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| author | Bart Van Assche <bart.vanassche@sandisk.com> | 2016-11-02 19:09:51 +0300 |
|---|---|---|
| committer | Jens Axboe <axboe@fb.com> | 2016-11-02 21:50:19 +0300 |
| commit | 6a83e74d214a47a1371cd2e6a783264fcba7d428 (patch) | |
| tree | 871df14894af953b8486575a2803f038c8f33c4a /include/linux/blkdev.h | |
| parent | 9b7dd572cc439fa92e120290eb74d0295567c5a0 (diff) | |
| download | linux-6a83e74d214a47a1371cd2e6a783264fcba7d428.tar.xz | |
blk-mq: Introduce blk_mq_quiesce_queue()
blk_mq_quiesce_queue() waits until ongoing .queue_rq() invocations
have finished. This function does *not* wait until all outstanding
requests have finished (this means invocation of request.end_io()).
The algorithm used by blk_mq_quiesce_queue() is as follows:
* Hold either an RCU read lock or an SRCU read lock around
.queue_rq() calls. The former is used if .queue_rq() does not
block and the latter if .queue_rq() may block.
* blk_mq_quiesce_queue() first calls blk_mq_stop_hw_queues()
followed by synchronize_srcu() or synchronize_rcu(). The latter
call waits for .queue_rq() invocations that started before
blk_mq_quiesce_queue() was called.
* The blk_mq_hctx_stopped() calls that control whether or not
.queue_rq() will be called are called with the (S)RCU read lock
held. This is necessary to avoid race conditions against
blk_mq_quiesce_queue().
Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Ming Lei <tom.leiming@gmail.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
Diffstat (limited to 'include/linux/blkdev.h')
| -rw-r--r-- | include/linux/blkdev.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index 8396da2bb698..13d893a69b46 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -918,6 +918,7 @@ extern void __blk_run_queue(struct request_queue *q); extern void __blk_run_queue_uncond(struct request_queue *q); extern void blk_run_queue(struct request_queue *); extern void blk_run_queue_async(struct request_queue *q); +extern void blk_mq_quiesce_queue(struct request_queue *q); extern int blk_rq_map_user(struct request_queue *, struct request *, struct rq_map_data *, void __user *, unsigned long, gfp_t); |