new helper: file_inode(file)

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/nilfs2/ioctl.c b/fs/nilfs2/ioctl.c
index fdb1807..ef61c74 100644
--- a/fs/nilfs2/ioctl.c
+++ b/fs/nilfs2/ioctl.c
@@ -793,7 +793,7 @@
 
 long nilfs_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 {
-	struct inode *inode = filp->f_dentry->d_inode;
+	struct inode *inode = file_inode(filp);
 	void __user *argp = (void __user *)arg;
 
 	switch (cmd) {