On Thu, Feb 21, 2013 at 14:39:24 +0100, Michal Privoznik wrote:
> This function does the source part of NBD magic. It
> invokes drive-mirror on each non shared and RW disk with
> a source and wait till the mirroring process completes.
> When it does we can proceed with migration.
>
> Currently, an active waiting is done: every 500ms libvirt
> asks qemu if block-job is finished or not. However, once
> the job finishes, qemu doesn't report its progress so we
> can only assume if the job finished successfully or not.
> The better solution would be to listen to the event which
> is sent as soon as the job finishes. The event does
> contain the result of job.
...
> +static int
> +qemuMigrationDriveMirror(virQEMUDriverPtr driver,
> + virDomainObjPtr vm,
> + qemuMigrationCookiePtr mig,
> + const char *host,
> + unsigned long speed,
> + unsigned int *migrate_flags)
> +{
> + qemuDomainObjPrivatePtr priv = vm->privateData;
> + int ret = -1;
> + int mon_ret;
> + int port;
> + size_t i, lastGood = 0;
> + char *diskAlias = NULL;
> + char *nbd_dest = NULL;
> + unsigned int mirror_flags = VIR_DOMAIN_BLOCK_REBASE_REUSE_EXT;
> + virErrorPtr err = NULL;
> +
> + if (!(*migrate_flags & (QEMU_MONITOR_MIGRATE_NON_SHARED_DISK |
> + QEMU_MONITOR_MIGRATE_NON_SHARED_INC)))
> + return 0;
> +
> + if (!mig->nbd) {
> + /* Destination doesn't support NBD server.
> + * Fall back to previous implementation. */
> + VIR_DEBUG("Destination doesn't support NBD server "
> + "Falling back to previous implementation.");
> + return 0;
> + }
> +
> + /* steal NBD port and thus prevent its propagation back to destination */
> + port = mig->nbd->port;
> + mig->nbd->port = 0;
> +
> + if (*migrate_flags & QEMU_MONITOR_MIGRATE_NON_SHARED_INC)
> + mirror_flags |= VIR_DOMAIN_BLOCK_REBASE_SHALLOW;
> +
> + for (i = 0; i < vm->def->ndisks; i++) {
> + virDomainDiskDefPtr disk = vm->def->disks[i];
> + virDomainBlockJobInfo info;
> +
> + /* skip shared, RO and source-less disks */
> + if (disk->shared || disk->readonly || !disk->src)
> + continue;
> +
> + VIR_FREE(diskAlias);
> + VIR_FREE(nbd_dest);
> + if ((virAsprintf(&diskAlias, "%s%s",
> + QEMU_DRIVE_HOST_PREFIX, disk->info.alias) < 0) ||
> + (virAsprintf(&nbd_dest, "nbd:%s:%u:exportname=%s",
> + host, port, diskAlias) < 0)) {
port is signed => s/%u/%d/
ACK
Jirka
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