RFE: More info in qemu-img info/check

[Cole Robinson]

Originally filed in Fedora bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=861375

"""
qemu-img info currently give me info like this:

image: /home/alex/.local/share/gnome-boxes/images/Fedora 16
file format: qcow2
virtual size: 11G (11794287616 bytes)
disk size: 4.5G
cluster_size: 65536

In order to figure out the "health" of an image there is some more information I would like:

in-use disk size - I.e the subset of disk size that is not marked as unused due to e.g. TRIM operations

amount of compressed clusters. I.e. "is it useful to re-compress the image".

Fragmentation estimation.

This would be useful to both sysadmins in general and for automated things like
what we want to do in gnome-boxes:
https://bugzilla.gnome.org/show_bug.cgi?id=685032
"""

As mentioned in the original report, qemu-img check currently has fragmentation stats, but only for QED.

[Kevin Wolf (kwolf-redhat)]

qemu-img check has reported allocated clusters, compressed clusters and fragmentation for qcow2 images since February 2013 (QEMU 1.5).