d61dc68454c72d62e8247b05
parent 02b7831019ea4e7994968c84b5826fa8b248ffc8
author Salman Qazi <sqazi@google.com> 1338522734 -0400
committer Theodore Ts'o <tytso@mit.edu> 1338522734 -0400

ext4: remove mb_groups before tearing down the buddy_cache

We can't have references held on pages in the s_buddy_cache while we are
trying to truncate its pages and put the inode.  All the pages must be
gone before we reach clear_inode.  This can only be gauranteed if we
can prevent new users from grabbing references to s_buddy_cache's pages.

The original bug can be reproduced and the bug fix can be verified by:

while true; do mount -t ext4 /dev/ram0 /export/hda3/ram0; \
	umount /export/hda3/ram0; done &

while true; do cat /proc/fs/ext4/ram0/mb_groups; done

Signed-off-by: Salman Qazi <sqazi@google.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: stable@kernel.org
z0+w’