From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Sandeen Subject: Re: Inquiry: disk format change in the future Date: Thu, 20 Aug 2009 23:04:11 -0500 Message-ID: <4A8E1CBB.2020300@redhat.com> References: <20090820002457.A0C0520E21@spam-fw.osrg.net> <20090820.112237.04623349.ryusuke@osrg.net> <4A8CC93B.9090904@redhat.com> <20090821.125734.96697535.ryusuke@osrg.net> Reply-To: NILFS Users mailing list Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20090821.125734.96697535.ryusuke-sG5X7nlA6pw@public.gmane.org> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: users-bounces-JrjvKiOkagjYtjvyW6yDsg@public.gmane.org Errors-To: users-bounces-JrjvKiOkagjYtjvyW6yDsg@public.gmane.org To: Ryusuke Konishi Cc: users-JrjvKiOkagjYtjvyW6yDsg@public.gmane.org Ryusuke Konishi wrote: > Hi! > On Wed, 19 Aug 2009 22:55:39 -0500, Eric Sandeen wrote: >> Ryusuke Konishi wrote: >>> (reply added to "Yann E. MORIN") >>> >>> Hi, >>> On Wed, 19 Aug 2009 11:31:56 +0200, "Yann E. MORIN" wrote: >>>> Hello All! >>>> >>>> I've searched the archives, but could not find the answer to the >>>> following questions: >>>> >>>> - will there be, or what is the probability of, a disk format change >>>> in the near future (few months)? >>> We still have some possibilities for the format change at this time. >>> >>> Basically I intend to keep the disk format, but some new features like >>> >>> - Extended attributes, ACLs >>> - Rollback >>> - Checkpoint based remote replication >>> >>> may require it. So far, we haven't seen any specific requisition. >>> >> Do you expect that any of the changes may impact the ability of >> utilities such as blkid or file to recognize a nilfs filesystem? > > I don't think these affect blkid or similar programs even if > additional fields may be required in the superblock. > > One my concern about the automated recognition is too short magic > field of nilfs. I think those tools will need to confirm the checksum > in addition to the magic field. That's possible, at least for blkid. I did that for recognizing lvm volumes. I'll take a look. > If I have a chance to reorganize the superblock, I would like to make > it longer and adjust some other fields. But I will not do so for the > above features. > >> I'd happily write patches for those utilities to add nilfs recognition >> if you think there is a stable fingerprint that can be recognized. >> >> Thanks, >> -Eric > > Thank you for the proposal! I'm grateful if you could do so. I think > the time when we drop the experimental flag from Kconfig is the time. Ok, I can wait 'til then to submit it. Once I get time to see what it takes I can run the patch past you, see if you think it's a stable fingerprint, and either send it upstream or wait, based on what you think is best at that point. Thanks, -Eric