diff options
author | Wang Shilong <wangsl-fnst@cn.fujitsu.com> | 2013-04-07 10:50:16 +0000 |
---|---|---|
committer | Josef Bacik <jbacik@fusionio.com> | 2013-05-06 15:54:38 -0400 |
commit | f2f6ed3d54648ec19dcdeec30f66843cf7a38487 (patch) | |
tree | cc82afe22a835994252961f21e422258393a8974 /fs/btrfs/ctree.h | |
parent | 7708f029dca5f1b9e9d6ea01ab10cd83e4c74ff2 (diff) |
Btrfs: introduce a mutex lock for btrfs quota operations
The original code has one spin_lock 'qgroup_lock' to protect quota
configurations in memory. If we want to add a BTRFS_QGROUP_INFO_KEY,
it will be added to Btree firstly, and then update configurations in
memory,however, a race condition may happen between these operations.
For example:
->add_qgroup_info_item()
->add_qgroup_rb()
For the above case, del_qgroup_info_item() may happen just before
add_qgroup_rb().
What's worse, when we want to add a qgroup relation:
->add_qgroup_relation_item()
->add_qgroup_relations()
We don't have any checks whether 'src' and 'dst' exist before
add_qgroup_relation_item(), a race condition can also happen for
the above case.
To avoid race condition and have all the necessary checks, we introduce
a mutex lock 'qgroup_ioctl_lock', and we make all the user change operations
protected by the mutex lock.
Signed-off-by: Wang Shilong <wangsl-fnst@cn.fujitsu.com>
Reviewed-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Diffstat (limited to 'fs/btrfs/ctree.h')
-rw-r--r-- | fs/btrfs/ctree.h | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h index 075a8a0e49c4..1a850402937d 100644 --- a/fs/btrfs/ctree.h +++ b/fs/btrfs/ctree.h @@ -1583,6 +1583,9 @@ struct btrfs_fs_info { struct rb_root qgroup_tree; spinlock_t qgroup_lock; + /* protect user change for quota operations */ + struct mutex qgroup_ioctl_lock; + /* list of dirty qgroups to be written at next commit */ struct list_head dirty_qgroups; |