From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from verein.lst.de ([213.95.11.211]:58658 "EHLO newverein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726219AbfBTO61 (ORCPT ); Wed, 20 Feb 2019 09:58:27 -0500 Date: Wed, 20 Feb 2019 15:58:25 +0100 From: Christoph Hellwig Subject: Re: [PATCH 8/8] xfs: introduce an always_cow mode Message-ID: <20190220145825.GA27724@lst.de> References: <20190218091827.12619-1-hch@lst.de> <20190218091827.12619-9-hch@lst.de> <20190219052545.GG32253@magnolia> <20190219175358.GH32253@magnolia> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190219175358.GH32253@magnolia> Sender: linux-xfs-owner@vger.kernel.org List-ID: List-Id: xfs To: "Darrick J. Wong" Cc: Christoph Hellwig , linux-xfs@vger.kernel.org On Tue, Feb 19, 2019 at 09:53:58AM -0800, Darrick J. Wong wrote: > xfsrestore tries to RESVSP space for its index file and fails, > presumably because the vfs intercepts the RESVSP ioctl and calls > vfs_fallocate. But then xfsrestore seems to run ALLOCSP, which afaict > succeeds... ? s/ALLOCSP/fallocate/ I think. But not, fallocate on an always_cow inode does not work, because it can't (modulo the non-persistent delalloc only idea from Dave). > > Two questions: > > - Are you going to mask off xfs_ioc_space from alwayscow inodes like you > did for xfs_file_fallocate? xfs_ioc_space does a few different things: - it contains a RESVP implementation that actually is dead code, as the VFS takes care of it. - it contains a UNRESVSP implementation, this is supported by always_cow - it contains a ZERO_RANGE implementation, also supported by always_cow So nothing to do there. > - What are we going to do for xfsrestore if it encounters a filesystem > where everything is alwayscow? > > > xfs/205 > > "disk full, expected" ? > > /me wonders, since this is an ENOSPC test, why would it fail if we run > out of space. As far as I can tell because we run out of space too early due to the transient double block usage due to the COW writes.