Mail.ru: file read on MCS servers via supplying a QCOW2 image with external backing file

Local file read in mcs.mail.ru by providing QCOW2 disk image with backing image pointing to external file Mail.ru Cloud Solutions allows uploading custom images for disks. This functionality supported QCOW2 disk images. A QCOW2 disk image can have a so-called "backing image" - a file to read...