Re: [PATCH v7 10/11] scsi: scsi_debug: Map the region written by WRITE ATOMIC (16)

[John Garry <john.garry@linux.dev>]

On 9/25/26 08:17, Niklas Cassel wrote:
> When logical block provisioning is enabled, every command that writes
> user data calls map_region() so that GET LBA STATUS reports the region
> as mapped. resp_atomic_write() does not, so GET LBA STATUS keeps
> reporting a region as deallocated after a WRITE ATOMIC (16) has written
> it.
> 
> Call map_region() the way resp_write_dt0() does, holding the zone
> metadata write lock across the access. That lock is what serialises the
> map against resp_unmap(), which does nothing unless logical block
> provisioning is enabled.
> 
> Assisted-by: LLM
> Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
> Fixes: 84f3a3c01d70 ("scsi: scsi_debug: Atomic write support")
> Signed-off-by: Niklas Cassel <cassel@kernel.org>

Reviewed-by: John Garry <john.garry@linux.dev>

> ---
> Tested with:
> 
>    modprobe scsi_debug sector_size=512 physblk_exp=3 dev_size_mb=128 \
>        atomic_wr=1 lbpu=1
> 
> GET LBA STATUS reports a region that has never been written as
> deallocated, and reports it as mapped after a WRITE ATOMIC (16) of eight
> blocks. Only an ordinary WRITE did so before this patch.
> ---
>   drivers/scsi/scsi_debug.c | 9 +++++++++
>   1 file changed, 9 insertions(+)
> 
> diff --git a/drivers/scsi/scsi_debug.c b/drivers/scsi/scsi_debug.c
> index c0bcf8155fc8..c407f4c5ac47 100644
> --- a/drivers/scsi/scsi_debug.c
> +++ b/drivers/scsi/scsi_debug.c
> @@ -6203,6 +6203,7 @@ static int resp_atomic_write(struct scsi_cmnd *scp,
>   	u8 *cmd = scp->cmnd;
>   	u16 boundary, len;
>   	u64 lba, lba_tmp;
> +	bool lbp = scsi_debug_lbp();
>   	int ret;
>   
>   	if (!scsi_debug_atomic_write()) {
> @@ -6251,7 +6252,15 @@ static int resp_atomic_write(struct scsi_cmnd *scp,
>   	if (scsi_bufflen(scp) < len * sdebug_sector_size)
>   		return DID_ERROR << 16;
>   
> +	if (lbp)
> +		sdeb_meta_write_lock(sip);
> +
>   	ret = do_device_access(sip, scp, 0, lba, len, 0, true, true);
> +	if (lbp) {
> +		map_region(sip, lba, len);
> +		sdeb_meta_write_unlock(sip);
> +	}
> +
>   	if (unlikely(ret == -1))
>   		return DID_ERROR << 16;
>   	if (unlikely(ret != len * sdebug_sector_size))