Re: [PATCH v2] btrfs: extract the parity scrub code into a helper

[David Sterba <dsterba@suse.cz>]

On Thu, Nov 06, 2025 at 08:02:15PM +1030, Qu Wenruo wrote:
> The function scrub_raid56_parity_stripe() is handling the partity stripe
> by the following steps:
> 
> - Scrub each data stripes
>   And make sure everything is fine in each data stripe
> 
> - Cache the data stripe into the raid bio
> 
> - Use the cached raid bio to scrub the target parity stripe
> 
> Extract the last two steps into a new helper,
> scrub_radi56_cached_parity(), as a cleanup and make the error handling
> more straightforward.
> 
> With the following minor cleanups:
> 
> - Use on-stack bio structure
>   The bio is always empty thus we do not need any bio vector nor the
>   block device. Thus there is no need to allocate a bio, the on-stack
>   one is more than enough to cut it.
> 
> - Remove the unnecessary btrfs_put_bioc() call if btrfs_map_block()
>   failed
>   If btrfs_map_block() is failed, @bioc_ret will not be touched thus
>   there is no need to call btrfs_put_bioc() in this case.
> 
> - Use a proper out: tag to do the cleanup
>   Now the error cleanup is much shorter and simpler, just
>   btrfs_bio_counter_dec() and bio_uninit().
> 
> Signed-off-by: Qu Wenruo <wqu@suse.com>
> ---
> Changelog:
> v2:
> - Rebased to the latest for-next branch
>   The latest branch has the memory leak fixed merged, causing a minor
>   conflict.
> 
> - Remove the DECLARE_COMPLETION_ONSTACK() inside the caller
>   Which is no longer utilized.

Reviewed-by: David Sterba <dsterba@suse.com>