From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Thu, 19 Aug 2010 12:44:48 -0400 To: Trond Myklebust Message-ID: <20100819164448.GF30151@fieldses.org> References: <1278545423.15524.26.camel@heimdal.trondhjem.org> <1278623332.13551.47.camel@heimdal.trondhjem.org> In-Reply-To: <1278623332.13551.47.camel@heimdal.trondhjem.org> From: "J. Bruce Fields" Cc: linux-nfs@vger.kernel.org, nfsv4@ietf.org Subject: Re: [nfsv4] OPEN_DOWNGRADE and posix byte range locking issue List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Sender: nfsv4-bounces@ietf.org Errors-To: nfsv4-bounces@ietf.org MIME-Version: 1.0 List-ID: > > -----Original Message----- > > From: nfsv4-bounces@ietf.org [mailto:nfsv4-bounces@ietf.org] On Behalf > > Of Trond Myklebust > > Sent: Wednesday, July 07, 2010 7:30 PM > > To: nfsv4@ietf.org > > Subject: [nfsv4] OPEN_DOWNGRADE and posix byte range locking issue > > > > Neither RFC3530, nor RFC5661 appear to list NFS4ERR_LOCKS_HELD as a > > valid response when the client calls OPEN_DOWNGRADE. > > > > The question is: what should the server then do if the NFS client holds > > a WRITE_LT lock, but then asks for an OPEN_DOWNGRADE to > > OPEN4_SHARE_ACCESS_READ. I understand that this is sanctioned in Windows > > server environments, but it should definitely be forbidden in a POSIX > > environment, and NFS4ERR_LOCKS_HELD would appear to fit the bill... A bizarre variation: the linux server associates vfs opens with stateid's. Locks are performed on vfs opens, and the vfs will complain if you attempt to close a file that still has locks associated with it. The sequence open RW lock R open R open downgrade to R would therefore be implemented at the vfs level as: open RW -> f lock R on f open R -> g close f Oops. We're stuck with ditching the lock (or erroring out) even though it's still compatible with the new config option. Well, I suppose this is my problem: either I should get a new vfs open for the use of the lock, or represent the original RW open by two vfs open's. It's not something a unix-like client could do, I think, but I don't think it's safe for me to assume I can reject it? --b. _______________________________________________ nfsv4 mailing list nfsv4@ietf.org https://www.ietf.org/mailman/listinfo/nfsv4