Btrfs: avoid unnecessary utimes update in incremental send

When we're finishing processing of an inode, if we're dealing with a
directory inode that has a pending move/rename operation, we don't
need to send a utimes update instruction to the send stream, as we'll
do it later after doing the move/rename operation. Therefore we save
some time here building paths and doing btree lookups.
Signed-off-by: Filipe David Borba Manana <fdmanana@gmail.com>
Signed-off-by: Josef Bacik <jbacik@fb.com>

fs/btrfs/send.c

@@ -4957,17 +4957,18 @@ static int finish_inode_if_needed(struct send_ctx *sctx, int at_end)
 		ret = apply_children_dir_moves(sctx);
 		if (ret)
 			goto out;
-	}
-
 		/*
 		 * Need to send that every time, no matter if it actually
 		 * changed between the two trees as we have done changes to
-	 * the inode before.
+		 * the inode before. If our inode is a directory and it's
+		 * waiting to be moved/renamed, we will send its utimes when
+		 * it's moved/renamed, therefore we don't need to do it here.
 		 */
 		sctx->send_progress = sctx->cur_ino + 1;
 		ret = send_utimes(sctx, sctx->cur_ino, sctx->cur_inode_gen);
 		if (ret < 0)
 			goto out;
+	}
 
 out:
 	return ret;