diff options
| -rw-r--r-- | block/block-copy.c | 129 |
1 files changed, 105 insertions, 24 deletions
diff --git a/block/block-copy.c b/block/block-copy.c index 8b91fa0b06..44a64a94c8 100644 --- a/block/block-copy.c +++ b/block/block-copy.c @@ -39,29 +39,72 @@ static BlockCopyInFlightReq *find_conflicting_inflight_req(BlockCopyState *s, return NULL; } -static void coroutine_fn block_copy_wait_inflight_reqs(BlockCopyState *s, - int64_t offset, - int64_t bytes) +/* + * If there are no intersecting requests return false. Otherwise, wait for the + * first found intersecting request to finish and return true. + */ +static bool coroutine_fn block_copy_wait_one(BlockCopyState *s, int64_t offset, + int64_t bytes) { - BlockCopyInFlightReq *req; + BlockCopyInFlightReq *req = find_conflicting_inflight_req(s, offset, bytes); - while ((req = find_conflicting_inflight_req(s, offset, bytes))) { - qemu_co_queue_wait(&req->wait_queue, NULL); + if (!req) { + return false; } + + qemu_co_queue_wait(&req->wait_queue, NULL); + + return true; } +/* Called only on full-dirty region */ static void block_copy_inflight_req_begin(BlockCopyState *s, BlockCopyInFlightReq *req, int64_t offset, int64_t bytes) { + assert(!find_conflicting_inflight_req(s, offset, bytes)); + + bdrv_reset_dirty_bitmap(s->copy_bitmap, offset, bytes); + s->in_flight_bytes += bytes; + req->offset = offset; req->bytes = bytes; qemu_co_queue_init(&req->wait_queue); QLIST_INSERT_HEAD(&s->inflight_reqs, req, list); } -static void coroutine_fn block_copy_inflight_req_end(BlockCopyInFlightReq *req) +/* + * block_copy_inflight_req_shrink + * + * Drop the tail of the request to be handled later. Set dirty bits back and + * wake up all requests waiting for us (may be some of them are not intersecting + * with shrunk request) + */ +static void coroutine_fn block_copy_inflight_req_shrink(BlockCopyState *s, + BlockCopyInFlightReq *req, int64_t new_bytes) { + if (new_bytes == req->bytes) { + return; + } + + assert(new_bytes > 0 && new_bytes < req->bytes); + + s->in_flight_bytes -= req->bytes - new_bytes; + bdrv_set_dirty_bitmap(s->copy_bitmap, + req->offset + new_bytes, req->bytes - new_bytes); + + req->bytes = new_bytes; + qemu_co_queue_restart_all(&req->wait_queue); +} + +static void coroutine_fn block_copy_inflight_req_end(BlockCopyState *s, + BlockCopyInFlightReq *req, + int ret) +{ + s->in_flight_bytes -= req->bytes; + if (ret < 0) { + bdrv_set_dirty_bitmap(s->copy_bitmap, req->offset, req->bytes); + } QLIST_REMOVE(req, list); qemu_co_queue_restart_all(&req->wait_queue); } @@ -357,12 +400,19 @@ int64_t block_copy_reset_unallocated(BlockCopyState *s, return ret; } -int coroutine_fn block_copy(BlockCopyState *s, - int64_t offset, int64_t bytes, - bool *error_is_read) +/* + * block_copy_dirty_clusters + * + * Copy dirty clusters in @offset/@bytes range. + * Returns 1 if dirty clusters found and successfully copied, 0 if no dirty + * clusters found and -errno on failure. + */ +static int coroutine_fn block_copy_dirty_clusters(BlockCopyState *s, + int64_t offset, int64_t bytes, + bool *error_is_read) { int ret = 0; - BlockCopyInFlightReq req; + bool found_dirty = false; /* * block_copy() user is responsible for keeping source and target in same @@ -374,10 +424,8 @@ int coroutine_fn block_copy(BlockCopyState *s, assert(QEMU_IS_ALIGNED(offset, s->cluster_size)); assert(QEMU_IS_ALIGNED(bytes, s->cluster_size)); - block_copy_wait_inflight_reqs(s, offset, bytes); - block_copy_inflight_req_begin(s, &req, offset, bytes); - while (bytes) { + BlockCopyInFlightReq req; int64_t next_zero, cur_bytes, status_bytes; if (!bdrv_dirty_bitmap_get(s->copy_bitmap, offset)) { @@ -387,6 +435,8 @@ int coroutine_fn block_copy(BlockCopyState *s, continue; /* already copied */ } + found_dirty = true; + cur_bytes = MIN(bytes, s->copy_size); next_zero = bdrv_dirty_bitmap_next_zero(s->copy_bitmap, offset, @@ -396,10 +446,14 @@ int coroutine_fn block_copy(BlockCopyState *s, assert(next_zero < offset + cur_bytes); /* no need to do MIN() */ cur_bytes = next_zero - offset; } + block_copy_inflight_req_begin(s, &req, offset, cur_bytes); ret = block_copy_block_status(s, offset, cur_bytes, &status_bytes); + assert(ret >= 0); /* never fail */ + cur_bytes = MIN(cur_bytes, status_bytes); + block_copy_inflight_req_shrink(s, &req, cur_bytes); if (s->skip_unallocated && !(ret & BDRV_BLOCK_ALLOCATED)) { - bdrv_reset_dirty_bitmap(s->copy_bitmap, offset, status_bytes); + block_copy_inflight_req_end(s, &req, 0); progress_set_remaining(s->progress, bdrv_get_dirty_count(s->copy_bitmap) + s->in_flight_bytes); @@ -409,21 +463,15 @@ int coroutine_fn block_copy(BlockCopyState *s, continue; } - cur_bytes = MIN(cur_bytes, status_bytes); - trace_block_copy_process(s, offset); - bdrv_reset_dirty_bitmap(s->copy_bitmap, offset, cur_bytes); - s->in_flight_bytes += cur_bytes; - co_get_from_shres(s->mem, cur_bytes); ret = block_copy_do_copy(s, offset, cur_bytes, ret & BDRV_BLOCK_ZERO, error_is_read); co_put_to_shres(s->mem, cur_bytes); - s->in_flight_bytes -= cur_bytes; + block_copy_inflight_req_end(s, &req, ret); if (ret < 0) { - bdrv_set_dirty_bitmap(s->copy_bitmap, offset, cur_bytes); - break; + return ret; } progress_work_done(s->progress, cur_bytes); @@ -432,7 +480,40 @@ int coroutine_fn block_copy(BlockCopyState *s, bytes -= cur_bytes; } - block_copy_inflight_req_end(&req); + return found_dirty; +} + +/* + * block_copy + * + * Copy requested region, accordingly to dirty bitmap. + * Collaborate with parallel block_copy requests: if they succeed it will help + * us. If they fail, we will retry not-copied regions. So, if we return error, + * it means that some I/O operation failed in context of _this_ block_copy call, + * not some parallel operation. + */ +int coroutine_fn block_copy(BlockCopyState *s, int64_t offset, int64_t bytes, + bool *error_is_read) +{ + int ret; + + do { + ret = block_copy_dirty_clusters(s, offset, bytes, error_is_read); + + if (ret == 0) { + ret = block_copy_wait_one(s, offset, bytes); + } + + /* + * We retry in two cases: + * 1. Some progress done + * Something was copied, which means that there were yield points + * and some new dirty bits may have appeared (due to failed parallel + * block-copy requests). + * 2. We have waited for some intersecting block-copy request + * It may have failed and produced new dirty bits. + */ + } while (ret > 0); return ret; } |