NFS: Use cached page as buffer for NFS symlink requests

Now that we have a copy of the symlink path in the page cache, we can pass
a struct page down to the XDR routines instead of a string buffer.

Test plan:
Connectathon, all NFS versions.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/fs/nfs/proc.c b/fs/nfs/proc.c
index 0b507bf..630e506 100644
--- a/fs/nfs/proc.c
+++ b/fs/nfs/proc.c
@@ -425,8 +425,8 @@
 }
 
 static int
-nfs_proc_symlink(struct inode *dir, struct dentry *dentry, struct qstr *path,
-		 struct iattr *sattr)
+nfs_proc_symlink(struct inode *dir, struct dentry *dentry, struct page *page,
+		 unsigned int len, struct iattr *sattr)
 {
 	struct nfs_fh fhandle;
 	struct nfs_fattr fattr;
@@ -434,8 +434,8 @@
 		.fromfh		= NFS_FH(dir),
 		.fromname	= dentry->d_name.name,
 		.fromlen	= dentry->d_name.len,
-		.topath		= path->name,
-		.tolen		= path->len,
+		.pages		= &page,
+		.pathlen	= len,
 		.sattr		= sattr
 	};
 	struct rpc_message msg = {
@@ -444,11 +444,11 @@
 	};
 	int			status;
 
-	if (path->len > NFS2_MAXPATHLEN)
+	if (len > NFS2_MAXPATHLEN)
 		return -ENAMETOOLONG;
 
-	dprintk("NFS call  symlink %s -> %s\n", dentry->d_name.name,
-			path->name);
+	dprintk("NFS call  symlink %s\n", dentry->d_name.name);
+
 	status = rpc_call_sync(NFS_CLIENT(dir), &msg, 0);
 	nfs_mark_for_revalidate(dir);