Merge remote-tracking branch 'remotes/kraxel/tags/pull-vga-20170103-1' 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 ret = -EINVAL;
90 opts = qemu_opts_create(&replication_runtime_opts, NULL, 0, &error_abort);
91 qemu_opts_absorb_qdict(opts, options, &local_err);
92 if (local_err) {
93 goto fail;
94 }
95
96 mode = qemu_opt_get(opts, REPLICATION_MODE);
97 if (!mode) {
98 error_setg(&local_err, "Missing the option mode");
99 goto fail;
100 }
101
102 if (!strcmp(mode, "primary")) {
103 s->mode = REPLICATION_MODE_PRIMARY;
104 top_id = qemu_opt_get(opts, REPLICATION_TOP_ID);
105 if (top_id) {
106 error_setg(&local_err, "The primary side does not support option top-id");
107 goto fail;
108 }
109 } else if (!strcmp(mode, "secondary")) {
110 s->mode = REPLICATION_MODE_SECONDARY;
111 top_id = qemu_opt_get(opts, REPLICATION_TOP_ID);
112 s->top_id = g_strdup(top_id);
113 if (!s->top_id) {
114 error_setg(&local_err, "Missing the option top-id");
115 goto fail;
116 }
117 } else {
118 error_setg(&local_err,
119 "The option mode's value should be primary or secondary");
120 goto fail;
121 }
122
123 s->rs = replication_new(bs, &replication_ops);
124
125 ret = 0;
126
127 fail:
128 qemu_opts_del(opts);
129 error_propagate(errp, local_err);
130
131 return ret;
132 }
133
134 static void replication_close(BlockDriverState *bs)
135 {
136 BDRVReplicationState *s = bs->opaque;
137
138 if (s->replication_state == BLOCK_REPLICATION_RUNNING) {
139 replication_stop(s->rs, false, NULL);
140 }
141 if (s->replication_state == BLOCK_REPLICATION_FAILOVER) {
142 block_job_cancel_sync(s->active_disk->bs->job);
143 }
144
145 if (s->mode == REPLICATION_MODE_SECONDARY) {
146 g_free(s->top_id);
147 }
148
149 replication_remove(s->rs);
150 }
151
152 static int64_t replication_getlength(BlockDriverState *bs)
153 {
154 return bdrv_getlength(bs->file->bs);
155 }
156
157 static int replication_get_io_status(BDRVReplicationState *s)
158 {
159 switch (s->replication_state) {
160 case BLOCK_REPLICATION_NONE:
161 return -EIO;
162 case BLOCK_REPLICATION_RUNNING:
163 return 0;
164 case BLOCK_REPLICATION_FAILOVER:
165 return s->mode == REPLICATION_MODE_PRIMARY ? -EIO : 0;
166 case BLOCK_REPLICATION_FAILOVER_FAILED:
167 return s->mode == REPLICATION_MODE_PRIMARY ? -EIO : 1;
168 case BLOCK_REPLICATION_DONE:
169 /*
170 * active commit job completes, and active disk and secondary_disk
171 * is swapped, so we can operate bs->file directly
172 */
173 return s->mode == REPLICATION_MODE_PRIMARY ? -EIO : 0;
174 default:
175 abort();
176 }
177 }
178
179 static int replication_return_value(BDRVReplicationState *s, int ret)
180 {
181 if (s->mode == REPLICATION_MODE_SECONDARY) {
182 return ret;
183 }
184
185 if (ret < 0) {
186 s->error = ret;
187 ret = 0;
188 }
189
190 return ret;
191 }
192
193 static coroutine_fn int replication_co_readv(BlockDriverState *bs,
194 int64_t sector_num,
195 int remaining_sectors,
196 QEMUIOVector *qiov)
197 {
198 BDRVReplicationState *s = bs->opaque;
199 BdrvChild *child = s->secondary_disk;
200 BlockJob *job = NULL;
201 CowRequest req;
202 int ret;
203
204 if (s->mode == REPLICATION_MODE_PRIMARY) {
205 /* We only use it to forward primary write requests */
206 return -EIO;
207 }
208
209 ret = replication_get_io_status(s);
210 if (ret < 0) {
211 return ret;
212 }
213
214 if (child && child->bs) {
215 job = child->bs->job;
216 }
217
218 if (job) {
219 backup_wait_for_overlapping_requests(child->bs->job, sector_num,
220 remaining_sectors);
221 backup_cow_request_begin(&req, child->bs->job, sector_num,
222 remaining_sectors);
223 ret = bdrv_co_readv(bs->file, sector_num, remaining_sectors,
224 qiov);
225 backup_cow_request_end(&req);
226 goto out;
227 }
228
229 ret = bdrv_co_readv(bs->file, sector_num, remaining_sectors, qiov);
230 out:
231 return replication_return_value(s, ret);
232 }
233
234 static coroutine_fn int replication_co_writev(BlockDriverState *bs,
235 int64_t sector_num,
236 int remaining_sectors,
237 QEMUIOVector *qiov)
238 {
239 BDRVReplicationState *s = bs->opaque;
240 QEMUIOVector hd_qiov;
241 uint64_t bytes_done = 0;
242 BdrvChild *top = bs->file;
243 BdrvChild *base = s->secondary_disk;
244 BdrvChild *target;
245 int ret, n;
246
247 ret = replication_get_io_status(s);
248 if (ret < 0) {
249 goto out;
250 }
251
252 if (ret == 0) {
253 ret = bdrv_co_writev(top, sector_num,
254 remaining_sectors, qiov);
255 return replication_return_value(s, ret);
256 }
257
258 /*
259 * Failover failed, only write to active disk if the sectors
260 * have already been allocated in active disk/hidden disk.
261 */
262 qemu_iovec_init(&hd_qiov, qiov->niov);
263 while (remaining_sectors > 0) {
264 ret = bdrv_is_allocated_above(top->bs, base->bs, sector_num,
265 remaining_sectors, &n);
266 if (ret < 0) {
267 goto out1;
268 }
269
270 qemu_iovec_reset(&hd_qiov);
271 qemu_iovec_concat(&hd_qiov, qiov, bytes_done, n * BDRV_SECTOR_SIZE);
272
273 target = ret ? top : base;
274 ret = bdrv_co_writev(target, sector_num, n, &hd_qiov);
275 if (ret < 0) {
276 goto out1;
277 }
278
279 remaining_sectors -= n;
280 sector_num += n;
281 bytes_done += n * BDRV_SECTOR_SIZE;
282 }
283
284 out1:
285 qemu_iovec_destroy(&hd_qiov);
286 out:
287 return ret;
288 }
289
290 static bool replication_recurse_is_first_non_filter(BlockDriverState *bs,
291 BlockDriverState *candidate)
292 {
293 return bdrv_recurse_is_first_non_filter(bs->file->bs, candidate);
294 }
295
296 static void secondary_do_checkpoint(BDRVReplicationState *s, Error **errp)
297 {
298 Error *local_err = NULL;
299 int ret;
300
301 if (!s->secondary_disk->bs->job) {
302 error_setg(errp, "Backup job was cancelled unexpectedly");
303 return;
304 }
305
306 backup_do_checkpoint(s->secondary_disk->bs->job, &local_err);
307 if (local_err) {
308 error_propagate(errp, local_err);
309 return;
310 }
311
312 ret = s->active_disk->bs->drv->bdrv_make_empty(s->active_disk->bs);
313 if (ret < 0) {
314 error_setg(errp, "Cannot make active disk empty");
315 return;
316 }
317
318 ret = s->hidden_disk->bs->drv->bdrv_make_empty(s->hidden_disk->bs);
319 if (ret < 0) {
320 error_setg(errp, "Cannot make hidden disk empty");
321 return;
322 }
323 }
324
325 static void reopen_backing_file(BlockDriverState *bs, bool writable,
326 Error **errp)
327 {
328 BDRVReplicationState *s = bs->opaque;
329 BlockReopenQueue *reopen_queue = NULL;
330 int orig_hidden_flags, orig_secondary_flags;
331 int new_hidden_flags, new_secondary_flags;
332 Error *local_err = NULL;
333
334 if (writable) {
335 orig_hidden_flags = s->orig_hidden_flags =
336 bdrv_get_flags(s->hidden_disk->bs);
337 new_hidden_flags = (orig_hidden_flags | BDRV_O_RDWR) &
338 ~BDRV_O_INACTIVE;
339 orig_secondary_flags = s->orig_secondary_flags =
340 bdrv_get_flags(s->secondary_disk->bs);
341 new_secondary_flags = (orig_secondary_flags | BDRV_O_RDWR) &
342 ~BDRV_O_INACTIVE;
343 } else {
344 orig_hidden_flags = (s->orig_hidden_flags | BDRV_O_RDWR) &
345 ~BDRV_O_INACTIVE;
346 new_hidden_flags = s->orig_hidden_flags;
347 orig_secondary_flags = (s->orig_secondary_flags | BDRV_O_RDWR) &
348 ~BDRV_O_INACTIVE;
349 new_secondary_flags = s->orig_secondary_flags;
350 }
351
352 if (orig_hidden_flags != new_hidden_flags) {
353 reopen_queue = bdrv_reopen_queue(reopen_queue, s->hidden_disk->bs, NULL,
354 new_hidden_flags);
355 }
356
357 if (!(orig_secondary_flags & BDRV_O_RDWR)) {
358 reopen_queue = bdrv_reopen_queue(reopen_queue, s->secondary_disk->bs,
359 NULL, new_secondary_flags);
360 }
361
362 if (reopen_queue) {
363 bdrv_reopen_multiple(bdrv_get_aio_context(bs),
364 reopen_queue, &local_err);
365 error_propagate(errp, local_err);
366 }
367 }
368
369 static void backup_job_cleanup(BlockDriverState *bs)
370 {
371 BDRVReplicationState *s = bs->opaque;
372 BlockDriverState *top_bs;
373
374 top_bs = bdrv_lookup_bs(s->top_id, s->top_id, NULL);
375 if (!top_bs) {
376 return;
377 }
378 bdrv_op_unblock_all(top_bs, s->blocker);
379 error_free(s->blocker);
380 reopen_backing_file(bs, false, NULL);
381 }
382
383 static void backup_job_completed(void *opaque, int ret)
384 {
385 BlockDriverState *bs = opaque;
386 BDRVReplicationState *s = bs->opaque;
387
388 if (s->replication_state != BLOCK_REPLICATION_FAILOVER) {
389 /* The backup job is cancelled unexpectedly */
390 s->error = -EIO;
391 }
392
393 backup_job_cleanup(bs);
394 }
395
396 static bool check_top_bs(BlockDriverState *top_bs, BlockDriverState *bs)
397 {
398 BdrvChild *child;
399
400 /* The bs itself is the top_bs */
401 if (top_bs == bs) {
402 return true;
403 }
404
405 /* Iterate over top_bs's children */
406 QLIST_FOREACH(child, &top_bs->children, next) {
407 if (child->bs == bs || check_top_bs(child->bs, bs)) {
408 return true;
409 }
410 }
411
412 return false;
413 }
414
415 static void replication_start(ReplicationState *rs, ReplicationMode mode,
416 Error **errp)
417 {
418 BlockDriverState *bs = rs->opaque;
419 BDRVReplicationState *s;
420 BlockDriverState *top_bs;
421 int64_t active_length, hidden_length, disk_length;
422 AioContext *aio_context;
423 Error *local_err = NULL;
424 BlockJob *job;
425
426 aio_context = bdrv_get_aio_context(bs);
427 aio_context_acquire(aio_context);
428 s = bs->opaque;
429
430 if (s->replication_state != BLOCK_REPLICATION_NONE) {
431 error_setg(errp, "Block replication is running or done");
432 aio_context_release(aio_context);
433 return;
434 }
435
436 if (s->mode != mode) {
437 error_setg(errp, "The parameter mode's value is invalid, needs %d,"
438 " but got %d", s->mode, mode);
439 aio_context_release(aio_context);
440 return;
441 }
442
443 switch (s->mode) {
444 case REPLICATION_MODE_PRIMARY:
445 break;
446 case REPLICATION_MODE_SECONDARY:
447 s->active_disk = bs->file;
448 if (!s->active_disk || !s->active_disk->bs ||
449 !s->active_disk->bs->backing) {
450 error_setg(errp, "Active disk doesn't have backing file");
451 aio_context_release(aio_context);
452 return;
453 }
454
455 s->hidden_disk = s->active_disk->bs->backing;
456 if (!s->hidden_disk->bs || !s->hidden_disk->bs->backing) {
457 error_setg(errp, "Hidden disk doesn't have backing file");
458 aio_context_release(aio_context);
459 return;
460 }
461
462 s->secondary_disk = s->hidden_disk->bs->backing;
463 if (!s->secondary_disk->bs || !bdrv_has_blk(s->secondary_disk->bs)) {
464 error_setg(errp, "The secondary disk doesn't have block backend");
465 aio_context_release(aio_context);
466 return;
467 }
468
469 /* verify the length */
470 active_length = bdrv_getlength(s->active_disk->bs);
471 hidden_length = bdrv_getlength(s->hidden_disk->bs);
472 disk_length = bdrv_getlength(s->secondary_disk->bs);
473 if (active_length < 0 || hidden_length < 0 || disk_length < 0 ||
474 active_length != hidden_length || hidden_length != disk_length) {
475 error_setg(errp, "Active disk, hidden disk, secondary disk's length"
476 " are not the same");
477 aio_context_release(aio_context);
478 return;
479 }
480
481 if (!s->active_disk->bs->drv->bdrv_make_empty ||
482 !s->hidden_disk->bs->drv->bdrv_make_empty) {
483 error_setg(errp,
484 "Active disk or hidden disk doesn't support make_empty");
485 aio_context_release(aio_context);
486 return;
487 }
488
489 /* reopen the backing file in r/w mode */
490 reopen_backing_file(bs, true, &local_err);
491 if (local_err) {
492 error_propagate(errp, local_err);
493 aio_context_release(aio_context);
494 return;
495 }
496
497 /* start backup job now */
498 error_setg(&s->blocker,
499 "Block device is in use by internal backup job");
500
501 top_bs = bdrv_lookup_bs(s->top_id, s->top_id, NULL);
502 if (!top_bs || !bdrv_is_root_node(top_bs) ||
503 !check_top_bs(top_bs, bs)) {
504 error_setg(errp, "No top_bs or it is invalid");
505 reopen_backing_file(bs, false, NULL);
506 aio_context_release(aio_context);
507 return;
508 }
509 bdrv_op_block_all(top_bs, s->blocker);
510 bdrv_op_unblock(top_bs, BLOCK_OP_TYPE_DATAPLANE, s->blocker);
511
512 job = backup_job_create(NULL, s->secondary_disk->bs, s->hidden_disk->bs,
513 0, MIRROR_SYNC_MODE_NONE, NULL, false,
514 BLOCKDEV_ON_ERROR_REPORT,
515 BLOCKDEV_ON_ERROR_REPORT, BLOCK_JOB_INTERNAL,
516 backup_job_completed, bs, NULL, &local_err);
517 if (local_err) {
518 error_propagate(errp, local_err);
519 backup_job_cleanup(bs);
520 aio_context_release(aio_context);
521 return;
522 }
523 block_job_start(job);
524 break;
525 default:
526 aio_context_release(aio_context);
527 abort();
528 }
529
530 s->replication_state = BLOCK_REPLICATION_RUNNING;
531
532 if (s->mode == REPLICATION_MODE_SECONDARY) {
533 secondary_do_checkpoint(s, errp);
534 }
535
536 s->error = 0;
537 aio_context_release(aio_context);
538 }
539
540 static void replication_do_checkpoint(ReplicationState *rs, Error **errp)
541 {
542 BlockDriverState *bs = rs->opaque;
543 BDRVReplicationState *s;
544 AioContext *aio_context;
545
546 aio_context = bdrv_get_aio_context(bs);
547 aio_context_acquire(aio_context);
548 s = bs->opaque;
549
550 if (s->mode == REPLICATION_MODE_SECONDARY) {
551 secondary_do_checkpoint(s, errp);
552 }
553 aio_context_release(aio_context);
554 }
555
556 static void replication_get_error(ReplicationState *rs, Error **errp)
557 {
558 BlockDriverState *bs = rs->opaque;
559 BDRVReplicationState *s;
560 AioContext *aio_context;
561
562 aio_context = bdrv_get_aio_context(bs);
563 aio_context_acquire(aio_context);
564 s = bs->opaque;
565
566 if (s->replication_state != BLOCK_REPLICATION_RUNNING) {
567 error_setg(errp, "Block replication is not running");
568 aio_context_release(aio_context);
569 return;
570 }
571
572 if (s->error) {
573 error_setg(errp, "I/O error occurred");
574 aio_context_release(aio_context);
575 return;
576 }
577 aio_context_release(aio_context);
578 }
579
580 static void replication_done(void *opaque, int ret)
581 {
582 BlockDriverState *bs = opaque;
583 BDRVReplicationState *s = bs->opaque;
584
585 if (ret == 0) {
586 s->replication_state = BLOCK_REPLICATION_DONE;
587
588 /* refresh top bs's filename */
589 bdrv_refresh_filename(bs);
590 s->active_disk = NULL;
591 s->secondary_disk = NULL;
592 s->hidden_disk = NULL;
593 s->error = 0;
594 } else {
595 s->replication_state = BLOCK_REPLICATION_FAILOVER_FAILED;
596 s->error = -EIO;
597 }
598 }
599
600 static void replication_stop(ReplicationState *rs, bool failover, Error **errp)
601 {
602 BlockDriverState *bs = rs->opaque;
603 BDRVReplicationState *s;
604 AioContext *aio_context;
605
606 aio_context = bdrv_get_aio_context(bs);
607 aio_context_acquire(aio_context);
608 s = bs->opaque;
609
610 if (s->replication_state != BLOCK_REPLICATION_RUNNING) {
611 error_setg(errp, "Block replication is not running");
612 aio_context_release(aio_context);
613 return;
614 }
615
616 switch (s->mode) {
617 case REPLICATION_MODE_PRIMARY:
618 s->replication_state = BLOCK_REPLICATION_DONE;
619 s->error = 0;
620 break;
621 case REPLICATION_MODE_SECONDARY:
622 /*
623 * This BDS will be closed, and the job should be completed
624 * before the BDS is closed, because we will access hidden
625 * disk, secondary disk in backup_job_completed().
626 */
627 if (s->secondary_disk->bs->job) {
628 block_job_cancel_sync(s->secondary_disk->bs->job);
629 }
630
631 if (!failover) {
632 secondary_do_checkpoint(s, errp);
633 s->replication_state = BLOCK_REPLICATION_DONE;
634 aio_context_release(aio_context);
635 return;
636 }
637
638 s->replication_state = BLOCK_REPLICATION_FAILOVER;
639 commit_active_start(NULL, s->active_disk->bs, s->secondary_disk->bs,
640 BLOCK_JOB_INTERNAL, 0, BLOCKDEV_ON_ERROR_REPORT,
641 replication_done, bs, errp, true);
642 break;
643 default:
644 aio_context_release(aio_context);
645 abort();
646 }
647 aio_context_release(aio_context);
648 }
649
650 BlockDriver bdrv_replication = {
651 .format_name = "replication",
652 .protocol_name = "replication",
653 .instance_size = sizeof(BDRVReplicationState),
654
655 .bdrv_open = replication_open,
656 .bdrv_close = replication_close,
657
658 .bdrv_getlength = replication_getlength,
659 .bdrv_co_readv = replication_co_readv,
660 .bdrv_co_writev = replication_co_writev,
661
662 .is_filter = true,
663 .bdrv_recurse_is_first_non_filter = replication_recurse_is_first_non_filter,
664
665 .has_variable_length = true,
666 };
667
668 static void bdrv_replication_init(void)
669 {
670 bdrv_register(&bdrv_replication);
671 }
672
673 block_init(bdrv_replication_init);