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Re: [libvirt] [PATCH] qemu: keep pre-migration domain state after failed migration



On Thu, Feb 06, 2014 at 17:33:14 +0100, Martin Kletzander wrote:
> Couple of codepaths shared the same code which can be moved out to a
> function and on one of such places, qemuMigrationConfirmPhase(), the
> domain was resumed even if it wasn't running before the migration
> started.
> 
> Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1057407
> 
> Signed-off-by: Martin Kletzander <mkletzan redhat com>
> ---
>  src/qemu/qemu_domain.h    |   3 +-
>  src/qemu/qemu_migration.c | 117 +++++++++++++++++++++++++---------------------
>  2 files changed, 66 insertions(+), 54 deletions(-)
> 
> diff --git a/src/qemu/qemu_domain.h b/src/qemu/qemu_domain.h
> index 6a92351..84624f9 100644
> --- a/src/qemu/qemu_domain.h
> +++ b/src/qemu/qemu_domain.h
> @@ -1,7 +1,7 @@
>  /*
>   * qemu_domain.h: QEMU domain private state
>   *
> - * Copyright (C) 2006-2013 Red Hat, Inc.
> + * Copyright (C) 2006-2014 Red Hat, Inc.
>   * Copyright (C) 2006 Daniel P. Berrange
>   *
>   * This library is free software; you can redistribute it and/or
> @@ -161,6 +161,7 @@ struct _qemuDomainObjPrivate {
>      char *origname;
>      int nbdPort; /* Port used for migration with NBD */
>      unsigned short migrationPort;
> +    int preMigrationState;
> 
>      virChrdevsPtr devs;
> 
> diff --git a/src/qemu/qemu_migration.c b/src/qemu/qemu_migration.c
> index 407fb70..1a29efa 100644
> --- a/src/qemu/qemu_migration.c
> +++ b/src/qemu/qemu_migration.c
> @@ -1075,6 +1075,53 @@ error:
>      return NULL;
>  }
> 
> +static void
> +qemuDomainObjStorePreMigrationState(virDomainObjPtr vm)
> +{
> +    qemuDomainObjPrivatePtr priv = vm->privateData;
> +    priv->preMigrationState = virDomainObjGetState(vm, NULL);
> +
> +    VIR_DEBUG("Storing pre-migration state=%d domain=%p",
> +              priv->preMigrationState, vm);
> +}

We are in qemu_migration.c file so this function and the one below
should use qemuMigration prefix.

> +
> +/* Returns true if the domain was resumed, false otherwise */
> +static bool
> +qemuDomainObjRestorePreMigrationState(virConnectPtr conn, virDomainObjPtr vm)
> +{
> +    virQEMUDriverPtr driver = conn->privateData;
> +    qemuDomainObjPrivatePtr priv = vm->privateData;
> +    int state = virDomainObjGetState(vm, NULL);
> +    bool ret = false;
> +
> +    VIR_DEBUG("driver=%p, vm=%p, pre-mig-state=%d, state=%d",
> +              driver, vm, priv->preMigrationState, state);
> +
> +    if (state == VIR_DOMAIN_PAUSED &&
> +        priv->preMigrationState == VIR_DOMAIN_RUNNING) {
> +        /* This is basically the only restore possibility that's safe
> +         * and we should attemt to do */
> +
> +        VIR_DEBUG("Restoring pre-migration state due to migration error");
> +
> +        /* we got here through some sort of failure; start the domain again */
> +        if (qemuProcessStartCPUs(driver, vm, conn,
> +                                 VIR_DOMAIN_RUNNING_MIGRATION_CANCELED,
> +                                 QEMU_ASYNC_JOB_MIGRATION_OUT) < 0) {
> +            /* Hm, we already know we are in error here.  We don't want to
> +             * overwrite the previous error, though, so we just throw something
> +             * to the logs and hope for the best */
> +            VIR_ERROR(_("Failed to resume guest %s after failure"), vm->def->name);
> +            goto cleanup;
> +        }
> +        ret = true;
> +    }
> +
> + cleanup:
> +    priv->preMigrationState = VIR_DOMAIN_NOSTATE;
> +    return ret;
> +}
> +
>  /**
>   * qemuMigrationStartNBDServer:
>   * @driver: qemu driver
> @@ -1952,8 +1999,8 @@ cleanup:
> 
> 
>  /* The caller is supposed to lock the vm and start a migration job. */
> -static char
> -*qemuMigrationBeginPhase(virQEMUDriverPtr driver,
> +static char *
> +qemuMigrationBeginPhase(virQEMUDriverPtr driver,

Heh, it took me a while to see what you did :-) However, the following
lines are not indented correctly now...

>                           virDomainObjPtr vm,
>                           const char *xmlin,
>                           const char *dname,
> @@ -2075,6 +2122,8 @@ qemuMigrationBegin(virConnectPtr conn,
>          asyncJob = QEMU_ASYNC_JOB_NONE;
>      }
> 
> +    qemuDomainObjStorePreMigrationState(vm);
> +
>      if (!virDomainObjIsActive(vm) && !(flags & VIR_MIGRATE_OFFLINE)) {
>          virReportError(VIR_ERR_OPERATION_INVALID,
>                         "%s", _("domain is not running"));
> @@ -2744,22 +2793,12 @@ qemuMigrationConfirmPhase(virQEMUDriverPtr driver,
>          /* cancel any outstanding NBD jobs */
>          qemuMigrationCancelDriveMirror(mig, driver, vm);
> 
> -        /* run 'cont' on the destination, which allows migration on qemu
> -         * >= 0.10.6 to work properly.  This isn't strictly necessary on
> -         * older qemu's, but it also doesn't hurt anything there
> -         */
> -        if (qemuProcessStartCPUs(driver, vm, conn,
> -                                 VIR_DOMAIN_RUNNING_MIGRATED,
> -                                 QEMU_ASYNC_JOB_MIGRATION_OUT) < 0) {
> -            if (virGetLastError() == NULL)
> -                virReportError(VIR_ERR_INTERNAL_ERROR,
> -                               "%s", _("resume operation failed"));
> -            goto cleanup;
> +        if (qemuDomainObjRestorePreMigrationState(conn, vm)) {
> +            event = virDomainEventLifecycleNewFromObj(vm,
> +                                                      VIR_DOMAIN_EVENT_RESUMED,
> +                                                      VIR_DOMAIN_EVENT_RESUMED_MIGRATED);
>          }
> 
> -        event = virDomainEventLifecycleNewFromObj(vm,
> -                                         VIR_DOMAIN_EVENT_RESUMED,
> -                                         VIR_DOMAIN_EVENT_RESUMED_MIGRATED);
>          if (virDomainSaveStatus(driver->xmlopt, cfg->stateDir, vm) < 0) {
>              VIR_WARN("Failed to save status on vm %s", vm->def->name);
>              goto cleanup;
> @@ -4065,7 +4104,6 @@ qemuMigrationPerformJob(virQEMUDriverPtr driver,
>  {
>      virObjectEventPtr event = NULL;
>      int ret = -1;
> -    int resume = 0;
>      virErrorPtr orig_err = NULL;
>      virQEMUDriverConfigPtr cfg = virQEMUDriverGetConfig(driver);
>      bool abort_on_error = !!(flags & VIR_MIGRATE_ABORT_ON_ERROR);
> @@ -4085,7 +4123,7 @@ qemuMigrationPerformJob(virQEMUDriverPtr driver,
>      if (!(flags & VIR_MIGRATE_UNSAFE) && !qemuMigrationIsSafe(vm->def))
>          goto endjob;
> 
> -    resume = virDomainObjGetState(vm, NULL) == VIR_DOMAIN_RUNNING;
> +    qemuDomainObjStorePreMigrationState(vm);
> 
>      if ((flags & (VIR_MIGRATE_TUNNELLED | VIR_MIGRATE_PEER2PEER))) {
>          ret = doPeer2PeerMigrate(driver, conn, vm, xmlin,
> @@ -4112,25 +4150,13 @@ qemuMigrationPerformJob(virQEMUDriverPtr driver,
>                                           VIR_DOMAIN_EVENT_STOPPED,
>                                           VIR_DOMAIN_EVENT_STOPPED_MIGRATED);
>      }
> -    resume = 0;
> 
>  endjob:
>      if (ret < 0)
>          orig_err = virSaveLastError();
> 
> -    if (resume && virDomainObjGetState(vm, NULL) == VIR_DOMAIN_PAUSED) {
> -        /* we got here through some sort of failure; start the domain again */
> -        if (qemuProcessStartCPUs(driver, vm, conn,
> -                                 VIR_DOMAIN_RUNNING_MIGRATION_CANCELED,
> -                                 QEMU_ASYNC_JOB_MIGRATION_OUT) < 0) {
> -            /* Hm, we already know we are in error here.  We don't want to
> -             * overwrite the previous error, though, so we just throw something
> -             * to the logs and hope for the best
> -             */
> -            VIR_ERROR(_("Failed to resume guest %s after failure"),
> -                      vm->def->name);
> -        }
> -
> +    if (!v3proto &&
> +        qemuDomainObjRestorePreMigrationState(conn, vm)) {

You could also call qemuDomainObjRestorePreMigrationState
unconditionally since you always reset preMigrationState which makes it
safe to call qemuDomainObjRestorePreMigrationState multiple times but it
does not really matter.

>          event = virDomainEventLifecycleNewFromObj(vm,
>                                           VIR_DOMAIN_EVENT_RESUMED,
>                                           VIR_DOMAIN_EVENT_RESUMED_MIGRATED);
> @@ -4179,7 +4205,6 @@ qemuMigrationPerformPhase(virQEMUDriverPtr driver,
>  {
>      virObjectEventPtr event = NULL;
>      int ret = -1;
> -    bool resume;
>      bool hasrefs;
> 
>      /* If we didn't start the job in the begin phase, start it now. */
> @@ -4194,32 +4219,18 @@ qemuMigrationPerformPhase(virQEMUDriverPtr driver,
>      virCloseCallbacksUnset(driver->closeCallbacks, vm,
>                             qemuMigrationCleanup);
> 
> -    resume = virDomainObjGetState(vm, NULL) == VIR_DOMAIN_RUNNING;
>      ret = doNativeMigrate(driver, vm, uri, cookiein, cookieinlen,
>                            cookieout, cookieoutlen,
>                            flags, resource, NULL, graphicsuri);
> 
> -    if (ret < 0 && resume &&
> -        virDomainObjGetState(vm, NULL) == VIR_DOMAIN_PAUSED) {
> -        /* we got here through some sort of failure; start the domain again */
> -        if (qemuProcessStartCPUs(driver, vm, conn,
> -                                 VIR_DOMAIN_RUNNING_MIGRATION_CANCELED,
> -                                 QEMU_ASYNC_JOB_MIGRATION_OUT) < 0) {
> -            /* Hm, we already know we are in error here.  We don't want to
> -             * overwrite the previous error, though, so we just throw something
> -             * to the logs and hope for the best
> -             */
> -            VIR_ERROR(_("Failed to resume guest %s after failure"),
> -                      vm->def->name);
> +    if (ret < 0) {
> +        if (qemuDomainObjRestorePreMigrationState(conn, vm)) {
> +            event = virDomainEventLifecycleNewFromObj(vm,
> +                                                      VIR_DOMAIN_EVENT_RESUMED,
> +                                                      VIR_DOMAIN_EVENT_RESUMED_MIGRATED);
>          }
> -
> -        event = virDomainEventLifecycleNewFromObj(vm,
> -                                         VIR_DOMAIN_EVENT_RESUMED,
> -                                         VIR_DOMAIN_EVENT_RESUMED_MIGRATED);
> -    }
> -
> -    if (ret < 0)
>          goto endjob;
> +    }
> 
>      qemuMigrationJobSetPhase(driver, vm, QEMU_MIGRATION_PHASE_PERFORM3_DONE);
> 

ACK with the nits addressed.

Jirka


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