Hi
I applied the patch, thanks.
Mikulas
On Fri, 2 May 2025, John Garry wrote:
> Feature flag BLK_FEAT_ATOMIC_WRITES is not being properly set for the
> target queue limits, and this means that atomic writes are not being
> enabled for any dm personalities.
>
> When calling dm_set_device_limits() -> blk_stack_limits() ->
> ... -> blk_stack_atomic_writes_limits(), the bottom device limits
> (which corresponds to intermediate target queue limits) does not have
> BLK_FEAT_ATOMIC_WRITES set, and so atomic writes can never be enabled.
>
> Typically such a flag would be inherited from the stacked device in
> dm_set_device_limits() -> blk_stack_limits() via BLK_FEAT_INHERIT_MASK,
> but BLK_FEAT_ATOMIC_WRITES is not inherited as it's preferred to manually
> enable on a per-personality basis.
>
> Set BLK_FEAT_ATOMIC_WRITES manually for the intermediate target queue
> limits from the stacked device to get atomic writes working.
>
> Fixes: 3194e36488e2 ("dm-table: atomic writes support")
> Signed-off-by: John Garry <john.g.ga...@oracle.com>
>
> diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
> index 9e175c5e0634..b35e48fed641 100644
> --- a/drivers/md/dm-table.c
> +++ b/drivers/md/dm-table.c
> @@ -431,6 +431,12 @@ static int dm_set_device_limits(struct dm_target *ti,
> struct dm_dev *dev,
> return 0;
> }
>
> + /*
> + * BLK_FEAT_ATOMIC_WRITES is not inherited from the bottom device in
> + * blk_stack_limits(), so do it manually.
> + */
> + limits->features |= (q->limits.features & BLK_FEAT_ATOMIC_WRITES);
> +
> if (blk_stack_limits(limits, &q->limits,
> get_start_sect(bdev) + start) < 0)
> DMWARN("%s: adding target device %pg caused an alignment
> inconsistency: "
> --
> 2.31.1
>
