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Commit | Line | Data |
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747ff602 JC |
1 | /* |
2 | * Live block commit | |
3 | * | |
4 | * Copyright Red Hat, Inc. 2012 | |
5 | * | |
6 | * Authors: | |
7 | * Jeff Cody <jcody@redhat.com> | |
8 | * Based on stream.c by Stefan Hajnoczi | |
9 | * | |
10 | * This work is licensed under the terms of the GNU LGPL, version 2 or later. | |
11 | * See the COPYING.LIB file in the top-level directory. | |
12 | * | |
13 | */ | |
14 | ||
80c71a24 | 15 | #include "qemu/osdep.h" |
dcbf37ce | 16 | #include "qemu/cutils.h" |
747ff602 | 17 | #include "trace.h" |
737e150e | 18 | #include "block/block_int.h" |
c87621ea | 19 | #include "block/blockjob_int.h" |
da34e65c | 20 | #include "qapi/error.h" |
cc7a8ea7 | 21 | #include "qapi/qmp/qerror.h" |
747ff602 | 22 | #include "qemu/ratelimit.h" |
373340b2 | 23 | #include "sysemu/block-backend.h" |
747ff602 JC |
24 | |
25 | enum { | |
26 | /* | |
27 | * Size of data buffer for populating the image file. This should be large | |
28 | * enough to process multiple clusters in a single call, so that populating | |
29 | * contiguous regions of the image is efficient. | |
30 | */ | |
31 | COMMIT_BUFFER_SIZE = 512 * 1024, /* in bytes */ | |
32 | }; | |
33 | ||
747ff602 JC |
34 | typedef struct CommitBlockJob { |
35 | BlockJob common; | |
8dfba279 | 36 | BlockDriverState *commit_top_bs; |
4653456a KW |
37 | BlockBackend *top; |
38 | BlockBackend *base; | |
22dffcbe | 39 | BlockDriverState *base_bs; |
9a71b9de | 40 | BlockDriverState *base_overlay; |
92aa5c6d | 41 | BlockdevOnError on_error; |
e70cdc57 | 42 | bool base_read_only; |
df827336 | 43 | bool chain_frozen; |
54e26900 | 44 | char *backing_file_str; |
747ff602 JC |
45 | } CommitBlockJob; |
46 | ||
22dffcbe | 47 | static int commit_prepare(Job *job) |
747ff602 | 48 | { |
1908a559 | 49 | CommitBlockJob *s = container_of(job, CommitBlockJob, common.job); |
19ebd13e | 50 | |
df827336 AG |
51 | bdrv_unfreeze_backing_chain(s->commit_top_bs, s->base_bs); |
52 | s->chain_frozen = false; | |
53 | ||
8dfba279 KW |
54 | /* Remove base node parent that still uses BLK_PERM_WRITE/RESIZE before |
55 | * the normal backing chain can be restored. */ | |
56 | blk_unref(s->base); | |
22dffcbe JS |
57 | s->base = NULL; |
58 | ||
59 | /* FIXME: bdrv_drop_intermediate treats total failures and partial failures | |
60 | * identically. Further work is needed to disambiguate these cases. */ | |
61 | return bdrv_drop_intermediate(s->commit_top_bs, s->base_bs, | |
62 | s->backing_file_str); | |
63 | } | |
9e85cd5c | 64 | |
22dffcbe JS |
65 | static void commit_abort(Job *job) |
66 | { | |
67 | CommitBlockJob *s = container_of(job, CommitBlockJob, common.job); | |
68 | BlockDriverState *top_bs = blk_bs(s->top); | |
69 | ||
df827336 AG |
70 | if (s->chain_frozen) { |
71 | bdrv_unfreeze_backing_chain(s->commit_top_bs, s->base_bs); | |
72 | } | |
73 | ||
22dffcbe JS |
74 | /* Make sure commit_top_bs and top stay around until bdrv_replace_node() */ |
75 | bdrv_ref(top_bs); | |
76 | bdrv_ref(s->commit_top_bs); | |
77 | ||
78 | if (s->base) { | |
79 | blk_unref(s->base); | |
9e85cd5c SH |
80 | } |
81 | ||
22dffcbe JS |
82 | /* free the blockers on the intermediate nodes so that bdrv_replace_nodes |
83 | * can succeed */ | |
84 | block_job_remove_all_bdrv(&s->common); | |
85 | ||
86 | /* If bdrv_drop_intermediate() failed (or was not invoked), remove the | |
87 | * commit filter driver from the backing chain now. Do this as the final | |
88 | * step so that the 'consistent read' permission can be granted. | |
89 | * | |
90 | * XXX Can (or should) we somehow keep 'consistent read' blocked even | |
91 | * after the failed/cancelled commit job is gone? If we already wrote | |
92 | * something to base, the intermediate images aren't valid any more. */ | |
9a71b9de | 93 | bdrv_replace_node(s->commit_top_bs, s->commit_top_bs->backing->bs, |
22dffcbe JS |
94 | &error_abort); |
95 | ||
96 | bdrv_unref(s->commit_top_bs); | |
97 | bdrv_unref(top_bs); | |
98 | } | |
99 | ||
100 | static void commit_clean(Job *job) | |
101 | { | |
102 | CommitBlockJob *s = container_of(job, CommitBlockJob, common.job); | |
103 | ||
9e85cd5c SH |
104 | /* restore base open flags here if appropriate (e.g., change the base back |
105 | * to r/o). These reopens do not need to be atomic, since we won't abort | |
106 | * even on failure here */ | |
e70cdc57 AG |
107 | if (s->base_read_only) { |
108 | bdrv_reopen_set_read_only(s->base_bs, true, NULL); | |
9e85cd5c | 109 | } |
22dffcbe | 110 | |
9e85cd5c | 111 | g_free(s->backing_file_str); |
4653456a | 112 | blk_unref(s->top); |
9e85cd5c SH |
113 | } |
114 | ||
f67432a2 | 115 | static int coroutine_fn commit_run(Job *job, Error **errp) |
9e85cd5c | 116 | { |
f67432a2 | 117 | CommitBlockJob *s = container_of(job, CommitBlockJob, common.job); |
317a6676 | 118 | int64_t offset; |
f14a39cc | 119 | uint64_t delay_ns = 0; |
747ff602 | 120 | int ret = 0; |
51b0a488 | 121 | int64_t n = 0; /* bytes */ |
9e85cd5c | 122 | void *buf = NULL; |
05df8a6a | 123 | int64_t len, base_len; |
747ff602 | 124 | |
05df8a6a KW |
125 | ret = len = blk_getlength(s->top); |
126 | if (len < 0) { | |
9e85cd5c | 127 | goto out; |
747ff602 | 128 | } |
30a5c887 | 129 | job_progress_set_remaining(&s->common.job, len); |
747ff602 | 130 | |
4653456a | 131 | ret = base_len = blk_getlength(s->base); |
747ff602 | 132 | if (base_len < 0) { |
9e85cd5c | 133 | goto out; |
747ff602 JC |
134 | } |
135 | ||
05df8a6a | 136 | if (base_len < len) { |
8c6242b6 | 137 | ret = blk_truncate(s->base, len, false, PREALLOC_MODE_OFF, 0, NULL); |
747ff602 | 138 | if (ret) { |
9e85cd5c | 139 | goto out; |
747ff602 JC |
140 | } |
141 | } | |
142 | ||
4653456a | 143 | buf = blk_blockalign(s->top, COMMIT_BUFFER_SIZE); |
747ff602 | 144 | |
05df8a6a | 145 | for (offset = 0; offset < len; offset += n) { |
747ff602 | 146 | bool copy; |
9ad1e79f | 147 | bool error_in_source = true; |
747ff602 | 148 | |
747ff602 | 149 | /* Note that even when no rate limit is applied we need to yield |
c57b6656 | 150 | * with no pending I/O here so that bdrv_drain_all() returns. |
747ff602 | 151 | */ |
5d43e86e | 152 | job_sleep_ns(&s->common.job, delay_ns); |
daa7f2f9 | 153 | if (job_is_cancelled(&s->common.job)) { |
747ff602 JC |
154 | break; |
155 | } | |
156 | /* Copy if allocated above the base */ | |
9a71b9de | 157 | ret = bdrv_is_allocated_above(blk_bs(s->top), s->base_overlay, true, |
51b0a488 | 158 | offset, COMMIT_BUFFER_SIZE, &n); |
a92b1b06 | 159 | copy = (ret > 0); |
51b0a488 | 160 | trace_commit_one_iteration(s, offset, n, ret); |
747ff602 | 161 | if (copy) { |
0c42e175 KW |
162 | assert(n < SIZE_MAX); |
163 | ||
164 | ret = blk_co_pread(s->top, offset, n, buf, 0); | |
165 | if (ret >= 0) { | |
166 | ret = blk_co_pwrite(s->base, offset, n, buf, 0); | |
9ad1e79f KW |
167 | if (ret < 0) { |
168 | error_in_source = false; | |
169 | } | |
0c42e175 | 170 | } |
747ff602 JC |
171 | } |
172 | if (ret < 0) { | |
1e8fb7f1 | 173 | BlockErrorAction action = |
9ad1e79f KW |
174 | block_job_error_action(&s->common, s->on_error, |
175 | error_in_source, -ret); | |
1e8fb7f1 | 176 | if (action == BLOCK_ERROR_ACTION_REPORT) { |
9e85cd5c | 177 | goto out; |
747ff602 JC |
178 | } else { |
179 | n = 0; | |
180 | continue; | |
181 | } | |
182 | } | |
183 | /* Publish progress */ | |
30a5c887 | 184 | job_progress_update(&s->common.job, n); |
f14a39cc | 185 | |
dee81d51 KW |
186 | if (copy) { |
187 | delay_ns = block_job_ratelimit_get_delay(&s->common, n); | |
2fe4bba1 KW |
188 | } else { |
189 | delay_ns = 0; | |
f14a39cc | 190 | } |
747ff602 JC |
191 | } |
192 | ||
193 | ret = 0; | |
194 | ||
9e85cd5c | 195 | out: |
747ff602 JC |
196 | qemu_vfree(buf); |
197 | ||
f67432a2 | 198 | return ret; |
747ff602 JC |
199 | } |
200 | ||
3fc4b10a | 201 | static const BlockJobDriver commit_job_driver = { |
33e9e9bd KW |
202 | .job_driver = { |
203 | .instance_size = sizeof(CommitBlockJob), | |
252291ea | 204 | .job_type = JOB_TYPE_COMMIT, |
80fa2c75 | 205 | .free = block_job_free, |
b15de828 | 206 | .user_resume = block_job_user_resume, |
f67432a2 | 207 | .run = commit_run, |
22dffcbe JS |
208 | .prepare = commit_prepare, |
209 | .abort = commit_abort, | |
210 | .clean = commit_clean | |
33e9e9bd | 211 | }, |
747ff602 JC |
212 | }; |
213 | ||
8dfba279 KW |
214 | static int coroutine_fn bdrv_commit_top_preadv(BlockDriverState *bs, |
215 | uint64_t offset, uint64_t bytes, QEMUIOVector *qiov, int flags) | |
216 | { | |
217 | return bdrv_co_preadv(bs->backing, offset, bytes, qiov, flags); | |
218 | } | |
219 | ||
998b3a1e | 220 | static void bdrv_commit_top_refresh_filename(BlockDriverState *bs) |
dcbf37ce | 221 | { |
dcbf37ce KW |
222 | pstrcpy(bs->exact_filename, sizeof(bs->exact_filename), |
223 | bs->backing->bs->filename); | |
224 | } | |
91965658 | 225 | |
8dfba279 | 226 | static void bdrv_commit_top_child_perm(BlockDriverState *bs, BdrvChild *c, |
bf8e925e | 227 | BdrvChildRole role, |
e0995dc3 | 228 | BlockReopenQueue *reopen_queue, |
8dfba279 KW |
229 | uint64_t perm, uint64_t shared, |
230 | uint64_t *nperm, uint64_t *nshared) | |
231 | { | |
232 | *nperm = 0; | |
233 | *nshared = BLK_PERM_ALL; | |
234 | } | |
235 | ||
236 | /* Dummy node that provides consistent read to its users without requiring it | |
237 | * from its backing file and that allows writes on the backing file chain. */ | |
238 | static BlockDriver bdrv_commit_top = { | |
91965658 KW |
239 | .format_name = "commit_top", |
240 | .bdrv_co_preadv = bdrv_commit_top_preadv, | |
dcbf37ce | 241 | .bdrv_refresh_filename = bdrv_commit_top_refresh_filename, |
91965658 | 242 | .bdrv_child_perm = bdrv_commit_top_child_perm, |
6540fd15 HR |
243 | |
244 | .is_filter = true, | |
8dfba279 KW |
245 | }; |
246 | ||
fd62c609 | 247 | void commit_start(const char *job_id, BlockDriverState *bs, |
5360782d JS |
248 | BlockDriverState *base, BlockDriverState *top, |
249 | int creation_flags, int64_t speed, | |
8254b6d9 | 250 | BlockdevOnError on_error, const char *backing_file_str, |
0db832f4 | 251 | const char *filter_node_name, Error **errp) |
747ff602 JC |
252 | { |
253 | CommitBlockJob *s; | |
3e4c5122 | 254 | BlockDriverState *iter; |
8dfba279 | 255 | BlockDriverState *commit_top_bs = NULL; |
9a71b9de | 256 | BlockDriverState *filtered_base; |
9a71b9de HR |
257 | int64_t base_size, top_size; |
258 | uint64_t base_perms, iter_shared_perms; | |
d7086422 | 259 | int ret; |
747ff602 | 260 | |
18da7f94 | 261 | assert(top != bs); |
9a71b9de | 262 | if (bdrv_skip_filters(top) == bdrv_skip_filters(base)) { |
747ff602 JC |
263 | error_setg(errp, "Invalid files for merge: top and base are the same"); |
264 | return; | |
265 | } | |
266 | ||
9a71b9de HR |
267 | base_size = bdrv_getlength(base); |
268 | if (base_size < 0) { | |
269 | error_setg_errno(errp, -base_size, "Could not inquire base image size"); | |
270 | return; | |
271 | } | |
272 | ||
273 | top_size = bdrv_getlength(top); | |
274 | if (top_size < 0) { | |
275 | error_setg_errno(errp, -top_size, "Could not inquire top image size"); | |
276 | return; | |
277 | } | |
278 | ||
279 | base_perms = BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE; | |
280 | if (base_size < top_size) { | |
281 | base_perms |= BLK_PERM_RESIZE; | |
282 | } | |
283 | ||
75859b94 | 284 | s = block_job_create(job_id, &commit_job_driver, NULL, bs, 0, BLK_PERM_ALL, |
5360782d | 285 | speed, creation_flags, NULL, NULL, errp); |
834fe28d AG |
286 | if (!s) { |
287 | return; | |
288 | } | |
289 | ||
bde70715 | 290 | /* convert base to r/w, if necessary */ |
e70cdc57 AG |
291 | s->base_read_only = bdrv_is_read_only(base); |
292 | if (s->base_read_only) { | |
293 | if (bdrv_reopen_set_read_only(base, false, errp) != 0) { | |
d7086422 | 294 | goto fail; |
747ff602 JC |
295 | } |
296 | } | |
297 | ||
8dfba279 KW |
298 | /* Insert commit_top block node above top, so we can block consistent read |
299 | * on the backing chain below it */ | |
0db832f4 KW |
300 | commit_top_bs = bdrv_new_open_driver(&bdrv_commit_top, filter_node_name, 0, |
301 | errp); | |
8dfba279 KW |
302 | if (commit_top_bs == NULL) { |
303 | goto fail; | |
304 | } | |
d3c8c674 KW |
305 | if (!filter_node_name) { |
306 | commit_top_bs->implicit = true; | |
307 | } | |
e5182c1c HR |
308 | |
309 | /* So that we can always drop this node */ | |
310 | commit_top_bs->never_freeze = true; | |
311 | ||
0d0676a1 | 312 | commit_top_bs->total_sectors = top->total_sectors; |
8dfba279 | 313 | |
934aee14 VSO |
314 | ret = bdrv_append(commit_top_bs, top, errp); |
315 | if (ret < 0) { | |
b69f00dd | 316 | commit_top_bs = NULL; |
b69f00dd FZ |
317 | goto fail; |
318 | } | |
8dfba279 KW |
319 | |
320 | s->commit_top_bs = commit_top_bs; | |
747ff602 | 321 | |
9a71b9de HR |
322 | /* |
323 | * Block all nodes between top and base, because they will | |
324 | * disappear from the chain after this operation. | |
325 | * Note that this assumes that the user is fine with removing all | |
326 | * nodes (including R/W filters) between top and base. Assuring | |
327 | * this is the responsibility of the interface (i.e. whoever calls | |
328 | * commit_start()). | |
329 | */ | |
330 | s->base_overlay = bdrv_find_overlay(top, base); | |
331 | assert(s->base_overlay); | |
332 | ||
333 | /* | |
334 | * The topmost node with | |
335 | * bdrv_skip_filters(filtered_base) == bdrv_skip_filters(base) | |
336 | */ | |
337 | filtered_base = bdrv_cow_bs(s->base_overlay); | |
338 | assert(bdrv_skip_filters(filtered_base) == bdrv_skip_filters(base)); | |
339 | ||
340 | /* | |
341 | * XXX BLK_PERM_WRITE needs to be allowed so we don't block ourselves | |
342 | * at s->base (if writes are blocked for a node, they are also blocked | |
343 | * for its backing file). The other options would be a second filter | |
344 | * driver above s->base. | |
345 | */ | |
346 | iter_shared_perms = BLK_PERM_WRITE_UNCHANGED | BLK_PERM_WRITE; | |
347 | ||
348 | for (iter = top; iter != base; iter = bdrv_filter_or_cow_bs(iter)) { | |
349 | if (iter == filtered_base) { | |
350 | /* | |
351 | * From here on, all nodes are filters on the base. This | |
352 | * allows us to share BLK_PERM_CONSISTENT_READ. | |
353 | */ | |
354 | iter_shared_perms |= BLK_PERM_CONSISTENT_READ; | |
355 | } | |
356 | ||
8dfba279 | 357 | ret = block_job_add_bdrv(&s->common, "intermediate node", iter, 0, |
9a71b9de | 358 | iter_shared_perms, errp); |
8dfba279 KW |
359 | if (ret < 0) { |
360 | goto fail; | |
361 | } | |
3e4c5122 | 362 | } |
8dfba279 | 363 | |
df827336 AG |
364 | if (bdrv_freeze_backing_chain(commit_top_bs, base, errp) < 0) { |
365 | goto fail; | |
366 | } | |
367 | s->chain_frozen = true; | |
368 | ||
8dfba279 KW |
369 | ret = block_job_add_bdrv(&s->common, "base", base, 0, BLK_PERM_ALL, errp); |
370 | if (ret < 0) { | |
371 | goto fail; | |
372 | } | |
373 | ||
d861ab3a | 374 | s->base = blk_new(s->common.job.aio_context, |
9a71b9de | 375 | base_perms, |
8dfba279 KW |
376 | BLK_PERM_CONSISTENT_READ |
377 | | BLK_PERM_GRAPH_MOD | |
378 | | BLK_PERM_WRITE_UNCHANGED); | |
d7086422 KW |
379 | ret = blk_insert_bs(s->base, base, errp); |
380 | if (ret < 0) { | |
381 | goto fail; | |
382 | } | |
cf312932 | 383 | blk_set_disable_request_queuing(s->base, true); |
22dffcbe | 384 | s->base_bs = base; |
4653456a | 385 | |
8dfba279 | 386 | /* Required permissions are already taken with block_job_add_bdrv() */ |
d861ab3a | 387 | s->top = blk_new(s->common.job.aio_context, 0, BLK_PERM_ALL); |
b247767a | 388 | ret = blk_insert_bs(s->top, top, errp); |
d7086422 KW |
389 | if (ret < 0) { |
390 | goto fail; | |
391 | } | |
cf312932 | 392 | blk_set_disable_request_queuing(s->top, true); |
4653456a | 393 | |
54e26900 | 394 | s->backing_file_str = g_strdup(backing_file_str); |
747ff602 | 395 | s->on_error = on_error; |
747ff602 | 396 | |
5ccac6f1 | 397 | trace_commit_start(bs, base, top, s); |
da01ff7f | 398 | job_start(&s->common.job); |
d7086422 KW |
399 | return; |
400 | ||
401 | fail: | |
df827336 AG |
402 | if (s->chain_frozen) { |
403 | bdrv_unfreeze_backing_chain(commit_top_bs, base); | |
404 | } | |
d7086422 KW |
405 | if (s->base) { |
406 | blk_unref(s->base); | |
407 | } | |
408 | if (s->top) { | |
409 | blk_unref(s->top); | |
410 | } | |
065abf9f AG |
411 | if (s->base_read_only) { |
412 | bdrv_reopen_set_read_only(base, true, NULL); | |
413 | } | |
2468eed3 AG |
414 | job_early_fail(&s->common.job); |
415 | /* commit_top_bs has to be replaced after deleting the block job, | |
416 | * otherwise this would fail because of lack of permissions. */ | |
8dfba279 | 417 | if (commit_top_bs) { |
bde70715 | 418 | bdrv_replace_node(commit_top_bs, top, &error_abort); |
8dfba279 | 419 | } |
747ff602 | 420 | } |
83fd6dd3 KW |
421 | |
422 | ||
d6a644bb | 423 | #define COMMIT_BUF_SIZE (2048 * BDRV_SECTOR_SIZE) |
83fd6dd3 KW |
424 | |
425 | /* commit COW file into the raw image */ | |
426 | int bdrv_commit(BlockDriverState *bs) | |
427 | { | |
f8e2bd53 | 428 | BlockBackend *src, *backing; |
d3f06759 KW |
429 | BlockDriverState *backing_file_bs = NULL; |
430 | BlockDriverState *commit_top_bs = NULL; | |
83fd6dd3 | 431 | BlockDriver *drv = bs->drv; |
d861ab3a | 432 | AioContext *ctx; |
d6a644bb | 433 | int64_t offset, length, backing_length; |
c742a364 | 434 | int ro; |
d6a644bb | 435 | int64_t n; |
83fd6dd3 KW |
436 | int ret = 0; |
437 | uint8_t *buf = NULL; | |
d3f06759 | 438 | Error *local_err = NULL; |
83fd6dd3 KW |
439 | |
440 | if (!drv) | |
441 | return -ENOMEDIUM; | |
442 | ||
9a71b9de HR |
443 | backing_file_bs = bdrv_cow_bs(bs); |
444 | ||
445 | if (!backing_file_bs) { | |
83fd6dd3 KW |
446 | return -ENOTSUP; |
447 | } | |
448 | ||
449 | if (bdrv_op_is_blocked(bs, BLOCK_OP_TYPE_COMMIT_SOURCE, NULL) || | |
9a71b9de HR |
450 | bdrv_op_is_blocked(backing_file_bs, BLOCK_OP_TYPE_COMMIT_TARGET, NULL)) |
451 | { | |
83fd6dd3 KW |
452 | return -EBUSY; |
453 | } | |
454 | ||
9a71b9de | 455 | ro = backing_file_bs->read_only; |
83fd6dd3 KW |
456 | |
457 | if (ro) { | |
9a71b9de | 458 | if (bdrv_reopen_set_read_only(backing_file_bs, false, NULL)) { |
83fd6dd3 KW |
459 | return -EACCES; |
460 | } | |
461 | } | |
462 | ||
d861ab3a | 463 | ctx = bdrv_get_aio_context(bs); |
2d97fde4 HR |
464 | /* WRITE_UNCHANGED is required for bdrv_make_empty() */ |
465 | src = blk_new(ctx, BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE_UNCHANGED, | |
466 | BLK_PERM_ALL); | |
d861ab3a | 467 | backing = blk_new(ctx, BLK_PERM_WRITE | BLK_PERM_RESIZE, BLK_PERM_ALL); |
d7086422 | 468 | |
d3f06759 | 469 | ret = blk_insert_bs(src, bs, &local_err); |
d7086422 | 470 | if (ret < 0) { |
d3f06759 KW |
471 | error_report_err(local_err); |
472 | goto ro_cleanup; | |
473 | } | |
474 | ||
475 | /* Insert commit_top block node above backing, so we can write to it */ | |
d3f06759 KW |
476 | commit_top_bs = bdrv_new_open_driver(&bdrv_commit_top, NULL, BDRV_O_RDWR, |
477 | &local_err); | |
478 | if (commit_top_bs == NULL) { | |
479 | error_report_err(local_err); | |
d7086422 KW |
480 | goto ro_cleanup; |
481 | } | |
482 | ||
12fa4af6 KW |
483 | bdrv_set_backing_hd(commit_top_bs, backing_file_bs, &error_abort); |
484 | bdrv_set_backing_hd(bs, commit_top_bs, &error_abort); | |
d3f06759 KW |
485 | |
486 | ret = blk_insert_bs(backing, backing_file_bs, &local_err); | |
d7086422 | 487 | if (ret < 0) { |
d3f06759 | 488 | error_report_err(local_err); |
d7086422 KW |
489 | goto ro_cleanup; |
490 | } | |
f8e2bd53 KW |
491 | |
492 | length = blk_getlength(src); | |
83fd6dd3 KW |
493 | if (length < 0) { |
494 | ret = length; | |
495 | goto ro_cleanup; | |
496 | } | |
497 | ||
f8e2bd53 | 498 | backing_length = blk_getlength(backing); |
83fd6dd3 KW |
499 | if (backing_length < 0) { |
500 | ret = backing_length; | |
501 | goto ro_cleanup; | |
502 | } | |
503 | ||
504 | /* If our top snapshot is larger than the backing file image, | |
505 | * grow the backing file image if possible. If not possible, | |
506 | * we must return an error */ | |
507 | if (length > backing_length) { | |
8c6242b6 | 508 | ret = blk_truncate(backing, length, false, PREALLOC_MODE_OFF, 0, |
c80d8b06 | 509 | &local_err); |
83fd6dd3 | 510 | if (ret < 0) { |
ed3d2ec9 | 511 | error_report_err(local_err); |
83fd6dd3 KW |
512 | goto ro_cleanup; |
513 | } | |
514 | } | |
515 | ||
f8e2bd53 KW |
516 | /* blk_try_blockalign() for src will choose an alignment that works for |
517 | * backing as well, so no need to compare the alignment manually. */ | |
d6a644bb | 518 | buf = blk_try_blockalign(src, COMMIT_BUF_SIZE); |
83fd6dd3 KW |
519 | if (buf == NULL) { |
520 | ret = -ENOMEM; | |
521 | goto ro_cleanup; | |
522 | } | |
523 | ||
d6a644bb EB |
524 | for (offset = 0; offset < length; offset += n) { |
525 | ret = bdrv_is_allocated(bs, offset, COMMIT_BUF_SIZE, &n); | |
83fd6dd3 KW |
526 | if (ret < 0) { |
527 | goto ro_cleanup; | |
528 | } | |
529 | if (ret) { | |
d6a644bb | 530 | ret = blk_pread(src, offset, buf, n); |
83fd6dd3 KW |
531 | if (ret < 0) { |
532 | goto ro_cleanup; | |
533 | } | |
534 | ||
d6a644bb | 535 | ret = blk_pwrite(backing, offset, buf, n, 0); |
83fd6dd3 KW |
536 | if (ret < 0) { |
537 | goto ro_cleanup; | |
538 | } | |
539 | } | |
540 | } | |
541 | ||
2d97fde4 HR |
542 | ret = blk_make_empty(src, NULL); |
543 | /* Ignore -ENOTSUP */ | |
544 | if (ret < 0 && ret != -ENOTSUP) { | |
545 | goto ro_cleanup; | |
83fd6dd3 KW |
546 | } |
547 | ||
2d97fde4 HR |
548 | blk_flush(src); |
549 | ||
83fd6dd3 KW |
550 | /* |
551 | * Make sure all data we wrote to the backing device is actually | |
552 | * stable on disk. | |
553 | */ | |
f8e2bd53 | 554 | blk_flush(backing); |
83fd6dd3 KW |
555 | |
556 | ret = 0; | |
557 | ro_cleanup: | |
558 | qemu_vfree(buf); | |
559 | ||
f8e2bd53 | 560 | blk_unref(backing); |
9a71b9de | 561 | if (bdrv_cow_bs(bs) != backing_file_bs) { |
12fa4af6 | 562 | bdrv_set_backing_hd(bs, backing_file_bs, &error_abort); |
d3f06759 KW |
563 | } |
564 | bdrv_unref(commit_top_bs); | |
565 | blk_unref(src); | |
f8e2bd53 | 566 | |
83fd6dd3 KW |
567 | if (ro) { |
568 | /* ignoring error return here */ | |
9a71b9de | 569 | bdrv_reopen_set_read_only(backing_file_bs, true, NULL); |
83fd6dd3 KW |
570 | } |
571 | ||
572 | return ret; | |
573 | } |