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19ff0ddfbb
Inexplicably the sanlock code all got placed under the GPLv2-only, so libvirt's use of sanlock introduces a license incompatibility. The sanlock developers have now rearranged the code such that there is a 'sanlock_client.so' which is LGPLv2+ while their daemon remains GPLv2-only. To use the new client library we need to call the new sanlock_init and sanlock_align APIs instead of sanlock_direct_init and sanlock_direct_align. These APIs calls are now routed via the sanlock daemon, instead of doing direct I/O calls to disk. For all this we require sanlock >= 1.8 * configure.ac: Check for sanlock_client.so instead of sanlock.so and fix various comments * libvirt.spec.in: Mandate sanlock >= 1.8 * src/Makefile.am: Link to -lsanlock_client * src/locking/lock_driver_sanlock.c: Use sanlock_init and sanlock_align
Using the Lock Manager APIs
===========================
This file describes how to use the lock manager APIs.
All the guest lifecycle sequences here have higher
level wrappers provided by the 'domain_lock.h' API,
which simplify thue usage
At libvirtd startup:
plugin = virLockManagerPluginLoad("sync-manager");
At libvirtd shtudown:
virLockManagerPluginUnload(plugin)
At guest startup:
manager = virLockManagerNew(plugin,
VIR_LOCK_MANAGER_OBJECT_DOMAIN,
0);
virLockManagerSetParameter(manager, "id", id);
virLockManagerSetParameter(manager, "uuid", uuid);
virLockManagerSetParameter(manager, "name", name);
foreach disk
virLockManagerRegisterResource(manager,
VIR_LOCK_MANAGER_RESOURCE_TYPE_DISK,
disk.path,
..flags...);
if (!virLockManagerAcquireObject(manager))
abort..
run QEMU
At guest shutdown:
...send QEMU 'quit' monitor command, and/or kill(qemupid)...
if (!virLockManagerShutdown(manager))
kill(supervisorpid); /* XXX or leave it running ??? */
virLockManagerFree(manager);
At libvirtd restart with running guests:
foreach still running guest
manager = virLockManagerNew(driver,
VIR_LOCK_MANAGER_START_DOMAIN,
VIR_LOCK_MANAGER_NEW_ATTACH);
virLockManagerSetParameter(manager, "id", id);
virLockManagerSetParameter(manager, "uuid", uuid);
virLockManagerSetParameter(manager, "name", name);
if (!virLockManagerGetChild(manager, &qemupid))
kill(supervisorpid); /* XXX or leave it running ??? */
With disk hotplug:
if (virLockManagerAcquireResource(manager,
VIR_LOCK_MANAGER_RESOURCE_TYPE_DISK,
disk.path
..flags..))
...abort hotplug attempt ...
...hotplug the device...
With disk unhotplug:
...hotunplug the device...
if (virLockManagerReleaseResource(manager,
VIR_LOCK_MANAGER_RESOURCE_TYPE_DISK,
disk.path
..flags..))
...log warning ...
During migration:
1. On source host
if (!virLockManagerPrepareMigrate(manager, hosturi))
..don't start migration..
2. On dest host
manager = virLockManagerNew(driver,
VIR_LOCK_MANAGER_START_DOMAIN,
VIR_LOCK_MANAGER_NEW_MIGRATE);
virLockManagerSetParameter(manager, "id", id);
virLockManagerSetParameter(manager, "uuid", uuid);
virLockManagerSetParameter(manager, "name", name);
foreach disk
virLockManagerRegisterResource(manager,
VIR_LOCK_MANAGER_RESOURCE_TYPE_DISK,
disk.path,
..flags...);
char **supervisorargv;
int supervisorargc;
supervisor = virLockManagerGetSupervisorPath(manager);
virLockManagerGetSupervisorArgs(&argv, &argc);
cmd = qemuBuildCommandLine(supervisor, supervisorargv, supervisorargv);
supervisorpid = virCommandExec(cmd);
if (!virLockManagerGetChild(manager, &qemupid))
kill(supervisorpid); /* XXX or leave it running ??? */
3. Initiate migration in QEMU on source and wait for completion
4a. On failure
4a1 On target
virLockManagerCompleteMigrateIn(manager,
VIR_LOCK_MANAGER_MIGRATE_CANCEL);
virLockManagerShutdown(manager);
virLockManagerFree(manager);
4a2 On source
virLockManagerCompleteMigrateIn(manager,
VIR_LOCK_MANAGER_MIGRATE_CANCEL);
4b. On succcess
4b1 On target
virLockManagerCompleteMigrateIn(manager, 0);
42 On source
virLockManagerCompleteMigrateIn(manager, 0);
virLockManagerShutdown(manager);
virLockManagerFree(manager);
Notes:
- If a lock manager impl does just VM level leases, it can
ignore all the resource paths at startup.
- If a lock manager impl does not support migrate
it can return an error from all migrate calls
- If a lock manger impl does not support hotplug
it can return an error from all resource acquire/release calls