Merge branch 'nfs-for-2.6.32'

2 files changed, 127 insertions, 0 deletions

diff --git a/Documentation/filesystems/nfs.txt b/Documentation/filesystems/nfs.txt
new file mode 100644
index 000000000000..f50f26ce6cd0
--- /dev/null
+++ b/Documentation/filesystems/nfs.txt
@@ -0,0 +1,98 @@
+
+The NFS client
+==============
+
+The NFS version 2 protocol was first documented in RFC1094 (March 1989).
+Since then two more major releases of NFS have been published, with NFSv3
+being documented in RFC1813 (June 1995), and NFSv4 in RFC3530 (April
+2003).
+
+The Linux NFS client currently supports all the above published versions,
+and work is in progress on adding support for minor version 1 of the NFSv4
+protocol.
+
+The purpose of this document is to provide information on some of the
+upcall interfaces that are used in order to provide the NFS client with
+some of the information that it requires in order to fully comply with
+the NFS spec.
+
+The DNS resolver
+================
+
+NFSv4 allows for one server to refer the NFS client to data that has been
+migrated onto another server by means of the special "fs_locations"
+attribute. See
+        http://tools.ietf.org/html/rfc3530#section-6
+and
+        http://tools.ietf.org/html/draft-ietf-nfsv4-referrals-00
+
+The fs_locations information can take the form of either an ip address and
+a path, or a DNS hostname and a path. The latter requires the NFS client to
+do a DNS lookup in order to mount the new volume, and hence the need for an
+upcall to allow userland to provide this service.
+
+Assuming that the user has the 'rpc_pipefs' filesystem mounted in the usual
+/var/lib/nfs/rpc_pipefs, the upcall consists of the following steps:
+
+   (1) The process checks the dns_resolve cache to see if it contains a
+       valid entry. If so, it returns that entry and exits.
+
+   (2) If no valid entry exists, the helper script '/sbin/nfs_cache_getent'
+       (may be changed using the 'nfs.cache_getent' kernel boot parameter)
+       is run, with two arguments:
+                - the cache name, "dns_resolve"
+                - the hostname to resolve
+
+   (3) After looking up the corresponding ip address, the helper script
+       writes the result into the rpc_pipefs pseudo-file
+       '/var/lib/nfs/rpc_pipefs/cache/dns_resolve/channel'
+       in the following (text) format:
+
+                "<ip address> <hostname> <ttl>\n"
+
+       Where <ip address> is in the usual IPv4 (123.456.78.90) or IPv6
+       (ffee:ddcc:bbaa:9988:7766:5544:3322:1100, ffee::1100, ...) format.
+       <hostname> is identical to the second argument of the helper
+       script, and <ttl> is the 'time to live' of this cache entry (in
+       units of seconds).
+
+       Note: If <ip address> is invalid, say the string "0", then a negative
+       entry is created, which will cause the kernel to treat the hostname
+       as having no valid DNS translation.
+
+
+
+
+A basic sample /sbin/nfs_cache_getent
+=====================================
+
+#!/bin/bash
+#
+ttl=600
+#
+cut=/usr/bin/cut
+getent=/usr/bin/getent
+rpc_pipefs=/var/lib/nfs/rpc_pipefs
+#
+die()
+{
+        echo "Usage: $0 cache_name entry_name"
+        exit 1
+}
+
+[ $# -lt 2 ] && die
+cachename="$1"
+cache_path=${rpc_pipefs}/cache/${cachename}/channel
+
+case "${cachename}" in
+        dns_resolve)
+                name="$2"
+                result="$(${getent} hosts ${name} | ${cut} -f1 -d\ )"
+                [ -z "${result}" ] && result="0"
+                ;;
+        *)
+                die
+                ;;
+esac
+echo "${result} ${name} ${ttl}" >${cache_path}
+
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 7936b801fe6a..ce8853755814 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1503,6 +1503,14 @@ and is between 256 and 4096 characters. It is defined in the file
                         [NFS] set the TCP port on which the NFSv4 callback
                         channel should listen.
 
+        nfs.cache_getent=
+                        [NFS] sets the pathname to the program which is used
+                        to update the NFS client cache entries.
+
+        nfs.cache_getent_timeout=
+                        [NFS] sets the timeout after which an attempt to
+                        update a cache entry is deemed to have failed.
+
         nfs.idmap_cache_timeout=
                         [NFS] set the maximum lifetime for idmapper cache
                         entries.
@@ -2395,6 +2403,18 @@ and is between 256 and 4096 characters. It is defined in the file
         stifb=          [HW]
                         Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
 
+        sunrpc.min_resvport=
+        sunrpc.max_resvport=
+                        [NFS,SUNRPC]
+                        SunRPC servers often require that client requests
+                        originate from a privileged port (i.e. a port in the
+                        range 0 < portnr < 1024).
+                        An administrator who wishes to reserve some of these
+                        ports for other uses may adjust the range that the
+                        kernel's sunrpc client considers to be privileged
+                        using these two parameters to set the minimum and
+                        maximum port values.
+
         sunrpc.pool_mode=
                         [NFS]
                         Control how the NFS server code allocates CPUs to
@@ -2411,6 +2431,15 @@ and is between 256 and 4096 characters. It is defined in the file
                         pernode     one pool for each NUMA node (equivalent
                                     to global on non-NUMA machines)
 
+        sunrpc.tcp_slot_table_entries=
+        sunrpc.udp_slot_table_entries=
+                        [NFS,SUNRPC]
+                        Sets the upper limit on the number of simultaneous
+                        RPC calls that can be sent from the client to a
+                        server. Increasing these values may allow you to
+                        improve throughput, but will also increase the
+                        amount of memory reserved for use by the client.
+
         swiotlb=        [IA-64] Number of I/O TLB slabs
 
         switches=       [HW,M68k]