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Re: [libvirt] [PATCH 1/6] Add virDomainGetBlockInfo API to query disk sizing



On Wed, Apr 28, 2010 at 01:54:45PM +0100, Daniel P. Berrange wrote:
> Some applications need to be able to query a guest's disk info,
> even for paths not managed by the storage pool APIs. This adds
> a very simple API to get this information, modelled on the
> virStorageVolGetInfo API, but with an extra field 'physical'.
> Normally 'physical' and 'allocation' will be identical, but
> in the case of a qcow2-like file stored inside a block device
> 'physical' will give the block device size, while 'allocation'
> will give the qcow2 image size
[....]
> +
> +/** virDomainBlockInfo:
> + *
> + * This struct provides information about the size of a block device backing store
> + *
> + * Examples:
> + *
> + *  - Fully allocated raw file in filesystem:
> + *       * capacity, allocation, physical: All the same
> + *
> + *  - Sparse raw file in filesystem:
> + *       * capacity: logical size of the file
> + *       * allocation, physical: number of blocks allocated to file
> + *
> + *  - qcow2 file in filesystem
> + *       * capacity: logical size from qcow2 header
> + *       * allocation, physical: logical size of the file / highest qcow extent (identical)
> + *
> + *  - qcow2 file in a block device
> + *       * capacity: logical size from qcow2 header
> + *       * allocation: highest qcow extent written
> + *       * physical: size of the block device container
> + */

  Argh, forgot that in my previous review, we need to explicitely tell
  the size units, I expect bytes but we're unsing kB in some places
  so...

> +typedef struct _virDomainBlockInfo virDomainBlockInfo;
> +typedef virDomainBlockInfo *virDomainBlockInfoPtr;
> +struct _virDomainBlockInfo {
> +    unsigned long long capacity;   /* logical size of the block device backing image */
> +    unsigned long long allocation; /* allocated extent of the block device backing image */
> +    unsigned long long physical;   /* physical size of the container of the backing image */
> +};

  s/size/size in bytes/g

Daniel

-- 
Daniel Veillard      | libxml Gnome XML XSLT toolkit  http://xmlsoft.org/
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