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-rw-r--r--block/blk-merge.c29
1 files changed, 26 insertions, 3 deletions
diff --git a/block/blk-merge.c b/block/blk-merge.c
index 8452fc7164cc..782940c65d8a 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -550,6 +550,24 @@ 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)
{
@@ -683,9 +701,13 @@ 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))
+ if (req_op(req) == REQ_OP_DISCARD) {
+ if (!req_attempt_discard_merge(q, req, next))
+ return NULL;
+ } else if (!ll_merge_requests_fn(q, req, next))
return NULL;
/*
@@ -715,7 +737,8 @@ static struct request *attempt_merge(struct request_queue *q,
req->__data_len += blk_rq_bytes(next);
- elv_merge_requests(q, req, next);
+ if (req_op(req) != REQ_OP_DISCARD)
+ elv_merge_requests(q, req, next);
/*
* 'next' is going away, so update stats accordingly

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