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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 | ||
9e85cd5c SH |
71 | typedef struct { |
72 | int ret; | |
73 | } CommitCompleteData; | |
74 | ||
75 | static void commit_complete(BlockJob *job, void *opaque) | |
747ff602 | 76 | { |
9e85cd5c SH |
77 | CommitBlockJob *s = container_of(job, CommitBlockJob, common); |
78 | CommitCompleteData *data = opaque; | |
4653456a KW |
79 | BlockDriverState *top = blk_bs(s->top); |
80 | BlockDriverState *base = blk_bs(s->base); | |
bde70715 | 81 | BlockDriverState *commit_top_bs = s->commit_top_bs; |
9e85cd5c | 82 | int ret = data->ret; |
8dfba279 KW |
83 | bool remove_commit_top_bs = false; |
84 | ||
bde70715 | 85 | /* Make sure commit_top_bs and top stay around until bdrv_replace_node() */ |
19ebd13e | 86 | bdrv_ref(top); |
bde70715 | 87 | bdrv_ref(commit_top_bs); |
19ebd13e | 88 | |
8dfba279 KW |
89 | /* Remove base node parent that still uses BLK_PERM_WRITE/RESIZE before |
90 | * the normal backing chain can be restored. */ | |
91 | blk_unref(s->base); | |
9e85cd5c | 92 | |
daa7f2f9 | 93 | if (!job_is_cancelled(&s->common.job) && ret == 0) { |
9e85cd5c | 94 | /* success */ |
bde70715 | 95 | ret = bdrv_drop_intermediate(s->commit_top_bs, base, |
8dfba279 | 96 | s->backing_file_str); |
bde70715 | 97 | } else { |
8dfba279 KW |
98 | /* XXX Can (or should) we somehow keep 'consistent read' blocked even |
99 | * after the failed/cancelled commit job is gone? If we already wrote | |
100 | * something to base, the intermediate images aren't valid any more. */ | |
101 | remove_commit_top_bs = true; | |
9e85cd5c SH |
102 | } |
103 | ||
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 */ | |
107 | if (s->base_flags != bdrv_get_flags(base)) { | |
108 | bdrv_reopen(base, s->base_flags, NULL); | |
109 | } | |
9e85cd5c | 110 | g_free(s->backing_file_str); |
4653456a | 111 | blk_unref(s->top); |
4f78a16f KW |
112 | |
113 | /* If there is more than one reference to the job (e.g. if called from | |
114 | * block_job_finish_sync()), block_job_completed() won't free it and | |
115 | * therefore the blockers on the intermediate nodes remain. This would | |
116 | * cause bdrv_set_backing_hd() to fail. */ | |
117 | block_job_remove_all_bdrv(job); | |
118 | ||
9e85cd5c SH |
119 | block_job_completed(&s->common, ret); |
120 | g_free(data); | |
8dfba279 KW |
121 | |
122 | /* If bdrv_drop_intermediate() didn't already do that, remove the commit | |
123 | * filter driver from the backing chain. Do this as the final step so that | |
124 | * the 'consistent read' permission can be granted. */ | |
125 | if (remove_commit_top_bs) { | |
bde70715 KW |
126 | bdrv_child_try_set_perm(commit_top_bs->backing, 0, BLK_PERM_ALL, |
127 | &error_abort); | |
128 | bdrv_replace_node(commit_top_bs, backing_bs(commit_top_bs), | |
129 | &error_abort); | |
8dfba279 | 130 | } |
19ebd13e | 131 | |
bde70715 | 132 | bdrv_unref(commit_top_bs); |
19ebd13e | 133 | bdrv_unref(top); |
9e85cd5c SH |
134 | } |
135 | ||
136 | static void coroutine_fn commit_run(void *opaque) | |
137 | { | |
138 | CommitBlockJob *s = opaque; | |
139 | CommitCompleteData *data; | |
317a6676 | 140 | int64_t offset; |
f14a39cc | 141 | uint64_t delay_ns = 0; |
747ff602 | 142 | int ret = 0; |
51b0a488 | 143 | int64_t n = 0; /* bytes */ |
9e85cd5c | 144 | void *buf = NULL; |
747ff602 | 145 | int bytes_written = 0; |
05df8a6a | 146 | int64_t len, base_len; |
747ff602 | 147 | |
05df8a6a KW |
148 | ret = len = blk_getlength(s->top); |
149 | if (len < 0) { | |
9e85cd5c | 150 | goto out; |
747ff602 | 151 | } |
05df8a6a | 152 | block_job_progress_set_remaining(&s->common, len); |
747ff602 | 153 | |
4653456a | 154 | ret = base_len = blk_getlength(s->base); |
747ff602 | 155 | if (base_len < 0) { |
9e85cd5c | 156 | goto out; |
747ff602 JC |
157 | } |
158 | ||
05df8a6a KW |
159 | if (base_len < len) { |
160 | ret = blk_truncate(s->base, len, PREALLOC_MODE_OFF, NULL); | |
747ff602 | 161 | if (ret) { |
9e85cd5c | 162 | goto out; |
747ff602 JC |
163 | } |
164 | } | |
165 | ||
4653456a | 166 | buf = blk_blockalign(s->top, COMMIT_BUFFER_SIZE); |
747ff602 | 167 | |
05df8a6a | 168 | for (offset = 0; offset < len; offset += n) { |
747ff602 JC |
169 | bool copy; |
170 | ||
747ff602 | 171 | /* Note that even when no rate limit is applied we need to yield |
c57b6656 | 172 | * with no pending I/O here so that bdrv_drain_all() returns. |
747ff602 | 173 | */ |
5bf1d5a7 | 174 | block_job_sleep_ns(&s->common, delay_ns); |
daa7f2f9 | 175 | if (job_is_cancelled(&s->common.job)) { |
747ff602 JC |
176 | break; |
177 | } | |
178 | /* Copy if allocated above the base */ | |
4653456a | 179 | ret = bdrv_is_allocated_above(blk_bs(s->top), blk_bs(s->base), |
51b0a488 | 180 | offset, COMMIT_BUFFER_SIZE, &n); |
747ff602 | 181 | copy = (ret == 1); |
51b0a488 | 182 | trace_commit_one_iteration(s, offset, n, ret); |
747ff602 | 183 | if (copy) { |
51b0a488 EB |
184 | ret = commit_populate(s->top, s->base, offset, n, buf); |
185 | bytes_written += n; | |
747ff602 JC |
186 | } |
187 | if (ret < 0) { | |
1e8fb7f1 KW |
188 | BlockErrorAction action = |
189 | block_job_error_action(&s->common, false, s->on_error, -ret); | |
190 | if (action == BLOCK_ERROR_ACTION_REPORT) { | |
9e85cd5c | 191 | goto out; |
747ff602 JC |
192 | } else { |
193 | n = 0; | |
194 | continue; | |
195 | } | |
196 | } | |
197 | /* Publish progress */ | |
05df8a6a | 198 | block_job_progress_update(&s->common, n); |
f14a39cc | 199 | |
dee81d51 KW |
200 | if (copy) { |
201 | delay_ns = block_job_ratelimit_get_delay(&s->common, n); | |
2fe4bba1 KW |
202 | } else { |
203 | delay_ns = 0; | |
f14a39cc | 204 | } |
747ff602 JC |
205 | } |
206 | ||
207 | ret = 0; | |
208 | ||
9e85cd5c | 209 | out: |
747ff602 JC |
210 | qemu_vfree(buf); |
211 | ||
9e85cd5c SH |
212 | data = g_malloc(sizeof(*data)); |
213 | data->ret = ret; | |
214 | block_job_defer_to_main_loop(&s->common, commit_complete, data); | |
747ff602 JC |
215 | } |
216 | ||
3fc4b10a | 217 | static const BlockJobDriver commit_job_driver = { |
33e9e9bd KW |
218 | .job_driver = { |
219 | .instance_size = sizeof(CommitBlockJob), | |
252291ea | 220 | .job_type = JOB_TYPE_COMMIT, |
80fa2c75 | 221 | .free = block_job_free, |
33e9e9bd | 222 | }, |
a7815a76 | 223 | .start = commit_run, |
747ff602 JC |
224 | }; |
225 | ||
8dfba279 KW |
226 | static int coroutine_fn bdrv_commit_top_preadv(BlockDriverState *bs, |
227 | uint64_t offset, uint64_t bytes, QEMUIOVector *qiov, int flags) | |
228 | { | |
229 | return bdrv_co_preadv(bs->backing, offset, bytes, qiov, flags); | |
230 | } | |
231 | ||
dcbf37ce KW |
232 | static void bdrv_commit_top_refresh_filename(BlockDriverState *bs, QDict *opts) |
233 | { | |
234 | bdrv_refresh_filename(bs->backing->bs); | |
235 | pstrcpy(bs->exact_filename, sizeof(bs->exact_filename), | |
236 | bs->backing->bs->filename); | |
237 | } | |
91965658 | 238 | |
8dfba279 KW |
239 | static void bdrv_commit_top_close(BlockDriverState *bs) |
240 | { | |
241 | } | |
242 | ||
243 | static void bdrv_commit_top_child_perm(BlockDriverState *bs, BdrvChild *c, | |
244 | const BdrvChildRole *role, | |
e0995dc3 | 245 | BlockReopenQueue *reopen_queue, |
8dfba279 KW |
246 | uint64_t perm, uint64_t shared, |
247 | uint64_t *nperm, uint64_t *nshared) | |
248 | { | |
249 | *nperm = 0; | |
250 | *nshared = BLK_PERM_ALL; | |
251 | } | |
252 | ||
253 | /* Dummy node that provides consistent read to its users without requiring it | |
254 | * from its backing file and that allows writes on the backing file chain. */ | |
255 | static BlockDriver bdrv_commit_top = { | |
91965658 KW |
256 | .format_name = "commit_top", |
257 | .bdrv_co_preadv = bdrv_commit_top_preadv, | |
3e4d0e72 | 258 | .bdrv_co_block_status = bdrv_co_block_status_from_backing, |
dcbf37ce | 259 | .bdrv_refresh_filename = bdrv_commit_top_refresh_filename, |
91965658 KW |
260 | .bdrv_close = bdrv_commit_top_close, |
261 | .bdrv_child_perm = bdrv_commit_top_child_perm, | |
8dfba279 KW |
262 | }; |
263 | ||
fd62c609 AG |
264 | void commit_start(const char *job_id, BlockDriverState *bs, |
265 | BlockDriverState *base, BlockDriverState *top, int64_t speed, | |
8254b6d9 | 266 | BlockdevOnError on_error, const char *backing_file_str, |
0db832f4 | 267 | const char *filter_node_name, Error **errp) |
747ff602 JC |
268 | { |
269 | CommitBlockJob *s; | |
747ff602 | 270 | int orig_base_flags; |
3e4c5122 | 271 | BlockDriverState *iter; |
8dfba279 | 272 | BlockDriverState *commit_top_bs = NULL; |
747ff602 | 273 | Error *local_err = NULL; |
d7086422 | 274 | int ret; |
747ff602 | 275 | |
18da7f94 | 276 | assert(top != bs); |
747ff602 JC |
277 | if (top == base) { |
278 | error_setg(errp, "Invalid files for merge: top and base are the same"); | |
279 | return; | |
280 | } | |
281 | ||
75859b94 | 282 | s = block_job_create(job_id, &commit_job_driver, NULL, bs, 0, BLK_PERM_ALL, |
c6cc12bf | 283 | speed, BLOCK_JOB_DEFAULT, NULL, NULL, errp); |
834fe28d AG |
284 | if (!s) { |
285 | return; | |
286 | } | |
287 | ||
bde70715 KW |
288 | /* convert base to r/w, if necessary */ |
289 | orig_base_flags = bdrv_get_flags(base); | |
3db2bd55 | 290 | if (!(orig_base_flags & BDRV_O_RDWR)) { |
44487eb9 | 291 | bdrv_reopen(base, orig_base_flags | BDRV_O_RDWR, &local_err); |
747ff602 JC |
292 | if (local_err != NULL) { |
293 | error_propagate(errp, local_err); | |
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 | } | |
0d0676a1 | 308 | commit_top_bs->total_sectors = top->total_sectors; |
02be4aeb | 309 | bdrv_set_aio_context(commit_top_bs, bdrv_get_aio_context(top)); |
8dfba279 | 310 | |
b69f00dd FZ |
311 | bdrv_set_backing_hd(commit_top_bs, top, &local_err); |
312 | if (local_err) { | |
313 | bdrv_unref(commit_top_bs); | |
314 | commit_top_bs = NULL; | |
315 | error_propagate(errp, local_err); | |
316 | goto fail; | |
317 | } | |
61f09cea | 318 | bdrv_replace_node(top, commit_top_bs, &local_err); |
b69f00dd FZ |
319 | if (local_err) { |
320 | bdrv_unref(commit_top_bs); | |
321 | commit_top_bs = NULL; | |
322 | error_propagate(errp, local_err); | |
323 | goto fail; | |
324 | } | |
8dfba279 KW |
325 | |
326 | s->commit_top_bs = commit_top_bs; | |
327 | bdrv_unref(commit_top_bs); | |
747ff602 | 328 | |
3e4c5122 AG |
329 | /* Block all nodes between top and base, because they will |
330 | * disappear from the chain after this operation. */ | |
331 | assert(bdrv_chain_contains(top, base)); | |
8dfba279 KW |
332 | for (iter = top; iter != base; iter = backing_bs(iter)) { |
333 | /* XXX BLK_PERM_WRITE needs to be allowed so we don't block ourselves | |
334 | * at s->base (if writes are blocked for a node, they are also blocked | |
335 | * for its backing file). The other options would be a second filter | |
336 | * driver above s->base. */ | |
337 | ret = block_job_add_bdrv(&s->common, "intermediate node", iter, 0, | |
338 | BLK_PERM_WRITE_UNCHANGED | BLK_PERM_WRITE, | |
339 | errp); | |
340 | if (ret < 0) { | |
341 | goto fail; | |
342 | } | |
3e4c5122 | 343 | } |
8dfba279 KW |
344 | |
345 | ret = block_job_add_bdrv(&s->common, "base", base, 0, BLK_PERM_ALL, errp); | |
346 | if (ret < 0) { | |
347 | goto fail; | |
348 | } | |
349 | ||
8dfba279 KW |
350 | s->base = blk_new(BLK_PERM_CONSISTENT_READ |
351 | | BLK_PERM_WRITE | |
352 | | BLK_PERM_RESIZE, | |
353 | BLK_PERM_CONSISTENT_READ | |
354 | | BLK_PERM_GRAPH_MOD | |
355 | | BLK_PERM_WRITE_UNCHANGED); | |
d7086422 KW |
356 | ret = blk_insert_bs(s->base, base, errp); |
357 | if (ret < 0) { | |
358 | goto fail; | |
359 | } | |
4653456a | 360 | |
8dfba279 | 361 | /* Required permissions are already taken with block_job_add_bdrv() */ |
6d0eb64d | 362 | s->top = blk_new(0, BLK_PERM_ALL); |
b247767a | 363 | ret = blk_insert_bs(s->top, top, errp); |
d7086422 KW |
364 | if (ret < 0) { |
365 | goto fail; | |
366 | } | |
4653456a | 367 | |
bde70715 | 368 | s->base_flags = orig_base_flags; |
54e26900 | 369 | s->backing_file_str = g_strdup(backing_file_str); |
747ff602 | 370 | s->on_error = on_error; |
747ff602 | 371 | |
5ccac6f1 JS |
372 | trace_commit_start(bs, base, top, s); |
373 | block_job_start(&s->common); | |
d7086422 KW |
374 | return; |
375 | ||
376 | fail: | |
377 | if (s->base) { | |
378 | blk_unref(s->base); | |
379 | } | |
380 | if (s->top) { | |
381 | blk_unref(s->top); | |
382 | } | |
8dfba279 | 383 | if (commit_top_bs) { |
bde70715 | 384 | bdrv_replace_node(commit_top_bs, top, &error_abort); |
8dfba279 | 385 | } |
05b0d8e3 | 386 | block_job_early_fail(&s->common); |
747ff602 | 387 | } |
83fd6dd3 KW |
388 | |
389 | ||
d6a644bb | 390 | #define COMMIT_BUF_SIZE (2048 * BDRV_SECTOR_SIZE) |
83fd6dd3 KW |
391 | |
392 | /* commit COW file into the raw image */ | |
393 | int bdrv_commit(BlockDriverState *bs) | |
394 | { | |
f8e2bd53 | 395 | BlockBackend *src, *backing; |
d3f06759 KW |
396 | BlockDriverState *backing_file_bs = NULL; |
397 | BlockDriverState *commit_top_bs = NULL; | |
83fd6dd3 | 398 | BlockDriver *drv = bs->drv; |
d6a644bb EB |
399 | int64_t offset, length, backing_length; |
400 | int ro, open_flags; | |
401 | int64_t n; | |
83fd6dd3 KW |
402 | int ret = 0; |
403 | uint8_t *buf = NULL; | |
d3f06759 | 404 | Error *local_err = NULL; |
83fd6dd3 KW |
405 | |
406 | if (!drv) | |
407 | return -ENOMEDIUM; | |
408 | ||
409 | if (!bs->backing) { | |
410 | return -ENOTSUP; | |
411 | } | |
412 | ||
413 | if (bdrv_op_is_blocked(bs, BLOCK_OP_TYPE_COMMIT_SOURCE, NULL) || | |
414 | bdrv_op_is_blocked(bs->backing->bs, BLOCK_OP_TYPE_COMMIT_TARGET, NULL)) { | |
415 | return -EBUSY; | |
416 | } | |
417 | ||
418 | ro = bs->backing->bs->read_only; | |
419 | open_flags = bs->backing->bs->open_flags; | |
420 | ||
421 | if (ro) { | |
422 | if (bdrv_reopen(bs->backing->bs, open_flags | BDRV_O_RDWR, NULL)) { | |
423 | return -EACCES; | |
424 | } | |
425 | } | |
426 | ||
d3f06759 KW |
427 | src = blk_new(BLK_PERM_CONSISTENT_READ, BLK_PERM_ALL); |
428 | backing = blk_new(BLK_PERM_WRITE | BLK_PERM_RESIZE, BLK_PERM_ALL); | |
d7086422 | 429 | |
d3f06759 | 430 | ret = blk_insert_bs(src, bs, &local_err); |
d7086422 | 431 | if (ret < 0) { |
d3f06759 KW |
432 | error_report_err(local_err); |
433 | goto ro_cleanup; | |
434 | } | |
435 | ||
436 | /* Insert commit_top block node above backing, so we can write to it */ | |
437 | backing_file_bs = backing_bs(bs); | |
438 | ||
439 | commit_top_bs = bdrv_new_open_driver(&bdrv_commit_top, NULL, BDRV_O_RDWR, | |
440 | &local_err); | |
441 | if (commit_top_bs == NULL) { | |
442 | error_report_err(local_err); | |
d7086422 KW |
443 | goto ro_cleanup; |
444 | } | |
02be4aeb | 445 | bdrv_set_aio_context(commit_top_bs, bdrv_get_aio_context(backing_file_bs)); |
d7086422 | 446 | |
12fa4af6 KW |
447 | bdrv_set_backing_hd(commit_top_bs, backing_file_bs, &error_abort); |
448 | bdrv_set_backing_hd(bs, commit_top_bs, &error_abort); | |
d3f06759 KW |
449 | |
450 | ret = blk_insert_bs(backing, backing_file_bs, &local_err); | |
d7086422 | 451 | if (ret < 0) { |
d3f06759 | 452 | error_report_err(local_err); |
d7086422 KW |
453 | goto ro_cleanup; |
454 | } | |
f8e2bd53 KW |
455 | |
456 | length = blk_getlength(src); | |
83fd6dd3 KW |
457 | if (length < 0) { |
458 | ret = length; | |
459 | goto ro_cleanup; | |
460 | } | |
461 | ||
f8e2bd53 | 462 | backing_length = blk_getlength(backing); |
83fd6dd3 KW |
463 | if (backing_length < 0) { |
464 | ret = backing_length; | |
465 | goto ro_cleanup; | |
466 | } | |
467 | ||
468 | /* If our top snapshot is larger than the backing file image, | |
469 | * grow the backing file image if possible. If not possible, | |
470 | * we must return an error */ | |
471 | if (length > backing_length) { | |
3a691c50 | 472 | ret = blk_truncate(backing, length, PREALLOC_MODE_OFF, &local_err); |
83fd6dd3 | 473 | if (ret < 0) { |
ed3d2ec9 | 474 | error_report_err(local_err); |
83fd6dd3 KW |
475 | goto ro_cleanup; |
476 | } | |
477 | } | |
478 | ||
f8e2bd53 KW |
479 | /* blk_try_blockalign() for src will choose an alignment that works for |
480 | * backing as well, so no need to compare the alignment manually. */ | |
d6a644bb | 481 | buf = blk_try_blockalign(src, COMMIT_BUF_SIZE); |
83fd6dd3 KW |
482 | if (buf == NULL) { |
483 | ret = -ENOMEM; | |
484 | goto ro_cleanup; | |
485 | } | |
486 | ||
d6a644bb EB |
487 | for (offset = 0; offset < length; offset += n) { |
488 | ret = bdrv_is_allocated(bs, offset, COMMIT_BUF_SIZE, &n); | |
83fd6dd3 KW |
489 | if (ret < 0) { |
490 | goto ro_cleanup; | |
491 | } | |
492 | if (ret) { | |
d6a644bb | 493 | ret = blk_pread(src, offset, buf, n); |
83fd6dd3 KW |
494 | if (ret < 0) { |
495 | goto ro_cleanup; | |
496 | } | |
497 | ||
d6a644bb | 498 | ret = blk_pwrite(backing, offset, buf, n, 0); |
83fd6dd3 KW |
499 | if (ret < 0) { |
500 | goto ro_cleanup; | |
501 | } | |
502 | } | |
503 | } | |
504 | ||
505 | if (drv->bdrv_make_empty) { | |
506 | ret = drv->bdrv_make_empty(bs); | |
507 | if (ret < 0) { | |
508 | goto ro_cleanup; | |
509 | } | |
f8e2bd53 | 510 | blk_flush(src); |
83fd6dd3 KW |
511 | } |
512 | ||
513 | /* | |
514 | * Make sure all data we wrote to the backing device is actually | |
515 | * stable on disk. | |
516 | */ | |
f8e2bd53 | 517 | blk_flush(backing); |
83fd6dd3 KW |
518 | |
519 | ret = 0; | |
520 | ro_cleanup: | |
521 | qemu_vfree(buf); | |
522 | ||
f8e2bd53 | 523 | blk_unref(backing); |
d3f06759 | 524 | if (backing_file_bs) { |
12fa4af6 | 525 | bdrv_set_backing_hd(bs, backing_file_bs, &error_abort); |
d3f06759 KW |
526 | } |
527 | bdrv_unref(commit_top_bs); | |
528 | blk_unref(src); | |
f8e2bd53 | 529 | |
83fd6dd3 KW |
530 | if (ro) { |
531 | /* ignoring error return here */ | |
532 | bdrv_reopen(bs->backing->bs, open_flags & ~BDRV_O_RDWR, NULL); | |
533 | } | |
534 | ||
535 | return ret; | |
536 | } |