gfs2: convert gfs2_write_jdata_page() to gfs2_write_jdata_folio()

Add support for large folios and remove some accesses to page->mapping and
page->index.

Link: https://lkml.kernel.org/r/20230612210141.730128-4-willy@infradead.orgSigned-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Tested-by: Bob Peterson <rpeterso@redhat.com>
Reviewed-by: Bob Peterson <rpeterso@redhat.com>
Reviewed-by: Andreas Gruenbacher <agruenba@redhat.com>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

fs/gfs2/aops.c

@@ -82,33 +82,33 @@ static int gfs2_get_block_noalloc(struct inode *inode, sector_t lblock,
 }
 
 /**
- * gfs2_write_jdata_page - gfs2 jdata-specific version of block_write_full_page
- * @page: The page to write
+ * gfs2_write_jdata_folio - gfs2 jdata-specific version of block_write_full_page
+ * @folio: The folio to write
  * @wbc: The writeback control
  *
  * This is the same as calling block_write_full_page, but it also
  * writes pages outside of i_size
  */
-static int gfs2_write_jdata_page(struct page *page,
+static int gfs2_write_jdata_folio(struct folio *folio,
 				 struct writeback_control *wbc)
 {
-	struct inode * const inode = page->mapping->host;
+	struct inode * const inode = folio->mapping->host;
 	loff_t i_size = i_size_read(inode);
-	const pgoff_t end_index = i_size >> PAGE_SHIFT;
-	unsigned offset;
 
 	/*
-	 * The page straddles i_size.  It must be zeroed out on each and every
+	 * The folio straddles i_size.  It must be zeroed out on each and every
 	 * writepage invocation because it may be mmapped.  "A file is mapped
 	 * in multiples of the page size.  For a file that is not a multiple of
 	 * the page size, the remaining memory is zeroed when mapped, and
 	 * writes to that region are not written out to the file."
 	 */
-	offset = i_size & (PAGE_SIZE - 1);
-	if (page->index == end_index && offset)
-		zero_user_segment(page, offset, PAGE_SIZE);
+	if (folio_pos(folio) < i_size &&
+	    i_size < folio_pos(folio) + folio_size(folio))
+		folio_zero_segment(folio, offset_in_folio(folio, i_size),
+				folio_size(folio));
 
-	return __block_write_full_page(inode, page, gfs2_get_block_noalloc, wbc,
+	return __block_write_full_page(inode, &folio->page,
+				       gfs2_get_block_noalloc, wbc,
 				       end_buffer_async_write);
 }
 
@@ -137,7 +137,7 @@ static int __gfs2_jdata_write_folio(struct folio *folio,
 		}
 		gfs2_trans_add_databufs(ip, folio, 0, folio_size(folio));
 	}
-	return gfs2_write_jdata_page(&folio->page, wbc);
+	return gfs2_write_jdata_folio(folio, wbc);
 }
 
 /**