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f234dc9366
The virtlockd daemon maintains file locks on behalf of libvirtd
and any VMs it is running. These file locks must be held for as
long as any VM is running. If virtlockd itself ever quits, then
it is expected that a node would be fenced/rebooted. Thus to
allow for software upgrads on live systemd, virtlockd needs the
ability to re-exec() itself.
Upon receipt of SIGUSR1, virtlockd will save its current live
state out to a file /var/run/virtlockd-restart-exec.json
It then re-exec()'s itself with exactly the same argv as it
originally had, and loads the state file, reconstructing any
objects as appropriate.
The state file contains information about all locks held and
all network services and clients currently active. An example
state document is
{
"server": {
"min_workers": 1,
"max_workers": 20,
"priority_workers": 0,
"max_clients": 20,
"keepaliveInterval": 4294967295,
"keepaliveCount": 0,
"keepaliveRequired": false,
"services": [
{
"auth": 0,
"readonly": false,
"nrequests_client_max": 1,
"socks": [
{
"fd": 6,
"errfd": -1,
"pid": 0,
"isClient": false
}
]
}
],
"clients": [
{
"auth": 0,
"readonly": false,
"nrequests_max": 1,
"sock": {
"fd": 9,
"errfd": -1,
"pid": 0,
"isClient": true
},
"privateData": {
"restricted": true,
"ownerPid": 1722,
"ownerId": 6,
"ownerName": "f18x86_64",
"ownerUUID": "97586ba9-df27-9459-c806-f016c8bbd224"
}
},
{
"auth": 0,
"readonly": false,
"nrequests_max": 1,
"sock": {
"fd": 10,
"errfd": -1,
"pid": 0,
"isClient": true
},
"privateData": {
"restricted": true,
"ownerPid": 1784,
"ownerId": 7,
"ownerName": "f16x86_64",
"ownerUUID": "7b8e5e42-b875-61e9-b981-91ad8fa46979"
}
}
]
},
"defaultLockspace": {
"resources": [
{
"name": "/var/lib/libvirt/images/f16x86_64.raw",
"path": "/var/lib/libvirt/images/f16x86_64.raw",
"fd": 14,
"lockHeld": true,
"flags": 0,
"owners": [
1784
]
},
{
"name": "/var/lib/libvirt/images/shared.img",
"path": "/var/lib/libvirt/images/shared.img",
"fd": 12,
"lockHeld": true,
"flags": 1,
"owners": [
1722,
1784
]
},
{
"name": "/var/lib/libvirt/images/f18x86_64.img",
"path": "/var/lib/libvirt/images/f18x86_64.img",
"fd": 11,
"lockHeld": true,
"flags": 0,
"owners": [
1722
]
}
]
},
"lockspaces": [
],
"magic": "30199"
}
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
LibVirt : simple API for virtualization
Libvirt is a C toolkit to interact with the virtualization capabilities
of recent versions of Linux (and other OSes). It is free software
available under the GNU Lesser General Public License. Virtualization of
the Linux Operating System means the ability to run multiple instances of
Operating Systems concurrently on a single hardware system where the basic
resources are driven by a Linux instance. The library aim at providing
long term stable C API initially for the Xen paravirtualization but
should be able to integrate other virtualization mechanisms if needed.
Daniel Veillard <veillard@redhat.com>