ufs: convert ufs_change_blocknr() to use folios

Convert the locked_page argument to a folio, then use folios throughout. 
Saves three hidden calls to compound_head().

Link: https://lkml.kernel.org/r/20231016201114.1928083-26-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Andreas Gruenbacher <agruenba@redhat.com>
Cc: Pankaj Raghav <p.raghav@samsung.com>
Cc: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

fs/ufs/balloc.c

@@ -240,49 +240,47 @@ static void ufs_change_blocknr(struct inode *inode, sector_t beg,
 			       unsigned int count, sector_t oldb,
 			       sector_t newb, struct page *locked_page)
 {
+	struct folio *folio, *locked_folio = page_folio(locked_page);
 	const unsigned blks_per_page =
 		1 << (PAGE_SHIFT - inode->i_blkbits);
 	const unsigned mask = blks_per_page - 1;
 	struct address_space * const mapping = inode->i_mapping;
 	pgoff_t index, cur_index, last_index;
 	unsigned pos, j, lblock;
 	sector_t end, i;
-	struct page *page;
 	struct buffer_head *head, *bh;
 
 	UFSD("ENTER, ino %lu, count %u, oldb %llu, newb %llu\n",
 	      inode->i_ino, count,
 	     (unsigned long long)oldb, (unsigned long long)newb);
 
-	BUG_ON(!locked_page);
-	BUG_ON(!PageLocked(locked_page));
+	BUG_ON(!folio_test_locked(locked_folio));
 
-	cur_index = locked_page->index;
+	cur_index = locked_folio->index;
 	end = count + beg;
 	last_index = end >> (PAGE_SHIFT - inode->i_blkbits);
 	for (i = beg; i < end; i = (i | mask) + 1) {
 		index = i >> (PAGE_SHIFT - inode->i_blkbits);
 
 		if (likely(cur_index != index)) {
-			page = ufs_get_locked_page(mapping, index);
-			if (!page)/* it was truncated */
+			folio = ufs_get_locked_folio(mapping, index);
+			if (!folio) /* it was truncated */
 				continue;
-			if (IS_ERR(page)) {/* or EIO */
+			if (IS_ERR(folio)) {/* or EIO */
 				ufs_error(inode->i_sb, __func__,
 					  "read of page %llu failed\n",
 					  (unsigned long long)index);
 				continue;
 			}
 		} else
-			page = locked_page;
+			folio = locked_folio;
 
-		head = page_buffers(page);
+		head = folio_buffers(folio);
 		bh = head;
 		pos = i & mask;
 		for (j = 0; j < pos; ++j)
 			bh = bh->b_this_page;
 
-
 		if (unlikely(index == last_index))
 			lblock = end & mask;
 		else
@@ -313,7 +311,7 @@ static void ufs_change_blocknr(struct inode *inode, sector_t beg,
 		} while (bh != head);
 
 		if (likely(cur_index != index))
-			ufs_put_locked_page(page);
+			ufs_put_locked_folio(folio);
  	}
 	UFSD("EXIT\n");
 }