NFS: Create a try_mount rpc op

I'm already looking up the nfs subversion in nfs_fs_mount(), so I have
easy access to rpc_ops that used to be difficult to reach.  This allows
me to set up a different mount path for NFS v2/3 and NFS v4.

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

1 files changed, 4 insertions, 0 deletions

diff --git a/include/linux/nfs_xdr.h b/include/linux/nfs_xdr.h
index 0e181c2320b7..bc7415baf44d 100644
--- a/include/linux/nfs_xdr.h
+++ b/include/linux/nfs_xdr.h
@@ -1353,6 +1353,8 @@ struct nfs_renamedata {
 struct nfs_access_entry;
 struct nfs_client;
 struct rpc_timeout;
+struct nfs_subversion;
+struct nfs_mount_info;
 struct nfs_client_initdata;
 struct nfs_pageio_descriptor;
 
@@ -1370,6 +1372,8 @@ struct nfs_rpc_ops {
                             struct nfs_fsinfo *);
         struct vfsmount *(*submount) (struct nfs_server *, struct dentry *,
                                       struct nfs_fh *, struct nfs_fattr *);
+        struct dentry *(*try_mount) (int, const char *, struct nfs_mount_info *,
+                                     struct nfs_subversion *);
         int     (*getattr) (struct nfs_server *, struct nfs_fh *,
                             struct nfs_fattr *);
         int     (*setattr) (struct dentry *, struct nfs_fattr *,