[libvirt] [PATCH 1/1] storage: resize vol against real allocated size when --allocate is specified

[Michal Privoznik]

On 16.12.2013 06:00, Wang Sen wrote:
> Currently, vol-resize allocates more bytes against vol->capacity, but
> vol->capacity may be different from the real allocated size because --allocate
> may not be specified. e.g.
> 	[root at localhost ~]# virsh vol-list --pool tmp-pool --details
> 	 name path type Capacity allocated
> 	-------------------------------------------------------------
> 	 tmp-vol  /root/tmp-pool/tmp-vol  file  1.00 GiB  1.00 GiB
> 	[root at localhost ~]# virsh vol-resize tmp-vol --pool tmp-pool 2G
> 	[root at localhost ~]# virsh vol-list --pool tmp-pool --details
> 	 name path type Capacity allocated
> 	-------------------------------------------------------------
> 	 tmp-vol  /root/tmp-pool/tmp-vol  file  2.00 GiB  1.00 GiB
> So, if we want to allocate more bytes to 3G, the real allocated size is 2G
> actually.
> 	[root at localhost ~]# virsh vol-resize tmp-vol --pool tmp-pool 3G --allocate
> 	[root at localhost ~]# virsh vol-list --pool tmp-pool --details
> 	 name path type Capacity allocated
> 	-------------------------------------------------------------
> 	 tmp-vol  /root/tmp-pool/tmp-vol  file  3.00 GiB  2.00 GiB
> This patch enable resize vol against the real allocated size. After this patch
> is applied, the result of the last resize command become 3G.
> 	[root at localhost ~]# virsh vol-resize tmp-vol --pool tmp-pool 3G --allocate
> 	[root at localhost ~]# virsh vol-list --pool tmp-pool --details
> 	 name path type Capacity allocated
> 	-------------------------------------------------------------
> 	 tmp-vol  /root/tmp-pool/tmp-vol  file  3.00 GiB  3.00 GiB
> 
> Signed-off-by: Wang Sen <wangsen at linux.vnet.ibm.com>
> ---
>  src/storage/storage_backend_fs.c | 17 ++++++++++++++++-
>  1 file changed, 16 insertions(+), 1 deletion(-)
> 
> diff --git a/src/storage/storage_backend_fs.c b/src/storage/storage_backend_fs.c
> index 11cf2df..e75c57b 100644
> --- a/src/storage/storage_backend_fs.c
> +++ b/src/storage/storage_backend_fs.c
> @@ -1261,13 +1261,28 @@ virStorageBackendFileSystemVolResize(virConnectPtr conn ATTRIBUTE_UNUSED,
>                                       unsigned long long capacity,
>                                       unsigned int flags)
>  {
> +    int fd = -1;
>      virCheckFlags(VIR_STORAGE_VOL_RESIZE_ALLOCATE, -1);
> +    unsigned long long orig_capacity;
> +    virStorageFileMetadataPtr meta = NULL;
> +
> +    if ((fd = open(vol->target.path, O_RDWR)) < 0) {
> +        virReportError(VIR_ERR_INTERNAL_ERROR, "%s", _("Can not open file"));
> +    }
> +
> +    if (!(meta =  virStorageFileGetMetadataFromFD(vol->target.path, fd, \
> +                                                  vol->target.format))) {
> +        virReportError(VIR_ERR_INTERNAL_ERROR, "%s", _("Get meta data error!"));
> +    }
> +    orig_capacity = meta->capacity;
> +    virStorageFileFreeMetadata(meta);
> +    close(fd);

Using close() is prohibited and you should you VIR_CLOSE instead.
However, there's no need to do this while we have
virStorageFileGetMetadata(), Nor it's needed for other formats than _RAW.

>  
>      bool pre_allocate = flags & VIR_STORAGE_VOL_RESIZE_ALLOCATE;
>  
>      if (vol->target.format == VIR_STORAGE_FILE_RAW) {
>          return virStorageFileResize(vol->target.path, capacity,
> -                                    vol->capacity, pre_allocate);
> +                                    orig_capacity, pre_allocate);
>      } else {
>          if (pre_allocate) {
>              virReportError(VIR_ERR_OPERATION_UNSUPPORTED, "%s",
> 

I agree that we have a bug here. But I think we need this modified
version. I'll post it shortly.

Michal