[libvirt] [PATCH 6/6] unpriv_sgio: Error out if the unpriv_sgio setting conflicts with others

[Daniel P. Berrange]

On Mon, Nov 26, 2012 at 06:21:42PM +0800, Osier Yang wrote:
> This prevent the domain starting if the shared disk's setting conflicts
> with other active domain(s), E.g. A domain with unpriv_sgio set as
> "yes", however, another active domain is using it set as "no".
> ---
>  src/conf/domain_conf.c   |   45 +++++++++++++++++++++++++++++++++++++++++++++
>  src/conf/domain_conf.h   |    3 +++
>  src/libvirt_private.syms |    1 +
>  src/qemu/qemu_process.c  |   14 +++++++++++++-
>  4 files changed, 62 insertions(+), 1 deletions(-)
> 
> diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c
> index 02df96e..fb7bb1f 100644
> --- a/src/conf/domain_conf.c
> +++ b/src/conf/domain_conf.c
> @@ -15763,3 +15763,48 @@ virDomainDiskIsUsed(const virDomainObjList doms,
>  
>      return false;
>  }
> +
> +static int
> +virDomainSharedDiskCompare(const void *payload,
> +                           const void *name ATTRIBUTE_UNUSED,
> +                           const void *opaque)
> +{
> +    virDomainObjPtr obj = (virDomainObjPtr)payload;
> +    const virDomainDiskDefPtr disk = (virDomainDiskDefPtr)opaque;
> +    int i;
> +
> +    virDomainObjLock(obj);
> +
> +    /* Ingores the inactive ones */
> +    if (!virDomainObjIsActive(obj))
> +        return 0;
> +
> +    for (i = 0; i < obj->def->ndisks; i++) {
> +        if (STRNEQ(obj->def->disks[i]->src, disk->src))
> +            continue;
> +
> +        if (obj->def->disks[i]->unpriv_sgio != disk->unpriv_sgio) {
> +            virDomainObjUnlock(obj);
> +            return 1;
> +        }
> +    }
> +
> +    virDomainObjUnlock(obj);
> +    return 0;
> +}
> +
> +/* Validate if the shared disk conf is conflicted with other domains,
> + * currently only validates the unpriv_sgio setting
> + */
> +bool
> +virDomainSharedDiskValidate(const virDomainObjList doms,
> +                            const virDomainDiskDefPtr disk)
> +{
> +    virDomainObjPtr obj;
> +
> +    obj = virHashSearch(doms.objs, virDomainSharedDiskCompare, disk);
> +    if (obj)
> +        return false;
> +
> +    return true;
> +}

This code is rather undesirable since it requires locking every
single VM known to the QEMU driver. Better to use the model we
have for PCI/USB devices where the driver maintains a central
list of the devices 

Daniel
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