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

[KAMEZAWA Hiroyuki]

Thank you for review.

On Thu, 24 Feb 2011 14:25:24 +0800
Hu Tao <hutao at cn.fujitsu.com> wrote:

> 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 at 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 at 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().
> 

Hmm, ok.


> > +            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.
> 

ok, will add a patch for conf/domain_conf.c



> > +            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().
> 

Ok, will remove.


> > +
> > +    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.
> 
It seems...."virDomainObjIsActive(vm) check" is lacked..

Above 'if' returns true only when timeout..

> > +        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;
> 

will fix.

Thanks,
-Kame