MDEV-16682 Assertion `(buff[7] & 7) == HEAD_PAGE' failed

Missed one file in last push...

Author: montywi

storage/maria/ma_blockrec.c

@@ -53,10 +53,10 @@
  Page header:
 
  LSN 7 bytes Log position for last page change
- PAGE_TYPE 1 uchar 1 for head / 2 for tail / 3 for blob
+ PAGE_TYPE 1 uchar 0 unalloced / 1 for head / 2 for tail / 3 for blob
  DIR_COUNT 1 uchar Number of row/tail entries on page
  FREE_DIR_LINK 1 uchar Pointer to first free director entry or 255 if no
- empty space 2 bytes Empty space on page
+ empty space 2 bytes  Bytes of empty space on page
 
  The most significant bit in PAGE_TYPE is set to 1 if the data on the page
  can be compacted to get more space. (PAGE_CAN_BE_COMPACTED)
@@ -5122,11 +5122,19 @@ int _ma_read_block_record(MARIA_HA *info, uchar *record,
  info->buff, share->page_type,
  PAGECACHE_LOCK_LEFT_UNLOCKED, 0)))
  DBUG_RETURN(my_errno);
- DBUG_ASSERT((buff[PAGE_TYPE_OFFSET] & PAGE_TYPE_MASK) == HEAD_PAGE);
- if (!(data= get_record_position(buff, block_size, offset, &end_of_data)))
+
+ /*
+ Unallocated page access can happen if this is an access to a page where
+ all rows where deleted as part of this statement.
+ */
+ DBUG_ASSERT((buff[PAGE_TYPE_OFFSET] & PAGE_TYPE_MASK) == HEAD_PAGE ||
+ (buff[PAGE_TYPE_OFFSET] & PAGE_TYPE_MASK) == UNALLOCATED_PAGE);
+
+ if (((buff[PAGE_TYPE_OFFSET] & PAGE_TYPE_MASK) == UNALLOCATED_PAGE) ||
+ !(data= get_record_position(buff, block_size, offset, &end_of_data)))
  {
  DBUG_ASSERT(!maria_assert_if_crashed_table);
- DBUG_PRINT("error", ("Wrong directory entry in data block"));
+ DBUG_PRINT("warning", ("Wrong directory entry in data block"));
  my_errno= HA_ERR_RECORD_DELETED; /* File crashed */
  DBUG_RETURN(HA_ERR_RECORD_DELETED);
  }