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Date: Thu, 24 Nov 2011 11:15:50 +0800
From: Cong Wang <amwang@redhat.com>
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To: Hugh Dickins <hughd@google.com>
CC: Pekka Enberg <penberg@kernel.org>,
        KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
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        Lennart Poettering <lennart@poettering.net>,
        Kay Sievers <kay.sievers@vrfy.org>, linux-mm@kvack.org
Subject: Re: [V3 PATCH 1/2] tmpfs: add fallocate support
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于 2011年11月24日 06:20, Hugh Dickins 写道:
> On Wed, 23 Nov 2011, Pekka Enberg wrote:
>>
>> Why do we need to undo anyway?
...
> Another answer would be: if fallocate() had been defined to return
> the length that has been successfully allocated (as write() returns
> the length written), then it would be reasonable to return partial
> length instead of failing with ENOSPC, and not undo.  But it was
> defined to return -1 on failure or 0 on success, so cannot report
> partial success.
>
> Another answer would be: if the disk is near full, it's not good
> for a fallocate() to fail with -ENOSPC while nonetheless grabbing
> all the remaining blocks; even worse if another fallocate() were
> racing with it.

Exactly, fallocate() should not make the bad situation even worse.

Thanks.