ext4: atomically set inode->i_flags in ext4_set_inode_flags()
authorTheodore Ts'o <tytso@mit.edu>
Mon, 24 Mar 2014 18:43:12 +0000 (14:43 -0400)
committerTheodore Ts'o <tytso@mit.edu>
Mon, 24 Mar 2014 18:43:12 +0000 (14:43 -0400)
commit5f16f3225b06242a9ee876f07c1c9b6ed36a22b6
treecebecf399c2d9ef5b0a24902638cb37d2e9e092b
parented3654eb981fd44694b4d2a636e13f998bc10e7f
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
fs/ext4/inode.c
fs/inode.c
include/linux/fs.h