Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756510AbXFZKcw (ORCPT ); Tue, 26 Jun 2007 06:32:52 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752491AbXFZKcm (ORCPT ); Tue, 26 Jun 2007 06:32:42 -0400 Received: from e4.ny.us.ibm.com ([32.97.182.144]:53617 "EHLO e4.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752373AbXFZKck (ORCPT ); Tue, 26 Jun 2007 06:32:40 -0400 Date: Tue, 26 Jun 2007 16:02:47 +0530 From: "Amit K. Arora" To: Andreas Dilger Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-ext4@vger.kernel.org, David Chinner , suparna@in.ibm.com, cmm@us.ibm.com, xfs@oss.sgi.com Subject: Re: [PATCH 4/7][TAKE5] support new modes in fallocate Message-ID: <20070626103247.GA19870@amitarora.in.ibm.com> References: <20070512080157.GF85884050@sgi.com> <20070612061652.GA6320@amitarora.in.ibm.com> <20070613235217.GS86004887@sgi.com> <20070614091458.GH5181@schatzie.adilger.int> <20070614120413.GD86004887@sgi.com> <20070614193347.GN5181@schatzie.adilger.int> <20070625132810.GA1951@amitarora.in.ibm.com> <20070625134500.GE1951@amitarora.in.ibm.com> <20070625150320.GA8686@amitarora.in.ibm.com> <20070625214626.GJ5181@schatzie.adilger.int> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20070625214626.GJ5181@schatzie.adilger.int> User-Agent: Mutt/1.4.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1706 Lines: 35 On Mon, Jun 25, 2007 at 03:46:26PM -0600, Andreas Dilger wrote: > On Jun 25, 2007 20:33 +0530, Amit K. Arora wrote: > > I have not implemented FA_FL_FREE_ENOSPC and FA_ZERO_SPACE flags yet, as > > *suggested* by Andreas in http://lkml.org/lkml/2007/6/14/323 post. > > If it is decided that these flags are also needed, I will update this > > patch. Thanks! > > Can you clarify - what is the current behaviour when ENOSPC (or some other > error) is hit? Does it keep the current fallocate() or does it free it? Currently it is left on the file system implementation. In ext4, we do not undo preallocation if some error (say, ENOSPC) is hit. Hence it may end up with partial (pre)allocation. This is inline with dd and posix_fallocate, which also do not free the partially allocated space. > For FA_ZERO_SPACE - I'd think this would (IMHO) be the default - we > don't want to expose uninitialized disk blocks to userspace. I'm not > sure if this makes sense at all. I don't think we need to make it default - atleast for filesystems which have a mechanism to distinguish preallocated blocks from "regular" ones. In ext4, for example, we will have a way to mark uninitialized extents. All the preallocated blocks will be part of these uninitialized extents. And any read on these extents will treat them as a hole, returning zeroes to user land. Thus any existing data on uninitialized blocks will not be exposed to the userspace. -- Regards, Amit Arora - 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/