linux-kernel - Re: page_mkwrite caller is racy?

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Date:	Wed, 31 Jan 2007 12:18:53 +1100
From:	Nick Piggin <nickpiggin@...oo.com.au>
To:	Anton Altaparmakov <aia21@....ac.uk>
CC:	Mark Fasheh <mark.fasheh@...cle.com>,
	Hugh Dickins <hugh@...itas.com>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	Linux Memory Management <linux-mm@...ck.org>,
	David Howells <dhowells@...hat.com>,
	Andrew Morton <akpm@...l.org>
Subject: Re: page_mkwrite caller is racy?

Anton Altaparmakov wrote:
> On Mon, 29 Jan 2007, Mark Fasheh wrote:
> 
>>
>>No page lock please. Generally, Ocfs2 wants to order cluster locks outside
>>of page locks. Also, the sparse b-tree support I'm working on right now will
>>need to be able to allocate in ->page_mkwrite() which would become very
>>nasty if we came in with the page lock - aside from the additional cluster
>>locks taken, ocfs2 will want to zero some adjacent pages (because we support
>>atomic allocation up to 1 meg).
> 
> 
> Ditto for NTFS.  I will need to lock pages on both sides of the page for 
> large volume cluster sizes thus I will have to drop the page lock if it is 
> already taken so it might as well not be...  Although I do not feel 
> strongly about it.  If the page is locked I will just drop the lock and 
> then take it again.  If possible to not have the page locked that would 
> make my code a little easier/more efficient I expect...

OK, that makes sense. Thanks to you both.

-- 
SUSE Labs, Novell Inc.
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