With compressed data being written by the client, it potentially becomes possible to pack a considerable amount of data directly into the MDT inode with DoM together with the ext4 inline_data feature.
Currently, the inline_data feature might allow ~512 bytes of data to be stored directly in the 1024-byte MDT inode (after layout and other xattrs are added), but with compression this might be 1-2KiB depending on the file contents.
Note however, that there is some development work needed for inline_data to work together with the dir_data feature.
EX-7806 has not landed yet, close the ticket and verify when it lands