[libvirt] [PATCH 3/3] virsh: Allow display of the physical volume size

[Michal Privoznik]

On 13.12.2016 22:07, John Ferlan wrote:
> Add a new qualifier '--physical' to the 'vol-info' command in order to
> dispaly the physical size of the volume. The size can differ from the
> allocation value depending on the volume file time. In particular, qcow2
> volumes will have a physical value larger than allocation. This also occurs
> for sparse files, although for those the capacity is the largest size;
> whereas, for qcow2 capacity is the logical size.
> 
> Signed-off-by: John Ferlan <jferlan at redhat.com>
> ---
>  tools/virsh-volume.c | 37 +++++++++++++++++++++++++++++++++----
>  tools/virsh.pod      |  8 ++++++--
>  2 files changed, 39 insertions(+), 6 deletions(-)
> 
> diff --git a/tools/virsh-volume.c b/tools/virsh-volume.c
> index 96b4a7b..f702627 100644
> --- a/tools/virsh-volume.c
> +++ b/tools/virsh-volume.c
> @@ -996,6 +996,10 @@ static const vshCmdOptDef opts_vol_info[] = {
>       .type = VSH_OT_BOOL,
>       .help = N_("sizes are represented in bytes rather than pretty units")
>      },
> +    {.name = "physical",
> +     .type = VSH_OT_BOOL,
> +     .help = N_("return the physical size of the volume in allocation field")
> +    },
>      {.name = NULL}
>  };
>  
> @@ -1005,14 +1009,32 @@ cmdVolInfo(vshControl *ctl, const vshCmd *cmd)
>      virStorageVolInfo info;
>      virStorageVolPtr vol;
>      bool bytes = vshCommandOptBool(cmd, "bytes");
> +    bool physical = vshCommandOptBool(cmd, "physical");
>      bool ret = true;
> +    int rc;
> +    unsigned int flags = 0;
>  
>      if (!(vol = virshCommandOptVol(ctl, cmd, "vol", "pool", NULL)))
>          return false;
>  
>      vshPrint(ctl, "%-15s %s\n", _("Name:"), virStorageVolGetName(vol));
>  
> -    if (virStorageVolGetInfo(vol, &info) == 0) {
> +    if (physical)
> +        flags |= VIR_STORAGE_VOL_GET_PHYSICAL;
> +
> +    if (flags) {
> +        if ((rc = virStorageVolGetInfoFlags(vol, &info, flags)) < 0) {
> +            flags = 0;
> +            if (last_error->code == VIR_ERR_NO_SUPPORT) {
> +                vshResetLibvirtError();
> +                rc = virStorageVolGetInfo(vol, &info);

I don't think this is right. User had requested --physical. We should
either get them what they demand or error out. This is not the case like
in some other APIs where we can fetch a piece of info from different
APIs and we iterate over them.

> +            }
> +        }
> +    } else {
> +        rc = virStorageVolGetInfo(vol, &info);
> +    }
> +
> +    if (rc == 0) {
>          double val;
>          const char *unit;
>  
> @@ -1028,11 +1050,18 @@ cmdVolInfo(vshControl *ctl, const vshCmd *cmd)
>          }
>  
>          if (bytes) {
> -            vshPrint(ctl, "%-15s %llu %s\n", _("Allocation:"),
> -                     info.allocation, _("bytes"));
> +            if (physical)
> +                vshPrint(ctl, "%-15s %llu %s\n", _("Physical:"),
> +                         info.allocation, _("bytes"));
> +            else
> +                vshPrint(ctl, "%-15s %llu %s\n", _("Allocation:"),
> +                         info.allocation, _("bytes"));
>           } else {
>              val = vshPrettyCapacity(info.allocation, &unit);
> -            vshPrint(ctl, "%-15s %2.2lf %s\n", _("Allocation:"), val, unit);
> +            if (physical)
> +                vshPrint(ctl, "%-15s %2.2lf %s\n", _("Physical:"), val, unit);
> +            else
> +                vshPrint(ctl, "%-15s %2.2lf %s\n", _("Allocation:"), val, unit);
>           }
>      } else {
>          ret = false;
> diff --git a/tools/virsh.pod b/tools/virsh.pod
> index 74c05c9..f606f4f 100644
> --- a/tools/virsh.pod
> +++ b/tools/virsh.pod
> @@ -3862,13 +3862,17 @@ is in. I<vol-name-or-key-or-path> is the name or key or path of the volume
>  to output the XML of.
>  
>  =item B<vol-info> [I<--pool> I<pool-or-uuid>] I<vol-name-or-key-or-path>
> -[I<--bytes>]
> +[I<--bytes>] [I<--physical>]
>  
>  Returns basic information about the given storage volume.
>  I<--pool> I<pool-or-uuid> is the name or UUID of the storage pool the volume
>  is in. I<vol-name-or-key-or-path> is the name or key or path of the volume
>  to return information for. If I<--bytes> is specified the sizes are not
> -converted to human friendly units.
> +converted to human friendly units. If I<--physical> is specified, then the host
> +physical size is returned and displayed instead of the allocation value. The
> +physical value for some file types, such as qcow2 may have a different (larger)
> +physical value than is shown for allocation. Additionally sparse files will
> +have different physical and allocation values.

If we want this to be true, we must error out if
virStorageVolGetInfoFlags() fails (e.g. because its missing as a result
of talking to older daemon). Otherwise, vol-info --physical ... might
return allocation values which contradicts the documentation.

ACK if you fix it.

Michal