[PATCH] avoid -ENOMEM due reclaimable slab caches

This makes sure that reclaimable buffer headers and reclaimable inodes
are accounted properly during the overcommit checks.

Signed-off-by: Andrea Arcangeli <andrea@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>