Re: [PATCH v4 09/11] qemu: validate: Allow <transient/> disks

[Ján Tomko <jtomko@xxxxxxxxxx>]

On a Thursday in 2020, Peter Krempa wrote:
> From: Masayoshi Mizuma <m.mizuma@xxxxxxxxxxxxxx>
>
> Extract the validation of transient disk option. We support transient
> disks in qemu under the following conditions:
>
> - -blockdev is used
> - the disk source is a local file
> - the disk type is 'disk'
> - the disk is not readonly
>
> Signed-off-by: Masayoshi Mizuma <m.mizuma@xxxxxxxxxxxxxx>
> Signed-off-by: Peter Krempa <pkrempa@xxxxxxxxxx>
> ---
> docs/formatdomain.rst    |  5 ++--
> src/qemu/qemu_validate.c | 56 +++++++++++++++++++++++++++++++++++-----
> 2 files changed, 53 insertions(+), 8 deletions(-)
>
> diff --git a/docs/formatdomain.rst b/docs/formatdomain.rst
> index 888db5ea29..cc1467c0e6 100644
> --- a/docs/formatdomain.rst
> +++ b/docs/formatdomain.rst
> @@ -2974,8 +2974,9 @@ paravirtualized driver is specified via the ``disk`` element.
> ``transient``
>    If present, this indicates that changes to the device contents should be
>    reverted automatically when the guest exits. With some hypervisors, marking a
> -   disk transient prevents the domain from participating in migration or
> -   snapshots. Only suppported in vmx hypervisor. :since:`Since 0.9.5`
> +   disk transient prevents the domain from participating in migration,
> +   snapshots, or blockjobs. Only suppported in vmx hypervisor

I'd say:
  *supported
but that's pre-existing.

> +   (:since:`Since 0.9.5`) and ``qemu`` hypervisor (:since:`Since 6.9.0`).
> ``serial``
>    If present, this specify serial number of virtual hard drive. For example, it
>    may look like ``<serial>WD-WMAP9A966149</serial>``. Not supported for
> diff --git a/src/qemu/qemu_validate.c b/src/qemu/qemu_validate.c
> index 3ed4039cdf..3196814aca 100644
> --- a/src/qemu/qemu_validate.c
> +++ b/src/qemu/qemu_validate.c
> @@ -2186,12 +2186,6 @@ qemuValidateDomainDeviceDefDiskFrontend(const virDomainDiskDef *disk,
>         }
>     }
>
> -    if (disk->transient) {
> -        virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
> -                       _("transient disks not supported yet"));
> -        return -1;
> -    }
> -
>     if (disk->iomode == VIR_DOMAIN_DISK_IO_NATIVE &&
>         disk->cachemode != VIR_DOMAIN_DISK_CACHE_DIRECTSYNC &&
>         disk->cachemode != VIR_DOMAIN_DISK_CACHE_DISABLE) {
> @@ -2340,6 +2334,53 @@ qemuValidateDomainDeviceDefDiskBlkdeviotune(const virDomainDiskDef *disk,
> }
>
>
> +static int
> +qemuValidateDomainDeviceDefDiskTransient(const virDomainDiskDef *disk,
> +                                         virQEMUCapsPtr qemuCaps)
> +
> +{
> +    virStorageType actualType = virStorageSourceGetActualType(disk->src);
> +
> +    if (!disk->transient)
> +        return 0;
> +
> +    if (virStorageSourceIsEmpty(disk->src)) {
> +        virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
> +                       _("transient disk '%s' must not be empty"), disk->dst);
> +        return -1;
> +    }
> +
> +    if (disk->src->readonly) {
> +        virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
> +                       _("transient disk '%s' must not be read-only"), disk->dst);
> +        return -1;
> +    }
> +
> +    if (actualType != VIR_STORAGE_TYPE_FILE) {
> +        virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
> +                       _("transient disk supported only with 'file' type (%s)"),
> +                       disk->dst);
> +        return -1;
> +    }
> +
> +    if (disk->device != VIR_DOMAIN_DISK_DEVICE_DISK) {
> +        virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
> +                       _("transient disk supported only with 'disk' device (%s)"),
> +                       disk->dst);
> +        return -1;
> +    }
> +
> +    if (qemuCaps && !virQEMUCapsGet(qemuCaps, QEMU_CAPS_BLOCKDEV)) {
> +        virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
> +                       _("transient disk not supported by this qemu binary (%s)"),

s/qemu/QEMU/

Jano

> +                       disk->dst);
> +        return -1;
> +    }
> +
> +    return 0;
> +}
> +
> +
> int
> qemuValidateDomainDeviceDefDisk(const virDomainDiskDef *disk,
>                                 const virDomainDef *def,

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