Merge tag 'pull-ppc-20220706' of https://gitlab.com/danielhb/qemu into staging
[qemu.git] / block / io.c
1 /*
2 * Block layer I/O functions
3 *
4 * Copyright (c) 2003 Fabrice Bellard
5 *
6 * Permission is hereby granted, free of charge, to any person obtaining a copy
7 * of this software and associated documentation files (the "Software"), to deal
8 * in the Software without restriction, including without limitation the rights
9 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
10 * copies of the Software, and to permit persons to whom the Software is
11 * furnished to do so, subject to the following conditions:
12 *
13 * The above copyright notice and this permission notice shall be included in
14 * all copies or substantial portions of the Software.
15 *
16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
17 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
18 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
19 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
20 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
21 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
22 * THE SOFTWARE.
23 */
24
25 #include "qemu/osdep.h"
26 #include "trace.h"
27 #include "sysemu/block-backend.h"
28 #include "block/blockjob.h"
29 #include "block/block_int.h"
30 #include "qemu/cutils.h"
31 #include "qapi/error.h"
32 #include "qemu/error-report.h"
33
34 #define NOT_DONE 0x7fffffff /* used while emulated sync operation in progress */
35
36 static BlockAIOCB *bdrv_co_aio_prw_vector(BdrvChild *child,
37 int64_t offset,
38 QEMUIOVector *qiov,
39 BdrvRequestFlags flags,
40 BlockCompletionFunc *cb,
41 void *opaque,
42 bool is_write);
43 static void coroutine_fn bdrv_co_do_rw(void *opaque);
44 static int coroutine_fn bdrv_co_do_pwrite_zeroes(BlockDriverState *bs,
45 int64_t offset, int count, BdrvRequestFlags flags);
46
47 static void bdrv_parent_drained_begin(BlockDriverState *bs)
48 {
49 BdrvChild *c;
50
51 QLIST_FOREACH(c, &bs->parents, next_parent) {
52 if (c->role->drained_begin) {
53 c->role->drained_begin(c);
54 }
55 }
56 }
57
58 static void bdrv_parent_drained_end(BlockDriverState *bs)
59 {
60 BdrvChild *c;
61
62 QLIST_FOREACH(c, &bs->parents, next_parent) {
63 if (c->role->drained_end) {
64 c->role->drained_end(c);
65 }
66 }
67 }
68
69 static void bdrv_merge_limits(BlockLimits *dst, const BlockLimits *src)
70 {
71 dst->opt_transfer = MAX(dst->opt_transfer, src->opt_transfer);
72 dst->max_transfer = MIN_NON_ZERO(dst->max_transfer, src->max_transfer);
73 dst->opt_mem_alignment = MAX(dst->opt_mem_alignment,
74 src->opt_mem_alignment);
75 dst->min_mem_alignment = MAX(dst->min_mem_alignment,
76 src->min_mem_alignment);
77 dst->max_iov = MIN_NON_ZERO(dst->max_iov, src->max_iov);
78 }
79
80 void bdrv_refresh_limits(BlockDriverState *bs, Error **errp)
81 {
82 BlockDriver *drv = bs->drv;
83 Error *local_err = NULL;
84
85 memset(&bs->bl, 0, sizeof(bs->bl));
86
87 if (!drv) {
88 return;
89 }
90
91 /* Default alignment based on whether driver has byte interface */
92 bs->bl.request_alignment = drv->bdrv_co_preadv ? 1 : 512;
93
94 /* Take some limits from the children as a default */
95 if (bs->file) {
96 bdrv_refresh_limits(bs->file->bs, &local_err);
97 if (local_err) {
98 error_propagate(errp, local_err);
99 return;
100 }
101 bdrv_merge_limits(&bs->bl, &bs->file->bs->bl);
102 } else {
103 bs->bl.min_mem_alignment = 512;
104 bs->bl.opt_mem_alignment = getpagesize();
105
106 /* Safe default since most protocols use readv()/writev()/etc */
107 bs->bl.max_iov = IOV_MAX;
108 }
109
110 if (bs->backing) {
111 bdrv_refresh_limits(bs->backing->bs, &local_err);
112 if (local_err) {
113 error_propagate(errp, local_err);
114 return;
115 }
116 bdrv_merge_limits(&bs->bl, &bs->backing->bs->bl);
117 }
118
119 /* Then let the driver override it */
120 if (drv->bdrv_refresh_limits) {
121 drv->bdrv_refresh_limits(bs, errp);
122 }
123 }
124
125 /**
126 * The copy-on-read flag is actually a reference count so multiple users may
127 * use the feature without worrying about clobbering its previous state.
128 * Copy-on-read stays enabled until all users have called to disable it.
129 */
130 void bdrv_enable_copy_on_read(BlockDriverState *bs)
131 {
132 bs->copy_on_read++;
133 }
134
135 void bdrv_disable_copy_on_read(BlockDriverState *bs)
136 {
137 assert(bs->copy_on_read > 0);
138 bs->copy_on_read--;
139 }
140
141 /* Check if any requests are in-flight (including throttled requests) */
142 bool bdrv_requests_pending(BlockDriverState *bs)
143 {
144 BdrvChild *child;
145
146 if (atomic_read(&bs->in_flight)) {
147 return true;
148 }
149
150 QLIST_FOREACH(child, &bs->children, next) {
151 if (bdrv_requests_pending(child->bs)) {
152 return true;
153 }
154 }
155
156 return false;
157 }
158
159 static bool bdrv_drain_recurse(BlockDriverState *bs)
160 {
161 BdrvChild *child;
162 bool waited;
163
164 waited = BDRV_POLL_WHILE(bs, atomic_read(&bs->in_flight) > 0);
165
166 if (bs->drv && bs->drv->bdrv_drain) {
167 bs->drv->bdrv_drain(bs);
168 }
169
170 QLIST_FOREACH(child, &bs->children, next) {
171 waited |= bdrv_drain_recurse(child->bs);
172 }
173
174 return waited;
175 }
176
177 typedef struct {
178 Coroutine *co;
179 BlockDriverState *bs;
180 bool done;
181 } BdrvCoDrainData;
182
183 static void bdrv_co_drain_bh_cb(void *opaque)
184 {
185 BdrvCoDrainData *data = opaque;
186 Coroutine *co = data->co;
187 BlockDriverState *bs = data->bs;
188
189 bdrv_dec_in_flight(bs);
190 bdrv_drained_begin(bs);
191 data->done = true;
192 qemu_coroutine_enter(co);
193 }
194
195 static void coroutine_fn bdrv_co_yield_to_drain(BlockDriverState *bs)
196 {
197 BdrvCoDrainData data;
198
199 /* Calling bdrv_drain() from a BH ensures the current coroutine yields and
200 * other coroutines run if they were queued from
201 * qemu_co_queue_run_restart(). */
202
203 assert(qemu_in_coroutine());
204 data = (BdrvCoDrainData) {
205 .co = qemu_coroutine_self(),
206 .bs = bs,
207 .done = false,
208 };
209 bdrv_inc_in_flight(bs);
210 aio_bh_schedule_oneshot(bdrv_get_aio_context(bs),
211 bdrv_co_drain_bh_cb, &data);
212
213 qemu_coroutine_yield();
214 /* If we are resumed from some other event (such as an aio completion or a
215 * timer callback), it is a bug in the caller that should be fixed. */
216 assert(data.done);
217 }
218
219 void bdrv_drained_begin(BlockDriverState *bs)
220 {
221 if (qemu_in_coroutine()) {
222 bdrv_co_yield_to_drain(bs);
223 return;
224 }
225
226 if (!bs->quiesce_counter++) {
227 aio_disable_external(bdrv_get_aio_context(bs));
228 bdrv_parent_drained_begin(bs);
229 }
230
231 bdrv_drain_recurse(bs);
232 }
233
234 void bdrv_drained_end(BlockDriverState *bs)
235 {
236 assert(bs->quiesce_counter > 0);
237 if (--bs->quiesce_counter > 0) {
238 return;
239 }
240
241 bdrv_parent_drained_end(bs);
242 aio_enable_external(bdrv_get_aio_context(bs));
243 }
244
245 /*
246 * Wait for pending requests to complete on a single BlockDriverState subtree,
247 * and suspend block driver's internal I/O until next request arrives.
248 *
249 * Note that unlike bdrv_drain_all(), the caller must hold the BlockDriverState
250 * AioContext.
251 *
252 * Only this BlockDriverState's AioContext is run, so in-flight requests must
253 * not depend on events in other AioContexts. In that case, use
254 * bdrv_drain_all() instead.
255 */
256 void coroutine_fn bdrv_co_drain(BlockDriverState *bs)
257 {
258 assert(qemu_in_coroutine());
259 bdrv_drained_begin(bs);
260 bdrv_drained_end(bs);
261 }
262
263 void bdrv_drain(BlockDriverState *bs)
264 {
265 bdrv_drained_begin(bs);
266 bdrv_drained_end(bs);
267 }
268
269 /*
270 * Wait for pending requests to complete across all BlockDriverStates
271 *
272 * This function does not flush data to disk, use bdrv_flush_all() for that
273 * after calling this function.
274 *
275 * This pauses all block jobs and disables external clients. It must
276 * be paired with bdrv_drain_all_end().
277 *
278 * NOTE: no new block jobs or BlockDriverStates can be created between
279 * the bdrv_drain_all_begin() and bdrv_drain_all_end() calls.
280 */
281 void bdrv_drain_all_begin(void)
282 {
283 /* Always run first iteration so any pending completion BHs run */
284 bool waited = true;
285 BlockDriverState *bs;
286 BdrvNextIterator it;
287 BlockJob *job = NULL;
288 GSList *aio_ctxs = NULL, *ctx;
289
290 while ((job = block_job_next(job))) {
291 AioContext *aio_context = blk_get_aio_context(job->blk);
292
293 aio_context_acquire(aio_context);
294 block_job_pause(job);
295 aio_context_release(aio_context);
296 }
297
298 for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
299 AioContext *aio_context = bdrv_get_aio_context(bs);
300
301 aio_context_acquire(aio_context);
302 bdrv_parent_drained_begin(bs);
303 aio_disable_external(aio_context);
304 aio_context_release(aio_context);
305
306 if (!g_slist_find(aio_ctxs, aio_context)) {
307 aio_ctxs = g_slist_prepend(aio_ctxs, aio_context);
308 }
309 }
310
311 /* Note that completion of an asynchronous I/O operation can trigger any
312 * number of other I/O operations on other devices---for example a
313 * coroutine can submit an I/O request to another device in response to
314 * request completion. Therefore we must keep looping until there was no
315 * more activity rather than simply draining each device independently.
316 */
317 while (waited) {
318 waited = false;
319
320 for (ctx = aio_ctxs; ctx != NULL; ctx = ctx->next) {
321 AioContext *aio_context = ctx->data;
322
323 aio_context_acquire(aio_context);
324 for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
325 if (aio_context == bdrv_get_aio_context(bs)) {
326 waited |= bdrv_drain_recurse(bs);
327 }
328 }
329 aio_context_release(aio_context);
330 }
331 }
332
333 g_slist_free(aio_ctxs);
334 }
335
336 void bdrv_drain_all_end(void)
337 {
338 BlockDriverState *bs;
339 BdrvNextIterator it;
340 BlockJob *job = NULL;
341
342 for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
343 AioContext *aio_context = bdrv_get_aio_context(bs);
344
345 aio_context_acquire(aio_context);
346 aio_enable_external(aio_context);
347 bdrv_parent_drained_end(bs);
348 aio_context_release(aio_context);
349 }
350
351 while ((job = block_job_next(job))) {
352 AioContext *aio_context = blk_get_aio_context(job->blk);
353
354 aio_context_acquire(aio_context);
355 block_job_resume(job);
356 aio_context_release(aio_context);
357 }
358 }
359
360 void bdrv_drain_all(void)
361 {
362 bdrv_drain_all_begin();
363 bdrv_drain_all_end();
364 }
365
366 /**
367 * Remove an active request from the tracked requests list
368 *
369 * This function should be called when a tracked request is completing.
370 */
371 static void tracked_request_end(BdrvTrackedRequest *req)
372 {
373 if (req->serialising) {
374 req->bs->serialising_in_flight--;
375 }
376
377 QLIST_REMOVE(req, list);
378 qemu_co_queue_restart_all(&req->wait_queue);
379 }
380
381 /**
382 * Add an active request to the tracked requests list
383 */
384 static void tracked_request_begin(BdrvTrackedRequest *req,
385 BlockDriverState *bs,
386 int64_t offset,
387 unsigned int bytes,
388 enum BdrvTrackedRequestType type)
389 {
390 *req = (BdrvTrackedRequest){
391 .bs = bs,
392 .offset = offset,
393 .bytes = bytes,
394 .type = type,
395 .co = qemu_coroutine_self(),
396 .serialising = false,
397 .overlap_offset = offset,
398 .overlap_bytes = bytes,
399 };
400
401 qemu_co_queue_init(&req->wait_queue);
402
403 QLIST_INSERT_HEAD(&bs->tracked_requests, req, list);
404 }
405
406 static void mark_request_serialising(BdrvTrackedRequest *req, uint64_t align)
407 {
408 int64_t overlap_offset = req->offset & ~(align - 1);
409 unsigned int overlap_bytes = ROUND_UP(req->offset + req->bytes, align)
410 - overlap_offset;
411
412 if (!req->serialising) {
413 req->bs->serialising_in_flight++;
414 req->serialising = true;
415 }
416
417 req->overlap_offset = MIN(req->overlap_offset, overlap_offset);
418 req->overlap_bytes = MAX(req->overlap_bytes, overlap_bytes);
419 }
420
421 /**
422 * Round a region to cluster boundaries (sector-based)
423 */
424 void bdrv_round_sectors_to_clusters(BlockDriverState *bs,
425 int64_t sector_num, int nb_sectors,
426 int64_t *cluster_sector_num,
427 int *cluster_nb_sectors)
428 {
429 BlockDriverInfo bdi;
430
431 if (bdrv_get_info(bs, &bdi) < 0 || bdi.cluster_size == 0) {
432 *cluster_sector_num = sector_num;
433 *cluster_nb_sectors = nb_sectors;
434 } else {
435 int64_t c = bdi.cluster_size / BDRV_SECTOR_SIZE;
436 *cluster_sector_num = QEMU_ALIGN_DOWN(sector_num, c);
437 *cluster_nb_sectors = QEMU_ALIGN_UP(sector_num - *cluster_sector_num +
438 nb_sectors, c);
439 }
440 }
441
442 /**
443 * Round a region to cluster boundaries
444 */
445 void bdrv_round_to_clusters(BlockDriverState *bs,
446 int64_t offset, unsigned int bytes,
447 int64_t *cluster_offset,
448 unsigned int *cluster_bytes)
449 {
450 BlockDriverInfo bdi;
451
452 if (bdrv_get_info(bs, &bdi) < 0 || bdi.cluster_size == 0) {
453 *cluster_offset = offset;
454 *cluster_bytes = bytes;
455 } else {
456 int64_t c = bdi.cluster_size;
457 *cluster_offset = QEMU_ALIGN_DOWN(offset, c);
458 *cluster_bytes = QEMU_ALIGN_UP(offset - *cluster_offset + bytes, c);
459 }
460 }
461
462 static int bdrv_get_cluster_size(BlockDriverState *bs)
463 {
464 BlockDriverInfo bdi;
465 int ret;
466
467 ret = bdrv_get_info(bs, &bdi);
468 if (ret < 0 || bdi.cluster_size == 0) {
469 return bs->bl.request_alignment;
470 } else {
471 return bdi.cluster_size;
472 }
473 }
474
475 static bool tracked_request_overlaps(BdrvTrackedRequest *req,
476 int64_t offset, unsigned int bytes)
477 {
478 /* aaaa bbbb */
479 if (offset >= req->overlap_offset + req->overlap_bytes) {
480 return false;
481 }
482 /* bbbb aaaa */
483 if (req->overlap_offset >= offset + bytes) {
484 return false;
485 }
486 return true;
487 }
488
489 void bdrv_inc_in_flight(BlockDriverState *bs)
490 {
491 atomic_inc(&bs->in_flight);
492 }
493
494 static void dummy_bh_cb(void *opaque)
495 {
496 }
497
498 void bdrv_wakeup(BlockDriverState *bs)
499 {
500 if (bs->wakeup) {
501 aio_bh_schedule_oneshot(qemu_get_aio_context(), dummy_bh_cb, NULL);
502 }
503 }
504
505 void bdrv_dec_in_flight(BlockDriverState *bs)
506 {
507 atomic_dec(&bs->in_flight);
508 bdrv_wakeup(bs);
509 }
510
511 static bool coroutine_fn wait_serialising_requests(BdrvTrackedRequest *self)
512 {
513 BlockDriverState *bs = self->bs;
514 BdrvTrackedRequest *req;
515 bool retry;
516 bool waited = false;
517
518 if (!bs->serialising_in_flight) {
519 return false;
520 }
521
522 do {
523 retry = false;
524 QLIST_FOREACH(req, &bs->tracked_requests, list) {
525 if (req == self || (!req->serialising && !self->serialising)) {
526 continue;
527 }
528 if (tracked_request_overlaps(req, self->overlap_offset,
529 self->overlap_bytes))
530 {
531 /* Hitting this means there was a reentrant request, for
532 * example, a block driver issuing nested requests. This must
533 * never happen since it means deadlock.
534 */
535 assert(qemu_coroutine_self() != req->co);
536
537 /* If the request is already (indirectly) waiting for us, or
538 * will wait for us as soon as it wakes up, then just go on
539 * (instead of producing a deadlock in the former case). */
540 if (!req->waiting_for) {
541 self->waiting_for = req;
542 qemu_co_queue_wait(&req->wait_queue);
543 self->waiting_for = NULL;
544 retry = true;
545 waited = true;
546 break;
547 }
548 }
549 }
550 } while (retry);
551
552 return waited;
553 }
554
555 static int bdrv_check_byte_request(BlockDriverState *bs, int64_t offset,
556 size_t size)
557 {
558 if (size > BDRV_REQUEST_MAX_SECTORS << BDRV_SECTOR_BITS) {
559 return -EIO;
560 }
561
562 if (!bdrv_is_inserted(bs)) {
563 return -ENOMEDIUM;
564 }
565
566 if (offset < 0) {
567 return -EIO;
568 }
569
570 return 0;
571 }
572
573 typedef struct RwCo {
574 BdrvChild *child;
575 int64_t offset;
576 QEMUIOVector *qiov;
577 bool is_write;
578 int ret;
579 BdrvRequestFlags flags;
580 } RwCo;
581
582 static void coroutine_fn bdrv_rw_co_entry(void *opaque)
583 {
584 RwCo *rwco = opaque;
585
586 if (!rwco->is_write) {
587 rwco->ret = bdrv_co_preadv(rwco->child, rwco->offset,
588 rwco->qiov->size, rwco->qiov,
589 rwco->flags);
590 } else {
591 rwco->ret = bdrv_co_pwritev(rwco->child, rwco->offset,
592 rwco->qiov->size, rwco->qiov,
593 rwco->flags);
594 }
595 }
596
597 /*
598 * Process a vectored synchronous request using coroutines
599 */
600 static int bdrv_prwv_co(BdrvChild *child, int64_t offset,
601 QEMUIOVector *qiov, bool is_write,
602 BdrvRequestFlags flags)
603 {
604 Coroutine *co;
605 RwCo rwco = {
606 .child = child,
607 .offset = offset,
608 .qiov = qiov,
609 .is_write = is_write,
610 .ret = NOT_DONE,
611 .flags = flags,
612 };
613
614 if (qemu_in_coroutine()) {
615 /* Fast-path if already in coroutine context */
616 bdrv_rw_co_entry(&rwco);
617 } else {
618 co = qemu_coroutine_create(bdrv_rw_co_entry, &rwco);
619 qemu_coroutine_enter(co);
620 BDRV_POLL_WHILE(child->bs, rwco.ret == NOT_DONE);
621 }
622 return rwco.ret;
623 }
624
625 /*
626 * Process a synchronous request using coroutines
627 */
628 static int bdrv_rw_co(BdrvChild *child, int64_t sector_num, uint8_t *buf,
629 int nb_sectors, bool is_write, BdrvRequestFlags flags)
630 {
631 QEMUIOVector qiov;
632 struct iovec iov = {
633 .iov_base = (void *)buf,
634 .iov_len = nb_sectors * BDRV_SECTOR_SIZE,
635 };
636
637 if (nb_sectors < 0 || nb_sectors > BDRV_REQUEST_MAX_SECTORS) {
638 return -EINVAL;
639 }
640
641 qemu_iovec_init_external(&qiov, &iov, 1);
642 return bdrv_prwv_co(child, sector_num << BDRV_SECTOR_BITS,
643 &qiov, is_write, flags);
644 }
645
646 /* return < 0 if error. See bdrv_write() for the return codes */
647 int bdrv_read(BdrvChild *child, int64_t sector_num,
648 uint8_t *buf, int nb_sectors)
649 {
650 return bdrv_rw_co(child, sector_num, buf, nb_sectors, false, 0);
651 }
652
653 /* Return < 0 if error. Important errors are:
654 -EIO generic I/O error (may happen for all errors)
655 -ENOMEDIUM No media inserted.
656 -EINVAL Invalid sector number or nb_sectors
657 -EACCES Trying to write a read-only device
658 */
659 int bdrv_write(BdrvChild *child, int64_t sector_num,
660 const uint8_t *buf, int nb_sectors)
661 {
662 return bdrv_rw_co(child, sector_num, (uint8_t *)buf, nb_sectors, true, 0);
663 }
664
665 int bdrv_pwrite_zeroes(BdrvChild *child, int64_t offset,
666 int count, BdrvRequestFlags flags)
667 {
668 QEMUIOVector qiov;
669 struct iovec iov = {
670 .iov_base = NULL,
671 .iov_len = count,
672 };
673
674 qemu_iovec_init_external(&qiov, &iov, 1);
675 return bdrv_prwv_co(child, offset, &qiov, true,
676 BDRV_REQ_ZERO_WRITE | flags);
677 }
678
679 /*
680 * Completely zero out a block device with the help of bdrv_pwrite_zeroes.
681 * The operation is sped up by checking the block status and only writing
682 * zeroes to the device if they currently do not return zeroes. Optional
683 * flags are passed through to bdrv_pwrite_zeroes (e.g. BDRV_REQ_MAY_UNMAP,
684 * BDRV_REQ_FUA).
685 *
686 * Returns < 0 on error, 0 on success. For error codes see bdrv_write().
687 */
688 int bdrv_make_zero(BdrvChild *child, BdrvRequestFlags flags)
689 {
690 int64_t target_sectors, ret, nb_sectors, sector_num = 0;
691 BlockDriverState *bs = child->bs;
692 BlockDriverState *file;
693 int n;
694
695 target_sectors = bdrv_nb_sectors(bs);
696 if (target_sectors < 0) {
697 return target_sectors;
698 }
699
700 for (;;) {
701 nb_sectors = MIN(target_sectors - sector_num, BDRV_REQUEST_MAX_SECTORS);
702 if (nb_sectors <= 0) {
703 return 0;
704 }
705 ret = bdrv_get_block_status(bs, sector_num, nb_sectors, &n, &file);
706 if (ret < 0) {
707 error_report("error getting block status at sector %" PRId64 ": %s",
708 sector_num, strerror(-ret));
709 return ret;
710 }
711 if (ret & BDRV_BLOCK_ZERO) {
712 sector_num += n;
713 continue;
714 }
715 ret = bdrv_pwrite_zeroes(child, sector_num << BDRV_SECTOR_BITS,
716 n << BDRV_SECTOR_BITS, flags);
717 if (ret < 0) {
718 error_report("error writing zeroes at sector %" PRId64 ": %s",
719 sector_num, strerror(-ret));
720 return ret;
721 }
722 sector_num += n;
723 }
724 }
725
726 int bdrv_preadv(BdrvChild *child, int64_t offset, QEMUIOVector *qiov)
727 {
728 int ret;
729
730 ret = bdrv_prwv_co(child, offset, qiov, false, 0);
731 if (ret < 0) {
732 return ret;
733 }
734
735 return qiov->size;
736 }
737
738 int bdrv_pread(BdrvChild *child, int64_t offset, void *buf, int bytes)
739 {
740 QEMUIOVector qiov;
741 struct iovec iov = {
742 .iov_base = (void *)buf,
743 .iov_len = bytes,
744 };
745
746 if (bytes < 0) {
747 return -EINVAL;
748 }
749
750 qemu_iovec_init_external(&qiov, &iov, 1);
751 return bdrv_preadv(child, offset, &qiov);
752 }
753
754 int bdrv_pwritev(BdrvChild *child, int64_t offset, QEMUIOVector *qiov)
755 {
756 int ret;
757
758 ret = bdrv_prwv_co(child, offset, qiov, true, 0);
759 if (ret < 0) {
760 return ret;
761 }
762
763 return qiov->size;
764 }
765
766 int bdrv_pwrite(BdrvChild *child, int64_t offset, const void *buf, int bytes)
767 {
768 QEMUIOVector qiov;
769 struct iovec iov = {
770 .iov_base = (void *) buf,
771 .iov_len = bytes,
772 };
773
774 if (bytes < 0) {
775 return -EINVAL;
776 }
777
778 qemu_iovec_init_external(&qiov, &iov, 1);
779 return bdrv_pwritev(child, offset, &qiov);
780 }
781
782 /*
783 * Writes to the file and ensures that no writes are reordered across this
784 * request (acts as a barrier)
785 *
786 * Returns 0 on success, -errno in error cases.
787 */
788 int bdrv_pwrite_sync(BdrvChild *child, int64_t offset,
789 const void *buf, int count)
790 {
791 int ret;
792
793 ret = bdrv_pwrite(child, offset, buf, count);
794 if (ret < 0) {
795 return ret;
796 }
797
798 ret = bdrv_flush(child->bs);
799 if (ret < 0) {
800 return ret;
801 }
802
803 return 0;
804 }
805
806 typedef struct CoroutineIOCompletion {
807 Coroutine *coroutine;
808 int ret;
809 } CoroutineIOCompletion;
810
811 static void bdrv_co_io_em_complete(void *opaque, int ret)
812 {
813 CoroutineIOCompletion *co = opaque;
814
815 co->ret = ret;
816 qemu_coroutine_enter(co->coroutine);
817 }
818
819 static int coroutine_fn bdrv_driver_preadv(BlockDriverState *bs,
820 uint64_t offset, uint64_t bytes,
821 QEMUIOVector *qiov, int flags)
822 {
823 BlockDriver *drv = bs->drv;
824 int64_t sector_num;
825 unsigned int nb_sectors;
826
827 assert(!(flags & ~BDRV_REQ_MASK));
828
829 if (drv->bdrv_co_preadv) {
830 return drv->bdrv_co_preadv(bs, offset, bytes, qiov, flags);
831 }
832
833 sector_num = offset >> BDRV_SECTOR_BITS;
834 nb_sectors = bytes >> BDRV_SECTOR_BITS;
835
836 assert((offset & (BDRV_SECTOR_SIZE - 1)) == 0);
837 assert((bytes & (BDRV_SECTOR_SIZE - 1)) == 0);
838 assert((bytes >> BDRV_SECTOR_BITS) <= BDRV_REQUEST_MAX_SECTORS);
839
840 if (drv->bdrv_co_readv) {
841 return drv->bdrv_co_readv(bs, sector_num, nb_sectors, qiov);
842 } else {
843 BlockAIOCB *acb;
844 CoroutineIOCompletion co = {
845 .coroutine = qemu_coroutine_self(),
846 };
847
848 acb = bs->drv->bdrv_aio_readv(bs, sector_num, qiov, nb_sectors,
849 bdrv_co_io_em_complete, &co);
850 if (acb == NULL) {
851 return -EIO;
852 } else {
853 qemu_coroutine_yield();
854 return co.ret;
855 }
856 }
857 }
858
859 static int coroutine_fn bdrv_driver_pwritev(BlockDriverState *bs,
860 uint64_t offset, uint64_t bytes,
861 QEMUIOVector *qiov, int flags)
862 {
863 BlockDriver *drv = bs->drv;
864 int64_t sector_num;
865 unsigned int nb_sectors;
866 int ret;
867
868 assert(!(flags & ~BDRV_REQ_MASK));
869
870 if (drv->bdrv_co_pwritev) {
871 ret = drv->bdrv_co_pwritev(bs, offset, bytes, qiov,
872 flags & bs->supported_write_flags);
873 flags &= ~bs->supported_write_flags;
874 goto emulate_flags;
875 }
876
877 sector_num = offset >> BDRV_SECTOR_BITS;
878 nb_sectors = bytes >> BDRV_SECTOR_BITS;
879
880 assert((offset & (BDRV_SECTOR_SIZE - 1)) == 0);
881 assert((bytes & (BDRV_SECTOR_SIZE - 1)) == 0);
882 assert((bytes >> BDRV_SECTOR_BITS) <= BDRV_REQUEST_MAX_SECTORS);
883
884 if (drv->bdrv_co_writev_flags) {
885 ret = drv->bdrv_co_writev_flags(bs, sector_num, nb_sectors, qiov,
886 flags & bs->supported_write_flags);
887 flags &= ~bs->supported_write_flags;
888 } else if (drv->bdrv_co_writev) {
889 assert(!bs->supported_write_flags);
890 ret = drv->bdrv_co_writev(bs, sector_num, nb_sectors, qiov);
891 } else {
892 BlockAIOCB *acb;
893 CoroutineIOCompletion co = {
894 .coroutine = qemu_coroutine_self(),
895 };
896
897 acb = bs->drv->bdrv_aio_writev(bs, sector_num, qiov, nb_sectors,
898 bdrv_co_io_em_complete, &co);
899 if (acb == NULL) {
900 ret = -EIO;
901 } else {
902 qemu_coroutine_yield();
903 ret = co.ret;
904 }
905 }
906
907 emulate_flags:
908 if (ret == 0 && (flags & BDRV_REQ_FUA)) {
909 ret = bdrv_co_flush(bs);
910 }
911
912 return ret;
913 }
914
915 static int coroutine_fn
916 bdrv_driver_pwritev_compressed(BlockDriverState *bs, uint64_t offset,
917 uint64_t bytes, QEMUIOVector *qiov)
918 {
919 BlockDriver *drv = bs->drv;
920
921 if (!drv->bdrv_co_pwritev_compressed) {
922 return -ENOTSUP;
923 }
924
925 return drv->bdrv_co_pwritev_compressed(bs, offset, bytes, qiov);
926 }
927
928 static int coroutine_fn bdrv_co_do_copy_on_readv(BlockDriverState *bs,
929 int64_t offset, unsigned int bytes, QEMUIOVector *qiov)
930 {
931 /* Perform I/O through a temporary buffer so that users who scribble over
932 * their read buffer while the operation is in progress do not end up
933 * modifying the image file. This is critical for zero-copy guest I/O
934 * where anything might happen inside guest memory.
935 */
936 void *bounce_buffer;
937
938 BlockDriver *drv = bs->drv;
939 struct iovec iov;
940 QEMUIOVector bounce_qiov;
941 int64_t cluster_offset;
942 unsigned int cluster_bytes;
943 size_t skip_bytes;
944 int ret;
945
946 /* Cover entire cluster so no additional backing file I/O is required when
947 * allocating cluster in the image file.
948 */
949 bdrv_round_to_clusters(bs, offset, bytes, &cluster_offset, &cluster_bytes);
950
951 trace_bdrv_co_do_copy_on_readv(bs, offset, bytes,
952 cluster_offset, cluster_bytes);
953
954 iov.iov_len = cluster_bytes;
955 iov.iov_base = bounce_buffer = qemu_try_blockalign(bs, iov.iov_len);
956 if (bounce_buffer == NULL) {
957 ret = -ENOMEM;
958 goto err;
959 }
960
961 qemu_iovec_init_external(&bounce_qiov, &iov, 1);
962
963 ret = bdrv_driver_preadv(bs, cluster_offset, cluster_bytes,
964 &bounce_qiov, 0);
965 if (ret < 0) {
966 goto err;
967 }
968
969 if (drv->bdrv_co_pwrite_zeroes &&
970 buffer_is_zero(bounce_buffer, iov.iov_len)) {
971 /* FIXME: Should we (perhaps conditionally) be setting
972 * BDRV_REQ_MAY_UNMAP, if it will allow for a sparser copy
973 * that still correctly reads as zero? */
974 ret = bdrv_co_do_pwrite_zeroes(bs, cluster_offset, cluster_bytes, 0);
975 } else {
976 /* This does not change the data on the disk, it is not necessary
977 * to flush even in cache=writethrough mode.
978 */
979 ret = bdrv_driver_pwritev(bs, cluster_offset, cluster_bytes,
980 &bounce_qiov, 0);
981 }
982
983 if (ret < 0) {
984 /* It might be okay to ignore write errors for guest requests. If this
985 * is a deliberate copy-on-read then we don't want to ignore the error.
986 * Simply report it in all cases.
987 */
988 goto err;
989 }
990
991 skip_bytes = offset - cluster_offset;
992 qemu_iovec_from_buf(qiov, 0, bounce_buffer + skip_bytes, bytes);
993
994 err:
995 qemu_vfree(bounce_buffer);
996 return ret;
997 }
998
999 /*
1000 * Forwards an already correctly aligned request to the BlockDriver. This
1001 * handles copy on read, zeroing after EOF, and fragmentation of large
1002 * reads; any other features must be implemented by the caller.
1003 */
1004 static int coroutine_fn bdrv_aligned_preadv(BlockDriverState *bs,
1005 BdrvTrackedRequest *req, int64_t offset, unsigned int bytes,
1006 int64_t align, QEMUIOVector *qiov, int flags)
1007 {
1008 int64_t total_bytes, max_bytes;
1009 int ret = 0;
1010 uint64_t bytes_remaining = bytes;
1011 int max_transfer;
1012
1013 assert(is_power_of_2(align));
1014 assert((offset & (align - 1)) == 0);
1015 assert((bytes & (align - 1)) == 0);
1016 assert(!qiov || bytes == qiov->size);
1017 assert((bs->open_flags & BDRV_O_NO_IO) == 0);
1018 max_transfer = QEMU_ALIGN_DOWN(MIN_NON_ZERO(bs->bl.max_transfer, INT_MAX),
1019 align);
1020
1021 /* TODO: We would need a per-BDS .supported_read_flags and
1022 * potential fallback support, if we ever implement any read flags
1023 * to pass through to drivers. For now, there aren't any
1024 * passthrough flags. */
1025 assert(!(flags & ~(BDRV_REQ_NO_SERIALISING | BDRV_REQ_COPY_ON_READ)));
1026
1027 /* Handle Copy on Read and associated serialisation */
1028 if (flags & BDRV_REQ_COPY_ON_READ) {
1029 /* If we touch the same cluster it counts as an overlap. This
1030 * guarantees that allocating writes will be serialized and not race
1031 * with each other for the same cluster. For example, in copy-on-read
1032 * it ensures that the CoR read and write operations are atomic and
1033 * guest writes cannot interleave between them. */
1034 mark_request_serialising(req, bdrv_get_cluster_size(bs));
1035 }
1036
1037 if (!(flags & BDRV_REQ_NO_SERIALISING)) {
1038 wait_serialising_requests(req);
1039 }
1040
1041 if (flags & BDRV_REQ_COPY_ON_READ) {
1042 int64_t start_sector = offset >> BDRV_SECTOR_BITS;
1043 int64_t end_sector = DIV_ROUND_UP(offset + bytes, BDRV_SECTOR_SIZE);
1044 unsigned int nb_sectors = end_sector - start_sector;
1045 int pnum;
1046
1047 ret = bdrv_is_allocated(bs, start_sector, nb_sectors, &pnum);
1048 if (ret < 0) {
1049 goto out;
1050 }
1051
1052 if (!ret || pnum != nb_sectors) {
1053 ret = bdrv_co_do_copy_on_readv(bs, offset, bytes, qiov);
1054 goto out;
1055 }
1056 }
1057
1058 /* Forward the request to the BlockDriver, possibly fragmenting it */
1059 total_bytes = bdrv_getlength(bs);
1060 if (total_bytes < 0) {
1061 ret = total_bytes;
1062 goto out;
1063 }
1064
1065 max_bytes = ROUND_UP(MAX(0, total_bytes - offset), align);
1066 if (bytes <= max_bytes && bytes <= max_transfer) {
1067 ret = bdrv_driver_preadv(bs, offset, bytes, qiov, 0);
1068 goto out;
1069 }
1070
1071 while (bytes_remaining) {
1072 int num;
1073
1074 if (max_bytes) {
1075 QEMUIOVector local_qiov;
1076
1077 num = MIN(bytes_remaining, MIN(max_bytes, max_transfer));
1078 assert(num);
1079 qemu_iovec_init(&local_qiov, qiov->niov);
1080 qemu_iovec_concat(&local_qiov, qiov, bytes - bytes_remaining, num);
1081
1082 ret = bdrv_driver_preadv(bs, offset + bytes - bytes_remaining,
1083 num, &local_qiov, 0);
1084 max_bytes -= num;
1085 qemu_iovec_destroy(&local_qiov);
1086 } else {
1087 num = bytes_remaining;
1088 ret = qemu_iovec_memset(qiov, bytes - bytes_remaining, 0,
1089 bytes_remaining);
1090 }
1091 if (ret < 0) {
1092 goto out;
1093 }
1094 bytes_remaining -= num;
1095 }
1096
1097 out:
1098 return ret < 0 ? ret : 0;
1099 }
1100
1101 /*
1102 * Handle a read request in coroutine context
1103 */
1104 int coroutine_fn bdrv_co_preadv(BdrvChild *child,
1105 int64_t offset, unsigned int bytes, QEMUIOVector *qiov,
1106 BdrvRequestFlags flags)
1107 {
1108 BlockDriverState *bs = child->bs;
1109 BlockDriver *drv = bs->drv;
1110 BdrvTrackedRequest req;
1111
1112 uint64_t align = bs->bl.request_alignment;
1113 uint8_t *head_buf = NULL;
1114 uint8_t *tail_buf = NULL;
1115 QEMUIOVector local_qiov;
1116 bool use_local_qiov = false;
1117 int ret;
1118
1119 if (!drv) {
1120 return -ENOMEDIUM;
1121 }
1122
1123 ret = bdrv_check_byte_request(bs, offset, bytes);
1124 if (ret < 0) {
1125 return ret;
1126 }
1127
1128 bdrv_inc_in_flight(bs);
1129
1130 /* Don't do copy-on-read if we read data before write operation */
1131 if (bs->copy_on_read && !(flags & BDRV_REQ_NO_SERIALISING)) {
1132 flags |= BDRV_REQ_COPY_ON_READ;
1133 }
1134
1135 /* Align read if necessary by padding qiov */
1136 if (offset & (align - 1)) {
1137 head_buf = qemu_blockalign(bs, align);
1138 qemu_iovec_init(&local_qiov, qiov->niov + 2);
1139 qemu_iovec_add(&local_qiov, head_buf, offset & (align - 1));
1140 qemu_iovec_concat(&local_qiov, qiov, 0, qiov->size);
1141 use_local_qiov = true;
1142
1143 bytes += offset & (align - 1);
1144 offset = offset & ~(align - 1);
1145 }
1146
1147 if ((offset + bytes) & (align - 1)) {
1148 if (!use_local_qiov) {
1149 qemu_iovec_init(&local_qiov, qiov->niov + 1);
1150 qemu_iovec_concat(&local_qiov, qiov, 0, qiov->size);
1151 use_local_qiov = true;
1152 }
1153 tail_buf = qemu_blockalign(bs, align);
1154 qemu_iovec_add(&local_qiov, tail_buf,
1155 align - ((offset + bytes) & (align - 1)));
1156
1157 bytes = ROUND_UP(bytes, align);
1158 }
1159
1160 tracked_request_begin(&req, bs, offset, bytes, BDRV_TRACKED_READ);
1161 ret = bdrv_aligned_preadv(bs, &req, offset, bytes, align,
1162 use_local_qiov ? &local_qiov : qiov,
1163 flags);
1164 tracked_request_end(&req);
1165 bdrv_dec_in_flight(bs);
1166
1167 if (use_local_qiov) {
1168 qemu_iovec_destroy(&local_qiov);
1169 qemu_vfree(head_buf);
1170 qemu_vfree(tail_buf);
1171 }
1172
1173 return ret;
1174 }
1175
1176 static int coroutine_fn bdrv_co_do_readv(BdrvChild *child,
1177 int64_t sector_num, int nb_sectors, QEMUIOVector *qiov,
1178 BdrvRequestFlags flags)
1179 {
1180 if (nb_sectors < 0 || nb_sectors > BDRV_REQUEST_MAX_SECTORS) {
1181 return -EINVAL;
1182 }
1183
1184 return bdrv_co_preadv(child, sector_num << BDRV_SECTOR_BITS,
1185 nb_sectors << BDRV_SECTOR_BITS, qiov, flags);
1186 }
1187
1188 int coroutine_fn bdrv_co_readv(BdrvChild *child, int64_t sector_num,
1189 int nb_sectors, QEMUIOVector *qiov)
1190 {
1191 trace_bdrv_co_readv(child->bs, sector_num, nb_sectors);
1192
1193 return bdrv_co_do_readv(child, sector_num, nb_sectors, qiov, 0);
1194 }
1195
1196 /* Maximum buffer for write zeroes fallback, in bytes */
1197 #define MAX_WRITE_ZEROES_BOUNCE_BUFFER (32768 << BDRV_SECTOR_BITS)
1198
1199 static int coroutine_fn bdrv_co_do_pwrite_zeroes(BlockDriverState *bs,
1200 int64_t offset, int count, BdrvRequestFlags flags)
1201 {
1202 BlockDriver *drv = bs->drv;
1203 QEMUIOVector qiov;
1204 struct iovec iov = {0};
1205 int ret = 0;
1206 bool need_flush = false;
1207 int head = 0;
1208 int tail = 0;
1209
1210 int max_write_zeroes = MIN_NON_ZERO(bs->bl.max_pwrite_zeroes, INT_MAX);
1211 int alignment = MAX(bs->bl.pwrite_zeroes_alignment,
1212 bs->bl.request_alignment);
1213 int max_transfer = MIN_NON_ZERO(bs->bl.max_transfer,
1214 MAX_WRITE_ZEROES_BOUNCE_BUFFER);
1215
1216 assert(alignment % bs->bl.request_alignment == 0);
1217 head = offset % alignment;
1218 tail = (offset + count) % alignment;
1219 max_write_zeroes = QEMU_ALIGN_DOWN(max_write_zeroes, alignment);
1220 assert(max_write_zeroes >= bs->bl.request_alignment);
1221
1222 while (count > 0 && !ret) {
1223 int num = count;
1224
1225 /* Align request. Block drivers can expect the "bulk" of the request
1226 * to be aligned, and that unaligned requests do not cross cluster
1227 * boundaries.
1228 */
1229 if (head) {
1230 /* Make a small request up to the first aligned sector. For
1231 * convenience, limit this request to max_transfer even if
1232 * we don't need to fall back to writes. */
1233 num = MIN(MIN(count, max_transfer), alignment - head);
1234 head = (head + num) % alignment;
1235 assert(num < max_write_zeroes);
1236 } else if (tail && num > alignment) {
1237 /* Shorten the request to the last aligned sector. */
1238 num -= tail;
1239 }
1240
1241 /* limit request size */
1242 if (num > max_write_zeroes) {
1243 num = max_write_zeroes;
1244 }
1245
1246 ret = -ENOTSUP;
1247 /* First try the efficient write zeroes operation */
1248 if (drv->bdrv_co_pwrite_zeroes) {
1249 ret = drv->bdrv_co_pwrite_zeroes(bs, offset, num,
1250 flags & bs->supported_zero_flags);
1251 if (ret != -ENOTSUP && (flags & BDRV_REQ_FUA) &&
1252 !(bs->supported_zero_flags & BDRV_REQ_FUA)) {
1253 need_flush = true;
1254 }
1255 } else {
1256 assert(!bs->supported_zero_flags);
1257 }
1258
1259 if (ret == -ENOTSUP) {
1260 /* Fall back to bounce buffer if write zeroes is unsupported */
1261 BdrvRequestFlags write_flags = flags & ~BDRV_REQ_ZERO_WRITE;
1262
1263 if ((flags & BDRV_REQ_FUA) &&
1264 !(bs->supported_write_flags & BDRV_REQ_FUA)) {
1265 /* No need for bdrv_driver_pwrite() to do a fallback
1266 * flush on each chunk; use just one at the end */
1267 write_flags &= ~BDRV_REQ_FUA;
1268 need_flush = true;
1269 }
1270 num = MIN(num, max_transfer);
1271 iov.iov_len = num;
1272 if (iov.iov_base == NULL) {
1273 iov.iov_base = qemu_try_blockalign(bs, num);
1274 if (iov.iov_base == NULL) {
1275 ret = -ENOMEM;
1276 goto fail;
1277 }
1278 memset(iov.iov_base, 0, num);
1279 }
1280 qemu_iovec_init_external(&qiov, &iov, 1);
1281
1282 ret = bdrv_driver_pwritev(bs, offset, num, &qiov, write_flags);
1283
1284 /* Keep bounce buffer around if it is big enough for all
1285 * all future requests.
1286 */
1287 if (num < max_transfer) {
1288 qemu_vfree(iov.iov_base);
1289 iov.iov_base = NULL;
1290 }
1291 }
1292
1293 offset += num;
1294 count -= num;
1295 }
1296
1297 fail:
1298 if (ret == 0 && need_flush) {
1299 ret = bdrv_co_flush(bs);
1300 }
1301 qemu_vfree(iov.iov_base);
1302 return ret;
1303 }
1304
1305 /*
1306 * Forwards an already correctly aligned write request to the BlockDriver,
1307 * after possibly fragmenting it.
1308 */
1309 static int coroutine_fn bdrv_aligned_pwritev(BlockDriverState *bs,
1310 BdrvTrackedRequest *req, int64_t offset, unsigned int bytes,
1311 int64_t align, QEMUIOVector *qiov, int flags)
1312 {
1313 BlockDriver *drv = bs->drv;
1314 bool waited;
1315 int ret;
1316
1317 int64_t start_sector = offset >> BDRV_SECTOR_BITS;
1318 int64_t end_sector = DIV_ROUND_UP(offset + bytes, BDRV_SECTOR_SIZE);
1319 uint64_t bytes_remaining = bytes;
1320 int max_transfer;
1321
1322 assert(is_power_of_2(align));
1323 assert((offset & (align - 1)) == 0);
1324 assert((bytes & (align - 1)) == 0);
1325 assert(!qiov || bytes == qiov->size);
1326 assert((bs->open_flags & BDRV_O_NO_IO) == 0);
1327 assert(!(flags & ~BDRV_REQ_MASK));
1328 max_transfer = QEMU_ALIGN_DOWN(MIN_NON_ZERO(bs->bl.max_transfer, INT_MAX),
1329 align);
1330
1331 waited = wait_serialising_requests(req);
1332 assert(!waited || !req->serialising);
1333 assert(req->overlap_offset <= offset);
1334 assert(offset + bytes <= req->overlap_offset + req->overlap_bytes);
1335
1336 ret = notifier_with_return_list_notify(&bs->before_write_notifiers, req);
1337
1338 if (!ret && bs->detect_zeroes != BLOCKDEV_DETECT_ZEROES_OPTIONS_OFF &&
1339 !(flags & BDRV_REQ_ZERO_WRITE) && drv->bdrv_co_pwrite_zeroes &&
1340 qemu_iovec_is_zero(qiov)) {
1341 flags |= BDRV_REQ_ZERO_WRITE;
1342 if (bs->detect_zeroes == BLOCKDEV_DETECT_ZEROES_OPTIONS_UNMAP) {
1343 flags |= BDRV_REQ_MAY_UNMAP;
1344 }
1345 }
1346
1347 if (ret < 0) {
1348 /* Do nothing, write notifier decided to fail this request */
1349 } else if (flags & BDRV_REQ_ZERO_WRITE) {
1350 bdrv_debug_event(bs, BLKDBG_PWRITEV_ZERO);
1351 ret = bdrv_co_do_pwrite_zeroes(bs, offset, bytes, flags);
1352 } else if (flags & BDRV_REQ_WRITE_COMPRESSED) {
1353 ret = bdrv_driver_pwritev_compressed(bs, offset, bytes, qiov);
1354 } else if (bytes <= max_transfer) {
1355 bdrv_debug_event(bs, BLKDBG_PWRITEV);
1356 ret = bdrv_driver_pwritev(bs, offset, bytes, qiov, flags);
1357 } else {
1358 bdrv_debug_event(bs, BLKDBG_PWRITEV);
1359 while (bytes_remaining) {
1360 int num = MIN(bytes_remaining, max_transfer);
1361 QEMUIOVector local_qiov;
1362 int local_flags = flags;
1363
1364 assert(num);
1365 if (num < bytes_remaining && (flags & BDRV_REQ_FUA) &&
1366 !(bs->supported_write_flags & BDRV_REQ_FUA)) {
1367 /* If FUA is going to be emulated by flush, we only
1368 * need to flush on the last iteration */
1369 local_flags &= ~BDRV_REQ_FUA;
1370 }
1371 qemu_iovec_init(&local_qiov, qiov->niov);
1372 qemu_iovec_concat(&local_qiov, qiov, bytes - bytes_remaining, num);
1373
1374 ret = bdrv_driver_pwritev(bs, offset + bytes - bytes_remaining,
1375 num, &local_qiov, local_flags);
1376 qemu_iovec_destroy(&local_qiov);
1377 if (ret < 0) {
1378 break;
1379 }
1380 bytes_remaining -= num;
1381 }
1382 }
1383 bdrv_debug_event(bs, BLKDBG_PWRITEV_DONE);
1384
1385 ++bs->write_gen;
1386 bdrv_set_dirty(bs, start_sector, end_sector - start_sector);
1387
1388 if (bs->wr_highest_offset < offset + bytes) {
1389 bs->wr_highest_offset = offset + bytes;
1390 }
1391
1392 if (ret >= 0) {
1393 bs->total_sectors = MAX(bs->total_sectors, end_sector);
1394 ret = 0;
1395 }
1396
1397 return ret;
1398 }
1399
1400 static int coroutine_fn bdrv_co_do_zero_pwritev(BlockDriverState *bs,
1401 int64_t offset,
1402 unsigned int bytes,
1403 BdrvRequestFlags flags,
1404 BdrvTrackedRequest *req)
1405 {
1406 uint8_t *buf = NULL;
1407 QEMUIOVector local_qiov;
1408 struct iovec iov;
1409 uint64_t align = bs->bl.request_alignment;
1410 unsigned int head_padding_bytes, tail_padding_bytes;
1411 int ret = 0;
1412
1413 head_padding_bytes = offset & (align - 1);
1414 tail_padding_bytes = align - ((offset + bytes) & (align - 1));
1415
1416
1417 assert(flags & BDRV_REQ_ZERO_WRITE);
1418 if (head_padding_bytes || tail_padding_bytes) {
1419 buf = qemu_blockalign(bs, align);
1420 iov = (struct iovec) {
1421 .iov_base = buf,
1422 .iov_len = align,
1423 };
1424 qemu_iovec_init_external(&local_qiov, &iov, 1);
1425 }
1426 if (head_padding_bytes) {
1427 uint64_t zero_bytes = MIN(bytes, align - head_padding_bytes);
1428
1429 /* RMW the unaligned part before head. */
1430 mark_request_serialising(req, align);
1431 wait_serialising_requests(req);
1432 bdrv_debug_event(bs, BLKDBG_PWRITEV_RMW_HEAD);
1433 ret = bdrv_aligned_preadv(bs, req, offset & ~(align - 1), align,
1434 align, &local_qiov, 0);
1435 if (ret < 0) {
1436 goto fail;
1437 }
1438 bdrv_debug_event(bs, BLKDBG_PWRITEV_RMW_AFTER_HEAD);
1439
1440 memset(buf + head_padding_bytes, 0, zero_bytes);
1441 ret = bdrv_aligned_pwritev(bs, req, offset & ~(align - 1), align,
1442 align, &local_qiov,
1443 flags & ~BDRV_REQ_ZERO_WRITE);
1444 if (ret < 0) {
1445 goto fail;
1446 }
1447 offset += zero_bytes;
1448 bytes -= zero_bytes;
1449 }
1450
1451 assert(!bytes || (offset & (align - 1)) == 0);
1452 if (bytes >= align) {
1453 /* Write the aligned part in the middle. */
1454 uint64_t aligned_bytes = bytes & ~(align - 1);
1455 ret = bdrv_aligned_pwritev(bs, req, offset, aligned_bytes, align,
1456 NULL, flags);
1457 if (ret < 0) {
1458 goto fail;
1459 }
1460 bytes -= aligned_bytes;
1461 offset += aligned_bytes;
1462 }
1463
1464 assert(!bytes || (offset & (align - 1)) == 0);
1465 if (bytes) {
1466 assert(align == tail_padding_bytes + bytes);
1467 /* RMW the unaligned part after tail. */
1468 mark_request_serialising(req, align);
1469 wait_serialising_requests(req);
1470 bdrv_debug_event(bs, BLKDBG_PWRITEV_RMW_TAIL);
1471 ret = bdrv_aligned_preadv(bs, req, offset, align,
1472 align, &local_qiov, 0);
1473 if (ret < 0) {
1474 goto fail;
1475 }
1476 bdrv_debug_event(bs, BLKDBG_PWRITEV_RMW_AFTER_TAIL);
1477
1478 memset(buf, 0, bytes);
1479 ret = bdrv_aligned_pwritev(bs, req, offset, align, align,
1480 &local_qiov, flags & ~BDRV_REQ_ZERO_WRITE);
1481 }
1482 fail:
1483 qemu_vfree(buf);
1484 return ret;
1485
1486 }
1487
1488 /*
1489 * Handle a write request in coroutine context
1490 */
1491 int coroutine_fn bdrv_co_pwritev(BdrvChild *child,
1492 int64_t offset, unsigned int bytes, QEMUIOVector *qiov,
1493 BdrvRequestFlags flags)
1494 {
1495 BlockDriverState *bs = child->bs;
1496 BdrvTrackedRequest req;
1497 uint64_t align = bs->bl.request_alignment;
1498 uint8_t *head_buf = NULL;
1499 uint8_t *tail_buf = NULL;
1500 QEMUIOVector local_qiov;
1501 bool use_local_qiov = false;
1502 int ret;
1503
1504 if (!bs->drv) {
1505 return -ENOMEDIUM;
1506 }
1507 if (bs->read_only) {
1508 return -EPERM;
1509 }
1510 assert(!(bs->open_flags & BDRV_O_INACTIVE));
1511
1512 ret = bdrv_check_byte_request(bs, offset, bytes);
1513 if (ret < 0) {
1514 return ret;
1515 }
1516
1517 bdrv_inc_in_flight(bs);
1518 /*
1519 * Align write if necessary by performing a read-modify-write cycle.
1520 * Pad qiov with the read parts and be sure to have a tracked request not
1521 * only for bdrv_aligned_pwritev, but also for the reads of the RMW cycle.
1522 */
1523 tracked_request_begin(&req, bs, offset, bytes, BDRV_TRACKED_WRITE);
1524
1525 if (!qiov) {
1526 ret = bdrv_co_do_zero_pwritev(bs, offset, bytes, flags, &req);
1527 goto out;
1528 }
1529
1530 if (offset & (align - 1)) {
1531 QEMUIOVector head_qiov;
1532 struct iovec head_iov;
1533
1534 mark_request_serialising(&req, align);
1535 wait_serialising_requests(&req);
1536
1537 head_buf = qemu_blockalign(bs, align);
1538 head_iov = (struct iovec) {
1539 .iov_base = head_buf,
1540 .iov_len = align,
1541 };
1542 qemu_iovec_init_external(&head_qiov, &head_iov, 1);
1543
1544 bdrv_debug_event(bs, BLKDBG_PWRITEV_RMW_HEAD);
1545 ret = bdrv_aligned_preadv(bs, &req, offset & ~(align - 1), align,
1546 align, &head_qiov, 0);
1547 if (ret < 0) {
1548 goto fail;
1549 }
1550 bdrv_debug_event(bs, BLKDBG_PWRITEV_RMW_AFTER_HEAD);
1551
1552 qemu_iovec_init(&local_qiov, qiov->niov + 2);
1553 qemu_iovec_add(&local_qiov, head_buf, offset & (align - 1));
1554 qemu_iovec_concat(&local_qiov, qiov, 0, qiov->size);
1555 use_local_qiov = true;
1556
1557 bytes += offset & (align - 1);
1558 offset = offset & ~(align - 1);
1559
1560 /* We have read the tail already if the request is smaller
1561 * than one aligned block.
1562 */
1563 if (bytes < align) {
1564 qemu_iovec_add(&local_qiov, head_buf + bytes, align - bytes);
1565 bytes = align;
1566 }
1567 }
1568
1569 if ((offset + bytes) & (align - 1)) {
1570 QEMUIOVector tail_qiov;
1571 struct iovec tail_iov;
1572 size_t tail_bytes;
1573 bool waited;
1574
1575 mark_request_serialising(&req, align);
1576 waited = wait_serialising_requests(&req);
1577 assert(!waited || !use_local_qiov);
1578
1579 tail_buf = qemu_blockalign(bs, align);
1580 tail_iov = (struct iovec) {
1581 .iov_base = tail_buf,
1582 .iov_len = align,
1583 };
1584 qemu_iovec_init_external(&tail_qiov, &tail_iov, 1);
1585
1586 bdrv_debug_event(bs, BLKDBG_PWRITEV_RMW_TAIL);
1587 ret = bdrv_aligned_preadv(bs, &req, (offset + bytes) & ~(align - 1), align,
1588 align, &tail_qiov, 0);
1589 if (ret < 0) {
1590 goto fail;
1591 }
1592 bdrv_debug_event(bs, BLKDBG_PWRITEV_RMW_AFTER_TAIL);
1593
1594 if (!use_local_qiov) {
1595 qemu_iovec_init(&local_qiov, qiov->niov + 1);
1596 qemu_iovec_concat(&local_qiov, qiov, 0, qiov->size);
1597 use_local_qiov = true;
1598 }
1599
1600 tail_bytes = (offset + bytes) & (align - 1);
1601 qemu_iovec_add(&local_qiov, tail_buf + tail_bytes, align - tail_bytes);
1602
1603 bytes = ROUND_UP(bytes, align);
1604 }
1605
1606 ret = bdrv_aligned_pwritev(bs, &req, offset, bytes, align,
1607 use_local_qiov ? &local_qiov : qiov,
1608 flags);
1609
1610 fail:
1611
1612 if (use_local_qiov) {
1613 qemu_iovec_destroy(&local_qiov);
1614 }
1615 qemu_vfree(head_buf);
1616 qemu_vfree(tail_buf);
1617 out:
1618 tracked_request_end(&req);
1619 bdrv_dec_in_flight(bs);
1620 return ret;
1621 }
1622
1623 static int coroutine_fn bdrv_co_do_writev(BdrvChild *child,
1624 int64_t sector_num, int nb_sectors, QEMUIOVector *qiov,
1625 BdrvRequestFlags flags)
1626 {
1627 if (nb_sectors < 0 || nb_sectors > BDRV_REQUEST_MAX_SECTORS) {
1628 return -EINVAL;
1629 }
1630
1631 return bdrv_co_pwritev(child, sector_num << BDRV_SECTOR_BITS,
1632 nb_sectors << BDRV_SECTOR_BITS, qiov, flags);
1633 }
1634
1635 int coroutine_fn bdrv_co_writev(BdrvChild *child, int64_t sector_num,
1636 int nb_sectors, QEMUIOVector *qiov)
1637 {
1638 trace_bdrv_co_writev(child->bs, sector_num, nb_sectors);
1639
1640 return bdrv_co_do_writev(child, sector_num, nb_sectors, qiov, 0);
1641 }
1642
1643 int coroutine_fn bdrv_co_pwrite_zeroes(BdrvChild *child, int64_t offset,
1644 int count, BdrvRequestFlags flags)
1645 {
1646 trace_bdrv_co_pwrite_zeroes(child->bs, offset, count, flags);
1647
1648 if (!(child->bs->open_flags & BDRV_O_UNMAP)) {
1649 flags &= ~BDRV_REQ_MAY_UNMAP;
1650 }
1651
1652 return bdrv_co_pwritev(child, offset, count, NULL,
1653 BDRV_REQ_ZERO_WRITE | flags);
1654 }
1655
1656 /*
1657 * Flush ALL BDSes regardless of if they are reachable via a BlkBackend or not.
1658 */
1659 int bdrv_flush_all(void)
1660 {
1661 BdrvNextIterator it;
1662 BlockDriverState *bs = NULL;
1663 int result = 0;
1664
1665 for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
1666 AioContext *aio_context = bdrv_get_aio_context(bs);
1667 int ret;
1668
1669 aio_context_acquire(aio_context);
1670 ret = bdrv_flush(bs);
1671 if (ret < 0 && !result) {
1672 result = ret;
1673 }
1674 aio_context_release(aio_context);
1675 }
1676
1677 return result;
1678 }
1679
1680
1681 typedef struct BdrvCoGetBlockStatusData {
1682 BlockDriverState *bs;
1683 BlockDriverState *base;
1684 BlockDriverState **file;
1685 int64_t sector_num;
1686 int nb_sectors;
1687 int *pnum;
1688 int64_t ret;
1689 bool done;
1690 } BdrvCoGetBlockStatusData;
1691
1692 /*
1693 * Returns the allocation status of the specified sectors.
1694 * Drivers not implementing the functionality are assumed to not support
1695 * backing files, hence all their sectors are reported as allocated.
1696 *
1697 * If 'sector_num' is beyond the end of the disk image the return value is 0
1698 * and 'pnum' is set to 0.
1699 *
1700 * 'pnum' is set to the number of sectors (including and immediately following
1701 * the specified sector) that are known to be in the same
1702 * allocated/unallocated state.
1703 *
1704 * 'nb_sectors' is the max value 'pnum' should be set to. If nb_sectors goes
1705 * beyond the end of the disk image it will be clamped.
1706 *
1707 * If returned value is positive and BDRV_BLOCK_OFFSET_VALID bit is set, 'file'
1708 * points to the BDS which the sector range is allocated in.
1709 */
1710 static int64_t coroutine_fn bdrv_co_get_block_status(BlockDriverState *bs,
1711 int64_t sector_num,
1712 int nb_sectors, int *pnum,
1713 BlockDriverState **file)
1714 {
1715 int64_t total_sectors;
1716 int64_t n;
1717 int64_t ret, ret2;
1718
1719 total_sectors = bdrv_nb_sectors(bs);
1720 if (total_sectors < 0) {
1721 return total_sectors;
1722 }
1723
1724 if (sector_num >= total_sectors) {
1725 *pnum = 0;
1726 return 0;
1727 }
1728
1729 n = total_sectors - sector_num;
1730 if (n < nb_sectors) {
1731 nb_sectors = n;
1732 }
1733
1734 if (!bs->drv->bdrv_co_get_block_status) {
1735 *pnum = nb_sectors;
1736 ret = BDRV_BLOCK_DATA | BDRV_BLOCK_ALLOCATED;
1737 if (bs->drv->protocol_name) {
1738 ret |= BDRV_BLOCK_OFFSET_VALID | (sector_num * BDRV_SECTOR_SIZE);
1739 }
1740 return ret;
1741 }
1742
1743 *file = NULL;
1744 bdrv_inc_in_flight(bs);
1745 ret = bs->drv->bdrv_co_get_block_status(bs, sector_num, nb_sectors, pnum,
1746 file);
1747 if (ret < 0) {
1748 *pnum = 0;
1749 goto out;
1750 }
1751
1752 if (ret & BDRV_BLOCK_RAW) {
1753 assert(ret & BDRV_BLOCK_OFFSET_VALID);
1754 ret = bdrv_get_block_status(bs->file->bs, ret >> BDRV_SECTOR_BITS,
1755 *pnum, pnum, file);
1756 goto out;
1757 }
1758
1759 if (ret & (BDRV_BLOCK_DATA | BDRV_BLOCK_ZERO)) {
1760 ret |= BDRV_BLOCK_ALLOCATED;
1761 } else {
1762 if (bdrv_unallocated_blocks_are_zero(bs)) {
1763 ret |= BDRV_BLOCK_ZERO;
1764 } else if (bs->backing) {
1765 BlockDriverState *bs2 = bs->backing->bs;
1766 int64_t nb_sectors2 = bdrv_nb_sectors(bs2);
1767 if (nb_sectors2 >= 0 && sector_num >= nb_sectors2) {
1768 ret |= BDRV_BLOCK_ZERO;
1769 }
1770 }
1771 }
1772
1773 if (*file && *file != bs &&
1774 (ret & BDRV_BLOCK_DATA) && !(ret & BDRV_BLOCK_ZERO) &&
1775 (ret & BDRV_BLOCK_OFFSET_VALID)) {
1776 BlockDriverState *file2;
1777 int file_pnum;
1778
1779 ret2 = bdrv_co_get_block_status(*file, ret >> BDRV_SECTOR_BITS,
1780 *pnum, &file_pnum, &file2);
1781 if (ret2 >= 0) {
1782 /* Ignore errors. This is just providing extra information, it
1783 * is useful but not necessary.
1784 */
1785 if (!file_pnum) {
1786 /* !file_pnum indicates an offset at or beyond the EOF; it is
1787 * perfectly valid for the format block driver to point to such
1788 * offsets, so catch it and mark everything as zero */
1789 ret |= BDRV_BLOCK_ZERO;
1790 } else {
1791 /* Limit request to the range reported by the protocol driver */
1792 *pnum = file_pnum;
1793 ret |= (ret2 & BDRV_BLOCK_ZERO);
1794 }
1795 }
1796 }
1797
1798 out:
1799 bdrv_dec_in_flight(bs);
1800 return ret;
1801 }
1802
1803 static int64_t coroutine_fn bdrv_co_get_block_status_above(BlockDriverState *bs,
1804 BlockDriverState *base,
1805 int64_t sector_num,
1806 int nb_sectors,
1807 int *pnum,
1808 BlockDriverState **file)
1809 {
1810 BlockDriverState *p;
1811 int64_t ret = 0;
1812
1813 assert(bs != base);
1814 for (p = bs; p != base; p = backing_bs(p)) {
1815 ret = bdrv_co_get_block_status(p, sector_num, nb_sectors, pnum, file);
1816 if (ret < 0 || ret & BDRV_BLOCK_ALLOCATED) {
1817 break;
1818 }
1819 /* [sector_num, pnum] unallocated on this layer, which could be only
1820 * the first part of [sector_num, nb_sectors]. */
1821 nb_sectors = MIN(nb_sectors, *pnum);
1822 }
1823 return ret;
1824 }
1825
1826 /* Coroutine wrapper for bdrv_get_block_status_above() */
1827 static void coroutine_fn bdrv_get_block_status_above_co_entry(void *opaque)
1828 {
1829 BdrvCoGetBlockStatusData *data = opaque;
1830
1831 data->ret = bdrv_co_get_block_status_above(data->bs, data->base,
1832 data->sector_num,
1833 data->nb_sectors,
1834 data->pnum,
1835 data->file);
1836 data->done = true;
1837 }
1838
1839 /*
1840 * Synchronous wrapper around bdrv_co_get_block_status_above().
1841 *
1842 * See bdrv_co_get_block_status_above() for details.
1843 */
1844 int64_t bdrv_get_block_status_above(BlockDriverState *bs,
1845 BlockDriverState *base,
1846 int64_t sector_num,
1847 int nb_sectors, int *pnum,
1848 BlockDriverState **file)
1849 {
1850 Coroutine *co;
1851 BdrvCoGetBlockStatusData data = {
1852 .bs = bs,
1853 .base = base,
1854 .file = file,
1855 .sector_num = sector_num,
1856 .nb_sectors = nb_sectors,
1857 .pnum = pnum,
1858 .done = false,
1859 };
1860
1861 if (qemu_in_coroutine()) {
1862 /* Fast-path if already in coroutine context */
1863 bdrv_get_block_status_above_co_entry(&data);
1864 } else {
1865 co = qemu_coroutine_create(bdrv_get_block_status_above_co_entry,
1866 &data);
1867 qemu_coroutine_enter(co);
1868 BDRV_POLL_WHILE(bs, !data.done);
1869 }
1870 return data.ret;
1871 }
1872
1873 int64_t bdrv_get_block_status(BlockDriverState *bs,
1874 int64_t sector_num,
1875 int nb_sectors, int *pnum,
1876 BlockDriverState **file)
1877 {
1878 return bdrv_get_block_status_above(bs, backing_bs(bs),
1879 sector_num, nb_sectors, pnum, file);
1880 }
1881
1882 int coroutine_fn bdrv_is_allocated(BlockDriverState *bs, int64_t sector_num,
1883 int nb_sectors, int *pnum)
1884 {
1885 BlockDriverState *file;
1886 int64_t ret = bdrv_get_block_status(bs, sector_num, nb_sectors, pnum,
1887 &file);
1888 if (ret < 0) {
1889 return ret;
1890 }
1891 return !!(ret & BDRV_BLOCK_ALLOCATED);
1892 }
1893
1894 /*
1895 * Given an image chain: ... -> [BASE] -> [INTER1] -> [INTER2] -> [TOP]
1896 *
1897 * Return true if the given sector is allocated in any image between
1898 * BASE and TOP (inclusive). BASE can be NULL to check if the given
1899 * sector is allocated in any image of the chain. Return false otherwise.
1900 *
1901 * 'pnum' is set to the number of sectors (including and immediately following
1902 * the specified sector) that are known to be in the same
1903 * allocated/unallocated state.
1904 *
1905 */
1906 int bdrv_is_allocated_above(BlockDriverState *top,
1907 BlockDriverState *base,
1908 int64_t sector_num,
1909 int nb_sectors, int *pnum)
1910 {
1911 BlockDriverState *intermediate;
1912 int ret, n = nb_sectors;
1913
1914 intermediate = top;
1915 while (intermediate && intermediate != base) {
1916 int pnum_inter;
1917 ret = bdrv_is_allocated(intermediate, sector_num, nb_sectors,
1918 &pnum_inter);
1919 if (ret < 0) {
1920 return ret;
1921 } else if (ret) {
1922 *pnum = pnum_inter;
1923 return 1;
1924 }
1925
1926 /*
1927 * [sector_num, nb_sectors] is unallocated on top but intermediate
1928 * might have
1929 *
1930 * [sector_num+x, nr_sectors] allocated.
1931 */
1932 if (n > pnum_inter &&
1933 (intermediate == top ||
1934 sector_num + pnum_inter < intermediate->total_sectors)) {
1935 n = pnum_inter;
1936 }
1937
1938 intermediate = backing_bs(intermediate);
1939 }
1940
1941 *pnum = n;
1942 return 0;
1943 }
1944
1945 typedef struct BdrvVmstateCo {
1946 BlockDriverState *bs;
1947 QEMUIOVector *qiov;
1948 int64_t pos;
1949 bool is_read;
1950 int ret;
1951 } BdrvVmstateCo;
1952
1953 static int coroutine_fn
1954 bdrv_co_rw_vmstate(BlockDriverState *bs, QEMUIOVector *qiov, int64_t pos,
1955 bool is_read)
1956 {
1957 BlockDriver *drv = bs->drv;
1958
1959 if (!drv) {
1960 return -ENOMEDIUM;
1961 } else if (drv->bdrv_load_vmstate) {
1962 return is_read ? drv->bdrv_load_vmstate(bs, qiov, pos)
1963 : drv->bdrv_save_vmstate(bs, qiov, pos);
1964 } else if (bs->file) {
1965 return bdrv_co_rw_vmstate(bs->file->bs, qiov, pos, is_read);
1966 }
1967
1968 return -ENOTSUP;
1969 }
1970
1971 static void coroutine_fn bdrv_co_rw_vmstate_entry(void *opaque)
1972 {
1973 BdrvVmstateCo *co = opaque;
1974 co->ret = bdrv_co_rw_vmstate(co->bs, co->qiov, co->pos, co->is_read);
1975 }
1976
1977 static inline int
1978 bdrv_rw_vmstate(BlockDriverState *bs, QEMUIOVector *qiov, int64_t pos,
1979 bool is_read)
1980 {
1981 if (qemu_in_coroutine()) {
1982 return bdrv_co_rw_vmstate(bs, qiov, pos, is_read);
1983 } else {
1984 BdrvVmstateCo data = {
1985 .bs = bs,
1986 .qiov = qiov,
1987 .pos = pos,
1988 .is_read = is_read,
1989 .ret = -EINPROGRESS,
1990 };
1991 Coroutine *co = qemu_coroutine_create(bdrv_co_rw_vmstate_entry, &data);
1992
1993 qemu_coroutine_enter(co);
1994 while (data.ret == -EINPROGRESS) {
1995 aio_poll(bdrv_get_aio_context(bs), true);
1996 }
1997 return data.ret;
1998 }
1999 }
2000
2001 int bdrv_save_vmstate(BlockDriverState *bs, const uint8_t *buf,
2002 int64_t pos, int size)
2003 {
2004 QEMUIOVector qiov;
2005 struct iovec iov = {
2006 .iov_base = (void *) buf,
2007 .iov_len = size,
2008 };
2009 int ret;
2010
2011 qemu_iovec_init_external(&qiov, &iov, 1);
2012
2013 ret = bdrv_writev_vmstate(bs, &qiov, pos);
2014 if (ret < 0) {
2015 return ret;
2016 }
2017
2018 return size;
2019 }
2020
2021 int bdrv_writev_vmstate(BlockDriverState *bs, QEMUIOVector *qiov, int64_t pos)
2022 {
2023 return bdrv_rw_vmstate(bs, qiov, pos, false);
2024 }
2025
2026 int bdrv_load_vmstate(BlockDriverState *bs, uint8_t *buf,
2027 int64_t pos, int size)
2028 {
2029 QEMUIOVector qiov;
2030 struct iovec iov = {
2031 .iov_base = buf,
2032 .iov_len = size,
2033 };
2034 int ret;
2035
2036 qemu_iovec_init_external(&qiov, &iov, 1);
2037 ret = bdrv_readv_vmstate(bs, &qiov, pos);
2038 if (ret < 0) {
2039 return ret;
2040 }
2041
2042 return size;
2043 }
2044
2045 int bdrv_readv_vmstate(BlockDriverState *bs, QEMUIOVector *qiov, int64_t pos)
2046 {
2047 return bdrv_rw_vmstate(bs, qiov, pos, true);
2048 }
2049
2050 /**************************************************************/
2051 /* async I/Os */
2052
2053 BlockAIOCB *bdrv_aio_readv(BdrvChild *child, int64_t sector_num,
2054 QEMUIOVector *qiov, int nb_sectors,
2055 BlockCompletionFunc *cb, void *opaque)
2056 {
2057 trace_bdrv_aio_readv(child->bs, sector_num, nb_sectors, opaque);
2058
2059 assert(nb_sectors << BDRV_SECTOR_BITS == qiov->size);
2060 return bdrv_co_aio_prw_vector(child, sector_num << BDRV_SECTOR_BITS, qiov,
2061 0, cb, opaque, false);
2062 }
2063
2064 BlockAIOCB *bdrv_aio_writev(BdrvChild *child, int64_t sector_num,
2065 QEMUIOVector *qiov, int nb_sectors,
2066 BlockCompletionFunc *cb, void *opaque)
2067 {
2068 trace_bdrv_aio_writev(child->bs, sector_num, nb_sectors, opaque);
2069
2070 assert(nb_sectors << BDRV_SECTOR_BITS == qiov->size);
2071 return bdrv_co_aio_prw_vector(child, sector_num << BDRV_SECTOR_BITS, qiov,
2072 0, cb, opaque, true);
2073 }
2074
2075 void bdrv_aio_cancel(BlockAIOCB *acb)
2076 {
2077 qemu_aio_ref(acb);
2078 bdrv_aio_cancel_async(acb);
2079 while (acb->refcnt > 1) {
2080 if (acb->aiocb_info->get_aio_context) {
2081 aio_poll(acb->aiocb_info->get_aio_context(acb), true);
2082 } else if (acb->bs) {
2083 aio_poll(bdrv_get_aio_context(acb->bs), true);
2084 } else {
2085 abort();
2086 }
2087 }
2088 qemu_aio_unref(acb);
2089 }
2090
2091 /* Async version of aio cancel. The caller is not blocked if the acb implements
2092 * cancel_async, otherwise we do nothing and let the request normally complete.
2093 * In either case the completion callback must be called. */
2094 void bdrv_aio_cancel_async(BlockAIOCB *acb)
2095 {
2096 if (acb->aiocb_info->cancel_async) {
2097 acb->aiocb_info->cancel_async(acb);
2098 }
2099 }
2100
2101 /**************************************************************/
2102 /* async block device emulation */
2103
2104 typedef struct BlockRequest {
2105 union {
2106 /* Used during read, write, trim */
2107 struct {
2108 int64_t offset;
2109 int bytes;
2110 int flags;
2111 QEMUIOVector *qiov;
2112 };
2113 /* Used during ioctl */
2114 struct {
2115 int req;
2116 void *buf;
2117 };
2118 };
2119 BlockCompletionFunc *cb;
2120 void *opaque;
2121
2122 int error;
2123 } BlockRequest;
2124
2125 typedef struct BlockAIOCBCoroutine {
2126 BlockAIOCB common;
2127 BdrvChild *child;
2128 BlockRequest req;
2129 bool is_write;
2130 bool need_bh;
2131 bool *done;
2132 } BlockAIOCBCoroutine;
2133
2134 static const AIOCBInfo bdrv_em_co_aiocb_info = {
2135 .aiocb_size = sizeof(BlockAIOCBCoroutine),
2136 };
2137
2138 static void bdrv_co_complete(BlockAIOCBCoroutine *acb)
2139 {
2140 if (!acb->need_bh) {
2141 bdrv_dec_in_flight(acb->common.bs);
2142 acb->common.cb(acb->common.opaque, acb->req.error);
2143 qemu_aio_unref(acb);
2144 }
2145 }
2146
2147 static void bdrv_co_em_bh(void *opaque)
2148 {
2149 BlockAIOCBCoroutine *acb = opaque;
2150
2151 assert(!acb->need_bh);
2152 bdrv_co_complete(acb);
2153 }
2154
2155 static void bdrv_co_maybe_schedule_bh(BlockAIOCBCoroutine *acb)
2156 {
2157 acb->need_bh = false;
2158 if (acb->req.error != -EINPROGRESS) {
2159 BlockDriverState *bs = acb->common.bs;
2160
2161 aio_bh_schedule_oneshot(bdrv_get_aio_context(bs), bdrv_co_em_bh, acb);
2162 }
2163 }
2164
2165 /* Invoke bdrv_co_do_readv/bdrv_co_do_writev */
2166 static void coroutine_fn bdrv_co_do_rw(void *opaque)
2167 {
2168 BlockAIOCBCoroutine *acb = opaque;
2169
2170 if (!acb->is_write) {
2171 acb->req.error = bdrv_co_preadv(acb->child, acb->req.offset,
2172 acb->req.qiov->size, acb->req.qiov, acb->req.flags);
2173 } else {
2174 acb->req.error = bdrv_co_pwritev(acb->child, acb->req.offset,
2175 acb->req.qiov->size, acb->req.qiov, acb->req.flags);
2176 }
2177
2178 bdrv_co_complete(acb);
2179 }
2180
2181 static BlockAIOCB *bdrv_co_aio_prw_vector(BdrvChild *child,
2182 int64_t offset,
2183 QEMUIOVector *qiov,
2184 BdrvRequestFlags flags,
2185 BlockCompletionFunc *cb,
2186 void *opaque,
2187 bool is_write)
2188 {
2189 Coroutine *co;
2190 BlockAIOCBCoroutine *acb;
2191
2192 /* Matched by bdrv_co_complete's bdrv_dec_in_flight. */
2193 bdrv_inc_in_flight(child->bs);
2194
2195 acb = qemu_aio_get(&bdrv_em_co_aiocb_info, child->bs, cb, opaque);
2196 acb->child = child;
2197 acb->need_bh = true;
2198 acb->req.error = -EINPROGRESS;
2199 acb->req.offset = offset;
2200 acb->req.qiov = qiov;
2201 acb->req.flags = flags;
2202 acb->is_write = is_write;
2203
2204 co = qemu_coroutine_create(bdrv_co_do_rw, acb);
2205 qemu_coroutine_enter(co);
2206
2207 bdrv_co_maybe_schedule_bh(acb);
2208 return &acb->common;
2209 }
2210
2211 static void coroutine_fn bdrv_aio_flush_co_entry(void *opaque)
2212 {
2213 BlockAIOCBCoroutine *acb = opaque;
2214 BlockDriverState *bs = acb->common.bs;
2215
2216 acb->req.error = bdrv_co_flush(bs);
2217 bdrv_co_complete(acb);
2218 }
2219
2220 BlockAIOCB *bdrv_aio_flush(BlockDriverState *bs,
2221 BlockCompletionFunc *cb, void *opaque)
2222 {
2223 trace_bdrv_aio_flush(bs, opaque);
2224
2225 Coroutine *co;
2226 BlockAIOCBCoroutine *acb;
2227
2228 /* Matched by bdrv_co_complete's bdrv_dec_in_flight. */
2229 bdrv_inc_in_flight(bs);
2230
2231 acb = qemu_aio_get(&bdrv_em_co_aiocb_info, bs, cb, opaque);
2232 acb->need_bh = true;
2233 acb->req.error = -EINPROGRESS;
2234
2235 co = qemu_coroutine_create(bdrv_aio_flush_co_entry, acb);
2236 qemu_coroutine_enter(co);
2237
2238 bdrv_co_maybe_schedule_bh(acb);
2239 return &acb->common;
2240 }
2241
2242 void *qemu_aio_get(const AIOCBInfo *aiocb_info, BlockDriverState *bs,
2243 BlockCompletionFunc *cb, void *opaque)
2244 {
2245 BlockAIOCB *acb;
2246
2247 acb = g_malloc(aiocb_info->aiocb_size);
2248 acb->aiocb_info = aiocb_info;
2249 acb->bs = bs;
2250 acb->cb = cb;
2251 acb->opaque = opaque;
2252 acb->refcnt = 1;
2253 return acb;
2254 }
2255
2256 void qemu_aio_ref(void *p)
2257 {
2258 BlockAIOCB *acb = p;
2259 acb->refcnt++;
2260 }
2261
2262 void qemu_aio_unref(void *p)
2263 {
2264 BlockAIOCB *acb = p;
2265 assert(acb->refcnt > 0);
2266 if (--acb->refcnt == 0) {
2267 g_free(acb);
2268 }
2269 }
2270
2271 /**************************************************************/
2272 /* Coroutine block device emulation */
2273
2274 typedef struct FlushCo {
2275 BlockDriverState *bs;
2276 int ret;
2277 } FlushCo;
2278
2279
2280 static void coroutine_fn bdrv_flush_co_entry(void *opaque)
2281 {
2282 FlushCo *rwco = opaque;
2283
2284 rwco->ret = bdrv_co_flush(rwco->bs);
2285 }
2286
2287 int coroutine_fn bdrv_co_flush(BlockDriverState *bs)
2288 {
2289 int ret;
2290
2291 if (!bs || !bdrv_is_inserted(bs) || bdrv_is_read_only(bs) ||
2292 bdrv_is_sg(bs)) {
2293 return 0;
2294 }
2295
2296 bdrv_inc_in_flight(bs);
2297
2298 int current_gen = bs->write_gen;
2299
2300 /* Wait until any previous flushes are completed */
2301 while (bs->active_flush_req) {
2302 qemu_co_queue_wait(&bs->flush_queue);
2303 }
2304
2305 bs->active_flush_req = true;
2306
2307 /* Write back all layers by calling one driver function */
2308 if (bs->drv->bdrv_co_flush) {
2309 ret = bs->drv->bdrv_co_flush(bs);
2310 goto out;
2311 }
2312
2313 /* Write back cached data to the OS even with cache=unsafe */
2314 BLKDBG_EVENT(bs->file, BLKDBG_FLUSH_TO_OS);
2315 if (bs->drv->bdrv_co_flush_to_os) {
2316 ret = bs->drv->bdrv_co_flush_to_os(bs);
2317 if (ret < 0) {
2318 goto out;
2319 }
2320 }
2321
2322 /* But don't actually force it to the disk with cache=unsafe */
2323 if (bs->open_flags & BDRV_O_NO_FLUSH) {
2324 goto flush_parent;
2325 }
2326
2327 /* Check if we really need to flush anything */
2328 if (bs->flushed_gen == current_gen) {
2329 goto flush_parent;
2330 }
2331
2332 BLKDBG_EVENT(bs->file, BLKDBG_FLUSH_TO_DISK);
2333 if (bs->drv->bdrv_co_flush_to_disk) {
2334 ret = bs->drv->bdrv_co_flush_to_disk(bs);
2335 } else if (bs->drv->bdrv_aio_flush) {
2336 BlockAIOCB *acb;
2337 CoroutineIOCompletion co = {
2338 .coroutine = qemu_coroutine_self(),
2339 };
2340
2341 acb = bs->drv->bdrv_aio_flush(bs, bdrv_co_io_em_complete, &co);
2342 if (acb == NULL) {
2343 ret = -EIO;
2344 } else {
2345 qemu_coroutine_yield();
2346 ret = co.ret;
2347 }
2348 } else {
2349 /*
2350 * Some block drivers always operate in either writethrough or unsafe
2351 * mode and don't support bdrv_flush therefore. Usually qemu doesn't
2352 * know how the server works (because the behaviour is hardcoded or
2353 * depends on server-side configuration), so we can't ensure that
2354 * everything is safe on disk. Returning an error doesn't work because
2355 * that would break guests even if the server operates in writethrough
2356 * mode.
2357 *
2358 * Let's hope the user knows what he's doing.
2359 */
2360 ret = 0;
2361 }
2362
2363 if (ret < 0) {
2364 goto out;
2365 }
2366
2367 /* Now flush the underlying protocol. It will also have BDRV_O_NO_FLUSH
2368 * in the case of cache=unsafe, so there are no useless flushes.
2369 */
2370 flush_parent:
2371 ret = bs->file ? bdrv_co_flush(bs->file->bs) : 0;
2372 out:
2373 /* Notify any pending flushes that we have completed */
2374 if (ret == 0) {
2375 bs->flushed_gen = current_gen;
2376 }
2377 bs->active_flush_req = false;
2378 /* Return value is ignored - it's ok if wait queue is empty */
2379 qemu_co_queue_next(&bs->flush_queue);
2380
2381 bdrv_dec_in_flight(bs);
2382 return ret;
2383 }
2384
2385 int bdrv_flush(BlockDriverState *bs)
2386 {
2387 Coroutine *co;
2388 FlushCo flush_co = {
2389 .bs = bs,
2390 .ret = NOT_DONE,
2391 };
2392
2393 if (qemu_in_coroutine()) {
2394 /* Fast-path if already in coroutine context */
2395 bdrv_flush_co_entry(&flush_co);
2396 } else {
2397 co = qemu_coroutine_create(bdrv_flush_co_entry, &flush_co);
2398 qemu_coroutine_enter(co);
2399 BDRV_POLL_WHILE(bs, flush_co.ret == NOT_DONE);
2400 }
2401
2402 return flush_co.ret;
2403 }
2404
2405 typedef struct DiscardCo {
2406 BlockDriverState *bs;
2407 int64_t offset;
2408 int count;
2409 int ret;
2410 } DiscardCo;
2411 static void coroutine_fn bdrv_pdiscard_co_entry(void *opaque)
2412 {
2413 DiscardCo *rwco = opaque;
2414
2415 rwco->ret = bdrv_co_pdiscard(rwco->bs, rwco->offset, rwco->count);
2416 }
2417
2418 int coroutine_fn bdrv_co_pdiscard(BlockDriverState *bs, int64_t offset,
2419 int count)
2420 {
2421 BdrvTrackedRequest req;
2422 int max_pdiscard, ret;
2423 int head, tail, align;
2424
2425 if (!bs->drv) {
2426 return -ENOMEDIUM;
2427 }
2428
2429 ret = bdrv_check_byte_request(bs, offset, count);
2430 if (ret < 0) {
2431 return ret;
2432 } else if (bs->read_only) {
2433 return -EPERM;
2434 }
2435 assert(!(bs->open_flags & BDRV_O_INACTIVE));
2436
2437 /* Do nothing if disabled. */
2438 if (!(bs->open_flags & BDRV_O_UNMAP)) {
2439 return 0;
2440 }
2441
2442 if (!bs->drv->bdrv_co_pdiscard && !bs->drv->bdrv_aio_pdiscard) {
2443 return 0;
2444 }
2445
2446 /* Discard is advisory, but some devices track and coalesce
2447 * unaligned requests, so we must pass everything down rather than
2448 * round here. Still, most devices will just silently ignore
2449 * unaligned requests (by returning -ENOTSUP), so we must fragment
2450 * the request accordingly. */
2451 align = MAX(bs->bl.pdiscard_alignment, bs->bl.request_alignment);
2452 assert(align % bs->bl.request_alignment == 0);
2453 head = offset % align;
2454 tail = (offset + count) % align;
2455
2456 bdrv_inc_in_flight(bs);
2457 tracked_request_begin(&req, bs, offset, count, BDRV_TRACKED_DISCARD);
2458
2459 ret = notifier_with_return_list_notify(&bs->before_write_notifiers, &req);
2460 if (ret < 0) {
2461 goto out;
2462 }
2463
2464 max_pdiscard = QEMU_ALIGN_DOWN(MIN_NON_ZERO(bs->bl.max_pdiscard, INT_MAX),
2465 align);
2466 assert(max_pdiscard >= bs->bl.request_alignment);
2467
2468 while (count > 0) {
2469 int ret;
2470 int num = count;
2471
2472 if (head) {
2473 /* Make small requests to get to alignment boundaries. */
2474 num = MIN(count, align - head);
2475 if (!QEMU_IS_ALIGNED(num, bs->bl.request_alignment)) {
2476 num %= bs->bl.request_alignment;
2477 }
2478 head = (head + num) % align;
2479 assert(num < max_pdiscard);
2480 } else if (tail) {
2481 if (num > align) {
2482 /* Shorten the request to the last aligned cluster. */
2483 num -= tail;
2484 } else if (!QEMU_IS_ALIGNED(tail, bs->bl.request_alignment) &&
2485 tail > bs->bl.request_alignment) {
2486 tail %= bs->bl.request_alignment;
2487 num -= tail;
2488 }
2489 }
2490 /* limit request size */
2491 if (num > max_pdiscard) {
2492 num = max_pdiscard;
2493 }
2494
2495 if (bs->drv->bdrv_co_pdiscard) {
2496 ret = bs->drv->bdrv_co_pdiscard(bs, offset, num);
2497 } else {
2498 BlockAIOCB *acb;
2499 CoroutineIOCompletion co = {
2500 .coroutine = qemu_coroutine_self(),
2501 };
2502
2503 acb = bs->drv->bdrv_aio_pdiscard(bs, offset, num,
2504 bdrv_co_io_em_complete, &co);
2505 if (acb == NULL) {
2506 ret = -EIO;
2507 goto out;
2508 } else {
2509 qemu_coroutine_yield();
2510 ret = co.ret;
2511 }
2512 }
2513 if (ret && ret != -ENOTSUP) {
2514 goto out;
2515 }
2516
2517 offset += num;
2518 count -= num;
2519 }
2520 ret = 0;
2521 out:
2522 ++bs->write_gen;
2523 bdrv_set_dirty(bs, req.offset >> BDRV_SECTOR_BITS,
2524 req.bytes >> BDRV_SECTOR_BITS);
2525 tracked_request_end(&req);
2526 bdrv_dec_in_flight(bs);
2527 return ret;
2528 }
2529
2530 int bdrv_pdiscard(BlockDriverState *bs, int64_t offset, int count)
2531 {
2532 Coroutine *co;
2533 DiscardCo rwco = {
2534 .bs = bs,
2535 .offset = offset,
2536 .count = count,
2537 .ret = NOT_DONE,
2538 };
2539
2540 if (qemu_in_coroutine()) {
2541 /* Fast-path if already in coroutine context */
2542 bdrv_pdiscard_co_entry(&rwco);
2543 } else {
2544 co = qemu_coroutine_create(bdrv_pdiscard_co_entry, &rwco);
2545 qemu_coroutine_enter(co);
2546 BDRV_POLL_WHILE(bs, rwco.ret == NOT_DONE);
2547 }
2548
2549 return rwco.ret;
2550 }
2551
2552 int bdrv_co_ioctl(BlockDriverState *bs, int req, void *buf)
2553 {
2554 BlockDriver *drv = bs->drv;
2555 CoroutineIOCompletion co = {
2556 .coroutine = qemu_coroutine_self(),
2557 };
2558 BlockAIOCB *acb;
2559
2560 bdrv_inc_in_flight(bs);
2561 if (!drv || (!drv->bdrv_aio_ioctl && !drv->bdrv_co_ioctl)) {
2562 co.ret = -ENOTSUP;
2563 goto out;
2564 }
2565
2566 if (drv->bdrv_co_ioctl) {
2567 co.ret = drv->bdrv_co_ioctl(bs, req, buf);
2568 } else {
2569 acb = drv->bdrv_aio_ioctl(bs, req, buf, bdrv_co_io_em_complete, &co);
2570 if (!acb) {
2571 co.ret = -ENOTSUP;
2572 goto out;
2573 }
2574 qemu_coroutine_yield();
2575 }
2576 out:
2577 bdrv_dec_in_flight(bs);
2578 return co.ret;
2579 }
2580
2581 void *qemu_blockalign(BlockDriverState *bs, size_t size)
2582 {
2583 return qemu_memalign(bdrv_opt_mem_align(bs), size);
2584 }
2585
2586 void *qemu_blockalign0(BlockDriverState *bs, size_t size)
2587 {
2588 return memset(qemu_blockalign(bs, size), 0, size);
2589 }
2590
2591 void *qemu_try_blockalign(BlockDriverState *bs, size_t size)
2592 {
2593 size_t align = bdrv_opt_mem_align(bs);
2594
2595 /* Ensure that NULL is never returned on success */
2596 assert(align > 0);
2597 if (size == 0) {
2598 size = align;
2599 }
2600
2601 return qemu_try_memalign(align, size);
2602 }
2603
2604 void *qemu_try_blockalign0(BlockDriverState *bs, size_t size)
2605 {
2606 void *mem = qemu_try_blockalign(bs, size);
2607
2608 if (mem) {
2609 memset(mem, 0, size);
2610 }
2611
2612 return mem;
2613 }
2614
2615 /*
2616 * Check if all memory in this vector is sector aligned.
2617 */
2618 bool bdrv_qiov_is_aligned(BlockDriverState *bs, QEMUIOVector *qiov)
2619 {
2620 int i;
2621 size_t alignment = bdrv_min_mem_align(bs);
2622
2623 for (i = 0; i < qiov->niov; i++) {
2624 if ((uintptr_t) qiov->iov[i].iov_base % alignment) {
2625 return false;
2626 }
2627 if (qiov->iov[i].iov_len % alignment) {
2628 return false;
2629 }
2630 }
2631
2632 return true;
2633 }
2634
2635 void bdrv_add_before_write_notifier(BlockDriverState *bs,
2636 NotifierWithReturn *notifier)
2637 {
2638 notifier_with_return_list_add(&bs->before_write_notifiers, notifier);
2639 }
2640
2641 void bdrv_io_plug(BlockDriverState *bs)
2642 {
2643 BdrvChild *child;
2644
2645 QLIST_FOREACH(child, &bs->children, next) {
2646 bdrv_io_plug(child->bs);
2647 }
2648
2649 if (bs->io_plugged++ == 0) {
2650 BlockDriver *drv = bs->drv;
2651 if (drv && drv->bdrv_io_plug) {
2652 drv->bdrv_io_plug(bs);
2653 }
2654 }
2655 }
2656
2657 void bdrv_io_unplug(BlockDriverState *bs)
2658 {
2659 BdrvChild *child;
2660
2661 assert(bs->io_plugged);
2662 if (--bs->io_plugged == 0) {
2663 BlockDriver *drv = bs->drv;
2664 if (drv && drv->bdrv_io_unplug) {
2665 drv->bdrv_io_unplug(bs);
2666 }
2667 }
2668
2669 QLIST_FOREACH(child, &bs->children, next) {
2670 bdrv_io_unplug(child->bs);
2671 }
2672 }