Currently we every filesystem with Posix ACLs has it's own reimplemtation
of the generic permission checking code with additonal ACL support.  This
patch

- adds an optional callback to vfs_permission that filesystems can use
  for ACL support (and renames it to generic_permission because the old
  name was wrong - it wasn't like the other vfs_* functions at all)

- uses it in ext2, ext3 and jfs.  XFS will follow a little later as it's
  permission checking is burried under several layers of abstraction.

From: Dave Kleikamp <shaggy@austin.ibm.com>

  jfs doesn't currently set MS_POSIXACL (it doesn't require the acl mount
  option), so this test would fail here.  The patch below will set it.
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>