[libvirt] [PATCH v4 7/9] qemu_migration: Introduce qemuMigrationDriveMirror

[Jiri Denemark]

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