Tejun Heo add703fda9 blk-mq: use percpu_ref for mq usage count ... Currently, blk-mq uses a percpu_counter to keep track of how many usages are in flight. The percpu_counter is drained while freezing to ensure that no usage is left in-flight after freezing is complete. blk_mq_queue_enter/exit() and blk_mq_[un]freeze_queue() implement this per-cpu gating mechanism. This type of code has relatively high chance of subtle bugs which are extremely difficult to trigger and it's way too hairy to be open coded in blk-mq. percpu_ref can serve the same purpose after the recent changes. This patch replaces the open-coded per-cpu usage counting and draining mechanism with percpu_ref. blk_mq_queue_enter() performs tryget_live on the ref and exit() performs put. blk_mq_freeze_queue() kills the ref and waits until the reference count reaches zero. blk_mq_unfreeze_queue() revives the ref and wakes up the waiters. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: Nicholas A. Bellinger <nab@linux-iscsi.org> Cc: Kent Overstreet <kmo@daterainc.com> Signed-off-by: Jens Axboe <axboe@fb.com>		2014-07-01 10:34:38 -06:00
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partitions	block: Use macros from compiler.h instead of __attribute__((...))	2014-02-18 12:20:01 -08:00
Kconfig	block: change config option name for cmdline partition parsing	2013-09-30 14:31:02 -07:00
Kconfig.iosched	blkcg: make CONFIG_BLK_CGROUP bool	2012-03-06 21:27:21 +01:00
Makefile	block: move mm/bounce.c to block/	2014-05-19 20:01:52 -06:00
bio-integrity.c	block: move bio.c and bio-integrity.c from fs/ to block/	2014-05-19 08:34:46 -06:00
bio.c	block: add support for limiting gaps in SG lists	2014-06-24 16:22:24 -06:00
blk-cgroup.c	Revert "block: add __init to blkcg_policy_register"	2014-06-22 16:34:11 -06:00
blk-cgroup.h	Revert "block: add __init to blkcg_policy_register"	2014-06-22 16:34:11 -06:00
blk-core.c	blk-mq: decouble blk-mq freezing from generic bypassing	2014-07-01 10:31:13 -06:00
blk-exec.c	block: blk-exec.c: Cleaning up local variable address returnd	2014-06-08 19:51:31 -06:00
blk-flush.c	block: remove elv_abort_queue and blk_abort_flushes	2014-06-11 15:31:21 -06:00
blk-integrity.c	bio-integrity: Convert to bvec_iter	2013-11-23 22:33:50 -08:00
blk-ioc.c	block: Substitute rcu_access_pointer() for rcu_dereference_raw()	2014-02-18 12:21:26 -08:00
blk-iopoll.c	Merge branch 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip into next	2014-06-03 12:57:53 -07:00
blk-lib.c	block/blk-lib.c: make __blkdev_issue_zeroout static	2014-05-26 17:39:09 -06:00
blk-map.c	block: remove struct request buffer member	2014-04-15 14:03:02 -06:00
blk-merge.c	block: add support for limiting gaps in SG lists	2014-06-24 16:22:24 -06:00
blk-mq-cpu.c	blk-mq: add file comments and update copyright notices	2014-05-28 10:15:41 -06:00
blk-mq-cpumap.c	blk-mq: add file comments and update copyright notices	2014-05-28 10:15:41 -06:00
blk-mq-sysfs.c	blk-mq: blk_mq_unregister_hctx() can be static	2014-05-30 10:31:13 -06:00
blk-mq-tag.c	blk-mq: bitmap tag: fix races in bt_get() function	2014-06-17 22:13:08 -07:00
blk-mq-tag.h	blk-mq: bitmap tag: fix races on shared ::wake_index fields	2014-06-17 22:12:35 -07:00
blk-mq.c	blk-mq: use percpu_ref for mq usage count	2014-07-01 10:34:38 -06:00
blk-mq.h	blk-mq: decouble blk-mq freezing from generic bypassing	2014-07-01 10:31:13 -06:00
blk-settings.c	block: ensure that bio_add_page() always accepts a page for an empty bio	2014-06-10 12:53:56 -06:00
blk-softirq.c	block: fix regression with block enabled tagging	2014-04-09 21:54:06 -06:00
blk-sysfs.c	block, blk-mq: draining can't be skipped even if bypass_depth was non-zero	2014-07-01 10:29:17 -06:00
blk-tag.c	block: Reserve only one queue tag for sync IO if only 3 tags are available	2013-06-28 21:32:27 +02:00
blk-throttle.c	Merge branch 'for-3.16' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup	2014-06-09 15:03:33 -07:00
blk-timeout.c	block: ensure that the timer is always added	2014-05-30 15:41:39 -06:00
blk.h	block: remove elv_abort_queue and blk_abort_flushes	2014-06-11 15:31:21 -06:00
bounce.c	mm: convert some level-less printks to pr_*	2014-06-06 16:08:18 -07:00
bsg-lib.c	bsg: Remove unused function bsg_goose_queue()	2012-12-06 14:33:02 +01:00
bsg.c	block: add blk_rq_set_block_pc()	2014-06-06 07:57:37 -06:00
cfq-iosched.c	Merge branch 'for-3.16' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup	2014-06-09 15:03:33 -07:00
cmdline-parser.c	block: remove unrelated header files and export symbol	2014-01-21 20:18:26 -08:00
compat_ioctl.c	kernel-wide: fix missing validations on __get/__put/__copy_to/__copy_from_user()	2013-09-11 15:58:18 -07:00
deadline-iosched.c	block: Stop abusing csd.list for fifo_time	2014-02-24 14:46:32 -08:00
elevator.c	Revert "block: add __init to elv_register"	2014-06-22 16:34:11 -06:00
genhd.c	block: Convert kmalloc_node(...GFP_ZERO...) to kzalloc_node(...)	2013-09-11 13:22:03 -06:00
ioctl.c	block: replace IS_ERR and PTR_ERR with PTR_ERR_OR_ZERO	2013-11-08 09:05:31 -07:00
ioprio.c	block: move ioprio.c from fs/ to block/	2014-05-19 11:02:18 -06:00
noop-iosched.c	elevator: Fix a race in elevator switching	2013-07-03 13:25:24 +02:00
partition-generic.c	Revert "loop: cleanup partitions when detaching loop device"	2013-04-08 10:12:11 +02:00
scsi_ioctl.c	block: add blk_rq_set_block_pc()	2014-06-06 07:57:37 -06:00