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

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 + */

+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 */ +};