linux-kernel - Re: [PATCH 1/3] direct-io: make O

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Message-Id: <1250773693.5352.24.camel@heimdal.trondhjem.org>
Date:	Thu, 20 Aug 2009 09:08:13 -0400
From:	Trond Myklebust <Trond.Myklebust@...app.com>
To:	Jens Axboe <jens.axboe@...cle.com>
Cc:	linux-kernel@...r.kernel.org, zach.brown@...cle.com
Subject: Re: [PATCH 1/3] direct-io: make O_DIRECT IO path be page based

On Mon, 2009-08-17 at 14:11 +0200, Jens Axboe wrote:
> On Mon, Aug 17 2009, Jens Axboe wrote:
> > Switch the aops->direct_IO() and below code to use page arrays
> > instead, so that it doesn't make any assumptions about who the pages
> > belong to. This works directly for all users but NFS, which just
> > uses the same helper that the generic mapping read/write functions
> > also call.
> 
> A quick NFS test reveals a simple problem - it wants to free the
> pagevec on IO completion, but for O_DIRECT it should not do that anymore
> since it'll simply inherit the given page map.
> 
> There's a flag structure in the nfs_{read,write}_data structure, but I
> was not able to find out which flags (if any?!) it actually uses. So I
> just stuck an int in there. Trond?

Why not just have O_DIRECT reset the pagevec before freeing the
structure?

Cheers
  Trond
-- 
Trond Myklebust
Linux NFS client maintainer

NetApp
Trond.Myklebust@...app.com
www.netapp.com
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