I'll try to recreate this later on, thanks for the detailed test steps
** Description changed:
On Bionic, Qemu complains that it cannot acquire write lock when
commiting a snapshot if a read-only backing-store is opened by another
qemu process. This behavior does not happen with version 2.12 in Cosmic.
Reproducer
==========
Create two QCOW2 containers sharing the same base file as a backing store :
- base.qcow2
- |
- +---------+---------+
- | |
- middle-vm02.img middle-vm02.img
- | |
+ base.qcow2
+ |
+ +---------+---------+
+ | |
+ middle-vm01.img middle-vm02.img
+ | |
top-vm01.img top-vm02.img
# cat mkimage
#!/bin/bash
qemu-img create -f qcow2 base.qcow2 10G
qemu-img create -f qcow2 -b base.qcow2 middle-vm01.img 10G
qemu-img create -f qcow2 -b base.qcow2 middle-vm02.img 10G
qemu-img create -f qcow2 -b middle-vm01.img top-vm01.img 10G
qemu-img create -f qcow2 -b middle-vm01.img top-vm02.img 10G
-
Start two VM each using its own top-vm{id}.img
- # cat runvm
+ # cat runvm
#!/bin/bash
qemu-system-x86_64 -nographic -qmp unix:./qmp-1.sock,server,nowait
-enable-kvm -device virtio-scsi-pci,id=scsi -device sga -nodefaults
-monitor none -m 256M -drive file=./top-vm01.img,if=virtio,id=disk0 -smp 1
-smbios type=1,manufacturer=test&
qemu-system-x86_64 -nographic -qmp unix:./qmp-2.sock,server,nowait
-enable-kvm -device virtio-scsi-pci,id=scsi -device sga -nodefaults
-monitor none -m 256M -drive file=./top-vm02.img,if=virtio,id=disk0 -smp 1
-smbios type=1,manufacturer=test&
Create a snapshot
./scripts/qmp/qmp-shell ./qmp-1.sock
Welcome to the QMP low-level shell!
Connected to QEMU 2.11.1
(QEMU) blockdev-snapshot-sync device=disk0 snapshot-file=tmp.qcow2
format=qcow2
Formatting 'tmp.qcow2', fmt=qcow2 size=10737418240
backing_file=./top-vm01.img backing_fmt=qcow2 cluster_size=65536
lazy_refcounts=off refcount_bits=16
{"return": {}}
Commit the snapshot
(QEMU) block-commit device=disk0 base=top-vm01.img
{"error": {"class": "GenericError", "desc": "Failed to get \"write\" lock"}}
-
Expected Behavior
=================
The commit should complete succesfully as the base.img backing store is
opened read-only so no write lock is required
Current Behavior
================
The commit fails with "Failed to get "write" lock
** Description changed:
On Bionic, Qemu complains that it cannot acquire write lock when
commiting a snapshot if a read-only backing-store is opened by another
qemu process. This behavior does not happen with version 2.12 in Cosmic.
Reproducer
==========
Create two QCOW2 containers sharing the same base file as a backing store :
base.qcow2
|
+---------+---------+
- | |
+ | |
middle-vm01.img middle-vm02.img
| |
top-vm01.img top-vm02.img
# cat mkimage
#!/bin/bash
qemu-img create -f qcow2 base.qcow2 10G
qemu-img create -f qcow2 -b base.qcow2 middle-vm01.img 10G
qemu-img create -f qcow2 -b base.qcow2 middle-vm02.img 10G
qemu-img create -f qcow2 -b middle-vm01.img top-vm01.img 10G
qemu-img create -f qcow2 -b middle-vm01.img top-vm02.img 10G
Start two VM each using its own top-vm{id}.img
# cat runvm
#!/bin/bash
qemu-system-x86_64 -nographic -qmp unix:./qmp-1.sock,server,nowait
-enable-kvm -device virtio-scsi-pci,id=scsi -device sga -nodefaults
-monitor none -m 256M -drive file=./top-vm01.img,if=virtio,id=disk0 -smp 1
-smbios type=1,manufacturer=test&
qemu-system-x86_64 -nographic -qmp unix:./qmp-2.sock,server,nowait
-enable-kvm -device virtio-scsi-pci,id=scsi -device sga -nodefaults
-monitor none -m 256M -drive file=./top-vm02.img,if=virtio,id=disk0 -smp 1
-smbios type=1,manufacturer=test&
Create a snapshot
./scripts/qmp/qmp-shell ./qmp-1.sock
Welcome to the QMP low-level shell!
Connected to QEMU 2.11.1
(QEMU) blockdev-snapshot-sync device=disk0 snapshot-file=tmp.qcow2
format=qcow2
Formatting 'tmp.qcow2', fmt=qcow2 size=10737418240
backing_file=./top-vm01.img backing_fmt=qcow2 cluster_size=65536
lazy_refcounts=off refcount_bits=16
{"return": {}}
Commit the snapshot
(QEMU) block-commit device=disk0 base=top-vm01.img
{"error": {"class": "GenericError", "desc": "Failed to get \"write\" lock"}}
Expected Behavior
=================
The commit should complete succesfully as the base.img backing store is
opened read-only so no write lock is required
Current Behavior
================
The commit fails with "Failed to get "write" lock
** Description changed:
On Bionic, Qemu complains that it cannot acquire write lock when
commiting a snapshot if a read-only backing-store is opened by another
qemu process. This behavior does not happen with version 2.12 in Cosmic.
Reproducer
==========
Create two QCOW2 containers sharing the same base file as a backing store :
base.qcow2
|
+---------+---------+
- | |
+ |-------------------|
middle-vm01.img middle-vm02.img
- | |
+ |-------------------|
top-vm01.img top-vm02.img
# cat mkimage
#!/bin/bash
qemu-img create -f qcow2 base.qcow2 10G
qemu-img create -f qcow2 -b base.qcow2 middle-vm01.img 10G
qemu-img create -f qcow2 -b base.qcow2 middle-vm02.img 10G
qemu-img create -f qcow2 -b middle-vm01.img top-vm01.img 10G
qemu-img create -f qcow2 -b middle-vm01.img top-vm02.img 10G
Start two VM each using its own top-vm{id}.img
# cat runvm
#!/bin/bash
qemu-system-x86_64 -nographic -qmp unix:./qmp-1.sock,server,nowait
-enable-kvm -device virtio-scsi-pci,id=scsi -device sga -nodefaults
-monitor none -m 256M -drive file=./top-vm01.img,if=virtio,id=disk0 -smp 1
-smbios type=1,manufacturer=test&
qemu-system-x86_64 -nographic -qmp unix:./qmp-2.sock,server,nowait
-enable-kvm -device virtio-scsi-pci,id=scsi -device sga -nodefaults
-monitor none -m 256M -drive file=./top-vm02.img,if=virtio,id=disk0 -smp 1
-smbios type=1,manufacturer=test&
Create a snapshot
./scripts/qmp/qmp-shell ./qmp-1.sock
Welcome to the QMP low-level shell!
Connected to QEMU 2.11.1
(QEMU) blockdev-snapshot-sync device=disk0 snapshot-file=tmp.qcow2
format=qcow2
Formatting 'tmp.qcow2', fmt=qcow2 size=10737418240
backing_file=./top-vm01.img backing_fmt=qcow2 cluster_size=65536
lazy_refcounts=off refcount_bits=16
{"return": {}}
Commit the snapshot
(QEMU) block-commit device=disk0 base=top-vm01.img
{"error": {"class": "GenericError", "desc": "Failed to get \"write\" lock"}}
Expected Behavior
=================
The commit should complete succesfully as the base.img backing store is
opened read-only so no write lock is required
Current Behavior
================
The commit fails with "Failed to get "write" lock
** Description changed:
On Bionic, Qemu complains that it cannot acquire write lock when
commiting a snapshot if a read-only backing-store is opened by another
qemu process. This behavior does not happen with version 2.12 in Cosmic.
Reproducer
==========
Create two QCOW2 containers sharing the same base file as a backing store :
base.qcow2
|
+---------+---------+
|-------------------|
middle-vm01.img middle-vm02.img
|-------------------|
- top-vm01.img top-vm02.img
+ top-vm01.img ---- top-vm02.img
# cat mkimage
#!/bin/bash
qemu-img create -f qcow2 base.qcow2 10G
qemu-img create -f qcow2 -b base.qcow2 middle-vm01.img 10G
qemu-img create -f qcow2 -b base.qcow2 middle-vm02.img 10G
qemu-img create -f qcow2 -b middle-vm01.img top-vm01.img 10G
qemu-img create -f qcow2 -b middle-vm01.img top-vm02.img 10G
Start two VM each using its own top-vm{id}.img
# cat runvm
#!/bin/bash
qemu-system-x86_64 -nographic -qmp unix:./qmp-1.sock,server,nowait
-enable-kvm -device virtio-scsi-pci,id=scsi -device sga -nodefaults
-monitor none -m 256M -drive file=./top-vm01.img,if=virtio,id=disk0 -smp 1
-smbios type=1,manufacturer=test&
qemu-system-x86_64 -nographic -qmp unix:./qmp-2.sock,server,nowait
-enable-kvm -device virtio-scsi-pci,id=scsi -device sga -nodefaults
-monitor none -m 256M -drive file=./top-vm02.img,if=virtio,id=disk0 -smp 1
-smbios type=1,manufacturer=test&
Create a snapshot
./scripts/qmp/qmp-shell ./qmp-1.sock
Welcome to the QMP low-level shell!
Connected to QEMU 2.11.1
(QEMU) blockdev-snapshot-sync device=disk0 snapshot-file=tmp.qcow2
format=qcow2
Formatting 'tmp.qcow2', fmt=qcow2 size=10737418240
backing_file=./top-vm01.img backing_fmt=qcow2 cluster_size=65536
lazy_refcounts=off refcount_bits=16
{"return": {}}
Commit the snapshot
(QEMU) block-commit device=disk0 base=top-vm01.img
{"error": {"class": "GenericError", "desc": "Failed to get \"write\" lock"}}
Expected Behavior
=================
The commit should complete succesfully as the base.img backing store is
opened read-only so no write lock is required
Current Behavior
================
The commit fails with "Failed to get "write" lock
--
You received this bug notification because you are a member of Ubuntu
Bugs, which is subscribed to Ubuntu.
https://bugs.launchpad.net/bugs/1837869
Title:
Cannot complete snapshot if read-only backing store is opened by
another VM
To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/qemu/+bug/1837869/+subscriptions
--
ubuntu-bugs mailing list
ubuntu-bugs@lists.ubuntu.com
https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
