X-Git-Url: https://git.proxmox.com/?a=blobdiff_plain;f=block%2Fblk-merge.c;h=5a0cc8550fe6e6b74933c7598cb8d9f3fd8f8587;hb=bccd2117bd75d8845b462db2c83eb459958190f7;hp=f5dedd57dff6b40fb6e88faa532bb88a94fcde61;hpb=925cbd7ed4b073a2afc9915e241ab789b44a3f61;p=mirror_ubuntu-bionic-kernel.git

diff --git a/block/blk-merge.c b/block/blk-merge.c
index f5dedd57dff6..5a0cc8550fe6 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -27,7 +27,8 @@ static struct bio *blk_bio_discard_split(struct request_queue *q,
 	/* Zero-sector (unknown) and one-sector granularities are the same.  */
 	granularity = max(q->limits.discard_granularity >> 9, 1U);
 
-	max_discard_sectors = min(q->limits.max_discard_sectors, UINT_MAX >> 9);
+	max_discard_sectors = min(q->limits.max_discard_sectors,
+			bio_allowed_max_sectors(q));
 	max_discard_sectors -= max_discard_sectors % granularity;
 
 	if (unlikely(!max_discard_sectors)) {
@@ -551,6 +552,24 @@ static bool req_no_special_merge(struct request *req)
 	return !q->mq_ops && req->special;
 }
 
+static bool req_attempt_discard_merge(struct request_queue *q, struct request *req,
+		struct request *next)
+{
+	unsigned short segments = blk_rq_nr_discard_segments(req);
+
+	if (segments >= queue_max_discard_segments(q))
+		goto no_merge;
+	if (blk_rq_sectors(req) + bio_sectors(next->bio) >
+	    blk_rq_get_max_sectors(req, blk_rq_pos(req)))
+		goto no_merge;
+
+	req->nr_phys_segments = segments + blk_rq_nr_discard_segments(next);
+	return true;
+no_merge:
+	req_set_nomerge(q, req);
+	return false;
+}
+
 static int ll_merge_requests_fn(struct request_queue *q, struct request *req,
 				struct request *next)
 {
@@ -641,6 +660,31 @@ static void blk_account_io_merge(struct request *req)
 		part_stat_unlock();
 	}
 }
+/*
+ * Two cases of handling DISCARD merge:
+ * If max_discard_segments > 1, the driver takes every bio
+ * as a range and send them to controller together. The ranges
+ * needn't to be contiguous.
+ * Otherwise, the bios/requests will be handled as same as
+ * others which should be contiguous.
+ */
+static inline bool blk_discard_mergable(struct request *req)
+{
+	if (req_op(req) == REQ_OP_DISCARD &&
+	    queue_max_discard_segments(req->q) > 1)
+		return true;
+	return false;
+}
+
+enum elv_merge blk_try_req_merge(struct request *req, struct request *next)
+{
+	if (blk_discard_mergable(req))
+		return ELEVATOR_DISCARD_MERGE;
+	else if (blk_rq_pos(req) + blk_rq_sectors(req) == blk_rq_pos(next))
+		return ELEVATOR_BACK_MERGE;
+
+	return ELEVATOR_NO_MERGE;
+}
 
 /*
  * For non-mq, this has to be called with the request spinlock acquired.
@@ -658,12 +702,6 @@ static struct request *attempt_merge(struct request_queue *q,
 	if (req_op(req) != req_op(next))
 		return NULL;
 
-	/*
-	 * not contiguous
-	 */
-	if (blk_rq_pos(req) + blk_rq_sectors(req) != blk_rq_pos(next))
-		return NULL;
-
 	if (rq_data_dir(req) != rq_data_dir(next)
 	    || req->rq_disk != next->rq_disk
 	    || req_no_special_merge(next))
@@ -684,10 +722,22 @@ static struct request *attempt_merge(struct request_queue *q,
 	 * If we are allowed to merge, then append bio list
 	 * from next to rq and release next. merge_requests_fn
 	 * will have updated segment counts, update sector
-	 * counts here.
+	 * counts here. Handle DISCARDs separately, as they
+	 * have separate settings.
 	 */
-	if (!ll_merge_requests_fn(q, req, next))
+
+	switch (blk_try_req_merge(req, next)) {
+	case ELEVATOR_DISCARD_MERGE:
+		if (!req_attempt_discard_merge(q, req, next))
+			return NULL;
+		break;
+	case ELEVATOR_BACK_MERGE:
+		if (!ll_merge_requests_fn(q, req, next))
+			return NULL;
+		break;
+	default:
 		return NULL;
+	}
 
 	/*
 	 * If failfast settings disagree or any of the two is already
@@ -716,7 +766,8 @@ static struct request *attempt_merge(struct request_queue *q,
 
 	req->__data_len += blk_rq_bytes(next);
 
-	elv_merge_requests(q, req, next);
+	if (!blk_discard_mergable(req))
+		elv_merge_requests(q, req, next);
 
 	/*
 	 * 'next' is going away, so update stats accordingly
@@ -811,8 +862,7 @@ bool blk_rq_merge_ok(struct request *rq, struct bio *bio)
 
 enum elv_merge blk_try_merge(struct request *rq, struct bio *bio)
 {
-	if (req_op(rq) == REQ_OP_DISCARD &&
-	    queue_max_discard_segments(rq->q) > 1)
+	if (blk_discard_mergable(rq))
 		return ELEVATOR_DISCARD_MERGE;
 	else if (blk_rq_pos(rq) + blk_rq_sectors(rq) == bio->bi_iter.bi_sector)
 		return ELEVATOR_BACK_MERGE;