On Fri, Aug 20, 2010 at 11:35:02AM -0400, david.noveck@xxxxxxx wrote: > It isn't the server's problem. There is no way the server has access to > the Vfs opens as visible objects I was talking about how our server maps incoming open requests to vfs opens when talking to its own vfs layer. Whatever, it's my problem--I can deal with it. > or as having the assignment of locks to > such fine-grained opens. > > I'm kind of thinking that this shows we (Bruce, me, and rest of the > working group) made a mistake in that sort of a design in which we do > not allow multiple distinguished open objects for a given fh-owner pair. > Anyway the problems that it caused are pretty minor and we don't know > what problems would have been generated with an alternate design. I > think this is something to look at in NFSv5 or the next NFSv4.1-style > minor version, if any. But, yes, I have found the open upgrade/downgrade behavior confusing. --b. > > -----Original Message----- > From: J. Bruce Fields [mailto:bfields@xxxxxxxxxxxx] > Sent: Thursday, August 19, 2010 12:45 PM > To: Trond Myklebust > Cc: Noveck, David; nfsv4@xxxxxxxx; linux-nfs@xxxxxxxxxxxxxxx > Subject: Re: [nfsv4] OPEN_DOWNGRADE and posix byte range locking issue > > > > -----Original Message----- > > > From: nfsv4-bounces@xxxxxxxx [mailto:nfsv4-bounces@xxxxxxxx] On > Behalf > > > Of Trond Myklebust > > > Sent: Wednesday, July 07, 2010 7:30 PM > > > To: nfsv4@xxxxxxxx > > > 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. > -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
