scsi: core: scsi_logging: Fix a BUG

The request_queue may be NULL in a request, for example when it comes from
scsi_ioctl_reset(). Check it before use.

Fixes: f3fa33a ("block: remove the ->rq_disk field in struct request")
Link: https://lore.kernel.org/r/20220324134603.28463-1-thenzl@redhat.com
Reported-by: Changhui Zhong <czhong@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Tomas Henzl <thenzl@redhat.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/scsi_logging.c

@@ -30,7 +30,7 @@ static inline const char *scmd_name(const struct scsi_cmnd *scmd)
 {
 	struct request *rq = scsi_cmd_to_rq((struct scsi_cmnd *)scmd);
 
-	if (!rq->q->disk)
+	if (!rq->q || !rq->q->disk)
 		return NULL;
 	return rq->q->disk->disk_name;
 }