block: move blk_print_req_error to blk-mq.c

This function is only used by the request completion path.  Factor out
a blk_status_to_str to keep blk_errors private in blk-core.c.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/20211117061404.331732-11-hch@lst.deSigned-off-by: Jens Axboe <axboe@kernel.dk>

block/blk-core.c

@@ -199,22 +199,13 @@ int blk_status_to_errno(blk_status_t status)
 }
 EXPORT_SYMBOL_GPL(blk_status_to_errno);
 
-void blk_print_req_error(struct request *req, blk_status_t status)
+const char *blk_status_to_str(blk_status_t status)
 {
 	int idx = (__force int)status;
 
 	if (WARN_ON_ONCE(idx >= ARRAY_SIZE(blk_errors)))
-		return;
-
-	printk_ratelimited(KERN_ERR
-		"%s error, dev %s, sector %llu op 0x%x:(%s) flags 0x%x "
-		"phys_seg %u prio class %u\n",
-		blk_errors[idx].name,
-		req->rq_disk ? req->rq_disk->disk_name : "?",
-		blk_rq_pos(req), req_op(req), blk_op_str(req_op(req)),
-		req->cmd_flags & ~REQ_OP_MASK,
-		req->nr_phys_segments,
-		IOPRIO_PRIO_CLASS(req->ioprio));
+		return "<null>";
+	return blk_errors[idx].name;
 }
 
 /**

block/blk-mq.c

@@ -717,6 +717,19 @@ static void blk_account_io_completion(struct request *req, unsigned int bytes)
 	}
 }
 
+static void blk_print_req_error(struct request *req, blk_status_t status)
+{
+	printk_ratelimited(KERN_ERR
+		"%s error, dev %s, sector %llu op 0x%x:(%s) flags 0x%x "
+		"phys_seg %u prio class %u\n",
+		blk_status_to_str(status),
+		req->rq_disk ? req->rq_disk->disk_name : "?",
+		blk_rq_pos(req), req_op(req), blk_op_str(req_op(req)),
+		req->cmd_flags & ~REQ_OP_MASK,
+		req->nr_phys_segments,
+		IOPRIO_PRIO_CLASS(req->ioprio));
+}
+
 /**
  * blk_update_request - Complete multiple bytes without completing the request
  * @req:      the request being processed

block/blk.h

@@ -250,7 +250,7 @@ static inline void blk_integrity_del(struct gendisk *disk)
 
 unsigned long blk_rq_timeout(unsigned long timeout);
 void blk_add_timer(struct request *req);
-void blk_print_req_error(struct request *req, blk_status_t status);
+const char *blk_status_to_str(blk_status_t status);
 
 bool blk_attempt_plug_merge(struct request_queue *q, struct bio *bio,
 		unsigned int nr_segs, bool *same_queue_rq);