From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wendy Cheng Subject: Re: File system awareness (or lack thereof) of vfs granting of leases Date: Sat, 17 Feb 2007 00:32:42 -0500 Message-ID: <45D6937A.10902@redhat.com> References: Reply-To: wcheng@redhat.com Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: linux-fsdevel@vger.kernel.org To: Robert Rappaport Return-path: Received: from mx1.redhat.com ([66.187.233.31]:52721 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965030AbXBQFXg (ORCPT ); Sat, 17 Feb 2007 00:23:36 -0500 In-Reply-To: Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org Robert Rappaport wrote: > [snip] > .... This is because the vfs running on the same node where the > samba server is running is not necessarily aware of all accesses to > the file on which it is granting a lease. Since vfs does not > currently inform file systems about the granting and rescinding of > leases, a clustered file system cannot allow a samba server to support > OpLocks on its files and this has a negative impact on performance. > > What I think is needed is to add a file systems defined > file_operations function, that would be invoked when vfs is > considering the granting of a lease on a file associated with an > inode. Such an enhancement would allow a file system to be come aware > of vfs lease activity and allow it to support this activity. > NFS has similar issues because Linux NLM-VFS does not invoke server side filesystem specific lock method. This implies NFS client applications is not able to use posix locks to coordinate file access across different nodes with a cluster filesystem, even the cluster filesystem itself does support posix locking. IBM Research and University of Michigan CITI group have worked out a set of patches to remedy the issue: http://www.opensubscriber.com/message/linux-fsdevel@vger.kernel.org/5527833.html -- Wendy