btrfs: remove superfluous chunk_tree argument from btrfs_alloc_dev_extent

Currently this function is always called with the object id of the root
key of the chunk_tree, which is always BTRFS_CHUNK_TREE_OBJECTID. So
let's subsume it straight into the function itself. No functional
change.
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/volumes.c

@@ -1571,8 +1571,7 @@ static int btrfs_free_dev_extent(struct btrfs_trans_handle *trans,
 
 static int btrfs_alloc_dev_extent(struct btrfs_trans_handle *trans,
 				  struct btrfs_device *device,
-				  u64 chunk_tree, u64 chunk_offset, u64 start,
-				  u64 num_bytes)
+				  u64 chunk_offset, u64 start, u64 num_bytes)
 {
 	int ret;
 	struct btrfs_path *path;
@@ -1599,7 +1598,8 @@ static int btrfs_alloc_dev_extent(struct btrfs_trans_handle *trans,
 	leaf = path->nodes[0];
 	extent = btrfs_item_ptr(leaf, path->slots[0],
 				struct btrfs_dev_extent);
-	btrfs_set_dev_extent_chunk_tree(leaf, extent, chunk_tree);
+	btrfs_set_dev_extent_chunk_tree(leaf, extent,
+					BTRFS_CHUNK_TREE_OBJECTID);
 	btrfs_set_dev_extent_chunk_objectid(leaf, extent,
 					    BTRFS_FIRST_CHUNK_TREE_OBJECTID);
 	btrfs_set_dev_extent_chunk_offset(leaf, extent, chunk_offset);
@@ -4903,10 +4903,8 @@ int btrfs_finish_chunk_alloc(struct btrfs_trans_handle *trans,
 		ret = btrfs_update_device(trans, device);
 		if (ret)
 			break;
-		ret = btrfs_alloc_dev_extent(trans, device,
-					     chunk_root->root_key.objectid,
-					     chunk_offset, dev_offset,
-					     stripe_size);
+		ret = btrfs_alloc_dev_extent(trans, device, chunk_offset,
+					     dev_offset, stripe_size);
 		if (ret)
 			break;
 	}