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| author | Miao Xie <miaox@cn.fujitsu.com> | 2013-01-29 10:14:48 +0000 |
|---|---|---|
| committer | Josef Bacik <jbacik@fusionio.com> | 2013-02-20 12:59:09 -0500 |
| commit | 87533c475187c1420794a2e164bc67a7974f1327 (patch) | |
| tree | 699709da85c0a6c284cf37fe7026fbaf4768e6ab /fs/btrfs/super.c | |
| parent | de98ced9e743656d108de41841797def0f5cb951 (diff) | |
| download | op-kernel-dev-87533c475187c1420794a2e164bc67a7974f1327.zip op-kernel-dev-87533c475187c1420794a2e164bc67a7974f1327.tar.gz | |
Btrfs: use bit operation for ->fs_state
There is no lock to protect fs_info->fs_state, it will introduce
some problems, such as the value may be covered by the other task
when several tasks modify it. For example:
Task0 - CPU0 Task1 - CPU1
mov %fs_state rax
or $0x1 rax
mov %fs_state rax
or $0x2 rax
mov rax %fs_state
mov rax %fs_state
The expected value is 3, but in fact, it is 2.
Though this problem doesn't happen now (because there is only one
flag currently), the code is error prone, if we add other flags,
the above problem will happen to a certainty.
Now we use bit operation for it to fix the above problem.
In this way, we can make the code more robust and be easy to
add new flags.
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Diffstat (limited to 'fs/btrfs/super.c')
| -rw-r--r-- | fs/btrfs/super.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c index eda330d..4152f9e 100644 --- a/fs/btrfs/super.c +++ b/fs/btrfs/super.c @@ -98,7 +98,7 @@ static void __save_error_info(struct btrfs_fs_info *fs_info) * today we only save the error info into ram. Long term we'll * also send it down to the disk */ - fs_info->fs_state = BTRFS_SUPER_FLAG_ERROR; + set_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state); } static void save_error_info(struct btrfs_fs_info *fs_info) @@ -114,7 +114,7 @@ static void btrfs_handle_error(struct btrfs_fs_info *fs_info) if (sb->s_flags & MS_RDONLY) return; - if (fs_info->fs_state & BTRFS_SUPER_FLAG_ERROR) { + if (test_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state)) { sb->s_flags |= MS_RDONLY; printk(KERN_INFO "btrfs is forced readonly\n"); /* |
