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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, |
d8a98584 | 50 | int64_t offset, uint64_t bytes, |
747ff602 JC |
51 | void *buf) |
52 | { | |
53 | int ret = 0; | |
4653456a KW |
54 | QEMUIOVector qiov; |
55 | struct iovec iov = { | |
56 | .iov_base = buf, | |
d8a98584 | 57 | .iov_len = bytes, |
4653456a | 58 | }; |
747ff602 | 59 | |
d8a98584 | 60 | assert(bytes < SIZE_MAX); |
4653456a KW |
61 | qemu_iovec_init_external(&qiov, &iov, 1); |
62 | ||
d8a98584 | 63 | ret = blk_co_preadv(bs, offset, qiov.size, &qiov, 0); |
4653456a | 64 | if (ret < 0) { |
747ff602 JC |
65 | return ret; |
66 | } | |
67 | ||
d8a98584 | 68 | ret = blk_co_pwritev(base, offset, qiov.size, &qiov, 0); |
4653456a | 69 | if (ret < 0) { |
747ff602 JC |
70 | return ret; |
71 | } | |
72 | ||
73 | return 0; | |
74 | } | |
75 | ||
9e85cd5c SH |
76 | typedef struct { |
77 | int ret; | |
78 | } CommitCompleteData; | |
79 | ||
80 | static void commit_complete(BlockJob *job, void *opaque) | |
747ff602 | 81 | { |
9e85cd5c SH |
82 | CommitBlockJob *s = container_of(job, CommitBlockJob, common); |
83 | CommitCompleteData *data = opaque; | |
747ff602 | 84 | BlockDriverState *active = s->active; |
4653456a KW |
85 | BlockDriverState *top = blk_bs(s->top); |
86 | BlockDriverState *base = blk_bs(s->base); | |
8dfba279 | 87 | BlockDriverState *overlay_bs = bdrv_find_overlay(active, s->commit_top_bs); |
9e85cd5c | 88 | int ret = data->ret; |
8dfba279 KW |
89 | bool remove_commit_top_bs = false; |
90 | ||
19ebd13e KW |
91 | /* Make sure overlay_bs and top stay around until bdrv_set_backing_hd() */ |
92 | bdrv_ref(top); | |
b1e1fa0c KW |
93 | if (overlay_bs) { |
94 | bdrv_ref(overlay_bs); | |
95 | } | |
19ebd13e | 96 | |
8dfba279 KW |
97 | /* Remove base node parent that still uses BLK_PERM_WRITE/RESIZE before |
98 | * the normal backing chain can be restored. */ | |
99 | blk_unref(s->base); | |
9e85cd5c SH |
100 | |
101 | if (!block_job_is_cancelled(&s->common) && ret == 0) { | |
102 | /* success */ | |
8dfba279 KW |
103 | ret = bdrv_drop_intermediate(active, s->commit_top_bs, base, |
104 | s->backing_file_str); | |
105 | } else if (overlay_bs) { | |
106 | /* XXX Can (or should) we somehow keep 'consistent read' blocked even | |
107 | * after the failed/cancelled commit job is gone? If we already wrote | |
108 | * something to base, the intermediate images aren't valid any more. */ | |
109 | remove_commit_top_bs = true; | |
9e85cd5c SH |
110 | } |
111 | ||
112 | /* restore base open flags here if appropriate (e.g., change the base back | |
113 | * to r/o). These reopens do not need to be atomic, since we won't abort | |
114 | * even on failure here */ | |
115 | if (s->base_flags != bdrv_get_flags(base)) { | |
116 | bdrv_reopen(base, s->base_flags, NULL); | |
117 | } | |
9e85cd5c SH |
118 | if (overlay_bs && s->orig_overlay_flags != bdrv_get_flags(overlay_bs)) { |
119 | bdrv_reopen(overlay_bs, s->orig_overlay_flags, NULL); | |
120 | } | |
121 | g_free(s->backing_file_str); | |
4653456a | 122 | blk_unref(s->top); |
4f78a16f KW |
123 | |
124 | /* If there is more than one reference to the job (e.g. if called from | |
125 | * block_job_finish_sync()), block_job_completed() won't free it and | |
126 | * therefore the blockers on the intermediate nodes remain. This would | |
127 | * cause bdrv_set_backing_hd() to fail. */ | |
128 | block_job_remove_all_bdrv(job); | |
129 | ||
9e85cd5c SH |
130 | block_job_completed(&s->common, ret); |
131 | g_free(data); | |
8dfba279 KW |
132 | |
133 | /* If bdrv_drop_intermediate() didn't already do that, remove the commit | |
134 | * filter driver from the backing chain. Do this as the final step so that | |
135 | * the 'consistent read' permission can be granted. */ | |
136 | if (remove_commit_top_bs) { | |
12fa4af6 | 137 | bdrv_set_backing_hd(overlay_bs, top, &error_abort); |
8dfba279 | 138 | } |
19ebd13e KW |
139 | |
140 | bdrv_unref(overlay_bs); | |
141 | bdrv_unref(top); | |
9e85cd5c SH |
142 | } |
143 | ||
144 | static void coroutine_fn commit_run(void *opaque) | |
145 | { | |
146 | CommitBlockJob *s = opaque; | |
147 | CommitCompleteData *data; | |
317a6676 | 148 | int64_t offset; |
f14a39cc | 149 | uint64_t delay_ns = 0; |
747ff602 | 150 | int ret = 0; |
51b0a488 | 151 | int64_t n = 0; /* bytes */ |
9e85cd5c | 152 | void *buf = NULL; |
747ff602 JC |
153 | int bytes_written = 0; |
154 | int64_t base_len; | |
155 | ||
4653456a | 156 | ret = s->common.len = blk_getlength(s->top); |
747ff602 | 157 | |
747ff602 | 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) { | |
3a691c50 | 168 | ret = blk_truncate(s->base, s->common.len, PREALLOC_MODE_OFF, NULL); |
747ff602 | 169 | if (ret) { |
9e85cd5c | 170 | goto out; |
747ff602 JC |
171 | } |
172 | } | |
173 | ||
4653456a | 174 | buf = blk_blockalign(s->top, COMMIT_BUFFER_SIZE); |
747ff602 | 175 | |
51b0a488 | 176 | for (offset = 0; offset < s->common.len; offset += n) { |
747ff602 JC |
177 | bool copy; |
178 | ||
747ff602 | 179 | /* Note that even when no rate limit is applied we need to yield |
c57b6656 | 180 | * with no pending I/O here so that bdrv_drain_all() returns. |
747ff602 | 181 | */ |
7483d1e5 | 182 | block_job_sleep_ns(&s->common, QEMU_CLOCK_REALTIME, delay_ns); |
747ff602 JC |
183 | if (block_job_is_cancelled(&s->common)) { |
184 | break; | |
185 | } | |
186 | /* Copy if allocated above the base */ | |
4653456a | 187 | ret = bdrv_is_allocated_above(blk_bs(s->top), blk_bs(s->base), |
51b0a488 | 188 | offset, COMMIT_BUFFER_SIZE, &n); |
747ff602 | 189 | copy = (ret == 1); |
51b0a488 | 190 | trace_commit_one_iteration(s, offset, n, ret); |
747ff602 | 191 | if (copy) { |
51b0a488 EB |
192 | ret = commit_populate(s->top, s->base, offset, n, buf); |
193 | bytes_written += n; | |
747ff602 JC |
194 | } |
195 | if (ret < 0) { | |
1e8fb7f1 KW |
196 | BlockErrorAction action = |
197 | block_job_error_action(&s->common, false, s->on_error, -ret); | |
198 | if (action == BLOCK_ERROR_ACTION_REPORT) { | |
9e85cd5c | 199 | goto out; |
747ff602 JC |
200 | } else { |
201 | n = 0; | |
202 | continue; | |
203 | } | |
204 | } | |
205 | /* Publish progress */ | |
51b0a488 | 206 | s->common.offset += n; |
f14a39cc SS |
207 | |
208 | if (copy && s->common.speed) { | |
51b0a488 | 209 | delay_ns = ratelimit_calculate_delay(&s->limit, n); |
f14a39cc | 210 | } |
747ff602 JC |
211 | } |
212 | ||
213 | ret = 0; | |
214 | ||
9e85cd5c | 215 | out: |
747ff602 JC |
216 | qemu_vfree(buf); |
217 | ||
9e85cd5c SH |
218 | data = g_malloc(sizeof(*data)); |
219 | data->ret = ret; | |
220 | block_job_defer_to_main_loop(&s->common, commit_complete, data); | |
747ff602 JC |
221 | } |
222 | ||
223 | static void commit_set_speed(BlockJob *job, int64_t speed, Error **errp) | |
224 | { | |
225 | CommitBlockJob *s = container_of(job, CommitBlockJob, common); | |
226 | ||
227 | if (speed < 0) { | |
c6bd8c70 | 228 | error_setg(errp, QERR_INVALID_PARAMETER, "speed"); |
747ff602 JC |
229 | return; |
230 | } | |
f3e4ce4a | 231 | ratelimit_set_speed(&s->limit, speed, SLICE_TIME); |
747ff602 JC |
232 | } |
233 | ||
3fc4b10a | 234 | static const BlockJobDriver commit_job_driver = { |
747ff602 | 235 | .instance_size = sizeof(CommitBlockJob), |
79e14bf7 | 236 | .job_type = BLOCK_JOB_TYPE_COMMIT, |
747ff602 | 237 | .set_speed = commit_set_speed, |
a7815a76 | 238 | .start = commit_run, |
747ff602 JC |
239 | }; |
240 | ||
8dfba279 KW |
241 | static int coroutine_fn bdrv_commit_top_preadv(BlockDriverState *bs, |
242 | uint64_t offset, uint64_t bytes, QEMUIOVector *qiov, int flags) | |
243 | { | |
244 | return bdrv_co_preadv(bs->backing, offset, bytes, qiov, flags); | |
245 | } | |
246 | ||
dcbf37ce KW |
247 | static void bdrv_commit_top_refresh_filename(BlockDriverState *bs, QDict *opts) |
248 | { | |
249 | bdrv_refresh_filename(bs->backing->bs); | |
250 | pstrcpy(bs->exact_filename, sizeof(bs->exact_filename), | |
251 | bs->backing->bs->filename); | |
252 | } | |
91965658 | 253 | |
8dfba279 KW |
254 | static void bdrv_commit_top_close(BlockDriverState *bs) |
255 | { | |
256 | } | |
257 | ||
258 | static void bdrv_commit_top_child_perm(BlockDriverState *bs, BdrvChild *c, | |
259 | const BdrvChildRole *role, | |
e0995dc3 | 260 | BlockReopenQueue *reopen_queue, |
8dfba279 KW |
261 | uint64_t perm, uint64_t shared, |
262 | uint64_t *nperm, uint64_t *nshared) | |
263 | { | |
264 | *nperm = 0; | |
265 | *nshared = BLK_PERM_ALL; | |
266 | } | |
267 | ||
268 | /* Dummy node that provides consistent read to its users without requiring it | |
269 | * from its backing file and that allows writes on the backing file chain. */ | |
270 | static BlockDriver bdrv_commit_top = { | |
91965658 KW |
271 | .format_name = "commit_top", |
272 | .bdrv_co_preadv = bdrv_commit_top_preadv, | |
f7cc69b3 | 273 | .bdrv_co_get_block_status = bdrv_co_get_block_status_from_backing, |
dcbf37ce | 274 | .bdrv_refresh_filename = bdrv_commit_top_refresh_filename, |
91965658 KW |
275 | .bdrv_close = bdrv_commit_top_close, |
276 | .bdrv_child_perm = bdrv_commit_top_child_perm, | |
8dfba279 KW |
277 | }; |
278 | ||
fd62c609 AG |
279 | void commit_start(const char *job_id, BlockDriverState *bs, |
280 | BlockDriverState *base, BlockDriverState *top, int64_t speed, | |
8254b6d9 | 281 | BlockdevOnError on_error, const char *backing_file_str, |
0db832f4 | 282 | const char *filter_node_name, Error **errp) |
747ff602 JC |
283 | { |
284 | CommitBlockJob *s; | |
285 | BlockReopenQueue *reopen_queue = NULL; | |
286 | int orig_overlay_flags; | |
287 | int orig_base_flags; | |
3e4c5122 | 288 | BlockDriverState *iter; |
747ff602 | 289 | BlockDriverState *overlay_bs; |
8dfba279 | 290 | BlockDriverState *commit_top_bs = NULL; |
747ff602 | 291 | Error *local_err = NULL; |
d7086422 | 292 | int ret; |
747ff602 | 293 | |
18da7f94 | 294 | assert(top != bs); |
747ff602 JC |
295 | if (top == base) { |
296 | error_setg(errp, "Invalid files for merge: top and base are the same"); | |
297 | return; | |
298 | } | |
299 | ||
747ff602 JC |
300 | overlay_bs = bdrv_find_overlay(bs, top); |
301 | ||
302 | if (overlay_bs == NULL) { | |
303 | error_setg(errp, "Could not find overlay image for %s:", top->filename); | |
304 | return; | |
305 | } | |
306 | ||
c6cc12bf KW |
307 | s = block_job_create(job_id, &commit_job_driver, bs, 0, BLK_PERM_ALL, |
308 | speed, BLOCK_JOB_DEFAULT, NULL, NULL, errp); | |
834fe28d AG |
309 | if (!s) { |
310 | return; | |
311 | } | |
312 | ||
747ff602 JC |
313 | orig_base_flags = bdrv_get_flags(base); |
314 | orig_overlay_flags = bdrv_get_flags(overlay_bs); | |
315 | ||
316 | /* convert base & overlay_bs to r/w, if necessary */ | |
3db2bd55 AG |
317 | if (!(orig_base_flags & BDRV_O_RDWR)) { |
318 | reopen_queue = bdrv_reopen_queue(reopen_queue, base, NULL, | |
319 | orig_base_flags | BDRV_O_RDWR); | |
320 | } | |
0fe282bb AG |
321 | if (!(orig_overlay_flags & BDRV_O_RDWR)) { |
322 | reopen_queue = bdrv_reopen_queue(reopen_queue, overlay_bs, NULL, | |
323 | orig_overlay_flags | BDRV_O_RDWR); | |
324 | } | |
747ff602 | 325 | if (reopen_queue) { |
720150f3 | 326 | bdrv_reopen_multiple(bdrv_get_aio_context(bs), reopen_queue, &local_err); |
747ff602 JC |
327 | if (local_err != NULL) { |
328 | error_propagate(errp, local_err); | |
d7086422 | 329 | goto fail; |
747ff602 JC |
330 | } |
331 | } | |
332 | ||
8dfba279 KW |
333 | /* Insert commit_top block node above top, so we can block consistent read |
334 | * on the backing chain below it */ | |
0db832f4 KW |
335 | commit_top_bs = bdrv_new_open_driver(&bdrv_commit_top, filter_node_name, 0, |
336 | errp); | |
8dfba279 KW |
337 | if (commit_top_bs == NULL) { |
338 | goto fail; | |
339 | } | |
d3c8c674 KW |
340 | if (!filter_node_name) { |
341 | commit_top_bs->implicit = true; | |
342 | } | |
0d0676a1 | 343 | commit_top_bs->total_sectors = top->total_sectors; |
02be4aeb | 344 | bdrv_set_aio_context(commit_top_bs, bdrv_get_aio_context(top)); |
8dfba279 | 345 | |
b69f00dd FZ |
346 | bdrv_set_backing_hd(commit_top_bs, top, &local_err); |
347 | if (local_err) { | |
348 | bdrv_unref(commit_top_bs); | |
349 | commit_top_bs = NULL; | |
350 | error_propagate(errp, local_err); | |
351 | goto fail; | |
352 | } | |
353 | bdrv_set_backing_hd(overlay_bs, commit_top_bs, &local_err); | |
354 | if (local_err) { | |
355 | bdrv_unref(commit_top_bs); | |
356 | commit_top_bs = NULL; | |
357 | error_propagate(errp, local_err); | |
358 | goto fail; | |
359 | } | |
8dfba279 KW |
360 | |
361 | s->commit_top_bs = commit_top_bs; | |
362 | bdrv_unref(commit_top_bs); | |
747ff602 | 363 | |
3e4c5122 AG |
364 | /* Block all nodes between top and base, because they will |
365 | * disappear from the chain after this operation. */ | |
366 | assert(bdrv_chain_contains(top, base)); | |
8dfba279 KW |
367 | for (iter = top; iter != base; iter = backing_bs(iter)) { |
368 | /* XXX BLK_PERM_WRITE needs to be allowed so we don't block ourselves | |
369 | * at s->base (if writes are blocked for a node, they are also blocked | |
370 | * for its backing file). The other options would be a second filter | |
371 | * driver above s->base. */ | |
372 | ret = block_job_add_bdrv(&s->common, "intermediate node", iter, 0, | |
373 | BLK_PERM_WRITE_UNCHANGED | BLK_PERM_WRITE, | |
374 | errp); | |
375 | if (ret < 0) { | |
376 | goto fail; | |
377 | } | |
3e4c5122 | 378 | } |
8dfba279 KW |
379 | |
380 | ret = block_job_add_bdrv(&s->common, "base", base, 0, BLK_PERM_ALL, errp); | |
381 | if (ret < 0) { | |
382 | goto fail; | |
383 | } | |
384 | ||
3e4c5122 | 385 | /* overlay_bs must be blocked because it needs to be modified to |
8dfba279 KW |
386 | * update the backing image string. */ |
387 | ret = block_job_add_bdrv(&s->common, "overlay of top", overlay_bs, | |
388 | BLK_PERM_GRAPH_MOD, BLK_PERM_ALL, errp); | |
389 | if (ret < 0) { | |
390 | goto fail; | |
3e4c5122 AG |
391 | } |
392 | ||
8dfba279 KW |
393 | s->base = blk_new(BLK_PERM_CONSISTENT_READ |
394 | | BLK_PERM_WRITE | |
395 | | BLK_PERM_RESIZE, | |
396 | BLK_PERM_CONSISTENT_READ | |
397 | | BLK_PERM_GRAPH_MOD | |
398 | | BLK_PERM_WRITE_UNCHANGED); | |
d7086422 KW |
399 | ret = blk_insert_bs(s->base, base, errp); |
400 | if (ret < 0) { | |
401 | goto fail; | |
402 | } | |
4653456a | 403 | |
8dfba279 | 404 | /* Required permissions are already taken with block_job_add_bdrv() */ |
6d0eb64d | 405 | s->top = blk_new(0, BLK_PERM_ALL); |
b247767a | 406 | ret = blk_insert_bs(s->top, top, errp); |
d7086422 KW |
407 | if (ret < 0) { |
408 | goto fail; | |
409 | } | |
4653456a | 410 | |
747ff602 JC |
411 | s->active = bs; |
412 | ||
413 | s->base_flags = orig_base_flags; | |
414 | s->orig_overlay_flags = orig_overlay_flags; | |
415 | ||
54e26900 JC |
416 | s->backing_file_str = g_strdup(backing_file_str); |
417 | ||
747ff602 | 418 | s->on_error = on_error; |
747ff602 | 419 | |
5ccac6f1 JS |
420 | trace_commit_start(bs, base, top, s); |
421 | block_job_start(&s->common); | |
d7086422 KW |
422 | return; |
423 | ||
424 | fail: | |
425 | if (s->base) { | |
426 | blk_unref(s->base); | |
427 | } | |
428 | if (s->top) { | |
429 | blk_unref(s->top); | |
430 | } | |
8dfba279 | 431 | if (commit_top_bs) { |
12fa4af6 | 432 | bdrv_set_backing_hd(overlay_bs, top, &error_abort); |
8dfba279 | 433 | } |
05b0d8e3 | 434 | block_job_early_fail(&s->common); |
747ff602 | 435 | } |
83fd6dd3 KW |
436 | |
437 | ||
d6a644bb | 438 | #define COMMIT_BUF_SIZE (2048 * BDRV_SECTOR_SIZE) |
83fd6dd3 KW |
439 | |
440 | /* commit COW file into the raw image */ | |
441 | int bdrv_commit(BlockDriverState *bs) | |
442 | { | |
f8e2bd53 | 443 | BlockBackend *src, *backing; |
d3f06759 KW |
444 | BlockDriverState *backing_file_bs = NULL; |
445 | BlockDriverState *commit_top_bs = NULL; | |
83fd6dd3 | 446 | BlockDriver *drv = bs->drv; |
d6a644bb EB |
447 | int64_t offset, length, backing_length; |
448 | int ro, open_flags; | |
449 | int64_t n; | |
83fd6dd3 KW |
450 | int ret = 0; |
451 | uint8_t *buf = NULL; | |
d3f06759 | 452 | Error *local_err = NULL; |
83fd6dd3 KW |
453 | |
454 | if (!drv) | |
455 | return -ENOMEDIUM; | |
456 | ||
457 | if (!bs->backing) { | |
458 | return -ENOTSUP; | |
459 | } | |
460 | ||
461 | if (bdrv_op_is_blocked(bs, BLOCK_OP_TYPE_COMMIT_SOURCE, NULL) || | |
462 | bdrv_op_is_blocked(bs->backing->bs, BLOCK_OP_TYPE_COMMIT_TARGET, NULL)) { | |
463 | return -EBUSY; | |
464 | } | |
465 | ||
466 | ro = bs->backing->bs->read_only; | |
467 | open_flags = bs->backing->bs->open_flags; | |
468 | ||
469 | if (ro) { | |
470 | if (bdrv_reopen(bs->backing->bs, open_flags | BDRV_O_RDWR, NULL)) { | |
471 | return -EACCES; | |
472 | } | |
473 | } | |
474 | ||
d3f06759 KW |
475 | src = blk_new(BLK_PERM_CONSISTENT_READ, BLK_PERM_ALL); |
476 | backing = blk_new(BLK_PERM_WRITE | BLK_PERM_RESIZE, BLK_PERM_ALL); | |
d7086422 | 477 | |
d3f06759 | 478 | ret = blk_insert_bs(src, bs, &local_err); |
d7086422 | 479 | if (ret < 0) { |
d3f06759 KW |
480 | error_report_err(local_err); |
481 | goto ro_cleanup; | |
482 | } | |
483 | ||
484 | /* Insert commit_top block node above backing, so we can write to it */ | |
485 | backing_file_bs = backing_bs(bs); | |
486 | ||
487 | commit_top_bs = bdrv_new_open_driver(&bdrv_commit_top, NULL, BDRV_O_RDWR, | |
488 | &local_err); | |
489 | if (commit_top_bs == NULL) { | |
490 | error_report_err(local_err); | |
d7086422 KW |
491 | goto ro_cleanup; |
492 | } | |
02be4aeb | 493 | bdrv_set_aio_context(commit_top_bs, bdrv_get_aio_context(backing_file_bs)); |
d7086422 | 494 | |
12fa4af6 KW |
495 | bdrv_set_backing_hd(commit_top_bs, backing_file_bs, &error_abort); |
496 | bdrv_set_backing_hd(bs, commit_top_bs, &error_abort); | |
d3f06759 KW |
497 | |
498 | ret = blk_insert_bs(backing, backing_file_bs, &local_err); | |
d7086422 | 499 | if (ret < 0) { |
d3f06759 | 500 | error_report_err(local_err); |
d7086422 KW |
501 | goto ro_cleanup; |
502 | } | |
f8e2bd53 KW |
503 | |
504 | length = blk_getlength(src); | |
83fd6dd3 KW |
505 | if (length < 0) { |
506 | ret = length; | |
507 | goto ro_cleanup; | |
508 | } | |
509 | ||
f8e2bd53 | 510 | backing_length = blk_getlength(backing); |
83fd6dd3 KW |
511 | if (backing_length < 0) { |
512 | ret = backing_length; | |
513 | goto ro_cleanup; | |
514 | } | |
515 | ||
516 | /* If our top snapshot is larger than the backing file image, | |
517 | * grow the backing file image if possible. If not possible, | |
518 | * we must return an error */ | |
519 | if (length > backing_length) { | |
3a691c50 | 520 | ret = blk_truncate(backing, length, PREALLOC_MODE_OFF, &local_err); |
83fd6dd3 | 521 | if (ret < 0) { |
ed3d2ec9 | 522 | error_report_err(local_err); |
83fd6dd3 KW |
523 | goto ro_cleanup; |
524 | } | |
525 | } | |
526 | ||
f8e2bd53 KW |
527 | /* blk_try_blockalign() for src will choose an alignment that works for |
528 | * backing as well, so no need to compare the alignment manually. */ | |
d6a644bb | 529 | buf = blk_try_blockalign(src, COMMIT_BUF_SIZE); |
83fd6dd3 KW |
530 | if (buf == NULL) { |
531 | ret = -ENOMEM; | |
532 | goto ro_cleanup; | |
533 | } | |
534 | ||
d6a644bb EB |
535 | for (offset = 0; offset < length; offset += n) { |
536 | ret = bdrv_is_allocated(bs, offset, COMMIT_BUF_SIZE, &n); | |
83fd6dd3 KW |
537 | if (ret < 0) { |
538 | goto ro_cleanup; | |
539 | } | |
540 | if (ret) { | |
d6a644bb | 541 | ret = blk_pread(src, offset, buf, n); |
83fd6dd3 KW |
542 | if (ret < 0) { |
543 | goto ro_cleanup; | |
544 | } | |
545 | ||
d6a644bb | 546 | ret = blk_pwrite(backing, offset, buf, n, 0); |
83fd6dd3 KW |
547 | if (ret < 0) { |
548 | goto ro_cleanup; | |
549 | } | |
550 | } | |
551 | } | |
552 | ||
553 | if (drv->bdrv_make_empty) { | |
554 | ret = drv->bdrv_make_empty(bs); | |
555 | if (ret < 0) { | |
556 | goto ro_cleanup; | |
557 | } | |
f8e2bd53 | 558 | blk_flush(src); |
83fd6dd3 KW |
559 | } |
560 | ||
561 | /* | |
562 | * Make sure all data we wrote to the backing device is actually | |
563 | * stable on disk. | |
564 | */ | |
f8e2bd53 | 565 | blk_flush(backing); |
83fd6dd3 KW |
566 | |
567 | ret = 0; | |
568 | ro_cleanup: | |
569 | qemu_vfree(buf); | |
570 | ||
f8e2bd53 | 571 | blk_unref(backing); |
d3f06759 | 572 | if (backing_file_bs) { |
12fa4af6 | 573 | bdrv_set_backing_hd(bs, backing_file_bs, &error_abort); |
d3f06759 KW |
574 | } |
575 | bdrv_unref(commit_top_bs); | |
576 | blk_unref(src); | |
f8e2bd53 | 577 | |
83fd6dd3 KW |
578 | if (ro) { |
579 | /* ignoring error return here */ | |
580 | bdrv_reopen(bs->backing->bs, open_flags & ~BDRV_O_RDWR, NULL); | |
581 | } | |
582 | ||
583 | return ret; | |
584 | } |