file(file);
		39	if (IS_ERR(subfile))
		40	goto out;
		41
		42	sfi = supermount_f(file);
		43	if (sfi->vm_ops && sfi->vm_ops->open)
		44	sfi->vm_ops->open(area);
		45
		46	fput(subfile);
		47	out:
		48	LEAVE(sb, "vm=%p", area);
		49
		50	return;
		51	}
		52
		53	static void
		54	supermount_vm_close(struct vm_area_struct *area)
		55	{
		56	struct file file = area->vm_file, subfile;
		57	struct super_block *sb = file->f_dentry->d_sb;
		58	struct supermount_file_info *sfi;
		59
		60	ENTER(sb, "vm=%p", area);
		61
		62	if (subfs_check_disk_change(sb))
		63	goto out;
		64
65	subfile = get_subfs_file(file);
66	if (IS_ERR(subfile))
67	goto out;
68
69	sfi = supermount_f(file);
70	if (sfi->vm_ops && sfi->vm_ops->close)
71	sfi->vm_ops->close(area);
72
73	fput(subfile);
74	out:
75	LEAVE(sb, "vm=%p", area);
76
77	return;
78	}
79
80	static struct page *
81	supermount_vm_nopage(struct vm_area_struct area, unsigned long address, int type)
82	{
83	struct file file = area->vm_file, subfile;
84	struct super_block *sb = file->f_dentry->d_sb;
85	struct supermount_file_info *sfi;
86	struct page *page = 0;
87
88	ENTER(sb, "vm=%p addr=%lx", area, address);
89
90	/*
91	* this is called with mm semaphore down read and pagetable
92	* spinlock released. So it _appears_ safe to sleep ...
93	*/
94	if (subfs_check_disk_change(sb))
95	goto out;
96
97	subfile = get_subfs_file(file);
98	if (IS_ERR(subfile))
99	goto out;
100
101	sfi = supermount_f(file);
102	page = sfi->vm_ops->nopage(area, address, type);
103
104	fput(subfile);
105	out:
106	LEAVE(sb, "vm=%p page=%p", area, page);
107
108	return page;
109	}
110
111	int
112	supermount_file_mmap(struct file file, struct vm_area_struct vma)
113	{
114
115	struct super_block *sb = file->f_dentry->d_sb;
116	struct inode *inode = file->f_dentry->d_inode;
117	struct supermount_file_info *sfi;
118	struct file *subfile;
119	int write_on = NEED_WRITE_ATIME(inode);
120	int rc;
121
122	ENTER(sb, "file=%p vm=%p", file, vma);
123
124	rc = -ESTALE;
125	if (subfs_check_disk_change(sb))
126	goto out;
127
128	subfile = get_subfs_file(file);
129	rc = PTR_ERR(subfile);
130	if (IS_ERR(subfile))
131	goto out;
132
133	sfi = supermount_f(file);
134
135	rc = -ENODEV;
136	if (!subfile->f_op \|\| !subfile->f_op->mmap)
137	goto put_subfile;
138
139	rc = subfs_get_access(inode, write_on);
140	if (rc)
141	goto put_subfile;
142
143	rc = subfile->f_op->mmap(subfile, vma);
144	subfs_put_access(inode, write_on);
145	if (rc)
146	goto put_subfile;
147	/*
148	* we cannot deal with anonymous mapping
149	*/
150	if (!vma->vm_ops \|\| !vma->vm_ops->nopage) {
151	rc = -ENOSYS;
152	goto put_subfile;
153	}
154
155	/*
156	* now do the nasty trick
157	*/
158	sfi->vm_ops = vma->vm_ops;
159	vma->vm_ops = &supermount_vm_ops;
160
161	put_subfile:
162	fput(subfile);
163	out:
164	LEAVE(sb, "file=%p vm=%p rc=%d", file, vma, rc);
165
166	return rc;
167	}
168
169	/*
170	* ->populate: to properly implement it it should call do_no_page if
171	* subfs does not provide its own ->populate. Unfortunately
172	* populate gets different parameters. Translating them into
173	* what ->nopage expects just does not worth it - currently
174	* supermount is slow enough to bother about this imaginary
175	* speed up even if it was possible (which probably is not
176	* due to how locking is done; see mm/memory.c).
177	*/
178	struct vm_operations_struct supermount_vm_ops = {
179	.open = supermount_vm_open,
180	.close = supermount_vm_close,
181	.nopage = supermount_vm_nopage,
182	};

Line 0 Link Here

(-)linux-2.6.8.1_supermount/fs/supermount/init.c (+48 lines)
	1	/*
	2	* linux/fs/supermount/init.c
	3	*
	4	* (C) Copyright 2001-2002 Juan Quintela <quintela@mandrakesoft.com>
	5	* Released unde GPL v2.
	6	* Rewritten for kernel 2.4.21 (C) 2003 Andrey Borzenkov
	7	* (arvidjaar@mail.ru)
	8	* Rewritten for kernel 2.5.70 (C) 2003 Andrey Borzenkov
	9	* (arvidjaar@mail.ru)
	10	*
	11	* $Id: 4715_supermount-2.0.4-2.6.7.patch,v 1.1 2004/06/22 22:15:04 gregkh Exp $
	12	*/
	13
	14	#include "supermount.h"
	15
	16	struct file_system_type supermount_fs_type = {
	17	.owner = THIS_MODULE,
	18	.name = "supermount",
	19	.get_sb = supermount_get_sb,
	20	.kill_sb = kill_anon_super,
	21	.fs_flags = FS_NO_SUBMNT,
	22	};
	23
	24	static int __init
	25	init_supermount_fs(void)
	26	{
	27	int rc = register_filesystem(&supermount_fs_type);
	28
	29	if (!rc) {
	30	printk(KERN_INFO "Supermount version %s for kernel 2.6\n", SUPERMOUNT_VERSION);
	31	supermount_proc_register();
	32	}
	33
	34	return rc;
	35	}
	36
	37	static void __exit
	38	exit_supermount_fs(void)
	39	{
	40	supermount_proc_unregister();
	41	unregister_filesystem(&supermount_fs_type);
	42	}
	43
	44	MODULE_AUTHOR("Stephen Tweedie, Alexis Mikhailov, Juan Quintela, Andrey Borzenkov and others");
	45	MODULE_DESCRIPTION("Transparent removable media support");
	46	MODULE_LICENSE("GPL");
	47	module_init(init_supermount_fs);
	48	module_exit(exit_supermount_fs);

Line 0 Link Here

(-)linux-2.6.8.1_supermount/fs/supermount/mediactl.c (+69 lines)
		1	/*
		2	* linux/fs/supermount/mediactl.c
		3	*
		4	* Original version:
		5	* Copyright (C) 1995, 1997
		6	* Stephen Tweedie (sct@dcs.ed.ac.uk)
		7	*
		8	* Rewriten for kernel 2.2, 2.4. (C) 1999, 2000 Alexis Mikhailov
		9	* (alexis@abc.cap.ru)
		10	* Rewritten for kernel 2.4.21 (C) 2003 Andrey Borzenkov
		11	* (arvidjaar@mail.ru)
		12	* Rewritten for kernel 2.5.70 (C) 2003 Andrey Borzenkov
		13	* (arvidjaar@mail.ru)
		14	*
		15	* $Id: 4715_supermount-2.0.4-2.6.7.patch,v 1.1 2004/06/22 22:15:04 gregkh Exp $
		16	*/
		17
		18	#define S_DBG_TRACE_CURRENT S_DBG_TRACE_MEDIACTL
		19	#include "supermount.h"
		20
		21	/*
		22	* Try to lock the drive door. This is not guaranteed to work on all
		23	* hardware, but we try any tricks we know of anyway.
		24	*/
		25	void
		26	supermount_mediactl(struct super_block *sb, int operation, int opt)
		27	{
		28	struct block_device *bdev;
		29	struct super_block *subsb;
		30	struct block_device_operations *fops = 0;
		31
		32	if (!subfs_is_mounted(sb))
		33	return;
		34
		35	subsb = subfs_sb(sb);
		36	bdev = subsb->s_bdev;
		37	if (!bdev->bd_disk)
		38	return;
		39
		40	/* FIXME is it enough to use bd_sem here? */
		41	switch (operation) {
		42	case SUPERMOUNT_INC_COUNT:
		43	lock_kernel();
		44	SUPERMOUNT_BUG_ON(bdev->bd_disk->scount < 0);
		45	bdev->bd_disk->scount++;
		46	unlock_kernel();
		47	return;
		48	case SUPERMOUNT_DEC_COUNT:
		49	lock_kernel();
		50	SUPERMOUNT_BUG_ON(bdev->bd_disk->scount <= 0);
		51	bdev->bd_disk->scount--;
		52	unlock_kernel();
		53	return;
		54	}
		55
		56	fops = bdev->bd_disk->fops;
		57	if (!fops \|\| !fops->mediactl)
		58	return;
		59	/*
		60	* tray is (un-)locked in open (BKL for bdev), release (BKL for bdev)
		61	* and ioctl (BKL). We are in good company.
		62	* This must be changed if block devices ever stop using BKL
		63	* for open/release. Unfortunately, using just bdev->bd_sem is not
		64	* enough due to ioctl.
65	*/
66	lock_kernel();
67	fops->mediactl(bdev, operation, opt);
68	unlock_kernel();
69	}

Line 0 Link Here

(-)linux-2.6.8.1_supermount/fs/supermount/proc.c (+289 lines)
		1	/*
		2	* linux/fs/supermount/proc.c
		3	*
		4	* Initial version for kernel 2.4.21 (C) 2003 Andrey Borzenkov
		5	* (arvidjaar@mail.ru)
		6	* Rewritten for kernel 2.5.70 (C) 2003 Andrey Borzenkov
		7	* (arvidjaar@mail.ru)
		8	*
		9	* $Id: 4715_supermount-2.0.4-2.6.7.patch,v 1.1 2004/06/22 22:15:04 gregkh Exp $
		10	*/
		11
		12	#include "supermount.h"
		13
		14	#ifdef CONFIG_PROC_FS
		15
		16	/*
		17	* we use semaphore because we have to lock subfs inside and it can
		18	* sleep. Unlocking procfs list would mean adding generic usage count
		19	* management to sbi and this is far too fetching
		20	*/
		21
		22	static DECLARE_MUTEX(supermount_proc_sem);
		23	static struct proc_dir_entry *supermount_proc_root;
		24	static struct proc_dir_entry *supermount_proc_subfs;
		25	static struct proc_dir_entry *supermount_proc_version;
		26	static struct supermount_sb_info *supermount_list_head;
		27
		28	#define SKIP_BLANKS(s) while(s == ' ' \|\| s == '\t' \|\| *s == '\n') s++
		29	#define CHECK_COUNT do { \
		30	size += n; \
		31	count -= n; \
		32	if (count <= 0) { \
		33	subfs_unlock(sbi->host); \
		34	break; \
		35	} \
		36	} while (0)
		37
		38	/* iterator; shamelessly copied over from pci.c */
		39	static void supermount_seq_start(struct seq_file sf, loff_t *pos)
		40	{
		41	struct supermount_sb_info *sbi;
		42	loff_t n = *pos;
		43
		44	down(&supermount_proc_sem);
		45
		46	sbi = supermount_list_head;
		47	while (n-- && sbi)
		48	sbi = sbi->next;
		49
		50	return sbi;
		51	}
		52
		53	static void supermount_seq_next(struct seq_file sf, void v, loff_t pos)
		54	{
		55	struct supermount_sb_info *sbi = v;
		56	(*pos)++;
		57	return sbi->next;
		58	}
		59
		60	static void supermount_seq_stop(struct seq_file sf, void v)
		61	{
		62	up(&supermount_proc_sem);
		63	}
		64
65
66	static int
67	supermount_show_sbi(struct seq_file sf, void v)
68	{
69	struct supermount_sb_info *sbi = v;
70
71
72	subfs_lock(sbi->host);
73	seq_puts(sf, sbi->devname);
74	if (sbi->disabled)
75	seq_puts(sf, " disabled\n");
76	else if (subfs_is_mounted(sbi->host))
77	seq_printf(sf, " mounted %d %d\n",
78	sbi->readcount, sbi->writecount);
79	else
80	seq_puts(sf, " unmounted\n");
81	subfs_unlock(sbi->host);
82
83	return 0;
84	}
85
86	static struct seq_operations supermount_proc_subfs_op = {
87	start: supermount_seq_start,
88	next: supermount_seq_next,
89	stop: supermount_seq_stop,
90	show: supermount_show_sbi
91	};
92
93	static int supermount_proc_subfs_open(struct inode inode, struct file file)
94	{
95	return seq_open(file, &supermount_proc_subfs_op);
96	}
97
98	/*
99	* mostly copied over from drivers/scsi/scsi.c:proc_scsi_gen_write()
100	*/
101	static int
102	supermount_proc_subfs_write(struct file file, const char buf, size_t length, loff_t *offset)
103	{
104	char buffer, s, *dev = 0;
105	int disable = 0, enable = 0, release = 0, force = 0;
106	struct supermount_sb_info *sbi;
107	size_t rc;
108
109	rc = -EINVAL;
110	if (!buf \|\| length > PAGE_SIZE)
111	goto out;
112
113	rc = -ENOMEM;
114	if (!(s = buffer = (char *)__get_free_page(GFP_KERNEL)))
115	goto out;
116
117	rc =-EFAULT;
118	if(copy_from_user(buffer, buf, length))
119	goto free_buffer;
120
121	rc = -EINVAL;
122	if (length < PAGE_SIZE)
123	buffer[length] = '\0';
124	else if (buffer[PAGE_SIZE-1])
125	goto free_buffer;
126
127	/*
128	* echo "/dev/cdrom [enable\|disable] [release [force]]" > \
129	* /proc/fs/supermount/subfs
130	*/
131
132	do {
133	char *p;
134
135	SKIP_BLANKS(s);
136	p = strpbrk(s, " \t\n");
137	if (p)
138	*p++ = '\0';
139	if (!dev)
140	dev = s;
141	else if (!strcmp(s, "disable"))
142	disable = 1;
143	else if (!strcmp(s, "enable"))
144	enable = 1;
145	else if (!strcmp(s, "release"))
146	release = 1;
147	else if (!strcmp(s, "force"))
148	force = 1;
149	else
150	goto free_buffer;
151
152	s = p;
153	} while (s && *s);
154
155	if ((enable && disable) \|\| (force && !release))
156	goto free_buffer;
157
158	down(&supermount_proc_sem);
159	for(sbi = supermount_list_head; sbi; sbi = sbi->next) {
160	if (strcmp(sbi->devname, dev))
161	continue;
162
163	subfs_lock(sbi->host);
164
165	rc = length;
166	if (release && subfs_is_mounted(sbi->host)) {
167	if (!subfs_is_busy(sbi->host) \|\| force)
168	subfs_umount(sbi->host, SUBFS_UMNT_USER);
169	else
170	rc = -EBUSY;
171	}
172
173	if (disable && subfs_is_mounted(sbi->host))
174	rc = -EBUSY;
175
176	if (rc >= 0) {
177	if (disable)
178	sbi->disabled = 1;
179	else if (enable)
180	sbi->disabled = 0;
181	}
182
183	subfs_unlock(sbi->host);
184	break;
185	}
186	up(&supermount_proc_sem);
187
188	free_buffer:
189	free_page((unsigned long)buffer);
190	out:
191	return rc;
192
193	}
194
195	static struct file_operations supermount_proc_subfs_operations = {
196	open: supermount_proc_subfs_open,
197	read: seq_read,
198	llseek: seq_lseek,
199	release: seq_release,
200	write: supermount_proc_subfs_write,
201	};
202
203	static int
204	supermount_proc_version_read(char page, char start, off_t pos, int count, int eof, void *data)
205	{
206	int rc;
207
208	rc = snprintf(page, count, "Supermount version %s for kernel 2.6\n",
209	SUPERMOUNT_VERSION);
210	*eof = 1;
211	return rc;
212	}
213
214	void
215	supermount_proc_register(void)
216	{
217	supermount_proc_root = proc_mkdir("fs/supermount", 0);
218	if (!supermount_proc_root) {
219	printk(KERN_ERR "SUPERMOUNT failed to create /proc/fs/supermount");
220	return;
221	}
222	supermount_proc_root->owner = THIS_MODULE;
223
224	supermount_proc_version = create_proc_read_entry("version",
225	S_IFREG \| S_IRUGO,
226	supermount_proc_root,
227	supermount_proc_version_read,
228	0);
229
230	if (supermount_proc_version)
231	supermount_proc_version->owner = THIS_MODULE;
232	else
233	printk(KERN_ERR
234	"SUPERMOUNT failed to create /proc/fs/supermount/version");
235
236	supermount_proc_subfs = create_proc_entry("subfs",
237	S_IFREG \| S_IRUGO \| S_IWUSR,
238	supermount_proc_root);
239
240	if (supermount_proc_subfs) {
241	supermount_proc_subfs->proc_fops =
242	&supermount_proc_subfs_operations;
243	supermount_proc_subfs->owner = THIS_MODULE;
244	} else
245	printk(KERN_ERR
246	"SUPERMOUNT failed to create /proc/fs/supermount/subfs");
247
248	}
249
250	void
251	supermount_proc_unregister(void)
252	{
253	remove_proc_entry("fs/supermount/subfs", 0);
254	remove_proc_entry("fs/supermount/version", 0);
255	remove_proc_entry("fs/supermount", 0);
256	}
257
258	void
259	supermount_proc_insert(struct supermount_sb_info *sbi)
260	{
261
262	down(&supermount_proc_sem);
263
264	sbi->next = supermount_list_head;
265	supermount_list_head = sbi;
266
267	up(&supermount_proc_sem);
268	}
269
270	void
271	supermount_proc_remove(struct supermount_sb_info *sbi)
272	{
273	struct supermount_sb_info *p, q;
274
275	down(&supermount_proc_sem);
276
277	for(p = &supermount_list_head, q = supermount_list_head;
278	q; p = &q->next, q = q->next)
279	if (q == sbi)
280	break;
281
282	if (q)
283	*p = q->next;
284
285	up(&supermount_proc_sem);
286
287	SUPERMOUNT_BUG_ON(!q);
288	}
289	#endif /* CONFIG_PROC_FS */

Line 0 Link Here

(-)linux-2.6.8.1_supermount/fs/supermount/subfs.c (+742 lines)
		1	/*
		2	* linux/fs/supermount/subfs.c
		3	*
		4	* Original version:
		5	* Copyright (C) 1995, 1997
		6	* Stephen Tweedie (sct@dcs.ed.ac.uk)
		7	*
		8	* from
		9	*
		10	* linux/fs/minix/inode.c
		11	* Copyright (C) 1991, 1992 Linus Torvalds
		12	*
		13	* and
		14	*
		15	* linux/fs/ext2/super.c
		16	* Copyright (C) 1992, 1993, 1994, 1995 Remy Card
		17	*
		18	* Rewriten for kernel 2.2, 2.4. (C) 1999, 2000 Alexis Mikhailov
		19	* (alexis@abc.cap.ru)
		20	* Rewritten for kernel 2.4.21 (C) 2003 Andrey Borzenkov
		21	* (arvidjaar@mail.ru)
		22	* Rewritten for kernel 2.5.70 (C) 2003 Andrey Borzenkov
		23	* (arvidjaar@mail.ru)
		24	*
		25	* $Id: 4715_supermount-2.0.4-2.6.7.patch,v 1.1 2004/06/22 22:15:04 gregkh Exp $
		26	*/
		27
		28	#define S_DBG_TRACE_CURRENT S_DBG_TRACE_SUBFS
		29	#include "supermount.h"
		30
		31	/*
		32	* close all open files on subfs
		33	*/
		34	static void
		35	supermount_clean_files(struct super_block *sb)
		36	{
		37	struct supermount_sb_info *sbi = supermount_sbi(sb);
		38	struct list_head ptr, n;
		39
		40	ENTER(sb);
		41
		42	list_for_each_safe(ptr, n, &sbi->s_files) {
		43	struct supermount_file_info *sfi;
		44	struct file *subfile;
		45
		46	sfi = list_entry(ptr, struct supermount_file_info, list);
		47
		48	subfile = sfi->file;
		49	sfi->file = 0;
		50	list_del_init(&sfi->list);
		51
		52	SUPERMOUNT_BUG_LOCKED_ON(sb, !subfile);
		53
		54	fput(subfile);
		55	}
		56
		57	LEAVE(sb);
		58
		59	}
		60
		61	/*
		62	* close all open dentries on subfs
		63	*/
		64	static void
65	supermount_clean_dentries(struct super_block *sb)
66	{
67	struct supermount_sb_info *sbi = supermount_sbi(sb);
68	struct list_head ptr, n;
69
70	ENTER(sb);
71
72	list_for_each_safe(ptr, n, &sbi->s_dentries) {
73	struct supermount_dentry_info *sdi;
74	struct dentry *subdent;
75
76	sdi = list_entry(ptr, struct supermount_dentry_info, list);
77	/*
78	* HACK - FIXME
79	* see dentry.c:supermount_d_compare
80	*/
81	write_lock(&d_compare_lock);
82	subdent = sdi->dentry;
83	sdi->dentry = 0;
84	write_unlock(&d_compare_lock);
85
86	list_del_init(&sdi->list);
87	d_drop(sdi->host);
88	dnotify_parent(sdi->host, DN_DELETE);
89
90	SUPERMOUNT_BUG_LOCKED_ON(sb, !subdent);
91
92	dput(subdent);
93	}
94
95	LEAVE(sb);
96
97	}
98
99	/*
100	* close all open inodes on subfs
101	*/
102	static void
103	supermount_clean_inodes(struct super_block *sb)
104	{
105	struct supermount_sb_info *sbi = supermount_sbi(sb);
106	struct list_head ptr, n;
107
108	ENTER(sb);
109
110	list_for_each_safe(ptr, n, &sbi->s_inodes) {
111	struct supermount_inode_info *sii;
112	struct inode *host;
113	struct inode *subi;
114
115	sii = list_entry(ptr, struct supermount_inode_info, list);
116	host = &sii->vfs_inode;
117
118	subi = sii->inode;
119	sii->inode = NULL;
120	list_del_init(&sii->list);
121	remove_inode_hash(host);
122	host->i_mapping = &host->i_data;
123
124	/*
125	* it is possible to have no subi here. clear_inode does
126	* release lock after removing subi but before unlinking
127	* it
128	*/
129	if (subi)
130	iput(subi);
131
132	SUPERMOUNT_BUG_LOCKED_ON(sb, sii->writecount < 0);
133	SUPERMOUNT_BUG_LOCKED_ON(sb, sii->readcount < 0);
134	while (sii->writecount) {
135	sii->writecount--;
136	sbi->writecount--;
137	}
138	while (sii->readcount) {
139	sii->readcount--;
140	sbi->readcount--;
141	}
142	}
143
144	LEAVE(sb);
145	}
146
147	/*
148	* reason can be
149	* SUBFS_UMNT_NORMAL - normal umount, do not try to release subfs
150	* SUBFS_UMNT_MEDIA - media change detected, release subfs,
151	* do not remount ro (as media is already gone)
152	* SUBFS_UMNT_USER - user request, release subfs, remount ro before
153	* releasing tray lock
154	*
155	* unlock_door is always needed to keep device usage count correct
156	*/
157	static inline int subfs_remount_ro(struct super_block *sb);
158	void
159	subfs_umount(struct super_block *sb, int reason)
160	{
161	struct supermount_sb_info *sbi = supermount_sbi(sb);
162	int writecount = sbi->writecount;
163
164	ENTER(sb);
165
166	if (reason != SUBFS_UMNT_NORMAL) {
167	/*
168	* we used to did shrink_dcache here. It compicates locking
169	* (clear_inode is called under sbi->sem thus requiring either
170	* recursive lock or separate lock just for inode list).
171	* This is not needed any more to ensure subfs can be umounted
172	* so we let dentries die and rely on dentry_revalidate to
173	* reject stale dentries
174	*/
175
176	if (subfs_is_busy(sb))
177	supermount_warning(sb, "opened files during media change");
178
179	supermount_clean_files(sb);
180	supermount_clean_dentries(sb);
181	supermount_clean_inodes(sb);
182
183	if (reason == SUBFS_UMNT_USER && writecount > 0)
184	subfs_remount_ro(sb);
185	if (sbi->lockcount > 0)
186	supermount_unlock_door(sb);
187	/*
188	* this is quite ugly but so far I have no idea how to
189	* do it cleanly
190	*/
191	sbi->lockcount = 0;
192	}
193
194	/*
195	* all files are expected to be closed
196	*/
197	SUPERMOUNT_BUG_LOCKED_ON(sb, sbi->writecount);
198	SUPERMOUNT_BUG_LOCKED_ON(sb, sbi->readcount);
199	SUPERMOUNT_BUG_LOCKED_ON(sb, sbi->lockcount);
200	SUPERMOUNT_BUG_LOCKED_ON(sb, !list_empty(&sbi->s_files));
201	SUPERMOUNT_BUG_LOCKED_ON(sb, !list_empty(&sbi->s_dentries));
202	SUPERMOUNT_BUG_LOCKED_ON(sb, !list_empty(&sbi->s_inodes));
203
204	unmark_media_supermounted(sb);
205	mntput(sbi->s_undermount);
206	sbi->s_undermount = NULL;
207	if (sbi->rw)
208	sb->s_flags &= ~MS_RDONLY;
209	sb->s_blocksize = 1024;
210	sb->s_blocksize_bits = 10;
211
212	/*
213	* FIXME
214	* again the problem of unmounting subfs from inside of put_super
215	*/
216	if (sb->s_root)
217	supermount_init_root_inode(sb->s_root->d_inode);
218
219	LEAVE(sb);
220	}
221
222	static inline int
223	subfs_remount_ro(struct super_block *sb)
224	{
225	struct super_block *subsb = subfs_sb(sb);
226	int rc;
227
228	ENTER(sb);
229
230	rc = do_remount_sb(subsb, subsb->s_flags \| MS_RDONLY, NULL, 0);
231
232	LEAVE(sb);
233
234	return rc;
235	}
236
237	static inline int
238	subfs_remount_rw(struct super_block *sb)
239	{
240	struct super_block *subsb = subfs_sb(sb);
241	int rc;
242
243	ENTER(sb);
244
245	rc = do_remount_sb(subsb, subsb->s_flags & ~MS_RDONLY, NULL, 0);
246
247	LEAVE(sb);
248
249	return rc;
250	}
251
252	static struct vfsmount *
253	subfs_real_mount(struct super_block sb, char type)
254	{
255	struct supermount_sb_info *sbi = supermount_sbi(sb);
256	struct vfsmount *mnt;
257	char *opts = NULL;
258
259	ENTER(sb, "type=%s", type);
260
261	if (sbi->s_data) {
262	opts = strdup(sbi->s_data);
263	if (!opts) {
264	mnt = ERR_PTR(-ENOMEM);
265	goto fail;
266	}
267	}
268
269	mnt = do_kern_mount(type,
270	(sb->s_flags & MS_RMT_MASK) \| MS_SUPERMOUNTED,
271	sbi->devname, opts);
272	if (opts)
273	kfree(opts);
274
275	fail:
276	LEAVE(sb, "submnt=%p", mnt);
277
278	return mnt;
279	}
280
281	static int
282	subfs_real_mount2(struct super_block sb, char type)
283	{
284	struct supermount_sb_info *sbi = supermount_sbi(sb);
285	struct vfsmount *mnt;
286	struct super_block *subsb;
287	int rc = 0;
288
289	ENTER(sb, "type=%s", type);
290
291	mnt = subfs_real_mount(sb, type);
292
293	if (IS_ERR(mnt) && PTR_ERR(mnt) == -EROFS) {
294	sb->s_flags \|= MS_RDONLY;
295	mnt = subfs_real_mount(sb, type);
296	}
297	rc = PTR_ERR(mnt);
298	if (IS_ERR(mnt))
299	goto out;
300
301	/* paranoid check for double-mounting */
302	SUPERMOUNT_BUG_LOCKED_ON(sb, atomic_read(&mnt->mnt_sb->s_active) != 1);
303
304	sbi->s_undermount = mnt;
305
306	if (!(sb->s_flags & MS_RDONLY)) {
307	rc = subfs_remount_ro(sb);
308	if (rc)
309	goto mntput;
310	}
311
312	subsb = mnt->mnt_sb;
313	sb->s_blocksize = subsb->s_blocksize;
314	sb->s_blocksize_bits = subsb->s_blocksize_bits;
315	attach_subfs_dentry(sb->s_root, mnt->mnt_root);
316	attach_subfs_inode(sb->s_root->d_inode, mnt->mnt_root->d_inode);
317	insert_inode_hash(sb->s_root->d_inode);
318	dnotify_parent(sb->s_root, DN_CREATE);
319	rc = 0;
320	goto out;
321
322	/*
323	* error clean up
324	*/
325	mntput:
326	sbi->s_undermount = 0;
327	mntput(mnt);
328	out:
329	LEAVE(sb, "type=%s rc=%d", type, rc);
330
331	return rc;
332	}
333
334	/*
335	* Error values from mount
336	* ENOENT - no device file (quite possible with devfs)
337	* ENXIO - device does not exist
338	* ENOMEDIUM - no medium inserted (surprise, surprise :)
339	* EBUSY - attempt to mount on already mounted device
340	* we specifically disallow it even when both
341	* file system and mode (ro/rw) are the same
342	*/
343	static int
344	subfs_mount(struct super_block *sb)
345	{
346	struct supermount_sb_info *sbi = supermount_sbi(sb);
347	int retval = -ENODEV;
348	char *types = strdup(sbi->s_type);
349
350	ENTER(sb);
351
352	if (sbi->disabled)
353	retval = -EPERM;
354	else if (!types)
355	retval = -ENOMEM;
356	else {
357	char p = types, fs;
358
359	while ((fs = strsep(&p, ":")) != NULL && retval
360	&& retval != -ENXIO
361	&& retval != -ENOMEDIUM
362	&& retval != -ENOENT
363	&& retval != -EBUSY)
364	retval = subfs_real_mount2(sb, fs);
365	}
366
367	if (types)
368	kfree(types);
369
370	if (!retval)
371	mark_media_supermounted(sb);
372
373	LEAVE(sb, "rc=%d", retval);
374
375	return retval;
376	}
377
378	static int
379	__subfs_check_disk_change(struct super_block *sb)
380	{
381	struct super_block *subsb = subfs_sb(sb);
382	int rc;
383	struct block_device *dev = subsb->s_bdev;
384
385	ENTER(sb);
386
387	rc = atomic_read(&subsb->s_media_changed);
388	if (!rc) {
389	lock_kernel();
390	rc = check_disk_change(dev);
391	unlock_kernel();
392	}
393
394	if (rc)
395	subfs_umount(sb, SUBFS_UMNT_MEDIA);
396
397	LEAVE(sb, "rc=%d", rc);
398
399	return rc;
400	}
401
402	/*
403	* this must really be called subfs_active ...
404	*/
405	int
406	subfs_check_disk_change(struct super_block *sb)
407	{
408	int rc;
409
410	ENTER(sb);
411
412	subfs_lock(sb);
413	if (subfs_is_mounted(sb))
414	rc = __subfs_check_disk_change(sb);
415	else
416	rc = 1;
417	subfs_unlock(sb);
418
419
420	LEAVE(sb, "rc=%d", rc);
421
422	return rc;
423	}
424
425	static int
426	check_and_remount_subfs(struct super_block *sb)
427	{
428	int rc;
429
430	ENTER(sb);
431
432	if (subfs_is_mounted(sb) && !__subfs_check_disk_change(sb)) {
433	rc = 0;
434	goto out;
435	}
436
437	rc = subfs_mount(sb);
438
439	out:
440	LEAVE(sb, "rc=%d", rc);
441
442	return rc;
443	}
444
445	static inline void
446	subfs_tray_lock(struct super_block *sb)
447	{
448	struct supermount_sb_info *sbi = supermount_sbi(sb);
449
450	ENTER(sb);
451
452	SUPERMOUNT_BUG_LOCKED_ON(sb, sbi->lockcount < 0);
453
454	if (!sbi->lockcount++)
455	supermount_lock_door(sb);
456
457	LEAVE(sb);
458	}
459
460	static inline void
461	subfs_tray_unlock(struct super_block *sb)
462	{
463	struct supermount_sb_info *sbi = supermount_sbi(sb);
464
465	ENTER(sb);
466
467	SUPERMOUNT_BUG_LOCKED_ON(sb, sbi->lockcount <= 0);
468
469	if (!--sbi->lockcount)
470	supermount_unlock_door(sb);
471
472	LEAVE(sb);
473	}
474
475	static void
476	subfs_get_read_access(struct super_block *sb)
477	{
478	struct supermount_sb_info *sbi = supermount_sbi(sb);
479
480	ENTER(sb);
481
482	SUPERMOUNT_BUG_LOCKED_ON(sb, sbi->readcount < 0);
483
484	if (!sbi->readcount++ && sbi->tray_lock == TRAY_LOCK_ALWAYS)
485	subfs_tray_lock(sb);
486
487	LEAVE(sb);
488	}
489
490	static int
491	subfs_get_write_access(struct super_block *sb)
492	{
493	struct supermount_sb_info *sbi = supermount_sbi(sb);
494	int rc;
495
496	ENTER(sb);
497
498	SUPERMOUNT_BUG_LOCKED_ON(sb, sbi->writecount < 0);
499
500	rc = 0;
501	if (!sbi->writecount) {
502	if (sb->s_flags & MS_RDONLY)
503	rc = -EROFS;
504	else
505	rc = subfs_remount_rw(sb);
506	}
507
508	if (!rc && !sbi->writecount++ && sbi->tray_lock != TRAY_LOCK_NEVER)
509	subfs_tray_lock(sb);
510
511	LEAVE(sb, "rc=%d", rc);
512
513	return rc;
514	}
515
516	static void
517	subfs_put_read_access(struct super_block *sb)
518	{
519	struct supermount_sb_info *sbi = supermount_sbi(sb);
520
521	ENTER(sb);
522
523	SUPERMOUNT_BUG_LOCKED_ON(sb, sbi->readcount <= 0);
524
525	if (!--sbi->readcount && sbi->tray_lock == TRAY_LOCK_ALWAYS)
526	subfs_tray_unlock(sb);
527
528	LEAVE(sb);
529	}
530
531	static void
532	subfs_put_write_access(struct super_block *sb)
533	{
534	struct supermount_sb_info *sbi = supermount_sbi(sb);
535
536	ENTER(sb);
537
538	SUPERMOUNT_BUG_LOCKED_ON(sb, sbi->writecount <= 0);
539
540	if (!--sbi->writecount) {
541	/*
542	* no need to fsync, it is done automatically on remount
543	*/
544	int rc = subfs_remount_ro(sb);
545	if (rc)
546	supermount_error(sb, "failed to remount ro, error = %d", rc);
547	if (sbi->tray_lock != TRAY_LOCK_NEVER)
548	subfs_tray_unlock(sb);
549	}
550
551	LEAVE(sb);
552	}
553
554	int
555	subfs_get_access(struct inode *inode, int rw)
556	{
557	struct super_block *sb = inode->i_sb;
558	int rc = 0;
559
560	ENTER(sb);
561
562	subfs_lock(sb);
563	if (is_inode_obsolete(inode))
564	rc = -ESTALE;
565	else {
566	struct supermount_inode_info *sii = supermount_i(inode);
567
568	if (rw) {
569	SUPERMOUNT_BUG_LOCKED_ON(sb, sii->writecount < 0);
570	rc = subfs_get_write_access(sb);
571	if (!rc)
572	sii->writecount++;
573	} else {
574	SUPERMOUNT_BUG_LOCKED_ON(sb, sii->readcount < 0);
575	subfs_get_read_access(sb);
576	sii->readcount++;
577	}
578	}
579	subfs_unlock(sb);
580
581	LEAVE(sb, "rc=%d", rc);
582
583	return rc;
584	}
585
586	void
587	subfs_put_access(struct inode *inode, int rw)
588	{
589	struct super_block *sb = inode->i_sb;
590
591	ENTER(sb);
592
593	subfs_lock(sb);
594	if (!is_inode_obsolete(inode)) {
595	struct supermount_inode_info *sii = supermount_i(inode);
596
597	if (rw) {
598	SUPERMOUNT_BUG_LOCKED_ON(sb, sii->writecount <= 0);
599	sii->writecount--;
600	subfs_put_write_access(sb);
601	} else {
602	SUPERMOUNT_BUG_LOCKED_ON(sb, sii->readcount <= 0);
603	sii->readcount--;
604	subfs_put_read_access(sb);
605	}
606
607	}
608	subfs_unlock(sb);
609
610	LEAVE(sb);
611	}
612
613	struct vfsmount *
614	subfs_go_online(struct super_block *sb)
615	{
616	int rc;
617	struct vfsmount *mnt;
618
619	ENTER(sb);
620
621	subfs_lock(sb);
622
623	rc = check_and_remount_subfs(sb);
624	mnt = ERR_PTR(rc);
625	if (!rc)
626	mnt = mntget(subfs_mnt(sb));
627	subfs_unlock(sb);
628
629	LEAVE(sb, "mnt=%p", mnt);
630
631	return mnt;
632	}
633
634	void
635	subfs_go_offline(struct super_block sb, struct vfsmount mnt)
636	{
637	ENTER(sb);
638
639	SUPERMOUNT_BUG_ON(!mnt);
640	mntput(mnt);
641
642	LEAVE(sb);
643
644	}
645
646	struct vfsmount *
647	subfs_prevent_umount(struct super_block *sb)
648	{
649	struct vfsmount *mnt;
650
651	ENTER(sb);
652
653	subfs_lock(sb);
654	mnt = subfs_mnt(sb);
655	if (mnt)
656	mnt = mntget(mnt);
657	subfs_unlock(sb);
658
659	LEAVE(sb, "mnt=%p", mnt);
660
661	return mnt;
662	}
663
664	void
665	subfs_allow_umount(struct super_block sb, struct vfsmount mnt)
666	{
667	ENTER(sb);
668
669	SUPERMOUNT_BUG_ON(!mnt);
670	mntput(mnt);
671
672	LEAVE(sb);
673
674	}
675
676	struct vfsmount *
677	subfs_get_mnt(struct super_block *sb)
678	{
679	struct vfsmount *mnt = NULL;
680
681	ENTER(sb);
682
683	subfs_lock(sb);
684	if (subfs_is_mounted(sb))
685	mnt = mntget(subfs_mnt(sb));
686	subfs_unlock(sb);
687
688	LEAVE(sb, "mnt=%p", mnt);
689
690	return mnt;
691	}
692
693	struct super_block *
694	subfs_get_sb(struct super_block *sb)
695	{
696	struct super_block *subsb = NULL;
697
698	ENTER(sb);
699
700	subfs_lock(sb);
701	if (subfs_is_mounted(sb))
702	subsb = subfs_sb(sb);
703	subfs_unlock(sb);
704
705	LEAVE(sb, "subsb=%p", subsb);
706
707	return subsb;
708	}
709
710	/*
711	* contrary to its name this function deals with _supermount_ inode
712	*/
713	void
714	subfs_clear_inode(struct inode *inode)
715	{
716	struct super_block *sb = inode->i_sb;
717	struct supermount_inode_info *sii = supermount_i(inode);
718
719	ENTER(sb, "inode=%p", inode);
720
721	subfs_lock(sb);
722
723	/*
724	* this is safe. If subfs has been unmounted, counters has been
725	* set to 0 already
726	*/
727	while(sii->writecount > 0) {
728	sii->writecount--;
729	subfs_put_write_access(sb);
730	}
731
732	while(sii->readcount > 0) {
733	sii->readcount--;
734	subfs_put_read_access(sb);
735	}
736
737	list_del(&sii->list);
738
739	subfs_unlock(sb);
740
741	LEAVE(sb, "inode=%p", inode);
742	}

Line 0 Link Here

(-)linux-2.6.8.1_supermount/fs/supermount/super.c (+646 lines)
		1	/*
		2	* linux/fs/supermount/super.c
		3	*
		4	* Original version:
		5	* Copyright (C) 1995, 1997
		6	* Stephen Tweedie (sct@@dcs.ed.ac.uk)
		7	*
		8	* from
		9	*
		10	* linux/fs/minix/inode.c
		11	* Copyright (C) 1991, 1992 Linus Torvalds
		12	*
		13	* and
		14	*
		15	* linux/fs/ext2/super.c
		16	* Copyright (C) 1992, 1993, 1994, 1995 Remy Card
		17	*
		18	* Rewriten for kernel 2.2, 2.4. (C) 1999, 2000 Alexis Mikhailov
		19	* (alexis@@abc.cap.ru)
		20	* Rewritten for kernel 2.4.21 (C) 2003 Andrey Borzenkov
		21	* (arvidjaar@@mail.ru)
		22	* Rewritten for kernel 2.5.70 (C) 2003 Andrey Borzenkov
		23	* (arvidjaar@@mail.ru)
		24	*
		25	* $Id: 4715_supermount-2.0.4-2.6.7.patch,v 1.1 2004/06/22 22:15:04 gregkh Exp $
		26	*/
		27
		28	#define S_DBG_TRACE_CURRENT S_DBG_TRACE_SUPER
		29
		30	#include <linux/statfs.h>
		31	#include <linux/parser.h>
		32	#include "supermount.h"
		33
		34	/*
		35	* vfat and msdos do not have any valididty checks for superblock and must
		36	* be the last entries!
		37	*/
		38
		39	static char *default_fs_types = "udf:iso9660:ext2:vfat:msdos";
		40
		41	static struct super_operations supermount_sops;
		42
		43	/* ========================= helpers ================================= */
		44
		45	static inline void
		46	supermount_update_inode(struct inode superi, struct inode subi)
		47	{
		48	struct super_block *sb = superi->i_sb;
		49
		50	ENTER(sb, "superi=%p subi=%p", superi, subi);
		51
		52	superi->i_ino = subi->i_ino;
		53	superi->i_mode = subi->i_mode;
		54	superi->i_uid = subi->i_uid;
		55	superi->i_gid = subi->i_gid;
		56	superi->i_nlink = subi->i_nlink;
		57	superi->i_size = subi->i_size;
		58	superi->i_atime = subi->i_atime;
		59	superi->i_ctime = subi->i_ctime;
		60	superi->i_mtime = subi->i_mtime;
		61	superi->i_blksize = subi->i_blksize;
		62	superi->i_blocks = subi->i_blocks;
		63	superi->i_rdev = subi->i_rdev;
		64	superi->i_version++;
65	set_inode_flags(superi, subi);
66
67	if (S_ISDIR(superi->i_mode)) {
68	superi->i_op = &supermount_dir_iops;
69	superi->i_fop = &supermount_dir_operations;
70	} else if (S_ISLNK(superi->i_mode)) {
71	superi->i_op = &supermount_symlink_iops;
72	superi->i_mapping = subi->i_mapping;
73	} else {
74	superi->i_op = &supermount_file_iops;
75	superi->i_fop = &supermount_file_operations;
76	superi->i_mapping = subi->i_mapping;
77	}
78
79	LEAVE(sb, "superi=%p subi=%p", superi, subi);
80	}
81
82	/* this is also called from subfs_mount to reinstantiate root inode */
83	void
84	attach_subfs_inode(struct inode inode, struct inode subi)
85	{
86	struct super_block *sb = inode->i_sb;
87	struct supermount_sb_info *sbi = supermount_sbi(sb);
88	struct supermount_inode_info *sii;
89
90	ENTER(sb, "inode=%p subi=%p", inode, subi);
91
92	sii = supermount_i(inode);
93	if (!sii->inode) {
94	/*
95	* this can be run concurrently. It is executed under
96	* sbi->sem so only one task would actually instantate
97	* inode. See namei.c:prepare_inode
98	* Another user is subfs.c:subfs_real_mount2
99	*/
100	sii->inode = igrab(subi);
101	supermount_update_inode(inode, subi);
102	list_add(&sii->list, &sbi->s_inodes);
103	} else
104	SUPERMOUNT_BUG_LOCKED_ON(sb, sii->inode != subi);
105
106	LEAVE(sb, "inode=%p subi=%p", inode, subi);
107	}
108
109	char *
110	strdup(const char *val)
111	{
112	char *tmp;
113	tmp = kmalloc(1 + strlen(val), GFP_KERNEL);
114	if (tmp)
115	strcpy(tmp, val);
116	return tmp;
117	}
118
119	static struct supermount_sb_info *
120	create_sbi(struct super_block *sb)
121	{
122	struct supermount_sb_info sbi = kmalloc(sizeof (sbi), GFP_KERNEL);
123
124	if (!sbi)
125	return NULL;
126
127	memset(sbi, 0, sizeof (*sbi));
128
129	sbi->s_undermount = NULL;
130	sbi->s_type = sbi->devname = sbi->s_data = NULL;
131	INIT_LIST_HEAD(&sbi->s_inodes);
132	INIT_LIST_HEAD(&sbi->s_files);
133	INIT_LIST_HEAD(&sbi->s_dentries);
134	init_MUTEX(&sbi->sem);
135	sbi->host = sb;
136	sbi->tray_lock = TRAY_LOCK_ONWRITE;
137	sbi->rw = !(sb->s_flags & MS_RDONLY);
138
139	return sbi;
140	}
141
142	static void
143	free_sbi(struct supermount_sb_info *sbi)
144	{
145	if (sbi->s_type && sbi->s_type != default_fs_types)
146	kfree(sbi->s_type);
147	if (sbi->devname)
148	kfree(sbi->devname);
149	if (sbi->s_data)
150	kfree(sbi->s_data);
151	kfree(sbi);
152	}
153
154	enum {
155	Opt_fs, Opt_fs_auto, Opt_dev, Opt_debug, Opt_debug_old, Opt_subfsopts,
156	Opt_tray_lock_always, Opt_tray_lock_never, Opt_tray_lock_onwrite,
157	Opt_ignore, Opt_err
158	};
159
160	static match_table_t tokens = {
161	{Opt_fs_auto, "fs=auto"},
162	{Opt_fs, "fs=%s"},
163	{Opt_dev, "dev=%s"},
164	{Opt_debug, "debug=%u"},
165	{Opt_debug_old, "debug"},
166	{Opt_subfsopts, "--"},
167	{Opt_tray_lock_always, "tray_lock=always"},
168	{Opt_tray_lock_never, "tray_lock=never"},
169	{Opt_tray_lock_onwrite, "tray_lock=onwrite"},
170	{Opt_ignore, "no_tray_lock"},
171	{Opt_ignore, "fail_statfs_until_mount"},
172	{Opt_err, NULL}
173	};
174
175	static int
176	parse_options(char options, struct super_block sb)
177	{
178	struct supermount_sb_info *sbi = supermount_sbi(sb);
179	int rc;
180	char *p;
181
182	if (!options)
183	return 0;
184
185	while ((p = strsep(&options, ",")) != NULL) {
186	int token;
187	substring_t args[MAX_OPT_ARGS];
188	int n;
189
190	/* empty option means start of subfs options */
191	if (!*p)
192	goto copy_subfs_options;
193
194	token = match_token(p, tokens, args);
195	switch(token) {
196	case Opt_fs:
197	sbi->s_type = match_strdup(&args[0]);
198	if (!sbi->s_type)
199	return -ENOMEM;
200	break;
201	case Opt_fs_auto:
202	sbi->s_type = default_fs_types;
203	break;
204	case Opt_dev:
205	sbi->devname = match_strdup(&args[0]);
206	if (!sbi->devname)
207	return -ENOMEM;
208	break;
209	case Opt_debug:
210	if ((rc = match_int(&args[0], &n)))
211	return rc;
212	sbi->s_debug = n;
213	break;
214	case Opt_debug_old:
215	sbi->s_debug = S_DBG_DEBUG;
216	break;
217	case Opt_tray_lock_always:
218	sbi->tray_lock = TRAY_LOCK_ALWAYS;
219	break;
220	case Opt_tray_lock_onwrite:
221	sbi->tray_lock = TRAY_LOCK_ONWRITE;
222	break;
223	case Opt_tray_lock_never:
224	sbi->tray_lock = TRAY_LOCK_NEVER;
225	break;
226	case Opt_subfsopts:
227	copy_subfs_options:
228	/* mount may have removed options after -- */
229	if (options && *options) {
230	sbi->s_data = strdup(options);
231	if (!sbi->s_data)
232	return -ENOMEM;
233	}
234	return 0;
235	break;
236	case Opt_ignore:
237	break;
238	default:
239	supermount_error(sb, "Unrecognized mount option \"%s\"",
240	p);
241	return -EINVAL;
242	break;
243	}
244	}
245
246	return 0;
247	}
248
249	void
250	supermount_init_root_inode(struct inode *inode)
251	{
252	inode->i_mode = 0777 \| S_IFDIR;
253	inode->i_uid = current->fsuid;
254	inode->i_gid = current->fsgid;
255	inode->i_blksize = inode->i_sb->s_blocksize;
256	inode->i_rdev = MKDEV(UNNAMED_MAJOR, 0);
257	inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
258	inode->i_size = 0;
259	inode->i_blocks = 0;
260	inode->i_ino = 0;
261	inode->i_nlink = 0;
262
263	set_inode_flags(inode, 0);
264
265	inode->i_op = &supermount_dir_iops;
266	inode->i_fop = &supermount_dir_operations;
267	}
268
269	static struct inode *
270	supermount_root_inode(struct super_block *sb)
271	{
272	struct inode *inode = new_inode(sb);
273
274	ENTER(sb);
275
276	if (inode) {
277	inode->i_version = 0;
278	supermount_init_root_inode(inode);
279	}
280
281	LEAVE(sb, "inode=%p", inode);
282
283	return inode;
284	}
285
286	/* ========================== used in fstype declaration ================*/
287
288	/* read_super: the main mount() entry point into the VFS layer. */
289	static int
290	supermount_read_super(struct super_block sb, void data, int silent)
291	{
292	struct inode *root_inode;
293	struct dentry *root;
294	struct supermount_sb_info *sbi = create_sbi(sb);
295	int rc = -ENOMEM;
296
297	if (!sbi)
298	goto fail_no_memory;
299
300	sb->s_fs_info = sbi;
301
302	rc = parse_options((char *) data, sb);
303	if (rc)
304	goto fail_parsing;
305
306	rc = -EINVAL;
307	if (!sbi->devname) {
308	supermount_error(sb, "no dev=<device> option");
309	goto fail_parsing;
310	}
311
312	if (!sbi->s_type) {
313	sbi->s_type = default_fs_types;
314	supermount_warning(sb, "no fs=<filesystem> option, assuming fs=auto");
315	}
316
317	rc = -ENOMEM;
318
319	sb->s_blocksize = 1024;
320	sb->s_blocksize_bits = 10;
321	sb->s_magic = SUPERMOUNT_SUPER_MAGIC;
322	sb->s_op = &supermount_sops;
323
324	root_inode = supermount_root_inode(sb);
325	if (!root_inode)
326	goto fail_allocating_root_inode;
327
328	root = d_alloc_root(root_inode);
329	if (!root)
330	goto fail_allocating_root_dentry;
331	if (init_dentry_info(root))
332	goto fail_init_root_info;
333
334	sb->s_root = root;
335
336	supermount_proc_insert(sbi);
337
338	return 0;
339
340	fail_init_root_info:
341	dput(root);
342	fail_allocating_root_dentry:
343	iput(root_inode);
344	fail_parsing:
345	fail_allocating_root_inode:
346	free_sbi(sbi);
347
348	fail_no_memory:
349	return rc;
350	}
351
352	struct super_block supermount_get_sb(struct file_system_type fs_type, int flags, const char dev_name, void data)
353	{
354	return get_sb_nodev(fs_type, flags, data, supermount_read_super);
355	}
356
357	/* ======================= super_operations methods ==================== */
358
359	static struct inode *
360	supermount_alloc_inode(struct super_block *sb)
361	{
362	struct supermount_inode_info sii = kmalloc(sizeof(sii), GFP_KERNEL);
363	struct inode *inode = 0;
364
365	ENTER(sb);
366
367	if (sii) {
368	INIT_LIST_HEAD(&sii->list);
369	sii->inode = 0;
370	sii->readcount = 0;
371	sii->writecount = 0;
372	inode = &sii->vfs_inode;
373	inode_init_once(inode);
374	}
375
376	LEAVE(sb, "inode=%p", inode);
377
378	return inode;
379	}
380
381	static void
382	supermount_destroy_inode(struct inode *inode)
383	{
384	struct super_block *sb = inode->i_sb;
385	struct supermount_inode_info *sii = supermount_i(inode);
386
387	ENTER(sb, "inode=%p", inode);
388
389	kfree(sii);
390
391	ENTER(sb, "inode=%p", inode);
392	}
393
394	/*
395	* FIXME
396	* I am still unsure if (or why) this functions is needed; it is likely
397	* to go away. So far the only _real_ user seems to be knfsd.
398	*/
399	static void
400	supermount_write_inode(struct inode *inode, int sync)
401	{
402	struct super_block *sb = inode->i_sb;
403	struct super_block *subsb;
404	struct inode *subi;
405	struct vfsmount *submnt;
406
407	ENTER(sb);
408
409	if (subfs_check_disk_change(sb))
410	goto out;
411
412	submnt = subfs_prevent_umount(sb);
413	if (!submnt)
414	goto out;
415
416	subi = get_subfs_inode(inode);
417	if (IS_ERR(subi))
418	goto allow_umount;
419
420	subsb = subfs_get_sb(sb);
421	if (!sb)
422	goto put_subi;
423
424	if (subsb->s_op && subsb->s_op->write_inode) {
425	if (subfs_get_access(inode, 1))
426	goto put_subi;
427
428	write_inode_now(subi, sync);
429
430	subfs_put_access(inode, 1);
431	}
432	put_subi:
433	iput(subi);
434	allow_umount:
435	subfs_allow_umount(sb, submnt);
436	out:
437	LEAVE(sb);
438
439	return;
440	}
441
442	/*
443	* FIXME
444	* subfs_umount has no business here
445	* it should be moved into umount_begin; in this case force umount will
446	* free subfs (and give false No medium as error ... oh, well)
447	*/
448	static void
449	supermount_put_super(struct super_block *sb)
450	{
451	struct supermount_sb_info *sbi = supermount_sbi(sb);
452
453	ENTER(sb);
454
455	subfs_lock(sb);
456	if (subfs_is_mounted(sb))
457	subfs_umount(sb, SUBFS_UMNT_NORMAL);
458	subfs_unlock(sb);
459
460	supermount_proc_remove(sbi);
461
462	LEAVE(sb);
463
464	sb->s_fs_info = 0;
465	free_sbi(sbi);
466	}
467
468	/*
469	* The following has to be done in two steps (unfortunately)
470	* First make sure iput(subi) is run just once - and then put
471	* read/write access and finally remove inode from list
472	*
473	* We can't do it in one shot because removing inode from list
474	* will remove also possibility to mark it stale. It has been
475	* introduced by me :( removing generation numbers. OTOH so far
476	* it is the only place that needs extra treatment because of it.
477	*/
478	static void
479	supermount_clear_inode(struct inode *inode)
480	{
481	struct supermount_inode_info *sii = supermount_i(inode);
482	struct super_block *sb = inode->i_sb;
483	struct inode *subi;
484	struct vfsmount *mnt;
485
486	ENTER(sb, "inode=%p", inode);
487
488	mnt = subfs_prevent_umount(sb);
489	if (!mnt)
490	goto out;
491
492	subfs_lock(sb);
493	subi = sii->inode;
494	sii->inode = 0;
495	subfs_unlock(sb);
496
497
498	if (subi) {
499	/*
500	* we used to check for subi->i_count != 1 here.
501	* This does not actually work - it is quite possible
502	* that inode has been looked up while we were in this
503	* function. So just ignore it (the worst thing that
504	* may happen is that subfs cannot be remounted)
505	*/
506
507	iput(subi);
508
509	}
510	subfs_allow_umount(sb, mnt);
511
512	/*
513	* This does not has much to do with subfs but I did not want
514	* to export __ functions
515	*/
516	subfs_clear_inode(inode);
517	out:
518	LEAVE(sb, "inode=%p", inode);
519	}
520	/*
521	* FIXME why it is needed?
522	*/
523
524	static void
525	supermount_write_super(struct super_block *sb)
526	{
527	struct vfsmount *mnt;
528
529	ENTER(sb);
530
531	if (subfs_check_disk_change(sb))
532	goto out;
533
534	if (subfs_is_rw(sb)) {
535	struct super_block *subsb;
536
537	mnt = subfs_prevent_umount(sb);
538	if (!mnt)
539	goto out;
540
541	subsb = subfs_get_sb(sb);
542	if (subsb && subsb->s_op && subsb->s_op->write_super)
543	subsb->s_op->write_super(subsb);
544
545	subfs_allow_umount(sb, mnt);
546	}
547
548	out:
549	LEAVE(sb);
550
551	return;
552	}
553
554	static int
555	supermount_statfs(struct super_block sb, struct kstatfs buf)
556	{
557	int rc = 0;
558	struct super_block *subsb;
559	struct vfsmount *mnt;
560
561	ENTER(sb);
562
563	(void)subfs_check_disk_change(sb);
564
565	mnt = subfs_prevent_umount(sb);
566	if (!mnt)
567	goto out;
568
569	subsb = subfs_get_sb(sb);
570	if (subsb && subsb->s_op && subsb->s_op->statfs)
571	rc = subsb->s_op->statfs(subsb, buf);
572	if (!rc)
573	buf->f_type = SUPERMOUNT_SUPER_MAGIC;
574
575	subfs_allow_umount(sb, mnt);
576	out:
577	LEAVE(sb, "rc=%d", rc);
578
579	return rc;
580	}
581
582	static int
583	supermount_remount_fs(struct super_block sb, int flags, char *data)
584	{
585	return -ENOSYS;
586	}
587
588	/*
589	* based on fs/ntfs/inode.c:ntfs_show_options
590	*/
591	static int
592	supermount_show_options(struct seq_file sf, struct vfsmount mnt)
593	{
594	struct supermount_sb_info *sbi = supermount_sbi(mnt->mnt_sb);
595
596	seq_printf(sf, ",dev=%s", sbi->devname);
597	seq_puts(sf, ",fs=");
598	if (sbi->s_type == default_fs_types)
599	seq_puts(sf, "auto");
600	else
601	seq_puts(sf, sbi->s_type);
602	seq_puts(sf, ",tray_lock=");
603	if (sbi->tray_lock == TRAY_LOCK_ALWAYS)
604	seq_puts(sf, "always");
605	else if (sbi->tray_lock == TRAY_LOCK_NEVER)
606	seq_puts(sf, "never");
607	else if (sbi->tray_lock == TRAY_LOCK_ONWRITE)
608	seq_puts(sf, "onwrite");
609	else
610	SUPERMOUNT_BUG_ON(1);
611
612	if (sbi->s_debug)
613	seq_printf(sf, ",debug=0x%lx", sbi->s_debug);
614	if (sbi->s_data)
615	seq_printf(sf, ",--,%s", sbi->s_data);
616	return 0;
617	}
618
619	/*
620	* ->read_inode: not needed
621	* ->dirty_inode: probably not needed. It appears VFS layer never
622	* calls mark_inode_dirty itself; exception is
623	* UPDATE_ATIME and it is already handled specially
624	* FIXME
625	* It may be needed for knfsd and similar
626	* ->put_inode: not needed
627	* ->delete_inode: not needed
628	* ->write_super: FIXME not needed, we do not have any backing store
629	* ->sync_fs: not needed
630	* ->write_super_lockfs:not needed
631	* ->unlockfs: not needed
632	* ->umount_begin: TODO maybe to move subfs_umount aways from put_super
633	* ->fh_to_dentry: TODO may be
634	* ->dentry_to_fh: TODO may be
635	*/
636	static struct super_operations supermount_sops = {
637	.alloc_inode = supermount_alloc_inode,
638	.destroy_inode = supermount_destroy_inode,
639	.write_inode = supermount_write_inode,
640	.clear_inode = supermount_clear_inode,
641	.put_super = supermount_put_super,
642	.write_super = supermount_write_super,
643	.statfs = supermount_statfs,
644	.remount_fs = supermount_remount_fs,
645	.show_options = supermount_show_options,
646	};

Line 0 Link Here

(-)linux-2.6.8.1_supermount/fs/supermount/supermount.h (+497 lines)
		1	#ifndef _SUPERMOUNT_I_H
		2	#define _SUPERMOUNT_I_H
		3
		4	/*
		5	* $Id: 4715_supermount-2.0.4-2.6.7.patch,v 1.1 2004/06/22 22:15:04 gregkh Exp $
		6	*/
		7
		8	#include <linux/module.h>
		9	#include <linux/version.h>
		10
		11	#include <linux/slab.h>
		12	#include <linux/sched.h>
		13	#include <linux/errno.h>
		14	#include <linux/fs.h>
		15	#include <linux/list.h>
		16	#include <linux/file.h>
		17	#include <linux/mm.h>
		18	#include <linux/poll.h>
		19	#include <linux/smp_lock.h>
		20	#include <linux/proc_fs.h>
		21	#include <linux/seq_file.h>
		22	#include <linux/dnotify.h>
		23	#include <linux/mount.h>
		24	#include <linux/moduleparam.h>
		25	#include <linux/genhd.h>
		26	#include <linux/namei.h>
		27	#include <linux/supermount_media.h>
		28
		29	#ifdef CONFIG_SUPERMOUNT_DEBUG
		30	#define SUPERMOUNT_DEBUG
		31	#endif
		32	/*
		33	* The supermount superblock magic number
		34	*/
		35
		36	#define SUPERMOUNT_SUPER_MAGIC 0x9fa1
		37	#define SUPERMOUNT_VERSION "2.0.4"
		38
		39	#define S_DBG_DEBUG 0x001
		40	#define S_DBG_TRACE_DENTRY 0x002
		41	#define S_DBG_TRACE_FILE 0x004
		42	#define S_DBG_TRACE_FILEMAP 0x008
		43	#define S_DBG_TRACE_MEDIACTL 0x010
		44	#define S_DBG_TRACE_NAMEI 0x020
		45	#define S_DBG_TRACE_SUBFS 0x040
		46	#define S_DBG_TRACE_SUPER 0x080
		47
		48	/*
		49	* The subfs umount reason
		50	*/
		51	#define SUBFS_UMNT_NORMAL 0 /* normal umount */
		52	#define SUBFS_UMNT_MEDIA 1 /* media change detected */
		53	#define SUBFS_UMNT_USER 2 /* user request */
		54
		55	/*
		56	* When to lock media
		57	*/
		58	#define TRAY_LOCK_NEVER 0
		59	#define TRAY_LOCK_ONWRITE 1
		60	#define TRAY_LOCK_ALWAYS 2
		61
		62	extern struct file_system_type supermount_fs_type;
		63
		64	#ifdef SUPERMOUNT_DEBUG
65
66	#define SUPERMOUNT_BUG_ON(x) BUG_ON(x)
67	#define SUPERMOUNT_BUG_LOCKED_ON(sb, x) \
68	do { \
69	if (x) { \
70	subfs_unlock(sb); \
71	BUG(); \
72	} \
73	} while (0)
74
75	#define supermount_debug(sb, args...) \
76	do { \
77	struct supermount_sb_info *sbi = supermount_sbi(sb); \
78	char *dev = sbi->devname ? sbi->devname : "unknown"; \
79	\
80	if (supermount_dbg(sb, S_DBG_DEBUG)) { \
81	printk("%sSUPERMOUNT DEBUG [dev=%s] <%s:%d> ", \
82	KERN_DEBUG, dev, __FUNCTION__, __LINE__); \
83	printk(args); \
84	printk("\n"); \
85	} \
86	} while(0)
87
88	#define ENTER(sb, args...) \
89	do { \
90	struct supermount_sb_info *sbi = supermount_sbi(sb); \
91	char *dev = sbi->devname ? sbi->devname : "unknown"; \
92	\
93	if (supermount_dbg(sb, S_DBG_TRACE_CURRENT)) { \
94	printk("%sSUPERMOUNT TRACE [dev=%s] PID=%lu ENTER %s", \
95	KERN_DEBUG, dev, (unsigned long)current->pid, \
96	__FUNCTION__); \
97	printk(" " args); \
98	printk("\n"); \
99	} \
100	} while (0)
101
102	#define LEAVE(sb, args...) \
103	do { \
104	struct supermount_sb_info *sbi = supermount_sbi(sb); \
105	char *dev = sbi->devname ? sbi->devname : "unknown"; \
106	\
107	if (supermount_dbg(sb, S_DBG_TRACE_CURRENT)) { \
108	printk("%sSUPERMOUNT TRACE [dev=%s] PID=%lu LEAVE %s", \
109	KERN_DEBUG, dev, (unsigned long)current->pid, \
110	__FUNCTION__); \
111	printk(" " args); \
112	printk("\n"); \
113	} \
114	} while (0)
115
116	#else /* SUPERMOUNT_DEBUG */
117	#define supermount_debug(f, a...) /**/
118	#define SUPERMOUNT_BUG_ON(x) do { } while (0)
119	#define SUPERMOUNT_BUG_LOCKED_ON(sb, x) do { } while (0)
120
121	#define ENTER(sb, args...) do { (void)sb; } while (0)
122	#define LEAVE(sb, args...) do { (void)sb; } while (0)
123	#endif /* SUPERMOUNT_DEBUG */
124
125	#define supermount_warning(sb, ...) \
126	do { \
127	struct supermount_sb_info *sbi = supermount_sbi(sb); \
128	char *dev = sbi->devname ? sbi->devname : "unknown"; \
129	\
130	printk("%sSUPERMOUNT WARNING [dev=%s] ", KERN_WARNING, dev); \
131	printk(__VA_ARGS__); \
132	printk("\n"); \
133	} while(0)
134
135	#define supermount_error(sb, ...) \
136	do { \
137	struct supermount_sb_info *sbi = supermount_sbi(sb); \
138	char *dev = sbi->devname ? sbi->devname : "unknown"; \
139	\
140	printk("%sSUPERMOUNT ERROR [dev=%s] ", KERN_ERR, dev); \
141	printk(__VA_ARGS__); \
142	printk("\n"); \
143	} while(0)
144
145	/*
146	* The following is drived from fs/inode.c:update_atime()
147	*/
148	#define NEED_WRITE_ATIME(inode) \
149	(!(IS_NOATIME(inode) \|\| \
150	(IS_NODIRATIME(inode) && S_ISDIR(inode->i_mode)) \|\| \
151	IS_RDONLY(inode)))
152
153
154	/*
155	* supermount super-block data in memory
156	*/
157	struct supermount_sb_info;
158	struct supermount_sb_info {
159	/* == options == */
160	unsigned long s_debug; /* debug flags S_DBG_* */
161	char s_type; / Type of fs to be sub-mounted */
162	char devname; / Where to mount the subfs from */
163	char s_data; / Data to pass when mounting subfs */
164	/* == end of options == */
165	struct vfsmount *s_undermount;
166	/* Mount point for subfs */
167	int readcount; /* Refcount of read access
168	on the filesystem */
169	int writecount; /* Refcount of write access
170	on the filesystem */
171	int lockcount; /* Refcount of requests to lock tray */
172	struct list_head s_inodes;
173	/* list of active inodes */
174	struct list_head s_files;
175	/* list of active files */
176	struct list_head s_dentries;
177	/* list of active dentries */
178	struct semaphore sem;
179	struct super_block *host;
180	/* needed for procfs support */
181	struct supermount_sb_info *next;
182	/* list of all supermount fs */
183	unsigned int tray_lock:2;
184	unsigned int disabled:1;
185	unsigned int rw:1;
186	};
187
188	static inline struct supermount_sb_info *
189	supermount_sbi(struct super_block *sb)
190	{
191	struct supermount_sb_info *sbi;
192	BUG_ON(!sb);
193	BUG_ON(sb->s_type != &supermount_fs_type);
194
195	sbi = (struct supermount_sb_info *) (sb->s_fs_info);
196	BUG_ON(!sbi);
197
198	return sbi;
199	}
200
201	static inline struct vfsmount *
202	subfs_mnt(struct super_block *sb)
203	{
204	return supermount_sbi(sb)->s_undermount;
205	}
206
207	static inline struct super_block *
208	subfs_sb(struct super_block *sb)
209	{
210	struct vfsmount *mnt = subfs_mnt(sb);
211
212	if (mnt) return mnt->mnt_sb;
213
214	return 0;
215	}
216
217	/* this is expected to run under sb->sem */
218	static inline int
219	subfs_is_mounted(struct super_block *sb)
220	{
221	struct supermount_sb_info *sbi = supermount_sbi(sb);
222
223	return sbi->s_undermount != 0;
224	}
225
226	/* this is expected to run under sb->sem */
227	static inline int
228	subfs_is_busy(struct super_block *sb)
229	{
230	struct vfsmount *mnt = subfs_mnt(sb);
231
232	/*
233	* In "normal" case mnt_count is 2. But we currently do
234	* not insert subfs into task namespace so count is 1
235	* FIXME
236	* This also means we do not do_umount i.e. do not run
237	* either umount_begin or DQUOT_OFF for subfs.
238	*/
239	if (mnt) return atomic_read(&mnt->mnt_count) > 1;
240
241	return 0;
242	}
243
244	/* this is expected to run under sb->sem */
245	static inline int
246	subfs_is_rw(struct super_block *sb)
247	{
248	struct super_block *subsb;
249
250	if (!subfs_is_mounted(sb))
251	return 0;
252
253	subsb = subfs_sb(sb);
254	return !(subsb->s_flags & MS_RDONLY);
255	}
256
257	static inline void
258	subfs_lock(struct super_block *sb)
259	{
260	struct supermount_sb_info *sbi = supermount_sbi(sb);
261
262	down(&sbi->sem);
263	}
264
265	static inline void
266	subfs_unlock(struct super_block *sb)
267	{
268	struct supermount_sb_info *sbi = supermount_sbi(sb);
269
270	up(&sbi->sem);
271	}
272
273	/*
274	* query debug flags set
275	*/
276	static inline int supermount_dbg(struct super_block *sb, unsigned long flags)
277	{
278	struct supermount_sb_info *sbi = supermount_sbi(sb);
279
280	return sbi->s_debug & flags;
281	}
282
283	/*
284	* supermount inode info
285	*/
286
287	struct supermount_inode_info {
288	struct list_head list;
289	struct inode inode; / subfs inode */
290	int readcount;
291	int writecount;
292	struct inode vfs_inode; /* superfs inode */
293	};
294
295	static inline int
296	is_inode_supermounted(struct inode *inode)
297	{
298	return inode && inode->i_sb && inode->i_sb->s_type == &supermount_fs_type;
299	}
300
301	static inline struct supermount_inode_info *
302	supermount_i(struct inode *inode)
303	{
304	SUPERMOUNT_BUG_ON(!is_inode_supermounted(inode));
305
306	return list_entry(inode, struct supermount_inode_info, vfs_inode);
307	}
308
309	static inline int
310	is_inode_obsolete(struct inode *inode)
311	{
312	struct supermount_inode_info *sii = supermount_i(inode);
313
314	return sii->inode == 0;
315	}
316
317	static inline void
318	supermount_list_add_inode(struct inode *inode)
319	{
320	struct supermount_inode_info *sii = supermount_i(inode);
321
322	list_add(&(sii->list), &(supermount_sbi(inode->i_sb)->s_inodes));
323	}
324
325	/*
326	* FIXME
327	* Should we propagate all flags? *_QUOTA looks very possible candidate
328	* We can't just assign them because other flags may be set by VFS
329	*/
330	#define SMNT_INODE_FLAGS (S_IMMUTABLE\|S_NOATIME\|S_APPEND\|S_SYNC)
331	static inline void
332	set_inode_flags(struct inode inode, struct inode subi)
333	{
334	inode->i_flags &= ~SMNT_INODE_FLAGS;
335	if (subi)
336	inode->i_flags \|= (subi->i_flags & SMNT_INODE_FLAGS);
337	}
338
339	/*
340	* supermount dentry info
341	*/
342
343	struct supermount_dentry_info {
344	struct list_head list;
345	struct dentry *dentry;
346	struct dentry *host;
347	};
348
349	static inline int
350	is_dentry_supermounted(struct dentry *dentry)
351	{
352	return (dentry && dentry->d_sb && dentry->d_sb->s_type == &supermount_fs_type);
353	}
354
355	static inline struct supermount_dentry_info *
356	supermount_d(struct dentry *dentry)
357	{
358	SUPERMOUNT_BUG_ON(!is_dentry_supermounted(dentry));
359	SUPERMOUNT_BUG_ON(!dentry->d_fsdata);
360
361	return (struct supermount_dentry_info *)dentry->d_fsdata;
362	}
363
364	static inline int
365	is_dentry_obsolete(struct dentry *dentry)
366	{
367	struct supermount_dentry_info *sdi = supermount_d(dentry);
368
369	return sdi->dentry == 0;
370	}
371
372	/*
373	* Supermount file info
374	*/
375
376	struct supermount_file_info {
377	struct list_head list;
378	struct file * host;
379	struct file *file;
380	pid_t owner;
381	struct vm_operations_struct *vm_ops;
382	unsigned int fake:1;
383	};
384
385	static inline int
386	is_file_supermounted(struct file *file)
387	{
388	return file && file->f_dentry && is_dentry_supermounted(file->f_dentry);
389	}
390
391	static inline struct supermount_file_info *
392	supermount_f(struct file *file)
393	{
394	SUPERMOUNT_BUG_ON(!is_file_supermounted(file));
395	SUPERMOUNT_BUG_ON(!file->f_supermount);
396
397	return file->f_supermount;
398	}
399
400	static inline int
401	is_file_obsolete(struct file *file)
402	{
403	struct supermount_file_info *sfi = supermount_f(file);
404
405	return sfi->file == NULL;
406	}
407
408	static inline int
409	is_file_fake(struct file *file)
410	{
411	struct supermount_file_info *sfi = supermount_f(file);
412
413	return sfi->fake;
414	}
415
416	/* dentry.c */
417	extern rwlock_t d_compare_lock;
418	extern struct dentry_operations supermount_dops;
419	extern int init_dentry_info(struct dentry *);
420	extern void attach_subfs_dentry(struct dentry , struct dentry );
421	extern struct dentry get_subfs_dentry(struct dentry dentry);
422
423	/* file.c */
424	extern struct file_operations supermount_dir_operations;
425	extern struct file_operations supermount_file_operations;
426
427	/* filemap.c */
428	extern struct vm_operations_struct supermount_vm_ops;
429	extern int supermount_file_mmap(struct file , struct vm_area_struct );
430	extern struct file get_subfs_file(struct file);
431
432	/* mediactl.c */
433	extern void supermount_mediactl(struct super_block *, int, int);
434	static inline void
435	supermount_lock_door(struct super_block *sb)
436	{
437	supermount_mediactl(sb, MEDIA_LOCK, 1);
438	}
439	static inline void
440	supermount_unlock_door(struct super_block *sb)
441	{
442	supermount_mediactl(sb, MEDIA_UNLOCK, 1);
443	}
444
445	static inline void
446	mark_media_supermounted(struct super_block *sb)
447	{
448	supermount_mediactl(sb, SUPERMOUNT_INC_COUNT, 0);
449	supermount_mediactl(sb, MEDIA_UNLOCK, 0);
450	}
451
452	static inline void
453	unmark_media_supermounted(struct super_block *sb)
454	{
455	supermount_mediactl(sb, SUPERMOUNT_DEC_COUNT, 0);
456	}
457
458	/* namei.c */
459	extern struct inode_operations supermount_dir_iops;
460	extern struct inode_operations supermount_file_iops;
461	extern struct inode_operations supermount_symlink_iops;
462	extern struct inode create_supermount_inode(struct super_block );
463	extern struct inode get_subfs_inode(struct inode inode);
464
465	/* proc.c */
466	#ifdef CONFIG_PROC_FS
467	extern void supermount_proc_register(void);
468	extern void supermount_proc_unregister(void);
469	extern void supermount_proc_insert(struct supermount_sb_info *);
470	extern void supermount_proc_remove(struct supermount_sb_info *);
471	#else
472	#define supermount_proc_register() do { } while(0)
473	#define supermount_proc_unregister() do { } while(0)
474	#define supermount_proc_insert(sbi) do { } while(0)
475	#define supermount_proc_remove(sbi) do { } while(0)
476	#endif
477
478	/* subfs.c */
479	extern void subfs_umount(struct super_block *sb, int);
480	extern struct vfsmount subfs_go_online(struct super_block );
481	extern void subfs_go_offline(struct super_block , struct vfsmount );
482	extern int subfs_get_access(struct inode *, int);
483	extern void subfs_put_access(struct inode *, int);
484	extern int subfs_check_disk_change(struct super_block *);
485	extern struct vfsmount subfs_prevent_umount(struct super_block );
486	extern void subfs_allow_umount(struct super_block , struct vfsmount );
487	extern struct vfsmount subfs_get_mnt(struct super_block sb);
488	extern struct super_block subfs_get_sb(struct super_block sb);
489	extern void subfs_clear_inode(struct inode *);
490
491	/* super.c */
492	extern struct super_block supermount_get_sb(struct file_system_type , int, const char , void );
493	extern void attach_subfs_inode(struct inode , struct inode );
494	extern void supermount_init_root_inode(struct inode *);
495	extern char strdup(const char );
496
497	#endif /* _SUPERMOUNT_I_H */

Line 0 Link Here

(-)linux-2.6.8.1_supermount/include/linux/supermount_media.h (+47 lines)
	1	#if defined(CONFIG_SUPERMOUNT) \|\| defined(CONFIG_SUPERMOUNT_MODULE)
	2
	3	/*
	4	* These are the "op" operation codes for mediactl() media control
	5	* calls for device special files
	6	*/
	7	enum {
	8	MEDIA_LOCK = 1234, /* Lock the drive door */
	9	MEDIA_UNLOCK, /* Unlock the drive door */
	10	SUPERMOUNT_INC_COUNT,
	11	SUPERMOUNT_DEC_COUNT,
	12	};
	13
	14	static inline int
	15	supermount_usage_count(struct block_device *bdev, int count)
	16	{
	17	if (bdev) {
	18	count -= bdev->bd_disk->scount;
	19	if (count < 0)
	20	count = 0;
	21	}
	22	return count;
	23	}
	24
	25	static inline int
	26	dev_is_supermounted(struct block_device *bdev)
	27	{
	28	return bdev ? bdev->bd_disk->scount > 0 : 0;
	29	}
	30
	31	#else /* CONFIG_SUPERMOUNT */
	32
	33	static inline int
	34	supermount_usage_count(struct block_device *bdev, int count)
	35	{
	36	(void)bdev; // make compiler happy
	37	return count;
	38	}
	39
	40	static inline int
	41	dev_is_supermounted(struct block_device *bdev)
	42	{
	43	(void)bdev; // make compiler happy
	44	return 0;
	45	}
	46
	47	#endif /* CONFIG_SUPERMOUNT */