[libvirt] [PATCH v4 00/23] Introduce metadata locking

[Bjoern Walk]

Michal Privoznik <mprivozn at redhat.com> [2018-09-19, 11:45AM +0200]:
> On 09/19/2018 11:17 AM, Bjoern Walk wrote:
> > Bjoern Walk <bwalk at linux.ibm.com> [2018-09-12, 01:17PM +0200]:
> >> Michal Privoznik <mprivozn at redhat.com> [2018-09-12, 11:32AM +0200]:
> 
> >>
> > 
> > Still seeing the same timeout. Is this expected behaviour?
> > 
> 
> Nope. I wonder if something has locked the path and forgot to unlock it
> (however, virtlockd should have unlocked all the paths owned by PID on
> connection close), or something is still holding the lock and connection
> opened.

I can reproduce on a freshly booted machine. There should be no rouge
lock held anywhere.

> 
> Can you see the timeout even when you turn off the selinux driver
> (security_driver="none' in qemu.conf)? I tried to reproduce the issue

Yes, same issue.

> yesterday and was unsuccessful. Do you have any steps to reproduce?

0. Host setup:

    # /usr/sbin/sestatus
    SELinux status:                 enabled
    SELinuxfs mount:                /sys/fs/selinux
    SELinux root directory:         /etc/selinux
    Loaded policy name:             targeted
    Current mode:                   enforcing
    Mode from config file:          enforcing
    Policy MLS status:              enabled
    Policy deny_unknown status:     allowed
    Memory protection checking:     actual (secure)
    Max kernel policy version:      31

    # grep -E "^[^#]" /etc/libvirt/qemu.conf
    lock_manager = "lockd"
    metadata_lock_manager = "lockd"

1. Define two domains, u1604-1 and u1604-2, using the same image, not
   shared:

    <domain type='kvm'>
      <name>u1604-1</name>
      <uuid>e49679de-eca9-4a72-8d1a-56f437541157</uuid>
      <memory unit='KiB'>524288</memory>
      <currentMemory unit='KiB'>524288</currentMemory>
      <vcpu placement='static'>2</vcpu>
      <os>
        <type arch='s390x' machine='s390-ccw-virtio-2.12'>hvm</type>
        <boot dev='hd'/>
      </os>
      <clock offset='utc'/>
      <on_poweroff>destroy</on_poweroff>
      <on_reboot>restart</on_reboot>
      <on_crash>preserve</on_crash>
      <devices>
        <emulator>/usr/bin/qemu-system-s390x</emulator>
        <disk type='file' device='disk'>
          <driver name='qemu' type='qcow2'/>
          <source file='/var/lib/libvirt/images/u1604.qcow2'/>
          <target dev='vda' bus='virtio'/>
          <address type='ccw' cssid='0xfe' ssid='0x0' devno='0x0000'/>
        </disk>
        <console type='pty'>
          <target type='sclp' port='0'/>
        </console>
        <memballoon model='virtio'>
          <address type='ccw' cssid='0xfe' ssid='0x0' devno='0x0001'/>
        </memballoon>
        <panic model='s390'/>
      </devices>
    </domain>

2. Start domain u1604-1:

    # ls -Z /var/lib/libvirt/images/u1604.qcow2
    system_u:object_r:svirt_image_t:s0:c387,c937 /var/lib/libvirt/images/u1604.qcow2

3. Start domain u1604-2.

4. Result: the libvirtd hangs for 60 seconds after which the expected
   locking message appears. Security labels of the image are not
   changed:

    # virsh start u1604-2
    error: Failed to start domain u1604-2
    error: internal error: child reported: resource busy: Lockspace resource '/var/lib/libvirt/images/u1604.qcow2' is locked

    # ls -Z /var/lib/libvirt/images/u1604.qcow2
    system_u:object_r:svirt_image_t:s0:c387,c937 /var/lib/libvirt/images/u1604.qcow2

Backtrace is the same I sent earlier.

Let me know if you need more info or if anything is borked in my setup.

> 
> Michal
> 
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