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authorBart Van Assche <bart.vanassche@sandisk.com>2016-11-02 10:09:51 -0600
committerJens Axboe <axboe@fb.com>2016-11-02 12:50:19 -0600
commit6a83e74d214a47a1371cd2e6a783264fcba7d428 (patch)
tree871df14894af953b8486575a2803f038c8f33c4a /block/Kconfig
parent9b7dd572cc439fa92e120290eb74d0295567c5a0 (diff)
downloadlinux-0-day-6a83e74d214a47a1371cd2e6a783264fcba7d428.tar.gz
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/Kconfig1
1 files changed, 1 insertions, 0 deletions
diff --git a/block/Kconfig b/block/Kconfig
index 6b0ad08..3a02444 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.