From: Ming Lei <tom.leiming@gmail.com>
To: Jens Axboe <axboe@fb.com>,
linux-block@vger.kernel.org,
Christoph Hellwig <hch@infradead.org>
Cc: Bart Van Assche <bart.vanassche@sandisk.com>,
Hannes Reinecke <hare@suse.de>, Ming Lei <tom.leiming@gmail.com>,
Tejun Heo <tj@kernel.org>
Subject: [PATCH v3 4/4] block: block new I/O just after queue is set as dying
Date: Mon, 27 Mar 2017 20:06:58 +0800 [thread overview]
Message-ID: <20170327120658.29864-5-tom.leiming@gmail.com> (raw)
In-Reply-To: <20170327120658.29864-1-tom.leiming@gmail.com>
Before commit 780db2071a(blk-mq: decouble blk-mq freezing
from generic bypassing), the dying flag is checked before
entering queue, and Tejun converts the checking into .mq_freeze_depth,
and assumes the counter is increased just after dying flag
is set. Unfortunately we doesn't do that in blk_set_queue_dying().
This patch calls blk_freeze_queue_start() in blk_set_queue_dying(),
so that we can block new I/O coming once the queue is set as dying.
Given blk_set_queue_dying() is always called in remove path
of block device, and queue will be cleaned up later, we don't
need to worry about undoing the counter.
Cc: Bart Van Assche <bart.vanassche@sandisk.com>
Cc: Tejun Heo <tj@kernel.org>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Ming Lei <tom.leiming@gmail.com>
---
block/blk-core.c | 13 ++++++++++---
1 file changed, 10 insertions(+), 3 deletions(-)
diff --git a/block/blk-core.c b/block/blk-core.c
index 60f364e1d36b..e22c4ea002ec 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -500,6 +500,13 @@ void blk_set_queue_dying(struct request_queue *q)
queue_flag_set(QUEUE_FLAG_DYING, q);
spin_unlock_irq(q->queue_lock);
+ /*
+ * When queue DYING flag is set, we need to block new req
+ * entering queue, so we call blk_freeze_queue_start() to
+ * prevent I/O from crossing blk_queue_enter().
+ */
+ blk_freeze_queue_start(q);
+
if (q->mq_ops)
blk_mq_wake_waiters(q);
else {
@@ -672,9 +679,9 @@ int blk_queue_enter(struct request_queue *q, bool nowait)
/*
* read pair of barrier in blk_freeze_queue_start(),
* we need to order reading __PERCPU_REF_DEAD flag of
- * .q_usage_counter and reading .mq_freeze_depth,
- * otherwise the following wait may never return if the
- * two reads are reordered.
+ * .q_usage_counter and reading .mq_freeze_depth or
+ * queue dying flag, otherwise the following wait may
+ * never return if the two reads are reordered.
*/
smp_rmb();
--
2.9.3
next prev parent reply other threads:[~2017-03-27 12:07 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-27 12:06 [PATCH v3 0/4] block: misc changes Ming Lei
2017-03-27 12:06 ` [PATCH v3 1/4] blk-mq: comment on races related with timeout handler Ming Lei
2017-03-27 12:11 ` Johannes Thumshirn
2017-03-27 12:06 ` [PATCH v3 2/4] block: add a read barrier in blk_queue_enter() Ming Lei
2017-03-27 12:14 ` Johannes Thumshirn
2017-03-27 15:44 ` Bart Van Assche
2017-03-27 12:06 ` [PATCH v3 3/4] block: rename blk_mq_freeze_queue_start() Ming Lei
2017-03-27 12:15 ` Johannes Thumshirn
2017-03-27 12:06 ` Ming Lei [this message]
2017-03-27 12:16 ` [PATCH v3 4/4] block: block new I/O just after queue is set as dying Johannes Thumshirn
2017-03-27 15:49 ` Bart Van Assche
2017-03-29 2:11 ` [PATCH v3 0/4] block: misc changes Ming Lei
2017-03-29 14:00 ` 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=20170327120658.29864-5-tom.leiming@gmail.com \
--to=tom.leiming@gmail.com \
--cc=axboe@fb.com \
--cc=bart.vanassche@sandisk.com \
--cc=hare@suse.de \
--cc=hch@infradead.org \
--cc=linux-block@vger.kernel.org \
--cc=tj@kernel.org \
/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).