Re: [libvirt] API Proposal: virDomainBlockPull() (Block device streaming) V4

/**  * virDomainBlockPull:  * @dom: pointer to domain object  * @path: Fully-qualified filename of disk  * @cursor: pointer to a virDomainBlockPullCursor, or NULL  * @flags: One of virDomainBlockPullFlags, or zero  *  * Populate a disk image with data from its backing image.  Once all data from  * its backing image has been pulled, the disk no longer depends on a backing  * image.  *  * If VIR_DOMAIN_BLOCK_PULL_CONTINUOUS is specified, the entire device will be  * streamed in the background.  Otherwise, the value stored in @cursor will be  * used to stream an increment.  *  * Returns -1 in case of failure, 0 when successful.  On success and when @flags  * does not contain VIR_DOMAIN_BLOCK_PULL_CONTINUOUS, the iterator @cursor will  * be updated to the proper value for use in a subsequent call.  */ int                 virDomainBlockPull(virDomainPtr dom,                                       const char *path,                                       virDomainBlockPullCursor *cursor,                                       unsigned int flags);

NOTE: Qemu will emit an asynchronous event (VIR_DOMAIN_BLOCK_PULL_COMPLETED) after any operation that eliminates the dependency on the backing file.  This could be a virDomainBlockPull() without VIR_DOMAIN_BLOCK_PULL_CONTINUOUS and will allow libvirt to manage backing file security regardless of the pull mode used.