From: Dave Chinner <david@fromorbit.com>
To: Josef Bacik <josef@redhat.com>
Cc: linux-btrfs@vger.kernel.org, linux-fsdevel@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-mm@vger.kernel.org
Subject: Re: [PATCH 1/3] fs: allow short direct-io reads to be completed via buffered IO
Date: Tue, 4 May 2010 10:14:18 +1000 [thread overview]
Message-ID: <20100504001418.GH2591@dastard> (raw)
In-Reply-To: <20100503172702.GB3961@localhost.localdomain>
On Mon, May 03, 2010 at 01:27:02PM -0400, Josef Bacik wrote:
> This is similar to what already happens in the write case. If we have a short
> read while doing O_DIRECT, instead of just returning, fallthrough and try to
> read the rest via buffered IO. BTRFS needs this because if we encounter a
> compressed or inline extent during DIO, we need to fallback on buffered. If the
> extent is compressed we need to read the entire thing into memory and
> de-compress it into the users pages. I have tested this with fsx and everything
> works great. Thanks,
Won't this mean that any direct IO read that spans EOF (i.e. get a
short read) now attempt a buffered IO (that will fail) before returning?
Cheers,
Dave.
--
Dave Chinner
david@fromorbit.com
next prev parent reply other threads:[~2010-05-04 0:14 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-05-03 17:27 [PATCH 1/3] fs: allow short direct-io reads to be completed via buffered IO Josef Bacik
2010-05-04 0:14 ` Dave Chinner [this message]
2010-05-04 15:27 ` Josef Bacik
2010-05-04 23:07 ` Dave Chinner
-- strict thread matches above, loose matches on Subject: below --
2010-05-03 16:11 Josef Bacik
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