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Date: Tue, 31 Jan 2012 19:42:56 +0800
From: Wu Fengguang <wfg@linux.intel.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: Shaohua Li <shaohua.li@intel.com>, lkml <linux-kernel@vger.kernel.org>,
        linux-mm <linux-mm@kvack.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Jens Axboe <axboe@kernel.dk>, Herbert Poetzl <herbert@13thfloor.at>,
        Eric Dumazet <eric.dumazet@gmail.com>, Vivek Goyal <vgoyal@redhat.com>
Subject: Re: [PATCH] fix readahead pipeline break caused by block plug
Message-ID: <20120131114256.GA8796@localhost>
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On Tue, Jan 31, 2012 at 06:34:52AM -0500, Christoph Hellwig wrote:
> On Tue, Jan 31, 2012 at 06:57:54PM +0800, Wu Fengguang wrote:
> > The problem is, there are a dozen of ->direct_IO callback functions.
> > While there are only two ->direct_IO() callers, one for READ and
> > another for WRITE, which are much easier to deal with.
> 
> So what?  Better do a bit more work now and keep the damn thing
> maintainable.

What if we add a wrapper function for doing

        blk_start_plug(&plug);
        ->direct_IO()
        blk_finish_plug(&plug);

Thanks,
Fengguang