path: root/fs/btrfs/disk-io.c
diff options
authorWang Shilong <>2013-04-07 10:50:16 +0000
committerJosef Bacik <>2013-05-06 15:54:38 -0400
commitf2f6ed3d54648ec19dcdeec30f66843cf7a38487 (patch)
treecc82afe22a835994252961f21e422258393a8974 /fs/btrfs/disk-io.c
parent7708f029dca5f1b9e9d6ea01ab10cd83e4c74ff2 (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 <> Reviewed-by: Miao Xie <> Signed-off-by: Josef Bacik <>
Diffstat (limited to 'fs/btrfs/disk-io.c')
1 files changed, 1 insertions, 0 deletions
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 70e6b0c32db2..9f83e5b870d2 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -2213,6 +2213,7 @@ int open_ctree(struct super_block *sb,
+ mutex_init(&fs_info->qgroup_ioctl_lock);
fs_info->qgroup_tree = RB_ROOT;
fs_info->qgroup_seq = 1;