scsi: core: Return BLK_STS_AGAIN for ALUA transitioning

Whenever we encounter a sense code of ALUA transitioning in
scsi_io_completion() it means that the SCSI midlayer ran out of retries
trying to wait for ALUA transitioning.  In these cases we should be passing
up the error, but signalling that the I/O might be retried, preferably on
another path.  So return BLK_STS_AGAIN in these cases.

[mkp: typo + fallthrough]

Link: https://lore.kernel.org/r/20200930080256.90964-5-hare@suse.de
Reviewed-by: Ewan D. Milne <emilne@redhat.com>
Signed-off-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/scsi_lib.c

@@ -766,6 +766,9 @@ static void scsi_io_completion_action(struct scsi_cmnd *cmd, int result)
 				case 0x24: /* depopulation in progress */
 					action = ACTION_DELAYED_RETRY;
 					break;
+				case 0x0a: /* ALUA state transition */
+					blk_stat = BLK_STS_AGAIN;
+					fallthrough;
 				default:
 					action = ACTION_FAIL;
 					break;