Btrfs: send, account for orphan directories when building path strings

commit c992ec94f24c3e7135d6c23860615f269f0b1d87 upstream.

If we have directories with a pending move/rename operation, we must take into
account any orphan directories that got created before executing the pending
move/rename. Those orphan directories are directories with an inode number higher
then the current send progress and that don't exist in the parent snapshot, they
are created before current progress reaches their inode number, with a generated
name of the form oN-M-I and at the root of the filesystem tree, and later when
progress matches their inode number, moved/renamed to their final location.

Reproducer:

          $ mkfs.btrfs -f /dev/sdd
          $ mount /dev/sdd /mnt

          $ mkdir -p /mnt/a/b/c/d
          $ mkdir /mnt/a/b/e
          $ mv /mnt/a/b/c /mnt/a/b/e/CC
          $ mkdir /mnt/a/b/e/CC/d/f
	  $ mkdir /mnt/a/g

          $ btrfs subvolume snapshot -r /mnt /mnt/snap1
          $ btrfs send /mnt/snap1 -f /tmp/base.send

          $ mkdir /mnt/a/g/h
	  $ mv /mnt/a/b/e /mnt/a/g/h/EE
          $ mv /mnt/a/g/h/EE/CC/d /mnt/a/g/h/EE/DD

          $ btrfs subvolume snapshot -r /mnt /mnt/snap2
          $ btrfs send -p /mnt/snap1 /mnt/snap2 -f /tmp/incremental.send

The second receive command failed with the following error:

    ERROR: rename a/b/e/CC/d -> o264-7-0/EE/DD failed. No such file or directory

A test case for xfstests follows soon.

Signed-off-by: Filipe David Borba Manana <fdmanana@gmail.com>
Signed-off-by: Chris Mason <clm@fb.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 9 insertions, 24 deletions

diff --git a/fs/btrfs/send.c b/fs/btrfs/send.c
index 484aacac2c8..3a5b83ae605 100644
--- a/fs/btrfs/send.c
+++ b/fs/btrfs/send.c
@@ -3054,33 +3054,18 @@ static int apply_dir_move(struct send_ctx *sctx, struct pending_dir_move *pm)
 	if (ret < 0)
 		goto out;
 
-	if (parent_ino == sctx->cur_ino) {
-		/* child only renamed, not moved */
-		ASSERT(parent_gen == sctx->cur_inode_gen);
-		ret = get_cur_path(sctx, sctx->cur_ino, sctx->cur_inode_gen,
-				   from_path);
-		if (ret < 0)
-			goto out;
-		ret = fs_path_add_path(from_path, name);
-		if (ret < 0)
-			goto out;
-	} else {
-		/* child moved and maybe renamed too */
-		sctx->send_progress = pm->ino;
-		ret = get_cur_path(sctx, pm->ino, pm->gen, from_path);
-		if (ret < 0)
-			goto out;
-	}
+	ret = get_cur_path(sctx, parent_ino, parent_gen,
+			   from_path);
+	if (ret < 0)
+		goto out;
+	ret = fs_path_add_path(from_path, name);
+	if (ret < 0)
+		goto out;
 
-	fs_path_free(name);
+	fs_path_reset(name);
+	to_path = name;
 	name = NULL;
 
-	to_path = fs_path_alloc();
-	if (!to_path) {
-		ret = -ENOMEM;
-		goto out;
-	}
-
 	sctx->send_progress = sctx->cur_ino + 1;
 	ret = get_cur_path(sctx, pm->ino, pm->gen, to_path);
 	if (ret < 0)