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

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.

---
 fs/btrfs/send.c |   27 +++++++--------------------
 1 file changed, 7 insertions(+), 20 deletions(-)

index 143fed3..ab404ff 100644
@@ -3004,7 +3004,6 @@ static int apply_dir_move(struct send_ctx *sctx, struct pending_dir_move *pm)
 	struct fs_path *from_path = NULL;
 	struct fs_path *to_path = NULL;
 	struct fs_path *name = NULL;
-	u64 orig_progress = sctx->send_progress;
 	struct recorded_ref *cur;
 	u64 parent_ino, parent_gen;
 	struct waiting_dir_move *dm = NULL;

@@ -3028,23 +3027,13 @@ 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);
 	name = NULL;

@@ -3055,7 +3044,6 @@ static int apply_dir_move(struct send_ctx *sctx, struct pending_dir_move *pm)
 		goto out;
 	}
 
-	sctx->send_progress = sctx->cur_ino + 1;
 	ret = get_cur_path(sctx, pm->ino, pm->gen, to_path);
 	if (ret < 0)
 		goto out;

@@ -3113,7 +3101,6 @@ out:
 	fs_path_free(name);
 	fs_path_free(from_path);
 	fs_path_free(to_path);
-	sctx->send_progress = orig_progress;
 
 	return ret;
 }

1.7.10.4

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.

---

V2: Simpler version, removed more no longer needed code.

 fs/btrfs/send.c |   33 +++++++++------------------------
 1 file changed, 9 insertions(+), 24 deletions(-)

index 143fed3..a08ceca 100644
@@ -3028,33 +3028,18 @@ 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)

1.7.10.4