2002-08-13 22:54:02

by Kendrick M. Smith

[permalink] [raw]
Subject: announcing NFSv4 patches against 2.5.31


This is an announcement of a set of 38 patches against Linux 2.5.31,
which implement basic NFSv4 functionality. The patches were
developed as part of the NFSv4 project at the University of Michigan.
We are aiming to work with other kernel developers in the next
few weeks, to get the patches included in 2.5.x. In addition, we
could always use more testing, so if anyone wants to apply the patches
and bang on them, that would be extremely helpful as well.

For now, only the bare minimum of features have been implemented --
just enough to create a functional network file system. Byte-range
file locking, state management, recovery from server reboot, extended
attributes, ACL's, the NFSv4 "pseudo filesystem", and strong security
are still unimplemented in 2.5.x. Actually, we have implementations of
most of these features in 2.4.x, but are waiting to port them to 2.5.x
until the "minimal" patches have been approved.

(For those familiar with the NFSv4 protocol, I should elaborate by
saying that the client does all of its READs and WRITEs using "magic
stateids" and uses OPEN and CLOSE only when it needs to create a
file. The server treats all state-manipulating operations such
as SETCLIENTID,OPEN,CLOSE... as no-ops and does not remember state.
Instead of a proper implementation of the pseudo filesystem, the
first entry in /etc/exports is chosen as the nominal root.)

Here are directions for running NFSv4. Note that a few userland
utilities are necessary (URL's given as needed):

1. Apply the NFSv4 patches to a clean 2.5.31 kernel, either one at a time
from the messages following this one, or all at once by downloading
the "grand unified patch" from
http://www.citi.umich.edu/projects/nfsv4/patches-2.5/patch-2.5.31-E
There will be seperate kernel config options for NFSv4 support in
the client and server.

2. Download and install the GSSD daemon from
http://www.citi.umich.edu/projects/nfsv4/simple-gssd/
This daemon must be running on both the client and server.

3. Warning!! Special configuration on the server is necessary before an
NFSv4 export will be accessible.
First, it must be exported specifically to the client in question,
without use of string wildcards, e.g.

/some/export farringdon.citi.umich.edu(rw)

in /etc/exports is OK, but

/some/export *.citi.umich.edu(rw)

is not.
Second, only the _first_ export (by order in /etc/exports) will be
visible to a given client.
Finally, this export will appear to an NFSv4 client as '/' instead of
the actual export pathname (/some/export in the example above).
All of this special configuration is only necessary because this
set of patches does not include a proper implementation of the NFSv4
pseudo filesystem. As soon as these patches patches (or a variant
thereof) is incorporated into the kernel, our next goal is to develop a
satisfactory pseudofs for 2.5.x, at which point the need for this
special configuration will go away.

4. On the client, you will need a patched version of the mount and umount
utilities. Download util-linux-2.11t from kernel.org, apply the patch

http://www.citi.umich.edu/projects/nfsv4/patches-2.5/patch-util-linux-2.11t-A

and build mount and umount as usual. If you are nervous about
tampering with the built-in mount and umount on your system, we
recommend creating symlinks, e.g.

# ln -s /usr/src/util-linux-2.11t-nfsv4/mount/mount /usr/local/bin/mount4
# ln -s /usr/src/util-linux-2.11t-nfsv4/mount/umount /usr/local/bin/umount4

You should then be able to start the server as usual, and mount with

# mount4 -t nfs -o vers=4,... somehost.somedomain.com:/ /mnt/nfs

If this doesn't work, it is probably because GSSD is not running
on either the client or the server, or because you're not mounting '/'
(see 3. above).


These directions, as well as copies of the patches, are also available at
http://www.citi.umich.edu/projects/nfsv4/patches-2.5
This URL will always be kept up-to-date with the latest versions of the
patches.

Cheers,
Kendrick Smith
Center for Information Technology and Integration, University of Michigan



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