Re: [PATCH 0/6] btrfs: metadata uuid fixes and enhancements

[Nikolay Borisov <nborisov@suse.com>]

On 12.12.19 г. 13:01 ч., damenly.su@gmail.com wrote:
> From: Su Yue <Damenly_Su@gmx.com>
> 
> This patchset fixes one reproducible bug and add two split-brain
> cases ignored.
> 
> The origin code thinks the final state of successful synced device is
> always has INCOMPAT_METADATA_UUID feature. However, a device without
> the feature flag can be the one pull into disk. This is what handled
> in the patchset. Test images are added in btrfs-progs part.
> 
> Patch[1] fixes a bug about wrong fsid copy.
> Patch[2] is for the later patches.
> Patch[3-5] add the forgotten cases.
> Patch[6] just does simple code movement for grace.
> 
> The set passes xfstests-dev without regressions.
> 
> Su Yue (6):
>   btrfs: metadata_uuid: fix failed assertion due to unsuccessful device
>     scan
>   btrfs: metadata_uuid: move split-brain handling from fs_id() to new
>     function
>   btrfs: split-brain case for scanned changing device with
>     INCOMPAT_METADATA_UUID
>   btrfs: split-brain case for scanned changed device without
>     INCOMPAT_METADATA_UUID
>   btrfs: copy fsid and metadata_uuid for pulled disk without
>     INCOMPAT_METADATA_UUID
>   btrfs: metadata_uuid: move partly logic into find_fsid_inprogress()
> 
>  fs/btrfs/volumes.c | 193 +++++++++++++++++++++++++++++----------------
>  1 file changed, 125 insertions(+), 68 deletions(-)
> 


I'm currently on holiday but the fsid change feature has a design
document here:
https://github.com/btrfs/btrfs-dev-docs/blob/master/fsid-change.txt

it lists all the cases I have handled. If you think there are other
please first describe them in prose following the parlance set out in
the document to ease reasoning.