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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 | ||
34 | #define SLICE_TIME 100000000ULL /* ns */ | |
35 | ||
36 | typedef struct CommitBlockJob { | |
37 | BlockJob common; | |
38 | RateLimit limit; | |
39 | BlockDriverState *active; | |
8dfba279 | 40 | BlockDriverState *commit_top_bs; |
4653456a KW |
41 | BlockBackend *top; |
42 | BlockBackend *base; | |
92aa5c6d | 43 | BlockdevOnError on_error; |
747ff602 JC |
44 | int base_flags; |
45 | int orig_overlay_flags; | |
54e26900 | 46 | char *backing_file_str; |
747ff602 JC |
47 | } CommitBlockJob; |
48 | ||
4653456a | 49 | static int coroutine_fn commit_populate(BlockBackend *bs, BlockBackend *base, |
747ff602 JC |
50 | int64_t sector_num, int nb_sectors, |
51 | void *buf) | |
52 | { | |
53 | int ret = 0; | |
4653456a KW |
54 | QEMUIOVector qiov; |
55 | struct iovec iov = { | |
56 | .iov_base = buf, | |
57 | .iov_len = nb_sectors * BDRV_SECTOR_SIZE, | |
58 | }; | |
747ff602 | 59 | |
4653456a KW |
60 | qemu_iovec_init_external(&qiov, &iov, 1); |
61 | ||
62 | ret = blk_co_preadv(bs, sector_num * BDRV_SECTOR_SIZE, | |
63 | qiov.size, &qiov, 0); | |
64 | if (ret < 0) { | |
747ff602 JC |
65 | return ret; |
66 | } | |
67 | ||
4653456a KW |
68 | ret = blk_co_pwritev(base, sector_num * BDRV_SECTOR_SIZE, |
69 | qiov.size, &qiov, 0); | |
70 | if (ret < 0) { | |
747ff602 JC |
71 | return ret; |
72 | } | |
73 | ||
74 | return 0; | |
75 | } | |
76 | ||
9e85cd5c SH |
77 | typedef struct { |
78 | int ret; | |
79 | } CommitCompleteData; | |
80 | ||
81 | static void commit_complete(BlockJob *job, void *opaque) | |
747ff602 | 82 | { |
9e85cd5c SH |
83 | CommitBlockJob *s = container_of(job, CommitBlockJob, common); |
84 | CommitCompleteData *data = opaque; | |
747ff602 | 85 | BlockDriverState *active = s->active; |
4653456a KW |
86 | BlockDriverState *top = blk_bs(s->top); |
87 | BlockDriverState *base = blk_bs(s->base); | |
8dfba279 | 88 | BlockDriverState *overlay_bs = bdrv_find_overlay(active, s->commit_top_bs); |
9e85cd5c | 89 | int ret = data->ret; |
8dfba279 KW |
90 | bool remove_commit_top_bs = false; |
91 | ||
f28b8906 KW |
92 | /* Make sure overlay_bs and top stay around until bdrv_set_backing_hd() */ |
93 | bdrv_ref(top); | |
94 | bdrv_ref(overlay_bs); | |
95 | ||
8dfba279 KW |
96 | /* Remove base node parent that still uses BLK_PERM_WRITE/RESIZE before |
97 | * the normal backing chain can be restored. */ | |
98 | blk_unref(s->base); | |
9e85cd5c SH |
99 | |
100 | if (!block_job_is_cancelled(&s->common) && ret == 0) { | |
101 | /* success */ | |
8dfba279 KW |
102 | ret = bdrv_drop_intermediate(active, s->commit_top_bs, base, |
103 | s->backing_file_str); | |
104 | } else if (overlay_bs) { | |
105 | /* XXX Can (or should) we somehow keep 'consistent read' blocked even | |
106 | * after the failed/cancelled commit job is gone? If we already wrote | |
107 | * something to base, the intermediate images aren't valid any more. */ | |
108 | remove_commit_top_bs = true; | |
9e85cd5c SH |
109 | } |
110 | ||
111 | /* restore base open flags here if appropriate (e.g., change the base back | |
112 | * to r/o). These reopens do not need to be atomic, since we won't abort | |
113 | * even on failure here */ | |
114 | if (s->base_flags != bdrv_get_flags(base)) { | |
115 | bdrv_reopen(base, s->base_flags, NULL); | |
116 | } | |
9e85cd5c SH |
117 | if (overlay_bs && s->orig_overlay_flags != bdrv_get_flags(overlay_bs)) { |
118 | bdrv_reopen(overlay_bs, s->orig_overlay_flags, NULL); | |
119 | } | |
120 | g_free(s->backing_file_str); | |
4653456a | 121 | blk_unref(s->top); |
1dd3ba38 KW |
122 | |
123 | /* If there is more than one reference to the job (e.g. if called from | |
124 | * block_job_finish_sync()), block_job_completed() won't free it and | |
125 | * therefore the blockers on the intermediate nodes remain. This would | |
126 | * cause bdrv_set_backing_hd() to fail. */ | |
127 | block_job_remove_all_bdrv(job); | |
128 | ||
9e85cd5c SH |
129 | block_job_completed(&s->common, ret); |
130 | g_free(data); | |
8dfba279 KW |
131 | |
132 | /* If bdrv_drop_intermediate() didn't already do that, remove the commit | |
133 | * filter driver from the backing chain. Do this as the final step so that | |
134 | * the 'consistent read' permission can be granted. */ | |
135 | if (remove_commit_top_bs) { | |
12fa4af6 | 136 | bdrv_set_backing_hd(overlay_bs, top, &error_abort); |
8dfba279 | 137 | } |
f28b8906 KW |
138 | |
139 | bdrv_unref(overlay_bs); | |
140 | bdrv_unref(top); | |
9e85cd5c SH |
141 | } |
142 | ||
143 | static void coroutine_fn commit_run(void *opaque) | |
144 | { | |
145 | CommitBlockJob *s = opaque; | |
146 | CommitCompleteData *data; | |
747ff602 | 147 | int64_t sector_num, end; |
f14a39cc | 148 | uint64_t delay_ns = 0; |
747ff602 JC |
149 | int ret = 0; |
150 | int n = 0; | |
9e85cd5c | 151 | void *buf = NULL; |
747ff602 JC |
152 | int bytes_written = 0; |
153 | int64_t base_len; | |
154 | ||
4653456a | 155 | ret = s->common.len = blk_getlength(s->top); |
747ff602 JC |
156 | |
157 | ||
158 | if (s->common.len < 0) { | |
9e85cd5c | 159 | goto out; |
747ff602 JC |
160 | } |
161 | ||
4653456a | 162 | ret = base_len = blk_getlength(s->base); |
747ff602 | 163 | if (base_len < 0) { |
9e85cd5c | 164 | goto out; |
747ff602 JC |
165 | } |
166 | ||
167 | if (base_len < s->common.len) { | |
5797a36a | 168 | ret = blk_truncate(s->base, s->common.len, NULL); |
747ff602 | 169 | if (ret) { |
9e85cd5c | 170 | goto out; |
747ff602 JC |
171 | } |
172 | } | |
173 | ||
747ff602 | 174 | end = s->common.len >> BDRV_SECTOR_BITS; |
4653456a | 175 | buf = blk_blockalign(s->top, COMMIT_BUFFER_SIZE); |
747ff602 JC |
176 | |
177 | for (sector_num = 0; sector_num < end; sector_num += n) { | |
747ff602 JC |
178 | bool copy; |
179 | ||
747ff602 | 180 | /* Note that even when no rate limit is applied we need to yield |
c57b6656 | 181 | * with no pending I/O here so that bdrv_drain_all() returns. |
747ff602 | 182 | */ |
7483d1e5 | 183 | block_job_sleep_ns(&s->common, QEMU_CLOCK_REALTIME, delay_ns); |
747ff602 JC |
184 | if (block_job_is_cancelled(&s->common)) { |
185 | break; | |
186 | } | |
187 | /* Copy if allocated above the base */ | |
4653456a KW |
188 | ret = bdrv_is_allocated_above(blk_bs(s->top), blk_bs(s->base), |
189 | sector_num, | |
4f578637 PB |
190 | COMMIT_BUFFER_SIZE / BDRV_SECTOR_SIZE, |
191 | &n); | |
747ff602 JC |
192 | copy = (ret == 1); |
193 | trace_commit_one_iteration(s, sector_num, n, ret); | |
194 | if (copy) { | |
4653456a | 195 | ret = commit_populate(s->top, s->base, sector_num, n, buf); |
747ff602 JC |
196 | bytes_written += n * BDRV_SECTOR_SIZE; |
197 | } | |
198 | if (ret < 0) { | |
1e8fb7f1 KW |
199 | BlockErrorAction action = |
200 | block_job_error_action(&s->common, false, s->on_error, -ret); | |
201 | if (action == BLOCK_ERROR_ACTION_REPORT) { | |
9e85cd5c | 202 | goto out; |
747ff602 JC |
203 | } else { |
204 | n = 0; | |
205 | continue; | |
206 | } | |
207 | } | |
208 | /* Publish progress */ | |
209 | s->common.offset += n * BDRV_SECTOR_SIZE; | |
f14a39cc SS |
210 | |
211 | if (copy && s->common.speed) { | |
212 | delay_ns = ratelimit_calculate_delay(&s->limit, n); | |
213 | } | |
747ff602 JC |
214 | } |
215 | ||
216 | ret = 0; | |
217 | ||
9e85cd5c | 218 | out: |
747ff602 JC |
219 | qemu_vfree(buf); |
220 | ||
9e85cd5c SH |
221 | data = g_malloc(sizeof(*data)); |
222 | data->ret = ret; | |
223 | block_job_defer_to_main_loop(&s->common, commit_complete, data); | |
747ff602 JC |
224 | } |
225 | ||
226 | static void commit_set_speed(BlockJob *job, int64_t speed, Error **errp) | |
227 | { | |
228 | CommitBlockJob *s = container_of(job, CommitBlockJob, common); | |
229 | ||
230 | if (speed < 0) { | |
c6bd8c70 | 231 | error_setg(errp, QERR_INVALID_PARAMETER, "speed"); |
747ff602 JC |
232 | return; |
233 | } | |
234 | ratelimit_set_speed(&s->limit, speed / BDRV_SECTOR_SIZE, SLICE_TIME); | |
235 | } | |
236 | ||
3fc4b10a | 237 | static const BlockJobDriver commit_job_driver = { |
747ff602 | 238 | .instance_size = sizeof(CommitBlockJob), |
79e14bf7 | 239 | .job_type = BLOCK_JOB_TYPE_COMMIT, |
747ff602 | 240 | .set_speed = commit_set_speed, |
a7815a76 | 241 | .start = commit_run, |
747ff602 JC |
242 | }; |
243 | ||
8dfba279 KW |
244 | static int coroutine_fn bdrv_commit_top_preadv(BlockDriverState *bs, |
245 | uint64_t offset, uint64_t bytes, QEMUIOVector *qiov, int flags) | |
246 | { | |
247 | return bdrv_co_preadv(bs->backing, offset, bytes, qiov, flags); | |
248 | } | |
249 | ||
91965658 KW |
250 | static int64_t coroutine_fn bdrv_commit_top_get_block_status( |
251 | BlockDriverState *bs, int64_t sector_num, int nb_sectors, int *pnum, | |
252 | BlockDriverState **file) | |
253 | { | |
254 | *pnum = nb_sectors; | |
255 | *file = bs->backing->bs; | |
256 | return BDRV_BLOCK_RAW | BDRV_BLOCK_OFFSET_VALID | BDRV_BLOCK_DATA | | |
257 | (sector_num << BDRV_SECTOR_BITS); | |
258 | } | |
259 | ||
dcbf37ce KW |
260 | static void bdrv_commit_top_refresh_filename(BlockDriverState *bs, QDict *opts) |
261 | { | |
262 | bdrv_refresh_filename(bs->backing->bs); | |
263 | pstrcpy(bs->exact_filename, sizeof(bs->exact_filename), | |
264 | bs->backing->bs->filename); | |
265 | } | |
91965658 | 266 | |
8dfba279 KW |
267 | static void bdrv_commit_top_close(BlockDriverState *bs) |
268 | { | |
269 | } | |
270 | ||
271 | static void bdrv_commit_top_child_perm(BlockDriverState *bs, BdrvChild *c, | |
272 | const BdrvChildRole *role, | |
273 | uint64_t perm, uint64_t shared, | |
274 | uint64_t *nperm, uint64_t *nshared) | |
275 | { | |
276 | *nperm = 0; | |
277 | *nshared = BLK_PERM_ALL; | |
278 | } | |
279 | ||
280 | /* Dummy node that provides consistent read to its users without requiring it | |
281 | * from its backing file and that allows writes on the backing file chain. */ | |
282 | static BlockDriver bdrv_commit_top = { | |
91965658 KW |
283 | .format_name = "commit_top", |
284 | .bdrv_co_preadv = bdrv_commit_top_preadv, | |
285 | .bdrv_co_get_block_status = bdrv_commit_top_get_block_status, | |
dcbf37ce | 286 | .bdrv_refresh_filename = bdrv_commit_top_refresh_filename, |
91965658 KW |
287 | .bdrv_close = bdrv_commit_top_close, |
288 | .bdrv_child_perm = bdrv_commit_top_child_perm, | |
8dfba279 KW |
289 | }; |
290 | ||
fd62c609 AG |
291 | void commit_start(const char *job_id, BlockDriverState *bs, |
292 | BlockDriverState *base, BlockDriverState *top, int64_t speed, | |
8254b6d9 | 293 | BlockdevOnError on_error, const char *backing_file_str, |
0db832f4 | 294 | const char *filter_node_name, Error **errp) |
747ff602 JC |
295 | { |
296 | CommitBlockJob *s; | |
297 | BlockReopenQueue *reopen_queue = NULL; | |
298 | int orig_overlay_flags; | |
299 | int orig_base_flags; | |
3e4c5122 | 300 | BlockDriverState *iter; |
747ff602 | 301 | BlockDriverState *overlay_bs; |
8dfba279 | 302 | BlockDriverState *commit_top_bs = NULL; |
747ff602 | 303 | Error *local_err = NULL; |
d7086422 | 304 | int ret; |
747ff602 | 305 | |
18da7f94 | 306 | assert(top != bs); |
747ff602 JC |
307 | if (top == base) { |
308 | error_setg(errp, "Invalid files for merge: top and base are the same"); | |
309 | return; | |
310 | } | |
311 | ||
747ff602 JC |
312 | overlay_bs = bdrv_find_overlay(bs, top); |
313 | ||
314 | if (overlay_bs == NULL) { | |
315 | error_setg(errp, "Could not find overlay image for %s:", top->filename); | |
316 | return; | |
317 | } | |
318 | ||
c6cc12bf KW |
319 | s = block_job_create(job_id, &commit_job_driver, bs, 0, BLK_PERM_ALL, |
320 | speed, BLOCK_JOB_DEFAULT, NULL, NULL, errp); | |
834fe28d AG |
321 | if (!s) { |
322 | return; | |
323 | } | |
324 | ||
747ff602 JC |
325 | orig_base_flags = bdrv_get_flags(base); |
326 | orig_overlay_flags = bdrv_get_flags(overlay_bs); | |
327 | ||
328 | /* convert base & overlay_bs to r/w, if necessary */ | |
3db2bd55 AG |
329 | if (!(orig_base_flags & BDRV_O_RDWR)) { |
330 | reopen_queue = bdrv_reopen_queue(reopen_queue, base, NULL, | |
331 | orig_base_flags | BDRV_O_RDWR); | |
332 | } | |
0fe282bb AG |
333 | if (!(orig_overlay_flags & BDRV_O_RDWR)) { |
334 | reopen_queue = bdrv_reopen_queue(reopen_queue, overlay_bs, NULL, | |
335 | orig_overlay_flags | BDRV_O_RDWR); | |
336 | } | |
747ff602 | 337 | if (reopen_queue) { |
720150f3 | 338 | bdrv_reopen_multiple(bdrv_get_aio_context(bs), reopen_queue, &local_err); |
747ff602 JC |
339 | if (local_err != NULL) { |
340 | error_propagate(errp, local_err); | |
d7086422 | 341 | goto fail; |
747ff602 JC |
342 | } |
343 | } | |
344 | ||
8dfba279 KW |
345 | /* Insert commit_top block node above top, so we can block consistent read |
346 | * on the backing chain below it */ | |
0db832f4 KW |
347 | commit_top_bs = bdrv_new_open_driver(&bdrv_commit_top, filter_node_name, 0, |
348 | errp); | |
8dfba279 KW |
349 | if (commit_top_bs == NULL) { |
350 | goto fail; | |
351 | } | |
0d0676a1 | 352 | commit_top_bs->total_sectors = top->total_sectors; |
02be4aeb | 353 | bdrv_set_aio_context(commit_top_bs, bdrv_get_aio_context(top)); |
8dfba279 | 354 | |
b69f00dd FZ |
355 | bdrv_set_backing_hd(commit_top_bs, top, &local_err); |
356 | if (local_err) { | |
357 | bdrv_unref(commit_top_bs); | |
358 | commit_top_bs = NULL; | |
359 | error_propagate(errp, local_err); | |
360 | goto fail; | |
361 | } | |
362 | bdrv_set_backing_hd(overlay_bs, commit_top_bs, &local_err); | |
363 | if (local_err) { | |
364 | bdrv_unref(commit_top_bs); | |
365 | commit_top_bs = NULL; | |
366 | error_propagate(errp, local_err); | |
367 | goto fail; | |
368 | } | |
8dfba279 KW |
369 | |
370 | s->commit_top_bs = commit_top_bs; | |
371 | bdrv_unref(commit_top_bs); | |
747ff602 | 372 | |
3e4c5122 AG |
373 | /* Block all nodes between top and base, because they will |
374 | * disappear from the chain after this operation. */ | |
375 | assert(bdrv_chain_contains(top, base)); | |
8dfba279 KW |
376 | for (iter = top; iter != base; iter = backing_bs(iter)) { |
377 | /* XXX BLK_PERM_WRITE needs to be allowed so we don't block ourselves | |
378 | * at s->base (if writes are blocked for a node, they are also blocked | |
379 | * for its backing file). The other options would be a second filter | |
380 | * driver above s->base. */ | |
381 | ret = block_job_add_bdrv(&s->common, "intermediate node", iter, 0, | |
382 | BLK_PERM_WRITE_UNCHANGED | BLK_PERM_WRITE, | |
383 | errp); | |
384 | if (ret < 0) { | |
385 | goto fail; | |
386 | } | |
3e4c5122 | 387 | } |
8dfba279 KW |
388 | |
389 | ret = block_job_add_bdrv(&s->common, "base", base, 0, BLK_PERM_ALL, errp); | |
390 | if (ret < 0) { | |
391 | goto fail; | |
392 | } | |
393 | ||
3e4c5122 | 394 | /* overlay_bs must be blocked because it needs to be modified to |
8dfba279 KW |
395 | * update the backing image string. */ |
396 | ret = block_job_add_bdrv(&s->common, "overlay of top", overlay_bs, | |
397 | BLK_PERM_GRAPH_MOD, BLK_PERM_ALL, errp); | |
398 | if (ret < 0) { | |
399 | goto fail; | |
3e4c5122 AG |
400 | } |
401 | ||
8dfba279 KW |
402 | s->base = blk_new(BLK_PERM_CONSISTENT_READ |
403 | | BLK_PERM_WRITE | |
404 | | BLK_PERM_RESIZE, | |
405 | BLK_PERM_CONSISTENT_READ | |
406 | | BLK_PERM_GRAPH_MOD | |
407 | | BLK_PERM_WRITE_UNCHANGED); | |
d7086422 KW |
408 | ret = blk_insert_bs(s->base, base, errp); |
409 | if (ret < 0) { | |
410 | goto fail; | |
411 | } | |
4653456a | 412 | |
8dfba279 | 413 | /* Required permissions are already taken with block_job_add_bdrv() */ |
6d0eb64d | 414 | s->top = blk_new(0, BLK_PERM_ALL); |
b247767a | 415 | ret = blk_insert_bs(s->top, top, errp); |
d7086422 KW |
416 | if (ret < 0) { |
417 | goto fail; | |
418 | } | |
4653456a | 419 | |
747ff602 JC |
420 | s->active = bs; |
421 | ||
422 | s->base_flags = orig_base_flags; | |
423 | s->orig_overlay_flags = orig_overlay_flags; | |
424 | ||
54e26900 JC |
425 | s->backing_file_str = g_strdup(backing_file_str); |
426 | ||
747ff602 | 427 | s->on_error = on_error; |
747ff602 | 428 | |
5ccac6f1 JS |
429 | trace_commit_start(bs, base, top, s); |
430 | block_job_start(&s->common); | |
d7086422 KW |
431 | return; |
432 | ||
433 | fail: | |
434 | if (s->base) { | |
435 | blk_unref(s->base); | |
436 | } | |
437 | if (s->top) { | |
438 | blk_unref(s->top); | |
439 | } | |
8dfba279 | 440 | if (commit_top_bs) { |
12fa4af6 | 441 | bdrv_set_backing_hd(overlay_bs, top, &error_abort); |
8dfba279 | 442 | } |
d7086422 | 443 | block_job_unref(&s->common); |
747ff602 | 444 | } |
83fd6dd3 KW |
445 | |
446 | ||
447 | #define COMMIT_BUF_SECTORS 2048 | |
448 | ||
449 | /* commit COW file into the raw image */ | |
450 | int bdrv_commit(BlockDriverState *bs) | |
451 | { | |
f8e2bd53 | 452 | BlockBackend *src, *backing; |
d3f06759 KW |
453 | BlockDriverState *backing_file_bs = NULL; |
454 | BlockDriverState *commit_top_bs = NULL; | |
83fd6dd3 KW |
455 | BlockDriver *drv = bs->drv; |
456 | int64_t sector, total_sectors, length, backing_length; | |
457 | int n, ro, open_flags; | |
458 | int ret = 0; | |
459 | uint8_t *buf = NULL; | |
d3f06759 | 460 | Error *local_err = NULL; |
83fd6dd3 KW |
461 | |
462 | if (!drv) | |
463 | return -ENOMEDIUM; | |
464 | ||
465 | if (!bs->backing) { | |
466 | return -ENOTSUP; | |
467 | } | |
468 | ||
469 | if (bdrv_op_is_blocked(bs, BLOCK_OP_TYPE_COMMIT_SOURCE, NULL) || | |
470 | bdrv_op_is_blocked(bs->backing->bs, BLOCK_OP_TYPE_COMMIT_TARGET, NULL)) { | |
471 | return -EBUSY; | |
472 | } | |
473 | ||
474 | ro = bs->backing->bs->read_only; | |
475 | open_flags = bs->backing->bs->open_flags; | |
476 | ||
477 | if (ro) { | |
478 | if (bdrv_reopen(bs->backing->bs, open_flags | BDRV_O_RDWR, NULL)) { | |
479 | return -EACCES; | |
480 | } | |
481 | } | |
482 | ||
d3f06759 KW |
483 | src = blk_new(BLK_PERM_CONSISTENT_READ, BLK_PERM_ALL); |
484 | backing = blk_new(BLK_PERM_WRITE | BLK_PERM_RESIZE, BLK_PERM_ALL); | |
d7086422 | 485 | |
d3f06759 | 486 | ret = blk_insert_bs(src, bs, &local_err); |
d7086422 | 487 | if (ret < 0) { |
d3f06759 KW |
488 | error_report_err(local_err); |
489 | goto ro_cleanup; | |
490 | } | |
491 | ||
492 | /* Insert commit_top block node above backing, so we can write to it */ | |
493 | backing_file_bs = backing_bs(bs); | |
494 | ||
495 | commit_top_bs = bdrv_new_open_driver(&bdrv_commit_top, NULL, BDRV_O_RDWR, | |
496 | &local_err); | |
497 | if (commit_top_bs == NULL) { | |
498 | error_report_err(local_err); | |
d7086422 KW |
499 | goto ro_cleanup; |
500 | } | |
02be4aeb | 501 | bdrv_set_aio_context(commit_top_bs, bdrv_get_aio_context(backing_file_bs)); |
d7086422 | 502 | |
12fa4af6 KW |
503 | bdrv_set_backing_hd(commit_top_bs, backing_file_bs, &error_abort); |
504 | bdrv_set_backing_hd(bs, commit_top_bs, &error_abort); | |
d3f06759 KW |
505 | |
506 | ret = blk_insert_bs(backing, backing_file_bs, &local_err); | |
d7086422 | 507 | if (ret < 0) { |
d3f06759 | 508 | error_report_err(local_err); |
d7086422 KW |
509 | goto ro_cleanup; |
510 | } | |
f8e2bd53 KW |
511 | |
512 | length = blk_getlength(src); | |
83fd6dd3 KW |
513 | if (length < 0) { |
514 | ret = length; | |
515 | goto ro_cleanup; | |
516 | } | |
517 | ||
f8e2bd53 | 518 | backing_length = blk_getlength(backing); |
83fd6dd3 KW |
519 | if (backing_length < 0) { |
520 | ret = backing_length; | |
521 | goto ro_cleanup; | |
522 | } | |
523 | ||
524 | /* If our top snapshot is larger than the backing file image, | |
525 | * grow the backing file image if possible. If not possible, | |
526 | * we must return an error */ | |
527 | if (length > backing_length) { | |
5797a36a | 528 | ret = blk_truncate(backing, length, &local_err); |
83fd6dd3 | 529 | if (ret < 0) { |
5797a36a | 530 | error_report_err(local_err); |
83fd6dd3 KW |
531 | goto ro_cleanup; |
532 | } | |
533 | } | |
534 | ||
535 | total_sectors = length >> BDRV_SECTOR_BITS; | |
536 | ||
f8e2bd53 KW |
537 | /* blk_try_blockalign() for src will choose an alignment that works for |
538 | * backing as well, so no need to compare the alignment manually. */ | |
539 | buf = blk_try_blockalign(src, COMMIT_BUF_SECTORS * BDRV_SECTOR_SIZE); | |
83fd6dd3 KW |
540 | if (buf == NULL) { |
541 | ret = -ENOMEM; | |
542 | goto ro_cleanup; | |
543 | } | |
544 | ||
545 | for (sector = 0; sector < total_sectors; sector += n) { | |
546 | ret = bdrv_is_allocated(bs, sector, COMMIT_BUF_SECTORS, &n); | |
547 | if (ret < 0) { | |
548 | goto ro_cleanup; | |
549 | } | |
550 | if (ret) { | |
f8e2bd53 KW |
551 | ret = blk_pread(src, sector * BDRV_SECTOR_SIZE, buf, |
552 | n * BDRV_SECTOR_SIZE); | |
83fd6dd3 KW |
553 | if (ret < 0) { |
554 | goto ro_cleanup; | |
555 | } | |
556 | ||
f8e2bd53 KW |
557 | ret = blk_pwrite(backing, sector * BDRV_SECTOR_SIZE, buf, |
558 | n * BDRV_SECTOR_SIZE, 0); | |
83fd6dd3 KW |
559 | if (ret < 0) { |
560 | goto ro_cleanup; | |
561 | } | |
562 | } | |
563 | } | |
564 | ||
565 | if (drv->bdrv_make_empty) { | |
566 | ret = drv->bdrv_make_empty(bs); | |
567 | if (ret < 0) { | |
568 | goto ro_cleanup; | |
569 | } | |
f8e2bd53 | 570 | blk_flush(src); |
83fd6dd3 KW |
571 | } |
572 | ||
573 | /* | |
574 | * Make sure all data we wrote to the backing device is actually | |
575 | * stable on disk. | |
576 | */ | |
f8e2bd53 | 577 | blk_flush(backing); |
83fd6dd3 KW |
578 | |
579 | ret = 0; | |
580 | ro_cleanup: | |
581 | qemu_vfree(buf); | |
582 | ||
f8e2bd53 | 583 | blk_unref(backing); |
d3f06759 | 584 | if (backing_file_bs) { |
12fa4af6 | 585 | bdrv_set_backing_hd(bs, backing_file_bs, &error_abort); |
d3f06759 KW |
586 | } |
587 | bdrv_unref(commit_top_bs); | |
588 | blk_unref(src); | |
f8e2bd53 | 589 | |
83fd6dd3 KW |
590 | if (ro) { |
591 | /* ignoring error return here */ | |
592 | bdrv_reopen(bs->backing->bs, open_flags & ~BDRV_O_RDWR, NULL); | |
593 | } | |
594 | ||
595 | return ret; | |
596 | } |