new helper: file_inode(file)

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/splice.c b/fs/splice.c
index 6909d89d0..963213d 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -1170,7 +1170,7 @@
 	 * randomly drop data for eg socket -> socket splicing. Use the
 	 * piped splicing for that!
 	 */
-	i_mode = in->f_path.dentry->d_inode->i_mode;
+	i_mode = file_inode(in)->i_mode;
 	if (unlikely(!S_ISREG(i_mode) && !S_ISBLK(i_mode)))
 		return -EINVAL;