From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S265242AbTLLOCK (ORCPT ); Fri, 12 Dec 2003 09:02:10 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S265245AbTLLOCI (ORCPT ); Fri, 12 Dec 2003 09:02:08 -0500 Received: from thebsh.namesys.com ([212.16.7.65]:11913 "HELO thebsh.namesys.com") by vger.kernel.org with SMTP id S265242AbTLLOCC (ORCPT ); Fri, 12 Dec 2003 09:02:02 -0500 Subject: Re: Is there a "make hole" (truncate in middle) syscall? From: Vladimir Saveliev To: Rob Landley Cc: linux-kernel@vger.kernel.org In-Reply-To: <200312120753.11906.rob@landley.net> References: <20031211125806.B2422@hexapodia.org> <20031212125513.GC6112@wohnheim.fh-wedel.de> <1071235698.27730.146.camel@tribesman.namesys.com> <200312120753.11906.rob@landley.net> Content-Type: text/plain; charset=ISO-8859-1 Message-Id: <1071237719.27730.158.camel@tribesman.namesys.com> Mime-Version: 1.0 X-Mailer: Ximian Evolution 1.4.4 Date: Fri, 12 Dec 2003 17:01:59 +0300 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 2003-12-12 at 16:53, Rob Landley wrote: > On Friday 12 December 2003 07:28, Vladimir Saveliev wrote: > > Hi > > > > On Fri, 2003-12-12 at 15:55, Jörn Engel wrote: > > > On Thu, 11 December 2003 14:32:12 -0600, Rob Landley wrote: > > > > On Thursday 11 December 2003 13:48, Jörn Engel wrote: > > > > > If you really do it, please don't add a syscall for it. Simply check > > > > > each written page if it is completely filled with zero. (This will > > > > > be a very quick check for most pages, as they will contain something > > > > > nonzero in the first couple of words) > > > > > > > > Cache poisoning, streaming writes to large RAID arrays... There are > > > > about 8 zllion reasons not to do this. Really. (It defeats the whole > > > > purpose of DMA, doesn't it?) > > > > Sorry, > > but doesn't truncate do almost exactly what "make hole" is supposed to > > do? > > I have a 2 gigabyte file. I want to punch a hole from 257 megabytes to 364 > megabytes, saving over 100 megs of disk space. I do NOT want to have to copy > off and rewrite 1.6 gigabytes of data from the end of the file. (There may > not even be enough room on the disk, and it would take a long time anyway.) > ok. But I asked why would "make hole" have problems you list (8 zillions) and truncate would not have them? > No, it doesn't do the same thing. Truncate is always to end of file. Punch > hole is like a write, it takes a length. lseek(pos), punch(length). > > Rob > - > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ >