Libvirt provides a portable, long term stable C API for managing the virtualization technologies provided by many operating systems. It includes support for QEMU, KVM, Xen, LXC, bhyve, Virtuozzo, VMware vCenter and ESX, VMware Desktop, Hyper-V, VirtualBox and the POWER Hypervisor.
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Daniel P. Berrange f234dc9366 Add support for re-exec() of virtlockd upon SIGUSR1
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>
2012-12-13 15:26:57 +00:00
.gnulib@d245e6ddd6 maint: update to latest gnulib 2012-10-22 20:25:44 -06:00
build-aux Document bracket whitespace rules & add syntax-check rule 2012-11-02 14:00:32 +00:00
daemon Inhibit daemon shutdown during driver initialization 2012-12-06 20:27:09 +01:00
docs docs: Document offline migration 2012-12-11 20:46:31 +01:00
examples examples: Fix balloon event callback 2012-12-11 13:25:50 +01:00
gnulib build: fix fresh checkout on RHEL5 2012-04-19 17:11:43 -06:00
include Add support for offline migration 2012-12-10 21:52:15 +01:00
m4 build: improve FORTIFY_SOURCE usage 2012-10-23 14:00:32 -06:00
po Implement dispatch functions for lock protocol in virtlockd 2012-12-13 15:26:57 +00:00
python Fix the indention 2012-12-04 23:41:35 +08:00
src Add support for re-exec() of virtlockd upon SIGUSR1 2012-12-13 15:26:57 +00:00
tests network: match xml warning message 2012-12-12 15:12:58 -07:00
tools tools: Only install guests init script if --with-init=script=redhat 2012-12-11 19:54:37 -05:00
.dir-locals.el build: avoid tabs that failed syntax-check 2012-09-06 09:43:46 -06:00
.gitignore Implement dispatch functions for lock protocol in virtlockd 2012-12-13 15:26:57 +00:00
.gitmodules make .gnulib a submodule 2009-07-08 16:17:51 +02:00
.mailmap Autogenerate AUTHORS 2012-10-19 12:44:56 -04:00
AUTHORS.in Doug Goldstein gained commit capability 2012-11-15 09:34:01 +08:00
autobuild.sh Switch automated builds to use Mingw64 toolchain instead of Mingw32 2012-06-25 10:41:10 +01:00
autogen.sh build: fix incremental autogen.sh when no AUTHORS is present 2012-12-03 14:59:09 -07:00
bootstrap maint: regenerate bootstrap 2012-07-27 09:34:04 -06:00
bootstrap.conf build: prefer mkostemp for multi-thread safety 2012-10-31 10:06:10 -06:00
cfg.mk Define a wire protocol for talking to the virtlockd daemon 2012-12-13 15:26:57 +00:00
ChangeLog-old virterror.c: Fix several spelling mistakes 2012-02-03 11:32:51 -07:00
configure.ac Qemu FreeBSD: fix compilation 2012-12-12 11:59:53 -07:00
COPYING.LIB remove all trailing blank lines 2009-07-16 15:06:42 +02:00
HACKING Document bracket whitespace rules & add syntax-check rule 2012-11-02 14:00:32 +00:00
libvirt.pc.in build: silence warning from autoconf 2012-05-30 09:22:02 -06:00
libvirt.spec.in Add support for re-exec() of virtlockd upon SIGUSR1 2012-12-13 15:26:57 +00:00
Makefile.am maint: mention when HACKING is rebuilt during make 2012-12-11 13:35:33 -07:00
Makefile.nonreentrant Ban use of all inet_* functions 2010-10-22 11:59:23 +01:00
mingw-libvirt.spec.in parallels: add driver skeleton 2012-08-01 11:44:26 +08:00
README Correct typos in the documentation (Atsushi SAKAI) 2008-01-24 10:15:13 +00:00
README-hacking maint: relax git minimum version 2010-02-24 14:29:27 -05:00
run.in syntax-check: fix run.in 2012-09-18 13:59:53 +02:00
TODO Update todo list file to point at bugzilla/website 2010-10-13 16:45:26 +01:00

         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>