Btrfs: don't do anything in our ->freeze_fs and ->unfreeze_fs

We do not need to do anything special to freeze or unfreeze, it's all taken
care of by the generic work, and what we currently have is wrong anyway
since we shouldn't be returnning to userspace with mutexes held anyway.
Thanks,

Signed-off-by: Josef Bacik <jbacik@fusionio.com>

fs/btrfs/super.c

@@ -1511,17 +1511,11 @@ static long btrfs_control_ioctl(struct file *file, unsigned int cmd,
 
 static int btrfs_freeze(struct super_block *sb)
 {
-	struct btrfs_fs_info *fs_info = btrfs_sb(sb);
-	mutex_lock(&fs_info->transaction_kthread_mutex);
-	mutex_lock(&fs_info->cleaner_mutex);
 	return 0;
 }
 
 static int btrfs_unfreeze(struct super_block *sb)
 {
-	struct btrfs_fs_info *fs_info = btrfs_sb(sb);
-	mutex_unlock(&fs_info->cleaner_mutex);
-	mutex_unlock(&fs_info->transaction_kthread_mutex);
 	return 0;
 }