Update VERSION for v7.2.0-rc4
[qemu.git] / block / backup.c
1 /*
2 * QEMU backup
3 *
4 * Copyright (C) 2013 Proxmox Server Solutions
5 *
6 * Authors:
7 * Dietmar Maurer (dietmar@proxmox.com)
8 *
9 * This work is licensed under the terms of the GNU GPL, version 2 or later.
10 * See the COPYING file in the top-level directory.
11 *
12 */
13
14 #include <stdio.h>
15 #include <errno.h>
16 #include <unistd.h>
17
18 #include "trace.h"
19 #include "block/block.h"
20 #include "block/block_int.h"
21 #include "block/blockjob.h"
22 #include "qapi/qmp/qerror.h"
23 #include "qemu/ratelimit.h"
24
25 #define BACKUP_CLUSTER_BITS 16
26 #define BACKUP_CLUSTER_SIZE (1 << BACKUP_CLUSTER_BITS)
27 #define BACKUP_SECTORS_PER_CLUSTER (BACKUP_CLUSTER_SIZE / BDRV_SECTOR_SIZE)
28
29 #define SLICE_TIME 100000000ULL /* ns */
30
31 typedef struct CowRequest {
32 int64_t start;
33 int64_t end;
34 QLIST_ENTRY(CowRequest) list;
35 CoQueue wait_queue; /* coroutines blocked on this request */
36 } CowRequest;
37
38 typedef struct BackupBlockJob {
39 BlockJob common;
40 BlockDriverState *target;
41 /* bitmap for sync=incremental */
42 BdrvDirtyBitmap *sync_bitmap;
43 MirrorSyncMode sync_mode;
44 RateLimit limit;
45 BlockdevOnError on_source_error;
46 BlockdevOnError on_target_error;
47 CoRwlock flush_rwlock;
48 uint64_t sectors_read;
49 HBitmap *bitmap;
50 QLIST_HEAD(, CowRequest) inflight_reqs;
51 } BackupBlockJob;
52
53 /* See if in-flight requests overlap and wait for them to complete */
54 static void coroutine_fn wait_for_overlapping_requests(BackupBlockJob *job,
55 int64_t start,
56 int64_t end)
57 {
58 CowRequest *req;
59 bool retry;
60
61 do {
62 retry = false;
63 QLIST_FOREACH(req, &job->inflight_reqs, list) {
64 if (end > req->start && start < req->end) {
65 qemu_co_queue_wait(&req->wait_queue);
66 retry = true;
67 break;
68 }
69 }
70 } while (retry);
71 }
72
73 /* Keep track of an in-flight request */
74 static void cow_request_begin(CowRequest *req, BackupBlockJob *job,
75 int64_t start, int64_t end)
76 {
77 req->start = start;
78 req->end = end;
79 qemu_co_queue_init(&req->wait_queue);
80 QLIST_INSERT_HEAD(&job->inflight_reqs, req, list);
81 }
82
83 /* Forget about a completed request */
84 static void cow_request_end(CowRequest *req)
85 {
86 QLIST_REMOVE(req, list);
87 qemu_co_queue_restart_all(&req->wait_queue);
88 }
89
90 static int coroutine_fn backup_do_cow(BlockDriverState *bs,
91 int64_t sector_num, int nb_sectors,
92 bool *error_is_read)
93 {
94 BackupBlockJob *job = (BackupBlockJob *)bs->job;
95 CowRequest cow_request;
96 struct iovec iov;
97 QEMUIOVector bounce_qiov;
98 void *bounce_buffer = NULL;
99 int ret = 0;
100 int64_t start, end;
101 int n;
102
103 qemu_co_rwlock_rdlock(&job->flush_rwlock);
104
105 start = sector_num / BACKUP_SECTORS_PER_CLUSTER;
106 end = DIV_ROUND_UP(sector_num + nb_sectors, BACKUP_SECTORS_PER_CLUSTER);
107
108 trace_backup_do_cow_enter(job, start, sector_num, nb_sectors);
109
110 wait_for_overlapping_requests(job, start, end);
111 cow_request_begin(&cow_request, job, start, end);
112
113 for (; start < end; start++) {
114 if (hbitmap_get(job->bitmap, start)) {
115 trace_backup_do_cow_skip(job, start);
116 continue; /* already copied */
117 }
118
119 trace_backup_do_cow_process(job, start);
120
121 n = MIN(BACKUP_SECTORS_PER_CLUSTER,
122 job->common.len / BDRV_SECTOR_SIZE -
123 start * BACKUP_SECTORS_PER_CLUSTER);
124
125 if (!bounce_buffer) {
126 bounce_buffer = qemu_blockalign(bs, BACKUP_CLUSTER_SIZE);
127 }
128 iov.iov_base = bounce_buffer;
129 iov.iov_len = n * BDRV_SECTOR_SIZE;
130 qemu_iovec_init_external(&bounce_qiov, &iov, 1);
131
132 ret = bdrv_co_readv(bs, start * BACKUP_SECTORS_PER_CLUSTER, n,
133 &bounce_qiov);
134 if (ret < 0) {
135 trace_backup_do_cow_read_fail(job, start, ret);
136 if (error_is_read) {
137 *error_is_read = true;
138 }
139 goto out;
140 }
141
142 if (buffer_is_zero(iov.iov_base, iov.iov_len)) {
143 ret = bdrv_co_write_zeroes(job->target,
144 start * BACKUP_SECTORS_PER_CLUSTER,
145 n, BDRV_REQ_MAY_UNMAP);
146 } else {
147 ret = bdrv_co_writev(job->target,
148 start * BACKUP_SECTORS_PER_CLUSTER, n,
149 &bounce_qiov);
150 }
151 if (ret < 0) {
152 trace_backup_do_cow_write_fail(job, start, ret);
153 if (error_is_read) {
154 *error_is_read = false;
155 }
156 goto out;
157 }
158
159 hbitmap_set(job->bitmap, start, 1);
160
161 /* Publish progress, guest I/O counts as progress too. Note that the
162 * offset field is an opaque progress value, it is not a disk offset.
163 */
164 job->sectors_read += n;
165 job->common.offset += n * BDRV_SECTOR_SIZE;
166 }
167
168 out:
169 if (bounce_buffer) {
170 qemu_vfree(bounce_buffer);
171 }
172
173 cow_request_end(&cow_request);
174
175 trace_backup_do_cow_return(job, sector_num, nb_sectors, ret);
176
177 qemu_co_rwlock_unlock(&job->flush_rwlock);
178
179 return ret;
180 }
181
182 static int coroutine_fn backup_before_write_notify(
183 NotifierWithReturn *notifier,
184 void *opaque)
185 {
186 BdrvTrackedRequest *req = opaque;
187 int64_t sector_num = req->offset >> BDRV_SECTOR_BITS;
188 int nb_sectors = req->bytes >> BDRV_SECTOR_BITS;
189
190 assert((req->offset & (BDRV_SECTOR_SIZE - 1)) == 0);
191 assert((req->bytes & (BDRV_SECTOR_SIZE - 1)) == 0);
192
193 return backup_do_cow(req->bs, sector_num, nb_sectors, NULL);
194 }
195
196 static void backup_set_speed(BlockJob *job, int64_t speed, Error **errp)
197 {
198 BackupBlockJob *s = container_of(job, BackupBlockJob, common);
199
200 if (speed < 0) {
201 error_setg(errp, QERR_INVALID_PARAMETER, "speed");
202 return;
203 }
204 ratelimit_set_speed(&s->limit, speed / BDRV_SECTOR_SIZE, SLICE_TIME);
205 }
206
207 static void backup_iostatus_reset(BlockJob *job)
208 {
209 BackupBlockJob *s = container_of(job, BackupBlockJob, common);
210
211 bdrv_iostatus_reset(s->target);
212 }
213
214 static const BlockJobDriver backup_job_driver = {
215 .instance_size = sizeof(BackupBlockJob),
216 .job_type = BLOCK_JOB_TYPE_BACKUP,
217 .set_speed = backup_set_speed,
218 .iostatus_reset = backup_iostatus_reset,
219 };
220
221 static BlockErrorAction backup_error_action(BackupBlockJob *job,
222 bool read, int error)
223 {
224 if (read) {
225 return block_job_error_action(&job->common, job->common.bs,
226 job->on_source_error, true, error);
227 } else {
228 return block_job_error_action(&job->common, job->target,
229 job->on_target_error, false, error);
230 }
231 }
232
233 typedef struct {
234 int ret;
235 } BackupCompleteData;
236
237 static void backup_complete(BlockJob *job, void *opaque)
238 {
239 BackupBlockJob *s = container_of(job, BackupBlockJob, common);
240 BackupCompleteData *data = opaque;
241
242 bdrv_unref(s->target);
243
244 block_job_completed(job, data->ret);
245 g_free(data);
246 }
247
248 static bool coroutine_fn yield_and_check(BackupBlockJob *job)
249 {
250 if (block_job_is_cancelled(&job->common)) {
251 return true;
252 }
253
254 /* we need to yield so that bdrv_drain_all() returns.
255 * (without, VM does not reboot)
256 */
257 if (job->common.speed) {
258 uint64_t delay_ns = ratelimit_calculate_delay(&job->limit,
259 job->sectors_read);
260 job->sectors_read = 0;
261 block_job_sleep_ns(&job->common, QEMU_CLOCK_REALTIME, delay_ns);
262 } else {
263 block_job_sleep_ns(&job->common, QEMU_CLOCK_REALTIME, 0);
264 }
265
266 if (block_job_is_cancelled(&job->common)) {
267 return true;
268 }
269
270 return false;
271 }
272
273 static int coroutine_fn backup_run_incremental(BackupBlockJob *job)
274 {
275 bool error_is_read;
276 int ret = 0;
277 int clusters_per_iter;
278 uint32_t granularity;
279 int64_t sector;
280 int64_t cluster;
281 int64_t end;
282 int64_t last_cluster = -1;
283 BlockDriverState *bs = job->common.bs;
284 HBitmapIter hbi;
285
286 granularity = bdrv_dirty_bitmap_granularity(job->sync_bitmap);
287 clusters_per_iter = MAX((granularity / BACKUP_CLUSTER_SIZE), 1);
288 bdrv_dirty_iter_init(job->sync_bitmap, &hbi);
289
290 /* Find the next dirty sector(s) */
291 while ((sector = hbitmap_iter_next(&hbi)) != -1) {
292 cluster = sector / BACKUP_SECTORS_PER_CLUSTER;
293
294 /* Fake progress updates for any clusters we skipped */
295 if (cluster != last_cluster + 1) {
296 job->common.offset += ((cluster - last_cluster - 1) *
297 BACKUP_CLUSTER_SIZE);
298 }
299
300 for (end = cluster + clusters_per_iter; cluster < end; cluster++) {
301 do {
302 if (yield_and_check(job)) {
303 return ret;
304 }
305 ret = backup_do_cow(bs, cluster * BACKUP_SECTORS_PER_CLUSTER,
306 BACKUP_SECTORS_PER_CLUSTER, &error_is_read);
307 if ((ret < 0) &&
308 backup_error_action(job, error_is_read, -ret) ==
309 BLOCK_ERROR_ACTION_REPORT) {
310 return ret;
311 }
312 } while (ret < 0);
313 }
314
315 /* If the bitmap granularity is smaller than the backup granularity,
316 * we need to advance the iterator pointer to the next cluster. */
317 if (granularity < BACKUP_CLUSTER_SIZE) {
318 bdrv_set_dirty_iter(&hbi, cluster * BACKUP_SECTORS_PER_CLUSTER);
319 }
320
321 last_cluster = cluster - 1;
322 }
323
324 /* Play some final catchup with the progress meter */
325 end = DIV_ROUND_UP(job->common.len, BACKUP_CLUSTER_SIZE);
326 if (last_cluster + 1 < end) {
327 job->common.offset += ((end - last_cluster - 1) * BACKUP_CLUSTER_SIZE);
328 }
329
330 return ret;
331 }
332
333 static void coroutine_fn backup_run(void *opaque)
334 {
335 BackupBlockJob *job = opaque;
336 BackupCompleteData *data;
337 BlockDriverState *bs = job->common.bs;
338 BlockDriverState *target = job->target;
339 BlockdevOnError on_target_error = job->on_target_error;
340 NotifierWithReturn before_write = {
341 .notify = backup_before_write_notify,
342 };
343 int64_t start, end;
344 int ret = 0;
345
346 QLIST_INIT(&job->inflight_reqs);
347 qemu_co_rwlock_init(&job->flush_rwlock);
348
349 start = 0;
350 end = DIV_ROUND_UP(job->common.len, BACKUP_CLUSTER_SIZE);
351
352 job->bitmap = hbitmap_alloc(end, 0);
353
354 bdrv_set_enable_write_cache(target, true);
355 bdrv_set_on_error(target, on_target_error, on_target_error);
356 bdrv_iostatus_enable(target);
357
358 bdrv_add_before_write_notifier(bs, &before_write);
359
360 if (job->sync_mode == MIRROR_SYNC_MODE_NONE) {
361 while (!block_job_is_cancelled(&job->common)) {
362 /* Yield until the job is cancelled. We just let our before_write
363 * notify callback service CoW requests. */
364 job->common.busy = false;
365 qemu_coroutine_yield();
366 job->common.busy = true;
367 }
368 } else if (job->sync_mode == MIRROR_SYNC_MODE_INCREMENTAL) {
369 ret = backup_run_incremental(job);
370 } else {
371 /* Both FULL and TOP SYNC_MODE's require copying.. */
372 for (; start < end; start++) {
373 bool error_is_read;
374 if (yield_and_check(job)) {
375 break;
376 }
377
378 if (job->sync_mode == MIRROR_SYNC_MODE_TOP) {
379 int i, n;
380 int alloced = 0;
381
382 /* Check to see if these blocks are already in the
383 * backing file. */
384
385 for (i = 0; i < BACKUP_SECTORS_PER_CLUSTER;) {
386 /* bdrv_is_allocated() only returns true/false based
387 * on the first set of sectors it comes across that
388 * are are all in the same state.
389 * For that reason we must verify each sector in the
390 * backup cluster length. We end up copying more than
391 * needed but at some point that is always the case. */
392 alloced =
393 bdrv_is_allocated(bs,
394 start * BACKUP_SECTORS_PER_CLUSTER + i,
395 BACKUP_SECTORS_PER_CLUSTER - i, &n);
396 i += n;
397
398 if (alloced == 1 || n == 0) {
399 break;
400 }
401 }
402
403 /* If the above loop never found any sectors that are in
404 * the topmost image, skip this backup. */
405 if (alloced == 0) {
406 continue;
407 }
408 }
409 /* FULL sync mode we copy the whole drive. */
410 ret = backup_do_cow(bs, start * BACKUP_SECTORS_PER_CLUSTER,
411 BACKUP_SECTORS_PER_CLUSTER, &error_is_read);
412 if (ret < 0) {
413 /* Depending on error action, fail now or retry cluster */
414 BlockErrorAction action =
415 backup_error_action(job, error_is_read, -ret);
416 if (action == BLOCK_ERROR_ACTION_REPORT) {
417 break;
418 } else {
419 start--;
420 continue;
421 }
422 }
423 }
424 }
425
426 notifier_with_return_remove(&before_write);
427
428 /* wait until pending backup_do_cow() calls have completed */
429 qemu_co_rwlock_wrlock(&job->flush_rwlock);
430 qemu_co_rwlock_unlock(&job->flush_rwlock);
431
432 if (job->sync_bitmap) {
433 BdrvDirtyBitmap *bm;
434 if (ret < 0 || block_job_is_cancelled(&job->common)) {
435 /* Merge the successor back into the parent, delete nothing. */
436 bm = bdrv_reclaim_dirty_bitmap(bs, job->sync_bitmap, NULL);
437 assert(bm);
438 } else {
439 /* Everything is fine, delete this bitmap and install the backup. */
440 bm = bdrv_dirty_bitmap_abdicate(bs, job->sync_bitmap, NULL);
441 assert(bm);
442 }
443 }
444 hbitmap_free(job->bitmap);
445
446 bdrv_iostatus_disable(target);
447 bdrv_op_unblock_all(target, job->common.blocker);
448
449 data = g_malloc(sizeof(*data));
450 data->ret = ret;
451 block_job_defer_to_main_loop(&job->common, backup_complete, data);
452 }
453
454 void backup_start(BlockDriverState *bs, BlockDriverState *target,
455 int64_t speed, MirrorSyncMode sync_mode,
456 BdrvDirtyBitmap *sync_bitmap,
457 BlockdevOnError on_source_error,
458 BlockdevOnError on_target_error,
459 BlockCompletionFunc *cb, void *opaque,
460 Error **errp)
461 {
462 int64_t len;
463
464 assert(bs);
465 assert(target);
466 assert(cb);
467
468 if (bs == target) {
469 error_setg(errp, "Source and target cannot be the same");
470 return;
471 }
472
473 if ((on_source_error == BLOCKDEV_ON_ERROR_STOP ||
474 on_source_error == BLOCKDEV_ON_ERROR_ENOSPC) &&
475 !bdrv_iostatus_is_enabled(bs)) {
476 error_setg(errp, QERR_INVALID_PARAMETER, "on-source-error");
477 return;
478 }
479
480 if (!bdrv_is_inserted(bs)) {
481 error_setg(errp, "Device is not inserted: %s",
482 bdrv_get_device_name(bs));
483 return;
484 }
485
486 if (!bdrv_is_inserted(target)) {
487 error_setg(errp, "Device is not inserted: %s",
488 bdrv_get_device_name(target));
489 return;
490 }
491
492 if (bdrv_op_is_blocked(bs, BLOCK_OP_TYPE_BACKUP_SOURCE, errp)) {
493 return;
494 }
495
496 if (bdrv_op_is_blocked(target, BLOCK_OP_TYPE_BACKUP_TARGET, errp)) {
497 return;
498 }
499
500 if (sync_mode == MIRROR_SYNC_MODE_INCREMENTAL) {
501 if (!sync_bitmap) {
502 error_setg(errp, "must provide a valid bitmap name for "
503 "\"incremental\" sync mode");
504 return;
505 }
506
507 /* Create a new bitmap, and freeze/disable this one. */
508 if (bdrv_dirty_bitmap_create_successor(bs, sync_bitmap, errp) < 0) {
509 return;
510 }
511 } else if (sync_bitmap) {
512 error_setg(errp,
513 "a sync_bitmap was provided to backup_run, "
514 "but received an incompatible sync_mode (%s)",
515 MirrorSyncMode_lookup[sync_mode]);
516 return;
517 }
518
519 len = bdrv_getlength(bs);
520 if (len < 0) {
521 error_setg_errno(errp, -len, "unable to get length for '%s'",
522 bdrv_get_device_name(bs));
523 goto error;
524 }
525
526 BackupBlockJob *job = block_job_create(&backup_job_driver, bs, speed,
527 cb, opaque, errp);
528 if (!job) {
529 goto error;
530 }
531
532 bdrv_op_block_all(target, job->common.blocker);
533
534 job->on_source_error = on_source_error;
535 job->on_target_error = on_target_error;
536 job->target = target;
537 job->sync_mode = sync_mode;
538 job->sync_bitmap = sync_mode == MIRROR_SYNC_MODE_INCREMENTAL ?
539 sync_bitmap : NULL;
540 job->common.len = len;
541 job->common.co = qemu_coroutine_create(backup_run);
542 qemu_coroutine_enter(job->common.co, job);
543 return;
544
545 error:
546 if (sync_bitmap) {
547 bdrv_reclaim_dirty_bitmap(bs, sync_bitmap, NULL);
548 }
549 }