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Re: [libvirt] [PATCH V5] support offline migration



On Thu, Sep 06, 2012 at 01:24:45PM +0800, liguang wrote:
> original migration did not aware of offline case,
> so, add code to support offline migration quietly
> (did not disturb original migration) by pass
> VIR_MIGRATE_OFFLINE flag to migration APIs, and
> migration process will not puzzeled by domain
> offline and exit unexpectly.

IIUC, if you pass VIR_MIGRATE_OFFLINE and the guest is not running,
this API is more or less a no-op.  Only if you add in the
VIR_MIGRATE_PERSISTENT or VIR_MIGRATE_UNDEFINE_SOURCE flag will
anything actually be done.

> these changes did not take care of disk images the
> domain required, for disk images could be transfered
> by other APIs as suggested.
> so, the migration result is just make domain
> definition alive at target side.

But only if VIR_MIGRATE_PERSISTENT is set, right ?

> Signed-off-by: liguang <lig fnst cn fujitsu com>
> ---
>  include/libvirt/libvirt.h.in |    1 +
>  src/qemu/qemu_driver.c       |    8 +++++
>  src/qemu/qemu_migration.c    |   63 ++++++++++++++++++++++++++++++++++++-----
>  src/qemu/qemu_migration.h    |    3 +-
>  tools/virsh-domain.c         |    4 ++
>  5 files changed, 70 insertions(+), 9 deletions(-)
> 
> diff --git a/include/libvirt/libvirt.h.in b/include/libvirt/libvirt.h.in
> index cfe5047..77df2ab 100644
> --- a/include/libvirt/libvirt.h.in
> +++ b/include/libvirt/libvirt.h.in
> @@ -995,6 +995,7 @@ typedef enum {
>                                                 * whole migration process; this will be used automatically
>                                                 * when supported */
>      VIR_MIGRATE_UNSAFE            = (1 << 9), /* force migration even if it is considered unsafe */
> +    VIR_MIGRATE_OFFLINE           = (1 << 10), /* offline migrate */
>  } virDomainMigrateFlags;
>  
>  /* Domain migration. */
> diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
> index b12d9bc..0ed7053 100644
> --- a/src/qemu/qemu_driver.c
> +++ b/src/qemu/qemu_driver.c
> @@ -9641,6 +9641,8 @@ qemuDomainMigrateBegin3(virDomainPtr domain,
>      }
>  
>      if (!virDomainObjIsActive(vm)) {
> +        if (flags |= VIR_MIGRATE_OFFLINE)
> +            goto offline;

This doesn't make sense - it should be '&' not '|='.

>          virReportError(VIR_ERR_OPERATION_INVALID,
>                         "%s", _("domain is not running"));
>          goto endjob;
> @@ -9653,6 +9655,7 @@ qemuDomainMigrateBegin3(virDomainPtr domain,
>      if (qemuDomainCheckEjectableMedia(driver, vm, asyncJob) < 0)
>          goto endjob;
>  
> +offline:
>      if (!(xml = qemuMigrationBegin(driver, vm, xmlin, dname,
>                                     cookieout, cookieoutlen,
>                                     flags)))
> @@ -9888,6 +9891,11 @@ qemuDomainMigrateConfirm3(virDomainPtr domain,
>          goto cleanup;
>      }
>  
> +    if (flags & VIR_MIGRATE_OFFLINE) {
> +        ret = 0;
> +        goto cleanup;
> +    }
> +
>      if (!qemuMigrationJobIsActive(vm, QEMU_ASYNC_JOB_MIGRATION_OUT))
>          goto cleanup;
>  
> diff --git a/src/qemu/qemu_migration.c b/src/qemu/qemu_migration.c
> index 1b21ef6..cf140d4 100644
> --- a/src/qemu/qemu_migration.c
> +++ b/src/qemu/qemu_migration.c
> @@ -70,6 +70,7 @@ enum qemuMigrationCookieFlags {
>      QEMU_MIGRATION_COOKIE_FLAG_GRAPHICS,
>      QEMU_MIGRATION_COOKIE_FLAG_LOCKSTATE,
>      QEMU_MIGRATION_COOKIE_FLAG_PERSISTENT,
> +    QEMU_MIGRATION_COOKIE_FLAG_OFFLINE,
>  
>      QEMU_MIGRATION_COOKIE_FLAG_LAST
>  };
> @@ -77,12 +78,13 @@ enum qemuMigrationCookieFlags {
>  VIR_ENUM_DECL(qemuMigrationCookieFlag);
>  VIR_ENUM_IMPL(qemuMigrationCookieFlag,
>                QEMU_MIGRATION_COOKIE_FLAG_LAST,
> -              "graphics", "lockstate", "persistent");
> +              "graphics", "lockstate", "persistent", "offline");
>  
>  enum qemuMigrationCookieFeatures {
>      QEMU_MIGRATION_COOKIE_GRAPHICS  = (1 << QEMU_MIGRATION_COOKIE_FLAG_GRAPHICS),
>      QEMU_MIGRATION_COOKIE_LOCKSTATE = (1 << QEMU_MIGRATION_COOKIE_FLAG_LOCKSTATE),
>      QEMU_MIGRATION_COOKIE_PERSISTENT = (1 << QEMU_MIGRATION_COOKIE_FLAG_PERSISTENT),
> +    QEMU_MIGRATION_COOKIE_OFFLINE = (1 << QEMU_MIGRATION_COOKIE_FLAG_OFFLINE),
>  };
>  
>  typedef struct _qemuMigrationCookieGraphics qemuMigrationCookieGraphics;
> @@ -439,6 +441,12 @@ qemuMigrationCookieXMLFormat(struct qemud_driver *driver,
>          virBufferAdjustIndent(buf, -2);
>      }
>  
> +    if (mig->flags & QEMU_MIGRATION_COOKIE_OFFLINE) {
> +        virBufferAsprintf(buf, "  <offline mig_ol='%d'>\n",
> +                          1);
> +        virBufferAddLit(buf, "  </offline>\n");
> +    }

The 'mig_ol' attribute appears to be entirely pointless.

> +
>      virBufferAddLit(buf, "</qemu-migration>\n");
>      return 0;
>  }
> @@ -662,6 +670,18 @@ qemuMigrationCookieXMLParse(qemuMigrationCookiePtr mig,
>          VIR_FREE(nodes);
>      }
>  
> +    if ((flags & QEMU_MIGRATION_COOKIE_OFFLINE) &&
> +        virXPathBoolean("count(./offline) > 0", ctxt)) {
> +        int offline = 0;
> +        if (virXPathInt("string(./offline/@mig_ol)", ctxt, &offline) < 0) {
> +            virReportError(VIR_ERR_INTERNAL_ERROR,
> +                           "%s", _("missing mig_ol attribute in migration data"));
> +            goto error;
> +        }

This just re-inforces it. The existance of <offline/> is enough to show
that this was offline.

> +        if (offline != 1)
> +            mig->flags &= ~QEMU_MIGRATION_COOKIE_OFFLINE;
> +    }
> +
>      return 0;
>  
>  error:
> @@ -721,6 +741,10 @@ qemuMigrationBakeCookie(qemuMigrationCookiePtr mig,
>          qemuMigrationCookieAddPersistent(mig, dom) < 0)
>          return -1;
>  
> +    if (flags & QEMU_MIGRATION_COOKIE_OFFLINE) {
> +        mig->flags |= QEMU_MIGRATION_COOKIE_OFFLINE;
> +    }
> +
>      if (!(*cookieout = qemuMigrationCookieXMLFormatStr(driver, mig)))
>          return -1;
>  
> @@ -1151,6 +1175,13 @@ char *qemuMigrationBegin(struct qemud_driver *driver,
>                                  QEMU_MIGRATION_COOKIE_LOCKSTATE) < 0)
>          goto cleanup;
>  
> +    if (flags & VIR_MIGRATE_OFFLINE) {
> +        if (qemuMigrationBakeCookie(mig, driver, vm,
> +                                    cookieout, cookieoutlen,
> +                                    QEMU_MIGRATION_COOKIE_OFFLINE) < 0)
> +            goto cleanup;
> +    }
> +
>      if (xmlin) {
>          if (!(def = virDomainDefParseString(driver->caps, xmlin,
>                                              QEMU_EXPECTED_VIRT_TYPES,
> @@ -1314,6 +1345,15 @@ qemuMigrationPrepareAny(struct qemud_driver *driver,
>          goto endjob;
>      }
>  
> +    if (!(mig = qemuMigrationEatCookie(driver, vm, cookiein, cookieinlen,
> +                                       QEMU_MIGRATION_COOKIE_OFFLINE)))
> +        return ret;
> +
> +    if (mig->flags & QEMU_MIGRATION_COOKIE_OFFLINE) {
> +        ret = 0;
> +        goto cleanup;
> +    }
> +
>      /* Start the QEMU daemon, with the same command-line arguments plus
>       * -incoming $migrateFrom
>       */
> @@ -1856,7 +1896,8 @@ qemuMigrationRun(struct qemud_driver *driver,
>                         virLockManagerPluginGetName(driver->lockManager));
>          return -1;
>      }
> -
> +    if (flags & VIR_MIGRATE_OFFLINE)
> +        return 0;
>      if (!(mig = qemuMigrationEatCookie(driver, vm, cookiein, cookieinlen,
>                                         QEMU_MIGRATION_COOKIE_GRAPHICS)))
>          goto cleanup;
> @@ -2372,6 +2413,8 @@ static int doPeer2PeerMigrate3(struct qemud_driver *driver,
>          qemuDomainObjExitRemoteWithDriver(driver, vm);
>      }
>      VIR_FREE(dom_xml);
> +    if (flags & VIR_MIGRATE_OFFLINE)
> +        goto cleanup;
>      if (ret == -1)
>          goto cleanup;
>  
> @@ -2477,7 +2520,7 @@ finish:
>                   vm->def->name);
>  
>   cleanup:
> -    if (ddomain) {
> +    if (ddomain || (flags & VIR_MIGRATE_OFFLINE)) {
>          virObjectUnref(ddomain);
>          ret = 0;
>      } else {
> @@ -2554,10 +2597,9 @@ static int doPeer2PeerMigrate(struct qemud_driver *driver,
>      }
>  
>      /* domain may have been stopped while we were talking to remote daemon */
> -    if (!virDomainObjIsActive(vm)) {
> +    if (!virDomainObjIsActive(vm) && !(flags & VIR_MIGRATE_OFFLINE)) {
>          virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
>                         _("guest unexpectedly quit"));
> -        goto cleanup;
>      }

Huh, why are you removing this goto ?


Daniel
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