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Date: Tue, 22 Nov 2011 13:39:51 +0800
From: Cong Wang <amwang@redhat.com>
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To: Christoph Hellwig <hch@infradead.org>
CC: Kay Sievers <kay.sievers@vrfy.org>, linux-kernel@vger.kernel.org,
        akpm@linux-foundation.org, Pekka Enberg <penberg@kernel.org>,
        Hugh Dickins <hughd@google.com>, Dave Hansen <dave@linux.vnet.ibm.com>,
        Lennart Poettering <lennart@poettering.net>,
        KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>, linux-mm@kvack.org
Subject: Re: [V2 PATCH] tmpfs: add fallocate support
References: <1321612791-4764-1-git-send-email-amwang@redhat.com> <20111119100326.GA27967@infradead.org> <CAPXgP10q8Fba3vr0zf-XBBaRPwjP7MyJ=-QRL45_8WC-vtotOg@mail.gmail.com> <20111121100622.GA17887@infradead.org>
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于 2011年11月21日 18:06, Christoph Hellwig 写道:
> On Sat, Nov 19, 2011 at 03:14:48PM +0100, Kay Sievers wrote:
>> On Sat, Nov 19, 2011 at 11:03, Christoph Hellwig<hch@infradead.org>  wrote:
>>> On Fri, Nov 18, 2011 at 06:39:50PM +0800, Cong Wang wrote:
>>>> It seems that systemd needs tmpfs to support fallocate,
>>>> see http://lkml.org/lkml/2011/10/20/275. This patch adds
>>>> fallocate support to tmpfs.
>>>
>>> What for exactly? ??Please explain why preallocating on tmpfs would
>>> make any sense.
>>
>> To be able to safely use mmap(), regarding SIGBUS, on files on the
>> /dev/shm filesystem. The glibc fallback loop for -ENOSYS on fallocate
>> is just ugly.
>
> That is the kind of information which needs to be in the changelog.
>

I will fix the changelog.

Thanks, Christoph and Kay.