@@ -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"
@@ -3770,18 +3771,20 @@ int ext4_get_inode_loc(struct inode *inode, struct ext4_iloc *iloc)
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 */
@@ -185,6 +185,21 @@ static inline unsigned long __ffs64(u64 word)
#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
This is a note to let you know that I have just added a patch titled ext4: atomically set inode->i_flags in ext4_set_inode_flags() to the linux-3.8.y-queue branch of the 3.8.y.z extended stable tree which can be found at: http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.8.y-queue This patch is scheduled to be released in version 3.8.13.21. If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.8.y.z tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Kamal ------ From 26832d045b85146f2fdf9228308ae7b7fc54f4b5 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() 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: Kamal Mostafa <kamal@canonical.com> --- fs/ext4/inode.c | 15 +++++++++------ include/linux/bitops.h | 15 +++++++++++++++ 2 files changed, 24 insertions(+), 6 deletions(-) -- 1.8.3.2