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Re: [libvirt] [PATCH v3 4/4] storage: Disallow usage of the HBA for a fc_host backing



On Thu, Jul 20, 2017 at 03:48:49PM -0400, John Ferlan wrote:
> Disallow providing the wwnn/wwpn of the HBA in the adapter XML:
>
>   <adapter type='fc_host' [parent='scsi_hostN'] wwnn='HBA_wwnn'
>     wwpn='HBA_wwpn'/>
>
> This should be considered a configuration error since a vHBA
> would not be created. In order to use the HBA as the backing the
> following XML should be used:
>
>   <adapter type='scsi_host' name='scsi_hostN'/>
>
> This also alters the caller such that the @parent_name param
> into checkParent can be NULL so as to confirm that at least
> the provided wwnn/wwpn found a vHBA instead of an HBA.
>
> Signed-off-by: John Ferlan <jferlan redhat com>
> ---
>  docs/formatstorage.html.in         | 27 +++++++++++++----------
>  src/storage/storage_backend_scsi.c | 45 ++++++++++++++++++++++++++++----------
>  2 files changed, 49 insertions(+), 23 deletions(-)
>
> diff --git a/docs/formatstorage.html.in b/docs/formatstorage.html.in
> index 4946ddf..27578e8 100644
> --- a/docs/formatstorage.html.in
> +++ b/docs/formatstorage.html.in
> @@ -207,18 +207,21 @@
>          </dl>
>          <dl>
>            <dt><code>wwnn</code> and <code>wwpn</code></dt>
> -          <dd>The "World Wide Node Name" (<code>wwnn</code>) and "World Wide
> -            Port Name" (<code>wwpn</code>) are used by the "fc_host" adapter
> -            to uniquely identify the device in the Fibre Channel storage fabric
> -            (the device can be either a HBA or vHBA). Both wwnn and wwpn should
> -            be specified. Use the command 'virsh nodedev-dumpxml' to determine
> -            how to set the values for the wwnn/wwpn of a (v)HBA. The wwnn and
> -            wwpn have very specific numerical format requirements based on the
> -            hypervisor being used, thus care should be taken if you decide to
> -            generate your own to follow the standards; otherwise, the pool
> -            will fail to start with an opaque error message indicating failure
> -            to write to the vport_create file during vport create/delete due
> -            to "No such file or directory".
> +          <dd>The required "World Wide Node Name" (<code>wwnn</code>) and
> +            "World Wide Port Name" (<code>wwpn</code>) are used by the
> +            "fc_host" adapter to uniquely identify the vHBA device in the
> +            Fibre Channel storage fabric. If the vHBA device already exists
> +            as a Node Device, then libvirt will use it; otherwise, the vHBA
> +            will be created using the provided values. It is considered a
> +            configuration error use the values from the HBA as those would
> +            be for a "scsi_host" <code>type</code> pool instead. The
> +            <code>wwnn</code> and <code>wwpn</code> have very specific
> +            format requirements based on the hypervisor being used, thus
> +            care should be taken if you decide to generate your own to
> +            follow the standards; otherwise, the pool will fail to start
> +            with an opaque error message indicating failure to write to
> +            the vport_create file during vport create/delete due to
> +            "No such file or directory".
>              <span class="since">Since 1.0.4</span>
>            </dd>
>          </dl>
> diff --git a/src/storage/storage_backend_scsi.c b/src/storage/storage_backend_scsi.c
> index af12889..c802738 100644
> --- a/src/storage/storage_backend_scsi.c
> +++ b/src/storage/storage_backend_scsi.c
> @@ -231,22 +231,47 @@ checkParent(virConnectPtr conn,
>      if (!conn)
>          return true;
>
> -    if (virSCSIHostGetNumber(parent_name, &host_num) < 0) {
> -        virReportError(VIR_ERR_XML_ERROR,
> -                       _("parent '%s' is not properly formatted"),
> -                       parent_name);
> +    /* If there's a parent_name, then make sure it's valid */
> +    if (parent_name) {
> +        if (virSCSIHostGetNumber(parent_name, &host_num) < 0) {
> +            virReportError(VIR_ERR_XML_ERROR,
> +                           _("parent '%s' is not properly formatted"),
> +                           parent_name);
> +            goto cleanup;
> +        }
> +
> +        if (!virVHBAPathExists(NULL, host_num)) {
> +            virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
> +                           _("parent '%s' is not an fc_host for the wwnn/wwpn"),
> +                           parent_name);
> +            goto cleanup;
> +        }
> +    }

^Here you're handling the device's parent - it's existence

> +
> +    if (virAsprintf(&scsi_host_name, "scsi_%s", name) < 0)
> +        goto cleanup;
> +
> +    if (virSCSIHostGetNumber(scsi_host_name, &host_num) < 0) {
> +        virReportError(VIR_ERR_INTERNAL_ERROR,
> +                       _("host name '%s' is not properly formatted"),
> +                       name);
>          goto cleanup;
>      }
>
> -    if (!virVHBAPathExists(NULL, host_num)) {
> +    /* If scsi_host_name is vport capable, then it's an HBA. This is
> +     * a configuration error as the wwnn/wwpn should only be for a vHBA */
> +    if (virVHBAIsVportCapable(NULL, host_num)) {
>          virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
> -                       _("parent '%s' is not an fc_host for the wwnn/wwpn"),
> -                       parent_name);
> +                       _("the wwnn/wwpn for '%s' are assigned to an HBA"),
> +                       scsi_host_name);
>          goto cleanup;
>      }

^Here you're handling the device itself.

>
> -    if (virAsprintf(&scsi_host_name, "scsi_%s", name) < 0)
> +    /* No parent name, then no need to get/compare against vhba_parent */
> +    if (!parent_name) {
> +        retval = true;
>          goto cleanup;
> +    }
>

And ^here you're again handling the device's parent - it's !existence and
perform some further parent device validation in the already existing hunk
below. Would it make more sense to first verify the device whether it's a vHBA,
if not then throw an error and then, if @parent_name wasn't supplied, return
successfully otherwise do both the parent existence check and validation, both
in a large "else" block. The checks make sense and work as described, I just
find it more understandable - the logic would be IMHO more continuous, as
opposed "scattered" (is that even the right term for this? But I think you get
the picture...)

if (scsi_host_name is vport capable)
    # it's an HBA
    error
    return failure

if (!parent_name)
    # no parent to validate
    return success
else
    if (parent doesn't exist)
        error - not an fc_host
        return failure

    if (provided_parent != actual_parent)
        error - invalid parent
        return failure

return success

Erik.

>      if (!(vhba_parent = virNodeDeviceGetParentName(conn, scsi_host_name)))
>          goto cleanup;
> @@ -288,9 +313,7 @@ createVport(virConnectPtr conn,
>       * this pool and we don't have to create the vHBA
>       */
>      if ((name = virVHBAGetHostByWWN(NULL, fchost->wwnn, fchost->wwpn))) {
> -        /* If a parent was provided, let's make sure the 'name' we've
> -         * retrieved has the same parent. If not this will cause failure. */
> -        if (!fchost->parent || checkParent(conn, name, fchost->parent))
> +        if (checkParent(conn, name, fchost->parent))
>              ret = 0;
>
>          goto cleanup;
> --
> 2.9.4
>
> --
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