static void coroutine_fn stream_run(void *opaque) { StreamBlockJob *s = opaque; BlockDriverState *bs = s->common.bs; BlockDriverState *base = s->base; int64_t sector_num, end; int error = 0; int ret = 0; int n = 0; void *buf; s->common.len = bdrv_getlength(bs); if (s->common.len < 0) { block_job_completed(&s->common, s->common.len); return; } end = s->common.len >> BDRV_SECTOR_BITS; buf = qemu_blockalign(bs, STREAM_BUFFER_SIZE); /* Turn on copy-on-read for the whole block device so that guest read * requests help us make progress. Only do this when copying the entire * backing chain since the copy-on-read operation does not take base into * account. */ if (!base) { bdrv_enable_copy_on_read(bs); } for (sector_num = 0; sector_num < end; sector_num += n) { uint64_t delay_ns = 0; bool copy; wait: /* Note that even when no rate limit is applied we need to yield * with no pending I/O here so that bdrv_drain_all() returns. */ block_job_sleep_ns(&s->common, QEMU_CLOCK_REALTIME, delay_ns); if (block_job_is_cancelled(&s->common)) { break; } ret = bdrv_is_allocated(bs, sector_num, STREAM_BUFFER_SIZE / BDRV_SECTOR_SIZE, &n); if (ret == 1) { /* Allocated in the top, no need to copy. */ copy = false; } else if (ret >= 0) { /* Copy if allocated in the intermediate images. Limit to the * known-unallocated area [sector_num, sector_num+n). */ ret = bdrv_is_allocated_above(bs->backing_hd, base, sector_num, n, &n); /* Finish early if end of backing file has been reached */ if (ret == 0 && n == 0) { n = end - sector_num; } copy = (ret == 1); } trace_stream_one_iteration(s, sector_num, n, ret); if (ret >= 0 && copy) { if (s->common.speed) { delay_ns = ratelimit_calculate_delay(&s->limit, n); if (delay_ns > 0) { goto wait; } } ret = stream_populate(bs, sector_num, n, buf); } if (ret < 0) { BlockErrorAction action = block_job_error_action(&s->common, s->common.bs, s->on_error, true, -ret); if (action == BDRV_ACTION_STOP) { n = 0; continue; } if (error == 0) { error = ret; } if (action == BDRV_ACTION_REPORT) { break; } } ret = 0; /* Publish progress */ s->common.offset += n * BDRV_SECTOR_SIZE; } if (!base) { bdrv_disable_copy_on_read(bs); } /* Do not remove the backing file if an error was there but ignored. */ ret = error; if (!block_job_is_cancelled(&s->common) && sector_num == end && ret == 0) { const char *base_id = NULL, *base_fmt = NULL; if (base) { base_id = s->backing_file_id; if (base->drv) { base_fmt = base->drv->format_name; } } ret = bdrv_change_backing_file(bs, base_id, base_fmt); close_unused_images(bs, base, base_id); } qemu_vfree(buf); block_job_completed(&s->common, ret); }