From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from verein.lst.de ([213.95.11.211]:51679 "EHLO newverein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726044AbeISLQg (ORCPT ); Wed, 19 Sep 2018 07:16:36 -0400 Date: Wed, 19 Sep 2018 07:40:22 +0200 From: Christoph Hellwig Subject: Re: delalloc and reflink fixes & tweaks Message-ID: <20180919054022.GA19507@lst.de> References: <20180917205354.15401-1-hch@lst.de> <20180917212323.GF16550@dastard> <20180918181728.GA7171@lst.de> <20180918230057.GK27618@dastard> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180918230057.GK27618@dastard> Sender: linux-xfs-owner@vger.kernel.org List-ID: List-Id: xfs To: Dave Chinner Cc: Christoph Hellwig , linux-xfs@vger.kernel.org On Wed, Sep 19, 2018 at 09:00:57AM +1000, Dave Chinner wrote: > > Careful. We already have issues because delalloc blocks before EOF don't > > ever get reclaimed. This triggers up on xfs/442 with 1k blocksize for > > me. I actually have a fix for that now, but that will require dropping > > one of the cleanup patches from this series, so expect a respin. > > Yeah, I didn't say everything already worked, just that using > preallocation for delalloc gets rid of the stale data exposure > problem that has prevented us from doing this in the past. And I think I have to do the mark preallocations as unwritten now given that my other fix idea that I wasted the whole day on yesterday didn't turn out to actually work properly. Sigh.. > That's sounds like a good idea, and a good direction to head > towards. No immediate hurry, just trying to understand where you > might be going with these changes. I've been working on adding (or resurrecting) and always_cow mode, which helped to expose all kinds of interesting bugs. That mode again will be that base for atomic writes (including safe overwrites) and a zone block device (aka SMR) mode that also can't write in place.