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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; |
92aa5c6d | 40 | BlockdevOnError on_error; |
e70cdc57 | 41 | bool base_read_only; |
df827336 | 42 | bool chain_frozen; |
54e26900 | 43 | char *backing_file_str; |
747ff602 JC |
44 | } CommitBlockJob; |
45 | ||
22dffcbe | 46 | static int commit_prepare(Job *job) |
747ff602 | 47 | { |
1908a559 | 48 | CommitBlockJob *s = container_of(job, CommitBlockJob, common.job); |
19ebd13e | 49 | |
df827336 AG |
50 | bdrv_unfreeze_backing_chain(s->commit_top_bs, s->base_bs); |
51 | s->chain_frozen = false; | |
52 | ||
8dfba279 KW |
53 | /* Remove base node parent that still uses BLK_PERM_WRITE/RESIZE before |
54 | * the normal backing chain can be restored. */ | |
55 | blk_unref(s->base); | |
22dffcbe JS |
56 | s->base = NULL; |
57 | ||
58 | /* FIXME: bdrv_drop_intermediate treats total failures and partial failures | |
59 | * identically. Further work is needed to disambiguate these cases. */ | |
60 | return bdrv_drop_intermediate(s->commit_top_bs, s->base_bs, | |
61 | s->backing_file_str); | |
62 | } | |
9e85cd5c | 63 | |
22dffcbe JS |
64 | static void commit_abort(Job *job) |
65 | { | |
66 | CommitBlockJob *s = container_of(job, CommitBlockJob, common.job); | |
67 | BlockDriverState *top_bs = blk_bs(s->top); | |
68 | ||
df827336 AG |
69 | if (s->chain_frozen) { |
70 | bdrv_unfreeze_backing_chain(s->commit_top_bs, s->base_bs); | |
71 | } | |
72 | ||
22dffcbe JS |
73 | /* Make sure commit_top_bs and top stay around until bdrv_replace_node() */ |
74 | bdrv_ref(top_bs); | |
75 | bdrv_ref(s->commit_top_bs); | |
76 | ||
77 | if (s->base) { | |
78 | blk_unref(s->base); | |
9e85cd5c SH |
79 | } |
80 | ||
22dffcbe JS |
81 | /* free the blockers on the intermediate nodes so that bdrv_replace_nodes |
82 | * can succeed */ | |
83 | block_job_remove_all_bdrv(&s->common); | |
84 | ||
85 | /* If bdrv_drop_intermediate() failed (or was not invoked), remove the | |
86 | * commit filter driver from the backing chain now. Do this as the final | |
87 | * step so that the 'consistent read' permission can be granted. | |
88 | * | |
89 | * XXX Can (or should) we somehow keep 'consistent read' blocked even | |
90 | * after the failed/cancelled commit job is gone? If we already wrote | |
91 | * something to base, the intermediate images aren't valid any more. */ | |
22dffcbe JS |
92 | bdrv_replace_node(s->commit_top_bs, backing_bs(s->commit_top_bs), |
93 | &error_abort); | |
94 | ||
95 | bdrv_unref(s->commit_top_bs); | |
96 | bdrv_unref(top_bs); | |
97 | } | |
98 | ||
99 | static void commit_clean(Job *job) | |
100 | { | |
101 | CommitBlockJob *s = container_of(job, CommitBlockJob, common.job); | |
102 | ||
9e85cd5c SH |
103 | /* restore base open flags here if appropriate (e.g., change the base back |
104 | * to r/o). These reopens do not need to be atomic, since we won't abort | |
105 | * even on failure here */ | |
e70cdc57 AG |
106 | if (s->base_read_only) { |
107 | bdrv_reopen_set_read_only(s->base_bs, true, NULL); | |
9e85cd5c | 108 | } |
22dffcbe | 109 | |
9e85cd5c | 110 | g_free(s->backing_file_str); |
4653456a | 111 | blk_unref(s->top); |
9e85cd5c SH |
112 | } |
113 | ||
f67432a2 | 114 | static int coroutine_fn commit_run(Job *job, Error **errp) |
9e85cd5c | 115 | { |
f67432a2 | 116 | CommitBlockJob *s = container_of(job, CommitBlockJob, common.job); |
317a6676 | 117 | int64_t offset; |
f14a39cc | 118 | uint64_t delay_ns = 0; |
747ff602 | 119 | int ret = 0; |
51b0a488 | 120 | int64_t n = 0; /* bytes */ |
9e85cd5c | 121 | void *buf = NULL; |
05df8a6a | 122 | int64_t len, base_len; |
747ff602 | 123 | |
05df8a6a KW |
124 | ret = len = blk_getlength(s->top); |
125 | if (len < 0) { | |
9e85cd5c | 126 | goto out; |
747ff602 | 127 | } |
30a5c887 | 128 | job_progress_set_remaining(&s->common.job, len); |
747ff602 | 129 | |
4653456a | 130 | ret = base_len = blk_getlength(s->base); |
747ff602 | 131 | if (base_len < 0) { |
9e85cd5c | 132 | goto out; |
747ff602 JC |
133 | } |
134 | ||
05df8a6a | 135 | if (base_len < len) { |
8c6242b6 | 136 | ret = blk_truncate(s->base, len, false, PREALLOC_MODE_OFF, 0, NULL); |
747ff602 | 137 | if (ret) { |
9e85cd5c | 138 | goto out; |
747ff602 JC |
139 | } |
140 | } | |
141 | ||
4653456a | 142 | buf = blk_blockalign(s->top, COMMIT_BUFFER_SIZE); |
747ff602 | 143 | |
05df8a6a | 144 | for (offset = 0; offset < len; offset += n) { |
747ff602 | 145 | bool copy; |
9ad1e79f | 146 | bool error_in_source = true; |
747ff602 | 147 | |
747ff602 | 148 | /* Note that even when no rate limit is applied we need to yield |
c57b6656 | 149 | * with no pending I/O here so that bdrv_drain_all() returns. |
747ff602 | 150 | */ |
5d43e86e | 151 | job_sleep_ns(&s->common.job, delay_ns); |
daa7f2f9 | 152 | if (job_is_cancelled(&s->common.job)) { |
747ff602 JC |
153 | break; |
154 | } | |
155 | /* Copy if allocated above the base */ | |
170d3bd3 | 156 | ret = bdrv_is_allocated_above(blk_bs(s->top), blk_bs(s->base), false, |
51b0a488 | 157 | offset, COMMIT_BUFFER_SIZE, &n); |
747ff602 | 158 | copy = (ret == 1); |
51b0a488 | 159 | trace_commit_one_iteration(s, offset, n, ret); |
747ff602 | 160 | if (copy) { |
0c42e175 KW |
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); | |
9ad1e79f KW |
166 | if (ret < 0) { |
167 | error_in_source = false; | |
168 | } | |
0c42e175 | 169 | } |
747ff602 JC |
170 | } |
171 | if (ret < 0) { | |
1e8fb7f1 | 172 | BlockErrorAction action = |
9ad1e79f KW |
173 | block_job_error_action(&s->common, s->on_error, |
174 | error_in_source, -ret); | |
1e8fb7f1 | 175 | if (action == BLOCK_ERROR_ACTION_REPORT) { |
9e85cd5c | 176 | goto out; |
747ff602 JC |
177 | } else { |
178 | n = 0; | |
179 | continue; | |
180 | } | |
181 | } | |
182 | /* Publish progress */ | |
30a5c887 | 183 | job_progress_update(&s->common.job, n); |
f14a39cc | 184 | |
dee81d51 KW |
185 | if (copy) { |
186 | delay_ns = block_job_ratelimit_get_delay(&s->common, n); | |
2fe4bba1 KW |
187 | } else { |
188 | delay_ns = 0; | |
f14a39cc | 189 | } |
747ff602 JC |
190 | } |
191 | ||
192 | ret = 0; | |
193 | ||
9e85cd5c | 194 | out: |
747ff602 JC |
195 | qemu_vfree(buf); |
196 | ||
f67432a2 | 197 | return ret; |
747ff602 JC |
198 | } |
199 | ||
3fc4b10a | 200 | static const BlockJobDriver commit_job_driver = { |
33e9e9bd KW |
201 | .job_driver = { |
202 | .instance_size = sizeof(CommitBlockJob), | |
252291ea | 203 | .job_type = JOB_TYPE_COMMIT, |
80fa2c75 | 204 | .free = block_job_free, |
b15de828 | 205 | .user_resume = block_job_user_resume, |
f67432a2 | 206 | .run = commit_run, |
22dffcbe JS |
207 | .prepare = commit_prepare, |
208 | .abort = commit_abort, | |
209 | .clean = commit_clean | |
33e9e9bd | 210 | }, |
747ff602 JC |
211 | }; |
212 | ||
8dfba279 KW |
213 | static int coroutine_fn bdrv_commit_top_preadv(BlockDriverState *bs, |
214 | uint64_t offset, uint64_t bytes, QEMUIOVector *qiov, int flags) | |
215 | { | |
216 | return bdrv_co_preadv(bs->backing, offset, bytes, qiov, flags); | |
217 | } | |
218 | ||
998b3a1e | 219 | static void bdrv_commit_top_refresh_filename(BlockDriverState *bs) |
dcbf37ce | 220 | { |
dcbf37ce KW |
221 | pstrcpy(bs->exact_filename, sizeof(bs->exact_filename), |
222 | bs->backing->bs->filename); | |
223 | } | |
91965658 | 224 | |
8dfba279 | 225 | static void bdrv_commit_top_child_perm(BlockDriverState *bs, BdrvChild *c, |
bd86fb99 | 226 | const BdrvChildClass *child_class, |
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, | |
3e4d0e72 | 241 | .bdrv_co_block_status = bdrv_co_block_status_from_backing, |
dcbf37ce | 242 | .bdrv_refresh_filename = bdrv_commit_top_refresh_filename, |
91965658 | 243 | .bdrv_child_perm = bdrv_commit_top_child_perm, |
6540fd15 HR |
244 | |
245 | .is_filter = true, | |
8dfba279 KW |
246 | }; |
247 | ||
fd62c609 | 248 | void commit_start(const char *job_id, BlockDriverState *bs, |
5360782d JS |
249 | BlockDriverState *base, BlockDriverState *top, |
250 | int creation_flags, int64_t speed, | |
8254b6d9 | 251 | BlockdevOnError on_error, const char *backing_file_str, |
0db832f4 | 252 | const char *filter_node_name, Error **errp) |
747ff602 JC |
253 | { |
254 | CommitBlockJob *s; | |
3e4c5122 | 255 | BlockDriverState *iter; |
8dfba279 | 256 | BlockDriverState *commit_top_bs = NULL; |
747ff602 | 257 | Error *local_err = NULL; |
d7086422 | 258 | int ret; |
747ff602 | 259 | |
18da7f94 | 260 | assert(top != bs); |
747ff602 JC |
261 | if (top == base) { |
262 | error_setg(errp, "Invalid files for merge: top and base are the same"); | |
263 | return; | |
264 | } | |
265 | ||
75859b94 | 266 | s = block_job_create(job_id, &commit_job_driver, NULL, bs, 0, BLK_PERM_ALL, |
5360782d | 267 | speed, creation_flags, NULL, NULL, errp); |
834fe28d AG |
268 | if (!s) { |
269 | return; | |
270 | } | |
271 | ||
bde70715 | 272 | /* convert base to r/w, if necessary */ |
e70cdc57 AG |
273 | s->base_read_only = bdrv_is_read_only(base); |
274 | if (s->base_read_only) { | |
275 | if (bdrv_reopen_set_read_only(base, false, errp) != 0) { | |
d7086422 | 276 | goto fail; |
747ff602 JC |
277 | } |
278 | } | |
279 | ||
8dfba279 KW |
280 | /* Insert commit_top block node above top, so we can block consistent read |
281 | * on the backing chain below it */ | |
0db832f4 KW |
282 | commit_top_bs = bdrv_new_open_driver(&bdrv_commit_top, filter_node_name, 0, |
283 | errp); | |
8dfba279 KW |
284 | if (commit_top_bs == NULL) { |
285 | goto fail; | |
286 | } | |
d3c8c674 KW |
287 | if (!filter_node_name) { |
288 | commit_top_bs->implicit = true; | |
289 | } | |
e5182c1c HR |
290 | |
291 | /* So that we can always drop this node */ | |
292 | commit_top_bs->never_freeze = true; | |
293 | ||
0d0676a1 | 294 | commit_top_bs->total_sectors = top->total_sectors; |
8dfba279 | 295 | |
6a634199 | 296 | bdrv_append(commit_top_bs, top, &local_err); |
b69f00dd | 297 | if (local_err) { |
b69f00dd FZ |
298 | commit_top_bs = NULL; |
299 | error_propagate(errp, local_err); | |
300 | goto fail; | |
301 | } | |
8dfba279 KW |
302 | |
303 | s->commit_top_bs = commit_top_bs; | |
747ff602 | 304 | |
3e4c5122 AG |
305 | /* Block all nodes between top and base, because they will |
306 | * disappear from the chain after this operation. */ | |
307 | assert(bdrv_chain_contains(top, base)); | |
8dfba279 KW |
308 | for (iter = top; iter != base; iter = backing_bs(iter)) { |
309 | /* XXX BLK_PERM_WRITE needs to be allowed so we don't block ourselves | |
310 | * at s->base (if writes are blocked for a node, they are also blocked | |
311 | * for its backing file). The other options would be a second filter | |
312 | * driver above s->base. */ | |
313 | ret = block_job_add_bdrv(&s->common, "intermediate node", iter, 0, | |
314 | BLK_PERM_WRITE_UNCHANGED | BLK_PERM_WRITE, | |
315 | errp); | |
316 | if (ret < 0) { | |
317 | goto fail; | |
318 | } | |
3e4c5122 | 319 | } |
8dfba279 | 320 | |
df827336 AG |
321 | if (bdrv_freeze_backing_chain(commit_top_bs, base, errp) < 0) { |
322 | goto fail; | |
323 | } | |
324 | s->chain_frozen = true; | |
325 | ||
8dfba279 KW |
326 | ret = block_job_add_bdrv(&s->common, "base", base, 0, BLK_PERM_ALL, errp); |
327 | if (ret < 0) { | |
328 | goto fail; | |
329 | } | |
330 | ||
d861ab3a KW |
331 | s->base = blk_new(s->common.job.aio_context, |
332 | BLK_PERM_CONSISTENT_READ | |
8dfba279 KW |
333 | | BLK_PERM_WRITE |
334 | | BLK_PERM_RESIZE, | |
335 | BLK_PERM_CONSISTENT_READ | |
336 | | BLK_PERM_GRAPH_MOD | |
337 | | BLK_PERM_WRITE_UNCHANGED); | |
d7086422 KW |
338 | ret = blk_insert_bs(s->base, base, errp); |
339 | if (ret < 0) { | |
340 | goto fail; | |
341 | } | |
cf312932 | 342 | blk_set_disable_request_queuing(s->base, true); |
22dffcbe | 343 | s->base_bs = base; |
4653456a | 344 | |
8dfba279 | 345 | /* Required permissions are already taken with block_job_add_bdrv() */ |
d861ab3a | 346 | s->top = blk_new(s->common.job.aio_context, 0, BLK_PERM_ALL); |
b247767a | 347 | ret = blk_insert_bs(s->top, top, errp); |
d7086422 KW |
348 | if (ret < 0) { |
349 | goto fail; | |
350 | } | |
cf312932 | 351 | blk_set_disable_request_queuing(s->top, true); |
4653456a | 352 | |
54e26900 | 353 | s->backing_file_str = g_strdup(backing_file_str); |
747ff602 | 354 | s->on_error = on_error; |
747ff602 | 355 | |
5ccac6f1 | 356 | trace_commit_start(bs, base, top, s); |
da01ff7f | 357 | job_start(&s->common.job); |
d7086422 KW |
358 | return; |
359 | ||
360 | fail: | |
df827336 AG |
361 | if (s->chain_frozen) { |
362 | bdrv_unfreeze_backing_chain(commit_top_bs, base); | |
363 | } | |
d7086422 KW |
364 | if (s->base) { |
365 | blk_unref(s->base); | |
366 | } | |
367 | if (s->top) { | |
368 | blk_unref(s->top); | |
369 | } | |
065abf9f AG |
370 | if (s->base_read_only) { |
371 | bdrv_reopen_set_read_only(base, true, NULL); | |
372 | } | |
2468eed3 AG |
373 | job_early_fail(&s->common.job); |
374 | /* commit_top_bs has to be replaced after deleting the block job, | |
375 | * otherwise this would fail because of lack of permissions. */ | |
8dfba279 | 376 | if (commit_top_bs) { |
bde70715 | 377 | bdrv_replace_node(commit_top_bs, top, &error_abort); |
8dfba279 | 378 | } |
747ff602 | 379 | } |
83fd6dd3 KW |
380 | |
381 | ||
d6a644bb | 382 | #define COMMIT_BUF_SIZE (2048 * BDRV_SECTOR_SIZE) |
83fd6dd3 KW |
383 | |
384 | /* commit COW file into the raw image */ | |
385 | int bdrv_commit(BlockDriverState *bs) | |
386 | { | |
f8e2bd53 | 387 | BlockBackend *src, *backing; |
d3f06759 KW |
388 | BlockDriverState *backing_file_bs = NULL; |
389 | BlockDriverState *commit_top_bs = NULL; | |
83fd6dd3 | 390 | BlockDriver *drv = bs->drv; |
d861ab3a | 391 | AioContext *ctx; |
d6a644bb | 392 | int64_t offset, length, backing_length; |
c742a364 | 393 | int ro; |
d6a644bb | 394 | int64_t n; |
83fd6dd3 KW |
395 | int ret = 0; |
396 | uint8_t *buf = NULL; | |
d3f06759 | 397 | Error *local_err = NULL; |
83fd6dd3 KW |
398 | |
399 | if (!drv) | |
400 | return -ENOMEDIUM; | |
401 | ||
402 | if (!bs->backing) { | |
403 | return -ENOTSUP; | |
404 | } | |
405 | ||
406 | if (bdrv_op_is_blocked(bs, BLOCK_OP_TYPE_COMMIT_SOURCE, NULL) || | |
407 | bdrv_op_is_blocked(bs->backing->bs, BLOCK_OP_TYPE_COMMIT_TARGET, NULL)) { | |
408 | return -EBUSY; | |
409 | } | |
410 | ||
411 | ro = bs->backing->bs->read_only; | |
83fd6dd3 KW |
412 | |
413 | if (ro) { | |
c742a364 | 414 | if (bdrv_reopen_set_read_only(bs->backing->bs, false, NULL)) { |
83fd6dd3 KW |
415 | return -EACCES; |
416 | } | |
417 | } | |
418 | ||
d861ab3a | 419 | ctx = bdrv_get_aio_context(bs); |
2d97fde4 HR |
420 | /* WRITE_UNCHANGED is required for bdrv_make_empty() */ |
421 | src = blk_new(ctx, BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE_UNCHANGED, | |
422 | BLK_PERM_ALL); | |
d861ab3a | 423 | backing = blk_new(ctx, BLK_PERM_WRITE | BLK_PERM_RESIZE, BLK_PERM_ALL); |
d7086422 | 424 | |
d3f06759 | 425 | ret = blk_insert_bs(src, bs, &local_err); |
d7086422 | 426 | if (ret < 0) { |
d3f06759 KW |
427 | error_report_err(local_err); |
428 | goto ro_cleanup; | |
429 | } | |
430 | ||
431 | /* Insert commit_top block node above backing, so we can write to it */ | |
432 | backing_file_bs = backing_bs(bs); | |
433 | ||
434 | commit_top_bs = bdrv_new_open_driver(&bdrv_commit_top, NULL, BDRV_O_RDWR, | |
435 | &local_err); | |
436 | if (commit_top_bs == NULL) { | |
437 | error_report_err(local_err); | |
d7086422 KW |
438 | goto ro_cleanup; |
439 | } | |
440 | ||
12fa4af6 KW |
441 | bdrv_set_backing_hd(commit_top_bs, backing_file_bs, &error_abort); |
442 | bdrv_set_backing_hd(bs, commit_top_bs, &error_abort); | |
d3f06759 KW |
443 | |
444 | ret = blk_insert_bs(backing, backing_file_bs, &local_err); | |
d7086422 | 445 | if (ret < 0) { |
d3f06759 | 446 | error_report_err(local_err); |
d7086422 KW |
447 | goto ro_cleanup; |
448 | } | |
f8e2bd53 KW |
449 | |
450 | length = blk_getlength(src); | |
83fd6dd3 KW |
451 | if (length < 0) { |
452 | ret = length; | |
453 | goto ro_cleanup; | |
454 | } | |
455 | ||
f8e2bd53 | 456 | backing_length = blk_getlength(backing); |
83fd6dd3 KW |
457 | if (backing_length < 0) { |
458 | ret = backing_length; | |
459 | goto ro_cleanup; | |
460 | } | |
461 | ||
462 | /* If our top snapshot is larger than the backing file image, | |
463 | * grow the backing file image if possible. If not possible, | |
464 | * we must return an error */ | |
465 | if (length > backing_length) { | |
8c6242b6 | 466 | ret = blk_truncate(backing, length, false, PREALLOC_MODE_OFF, 0, |
c80d8b06 | 467 | &local_err); |
83fd6dd3 | 468 | if (ret < 0) { |
ed3d2ec9 | 469 | error_report_err(local_err); |
83fd6dd3 KW |
470 | goto ro_cleanup; |
471 | } | |
472 | } | |
473 | ||
f8e2bd53 KW |
474 | /* blk_try_blockalign() for src will choose an alignment that works for |
475 | * backing as well, so no need to compare the alignment manually. */ | |
d6a644bb | 476 | buf = blk_try_blockalign(src, COMMIT_BUF_SIZE); |
83fd6dd3 KW |
477 | if (buf == NULL) { |
478 | ret = -ENOMEM; | |
479 | goto ro_cleanup; | |
480 | } | |
481 | ||
d6a644bb EB |
482 | for (offset = 0; offset < length; offset += n) { |
483 | ret = bdrv_is_allocated(bs, offset, COMMIT_BUF_SIZE, &n); | |
83fd6dd3 KW |
484 | if (ret < 0) { |
485 | goto ro_cleanup; | |
486 | } | |
487 | if (ret) { | |
d6a644bb | 488 | ret = blk_pread(src, offset, buf, n); |
83fd6dd3 KW |
489 | if (ret < 0) { |
490 | goto ro_cleanup; | |
491 | } | |
492 | ||
d6a644bb | 493 | ret = blk_pwrite(backing, offset, buf, n, 0); |
83fd6dd3 KW |
494 | if (ret < 0) { |
495 | goto ro_cleanup; | |
496 | } | |
497 | } | |
498 | } | |
499 | ||
2d97fde4 HR |
500 | ret = blk_make_empty(src, NULL); |
501 | /* Ignore -ENOTSUP */ | |
502 | if (ret < 0 && ret != -ENOTSUP) { | |
503 | goto ro_cleanup; | |
83fd6dd3 KW |
504 | } |
505 | ||
2d97fde4 HR |
506 | blk_flush(src); |
507 | ||
83fd6dd3 KW |
508 | /* |
509 | * Make sure all data we wrote to the backing device is actually | |
510 | * stable on disk. | |
511 | */ | |
f8e2bd53 | 512 | blk_flush(backing); |
83fd6dd3 KW |
513 | |
514 | ret = 0; | |
515 | ro_cleanup: | |
516 | qemu_vfree(buf); | |
517 | ||
f8e2bd53 | 518 | blk_unref(backing); |
d3f06759 | 519 | if (backing_file_bs) { |
12fa4af6 | 520 | bdrv_set_backing_hd(bs, backing_file_bs, &error_abort); |
d3f06759 KW |
521 | } |
522 | bdrv_unref(commit_top_bs); | |
523 | blk_unref(src); | |
f8e2bd53 | 524 | |
83fd6dd3 KW |
525 | if (ro) { |
526 | /* ignoring error return here */ | |
c742a364 | 527 | bdrv_reopen_set_read_only(bs->backing->bs, true, NULL); |
83fd6dd3 KW |
528 | } |
529 | ||
530 | return ret; | |
531 | } |