From mboxrd@z Thu Jan 1 00:00:00 1970 From: =?utf-8?B?SsO2cm4=?= Engel Subject: Re: [PATCH RFC] nilfs2: continuous snapshotting file system Date: Tue, 26 Aug 2008 12:16:19 +0200 Message-ID: <20080826101618.GA17261@logfs.org> References: <20080820004326.519405a2.akpm@linux-foundation.org> <200808201613.AA00212@capsicum.lab.ntt.co.jp> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: Andrew Morton , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org To: Ryusuke Konishi Return-path: Content-Disposition: inline In-Reply-To: <200808201613.AA00212@capsicum.lab.ntt.co.jp> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org On Thu, 21 August 2008 01:13:45 +0900, Ryusuke Konishi wrote: > >On Wed, 20 Aug 2008 11:45:05 +0900 Ryusuke Konishi wrote: >=20 > 4. To make disk blocks relocatable, NILFS2 maintains a table file (ca= lled DAT) > which maps virtual disk blocks addresses to usual block addresses. > The lifetime information is recorded in the DAT per virtual block = address. Interesting approach. Does that mean that every block lookup involves two disk accesses, one for the DAT and one for the actual block? > The current NILFS2 GC simply reclaims from the oldest segment, so the= disk > partition acts like a ring buffer. (this behaviour can be changed by=20 > replacing userland daemon). Is this userland daemon really necessary? I do all that stuff in kernelspace and the amount of code I have is likely less than would be necessary for the userspace interface alone. Apart from creating a plethora of research papers, I never saw much use for pluggable cleaners. Did you encounter any nasty deadlocks and how did you solve them? =46inding deadlocks in the vfs-interaction became a hobby of mine when testing logfs and at least one other lfs seems to have had similar problems - they exported the inode_lock in their patch. ;) J=C3=B6rn --=20 Consensus is no proof! -- John Naisbitt