From: Theodore Ts'o <tytso@mit.edu>
Date: Sun, 30 Mar 2014 14:20:01 +0000 (-0400)
Subject: ext4: atomically set inode->i_flags in ext4_set_inode_flags()
X-Git-Tag: v3.2.57~15
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=630176c5033a4ed19a0fc6608980344657ba69af;p=pandora-kernel.git

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

commit 00a1a053ebe5febcfc2ec498bd894f035ad2aa06 upstream.

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>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---

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