Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758816AbXFZPee (ORCPT ); Tue, 26 Jun 2007 11:34:34 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1758726AbXFZPeT (ORCPT ); Tue, 26 Jun 2007 11:34:19 -0400 Received: from mail.clusterfs.com ([206.168.112.78]:55774 "EHLO mail.clusterfs.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758710AbXFZPeQ (ORCPT ); Tue, 26 Jun 2007 11:34:16 -0400 Date: Tue, 26 Jun 2007 11:34:13 -0400 From: Andreas Dilger To: "Amit K. Arora" 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: <20070626153413.GC6652@schatzie.adilger.int> Mail-Followup-To: "Amit K. Arora" , 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 References: <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> <20070626103247.GA19870@amitarora.in.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20070626103247.GA19870@amitarora.in.ibm.com> User-Agent: Mutt/1.4.1i X-GPG-Key: 1024D/0D35BED6 X-GPG-Fingerprint: 7A37 5D79 BF1B CECA D44F 8A29 A488 39F5 0D35 BED6 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1772 Lines: 38 On Jun 26, 2007 16:02 +0530, Amit K. Arora wrote: > On Mon, Jun 25, 2007 at 03:46:26PM -0600, Andreas Dilger wrote: > > 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. Since I believe the XFS allocation ioctls do it the opposite way (free preallocated space on error) this should be encoded into the flags. Having it "filesystem dependent" just means that nobody will be happy. > > 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. What I mean is that any data read from the file should have the "appearance" of being zeroed (whether zeroes are actually written to disk or not). What I _think_ David is proposing is to allow fallocate() to return without marking the blocks even "uninitialized" and subsequent reads would return the old data from the disk. Cheers, Andreas -- Andreas Dilger Principal Software Engineer Cluster File Systems, Inc. - 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/