From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail203.messagelabs.com (mail203.messagelabs.com [216.82.254.243]) by kanga.kvack.org (Postfix) with ESMTP id 9DDA26B006C for ; Mon, 21 Nov 2011 05:06:40 -0500 (EST) Date: Mon, 21 Nov 2011 05:06:22 -0500 From: Christoph Hellwig Subject: Re: [V2 PATCH] tmpfs: add fallocate support Message-ID: <20111121100622.GA17887@infradead.org> References: <1321612791-4764-1-git-send-email-amwang@redhat.com> <20111119100326.GA27967@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org List-ID: To: Kay Sievers Cc: Christoph Hellwig , Cong Wang , linux-kernel@vger.kernel.org, akpm@linux-foundation.org, Pekka Enberg , Hugh Dickins , Dave Hansen , Lennart Poettering , KOSAKI Motohiro , linux-mm@kvack.org On Sat, Nov 19, 2011 at 03:14:48PM +0100, Kay Sievers wrote: > On Sat, Nov 19, 2011 at 11:03, Christoph Hellwig 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. -- 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 From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755478Ab1KUKG2 (ORCPT ); Mon, 21 Nov 2011 05:06:28 -0500 Received: from 173-166-109-252-newengland.hfc.comcastbusiness.net ([173.166.109.252]:39161 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754157Ab1KUKG1 (ORCPT ); Mon, 21 Nov 2011 05:06:27 -0500 Date: Mon, 21 Nov 2011 05:06:22 -0500 From: Christoph Hellwig To: Kay Sievers Cc: Christoph Hellwig , Cong Wang , linux-kernel@vger.kernel.org, akpm@linux-foundation.org, Pekka Enberg , Hugh Dickins , Dave Hansen , Lennart Poettering , KOSAKI Motohiro , linux-mm@kvack.org Subject: Re: [V2 PATCH] tmpfs: add fallocate support Message-ID: <20111121100622.GA17887@infradead.org> References: <1321612791-4764-1-git-send-email-amwang@redhat.com> <20111119100326.GA27967@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Nov 19, 2011 at 03:14:48PM +0100, Kay Sievers wrote: > On Sat, Nov 19, 2011 at 11:03, Christoph Hellwig 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.