Most of the merging happens at bio level. There should not be much
merging happening at request level anymore. Furthermore if we backmerged
a request to the previous one, the chances to be able to merge the
result to even previous request are slim - that could succeed only if
requests were inserted in 2 1 3 order. Merging more requests in
elv_attempt_insert_merge() will be difficult to handle when we want to
pass requests to free back to the caller of
blk_mq_sched_try_insert_merge(). So just remove the possibility of
merging multiple requests in elv_attempt_insert_merge().
Signed-off-by: Jan Kara <jack@xxxxxxx>
---
block/elevator.c | 19 +++++--------------
1 file changed, 5 insertions(+), 14 deletions(-)
diff --git a/block/elevator.c b/block/elevator.c
index 440699c28119..098f4bd226f5 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -350,12 +350,11 @@ enum elv_merge elv_merge(struct request_queue *q, struct request **req,
* we can append 'rq' to an existing request, so we can throw 'rq' away
* afterwards.
*
- * Returns true if we merged, false otherwise
+ * Returns true if we merged, false otherwise.
*/
bool elv_attempt_insert_merge(struct request_queue *q, struct request *rq)
{
struct request *__rq;
- bool ret;
if (blk_queue_nomerges(q))
return false;
@@ -369,21 +368,13 @@ bool elv_attempt_insert_merge(struct request_queue *q, struct request *rq)
if (blk_queue_noxmerges(q))
return false;
- ret = false;
/*
* See if our hash lookup can find a potential backmerge.
*/
- while (1) {
- __rq = elv_rqhash_find(q, blk_rq_pos(rq));
- if (!__rq || !blk_attempt_req_merge(q, __rq, rq))
- break;
-
- /* The merged request could be merged with others, try again */
- ret = true;
- rq = __rq;
- }
-
- return ret;
+ __rq = elv_rqhash_find(q, blk_rq_pos(rq));
+ if (!__rq || !blk_attempt_req_merge(q, __rq, rq))
+ return false;
+ return true;
}
void elv_merged_request(struct request_queue *q, struct request *rq,
--
2.26.2
