zyga@pi3-1:~$ losetup --json
{
   "loopdevices": [
      {"name": "/dev/loop0", "sizelimit": "0", "offset": "0", "autoclear": "0", "ro": "0", "back-file": "/writable/system-data/var/lib/snapd/snaps/core_3595.snap"},
      {"name": "/dev/loop1", "sizelimit": "0", "offset": "0", "autoclear": "1", "ro": "0", "back-file": "/writable/system-data/var/lib/snapd/snaps/pi2-kernel_46.snap"},
      {"name": "/dev/loop2", "sizelimit": "0", "offset": "0", "autoclear": "1", "ro": "1", "back-file": "/var/lib/snapd/snaps/pi2-kernel_44.snap"},
      {"name": "/dev/loop3", "sizelimit": "0", "offset": "0", "autoclear": "1", "ro": "1", "back-file": "/var/lib/snapd/snaps/core_3437.snap"},
      {"name": "/dev/loop4", "sizelimit": "0", "offset": "0", "autoclear": "1", "ro": "1", "back-file": "/var/lib/snapd/snaps/pi3_22.snap"},
      {"name": "/dev/loop5", "sizelimit": "0", "offset": "0", "autoclear": "1", "ro": "1", "back-file": "/var/lib/snapd/snaps/core_3595.snap"},
      {"name": "/dev/loop6", "sizelimit": "0", "offset": "0", "autoclear": "1", "ro": "1", "back-file": "/var/lib/snapd/snaps/pi2-kernel_46.snap"},
      {"name": "/dev/loop7", "sizelimit": "0", "offset": "0", "autoclear": "1", "ro": "1", "back-file": "/var/lib/snapd/snaps/core_3587.snap"},
      {"name": "/dev/loop8", "sizelimit": "0", "offset": "0", "autoclear": "1", "ro": "1", "back-file": "/var/lib/snapd/snaps/pi2-kernel_45.snap"},
      {"name": "/dev/loop9", "sizelimit": "0", "offset": "0", "autoclear": "1", "ro": "1", "back-file": "/var/lib/snapd/snaps/htop_71.snap"}
   ]
}