From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Teigland Subject: Re: File system awareness (or lack thereof) of vfs granting of leases Date: Tue, 20 Feb 2007 13:08:17 -0600 Message-ID: <20070220190817.GB3932@redhat.com> References: <45D6937A.10902@redhat.com> <20070218063948.GC22022@fieldses.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: "J. Bruce Fields" , Wendy Cheng , linux-fsdevel@vger.kernel.org To: Robert Rappaport Return-path: Received: from mx1.redhat.com ([66.187.233.31]:45374 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S964788AbXBTTH4 (ORCPT ); Tue, 20 Feb 2007 14:07:56 -0500 Content-Disposition: inline In-Reply-To: Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org On Tue, Feb 20, 2007 at 10:46:51AM -0500, Robert Rappaport wrote: > Thank you both for your helpful replies. In particular, the addition > of the calls to file system specific functions in routines, > fcntl_setlease() and break_lease(), as well as the modifications to > the file_operations and inode_operations structures, pointed to by > Bruce's reply, look exactly like the hooks that I would need to > proceed to resolve my problems. Is there any timetable established > for these modifications to make it into a future release? These hooks > would clearly benefit any cluster file system that has to deal with > leases. We did an experimental distributed lease implementation in gfs(1) a while ago. It worked, but was so extremely expensive that there was no point in considering it seriously. The problem is that _every_ open and close of every file requires a new dlm lock operation. Leases require knowledge about the cluster-wide opened/closed state of files, not only that but the mode they're open in. Dave