f2fs: atomically set inode->i_flags in f2fs_set_inode_flags()
Use set_mask_bits() to atomically set i_flags instead of clearing out the
S_IMMUTABLE, S_APPEND, etc. flags and then setting them from the
FS_IMMUTABLE_FL, FS_APPEND_FL, etc. flags, since this opens up a race
where an immutable file has the immutable flag cleared for a brief
window of time.
Signed-off-by: Zhang Zhen <zhenzhang.zhang@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
diff --git a/fs/f2fs/inode.c b/fs/f2fs/inode.c
index ee829d3..f7a6553 100644
--- a/fs/f2fs/inode.c
+++ b/fs/f2fs/inode.c
@@ -12,6 +12,7 @@
#include <linux/f2fs_fs.h>
#include <linux/buffer_head.h>
#include <linux/writeback.h>
+#include <linux/bitops.h>
#include "f2fs.h"
#include "node.h"
@@ -21,20 +22,20 @@
void f2fs_set_inode_flags(struct inode *inode)
{
unsigned int flags = F2FS_I(inode)->i_flags;
-
- inode->i_flags &= ~(S_SYNC | S_APPEND | S_IMMUTABLE |
- S_NOATIME | S_DIRSYNC);
+ unsigned int new_fl = 0;
if (flags & FS_SYNC_FL)
- inode->i_flags |= S_SYNC;
+ new_fl |= S_SYNC;
if (flags & FS_APPEND_FL)
- inode->i_flags |= S_APPEND;
+ new_fl |= S_APPEND;
if (flags & FS_IMMUTABLE_FL)
- inode->i_flags |= S_IMMUTABLE;
+ new_fl |= S_IMMUTABLE;
if (flags & FS_NOATIME_FL)
- inode->i_flags |= S_NOATIME;
+ new_fl |= S_NOATIME;
if (flags & FS_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);
}
static void __get_inode_rdev(struct inode *inode, struct f2fs_inode *ri)