From: Christoph Hellwig <hch@lst.de>
To: Ming Lei <ming.lei@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>, Jens Axboe <axboe@kernel.dk>,
Tejun Heo <tj@kernel.org>,
linux-block@vger.kernel.org
Subject: Re: [PATCH 3/4] block: drain file system I/O on del_gendisk
Date: Mon, 27 Sep 2021 14:04:41 +0200 [thread overview]
Message-ID: <20210927120441.GA25223@lst.de> (raw)
In-Reply-To: <YUwhPy1J8lzHQF77@T590>
On Thu, Sep 23, 2021 at 02:39:59PM +0800, Ming Lei wrote:
> > > After blk_mq_unfreeze_queue() returns, blk_try_enter_queue() will return
> > > true, so new FS I/O from opened bdev still won't be blocked, right?
> >
> > It won't be blocked by blk_mq_unfreeze_queue, but because the capacity
> > is set to 0 it still won't make it to the driver.
>
> One bio could be made & checked before set_capacity(0), then is
> submitted after blk_mq_unfreeze_queue() returns.
>
> blk_mq_freeze_queue_wait() doesn't always imply RCU grace period, for
> example, the .q_usage_counter may have been in atomic mode before
> calling blk_queue_start_drain() & blk_mq_freeze_queue_wait().
True, but this isn't really a new issue as we never had proper quiesce
behavior. I have a bunch of ideas of how to make this actually solid,
but none of them looks like 5.15 material.
next prev parent reply other threads:[~2021-09-27 12:14 UTC|newest]
Thread overview: 12+ 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 ` [PATCH 2/4] block: split bio_queue_enter from blk_queue_enter Christoph Hellwig
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 [this message]
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 3/4] block: drain file system I/O on del_gendisk Christoph Hellwig
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