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14#include "qemu/osdep.h"
15
16#include "trace.h"
17#include "block/block.h"
18#include "block/block_int.h"
19#include "block/blockjob_int.h"
20#include "block/block_backup.h"
21#include "qapi/error.h"
22#include "qapi/qmp/qerror.h"
23#include "qemu/ratelimit.h"
24#include "qemu/cutils.h"
25#include "sysemu/block-backend.h"
26#include "qemu/bitmap.h"
27#include "qemu/error-report.h"
28
29#define BACKUP_CLUSTER_SIZE_DEFAULT (1 << 16)
30
31typedef struct CowRequest {
32 int64_t start_byte;
33 int64_t end_byte;
34 QLIST_ENTRY(CowRequest) list;
35 CoQueue wait_queue;
36} CowRequest;
37
38typedef struct BackupBlockJob {
39 BlockJob common;
40 BlockBackend *target;
41
42 BdrvDirtyBitmap *sync_bitmap;
43 MirrorSyncMode sync_mode;
44 BlockdevOnError on_source_error;
45 BlockdevOnError on_target_error;
46 CoRwlock flush_rwlock;
47 uint64_t len;
48 uint64_t bytes_read;
49 int64_t cluster_size;
50 bool compress;
51 NotifierWithReturn before_write;
52 QLIST_HEAD(, CowRequest) inflight_reqs;
53
54 HBitmap *copy_bitmap;
55 bool use_copy_range;
56 int64_t copy_range_size;
57
58 bool serialize_target_writes;
59} BackupBlockJob;
60
61static const BlockJobDriver backup_job_driver;
62
63
64static void coroutine_fn wait_for_overlapping_requests(BackupBlockJob *job,
65 int64_t start,
66 int64_t end)
67{
68 CowRequest *req;
69 bool retry;
70
71 do {
72 retry = false;
73 QLIST_FOREACH(req, &job->inflight_reqs, list) {
74 if (end > req->start_byte && start < req->end_byte) {
75 qemu_co_queue_wait(&req->wait_queue, NULL);
76 retry = true;
77 break;
78 }
79 }
80 } while (retry);
81}
82
83
84static void cow_request_begin(CowRequest *req, BackupBlockJob *job,
85 int64_t start, int64_t end)
86{
87 req->start_byte = start;
88 req->end_byte = end;
89 qemu_co_queue_init(&req->wait_queue);
90 QLIST_INSERT_HEAD(&job->inflight_reqs, req, list);
91}
92
93
94static void cow_request_end(CowRequest *req)
95{
96 QLIST_REMOVE(req, list);
97 qemu_co_queue_restart_all(&req->wait_queue);
98}
99
100
101
102static int coroutine_fn backup_cow_with_bounce_buffer(BackupBlockJob *job,
103 int64_t start,
104 int64_t end,
105 bool is_write_notifier,
106 bool *error_is_read,
107 void **bounce_buffer)
108{
109 int ret;
110 BlockBackend *blk = job->common.blk;
111 int nbytes;
112 int read_flags = is_write_notifier ? BDRV_REQ_NO_SERIALISING : 0;
113 int write_flags = job->serialize_target_writes ? BDRV_REQ_SERIALISING : 0;
114
115 assert(QEMU_IS_ALIGNED(start, job->cluster_size));
116 hbitmap_reset(job->copy_bitmap, start, job->cluster_size);
117 nbytes = MIN(job->cluster_size, job->len - start);
118 if (!*bounce_buffer) {
119 *bounce_buffer = blk_blockalign(blk, job->cluster_size);
120 }
121
122 ret = blk_co_pread(blk, start, nbytes, *bounce_buffer, read_flags);
123 if (ret < 0) {
124 trace_backup_do_cow_read_fail(job, start, ret);
125 if (error_is_read) {
126 *error_is_read = true;
127 }
128 goto fail;
129 }
130
131 if (buffer_is_zero(*bounce_buffer, nbytes)) {
132 ret = blk_co_pwrite_zeroes(job->target, start,
133 nbytes, write_flags | BDRV_REQ_MAY_UNMAP);
134 } else {
135 ret = blk_co_pwrite(job->target, start,
136 nbytes, *bounce_buffer, write_flags |
137 (job->compress ? BDRV_REQ_WRITE_COMPRESSED : 0));
138 }
139 if (ret < 0) {
140 trace_backup_do_cow_write_fail(job, start, ret);
141 if (error_is_read) {
142 *error_is_read = false;
143 }
144 goto fail;
145 }
146
147 return nbytes;
148fail:
149 hbitmap_set(job->copy_bitmap, start, job->cluster_size);
150 return ret;
151
152}
153
154
155
156static int coroutine_fn backup_cow_with_offload(BackupBlockJob *job,
157 int64_t start,
158 int64_t end,
159 bool is_write_notifier)
160{
161 int ret;
162 int nr_clusters;
163 BlockBackend *blk = job->common.blk;
164 int nbytes;
165 int read_flags = is_write_notifier ? BDRV_REQ_NO_SERIALISING : 0;
166 int write_flags = job->serialize_target_writes ? BDRV_REQ_SERIALISING : 0;
167
168 assert(QEMU_IS_ALIGNED(job->copy_range_size, job->cluster_size));
169 assert(QEMU_IS_ALIGNED(start, job->cluster_size));
170 nbytes = MIN(job->copy_range_size, MIN(end, job->len) - start);
171 nr_clusters = DIV_ROUND_UP(nbytes, job->cluster_size);
172 hbitmap_reset(job->copy_bitmap, start, job->cluster_size * nr_clusters);
173 ret = blk_co_copy_range(blk, start, job->target, start, nbytes,
174 read_flags, write_flags);
175 if (ret < 0) {
176 trace_backup_do_cow_copy_range_fail(job, start, ret);
177 hbitmap_set(job->copy_bitmap, start, job->cluster_size * nr_clusters);
178 return ret;
179 }
180
181 return nbytes;
182}
183
184static int coroutine_fn backup_do_cow(BackupBlockJob *job,
185 int64_t offset, uint64_t bytes,
186 bool *error_is_read,
187 bool is_write_notifier)
188{
189 CowRequest cow_request;
190 int ret = 0;
191 int64_t start, end;
192 void *bounce_buffer = NULL;
193
194 qemu_co_rwlock_rdlock(&job->flush_rwlock);
195
196 start = QEMU_ALIGN_DOWN(offset, job->cluster_size);
197 end = QEMU_ALIGN_UP(bytes + offset, job->cluster_size);
198
199 trace_backup_do_cow_enter(job, start, offset, bytes);
200
201 wait_for_overlapping_requests(job, start, end);
202 cow_request_begin(&cow_request, job, start, end);
203
204 while (start < end) {
205 int64_t dirty_end;
206
207 if (!hbitmap_get(job->copy_bitmap, start)) {
208 trace_backup_do_cow_skip(job, start);
209 start += job->cluster_size;
210 continue;
211 }
212
213 dirty_end = hbitmap_next_zero(job->copy_bitmap, start, (end - start));
214 if (dirty_end < 0) {
215 dirty_end = end;
216 }
217
218 trace_backup_do_cow_process(job, start);
219
220 if (job->use_copy_range) {
221 ret = backup_cow_with_offload(job, start, dirty_end,
222 is_write_notifier);
223 if (ret < 0) {
224 job->use_copy_range = false;
225 }
226 }
227 if (!job->use_copy_range) {
228 ret = backup_cow_with_bounce_buffer(job, start, dirty_end,
229 is_write_notifier,
230 error_is_read, &bounce_buffer);
231 }
232 if (ret < 0) {
233 break;
234 }
235
236
237
238
239 start += ret;
240 job->bytes_read += ret;
241 job_progress_update(&job->common.job, ret);
242 ret = 0;
243 }
244
245 if (bounce_buffer) {
246 qemu_vfree(bounce_buffer);
247 }
248
249 cow_request_end(&cow_request);
250
251 trace_backup_do_cow_return(job, offset, bytes, ret);
252
253 qemu_co_rwlock_unlock(&job->flush_rwlock);
254
255 return ret;
256}
257
258static int coroutine_fn backup_before_write_notify(
259 NotifierWithReturn *notifier,
260 void *opaque)
261{
262 BackupBlockJob *job = container_of(notifier, BackupBlockJob, before_write);
263 BdrvTrackedRequest *req = opaque;
264
265 assert(req->bs == blk_bs(job->common.blk));
266 assert(QEMU_IS_ALIGNED(req->offset, BDRV_SECTOR_SIZE));
267 assert(QEMU_IS_ALIGNED(req->bytes, BDRV_SECTOR_SIZE));
268
269 return backup_do_cow(job, req->offset, req->bytes, NULL, true);
270}
271
272static void backup_cleanup_sync_bitmap(BackupBlockJob *job, int ret)
273{
274 BdrvDirtyBitmap *bm;
275 BlockDriverState *bs = blk_bs(job->common.blk);
276
277 if (ret < 0) {
278
279 bm = bdrv_reclaim_dirty_bitmap(bs, job->sync_bitmap, NULL);
280 assert(bm);
281 } else {
282
283 bm = bdrv_dirty_bitmap_abdicate(bs, job->sync_bitmap, NULL);
284 assert(bm);
285 }
286}
287
288static void backup_commit(Job *job)
289{
290 BackupBlockJob *s = container_of(job, BackupBlockJob, common.job);
291 if (s->sync_bitmap) {
292 backup_cleanup_sync_bitmap(s, 0);
293 }
294}
295
296static void backup_abort(Job *job)
297{
298 BackupBlockJob *s = container_of(job, BackupBlockJob, common.job);
299 if (s->sync_bitmap) {
300 backup_cleanup_sync_bitmap(s, -1);
301 }
302}
303
304static void backup_clean(Job *job)
305{
306 BackupBlockJob *s = container_of(job, BackupBlockJob, common.job);
307 assert(s->target);
308 blk_unref(s->target);
309 s->target = NULL;
310
311 if (s->copy_bitmap) {
312 hbitmap_free(s->copy_bitmap);
313 s->copy_bitmap = NULL;
314 }
315}
316
317void backup_do_checkpoint(BlockJob *job, Error **errp)
318{
319 BackupBlockJob *backup_job = container_of(job, BackupBlockJob, common);
320
321 assert(block_job_driver(job) == &backup_job_driver);
322
323 if (backup_job->sync_mode != MIRROR_SYNC_MODE_NONE) {
324 error_setg(errp, "The backup job only supports block checkpoint in"
325 " sync=none mode");
326 return;
327 }
328
329 hbitmap_set(backup_job->copy_bitmap, 0, backup_job->len);
330}
331
332static void backup_drain(BlockJob *job)
333{
334 BackupBlockJob *s = container_of(job, BackupBlockJob, common);
335
336
337
338
339 if (s->target) {
340 BlockBackend *target = s->target;
341 blk_ref(target);
342 blk_drain(target);
343 blk_unref(target);
344 }
345}
346
347static BlockErrorAction backup_error_action(BackupBlockJob *job,
348 bool read, int error)
349{
350 if (read) {
351 return block_job_error_action(&job->common, job->on_source_error,
352 true, error);
353 } else {
354 return block_job_error_action(&job->common, job->on_target_error,
355 false, error);
356 }
357}
358
359static bool coroutine_fn yield_and_check(BackupBlockJob *job)
360{
361 uint64_t delay_ns;
362
363 if (job_is_cancelled(&job->common.job)) {
364 return true;
365 }
366
367
368
369 delay_ns = block_job_ratelimit_get_delay(&job->common, job->bytes_read);
370 job->bytes_read = 0;
371 job_sleep_ns(&job->common.job, delay_ns);
372
373 if (job_is_cancelled(&job->common.job)) {
374 return true;
375 }
376
377 return false;
378}
379
380static bool bdrv_is_unallocated_range(BlockDriverState *bs,
381 int64_t offset, int64_t bytes)
382{
383 int64_t end = offset + bytes;
384
385 while (offset < end && !bdrv_is_allocated(bs, offset, bytes, &bytes)) {
386 if (bytes == 0) {
387 return true;
388 }
389 offset += bytes;
390 bytes = end - offset;
391 }
392
393 return offset >= end;
394}
395
396static int coroutine_fn backup_loop(BackupBlockJob *job)
397{
398 int ret;
399 bool error_is_read;
400 int64_t offset;
401 HBitmapIter hbi;
402 BlockDriverState *bs = blk_bs(job->common.blk);
403
404 hbitmap_iter_init(&hbi, job->copy_bitmap, 0);
405 while ((offset = hbitmap_iter_next(&hbi)) != -1) {
406 if (job->sync_mode == MIRROR_SYNC_MODE_TOP &&
407 bdrv_is_unallocated_range(bs, offset, job->cluster_size))
408 {
409 hbitmap_reset(job->copy_bitmap, offset, job->cluster_size);
410 continue;
411 }
412
413 do {
414 if (yield_and_check(job)) {
415 return 0;
416 }
417 ret = backup_do_cow(job, offset,
418 job->cluster_size, &error_is_read, false);
419 if (ret < 0 && backup_error_action(job, error_is_read, -ret) ==
420 BLOCK_ERROR_ACTION_REPORT)
421 {
422 return ret;
423 }
424 } while (ret < 0);
425 }
426
427 return 0;
428}
429
430
431static void backup_incremental_init_copy_bitmap(BackupBlockJob *job)
432{
433 uint64_t offset = 0;
434 uint64_t bytes = job->len;
435
436 while (bdrv_dirty_bitmap_next_dirty_area(job->sync_bitmap,
437 &offset, &bytes))
438 {
439 hbitmap_set(job->copy_bitmap, offset, bytes);
440
441 offset += bytes;
442 if (offset >= job->len) {
443 break;
444 }
445 bytes = job->len - offset;
446 }
447
448
449 job_progress_update(&job->common.job,
450 job->len - hbitmap_count(job->copy_bitmap));
451}
452
453static int coroutine_fn backup_run(Job *job, Error **errp)
454{
455 BackupBlockJob *s = container_of(job, BackupBlockJob, common.job);
456 BlockDriverState *bs = blk_bs(s->common.blk);
457 int ret = 0;
458
459 QLIST_INIT(&s->inflight_reqs);
460 qemu_co_rwlock_init(&s->flush_rwlock);
461
462 job_progress_set_remaining(job, s->len);
463
464 if (s->sync_mode == MIRROR_SYNC_MODE_INCREMENTAL) {
465 backup_incremental_init_copy_bitmap(s);
466 } else {
467 hbitmap_set(s->copy_bitmap, 0, s->len);
468 }
469
470 s->before_write.notify = backup_before_write_notify;
471 bdrv_add_before_write_notifier(bs, &s->before_write);
472
473 if (s->sync_mode == MIRROR_SYNC_MODE_NONE) {
474
475
476 while (!job_is_cancelled(job)) {
477
478
479 job_yield(job);
480 }
481 } else {
482 ret = backup_loop(s);
483 }
484
485 notifier_with_return_remove(&s->before_write);
486
487
488 qemu_co_rwlock_wrlock(&s->flush_rwlock);
489 qemu_co_rwlock_unlock(&s->flush_rwlock);
490
491 return ret;
492}
493
494static const BlockJobDriver backup_job_driver = {
495 .job_driver = {
496 .instance_size = sizeof(BackupBlockJob),
497 .job_type = JOB_TYPE_BACKUP,
498 .free = block_job_free,
499 .user_resume = block_job_user_resume,
500 .drain = block_job_drain,
501 .run = backup_run,
502 .commit = backup_commit,
503 .abort = backup_abort,
504 .clean = backup_clean,
505 },
506 .drain = backup_drain,
507};
508
509static int64_t backup_calculate_cluster_size(BlockDriverState *target,
510 Error **errp)
511{
512 int ret;
513 BlockDriverInfo bdi;
514
515
516
517
518
519
520 ret = bdrv_get_info(target, &bdi);
521 if (ret == -ENOTSUP && !target->backing) {
522
523 warn_report("The target block device doesn't provide "
524 "information about the block size and it doesn't have a "
525 "backing file. The default block size of %u bytes is "
526 "used. If the actual block size of the target exceeds "
527 "this default, the backup may be unusable",
528 BACKUP_CLUSTER_SIZE_DEFAULT);
529 return BACKUP_CLUSTER_SIZE_DEFAULT;
530 } else if (ret < 0 && !target->backing) {
531 error_setg_errno(errp, -ret,
532 "Couldn't determine the cluster size of the target image, "
533 "which has no backing file");
534 error_append_hint(errp,
535 "Aborting, since this may create an unusable destination image\n");
536 return ret;
537 } else if (ret < 0 && target->backing) {
538
539 return BACKUP_CLUSTER_SIZE_DEFAULT;
540 }
541
542 return MAX(BACKUP_CLUSTER_SIZE_DEFAULT, bdi.cluster_size);
543}
544
545BlockJob *backup_job_create(const char *job_id, BlockDriverState *bs,
546 BlockDriverState *target, int64_t speed,
547 MirrorSyncMode sync_mode, BdrvDirtyBitmap *sync_bitmap,
548 bool compress,
549 BlockdevOnError on_source_error,
550 BlockdevOnError on_target_error,
551 int creation_flags,
552 BlockCompletionFunc *cb, void *opaque,
553 JobTxn *txn, Error **errp)
554{
555 int64_t len;
556 BackupBlockJob *job = NULL;
557 int ret;
558 int64_t cluster_size;
559 HBitmap *copy_bitmap = NULL;
560
561 assert(bs);
562 assert(target);
563
564 if (bs == target) {
565 error_setg(errp, "Source and target cannot be the same");
566 return NULL;
567 }
568
569 if (!bdrv_is_inserted(bs)) {
570 error_setg(errp, "Device is not inserted: %s",
571 bdrv_get_device_name(bs));
572 return NULL;
573 }
574
575 if (!bdrv_is_inserted(target)) {
576 error_setg(errp, "Device is not inserted: %s",
577 bdrv_get_device_name(target));
578 return NULL;
579 }
580
581 if (compress && target->drv->bdrv_co_pwritev_compressed == NULL) {
582 error_setg(errp, "Compression is not supported for this drive %s",
583 bdrv_get_device_name(target));
584 return NULL;
585 }
586
587 if (bdrv_op_is_blocked(bs, BLOCK_OP_TYPE_BACKUP_SOURCE, errp)) {
588 return NULL;
589 }
590
591 if (bdrv_op_is_blocked(target, BLOCK_OP_TYPE_BACKUP_TARGET, errp)) {
592 return NULL;
593 }
594
595 if (sync_mode == MIRROR_SYNC_MODE_INCREMENTAL) {
596 if (!sync_bitmap) {
597 error_setg(errp, "must provide a valid bitmap name for "
598 "\"incremental\" sync mode");
599 return NULL;
600 }
601
602
603 if (bdrv_dirty_bitmap_create_successor(bs, sync_bitmap, errp) < 0) {
604 return NULL;
605 }
606 } else if (sync_bitmap) {
607 error_setg(errp,
608 "a sync_bitmap was provided to backup_run, "
609 "but received an incompatible sync_mode (%s)",
610 MirrorSyncMode_str(sync_mode));
611 return NULL;
612 }
613
614 len = bdrv_getlength(bs);
615 if (len < 0) {
616 error_setg_errno(errp, -len, "unable to get length for '%s'",
617 bdrv_get_device_name(bs));
618 goto error;
619 }
620
621 cluster_size = backup_calculate_cluster_size(target, errp);
622 if (cluster_size < 0) {
623 goto error;
624 }
625
626 copy_bitmap = hbitmap_alloc(len, ctz32(cluster_size));
627
628
629 job = block_job_create(job_id, &backup_job_driver, txn, bs,
630 BLK_PERM_CONSISTENT_READ,
631 BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE |
632 BLK_PERM_WRITE_UNCHANGED | BLK_PERM_GRAPH_MOD,
633 speed, creation_flags, cb, opaque, errp);
634 if (!job) {
635 goto error;
636 }
637
638
639 job->target = blk_new(job->common.job.aio_context,
640 BLK_PERM_WRITE,
641 BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE |
642 BLK_PERM_WRITE_UNCHANGED | BLK_PERM_GRAPH_MOD);
643 ret = blk_insert_bs(job->target, target, errp);
644 if (ret < 0) {
645 goto error;
646 }
647
648 job->on_source_error = on_source_error;
649 job->on_target_error = on_target_error;
650 job->sync_mode = sync_mode;
651 job->sync_bitmap = sync_mode == MIRROR_SYNC_MODE_INCREMENTAL ?
652 sync_bitmap : NULL;
653 job->compress = compress;
654
655
656 job->serialize_target_writes = bdrv_chain_contains(target, bs);
657 job->cluster_size = cluster_size;
658 job->copy_bitmap = copy_bitmap;
659 copy_bitmap = NULL;
660 job->copy_range_size = MIN_NON_ZERO(blk_get_max_transfer(job->common.blk),
661 blk_get_max_transfer(job->target));
662 job->copy_range_size = QEMU_ALIGN_DOWN(job->copy_range_size,
663 job->cluster_size);
664
665
666
667
668
669
670
671
672 job->use_copy_range = !compress && job->copy_range_size > 0;
673
674
675 block_job_add_bdrv(&job->common, "target", target, 0, BLK_PERM_ALL,
676 &error_abort);
677 job->len = len;
678
679 return &job->common;
680
681 error:
682 if (copy_bitmap) {
683 assert(!job || !job->copy_bitmap);
684 hbitmap_free(copy_bitmap);
685 }
686 if (sync_bitmap) {
687 bdrv_reclaim_dirty_bitmap(bs, sync_bitmap, NULL);
688 }
689 if (job) {
690 backup_clean(&job->common.job);
691 job_early_fail(&job->common.job);
692 }
693
694 return NULL;
695}
696