new helper: file_inode(file)

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/isofs/compress.c b/fs/isofs/compress.c
index 0b3fa79..592e511 100644
--- a/fs/isofs/compress.c
+++ b/fs/isofs/compress.c
@@ -296,7 +296,7 @@
  */
 static int zisofs_readpage(struct file *file, struct page *page)
 {
-	struct inode *inode = file->f_path.dentry->d_inode;
+	struct inode *inode = file_inode(file);
 	struct address_space *mapping = inode->i_mapping;
 	int err;
 	int i, pcount, full_page;