linux-kernel - Re: [PATCH v2 0/7] Change page reference handling semantic of page cache

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Date:	Wed, 5 Jan 2011 13:53:04 +0900
From:	Minchan Kim <minchan.kim@...il.com>
To:	balbir@...ux.vnet.ibm.com
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	linux-mm <linux-mm@...ck.org>,
	LKML <linux-kernel@...r.kernel.org>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	Hugh Dickins <hughd@...gle.com>
Subject: Re: [PATCH v2 0/7] Change page reference handling semantic of page cache

Hi Balbir,

On Wed, Jan 5, 2011 at 1:18 AM, Balbir Singh <balbir@...ux.vnet.ibm.com> wrote:
> * MinChan Kim <minchan.kim@...il.com> [2011-01-03 00:44:29]:
>
>> Now we increases page reference on add_to_page_cache but doesn't decrease it
>> in remove_from_page_cache. Such asymmetric makes confusing about
>> page reference so that caller should notice it and comment why they
>> release page reference. It's not good API.
>>
>> Long time ago, Hugh tried it[1] but gave up of reason which
>> reiser4's drop_page had to unlock the page between removing it from
>> page cache and doing the page_cache_release. But now the situation is
>> changed. I think at least things in current mainline doesn't have any
>> obstacles. The problem is fs or somethings out of mainline.
>> If it has done such thing like reiser4, this patch could be a problem but
>> they found it when compile time since we remove remove_from_page_cache.
>>
>> [1] http://lkml.org/lkml/2004/10/24/140
>>
>> The series configuration is following as.
>>
>> [1/7] : This patch introduces new API delete_from_page_cache.
>> [2,3,4,5/7] : Change remove_from_page_cache with delete_from_page_cache.
>> Intentionally I divide patch per file since someone might have a concern
>> about releasing page reference of delete_from_page_cache in
>> somecase (ex, truncate.c)
>> [6/7] : Remove old API so out of fs can meet compile error when build time
>> and can notice it.
>> [7/7] : Change __remove_from_page_cache with __delete_from_page_cache, too.
>> In this time, I made all-in-one patch because it doesn't change old behavior
>> so it has no concern. Just clean up patch.
>>
>
> Could you please describe any testing done, was it mostly functional?

I didn't test it since I think it's okay as a code review.
Do you find any faults or guess it?
Anyway, I should have tested it before sending patches.

we are now -rc8 and Andrew doesn't held a patch.
So I will test it until he grab a patch.

Thanks,

>
> --
>        Three Cheers,
>        Balbir
>



-- 
Kind regards,
Minchan Kim
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