From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ryusuke Konishi Subject: Re: Does nilfs2 do any in-place writes? Date: Sat, 18 Jan 2014 07:55:19 +0900 (JST) Message-ID: <20140118.075519.43661574.konishi.ryusuke@lab.ntt.co.jp> References: <1389787304.3913.28.camel@slavad-ubuntu> <20140116.002353.94325733.konishi.ryusuke@lab.ntt.co.jp> <1389866912.2565.44.camel@slavad-ubuntu> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1389866912.2565.44.camel@slavad-ubuntu> Sender: linux-nilfs-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: Content-Type: Text/Plain; charset="us-ascii" To: Vyacheslav Dubeyko Cc: Clemens Eisserer , linux-nilfs-u79uwXL29TY76Z2rM5mHXA@public.gmane.org Hi Vyacheslav, On Thu, 16 Jan 2014 14:08:32 +0400, Vyacheslav Dubeyko wrote: > Hi Ryusuke, > > On Thu, 2014-01-16 at 00:23 +0900, Ryusuke Konishi wrote: > >> >> By the way, do you have any nice idea to stop periodical update of >> superblocks? >> > > Yes, I think too that such suggestion is valuable for NILFS2. But I > suppose that the problem is more complex. I mean a situation with > write-able snapshots. If we will have write-able snapshots then it means > necessity to have independent version of some superblock's fields > (s_last_cno, s_last_pseg, s_last_seq, s_mtime, s_wtime, s_mnt_count, > s_state, s_c_interval, s_feature_compat_ro, s_feature_incompat). For > example, snapshot can be made before xafile creation on a volume and > write-able snapshot should continue to live without possibility to xattr > creation, and so on. OK, please tell me what do you suppose about the writable snapshot. Do you think we should keep multiple branches or concurrently mountable namespaces on one device ? I prefer to maintain only one super root block per partition even if we support writable snapshots. Otherwise, I think we should use multiple partitions to simplify the design. I mean keeping multiple branches in one super root block with a DAT file and a sufile in such a case. Maintaining multiple DAT files and sufiles on one device seems too complex to me. Regards, Ryusuke Konishi -- To unsubscribe from this list: send the line "unsubscribe linux-nilfs" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html