xref: /openbmc/qemu/block/replication.c (revision f0830823)
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/module.h"
17 #include "qemu/option.h"
18 #include "block/nbd.h"
19 #include "block/blockjob.h"
20 #include "block/block_int.h"
21 #include "block/block_backup.h"
22 #include "sysemu/block-backend.h"
23 #include "qapi/error.h"
24 #include "qapi/qmp/qdict.h"
25 #include "block/replication.h"
26 
27 typedef enum {
28     BLOCK_REPLICATION_NONE,             /* block replication is not started */
29     BLOCK_REPLICATION_RUNNING,          /* block replication is running */
30     BLOCK_REPLICATION_FAILOVER,         /* failover is running in background */
31     BLOCK_REPLICATION_FAILOVER_FAILED,  /* failover failed */
32     BLOCK_REPLICATION_DONE,             /* block replication is done */
33 } ReplicationStage;
34 
35 typedef struct BDRVReplicationState {
36     ReplicationMode mode;
37     ReplicationStage stage;
38     BlockJob *commit_job;
39     BdrvChild *hidden_disk;
40     BdrvChild *secondary_disk;
41     BlockJob *backup_job;
42     char *top_id;
43     ReplicationState *rs;
44     Error *blocker;
45     bool orig_hidden_read_only;
46     bool orig_secondary_read_only;
47     int error;
48 } BDRVReplicationState;
49 
50 static void replication_start(ReplicationState *rs, ReplicationMode mode,
51                               Error **errp);
52 static void replication_do_checkpoint(ReplicationState *rs, Error **errp);
53 static void replication_get_error(ReplicationState *rs, Error **errp);
54 static void replication_stop(ReplicationState *rs, bool failover,
55                              Error **errp);
56 
57 #define REPLICATION_MODE        "mode"
58 #define REPLICATION_TOP_ID      "top-id"
59 static QemuOptsList replication_runtime_opts = {
60     .name = "replication",
61     .head = QTAILQ_HEAD_INITIALIZER(replication_runtime_opts.head),
62     .desc = {
63         {
64             .name = REPLICATION_MODE,
65             .type = QEMU_OPT_STRING,
66         },
67         {
68             .name = REPLICATION_TOP_ID,
69             .type = QEMU_OPT_STRING,
70         },
71         { /* end of list */ }
72     },
73 };
74 
75 static ReplicationOps replication_ops = {
76     .start = replication_start,
77     .checkpoint = replication_do_checkpoint,
78     .get_error = replication_get_error,
79     .stop = replication_stop,
80 };
81 
82 static int replication_open(BlockDriverState *bs, QDict *options,
83                             int flags, Error **errp)
84 {
85     int ret;
86     BDRVReplicationState *s = bs->opaque;
87     QemuOpts *opts = NULL;
88     const char *mode;
89     const char *top_id;
90 
91     ret = bdrv_open_file_child(NULL, options, "file", bs, errp);
92     if (ret < 0) {
93         return ret;
94     }
95 
96     ret = -EINVAL;
97     opts = qemu_opts_create(&replication_runtime_opts, NULL, 0, &error_abort);
98     if (!qemu_opts_absorb_qdict(opts, options, errp)) {
99         goto fail;
100     }
101 
102     mode = qemu_opt_get(opts, REPLICATION_MODE);
103     if (!mode) {
104         error_setg(errp, "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(errp,
113                        "The primary side does not support option top-id");
114             goto fail;
115         }
116     } else if (!strcmp(mode, "secondary")) {
117         s->mode = REPLICATION_MODE_SECONDARY;
118         top_id = qemu_opt_get(opts, REPLICATION_TOP_ID);
119         s->top_id = g_strdup(top_id);
120         if (!s->top_id) {
121             error_setg(errp, "Missing the option top-id");
122             goto fail;
123         }
124     } else {
125         error_setg(errp,
126                    "The option mode's value should be primary or secondary");
127         goto fail;
128     }
129 
130     s->rs = replication_new(bs, &replication_ops);
131 
132     ret = 0;
133 
134 fail:
135     qemu_opts_del(opts);
136     return ret;
137 }
138 
139 static void replication_close(BlockDriverState *bs)
140 {
141     BDRVReplicationState *s = bs->opaque;
142     Job *commit_job;
143     GLOBAL_STATE_CODE();
144 
145     if (s->stage == BLOCK_REPLICATION_RUNNING) {
146         replication_stop(s->rs, false, NULL);
147     }
148     if (s->stage == BLOCK_REPLICATION_FAILOVER) {
149         commit_job = &s->commit_job->job;
150         assert(commit_job->aio_context == qemu_get_current_aio_context());
151         job_cancel_sync(commit_job, false);
152     }
153 
154     if (s->mode == REPLICATION_MODE_SECONDARY) {
155         g_free(s->top_id);
156     }
157 
158     replication_remove(s->rs);
159 }
160 
161 static void replication_child_perm(BlockDriverState *bs, BdrvChild *c,
162                                    BdrvChildRole role,
163                                    BlockReopenQueue *reopen_queue,
164                                    uint64_t perm, uint64_t shared,
165                                    uint64_t *nperm, uint64_t *nshared)
166 {
167     if (role & BDRV_CHILD_PRIMARY) {
168         *nperm = BLK_PERM_CONSISTENT_READ;
169     } else {
170         *nperm = 0;
171     }
172 
173     if ((bs->open_flags & (BDRV_O_INACTIVE | BDRV_O_RDWR)) == BDRV_O_RDWR) {
174         *nperm |= BLK_PERM_WRITE;
175     }
176     *nshared = BLK_PERM_CONSISTENT_READ
177                | BLK_PERM_WRITE
178                | BLK_PERM_WRITE_UNCHANGED;
179     return;
180 }
181 
182 static int64_t coroutine_fn GRAPH_RDLOCK
183 replication_co_getlength(BlockDriverState *bs)
184 {
185     return bdrv_co_getlength(bs->file->bs);
186 }
187 
188 static int replication_get_io_status(BDRVReplicationState *s)
189 {
190     switch (s->stage) {
191     case BLOCK_REPLICATION_NONE:
192         return -EIO;
193     case BLOCK_REPLICATION_RUNNING:
194         return 0;
195     case BLOCK_REPLICATION_FAILOVER:
196         return s->mode == REPLICATION_MODE_PRIMARY ? -EIO : 0;
197     case BLOCK_REPLICATION_FAILOVER_FAILED:
198         return s->mode == REPLICATION_MODE_PRIMARY ? -EIO : 1;
199     case BLOCK_REPLICATION_DONE:
200         /*
201          * active commit job completes, and active disk and secondary_disk
202          * is swapped, so we can operate bs->file directly
203          */
204         return s->mode == REPLICATION_MODE_PRIMARY ? -EIO : 0;
205     default:
206         abort();
207     }
208 }
209 
210 static int replication_return_value(BDRVReplicationState *s, int ret)
211 {
212     if (s->mode == REPLICATION_MODE_SECONDARY) {
213         return ret;
214     }
215 
216     if (ret < 0) {
217         s->error = ret;
218         ret = 0;
219     }
220 
221     return ret;
222 }
223 
224 static int coroutine_fn GRAPH_RDLOCK
225 replication_co_readv(BlockDriverState *bs, int64_t sector_num,
226                      int remaining_sectors, QEMUIOVector *qiov)
227 {
228     BDRVReplicationState *s = bs->opaque;
229     int ret;
230 
231     if (s->mode == REPLICATION_MODE_PRIMARY) {
232         /* We only use it to forward primary write requests */
233         return -EIO;
234     }
235 
236     ret = replication_get_io_status(s);
237     if (ret < 0) {
238         return ret;
239     }
240 
241     ret = bdrv_co_preadv(bs->file, sector_num * BDRV_SECTOR_SIZE,
242                          remaining_sectors * BDRV_SECTOR_SIZE, qiov, 0);
243 
244     return replication_return_value(s, ret);
245 }
246 
247 static int coroutine_fn GRAPH_RDLOCK
248 replication_co_writev(BlockDriverState *bs, int64_t sector_num,
249                       int remaining_sectors, QEMUIOVector *qiov, int flags)
250 {
251     BDRVReplicationState *s = bs->opaque;
252     QEMUIOVector hd_qiov;
253     uint64_t bytes_done = 0;
254     BdrvChild *top = bs->file;
255     BdrvChild *base = s->secondary_disk;
256     BdrvChild *target;
257     int ret;
258     int64_t n;
259 
260     ret = replication_get_io_status(s);
261     if (ret < 0) {
262         goto out;
263     }
264 
265     if (ret == 0) {
266         ret = bdrv_co_pwritev(top, sector_num * BDRV_SECTOR_SIZE,
267                               remaining_sectors * BDRV_SECTOR_SIZE, qiov, 0);
268         return replication_return_value(s, ret);
269     }
270 
271     /*
272      * Failover failed, only write to active disk if the sectors
273      * have already been allocated in active disk/hidden disk.
274      */
275     qemu_iovec_init(&hd_qiov, qiov->niov);
276     while (remaining_sectors > 0) {
277         int64_t count;
278 
279         ret = bdrv_is_allocated_above(top->bs, base->bs, false,
280                                       sector_num * BDRV_SECTOR_SIZE,
281                                       remaining_sectors * BDRV_SECTOR_SIZE,
282                                       &count);
283         if (ret < 0) {
284             goto out1;
285         }
286 
287         assert(QEMU_IS_ALIGNED(count, BDRV_SECTOR_SIZE));
288         n = count >> BDRV_SECTOR_BITS;
289         qemu_iovec_reset(&hd_qiov);
290         qemu_iovec_concat(&hd_qiov, qiov, bytes_done, count);
291 
292         target = ret ? top : base;
293         ret = bdrv_co_pwritev(target, sector_num * BDRV_SECTOR_SIZE,
294                               n * BDRV_SECTOR_SIZE, &hd_qiov, 0);
295         if (ret < 0) {
296             goto out1;
297         }
298 
299         remaining_sectors -= n;
300         sector_num += n;
301         bytes_done += count;
302     }
303 
304 out1:
305     qemu_iovec_destroy(&hd_qiov);
306 out:
307     return ret;
308 }
309 
310 static void secondary_do_checkpoint(BlockDriverState *bs, Error **errp)
311 {
312     BDRVReplicationState *s = bs->opaque;
313     BdrvChild *active_disk = bs->file;
314     Error *local_err = NULL;
315     int ret;
316 
317     if (!s->backup_job) {
318         error_setg(errp, "Backup job was cancelled unexpectedly");
319         return;
320     }
321 
322     backup_do_checkpoint(s->backup_job, &local_err);
323     if (local_err) {
324         error_propagate(errp, local_err);
325         return;
326     }
327 
328     if (!active_disk->bs->drv) {
329         error_setg(errp, "Active disk %s is ejected",
330                    active_disk->bs->node_name);
331         return;
332     }
333 
334     ret = bdrv_make_empty(active_disk, errp);
335     if (ret < 0) {
336         return;
337     }
338 
339     if (!s->hidden_disk->bs->drv) {
340         error_setg(errp, "Hidden disk %s is ejected",
341                    s->hidden_disk->bs->node_name);
342         return;
343     }
344 
345     ret = bdrv_make_empty(s->hidden_disk, errp);
346     if (ret < 0) {
347         return;
348     }
349 }
350 
351 /* This function is supposed to be called twice:
352  * first with writable = true, then with writable = false.
353  * The first call puts s->hidden_disk and s->secondary_disk in
354  * r/w mode, and the second puts them back in their original state.
355  */
356 static void reopen_backing_file(BlockDriverState *bs, bool writable,
357                                 Error **errp)
358 {
359     BDRVReplicationState *s = bs->opaque;
360     BdrvChild *hidden_disk, *secondary_disk;
361     BlockReopenQueue *reopen_queue = NULL;
362 
363     /*
364      * s->hidden_disk and s->secondary_disk may not be set yet, as they will
365      * only be set after the children are writable.
366      */
367     hidden_disk = bs->file->bs->backing;
368     secondary_disk = hidden_disk->bs->backing;
369 
370     if (writable) {
371         s->orig_hidden_read_only = bdrv_is_read_only(hidden_disk->bs);
372         s->orig_secondary_read_only = bdrv_is_read_only(secondary_disk->bs);
373     }
374 
375     if (s->orig_hidden_read_only) {
376         QDict *opts = qdict_new();
377         qdict_put_bool(opts, BDRV_OPT_READ_ONLY, !writable);
378         reopen_queue = bdrv_reopen_queue(reopen_queue, hidden_disk->bs,
379                                          opts, true);
380     }
381 
382     if (s->orig_secondary_read_only) {
383         QDict *opts = qdict_new();
384         qdict_put_bool(opts, BDRV_OPT_READ_ONLY, !writable);
385         reopen_queue = bdrv_reopen_queue(reopen_queue, secondary_disk->bs,
386                                          opts, true);
387     }
388 
389     if (reopen_queue) {
390         AioContext *ctx = bdrv_get_aio_context(bs);
391         if (ctx != qemu_get_aio_context()) {
392             aio_context_release(ctx);
393         }
394         bdrv_reopen_multiple(reopen_queue, errp);
395         if (ctx != qemu_get_aio_context()) {
396             aio_context_acquire(ctx);
397         }
398     }
399 }
400 
401 static void backup_job_cleanup(BlockDriverState *bs)
402 {
403     BDRVReplicationState *s = bs->opaque;
404     BlockDriverState *top_bs;
405 
406     s->backup_job = NULL;
407 
408     top_bs = bdrv_lookup_bs(s->top_id, s->top_id, NULL);
409     if (!top_bs) {
410         return;
411     }
412     bdrv_op_unblock_all(top_bs, s->blocker);
413     error_free(s->blocker);
414     reopen_backing_file(bs, false, NULL);
415 }
416 
417 static void backup_job_completed(void *opaque, int ret)
418 {
419     BlockDriverState *bs = opaque;
420     BDRVReplicationState *s = bs->opaque;
421 
422     if (s->stage != BLOCK_REPLICATION_FAILOVER) {
423         /* The backup job is cancelled unexpectedly */
424         s->error = -EIO;
425     }
426 
427     backup_job_cleanup(bs);
428 }
429 
430 static bool check_top_bs(BlockDriverState *top_bs, BlockDriverState *bs)
431 {
432     BdrvChild *child;
433 
434     /* The bs itself is the top_bs */
435     if (top_bs == bs) {
436         return true;
437     }
438 
439     /* Iterate over top_bs's children */
440     QLIST_FOREACH(child, &top_bs->children, next) {
441         if (child->bs == bs || check_top_bs(child->bs, bs)) {
442             return true;
443         }
444     }
445 
446     return false;
447 }
448 
449 static void replication_start(ReplicationState *rs, ReplicationMode mode,
450                               Error **errp)
451 {
452     BlockDriverState *bs = rs->opaque;
453     BDRVReplicationState *s;
454     BlockDriverState *top_bs;
455     BdrvChild *active_disk, *hidden_disk, *secondary_disk;
456     int64_t active_length, hidden_length, disk_length;
457     AioContext *aio_context;
458     Error *local_err = NULL;
459     BackupPerf perf = { .use_copy_range = true, .max_workers = 1 };
460 
461     aio_context = bdrv_get_aio_context(bs);
462     aio_context_acquire(aio_context);
463     s = bs->opaque;
464 
465     if (s->stage == BLOCK_REPLICATION_DONE ||
466         s->stage == BLOCK_REPLICATION_FAILOVER) {
467         /*
468          * This case happens when a secondary is promoted to primary.
469          * Ignore the request because the secondary side of replication
470          * doesn't have to do anything anymore.
471          */
472         aio_context_release(aio_context);
473         return;
474     }
475 
476     if (s->stage != BLOCK_REPLICATION_NONE) {
477         error_setg(errp, "Block replication is running or done");
478         aio_context_release(aio_context);
479         return;
480     }
481 
482     if (s->mode != mode) {
483         error_setg(errp, "The parameter mode's value is invalid, needs %d,"
484                    " but got %d", s->mode, mode);
485         aio_context_release(aio_context);
486         return;
487     }
488 
489     switch (s->mode) {
490     case REPLICATION_MODE_PRIMARY:
491         break;
492     case REPLICATION_MODE_SECONDARY:
493         active_disk = bs->file;
494         if (!active_disk || !active_disk->bs || !active_disk->bs->backing) {
495             error_setg(errp, "Active disk doesn't have backing file");
496             aio_context_release(aio_context);
497             return;
498         }
499 
500         hidden_disk = active_disk->bs->backing;
501         if (!hidden_disk->bs || !hidden_disk->bs->backing) {
502             error_setg(errp, "Hidden disk doesn't have backing file");
503             aio_context_release(aio_context);
504             return;
505         }
506 
507         secondary_disk = hidden_disk->bs->backing;
508         if (!secondary_disk->bs || !bdrv_has_blk(secondary_disk->bs)) {
509             error_setg(errp, "The secondary disk doesn't have block backend");
510             aio_context_release(aio_context);
511             return;
512         }
513 
514         /* verify the length */
515         active_length = bdrv_getlength(active_disk->bs);
516         hidden_length = bdrv_getlength(hidden_disk->bs);
517         disk_length = bdrv_getlength(secondary_disk->bs);
518         if (active_length < 0 || hidden_length < 0 || disk_length < 0 ||
519             active_length != hidden_length || hidden_length != disk_length) {
520             error_setg(errp, "Active disk, hidden disk, secondary disk's length"
521                        " are not the same");
522             aio_context_release(aio_context);
523             return;
524         }
525 
526         /* Must be true, or the bdrv_getlength() calls would have failed */
527         assert(active_disk->bs->drv && hidden_disk->bs->drv);
528 
529         if (!active_disk->bs->drv->bdrv_make_empty ||
530             !hidden_disk->bs->drv->bdrv_make_empty) {
531             error_setg(errp,
532                        "Active disk or hidden disk doesn't support make_empty");
533             aio_context_release(aio_context);
534             return;
535         }
536 
537         /* reopen the backing file in r/w mode */
538         reopen_backing_file(bs, true, &local_err);
539         if (local_err) {
540             error_propagate(errp, local_err);
541             aio_context_release(aio_context);
542             return;
543         }
544 
545         bdrv_ref(hidden_disk->bs);
546         s->hidden_disk = bdrv_attach_child(bs, hidden_disk->bs, "hidden disk",
547                                            &child_of_bds, BDRV_CHILD_DATA,
548                                            &local_err);
549         if (local_err) {
550             error_propagate(errp, local_err);
551             aio_context_release(aio_context);
552             return;
553         }
554 
555         bdrv_ref(secondary_disk->bs);
556         s->secondary_disk = bdrv_attach_child(bs, secondary_disk->bs,
557                                               "secondary disk", &child_of_bds,
558                                               BDRV_CHILD_DATA, &local_err);
559         if (local_err) {
560             error_propagate(errp, local_err);
561             aio_context_release(aio_context);
562             return;
563         }
564 
565         /* start backup job now */
566         error_setg(&s->blocker,
567                    "Block device is in use by internal backup job");
568 
569         top_bs = bdrv_lookup_bs(s->top_id, s->top_id, NULL);
570         if (!top_bs || !bdrv_is_root_node(top_bs) ||
571             !check_top_bs(top_bs, bs)) {
572             error_setg(errp, "No top_bs or it is invalid");
573             reopen_backing_file(bs, false, NULL);
574             aio_context_release(aio_context);
575             return;
576         }
577         bdrv_op_block_all(top_bs, s->blocker);
578         bdrv_op_unblock(top_bs, BLOCK_OP_TYPE_DATAPLANE, s->blocker);
579 
580         s->backup_job = backup_job_create(
581                                 NULL, s->secondary_disk->bs, s->hidden_disk->bs,
582                                 0, MIRROR_SYNC_MODE_NONE, NULL, 0, false, NULL,
583                                 &perf,
584                                 BLOCKDEV_ON_ERROR_REPORT,
585                                 BLOCKDEV_ON_ERROR_REPORT, JOB_INTERNAL,
586                                 backup_job_completed, bs, NULL, &local_err);
587         if (local_err) {
588             error_propagate(errp, local_err);
589             backup_job_cleanup(bs);
590             aio_context_release(aio_context);
591             return;
592         }
593         job_start(&s->backup_job->job);
594         break;
595     default:
596         aio_context_release(aio_context);
597         abort();
598     }
599 
600     s->stage = BLOCK_REPLICATION_RUNNING;
601 
602     if (s->mode == REPLICATION_MODE_SECONDARY) {
603         secondary_do_checkpoint(bs, errp);
604     }
605 
606     s->error = 0;
607     aio_context_release(aio_context);
608 }
609 
610 static void replication_do_checkpoint(ReplicationState *rs, Error **errp)
611 {
612     BlockDriverState *bs = rs->opaque;
613     BDRVReplicationState *s;
614     AioContext *aio_context;
615 
616     aio_context = bdrv_get_aio_context(bs);
617     aio_context_acquire(aio_context);
618     s = bs->opaque;
619 
620     if (s->stage == BLOCK_REPLICATION_DONE ||
621         s->stage == BLOCK_REPLICATION_FAILOVER) {
622         /*
623          * This case happens when a secondary was promoted to primary.
624          * Ignore the request because the secondary side of replication
625          * doesn't have to do anything anymore.
626          */
627         aio_context_release(aio_context);
628         return;
629     }
630 
631     if (s->mode == REPLICATION_MODE_SECONDARY) {
632         secondary_do_checkpoint(bs, errp);
633     }
634     aio_context_release(aio_context);
635 }
636 
637 static void replication_get_error(ReplicationState *rs, Error **errp)
638 {
639     BlockDriverState *bs = rs->opaque;
640     BDRVReplicationState *s;
641     AioContext *aio_context;
642 
643     aio_context = bdrv_get_aio_context(bs);
644     aio_context_acquire(aio_context);
645     s = bs->opaque;
646 
647     if (s->stage == BLOCK_REPLICATION_NONE) {
648         error_setg(errp, "Block replication is not running");
649         aio_context_release(aio_context);
650         return;
651     }
652 
653     if (s->error) {
654         error_setg(errp, "I/O error occurred");
655         aio_context_release(aio_context);
656         return;
657     }
658     aio_context_release(aio_context);
659 }
660 
661 static void replication_done(void *opaque, int ret)
662 {
663     BlockDriverState *bs = opaque;
664     BDRVReplicationState *s = bs->opaque;
665 
666     if (ret == 0) {
667         s->stage = BLOCK_REPLICATION_DONE;
668 
669         bdrv_unref_child(bs, s->secondary_disk);
670         s->secondary_disk = NULL;
671         bdrv_unref_child(bs, s->hidden_disk);
672         s->hidden_disk = NULL;
673         s->error = 0;
674     } else {
675         s->stage = BLOCK_REPLICATION_FAILOVER_FAILED;
676         s->error = -EIO;
677     }
678 }
679 
680 static void replication_stop(ReplicationState *rs, bool failover, Error **errp)
681 {
682     BlockDriverState *bs = rs->opaque;
683     BDRVReplicationState *s;
684     AioContext *aio_context;
685 
686     aio_context = bdrv_get_aio_context(bs);
687     aio_context_acquire(aio_context);
688     s = bs->opaque;
689 
690     if (s->stage == BLOCK_REPLICATION_DONE ||
691         s->stage == BLOCK_REPLICATION_FAILOVER) {
692         /*
693          * This case happens when a secondary was promoted to primary.
694          * Ignore the request because the secondary side of replication
695          * doesn't have to do anything anymore.
696          */
697         aio_context_release(aio_context);
698         return;
699     }
700 
701     if (s->stage != BLOCK_REPLICATION_RUNNING) {
702         error_setg(errp, "Block replication is not running");
703         aio_context_release(aio_context);
704         return;
705     }
706 
707     switch (s->mode) {
708     case REPLICATION_MODE_PRIMARY:
709         s->stage = BLOCK_REPLICATION_DONE;
710         s->error = 0;
711         break;
712     case REPLICATION_MODE_SECONDARY:
713         /*
714          * This BDS will be closed, and the job should be completed
715          * before the BDS is closed, because we will access hidden
716          * disk, secondary disk in backup_job_completed().
717          */
718         if (s->backup_job) {
719             aio_context_release(aio_context);
720             job_cancel_sync(&s->backup_job->job, true);
721             aio_context_acquire(aio_context);
722         }
723 
724         if (!failover) {
725             secondary_do_checkpoint(bs, errp);
726             s->stage = BLOCK_REPLICATION_DONE;
727             aio_context_release(aio_context);
728             return;
729         }
730 
731         s->stage = BLOCK_REPLICATION_FAILOVER;
732         s->commit_job = commit_active_start(
733                             NULL, bs->file->bs, s->secondary_disk->bs,
734                             JOB_INTERNAL, 0, BLOCKDEV_ON_ERROR_REPORT,
735                             NULL, replication_done, bs, true, errp);
736         break;
737     default:
738         aio_context_release(aio_context);
739         abort();
740     }
741     aio_context_release(aio_context);
742 }
743 
744 static const char *const replication_strong_runtime_opts[] = {
745     REPLICATION_MODE,
746     REPLICATION_TOP_ID,
747 
748     NULL
749 };
750 
751 static BlockDriver bdrv_replication = {
752     .format_name                = "replication",
753     .instance_size              = sizeof(BDRVReplicationState),
754 
755     .bdrv_open                  = replication_open,
756     .bdrv_close                 = replication_close,
757     .bdrv_child_perm            = replication_child_perm,
758 
759     .bdrv_co_getlength          = replication_co_getlength,
760     .bdrv_co_readv              = replication_co_readv,
761     .bdrv_co_writev             = replication_co_writev,
762 
763     .is_filter                  = true,
764 
765     .has_variable_length        = true,
766     .strong_runtime_opts        = replication_strong_runtime_opts,
767 };
768 
769 static void bdrv_replication_init(void)
770 {
771     bdrv_register(&bdrv_replication);
772 }
773 
774 block_init(bdrv_replication_init);
775