From mboxrd@z Thu Jan 1 00:00:00 1970 From: jim owens Subject: Re: [Ocfs2-devel] [PATCH 1/3] fs: Document the reflink(2) system call. Date: Wed, 06 May 2009 13:50:08 -0400 Message-ID: <4A01CDD0.6090102@hp.com> References: <1241331303-23753-1-git-send-email-joel.becker@oracle.com> <1241331303-23753-2-git-send-email-joel.becker@oracle.com> <20090505010703.GA12731@shareable.org> <20090505071608.GB10258@mail.oracle.com> <20090505080936.GG3209@webber.adilger.int> <20090505165628.GC7835@mail.oracle.com> <20090505212417.GO3209@webber.adilger.int> <20090505213206.GM7835@mail.oracle.com> <20090506071531.GB6976@mit.edu> <4A019DA9.4050700@hp.com> <4A019F21.2020907@hp.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Andreas Dilger , Jamie Lokier , linux-fsdevel@vger.kernel.org, jmorris@namei.org, ocfs2-devel@oss.oracle.com, viro@zeniv.linux.org.uk To: Theodore Tso , joel.becker@oracle.com Return-path: Received: from g5t0007.atlanta.hp.com ([15.192.0.44]:37192 "EHLO g5t0007.atlanta.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753826AbZEFRuN (ORCPT ); Wed, 6 May 2009 13:50:13 -0400 In-Reply-To: <4A019F21.2020907@hp.com> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: jim owens wrote: > > 1) "snapfile" - Joel's reflink(2) design. > 2) "cowfilecopy" - Ted's/Jamie's kernel cp. > > could be 1 syscall with a "preserve" flag that requires CAP_FCHOWN. No disagreement must mean the mail isn't getting through :) So on to the last turd in the punch bowl, quota and du rules: Both snapfile and cowfilecopy: - must not allow their use to cheat to exceed the user's quota - would best serve if only the actual disk non-shared space was counted But we know not all filesystems will be able to change their on-disk data structures and efficiently count only non-shared. So I suggest this is the rule: Quota accounting and disk space used for the original file will be as if there were 0 reflinks. Quota accounting and disk space reported for the new reflink file is filesystem specific and may or may not include shared disk space. jim