[PATCH 3.16 081/366] btrfs: Handle error from btrfs_uuid_tree_rem call in _btrfs_ioctl_set_received_subvol

[Ben Hutchings]

3.16.60-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Nikolay Borisov <nborisov@xxxxxxxx>

commit d87ff75863e92a500538ab53318c5740f196631e upstream.

As with every function which deals with modifying the btree
btrfs_uuid_tree_rem can fail for any number of reasons (ie. EIO/ENOMEM).
Handle return error value from this function gracefully by aborting the
transaction.

Fixes: dd5f9615fc5c ("Btrfs: maintain subvolume items in the UUID tree")
Signed-off-by: Nikolay Borisov <nborisov@xxxxxxxx>
Reviewed-by: David Sterba <dsterba@xxxxxxxx>
Signed-off-by: David Sterba <dsterba@xxxxxxxx>
[bwh: Backported to 3.16:
 - btrfs_{abort,end}_transaction() take a pointer to btrfs_root
 - Adjust context]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -5051,11 +5051,17 @@ static long _btrfs_ioctl_set_received_su
 	received_uuid_changed = memcmp(root_item->received_uuid, sa->uuid,
 				       BTRFS_UUID_SIZE);
 	if (received_uuid_changed &&
-	    !btrfs_is_empty_uuid(root_item->received_uuid))
-		btrfs_uuid_tree_rem(trans, root->fs_info->uuid_root,
-				    root_item->received_uuid,
-				    BTRFS_UUID_KEY_RECEIVED_SUBVOL,
-				    root->root_key.objectid);
+	    !btrfs_is_empty_uuid(root_item->received_uuid)) {
+		ret = btrfs_uuid_tree_rem(trans, root->fs_info->uuid_root,
+					  root_item->received_uuid,
+					  BTRFS_UUID_KEY_RECEIVED_SUBVOL,
+					  root->root_key.objectid);
+		if (ret && ret != -ENOENT) {
+			btrfs_abort_transaction(trans, root, ret);
+		        btrfs_end_transaction(trans, root);
+		        goto out;
+		}
+	}
 	memcpy(root_item->received_uuid, sa->uuid, BTRFS_UUID_SIZE);
 	btrfs_set_root_stransid(root_item, sa->stransid);
 	btrfs_set_root_rtransid(root_item, sa->rtransid);