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15#include "qemu/osdep.h"
16#include "qemu/cutils.h"
17#include "trace.h"
18#include "block/block_int.h"
19#include "block/blockjob_int.h"
20#include "qapi/error.h"
21#include "qemu/ratelimit.h"
22#include "qemu/memalign.h"
23#include "sysemu/block-backend.h"
24
25enum {
26
27
28
29
30
31 COMMIT_BUFFER_SIZE = 512 * 1024,
32};
33
34typedef struct CommitBlockJob {
35 BlockJob common;
36 BlockDriverState *commit_top_bs;
37 BlockBackend *top;
38 BlockBackend *base;
39 BlockDriverState *base_bs;
40 BlockDriverState *base_overlay;
41 BlockdevOnError on_error;
42 bool base_read_only;
43 bool chain_frozen;
44 char *backing_file_str;
45} CommitBlockJob;
46
47static int commit_prepare(Job *job)
48{
49 CommitBlockJob *s = container_of(job, CommitBlockJob, common.job);
50
51 bdrv_unfreeze_backing_chain(s->commit_top_bs, s->base_bs);
52 s->chain_frozen = false;
53
54
55
56 blk_unref(s->base);
57 s->base = NULL;
58
59
60
61 return bdrv_drop_intermediate(s->commit_top_bs, s->base_bs,
62 s->backing_file_str);
63}
64
65static void commit_abort(Job *job)
66{
67 CommitBlockJob *s = container_of(job, CommitBlockJob, common.job);
68 BlockDriverState *top_bs = blk_bs(s->top);
69
70 if (s->chain_frozen) {
71 bdrv_unfreeze_backing_chain(s->commit_top_bs, s->base_bs);
72 }
73
74
75 bdrv_ref(top_bs);
76 bdrv_ref(s->commit_top_bs);
77
78 if (s->base) {
79 blk_unref(s->base);
80 }
81
82
83
84 block_job_remove_all_bdrv(&s->common);
85
86
87
88
89
90
91
92
93 bdrv_replace_node(s->commit_top_bs, s->commit_top_bs->backing->bs,
94 &error_abort);
95
96 bdrv_unref(s->commit_top_bs);
97 bdrv_unref(top_bs);
98}
99
100static void commit_clean(Job *job)
101{
102 CommitBlockJob *s = container_of(job, CommitBlockJob, common.job);
103
104
105
106
107 if (s->base_read_only) {
108 bdrv_reopen_set_read_only(s->base_bs, true, NULL);
109 }
110
111 g_free(s->backing_file_str);
112 blk_unref(s->top);
113}
114
115static int coroutine_fn commit_run(Job *job, Error **errp)
116{
117 CommitBlockJob *s = container_of(job, CommitBlockJob, common.job);
118 int64_t offset;
119 int ret = 0;
120 int64_t n = 0;
121 QEMU_AUTO_VFREE void *buf = NULL;
122 int64_t len, base_len;
123
124 len = blk_co_getlength(s->top);
125 if (len < 0) {
126 return len;
127 }
128 job_progress_set_remaining(&s->common.job, len);
129
130 base_len = blk_co_getlength(s->base);
131 if (base_len < 0) {
132 return base_len;
133 }
134
135 if (base_len < len) {
136 ret = blk_co_truncate(s->base, len, false, PREALLOC_MODE_OFF, 0, NULL);
137 if (ret) {
138 return ret;
139 }
140 }
141
142 buf = blk_blockalign(s->top, COMMIT_BUFFER_SIZE);
143
144 for (offset = 0; offset < len; offset += n) {
145 bool copy;
146 bool error_in_source = true;
147
148
149
150
151 block_job_ratelimit_sleep(&s->common);
152 if (job_is_cancelled(&s->common.job)) {
153 break;
154 }
155
156 ret = blk_co_is_allocated_above(s->top, s->base_overlay, true,
157 offset, COMMIT_BUFFER_SIZE, &n);
158 copy = (ret > 0);
159 trace_commit_one_iteration(s, offset, n, ret);
160 if (copy) {
161 assert(n < SIZE_MAX);
162
163 ret = blk_co_pread(s->top, offset, n, buf, 0);
164 if (ret >= 0) {
165 ret = blk_co_pwrite(s->base, offset, n, buf, 0);
166 if (ret < 0) {
167 error_in_source = false;
168 }
169 }
170 }
171 if (ret < 0) {
172 BlockErrorAction action =
173 block_job_error_action(&s->common, s->on_error,
174 error_in_source, -ret);
175 if (action == BLOCK_ERROR_ACTION_REPORT) {
176 return ret;
177 } else {
178 n = 0;
179 continue;
180 }
181 }
182
183 job_progress_update(&s->common.job, n);
184
185 if (copy) {
186 block_job_ratelimit_processed_bytes(&s->common, n);
187 }
188 }
189
190 return 0;
191}
192
193static const BlockJobDriver commit_job_driver = {
194 .job_driver = {
195 .instance_size = sizeof(CommitBlockJob),
196 .job_type = JOB_TYPE_COMMIT,
197 .free = block_job_free,
198 .user_resume = block_job_user_resume,
199 .run = commit_run,
200 .prepare = commit_prepare,
201 .abort = commit_abort,
202 .clean = commit_clean
203 },
204};
205
206static int coroutine_fn GRAPH_RDLOCK
207bdrv_commit_top_preadv(BlockDriverState *bs, int64_t offset, int64_t bytes,
208 QEMUIOVector *qiov, BdrvRequestFlags flags)
209{
210 return bdrv_co_preadv(bs->backing, offset, bytes, qiov, flags);
211}
212
213static void bdrv_commit_top_refresh_filename(BlockDriverState *bs)
214{
215 pstrcpy(bs->exact_filename, sizeof(bs->exact_filename),
216 bs->backing->bs->filename);
217}
218
219static void bdrv_commit_top_child_perm(BlockDriverState *bs, BdrvChild *c,
220 BdrvChildRole role,
221 BlockReopenQueue *reopen_queue,
222 uint64_t perm, uint64_t shared,
223 uint64_t *nperm, uint64_t *nshared)
224{
225 *nperm = 0;
226 *nshared = BLK_PERM_ALL;
227}
228
229
230
231static BlockDriver bdrv_commit_top = {
232 .format_name = "commit_top",
233 .bdrv_co_preadv = bdrv_commit_top_preadv,
234 .bdrv_refresh_filename = bdrv_commit_top_refresh_filename,
235 .bdrv_child_perm = bdrv_commit_top_child_perm,
236
237 .is_filter = true,
238 .filtered_child_is_backing = true,
239};
240
241void commit_start(const char *job_id, BlockDriverState *bs,
242 BlockDriverState *base, BlockDriverState *top,
243 int creation_flags, int64_t speed,
244 BlockdevOnError on_error, const char *backing_file_str,
245 const char *filter_node_name, Error **errp)
246{
247 CommitBlockJob *s;
248 BlockDriverState *iter;
249 BlockDriverState *commit_top_bs = NULL;
250 BlockDriverState *filtered_base;
251 int64_t base_size, top_size;
252 uint64_t base_perms, iter_shared_perms;
253 int ret;
254
255 GLOBAL_STATE_CODE();
256
257 assert(top != bs);
258 if (bdrv_skip_filters(top) == bdrv_skip_filters(base)) {
259 error_setg(errp, "Invalid files for merge: top and base are the same");
260 return;
261 }
262
263 base_size = bdrv_getlength(base);
264 if (base_size < 0) {
265 error_setg_errno(errp, -base_size, "Could not inquire base image size");
266 return;
267 }
268
269 top_size = bdrv_getlength(top);
270 if (top_size < 0) {
271 error_setg_errno(errp, -top_size, "Could not inquire top image size");
272 return;
273 }
274
275 base_perms = BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE;
276 if (base_size < top_size) {
277 base_perms |= BLK_PERM_RESIZE;
278 }
279
280 s = block_job_create(job_id, &commit_job_driver, NULL, bs, 0, BLK_PERM_ALL,
281 speed, creation_flags, NULL, NULL, errp);
282 if (!s) {
283 return;
284 }
285
286
287 s->base_read_only = bdrv_is_read_only(base);
288 if (s->base_read_only) {
289 if (bdrv_reopen_set_read_only(base, false, errp) != 0) {
290 goto fail;
291 }
292 }
293
294
295
296 commit_top_bs = bdrv_new_open_driver(&bdrv_commit_top, filter_node_name, 0,
297 errp);
298 if (commit_top_bs == NULL) {
299 goto fail;
300 }
301 if (!filter_node_name) {
302 commit_top_bs->implicit = true;
303 }
304
305
306 commit_top_bs->never_freeze = true;
307
308 commit_top_bs->total_sectors = top->total_sectors;
309
310 ret = bdrv_append(commit_top_bs, top, errp);
311 bdrv_unref(commit_top_bs);
312 if (ret < 0) {
313 commit_top_bs = NULL;
314 goto fail;
315 }
316
317 s->commit_top_bs = commit_top_bs;
318
319
320
321
322
323
324
325
326
327 s->base_overlay = bdrv_find_overlay(top, base);
328 assert(s->base_overlay);
329
330
331
332
333
334 filtered_base = bdrv_cow_bs(s->base_overlay);
335 assert(bdrv_skip_filters(filtered_base) == bdrv_skip_filters(base));
336
337
338
339
340
341
342
343 iter_shared_perms = BLK_PERM_WRITE_UNCHANGED | BLK_PERM_WRITE;
344
345 for (iter = top; iter != base; iter = bdrv_filter_or_cow_bs(iter)) {
346 if (iter == filtered_base) {
347
348
349
350
351 iter_shared_perms |= BLK_PERM_CONSISTENT_READ;
352 }
353
354 ret = block_job_add_bdrv(&s->common, "intermediate node", iter, 0,
355 iter_shared_perms, errp);
356 if (ret < 0) {
357 goto fail;
358 }
359 }
360
361 if (bdrv_freeze_backing_chain(commit_top_bs, base, errp) < 0) {
362 goto fail;
363 }
364 s->chain_frozen = true;
365
366 ret = block_job_add_bdrv(&s->common, "base", base, 0, BLK_PERM_ALL, errp);
367 if (ret < 0) {
368 goto fail;
369 }
370
371 s->base = blk_new(s->common.job.aio_context,
372 base_perms,
373 BLK_PERM_CONSISTENT_READ
374 | BLK_PERM_WRITE_UNCHANGED);
375 ret = blk_insert_bs(s->base, base, errp);
376 if (ret < 0) {
377 goto fail;
378 }
379 blk_set_disable_request_queuing(s->base, true);
380 s->base_bs = base;
381
382
383 s->top = blk_new(s->common.job.aio_context, 0, BLK_PERM_ALL);
384 ret = blk_insert_bs(s->top, top, errp);
385 if (ret < 0) {
386 goto fail;
387 }
388 blk_set_disable_request_queuing(s->top, true);
389
390 s->backing_file_str = g_strdup(backing_file_str);
391 s->on_error = on_error;
392
393 trace_commit_start(bs, base, top, s);
394 job_start(&s->common.job);
395 return;
396
397fail:
398 if (s->chain_frozen) {
399 bdrv_unfreeze_backing_chain(commit_top_bs, base);
400 }
401 if (s->base) {
402 blk_unref(s->base);
403 }
404 if (s->top) {
405 blk_unref(s->top);
406 }
407 if (s->base_read_only) {
408 bdrv_reopen_set_read_only(base, true, NULL);
409 }
410 job_early_fail(&s->common.job);
411
412
413 if (commit_top_bs) {
414 bdrv_replace_node(commit_top_bs, top, &error_abort);
415 }
416}
417
418
419#define COMMIT_BUF_SIZE (2048 * BDRV_SECTOR_SIZE)
420
421
422int bdrv_commit(BlockDriverState *bs)
423{
424 BlockBackend *src, *backing;
425 BlockDriverState *backing_file_bs = NULL;
426 BlockDriverState *commit_top_bs = NULL;
427 BlockDriver *drv = bs->drv;
428 AioContext *ctx;
429 int64_t offset, length, backing_length;
430 int ro;
431 int64_t n;
432 int ret = 0;
433 QEMU_AUTO_VFREE uint8_t *buf = NULL;
434 Error *local_err = NULL;
435
436 GLOBAL_STATE_CODE();
437
438 if (!drv)
439 return -ENOMEDIUM;
440
441 backing_file_bs = bdrv_cow_bs(bs);
442
443 if (!backing_file_bs) {
444 return -ENOTSUP;
445 }
446
447 if (bdrv_op_is_blocked(bs, BLOCK_OP_TYPE_COMMIT_SOURCE, NULL) ||
448 bdrv_op_is_blocked(backing_file_bs, BLOCK_OP_TYPE_COMMIT_TARGET, NULL))
449 {
450 return -EBUSY;
451 }
452
453 ro = bdrv_is_read_only(backing_file_bs);
454
455 if (ro) {
456 if (bdrv_reopen_set_read_only(backing_file_bs, false, NULL)) {
457 return -EACCES;
458 }
459 }
460
461 ctx = bdrv_get_aio_context(bs);
462
463 src = blk_new(ctx, BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE_UNCHANGED,
464 BLK_PERM_ALL);
465 backing = blk_new(ctx, BLK_PERM_WRITE | BLK_PERM_RESIZE, BLK_PERM_ALL);
466
467 ret = blk_insert_bs(src, bs, &local_err);
468 if (ret < 0) {
469 error_report_err(local_err);
470 goto ro_cleanup;
471 }
472
473
474 commit_top_bs = bdrv_new_open_driver(&bdrv_commit_top, NULL, BDRV_O_RDWR,
475 &local_err);
476 if (commit_top_bs == NULL) {
477 error_report_err(local_err);
478 goto ro_cleanup;
479 }
480
481 bdrv_set_backing_hd(commit_top_bs, backing_file_bs, &error_abort);
482 bdrv_set_backing_hd(bs, commit_top_bs, &error_abort);
483
484 ret = blk_insert_bs(backing, backing_file_bs, &local_err);
485 if (ret < 0) {
486 error_report_err(local_err);
487 goto ro_cleanup;
488 }
489
490 length = blk_getlength(src);
491 if (length < 0) {
492 ret = length;
493 goto ro_cleanup;
494 }
495
496 backing_length = blk_getlength(backing);
497 if (backing_length < 0) {
498 ret = backing_length;
499 goto ro_cleanup;
500 }
501
502
503
504
505 if (length > backing_length) {
506 ret = blk_truncate(backing, length, false, PREALLOC_MODE_OFF, 0,
507 &local_err);
508 if (ret < 0) {
509 error_report_err(local_err);
510 goto ro_cleanup;
511 }
512 }
513
514
515
516 buf = blk_try_blockalign(src, COMMIT_BUF_SIZE);
517 if (buf == NULL) {
518 ret = -ENOMEM;
519 goto ro_cleanup;
520 }
521
522 for (offset = 0; offset < length; offset += n) {
523 ret = bdrv_is_allocated(bs, offset, COMMIT_BUF_SIZE, &n);
524 if (ret < 0) {
525 goto ro_cleanup;
526 }
527 if (ret) {
528 ret = blk_pread(src, offset, n, buf, 0);
529 if (ret < 0) {
530 goto ro_cleanup;
531 }
532
533 ret = blk_pwrite(backing, offset, n, buf, 0);
534 if (ret < 0) {
535 goto ro_cleanup;
536 }
537 }
538 }
539
540 ret = blk_make_empty(src, NULL);
541
542 if (ret < 0 && ret != -ENOTSUP) {
543 goto ro_cleanup;
544 }
545
546 blk_flush(src);
547
548
549
550
551
552 blk_flush(backing);
553
554 ret = 0;
555ro_cleanup:
556 blk_unref(backing);
557 if (bdrv_cow_bs(bs) != backing_file_bs) {
558 bdrv_set_backing_hd(bs, backing_file_bs, &error_abort);
559 }
560 bdrv_unref(commit_top_bs);
561 blk_unref(src);
562
563 if (ro) {
564
565 bdrv_reopen_set_read_only(backing_file_bs, true, NULL);
566 }
567
568 return ret;
569}
570