From: Kemeng Shi shikemeng@huawei.com
mainline inclusion from mainline-v6.2-rc1 commit 183daeb11de871b073515d14ec1e3bc0da79e038 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/IAUKH4 CVE: NA
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...
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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 Signed-off-by: Yu Kuai yukuai3@huawei.com --- block/blk-throttle.c | 38 +++++++++++++------------------------- 1 file changed, 13 insertions(+), 25 deletions(-)
diff --git a/block/blk-throttle.c b/block/blk-throttle.c index ba2f579a7934..d04a72b30faf 100644 --- a/block/blk-throttle.c +++ b/block/blk-throttle.c @@ -835,17 +835,15 @@ static void tg_update_carryover(struct throtl_grp *tg) tg->carryover_ios[READ], tg->carryover_ios[WRITE]); }
-static bool tg_within_iops_limit(struct throtl_grp *tg, struct bio *bio, - u32 iops_limit, unsigned long *wait) +static unsigned long tg_within_iops_limit(struct throtl_grp *tg, struct bio *bio, + u32 iops_limit) { bool rw = bio_data_dir(bio); unsigned int io_allowed; unsigned long jiffy_elapsed, jiffy_wait, jiffy_elapsed_rnd;
if (iops_limit == UINT_MAX) { - if (wait) - *wait = 0; - return true; + return 0; }
jiffy_elapsed = jiffies - tg->slice_start[rw]; @@ -855,21 +853,16 @@ static bool tg_within_iops_limit(struct throtl_grp *tg, struct bio *bio, io_allowed = calculate_io_allowed(iops_limit, jiffy_elapsed_rnd) + tg->carryover_ios[rw]; if (tg->io_disp[rw] + 1 <= io_allowed) { - if (wait) - *wait = 0; - return true; + return 0; }
/* Calc approx time to dispatch */ jiffy_wait = jiffy_elapsed_rnd - jiffy_elapsed; - - if (wait) - *wait = jiffy_wait; - return false; + return jiffy_wait; }
-static bool tg_within_bps_limit(struct throtl_grp *tg, struct bio *bio, - u64 bps_limit, unsigned long *wait) +static unsigned long tg_within_bps_limit(struct throtl_grp *tg, struct bio *bio, + u64 bps_limit) { bool rw = bio_data_dir(bio); u64 bytes_allowed, extra_bytes; @@ -878,9 +871,7 @@ static bool tg_within_bps_limit(struct throtl_grp *tg, struct bio *bio,
/* no need to throttle if this bio's bytes have been accounted */ if (bps_limit == U64_MAX || bio_flagged(bio, BIO_BPS_THROTTLED)) { - if (wait) - *wait = 0; - return true; + return 0; }
jiffy_elapsed = jiffy_elapsed_rnd = jiffies - tg->slice_start[rw]; @@ -893,9 +884,7 @@ static bool tg_within_bps_limit(struct throtl_grp *tg, struct bio *bio, bytes_allowed = calculate_bytes_allowed(bps_limit, jiffy_elapsed_rnd) + tg->carryover_bytes[rw]; if (tg->bytes_disp[rw] + bio_size <= bytes_allowed) { - if (wait) - *wait = 0; - return true; + return 0; }
/* Calc approx time to dispatch */ @@ -910,9 +899,7 @@ static bool tg_within_bps_limit(struct throtl_grp *tg, struct bio *bio, * up we did. Add that time also. */ jiffy_wait = jiffy_wait + (jiffy_elapsed_rnd - jiffy_elapsed); - if (wait) - *wait = jiffy_wait; - return false; + return jiffy_wait; }
/* @@ -959,8 +946,9 @@ static bool tg_may_dispatch(struct throtl_grp *tg, struct bio *bio, jiffies + tg->td->throtl_slice); }
- if (tg_within_bps_limit(tg, bio, bps_limit, &bps_wait) && - tg_within_iops_limit(tg, bio, iops_limit, &iops_wait)) { + bps_wait = tg_within_bps_limit(tg, bio, bps_limit); + iops_wait = tg_within_iops_limit(tg, bio, iops_limit); + if (bps_wait + iops_wait == 0) { if (wait) *wait = 0; return true;