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Date: Mon, 23 Jul 2007 13:54:16 -0700
From: Christoph Lameter <clameter@sgi.com>
To: Hugh Dickins <hugh@veritas.com>
Cc: Jens Axboe <jens.axboe@oracle.com>, linux-kernel@vger.kernel.org,
       Andrew Morton <akpm@linux-foundation.org>, Adam Litke <agl@us.ibm.com>,
       David Gibson <david@gibson.dropbear.id.au>,
       Ken Chen <kenchen@google.com>, Bill Irwin <wli@holomorphy.com>
Subject: Re: [PATCH] Check for compound pages in set_page_dirty()
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On Thu, 19 Jul 2007 18:35:17 +0100 (BST)
Hugh Dickins <hugh@veritas.com> wrote:

> I didn't see any attention to set_page_dirty in Christoph's
> Large Blocksize (variable page_cachesize) patches, but I expect
> he'd also be wanting set_page_dirty to act on compound_head.

There is no need for special casing if set_page_dirty() is only
ever called for page heads. Make sure that direct I/O does not call
set_page_dirty for tail pages.

A VM_BUG_ON(PageTail(page)) could be used to make sure that this
does not happen in the future?