Re: [PATCH v3 0/4] btrfs: make read time repair to be only submitted for each corrupted sector

[David Sterba <dsterba@suse.cz>]

On Mon, May 03, 2021 at 10:08:52AM +0800, Qu Wenruo wrote:
> Btrfs read time repair has to handle two different cases when a corruption
> or read failure is hit:
> - The failed bio contains only one sector
>   Then it only need to find a good copy
> 
> - The failed bio contains several sectors
>   Then it needs to find which sectors really need to be repaired
> 
> But this different behaviors are not really needed, as we can teach btrfs
> to only submit read repair for each corrupted sector.
> By this, we only need to handle the one-sector corruption case.
> 
> This not only makes the code smaller and simpler, but also benefits subpage,
> allow subpage case to use the same infrastructure.
> 
> For current subpage code, we hacked the read repair code to make full
> bvec read repair, which has less granularity compared to regular sector
> size.
> 
> The code is still based on subpage branch, but can be forward ported to
> non-subpage code basis with minor conflicts.
> 
> Changelog:
> v2:
> - Split the original patch
>   Now we have two preparation patches, then the core change.
>   And finally a cleanup.
> 
> - Fix the uninitialize @error_bitmap when the bio read fails.
> 
> v3:
> - Fix the return value type mismatch in repair_one_sector()
>   An error happens in v2 patch split, which can lead to hang when
>   we can't repair the error.

Patchset added to for-next. The cleanups and simplifications look good
to me, thanks.