I've just gotten everything switched to fedora 27, and I'm now finding that guestmount fails on a running VMs disk image. I used to be able to mount --ro and see a read only snapshot of the disk even if the KVM was still running. Now I get a lot of errors when I run:
LIBGUESTFS_DEBUG=1 LIBGUESTFS_TRACE=1 guestmount -d centinil -i --ro mnt
One of the errors that appears is:
qemu-img: /tmp/libguestfssn6HDK/overlay1.qcow2: Failed to get shared "write" lock Is another process using the image?
And, yes, another process is using the image, but --ro used to work even when that was the case.
Should I submit a bug on this, or is this change deliberate?
(The guestmount does seem to work fine once the VM is shut down).
On 12/26/17 07:24, Tom Horsley wrote:
I've just gotten everything switched to fedora 27, and I'm now finding that guestmount fails on a running VMs disk image. I used to be able to mount --ro and see a read only snapshot of the disk even if the KVM was still running. Now I get a lot of errors when I run:
LIBGUESTFS_DEBUG=1 LIBGUESTFS_TRACE=1 guestmount -d centinil -i --ro mnt
One of the errors that appears is:
qemu-img: /tmp/libguestfssn6HDK/overlay1.qcow2: Failed to get shared "write" lock Is another process using the image?
And, yes, another process is using the image, but --ro used to work even when that was the case.
Should I submit a bug on this, or is this change deliberate?
(The guestmount does seem to work fine once the VM is shut down).
I'd never used the guestmount command. In trying it, I found the same situation.
I wonder if this is the same as https://bugs.launchpad.net/qemu/+bug/1721788%C2%A0 ?
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Ed Greshko -
Tom Horsley