diff options
| author | Miao Xie <miaox@cn.fujitsu.com> | 2013-01-29 14:14:48 +0400 |
|---|---|---|
| committer | Josef Bacik <jbacik@fusionio.com> | 2013-02-20 21:59:09 +0400 |
| commit | 87533c475187c1420794a2e164bc67a7974f1327 (patch) | |
| tree | 699709da85c0a6c284cf37fe7026fbaf4768e6ab /fs/btrfs/transaction.c | |
| parent | de98ced9e743656d108de41841797def0f5cb951 (diff) | |
| download | linux-87533c475187c1420794a2e164bc67a7974f1327.tar.xz | |
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/transaction.c')
| -rw-r--r-- | fs/btrfs/transaction.c | 9 |
1 files changed, 4 insertions, 5 deletions
diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c index 34610dc6d140..baf6d74fd0f2 100644 --- a/fs/btrfs/transaction.c +++ b/fs/btrfs/transaction.c @@ -61,7 +61,7 @@ static noinline int join_transaction(struct btrfs_root *root, int type) spin_lock(&fs_info->trans_lock); loop: /* The file system has been taken offline. No new transactions. */ - if (fs_info->fs_state & BTRFS_SUPER_FLAG_ERROR) { + if (test_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state)) { spin_unlock(&fs_info->trans_lock); return -EROFS; } @@ -113,7 +113,7 @@ loop: kmem_cache_free(btrfs_transaction_cachep, cur_trans); cur_trans = fs_info->running_transaction; goto loop; - } else if (fs_info->fs_state & BTRFS_SUPER_FLAG_ERROR) { + } else if (test_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state)) { spin_unlock(&fs_info->trans_lock); kmem_cache_free(btrfs_transaction_cachep, cur_trans); return -EROFS; @@ -301,7 +301,7 @@ start_transaction(struct btrfs_root *root, u64 num_items, int type, int ret; u64 qgroup_reserved = 0; - if (root->fs_info->fs_state & BTRFS_SUPER_FLAG_ERROR) + if (test_bit(BTRFS_FS_STATE_ERROR, &root->fs_info->fs_state)) return ERR_PTR(-EROFS); if (current->journal_info) { @@ -645,9 +645,8 @@ static int __btrfs_end_transaction(struct btrfs_trans_handle *trans, btrfs_run_delayed_iputs(root); if (trans->aborted || - root->fs_info->fs_state & BTRFS_SUPER_FLAG_ERROR) { + test_bit(BTRFS_FS_STATE_ERROR, &root->fs_info->fs_state)) err = -EIO; - } assert_qgroups_uptodate(trans); kmem_cache_free(btrfs_trans_handle_cachep, trans); |