From: Christoph Hellwig <hch@lst.de>
To: Ming Lei <ming.lei@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>, Jens Axboe <axboe@kernel.dk>,
linux-block@vger.kernel.org, linux-mm@kvack.org,
linux-xfs@vger.kernel.org, Changhui Zhong <czhong@redhat.com>
Subject: Re: [PATCH V2] block: avoid io timeout in case of sync polled dio
Date: Mon, 18 Apr 2022 07:12:34 +0200 [thread overview]
Message-ID: <20220418051234.GA3559@lst.de> (raw)
In-Reply-To: <YlqGZ7W9rg0eNt9A@T590>
On Sat, Apr 16, 2022 at 05:03:35PM +0800, Ming Lei wrote:
> > Yes. But not doing this automatically also means you keep easily
> > forgetting callsites. For example iomap still does not flush the plug
> > in your patch.
>
> It is reasonable for flush user(usually submission) to be responsible
> for finishing/flushing plug.
Well, I very much disagree here. blk_flush_plug is not a publіc,
exported API, and that is for a reason. A bio submission interface
that requires flushing the plug to be useful is rather broken.
> iomap is one good example to show this point, since it does flush the plug
> before call bio_poll(), see __iomap_dio_rw().
iomap does not do a manual plug flush anywhere.
iomap does finish the plug before polling, which makes sense.
Now of course __blkdev_direct_IO_simple doesn't even use a plug
to start with, so I'm wondering what plug this patch even tries
to flush?
next prev parent reply other threads:[~2022-04-18 5:12 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-15 3:47 [PATCH V2] block: avoid io timeout in case of sync polled dio Ming Lei
2022-04-15 5:18 ` Christoph Hellwig
2022-04-15 11:00 ` Ming Lei
2022-04-16 5:49 ` Christoph Hellwig
2022-04-16 9:03 ` Ming Lei
2022-04-18 5:12 ` Christoph Hellwig [this message]
2022-04-18 8:19 ` Ming Lei
2022-04-19 5:39 ` Christoph Hellwig
2022-04-19 7:47 ` Ming Lei
2022-04-19 8:15 ` Christoph Hellwig
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