From: Christoph Hellwig <hch@infradead.org>
To: Josef Bacik <josef@redhat.com>
Cc: linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-fsdevel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH 1/3] fs: allow short direct-io reads to be completed via buffered IO V2
Date: Thu, 6 May 2010 17:10:12 -0400 [thread overview]
Message-ID: <20100506211012.GD2997@infradead.org> (raw)
In-Reply-To: <20100506190012.GB13974@dhcp231-156.rdu.redhat.com>
On Thu, May 06, 2010 at 03:00:13PM -0400, Josef Bacik wrote:
> V1->V2: Check to see if our current ppos is >= i_size after a short DIO read,
> just in case it was actually a short read and we need to just return.
>
> 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,
This seems safe to me, but I'm a bit worried about potential breakages.
Did you test this with xfsqa on xfs and ext3/4 to make sure there are
no regressions?
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prev parent reply other threads:[~2010-05-06 21:10 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-05-06 19:00 [PATCH 1/3] fs: allow short direct-io reads to be completed via buffered IO V2 Josef Bacik
2010-05-06 21:10 ` Christoph Hellwig [this message]
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