Created attachment 436488 [details, diff] libzfs patch this issues surfaced with sys-cluster/ceph-10.2.1 and sys-fs/zfs-0.6.5.4-r2, but might affect any combination. zfs does not supply a zfs.pc file, hence the PKG_CONFIG check for CFLAGS fails to identify the need for -I/usr/include/libzfs ... and subsequently the build fails to find libzfs.h. attached patch does fix this
commit 7613d00e0c400ad02f4ff234c9896f704d6f2563 Author: Yixun Lan <dlan@gentoo.org> Date: Tue Jun 7 14:42:45 2016 +0800 sys-cluster/ceph: correct zfs PKG_CONFIG's variable Gentoo-Bug: 585050 Package-Manager: portage-2.3.0_rc1 :100644 100644 ab79bf3... 1ab15d9... M sys-cluster/ceph/ceph-10.2.1.ebuild :000000 100644 0000000... 34f8eb8... A sys-cluster/ceph/files/ceph-10.2.1-libzfs.patch