We will try to get request from cache before alloc request, in
both cases will first attempt bio merge.
This patch move this common part to blk_mq_submit_bio(), which
simplify the code and avoid passing in the pointer of bio.
Signed-off-by: Chengming Zhou <[email protected]>
---
block/blk-mq.c | 32 ++++++++++++--------------------
1 file changed, 12 insertions(+), 20 deletions(-)
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 5ee62b95f3e5..aa091615e20b 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -2716,8 +2716,7 @@ static bool blk_mq_attempt_bio_merge(struct request_queue *q,
static struct request *blk_mq_get_new_requests(struct request_queue *q,
struct blk_plug *plug,
- struct bio *bio,
- unsigned int nsegs)
+ struct bio *bio)
{
struct blk_mq_alloc_data data = {
.q = q,
@@ -2729,9 +2728,6 @@ static struct request *blk_mq_get_new_requests(struct request_queue *q,
if (unlikely(bio_queue_enter(bio)))
return NULL;
- if (blk_mq_attempt_bio_merge(q, bio, nsegs))
- goto queue_exit;
-
rq_qos_throttle(q, bio);
if (plug) {
@@ -2746,13 +2742,13 @@ static struct request *blk_mq_get_new_requests(struct request_queue *q,
rq_qos_cleanup(q, bio);
if (bio->bi_opf & REQ_NOWAIT)
bio_wouldblock_error(bio);
-queue_exit:
+
blk_queue_exit(q);
return NULL;
}
static inline struct request *blk_mq_get_cached_request(struct request_queue *q,
- struct blk_plug *plug, struct bio **bio, unsigned int nsegs)
+ struct blk_plug *plug, struct bio *bio)
{
struct request *rq;
@@ -2762,14 +2758,9 @@ static inline struct request *blk_mq_get_cached_request(struct request_queue *q,
if (!rq || rq->q != q)
return NULL;
- if (blk_mq_attempt_bio_merge(q, *bio, nsegs)) {
- *bio = NULL;
- return NULL;
- }
-
- if (blk_mq_get_hctx_type((*bio)->bi_opf) != rq->mq_hctx->type)
+ if (blk_mq_get_hctx_type(bio->bi_opf) != rq->mq_hctx->type)
return NULL;
- if (op_is_flush(rq->cmd_flags) != op_is_flush((*bio)->bi_opf))
+ if (op_is_flush(rq->cmd_flags) != op_is_flush(bio->bi_opf))
return NULL;
/*
@@ -2778,9 +2769,9 @@ static inline struct request *blk_mq_get_cached_request(struct request_queue *q,
* before we throttle.
*/
plug->cached_rq = rq_list_next(rq);
- rq_qos_throttle(q, *bio);
+ rq_qos_throttle(q, bio);
- rq->cmd_flags = (*bio)->bi_opf;
+ rq->cmd_flags = bio->bi_opf;
INIT_LIST_HEAD(&rq->queuelist);
return rq;
}
@@ -2824,11 +2815,12 @@ void blk_mq_submit_bio(struct bio *bio)
bio_set_ioprio(bio);
- rq = blk_mq_get_cached_request(q, plug, &bio, nr_segs);
+ if (blk_mq_attempt_bio_merge(q, bio, nr_segs))
+ return;
+
+ rq = blk_mq_get_cached_request(q, plug, bio);
if (!rq) {
- if (!bio)
- return;
- rq = blk_mq_get_new_requests(q, plug, bio, nr_segs);
+ rq = blk_mq_get_new_requests(q, plug, bio);
if (unlikely(!rq))
return;
}
--
2.36.1
On 8/12/22 2:39 AM, Chengming Zhou wrote:
> We will try to get request from cache before alloc request, in
> both cases will first attempt bio merge.
>
> This patch move this common part to blk_mq_submit_bio(), which
> simplify the code and avoid passing in the pointer of bio.
I don't think this will work. If we get a cached request, then we
know we have a reference to the queue. If you swap these around,
then that's no longer the case and we can have a use-after-free if
the queue goes away.
--
Jens Axboe
On 2022/8/12 20:40, Jens Axboe wrote:
> On 8/12/22 2:39 AM, Chengming Zhou wrote:
>> We will try to get request from cache before alloc request, in
>> both cases will first attempt bio merge.
>>
>> This patch move this common part to blk_mq_submit_bio(), which
>> simplify the code and avoid passing in the pointer of bio.
>
> I don't think this will work. If we get a cached request, then we
> know we have a reference to the queue. If you swap these around,
> then that's no longer the case and we can have a use-after-free if
> the queue goes away.
>
Sorry, thanks for your reply!