Patch "btrfs: handle chunk tree lookup error in btrfs_relocate_sys_chunks()" has been added to the 5.10-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    btrfs: handle chunk tree lookup error in btrfs_relocate_sys_chunks()

to the 5.10-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     btrfs-handle-chunk-tree-lookup-error-in-btrfs_reloca.patch
and it can be found in the queue-5.10 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit eebd09941f051e3ec848d5e9186e27a868287d09
Author: David Sterba <dsterba@xxxxxxxx>
Date:   Tue Jan 23 23:42:29 2024 +0100

    btrfs: handle chunk tree lookup error in btrfs_relocate_sys_chunks()
    
    [ Upstream commit 7411055db5ce64f836aaffd422396af0075fdc99 ]
    
    The unhandled case in btrfs_relocate_sys_chunks() loop is a corruption,
    as it could be caused only by two impossible conditions:
    
    - at first the search key is set up to look for a chunk tree item, with
      offset -1, this is an inexact search and the key->offset will contain
      the correct offset upon a successful search, a valid chunk tree item
      cannot have an offset -1
    
    - after first successful search, the found_key corresponds to a chunk
      item, the offset is decremented by 1 before the next loop, it's
      impossible to find a chunk item there due to alignment and size
      constraints
    
    Reviewed-by: Josef Bacik <josef@xxxxxxxxxxxxxx>
    Reviewed-by: Anand Jain <anand.jain@xxxxxxxxxx>
    Signed-off-by: David Sterba <dsterba@xxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 9a05313c69f33..09c23626feba4 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -3178,7 +3178,17 @@ static int btrfs_relocate_sys_chunks(struct btrfs_fs_info *fs_info)
 			mutex_unlock(&fs_info->delete_unused_bgs_mutex);
 			goto error;
 		}
-		BUG_ON(ret == 0); /* Corruption */
+		if (ret == 0) {
+			/*
+			 * On the first search we would find chunk tree with
+			 * offset -1, which is not possible. On subsequent
+			 * loops this would find an existing item on an invalid
+			 * offset (one less than the previous one, wrong
+			 * alignment and size).
+			 */
+			ret = -EUCLEAN;
+			goto error;
+		}
 
 		ret = btrfs_previous_item(chunk_root, path, key.objectid,
 					  key.type);