buffer: use b_folio in touch_buffer()

Removes a call to compound_head() in this path.

Link: https://lkml.kernel.org/r/20221215214402.3522366-4-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

fs/buffer.c

@@ -60,7 +60,7 @@ static void submit_bh_wbc(blk_opf_t opf, struct buffer_head *bh,
 inline void touch_buffer(struct buffer_head *bh)
 {
 	trace_block_touch_buffer(bh);
-	mark_page_accessed(bh->b_page);
+	folio_mark_accessed(bh->b_folio);
 }
 EXPORT_SYMBOL(touch_buffer);