Merge remote-tracking branch 'remotes/armbru/tags/pull-qapi-2017-03-16' into staging
[qemu.git] / block / replication.c
1 /*
2 * Replication Block filter
3 *
4 * Copyright (c) 2016 HUAWEI TECHNOLOGIES CO., LTD.
5 * Copyright (c) 2016 Intel Corporation
6 * Copyright (c) 2016 FUJITSU LIMITED
7 *
8 * Author:
9 * Wen Congyang <wency@cn.fujitsu.com>
10 *
11 * This work is licensed under the terms of the GNU GPL, version 2 or later.
12 * See the COPYING file in the top-level directory.
13 */
14
15 #include "qemu/osdep.h"
16 #include "qemu-common.h"
17 #include "block/nbd.h"
18 #include "block/blockjob.h"
19 #include "block/block_int.h"
20 #include "block/block_backup.h"
21 #include "sysemu/block-backend.h"
22 #include "qapi/error.h"
23 #include "replication.h"
24
25 typedef struct BDRVReplicationState {
26 ReplicationMode mode;
27 int replication_state;
28 BdrvChild *active_disk;
29 BdrvChild *hidden_disk;
30 BdrvChild *secondary_disk;
31 char *top_id;
32 ReplicationState *rs;
33 Error *blocker;
34 int orig_hidden_flags;
35 int orig_secondary_flags;
36 int error;
37 } BDRVReplicationState;
38
39 enum {
40 BLOCK_REPLICATION_NONE, /* block replication is not started */
41 BLOCK_REPLICATION_RUNNING, /* block replication is running */
42 BLOCK_REPLICATION_FAILOVER, /* failover is running in background */
43 BLOCK_REPLICATION_FAILOVER_FAILED, /* failover failed */
44 BLOCK_REPLICATION_DONE, /* block replication is done */
45 };
46
47 static void replication_start(ReplicationState *rs, ReplicationMode mode,
48 Error **errp);
49 static void replication_do_checkpoint(ReplicationState *rs, Error **errp);
50 static void replication_get_error(ReplicationState *rs, Error **errp);
51 static void replication_stop(ReplicationState *rs, bool failover,
52 Error **errp);
53
54 #define REPLICATION_MODE "mode"
55 #define REPLICATION_TOP_ID "top-id"
56 static QemuOptsList replication_runtime_opts = {
57 .name = "replication",
58 .head = QTAILQ_HEAD_INITIALIZER(replication_runtime_opts.head),
59 .desc = {
60 {
61 .name = REPLICATION_MODE,
62 .type = QEMU_OPT_STRING,
63 },
64 {
65 .name = REPLICATION_TOP_ID,
66 .type = QEMU_OPT_STRING,
67 },
68 { /* end of list */ }
69 },
70 };
71
72 static ReplicationOps replication_ops = {
73 .start = replication_start,
74 .checkpoint = replication_do_checkpoint,
75 .get_error = replication_get_error,
76 .stop = replication_stop,
77 };
78
79 static int replication_open(BlockDriverState *bs, QDict *options,
80 int flags, Error **errp)
81 {
82 int ret;
83 BDRVReplicationState *s = bs->opaque;
84 Error *local_err = NULL;
85 QemuOpts *opts = NULL;
86 const char *mode;
87 const char *top_id;
88
89 bs->file = bdrv_open_child(NULL, options, "file", bs, &child_file,
90 false, errp);
91 if (!bs->file) {
92 return -EINVAL;
93 }
94
95 ret = -EINVAL;
96 opts = qemu_opts_create(&replication_runtime_opts, NULL, 0, &error_abort);
97 qemu_opts_absorb_qdict(opts, options, &local_err);
98 if (local_err) {
99 goto fail;
100 }
101
102 mode = qemu_opt_get(opts, REPLICATION_MODE);
103 if (!mode) {
104 error_setg(&local_err, "Missing the option mode");
105 goto fail;
106 }
107
108 if (!strcmp(mode, "primary")) {
109 s->mode = REPLICATION_MODE_PRIMARY;
110 top_id = qemu_opt_get(opts, REPLICATION_TOP_ID);
111 if (top_id) {
112 error_setg(&local_err, "The primary side does not support option top-id");
113 goto fail;
114 }
115 } else if (!strcmp(mode, "secondary")) {
116 s->mode = REPLICATION_MODE_SECONDARY;
117 top_id = qemu_opt_get(opts, REPLICATION_TOP_ID);
118 s->top_id = g_strdup(top_id);
119 if (!s->top_id) {
120 error_setg(&local_err, "Missing the option top-id");
121 goto fail;
122 }
123 } else {
124 error_setg(&local_err,
125 "The option mode's value should be primary or secondary");
126 goto fail;
127 }
128
129 s->rs = replication_new(bs, &replication_ops);
130
131 ret = 0;
132
133 fail:
134 qemu_opts_del(opts);
135 error_propagate(errp, local_err);
136
137 return ret;
138 }
139
140 static void replication_close(BlockDriverState *bs)
141 {
142 BDRVReplicationState *s = bs->opaque;
143
144 if (s->replication_state == BLOCK_REPLICATION_RUNNING) {
145 replication_stop(s->rs, false, NULL);
146 }
147 if (s->replication_state == BLOCK_REPLICATION_FAILOVER) {
148 block_job_cancel_sync(s->active_disk->bs->job);
149 }
150
151 if (s->mode == REPLICATION_MODE_SECONDARY) {
152 g_free(s->top_id);
153 }
154
155 replication_remove(s->rs);
156 }
157
158 static int64_t replication_getlength(BlockDriverState *bs)
159 {
160 return bdrv_getlength(bs->file->bs);
161 }
162
163 static int replication_get_io_status(BDRVReplicationState *s)
164 {
165 switch (s->replication_state) {
166 case BLOCK_REPLICATION_NONE:
167 return -EIO;
168 case BLOCK_REPLICATION_RUNNING:
169 return 0;
170 case BLOCK_REPLICATION_FAILOVER:
171 return s->mode == REPLICATION_MODE_PRIMARY ? -EIO : 0;
172 case BLOCK_REPLICATION_FAILOVER_FAILED:
173 return s->mode == REPLICATION_MODE_PRIMARY ? -EIO : 1;
174 case BLOCK_REPLICATION_DONE:
175 /*
176 * active commit job completes, and active disk and secondary_disk
177 * is swapped, so we can operate bs->file directly
178 */
179 return s->mode == REPLICATION_MODE_PRIMARY ? -EIO : 0;
180 default:
181 abort();
182 }
183 }
184
185 static int replication_return_value(BDRVReplicationState *s, int ret)
186 {
187 if (s->mode == REPLICATION_MODE_SECONDARY) {
188 return ret;
189 }
190
191 if (ret < 0) {
192 s->error = ret;
193 ret = 0;
194 }
195
196 return ret;
197 }
198
199 static coroutine_fn int replication_co_readv(BlockDriverState *bs,
200 int64_t sector_num,
201 int remaining_sectors,
202 QEMUIOVector *qiov)
203 {
204 BDRVReplicationState *s = bs->opaque;
205 BdrvChild *child = s->secondary_disk;
206 BlockJob *job = NULL;
207 CowRequest req;
208 int ret;
209
210 if (s->mode == REPLICATION_MODE_PRIMARY) {
211 /* We only use it to forward primary write requests */
212 return -EIO;
213 }
214
215 ret = replication_get_io_status(s);
216 if (ret < 0) {
217 return ret;
218 }
219
220 if (child && child->bs) {
221 job = child->bs->job;
222 }
223
224 if (job) {
225 backup_wait_for_overlapping_requests(child->bs->job, sector_num,
226 remaining_sectors);
227 backup_cow_request_begin(&req, child->bs->job, sector_num,
228 remaining_sectors);
229 ret = bdrv_co_readv(bs->file, sector_num, remaining_sectors,
230 qiov);
231 backup_cow_request_end(&req);
232 goto out;
233 }
234
235 ret = bdrv_co_readv(bs->file, sector_num, remaining_sectors, qiov);
236 out:
237 return replication_return_value(s, ret);
238 }
239
240 static coroutine_fn int replication_co_writev(BlockDriverState *bs,
241 int64_t sector_num,
242 int remaining_sectors,
243 QEMUIOVector *qiov)
244 {
245 BDRVReplicationState *s = bs->opaque;
246 QEMUIOVector hd_qiov;
247 uint64_t bytes_done = 0;
248 BdrvChild *top = bs->file;
249 BdrvChild *base = s->secondary_disk;
250 BdrvChild *target;
251 int ret, n;
252
253 ret = replication_get_io_status(s);
254 if (ret < 0) {
255 goto out;
256 }
257
258 if (ret == 0) {
259 ret = bdrv_co_writev(top, sector_num,
260 remaining_sectors, qiov);
261 return replication_return_value(s, ret);
262 }
263
264 /*
265 * Failover failed, only write to active disk if the sectors
266 * have already been allocated in active disk/hidden disk.
267 */
268 qemu_iovec_init(&hd_qiov, qiov->niov);
269 while (remaining_sectors > 0) {
270 ret = bdrv_is_allocated_above(top->bs, base->bs, sector_num,
271 remaining_sectors, &n);
272 if (ret < 0) {
273 goto out1;
274 }
275
276 qemu_iovec_reset(&hd_qiov);
277 qemu_iovec_concat(&hd_qiov, qiov, bytes_done, n * BDRV_SECTOR_SIZE);
278
279 target = ret ? top : base;
280 ret = bdrv_co_writev(target, sector_num, n, &hd_qiov);
281 if (ret < 0) {
282 goto out1;
283 }
284
285 remaining_sectors -= n;
286 sector_num += n;
287 bytes_done += n * BDRV_SECTOR_SIZE;
288 }
289
290 out1:
291 qemu_iovec_destroy(&hd_qiov);
292 out:
293 return ret;
294 }
295
296 static bool replication_recurse_is_first_non_filter(BlockDriverState *bs,
297 BlockDriverState *candidate)
298 {
299 return bdrv_recurse_is_first_non_filter(bs->file->bs, candidate);
300 }
301
302 static void secondary_do_checkpoint(BDRVReplicationState *s, Error **errp)
303 {
304 Error *local_err = NULL;
305 int ret;
306
307 if (!s->secondary_disk->bs->job) {
308 error_setg(errp, "Backup job was cancelled unexpectedly");
309 return;
310 }
311
312 backup_do_checkpoint(s->secondary_disk->bs->job, &local_err);
313 if (local_err) {
314 error_propagate(errp, local_err);
315 return;
316 }
317
318 ret = s->active_disk->bs->drv->bdrv_make_empty(s->active_disk->bs);
319 if (ret < 0) {
320 error_setg(errp, "Cannot make active disk empty");
321 return;
322 }
323
324 ret = s->hidden_disk->bs->drv->bdrv_make_empty(s->hidden_disk->bs);
325 if (ret < 0) {
326 error_setg(errp, "Cannot make hidden disk empty");
327 return;
328 }
329 }
330
331 static void reopen_backing_file(BlockDriverState *bs, bool writable,
332 Error **errp)
333 {
334 BDRVReplicationState *s = bs->opaque;
335 BlockReopenQueue *reopen_queue = NULL;
336 int orig_hidden_flags, orig_secondary_flags;
337 int new_hidden_flags, new_secondary_flags;
338 Error *local_err = NULL;
339
340 if (writable) {
341 orig_hidden_flags = s->orig_hidden_flags =
342 bdrv_get_flags(s->hidden_disk->bs);
343 new_hidden_flags = (orig_hidden_flags | BDRV_O_RDWR) &
344 ~BDRV_O_INACTIVE;
345 orig_secondary_flags = s->orig_secondary_flags =
346 bdrv_get_flags(s->secondary_disk->bs);
347 new_secondary_flags = (orig_secondary_flags | BDRV_O_RDWR) &
348 ~BDRV_O_INACTIVE;
349 } else {
350 orig_hidden_flags = (s->orig_hidden_flags | BDRV_O_RDWR) &
351 ~BDRV_O_INACTIVE;
352 new_hidden_flags = s->orig_hidden_flags;
353 orig_secondary_flags = (s->orig_secondary_flags | BDRV_O_RDWR) &
354 ~BDRV_O_INACTIVE;
355 new_secondary_flags = s->orig_secondary_flags;
356 }
357
358 if (orig_hidden_flags != new_hidden_flags) {
359 reopen_queue = bdrv_reopen_queue(reopen_queue, s->hidden_disk->bs, NULL,
360 new_hidden_flags);
361 }
362
363 if (!(orig_secondary_flags & BDRV_O_RDWR)) {
364 reopen_queue = bdrv_reopen_queue(reopen_queue, s->secondary_disk->bs,
365 NULL, new_secondary_flags);
366 }
367
368 if (reopen_queue) {
369 bdrv_reopen_multiple(bdrv_get_aio_context(bs),
370 reopen_queue, &local_err);
371 error_propagate(errp, local_err);
372 }
373 }
374
375 static void backup_job_cleanup(BlockDriverState *bs)
376 {
377 BDRVReplicationState *s = bs->opaque;
378 BlockDriverState *top_bs;
379
380 top_bs = bdrv_lookup_bs(s->top_id, s->top_id, NULL);
381 if (!top_bs) {
382 return;
383 }
384 bdrv_op_unblock_all(top_bs, s->blocker);
385 error_free(s->blocker);
386 reopen_backing_file(bs, false, NULL);
387 }
388
389 static void backup_job_completed(void *opaque, int ret)
390 {
391 BlockDriverState *bs = opaque;
392 BDRVReplicationState *s = bs->opaque;
393
394 if (s->replication_state != BLOCK_REPLICATION_FAILOVER) {
395 /* The backup job is cancelled unexpectedly */
396 s->error = -EIO;
397 }
398
399 backup_job_cleanup(bs);
400 }
401
402 static bool check_top_bs(BlockDriverState *top_bs, BlockDriverState *bs)
403 {
404 BdrvChild *child;
405
406 /* The bs itself is the top_bs */
407 if (top_bs == bs) {
408 return true;
409 }
410
411 /* Iterate over top_bs's children */
412 QLIST_FOREACH(child, &top_bs->children, next) {
413 if (child->bs == bs || check_top_bs(child->bs, bs)) {
414 return true;
415 }
416 }
417
418 return false;
419 }
420
421 static void replication_start(ReplicationState *rs, ReplicationMode mode,
422 Error **errp)
423 {
424 BlockDriverState *bs = rs->opaque;
425 BDRVReplicationState *s;
426 BlockDriverState *top_bs;
427 int64_t active_length, hidden_length, disk_length;
428 AioContext *aio_context;
429 Error *local_err = NULL;
430 BlockJob *job;
431
432 aio_context = bdrv_get_aio_context(bs);
433 aio_context_acquire(aio_context);
434 s = bs->opaque;
435
436 if (s->replication_state != BLOCK_REPLICATION_NONE) {
437 error_setg(errp, "Block replication is running or done");
438 aio_context_release(aio_context);
439 return;
440 }
441
442 if (s->mode != mode) {
443 error_setg(errp, "The parameter mode's value is invalid, needs %d,"
444 " but got %d", s->mode, mode);
445 aio_context_release(aio_context);
446 return;
447 }
448
449 switch (s->mode) {
450 case REPLICATION_MODE_PRIMARY:
451 break;
452 case REPLICATION_MODE_SECONDARY:
453 s->active_disk = bs->file;
454 if (!s->active_disk || !s->active_disk->bs ||
455 !s->active_disk->bs->backing) {
456 error_setg(errp, "Active disk doesn't have backing file");
457 aio_context_release(aio_context);
458 return;
459 }
460
461 s->hidden_disk = s->active_disk->bs->backing;
462 if (!s->hidden_disk->bs || !s->hidden_disk->bs->backing) {
463 error_setg(errp, "Hidden disk doesn't have backing file");
464 aio_context_release(aio_context);
465 return;
466 }
467
468 s->secondary_disk = s->hidden_disk->bs->backing;
469 if (!s->secondary_disk->bs || !bdrv_has_blk(s->secondary_disk->bs)) {
470 error_setg(errp, "The secondary disk doesn't have block backend");
471 aio_context_release(aio_context);
472 return;
473 }
474
475 /* verify the length */
476 active_length = bdrv_getlength(s->active_disk->bs);
477 hidden_length = bdrv_getlength(s->hidden_disk->bs);
478 disk_length = bdrv_getlength(s->secondary_disk->bs);
479 if (active_length < 0 || hidden_length < 0 || disk_length < 0 ||
480 active_length != hidden_length || hidden_length != disk_length) {
481 error_setg(errp, "Active disk, hidden disk, secondary disk's length"
482 " are not the same");
483 aio_context_release(aio_context);
484 return;
485 }
486
487 if (!s->active_disk->bs->drv->bdrv_make_empty ||
488 !s->hidden_disk->bs->drv->bdrv_make_empty) {
489 error_setg(errp,
490 "Active disk or hidden disk doesn't support make_empty");
491 aio_context_release(aio_context);
492 return;
493 }
494
495 /* reopen the backing file in r/w mode */
496 reopen_backing_file(bs, true, &local_err);
497 if (local_err) {
498 error_propagate(errp, local_err);
499 aio_context_release(aio_context);
500 return;
501 }
502
503 /* start backup job now */
504 error_setg(&s->blocker,
505 "Block device is in use by internal backup job");
506
507 top_bs = bdrv_lookup_bs(s->top_id, s->top_id, NULL);
508 if (!top_bs || !bdrv_is_root_node(top_bs) ||
509 !check_top_bs(top_bs, bs)) {
510 error_setg(errp, "No top_bs or it is invalid");
511 reopen_backing_file(bs, false, NULL);
512 aio_context_release(aio_context);
513 return;
514 }
515 bdrv_op_block_all(top_bs, s->blocker);
516 bdrv_op_unblock(top_bs, BLOCK_OP_TYPE_DATAPLANE, s->blocker);
517
518 job = backup_job_create(NULL, s->secondary_disk->bs, s->hidden_disk->bs,
519 0, MIRROR_SYNC_MODE_NONE, NULL, false,
520 BLOCKDEV_ON_ERROR_REPORT,
521 BLOCKDEV_ON_ERROR_REPORT, BLOCK_JOB_INTERNAL,
522 backup_job_completed, bs, NULL, &local_err);
523 if (local_err) {
524 error_propagate(errp, local_err);
525 backup_job_cleanup(bs);
526 aio_context_release(aio_context);
527 return;
528 }
529 block_job_start(job);
530 break;
531 default:
532 aio_context_release(aio_context);
533 abort();
534 }
535
536 s->replication_state = BLOCK_REPLICATION_RUNNING;
537
538 if (s->mode == REPLICATION_MODE_SECONDARY) {
539 secondary_do_checkpoint(s, errp);
540 }
541
542 s->error = 0;
543 aio_context_release(aio_context);
544 }
545
546 static void replication_do_checkpoint(ReplicationState *rs, Error **errp)
547 {
548 BlockDriverState *bs = rs->opaque;
549 BDRVReplicationState *s;
550 AioContext *aio_context;
551
552 aio_context = bdrv_get_aio_context(bs);
553 aio_context_acquire(aio_context);
554 s = bs->opaque;
555
556 if (s->mode == REPLICATION_MODE_SECONDARY) {
557 secondary_do_checkpoint(s, errp);
558 }
559 aio_context_release(aio_context);
560 }
561
562 static void replication_get_error(ReplicationState *rs, Error **errp)
563 {
564 BlockDriverState *bs = rs->opaque;
565 BDRVReplicationState *s;
566 AioContext *aio_context;
567
568 aio_context = bdrv_get_aio_context(bs);
569 aio_context_acquire(aio_context);
570 s = bs->opaque;
571
572 if (s->replication_state != BLOCK_REPLICATION_RUNNING) {
573 error_setg(errp, "Block replication is not running");
574 aio_context_release(aio_context);
575 return;
576 }
577
578 if (s->error) {
579 error_setg(errp, "I/O error occurred");
580 aio_context_release(aio_context);
581 return;
582 }
583 aio_context_release(aio_context);
584 }
585
586 static void replication_done(void *opaque, int ret)
587 {
588 BlockDriverState *bs = opaque;
589 BDRVReplicationState *s = bs->opaque;
590
591 if (ret == 0) {
592 s->replication_state = BLOCK_REPLICATION_DONE;
593
594 /* refresh top bs's filename */
595 bdrv_refresh_filename(bs);
596 s->active_disk = NULL;
597 s->secondary_disk = NULL;
598 s->hidden_disk = NULL;
599 s->error = 0;
600 } else {
601 s->replication_state = BLOCK_REPLICATION_FAILOVER_FAILED;
602 s->error = -EIO;
603 }
604 }
605
606 static void replication_stop(ReplicationState *rs, bool failover, Error **errp)
607 {
608 BlockDriverState *bs = rs->opaque;
609 BDRVReplicationState *s;
610 AioContext *aio_context;
611
612 aio_context = bdrv_get_aio_context(bs);
613 aio_context_acquire(aio_context);
614 s = bs->opaque;
615
616 if (s->replication_state != BLOCK_REPLICATION_RUNNING) {
617 error_setg(errp, "Block replication is not running");
618 aio_context_release(aio_context);
619 return;
620 }
621
622 switch (s->mode) {
623 case REPLICATION_MODE_PRIMARY:
624 s->replication_state = BLOCK_REPLICATION_DONE;
625 s->error = 0;
626 break;
627 case REPLICATION_MODE_SECONDARY:
628 /*
629 * This BDS will be closed, and the job should be completed
630 * before the BDS is closed, because we will access hidden
631 * disk, secondary disk in backup_job_completed().
632 */
633 if (s->secondary_disk->bs->job) {
634 block_job_cancel_sync(s->secondary_disk->bs->job);
635 }
636
637 if (!failover) {
638 secondary_do_checkpoint(s, errp);
639 s->replication_state = BLOCK_REPLICATION_DONE;
640 aio_context_release(aio_context);
641 return;
642 }
643
644 s->replication_state = BLOCK_REPLICATION_FAILOVER;
645 commit_active_start(NULL, s->active_disk->bs, s->secondary_disk->bs,
646 BLOCK_JOB_INTERNAL, 0, BLOCKDEV_ON_ERROR_REPORT,
647 NULL, replication_done, bs, errp, true);
648 break;
649 default:
650 aio_context_release(aio_context);
651 abort();
652 }
653 aio_context_release(aio_context);
654 }
655
656 BlockDriver bdrv_replication = {
657 .format_name = "replication",
658 .protocol_name = "replication",
659 .instance_size = sizeof(BDRVReplicationState),
660
661 .bdrv_open = replication_open,
662 .bdrv_close = replication_close,
663 .bdrv_child_perm = bdrv_filter_default_perms,
664
665 .bdrv_getlength = replication_getlength,
666 .bdrv_co_readv = replication_co_readv,
667 .bdrv_co_writev = replication_co_writev,
668
669 .is_filter = true,
670 .bdrv_recurse_is_first_non_filter = replication_recurse_is_first_non_filter,
671
672 .has_variable_length = true,
673 };
674
675 static void bdrv_replication_init(void)
676 {
677 bdrv_register(&bdrv_replication);
678 }
679
680 block_init(bdrv_replication_init);