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

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Message-Id: <20240530134547.970075-1-longman@redhat.com>
Date: Thu, 30 May 2024 09:45:47 -0400
From: Waiman Long <longman@...hat.com>
To: Jens Axboe <axboe@...nel.dk>,
	Tejun Heo <tj@...nel.org>,
	Josef Bacik <josef@...icpanda.com>
Cc: cgroups@...r.kernel.org,
	linux-block@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Dan Schatzberg <schatzberg.dan@...il.com>,
	Ming Lei <ming.lei@...hat.com>,
	Waiman Long <longman@...hat.com>,
	Justin Forbes <jforbes@...hat.com>
Subject: [PATCH] blk-throttle: Fix incorrect display of io.max

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@...hat.com>
Closes: https://github.com/containers/podman/issues/22701#issuecomment-2120627789
Signed-off-by: Waiman Long <longman@...hat.com>
---
 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