From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail6.bemta12.messagelabs.com (mail6.bemta12.messagelabs.com [216.82.250.247]) by kanga.kvack.org (Postfix) with ESMTP id D85926B00AA for ; Wed, 23 Nov 2011 22:22:56 -0500 (EST) Message-ID: <4ECDB87A.90106@redhat.com> Date: Thu, 24 Nov 2011 11:22:34 +0800 From: Cong Wang MIME-Version: 1.0 Subject: Re: [V3 PATCH 1/2] tmpfs: add fallocate support References: <1322038412-29013-1-git-send-email-amwang@redhat.com> <20111124105245.b252c65f.kamezawa.hiroyu@jp.fujitsu.com> <20111124120126.9361b2c9.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <20111124120126.9361b2c9.kamezawa.hiroyu@jp.fujitsu.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Sender: owner-linux-mm@kvack.org List-ID: To: KAMEZAWA Hiroyuki Cc: KOSAKI Motohiro , linux-kernel@vger.kernel.org, akpm@linux-foundation.org, Pekka Enberg , Christoph Hellwig , Hugh Dickins , Dave Hansen , Lennart Poettering , Kay Sievers , linux-mm@kvack.org ao? 2011a1'11ae??24ae?JPY 11:01, KAMEZAWA Hiroyuki a??e??: > On Wed, 23 Nov 2011 21:46:39 -0500 > KOSAKI Motohiro 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 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org