[v8,5/9] scsi: core: Retry unaligned zoned writes

If zoned writes (REQ_OP_WRITE) for a sequential write required zone have
a starting LBA that differs from the write pointer, e.g. because zoned
writes have been reordered, then the storage device will respond with an
UNALIGNED WRITE COMMAND error. Send commands that failed with an
unaligned write error to the SCSI error handler if zone write locking is
disabled. Let the SCSI error handler sort SCSI commands per LBA before
resubmitting these.

If zone write locking is disabled, increase the number of retries for
write commands sent to a sequential zone to the maximum number of
outstanding commands because in the worst case the number of times
reordered zoned writes have to be retried is (number of outstanding
writes per sequential zone) - 1.

Cc: Martin K. Petersen <martin.petersen@oracle.com>
Cc: Damien Le Moal <dlemoal@kernel.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
 drivers/scsi/scsi_error.c | 16 ++++++++++++++++
 drivers/scsi/scsi_lib.c   |  1 +
 drivers/scsi/sd.c         |  2 ++
 include/scsi/scsi.h       |  1 +
 4 files changed, 20 insertions(+)

On 8/12/23 06:35, Bart Van Assche wrote:
> If zoned writes (REQ_OP_WRITE) for a sequential write required zone have
> a starting LBA that differs from the write pointer, e.g. because zoned
> writes have been reordered, then the storage device will respond with an
> UNALIGNED WRITE COMMAND error. Send commands that failed with an
> unaligned write error to the SCSI error handler if zone write locking is
> disabled. Let the SCSI error handler sort SCSI commands per LBA before
> resubmitting these.
> 
> If zone write locking is disabled, increase the number of retries for
> write commands sent to a sequential zone to the maximum number of
> outstanding commands because in the worst case the number of times
> reordered zoned writes have to be retried is (number of outstanding
> writes per sequential zone) - 1.
> 
> Cc: Martin K. Petersen <martin.petersen@oracle.com>
> Cc: Damien Le Moal <dlemoal@kernel.org>
> Cc: Christoph Hellwig <hch@lst.de>
> Cc: Ming Lei <ming.lei@redhat.com>
> Signed-off-by: Bart Van Assche <bvanassche@acm.org>
> ---
>  drivers/scsi/scsi_error.c | 16 ++++++++++++++++
>  drivers/scsi/scsi_lib.c   |  1 +
>  drivers/scsi/sd.c         |  2 ++
>  include/scsi/scsi.h       |  1 +
>  4 files changed, 20 insertions(+)
> 
> diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c
> index 0d7835bdc8af..7ae43fac07b7 100644
> --- a/drivers/scsi/scsi_error.c
> +++ b/drivers/scsi/scsi_error.c
> @@ -699,6 +699,22 @@ enum scsi_disposition scsi_check_sense(struct scsi_cmnd *scmd)
>  		fallthrough;
>  
>  	case ILLEGAL_REQUEST:
> +		/*
> +		 * Unaligned write command. This may indicate that zoned writes
> +		 * have been received by the device in the wrong order. If zone
> +		 * write locking is disabled, retry after all pending commands
> +		 * have completed.
> +		 */
> +		if (sshdr.asc == 0x21 && sshdr.ascq == 0x04 &&
> +		    !req->q->limits.use_zone_write_lock &&
> +		    blk_rq_is_seq_zoned_write(req)) {
> +			SCSI_LOG_ERROR_RECOVERY(3,
> +				sdev_printk(KERN_INFO, scmd->device,
> +					    "Retrying unaligned write at LBA %#llx.\n",
> +					    scsi_get_lba(scmd)));
> +			return NEEDS_DELAYED_RETRY;
> +		}
> +
>  		if (sshdr.asc == 0x20 || /* Invalid command operation code */
>  		    sshdr.asc == 0x21 || /* Logical block address out of range */
>  		    sshdr.asc == 0x22 || /* Invalid function */
> diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
> index 59176946ab56..69da8aee13df 100644
> --- a/drivers/scsi/scsi_lib.c
> +++ b/drivers/scsi/scsi_lib.c
> @@ -1443,6 +1443,7 @@ static void scsi_complete(struct request *rq)
>  	case ADD_TO_MLQUEUE:
>  		scsi_queue_insert(cmd, SCSI_MLQUEUE_DEVICE_BUSY);
>  		break;
> +	case NEEDS_DELAYED_RETRY:
>  	default:
>  		scsi_eh_scmd_add(cmd);
>  		break;
> diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
> index 4d9c6ad11cca..c8466c6c7387 100644
> --- a/drivers/scsi/sd.c
> +++ b/drivers/scsi/sd.c
> @@ -1238,6 +1238,8 @@ static blk_status_t sd_setup_read_write_cmnd(struct scsi_cmnd *cmd)
>  	cmd->transfersize = sdp->sector_size;
>  	cmd->underflow = nr_blocks << 9;
>  	cmd->allowed = sdkp->max_retries;
> +	if (!rq->q->limits.use_zone_write_lock && blk_rq_is_seq_zoned_write(rq))

This condition could be written as a little inline helper
blk_req_need_zone_write_lock(), which could be used in mq-dealine patch 2.

> +		cmd->allowed += rq->q->nr_requests;
>  	cmd->sdb.length = nr_blocks * sdp->sector_size;
>  
>  	SCSI_LOG_HLQUEUE(1,
> diff --git a/include/scsi/scsi.h b/include/scsi/scsi.h
> index ec093594ba53..6600db046227 100644
> --- a/include/scsi/scsi.h
> +++ b/include/scsi/scsi.h
> @@ -93,6 +93,7 @@ static inline int scsi_status_is_check_condition(int status)
>   * Internal return values.
>   */
>  enum scsi_disposition {
> +	NEEDS_DELAYED_RETRY	= 0x2000,
>  	NEEDS_RETRY		= 0x2001,
>  	SUCCESS			= 0x2002,
>  	FAILED			= 0x2003,

On 8/15/23 18:13, Damien Le Moal wrote:
> I still think that added the test for use_zone_write_lock in
> blk_req_needs_zone_write_lock() is needed though, for consistency of all
> functions related to zone locking.

This has been implemented in v9 of this patch series. v9 has just been 
posted.

Thanks,

Bart.