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288 commits

Author SHA1 Message Date
Yu Kuai
eead005664 blk-throttle: consider 'carryover_ios/bytes' in throtl_trim_slice()
Currently, 'carryover_ios/bytes' is not handled in throtl_trim_slice(),
for consequence, 'carryover_ios/bytes' will be used to throttle bio
multiple times, for example:

1) set iops limit to 100, and slice start is 0, slice end is 100ms;
2) current time is 0, and 10 ios are dispatched, those io won't be
   throttled and io_disp is 10;
3) still at current time 0, update iops limit to 1000, carryover_ios is
   updated to (0 - 10) = -10;
4) in this slice(0 - 100ms), io_allowed = 100 + (-10) = 90, which means
   only 90 ios can be dispatched without waiting;
5) assume that io is throttled in slice(0 - 100ms), and
   throtl_trim_slice() update silce to (100ms - 200ms). In this case,
   'carryover_ios/bytes' is not cleared and still only 90 ios can be
   dispatched between 100ms - 200ms.

Fix this problem by updating 'carryover_ios/bytes' in
throtl_trim_slice().

Fixes: a880ae93e5 ("blk-throttle: fix io hung due to configuration updates")
Reported-by: zhuxiaohui <zhuxiaohui.400@bytedance.com>
Link: https://lore.kernel.org/all/20230812072116.42321-1-zhuxiaohui.400@bytedance.com/
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20230816012708.1193747-5-yukuai1@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2023-08-30 10:15:01 -06:00
Yu Kuai
e8368b57c0 blk-throttle: use calculate_io/bytes_allowed() for throtl_trim_slice()
There are no functional changes, just make the code cleaner.

Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20230816012708.1193747-4-yukuai1@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2023-08-30 10:15:01 -06:00
Yu Kuai
bb8d5587bd blk-throttle: fix wrong comparation while 'carryover_ios/bytes' is negative
carryover_ios/bytes[] can be negative in the case that ios are
dispatched in the slice in advance, and then configuration is updated.
For example:

1) set iops limit to 1000, and slice start is 0, slice end is 100ms;
2) current time is 0, and 100 ios are dispatched, those ios will not be
   throttled, hence io_disp is 100;
3) still at current time 0, update iops limit to 100, then carryover_ios
   is (0 - 100) = -100;
4) then, dispatch a new io at time 0, the expected result is that this
   io will wait for 1s. The calculation in tg_within_iops_limit:

   io_disp = 0;
   io_allowed = calculate_io_allowed + carryover_ios
	      = 10 + (-100) = -90;
   io won't be throttled if (io_disp + 1 < io_allowed) passed.

Before this patch, in step 4) (io_disp + 1 < io_allowed) is passed,
because -90 for unsigned value is very huge, and such io won't be
throttled.

Fix this problem by checking if 'io/bytes_allowed' is negative first.

Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20230816012708.1193747-3-yukuai1@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2023-08-30 10:15:01 -06:00
Yu Kuai
ef100397fa blk-throttle: print signed value 'carryover_bytes/ios' for user
'carryover_bytes/ios' can be negative, indicate that some bio is
dispatched in advance within slice while configuration is updated.
Print a huge value is not user-friendly.

Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20230816012708.1193747-2-yukuai1@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2023-08-30 10:15:01 -06:00
Jinke Han
ad7c3b41e8 blk-throttle: Fix io statistics for cgroup v1
After commit f382fb0bce ("block: remove legacy IO schedulers"),
blkio.throttle.io_serviced and blkio.throttle.io_service_bytes become
the only stable io stats interface of cgroup v1, and these statistics
are done in the blk-throttle code. But the current code only counts the
bios that are actually throttled. When the user does not add the throttle
limit, the io stats for cgroup v1 has nothing. I fix it according to the
statistical method of v2, and made it count all ios accurately.

Fixes: a7b36ee6ba ("block: move blk-throtl fast path inline")
Tested-by: Andrea Righi <andrea.righi@canonical.com>
Signed-off-by: Jinke Han <hanjinke.666@bytedance.com>
Acked-by: Muchun Song <songmuchun@bytedance.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20230507170631.89607-1-hanjinke.666@bytedance.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2023-06-25 08:00:39 -06:00
Chengming Zhou
8e15dfbd9a blk-throttle: only enable blk-stat when BLK_DEV_THROTTLING_LOW
blk_throtl_register() will unconditionally enable blk-stat for gendisk
when register, even when we have no BLK_DEV_THROTTLING_LOW config.

Since the kernel always has only BLK_DEV_THROTTLING config and the
BLK_DEV_THROTTLING_LOW config is still in EXPERIMENTAL state, we can
just skip blk-stat when !BLK_DEV_THROTTLING_LOW.

Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20230413062805.2081970-2-chengming.zhou@linux.dev
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2023-04-13 06:48:11 -06:00
Tejun Heo
faffaab289 blkcg: Restructure blkg_conf_prep() and friends
We want to support lazy init of rq-qos policies so that iolatency is enabled
lazily on configuration instead of gendisk initialization. The way blkg
config helpers are structured now is a bit awkward for that. Let's
restructure:

* blkcg_conf_open_bdev() is renamed to blkg_conf_open_bdev(). The blkcg_
  prefix was used because the bdev opening step is blkg-independent.
  However, the distinction is too subtle and confuses more than helps. Let's
  switch to blkg prefix so that it's consistent with the type and other
  helper names.

* struct blkg_conf_ctx now remembers the original input string and is always
  initialized by the new blkg_conf_init().

* blkg_conf_open_bdev() is updated to take a pointer to blkg_conf_ctx like
  blkg_conf_prep() and can be called multiple times safely. Instead of
  modifying the double pointer to input string directly,
  blkg_conf_open_bdev() now sets blkg_conf_ctx->body.

* blkg_conf_finish() is renamed to blkg_conf_exit() for symmetry and now
  must be called on all blkg_conf_ctx's which were initialized with
  blkg_conf_init().

Combined, this allows the users to either open the bdev first or do it
altogether with blkg_conf_prep() which will help implementing lazy init of
rq-qos policies.

blkg_conf_init/exit() will also be used implement synchronization against
device removal. This is necessary because iolat / iocost are configured
through cgroupfs instead of one of the files under /sys/block/DEVICE. As
cgroupfs operations aren't synchronized with block layer, the lazy init and
other configuration operations may race against device removal. This patch
makes blkg_conf_init/exit() used consistently for all cgroup-orginating
configurations making them a good place to implement explicit
synchronization.

Users are updated accordingly. No behavior change is intended by this patch.

v2: bfq wasn't updated in v1 causing a build error. Fixed.

v3: Update the description to include future use of blkg_conf_init/exit() as
    synchronization points.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Josef Bacik <josef@toxicpanda.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Yu Kuai <yukuai1@huaweicloud.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20230413000649.115785-3-tj@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2023-04-13 06:46:49 -06:00
Christoph Hellwig
a06377c5d0 Revert "blk-cgroup: pin the gendisk in struct blkcg_gq"
This reverts commit 84d7d462b1.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20230214183308.1658775-6-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2023-02-14 14:24:09 -07:00
Christoph Hellwig
b4e94f9c2c Revert "blk-cgroup: delay calling blkcg_exit_disk until disk_release"
This reverts commit c43332fe02 as it is not
needed without moving to disk references in the blkg.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20230214183308.1658775-3-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2023-02-14 14:24:09 -07:00
Christoph Hellwig
1231039db3 Revert "blk-cgroup: move the cgroup information to struct gendisk"
This reverts commit 3f13ab7c80 as a patch
it depends on caused a few problems.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20230214183308.1658775-2-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2023-02-14 14:24:09 -07:00
Christoph Hellwig
c43332fe02 blk-cgroup: delay calling blkcg_exit_disk until disk_release
While del_gendisk ensures there is no outstanding I/O on the queue,
it can't prevent block layer users from building new I/O.

This leads to a NULL ->root_blkg reference in bio_associate_blkg when
allocating a new bio on a shut down file system.  Delay freeing the
blk-cgroup subsystems from del_gendisk until disk_release to make
sure the blkg and throttle information is still avaіlable for bio
submitters, even if those bios will immediately fail.

This now can cause a case where disk_release is called on a disk
that hasn't been added.  That's mostly harmless, except for a case
in blk_throttl_exit that now needs to check for a NULL ->td pointer.

Fixes: 178fa7d498 ("blk-cgroup: delay blk-cgroup initialization until add_disk")
Reported-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20230208063514.171485-1-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2023-02-09 08:10:45 -07:00
Christoph Hellwig
3f13ab7c80 blk-cgroup: move the cgroup information to struct gendisk
cgroup information only makes sense on a live gendisk that allows
file system I/O (which includes the raw block device).  So move over
the cgroup related members.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Andreas Herrmann <aherrmann@suse.de>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20230203150400.3199230-20-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2023-02-03 08:20:05 -07:00
Christoph Hellwig
0a0b4f79db blk-cgroup: pass a gendisk to pd_alloc_fn
No need to the request_queue here, pass a gendisk and extract the
node ids from that.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Andreas Herrmann <aherrmann@suse.de>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20230203150400.3199230-18-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2023-02-03 08:20:05 -07:00
Christoph Hellwig
40e4996ec0 blk-cgroup: pass a gendisk to blkcg_{de,}activate_policy
Prepare for storing the blkcg information in the gendisk instead of
the request_queue.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Andreas Herrmann <aherrmann@suse.de>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20230203150400.3199230-17-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2023-02-03 08:20:05 -07:00
Christoph Hellwig
84d7d462b1 blk-cgroup: pin the gendisk in struct blkcg_gq
Currently each blkcg_gq holds a request_queue reference, which is what
is used in the policies.  But a lot of these interfaces will move over to
use a gendisk, so store a disk in struct blkcg_gq and hold a reference to
it.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Andreas Herrmann <aherrmann@suse.de>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20230203150400.3199230-7-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2023-02-03 08:20:05 -07:00
Kemeng Shi
eea3e8b74a blk-throttle: Use more suitable time_after check for update of slice_start
There is no need to update tg->slice_start[rw] to start when they are
equal already. So remove "eq" part of check before update slice_start.

Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Kemeng Shi <shikemeng@huawei.com>
Link: https://lore.kernel.org/r/20221205115709.251489-10-shikemeng@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-12-05 13:45:31 -07:00
Kemeng Shi
9c9f209d9d blk-throttle: remove repeat check of elapsed time
There is no need to check elapsed time from last upgrade for each node in
hierarchy. Move this check before traversing as throtl_can_upgrade do
to remove repeat check.

Reported-by: kernel test robot <lkp@intel.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Kemeng Shi <shikemeng@huawei.com>
Link: https://lore.kernel.org/r/20221205115709.251489-9-shikemeng@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-12-05 13:45:11 -07:00
Kemeng Shi
e3031d4c7d blk-throttle: remove incorrect comment for tg_last_low_overflow_time
Function tg_last_low_overflow_time is called with intermediate node as
following:
throtl_hierarchy_can_downgrade
  throtl_tg_can_downgrade
    tg_last_low_overflow_time

throtl_hierarchy_can_upgrade
  throtl_tg_can_upgrade
    tg_last_low_overflow_time

throtl_hierarchy_can_downgrade/throtl_hierarchy_can_upgrade will traverse
from leaf node to sub-root node and pass traversed intermediate node
to tg_last_low_overflow_time.

No such limit could be found from context and implementation of
tg_last_low_overflow_time, so remove this limit in comment.

Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Kemeng Shi <shikemeng@huawei.com>
Link: https://lore.kernel.org/r/20221205115709.251489-8-shikemeng@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-12-05 13:45:05 -07:00
Kemeng Shi
009df34171 blk-throttle: fix typo in comment of throtl_adjusted_limit
lapsed time -> elapsed time

Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Kemeng Shi <shikemeng@huawei.com>
Link: https://lore.kernel.org/r/20221205115709.251489-7-shikemeng@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-12-05 13:44:59 -07:00
Kemeng Shi
a4d508e333 blk-throttle: simpfy low limit reached check in throtl_tg_can_upgrade
Commit c79892c557 ("blk-throttle: add upgrade logic for LIMIT_LOW
state") added upgrade logic for low limit and methioned that
1. "To determine if a cgroup exceeds its limitation, we check if the cgroup
has pending request. Since cgroup is throttled according to the limit,
pending request means the cgroup reaches the limit."
2. "If a cgroup has limit set for both read and write, we consider the
combination of them for upgrade. The reason is read IO and write IO can
interfere with each other. If we do the upgrade based in one direction IO,
the other direction IO could be severly harmed."
Besides, we also determine that cgroup reaches low limit if low limit is 0,
see comment in throtl_tg_can_upgrade.

Collect the information above, the desgin of upgrade check is as following:
1.The low limit is reached if limit is zero or io is already queued.
2.Cgroup will pass upgrade check if low limits of READ and WRITE are both
reached.

Simpfy the check code described above to removce repeat check and improve
readability. There is no functional change.

Detail equivalence proof is as following:
All replaced conditions to return true are as following:
condition 1
  (!read_limit && !write_limit)
condition 2
  read_limit && sq->nr_queued[READ] &&
  (!write_limit || sq->nr_queued[WRITE])
condition 3
  write_limit && sq->nr_queued[WRITE] &&
  (!read_limit || sq->nr_queued[READ])

Transferring condition 2 as following:
  (read_limit && sq->nr_queued[READ]) &&
  (!write_limit || sq->nr_queued[WRITE])
is equivalent to
  (read_limit && sq->nr_queued[READ]) &&
  (!write_limit || (write_limit && sq->nr_queued[WRITE]))
is equivalent to
condition 2.1
  (read_limit && sq->nr_queued[READ] &&
  !write_limit) ||
condition 2.2
  (read_limit && sq->nr_queued[READ] &&
  (write_limit && sq->nr_queued[WRITE]))

Transferring condition 3 as following:
  write_limit && sq->nr_queued[WRITE] &&
  (!read_limit || sq->nr_queued[READ])
is equivalent to
  (write_limit && sq->nr_queued[WRITE]) &&
  (!read_limit || (read_limit && sq->nr_queued[READ]))
is equivalent to
condition 3.1
  ((write_limit && sq->nr_queued[WRITE]) &&
  !read_limit) ||
condition 3.2
  ((write_limit && sq->nr_queued[WRITE]) &&
  (read_limit && sq->nr_queued[READ]))

Condition 3.2 is the same as condition 2.2, so all conditions we get to
return are as following:
  (!read_limit && !write_limit) (1)
  (!read_limit && (write_limit && sq->nr_queued[WRITE])) (3.1)
  ((read_limit && sq->nr_queued[READ]) && !write_limit) (2.1)
  ((write_limit && sq->nr_queued[WRITE]) &&
  (read_limit && sq->nr_queued[READ])) (2.2)

As we can extract conditions "(a1 || a2) && (b1 || b2)" to:
a1 && b1
a1 && b2
a2 && b1
ab && b2

Considering that:
a1 = !read_limit
a2 = read_limit && sq->nr_queued[READ]
b1 = !write_limit
b2 = write_limit && sq->nr_queued[WRITE]

We can pack replaced conditions to
  (!read_limit || (read_limit && sq->nr_queued[READ])) &&
  (!write_limit || (write_limit && sq->nr_queued[WRITE]))
which is equivalent to
  (!read_limit || sq->nr_queued[READ]) &&
  (!write_limit || sq->nr_queued[WRITE])

Reported-by: kernel test robot <lkp@intel.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Kemeng Shi <shikemeng@huawei.com>
Link: https://lore.kernel.org/r/20221205115709.251489-6-shikemeng@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-12-05 13:44:48 -07:00
Kemeng Shi
183daeb11d blk-throttle: correct calculation of wait time in tg_may_dispatch
In C language, When executing "if (expression1 && expression2)" and
expression1 return false, the expression2 may not be executed.
For "tg_within_bps_limit(tg, bio, bps_limit, &bps_wait) &&
tg_within_iops_limit(tg, bio, iops_limit, &iops_wait))", if bps is
limited, tg_within_bps_limit will return false and
tg_within_iops_limit will not be called. So even bps and iops are
both limited, iops_wait will not be calculated and is always zero.
So wait time of iops is always ignored.

Fix this by always calling tg_within_bps_limit and tg_within_iops_limit
to get wait time for both bps and iops.

Observed that:
1. Wait time in tg_within_iops_limit/tg_within_bps_limit need always
be stored as wait argument is always passed.
2. wait time is stored to zero if iops/bps is limited otherwise non-zero
is stored.
Simpfy tg_within_iops_limit/tg_within_bps_limit by removing wait argument
and return wait time directly. Caller tg_may_dispatch checks if wait time
is zero to find if iops/bps is limited.

Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Kemeng Shi <shikemeng@huawei.com>
Link: https://lore.kernel.org/r/20221205115709.251489-5-shikemeng@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-12-05 13:44:42 -07:00
Kemeng Shi
eb18479182 blk-throttle: ignore cgroup without io queued in blk_throtl_cancel_bios
Ignore cgroup without io queued in blk_throtl_cancel_bios for two
reasons:
1. Save cpu cycle for trying to dispatch cgroup which is no io queued.
2. Avoid non-consistent state that cgroup is inserted to service queue
without THROTL_TG_PENDING set as tg_update_disptime will unconditional
re-insert cgroup to service queue. If we are on the default hierarchy,
IO dispatched from child in tg_dispatch_one_bio will trigger inserting
cgroup to service queue without erase first and ruin the tree.

Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Kemeng Shi <shikemeng@huawei.com>
Link: https://lore.kernel.org/r/20221205115709.251489-4-shikemeng@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-12-05 13:44:34 -07:00
Kemeng Shi
84aca0a7e0 blk-throttle: Fix that bps of child could exceed bps limited in parent
Consider situation as following (on the default hierarchy):
 HDD
  |
root (bps limit: 4k)
  |
child (bps limit :8k)
  |
fio bs=8k
Rate of fio is supposed to be 4k, but result is 8k. Reason is as
following:
Size of single IO from fio is larger than bytes allowed in one
throtl_slice in child, so IOs are always queued in child group first.
When queued IOs in child are dispatched to parent group, BIO_BPS_THROTTLED
is set and these IOs will not be limited by tg_within_bps_limit anymore.
Fix this by only set BIO_BPS_THROTTLED when the bio traversed the entire
tree.

There patch has no influence on situation which is not on the default
hierarchy as each group is a single root group without parent.

Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Kemeng Shi <shikemeng@huawei.com>
Link: https://lore.kernel.org/r/20221205115709.251489-3-shikemeng@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-12-05 13:44:27 -07:00
Kemeng Shi
f56019aef3 blk-throttle: correct stale comment in throtl_pd_init
On the default hierarchy (cgroup2), the throttle interface files don't
exist in the root cgroup, so the ablity to limit the whole system
by configuring root group is not existing anymore. In general, cgroup
doesn't wanna be in the business of restricting resources at the
system level, so correct the stale comment that we can limit whole
system to we can only limit subtree.

Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Kemeng Shi <shikemeng@huawei.com>
Link: https://lore.kernel.org/r/20221205115709.251489-2-shikemeng@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-12-05 13:44:19 -07:00
Christoph Hellwig
cad9266abc blk-throttle: pass a gendisk to blk_throtl_cancel_bios
Pass the gendisk to blk_throtl_cancel_bios as part of moving the
blk-cgroup infrastructure to be gendisk based.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Andreas Herrmann <aherrmann@suse.de>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20220921180501.1539876-15-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-09-26 19:17:28 -06:00
Christoph Hellwig
5f6dc7522a blk-throttle: pass a gendisk to blk_throtl_register_queue
Pass the gendisk to blk_throtl_register_queue as part of moving the
blk-cgroup infrastructure to be gendisk based.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Andreas Herrmann <aherrmann@suse.de>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20220921180501.1539876-14-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-09-26 19:17:27 -06:00
Christoph Hellwig
e13793bae6 blk-throttle: pass a gendisk to blk_throtl_init and blk_throtl_exit
Pass the gendisk to blk_throtl_init and blk_throtl_exit as part of moving
the blk-cgroup infrastructure to be gendisk based.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Andreas Herrmann <aherrmann@suse.de>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20220921180501.1539876-13-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-09-26 19:17:27 -06:00
Yu Kuai
81c7a63abc blk-throttle: improve bypassing bios checkings
"tg->has_rules" is extended to "tg->has_rules_iops/bps", thus bios that
don't need to be throttled can be checked accurately.

With this patch, bio will be throttled if:

1) Bio is read/write, and corresponding read/write iops limit exist.
2) If corresponding doesn't exist, corresponding bps limit exist and
bio is not throttled before.

Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20220921095309.1481289-3-yukuai1@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-09-24 08:59:43 -06:00
Yu Kuai
8549674990 blk-throttle: remove THROTL_TG_HAS_IOPS_LIMIT
Currently, "tg->has_rules" and "tg->flags & THROTL_TG_HAS_IOPS_LIMIT"
both try to bypass bios that don't need to be throttled, however, they are
a little redundant and both not perfect:

1) "tg->has_rules" only distinguish read and write, but not iops and bps
   limit.
2) "tg->flags & THROTL_TG_HAS_IOPS_LIMIT" only check if iops limit
   exist, read and write is not distinguished, and bps limit is not
   checked.

tg->has_rules will extended to distinguish bps and iops in the following
patch. There is no need to keep the flag.

Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20220921095309.1481289-2-yukuai1@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-09-24 08:59:43 -06:00
Yu Kuai
c013710e1a blk-throttle: cleanup tg_update_disptime()
tg_update_disptime() only need to adjust postion for 'tg' in
'parent_sq', there is no need to call throtl_enqueue/dequeue_tg(),
since they will set/clear flag THROTL_TG_PENDING and increase/decrease
nr_pending, which is useless. By the way, clear the flag/decrease
nr_pending while there are still throttled bios is not good for debugging.

There are no functional changes.

Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20220827101637.1775111-4-yukuai1@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-09-12 00:20:08 -06:00
Yu Kuai
8c25ed0cb9 blk-throttle: calling throtl_dequeue/enqueue_tg in pairs
It's a little weird to call throtl_dequeue_tg() unconditionally in
throtl_select_dispatch(), since it will be called in tg_update_disptime()
again if some bio is still throttled. Thus call it later if there are no
throttled bio. There are no functional changes.

Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20220827101637.1775111-3-yukuai1@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-09-12 00:20:07 -06:00
Yu Kuai
7e9c5c54d4 blk-throttle: use 'READ/WRITE' instead of '0/1'
Make the code easier to read, like everywhere else.

Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20220827101637.1775111-2-yukuai1@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-09-12 00:20:07 -06:00
Yu Kuai
a880ae93e5 blk-throttle: fix io hung due to configuration updates
If new configuration is submitted while a bio is throttled, then new
waiting time is recalculated regardless that the bio might already wait
for some time:

tg_conf_updated
 throtl_start_new_slice
  tg_update_disptime
  throtl_schedule_next_dispatch

Then io hung can be triggered by always submmiting new configuration
before the throttled bio is dispatched.

Fix the problem by respecting the time that throttled bio already waited.
In order to do that, add new fields to record how many bytes/io are
waited, and use it to calculate wait time for throttled bio under new
configuration.

Some simple test:
1)
cd /sys/fs/cgroup/blkio/
echo $$ > cgroup.procs
echo "8:0 2048" > blkio.throttle.write_bps_device
{
        sleep 2
        echo "8:0 1024" > blkio.throttle.write_bps_device
} &
dd if=/dev/zero of=/dev/sda bs=8k count=1 oflag=direct

2)
cd /sys/fs/cgroup/blkio/
echo $$ > cgroup.procs
echo "8:0 1024" > blkio.throttle.write_bps_device
{
        sleep 4
        echo "8:0 2048" > blkio.throttle.write_bps_device
} &
dd if=/dev/zero of=/dev/sda bs=8k count=1 oflag=direct

test results: io finish time
	before this patch	with this patch
1)	10s			6s
2)	8s			6s

Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Reviewed-by: Michal Koutný <mkoutny@suse.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20220829022240.3348319-5-yukuai1@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-09-12 00:19:48 -06:00
Yu Kuai
681cd46fff blk-throttle: factor out code to calculate ios/bytes_allowed
No functional changes, new apis will be used in later patches to
calculate wait time for throttled bios when new configuration is
submitted.

Noted this patch also rename tg_with_in_iops/bps_limit() to
tg_within_iops/bps_limit().

Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20220829022240.3348319-4-yukuai1@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-09-12 00:19:48 -06:00
Yu Kuai
8d6bbaada2 blk-throttle: prevent overflow while calculating wait time
There is a problem found by code review in tg_with_in_bps_limit() that
'bps_limit * jiffy_elapsed_rnd' might overflow. Fix the problem by
calling mul_u64_u64_div_u64() instead.

Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20220829022240.3348319-3-yukuai1@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-09-12 00:19:48 -06:00
Yu Kuai
320fb0f91e blk-throttle: fix that io throttle can only work for single bio
Test scripts:
cd /sys/fs/cgroup/blkio/
echo "8:0 1024" > blkio.throttle.write_bps_device
echo $$ > cgroup.procs
dd if=/dev/zero of=/dev/sda bs=10k count=1 oflag=direct &
dd if=/dev/zero of=/dev/sda bs=10k count=1 oflag=direct &

Test result:
10240 bytes (10 kB, 10 KiB) copied, 10.0134 s, 1.0 kB/s
10240 bytes (10 kB, 10 KiB) copied, 10.0135 s, 1.0 kB/s

The problem is that the second bio is finished after 10s instead of 20s.

Root cause:
1) second bio will be flagged:

__blk_throtl_bio
 while (true) {
  ...
  if (sq->nr_queued[rw]) -> some bio is throttled already
   break
 };
 bio_set_flag(bio, BIO_THROTTLED); -> flag the bio

2) flagged bio will be dispatched without waiting:

throtl_dispatch_tg
 tg_may_dispatch
  tg_with_in_bps_limit
   if (bps_limit == U64_MAX || bio_flagged(bio, BIO_THROTTLED))
    *wait = 0; -> wait time is zero
    return true;

commit 9f5ede3c01 ("block: throttle split bio in case of iops limit")
support to count split bios for iops limit, thus it adds flagged bio
checking in tg_with_in_bps_limit() so that split bios will only count
once for bps limit, however, it introduce a new problem that io throttle
won't work if multiple bios are throttled.

In order to fix the problem, handle iops/bps limit in different ways:

1) for iops limit, there is no flag to record if the bio is throttled,
   and iops is always applied.
2) for bps limit, original bio will be flagged with BIO_BPS_THROTTLED,
   and io throttle will ignore bio with the flag.

Noted this patch also remove the code to set flag in __bio_clone(), it's
introduced in commit 111be88398 ("block-throttle: avoid double
charge"), and author thinks split bio can be resubmited and throttled
again, which is wrong because split bio will continue to dispatch from
caller.

Fixes: 9f5ede3c01 ("block: throttle split bio in case of iops limit")
Cc: <stable@vger.kernel.org>
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20220829022240.3348319-2-yukuai1@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-09-12 00:19:48 -06:00
Yu Kuai
2d8f7a3b9f blk-throttle: clean up codes that can't be reached
While doing code coverage testing while CONFIG_BLK_DEV_THROTTLING_LOW is
disabled, we found that there are many codes can never be reached.

This patch move such codes inside "#ifdef CONFIG_BLK_DEV_THROTTLING_LOW".

Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20220903062826.1099085-1-yukuai1@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-09-04 14:38:18 -06:00
Bart Van Assche
77e7ffd7ad block: Use enum req_op where appropriate
Change the type of the arguments that are used to pass a REQ_OP_* value
from int or unsigned int into enum req_op to improve static type
checking.

Cc: Christoph Hellwig <hch@lst.de>
Cc: Ming Lei <ming.lei@redhat.com>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Damien Le Moal <damien.lemoal@wdc.com>
Cc: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Link: https://lore.kernel.org/r/20220714180729.1065367-3-bvanassche@acm.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-07-14 12:14:30 -06:00
Laibin Qiu
5a011f889b blk-throttle: Set BIO_THROTTLED when bio has been throttled
1.In current process, all bio will set the BIO_THROTTLED flag
after __blk_throtl_bio().

2.If bio needs to be throttled, it will start the timer and
stop submit bio directly. Bio will submit in
blk_throtl_dispatch_work_fn() when the timer expires.But in
the current process, if bio is throttled. The BIO_THROTTLED
will be set to bio after timer start. If the bio has been
completed, it may cause use-after-free blow.

BUG: KASAN: use-after-free in blk_throtl_bio+0x12f0/0x2c70
Read of size 2 at addr ffff88801b8902d4 by task fio/26380

 dump_stack+0x9b/0xce
 print_address_description.constprop.6+0x3e/0x60
 kasan_report.cold.9+0x22/0x3a
 blk_throtl_bio+0x12f0/0x2c70
 submit_bio_checks+0x701/0x1550
 submit_bio_noacct+0x83/0xc80
 submit_bio+0xa7/0x330
 mpage_readahead+0x380/0x500
 read_pages+0x1c1/0xbf0
 page_cache_ra_unbounded+0x471/0x6f0
 do_page_cache_ra+0xda/0x110
 ondemand_readahead+0x442/0xae0
 page_cache_async_ra+0x210/0x300
 generic_file_buffered_read+0x4d9/0x2130
 generic_file_read_iter+0x315/0x490
 blkdev_read_iter+0x113/0x1b0
 aio_read+0x2ad/0x450
 io_submit_one+0xc8e/0x1d60
 __se_sys_io_submit+0x125/0x350
 do_syscall_64+0x2d/0x40
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Allocated by task 26380:
 kasan_save_stack+0x19/0x40
 __kasan_kmalloc.constprop.2+0xc1/0xd0
 kmem_cache_alloc+0x146/0x440
 mempool_alloc+0x125/0x2f0
 bio_alloc_bioset+0x353/0x590
 mpage_alloc+0x3b/0x240
 do_mpage_readpage+0xddf/0x1ef0
 mpage_readahead+0x264/0x500
 read_pages+0x1c1/0xbf0
 page_cache_ra_unbounded+0x471/0x6f0
 do_page_cache_ra+0xda/0x110
 ondemand_readahead+0x442/0xae0
 page_cache_async_ra+0x210/0x300
 generic_file_buffered_read+0x4d9/0x2130
 generic_file_read_iter+0x315/0x490
 blkdev_read_iter+0x113/0x1b0
 aio_read+0x2ad/0x450
 io_submit_one+0xc8e/0x1d60
 __se_sys_io_submit+0x125/0x350
 do_syscall_64+0x2d/0x40
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Freed by task 0:
 kasan_save_stack+0x19/0x40
 kasan_set_track+0x1c/0x30
 kasan_set_free_info+0x1b/0x30
 __kasan_slab_free+0x111/0x160
 kmem_cache_free+0x94/0x460
 mempool_free+0xd6/0x320
 bio_free+0xe0/0x130
 bio_put+0xab/0xe0
 bio_endio+0x3a6/0x5d0
 blk_update_request+0x590/0x1370
 scsi_end_request+0x7d/0x400
 scsi_io_completion+0x1aa/0xe50
 scsi_softirq_done+0x11b/0x240
 blk_mq_complete_request+0xd4/0x120
 scsi_mq_done+0xf0/0x200
 virtscsi_vq_done+0xbc/0x150
 vring_interrupt+0x179/0x390
 __handle_irq_event_percpu+0xf7/0x490
 handle_irq_event_percpu+0x7b/0x160
 handle_irq_event+0xcc/0x170
 handle_edge_irq+0x215/0xb20
 common_interrupt+0x60/0x120
 asm_common_interrupt+0x1e/0x40

Fix this by move BIO_THROTTLED set into the queue_lock.

Signed-off-by: Laibin Qiu <qiulaibin@huawei.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20220301123919.2381579-1-qiulaibin@huawei.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-05-17 19:32:10 -06:00
Christoph Hellwig
f4a6a61cb6 blktrace: cleanup the __trace_note_message interface
Pass the cgroup_subsys_state instead of a the blkg so that blktrace
doesn't need to poke into blk-cgroup internals, and give the name a
blk prefix as the current name is way too generic for a public
interface.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20220420042723.1010598-9-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-05-02 14:06:20 -06:00
Yu Kuai
8f9e7b65f8 block: cancel all throttled bios in del_gendisk()
Throttled bios can't be issued after del_gendisk() is done, thus
it's better to cancel them immediately rather than waiting for
throttle is done.

For example, if user thread is throttled with low bps while it's
issuing large io, and the device is deleted. The user thread will
wait for a long time for io to return.

Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20220318130144.1066064-4-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-03-18 09:57:56 -06:00
Ming Lei
ee37eddbfa block: avoid use-after-free on throttle data
In throtl_pending_timer_fn(), request queue is retrieved from throttle
data. And tg's pending timer is deleted synchronously when releasing the
associated blkg, at that time, throttle data may have been freed since
commit 1059699f87 ("block: move blkcg initialization/destroy into disk
allocation/release handler") moves freeing q->td to disk_release() from
blk_release_queue(). So use-after-free on q->td in throtl_pending_timer_fn
can be triggered.

Fixes the issue by:

- do nothing in case that disk is released, when there isn't any bio to
  dispatch

- retrieve request queue from blkg instead of throttle data for
non top-level pending timer.

Signed-off-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20220318130144.1066064-2-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-03-18 09:57:56 -06:00
Ming Lei
34841e6fb1 block: revert 4f1e9630af ("blk-throtl: optimize IOPS throttle for large IO scenarios")
Revert commit 4f1e9630af ("blk-throtl: optimize IOPS throttle for large
IO scenarios") since we have another easier way to address this issue and
get better iops throttling result.

Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20220216044514.2903784-9-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-02-16 19:42:28 -07:00
Ming Lei
5a93b6027e block: don't try to throttle split bio if iops limit isn't set
We need to throttle split bio in case of IOPS limit even though the
split bio has been marked as BIO_THROTTLED since block layer
accounts split bio actually.

If only throughput throttle is setup, no need to throttle any more
if BIO_THROTTLED is set since we have accounted & considered the
whole bio bytes already.

Add one flag of THROTL_TG_HAS_IOPS_LIMIT for serving this purpose.

Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20220216044514.2903784-8-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-02-16 19:42:28 -07:00
Ming Lei
9f5ede3c01 block: throttle split bio in case of iops limit
Commit 111be88398 ("block-throttle: avoid double charge") marks bio as
BIO_THROTTLED unconditionally if __blk_throtl_bio() is called on this bio,
then this bio won't be called into __blk_throtl_bio() any more. This way
is to avoid double charge in case of bio splitting. It is reasonable for
read/write throughput limit, but not reasonable for IOPS limit because
block layer provides io accounting against split bio.

Chunguang Xu has already observed this issue and fixed it in commit
4f1e9630af ("blk-throtl: optimize IOPS throttle for large IO scenarios").
However, that patch only covers bio splitting in __blk_queue_split(), and
we have other kind of bio splitting, such as bio_split() &
submit_bio_noacct() and other ways.

This patch tries to fix the issue in one generic way by always charging
the bio for iops limit in blk_throtl_bio(). This way is reasonable:
re-submission & fast-cloned bio is charged if it is submitted to same
disk/queue, and BIO_THROTTLED will be cleared if bio->bi_bdev is changed.

This new approach can get much more smooth/stable iops limit compared with
commit 4f1e9630af ("blk-throtl: optimize IOPS throttle for large IO
scenarios") since that commit can't throttle current split bios actually.

Also this way won't cause new double bio iops charge in
blk_throtl_dispatch_work_fn() in which blk_throtl_bio() won't be called
any more.

Reported-by: Ning Li <lining2020x@163.com>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Chunguang Xu <brookxu@tencent.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20220216044514.2903784-7-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-02-16 19:42:28 -07:00
Ming Lei
3f98c75371 block: don't check bio in blk_throtl_dispatch_work_fn
The bio has been checked already before throttling, so no need to check
it again before dispatching it from throttle queue.

Add a helper of submit_bio_noacct_nocheck() for this purpose.

Signed-off-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20220216044514.2903784-5-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-02-16 19:42:28 -07:00
Ming Lei
672fdcf0e7 block: partition include/linux/blk-cgroup.h
Partition include/linux/blk-cgroup.h into two parts: one is public part,
the other is block layer private part.

Suggested by Christoph Hellwig.

Signed-off-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20220211101149.2368042-4-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-02-11 10:02:41 -07:00
Christoph Hellwig
e4a19f7289 block: don't include blk-mq.h in blk.h
No needed, shift a blk-stat.h include into the source file that needs it
instead.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211123185312.1432157-6-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-11-29 06:38:44 -07:00
Pavel Begunkov
ed6cddefdf block: convert the rest of block to bdev_get_queue
Convert bdev->bd_disk->queue to bdev_get_queue(), it's uses a cached
queue pointer and so is faster.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/addf6ea988c04213697ba3684c853e4ed7642a39.1634219547.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-10-18 06:17:37 -06:00
Jens Axboe
a7b36ee6ba block: move blk-throtl fast path inline
Even if no policies are defined, we spend ~2% of the total IO time
checking. Move the fast path inline.

Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-10-18 06:17:03 -06:00