btrfs: move btrfs_rm_dev_replace_free_srcdev outside of all locks

When closing and freeing the source device we could end up doing our
final blkdev_put() on the bdev, which will grab the bd_mutex.  As such
we want to be holding as few locks as possible, so move this call
outside of the dev_replace->lock_finishing_cancel_unmount lock.  Since
we're modifying the fs_devices we need to make sure we're holding the
uuid_mutex here, so take that as well.

Signed-off-by: Josef Bacik <[email protected]>
Signed-off-by: David Sterba <[email protected]>

fs/btrfs/dev-replace.c

@@ -748,7 +748,6 @@ static int btrfs_dev_replace_finishing(struct btrfs_fs_info *fs_info,
 	if (test_bit(BTRFS_DEV_STATE_WRITEABLE, &src_device->dev_state))
 		btrfs_scratch_superblocks(fs_info, src_device->bdev,
 					  src_device->name->str);
-	btrfs_rm_dev_replace_free_srcdev(src_device);
 
 	/* write back the superblocks */
 	trans = btrfs_start_transaction(root, 0);
@@ -757,6 +756,8 @@ static int btrfs_dev_replace_finishing(struct btrfs_fs_info *fs_info,
 
 	mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 
+	btrfs_rm_dev_replace_free_srcdev(src_device);
+
 	return 0;
 }
 

fs/btrfs/volumes.c

@@ -2224,6 +2224,8 @@ void btrfs_rm_dev_replace_free_srcdev(struct btrfs_device *srcdev)
 	struct btrfs_fs_info *fs_info = srcdev->fs_info;
 	struct btrfs_fs_devices *fs_devices = srcdev->fs_devices;
 
+	mutex_lock(&uuid_mutex);
+
 	btrfs_close_bdev(srcdev);
 	synchronize_rcu();
 	btrfs_free_device(srcdev);
@@ -2252,6 +2254,7 @@ void btrfs_rm_dev_replace_free_srcdev(struct btrfs_device *srcdev)
 		close_fs_devices(fs_devices);
 		free_fs_devices(fs_devices);
 	}
+	mutex_unlock(&uuid_mutex);
 }
 
 void btrfs_destroy_dev_replace_tgtdev(struct btrfs_device *tgtdev)