scsi: core: Support failing requests while recovering

The current behavior for SCSI commands submitted while error recovery is
ongoing is to retry command submission after error recovery has finished.
See also the scsi_host_in_recovery() check in scsi_host_queue_ready(). Add
support for failing SCSI commands while host recovery is in progress. This
functionality will be used to fix a deadlock in the UFS driver.

Cc: Christoph Hellwig <hch@lst.de>
Cc: Ming Lei <ming.lei@redhat.com>
Cc: John Garry <john.garry@huawei.com>
Cc: Mike Christie <michael.christie@oracle.com>
Cc: Hannes Reinecke <hare@suse.de>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Link: https://lore.kernel.org/r/20221018202958.1902564-4-bvanassche@acm.orgReviewed-by: Mike Christie <michael.christie@oracle.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/scsi_lib.c

@@ -1341,9 +1341,6 @@ static inline int scsi_host_queue_ready(struct request_queue *q,
 				   struct scsi_device *sdev,
 				   struct scsi_cmnd *cmd)
 {
-	if (scsi_host_in_recovery(shost))
-		return 0;
-
 	if (atomic_read(&shost->host_blocked) > 0) {
 		if (scsi_host_busy(shost) > 0)
 			goto starved;
@@ -1732,6 +1729,11 @@ static blk_status_t scsi_queue_rq(struct blk_mq_hw_ctx *hctx,
 	ret = BLK_STS_RESOURCE;
 	if (!scsi_target_queue_ready(shost, sdev))
 		goto out_put_budget;
+	if (unlikely(scsi_host_in_recovery(shost))) {
+		if (cmd->flags & SCMD_FAIL_IF_RECOVERING)
+			ret = BLK_STS_OFFLINE;
+		goto out_dec_target_busy;
+	}
 	if (!scsi_host_queue_ready(q, shost, sdev, cmd))
 		goto out_dec_target_busy;
 

include/scsi/scsi_cmnd.h

@@ -52,8 +52,9 @@ struct scsi_pointer {
 #define SCMD_TAGGED		(1 << 0)
 #define SCMD_INITIALIZED	(1 << 1)
 #define SCMD_LAST		(1 << 2)
+#define SCMD_FAIL_IF_RECOVERING	(1 << 4)
 /* flags preserved across unprep / reprep */
-#define SCMD_PRESERVED_FLAGS	(SCMD_INITIALIZED)
+#define SCMD_PRESERVED_FLAGS	(SCMD_INITIALIZED | SCMD_FAIL_IF_RECOVERING)
 
 /* for scmd->state */
 #define SCMD_STATE_COMPLETE	0