From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Date: Mon, 31 Mar 2014 22:15:49 +0000 (-0700)
Subject: 3.4-stable patches
X-Git-Tag: v3.4.86~10
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=38b68adbf739c3fb28273c1d42d85119f1890eaf;p=thirdparty%2Fkernel%2Fstable-queue.git

3.4-stable patches

added patches:
	ext4-atomically-set-inode-i_flags-in-ext4_set_inode_flags.patch
---

diff --git a/queue-3.4/ext4-atomically-set-inode-i_flags-in-ext4_set_inode_flags.patch b/queue-3.4/ext4-atomically-set-inode-i_flags-in-ext4_set_inode_flags.patch
new file mode 100644
index 00000000000..884dd235e67
--- /dev/null
+++ b/queue-3.4/ext4-atomically-set-inode-i_flags-in-ext4_set_inode_flags.patch
@@ -0,0 +1,86 @@
+From 00a1a053ebe5febcfc2ec498bd894f035ad2aa06 Mon Sep 17 00:00:00 2001
+From: Theodore Ts'o <tytso@mit.edu>
+Date: Sun, 30 Mar 2014 10:20:01 -0400
+Subject: ext4: atomically set inode->i_flags in ext4_set_inode_flags()
+
+From: Theodore Ts'o <tytso@mit.edu>
+
+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>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+
+---
+ fs/ext4/inode.c        |   15 +++++++++------
+ include/linux/bitops.h |   15 +++++++++++++++
+ 2 files changed, 24 insertions(+), 6 deletions(-)
+
+--- a/fs/ext4/inode.c
++++ b/fs/ext4/inode.c
+@@ -37,6 +37,7 @@
+ #include <linux/printk.h>
+ #include <linux/slab.h>
+ #include <linux/ratelimit.h>
++#include <linux/bitops.h>
+ 
+ #include "ext4_jbd2.h"
+ #include "xattr.h"
+@@ -3580,18 +3581,20 @@ int ext4_get_inode_loc(struct inode *ino
+ void ext4_set_inode_flags(struct inode *inode)
+ {
+ 	unsigned int flags = EXT4_I(inode)->i_flags;
++	unsigned int new_fl = 0;
+ 
+-	inode->i_flags &= ~(S_SYNC|S_APPEND|S_IMMUTABLE|S_NOATIME|S_DIRSYNC);
+ 	if (flags & EXT4_SYNC_FL)
+-		inode->i_flags |= S_SYNC;
++		new_fl |= S_SYNC;
+ 	if (flags & EXT4_APPEND_FL)
+-		inode->i_flags |= S_APPEND;
++		new_fl |= S_APPEND;
+ 	if (flags & EXT4_IMMUTABLE_FL)
+-		inode->i_flags |= S_IMMUTABLE;
++		new_fl |= S_IMMUTABLE;
+ 	if (flags & EXT4_NOATIME_FL)
+-		inode->i_flags |= S_NOATIME;
++		new_fl |= S_NOATIME;
+ 	if (flags & EXT4_DIRSYNC_FL)
+-		inode->i_flags |= S_DIRSYNC;
++		new_fl |= S_DIRSYNC;
++	set_mask_bits(&inode->i_flags,
++		      S_SYNC|S_APPEND|S_IMMUTABLE|S_NOATIME|S_DIRSYNC, new_fl);
+ }
+ 
+ /* Propagate flags from i_flags to EXT4_I(inode)->i_flags */
+--- a/include/linux/bitops.h
++++ b/include/linux/bitops.h
+@@ -185,6 +185,21 @@ static inline unsigned long __ffs64(u64
+ 
+ #ifdef __KERNEL__
+ 
++#ifndef set_mask_bits
++#define set_mask_bits(ptr, _mask, _bits)	\
++({								\
++	const typeof(*ptr) mask = (_mask), bits = (_bits);	\
++	typeof(*ptr) old, new;					\
++								\
++	do {							\
++		old = ACCESS_ONCE(*ptr);			\
++		new = (old & ~mask) | bits;			\
++	} while (cmpxchg(ptr, old, new) != old);		\
++								\
++	new;							\
++})
++#endif
++
+ #ifndef find_last_bit
+ /**
+  * find_last_bit - find the last set bit in a memory region