BugLink: http://bugs.launchpad.net/bugs/1656259

Sync with zfs to enable zfs to respect RSIZE_LIMIT limits, using:

 - backport of zfs upstream commit 933ec999511f3d29de005bfa8966ae007b161c0f
   ("Retire .write/.read file operations")
 - backport of zfs upstream commit 4b908d32200b6e5c7b5115322b6c8d25e770daa0
   ("Linux 4.8 compat: posix_acl_valid()") to facilitate changes in
   posix_acl_valid.
Acked-by: Tim Gardner <tim.gardner@canonical.com>
Acked-by: Brad Figg <brad.figg@canonical.com>
Signed-off-by: Brad Figg <brad.figg@canonical.com>