kernel_optimize_test/block
Tejun Heo 852c788f83 block: implement bio_associate_current()
IO scheduling and cgroup are tied to the issuing task via io_context
and cgroup of %current.  Unfortunately, there are cases where IOs need
to be routed via a different task which makes scheduling and cgroup
limit enforcement applied completely incorrectly.

For example, all bios delayed by blk-throttle end up being issued by a
delayed work item and get assigned the io_context of the worker task
which happens to serve the work item and dumped to the default block
cgroup.  This is double confusing as bios which aren't delayed end up
in the correct cgroup and makes using blk-throttle and cfq propio
together impossible.

Any code which punts IO issuing to another task is affected which is
getting more and more common (e.g. btrfs).  As both io_context and
cgroup are firmly tied to task including userland visible APIs to
manipulate them, it makes a lot of sense to match up tasks to bios.

This patch implements bio_associate_current() which associates the
specified bio with %current.  The bio will record the associated ioc
and blkcg at that point and block layer will use the recorded ones
regardless of which task actually ends up issuing the bio.  bio
release puts the associated ioc and blkcg.

It grabs and remembers ioc and blkcg instead of the task itself
because task may already be dead by the time the bio is issued making
ioc and blkcg inaccessible and those are all block layer cares about.

elevator_set_req_fn() is updated such that the bio elvdata is being
allocated for is available to the elevator.

This doesn't update block cgroup policies yet.  Further patches will
implement the support.

-v2: #ifdef CONFIG_BLK_CGROUP added around bio->bi_ioc dereference in
     rq_ioc() to fix build breakage.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Kent Overstreet <koverstreet@google.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2012-03-06 21:27:24 +01:00
..
partitions separate partition format handling from generic code 2012-01-03 22:54:06 -05:00
blk-cgroup.c blkcg: drop unnecessary RCU locking 2012-03-06 21:27:24 +01:00
blk-cgroup.h blkcg: drop unnecessary RCU locking 2012-03-06 21:27:24 +01:00
blk-core.c block: implement bio_associate_current() 2012-03-06 21:27:24 +01:00
blk-exec.c block: add missing blk_queue_dead() checks 2011-12-14 00:33:37 +01:00
blk-flush.c blk-flush: move the queue kick into 2011-10-24 16:24:31 +02:00
blk-integrity.c block: add export.h to files using EXPORT_SYMBOL/THIS_MODULE macros 2011-10-31 19:31:12 -04:00
blk-ioc.c block: add io_context->active_ref 2012-03-06 21:27:24 +01:00
blk-iopoll.c tree-wide: fix assorted typos all over the place 2009-12-04 15:39:55 +01:00
blk-lib.c block: fix patch import error in max_discard_sectors check 2011-07-23 20:34:59 +02:00
blk-map.c block: re-use existing 'reading' variable instead of checking direction again 2011-12-21 15:27:24 +01:00
blk-merge.c block: separate out blk_rq_merge_ok() and blk_try_merge() from elevator functions 2012-02-08 09:19:38 +01:00
blk-settings.c block: Introduce blk_set_stacking_limits function 2012-01-11 16:27:11 +01:00
blk-softirq.c block: Don't check QUEUE_FLAG_SAME_COMP in __blk_complete_request 2011-09-14 09:31:01 +02:00
blk-sysfs.c blkcg: unify blkg's for blkcg policies 2012-03-06 21:27:23 +01:00
blk-tag.c block: fix blk_queue_end_tag() 2011-12-29 09:16:28 +01:00
blk-throttle.c blkcg: drop unnecessary RCU locking 2012-03-06 21:27:24 +01:00
blk-timeout.c fault-injection: add ability to export fault_attr in arbitrary directory 2011-08-03 14:25:20 -10:00
blk.h block: interface update for ioc/icq creation functions 2012-03-06 21:27:24 +01:00
bsg-lib.c block: Change module.h -> export.h in bsg-lib.c 2011-10-31 19:31:13 -04:00
bsg.c bsg: fix sysfs link remove warning 2012-02-08 20:02:03 +01:00
cfq-iosched.c block: implement bio_associate_current() 2012-03-06 21:27:24 +01:00
cfq.h blkcg: use double locking instead of RCU for blkg synchronization 2012-03-06 21:27:24 +01:00
compat_ioctl.c block: Add BLKROTATIONAL ioctl 2012-01-11 16:29:31 +01:00
deadline-iosched.c elevator: make elevator_init_fn() return 0/-errno 2012-03-06 21:27:21 +01:00
elevator.c block: implement bio_associate_current() 2012-03-06 21:27:24 +01:00
genhd.c Block: use a freezable workqueue for disk-event polling 2012-03-02 10:51:00 +01:00
ioctl.c Merge branch 'for-3.3/core' of git://git.kernel.dk/linux-block 2012-01-15 12:24:45 -08:00
Kconfig move fs/partitions to block/ 2012-01-03 22:54:06 -05:00
Kconfig.iosched blkcg: make CONFIG_BLK_CGROUP bool 2012-03-06 21:27:21 +01:00
Makefile separate partition format handling from generic code 2012-01-03 22:54:06 -05:00
noop-iosched.c elevator: make elevator_init_fn() return 0/-errno 2012-03-06 21:27:21 +01:00
partition-generic.c block: Fix NULL pointer dereference in sd_revalidate_disk 2012-03-02 10:38:33 +01:00
scsi_ioctl.c block: fail SCSI passthrough ioctls on partition devices 2012-01-14 15:07:24 -08:00