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

From: Yu Kuai
Date: Thu May 30 2024 - 21:21:47 EST


在 2024/05/30 21:49, Waiman Long 写道:

On 5/30/24 09:45, Waiman Long wrote:
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>

LGTM
Reviewed-by: Yu Kuai <yukuai3@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];

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