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Description of problem:
Incorrect error messages when 2 guests on 1 host pointing at the same disk in non-shareable mode while virtlockd is enabled
Version-Release number of selected component (if applicable):
libvirt-3.9.0-1.el7.x86_64
kernel-3.10.0-766.el7.x86_64
qemu-kvm-rhev-2.10.0-4.el7.x86_64
How reproducible:
100%
Steps to Reproduce:
1. Prepare two guests which use one image without <shareable> element.
<disk type='file' device='disk'>
<driver name='qemu' type='raw' cache='none'/>
<source file='/var/lib/libvirt/images/lmn.qcow2'/>
<target dev='hda' bus='ide'/>
<address type='drive' controller='0' bus='0' target='0' unit='0'/>
</disk>
2. Config /etc/libvirt/qemu-lockd.conf.
#vim /etc/libvirt/qemu-lockd.conf
auto_disk_leases = 1
require_lease_for_disks = 1
file_lockspace_dir = "/var/lib/libvirt/lockd/files"
#vim /etc/libvirt/qemu.conf
lock_manager = "lockd"
3. Service start
#systemctl start virtlockd
#systemctl restart libvirtd
4. Start two guest.
# virsh start lmn
Domain lmn started
# virsh start test
error: Failed to start domain test
error: internal error: process exited while connecting to monitor: 2017-11-07T09:53:44.435636Z qemu-kvm: -chardev pty,id=charserial0: char device redirected to /dev/pts/4 (label charserial0)
2017-11-07T09:53:44.437831Z qemu-kvm: -drive file=/var/lib/libvirt/images/lmn.qcow2,format=qcow2,if=none,id=drive-virtio-disk0,cache=none,aio=native: Failed to get "write" lock
Is another process using the image?
Actual results:
As above descriptions.
Expected results:
# virsh start test
error: Failed to start domain test
error: resource busy: Lockspace resource '9e03fed04cb6a2f32f6624b47d212acb06d97653a02627d824b89fcf74c175bb' is locked
Additional info:
The error messages is expected in the following scenario:
(1)The above test steps in libvirt-3.2.0-14.el7_4.3.x86_64;
(2)Pointing at the same lvm/scsi device in none-shareable mode;
(3)2 guests on 2 hosts pointing at the same disk in none-shareable mode.
This is expected. The locking driver in libvirt will try to acquire the lock only when the vCPUs are being started. Due to the changes to qemu to add internal image locking, the message produced by qemu is reported at the point when the image is being opened (thus before vCPUs are started).
Since qemu is able to handle the locks only on one host, the locking daemon is still necessary. (That covers the iscsi/lvm/scsi case too).
note that for case 1) in additional notes, the difference is also in the qemu package, which actually reports the error.
The shared mode would not work though, but that is tracked by a combination of
https://bugzilla.redhat.com/show_bug.cgi?id=1378242
and
https://bugzilla.redhat.com/show_bug.cgi?id=1511480
The behavior here is expected.
Description of problem: Incorrect error messages when 2 guests on 1 host pointing at the same disk in non-shareable mode while virtlockd is enabled Version-Release number of selected component (if applicable): libvirt-3.9.0-1.el7.x86_64 kernel-3.10.0-766.el7.x86_64 qemu-kvm-rhev-2.10.0-4.el7.x86_64 How reproducible: 100% Steps to Reproduce: 1. Prepare two guests which use one image without <shareable> element. <disk type='file' device='disk'> <driver name='qemu' type='raw' cache='none'/> <source file='/var/lib/libvirt/images/lmn.qcow2'/> <target dev='hda' bus='ide'/> <address type='drive' controller='0' bus='0' target='0' unit='0'/> </disk> 2. Config /etc/libvirt/qemu-lockd.conf. #vim /etc/libvirt/qemu-lockd.conf auto_disk_leases = 1 require_lease_for_disks = 1 file_lockspace_dir = "/var/lib/libvirt/lockd/files" #vim /etc/libvirt/qemu.conf lock_manager = "lockd" 3. Service start #systemctl start virtlockd #systemctl restart libvirtd 4. Start two guest. # virsh start lmn Domain lmn started # virsh start test error: Failed to start domain test error: internal error: process exited while connecting to monitor: 2017-11-07T09:53:44.435636Z qemu-kvm: -chardev pty,id=charserial0: char device redirected to /dev/pts/4 (label charserial0) 2017-11-07T09:53:44.437831Z qemu-kvm: -drive file=/var/lib/libvirt/images/lmn.qcow2,format=qcow2,if=none,id=drive-virtio-disk0,cache=none,aio=native: Failed to get "write" lock Is another process using the image? Actual results: As above descriptions. Expected results: # virsh start test error: Failed to start domain test error: resource busy: Lockspace resource '9e03fed04cb6a2f32f6624b47d212acb06d97653a02627d824b89fcf74c175bb' is locked Additional info: The error messages is expected in the following scenario: (1)The above test steps in libvirt-3.2.0-14.el7_4.3.x86_64; (2)Pointing at the same lvm/scsi device in none-shareable mode; (3)2 guests on 2 hosts pointing at the same disk in none-shareable mode.