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From: Christoph Hellwig <hch@infradead.org>
To: Bijan Mottahedeh <bijan.mottahedeh@oracle.com>
Cc: axboe@kernel.dk, linux-block@vger.kernel.org, io-uring@vger.kernel.org
Subject: Re: [PATCH 1/1] block: Manage bio references so the bio persists until necessary
Date: Thu, 30 Jan 2020 22:42:30 -0800	[thread overview]
Message-ID: <20200131064230.GA28151@infradead.org> (raw)
In-Reply-To: <1580441022-59129-2-git-send-email-bijan.mottahedeh@oracle.com>

On Thu, Jan 30, 2020 at 07:23:42PM -0800, Bijan Mottahedeh wrote:
> Get a reference to a bio, so it won't be freed if end_io() gets to
> it before submit_io() returns.  Defer the release of the first bio
> in a mult-bio request until the last end_io() since the first bio is
> embedded in the dio structure and must therefore persist through an
> entire multi-bio request.

Can you explain the issue a little more?

The initial bio is embedded into the dio, and will have a reference
until the bio_put call at the end of the function, so we can't have
a race for that one and won't ever need the refcount for the single
bio case.  Avoiding the atomic is pretty important for aio/uring
performance.

  reply	other threads:[~2020-01-31  6:42 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-31  3:23 [PATCH 0/1] block: Manage bio references so the bio persists until necessary Bijan Mottahedeh
2020-01-31  3:23 ` [PATCH 1/1] " Bijan Mottahedeh
2020-01-31  6:42   ` Christoph Hellwig [this message]
2020-01-31 18:08     ` Bijan Mottahedeh
2020-02-03  8:34       ` Christoph Hellwig
2020-02-03 21:07         ` Bijan Mottahedeh
2020-02-04  7:51           ` Christoph Hellwig
2020-02-04 20:59             ` Jens Axboe
2020-02-04 22:41               ` Bijan Mottahedeh
2020-02-24 23:32               ` Bijan Mottahedeh

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