[PATCH v15 10/19] scsi: core: Retry unaligned zoned writes

[Bart Van Assche <bvanassche@acm.org>]

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. The SCSI error handler will 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.

Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Cc: Martin K. Petersen <martin.petersen@oracle.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
 drivers/scsi/constants.c  |  1 +
 drivers/scsi/scsi_error.c | 17 +++++++++++++++++
 drivers/scsi/scsi_lib.c   |  1 +
 drivers/scsi/sd.c         |  6 ++++++
 include/scsi/scsi.h       |  1 +
 5 files changed, 26 insertions(+)

diff --git a/drivers/scsi/constants.c b/drivers/scsi/constants.c
index 340785536998..8ddb30741999 100644
--- a/drivers/scsi/constants.c
+++ b/drivers/scsi/constants.c
@@ -419,6 +419,7 @@ EXPORT_SYMBOL(scsi_hostbyte_string);
 
 #define scsi_mlreturn_name(result)	{ result, #result }
 static const struct value_name_pair scsi_mlreturn_arr[] = {
+	scsi_mlreturn_name(NEEDS_DELAYED_RETRY),
 	scsi_mlreturn_name(NEEDS_RETRY),
 	scsi_mlreturn_name(SUCCESS),
 	scsi_mlreturn_name(FAILED),
diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c
index 3a2643293abf..4e9a35866a0d 100644
--- a/drivers/scsi/scsi_error.c
+++ b/drivers/scsi/scsi_error.c
@@ -699,6 +699,23 @@ 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_cmd_retry_allowed(scmd)) {
+			SCSI_LOG_ERROR_RECOVERY(1,
+				sdev_printk(KERN_WARNING, 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 cf3864f72093..2e28a1aeedd0 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -1442,6 +1442,7 @@ 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 d52ea605ada8..7e71f9f42036 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -1276,6 +1276,12 @@ 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;
+	/*
+	 * Increase the number of allowed retries for zoned writes if zone
+	 * write locking is disabled.
+	 */
+	if (!rq->q->limits.use_zone_write_lock && blk_rq_is_seq_zoned_write(rq))
+		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 4498f845b112..5eb8b6e3f85a 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,