1 | /* |
2 | * Block layer snapshot related functions |
3 | * |
4 | * Copyright (c) 2003-2008 Fabrice Bellard |
5 | * |
6 | * Permission is hereby granted, free of charge, to any person obtaining a copy |
7 | * of this software and associated documentation files (the "Software"), to deal |
8 | * in the Software without restriction, including without limitation the rights |
9 | * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell |
10 | * copies of the Software, and to permit persons to whom the Software is |
11 | * furnished to do so, subject to the following conditions: |
12 | * |
13 | * The above copyright notice and this permission notice shall be included in |
14 | * all copies or substantial portions of the Software. |
15 | * |
16 | * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR |
17 | * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
18 | * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL |
19 | * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER |
20 | * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, |
21 | * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN |
22 | * THE SOFTWARE. |
23 | */ |
24 | |
25 | #include "qemu/osdep.h" |
26 | #include "block/snapshot.h" |
27 | #include "block/block_int.h" |
28 | #include "block/qdict.h" |
29 | #include "qapi/error.h" |
30 | #include "qapi/qmp/qdict.h" |
31 | #include "qapi/qmp/qerror.h" |
32 | #include "qapi/qmp/qstring.h" |
33 | #include "qemu/option.h" |
34 | |
35 | QemuOptsList internal_snapshot_opts = { |
36 | .name = "snapshot" , |
37 | .head = QTAILQ_HEAD_INITIALIZER(internal_snapshot_opts.head), |
38 | .desc = { |
39 | { |
40 | .name = SNAPSHOT_OPT_ID, |
41 | .type = QEMU_OPT_STRING, |
42 | .help = "snapshot id" |
43 | },{ |
44 | .name = SNAPSHOT_OPT_NAME, |
45 | .type = QEMU_OPT_STRING, |
46 | .help = "snapshot name" |
47 | },{ |
48 | /* end of list */ |
49 | } |
50 | }, |
51 | }; |
52 | |
53 | int bdrv_snapshot_find(BlockDriverState *bs, QEMUSnapshotInfo *sn_info, |
54 | const char *name) |
55 | { |
56 | QEMUSnapshotInfo *sn_tab, *sn; |
57 | int nb_sns, i, ret; |
58 | |
59 | ret = -ENOENT; |
60 | nb_sns = bdrv_snapshot_list(bs, &sn_tab); |
61 | if (nb_sns < 0) { |
62 | return ret; |
63 | } |
64 | for (i = 0; i < nb_sns; i++) { |
65 | sn = &sn_tab[i]; |
66 | if (!strcmp(sn->name, name)) { |
67 | *sn_info = *sn; |
68 | ret = 0; |
69 | break; |
70 | } |
71 | } |
72 | g_free(sn_tab); |
73 | return ret; |
74 | } |
75 | |
76 | /** |
77 | * Look up an internal snapshot by @id and @name. |
78 | * @bs: block device to search |
79 | * @id: unique snapshot ID, or NULL |
80 | * @name: snapshot name, or NULL |
81 | * @sn_info: location to store information on the snapshot found |
82 | * @errp: location to store error, will be set only for exception |
83 | * |
84 | * This function will traverse snapshot list in @bs to search the matching |
85 | * one, @id and @name are the matching condition: |
86 | * If both @id and @name are specified, find the first one with id @id and |
87 | * name @name. |
88 | * If only @id is specified, find the first one with id @id. |
89 | * If only @name is specified, find the first one with name @name. |
90 | * if none is specified, abort(). |
91 | * |
92 | * Returns: true when a snapshot is found and @sn_info will be filled, false |
93 | * when error or not found. If all operation succeed but no matching one is |
94 | * found, @errp will NOT be set. |
95 | */ |
96 | bool bdrv_snapshot_find_by_id_and_name(BlockDriverState *bs, |
97 | const char *id, |
98 | const char *name, |
99 | QEMUSnapshotInfo *sn_info, |
100 | Error **errp) |
101 | { |
102 | QEMUSnapshotInfo *sn_tab, *sn; |
103 | int nb_sns, i; |
104 | bool ret = false; |
105 | |
106 | assert(id || name); |
107 | |
108 | nb_sns = bdrv_snapshot_list(bs, &sn_tab); |
109 | if (nb_sns < 0) { |
110 | error_setg_errno(errp, -nb_sns, "Failed to get a snapshot list" ); |
111 | return false; |
112 | } else if (nb_sns == 0) { |
113 | return false; |
114 | } |
115 | |
116 | if (id && name) { |
117 | for (i = 0; i < nb_sns; i++) { |
118 | sn = &sn_tab[i]; |
119 | if (!strcmp(sn->id_str, id) && !strcmp(sn->name, name)) { |
120 | *sn_info = *sn; |
121 | ret = true; |
122 | break; |
123 | } |
124 | } |
125 | } else if (id) { |
126 | for (i = 0; i < nb_sns; i++) { |
127 | sn = &sn_tab[i]; |
128 | if (!strcmp(sn->id_str, id)) { |
129 | *sn_info = *sn; |
130 | ret = true; |
131 | break; |
132 | } |
133 | } |
134 | } else if (name) { |
135 | for (i = 0; i < nb_sns; i++) { |
136 | sn = &sn_tab[i]; |
137 | if (!strcmp(sn->name, name)) { |
138 | *sn_info = *sn; |
139 | ret = true; |
140 | break; |
141 | } |
142 | } |
143 | } |
144 | |
145 | g_free(sn_tab); |
146 | return ret; |
147 | } |
148 | |
149 | int bdrv_can_snapshot(BlockDriverState *bs) |
150 | { |
151 | BlockDriver *drv = bs->drv; |
152 | if (!drv || !bdrv_is_inserted(bs) || bdrv_is_read_only(bs)) { |
153 | return 0; |
154 | } |
155 | |
156 | if (!drv->bdrv_snapshot_create) { |
157 | if (bs->file != NULL) { |
158 | return bdrv_can_snapshot(bs->file->bs); |
159 | } |
160 | return 0; |
161 | } |
162 | |
163 | return 1; |
164 | } |
165 | |
166 | int bdrv_snapshot_create(BlockDriverState *bs, |
167 | QEMUSnapshotInfo *sn_info) |
168 | { |
169 | BlockDriver *drv = bs->drv; |
170 | if (!drv) { |
171 | return -ENOMEDIUM; |
172 | } |
173 | if (drv->bdrv_snapshot_create) { |
174 | return drv->bdrv_snapshot_create(bs, sn_info); |
175 | } |
176 | if (bs->file) { |
177 | return bdrv_snapshot_create(bs->file->bs, sn_info); |
178 | } |
179 | return -ENOTSUP; |
180 | } |
181 | |
182 | int bdrv_snapshot_goto(BlockDriverState *bs, |
183 | const char *snapshot_id, |
184 | Error **errp) |
185 | { |
186 | BlockDriver *drv = bs->drv; |
187 | int ret, open_ret; |
188 | |
189 | if (!drv) { |
190 | error_setg(errp, "Block driver is closed" ); |
191 | return -ENOMEDIUM; |
192 | } |
193 | |
194 | if (!QLIST_EMPTY(&bs->dirty_bitmaps)) { |
195 | error_setg(errp, "Device has active dirty bitmaps" ); |
196 | return -EBUSY; |
197 | } |
198 | |
199 | if (drv->bdrv_snapshot_goto) { |
200 | ret = drv->bdrv_snapshot_goto(bs, snapshot_id); |
201 | if (ret < 0) { |
202 | error_setg_errno(errp, -ret, "Failed to load snapshot" ); |
203 | } |
204 | return ret; |
205 | } |
206 | |
207 | if (bs->file) { |
208 | BlockDriverState *file; |
209 | QDict *options = qdict_clone_shallow(bs->options); |
210 | QDict *file_options; |
211 | Error *local_err = NULL; |
212 | |
213 | file = bs->file->bs; |
214 | /* Prevent it from getting deleted when detached from bs */ |
215 | bdrv_ref(file); |
216 | |
217 | qdict_extract_subqdict(options, &file_options, "file." ); |
218 | qobject_unref(file_options); |
219 | qdict_put_str(options, "file" , bdrv_get_node_name(file)); |
220 | |
221 | if (drv->bdrv_close) { |
222 | drv->bdrv_close(bs); |
223 | } |
224 | bdrv_unref_child(bs, bs->file); |
225 | bs->file = NULL; |
226 | |
227 | ret = bdrv_snapshot_goto(file, snapshot_id, errp); |
228 | open_ret = drv->bdrv_open(bs, options, bs->open_flags, &local_err); |
229 | qobject_unref(options); |
230 | if (open_ret < 0) { |
231 | bdrv_unref(file); |
232 | bs->drv = NULL; |
233 | /* A bdrv_snapshot_goto() error takes precedence */ |
234 | error_propagate(errp, local_err); |
235 | return ret < 0 ? ret : open_ret; |
236 | } |
237 | |
238 | assert(bs->file->bs == file); |
239 | bdrv_unref(file); |
240 | return ret; |
241 | } |
242 | |
243 | error_setg(errp, "Block driver does not support snapshots" ); |
244 | return -ENOTSUP; |
245 | } |
246 | |
247 | /** |
248 | * Delete an internal snapshot by @snapshot_id and @name. |
249 | * @bs: block device used in the operation |
250 | * @snapshot_id: unique snapshot ID, or NULL |
251 | * @name: snapshot name, or NULL |
252 | * @errp: location to store error |
253 | * |
254 | * If both @snapshot_id and @name are specified, delete the first one with |
255 | * id @snapshot_id and name @name. |
256 | * If only @snapshot_id is specified, delete the first one with id |
257 | * @snapshot_id. |
258 | * If only @name is specified, delete the first one with name @name. |
259 | * if none is specified, return -EINVAL. |
260 | * |
261 | * Returns: 0 on success, -errno on failure. If @bs is not inserted, return |
262 | * -ENOMEDIUM. If @snapshot_id and @name are both NULL, return -EINVAL. If @bs |
263 | * does not support internal snapshot deletion, return -ENOTSUP. If @bs does |
264 | * not support parameter @snapshot_id or @name, or one of them is not correctly |
265 | * specified, return -EINVAL. If @bs can't find one matching @id and @name, |
266 | * return -ENOENT. If @errp != NULL, it will always be filled with error |
267 | * message on failure. |
268 | */ |
269 | int bdrv_snapshot_delete(BlockDriverState *bs, |
270 | const char *snapshot_id, |
271 | const char *name, |
272 | Error **errp) |
273 | { |
274 | BlockDriver *drv = bs->drv; |
275 | int ret; |
276 | |
277 | if (!drv) { |
278 | error_setg(errp, QERR_DEVICE_HAS_NO_MEDIUM, bdrv_get_device_name(bs)); |
279 | return -ENOMEDIUM; |
280 | } |
281 | if (!snapshot_id && !name) { |
282 | error_setg(errp, "snapshot_id and name are both NULL" ); |
283 | return -EINVAL; |
284 | } |
285 | |
286 | /* drain all pending i/o before deleting snapshot */ |
287 | bdrv_drained_begin(bs); |
288 | |
289 | if (drv->bdrv_snapshot_delete) { |
290 | ret = drv->bdrv_snapshot_delete(bs, snapshot_id, name, errp); |
291 | } else if (bs->file) { |
292 | ret = bdrv_snapshot_delete(bs->file->bs, snapshot_id, name, errp); |
293 | } else { |
294 | error_setg(errp, "Block format '%s' used by device '%s' " |
295 | "does not support internal snapshot deletion" , |
296 | drv->format_name, bdrv_get_device_name(bs)); |
297 | ret = -ENOTSUP; |
298 | } |
299 | |
300 | bdrv_drained_end(bs); |
301 | return ret; |
302 | } |
303 | |
304 | int bdrv_snapshot_list(BlockDriverState *bs, |
305 | QEMUSnapshotInfo **psn_info) |
306 | { |
307 | BlockDriver *drv = bs->drv; |
308 | if (!drv) { |
309 | return -ENOMEDIUM; |
310 | } |
311 | if (drv->bdrv_snapshot_list) { |
312 | return drv->bdrv_snapshot_list(bs, psn_info); |
313 | } |
314 | if (bs->file) { |
315 | return bdrv_snapshot_list(bs->file->bs, psn_info); |
316 | } |
317 | return -ENOTSUP; |
318 | } |
319 | |
320 | /** |
321 | * Temporarily load an internal snapshot by @snapshot_id and @name. |
322 | * @bs: block device used in the operation |
323 | * @snapshot_id: unique snapshot ID, or NULL |
324 | * @name: snapshot name, or NULL |
325 | * @errp: location to store error |
326 | * |
327 | * If both @snapshot_id and @name are specified, load the first one with |
328 | * id @snapshot_id and name @name. |
329 | * If only @snapshot_id is specified, load the first one with id |
330 | * @snapshot_id. |
331 | * If only @name is specified, load the first one with name @name. |
332 | * if none is specified, return -EINVAL. |
333 | * |
334 | * Returns: 0 on success, -errno on fail. If @bs is not inserted, return |
335 | * -ENOMEDIUM. If @bs is not readonly, return -EINVAL. If @bs did not support |
336 | * internal snapshot, return -ENOTSUP. If qemu can't find a matching @id and |
337 | * @name, return -ENOENT. If @errp != NULL, it will always be filled on |
338 | * failure. |
339 | */ |
340 | int bdrv_snapshot_load_tmp(BlockDriverState *bs, |
341 | const char *snapshot_id, |
342 | const char *name, |
343 | Error **errp) |
344 | { |
345 | BlockDriver *drv = bs->drv; |
346 | |
347 | if (!drv) { |
348 | error_setg(errp, QERR_DEVICE_HAS_NO_MEDIUM, bdrv_get_device_name(bs)); |
349 | return -ENOMEDIUM; |
350 | } |
351 | if (!snapshot_id && !name) { |
352 | error_setg(errp, "snapshot_id and name are both NULL" ); |
353 | return -EINVAL; |
354 | } |
355 | if (!bs->read_only) { |
356 | error_setg(errp, "Device is not readonly" ); |
357 | return -EINVAL; |
358 | } |
359 | if (drv->bdrv_snapshot_load_tmp) { |
360 | return drv->bdrv_snapshot_load_tmp(bs, snapshot_id, name, errp); |
361 | } |
362 | error_setg(errp, "Block format '%s' used by device '%s' " |
363 | "does not support temporarily loading internal snapshots" , |
364 | drv->format_name, bdrv_get_device_name(bs)); |
365 | return -ENOTSUP; |
366 | } |
367 | |
368 | int bdrv_snapshot_load_tmp_by_id_or_name(BlockDriverState *bs, |
369 | const char *id_or_name, |
370 | Error **errp) |
371 | { |
372 | int ret; |
373 | Error *local_err = NULL; |
374 | |
375 | ret = bdrv_snapshot_load_tmp(bs, id_or_name, NULL, &local_err); |
376 | if (ret == -ENOENT || ret == -EINVAL) { |
377 | error_free(local_err); |
378 | local_err = NULL; |
379 | ret = bdrv_snapshot_load_tmp(bs, NULL, id_or_name, &local_err); |
380 | } |
381 | |
382 | error_propagate(errp, local_err); |
383 | |
384 | return ret; |
385 | } |
386 | |
387 | |
388 | /* Group operations. All block drivers are involved. |
389 | * These functions will properly handle dataplane (take aio_context_acquire |
390 | * when appropriate for appropriate block drivers) */ |
391 | |
392 | bool bdrv_all_can_snapshot(BlockDriverState **first_bad_bs) |
393 | { |
394 | bool ok = true; |
395 | BlockDriverState *bs; |
396 | BdrvNextIterator it; |
397 | |
398 | for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) { |
399 | AioContext *ctx = bdrv_get_aio_context(bs); |
400 | |
401 | aio_context_acquire(ctx); |
402 | if (bdrv_is_inserted(bs) && !bdrv_is_read_only(bs)) { |
403 | ok = bdrv_can_snapshot(bs); |
404 | } |
405 | aio_context_release(ctx); |
406 | if (!ok) { |
407 | bdrv_next_cleanup(&it); |
408 | goto fail; |
409 | } |
410 | } |
411 | |
412 | fail: |
413 | *first_bad_bs = bs; |
414 | return ok; |
415 | } |
416 | |
417 | int bdrv_all_delete_snapshot(const char *name, BlockDriverState **first_bad_bs, |
418 | Error **err) |
419 | { |
420 | int ret = 0; |
421 | BlockDriverState *bs; |
422 | BdrvNextIterator it; |
423 | QEMUSnapshotInfo sn1, *snapshot = &sn1; |
424 | |
425 | for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) { |
426 | AioContext *ctx = bdrv_get_aio_context(bs); |
427 | |
428 | aio_context_acquire(ctx); |
429 | if (bdrv_can_snapshot(bs) && |
430 | bdrv_snapshot_find(bs, snapshot, name) >= 0) { |
431 | ret = bdrv_snapshot_delete(bs, snapshot->id_str, |
432 | snapshot->name, err); |
433 | } |
434 | aio_context_release(ctx); |
435 | if (ret < 0) { |
436 | bdrv_next_cleanup(&it); |
437 | goto fail; |
438 | } |
439 | } |
440 | |
441 | fail: |
442 | *first_bad_bs = bs; |
443 | return ret; |
444 | } |
445 | |
446 | |
447 | int bdrv_all_goto_snapshot(const char *name, BlockDriverState **first_bad_bs, |
448 | Error **errp) |
449 | { |
450 | int ret = 0; |
451 | BlockDriverState *bs; |
452 | BdrvNextIterator it; |
453 | |
454 | for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) { |
455 | AioContext *ctx = bdrv_get_aio_context(bs); |
456 | |
457 | aio_context_acquire(ctx); |
458 | if (bdrv_can_snapshot(bs)) { |
459 | ret = bdrv_snapshot_goto(bs, name, errp); |
460 | } |
461 | aio_context_release(ctx); |
462 | if (ret < 0) { |
463 | bdrv_next_cleanup(&it); |
464 | goto fail; |
465 | } |
466 | } |
467 | |
468 | fail: |
469 | *first_bad_bs = bs; |
470 | return ret; |
471 | } |
472 | |
473 | int bdrv_all_find_snapshot(const char *name, BlockDriverState **first_bad_bs) |
474 | { |
475 | QEMUSnapshotInfo sn; |
476 | int err = 0; |
477 | BlockDriverState *bs; |
478 | BdrvNextIterator it; |
479 | |
480 | for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) { |
481 | AioContext *ctx = bdrv_get_aio_context(bs); |
482 | |
483 | aio_context_acquire(ctx); |
484 | if (bdrv_can_snapshot(bs)) { |
485 | err = bdrv_snapshot_find(bs, &sn, name); |
486 | } |
487 | aio_context_release(ctx); |
488 | if (err < 0) { |
489 | bdrv_next_cleanup(&it); |
490 | goto fail; |
491 | } |
492 | } |
493 | |
494 | fail: |
495 | *first_bad_bs = bs; |
496 | return err; |
497 | } |
498 | |
499 | int bdrv_all_create_snapshot(QEMUSnapshotInfo *sn, |
500 | BlockDriverState *vm_state_bs, |
501 | uint64_t vm_state_size, |
502 | BlockDriverState **first_bad_bs) |
503 | { |
504 | int err = 0; |
505 | BlockDriverState *bs; |
506 | BdrvNextIterator it; |
507 | |
508 | for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) { |
509 | AioContext *ctx = bdrv_get_aio_context(bs); |
510 | |
511 | aio_context_acquire(ctx); |
512 | if (bs == vm_state_bs) { |
513 | sn->vm_state_size = vm_state_size; |
514 | err = bdrv_snapshot_create(bs, sn); |
515 | } else if (bdrv_can_snapshot(bs)) { |
516 | sn->vm_state_size = 0; |
517 | err = bdrv_snapshot_create(bs, sn); |
518 | } |
519 | aio_context_release(ctx); |
520 | if (err < 0) { |
521 | bdrv_next_cleanup(&it); |
522 | goto fail; |
523 | } |
524 | } |
525 | |
526 | fail: |
527 | *first_bad_bs = bs; |
528 | return err; |
529 | } |
530 | |
531 | BlockDriverState *bdrv_all_find_vmstate_bs(void) |
532 | { |
533 | BlockDriverState *bs; |
534 | BdrvNextIterator it; |
535 | |
536 | for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) { |
537 | AioContext *ctx = bdrv_get_aio_context(bs); |
538 | bool found; |
539 | |
540 | aio_context_acquire(ctx); |
541 | found = bdrv_can_snapshot(bs); |
542 | aio_context_release(ctx); |
543 | |
544 | if (found) { |
545 | bdrv_next_cleanup(&it); |
546 | break; |
547 | } |
548 | } |
549 | return bs; |
550 | } |
551 | |