| /* |
| * QEMU backup |
| * |
| * Copyright (C) 2013 Proxmox Server Solutions |
| * |
| * Authors: |
| * Dietmar Maurer (dietmar@proxmox.com) |
| * |
| * This work is licensed under the terms of the GNU GPL, version 2 or later. |
| * See the COPYING file in the top-level directory. |
| * |
| */ |
| |
| #include "qemu/osdep.h" |
| |
| #include "trace.h" |
| #include "block/block.h" |
| #include "block/block_int.h" |
| #include "block/blockjob.h" |
| #include "qapi/error.h" |
| #include "qapi/qmp/qerror.h" |
| #include "qemu/ratelimit.h" |
| #include "qemu/cutils.h" |
| #include "sysemu/block-backend.h" |
| #include "qemu/bitmap.h" |
| |
| #define BACKUP_CLUSTER_SIZE_DEFAULT (1 << 16) |
| #define SLICE_TIME 100000000ULL /* ns */ |
| |
| typedef struct CowRequest { |
| int64_t start; |
| int64_t end; |
| QLIST_ENTRY(CowRequest) list; |
| CoQueue wait_queue; /* coroutines blocked on this request */ |
| } CowRequest; |
| |
| typedef struct BackupBlockJob { |
| BlockJob common; |
| BlockBackend *target; |
| /* bitmap for sync=incremental */ |
| BdrvDirtyBitmap *sync_bitmap; |
| MirrorSyncMode sync_mode; |
| RateLimit limit; |
| BlockdevOnError on_source_error; |
| BlockdevOnError on_target_error; |
| CoRwlock flush_rwlock; |
| uint64_t sectors_read; |
| unsigned long *done_bitmap; |
| int64_t cluster_size; |
| NotifierWithReturn before_write; |
| QLIST_HEAD(, CowRequest) inflight_reqs; |
| } BackupBlockJob; |
| |
| /* Size of a cluster in sectors, instead of bytes. */ |
| static inline int64_t cluster_size_sectors(BackupBlockJob *job) |
| { |
| return job->cluster_size / BDRV_SECTOR_SIZE; |
| } |
| |
| /* See if in-flight requests overlap and wait for them to complete */ |
| static void coroutine_fn wait_for_overlapping_requests(BackupBlockJob *job, |
| int64_t start, |
| int64_t end) |
| { |
| CowRequest *req; |
| bool retry; |
| |
| do { |
| retry = false; |
| QLIST_FOREACH(req, &job->inflight_reqs, list) { |
| if (end > req->start && start < req->end) { |
| qemu_co_queue_wait(&req->wait_queue); |
| retry = true; |
| break; |
| } |
| } |
| } while (retry); |
| } |
| |
| /* Keep track of an in-flight request */ |
| static void cow_request_begin(CowRequest *req, BackupBlockJob *job, |
| int64_t start, int64_t end) |
| { |
| req->start = start; |
| req->end = end; |
| qemu_co_queue_init(&req->wait_queue); |
| QLIST_INSERT_HEAD(&job->inflight_reqs, req, list); |
| } |
| |
| /* Forget about a completed request */ |
| static void cow_request_end(CowRequest *req) |
| { |
| QLIST_REMOVE(req, list); |
| qemu_co_queue_restart_all(&req->wait_queue); |
| } |
| |
| static int coroutine_fn backup_do_cow(BackupBlockJob *job, |
| int64_t sector_num, int nb_sectors, |
| bool *error_is_read, |
| bool is_write_notifier) |
| { |
| BlockBackend *blk = job->common.blk; |
| CowRequest cow_request; |
| struct iovec iov; |
| QEMUIOVector bounce_qiov; |
| void *bounce_buffer = NULL; |
| int ret = 0; |
| int64_t sectors_per_cluster = cluster_size_sectors(job); |
| int64_t start, end; |
| int n; |
| |
| qemu_co_rwlock_rdlock(&job->flush_rwlock); |
| |
| start = sector_num / sectors_per_cluster; |
| end = DIV_ROUND_UP(sector_num + nb_sectors, sectors_per_cluster); |
| |
| trace_backup_do_cow_enter(job, start, sector_num, nb_sectors); |
| |
| wait_for_overlapping_requests(job, start, end); |
| cow_request_begin(&cow_request, job, start, end); |
| |
| for (; start < end; start++) { |
| if (test_bit(start, job->done_bitmap)) { |
| trace_backup_do_cow_skip(job, start); |
| continue; /* already copied */ |
| } |
| |
| trace_backup_do_cow_process(job, start); |
| |
| n = MIN(sectors_per_cluster, |
| job->common.len / BDRV_SECTOR_SIZE - |
| start * sectors_per_cluster); |
| |
| if (!bounce_buffer) { |
| bounce_buffer = blk_blockalign(blk, job->cluster_size); |
| } |
| iov.iov_base = bounce_buffer; |
| iov.iov_len = n * BDRV_SECTOR_SIZE; |
| qemu_iovec_init_external(&bounce_qiov, &iov, 1); |
| |
| ret = blk_co_preadv(blk, start * job->cluster_size, |
| bounce_qiov.size, &bounce_qiov, |
| is_write_notifier ? BDRV_REQ_NO_SERIALISING : 0); |
| if (ret < 0) { |
| trace_backup_do_cow_read_fail(job, start, ret); |
| if (error_is_read) { |
| *error_is_read = true; |
| } |
| goto out; |
| } |
| |
| if (buffer_is_zero(iov.iov_base, iov.iov_len)) { |
| ret = blk_co_pwrite_zeroes(job->target, start * job->cluster_size, |
| bounce_qiov.size, BDRV_REQ_MAY_UNMAP); |
| } else { |
| ret = blk_co_pwritev(job->target, start * job->cluster_size, |
| bounce_qiov.size, &bounce_qiov, 0); |
| } |
| if (ret < 0) { |
| trace_backup_do_cow_write_fail(job, start, ret); |
| if (error_is_read) { |
| *error_is_read = false; |
| } |
| goto out; |
| } |
| |
| set_bit(start, job->done_bitmap); |
| |
| /* Publish progress, guest I/O counts as progress too. Note that the |
| * offset field is an opaque progress value, it is not a disk offset. |
| */ |
| job->sectors_read += n; |
| job->common.offset += n * BDRV_SECTOR_SIZE; |
| } |
| |
| out: |
| if (bounce_buffer) { |
| qemu_vfree(bounce_buffer); |
| } |
| |
| cow_request_end(&cow_request); |
| |
| trace_backup_do_cow_return(job, sector_num, nb_sectors, ret); |
| |
| qemu_co_rwlock_unlock(&job->flush_rwlock); |
| |
| return ret; |
| } |
| |
| static int coroutine_fn backup_before_write_notify( |
| NotifierWithReturn *notifier, |
| void *opaque) |
| { |
| BackupBlockJob *job = container_of(notifier, BackupBlockJob, before_write); |
| BdrvTrackedRequest *req = opaque; |
| int64_t sector_num = req->offset >> BDRV_SECTOR_BITS; |
| int nb_sectors = req->bytes >> BDRV_SECTOR_BITS; |
| |
| assert(req->bs == blk_bs(job->common.blk)); |
| assert((req->offset & (BDRV_SECTOR_SIZE - 1)) == 0); |
| assert((req->bytes & (BDRV_SECTOR_SIZE - 1)) == 0); |
| |
| return backup_do_cow(job, sector_num, nb_sectors, NULL, true); |
| } |
| |
| static void backup_set_speed(BlockJob *job, int64_t speed, Error **errp) |
| { |
| BackupBlockJob *s = container_of(job, BackupBlockJob, common); |
| |
| if (speed < 0) { |
| error_setg(errp, QERR_INVALID_PARAMETER, "speed"); |
| return; |
| } |
| ratelimit_set_speed(&s->limit, speed / BDRV_SECTOR_SIZE, SLICE_TIME); |
| } |
| |
| static void backup_cleanup_sync_bitmap(BackupBlockJob *job, int ret) |
| { |
| BdrvDirtyBitmap *bm; |
| BlockDriverState *bs = blk_bs(job->common.blk); |
| |
| if (ret < 0 || block_job_is_cancelled(&job->common)) { |
| /* Merge the successor back into the parent, delete nothing. */ |
| bm = bdrv_reclaim_dirty_bitmap(bs, job->sync_bitmap, NULL); |
| assert(bm); |
| } else { |
| /* Everything is fine, delete this bitmap and install the backup. */ |
| bm = bdrv_dirty_bitmap_abdicate(bs, job->sync_bitmap, NULL); |
| assert(bm); |
| } |
| } |
| |
| static void backup_commit(BlockJob *job) |
| { |
| BackupBlockJob *s = container_of(job, BackupBlockJob, common); |
| if (s->sync_bitmap) { |
| backup_cleanup_sync_bitmap(s, 0); |
| } |
| } |
| |
| static void backup_abort(BlockJob *job) |
| { |
| BackupBlockJob *s = container_of(job, BackupBlockJob, common); |
| if (s->sync_bitmap) { |
| backup_cleanup_sync_bitmap(s, -1); |
| } |
| } |
| |
| static void backup_attached_aio_context(BlockJob *job, AioContext *aio_context) |
| { |
| BackupBlockJob *s = container_of(job, BackupBlockJob, common); |
| |
| blk_set_aio_context(s->target, aio_context); |
| } |
| |
| static const BlockJobDriver backup_job_driver = { |
| .instance_size = sizeof(BackupBlockJob), |
| .job_type = BLOCK_JOB_TYPE_BACKUP, |
| .set_speed = backup_set_speed, |
| .commit = backup_commit, |
| .abort = backup_abort, |
| .attached_aio_context = backup_attached_aio_context, |
| }; |
| |
| static BlockErrorAction backup_error_action(BackupBlockJob *job, |
| bool read, int error) |
| { |
| if (read) { |
| return block_job_error_action(&job->common, job->on_source_error, |
| true, error); |
| } else { |
| return block_job_error_action(&job->common, job->on_target_error, |
| false, error); |
| } |
| } |
| |
| typedef struct { |
| int ret; |
| } BackupCompleteData; |
| |
| static void backup_complete(BlockJob *job, void *opaque) |
| { |
| BackupBlockJob *s = container_of(job, BackupBlockJob, common); |
| BackupCompleteData *data = opaque; |
| |
| blk_unref(s->target); |
| |
| block_job_completed(job, data->ret); |
| g_free(data); |
| } |
| |
| static bool coroutine_fn yield_and_check(BackupBlockJob *job) |
| { |
| if (block_job_is_cancelled(&job->common)) { |
| return true; |
| } |
| |
| /* we need to yield so that bdrv_drain_all() returns. |
| * (without, VM does not reboot) |
| */ |
| if (job->common.speed) { |
| uint64_t delay_ns = ratelimit_calculate_delay(&job->limit, |
| job->sectors_read); |
| job->sectors_read = 0; |
| block_job_sleep_ns(&job->common, QEMU_CLOCK_REALTIME, delay_ns); |
| } else { |
| block_job_sleep_ns(&job->common, QEMU_CLOCK_REALTIME, 0); |
| } |
| |
| if (block_job_is_cancelled(&job->common)) { |
| return true; |
| } |
| |
| return false; |
| } |
| |
| static int coroutine_fn backup_run_incremental(BackupBlockJob *job) |
| { |
| bool error_is_read; |
| int ret = 0; |
| int clusters_per_iter; |
| uint32_t granularity; |
| int64_t sector; |
| int64_t cluster; |
| int64_t end; |
| int64_t last_cluster = -1; |
| int64_t sectors_per_cluster = cluster_size_sectors(job); |
| HBitmapIter hbi; |
| |
| granularity = bdrv_dirty_bitmap_granularity(job->sync_bitmap); |
| clusters_per_iter = MAX((granularity / job->cluster_size), 1); |
| bdrv_dirty_iter_init(job->sync_bitmap, &hbi); |
| |
| /* Find the next dirty sector(s) */ |
| while ((sector = hbitmap_iter_next(&hbi)) != -1) { |
| cluster = sector / sectors_per_cluster; |
| |
| /* Fake progress updates for any clusters we skipped */ |
| if (cluster != last_cluster + 1) { |
| job->common.offset += ((cluster - last_cluster - 1) * |
| job->cluster_size); |
| } |
| |
| for (end = cluster + clusters_per_iter; cluster < end; cluster++) { |
| do { |
| if (yield_and_check(job)) { |
| return ret; |
| } |
| ret = backup_do_cow(job, cluster * sectors_per_cluster, |
| sectors_per_cluster, &error_is_read, |
| false); |
| if ((ret < 0) && |
| backup_error_action(job, error_is_read, -ret) == |
| BLOCK_ERROR_ACTION_REPORT) { |
| return ret; |
| } |
| } while (ret < 0); |
| } |
| |
| /* If the bitmap granularity is smaller than the backup granularity, |
| * we need to advance the iterator pointer to the next cluster. */ |
| if (granularity < job->cluster_size) { |
| bdrv_set_dirty_iter(&hbi, cluster * sectors_per_cluster); |
| } |
| |
| last_cluster = cluster - 1; |
| } |
| |
| /* Play some final catchup with the progress meter */ |
| end = DIV_ROUND_UP(job->common.len, job->cluster_size); |
| if (last_cluster + 1 < end) { |
| job->common.offset += ((end - last_cluster - 1) * job->cluster_size); |
| } |
| |
| return ret; |
| } |
| |
| static void coroutine_fn backup_run(void *opaque) |
| { |
| BackupBlockJob *job = opaque; |
| BackupCompleteData *data; |
| BlockDriverState *bs = blk_bs(job->common.blk); |
| BlockBackend *target = job->target; |
| int64_t start, end; |
| int64_t sectors_per_cluster = cluster_size_sectors(job); |
| int ret = 0; |
| |
| QLIST_INIT(&job->inflight_reqs); |
| qemu_co_rwlock_init(&job->flush_rwlock); |
| |
| start = 0; |
| end = DIV_ROUND_UP(job->common.len, job->cluster_size); |
| |
| job->done_bitmap = bitmap_new(end); |
| |
| job->before_write.notify = backup_before_write_notify; |
| bdrv_add_before_write_notifier(bs, &job->before_write); |
| |
| if (job->sync_mode == MIRROR_SYNC_MODE_NONE) { |
| while (!block_job_is_cancelled(&job->common)) { |
| /* Yield until the job is cancelled. We just let our before_write |
| * notify callback service CoW requests. */ |
| block_job_yield(&job->common); |
| } |
| } else if (job->sync_mode == MIRROR_SYNC_MODE_INCREMENTAL) { |
| ret = backup_run_incremental(job); |
| } else { |
| /* Both FULL and TOP SYNC_MODE's require copying.. */ |
| for (; start < end; start++) { |
| bool error_is_read; |
| if (yield_and_check(job)) { |
| break; |
| } |
| |
| if (job->sync_mode == MIRROR_SYNC_MODE_TOP) { |
| int i, n; |
| int alloced = 0; |
| |
| /* Check to see if these blocks are already in the |
| * backing file. */ |
| |
| for (i = 0; i < sectors_per_cluster;) { |
| /* bdrv_is_allocated() only returns true/false based |
| * on the first set of sectors it comes across that |
| * are are all in the same state. |
| * For that reason we must verify each sector in the |
| * backup cluster length. We end up copying more than |
| * needed but at some point that is always the case. */ |
| alloced = |
| bdrv_is_allocated(bs, |
| start * sectors_per_cluster + i, |
| sectors_per_cluster - i, &n); |
| i += n; |
| |
| if (alloced == 1 || n == 0) { |
| break; |
| } |
| } |
| |
| /* If the above loop never found any sectors that are in |
| * the topmost image, skip this backup. */ |
| if (alloced == 0) { |
| continue; |
| } |
| } |
| /* FULL sync mode we copy the whole drive. */ |
| ret = backup_do_cow(job, start * sectors_per_cluster, |
| sectors_per_cluster, &error_is_read, false); |
| if (ret < 0) { |
| /* Depending on error action, fail now or retry cluster */ |
| BlockErrorAction action = |
| backup_error_action(job, error_is_read, -ret); |
| if (action == BLOCK_ERROR_ACTION_REPORT) { |
| break; |
| } else { |
| start--; |
| continue; |
| } |
| } |
| } |
| } |
| |
| notifier_with_return_remove(&job->before_write); |
| |
| /* wait until pending backup_do_cow() calls have completed */ |
| qemu_co_rwlock_wrlock(&job->flush_rwlock); |
| qemu_co_rwlock_unlock(&job->flush_rwlock); |
| g_free(job->done_bitmap); |
| |
| bdrv_op_unblock_all(blk_bs(target), job->common.blocker); |
| |
| data = g_malloc(sizeof(*data)); |
| data->ret = ret; |
| block_job_defer_to_main_loop(&job->common, backup_complete, data); |
| } |
| |
| void backup_start(const char *job_id, BlockDriverState *bs, |
| BlockDriverState *target, int64_t speed, |
| MirrorSyncMode sync_mode, BdrvDirtyBitmap *sync_bitmap, |
| BlockdevOnError on_source_error, |
| BlockdevOnError on_target_error, |
| BlockCompletionFunc *cb, void *opaque, |
| BlockJobTxn *txn, Error **errp) |
| { |
| int64_t len; |
| BlockDriverInfo bdi; |
| BackupBlockJob *job = NULL; |
| int ret; |
| |
| assert(bs); |
| assert(target); |
| |
| if (bs == target) { |
| error_setg(errp, "Source and target cannot be the same"); |
| return; |
| } |
| |
| if (!bdrv_is_inserted(bs)) { |
| error_setg(errp, "Device is not inserted: %s", |
| bdrv_get_device_name(bs)); |
| return; |
| } |
| |
| if (!bdrv_is_inserted(target)) { |
| error_setg(errp, "Device is not inserted: %s", |
| bdrv_get_device_name(target)); |
| return; |
| } |
| |
| if (bdrv_op_is_blocked(bs, BLOCK_OP_TYPE_BACKUP_SOURCE, errp)) { |
| return; |
| } |
| |
| if (bdrv_op_is_blocked(target, BLOCK_OP_TYPE_BACKUP_TARGET, errp)) { |
| return; |
| } |
| |
| if (sync_mode == MIRROR_SYNC_MODE_INCREMENTAL) { |
| if (!sync_bitmap) { |
| error_setg(errp, "must provide a valid bitmap name for " |
| "\"incremental\" sync mode"); |
| return; |
| } |
| |
| /* Create a new bitmap, and freeze/disable this one. */ |
| if (bdrv_dirty_bitmap_create_successor(bs, sync_bitmap, errp) < 0) { |
| return; |
| } |
| } else if (sync_bitmap) { |
| error_setg(errp, |
| "a sync_bitmap was provided to backup_run, " |
| "but received an incompatible sync_mode (%s)", |
| MirrorSyncMode_lookup[sync_mode]); |
| return; |
| } |
| |
| len = bdrv_getlength(bs); |
| if (len < 0) { |
| error_setg_errno(errp, -len, "unable to get length for '%s'", |
| bdrv_get_device_name(bs)); |
| goto error; |
| } |
| |
| job = block_job_create(job_id, &backup_job_driver, bs, speed, |
| cb, opaque, errp); |
| if (!job) { |
| goto error; |
| } |
| |
| job->target = blk_new(); |
| blk_insert_bs(job->target, target); |
| |
| job->on_source_error = on_source_error; |
| job->on_target_error = on_target_error; |
| job->sync_mode = sync_mode; |
| job->sync_bitmap = sync_mode == MIRROR_SYNC_MODE_INCREMENTAL ? |
| sync_bitmap : NULL; |
| |
| /* If there is no backing file on the target, we cannot rely on COW if our |
| * backup cluster size is smaller than the target cluster size. Even for |
| * targets with a backing file, try to avoid COW if possible. */ |
| ret = bdrv_get_info(target, &bdi); |
| if (ret < 0 && !target->backing) { |
| error_setg_errno(errp, -ret, |
| "Couldn't determine the cluster size of the target image, " |
| "which has no backing file"); |
| error_append_hint(errp, |
| "Aborting, since this may create an unusable destination image\n"); |
| goto error; |
| } else if (ret < 0 && target->backing) { |
| /* Not fatal; just trudge on ahead. */ |
| job->cluster_size = BACKUP_CLUSTER_SIZE_DEFAULT; |
| } else { |
| job->cluster_size = MAX(BACKUP_CLUSTER_SIZE_DEFAULT, bdi.cluster_size); |
| } |
| |
| bdrv_op_block_all(target, job->common.blocker); |
| job->common.len = len; |
| job->common.co = qemu_coroutine_create(backup_run, job); |
| block_job_txn_add_job(txn, &job->common); |
| qemu_coroutine_enter(job->common.co); |
| return; |
| |
| error: |
| if (sync_bitmap) { |
| bdrv_reclaim_dirty_bitmap(bs, sync_bitmap, NULL); |
| } |
| if (job) { |
| blk_unref(job->target); |
| block_job_unref(&job->common); |
| } |
| } |
