[libvirt] [PATCH 3/5] libvirt/qemu - support persistent modification of devices.

[Wen Congyang]

At 03/03/2011 09:11 AM, KAMEZAWA Hiroyuki Write:
>>From f7a997e3cd58cfac81e131afdd20c3691267831d Mon Sep 17 00:00:00 2001
> From: KAMEZAWA Hiroyuki <kamezawa.hiroyu at jp.fujitsu.com>
> Date: Thu, 3 Mar 2011 09:43:07 +0900
> Subject: [PATCH 3/5] libivrt/qemu - support persistent modification of devices.
> 
> Now, virsh attach-***/detach-*** has --persistent option and
> it can update XML definition of inactive domains.
> Now, disk and nic are supported in Xen, but none in qemu.
> 
> This patch adds a function for permanent modification for qemu.
> Following patches will add disk/network suport.
> 
> TODO:
>   - finally, need to do hotplug + XML modification for active domain.
> 
> Changelog v3->v4
>   - fixed trailing white spaces.
>   - splitted into 2 part and this patch only contains wrappers.
> Changelog v2->v3:
>   - clean ups.
>   - handle all VIR_DOMAIN_DEVICE_MODIFY_XXX flags.
> ---
>  src/qemu/qemu_driver.c |  143 ++++++++++++++++++++++++++++++++++++++++++++----
>  1 files changed, 131 insertions(+), 12 deletions(-)
> 
> diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
> index c9095bb..3248cdc 100644
> --- a/src/qemu/qemu_driver.c
> +++ b/src/qemu/qemu_driver.c
> @@ -4099,16 +4099,131 @@ cleanup:
>      return ret;
>  }
>  
> -static int qemudDomainAttachDeviceFlags(virDomainPtr dom,
> +/*
> + * 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)
> +{
> +
> +    /* At first, check device confliction */
> +    switch(newdev->type) {
> +    default:
> +        qemuReportError(VIR_ERR_INVALID_ARG, "%s",

When the device is not supported, we should use VIR_ERR_CONFIG_UNSUPPORTED
instead of VIR_ERR_INVALID_ARG.

> +                        _("Sorry, the device is not suppored for now"));
> +        return -1;
> +    }
> +
> +    return 0;
> +}
> +
> +static int qemuDomainDetachDevicePersistent(virDomainDefPtr vmdef,
> +                                       virDomainDeviceDefPtr device)

The coding style is wrong: virDomainDeviceDefPtr shoulde be left justified
with virDomainDefPtr.

> +{
> +    switch(device->type) {
> +    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, int flags)

Why do you modify the type of flag?

> +{
> +    struct qemud_driver *driver;
> +    virDomainDeviceDefPtr device;
> +    virDomainDefPtr vmdef;
> +    virDomainObjPtr vm;
> +    int ret = -1;
> +
> +    if (!dom || !dom->conn || !dom->name || !xml) {

dom and dom->conn does not need check, they are always not null.

> +        qemuReportError(VIR_ERR_INTERNAL_ERROR,
> +                        _("internal error : %s"),  __FUNCTION__);

Do not use __FUNCTION__ here, the macro qemuReportError will do it.
> +        return -1;
> +    }
> +    /*
> +     * When both of MODIFY_CONFIG and MODIFY_LIVE is specified at the same time,
> +     * return error for now. We should support this later.
> +     */
> +    if (flags & VIR_DOMAIN_DEVICE_MODIFY_LIVE) {
> +        qemuReportError(VIR_ERR_INVALID_ARG, "%s",

Please use VIR_ERR_OPERATION_INVALID instead of VIR_ERR_INVALID_ARG.

> +                        _("Now, cannot modify alive domain and its definition "
> +                          "at the same time."));
>          return -1;
>      }
>  
> -    return qemudDomainAttachDevice(dom, xml);
> +    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);

You use UUID to search the domain, so the error message should be:
no domain with matching uuid '%s'

> +        goto unlock_out;
> +    }
> +
> +    if (qemuDomainObjBeginJobWithDriver(driver, vm) < 0)
> +        goto unlock_out;
> +
> +    if (virDomainObjIsActive(vm)) {
> +        /*
> +         * 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_OPERATION_INVALID, "%s",
> +              _("Now, it's unsupported to update active domain's definition."));
> +        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);
> +    else
> +        ret = qemuDomainDetachDevicePersistent(vmdef, device);
> +
> +    if (!ret) /* save the result */
> +        ret = virDomainSaveConfig(driver->configDir, vmdef);
> +
> +    virDomainDeviceDefFree(device);
> +
> +endjob:
> +    if (qemuDomainObjEndJob(vm) == 0)
> +        vm = NULL;
> +    if (vm)
> +        virDomainObjUnlock(vm);

When qemuDomainObjBeginJobWithDriver() failed, we should unlock the domain.
So we should do it when we goto unlock_out.

> +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, flags);
> +
> +    if (flags & VIR_DOMAIN_DEVICE_MODIFY_LIVE)
> +        return qemudDomainAttachDevice(dom, xml);
> +
> +    qemuReportError(VIR_ERR_INVALID_ARG,
> +        _("bad flag: %x only MODIFY_LIVE, MODIFY_CONFIG are supported now"),
> +       flags);
> +
> +    return -1;
>  }
>  
>  
> @@ -4322,13 +4437,17 @@ 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;
> -    }
>  
> -    return qemudDomainDetachDevice(dom, xml);
> +    if (flags & VIR_DOMAIN_DEVICE_MODIFY_CONFIG)
> +        return qemuDomainModifyDevicePersistent(dom, xml, 0, flags);
> +
> +    if (flags & VIR_DOMAIN_DEVICE_MODIFY_LIVE)
> +        return qemudDomainDetachDevice(dom, xml);
> +
> +    qemuReportError(VIR_ERR_INVALID_ARG,
> +        _("bad flag: %x only MODIFY_LIVE, MODIFY_CONFIG are supported now"),
> +        flags);
> +    return -1;
>  }
>  
>  static int qemudDomainGetAutostart(virDomainPtr dom,