new helper: file_inode(file)

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/logfs/file.c b/fs/logfs/file.c
index 3886cde..c2219a6 100644
--- a/fs/logfs/file.c
+++ b/fs/logfs/file.c
@@ -183,7 +183,7 @@
 
 long logfs_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 {
-	struct inode *inode = file->f_path.dentry->d_inode;
+	struct inode *inode = file_inode(file);
 	struct logfs_inode *li = logfs_inode(inode);
 	unsigned int oldflags, flags;
 	int err;