[libvirt] [PATCH v13] support offline migration
li guang
lig.fnst at cn.fujitsu.com
Fri Nov 9 02:57:23 UTC 2012
在 2012-11-09五的 08:44 +0800，li guang写道：
> > diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
> > index 978af57..6c2bf98 100644
> > --- a/src/qemu/qemu_driver.c
> > +++ b/src/qemu/qemu_driver.c
> > @@ -9796,7 +9796,7 @@ qemuDomainMigrateBegin3(virDomainPtr domain,
> > asyncJob = QEMU_ASYNC_JOB_NONE;
> > }
> >
> > - if (!virDomainObjIsActive(vm)) {
> > + if (!virDomainObjIsActive(vm) && !(flags & VIR_MIGRATE_OFFLINE))
> {
> > virReportError(VIR_ERR_OPERATION_INVALID,
> > "%s", _("domain is not running"));
> > goto endjob;
> > @@ -9805,9 +9805,9 @@ qemuDomainMigrateBegin3(virDomainPtr domain,
> > /* Check if there is any ejected media.
> > * We don't want to require them on the destination.
> > */
> > -
> > - if (qemuDomainCheckEjectableMedia(driver, vm, asyncJob) < 0)
> > - goto endjob;
> > + if (virDomainObjIsActive(vm))
> > + if (qemuDomainCheckEjectableMedia(driver, vm, asyncJob) < 0)
> > + goto endjob;
> >
> > if (!(xml = qemuMigrationBegin(driver, vm, xmlin, dname,
> > cookieout, cookieoutlen,
>
> What if you want to offline migrate a domain that is currently running?
> I think it's better to first move qemuDomainCheckEjectableMedia down to
> qemuMigrationBegin in a separate patch and then just use the code from
> v12 (without using the offline label).
sorry, I don't like to do offline migrate for a domain that's running.
>
> > diff --git a/src/qemu/qemu_migration.c b/src/qemu/qemu_migration.c
> > index 5f8a9c5..66fbc02 100644
> > --- a/src/qemu/qemu_migration.c
> > +++ b/src/qemu/qemu_migration.c
> > @@ -72,6 +72,7 @@ enum qemuMigrationCookieFlags {
> > QEMU_MIGRATION_COOKIE_FLAG_LOCKSTATE,
> > QEMU_MIGRATION_COOKIE_FLAG_PERSISTENT,
> > QEMU_MIGRATION_COOKIE_FLAG_NETWORK,
> > + QEMU_MIGRATION_COOKIE_FLAG_OFFLINE,
> >
> > QEMU_MIGRATION_COOKIE_FLAG_LAST
> > };
> > @@ -79,13 +80,14 @@ enum qemuMigrationCookieFlags {
> > VIR_ENUM_DECL(qemuMigrationCookieFlag);
> > VIR_ENUM_IMPL(qemuMigrationCookieFlag,
> > QEMU_MIGRATION_COOKIE_FLAG_LAST,
> > - "graphics", "lockstate", "persistent", "network");
> > + "graphics", "lockstate", "persistent", "network",
> "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_NETWORK = (1 <<
> QEMU_MIGRATION_COOKIE_FLAG_NETWORK),
> > + QEMU_MIGRATION_COOKIE_OFFLINE = (1 <<
> QEMU_MIGRATION_COOKIE_FLAG_OFFLINE),
> > };
> >
> > typedef struct _qemuMigrationCookieGraphics
> qemuMigrationCookieGraphics;
> > @@ -594,6 +596,9 @@ qemuMigrationCookieXMLFormat(struct qemud_driver
> *driver,
> > if ((mig->flags & QEMU_MIGRATION_COOKIE_NETWORK) && mig->network)
> > qemuMigrationCookieNetworkXMLFormat(buf, mig->network);
> >
> > + if (mig->flags & QEMU_MIGRATION_COOKIE_OFFLINE)
> > + virBufferAsprintf(buf, " <offline/>\n");
> > +
> > virBufferAddLit(buf, "</qemu-migration>\n");
> > return 0;
> > }
> > @@ -874,6 +879,11 @@
> qemuMigrationCookieXMLParse(qemuMigrationCookiePtr mig,
> > (!(mig->network = qemuMigrationCookieNetworkXMLParse(ctxt))))
> > goto error;
> >
> > + if ((flags & QEMU_MIGRATION_COOKIE_OFFLINE)) {
> > + if (virXPathBoolean("count(./offline) > 0", ctxt))
> > + mig->flags |= QEMU_MIGRATION_COOKIE_OFFLINE;
> > + }
> > +
> > return 0;
> >
> > error:
> > @@ -938,6 +948,10 @@ qemuMigrationBakeCookie(qemuMigrationCookiePtr
> mig,
> > return -1;
> > }
> >
> > + if (flags & QEMU_MIGRATION_COOKIE_OFFLINE) {
> > + mig->flags |= QEMU_MIGRATION_COOKIE_OFFLINE;
> > + }
> > +
> > if (!(*cookieout = qemuMigrationCookieXMLFormatStr(driver, mig)))
> > return -1;
> >
>
> Oh, I'm sorry for not noticing this earlier, but why exactly do we need
> this <offline/> element in migration cookie? It doesn't look like we need to
> store some additional data required for offline migration. I think just
> passing the VIR_MIGRATE_OFFLINE flag will be better. Not to mention that if an older
> libvirt gets a cookie with <offline/> element, it will just ignore it
> while passing a flag (which the code should already been doing anyway) should
> make it fail for unsupported flag.
without this how do you know you a offline migration at target side?
>
> > @@ -1443,6 +1457,24 @@ char *qemuMigrationBegin(struct qemud_driver
> *driver,
> > QEMU_MIGRATION_COOKIE_LOCKSTATE) < 0)
> > goto cleanup;
> >
> > + if (flags & VIR_MIGRATE_OFFLINE) {
> > + if (flags & (VIR_MIGRATE_NON_SHARED_DISK|
> > + VIR_MIGRATE_NON_SHARED_INC)) {
> > + virReportError(VIR_ERR_OPERATION_INVALID,
> > + "%s", _("offline migration cannot handle
> non-shared storage"));
> > + goto cleanup;
> > + }
> > + if (!(flags & VIR_MIGRATE_PERSIST_DEST)) {
> > + virReportError(VIR_ERR_OPERATION_INVALID,
> > + "%s", _("offline migration must be
> specified with the persistent flag set"));
> > + goto cleanup;
> > + }
> > + 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,
>
> Good, just wrap the two long lines and create a separate patch (which
> this one
> will depend on) to move qemuDomainCheckEjectableMedia here as well.
>
> > @@ -1607,6 +1639,15 @@ qemuMigrationPrepareAny(struct qemud_driver
> *driver,
> > goto endjob;
> > }
> >
> > + if (!(mig = qemuMigrationEatCookie(driver, vm, cookiein,
> cookieinlen,
> > +
> QEMU_MIGRATION_COOKIE_OFFLINE)))
> > + return ret;
>
> AS I wrote in my last review, this needs to call goto endjob rather than
> returning directly.
right, will fix.
>
> > +
> > + if (mig->flags & QEMU_MIGRATION_COOKIE_OFFLINE) {
> > + ret = 0;
> > + goto done;
> > + }
> > +
> > /* Start the QEMU daemon, with the same command-line arguments
> plus
> > * -incoming $migrateFrom
> > */
> ...
> > @@ -2150,6 +2192,9 @@ qemuMigrationRun(struct qemud_driver *driver,
> > return -1;
> > }
> >
> > + if (flags & VIR_MIGRATE_OFFLINE)
> > + return 0;
> > +
> > if (!(mig = qemuMigrationEatCookie(driver, vm, cookiein,
> cookieinlen,
> >
> QEMU_MIGRATION_COOKIE_GRAPHICS)))
> > goto cleanup;
>
> I still think we should not even get into qemuMigrationRun when doing
> offline migration.
No, it will get into here for I did not touch migrationPerform path,
initially I don't want to change any code at libvirt.c so I must keep
offline migration walk through whole path like normal, or there're maybe
lots of fixes, any will break up the migration path.
>
> > @@ -2665,7 +2710,12 @@ static int doPeer2PeerMigrate3(struct
> qemud_driver *driver,
> > uri, &uri_out, flags, dname, resource, dom_xml);
> > qemuDomainObjExitRemoteWithDriver(driver, vm);
> > }
> > +
> > VIR_FREE(dom_xml);
> > +
> > + if (flags & VIR_MIGRATE_OFFLINE)
> > + goto cleanup;
> > +
> > if (ret == -1)
> > goto cleanup;
> >
>
> Quoting from my previous review:
>
> This will skip not only Perform but also Finish phase in
> peer-to-peer migration. You want to jump to finish label and do that *after* the
> check for ret == 1.
OK, I will jump to finish label.
>
> > @@ -2771,7 +2821,7 @@ finish:
> > vm->def->name);
> >
> > cleanup:
> > - if (ddomain) {
> > + if (ddomain || (flags & VIR_MIGRATE_OFFLINE)) {
> > virObjectUnref(ddomain);
> > ret = 0;
> > } else {
>
> I think this should not be changed at all.
>
or you'll get an error for ret = -1.
> ...
> > diff --git a/tools/virsh-domain.c b/tools/virsh-domain.c
> > index 393b67b..54ba63a 100644
> > --- a/tools/virsh-domain.c
> > +++ b/tools/virsh-domain.c
> > @@ -6644,6 +6644,7 @@ static const vshCmdInfo info_migrate[] = {
> >
> > static const vshCmdOptDef opts_migrate[] = {
> > {"live", VSH_OT_BOOL, 0, N_("live migration")},
> > + {"offline", VSH_OT_BOOL, 0, N_("offline (domain's inactive)
> migration")},
> > {"p2p", VSH_OT_BOOL, 0, N_("peer-2-peer migration")},
> > {"direct", VSH_OT_BOOL, 0, N_("direct migration")},
> > {"tunneled", VSH_OT_ALIAS, 0, "tunnelled"},
> > @@ -6729,6 +6730,15 @@ doMigrate(void *opaque)
> > if (vshCommandOptBool(cmd, "unsafe"))
> > flags |= VIR_MIGRATE_UNSAFE;
> >
> > + if (vshCommandOptBool(cmd, "offline")) {
> > + flags |= VIR_MIGRATE_OFFLINE;
> > + }
> > +
> > + if (virDomainIsActive(dom) && (flags & VIR_MIGRATE_OFFLINE)) {
> > + vshError(ctl, "%s", _("domain is active, offline migration
> for inactive domain only"));
> > + goto out;
> > + }
> > +
>
> Another thing I didn't notice last time :-( Is there any reason why
> offline migrating a running domain should be forbidden? But even if there was a
> reason, this check doesn't belong to virsh.
like I said before, running domain is active, so it's not offline,
if you want offline process to do job for an active domain, I think
an explicit flag is required.
> And --ofline flag for virsh migrate should also be documented in virsh
> man page.
>
got it, I'll add this to virsh man page.
> Jirka
>
>
--
li guang lig.fnst at cn.fujitsu.com
linux kernel team at FNST, china
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