On Mon, 2007-05-07 at 09:02 -0500, Chris Johns wrote: > Paul, > > You're correct, and this is a bug in recent kernels that is also now > present in RHEL5 (and Fedora Core 5, for that matter). We noticed the > bug a while ago when we started using the beta version of RHEL5, since > our product makes use of a mix of read-only and read-write mounts of > different directories within a single filesystem from the same NFS server. > > The bug is not even restricted to a single export entry. We have, in the > simples example, 2 exports: an export of /export/foo/ro (read-only from > the server) and /export/foo/rw (read-write from the server). When our > RHEL5 client mounts /export/foo/ro first, read-only on the client side, > it gets mounted read-only. Now, however, when we mount /export/foo/rw > read-write on the client side, the client NFS code downgrades the mount > to read-only, to match the first mount from the server's filesystem. > > A suggested workaround was to use a unique 'fsid' value for each export > entry on the server, thus faking the client out by making it believe > that each mount was from a different filesystem. While this would work, > it's an administration nightmare, particularly with a large > installation, or when using a NetApp filer, for instance. > > The Red Hat bug that's currently open against this is > https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=209964. > > On 11/20/06, Trond Myklebust (NFS developer) replied to a posting on > [EMAIL PROTECTED] about this: > > All, > > > > Any insights on this? > > > > I did find the following post from Trond which appears > > > > http://lkml.org/lkml/2006/10/18/264 > > > > Which seems to imply that this is a 'feature' and not > > a 'bug'? Is that true - or have I missed something? > > > > That is quite correct (thanks for taking the time to search the list > archives). For various reasons, we're trying to tighten the NFS cache > consistency. That means that practices that were previously allowed > (such as mounting different directories from the same filesystem using > different mount options) have been restricted. > The ability to have the same filesystem mounted both read-only and > read-write will hopefully soon be allowed again, but it needs to be > fixed at the VFS level. The patches to do so have circulated for quite > some time now, but have not been merged due to disagreements over how > the user interface for 'mount --bind' should be in this case.
>From what I've found about 50% or so of the patches were accepted in 2.6.19. We need to fire up the discussion on this again because I can't see any way forward until the rest of these patch set gets into the mainstream kernel. I'll try but I'm not sure how far I'll get. Ian _______________________________________________ rhelv5-list mailing list [email protected] https://www.redhat.com/mailman/listinfo/rhelv5-list
