commit 00a1a053ebe5febcfc2ec498bd894f035ad2aa06
author Theodore Ts'o <tytso@mit.edu> Sun Mar 30 10:20:01 2014 -0400
committer Linus Torvalds <torvalds@linux-foundation.org> Sun Mar 30 17:02:06 2014 -0700
tree 2a6206f1b3d195168cc1d835b459ea99c2db7811
parent 981e893ed537cbaa08f8089d480db4165e6d71c0

ext4: atomically set inode->i_flags in ext4_set_inode_flags()

Use cmpxchg() to atomically set i_flags instead of clearing out the
S_IMMUTABLE, S_APPEND, etc. flags and then setting them from the
EXT4_IMMUTABLE_FL, EXT4_APPEND_FL flags, since this opens up a race
where an immutable file has the immutable flag cleared for a brief
window of time.

Reported-by: John Sullivan <jsrhbz@kanargh.force9.co.uk>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>