block: move blk_rq_err_bytes to scsi

blk_rq_err_bytes is only used by the scsi midlayer, so move it there.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/20211117061404.331732-2-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 41 insertions, 1 deletions

diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 621d841d819a..5e8b5ecb3245 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -617,6 +617,46 @@ static blk_status_t scsi_result_to_blk_status(struct scsi_cmnd *cmd, int result)
 	}
 }
 
+/**
+ * scsi_rq_err_bytes - determine number of bytes till the next failure boundary
+ * @rq: request to examine
+ *
+ * Description:
+ *     A request could be merge of IOs which require different failure
+ *     handling.  This function determines the number of bytes which
+ *     can be failed from the beginning of the request without
+ *     crossing into area which need to be retried further.
+ *
+ * Return:
+ *     The number of bytes to fail.
+ */
+static unsigned int scsi_rq_err_bytes(const struct request *rq)
+{
+	unsigned int ff = rq->cmd_flags & REQ_FAILFAST_MASK;
+	unsigned int bytes = 0;
+	struct bio *bio;
+
+	if (!(rq->rq_flags & RQF_MIXED_MERGE))
+		return blk_rq_bytes(rq);
+
+	/*
+	 * Currently the only 'mixing' which can happen is between
+	 * different fastfail types.  We can safely fail portions
+	 * which have all the failfast bits that the first one has -
+	 * the ones which are at least as eager to fail as the first
+	 * one.
+	 */
+	for (bio = rq->bio; bio; bio = bio->bi_next) {
+		if ((bio->bi_opf & ff) != ff)
+			break;
+		bytes += bio->bi_iter.bi_size;
+	}
+
+	/* this could lead to infinite loop */
+	BUG_ON(blk_rq_bytes(rq) && !bytes);
+	return bytes;
+}
+
 /* Helper for scsi_io_completion() when "reprep" action required. */
 static void scsi_io_completion_reprep(struct scsi_cmnd *cmd,
 				      struct request_queue *q)
@@ -794,7 +834,7 @@ static void scsi_io_completion_action(struct scsi_cmnd *cmd, int result)
 				scsi_print_command(cmd);
 			}
 		}
-		if (!scsi_end_request(req, blk_stat, blk_rq_err_bytes(req)))
+		if (!scsi_end_request(req, blk_stat, scsi_rq_err_bytes(req)))
 			return;
 		fallthrough;
 	case ACTION_REPREP: