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