linux-block.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Christoph Hellwig <hch@lst.de>
To: Jens Axboe <axboe@kernel.dk>
Cc: Tejun Heo <tj@kernel.org>,
	linux-block@vger.kernel.org, Ming Lei <ming.lei@redhat.com>
Subject: [PATCH 2/4] block: split bio_queue_enter from blk_queue_enter
Date: Wed, 22 Sep 2021 19:22:20 +0200	[thread overview]
Message-ID: <20210922172222.2453343-3-hch@lst.de> (raw)
In-Reply-To: <20210922172222.2453343-1-hch@lst.de>

To prepare for fixing a gendisk shutdown race, open code the
blk_queue_enter logic in bio_queue_enter.  This also removes the
pointless flags translation.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 block/blk-core.c | 33 +++++++++++++++++++++++++--------
 1 file changed, 25 insertions(+), 8 deletions(-)

diff --git a/block/blk-core.c b/block/blk-core.c
index 4c078681f39b8..e951378855a02 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -475,18 +475,35 @@ int blk_queue_enter(struct request_queue *q, blk_mq_req_flags_t flags)
 static inline int bio_queue_enter(struct bio *bio)
 {
 	struct request_queue *q = bio->bi_bdev->bd_disk->queue;
-	bool nowait = bio->bi_opf & REQ_NOWAIT;
-	int ret;
 
-	ret = blk_queue_enter(q, nowait ? BLK_MQ_REQ_NOWAIT : 0);
-	if (unlikely(ret)) {
-		if (nowait && !blk_queue_dying(q))
+	while (!blk_try_enter_queue(q, false)) {
+		if (bio->bi_opf & REQ_NOWAIT) {
+			if (blk_queue_dying(q))
+				goto dead;
 			bio_wouldblock_error(bio);
-		else
-			bio_io_error(bio);
+			return -EBUSY;
+		}
+
+		/*
+		 * 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 or queue dying flag, otherwise the
+		 * following wait may never return if the two reads are
+		 * reordered.
+		 */
+		smp_rmb();
+		wait_event(q->mq_freeze_wq,
+			   (!q->mq_freeze_depth &&
+			    blk_pm_resume_queue(false, q)) ||
+			   blk_queue_dying(q));
+		if (blk_queue_dying(q))
+			goto dead;
 	}
 
-	return ret;
+	return 0;
+dead:
+	bio_io_error(bio);
+	return -ENODEV;
 }
 
 void blk_queue_exit(struct request_queue *q)
-- 
2.30.2


  parent reply	other threads:[~2021-09-22 17:28 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-22 17:22 tear down file system I/O in del_gendisk v2 Christoph Hellwig
2021-09-22 17:22 ` [PATCH 1/4] block: factor out a blk_try_enter_queue helper Christoph Hellwig
2021-09-22 17:22 ` Christoph Hellwig [this message]
2021-09-22 17:22 ` [PATCH 3/4] block: drain file system I/O on del_gendisk Christoph Hellwig
2021-09-23  1:34   ` Ming Lei
2021-09-23  5:27     ` Christoph Hellwig
2021-09-23  6:39       ` Ming Lei
2021-09-27 12:04         ` Christoph Hellwig
2021-09-27 14:32           ` Ming Lei
2021-09-23  6:21   ` Hannes Reinecke
2021-09-22 17:22 ` [PATCH 4/4] block: keep q_usage_counter in atomic mode after del_gendisk Christoph Hellwig
  -- strict thread matches above, loose matches on Subject: below --
2021-09-20 11:24 tear down file system I/O in del_gendisk Christoph Hellwig
2021-09-20 11:24 ` [PATCH 2/4] block: split bio_queue_enter from blk_queue_enter Christoph Hellwig
2021-09-21  3:25   ` Bart Van Assche

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=20210922172222.2453343-3-hch@lst.de \
    --to=hch@lst.de \
    --cc=axboe@kernel.dk \
    --cc=linux-block@vger.kernel.org \
    --cc=ming.lei@redhat.com \
    --cc=tj@kernel.org \
    --subject='Re: [PATCH 2/4] block: split bio_queue_enter from blk_queue_enter' \
    /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

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).