Btrfs: creating the subvolume qgroup automatically when enabling quota

Creating the subvolume/snapshots(including root subvolume) qgroup
auotomatically when enabling quota.

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>

1 files changed, 2 insertions, 0 deletions

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 9c44d657b795..4fc9751d2e0c 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -3697,6 +3697,7 @@ static long btrfs_ioctl_quota_ctl(struct file *file, void __user *arg)
                 goto drop_write;
         }
 
+        down_write(&root->fs_info->subvol_sem);
         if (sa->cmd != BTRFS_QUOTA_CTL_RESCAN) {
                 trans = btrfs_start_transaction(root, 2);
                 if (IS_ERR(trans)) {
@@ -3730,6 +3731,7 @@ static long btrfs_ioctl_quota_ctl(struct file *file, void __user *arg)
         }
 out:
         kfree(sa);
+        up_write(&root->fs_info->subvol_sem);
 drop_write:
         mnt_drop_write_file(file);
         return ret;