new helper: file_inode(file)

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/ext4/file.c b/fs/ext4/file.c
index 405565a6..c00ea79 100644
--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -167,7 +167,7 @@
 ext4_file_write(struct kiocb *iocb, const struct iovec *iov,
 		unsigned long nr_segs, loff_t pos)
 {
-	struct inode *inode = iocb->ki_filp->f_path.dentry->d_inode;
+	struct inode *inode = file_inode(iocb->ki_filp);
 	ssize_t ret;
 
 	/*