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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); | |
2e40aad2 KW |
94 | if (overlay_bs) { |
95 | bdrv_ref(overlay_bs); | |
96 | } | |
f28b8906 | 97 | |
8dfba279 KW |
98 | /* Remove base node parent that still uses BLK_PERM_WRITE/RESIZE before |
99 | * the normal backing chain can be restored. */ | |
100 | blk_unref(s->base); | |
9e85cd5c SH |
101 | |
102 | if (!block_job_is_cancelled(&s->common) && ret == 0) { | |
103 | /* success */ | |
8dfba279 KW |
104 | ret = bdrv_drop_intermediate(active, s->commit_top_bs, base, |
105 | s->backing_file_str); | |
106 | } else if (overlay_bs) { | |
107 | /* XXX Can (or should) we somehow keep 'consistent read' blocked even | |
108 | * after the failed/cancelled commit job is gone? If we already wrote | |
109 | * something to base, the intermediate images aren't valid any more. */ | |
110 | remove_commit_top_bs = true; | |
9e85cd5c SH |
111 | } |
112 | ||
113 | /* restore base open flags here if appropriate (e.g., change the base back | |
114 | * to r/o). These reopens do not need to be atomic, since we won't abort | |
115 | * even on failure here */ | |
116 | if (s->base_flags != bdrv_get_flags(base)) { | |
117 | bdrv_reopen(base, s->base_flags, NULL); | |
118 | } | |
9e85cd5c SH |
119 | if (overlay_bs && s->orig_overlay_flags != bdrv_get_flags(overlay_bs)) { |
120 | bdrv_reopen(overlay_bs, s->orig_overlay_flags, NULL); | |
121 | } | |
122 | g_free(s->backing_file_str); | |
4653456a | 123 | blk_unref(s->top); |
1dd3ba38 KW |
124 | |
125 | /* If there is more than one reference to the job (e.g. if called from | |
126 | * block_job_finish_sync()), block_job_completed() won't free it and | |
127 | * therefore the blockers on the intermediate nodes remain. This would | |
128 | * cause bdrv_set_backing_hd() to fail. */ | |
129 | block_job_remove_all_bdrv(job); | |
130 | ||
9e85cd5c SH |
131 | block_job_completed(&s->common, ret); |
132 | g_free(data); | |
8dfba279 KW |
133 | |
134 | /* If bdrv_drop_intermediate() didn't already do that, remove the commit | |
135 | * filter driver from the backing chain. Do this as the final step so that | |
136 | * the 'consistent read' permission can be granted. */ | |
137 | if (remove_commit_top_bs) { | |
12fa4af6 | 138 | bdrv_set_backing_hd(overlay_bs, top, &error_abort); |
8dfba279 | 139 | } |
f28b8906 KW |
140 | |
141 | bdrv_unref(overlay_bs); | |
142 | bdrv_unref(top); | |
9e85cd5c SH |
143 | } |
144 | ||
145 | static void coroutine_fn commit_run(void *opaque) | |
146 | { | |
147 | CommitBlockJob *s = opaque; | |
148 | CommitCompleteData *data; | |
747ff602 | 149 | int64_t sector_num, end; |
f14a39cc | 150 | uint64_t delay_ns = 0; |
747ff602 JC |
151 | int ret = 0; |
152 | int n = 0; | |
9e85cd5c | 153 | void *buf = NULL; |
747ff602 JC |
154 | int bytes_written = 0; |
155 | int64_t base_len; | |
156 | ||
4653456a | 157 | ret = s->common.len = blk_getlength(s->top); |
747ff602 JC |
158 | |
159 | ||
160 | if (s->common.len < 0) { | |
9e85cd5c | 161 | goto out; |
747ff602 JC |
162 | } |
163 | ||
4653456a | 164 | ret = base_len = blk_getlength(s->base); |
747ff602 | 165 | if (base_len < 0) { |
9e85cd5c | 166 | goto out; |
747ff602 JC |
167 | } |
168 | ||
169 | if (base_len < s->common.len) { | |
5797a36a | 170 | ret = blk_truncate(s->base, s->common.len, NULL); |
747ff602 | 171 | if (ret) { |
9e85cd5c | 172 | goto out; |
747ff602 JC |
173 | } |
174 | } | |
175 | ||
747ff602 | 176 | end = s->common.len >> BDRV_SECTOR_BITS; |
4653456a | 177 | buf = blk_blockalign(s->top, COMMIT_BUFFER_SIZE); |
747ff602 JC |
178 | |
179 | for (sector_num = 0; sector_num < end; sector_num += n) { | |
747ff602 JC |
180 | bool copy; |
181 | ||
747ff602 | 182 | /* Note that even when no rate limit is applied we need to yield |
c57b6656 | 183 | * with no pending I/O here so that bdrv_drain_all() returns. |
747ff602 | 184 | */ |
7483d1e5 | 185 | block_job_sleep_ns(&s->common, QEMU_CLOCK_REALTIME, delay_ns); |
747ff602 JC |
186 | if (block_job_is_cancelled(&s->common)) { |
187 | break; | |
188 | } | |
189 | /* Copy if allocated above the base */ | |
4653456a KW |
190 | ret = bdrv_is_allocated_above(blk_bs(s->top), blk_bs(s->base), |
191 | sector_num, | |
4f578637 PB |
192 | COMMIT_BUFFER_SIZE / BDRV_SECTOR_SIZE, |
193 | &n); | |
747ff602 JC |
194 | copy = (ret == 1); |
195 | trace_commit_one_iteration(s, sector_num, n, ret); | |
196 | if (copy) { | |
4653456a | 197 | ret = commit_populate(s->top, s->base, sector_num, n, buf); |
747ff602 JC |
198 | bytes_written += n * BDRV_SECTOR_SIZE; |
199 | } | |
200 | if (ret < 0) { | |
1e8fb7f1 KW |
201 | BlockErrorAction action = |
202 | block_job_error_action(&s->common, false, s->on_error, -ret); | |
203 | if (action == BLOCK_ERROR_ACTION_REPORT) { | |
9e85cd5c | 204 | goto out; |
747ff602 JC |
205 | } else { |
206 | n = 0; | |
207 | continue; | |
208 | } | |
209 | } | |
210 | /* Publish progress */ | |
211 | s->common.offset += n * BDRV_SECTOR_SIZE; | |
f14a39cc SS |
212 | |
213 | if (copy && s->common.speed) { | |
214 | delay_ns = ratelimit_calculate_delay(&s->limit, n); | |
215 | } | |
747ff602 JC |
216 | } |
217 | ||
218 | ret = 0; | |
219 | ||
9e85cd5c | 220 | out: |
747ff602 JC |
221 | qemu_vfree(buf); |
222 | ||
9e85cd5c SH |
223 | data = g_malloc(sizeof(*data)); |
224 | data->ret = ret; | |
225 | block_job_defer_to_main_loop(&s->common, commit_complete, data); | |
747ff602 JC |
226 | } |
227 | ||
228 | static void commit_set_speed(BlockJob *job, int64_t speed, Error **errp) | |
229 | { | |
230 | CommitBlockJob *s = container_of(job, CommitBlockJob, common); | |
231 | ||
232 | if (speed < 0) { | |
c6bd8c70 | 233 | error_setg(errp, QERR_INVALID_PARAMETER, "speed"); |
747ff602 JC |
234 | return; |
235 | } | |
236 | ratelimit_set_speed(&s->limit, speed / BDRV_SECTOR_SIZE, SLICE_TIME); | |
237 | } | |
238 | ||
3fc4b10a | 239 | static const BlockJobDriver commit_job_driver = { |
747ff602 | 240 | .instance_size = sizeof(CommitBlockJob), |
79e14bf7 | 241 | .job_type = BLOCK_JOB_TYPE_COMMIT, |
747ff602 | 242 | .set_speed = commit_set_speed, |
a7815a76 | 243 | .start = commit_run, |
747ff602 JC |
244 | }; |
245 | ||
8dfba279 KW |
246 | static int coroutine_fn bdrv_commit_top_preadv(BlockDriverState *bs, |
247 | uint64_t offset, uint64_t bytes, QEMUIOVector *qiov, int flags) | |
248 | { | |
249 | return bdrv_co_preadv(bs->backing, offset, bytes, qiov, flags); | |
250 | } | |
251 | ||
91965658 KW |
252 | static int64_t coroutine_fn bdrv_commit_top_get_block_status( |
253 | BlockDriverState *bs, int64_t sector_num, int nb_sectors, int *pnum, | |
254 | BlockDriverState **file) | |
255 | { | |
256 | *pnum = nb_sectors; | |
257 | *file = bs->backing->bs; | |
258 | return BDRV_BLOCK_RAW | BDRV_BLOCK_OFFSET_VALID | BDRV_BLOCK_DATA | | |
259 | (sector_num << BDRV_SECTOR_BITS); | |
260 | } | |
261 | ||
dcbf37ce KW |
262 | static void bdrv_commit_top_refresh_filename(BlockDriverState *bs, QDict *opts) |
263 | { | |
264 | bdrv_refresh_filename(bs->backing->bs); | |
265 | pstrcpy(bs->exact_filename, sizeof(bs->exact_filename), | |
266 | bs->backing->bs->filename); | |
267 | } | |
91965658 | 268 | |
8dfba279 KW |
269 | static void bdrv_commit_top_close(BlockDriverState *bs) |
270 | { | |
271 | } | |
272 | ||
273 | static void bdrv_commit_top_child_perm(BlockDriverState *bs, BdrvChild *c, | |
274 | const BdrvChildRole *role, | |
275 | uint64_t perm, uint64_t shared, | |
276 | uint64_t *nperm, uint64_t *nshared) | |
277 | { | |
278 | *nperm = 0; | |
279 | *nshared = BLK_PERM_ALL; | |
280 | } | |
281 | ||
282 | /* Dummy node that provides consistent read to its users without requiring it | |
283 | * from its backing file and that allows writes on the backing file chain. */ | |
284 | static BlockDriver bdrv_commit_top = { | |
91965658 KW |
285 | .format_name = "commit_top", |
286 | .bdrv_co_preadv = bdrv_commit_top_preadv, | |
287 | .bdrv_co_get_block_status = bdrv_commit_top_get_block_status, | |
dcbf37ce | 288 | .bdrv_refresh_filename = bdrv_commit_top_refresh_filename, |
91965658 KW |
289 | .bdrv_close = bdrv_commit_top_close, |
290 | .bdrv_child_perm = bdrv_commit_top_child_perm, | |
8dfba279 KW |
291 | }; |
292 | ||
fd62c609 AG |
293 | void commit_start(const char *job_id, BlockDriverState *bs, |
294 | BlockDriverState *base, BlockDriverState *top, int64_t speed, | |
8254b6d9 | 295 | BlockdevOnError on_error, const char *backing_file_str, |
0db832f4 | 296 | const char *filter_node_name, Error **errp) |
747ff602 JC |
297 | { |
298 | CommitBlockJob *s; | |
299 | BlockReopenQueue *reopen_queue = NULL; | |
300 | int orig_overlay_flags; | |
301 | int orig_base_flags; | |
3e4c5122 | 302 | BlockDriverState *iter; |
747ff602 | 303 | BlockDriverState *overlay_bs; |
8dfba279 | 304 | BlockDriverState *commit_top_bs = NULL; |
747ff602 | 305 | Error *local_err = NULL; |
d7086422 | 306 | int ret; |
747ff602 | 307 | |
18da7f94 | 308 | assert(top != bs); |
747ff602 JC |
309 | if (top == base) { |
310 | error_setg(errp, "Invalid files for merge: top and base are the same"); | |
311 | return; | |
312 | } | |
313 | ||
747ff602 JC |
314 | overlay_bs = bdrv_find_overlay(bs, top); |
315 | ||
316 | if (overlay_bs == NULL) { | |
317 | error_setg(errp, "Could not find overlay image for %s:", top->filename); | |
318 | return; | |
319 | } | |
320 | ||
c6cc12bf KW |
321 | s = block_job_create(job_id, &commit_job_driver, bs, 0, BLK_PERM_ALL, |
322 | speed, BLOCK_JOB_DEFAULT, NULL, NULL, errp); | |
834fe28d AG |
323 | if (!s) { |
324 | return; | |
325 | } | |
326 | ||
747ff602 JC |
327 | orig_base_flags = bdrv_get_flags(base); |
328 | orig_overlay_flags = bdrv_get_flags(overlay_bs); | |
329 | ||
330 | /* convert base & overlay_bs to r/w, if necessary */ | |
3db2bd55 AG |
331 | if (!(orig_base_flags & BDRV_O_RDWR)) { |
332 | reopen_queue = bdrv_reopen_queue(reopen_queue, base, NULL, | |
333 | orig_base_flags | BDRV_O_RDWR); | |
334 | } | |
0fe282bb AG |
335 | if (!(orig_overlay_flags & BDRV_O_RDWR)) { |
336 | reopen_queue = bdrv_reopen_queue(reopen_queue, overlay_bs, NULL, | |
337 | orig_overlay_flags | BDRV_O_RDWR); | |
338 | } | |
747ff602 | 339 | if (reopen_queue) { |
720150f3 | 340 | bdrv_reopen_multiple(bdrv_get_aio_context(bs), reopen_queue, &local_err); |
747ff602 JC |
341 | if (local_err != NULL) { |
342 | error_propagate(errp, local_err); | |
d7086422 | 343 | goto fail; |
747ff602 JC |
344 | } |
345 | } | |
346 | ||
8dfba279 KW |
347 | /* Insert commit_top block node above top, so we can block consistent read |
348 | * on the backing chain below it */ | |
0db832f4 KW |
349 | commit_top_bs = bdrv_new_open_driver(&bdrv_commit_top, filter_node_name, 0, |
350 | errp); | |
8dfba279 KW |
351 | if (commit_top_bs == NULL) { |
352 | goto fail; | |
353 | } | |
0d0676a1 | 354 | commit_top_bs->total_sectors = top->total_sectors; |
02be4aeb | 355 | bdrv_set_aio_context(commit_top_bs, bdrv_get_aio_context(top)); |
8dfba279 | 356 | |
b69f00dd FZ |
357 | bdrv_set_backing_hd(commit_top_bs, top, &local_err); |
358 | if (local_err) { | |
359 | bdrv_unref(commit_top_bs); | |
360 | commit_top_bs = NULL; | |
361 | error_propagate(errp, local_err); | |
362 | goto fail; | |
363 | } | |
364 | bdrv_set_backing_hd(overlay_bs, commit_top_bs, &local_err); | |
365 | if (local_err) { | |
366 | bdrv_unref(commit_top_bs); | |
367 | commit_top_bs = NULL; | |
368 | error_propagate(errp, local_err); | |
369 | goto fail; | |
370 | } | |
8dfba279 KW |
371 | |
372 | s->commit_top_bs = commit_top_bs; | |
373 | bdrv_unref(commit_top_bs); | |
747ff602 | 374 | |
3e4c5122 AG |
375 | /* Block all nodes between top and base, because they will |
376 | * disappear from the chain after this operation. */ | |
377 | assert(bdrv_chain_contains(top, base)); | |
8dfba279 KW |
378 | for (iter = top; iter != base; iter = backing_bs(iter)) { |
379 | /* XXX BLK_PERM_WRITE needs to be allowed so we don't block ourselves | |
380 | * at s->base (if writes are blocked for a node, they are also blocked | |
381 | * for its backing file). The other options would be a second filter | |
382 | * driver above s->base. */ | |
383 | ret = block_job_add_bdrv(&s->common, "intermediate node", iter, 0, | |
384 | BLK_PERM_WRITE_UNCHANGED | BLK_PERM_WRITE, | |
385 | errp); | |
386 | if (ret < 0) { | |
387 | goto fail; | |
388 | } | |
3e4c5122 | 389 | } |
8dfba279 KW |
390 | |
391 | ret = block_job_add_bdrv(&s->common, "base", base, 0, BLK_PERM_ALL, errp); | |
392 | if (ret < 0) { | |
393 | goto fail; | |
394 | } | |
395 | ||
3e4c5122 | 396 | /* overlay_bs must be blocked because it needs to be modified to |
8dfba279 KW |
397 | * update the backing image string. */ |
398 | ret = block_job_add_bdrv(&s->common, "overlay of top", overlay_bs, | |
399 | BLK_PERM_GRAPH_MOD, BLK_PERM_ALL, errp); | |
400 | if (ret < 0) { | |
401 | goto fail; | |
3e4c5122 AG |
402 | } |
403 | ||
8dfba279 KW |
404 | s->base = blk_new(BLK_PERM_CONSISTENT_READ |
405 | | BLK_PERM_WRITE | |
406 | | BLK_PERM_RESIZE, | |
407 | BLK_PERM_CONSISTENT_READ | |
408 | | BLK_PERM_GRAPH_MOD | |
409 | | BLK_PERM_WRITE_UNCHANGED); | |
d7086422 KW |
410 | ret = blk_insert_bs(s->base, base, errp); |
411 | if (ret < 0) { | |
412 | goto fail; | |
413 | } | |
4653456a | 414 | |
8dfba279 | 415 | /* Required permissions are already taken with block_job_add_bdrv() */ |
6d0eb64d | 416 | s->top = blk_new(0, BLK_PERM_ALL); |
b247767a | 417 | ret = blk_insert_bs(s->top, top, errp); |
d7086422 KW |
418 | if (ret < 0) { |
419 | goto fail; | |
420 | } | |
4653456a | 421 | |
747ff602 JC |
422 | s->active = bs; |
423 | ||
424 | s->base_flags = orig_base_flags; | |
425 | s->orig_overlay_flags = orig_overlay_flags; | |
426 | ||
54e26900 JC |
427 | s->backing_file_str = g_strdup(backing_file_str); |
428 | ||
747ff602 | 429 | s->on_error = on_error; |
747ff602 | 430 | |
5ccac6f1 JS |
431 | trace_commit_start(bs, base, top, s); |
432 | block_job_start(&s->common); | |
d7086422 KW |
433 | return; |
434 | ||
435 | fail: | |
436 | if (s->base) { | |
437 | blk_unref(s->base); | |
438 | } | |
439 | if (s->top) { | |
440 | blk_unref(s->top); | |
441 | } | |
8dfba279 | 442 | if (commit_top_bs) { |
12fa4af6 | 443 | bdrv_set_backing_hd(overlay_bs, top, &error_abort); |
8dfba279 | 444 | } |
d7086422 | 445 | block_job_unref(&s->common); |
747ff602 | 446 | } |
83fd6dd3 KW |
447 | |
448 | ||
449 | #define COMMIT_BUF_SECTORS 2048 | |
450 | ||
451 | /* commit COW file into the raw image */ | |
452 | int bdrv_commit(BlockDriverState *bs) | |
453 | { | |
f8e2bd53 | 454 | BlockBackend *src, *backing; |
d3f06759 KW |
455 | BlockDriverState *backing_file_bs = NULL; |
456 | BlockDriverState *commit_top_bs = NULL; | |
83fd6dd3 KW |
457 | BlockDriver *drv = bs->drv; |
458 | int64_t sector, total_sectors, length, backing_length; | |
459 | int n, ro, open_flags; | |
460 | int ret = 0; | |
461 | uint8_t *buf = NULL; | |
d3f06759 | 462 | Error *local_err = NULL; |
83fd6dd3 KW |
463 | |
464 | if (!drv) | |
465 | return -ENOMEDIUM; | |
466 | ||
467 | if (!bs->backing) { | |
468 | return -ENOTSUP; | |
469 | } | |
470 | ||
471 | if (bdrv_op_is_blocked(bs, BLOCK_OP_TYPE_COMMIT_SOURCE, NULL) || | |
472 | bdrv_op_is_blocked(bs->backing->bs, BLOCK_OP_TYPE_COMMIT_TARGET, NULL)) { | |
473 | return -EBUSY; | |
474 | } | |
475 | ||
476 | ro = bs->backing->bs->read_only; | |
477 | open_flags = bs->backing->bs->open_flags; | |
478 | ||
479 | if (ro) { | |
480 | if (bdrv_reopen(bs->backing->bs, open_flags | BDRV_O_RDWR, NULL)) { | |
481 | return -EACCES; | |
482 | } | |
483 | } | |
484 | ||
d3f06759 KW |
485 | src = blk_new(BLK_PERM_CONSISTENT_READ, BLK_PERM_ALL); |
486 | backing = blk_new(BLK_PERM_WRITE | BLK_PERM_RESIZE, BLK_PERM_ALL); | |
d7086422 | 487 | |
d3f06759 | 488 | ret = blk_insert_bs(src, bs, &local_err); |
d7086422 | 489 | if (ret < 0) { |
d3f06759 KW |
490 | error_report_err(local_err); |
491 | goto ro_cleanup; | |
492 | } | |
493 | ||
494 | /* Insert commit_top block node above backing, so we can write to it */ | |
495 | backing_file_bs = backing_bs(bs); | |
496 | ||
497 | commit_top_bs = bdrv_new_open_driver(&bdrv_commit_top, NULL, BDRV_O_RDWR, | |
498 | &local_err); | |
499 | if (commit_top_bs == NULL) { | |
500 | error_report_err(local_err); | |
d7086422 KW |
501 | goto ro_cleanup; |
502 | } | |
02be4aeb | 503 | bdrv_set_aio_context(commit_top_bs, bdrv_get_aio_context(backing_file_bs)); |
d7086422 | 504 | |
12fa4af6 KW |
505 | bdrv_set_backing_hd(commit_top_bs, backing_file_bs, &error_abort); |
506 | bdrv_set_backing_hd(bs, commit_top_bs, &error_abort); | |
d3f06759 KW |
507 | |
508 | ret = blk_insert_bs(backing, backing_file_bs, &local_err); | |
d7086422 | 509 | if (ret < 0) { |
d3f06759 | 510 | error_report_err(local_err); |
d7086422 KW |
511 | goto ro_cleanup; |
512 | } | |
f8e2bd53 KW |
513 | |
514 | length = blk_getlength(src); | |
83fd6dd3 KW |
515 | if (length < 0) { |
516 | ret = length; | |
517 | goto ro_cleanup; | |
518 | } | |
519 | ||
f8e2bd53 | 520 | backing_length = blk_getlength(backing); |
83fd6dd3 KW |
521 | if (backing_length < 0) { |
522 | ret = backing_length; | |
523 | goto ro_cleanup; | |
524 | } | |
525 | ||
526 | /* If our top snapshot is larger than the backing file image, | |
527 | * grow the backing file image if possible. If not possible, | |
528 | * we must return an error */ | |
529 | if (length > backing_length) { | |
5797a36a | 530 | ret = blk_truncate(backing, length, &local_err); |
83fd6dd3 | 531 | if (ret < 0) { |
5797a36a | 532 | error_report_err(local_err); |
83fd6dd3 KW |
533 | goto ro_cleanup; |
534 | } | |
535 | } | |
536 | ||
537 | total_sectors = length >> BDRV_SECTOR_BITS; | |
538 | ||
f8e2bd53 KW |
539 | /* blk_try_blockalign() for src will choose an alignment that works for |
540 | * backing as well, so no need to compare the alignment manually. */ | |
541 | buf = blk_try_blockalign(src, COMMIT_BUF_SECTORS * BDRV_SECTOR_SIZE); | |
83fd6dd3 KW |
542 | if (buf == NULL) { |
543 | ret = -ENOMEM; | |
544 | goto ro_cleanup; | |
545 | } | |
546 | ||
547 | for (sector = 0; sector < total_sectors; sector += n) { | |
548 | ret = bdrv_is_allocated(bs, sector, COMMIT_BUF_SECTORS, &n); | |
549 | if (ret < 0) { | |
550 | goto ro_cleanup; | |
551 | } | |
552 | if (ret) { | |
f8e2bd53 KW |
553 | ret = blk_pread(src, sector * BDRV_SECTOR_SIZE, buf, |
554 | n * BDRV_SECTOR_SIZE); | |
83fd6dd3 KW |
555 | if (ret < 0) { |
556 | goto ro_cleanup; | |
557 | } | |
558 | ||
f8e2bd53 KW |
559 | ret = blk_pwrite(backing, sector * BDRV_SECTOR_SIZE, buf, |
560 | n * BDRV_SECTOR_SIZE, 0); | |
83fd6dd3 KW |
561 | if (ret < 0) { |
562 | goto ro_cleanup; | |
563 | } | |
564 | } | |
565 | } | |
566 | ||
567 | if (drv->bdrv_make_empty) { | |
568 | ret = drv->bdrv_make_empty(bs); | |
569 | if (ret < 0) { | |
570 | goto ro_cleanup; | |
571 | } | |
f8e2bd53 | 572 | blk_flush(src); |
83fd6dd3 KW |
573 | } |
574 | ||
575 | /* | |
576 | * Make sure all data we wrote to the backing device is actually | |
577 | * stable on disk. | |
578 | */ | |
f8e2bd53 | 579 | blk_flush(backing); |
83fd6dd3 KW |
580 | |
581 | ret = 0; | |
582 | ro_cleanup: | |
583 | qemu_vfree(buf); | |
584 | ||
f8e2bd53 | 585 | blk_unref(backing); |
d3f06759 | 586 | if (backing_file_bs) { |
12fa4af6 | 587 | bdrv_set_backing_hd(bs, backing_file_bs, &error_abort); |
d3f06759 KW |
588 | } |
589 | bdrv_unref(commit_top_bs); | |
590 | blk_unref(src); | |
f8e2bd53 | 591 | |
83fd6dd3 KW |
592 | if (ro) { |
593 | /* ignoring error return here */ | |
594 | bdrv_reopen(bs->backing->bs, open_flags & ~BDRV_O_RDWR, NULL); | |
595 | } | |
596 | ||
597 | return ret; | |
598 | } |