diff --git a/block/mirror.c b/block/mirror.c index bca99ec206..724318f037 100644 --- a/block/mirror.c +++ b/block/mirror.c @@ -73,6 +73,7 @@ typedef struct MirrorBlockJob { size_t buf_size; int64_t bdev_length; unsigned long *cow_bitmap; + unsigned long *zero_bitmap; BdrvDirtyBitmap *dirty_bitmap; BdrvDirtyBitmapIter *dbi; uint8_t *buf; @@ -108,9 +109,12 @@ struct MirrorOp { int64_t offset; uint64_t bytes; - /* The pointee is set by mirror_co_read(), mirror_co_zero(), and - * mirror_co_discard() before yielding for the first time */ + /* + * These pointers are set by mirror_co_read(), mirror_co_zero(), and + * mirror_co_discard() before yielding for the first time + */ int64_t *bytes_handled; + bool *io_skipped; bool is_pseudo_op; bool is_active_write; @@ -408,15 +412,34 @@ static void coroutine_fn mirror_co_read(void *opaque) static void coroutine_fn mirror_co_zero(void *opaque) { MirrorOp *op = opaque; - int ret; + bool write_needed = true; + int ret = 0; op->s->in_flight++; op->s->bytes_in_flight += op->bytes; *op->bytes_handled = op->bytes; op->is_in_flight = true; - ret = blk_co_pwrite_zeroes(op->s->target, op->offset, op->bytes, - op->s->unmap ? BDRV_REQ_MAY_UNMAP : 0); + if (op->s->zero_bitmap) { + unsigned long end = DIV_ROUND_UP(op->offset + op->bytes, + op->s->granularity); + assert(QEMU_IS_ALIGNED(op->offset, op->s->granularity)); + assert(QEMU_IS_ALIGNED(op->bytes, op->s->granularity) || + op->offset + op->bytes == op->s->bdev_length); + if (find_next_zero_bit(op->s->zero_bitmap, end, + op->offset / op->s->granularity) == end) { + write_needed = false; + *op->io_skipped = true; + } + } + if (write_needed) { + ret = blk_co_pwrite_zeroes(op->s->target, op->offset, op->bytes, + op->s->unmap ? BDRV_REQ_MAY_UNMAP : 0); + } + if (ret >= 0 && op->s->zero_bitmap) { + bitmap_set(op->s->zero_bitmap, op->offset / op->s->granularity, + DIV_ROUND_UP(op->bytes, op->s->granularity)); + } mirror_write_complete(op, ret); } @@ -435,29 +458,43 @@ static void coroutine_fn mirror_co_discard(void *opaque) } static unsigned mirror_perform(MirrorBlockJob *s, int64_t offset, - unsigned bytes, MirrorMethod mirror_method) + unsigned bytes, MirrorMethod mirror_method, + bool *io_skipped) { MirrorOp *op; Coroutine *co; int64_t bytes_handled = -1; + assert(QEMU_IS_ALIGNED(offset, s->granularity)); + assert(QEMU_IS_ALIGNED(bytes, s->granularity) || + offset + bytes == s->bdev_length); op = g_new(MirrorOp, 1); *op = (MirrorOp){ .s = s, .offset = offset, .bytes = bytes, .bytes_handled = &bytes_handled, + .io_skipped = io_skipped, }; qemu_co_queue_init(&op->waiting_requests); switch (mirror_method) { case MIRROR_METHOD_COPY: + if (s->zero_bitmap) { + bitmap_clear(s->zero_bitmap, offset / s->granularity, + DIV_ROUND_UP(bytes, s->granularity)); + } co = qemu_coroutine_create(mirror_co_read, op); break; case MIRROR_METHOD_ZERO: + /* s->zero_bitmap handled in mirror_co_zero */ co = qemu_coroutine_create(mirror_co_zero, op); break; case MIRROR_METHOD_DISCARD: + if (s->zero_bitmap) { + bitmap_clear(s->zero_bitmap, offset / s->granularity, + DIV_ROUND_UP(bytes, s->granularity)); + } co = qemu_coroutine_create(mirror_co_discard, op); break; default: @@ -568,6 +605,7 @@ static void coroutine_fn GRAPH_UNLOCKED mirror_iteration(MirrorBlockJob *s) int ret = -1; int64_t io_bytes; int64_t io_bytes_acct; + bool io_skipped = false; MirrorMethod mirror_method = MIRROR_METHOD_COPY; assert(!(offset % s->granularity)); @@ -611,8 +649,10 @@ static void coroutine_fn GRAPH_UNLOCKED mirror_iteration(MirrorBlockJob *s) } io_bytes = mirror_clip_bytes(s, offset, io_bytes); - io_bytes = mirror_perform(s, offset, io_bytes, mirror_method); - if (mirror_method != MIRROR_METHOD_COPY && write_zeroes_ok) { + io_bytes = mirror_perform(s, offset, io_bytes, mirror_method, + &io_skipped); + if (io_skipped || + (mirror_method != MIRROR_METHOD_COPY && write_zeroes_ok)) { io_bytes_acct = 0; } else { io_bytes_acct = io_bytes; @@ -847,8 +887,10 @@ static int coroutine_fn GRAPH_UNLOCKED mirror_dirty_init(MirrorBlockJob *s) bool punch_holes = target_bs->detect_zeroes == BLOCKDEV_DETECT_ZEROES_OPTIONS_UNMAP && bdrv_can_write_zeroes_with_unmap(target_bs); + int64_t bitmap_length = DIV_ROUND_UP(s->bdev_length, s->granularity); /* Determine if the image is already zero, regardless of sync mode. */ + s->zero_bitmap = bitmap_new(bitmap_length); bdrv_graph_co_rdlock(); bs = s->mirror_top_bs->backing->bs; if (s->target_is_zero) { @@ -862,7 +904,14 @@ static int coroutine_fn GRAPH_UNLOCKED mirror_dirty_init(MirrorBlockJob *s) if (ret < 0) { return ret; } else if (s->sync_mode == MIRROR_SYNC_MODE_TOP) { - /* In TOP mode, there is no benefit to a pre-zeroing pass. */ + /* + * In TOP mode, there is no benefit to a pre-zeroing pass, but + * the zero bitmap can be set if the destination already reads + * as zero and we are not punching holes. + */ + if (ret > 0 && !punch_holes) { + bitmap_set(s->zero_bitmap, 0, bitmap_length); + } } else if (ret == 0 || punch_holes) { /* * Here, we are in FULL mode; our goal is to avoid writing @@ -871,8 +920,9 @@ static int coroutine_fn GRAPH_UNLOCKED mirror_dirty_init(MirrorBlockJob *s) * zeroing happened externally (ret > 0) or if we have a fast * way to pre-zero the image (the dirty bitmap will be * populated later by the non-zero portions, the same as for - * TOP mode). If pre-zeroing is not fast, or we need to punch - * holes, then our only recourse is to write the entire image. + * TOP mode). If pre-zeroing is not fast, then our only + * recourse is to mark the entire image dirty. The act of + * pre-zeroing will populate the zero bitmap. */ if (!bdrv_can_write_zeroes_with_unmap(target_bs)) { bdrv_set_dirty_bitmap(s->dirty_bitmap, 0, s->bdev_length); @@ -883,6 +933,7 @@ static int coroutine_fn GRAPH_UNLOCKED mirror_dirty_init(MirrorBlockJob *s) for (offset = 0; offset < s->bdev_length; ) { int bytes = MIN(s->bdev_length - offset, QEMU_ALIGN_DOWN(INT_MAX, s->granularity)); + bool ignored; mirror_throttle(s); @@ -898,12 +949,15 @@ static int coroutine_fn GRAPH_UNLOCKED mirror_dirty_init(MirrorBlockJob *s) continue; } - mirror_perform(s, offset, bytes, MIRROR_METHOD_ZERO); + mirror_perform(s, offset, bytes, MIRROR_METHOD_ZERO, &ignored); offset += bytes; } mirror_wait_for_all_io(s); s->initial_zeroing_ongoing = false; + } else { + /* In FULL mode, and image already reads as zero. */ + bitmap_set(s->zero_bitmap, 0, bitmap_length); } /* First part, loop on the sectors and initialize the dirty bitmap. */ @@ -1188,6 +1242,7 @@ immediate_exit: assert(s->in_flight == 0); qemu_vfree(s->buf); g_free(s->cow_bitmap); + g_free(s->zero_bitmap); g_free(s->in_flight_bitmap); bdrv_dirty_iter_free(s->dbi); @@ -1367,6 +1422,7 @@ do_sync_target_write(MirrorBlockJob *job, MirrorMethod method, int ret; size_t qiov_offset = 0; int64_t dirty_bitmap_offset, dirty_bitmap_end; + int64_t zero_bitmap_offset, zero_bitmap_end; if (!QEMU_IS_ALIGNED(offset, job->granularity) && bdrv_dirty_bitmap_get(job->dirty_bitmap, offset)) @@ -1410,8 +1466,9 @@ do_sync_target_write(MirrorBlockJob *job, MirrorMethod method, } /* - * Tails are either clean or shrunk, so for bitmap resetting - * we safely align the range down. + * Tails are either clean or shrunk, so for dirty bitmap resetting + * we safely align the range narrower. But for zero bitmap, round + * range wider for checking or clearing, and narrower for setting. */ dirty_bitmap_offset = QEMU_ALIGN_UP(offset, job->granularity); dirty_bitmap_end = QEMU_ALIGN_DOWN(offset + bytes, job->granularity); @@ -1419,22 +1476,44 @@ do_sync_target_write(MirrorBlockJob *job, MirrorMethod method, bdrv_reset_dirty_bitmap(job->dirty_bitmap, dirty_bitmap_offset, dirty_bitmap_end - dirty_bitmap_offset); } + zero_bitmap_offset = offset / job->granularity; + zero_bitmap_end = DIV_ROUND_UP(offset + bytes, job->granularity); job_progress_increase_remaining(&job->common.job, bytes); job->active_write_bytes_in_flight += bytes; switch (method) { case MIRROR_METHOD_COPY: + if (job->zero_bitmap) { + bitmap_clear(job->zero_bitmap, zero_bitmap_offset, + zero_bitmap_end - zero_bitmap_offset); + } ret = blk_co_pwritev_part(job->target, offset, bytes, qiov, qiov_offset, flags); break; case MIRROR_METHOD_ZERO: + if (job->zero_bitmap) { + if (find_next_zero_bit(job->zero_bitmap, zero_bitmap_end, + zero_bitmap_offset) == zero_bitmap_end) { + ret = 0; + break; + } + } assert(!qiov); ret = blk_co_pwrite_zeroes(job->target, offset, bytes, flags); + if (job->zero_bitmap && ret >= 0) { + bitmap_set(job->zero_bitmap, dirty_bitmap_offset / job->granularity, + (dirty_bitmap_end - dirty_bitmap_offset) / + job->granularity); + } break; case MIRROR_METHOD_DISCARD: + if (job->zero_bitmap) { + bitmap_clear(job->zero_bitmap, zero_bitmap_offset, + zero_bitmap_end - zero_bitmap_offset); + } assert(!qiov); ret = blk_co_pdiscard(job->target, offset, bytes); break;