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blk-mq: enable IO poll if .nr_queues of type poll > 0

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The queue mapping of type poll only exists when set->map[HCTX_TYPE_POLL].nr_queues
is bigger than zero, so enhance the constraint by checking .nr_queues of type poll
before enabling IO poll.

Otherwise IO race & timeout can be observed when running block/007.

Cc: Jeff Moyer <jmoyer@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Ming Lei 2018-12-18 12:15:29 +08:00 committed by Jens Axboe
parent 3c94d83cb3
commit cd19181bf9
2 changed files with 4 additions and 2 deletions
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3
block/blk-mq.c
View File

@ -2833,7 +2833,8 @@ struct request_queue *blk_mq_init_allocated_queue(struct blk_mq_tag_set *set,
q->tag_set = set;
q->queue_flags |= QUEUE_FLAG_MQ_DEFAULT;
if (set->nr_maps > HCTX_TYPE_POLL)
if (set->nr_maps > HCTX_TYPE_POLL &&
set->map[HCTX_TYPE_POLL].nr_queues)
blk_queue_flag_set(QUEUE_FLAG_POLL, q);
if (!(set->flags & BLK_MQ_F_SG_MERGE))

3
block/blk-sysfs.c
View File

@ -402,7 +402,8 @@ static ssize_t queue_poll_store(struct request_queue *q, const char *page,
unsigned long poll_on;
ssize_t ret;
if (!q->tag_set || q->tag_set->nr_maps <= HCTX_TYPE_POLL)
if (!q->tag_set || q->tag_set->nr_maps <= HCTX_TYPE_POLL ||
!q->tag_set->map[HCTX_TYPE_POLL].nr_queues)
return -EINVAL;
ret = queue_var_store(&poll_on, page, count);