Received: with ECARTIS (v1.0.0; list linux-xfs); Tue, 15 Nov 2005 13:09:33 -0800 (PST) Received: from larry.melbourne.sgi.com (mverd138.asia.info.net [61.14.31.138]) by oss.sgi.com (8.12.10/8.12.10/SuSE Linux 0.7) with SMTP id jAFL9SO0000522 for ; Tue, 15 Nov 2005 13:09:29 -0800 Received: from wobbly.melbourne.sgi.com (wobbly.melbourne.sgi.com [134.14.55.135]) by larry.melbourne.sgi.com (950413.SGI.8.6.12/950213.SGI.AUTOCF) via ESMTP id IAA15720; Wed, 16 Nov 2005 08:05:59 +1100 Received: from wobbly.melbourne.sgi.com (localhost [127.0.0.1]) by wobbly.melbourne.sgi.com (SGI-8.12.5/8.12.5) with ESMTP id jAFL69kt6654817; Wed, 16 Nov 2005 08:06:09 +1100 (EST) Received: (from nathans@localhost) by wobbly.melbourne.sgi.com (SGI-8.12.5/8.12.5/Submit) id jAFL67U46672401; Wed, 16 Nov 2005 08:06:07 +1100 (EST) Date: Wed, 16 Nov 2005 08:06:06 +1100 From: Nathan Scott To: Roger Willcocks , Steve Lord Cc: linux-xfs@oss.sgi.com Subject: Re: clearing 'flag unwritten extents' Message-ID: <20051116080606.B6643249@wobbly.melbourne.sgi.com> References: <20051111073434.B6484324@wobbly.melbourne.sgi.com> <20051114091337.P6499030@wobbly.melbourne.sgi.com> <4379FDDE.2040807@xfs.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5i In-Reply-To: <4379FDDE.2040807@xfs.org>; from lord@xfs.org on Tue, Nov 15, 2005 at 09:25:18AM -0600 X-archive-position: 6569 X-ecartis-version: Ecartis v1.0.0 Sender: linux-xfs-bounce@oss.sgi.com Errors-to: linux-xfs-bounce@oss.sgi.com X-original-sender: nathans@sgi.com Precedence: bulk X-list: linux-xfs Content-Length: 1061 Lines: 27 On Tue, Nov 15, 2005 at 09:25:18AM -0600, Steve Lord wrote: > Roger Willcocks wrote: > > On 11/13/05, Nathan Scott wrote: > >> On Fri, Nov 11, 2005 at 12:48:48PM +0000, Roger Willcocks wrote: > >>> AIUI, the 'flag unwritten extents' option allows non-root users to > >>> preallocate unwritten extents (root can always create them). Clearing > >>> the option would just prevent the creation of new unwritten extents. > >> It does more than just that - in xfs_bmapi it changes the way > >> extents are handled - look for XFS_SB_VERSION_HASEXTFLGBIT in > >> xfs_bmap.c in particular. > > > > But only for realtime extents - and I don't have any of those... Not only realtime - look more closely in xfs_bmapi(). > Nope, unwritten extents exist in the main part of the filesystem too. > They are not always used, but they are not just for realtime files. *nod*. They are a Good Thing (tm), although the current code implementing them on Linux is pretty horrible - that will get alot better in the not-too-distant future. cheers. -- Nathan