ext4: Convert mext_page_mkuptodate() to take a folio

Use a folio throughout.  Does not support large folios due to
an array sized for MAX_BUF_PER_PAGE, but it does remove a few
calls to compound_head().

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Link: https://lore.kernel.org/r/20230324180129.1220691-28-willy@infradead.org
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

fs/ext4/move_extent.c

@@ -168,25 +168,27 @@ mext_folio_double_lock(struct inode *inode1, struct inode *inode2,
 
 /* Force page buffers uptodate w/o dropping page's lock */
 static int
-mext_page_mkuptodate(struct page *page, unsigned from, unsigned to)
+mext_page_mkuptodate(struct folio *folio, unsigned from, unsigned to)
 {
-	struct inode *inode = page->mapping->host;
+	struct inode *inode = folio->mapping->host;
 	sector_t block;
 	struct buffer_head *bh, *head, *arr[MAX_BUF_PER_PAGE];
 	unsigned int blocksize, block_start, block_end;
 	int i, err,  nr = 0, partial = 0;
-	BUG_ON(!PageLocked(page));
-	BUG_ON(PageWriteback(page));
+	BUG_ON(!folio_test_locked(folio));
+	BUG_ON(folio_test_writeback(folio));
 
-	if (PageUptodate(page))
+	if (folio_test_uptodate(folio))
 		return 0;
 
 	blocksize = i_blocksize(inode);
-	if (!page_has_buffers(page))
-		create_empty_buffers(page, blocksize, 0);
+	head = folio_buffers(folio);
+	if (!head) {
+		create_empty_buffers(&folio->page, blocksize, 0);
+		head = folio_buffers(folio);
+	}
 
-	head = page_buffers(page);
-	block = (sector_t)page->index << (PAGE_SHIFT - inode->i_blkbits);
+	block = (sector_t)folio->index << (PAGE_SHIFT - inode->i_blkbits);
 	for (bh = head, block_start = 0; bh != head || !block_start;
 	     block++, block_start = block_end, bh = bh->b_this_page) {
 		block_end = block_start + blocksize;
@@ -200,11 +202,11 @@ mext_page_mkuptodate(struct page *page, unsigned from, unsigned to)
 		if (!buffer_mapped(bh)) {
 			err = ext4_get_block(inode, block, bh, 0);
 			if (err) {
-				SetPageError(page);
+				folio_set_error(folio);
 				return err;
 			}
 			if (!buffer_mapped(bh)) {
-				zero_user(page, block_start, blocksize);
+				folio_zero_range(folio, block_start, blocksize);
 				set_buffer_uptodate(bh);
 				continue;
 			}
@@ -226,7 +228,7 @@ mext_page_mkuptodate(struct page *page, unsigned from, unsigned to)
 	}
 out:
 	if (!partial)
-		SetPageUptodate(page);
+		folio_mark_uptodate(folio);
 	return 0;
 }
 
@@ -354,7 +356,7 @@ again:
 		goto unlock_folios;
 	}
 data_copy:
-	*err = mext_page_mkuptodate(&folio[0]->page, from, from + replaced_size);
+	*err = mext_page_mkuptodate(folio[0], from, from + replaced_size);
 	if (*err)
 		goto unlock_folios;