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