nilfs2: convert nilfs_btnode_commit_change_key to use a folio

Saves one call to compound_head().

Link: https://lkml.kernel.org/r/20231114084436.2755-20-konishi.ryusuke@gmail.comSigned-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

fs/nilfs2/btnode.c

@@ -238,15 +238,15 @@ void nilfs_btnode_commit_change_key(struct address_space *btnc,
 {
 	struct buffer_head *obh = ctxt->bh, *nbh = ctxt->newbh;
 	__u64 oldkey = ctxt->oldkey, newkey = ctxt->newkey;
-	struct page *opage;
+	struct folio *ofolio;
 
 	if (oldkey == newkey)
 		return;
 
 	if (nbh == NULL) {	/* blocksize == pagesize */
-		opage = obh->b_page;
-		if (unlikely(oldkey != opage->index))
-			NILFS_PAGE_BUG(opage,
+		ofolio = obh->b_folio;
+		if (unlikely(oldkey != ofolio->index))
+			NILFS_PAGE_BUG(&ofolio->page,
 				       "invalid oldkey %lld (newkey=%lld)",
 				       (unsigned long long)oldkey,
 				       (unsigned long long)newkey);
@@ -257,8 +257,8 @@ void nilfs_btnode_commit_change_key(struct address_space *btnc,
 		__xa_set_mark(&btnc->i_pages, newkey, PAGECACHE_TAG_DIRTY);
 		xa_unlock_irq(&btnc->i_pages);
 
-		opage->index = obh->b_blocknr = newkey;
-		unlock_page(opage);
+		ofolio->index = obh->b_blocknr = newkey;
+		folio_unlock(ofolio);
 	} else {
 		nilfs_copy_buffer(nbh, obh);
 		mark_buffer_dirty(nbh);