btrfs: remove folio_test_ordered() usage

This involves:

- The ASSERT() inside end_bbio_data_write()
  It's only an ASSERT() and it has never been triggered as far as I
  know.

- btrfs_migrate_folio()
  Since all folio_test_ordered() usage will be removed, there is no need to
  copy the folio ordered flag.

- The ASSERT() inside btrfs_invalidate_folio()
  This one has its usefulness as it indeed caught some bugs during
  development.
  But that's the last user and will not be worth the folio flag or the
  subpage bitmap.

This will allow btrfs to finally remove the ordered flags.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/extent_io.c

@@ -530,7 +530,6 @@ static void end_bbio_data_write(struct btrfs_bio *bbio)
 		u32 len = fi.length;
 
 		bio_size += len;
-		ASSERT(btrfs_folio_test_ordered(fs_info, folio, start, len));
 		btrfs_folio_clear_ordered(fs_info, folio, start, len);
 		btrfs_folio_clear_writeback(fs_info, folio, start, len);
 	}

fs/btrfs/inode.c

@@ -7499,12 +7499,6 @@ static int btrfs_migrate_folio(struct address_space *mapping,
 
 	if (ret)
 		return ret;
-
-	if (folio_test_ordered(src)) {
-		folio_clear_ordered(src);
-		folio_set_ordered(dst);
-	}
-
 	return 0;
 }
 #else
@@ -7672,12 +7666,6 @@ next:
 	}
 	btrfs_folio_clear_dirty(fs_info, folio, page_start, folio_size(folio));
 	btrfs_clear_folio_dirty_tag(folio);
-	/*
-	 * We have iterated through all ordered extents of the page, the page
-	 * should not have Ordered anymore, or the above iteration
-	 * did something wrong.
-	 */
-	ASSERT(!folio_test_ordered(folio));
 	if (!inode_evicting)
 		__btrfs_release_folio(folio, GFP_NOFS);
 	clear_folio_extent_mapped(folio);