Messages in this thread | | | Date | Tue, 10 Feb 2009 16:48:22 -0500 | Subject | Re: [RFC PATCH 0/2] Add VFS support for looking up paths on remote servers using a temporary mount namespace | From | "J. Bruce Fields" <> |
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On Tue, Feb 10, 2009 at 01:31:48PM -0500, Trond Myklebust wrote: > On Tue, 2009-02-10 at 10:58 -0500, J. Bruce Fields wrote: > > On Mon, Feb 09, 2009 at 01:45:34PM -0500, Trond Myklebust wrote: > > > The following two patches attempt to improve NFSv4's ability to look up > > > the mount path on a remote server. > > > > > > The first patch adds VFS support for walking the remote path, using a > > > temporary mount namespace to represent the server's namespace, so that > > > symlinks > > > > I'm a bit confused about the symlink case--I take it you're assuming > > that symlinks in the pseudofs should be interpreted as relative to the > > server's namespace (in keeping with traditional implementations of > > server exports), while symlinks elsewhere should continue to be > > intepreted relative to the client's namespace.
Maybe I shouldn't have said "symlinks in the pseudofs", as that's not entirely well defined--a complicated namespace may transition between "pseudofs" and "real" filesystems multiple times. So it's really a statement about the client's mount behavior: symlinks found along the mount path will be interpreted one way, symlinks found elsewhere another. Right?
Though put that way it's harder to decide what to store in a symlink, since you can't necessarily control which paths a given client may decide to mount.
> > Do the rfc's say anything about this? > > No, the RFCs say nothing, but interpreting symlinks as being relative to > the server namespace would be consistent with the mount behaviour of > NFSv2/v3. It also makes me uncomfortable to have a remote mount path > that could refer back to the client's namespace: that would not be an > NFS mount, but a local bind mount...
Some may be surprised to find that /mntsymlink/ and /mnt/symlink/ will be different after
mount file:/path/symlink/ /mntsymlink/ mount file:/path/ /mnt/
I see your point, though it might also be an argument for continuing to error out on symlinks.
It could also be argued that if a given symlink is expected to be interpreted on the server side, then the server should just go ahead and do that for the client, rather than returning it as a symlink.
Seems worth at least mentioning to the ietf group, as different behavior across different clients would be confusing.
--b.
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