Patch "btrfs: always report error in run_one_delayed_ref()" has been added to the 6.1-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

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

    btrfs: always report error in run_one_delayed_ref()

to the 6.1-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-always-report-error-in-run_one_delayed_ref.patch
and it can be found in the queue-6.1 subdirectory.

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



commit ac03a244327e889fdceabf059448e453c6585ddb
Author: Qu Wenruo <wqu@xxxxxxxx>
Date:   Mon Dec 26 09:00:40 2022 +0800

    btrfs: always report error in run_one_delayed_ref()
    
    [ Upstream commit 39f501d68ec1ed5cd5c66ac6ec2a7131c517bb92 ]
    
    Currently we have a btrfs_debug() for run_one_delayed_ref() failure, but
    if end users hit such problem, there will be no chance that
    btrfs_debug() is enabled.  This can lead to very little useful info for
    debugging.
    
    This patch will:
    
    - Add extra info for error reporting
      Including:
      * logical bytenr
      * num_bytes
      * type
      * action
      * ref_mod
    
    - Replace the btrfs_debug() with btrfs_err()
    
    - Move the error reporting into run_one_delayed_ref()
      This is to avoid use-after-free, the @node can be freed in the caller.
    
    This error should only be triggered at most once.
    
    As if run_one_delayed_ref() failed, we trigger the error message, then
    causing the call chain to error out:
    
    btrfs_run_delayed_refs()
    `- btrfs_run_delayed_refs()
       `- btrfs_run_delayed_refs_for_head()
          `- run_one_delayed_ref()
    
    And we will abort the current transaction in btrfs_run_delayed_refs().
    If we have to run delayed refs for the abort transaction,
    run_one_delayed_ref() will just cleanup the refs and do nothing, thus no
    new error messages would be output.
    
    Reviewed-by: Anand Jain <anand.jain@xxxxxxxxxx>
    Signed-off-by: Qu Wenruo <wqu@xxxxxxxx>
    Signed-off-by: David Sterba <dsterba@xxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 2801c991814f..571fcc5ae4dc 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -1706,6 +1706,11 @@ static int run_one_delayed_ref(struct btrfs_trans_handle *trans,
 		BUG();
 	if (ret && insert_reserved)
 		btrfs_pin_extent(trans, node->bytenr, node->num_bytes, 1);
+	if (ret < 0)
+		btrfs_err(trans->fs_info,
+"failed to run delayed ref for logical %llu num_bytes %llu type %u action %u ref_mod %d: %d",
+			  node->bytenr, node->num_bytes, node->type,
+			  node->action, node->ref_mod, ret);
 	return ret;
 }
 
@@ -1947,8 +1952,6 @@ static int btrfs_run_delayed_refs_for_head(struct btrfs_trans_handle *trans,
 		if (ret) {
 			unselect_delayed_ref_head(delayed_refs, locked_ref);
 			btrfs_put_delayed_ref(ref);
-			btrfs_debug(fs_info, "run_one_delayed_ref returned %d",
-				    ret);
 			return ret;
 		}