From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from relay.sgi.com (relay3.corp.sgi.com [198.149.34.15]) by oss.sgi.com (Postfix) with ESMTP id BD80F7CA0 for ; Thu, 9 Jun 2016 12:46:02 -0500 (CDT) Received: from cuda.sgi.com (cuda1.sgi.com [192.48.157.11]) by relay3.corp.sgi.com (Postfix) with ESMTP id 47D16AC002 for ; Thu, 9 Jun 2016 10:46:02 -0700 (PDT) Received: from userp1040.oracle.com (userp1040.oracle.com [156.151.31.81]) by cuda.sgi.com with ESMTP id J4D8igDfQvuT0CWG (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO) for ; Thu, 09 Jun 2016 10:46:00 -0700 (PDT) Date: Thu, 9 Jun 2016 10:45:51 -0700 From: "Darrick J. Wong" Subject: Re: [RFC] allow enabling reflinks at runtime Message-ID: <20160609174551.GD10371@birch.djwong.org> References: <1464877150-20457-1-git-send-email-hch@lst.de> <20160602225415.GP12670@dastard> <20160608071130.GB24663@lst.de> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20160608071130.GB24663@lst.de> List-Id: XFS Filesystem from SGI List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: xfs-bounces@oss.sgi.com Sender: xfs-bounces@oss.sgi.com To: Christoph Hellwig Cc: xfs@oss.sgi.com On Wed, Jun 08, 2016 at 09:11:30AM +0200, Christoph Hellwig wrote: > On Fri, Jun 03, 2016 at 08:54:15AM +1000, Dave Chinner wrote: > > On Thu, Jun 02, 2016 at 04:19:07PM +0200, Christoph Hellwig wrote: > > > I've had some vocal user requests to allow enabling reflinks at run time, > > > which happens to be a mostly trivial feature. The only caveat is that we > > > need a large enough log size to support the reflink requirements, but for > > > typical large file systems that's not an issue. > > > > Hmmm - how does this interact with all the rmap code? I was not > > planning on enabling reflink without rmap and vice versa simply > > because it makes the validation and testing matrix vastly more > > complex. > > Uh. So far I've only been testing pure reflink code, mostly because > rmap really doesn't buy much for the use case I'm working on. So far I've mostly been testing with mkfs.xfs -i sparse=1 -m rmapbt=1,reflink=1 on the assumption that sparse will get turned on soon and that it might help a lot in the post-COW fragmentation world. (Hoping that the cowextsize defaults avoid most of the horrifying fragmentation that we see on the second- and last-letter filesystems.) > Enabling rmap post-mkfs is defintively a different ballpark, and probably > not worth it even if it would be doable. Hughflgrgh. I wasn't even going to consider /that/ possibility. :) (I guess you could flip on the feature bit and run xfs_repair...) --D _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs