+ }
+}
+
+static uint64_t coroutine_fn mirror_iteration(MirrorBlockJob *s)
+{
+ BlockDriverState *source = s->common.bs;
+ int64_t sector_num, first_chunk;
+ uint64_t delay_ns = 0;
+ /* At least the first dirty chunk is mirrored in one iteration. */
+ int nb_chunks = 1;
+ int64_t end = s->bdev_length / BDRV_SECTOR_SIZE;
+ int sectors_per_chunk = s->granularity >> BDRV_SECTOR_BITS;
+
+ sector_num = hbitmap_iter_next(&s->hbi);
+ if (sector_num < 0) {
+ bdrv_dirty_iter_init(s->dirty_bitmap, &s->hbi);
+ sector_num = hbitmap_iter_next(&s->hbi);
+ trace_mirror_restart_iter(s, bdrv_get_dirty_count(s->dirty_bitmap));
+ assert(sector_num >= 0);
+ }
+
+ first_chunk = sector_num / sectors_per_chunk;
+ while (test_bit(first_chunk, s->in_flight_bitmap)) {
+ trace_mirror_yield_in_flight(s, first_chunk, s->in_flight);
+ mirror_wait_for_io(s);
+ }
+
+ /* Find the number of consective dirty chunks following the first dirty
+ * one, and wait for in flight requests in them. */
+ while (nb_chunks * sectors_per_chunk < (s->buf_size >> BDRV_SECTOR_BITS)) {
+ int64_t hbitmap_next;
+ int64_t next_sector = sector_num + nb_chunks * sectors_per_chunk;
+ int64_t next_chunk = next_sector / sectors_per_chunk;
+ if (next_sector >= end ||
+ !bdrv_get_dirty(source, s->dirty_bitmap, next_sector)) {
+ break;
+ }
+ if (test_bit(next_chunk, s->in_flight_bitmap)) {
+ break;
+ }
+
+ hbitmap_next = hbitmap_iter_next(&s->hbi);
+ if (hbitmap_next > next_sector || hbitmap_next < 0) {
+ /* The bitmap iterator's cache is stale, refresh it */
+ bdrv_set_dirty_iter(&s->hbi, next_sector);
+ hbitmap_next = hbitmap_iter_next(&s->hbi);
+ }
+ assert(hbitmap_next == next_sector);
+ nb_chunks++;
+ }
+
+ /* Clear dirty bits before querying the block status, because
+ * calling bdrv_get_block_status_above could yield - if some blocks are
+ * marked dirty in this window, we need to know.
+ */
+ bdrv_reset_dirty_bitmap(s->dirty_bitmap, sector_num,
+ nb_chunks * sectors_per_chunk);
+ bitmap_set(s->in_flight_bitmap, sector_num / sectors_per_chunk, nb_chunks);
+ while (nb_chunks > 0 && sector_num < end) {
+ int ret;
+ int io_sectors;
+ BlockDriverState *file;
+ enum MirrorMethod {
+ MIRROR_METHOD_COPY,
+ MIRROR_METHOD_ZERO,
+ MIRROR_METHOD_DISCARD
+ } mirror_method = MIRROR_METHOD_COPY;
+
+ assert(!(sector_num % sectors_per_chunk));
+ ret = bdrv_get_block_status_above(source, NULL, sector_num,
+ nb_chunks * sectors_per_chunk,
+ &io_sectors, &file);
+ if (ret < 0) {
+ io_sectors = nb_chunks * sectors_per_chunk;
+ }
+
+ io_sectors -= io_sectors % sectors_per_chunk;
+ if (io_sectors < sectors_per_chunk) {
+ io_sectors = sectors_per_chunk;
+ } else if (ret >= 0 && !(ret & BDRV_BLOCK_DATA)) {
+ int64_t target_sector_num;
+ int target_nb_sectors;
+ bdrv_round_to_clusters(s->target, sector_num, io_sectors,
+ &target_sector_num, &target_nb_sectors);
+ if (target_sector_num == sector_num &&
+ target_nb_sectors == io_sectors) {
+ mirror_method = ret & BDRV_BLOCK_ZERO ?
+ MIRROR_METHOD_ZERO :
+ MIRROR_METHOD_DISCARD;
+ }
+ }
+
+ mirror_clip_sectors(s, sector_num, &io_sectors);
+ switch (mirror_method) {
+ case MIRROR_METHOD_COPY:
+ io_sectors = mirror_do_read(s, sector_num, io_sectors);
+ break;
+ case MIRROR_METHOD_ZERO:
+ mirror_do_zero_or_discard(s, sector_num, io_sectors, false);
+ break;
+ case MIRROR_METHOD_DISCARD:
+ mirror_do_zero_or_discard(s, sector_num, io_sectors, true);
+ break;
+ default:
+ abort();
+ }
+ assert(io_sectors);
+ sector_num += io_sectors;
+ nb_chunks -= DIV_ROUND_UP(io_sectors, sectors_per_chunk);
+ delay_ns += ratelimit_calculate_delay(&s->limit, io_sectors);