new helper: file_inode(file)

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/romfs/super.c b/fs/romfs/super.c
index fd7c5f6..7e8d3a8 100644
--- a/fs/romfs/super.c
+++ b/fs/romfs/super.c
@@ -147,7 +147,7 @@
  */
 static int romfs_readdir(struct file *filp, void *dirent, filldir_t filldir)
 {
-	struct inode *i = filp->f_dentry->d_inode;
+	struct inode *i = file_inode(filp);
 	struct romfs_inode ri;
 	unsigned long offset, maxoff;
 	int j, ino, nextfh;