[Bug 1881648] Re: `qemu-img info` reports an incorrect actual-size when the underlying posix filesystem has transparent compression

[Ubuntu QA Website]

This bug has been reported on the Ubuntu ISO testing tracker.

A list of all reports related to this bug can be found here:
http://iso.qa.ubuntu.com/qatracker/reports/bugs/1881648

** Tags added: iso-testing

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https://bugs.launchpad.net/bugs/1881648

Title:
  `qemu-img info` reports an incorrect actual-size when the underlying
  posix filesystem has transparent compression

Status in QEMU:
  Invalid

Bug description:
  qemu-img info reports the same thing as `du`*1024:

  $ qemu-img info --output json ./my.qcow2  | jq '."actual-size"'
  558619648

  $ du ./my.qcow2
  545527        ./my.qcow2

  $ echo $((558619648 / 545527))
  1024

  and this is correct in terms of bytes on disk, but due to transparent
  compression implemented by the filesystem, it is not the actual byte
  count:

  $ du -h --apparent-size ./my.qcow2
  1346568192    my.qcow2

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