On Wed, Jan 06, 2021 at 09:01:45AM +0800, Qu Wenruo wrote:

+static struct extent_buffer *grab_extent_buffer(struct page *page)
+{
+	struct extent_buffer *exists;
+
+	/* Page not yet attached to an extent buffer */
+	if (!PagePrivate(page))
+		return NULL;
+
+	/*
+	 * We could have already allocated an eb for this page
+	 * and attached one so lets see if we can get a ref on
+	 * the existing eb, and if we can we know it's good and
+	 * we can just return that one, else we know we can just
+	 * overwrite page->private.
+	 */

Please reformat comments that get moved to full 80 columns line. Fixed.