qiurui
/
linux-kernelorg-stable
mirror of https://kernel.googlesource.com/pub/scm/linux/kernel/git/stable/linux.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

blk-throttle: Fix wrong tg->[bytes/io]_disp update in __tg_update_carryover() 

In commit 6cc477c368 ("blk-throttle: carry over directly"), the carryover
bytes/ios was be carried to [bytes/io]_disp. However, its update mechanism
has some issues.

In __tg_update_carryover(), we calculate "bytes" and "ios" to represent the
carryover, but the computation when updating [bytes/io]_disp is incorrect.
And if the sq->nr_queued is empty, we may not update tg->[bytes/io]_disp to
0 in tg_update_carryover(). We should set it to 0 in non carryover case.
This patch fixes the issue.

Fixes: 6cc477c368 ("blk-throttle: carry over directly")
Signed-off-by: Zizhi Wo <wozizhi@huawei.com>
Reviewed-by: Yu Kuai <yukuai3@huawei.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20250417132054.2866409-2-wozizhi@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Zizhi Wo 2025-04-17 21:20:52 +08:00 committed by Jens Axboe
parent e371b9d336
commit f66cf69eb8
1 changed files with 16 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

22
block/blk-throttle.c
View File

@ -644,6 +644,18 @@ static void __tg_update_carryover(struct throtl_grp *tg, bool rw,
u64 bps_limit = tg_bps_limit(tg, rw);
u32 iops_limit = tg_iops_limit(tg, rw);
/*
* If the queue is empty, carryover handling is not needed. In such cases,
* tg->[bytes/io]_disp should be reset to 0 to avoid impacting the dispatch
* of subsequent bios. The same handling applies when the previous BPS/IOPS
* limit was set to max.
*/
if (tg->service_queue.nr_queued[rw] == 0) {
tg->bytes_disp[rw] = 0;
tg->io_disp[rw] = 0;
return;
}
/*
* If config is updated while bios are still throttled, calculate and
* accumulate how many bytes/ios are waited across changes. And
@ -656,8 +668,8 @@ static void __tg_update_carryover(struct throtl_grp *tg, bool rw,
if (iops_limit != UINT_MAX)
*ios = calculate_io_allowed(iops_limit, jiffy_elapsed) -
tg->io_disp[rw];
tg->bytes_disp[rw] -= *bytes;
tg->io_disp[rw] -= *ios;
tg->bytes_disp[rw] = -*bytes;
tg->io_disp[rw] = -*ios;
}
static void tg_update_carryover(struct throtl_grp *tg)
@ -665,10 +677,8 @@ static void tg_update_carryover(struct throtl_grp *tg)
long long bytes[2] = {0};
int ios[2] = {0};
if (tg->service_queue.nr_queued[READ])
__tg_update_carryover(tg, READ, &bytes[READ], &ios[READ]);
if (tg->service_queue.nr_queued[WRITE])
__tg_update_carryover(tg, WRITE, &bytes[WRITE], &ios[WRITE]);
__tg_update_carryover(tg, READ, &bytes[READ], &ios[READ]);
__tg_update_carryover(tg, WRITE, &bytes[WRITE], &ios[WRITE]);
/* see comments in struct throtl_grp for meaning of these fields. */
throtl_log(&tg->service_queue, "%s: %lld %lld %d %d\n", __func__,