[Qemu-devel] block-commit & dropping privs

[Michael Tokarev <mjt@tls.msk.ru>]

Hello.

I tried to experiment with block-commit command, which propagates
changes accumulated in an overlay (qcow2) block image file back to
the base image file.

And immediately faced a problem.  All my VMs are run chrooted into
an empty dir and with low-priv user (using -runsa and -chroot options,
initially started as root).  Ofcourse this low-priv qemu process
can't open the base image anymore, because it doesn't have the
necessary permissions and because the base file is inaccessible
within the chroot.

So I wonder if we can avoid reopening the base img by always opening
it read-write (using a command-line option), does it make sense?

Or maybe there's some other possible solution to this, for example,
passing in a filedescriptor for the new base img over a unix socket?

Thanks,

/mjt