NFS: Create a single nfs_get_root()

This patch splits out the NFS v4 specific functionality of
nfs4_get_root() into its own rpc_op called by the generic client, and
leaves nfs4_proc_get_rootfh() as its own stand alone function.  This
also allows me to change nfs4_remote_mount(), nfs4_xdev_mount() and
nfs4_remote_referral_mount() to use the generic client's nfs_get_root()
function.  Later patches in this series will collapse these functions
into one common function, so using the same get_root() function
everywhere simplifies future changes.

Signed-off-by: Bryan Schumaker <bjschuma@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index 69212d2..e6ab15f 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -80,6 +80,7 @@
 static int nfs4_do_fsinfo(struct nfs_server *, struct nfs_fh *, struct nfs_fsinfo *);
 static int nfs4_async_handle_error(struct rpc_task *, const struct nfs_server *, struct nfs4_state *);
 static void nfs_fixup_referral_attributes(struct nfs_fattr *fattr);
+static int nfs4_proc_getattr(struct nfs_server *, struct nfs_fh *, struct nfs_fattr *);
 static int _nfs4_proc_getattr(struct nfs_server *server, struct nfs_fh *fhandle, struct nfs_fattr *fattr);
 static int nfs4_do_setattr(struct inode *inode, struct rpc_cred *cred,
 			    struct nfs_fattr *fattr, struct iattr *sattr,
@@ -2363,6 +2364,31 @@
 	return nfs4_map_errors(status);
 }
 
+static int nfs4_proc_get_root(struct nfs_server *server, struct nfs_fh *mntfh,
+			      struct nfs_fsinfo *info)
+{
+	int error;
+	struct nfs_fattr *fattr = info->fattr;
+
+	error = nfs4_server_capabilities(server, mntfh);
+	if (error < 0) {
+		dprintk("nfs4_get_root: getcaps error = %d\n", -error);
+		return error;
+	}
+
+	error = nfs4_proc_getattr(server, mntfh, fattr);
+	if (error < 0) {
+		dprintk("nfs4_get_root: getattr error = %d\n", -error);
+		return error;
+	}
+
+	if (fattr->valid & NFS_ATTR_FATTR_FSID &&
+	    !nfs_fsid_equal(&server->fsid, &fattr->fsid))
+		memcpy(&server->fsid, &fattr->fsid, sizeof(server->fsid));
+
+	return error;
+}
+
 /*
  * Get locations and (maybe) other attributes of a referral.
  * Note that we'll actually follow the referral later when
@@ -6539,7 +6565,7 @@
 	.dir_inode_ops	= &nfs4_dir_inode_operations,
 	.file_inode_ops	= &nfs4_file_inode_operations,
 	.file_ops	= &nfs4_file_operations,
-	.getroot	= nfs4_proc_get_rootfh,
+	.getroot	= nfs4_proc_get_root,
 	.submount	= nfs4_submount,
 	.getattr	= nfs4_proc_getattr,
 	.setattr	= nfs4_proc_setattr,