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Re: [libvirt] [PATCH 1/2] libvirt/qemu - support updating inactive domains (take 2)



On Thu, Feb 24, 2011 at 01:06:36PM +0900, KAMEZAWA Hiroyuki wrote:
> >From d6c65102224c493f67008b6521b0115d798f5a67 Mon Sep 17 00:00:00 2001
> From: KAMEZAWA Hiroyuki <kamezawa bluextal (none)>
> Date: Thu, 24 Feb 2011 12:14:25 +0900
> Subject: [PATCH 1/2] libvirt/qemu - support updating inactive domains.
> 
> Now, virsh attach-disk/detach-disk has --persistent option and
> it can update XML definition of inactive domains. But, it's only
> supported in Xen.
> 
> This patch adds support for attach-disk/detach-disk for qemu.
> 
> Changelog v1->v2:
>   - fixed TABs
>   - fixed PCI address assignment for VIRTIO driver.
> 
> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa hiroyu jp fujitsu com>
> ---
>  src/qemu/qemu_driver.c |  168 +++++++++++++++++++++++++++++++++++++++++++++---
>  1 files changed, 158 insertions(+), 10 deletions(-)
> 
> diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
> index 8b15a3e..e75478a 100644
> --- a/src/qemu/qemu_driver.c
> +++ b/src/qemu/qemu_driver.c
> @@ -4085,14 +4085,164 @@ cleanup:
>      return ret;
>  }
>  
> -static int qemudDomainAttachDeviceFlags(virDomainPtr dom,
> +static int qemuDomainFindDiskByName(virDomainDefPtr vmdef, const char *name)
> +{
> +    virDomainDiskDefPtr vdisk;
> +    int i;
> +
> +    for (i = 0; i < vmdef->ndisks; i++) {
> +        vdisk = vmdef->disks[i];
> +        if (!strcmp(vdisk->dst, name))

Maybe STREQ() is better here as other libvirt code uses STREQ() rather
than strcmp().

> +            return i;
> +    }
> +    return -1;
> +}
> +/*
> + * Attach a device given by XML, the change will be persistent
> + * and domain XML definition file is updated.
> + */
> +static int qemuDomainAttachDevicePersistent(virDomainDefPtr vmdef,
> +                                            virDomainDeviceDefPtr newdev)
> +{
> +    virDomainDiskDefPtr disk;
> +
> +    /* At first, check device confliction */
> +    switch(newdev->type) {
> +    case VIR_DOMAIN_DEVICE_DISK:
> +        disk = newdev->data.disk;
> +        if (qemuDomainFindDiskByName(vmdef, disk->dst) >= 0) {
> +            qemuReportError(VIR_ERR_INVALID_ARG,
> +                 _("target %s already exists."), disk->dst);
> +            return -1;
> +        }
> +
> +        if (virDomainDiskInsert(vmdef, disk)) {
> +            virReportOOMError();

I think it's better to report OOM error by virDomainDiskInsert() itself,
otherwise every caller has to call virReportOOMError() when fails.

> +            return -1;
> +        }
> +        if (disk->bus == VIR_DOMAIN_DISK_BUS_VIRTIO) {
> +            /*
> +             * Address/Drive information is NULL. If virtio, PCI address
> +             * shoule be fixed. Other devices as IDE, SCSI...will get ID
> +             * automatically
> +             */
> +            qemuDomainAssignPCIAddresses(vmdef);
> +
> +        }
> +        newdev->data.disk = NULL;
> +        break;
> +    default:
> +        qemuReportError(VIR_ERR_INVALID_ARG, "%s",
> +                        _("Sorry, the device is not suppored for now"));
> +        return -1;
> +    }
> +    
> +    return 0;
> +}
> +
> +static int qemuDomainDetachDevicePersistent(virDomainDefPtr vmdef,
> +                                       virDomainDeviceDefPtr device)
> +{
> +    int x;
> +    virDomainDiskDefPtr disk;
> +
> +    switch(device->type) {
> +    case VIR_DOMAIN_DEVICE_DISK:
> +        disk = device->data.disk;
> +        x = qemuDomainFindDiskByName(vmdef, disk->dst);
> +        if (x < 0) {
> +            qemuReportError(VIR_ERR_INVALID_ARG,
> +                 _("target %s doesn't exist."), disk->dst);
> +            return -1;
> +        }
> +        virDomainDiskRemove(vmdef, x);
> +        break;
> +    default:
> +        qemuReportError(VIR_ERR_INVALID_ARG, "%s",
> +                        _("Sorry, the device is not suppored for now"));
> +        return -1;
> +    }
> +    return 0;
> +}
> +
> +static int qemuDomainModifyDevicePersistent(virDomainPtr dom,
>                                          const char *xml,
> -                                        unsigned int flags) {
> -    if (flags & VIR_DOMAIN_DEVICE_MODIFY_CONFIG) {
> -        qemuReportError(VIR_ERR_OPERATION_INVALID,
> -                        "%s", _("cannot modify the persistent configuration of a domain"));
> +                                        unsigned int attach)
> +{
> +    struct qemud_driver *driver;
> +    virDomainDeviceDefPtr device;
> +    virDomainDefPtr vmdef;
> +    virDomainObjPtr vm;
> +    int ret = -1;
> +
> +    if (!dom || !dom->conn || !dom->name || !xml) {
> +        qemuReportError(VIR_ERR_INVALID_ARG,
> +                        _("internal error : %s"),  __FUNCTION__);
> +        return -1;
> +    }
> +
> +    if (dom->conn->flags & VIR_CONNECT_RO)
>          return -1;

No need to check the RO flag here: it should be and is done in
virDomainAttachDevice().

> +
> +    driver = dom->conn->privateData;
> +    qemuDriverLock(driver);
> +    vm = virDomainFindByUUID(&driver->domains, dom->uuid);
> +    if (!vm) {
> +        qemuReportError(VIR_ERR_NO_DOMAIN, _("cannot find domain '%s'"),
> +                        dom->name);
> +        goto unlock_out;
> +    }
> +
> +    if (qemuDomainObjBeginJobWithDriver(driver, vm) < 0) {
> +        /*
> +         * For now, just allow updating inactive domains. Further development
> +         * will allow updating both active domain and its config file at
> +         * the same time.
> +         */
> +        qemuReportError(VIR_ERR_INVALID_ARG,
> +                        _("cannot update alive domain : %s"),  __FUNCTION__);

I think we can silently fail here. Currently this function (qemuDomainModifyDevicePersistent)
is called only for modifying inactive domains.

> +        goto endjob;
> +    }
> +    vmdef = virDomainObjGetPersistentDef(driver->caps, vm);
> +
> +    if (!vmdef)
> +        goto endjob;
> +
> +    device = virDomainDeviceDefParse(driver->caps,
> +                 vmdef, xml, VIR_DOMAIN_XML_INACTIVE);
> +    if (!device)
> +        goto endjob;
> +
> +    if (attach) {
> +        ret = qemuDomainAttachDevicePersistent(vmdef, device);
> +        if (ret < 0)
> +            goto out;
> +    } else {
> +        ret = qemuDomainDetachDevicePersistent(vmdef, device);
> +        if (ret < 0)
> +            goto out;
>      }

This can be refined as:

if (attach)
    ret = qemuDomainAttachDevicePersistent(vmdef, device);
else
    ret = qemuDomainDetachDevicePersistent(vmdef, device);

if (ret < 0)
    goto out;

> +    ret = virDomainSaveConfig(driver->configDir, vmdef);
> +
> +out:
> +    virDomainDeviceDefFree(device);
> +endjob:
> +    if (qemuDomainObjEndJob(vm) == 0)
> +        vm = NULL;
> +    if (vm)
> +        virDomainObjUnlock(vm);
> +    /* Note: insert of newdev is done by copy */
> +unlock_out:
> +    qemuDriverUnlock(driver);
> +    return ret;
> +}
> +
> +static int qemudDomainAttachDeviceFlags(virDomainPtr dom,
> +                                        const char *xml,
> +                                        unsigned int flags) {
> +
> +    if (flags & VIR_DOMAIN_DEVICE_MODIFY_CONFIG)
> +        return qemuDomainModifyDevicePersistent(dom, xml, 1);
>  
>      return qemudDomainAttachDevice(dom, xml);
>  }
> @@ -4306,11 +4456,9 @@ cleanup:
>  static int qemudDomainDetachDeviceFlags(virDomainPtr dom,
>                                          const char *xml,
>                                          unsigned int flags) {
> -    if (flags & VIR_DOMAIN_DEVICE_MODIFY_CONFIG) {
> -        qemuReportError(VIR_ERR_OPERATION_INVALID,
> -                        "%s", _("cannot modify the persistent configuration of a domain"));
> -        return -1;
> -    }
> +
> +    if (flags & VIR_DOMAIN_DEVICE_MODIFY_CONFIG)
> +        return qemuDomainModifyDevicePersistent(dom, xml, 0);
>  
>      return qemudDomainDetachDevice(dom, xml);
>  }
> -- 
> 1.7.1

-- 
Thanks,
Hu Tao


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