switch dentry_open() to struct path, make it grab references itself

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index 05d9eee..4700a0a 100644
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -745,7 +745,7 @@
 nfsd_open(struct svc_rqst *rqstp, struct svc_fh *fhp, umode_t type,
 			int may_flags, struct file **filp)
 {
-	struct dentry	*dentry;
+	struct path	path;
 	struct inode	*inode;
 	int		flags = O_RDONLY|O_LARGEFILE;
 	__be32		err;
@@ -762,8 +762,9 @@
 	if (err)
 		goto out;
 
-	dentry = fhp->fh_dentry;
-	inode = dentry->d_inode;
+	path.mnt = fhp->fh_export->ex_path.mnt;
+	path.dentry = fhp->fh_dentry;
+	inode = path.dentry->d_inode;
 
 	/* Disallow write access to files with the append-only bit set
 	 * or any access when mandatory locking enabled
@@ -792,8 +793,7 @@
 		else
 			flags = O_WRONLY|O_LARGEFILE;
 	}
-	*filp = dentry_open(dget(dentry), mntget(fhp->fh_export->ex_path.mnt),
-			    flags, current_cred());
+	*filp = dentry_open(&path, flags, current_cred());
 	if (IS_ERR(*filp))
 		host_err = PTR_ERR(*filp);
 	else {