Re: [libvirt] [PATCHv2 09/33] storage: backend: Add unique id retrieval API

Different protocols have different means to uniquely identify a storage file. This patch implements a storage driver API to retrieve a unique string describing a volume. The current implementation works for local storage only and returns the canonical path of the volume. To add caching support the local filesystem driver now has a private structure holding the cached string, which is created only when it's initially accessed. This patch provides the implementation for local files only for start. --- src/storage/storage_backend.h | 3 +++ src/storage/storage_backend_fs.c | 49 ++++++++++++++++++++++++++++++++++++++++ src/storage/storage_driver.c | 30 ++++++++++++++++++++++++ src/storage/storage_driver.h | 1 + 4 files changed, 83 insertions(+)

+typedef struct _virStorageFileBackendFsPriv virStorageFileBackendFsPriv; +typedef virStorageFileBackendFsPriv *virStorageFileBackendFsPrivPtr; + +struct _virStorageFileBackendFsPriv { + char *uid; /* unique file identifier (canonical path) */

+}; + + static void virStorageFileBackendFileDeinit(virStorageSourcePtr src) { @@ -1346,16 +1354,27 @@ virStorageFileBackendFileDeinit(virStorageSourcePtr src) virStorageTypeToString(virStorageSourceGetActualType(src)), src->path); + virStorageFileBackendFsPrivPtr priv = src->drv->priv; + + VIR_FREE(priv->uid);

+/* + * virStorageFileGetUniqueIdentifier: Get a unique string describing the volume + * + * @src: file structure pointing to the file + * + * Returns a string uniquely describing a single volume (canonical path). + * The string shall not be freed. Returns NULL on error and sets a libvirt + * error code */