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, 7 insertions, 0 deletions

diff --git a/net/sunrpc/rpc_pipe.c b/net/sunrpc/rpc_pipe.c
index 3fdacaf5c708..7f676bdf70d3 100644
--- a/net/sunrpc/rpc_pipe.c
+++ b/net/sunrpc/rpc_pipe.c
@@ -416,11 +416,13 @@ struct vfsmount *rpc_get_mount(void)
                 return ERR_PTR(err);
         return rpc_mount;
 }
+EXPORT_SYMBOL_GPL(rpc_get_mount);
 
 void rpc_put_mount(void)
 {
         simple_release_fs(&rpc_mount, &rpc_mount_count);
 }
+EXPORT_SYMBOL_GPL(rpc_put_mount);
 
 static int rpc_delete_dentry(struct dentry *dentry)
 {
@@ -946,6 +948,7 @@ enum {
         RPCAUTH_portmap,
         RPCAUTH_statd,
         RPCAUTH_nfsd4_cb,
+        RPCAUTH_cache,
         RPCAUTH_RootEOF
 };
 
@@ -974,6 +977,10 @@ static const struct rpc_filelist files[] = {
                 .name = "nfsd4_cb",
                 .mode = S_IFDIR | S_IRUGO | S_IXUGO,
         },
+        [RPCAUTH_cache] = {
+                .name = "cache",
+                .mode = S_IFDIR | S_IRUGO | S_IXUGO,
+        },
 };
 
 static int