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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; | |
92aa5c6d | 39 | BlockdevOnError on_error; |
747ff602 | 40 | int base_flags; |
54e26900 | 41 | char *backing_file_str; |
747ff602 JC |
42 | } CommitBlockJob; |
43 | ||
4653456a | 44 | static int coroutine_fn commit_populate(BlockBackend *bs, BlockBackend *base, |
d8a98584 | 45 | int64_t offset, uint64_t bytes, |
747ff602 JC |
46 | void *buf) |
47 | { | |
48 | int ret = 0; | |
4653456a KW |
49 | QEMUIOVector qiov; |
50 | struct iovec iov = { | |
51 | .iov_base = buf, | |
d8a98584 | 52 | .iov_len = bytes, |
4653456a | 53 | }; |
747ff602 | 54 | |
d8a98584 | 55 | assert(bytes < SIZE_MAX); |
4653456a KW |
56 | qemu_iovec_init_external(&qiov, &iov, 1); |
57 | ||
d8a98584 | 58 | ret = blk_co_preadv(bs, offset, qiov.size, &qiov, 0); |
4653456a | 59 | if (ret < 0) { |
747ff602 JC |
60 | return ret; |
61 | } | |
62 | ||
d8a98584 | 63 | ret = blk_co_pwritev(base, offset, qiov.size, &qiov, 0); |
4653456a | 64 | if (ret < 0) { |
747ff602 JC |
65 | return ret; |
66 | } | |
67 | ||
68 | return 0; | |
69 | } | |
70 | ||
f369b48d | 71 | static void commit_exit(Job *job) |
747ff602 | 72 | { |
1908a559 KW |
73 | CommitBlockJob *s = container_of(job, CommitBlockJob, common.job); |
74 | BlockJob *bjob = &s->common; | |
4653456a KW |
75 | BlockDriverState *top = blk_bs(s->top); |
76 | BlockDriverState *base = blk_bs(s->base); | |
bde70715 | 77 | BlockDriverState *commit_top_bs = s->commit_top_bs; |
8dfba279 KW |
78 | bool remove_commit_top_bs = false; |
79 | ||
bde70715 | 80 | /* Make sure commit_top_bs and top stay around until bdrv_replace_node() */ |
19ebd13e | 81 | bdrv_ref(top); |
bde70715 | 82 | bdrv_ref(commit_top_bs); |
19ebd13e | 83 | |
8dfba279 KW |
84 | /* Remove base node parent that still uses BLK_PERM_WRITE/RESIZE before |
85 | * the normal backing chain can be restored. */ | |
86 | blk_unref(s->base); | |
9e85cd5c | 87 | |
f369b48d | 88 | if (!job_is_cancelled(job) && job->ret == 0) { |
9e85cd5c | 89 | /* success */ |
f369b48d JS |
90 | job->ret = bdrv_drop_intermediate(s->commit_top_bs, base, |
91 | s->backing_file_str); | |
bde70715 | 92 | } else { |
8dfba279 KW |
93 | /* XXX Can (or should) we somehow keep 'consistent read' blocked even |
94 | * after the failed/cancelled commit job is gone? If we already wrote | |
95 | * something to base, the intermediate images aren't valid any more. */ | |
96 | remove_commit_top_bs = true; | |
9e85cd5c SH |
97 | } |
98 | ||
99 | /* restore base open flags here if appropriate (e.g., change the base back | |
100 | * to r/o). These reopens do not need to be atomic, since we won't abort | |
101 | * even on failure here */ | |
102 | if (s->base_flags != bdrv_get_flags(base)) { | |
103 | bdrv_reopen(base, s->base_flags, NULL); | |
104 | } | |
9e85cd5c | 105 | g_free(s->backing_file_str); |
4653456a | 106 | blk_unref(s->top); |
4f78a16f KW |
107 | |
108 | /* If there is more than one reference to the job (e.g. if called from | |
3d70ff53 KW |
109 | * job_finish_sync()), job_completed() won't free it and therefore the |
110 | * blockers on the intermediate nodes remain. This would cause | |
6a74c075 | 111 | * bdrv_set_backing_hd() to fail. */ |
1908a559 | 112 | block_job_remove_all_bdrv(bjob); |
4f78a16f | 113 | |
8dfba279 KW |
114 | /* If bdrv_drop_intermediate() didn't already do that, remove the commit |
115 | * filter driver from the backing chain. Do this as the final step so that | |
116 | * the 'consistent read' permission can be granted. */ | |
117 | if (remove_commit_top_bs) { | |
bde70715 KW |
118 | bdrv_child_try_set_perm(commit_top_bs->backing, 0, BLK_PERM_ALL, |
119 | &error_abort); | |
120 | bdrv_replace_node(commit_top_bs, backing_bs(commit_top_bs), | |
121 | &error_abort); | |
8dfba279 | 122 | } |
19ebd13e | 123 | |
bde70715 | 124 | bdrv_unref(commit_top_bs); |
19ebd13e | 125 | bdrv_unref(top); |
9e85cd5c SH |
126 | } |
127 | ||
f67432a2 | 128 | static int coroutine_fn commit_run(Job *job, Error **errp) |
9e85cd5c | 129 | { |
f67432a2 | 130 | CommitBlockJob *s = container_of(job, CommitBlockJob, common.job); |
317a6676 | 131 | int64_t offset; |
f14a39cc | 132 | uint64_t delay_ns = 0; |
747ff602 | 133 | int ret = 0; |
51b0a488 | 134 | int64_t n = 0; /* bytes */ |
9e85cd5c | 135 | void *buf = NULL; |
747ff602 | 136 | int bytes_written = 0; |
05df8a6a | 137 | int64_t len, base_len; |
747ff602 | 138 | |
05df8a6a KW |
139 | ret = len = blk_getlength(s->top); |
140 | if (len < 0) { | |
9e85cd5c | 141 | goto out; |
747ff602 | 142 | } |
30a5c887 | 143 | job_progress_set_remaining(&s->common.job, len); |
747ff602 | 144 | |
4653456a | 145 | ret = base_len = blk_getlength(s->base); |
747ff602 | 146 | if (base_len < 0) { |
9e85cd5c | 147 | goto out; |
747ff602 JC |
148 | } |
149 | ||
05df8a6a KW |
150 | if (base_len < len) { |
151 | ret = blk_truncate(s->base, len, PREALLOC_MODE_OFF, NULL); | |
747ff602 | 152 | if (ret) { |
9e85cd5c | 153 | goto out; |
747ff602 JC |
154 | } |
155 | } | |
156 | ||
4653456a | 157 | buf = blk_blockalign(s->top, COMMIT_BUFFER_SIZE); |
747ff602 | 158 | |
05df8a6a | 159 | for (offset = 0; offset < len; offset += n) { |
747ff602 JC |
160 | bool copy; |
161 | ||
747ff602 | 162 | /* Note that even when no rate limit is applied we need to yield |
c57b6656 | 163 | * with no pending I/O here so that bdrv_drain_all() returns. |
747ff602 | 164 | */ |
5d43e86e | 165 | job_sleep_ns(&s->common.job, delay_ns); |
daa7f2f9 | 166 | if (job_is_cancelled(&s->common.job)) { |
747ff602 JC |
167 | break; |
168 | } | |
169 | /* Copy if allocated above the base */ | |
4653456a | 170 | ret = bdrv_is_allocated_above(blk_bs(s->top), blk_bs(s->base), |
51b0a488 | 171 | offset, COMMIT_BUFFER_SIZE, &n); |
747ff602 | 172 | copy = (ret == 1); |
51b0a488 | 173 | trace_commit_one_iteration(s, offset, n, ret); |
747ff602 | 174 | if (copy) { |
51b0a488 EB |
175 | ret = commit_populate(s->top, s->base, offset, n, buf); |
176 | bytes_written += n; | |
747ff602 JC |
177 | } |
178 | if (ret < 0) { | |
1e8fb7f1 KW |
179 | BlockErrorAction action = |
180 | block_job_error_action(&s->common, false, s->on_error, -ret); | |
181 | if (action == BLOCK_ERROR_ACTION_REPORT) { | |
9e85cd5c | 182 | goto out; |
747ff602 JC |
183 | } else { |
184 | n = 0; | |
185 | continue; | |
186 | } | |
187 | } | |
188 | /* Publish progress */ | |
30a5c887 | 189 | job_progress_update(&s->common.job, n); |
f14a39cc | 190 | |
dee81d51 KW |
191 | if (copy) { |
192 | delay_ns = block_job_ratelimit_get_delay(&s->common, n); | |
2fe4bba1 KW |
193 | } else { |
194 | delay_ns = 0; | |
f14a39cc | 195 | } |
747ff602 JC |
196 | } |
197 | ||
198 | ret = 0; | |
199 | ||
9e85cd5c | 200 | out: |
747ff602 JC |
201 | qemu_vfree(buf); |
202 | ||
f67432a2 | 203 | return ret; |
747ff602 JC |
204 | } |
205 | ||
3fc4b10a | 206 | static const BlockJobDriver commit_job_driver = { |
33e9e9bd KW |
207 | .job_driver = { |
208 | .instance_size = sizeof(CommitBlockJob), | |
252291ea | 209 | .job_type = JOB_TYPE_COMMIT, |
80fa2c75 | 210 | .free = block_job_free, |
b15de828 | 211 | .user_resume = block_job_user_resume, |
b69f777d | 212 | .drain = block_job_drain, |
f67432a2 | 213 | .run = commit_run, |
f369b48d | 214 | .exit = commit_exit, |
33e9e9bd | 215 | }, |
747ff602 JC |
216 | }; |
217 | ||
8dfba279 KW |
218 | static int coroutine_fn bdrv_commit_top_preadv(BlockDriverState *bs, |
219 | uint64_t offset, uint64_t bytes, QEMUIOVector *qiov, int flags) | |
220 | { | |
221 | return bdrv_co_preadv(bs->backing, offset, bytes, qiov, flags); | |
222 | } | |
223 | ||
dcbf37ce KW |
224 | static void bdrv_commit_top_refresh_filename(BlockDriverState *bs, QDict *opts) |
225 | { | |
226 | bdrv_refresh_filename(bs->backing->bs); | |
227 | pstrcpy(bs->exact_filename, sizeof(bs->exact_filename), | |
228 | bs->backing->bs->filename); | |
229 | } | |
91965658 | 230 | |
8dfba279 KW |
231 | static void bdrv_commit_top_child_perm(BlockDriverState *bs, BdrvChild *c, |
232 | const BdrvChildRole *role, | |
e0995dc3 | 233 | BlockReopenQueue *reopen_queue, |
8dfba279 KW |
234 | uint64_t perm, uint64_t shared, |
235 | uint64_t *nperm, uint64_t *nshared) | |
236 | { | |
237 | *nperm = 0; | |
238 | *nshared = BLK_PERM_ALL; | |
239 | } | |
240 | ||
241 | /* Dummy node that provides consistent read to its users without requiring it | |
242 | * from its backing file and that allows writes on the backing file chain. */ | |
243 | static BlockDriver bdrv_commit_top = { | |
91965658 KW |
244 | .format_name = "commit_top", |
245 | .bdrv_co_preadv = bdrv_commit_top_preadv, | |
3e4d0e72 | 246 | .bdrv_co_block_status = bdrv_co_block_status_from_backing, |
dcbf37ce | 247 | .bdrv_refresh_filename = bdrv_commit_top_refresh_filename, |
91965658 | 248 | .bdrv_child_perm = bdrv_commit_top_child_perm, |
8dfba279 KW |
249 | }; |
250 | ||
fd62c609 AG |
251 | void commit_start(const char *job_id, BlockDriverState *bs, |
252 | BlockDriverState *base, BlockDriverState *top, int64_t speed, | |
8254b6d9 | 253 | BlockdevOnError on_error, const char *backing_file_str, |
0db832f4 | 254 | const char *filter_node_name, Error **errp) |
747ff602 JC |
255 | { |
256 | CommitBlockJob *s; | |
747ff602 | 257 | int orig_base_flags; |
3e4c5122 | 258 | BlockDriverState *iter; |
8dfba279 | 259 | BlockDriverState *commit_top_bs = NULL; |
747ff602 | 260 | Error *local_err = NULL; |
d7086422 | 261 | int ret; |
747ff602 | 262 | |
18da7f94 | 263 | assert(top != bs); |
747ff602 JC |
264 | if (top == base) { |
265 | error_setg(errp, "Invalid files for merge: top and base are the same"); | |
266 | return; | |
267 | } | |
268 | ||
75859b94 | 269 | s = block_job_create(job_id, &commit_job_driver, NULL, bs, 0, BLK_PERM_ALL, |
bb02b65c | 270 | speed, JOB_DEFAULT, NULL, NULL, errp); |
834fe28d AG |
271 | if (!s) { |
272 | return; | |
273 | } | |
274 | ||
bde70715 KW |
275 | /* convert base to r/w, if necessary */ |
276 | orig_base_flags = bdrv_get_flags(base); | |
3db2bd55 | 277 | if (!(orig_base_flags & BDRV_O_RDWR)) { |
44487eb9 | 278 | bdrv_reopen(base, orig_base_flags | BDRV_O_RDWR, &local_err); |
747ff602 JC |
279 | if (local_err != NULL) { |
280 | error_propagate(errp, local_err); | |
d7086422 | 281 | goto fail; |
747ff602 JC |
282 | } |
283 | } | |
284 | ||
8dfba279 KW |
285 | /* Insert commit_top block node above top, so we can block consistent read |
286 | * on the backing chain below it */ | |
0db832f4 KW |
287 | commit_top_bs = bdrv_new_open_driver(&bdrv_commit_top, filter_node_name, 0, |
288 | errp); | |
8dfba279 KW |
289 | if (commit_top_bs == NULL) { |
290 | goto fail; | |
291 | } | |
d3c8c674 KW |
292 | if (!filter_node_name) { |
293 | commit_top_bs->implicit = true; | |
294 | } | |
0d0676a1 | 295 | commit_top_bs->total_sectors = top->total_sectors; |
02be4aeb | 296 | bdrv_set_aio_context(commit_top_bs, bdrv_get_aio_context(top)); |
8dfba279 | 297 | |
b69f00dd FZ |
298 | bdrv_set_backing_hd(commit_top_bs, top, &local_err); |
299 | if (local_err) { | |
300 | bdrv_unref(commit_top_bs); | |
301 | commit_top_bs = NULL; | |
302 | error_propagate(errp, local_err); | |
303 | goto fail; | |
304 | } | |
61f09cea | 305 | bdrv_replace_node(top, commit_top_bs, &local_err); |
b69f00dd FZ |
306 | if (local_err) { |
307 | bdrv_unref(commit_top_bs); | |
308 | commit_top_bs = NULL; | |
309 | error_propagate(errp, local_err); | |
310 | goto fail; | |
311 | } | |
8dfba279 KW |
312 | |
313 | s->commit_top_bs = commit_top_bs; | |
314 | bdrv_unref(commit_top_bs); | |
747ff602 | 315 | |
3e4c5122 AG |
316 | /* Block all nodes between top and base, because they will |
317 | * disappear from the chain after this operation. */ | |
318 | assert(bdrv_chain_contains(top, base)); | |
8dfba279 KW |
319 | for (iter = top; iter != base; iter = backing_bs(iter)) { |
320 | /* XXX BLK_PERM_WRITE needs to be allowed so we don't block ourselves | |
321 | * at s->base (if writes are blocked for a node, they are also blocked | |
322 | * for its backing file). The other options would be a second filter | |
323 | * driver above s->base. */ | |
324 | ret = block_job_add_bdrv(&s->common, "intermediate node", iter, 0, | |
325 | BLK_PERM_WRITE_UNCHANGED | BLK_PERM_WRITE, | |
326 | errp); | |
327 | if (ret < 0) { | |
328 | goto fail; | |
329 | } | |
3e4c5122 | 330 | } |
8dfba279 KW |
331 | |
332 | ret = block_job_add_bdrv(&s->common, "base", base, 0, BLK_PERM_ALL, errp); | |
333 | if (ret < 0) { | |
334 | goto fail; | |
335 | } | |
336 | ||
8dfba279 KW |
337 | s->base = blk_new(BLK_PERM_CONSISTENT_READ |
338 | | BLK_PERM_WRITE | |
339 | | BLK_PERM_RESIZE, | |
340 | BLK_PERM_CONSISTENT_READ | |
341 | | BLK_PERM_GRAPH_MOD | |
342 | | BLK_PERM_WRITE_UNCHANGED); | |
d7086422 KW |
343 | ret = blk_insert_bs(s->base, base, errp); |
344 | if (ret < 0) { | |
345 | goto fail; | |
346 | } | |
4653456a | 347 | |
8dfba279 | 348 | /* Required permissions are already taken with block_job_add_bdrv() */ |
6d0eb64d | 349 | s->top = blk_new(0, BLK_PERM_ALL); |
b247767a | 350 | ret = blk_insert_bs(s->top, top, errp); |
d7086422 KW |
351 | if (ret < 0) { |
352 | goto fail; | |
353 | } | |
4653456a | 354 | |
bde70715 | 355 | s->base_flags = orig_base_flags; |
54e26900 | 356 | s->backing_file_str = g_strdup(backing_file_str); |
747ff602 | 357 | s->on_error = on_error; |
747ff602 | 358 | |
5ccac6f1 | 359 | trace_commit_start(bs, base, top, s); |
da01ff7f | 360 | job_start(&s->common.job); |
d7086422 KW |
361 | return; |
362 | ||
363 | fail: | |
364 | if (s->base) { | |
365 | blk_unref(s->base); | |
366 | } | |
367 | if (s->top) { | |
368 | blk_unref(s->top); | |
369 | } | |
8dfba279 | 370 | if (commit_top_bs) { |
bde70715 | 371 | bdrv_replace_node(commit_top_bs, top, &error_abort); |
8dfba279 | 372 | } |
4ad35181 | 373 | job_early_fail(&s->common.job); |
747ff602 | 374 | } |
83fd6dd3 KW |
375 | |
376 | ||
d6a644bb | 377 | #define COMMIT_BUF_SIZE (2048 * BDRV_SECTOR_SIZE) |
83fd6dd3 KW |
378 | |
379 | /* commit COW file into the raw image */ | |
380 | int bdrv_commit(BlockDriverState *bs) | |
381 | { | |
f8e2bd53 | 382 | BlockBackend *src, *backing; |
d3f06759 KW |
383 | BlockDriverState *backing_file_bs = NULL; |
384 | BlockDriverState *commit_top_bs = NULL; | |
83fd6dd3 | 385 | BlockDriver *drv = bs->drv; |
d6a644bb EB |
386 | int64_t offset, length, backing_length; |
387 | int ro, open_flags; | |
388 | int64_t n; | |
83fd6dd3 KW |
389 | int ret = 0; |
390 | uint8_t *buf = NULL; | |
d3f06759 | 391 | Error *local_err = NULL; |
83fd6dd3 KW |
392 | |
393 | if (!drv) | |
394 | return -ENOMEDIUM; | |
395 | ||
396 | if (!bs->backing) { | |
397 | return -ENOTSUP; | |
398 | } | |
399 | ||
400 | if (bdrv_op_is_blocked(bs, BLOCK_OP_TYPE_COMMIT_SOURCE, NULL) || | |
401 | bdrv_op_is_blocked(bs->backing->bs, BLOCK_OP_TYPE_COMMIT_TARGET, NULL)) { | |
402 | return -EBUSY; | |
403 | } | |
404 | ||
405 | ro = bs->backing->bs->read_only; | |
406 | open_flags = bs->backing->bs->open_flags; | |
407 | ||
408 | if (ro) { | |
409 | if (bdrv_reopen(bs->backing->bs, open_flags | BDRV_O_RDWR, NULL)) { | |
410 | return -EACCES; | |
411 | } | |
412 | } | |
413 | ||
d3f06759 KW |
414 | src = blk_new(BLK_PERM_CONSISTENT_READ, BLK_PERM_ALL); |
415 | backing = blk_new(BLK_PERM_WRITE | BLK_PERM_RESIZE, BLK_PERM_ALL); | |
d7086422 | 416 | |
d3f06759 | 417 | ret = blk_insert_bs(src, bs, &local_err); |
d7086422 | 418 | if (ret < 0) { |
d3f06759 KW |
419 | error_report_err(local_err); |
420 | goto ro_cleanup; | |
421 | } | |
422 | ||
423 | /* Insert commit_top block node above backing, so we can write to it */ | |
424 | backing_file_bs = backing_bs(bs); | |
425 | ||
426 | commit_top_bs = bdrv_new_open_driver(&bdrv_commit_top, NULL, BDRV_O_RDWR, | |
427 | &local_err); | |
428 | if (commit_top_bs == NULL) { | |
429 | error_report_err(local_err); | |
d7086422 KW |
430 | goto ro_cleanup; |
431 | } | |
02be4aeb | 432 | bdrv_set_aio_context(commit_top_bs, bdrv_get_aio_context(backing_file_bs)); |
d7086422 | 433 | |
12fa4af6 KW |
434 | bdrv_set_backing_hd(commit_top_bs, backing_file_bs, &error_abort); |
435 | bdrv_set_backing_hd(bs, commit_top_bs, &error_abort); | |
d3f06759 KW |
436 | |
437 | ret = blk_insert_bs(backing, backing_file_bs, &local_err); | |
d7086422 | 438 | if (ret < 0) { |
d3f06759 | 439 | error_report_err(local_err); |
d7086422 KW |
440 | goto ro_cleanup; |
441 | } | |
f8e2bd53 KW |
442 | |
443 | length = blk_getlength(src); | |
83fd6dd3 KW |
444 | if (length < 0) { |
445 | ret = length; | |
446 | goto ro_cleanup; | |
447 | } | |
448 | ||
f8e2bd53 | 449 | backing_length = blk_getlength(backing); |
83fd6dd3 KW |
450 | if (backing_length < 0) { |
451 | ret = backing_length; | |
452 | goto ro_cleanup; | |
453 | } | |
454 | ||
455 | /* If our top snapshot is larger than the backing file image, | |
456 | * grow the backing file image if possible. If not possible, | |
457 | * we must return an error */ | |
458 | if (length > backing_length) { | |
3a691c50 | 459 | ret = blk_truncate(backing, length, PREALLOC_MODE_OFF, &local_err); |
83fd6dd3 | 460 | if (ret < 0) { |
ed3d2ec9 | 461 | error_report_err(local_err); |
83fd6dd3 KW |
462 | goto ro_cleanup; |
463 | } | |
464 | } | |
465 | ||
f8e2bd53 KW |
466 | /* blk_try_blockalign() for src will choose an alignment that works for |
467 | * backing as well, so no need to compare the alignment manually. */ | |
d6a644bb | 468 | buf = blk_try_blockalign(src, COMMIT_BUF_SIZE); |
83fd6dd3 KW |
469 | if (buf == NULL) { |
470 | ret = -ENOMEM; | |
471 | goto ro_cleanup; | |
472 | } | |
473 | ||
d6a644bb EB |
474 | for (offset = 0; offset < length; offset += n) { |
475 | ret = bdrv_is_allocated(bs, offset, COMMIT_BUF_SIZE, &n); | |
83fd6dd3 KW |
476 | if (ret < 0) { |
477 | goto ro_cleanup; | |
478 | } | |
479 | if (ret) { | |
d6a644bb | 480 | ret = blk_pread(src, offset, buf, n); |
83fd6dd3 KW |
481 | if (ret < 0) { |
482 | goto ro_cleanup; | |
483 | } | |
484 | ||
d6a644bb | 485 | ret = blk_pwrite(backing, offset, buf, n, 0); |
83fd6dd3 KW |
486 | if (ret < 0) { |
487 | goto ro_cleanup; | |
488 | } | |
489 | } | |
490 | } | |
491 | ||
492 | if (drv->bdrv_make_empty) { | |
493 | ret = drv->bdrv_make_empty(bs); | |
494 | if (ret < 0) { | |
495 | goto ro_cleanup; | |
496 | } | |
f8e2bd53 | 497 | blk_flush(src); |
83fd6dd3 KW |
498 | } |
499 | ||
500 | /* | |
501 | * Make sure all data we wrote to the backing device is actually | |
502 | * stable on disk. | |
503 | */ | |
f8e2bd53 | 504 | blk_flush(backing); |
83fd6dd3 KW |
505 | |
506 | ret = 0; | |
507 | ro_cleanup: | |
508 | qemu_vfree(buf); | |
509 | ||
f8e2bd53 | 510 | blk_unref(backing); |
d3f06759 | 511 | if (backing_file_bs) { |
12fa4af6 | 512 | bdrv_set_backing_hd(bs, backing_file_bs, &error_abort); |
d3f06759 KW |
513 | } |
514 | bdrv_unref(commit_top_bs); | |
515 | blk_unref(src); | |
f8e2bd53 | 516 | |
83fd6dd3 KW |
517 | if (ro) { |
518 | /* ignoring error return here */ | |
519 | bdrv_reopen(bs->backing->bs, open_flags & ~BDRV_O_RDWR, NULL); | |
520 | } | |
521 | ||
522 | return ret; | |
523 | } |