Modify nfsd.c to add support for the experimental nfs server.

This includes the addition of a new flag "-4" that will force
use of the experimental server with nfsv4 support in it. This
commit also adds two new man pages to the repository that are
NFSv4 specific. One describes the file used by the server to
restart nfsv4 services safely. The other is a brief overview
of nfsv4 and its setup.

Reviewed by:	dfr
Approved by:	kib (mentor)

1 files changed, 309 insertions, 0 deletions

diff --git a/usr.sbin/nfsd/nfsv4.4 b/usr.sbin/nfsd/nfsv4.4
new file mode 100644
index 0000000..582181d
--- /dev/null
+++ b/usr.sbin/nfsd/nfsv4.4
@@ -0,0 +1,309 @@
+.\" Copyright (c) 2009 Rick Macklem, University of Guelph
+.\" All rights reserved.
+.\"
+.\" Redistribution and use in source and binary forms, with or without
+.\" modification, are permitted provided that the following conditions
+.\" are met:
+.\" 1. Redistributions of source code must retain the above copyright
+.\"    notice, this list of conditions and the following disclaimer.
+.\" 2. Redistributions in binary form must reproduce the above copyright
+.\"    notice, this list of conditions and the following disclaimer in the
+.\"    documentation and/or other materials provided with the distribution.
+.\"
+.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+.\" SUCH DAMAGE.
+.\"
+.\" $FreeBSD$
+.\"
+.Dd April 30, 2009
+.Dt NFSV4 4
+.Os
+.Sh NAME
+.Nm nfsv4
+.Nd NFS Version 4 Protocol
+.Sh SYNOPSIS
+experimental client and server with NFSv4 support
+.Sh DESCRIPTION
+The experimental nfs client and server provides support for the
+.Tn NFSv4
+specification; see
+.%T "Network File System (NFS) Version 4 Protocol \\*(tNRFC\\*(sP 3530" .
+The protocol is somewhat similar to NFS Version 3, but differs in significant
+ways. It uses a single Compound RPC that concatenates operations to-gether.
+Each of these operations are similar to the RPCs of NFS Version 3.
+The operations in the compound are performed in order, until one of
+them fails (returns an error) and then the RPC terminates at that point.
+.Pp
+It has
+integrated locking support, which implies that the server is no longer
+stateless. As such, the
+.Tn NFSv4
+server remains in recovery mode for a Grace period (always greater than the
+lease duration the server uses) after a reboot.
+During this Grace period, clients may recover state but not perform other
+open/lock state changing operations.
+To provide for correct recovery semantics, a small file described by
+.Xr stablerestart 5
+is used by the server during the recovery phase. If this file is missing,
+the server will not start.
+If this file is lost, it should be recovered from backups, since creating
+an empty
+.Xr stablerestart 5
+file will result in the server starting without providing a Grace Period
+for recovery.
+Note that recovery only occurs when the server
+machine is rebooted, not when the
+.Xr nfsd 8
+are just restarted.
+.Pp
+It provides several optional features not in NFS Version 3:
+.sp
+.Bd -literal -offset indent -compact
+- NFS Version 4 ACLs
+- Referrals, which redirect subtrees to other servers
+  (not yet implemented)
+- Delegations, which allow a client to operate on a file locally
+.Ed
+.Pp
+The
+.Tn NFSv4
+protocol does not use a separate mount protocol and assumes that the
+server provides a single file system tree structure, rooted at the point
+in the local file system tree specified by the
+.sp 1
+.Bd -literal -offset indent -compact
+V4: <rootdir>
+.Ed
+.sp 1
+line in
+.Xr exports 5 .
+The
+.Xr nfsd 8
+allows a limited subset of operations to be performed on non-exported subtrees
+of the local file system, so that traversal of the tree to the exported
+subtrees is possible.
+As such, the ``<rootdir>'' can be in a non-exported file system. However,
+the entire tree that is rooted at that point must be in local file systems
+that are of types that can be NFS exported.
+Since the
+.Nm
+file system is rooted at ``<rootdir>'', setting this to anything other
+than ``/'' will result in clients being required to use different mount
+paths for
+.Nm
+than for NFS Version 2 or 3.
+Unlike NFS Version 2 and 3, Version 4 allows a client mount to span across
+multiple server file systems, although not all clients are capable of doing
+this.
+.Pp
+.Nm
+uses names for users and groups instead of numbers. On the wire, they
+take the form:
+.sp
+.Bd -literal -offset indent -compact
+<user>@<dns.domain>
+.Ed
+.sp
+where ``<dns.domain>'' is not the same as the DNS domain used
+for host name lookups, but is usually set to the same string. Most systems set this ``<dns.domain>''
+to the domain name part of the machine's
+.Xr hostname 1
+by default. However, this can normally be overridden by a command line
+option or configuration file for the daemon used to do the name<->number
+mapping.
+On FreeBSD, the mapping daemon is called
+.Xr nfsuserd 8
+and has a command line option that overrides the domain component of the
+machine's hostname.
+This can be set in
+.Xr rc.conf 5
+via the nfsv4_userd_flags variable.
+For use of
+.Nm ,
+either client or server, this daemon must be enabled by setting
+.sp
+.Bd -literal -offset indent -compact
+nfsv4_enable="YES"
+.Ed
+.sp
+in
+.Xr rc.conf 5 .
+If this ``<dns.domain>'' is not set correctly or the daemon is not running, ``ls -l'' will typically
+report a lot of ``nobody'' and ``nogroup'' ownerships.
+.Pp
+Although numbers are no longer used in the
+.Nm
+protocol, they will still be in the RPC authentication fields when running
+using AUTH_SYS (sec=sys), which is the default.
+As such, in this case both the user/group name and number spaces must
+be consistent between the client and server.
+.Pp
+However, if you run
+.Nm
+with RPCSEC_GSS (sec=krb5, krb5i, krb5p), only names and KerberosV tickets
+will go on the wire.
+.Sh SERVER SETUP
+.Pp
+To set up the experimental nfs server that supports
+.Nm
+you will need to either build a kernel with:
+.sp
+.Bd -literal -offset indent -compact
+options	NFSD
+.Ed
+and not
+.Bd -literal -offset indent -compact
+options	NFSSERVER
+.Ed
+.sp
+or start
+.Xr mountd 8
+and
+.Xr nfsd 8
+with the ``-4'' option to force use of the experimental server.
+This will occur if
+.sp
+.Bd -literal -offset indent -compact
+nfsv4_enable="YES"
+.Ed
+.sp
+is set in
+.Xr rc.conf 5 ,
+as above.
+.Pp
+You will also need to add a:
+.sp
+.Bd -literal -offset indent -compact
+V4: <rootdir>
+.Ed
+.sp
+line to the
+.Xr exports 5
+file, to tell the server where the
+.Nm
+tree is rooted.
+.Pp
+If the file systems you are exporting are only being accessed via
+.Nm
+there are a couple of
+.Xr sysctl 8
+variables that you can change, which might improve performance.
+.Bl -tag -width Ds
+.It Cm vfs.newnfs.issue_delegations
+when set non-zero, allows the server to issue Open Delegations to
+clients. These delegations permit the client to manipulate the file
+locally on the client. Unfortunately, at this time, client use of
+delegations is limited, so performance gains may not be observed.
+This can only be enabled when the file systems being exported to
+.Nm
+clients are not being accessed locally on the server and, if being
+accessed via NFS Version 2 or 3 clients, these clients cannot be
+using the NLM.
+.It Cm vfs.newnfs.enable_locallocks
+can be set to 0 to disable acquisition of local byte range locks.
+Disabling local locking can only be done if neither local accesses
+to the exported file systems nor the NLM is operating on them.
+.El
+.sp
+Note that Samba server access would be considered ``local access'' for the above
+discussion.
+.Pp
+To build a kernel with the experimental
+.Nm
+linked into it, the
+.sp
+.Bd -literal -offset indent -compact
+options	NFSD
+.Ed
+.sp
+must be specified in the kernel's
+.Xr config 5
+file.
+.Sh CLIENT MOUNTS
+.Pp
+To do an
+.Nm
+mount, specify the ``nfsv4'' option on the
+.Xr mount_nfs 8
+command line.
+This will force use of the experimental client plus set ``tcp'' and
+.Nm .
+.Pp
+If the
+.Nm
+server that is being mounted on supports delegations, you can set
+.sp
+.Bd -literal -offset indent -compact
+nfsv4_callbackdaemon_enable="YES"
+.Ed
+.sp
+via
+.Xr rc.conf 5
+so that the client side callback daemon
+.Xr nfscbd 8
+is started upon boot.
+Without a functioning callback path, a server will never issue Delegations
+to a client.
+.sp
+By default, the callback address will be set to the IP address acquired via
+rtalloc() in the kernel and port# 7745.
+To override the default port#, a command line option for
+.Xr nfscbd 8
+can be set via the variable
+.sp
+.Bd -literal -offset indent -compact
+nfsv4_callbackdaemon_flag
+.Ed
+.sp
+using
+.Xr rc.conf 5 .
+.sp
+To get callbacks to work when behind a NAT gateway, a port for the callback
+service will need to be set up on the NAT gateway and then the address
+of the NAT gateway (host IP plus port#) will need to be set by assigning the
+.Xr sysctl 8
+variable vfs.newnfs.callback_addr to a string of the form:
+.sp
+N.N.N.N.N.N
+.sp
+where the first 4 Ns are the host IP address and the last two are the
+port# in network byte order (all decimal #s in the range 0-255).
+.Pp
+To build a kernel with the experimental
+.Nm
+client linked into it, the option
+.sp
+.Bd -literal -offset indent -compact
+options	NFSCL
+.Ed
+.sp
+must be specified in the kernel's
+.Xr config 5
+file.
+.Sh FILES
+.Bl -tag -width /var/db/nfs-stablerestart -compact
+.It Pa /var/db/nfs-stablerestart
+NFS V4 stable restart file
+.El
+.Sh SEE ALSO
+.Xr stablerestart 5
+.Xr mountd 8
+.Xr nfscbd 8
+.Xr nfsd 8
+.Xr nfsdumpstate 8
+.Xr nfsrevoke 8
+.Xr nfsuserd 8
+.Sh BUGS
+At this time, there is no recall of delegations for local file system
+operations. As such, delegations should only be enabled for file systems
+that are being used soley as NFS export volumes and are not being accessed
+via local system calls nor services such as Samba.