block: Remove BLK_STS_ZONE_RESOURCE

The zone append emulation of the scsi disk driver was the only driver
using BLK_STS_ZONE_RESOURCE. With this code removed,
BLK_STS_ZONE_RESOURCE is now unused. Remove this macro definition and
simplify blk_mq_dispatch_rq_list() where this status code was handled.

Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Tested-by: Hans Holmberg <hans.holmberg@wdc.com>
Tested-by: Dennis Maisenbacher <dennis.maisenbacher@wdc.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Link: https://lore.kernel.org/r/20240408014128.205141-20-dlemoal@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Author: damien-lemoal

block/blk-mq.c

@@ -1921,19 +1921,6 @@ static void blk_mq_handle_dev_resource(struct request *rq,
 	__blk_mq_requeue_request(rq);
 }
 
-static void blk_mq_handle_zone_resource(struct request *rq,
-					struct list_head *zone_list)
-{
-	/*
-	 * If we end up here it is because we cannot dispatch a request to a
-	 * specific zone due to LLD level zone-write locking or other zone
-	 * related resource not being available. In this case, set the request
-	 * aside in zone_list for retrying it later.
-	 */
-	list_add(&rq->queuelist, zone_list);
-	__blk_mq_requeue_request(rq);
-}
-
 enum prep_dispatch {
 	PREP_DISPATCH_OK,
 	PREP_DISPATCH_NO_TAG,
@@ -2019,7 +2006,6 @@ bool blk_mq_dispatch_rq_list(struct blk_mq_hw_ctx *hctx, struct list_head *list,
 	struct request *rq;
 	int queued;
 	blk_status_t ret = BLK_STS_OK;
-	LIST_HEAD(zone_list);
 	bool needs_resource = false;
 
 	if (list_empty(list))
@@ -2061,23 +2047,11 @@ bool blk_mq_dispatch_rq_list(struct blk_mq_hw_ctx *hctx, struct list_head *list,
 		case BLK_STS_DEV_RESOURCE:
 			blk_mq_handle_dev_resource(rq, list);
 			goto out;
-		case BLK_STS_ZONE_RESOURCE:
-			/*
-			 * Move the request to zone_list and keep going through
-			 * the dispatch list to find more requests the drive can
-			 * accept.
-			 */
-			blk_mq_handle_zone_resource(rq, &zone_list);
-			needs_resource = true;
-			break;
 		default:
 			blk_mq_end_request(rq, ret);
 		}
 	} while (!list_empty(list));
 out:
-	if (!list_empty(&zone_list))
-		list_splice_tail_init(&zone_list, list);
-
 	/* If we didn't flush the entire list, we could have told the driver
 	 * there was more coming, but that turned out to be a lie.
 	 */

drivers/scsi/scsi_lib.c

@@ -1870,7 +1870,6 @@ static blk_status_t scsi_queue_rq(struct blk_mq_hw_ctx *hctx,
 	case BLK_STS_OK:
 		break;
 	case BLK_STS_RESOURCE:
-	case BLK_STS_ZONE_RESOURCE:
 		if (scsi_device_blocked(sdev))
 			ret = BLK_STS_DEV_RESOURCE;
 		break;

include/linux/blk_types.h

@@ -136,26 +136,14 @@ typedef u16 blk_short_t;
  */
 #define BLK_STS_DEV_RESOURCE	((__force blk_status_t)13)
 
-/*
- * BLK_STS_ZONE_RESOURCE is returned from the driver to the block layer if zone
- * related resources are unavailable, but the driver can guarantee the queue
- * will be rerun in the future once the resources become available again.
- *
- * This is different from BLK_STS_DEV_RESOURCE in that it explicitly references
- * a zone specific resource and IO to a different zone on the same device could
- * still be served. Examples of that are zones that are write-locked, but a read
- * to the same zone could be served.
- */
-#define BLK_STS_ZONE_RESOURCE	((__force blk_status_t)14)
-
 /*
  * BLK_STS_ZONE_OPEN_RESOURCE is returned from the driver in the completion
  * path if the device returns a status indicating that too many zone resources
  * are currently open. The same command should be successful if resubmitted
  * after the number of open zones decreases below the device's limits, which is
  * reported in the request_queue's max_open_zones.
  */
-#define BLK_STS_ZONE_OPEN_RESOURCE	((__force blk_status_t)15)
+#define BLK_STS_ZONE_OPEN_RESOURCE	((__force blk_status_t)14)
 
 /*
  * BLK_STS_ZONE_ACTIVE_RESOURCE is returned from the driver in the completion
@@ -164,20 +152,20 @@ typedef u16 blk_short_t;
  * after the number of active zones decreases below the device's limits, which
  * is reported in the request_queue's max_active_zones.
  */
-#define BLK_STS_ZONE_ACTIVE_RESOURCE	((__force blk_status_t)16)
+#define BLK_STS_ZONE_ACTIVE_RESOURCE	((__force blk_status_t)15)
 
 /*
  * BLK_STS_OFFLINE is returned from the driver when the target device is offline
  * or is being taken offline. This could help differentiate the case where a
  * device is intentionally being shut down from a real I/O error.
  */
-#define BLK_STS_OFFLINE		((__force blk_status_t)17)
+#define BLK_STS_OFFLINE		((__force blk_status_t)16)
 
 /*
  * BLK_STS_DURATION_LIMIT is returned from the driver when the target device
  * aborted the command because it exceeded one of its Command Duration Limits.
  */
-#define BLK_STS_DURATION_LIMIT	((__force blk_status_t)18)
+#define BLK_STS_DURATION_LIMIT	((__force blk_status_t)17)
 
 /**
  * blk_path_error - returns true if error may be path related