From: Alex Elder <aelder@sgi.com>
To: Dave Chinner <david@fromorbit.com>
Cc: xfs@oss.sgi.com
Subject: Re: [PATCH 2/3] xfs: serialise unaligned direct IO into unwritten extents
Date: Fri, 23 Jul 2010 10:30:04 -0500 [thread overview]
Message-ID: <1279899004.1983.87.camel@doink> (raw)
In-Reply-To: <1279881678-1660-3-git-send-email-david@fromorbit.com>
On Fri, 2010-07-23 at 20:41 +1000, Dave Chinner wrote:
> From: Dave Chinner <dchinner@redhat.com>
>
> If we do unaligned direct IO to a unwritten extent, the direct Io
> code does sub-block zeroing for us. However, we need to serialise
> the sub-block zeroing as we canot have another outstanding IO to the
> same block that is being zeroed at the same time. Ifw e do so, then
> we'll have two direct IOs to the same block that zero different
> portions of the block and we'll end up with zeros where we should
> have data.
>
> Serialise such IOs in the get_blocks callback when we know that we
> are mapping an unaligned direct IO. This initial implementation is
> the sledge-hammer approach - we can probably be finer grained than
> this to avoid excessive serialisation when all IO is unaligned to a
> file.
>
> Signed-off-by: Dave Chinner <dchinner@redhat.com>
Looks good.
Reviewed-by: Alex Elder <aelder@sgi.com>
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next prev parent reply other threads:[~2010-07-23 15:28 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-07-23 10:41 [RFC, PATCH 0/3] serialise concurrent direct IO sub-block zeroing Dave Chinner
2010-07-23 10:41 ` [PATCH 1/3] fs: get_blocks needs an unaligned mapping flag Dave Chinner
2010-07-23 15:29 ` Alex Elder
2010-07-23 10:41 ` [PATCH 2/3] xfs: serialise unaligned direct IO into unwritten extents Dave Chinner
2010-07-23 15:30 ` Alex Elder [this message]
2010-07-23 10:41 ` [PATCH 3/3] xfs: wait on IO completion inside an IO context Dave Chinner
2010-07-23 15:30 ` Alex Elder
2010-07-23 19:20 ` [RFC, PATCH 0/3] serialise concurrent direct IO sub-block zeroing Eric Sandeen
2010-07-24 0:09 ` Dave Chinner
2010-07-24 11:12 ` Alex Elder
2010-07-25 11:37 ` Dave Chinner
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