[PATCH] blk-throttle: Fix incorrect display of io.max

From: Waiman Long
Date: Thu May 30 2024 - 09:47:21 EST


Commit bf20ab538c81 ("blk-throttle: remove CONFIG_BLK_DEV_THROTTLING_LOW")
attempts to revert the code change introduced by commit cd5ab1b0fcb4
("blk-throttle: add .low interface"). However, it leaves behind the
bps_conf[] and iops_conf[] fields in the throtl_grp structure which
aren't set anywhere in the new blk-throttle.c code but are still being
used by tg_prfill_limit() to display the limits in io.max. Now io.max
always displays the following values if a block queue is used:

<m>:<n> rbps=0 wbps=0 riops=0 wiops=0

Fix this problem by removing bps_conf[] and iops_conf[] and use bps[]
and iops[] instead to complete the revert.

Fixes: bf20ab538c81 ("blk-throttle: remove CONFIG_BLK_DEV_THROTTLING_LOW")
Reported-by: Justin Forbes <jforbes@xxxxxxxxxx>
Closes: https://github.com/containers/podman/issues/22701#issuecomment-2120627789
Signed-off-by: Waiman Long <longman@xxxxxxxxxx>
---
block/blk-throttle.c | 24 ++++++++++++------------
block/blk-throttle.h | 8 ++------
2 files changed, 14 insertions(+), 18 deletions(-)

diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index d907040859f9..da619654f418 100644
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -1347,32 +1347,32 @@ static u64 tg_prfill_limit(struct seq_file *sf, struct blkg_policy_data *pd,
bps_dft = U64_MAX;
iops_dft = UINT_MAX;

- if (tg->bps_conf[READ] == bps_dft &&
- tg->bps_conf[WRITE] == bps_dft &&
- tg->iops_conf[READ] == iops_dft &&
- tg->iops_conf[WRITE] == iops_dft)
+ if (tg->bps[READ] == bps_dft &&
+ tg->bps[WRITE] == bps_dft &&
+ tg->iops[READ] == iops_dft &&
+ tg->iops[WRITE] == iops_dft)
return 0;

seq_printf(sf, "%s", dname);
- if (tg->bps_conf[READ] == U64_MAX)
+ if (tg->bps[READ] == U64_MAX)
seq_printf(sf, " rbps=max");
else
- seq_printf(sf, " rbps=%llu", tg->bps_conf[READ]);
+ seq_printf(sf, " rbps=%llu", tg->bps[READ]);

- if (tg->bps_conf[WRITE] == U64_MAX)
+ if (tg->bps[WRITE] == U64_MAX)
seq_printf(sf, " wbps=max");
else
- seq_printf(sf, " wbps=%llu", tg->bps_conf[WRITE]);
+ seq_printf(sf, " wbps=%llu", tg->bps[WRITE]);

- if (tg->iops_conf[READ] == UINT_MAX)
+ if (tg->iops[READ] == UINT_MAX)
seq_printf(sf, " riops=max");
else
- seq_printf(sf, " riops=%u", tg->iops_conf[READ]);
+ seq_printf(sf, " riops=%u", tg->iops[READ]);

- if (tg->iops_conf[WRITE] == UINT_MAX)
+ if (tg->iops[WRITE] == UINT_MAX)
seq_printf(sf, " wiops=max");
else
- seq_printf(sf, " wiops=%u", tg->iops_conf[WRITE]);
+ seq_printf(sf, " wiops=%u", tg->iops[WRITE]);

seq_printf(sf, "\n");
return 0;
diff --git a/block/blk-throttle.h b/block/blk-throttle.h
index 32503fd83a84..8c365541a275 100644
--- a/block/blk-throttle.h
+++ b/block/blk-throttle.h
@@ -95,15 +95,11 @@ struct throtl_grp {
bool has_rules_bps[2];
bool has_rules_iops[2];

- /* internally used bytes per second rate limits */
+ /* bytes per second rate limits */
uint64_t bps[2];
- /* user configured bps limits */
- uint64_t bps_conf[2];

- /* internally used IOPS limits */
+ /* IOPS limits */
unsigned int iops[2];
- /* user configured IOPS limits */
- unsigned int iops_conf[2];

/* Number of bytes dispatched in current slice */
uint64_t bytes_disp[2];
--
2.43.0