From: Cong Wang <amwang@redhat.com>
To: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
linux-kernel@vger.kernel.org, akpm@linux-foundation.org,
Pekka Enberg <penberg@kernel.org>, Christoph Hellwig <hch@lst.de>,
Hugh Dickins <hughd@google.com>,
Dave Hansen <dave@linux.vnet.ibm.com>,
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
Date: Thu, 24 Nov 2011 11:22:34 +0800 [thread overview]
Message-ID: <4ECDB87A.90106@redhat.com> (raw)
In-Reply-To: <20111124120126.9361b2c9.kamezawa.hiroyu@jp.fujitsu.com>
于 2011年11月24日 11:01, KAMEZAWA Hiroyuki 写道:
> On Wed, 23 Nov 2011 21:46:39 -0500
> KOSAKI Motohiro<kosaki.motohiro@jp.fujitsu.com> wrote:
>
>>>> + while (index< end) {
>>>> + ret = shmem_getpage(inode, index,&page, SGP_WRITE, NULL);
>>>
>>> If the 'page' for index exists before this call, this will return the page without
>>> allocaton.
>>>
>>> Then, the page may not be zero-cleared. I think the page should be zero-cleared.
>>
>> No. fallocate shouldn't destroy existing data. It only ensure
>> subsequent file access don't make ENOSPC error.
>>
> FALLOC_FL_KEEP_SIZE
> This flag allocates and initializes to zero the disk space
> within the range specified by offset and len. ....
>
> just manual is unclear ? it seems that the range [offset, offset+len) is
> zero cleared after the call.
I think we should fix the man page, because at least ext4 doesn't clear
the original contents,
% echo hi > /tmp/foobar
% fallocate -n -l 1 -o 10 /tmp/foobar
% hexdump -Cv /tmp/foobar
00000000 68 69 0a |hi.|
00000003
next prev parent reply other threads:[~2011-11-24 3:23 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-11-23 8:53 [V3 PATCH 1/2] tmpfs: add fallocate support Cong Wang
2011-11-23 8:53 ` [PATCH 2/2] fs: wire up .truncate_range and .fallocate Cong Wang
2011-11-23 10:38 ` Christoph Hellwig
2011-11-23 19:16 ` Hugh Dickins
2011-11-23 9:06 ` [V3 PATCH 1/2] tmpfs: add fallocate support Pekka Enberg
2011-11-23 19:07 ` Hugh Dickins
2011-11-24 3:18 ` Cong Wang
2011-11-23 19:59 ` KOSAKI Motohiro
2011-11-23 21:11 ` Pekka Enberg
2011-11-23 22:20 ` Hugh Dickins
2011-11-24 3:15 ` Cong Wang
2011-11-24 1:52 ` KAMEZAWA Hiroyuki
2011-11-24 2:46 ` KOSAKI Motohiro
2011-11-24 3:01 ` KAMEZAWA Hiroyuki
2011-11-24 3:22 ` Cong Wang [this message]
2011-11-24 4:23 ` KAMEZAWA Hiroyuki
2011-11-24 5:52 ` Cong Wang
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