From mboxrd@z Thu Jan 1 00:00:00 1970 Message-Id: <200006080022.CAA16063@e35.marxmeier.com> Subject: Re: [linux-lvm] LVM 0.8final for 2.2.15/2.2.16? Date: Thu, 08 Jun 2000 2:22:14 MESZ In-Reply-To: ; from "Paul Jakma" at Jun 8, 100 12:18 (midnight) From: Michael Marxmeier Sender: owner-linux-lvm Errors-To: owner-linux-lvm List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: paul@clubi.ie Cc: jan@gondor.com, ak@suse.de, linux-lvm@msede.com > > On Wed, 7 Jun 2000, Jan Niehusmann wrote: > > > The snapshot logic simply doesn't know what a filesystem is. It just > > clones the block device. > > this i knew.. :) > > > So the fs may be in en inconsistent state, if you do the snapshot > > while some write operation is in progress on the cloned > > filesystem. > > ok. so the solution is what? a call in the vfs to complete pending > writes, and hold off on modifying any blocks? IMHO when creating a snapshot LVM could simply sync all outstanding buffers for the block device vialog block_fsync() (not sure if this is already done -- Heinz care to comment?). This should also take care of pending fs meta information thus we should get a consistent state. The question is how atomic this is? Since fsync_dev() currently does a lock_kernel() is might even be sufficient. Any reason why this is not suffiecient? Michael -- Michael Marxmeier Marxmeier Software AG E-Mail: mike@msede.com Besenbruchstrasse 9 Phone : +49 202 2431440 42285 Wuppertal, Germany Fax : +49 202 2431420 http://www.msede.com/