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| author | Bart Van Assche <bart.vanassche@sandisk.com> | 2016-11-02 10:09:51 -0600 |
|---|---|---|
| committer | Jens Axboe <axboe@fb.com> | 2016-11-02 12:50:19 -0600 |
| commit | 6a83e74d214a47a1371cd2e6a783264fcba7d428 (patch) | |
| tree | 871df14894af953b8486575a2803f038c8f33c4a /block/Kconfig | |
| parent | 9b7dd572cc439fa92e120290eb74d0295567c5a0 (diff) | |
| download | lwn-6a83e74d214a47a1371cd2e6a783264fcba7d428.tar.gz lwn-6a83e74d214a47a1371cd2e6a783264fcba7d428.zip | |
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 'block/Kconfig')
| -rw-r--r-- | block/Kconfig | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/block/Kconfig b/block/Kconfig index 6b0ad08f0677..3a024440a669 100644 --- a/block/Kconfig +++ b/block/Kconfig @@ -5,6 +5,7 @@ menuconfig BLOCK bool "Enable the block layer" if EXPERT default y select SBITMAP + select SRCU help Provide block layer support for the kernel. |