Applied, thanks.
Mikulas
On Wed, 11 Jun 2025, Damien Le Moal wrote:
> For a zoned dm-crypt device, the native support for zone append
> operations (REQ_OP_ZONE_APPEND) is not enabled and instead dm-crypt
> relies on the emulation done by the block layer using regular write
> operations. This still requires to properly return the written sector as
> the BIO sector of the original BIO. However, this can be done correctly
> only and only if there is a single clone BIO used for processing the
> original zone append operation issued by the user. If the size of a zone
> append operation is larger than dm-crypt max_write_size, then the
> orginal BIO will be split and processed as a chain of regular write
> operations. Such chaining result in an incorrect written sector being
> returned to the zone append issuer using the original BIO sector.
> This in turn results in file system data corruptions using xfs or btrfs.
>
> Fix this by modifying crypt_io_hints() to cap the max_hw_sectors limit
> for the dm-crypt device to the max_write_size limit. As this limit also
> caps the device max_zone_append_sectors limit, this forces the caller to
> issue zone append operations smaller than this limit, thus moving the
> splitting of large append operations to the caller instead of the
> incorrect internal splitting.
>
> This change does not have any effect on the size of BIOs received by
> dm-crypt since the block layer does not automatically splits BIOs for
> BIO-based devices. So there is no impact on the performance of regular
> read and write operations.
>
> Fixes: f211268ed1f9 ("dm: Use the block layer zone append emulation")
> Cc: [email protected]
> Signed-off-by: Damien Le Moal <[email protected]>
> ---
> drivers/md/dm-crypt.c | 12 ++++++++++++
> 1 file changed, 12 insertions(+)
>
> diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
> index 9dfdb63220d7..7b1e88781a82 100644
> --- a/drivers/md/dm-crypt.c
> +++ b/drivers/md/dm-crypt.c
> @@ -3730,6 +3730,18 @@ static void crypt_io_hints(struct dm_target *ti,
> struct queue_limits *limits)
> max_t(unsigned int, limits->physical_block_size,
> cc->sector_size);
> limits->io_min = max_t(unsigned int, limits->io_min, cc->sector_size);
> limits->dma_alignment = limits->logical_block_size - 1;
> +
> + /*
> + * For zoned devices, we cannot split write operations used to emulate
> + * zone append operations. And since all write requests are going to be
> + * split on get_max_request_size(cc, true) size, apply this limit to the
> + * maximum hardware I/O size so that we have a cap on the
> + * max_zone_append_sectors limit when the zone limits are validated by
> + * the block layer.
> + */
> + if (ti->emulate_zone_append)
> + limits->max_hw_sectors = min(limits->max_hw_sectors,
> + get_max_request_size(cc, true));
> }
>
> static struct target_type crypt_target = {
> --
> 2.49.0
>
