btrfs: use mutex in btrfs_resume_balance_async

While the spinlock does not cause problems, using the mutex is more
correct and consistent with others. The global status of balance is eg.
checked from btrfs_pause_balance or btrfs_cancel_balance with mutex.

Resuming balance happens during mount or ro->rw remount. In the former
case, no other user of the balance_ctl exists, in the latter, balance
cannot run until the ro/rw transition is finished.

Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>

1 files changed, 3 insertions, 3 deletions

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 197b91b0e15b..447a0c275b43 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -3959,12 +3959,12 @@ int btrfs_resume_balance_async(struct btrfs_fs_info *fs_info)
 {
         struct task_struct *tsk;
 
-        spin_lock(&fs_info->balance_lock);
+        mutex_lock(&fs_info->balance_mutex);
         if (!fs_info->balance_ctl) {
-                spin_unlock(&fs_info->balance_lock);
+                mutex_unlock(&fs_info->balance_mutex);
                 return 0;
         }
-        spin_unlock(&fs_info->balance_lock);
+        mutex_unlock(&fs_info->balance_mutex);
 
         if (btrfs_test_opt(fs_info, SKIP_BALANCE)) {
                 btrfs_info(fs_info, "force skipping balance");