NFS: Add a dns resolver for use with NFSv4 referrals and migration

The NFSv4 and NFSv4.1 protocols both allow for the redirection of a client
from one server to another in order to support filesystem migration and
replication. For full protocol support, we need to add the ability to
convert a DNS host name into an IP address that we can feed to the RPC
client.

We'll reuse the sunrpc cache, now that it has been converted to work with
rpc_pipefs.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 8 insertions, 0 deletions

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index c08813dbfce2..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.