From: Zhang Yi <yi.zhang@huawei.com>
To: <linux-block@vger.kernel.org>
Cc: <axboe@kernel.dk>, <jbacik@fb.com>, <yi.zhang@huawei.com>,
<yukuai3@huawei.com>
Subject: [PATCH 1/2] blk-wbt: introduce a new disable state to prevent false positive by rwb_enabled()
Date: Sat, 19 Jun 2021 17:36:59 +0800 [thread overview]
Message-ID: <20210619093700.920393-2-yi.zhang@huawei.com> (raw)
In-Reply-To: <20210619093700.920393-1-yi.zhang@huawei.com>
Now that we disable wbt by simply zero out rwb->wb_normal in
wbt_disable_default() when switch elevator to bfq, but it's not safe
because it will become false positive if we change queue depth. If it
become false positive between wbt_wait() and wbt_track() when submit
write request, it will lead to drop rqw->inflight to -1 in wbt_done(),
which will end up trigger IO hung. Fix this issue by introduce a new
state which mean the wbt was disabled.
Fixes: a79050434b45 ("blk-rq-qos: refactor out common elements of blk-wbt")
Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
---
block/blk-wbt.c | 5 +++--
block/blk-wbt.h | 1 +
2 files changed, 4 insertions(+), 2 deletions(-)
diff --git a/block/blk-wbt.c b/block/blk-wbt.c
index 42aed0160f86..b098ac6a84f0 100644
--- a/block/blk-wbt.c
+++ b/block/blk-wbt.c
@@ -77,7 +77,8 @@ enum {
static inline bool rwb_enabled(struct rq_wb *rwb)
{
- return rwb && rwb->wb_normal != 0;
+ return rwb && rwb->enable_state != WBT_STATE_OFF_DEFAULT &&
+ rwb->wb_normal != 0;
}
static void wb_timestamp(struct rq_wb *rwb, unsigned long *var)
@@ -702,7 +703,7 @@ void wbt_disable_default(struct request_queue *q)
rwb = RQWB(rqos);
if (rwb->enable_state == WBT_STATE_ON_DEFAULT) {
blk_stat_deactivate(rwb->cb);
- rwb->wb_normal = 0;
+ rwb->enable_state = WBT_STATE_OFF_DEFAULT;
}
}
EXPORT_SYMBOL_GPL(wbt_disable_default);
diff --git a/block/blk-wbt.h b/block/blk-wbt.h
index 16bdc85b8df9..2eb01becde8c 100644
--- a/block/blk-wbt.h
+++ b/block/blk-wbt.h
@@ -34,6 +34,7 @@ enum {
enum {
WBT_STATE_ON_DEFAULT = 1,
WBT_STATE_ON_MANUAL = 2,
+ WBT_STATE_OFF_DEFAULT
};
struct rq_wb {
--
2.31.1
next prev parent reply other threads:[~2021-06-19 9:28 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-19 9:36 [PATCH 0/2] blk-wbt: fix two wbt enable problems Zhang Yi
2021-06-19 9:36 ` Zhang Yi [this message]
2021-06-19 9:37 ` [PATCH 2/2] blk-wbt: make sure throttle is enabled properly Zhang Yi
2021-06-21 16:07 ` [PATCH 0/2] blk-wbt: fix two wbt enable problems Jens Axboe
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20210619093700.920393-2-yi.zhang@huawei.com \
--to=yi.zhang@huawei.com \
--cc=axboe@kernel.dk \
--cc=jbacik@fb.com \
--cc=linux-block@vger.kernel.org \
--cc=yukuai3@huawei.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).