Date: Thu, 31 May 2007 18:24:40 -0700
From: Mark Fasheh <mark.fasheh@oracle.com>
To: Nick Piggin <npiggin@suse.de>
Cc: Andrew Morton <akpm@linux-foundation.org>, linux-kernel@vger.kernel.org
Subject: Re: 2.6.22-rc3-mm1 - page_mkwrite() breakage
Message-ID: <20070601012440.GS20632@ca-server1.us.oracle.com>
Reply-To: Mark Fasheh <mark.fasheh@oracle.com>
References: <20070530235823.793f00d9.akpm@linux-foundation.org> <20070531231354.GR20632@ca-server1.us.oracle.com> <20070601010129.GA15878@wotan.suse.de>
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On Fri, Jun 01, 2007 at 03:01:29AM +0200, Nick Piggin wrote:
> Ah, I didn't realise you were using that yet. I expect ocfs2 is using
> VM_CAN_INVALIDATE there anyway.
> 
> Hmm, this becomes easier to deal with after page_mkwrite is merged with
> ->fault. But for now, can we just lock the page at the do_wp_page site
> as well, and change the API? All users I have seen want the page locked
> there anyway...

Unfortunately that doesn't work for ocfs2 for exactly the same reasons page
lock doesn't work during a write either - there's a cluster lock inversion
and we might have to zero adjacent pages for an allocating write.

What's involved in merging it with ->fault?

Here's a nasty idea... Would it be valid for ->page_mkwrite to unlock the
page, so long as it's returned in a locked state? Though, do we even need
the page lock that early? It seemed to me that you were adding it for
consistency reasons (I could be wrong though).
	--Mark

--
Mark Fasheh
Senior Software Developer, Oracle
mark.fasheh@oracle.com
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