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To facilitate use of the locking plugins from hypervisor drivers, introduce a higher level API for locking virDomainObjPtr instances. In includes APIs targetted to VM startup, and hotplug/unplug * src/Makefile.am: Add domain lock API * src/locking/domain_lock.c, src/locking/domain_lock.h: High level API for domain locking
166 lines
4.5 KiB
Plaintext
166 lines
4.5 KiB
Plaintext
Using the Lock Manager APIs
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===========================
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This file describes how to use the lock manager APIs.
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All the guest lifecycle sequences here have higher
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level wrappers provided by the 'domain_lock.h' API,
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which simplify thue usage
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At libvirtd startup:
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plugin = virLockManagerPluginLoad("sync-manager");
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At libvirtd shtudown:
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virLockManagerPluginUnload(plugin)
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At guest startup:
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manager = virLockManagerNew(plugin,
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VIR_LOCK_MANAGER_OBJECT_DOMAIN,
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0);
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virLockManagerSetParameter(manager, "id", id);
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virLockManagerSetParameter(manager, "uuid", uuid);
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virLockManagerSetParameter(manager, "name", name);
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foreach disk
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virLockManagerRegisterResource(manager,
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VIR_LOCK_MANAGER_RESOURCE_TYPE_DISK,
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disk.path,
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..flags...);
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if (!virLockManagerAcquireObject(manager))
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abort..
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run QEMU
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At guest shutdown:
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...send QEMU 'quit' monitor command, and/or kill(qemupid)...
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if (!virLockManagerShutdown(manager))
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kill(supervisorpid); /* XXX or leave it running ??? */
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virLockManagerFree(manager);
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At libvirtd restart with running guests:
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foreach still running guest
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manager = virLockManagerNew(driver,
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VIR_LOCK_MANAGER_START_DOMAIN,
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VIR_LOCK_MANAGER_NEW_ATTACH);
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virLockManagerSetParameter(manager, "id", id);
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virLockManagerSetParameter(manager, "uuid", uuid);
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virLockManagerSetParameter(manager, "name", name);
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if (!virLockManagerGetChild(manager, &qemupid))
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kill(supervisorpid); /* XXX or leave it running ??? */
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With disk hotplug:
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if (virLockManagerAcquireResource(manager,
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VIR_LOCK_MANAGER_RESOURCE_TYPE_DISK,
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disk.path
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..flags..))
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...abort hotplug attempt ...
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...hotplug the device...
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With disk unhotplug:
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...hotunplug the device...
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if (virLockManagerReleaseResource(manager,
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VIR_LOCK_MANAGER_RESOURCE_TYPE_DISK,
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disk.path
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..flags..))
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...log warning ...
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During migration:
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1. On source host
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if (!virLockManagerPrepareMigrate(manager, hosturi))
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..don't start migration..
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2. On dest host
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manager = virLockManagerNew(driver,
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VIR_LOCK_MANAGER_START_DOMAIN,
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VIR_LOCK_MANAGER_NEW_MIGRATE);
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virLockManagerSetParameter(manager, "id", id);
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virLockManagerSetParameter(manager, "uuid", uuid);
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virLockManagerSetParameter(manager, "name", name);
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foreach disk
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virLockManagerRegisterResource(manager,
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VIR_LOCK_MANAGER_RESOURCE_TYPE_DISK,
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disk.path,
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..flags...);
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char **supervisorargv;
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int supervisorargc;
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supervisor = virLockManagerGetSupervisorPath(manager);
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virLockManagerGetSupervisorArgs(&argv, &argc);
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cmd = qemuBuildCommandLine(supervisor, supervisorargv, supervisorargv);
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supervisorpid = virCommandExec(cmd);
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if (!virLockManagerGetChild(manager, &qemupid))
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kill(supervisorpid); /* XXX or leave it running ??? */
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3. Initiate migration in QEMU on source and wait for completion
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4a. On failure
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4a1 On target
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virLockManagerCompleteMigrateIn(manager,
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VIR_LOCK_MANAGER_MIGRATE_CANCEL);
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virLockManagerShutdown(manager);
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virLockManagerFree(manager);
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4a2 On source
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virLockManagerCompleteMigrateIn(manager,
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VIR_LOCK_MANAGER_MIGRATE_CANCEL);
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4b. On succcess
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4b1 On target
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virLockManagerCompleteMigrateIn(manager, 0);
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42 On source
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virLockManagerCompleteMigrateIn(manager, 0);
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virLockManagerShutdown(manager);
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virLockManagerFree(manager);
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Notes:
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- If a lock manager impl does just VM level leases, it can
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ignore all the resource paths at startup.
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- If a lock manager impl does not support migrate
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it can return an error from all migrate calls
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- If a lock manger impl does not support hotplug
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it can return an error from all resource acquire/release calls
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