@@ -1643,7 +1643,7 @@ void blk_flush_plug(struct blk_plug *plug, bool from_schedule)
flush_plug_callbacks(plug, from_schedule);
if (!rq_list_empty(plug->mq_list))
blk_mq_flush_plug_list(plug, from_schedule);
- if (unlikely(!from_schedule && plug->cached_rq))
+ if (unlikely(!rq_list_empty(plug->cached_rq)))
blk_mq_free_plug_rqs(plug);
}
@@ -410,7 +410,10 @@ __blk_mq_alloc_requests_batch(struct blk_mq_alloc_data *data,
tag_mask &= ~(1UL << i);
rq = blk_mq_rq_ctx_init(data, tags, tag, alloc_time_ns);
rq_list_add(data->cached_rq, rq);
+ nr++;
}
+ /* caller already holds a reference, add for remainder */
+ percpu_ref_get_many(&data->q->q_usage_counter, nr - 1);
data->nr_tags -= nr;
return rq_list_pop(data->cached_rq);
@@ -630,10 +633,8 @@ void blk_mq_free_plug_rqs(struct blk_plug *plug)
{
struct request *rq;
- while ((rq = rq_list_pop(&plug->cached_rq)) != NULL) {
- percpu_ref_get(&rq->q->q_usage_counter);
+ while ((rq = rq_list_pop(&plug->cached_rq)) != NULL)
blk_mq_free_request(rq);
- }
}
static void req_bio_endio(struct request *rq, struct bio *bio,
Requests that were stored in the cache deliberately didn't hold an enter reference to the queue, instead we grabbed one every time we pulled a request out of there. That made for awkward logic on freeing the remainder of the cached list, if needed, where we had to artificially raise the queue usage count before each free. Grab references up front for cached plug requests. That's safer, and also more efficient. Fixes: 47c122e35d7e ("block: pre-allocate requests if plug is started and is a batch") Signed-off-by: Jens Axboe <axboe@kernel.dk> --- block/blk-core.c | 2 +- block/blk-mq.c | 7 ++++--- 2 files changed, 5 insertions(+), 4 deletions(-)