Re: [PATCH 0/3] btrfs: disguise single-data-RAID56 as RAID1/RAID1C3

[Qu Wenruo <wqu@suse.com>]

Hi David,

I know you hate this way to fix the problem, but considering it's 
already 7.2-rc3, if you do not like this method I think it's time for 
you to submit your alternative.

My existing patches still apply on the latest for-next and is known to 
avoid the extra warning from RAID6 lib.

Thanks,
Qu

在 2026/5/22 18:53, Qu Wenruo 写道:
> [CHANGELOG]
> RFC->v1:
> - Remove unused btrfs_chunk_map::io_(align|width) members
>    To make space for the new member.
> 
> - Fix a duplicated bg->flags assignment in fill_dummy_bgs()
>    Just exposed by the last patch which also touches that code.
> 
> - Use a dedicated member to record the on-disk chunk type
>    So it's less fragile than the RFC patch.
> 
> The single-data-RAID56 (2 disks raid5 or 3 disks raid6) is not a feature
> that should be supported in the first place, thus raid56 is going to
> remove such support.
> 
> Meanwhile rejecting single-data-RAID56 will cause existing btrfs users
> unable to mount their fs, even if there is only a single
> empty chunk with that flag, mostly caused by some degraded mount.
> 
> So to avoid impacting existing users, implement an internal
> single-data-RAID56 to RAID1/RAID1C3 mapping, to co-operate with the
> upstream raid56 lib changes.
> 
> Qu Wenruo (3):
>    btrfs: remove btrfs_chunk_map::io_(align|width) members
>    btrfs: remove duplicated block group type assignment
>    btrfs: disguise single-data-RAID56 as RAID1/RAID1C3
> 
>   fs/btrfs/block-group.c |  3 +--
>   fs/btrfs/volumes.c     | 25 ++++++++++++++++++-------
>   fs/btrfs/volumes.h     | 10 ++++++++--
>   3 files changed, 27 insertions(+), 11 deletions(-)
>