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/aio-wait.h"
29#include "block/blockjob.h"
30#include "block/blockjob_int.h"
31#include "block/block_int.h"
32#include "qemu/cutils.h"
33#include "qapi/error.h"
34#include "qemu/error-report.h"
35#include "qemu/main-loop.h"
36
37#define NOT_DONE 0x7fffffff /* used while emulated sync operation in progress */
38
39/* Maximum bounce buffer for copy-on-read and write zeroes, in bytes */
40#define MAX_BOUNCE_BUFFER (32768 << BDRV_SECTOR_BITS)
41
42static void bdrv_parent_cb_resize(BlockDriverState *bs);
43static int coroutine_fn bdrv_co_do_pwrite_zeroes(BlockDriverState *bs,
44 int64_t offset, int bytes, BdrvRequestFlags flags);
45
46static void bdrv_parent_drained_begin(BlockDriverState *bs, BdrvChild *ignore,
47 bool ignore_bds_parents)
48{
49 BdrvChild *c, *next;
50
51 QLIST_FOREACH_SAFE(c, &bs->parents, next_parent, next) {
52 if (c == ignore || (ignore_bds_parents && c->role->parent_is_bds)) {
53 continue;
54 }
55 bdrv_parent_drained_begin_single(c, false);
56 }
57}
58
59static void bdrv_parent_drained_end_single_no_poll(BdrvChild *c,
60 int *drained_end_counter)
61{
62 assert(c->parent_quiesce_counter > 0);
63 c->parent_quiesce_counter--;
64 if (c->role->drained_end) {
65 c->role->drained_end(c, drained_end_counter);
66 }
67}
68
69void bdrv_parent_drained_end_single(BdrvChild *c)
70{
71 int drained_end_counter = 0;
72 bdrv_parent_drained_end_single_no_poll(c, &drained_end_counter);
73 BDRV_POLL_WHILE(c->bs, atomic_read(&drained_end_counter) > 0);
74}
75
76static void bdrv_parent_drained_end(BlockDriverState *bs, BdrvChild *ignore,
77 bool ignore_bds_parents,
78 int *drained_end_counter)
79{
80 BdrvChild *c;
81
82 QLIST_FOREACH(c, &bs->parents, next_parent) {
83 if (c == ignore || (ignore_bds_parents && c->role->parent_is_bds)) {
84 continue;
85 }
86 bdrv_parent_drained_end_single_no_poll(c, drained_end_counter);
87 }
88}
89
90static bool bdrv_parent_drained_poll_single(BdrvChild *c)
91{
92 if (c->role->drained_poll) {
93 return c->role->drained_poll(c);
94 }
95 return false;
96}
97
98static bool bdrv_parent_drained_poll(BlockDriverState *bs, BdrvChild *ignore,
99 bool ignore_bds_parents)
100{
101 BdrvChild *c, *next;
102 bool busy = false;
103
104 QLIST_FOREACH_SAFE(c, &bs->parents, next_parent, next) {
105 if (c == ignore || (ignore_bds_parents && c->role->parent_is_bds)) {
106 continue;
107 }
108 busy |= bdrv_parent_drained_poll_single(c);
109 }
110
111 return busy;
112}
113
114void bdrv_parent_drained_begin_single(BdrvChild *c, bool poll)
115{
116 c->parent_quiesce_counter++;
117 if (c->role->drained_begin) {
118 c->role->drained_begin(c);
119 }
120 if (poll) {
121 BDRV_POLL_WHILE(c->bs, bdrv_parent_drained_poll_single(c));
122 }
123}
124
125static void bdrv_merge_limits(BlockLimits *dst, const BlockLimits *src)
126{
127 dst->opt_transfer = MAX(dst->opt_transfer, src->opt_transfer);
128 dst->max_transfer = MIN_NON_ZERO(dst->max_transfer, src->max_transfer);
129 dst->opt_mem_alignment = MAX(dst->opt_mem_alignment,
130 src->opt_mem_alignment);
131 dst->min_mem_alignment = MAX(dst->min_mem_alignment,
132 src->min_mem_alignment);
133 dst->max_iov = MIN_NON_ZERO(dst->max_iov, src->max_iov);
134}
135
136void bdrv_refresh_limits(BlockDriverState *bs, Error **errp)
137{
138 BlockDriver *drv = bs->drv;
139 Error *local_err = NULL;
140
141 memset(&bs->bl, 0, sizeof(bs->bl));
142
143 if (!drv) {
144 return;
145 }
146
147 /* Default alignment based on whether driver has byte interface */
148 bs->bl.request_alignment = (drv->bdrv_co_preadv ||
149 drv->bdrv_aio_preadv ||
150 drv->bdrv_co_preadv_part) ? 1 : 512;
151
152 /* Take some limits from the children as a default */
153 if (bs->file) {
154 bdrv_refresh_limits(bs->file->bs, &local_err);
155 if (local_err) {
156 error_propagate(errp, local_err);
157 return;
158 }
159 bdrv_merge_limits(&bs->bl, &bs->file->bs->bl);
160 } else {
161 bs->bl.min_mem_alignment = 512;
162 bs->bl.opt_mem_alignment = getpagesize();
163
164 /* Safe default since most protocols use readv()/writev()/etc */
165 bs->bl.max_iov = IOV_MAX;
166 }
167
168 if (bs->backing) {
169 bdrv_refresh_limits(bs->backing->bs, &local_err);
170 if (local_err) {
171 error_propagate(errp, local_err);
172 return;
173 }
174 bdrv_merge_limits(&bs->bl, &bs->backing->bs->bl);
175 }
176
177 /* Then let the driver override it */
178 if (drv->bdrv_refresh_limits) {
179 drv->bdrv_refresh_limits(bs, errp);
180 }
181}
182
183/**
184 * The copy-on-read flag is actually a reference count so multiple users may
185 * use the feature without worrying about clobbering its previous state.
186 * Copy-on-read stays enabled until all users have called to disable it.
187 */
188void bdrv_enable_copy_on_read(BlockDriverState *bs)
189{
190 atomic_inc(&bs->copy_on_read);
191}
192
193void bdrv_disable_copy_on_read(BlockDriverState *bs)
194{
195 int old = atomic_fetch_dec(&bs->copy_on_read);
196 assert(old >= 1);
197}
198
199typedef struct {
200 Coroutine *co;
201 BlockDriverState *bs;
202 bool done;
203 bool begin;
204 bool recursive;
205 bool poll;
206 BdrvChild *parent;
207 bool ignore_bds_parents;
208 int *drained_end_counter;
209} BdrvCoDrainData;
210
211static void coroutine_fn bdrv_drain_invoke_entry(void *opaque)
212{
213 BdrvCoDrainData *data = opaque;
214 BlockDriverState *bs = data->bs;
215
216 if (data->begin) {
217 bs->drv->bdrv_co_drain_begin(bs);
218 } else {
219 bs->drv->bdrv_co_drain_end(bs);
220 }
221
222 /* Set data->done and decrement drained_end_counter before bdrv_wakeup() */
223 atomic_mb_set(&data->done, true);
224 if (!data->begin) {
225 atomic_dec(data->drained_end_counter);
226 }
227 bdrv_dec_in_flight(bs);
228
229 g_free(data);
230}
231
232/* Recursively call BlockDriver.bdrv_co_drain_begin/end callbacks */
233static void bdrv_drain_invoke(BlockDriverState *bs, bool begin,
234 int *drained_end_counter)
235{
236 BdrvCoDrainData *data;
237
238 if (!bs->drv || (begin && !bs->drv->bdrv_co_drain_begin) ||
239 (!begin && !bs->drv->bdrv_co_drain_end)) {
240 return;
241 }
242
243 data = g_new(BdrvCoDrainData, 1);
244 *data = (BdrvCoDrainData) {
245 .bs = bs,
246 .done = false,
247 .begin = begin,
248 .drained_end_counter = drained_end_counter,
249 };
250
251 if (!begin) {
252 atomic_inc(drained_end_counter);
253 }
254
255 /* Make sure the driver callback completes during the polling phase for
256 * drain_begin. */
257 bdrv_inc_in_flight(bs);
258 data->co = qemu_coroutine_create(bdrv_drain_invoke_entry, data);
259 aio_co_schedule(bdrv_get_aio_context(bs), data->co);
260}
261
262/* Returns true if BDRV_POLL_WHILE() should go into a blocking aio_poll() */
263bool bdrv_drain_poll(BlockDriverState *bs, bool recursive,
264 BdrvChild *ignore_parent, bool ignore_bds_parents)
265{
266 BdrvChild *child, *next;
267
268 if (bdrv_parent_drained_poll(bs, ignore_parent, ignore_bds_parents)) {
269 return true;
270 }
271
272 if (atomic_read(&bs->in_flight)) {
273 return true;
274 }
275
276 if (recursive) {
277 assert(!ignore_bds_parents);
278 QLIST_FOREACH_SAFE(child, &bs->children, next, next) {
279 if (bdrv_drain_poll(child->bs, recursive, child, false)) {
280 return true;
281 }
282 }
283 }
284
285 return false;
286}
287
288static bool bdrv_drain_poll_top_level(BlockDriverState *bs, bool recursive,
289 BdrvChild *ignore_parent)
290{
291 return bdrv_drain_poll(bs, recursive, ignore_parent, false);
292}
293
294static void bdrv_do_drained_begin(BlockDriverState *bs, bool recursive,
295 BdrvChild *parent, bool ignore_bds_parents,
296 bool poll);
297static void bdrv_do_drained_end(BlockDriverState *bs, bool recursive,
298 BdrvChild *parent, bool ignore_bds_parents,
299 int *drained_end_counter);
300
301static void bdrv_co_drain_bh_cb(void *opaque)
302{
303 BdrvCoDrainData *data = opaque;
304 Coroutine *co = data->co;
305 BlockDriverState *bs = data->bs;
306
307 if (bs) {
308 AioContext *ctx = bdrv_get_aio_context(bs);
309 AioContext *co_ctx = qemu_coroutine_get_aio_context(co);
310
311 /*
312 * When the coroutine yielded, the lock for its home context was
313 * released, so we need to re-acquire it here. If it explicitly
314 * acquired a different context, the lock is still held and we don't
315 * want to lock it a second time (or AIO_WAIT_WHILE() would hang).
316 */
317 if (ctx == co_ctx) {
318 aio_context_acquire(ctx);
319 }
320 bdrv_dec_in_flight(bs);
321 if (data->begin) {
322 assert(!data->drained_end_counter);
323 bdrv_do_drained_begin(bs, data->recursive, data->parent,
324 data->ignore_bds_parents, data->poll);
325 } else {
326 assert(!data->poll);
327 bdrv_do_drained_end(bs, data->recursive, data->parent,
328 data->ignore_bds_parents,
329 data->drained_end_counter);
330 }
331 if (ctx == co_ctx) {
332 aio_context_release(ctx);
333 }
334 } else {
335 assert(data->begin);
336 bdrv_drain_all_begin();
337 }
338
339 data->done = true;
340 aio_co_wake(co);
341}
342
343static void coroutine_fn bdrv_co_yield_to_drain(BlockDriverState *bs,
344 bool begin, bool recursive,
345 BdrvChild *parent,
346 bool ignore_bds_parents,
347 bool poll,
348 int *drained_end_counter)
349{
350 BdrvCoDrainData data;
351
352 /* Calling bdrv_drain() from a BH ensures the current coroutine yields and
353 * other coroutines run if they were queued by aio_co_enter(). */
354
355 assert(qemu_in_coroutine());
356 data = (BdrvCoDrainData) {
357 .co = qemu_coroutine_self(),
358 .bs = bs,
359 .done = false,
360 .begin = begin,
361 .recursive = recursive,
362 .parent = parent,
363 .ignore_bds_parents = ignore_bds_parents,
364 .poll = poll,
365 .drained_end_counter = drained_end_counter,
366 };
367
368 if (bs) {
369 bdrv_inc_in_flight(bs);
370 }
371 aio_bh_schedule_oneshot(bdrv_get_aio_context(bs),
372 bdrv_co_drain_bh_cb, &data);
373
374 qemu_coroutine_yield();
375 /* If we are resumed from some other event (such as an aio completion or a
376 * timer callback), it is a bug in the caller that should be fixed. */
377 assert(data.done);
378}
379
380void bdrv_do_drained_begin_quiesce(BlockDriverState *bs,
381 BdrvChild *parent, bool ignore_bds_parents)
382{
383 assert(!qemu_in_coroutine());
384
385 /* Stop things in parent-to-child order */
386 if (atomic_fetch_inc(&bs->quiesce_counter) == 0) {
387 aio_disable_external(bdrv_get_aio_context(bs));
388 }
389
390 bdrv_parent_drained_begin(bs, parent, ignore_bds_parents);
391 bdrv_drain_invoke(bs, true, NULL);
392}
393
394static void bdrv_do_drained_begin(BlockDriverState *bs, bool recursive,
395 BdrvChild *parent, bool ignore_bds_parents,
396 bool poll)
397{
398 BdrvChild *child, *next;
399
400 if (qemu_in_coroutine()) {
401 bdrv_co_yield_to_drain(bs, true, recursive, parent, ignore_bds_parents,
402 poll, NULL);
403 return;
404 }
405
406 bdrv_do_drained_begin_quiesce(bs, parent, ignore_bds_parents);
407
408 if (recursive) {
409 assert(!ignore_bds_parents);
410 bs->recursive_quiesce_counter++;
411 QLIST_FOREACH_SAFE(child, &bs->children, next, next) {
412 bdrv_do_drained_begin(child->bs, true, child, ignore_bds_parents,
413 false);
414 }
415 }
416
417 /*
418 * Wait for drained requests to finish.
419 *
420 * Calling BDRV_POLL_WHILE() only once for the top-level node is okay: The
421 * call is needed so things in this AioContext can make progress even
422 * though we don't return to the main AioContext loop - this automatically
423 * includes other nodes in the same AioContext and therefore all child
424 * nodes.
425 */
426 if (poll) {
427 assert(!ignore_bds_parents);
428 BDRV_POLL_WHILE(bs, bdrv_drain_poll_top_level(bs, recursive, parent));
429 }
430}
431
432void bdrv_drained_begin(BlockDriverState *bs)
433{
434 bdrv_do_drained_begin(bs, false, NULL, false, true);
435}
436
437void bdrv_subtree_drained_begin(BlockDriverState *bs)
438{
439 bdrv_do_drained_begin(bs, true, NULL, false, true);
440}
441
442/**
443 * This function does not poll, nor must any of its recursively called
444 * functions. The *drained_end_counter pointee will be incremented
445 * once for every background operation scheduled, and decremented once
446 * the operation settles. Therefore, the pointer must remain valid
447 * until the pointee reaches 0. That implies that whoever sets up the
448 * pointee has to poll until it is 0.
449 *
450 * We use atomic operations to access *drained_end_counter, because
451 * (1) when called from bdrv_set_aio_context_ignore(), the subgraph of
452 * @bs may contain nodes in different AioContexts,
453 * (2) bdrv_drain_all_end() uses the same counter for all nodes,
454 * regardless of which AioContext they are in.
455 */
456static void bdrv_do_drained_end(BlockDriverState *bs, bool recursive,
457 BdrvChild *parent, bool ignore_bds_parents,
458 int *drained_end_counter)
459{
460 BdrvChild *child;
461 int old_quiesce_counter;
462
463 assert(drained_end_counter != NULL);
464
465 if (qemu_in_coroutine()) {
466 bdrv_co_yield_to_drain(bs, false, recursive, parent, ignore_bds_parents,
467 false, drained_end_counter);
468 return;
469 }
470 assert(bs->quiesce_counter > 0);
471
472 /* Re-enable things in child-to-parent order */
473 bdrv_drain_invoke(bs, false, drained_end_counter);
474 bdrv_parent_drained_end(bs, parent, ignore_bds_parents,
475 drained_end_counter);
476
477 old_quiesce_counter = atomic_fetch_dec(&bs->quiesce_counter);
478 if (old_quiesce_counter == 1) {
479 aio_enable_external(bdrv_get_aio_context(bs));
480 }
481
482 if (recursive) {
483 assert(!ignore_bds_parents);
484 bs->recursive_quiesce_counter--;
485 QLIST_FOREACH(child, &bs->children, next) {
486 bdrv_do_drained_end(child->bs, true, child, ignore_bds_parents,
487 drained_end_counter);
488 }
489 }
490}
491
492void bdrv_drained_end(BlockDriverState *bs)
493{
494 int drained_end_counter = 0;
495 bdrv_do_drained_end(bs, false, NULL, false, &drained_end_counter);
496 BDRV_POLL_WHILE(bs, atomic_read(&drained_end_counter) > 0);
497}
498
499void bdrv_drained_end_no_poll(BlockDriverState *bs, int *drained_end_counter)
500{
501 bdrv_do_drained_end(bs, false, NULL, false, drained_end_counter);
502}
503
504void bdrv_subtree_drained_end(BlockDriverState *bs)
505{
506 int drained_end_counter = 0;
507 bdrv_do_drained_end(bs, true, NULL, false, &drained_end_counter);
508 BDRV_POLL_WHILE(bs, atomic_read(&drained_end_counter) > 0);
509}
510
511void bdrv_apply_subtree_drain(BdrvChild *child, BlockDriverState *new_parent)
512{
513 int i;
514
515 for (i = 0; i < new_parent->recursive_quiesce_counter; i++) {
516 bdrv_do_drained_begin(child->bs, true, child, false, true);
517 }
518}
519
520void bdrv_unapply_subtree_drain(BdrvChild *child, BlockDriverState *old_parent)
521{
522 int drained_end_counter = 0;
523 int i;
524
525 for (i = 0; i < old_parent->recursive_quiesce_counter; i++) {
526 bdrv_do_drained_end(child->bs, true, child, false,
527 &drained_end_counter);
528 }
529
530 BDRV_POLL_WHILE(child->bs, atomic_read(&drained_end_counter) > 0);
531}
532
533/*
534 * Wait for pending requests to complete on a single BlockDriverState subtree,
535 * and suspend block driver's internal I/O until next request arrives.
536 *
537 * Note that unlike bdrv_drain_all(), the caller must hold the BlockDriverState
538 * AioContext.
539 */
540void coroutine_fn bdrv_co_drain(BlockDriverState *bs)
541{
542 assert(qemu_in_coroutine());
543 bdrv_drained_begin(bs);
544 bdrv_drained_end(bs);
545}
546
547void bdrv_drain(BlockDriverState *bs)
548{
549 bdrv_drained_begin(bs);
550 bdrv_drained_end(bs);
551}
552
553static void bdrv_drain_assert_idle(BlockDriverState *bs)
554{
555 BdrvChild *child, *next;
556
557 assert(atomic_read(&bs->in_flight) == 0);
558 QLIST_FOREACH_SAFE(child, &bs->children, next, next) {
559 bdrv_drain_assert_idle(child->bs);
560 }
561}
562
563unsigned int bdrv_drain_all_count = 0;
564
565static bool bdrv_drain_all_poll(void)
566{
567 BlockDriverState *bs = NULL;
568 bool result = false;
569
570 /* bdrv_drain_poll() can't make changes to the graph and we are holding the
571 * main AioContext lock, so iterating bdrv_next_all_states() is safe. */
572 while ((bs = bdrv_next_all_states(bs))) {
573 AioContext *aio_context = bdrv_get_aio_context(bs);
574 aio_context_acquire(aio_context);
575 result |= bdrv_drain_poll(bs, false, NULL, true);
576 aio_context_release(aio_context);
577 }
578
579 return result;
580}
581
582/*
583 * Wait for pending requests to complete across all BlockDriverStates
584 *
585 * This function does not flush data to disk, use bdrv_flush_all() for that
586 * after calling this function.
587 *
588 * This pauses all block jobs and disables external clients. It must
589 * be paired with bdrv_drain_all_end().
590 *
591 * NOTE: no new block jobs or BlockDriverStates can be created between
592 * the bdrv_drain_all_begin() and bdrv_drain_all_end() calls.
593 */
594void bdrv_drain_all_begin(void)
595{
596 BlockDriverState *bs = NULL;
597
598 if (qemu_in_coroutine()) {
599 bdrv_co_yield_to_drain(NULL, true, false, NULL, true, true, NULL);
600 return;
601 }
602
603 /* AIO_WAIT_WHILE() with a NULL context can only be called from the main
604 * loop AioContext, so make sure we're in the main context. */
605 assert(qemu_get_current_aio_context() == qemu_get_aio_context());
606 assert(bdrv_drain_all_count < INT_MAX);
607 bdrv_drain_all_count++;
608
609 /* Quiesce all nodes, without polling in-flight requests yet. The graph
610 * cannot change during this loop. */
611 while ((bs = bdrv_next_all_states(bs))) {
612 AioContext *aio_context = bdrv_get_aio_context(bs);
613
614 aio_context_acquire(aio_context);
615 bdrv_do_drained_begin(bs, false, NULL, true, false);
616 aio_context_release(aio_context);
617 }
618
619 /* Now poll the in-flight requests */
620 AIO_WAIT_WHILE(NULL, bdrv_drain_all_poll());
621
622 while ((bs = bdrv_next_all_states(bs))) {
623 bdrv_drain_assert_idle(bs);
624 }
625}
626
627void bdrv_drain_all_end(void)
628{
629 BlockDriverState *bs = NULL;
630 int drained_end_counter = 0;
631
632 while ((bs = bdrv_next_all_states(bs))) {
633 AioContext *aio_context = bdrv_get_aio_context(bs);
634
635 aio_context_acquire(aio_context);
636 bdrv_do_drained_end(bs, false, NULL, true, &drained_end_counter);
637 aio_context_release(aio_context);
638 }
639
640 assert(qemu_get_current_aio_context() == qemu_get_aio_context());
641 AIO_WAIT_WHILE(NULL, atomic_read(&drained_end_counter) > 0);
642
643 assert(bdrv_drain_all_count > 0);
644 bdrv_drain_all_count--;
645}
646
647void bdrv_drain_all(void)
648{
649 bdrv_drain_all_begin();
650 bdrv_drain_all_end();
651}
652
653/**
654 * Remove an active request from the tracked requests list
655 *
656 * This function should be called when a tracked request is completing.
657 */
658static void tracked_request_end(BdrvTrackedRequest *req)
659{
660 if (req->serialising) {
661 atomic_dec(&req->bs->serialising_in_flight);
662 }
663
664 qemu_co_mutex_lock(&req->bs->reqs_lock);
665 QLIST_REMOVE(req, list);
666 qemu_co_queue_restart_all(&req->wait_queue);
667 qemu_co_mutex_unlock(&req->bs->reqs_lock);
668}
669
670/**
671 * Add an active request to the tracked requests list
672 */
673static void tracked_request_begin(BdrvTrackedRequest *req,
674 BlockDriverState *bs,
675 int64_t offset,
676 uint64_t bytes,
677 enum BdrvTrackedRequestType type)
678{
679 assert(bytes <= INT64_MAX && offset <= INT64_MAX - bytes);
680
681 *req = (BdrvTrackedRequest){
682 .bs = bs,
683 .offset = offset,
684 .bytes = bytes,
685 .type = type,
686 .co = qemu_coroutine_self(),
687 .serialising = false,
688 .overlap_offset = offset,
689 .overlap_bytes = bytes,
690 };
691
692 qemu_co_queue_init(&req->wait_queue);
693
694 qemu_co_mutex_lock(&bs->reqs_lock);
695 QLIST_INSERT_HEAD(&bs->tracked_requests, req, list);
696 qemu_co_mutex_unlock(&bs->reqs_lock);
697}
698
699static void mark_request_serialising(BdrvTrackedRequest *req, uint64_t align)
700{
701 int64_t overlap_offset = req->offset & ~(align - 1);
702 uint64_t overlap_bytes = ROUND_UP(req->offset + req->bytes, align)
703 - overlap_offset;
704
705 if (!req->serialising) {
706 atomic_inc(&req->bs->serialising_in_flight);
707 req->serialising = true;
708 }
709
710 req->overlap_offset = MIN(req->overlap_offset, overlap_offset);
711 req->overlap_bytes = MAX(req->overlap_bytes, overlap_bytes);
712}
713
714static bool is_request_serialising_and_aligned(BdrvTrackedRequest *req)
715{
716 /*
717 * If the request is serialising, overlap_offset and overlap_bytes are set,
718 * so we can check if the request is aligned. Otherwise, don't care and
719 * return false.
720 */
721
722 return req->serialising && (req->offset == req->overlap_offset) &&
723 (req->bytes == req->overlap_bytes);
724}
725
726/**
727 * Round a region to cluster boundaries
728 */
729void bdrv_round_to_clusters(BlockDriverState *bs,
730 int64_t offset, int64_t bytes,
731 int64_t *cluster_offset,
732 int64_t *cluster_bytes)
733{
734 BlockDriverInfo bdi;
735
736 if (bdrv_get_info(bs, &bdi) < 0 || bdi.cluster_size == 0) {
737 *cluster_offset = offset;
738 *cluster_bytes = bytes;
739 } else {
740 int64_t c = bdi.cluster_size;
741 *cluster_offset = QEMU_ALIGN_DOWN(offset, c);
742 *cluster_bytes = QEMU_ALIGN_UP(offset - *cluster_offset + bytes, c);
743 }
744}
745
746static int bdrv_get_cluster_size(BlockDriverState *bs)
747{
748 BlockDriverInfo bdi;
749 int ret;
750
751 ret = bdrv_get_info(bs, &bdi);
752 if (ret < 0 || bdi.cluster_size == 0) {
753 return bs->bl.request_alignment;
754 } else {
755 return bdi.cluster_size;
756 }
757}
758
759static bool tracked_request_overlaps(BdrvTrackedRequest *req,
760 int64_t offset, uint64_t bytes)
761{
762 /* aaaa bbbb */
763 if (offset >= req->overlap_offset + req->overlap_bytes) {
764 return false;
765 }
766 /* bbbb aaaa */
767 if (req->overlap_offset >= offset + bytes) {
768 return false;
769 }
770 return true;
771}
772
773void bdrv_inc_in_flight(BlockDriverState *bs)
774{
775 atomic_inc(&bs->in_flight);
776}
777
778void bdrv_wakeup(BlockDriverState *bs)
779{
780 aio_wait_kick();
781}
782
783void bdrv_dec_in_flight(BlockDriverState *bs)
784{
785 atomic_dec(&bs->in_flight);
786 bdrv_wakeup(bs);
787}
788
789static bool coroutine_fn wait_serialising_requests(BdrvTrackedRequest *self)
790{
791 BlockDriverState *bs = self->bs;
792 BdrvTrackedRequest *req;
793 bool retry;
794 bool waited = false;
795
796 if (!atomic_read(&bs->serialising_in_flight)) {
797 return false;
798 }
799
800 do {
801 retry = false;
802 qemu_co_mutex_lock(&bs->reqs_lock);
803 QLIST_FOREACH(req, &bs->tracked_requests, list) {
804 if (req == self || (!req->serialising && !self->serialising)) {
805 continue;
806 }
807 if (tracked_request_overlaps(req, self->overlap_offset,
808 self->overlap_bytes))
809 {
810 /* Hitting this means there was a reentrant request, for
811 * example, a block driver issuing nested requests. This must
812 * never happen since it means deadlock.
813 */
814 assert(qemu_coroutine_self() != req->co);
815
816 /* If the request is already (indirectly) waiting for us, or
817 * will wait for us as soon as it wakes up, then just go on
818 * (instead of producing a deadlock in the former case). */
819 if (!req->waiting_for) {
820 self->waiting_for = req;
821 qemu_co_queue_wait(&req->wait_queue, &bs->reqs_lock);
822 self->waiting_for = NULL;
823 retry = true;
824 waited = true;
825 break;
826 }
827 }
828 }
829 qemu_co_mutex_unlock(&bs->reqs_lock);
830 } while (retry);
831
832 return waited;
833}
834
835static int bdrv_check_byte_request(BlockDriverState *bs, int64_t offset,
836 size_t size)
837{
838 if (size > BDRV_REQUEST_MAX_BYTES) {
839 return -EIO;
840 }
841
842 if (!bdrv_is_inserted(bs)) {
843 return -ENOMEDIUM;
844 }
845
846 if (offset < 0) {
847 return -EIO;
848 }
849
850 return 0;
851}
852
853typedef struct RwCo {
854 BdrvChild *child;
855 int64_t offset;
856 QEMUIOVector *qiov;
857 bool is_write;
858 int ret;
859 BdrvRequestFlags flags;
860} RwCo;
861
862static void coroutine_fn bdrv_rw_co_entry(void *opaque)
863{
864 RwCo *rwco = opaque;
865
866 if (!rwco->is_write) {
867 rwco->ret = bdrv_co_preadv(rwco->child, rwco->offset,
868 rwco->qiov->size, rwco->qiov,
869 rwco->flags);
870 } else {
871 rwco->ret = bdrv_co_pwritev(rwco->child, rwco->offset,
872 rwco->qiov->size, rwco->qiov,
873 rwco->flags);
874 }
875 aio_wait_kick();
876}
877
878/*
879 * Process a vectored synchronous request using coroutines
880 */
881static int bdrv_prwv_co(BdrvChild *child, int64_t offset,
882 QEMUIOVector *qiov, bool is_write,
883 BdrvRequestFlags flags)
884{
885 Coroutine *co;
886 RwCo rwco = {
887 .child = child,
888 .offset = offset,
889 .qiov = qiov,
890 .is_write = is_write,
891 .ret = NOT_DONE,
892 .flags = flags,
893 };
894
895 if (qemu_in_coroutine()) {
896 /* Fast-path if already in coroutine context */
897 bdrv_rw_co_entry(&rwco);
898 } else {
899 co = qemu_coroutine_create(bdrv_rw_co_entry, &rwco);
900 bdrv_coroutine_enter(child->bs, co);
901 BDRV_POLL_WHILE(child->bs, rwco.ret == NOT_DONE);
902 }
903 return rwco.ret;
904}
905
906int bdrv_pwrite_zeroes(BdrvChild *child, int64_t offset,
907 int bytes, BdrvRequestFlags flags)
908{
909 QEMUIOVector qiov = QEMU_IOVEC_INIT_BUF(qiov, NULL, bytes);
910
911 return bdrv_prwv_co(child, offset, &qiov, true,
912 BDRV_REQ_ZERO_WRITE | flags);
913}
914
915/*
916 * Completely zero out a block device with the help of bdrv_pwrite_zeroes.
917 * The operation is sped up by checking the block status and only writing
918 * zeroes to the device if they currently do not return zeroes. Optional
919 * flags are passed through to bdrv_pwrite_zeroes (e.g. BDRV_REQ_MAY_UNMAP,
920 * BDRV_REQ_FUA).
921 *
922 * Returns < 0 on error, 0 on success. For error codes see bdrv_write().
923 */
924int bdrv_make_zero(BdrvChild *child, BdrvRequestFlags flags)
925{
926 int ret;
927 int64_t target_size, bytes, offset = 0;
928 BlockDriverState *bs = child->bs;
929
930 target_size = bdrv_getlength(bs);
931 if (target_size < 0) {
932 return target_size;
933 }
934
935 for (;;) {
936 bytes = MIN(target_size - offset, BDRV_REQUEST_MAX_BYTES);
937 if (bytes <= 0) {
938 return 0;
939 }
940 ret = bdrv_block_status(bs, offset, bytes, &bytes, NULL, NULL);
941 if (ret < 0) {
942 return ret;
943 }
944 if (ret & BDRV_BLOCK_ZERO) {
945 offset += bytes;
946 continue;
947 }
948 ret = bdrv_pwrite_zeroes(child, offset, bytes, flags);
949 if (ret < 0) {
950 return ret;
951 }
952 offset += bytes;
953 }
954}
955
956int bdrv_preadv(BdrvChild *child, int64_t offset, QEMUIOVector *qiov)
957{
958 int ret;
959
960 ret = bdrv_prwv_co(child, offset, qiov, false, 0);
961 if (ret < 0) {
962 return ret;
963 }
964
965 return qiov->size;
966}
967
968/* See bdrv_pwrite() for the return codes */
969int bdrv_pread(BdrvChild *child, int64_t offset, void *buf, int bytes)
970{
971 QEMUIOVector qiov = QEMU_IOVEC_INIT_BUF(qiov, buf, bytes);
972
973 if (bytes < 0) {
974 return -EINVAL;
975 }
976
977 return bdrv_preadv(child, offset, &qiov);
978}
979
980int bdrv_pwritev(BdrvChild *child, int64_t offset, QEMUIOVector *qiov)
981{
982 int ret;
983
984 ret = bdrv_prwv_co(child, offset, qiov, true, 0);
985 if (ret < 0) {
986 return ret;
987 }
988
989 return qiov->size;
990}
991
992/* Return no. of bytes on success or < 0 on error. Important errors are:
993 -EIO generic I/O error (may happen for all errors)
994 -ENOMEDIUM No media inserted.
995 -EINVAL Invalid offset or number of bytes
996 -EACCES Trying to write a read-only device
997*/
998int bdrv_pwrite(BdrvChild *child, int64_t offset, const void *buf, int bytes)
999{
1000 QEMUIOVector qiov = QEMU_IOVEC_INIT_BUF(qiov, buf, bytes);
1001
1002 if (bytes < 0) {
1003 return -EINVAL;
1004 }
1005
1006 return bdrv_pwritev(child, offset, &qiov);
1007}
1008
1009/*
1010 * Writes to the file and ensures that no writes are reordered across this
1011 * request (acts as a barrier)
1012 *
1013 * Returns 0 on success, -errno in error cases.
1014 */
1015int bdrv_pwrite_sync(BdrvChild *child, int64_t offset,
1016 const void *buf, int count)
1017{
1018 int ret;
1019
1020 ret = bdrv_pwrite(child, offset, buf, count);
1021 if (ret < 0) {
1022 return ret;
1023 }
1024
1025 ret = bdrv_flush(child->bs);
1026 if (ret < 0) {
1027 return ret;
1028 }
1029
1030 return 0;
1031}
1032
1033typedef struct CoroutineIOCompletion {
1034 Coroutine *coroutine;
1035 int ret;
1036} CoroutineIOCompletion;
1037
1038static void bdrv_co_io_em_complete(void *opaque, int ret)
1039{
1040 CoroutineIOCompletion *co = opaque;
1041
1042 co->ret = ret;
1043 aio_co_wake(co->coroutine);
1044}
1045
1046static int coroutine_fn bdrv_driver_preadv(BlockDriverState *bs,
1047 uint64_t offset, uint64_t bytes,
1048 QEMUIOVector *qiov,
1049 size_t qiov_offset, int flags)
1050{
1051 BlockDriver *drv = bs->drv;
1052 int64_t sector_num;
1053 unsigned int nb_sectors;
1054 QEMUIOVector local_qiov;
1055 int ret;
1056
1057 assert(!(flags & ~BDRV_REQ_MASK));
1058 assert(!(flags & BDRV_REQ_NO_FALLBACK));
1059
1060 if (!drv) {
1061 return -ENOMEDIUM;
1062 }
1063
1064 if (drv->bdrv_co_preadv_part) {
1065 return drv->bdrv_co_preadv_part(bs, offset, bytes, qiov, qiov_offset,
1066 flags);
1067 }
1068
1069 if (qiov_offset > 0 || bytes != qiov->size) {
1070 qemu_iovec_init_slice(&local_qiov, qiov, qiov_offset, bytes);
1071 qiov = &local_qiov;
1072 }
1073
1074 if (drv->bdrv_co_preadv) {
1075 ret = drv->bdrv_co_preadv(bs, offset, bytes, qiov, flags);
1076 goto out;
1077 }
1078
1079 if (drv->bdrv_aio_preadv) {
1080 BlockAIOCB *acb;
1081 CoroutineIOCompletion co = {
1082 .coroutine = qemu_coroutine_self(),
1083 };
1084
1085 acb = drv->bdrv_aio_preadv(bs, offset, bytes, qiov, flags,
1086 bdrv_co_io_em_complete, &co);
1087 if (acb == NULL) {
1088 ret = -EIO;
1089 goto out;
1090 } else {
1091 qemu_coroutine_yield();
1092 ret = co.ret;
1093 goto out;
1094 }
1095 }
1096
1097 sector_num = offset >> BDRV_SECTOR_BITS;
1098 nb_sectors = bytes >> BDRV_SECTOR_BITS;
1099
1100 assert((offset & (BDRV_SECTOR_SIZE - 1)) == 0);
1101 assert((bytes & (BDRV_SECTOR_SIZE - 1)) == 0);
1102 assert(bytes <= BDRV_REQUEST_MAX_BYTES);
1103 assert(drv->bdrv_co_readv);
1104
1105 ret = drv->bdrv_co_readv(bs, sector_num, nb_sectors, qiov);
1106
1107out:
1108 if (qiov == &local_qiov) {
1109 qemu_iovec_destroy(&local_qiov);
1110 }
1111
1112 return ret;
1113}
1114
1115static int coroutine_fn bdrv_driver_pwritev(BlockDriverState *bs,
1116 uint64_t offset, uint64_t bytes,
1117 QEMUIOVector *qiov,
1118 size_t qiov_offset, int flags)
1119{
1120 BlockDriver *drv = bs->drv;
1121 int64_t sector_num;
1122 unsigned int nb_sectors;
1123 QEMUIOVector local_qiov;
1124 int ret;
1125
1126 assert(!(flags & ~BDRV_REQ_MASK));
1127 assert(!(flags & BDRV_REQ_NO_FALLBACK));
1128
1129 if (!drv) {
1130 return -ENOMEDIUM;
1131 }
1132
1133 if (drv->bdrv_co_pwritev_part) {
1134 ret = drv->bdrv_co_pwritev_part(bs, offset, bytes, qiov, qiov_offset,
1135 flags & bs->supported_write_flags);
1136 flags &= ~bs->supported_write_flags;
1137 goto emulate_flags;
1138 }
1139
1140 if (qiov_offset > 0 || bytes != qiov->size) {
1141 qemu_iovec_init_slice(&local_qiov, qiov, qiov_offset, bytes);
1142 qiov = &local_qiov;
1143 }
1144
1145 if (drv->bdrv_co_pwritev) {
1146 ret = drv->bdrv_co_pwritev(bs, offset, bytes, qiov,
1147 flags & bs->supported_write_flags);
1148 flags &= ~bs->supported_write_flags;
1149 goto emulate_flags;
1150 }
1151
1152 if (drv->bdrv_aio_pwritev) {
1153 BlockAIOCB *acb;
1154 CoroutineIOCompletion co = {
1155 .coroutine = qemu_coroutine_self(),
1156 };
1157
1158 acb = drv->bdrv_aio_pwritev(bs, offset, bytes, qiov,
1159 flags & bs->supported_write_flags,
1160 bdrv_co_io_em_complete, &co);
1161 flags &= ~bs->supported_write_flags;
1162 if (acb == NULL) {
1163 ret = -EIO;
1164 } else {
1165 qemu_coroutine_yield();
1166 ret = co.ret;
1167 }
1168 goto emulate_flags;
1169 }
1170
1171 sector_num = offset >> BDRV_SECTOR_BITS;
1172 nb_sectors = bytes >> BDRV_SECTOR_BITS;
1173
1174 assert((offset & (BDRV_SECTOR_SIZE - 1)) == 0);
1175 assert((bytes & (BDRV_SECTOR_SIZE - 1)) == 0);
1176 assert(bytes <= BDRV_REQUEST_MAX_BYTES);
1177
1178 assert(drv->bdrv_co_writev);
1179 ret = drv->bdrv_co_writev(bs, sector_num, nb_sectors, qiov,
1180 flags & bs->supported_write_flags);
1181 flags &= ~bs->supported_write_flags;
1182
1183emulate_flags:
1184 if (ret == 0 && (flags & BDRV_REQ_FUA)) {
1185 ret = bdrv_co_flush(bs);
1186 }
1187
1188 if (qiov == &local_qiov) {
1189 qemu_iovec_destroy(&local_qiov);
1190 }
1191
1192 return ret;
1193}
1194
1195static int coroutine_fn
1196bdrv_driver_pwritev_compressed(BlockDriverState *bs, uint64_t offset,
1197 uint64_t bytes, QEMUIOVector *qiov,
1198 size_t qiov_offset)
1199{
1200 BlockDriver *drv = bs->drv;
1201 QEMUIOVector local_qiov;
1202 int ret;
1203
1204 if (!drv) {
1205 return -ENOMEDIUM;
1206 }
1207
1208 if (!block_driver_can_compress(drv)) {
1209 return -ENOTSUP;
1210 }
1211
1212 if (drv->bdrv_co_pwritev_compressed_part) {
1213 return drv->bdrv_co_pwritev_compressed_part(bs, offset, bytes,
1214 qiov, qiov_offset);
1215 }
1216
1217 if (qiov_offset == 0) {
1218 return drv->bdrv_co_pwritev_compressed(bs, offset, bytes, qiov);
1219 }
1220
1221 qemu_iovec_init_slice(&local_qiov, qiov, qiov_offset, bytes);
1222 ret = drv->bdrv_co_pwritev_compressed(bs, offset, bytes, &local_qiov);
1223 qemu_iovec_destroy(&local_qiov);
1224
1225 return ret;
1226}
1227
1228static int coroutine_fn bdrv_co_do_copy_on_readv(BdrvChild *child,
1229 int64_t offset, unsigned int bytes, QEMUIOVector *qiov,
1230 size_t qiov_offset, int flags)
1231{
1232 BlockDriverState *bs = child->bs;
1233
1234 /* Perform I/O through a temporary buffer so that users who scribble over
1235 * their read buffer while the operation is in progress do not end up
1236 * modifying the image file. This is critical for zero-copy guest I/O
1237 * where anything might happen inside guest memory.
1238 */
1239 void *bounce_buffer = NULL;
1240
1241 BlockDriver *drv = bs->drv;
1242 int64_t cluster_offset;
1243 int64_t cluster_bytes;
1244 size_t skip_bytes;
1245 int ret;
1246 int max_transfer = MIN_NON_ZERO(bs->bl.max_transfer,
1247 BDRV_REQUEST_MAX_BYTES);
1248 unsigned int progress = 0;
1249
1250 if (!drv) {
1251 return -ENOMEDIUM;
1252 }
1253
1254 /* FIXME We cannot require callers to have write permissions when all they
1255 * are doing is a read request. If we did things right, write permissions
1256 * would be obtained anyway, but internally by the copy-on-read code. As
1257 * long as it is implemented here rather than in a separate filter driver,
1258 * the copy-on-read code doesn't have its own BdrvChild, however, for which
1259 * it could request permissions. Therefore we have to bypass the permission
1260 * system for the moment. */
1261 // assert(child->perm & (BLK_PERM_WRITE_UNCHANGED | BLK_PERM_WRITE));
1262
1263 /* Cover entire cluster so no additional backing file I/O is required when
1264 * allocating cluster in the image file. Note that this value may exceed
1265 * BDRV_REQUEST_MAX_BYTES (even when the original read did not), which
1266 * is one reason we loop rather than doing it all at once.
1267 */
1268 bdrv_round_to_clusters(bs, offset, bytes, &cluster_offset, &cluster_bytes);
1269 skip_bytes = offset - cluster_offset;
1270
1271 trace_bdrv_co_do_copy_on_readv(bs, offset, bytes,
1272 cluster_offset, cluster_bytes);
1273
1274 while (cluster_bytes) {
1275 int64_t pnum;
1276
1277 ret = bdrv_is_allocated(bs, cluster_offset,
1278 MIN(cluster_bytes, max_transfer), &pnum);
1279 if (ret < 0) {
1280 /* Safe to treat errors in querying allocation as if
1281 * unallocated; we'll probably fail again soon on the
1282 * read, but at least that will set a decent errno.
1283 */
1284 pnum = MIN(cluster_bytes, max_transfer);
1285 }
1286
1287 /* Stop at EOF if the image ends in the middle of the cluster */
1288 if (ret == 0 && pnum == 0) {
1289 assert(progress >= bytes);
1290 break;
1291 }
1292
1293 assert(skip_bytes < pnum);
1294
1295 if (ret <= 0) {
1296 QEMUIOVector local_qiov;
1297
1298 /* Must copy-on-read; use the bounce buffer */
1299 pnum = MIN(pnum, MAX_BOUNCE_BUFFER);
1300 if (!bounce_buffer) {
1301 int64_t max_we_need = MAX(pnum, cluster_bytes - pnum);
1302 int64_t max_allowed = MIN(max_transfer, MAX_BOUNCE_BUFFER);
1303 int64_t bounce_buffer_len = MIN(max_we_need, max_allowed);
1304
1305 bounce_buffer = qemu_try_blockalign(bs, bounce_buffer_len);
1306 if (!bounce_buffer) {
1307 ret = -ENOMEM;
1308 goto err;
1309 }
1310 }
1311 qemu_iovec_init_buf(&local_qiov, bounce_buffer, pnum);
1312
1313 ret = bdrv_driver_preadv(bs, cluster_offset, pnum,
1314 &local_qiov, 0, 0);
1315 if (ret < 0) {
1316 goto err;
1317 }
1318
1319 bdrv_debug_event(bs, BLKDBG_COR_WRITE);
1320 if (drv->bdrv_co_pwrite_zeroes &&
1321 buffer_is_zero(bounce_buffer, pnum)) {
1322 /* FIXME: Should we (perhaps conditionally) be setting
1323 * BDRV_REQ_MAY_UNMAP, if it will allow for a sparser copy
1324 * that still correctly reads as zero? */
1325 ret = bdrv_co_do_pwrite_zeroes(bs, cluster_offset, pnum,
1326 BDRV_REQ_WRITE_UNCHANGED);
1327 } else {
1328 /* This does not change the data on the disk, it is not
1329 * necessary to flush even in cache=writethrough mode.
1330 */
1331 ret = bdrv_driver_pwritev(bs, cluster_offset, pnum,
1332 &local_qiov, 0,
1333 BDRV_REQ_WRITE_UNCHANGED);
1334 }
1335
1336 if (ret < 0) {
1337 /* It might be okay to ignore write errors for guest
1338 * requests. If this is a deliberate copy-on-read
1339 * then we don't want to ignore the error. Simply
1340 * report it in all cases.
1341 */
1342 goto err;
1343 }
1344
1345 if (!(flags & BDRV_REQ_PREFETCH)) {
1346 qemu_iovec_from_buf(qiov, qiov_offset + progress,
1347 bounce_buffer + skip_bytes,
1348 pnum - skip_bytes);
1349 }
1350 } else if (!(flags & BDRV_REQ_PREFETCH)) {
1351 /* Read directly into the destination */
1352 ret = bdrv_driver_preadv(bs, offset + progress,
1353 MIN(pnum - skip_bytes, bytes - progress),
1354 qiov, qiov_offset + progress, 0);
1355 if (ret < 0) {
1356 goto err;
1357 }
1358 }
1359
1360 cluster_offset += pnum;
1361 cluster_bytes -= pnum;
1362 progress += pnum - skip_bytes;
1363 skip_bytes = 0;
1364 }
1365 ret = 0;
1366
1367err:
1368 qemu_vfree(bounce_buffer);
1369 return ret;
1370}
1371
1372/*
1373 * Forwards an already correctly aligned request to the BlockDriver. This
1374 * handles copy on read, zeroing after EOF, and fragmentation of large
1375 * reads; any other features must be implemented by the caller.
1376 */
1377static int coroutine_fn bdrv_aligned_preadv(BdrvChild *child,
1378 BdrvTrackedRequest *req, int64_t offset, unsigned int bytes,
1379 int64_t align, QEMUIOVector *qiov, size_t qiov_offset, int flags)
1380{
1381 BlockDriverState *bs = child->bs;
1382 int64_t total_bytes, max_bytes;
1383 int ret = 0;
1384 uint64_t bytes_remaining = bytes;
1385 int max_transfer;
1386
1387 assert(is_power_of_2(align));
1388 assert((offset & (align - 1)) == 0);
1389 assert((bytes & (align - 1)) == 0);
1390 assert((bs->open_flags & BDRV_O_NO_IO) == 0);
1391 max_transfer = QEMU_ALIGN_DOWN(MIN_NON_ZERO(bs->bl.max_transfer, INT_MAX),
1392 align);
1393
1394 /* TODO: We would need a per-BDS .supported_read_flags and
1395 * potential fallback support, if we ever implement any read flags
1396 * to pass through to drivers. For now, there aren't any
1397 * passthrough flags. */
1398 assert(!(flags & ~(BDRV_REQ_NO_SERIALISING | BDRV_REQ_COPY_ON_READ |
1399 BDRV_REQ_PREFETCH)));
1400
1401 /* Handle Copy on Read and associated serialisation */
1402 if (flags & BDRV_REQ_COPY_ON_READ) {
1403 /* If we touch the same cluster it counts as an overlap. This
1404 * guarantees that allocating writes will be serialized and not race
1405 * with each other for the same cluster. For example, in copy-on-read
1406 * it ensures that the CoR read and write operations are atomic and
1407 * guest writes cannot interleave between them. */
1408 mark_request_serialising(req, bdrv_get_cluster_size(bs));
1409 }
1410
1411 /* BDRV_REQ_SERIALISING is only for write operation */
1412 assert(!(flags & BDRV_REQ_SERIALISING));
1413
1414 if (!(flags & BDRV_REQ_NO_SERIALISING)) {
1415 wait_serialising_requests(req);
1416 }
1417
1418 if (flags & BDRV_REQ_COPY_ON_READ) {
1419 int64_t pnum;
1420
1421 ret = bdrv_is_allocated(bs, offset, bytes, &pnum);
1422 if (ret < 0) {
1423 goto out;
1424 }
1425
1426 if (!ret || pnum != bytes) {
1427 ret = bdrv_co_do_copy_on_readv(child, offset, bytes,
1428 qiov, qiov_offset, flags);
1429 goto out;
1430 } else if (flags & BDRV_REQ_PREFETCH) {
1431 goto out;
1432 }
1433 }
1434
1435 /* Forward the request to the BlockDriver, possibly fragmenting it */
1436 total_bytes = bdrv_getlength(bs);
1437 if (total_bytes < 0) {
1438 ret = total_bytes;
1439 goto out;
1440 }
1441
1442 max_bytes = ROUND_UP(MAX(0, total_bytes - offset), align);
1443 if (bytes <= max_bytes && bytes <= max_transfer) {
1444 ret = bdrv_driver_preadv(bs, offset, bytes, qiov, qiov_offset, 0);
1445 goto out;
1446 }
1447
1448 while (bytes_remaining) {
1449 int num;
1450
1451 if (max_bytes) {
1452 num = MIN(bytes_remaining, MIN(max_bytes, max_transfer));
1453 assert(num);
1454
1455 ret = bdrv_driver_preadv(bs, offset + bytes - bytes_remaining,
1456 num, qiov, bytes - bytes_remaining, 0);
1457 max_bytes -= num;
1458 } else {
1459 num = bytes_remaining;
1460 ret = qemu_iovec_memset(qiov, bytes - bytes_remaining, 0,
1461 bytes_remaining);
1462 }
1463 if (ret < 0) {
1464 goto out;
1465 }
1466 bytes_remaining -= num;
1467 }
1468
1469out:
1470 return ret < 0 ? ret : 0;
1471}
1472
1473/*
1474 * Request padding
1475 *
1476 * |<---- align ----->| |<----- align ---->|
1477 * |<- head ->|<------------- bytes ------------->|<-- tail -->|
1478 * | | | | | |
1479 * -*----------$-------*-------- ... --------*-----$------------*---
1480 * | | | | | |
1481 * | offset | | end |
1482 * ALIGN_DOWN(offset) ALIGN_UP(offset) ALIGN_DOWN(end) ALIGN_UP(end)
1483 * [buf ... ) [tail_buf )
1484 *
1485 * @buf is an aligned allocation needed to store @head and @tail paddings. @head
1486 * is placed at the beginning of @buf and @tail at the @end.
1487 *
1488 * @tail_buf is a pointer to sub-buffer, corresponding to align-sized chunk
1489 * around tail, if tail exists.
1490 *
1491 * @merge_reads is true for small requests,
1492 * if @buf_len == @head + bytes + @tail. In this case it is possible that both
1493 * head and tail exist but @buf_len == align and @tail_buf == @buf.
1494 */
1495typedef struct BdrvRequestPadding {
1496 uint8_t *buf;
1497 size_t buf_len;
1498 uint8_t *tail_buf;
1499 size_t head;
1500 size_t tail;
1501 bool merge_reads;
1502 QEMUIOVector local_qiov;
1503} BdrvRequestPadding;
1504
1505static bool bdrv_init_padding(BlockDriverState *bs,
1506 int64_t offset, int64_t bytes,
1507 BdrvRequestPadding *pad)
1508{
1509 uint64_t align = bs->bl.request_alignment;
1510 size_t sum;
1511
1512 memset(pad, 0, sizeof(*pad));
1513
1514 pad->head = offset & (align - 1);
1515 pad->tail = ((offset + bytes) & (align - 1));
1516 if (pad->tail) {
1517 pad->tail = align - pad->tail;
1518 }
1519
1520 if ((!pad->head && !pad->tail) || !bytes) {
1521 return false;
1522 }
1523
1524 sum = pad->head + bytes + pad->tail;
1525 pad->buf_len = (sum > align && pad->head && pad->tail) ? 2 * align : align;
1526 pad->buf = qemu_blockalign(bs, pad->buf_len);
1527 pad->merge_reads = sum == pad->buf_len;
1528 if (pad->tail) {
1529 pad->tail_buf = pad->buf + pad->buf_len - align;
1530 }
1531
1532 return true;
1533}
1534
1535static int bdrv_padding_rmw_read(BdrvChild *child,
1536 BdrvTrackedRequest *req,
1537 BdrvRequestPadding *pad,
1538 bool zero_middle)
1539{
1540 QEMUIOVector local_qiov;
1541 BlockDriverState *bs = child->bs;
1542 uint64_t align = bs->bl.request_alignment;
1543 int ret;
1544
1545 assert(req->serialising && pad->buf);
1546
1547 if (pad->head || pad->merge_reads) {
1548 uint64_t bytes = pad->merge_reads ? pad->buf_len : align;
1549
1550 qemu_iovec_init_buf(&local_qiov, pad->buf, bytes);
1551
1552 if (pad->head) {
1553 bdrv_debug_event(bs, BLKDBG_PWRITEV_RMW_HEAD);
1554 }
1555 if (pad->merge_reads && pad->tail) {
1556 bdrv_debug_event(bs, BLKDBG_PWRITEV_RMW_TAIL);
1557 }
1558 ret = bdrv_aligned_preadv(child, req, req->overlap_offset, bytes,
1559 align, &local_qiov, 0, 0);
1560 if (ret < 0) {
1561 return ret;
1562 }
1563 if (pad->head) {
1564 bdrv_debug_event(bs, BLKDBG_PWRITEV_RMW_AFTER_HEAD);
1565 }
1566 if (pad->merge_reads && pad->tail) {
1567 bdrv_debug_event(bs, BLKDBG_PWRITEV_RMW_AFTER_TAIL);
1568 }
1569
1570 if (pad->merge_reads) {
1571 goto zero_mem;
1572 }
1573 }
1574
1575 if (pad->tail) {
1576 qemu_iovec_init_buf(&local_qiov, pad->tail_buf, align);
1577
1578 bdrv_debug_event(bs, BLKDBG_PWRITEV_RMW_TAIL);
1579 ret = bdrv_aligned_preadv(
1580 child, req,
1581 req->overlap_offset + req->overlap_bytes - align,
1582 align, align, &local_qiov, 0, 0);
1583 if (ret < 0) {
1584 return ret;
1585 }
1586 bdrv_debug_event(bs, BLKDBG_PWRITEV_RMW_AFTER_TAIL);
1587 }
1588
1589zero_mem:
1590 if (zero_middle) {
1591 memset(pad->buf + pad->head, 0, pad->buf_len - pad->head - pad->tail);
1592 }
1593
1594 return 0;
1595}
1596
1597static void bdrv_padding_destroy(BdrvRequestPadding *pad)
1598{
1599 if (pad->buf) {
1600 qemu_vfree(pad->buf);
1601 qemu_iovec_destroy(&pad->local_qiov);
1602 }
1603}
1604
1605/*
1606 * bdrv_pad_request
1607 *
1608 * Exchange request parameters with padded request if needed. Don't include RMW
1609 * read of padding, bdrv_padding_rmw_read() should be called separately if
1610 * needed.
1611 *
1612 * All parameters except @bs are in-out: they represent original request at
1613 * function call and padded (if padding needed) at function finish.
1614 *
1615 * Function always succeeds.
1616 */
1617static bool bdrv_pad_request(BlockDriverState *bs,
1618 QEMUIOVector **qiov, size_t *qiov_offset,
1619 int64_t *offset, unsigned int *bytes,
1620 BdrvRequestPadding *pad)
1621{
1622 if (!bdrv_init_padding(bs, *offset, *bytes, pad)) {
1623 return false;
1624 }
1625
1626 qemu_iovec_init_extended(&pad->local_qiov, pad->buf, pad->head,
1627 *qiov, *qiov_offset, *bytes,
1628 pad->buf + pad->buf_len - pad->tail, pad->tail);
1629 *bytes += pad->head + pad->tail;
1630 *offset -= pad->head;
1631 *qiov = &pad->local_qiov;
1632 *qiov_offset = 0;
1633
1634 return true;
1635}
1636
1637int coroutine_fn bdrv_co_preadv(BdrvChild *child,
1638 int64_t offset, unsigned int bytes, QEMUIOVector *qiov,
1639 BdrvRequestFlags flags)
1640{
1641 return bdrv_co_preadv_part(child, offset, bytes, qiov, 0, flags);
1642}
1643
1644int coroutine_fn bdrv_co_preadv_part(BdrvChild *child,
1645 int64_t offset, unsigned int bytes,
1646 QEMUIOVector *qiov, size_t qiov_offset,
1647 BdrvRequestFlags flags)
1648{
1649 BlockDriverState *bs = child->bs;
1650 BdrvTrackedRequest req;
1651 BdrvRequestPadding pad;
1652 int ret;
1653
1654 trace_bdrv_co_preadv(bs, offset, bytes, flags);
1655
1656 ret = bdrv_check_byte_request(bs, offset, bytes);
1657 if (ret < 0) {
1658 return ret;
1659 }
1660
1661 bdrv_inc_in_flight(bs);
1662
1663 /* Don't do copy-on-read if we read data before write operation */
1664 if (atomic_read(&bs->copy_on_read) && !(flags & BDRV_REQ_NO_SERIALISING)) {
1665 flags |= BDRV_REQ_COPY_ON_READ;
1666 }
1667
1668 bdrv_pad_request(bs, &qiov, &qiov_offset, &offset, &bytes, &pad);
1669
1670 tracked_request_begin(&req, bs, offset, bytes, BDRV_TRACKED_READ);
1671 ret = bdrv_aligned_preadv(child, &req, offset, bytes,
1672 bs->bl.request_alignment,
1673 qiov, qiov_offset, flags);
1674 tracked_request_end(&req);
1675 bdrv_dec_in_flight(bs);
1676
1677 bdrv_padding_destroy(&pad);
1678
1679 return ret;
1680}
1681
1682static int coroutine_fn bdrv_co_do_pwrite_zeroes(BlockDriverState *bs,
1683 int64_t offset, int bytes, BdrvRequestFlags flags)
1684{
1685 BlockDriver *drv = bs->drv;
1686 QEMUIOVector qiov;
1687 void *buf = NULL;
1688 int ret = 0;
1689 bool need_flush = false;
1690 int head = 0;
1691 int tail = 0;
1692
1693 int max_write_zeroes = MIN_NON_ZERO(bs->bl.max_pwrite_zeroes, INT_MAX);
1694 int alignment = MAX(bs->bl.pwrite_zeroes_alignment,
1695 bs->bl.request_alignment);
1696 int max_transfer = MIN_NON_ZERO(bs->bl.max_transfer, MAX_BOUNCE_BUFFER);
1697
1698 if (!drv) {
1699 return -ENOMEDIUM;
1700 }
1701
1702 if ((flags & ~bs->supported_zero_flags) & BDRV_REQ_NO_FALLBACK) {
1703 return -ENOTSUP;
1704 }
1705
1706 assert(alignment % bs->bl.request_alignment == 0);
1707 head = offset % alignment;
1708 tail = (offset + bytes) % alignment;
1709 max_write_zeroes = QEMU_ALIGN_DOWN(max_write_zeroes, alignment);
1710 assert(max_write_zeroes >= bs->bl.request_alignment);
1711
1712 while (bytes > 0 && !ret) {
1713 int num = bytes;
1714
1715 /* Align request. Block drivers can expect the "bulk" of the request
1716 * to be aligned, and that unaligned requests do not cross cluster
1717 * boundaries.
1718 */
1719 if (head) {
1720 /* Make a small request up to the first aligned sector. For
1721 * convenience, limit this request to max_transfer even if
1722 * we don't need to fall back to writes. */
1723 num = MIN(MIN(bytes, max_transfer), alignment - head);
1724 head = (head + num) % alignment;
1725 assert(num < max_write_zeroes);
1726 } else if (tail && num > alignment) {
1727 /* Shorten the request to the last aligned sector. */
1728 num -= tail;
1729 }
1730
1731 /* limit request size */
1732 if (num > max_write_zeroes) {
1733 num = max_write_zeroes;
1734 }
1735
1736 ret = -ENOTSUP;
1737 /* First try the efficient write zeroes operation */
1738 if (drv->bdrv_co_pwrite_zeroes) {
1739 ret = drv->bdrv_co_pwrite_zeroes(bs, offset, num,
1740 flags & bs->supported_zero_flags);
1741 if (ret != -ENOTSUP && (flags & BDRV_REQ_FUA) &&
1742 !(bs->supported_zero_flags & BDRV_REQ_FUA)) {
1743 need_flush = true;
1744 }
1745 } else {
1746 assert(!bs->supported_zero_flags);
1747 }
1748
1749 if (ret < 0 && !(flags & BDRV_REQ_NO_FALLBACK)) {
1750 /* Fall back to bounce buffer if write zeroes is unsupported */
1751 BdrvRequestFlags write_flags = flags & ~BDRV_REQ_ZERO_WRITE;
1752
1753 if ((flags & BDRV_REQ_FUA) &&
1754 !(bs->supported_write_flags & BDRV_REQ_FUA)) {
1755 /* No need for bdrv_driver_pwrite() to do a fallback
1756 * flush on each chunk; use just one at the end */
1757 write_flags &= ~BDRV_REQ_FUA;
1758 need_flush = true;
1759 }
1760 num = MIN(num, max_transfer);
1761 if (buf == NULL) {
1762 buf = qemu_try_blockalign0(bs, num);
1763 if (buf == NULL) {
1764 ret = -ENOMEM;
1765 goto fail;
1766 }
1767 }
1768 qemu_iovec_init_buf(&qiov, buf, num);
1769
1770 ret = bdrv_driver_pwritev(bs, offset, num, &qiov, 0, write_flags);
1771
1772 /* Keep bounce buffer around if it is big enough for all
1773 * all future requests.
1774 */
1775 if (num < max_transfer) {
1776 qemu_vfree(buf);
1777 buf = NULL;
1778 }
1779 }
1780
1781 offset += num;
1782 bytes -= num;
1783 }
1784
1785fail:
1786 if (ret == 0 && need_flush) {
1787 ret = bdrv_co_flush(bs);
1788 }
1789 qemu_vfree(buf);
1790 return ret;
1791}
1792
1793static inline int coroutine_fn
1794bdrv_co_write_req_prepare(BdrvChild *child, int64_t offset, uint64_t bytes,
1795 BdrvTrackedRequest *req, int flags)
1796{
1797 BlockDriverState *bs = child->bs;
1798 bool waited;
1799 int64_t end_sector = DIV_ROUND_UP(offset + bytes, BDRV_SECTOR_SIZE);
1800
1801 if (bs->read_only) {
1802 return -EPERM;
1803 }
1804
1805 /* BDRV_REQ_NO_SERIALISING is only for read operation */
1806 assert(!(flags & BDRV_REQ_NO_SERIALISING));
1807 assert(!(bs->open_flags & BDRV_O_INACTIVE));
1808 assert((bs->open_flags & BDRV_O_NO_IO) == 0);
1809 assert(!(flags & ~BDRV_REQ_MASK));
1810
1811 if (flags & BDRV_REQ_SERIALISING) {
1812 mark_request_serialising(req, bdrv_get_cluster_size(bs));
1813 }
1814
1815 waited = wait_serialising_requests(req);
1816
1817 assert(!waited || !req->serialising ||
1818 is_request_serialising_and_aligned(req));
1819 assert(req->overlap_offset <= offset);
1820 assert(offset + bytes <= req->overlap_offset + req->overlap_bytes);
1821 assert(end_sector <= bs->total_sectors || child->perm & BLK_PERM_RESIZE);
1822
1823 switch (req->type) {
1824 case BDRV_TRACKED_WRITE:
1825 case BDRV_TRACKED_DISCARD:
1826 if (flags & BDRV_REQ_WRITE_UNCHANGED) {
1827 assert(child->perm & (BLK_PERM_WRITE_UNCHANGED | BLK_PERM_WRITE));
1828 } else {
1829 assert(child->perm & BLK_PERM_WRITE);
1830 }
1831 return notifier_with_return_list_notify(&bs->before_write_notifiers,
1832 req);
1833 case BDRV_TRACKED_TRUNCATE:
1834 assert(child->perm & BLK_PERM_RESIZE);
1835 return 0;
1836 default:
1837 abort();
1838 }
1839}
1840
1841static inline void coroutine_fn
1842bdrv_co_write_req_finish(BdrvChild *child, int64_t offset, uint64_t bytes,
1843 BdrvTrackedRequest *req, int ret)
1844{
1845 int64_t end_sector = DIV_ROUND_UP(offset + bytes, BDRV_SECTOR_SIZE);
1846 BlockDriverState *bs = child->bs;
1847
1848 atomic_inc(&bs->write_gen);
1849
1850 /*
1851 * Discard cannot extend the image, but in error handling cases, such as
1852 * when reverting a qcow2 cluster allocation, the discarded range can pass
1853 * the end of image file, so we cannot assert about BDRV_TRACKED_DISCARD
1854 * here. Instead, just skip it, since semantically a discard request
1855 * beyond EOF cannot expand the image anyway.
1856 */
1857 if (ret == 0 &&
1858 (req->type == BDRV_TRACKED_TRUNCATE ||
1859 end_sector > bs->total_sectors) &&
1860 req->type != BDRV_TRACKED_DISCARD) {
1861 bs->total_sectors = end_sector;
1862 bdrv_parent_cb_resize(bs);
1863 bdrv_dirty_bitmap_truncate(bs, end_sector << BDRV_SECTOR_BITS);
1864 }
1865 if (req->bytes) {
1866 switch (req->type) {
1867 case BDRV_TRACKED_WRITE:
1868 stat64_max(&bs->wr_highest_offset, offset + bytes);
1869 /* fall through, to set dirty bits */
1870 case BDRV_TRACKED_DISCARD:
1871 bdrv_set_dirty(bs, offset, bytes);
1872 break;
1873 default:
1874 break;
1875 }
1876 }
1877}
1878
1879/*
1880 * Forwards an already correctly aligned write request to the BlockDriver,
1881 * after possibly fragmenting it.
1882 */
1883static int coroutine_fn bdrv_aligned_pwritev(BdrvChild *child,
1884 BdrvTrackedRequest *req, int64_t offset, unsigned int bytes,
1885 int64_t align, QEMUIOVector *qiov, size_t qiov_offset, int flags)
1886{
1887 BlockDriverState *bs = child->bs;
1888 BlockDriver *drv = bs->drv;
1889 int ret;
1890
1891 uint64_t bytes_remaining = bytes;
1892 int max_transfer;
1893
1894 if (!drv) {
1895 return -ENOMEDIUM;
1896 }
1897
1898 if (bdrv_has_readonly_bitmaps(bs)) {
1899 return -EPERM;
1900 }
1901
1902 assert(is_power_of_2(align));
1903 assert((offset & (align - 1)) == 0);
1904 assert((bytes & (align - 1)) == 0);
1905 assert(!qiov || qiov_offset + bytes <= qiov->size);
1906 max_transfer = QEMU_ALIGN_DOWN(MIN_NON_ZERO(bs->bl.max_transfer, INT_MAX),
1907 align);
1908
1909 ret = bdrv_co_write_req_prepare(child, offset, bytes, req, flags);
1910
1911 if (!ret && bs->detect_zeroes != BLOCKDEV_DETECT_ZEROES_OPTIONS_OFF &&
1912 !(flags & BDRV_REQ_ZERO_WRITE) && drv->bdrv_co_pwrite_zeroes &&
1913 qemu_iovec_is_zero(qiov, qiov_offset, bytes)) {
1914 flags |= BDRV_REQ_ZERO_WRITE;
1915 if (bs->detect_zeroes == BLOCKDEV_DETECT_ZEROES_OPTIONS_UNMAP) {
1916 flags |= BDRV_REQ_MAY_UNMAP;
1917 }
1918 }
1919
1920 if (ret < 0) {
1921 /* Do nothing, write notifier decided to fail this request */
1922 } else if (flags & BDRV_REQ_ZERO_WRITE) {
1923 bdrv_debug_event(bs, BLKDBG_PWRITEV_ZERO);
1924 ret = bdrv_co_do_pwrite_zeroes(bs, offset, bytes, flags);
1925 } else if (flags & BDRV_REQ_WRITE_COMPRESSED) {
1926 ret = bdrv_driver_pwritev_compressed(bs, offset, bytes,
1927 qiov, qiov_offset);
1928 } else if (bytes <= max_transfer) {
1929 bdrv_debug_event(bs, BLKDBG_PWRITEV);
1930 ret = bdrv_driver_pwritev(bs, offset, bytes, qiov, qiov_offset, flags);
1931 } else {
1932 bdrv_debug_event(bs, BLKDBG_PWRITEV);
1933 while (bytes_remaining) {
1934 int num = MIN(bytes_remaining, max_transfer);
1935 int local_flags = flags;
1936
1937 assert(num);
1938 if (num < bytes_remaining && (flags & BDRV_REQ_FUA) &&
1939 !(bs->supported_write_flags & BDRV_REQ_FUA)) {
1940 /* If FUA is going to be emulated by flush, we only
1941 * need to flush on the last iteration */
1942 local_flags &= ~BDRV_REQ_FUA;
1943 }
1944
1945 ret = bdrv_driver_pwritev(bs, offset + bytes - bytes_remaining,
1946 num, qiov, bytes - bytes_remaining,
1947 local_flags);
1948 if (ret < 0) {
1949 break;
1950 }
1951 bytes_remaining -= num;
1952 }
1953 }
1954 bdrv_debug_event(bs, BLKDBG_PWRITEV_DONE);
1955
1956 if (ret >= 0) {
1957 ret = 0;
1958 }
1959 bdrv_co_write_req_finish(child, offset, bytes, req, ret);
1960
1961 return ret;
1962}
1963
1964static int coroutine_fn bdrv_co_do_zero_pwritev(BdrvChild *child,
1965 int64_t offset,
1966 unsigned int bytes,
1967 BdrvRequestFlags flags,
1968 BdrvTrackedRequest *req)
1969{
1970 BlockDriverState *bs = child->bs;
1971 QEMUIOVector local_qiov;
1972 uint64_t align = bs->bl.request_alignment;
1973 int ret = 0;
1974 bool padding;
1975 BdrvRequestPadding pad;
1976
1977 padding = bdrv_init_padding(bs, offset, bytes, &pad);
1978 if (padding) {
1979 mark_request_serialising(req, align);
1980 wait_serialising_requests(req);
1981
1982 bdrv_padding_rmw_read(child, req, &pad, true);
1983
1984 if (pad.head || pad.merge_reads) {
1985 int64_t aligned_offset = offset & ~(align - 1);
1986 int64_t write_bytes = pad.merge_reads ? pad.buf_len : align;
1987
1988 qemu_iovec_init_buf(&local_qiov, pad.buf, write_bytes);
1989 ret = bdrv_aligned_pwritev(child, req, aligned_offset, write_bytes,
1990 align, &local_qiov, 0,
1991 flags & ~BDRV_REQ_ZERO_WRITE);
1992 if (ret < 0 || pad.merge_reads) {
1993 /* Error or all work is done */
1994 goto out;
1995 }
1996 offset += write_bytes - pad.head;
1997 bytes -= write_bytes - pad.head;
1998 }
1999 }
2000
2001 assert(!bytes || (offset & (align - 1)) == 0);
2002 if (bytes >= align) {
2003 /* Write the aligned part in the middle. */
2004 uint64_t aligned_bytes = bytes & ~(align - 1);
2005 ret = bdrv_aligned_pwritev(child, req, offset, aligned_bytes, align,
2006 NULL, 0, flags);
2007 if (ret < 0) {
2008 goto out;
2009 }
2010 bytes -= aligned_bytes;
2011 offset += aligned_bytes;
2012 }
2013
2014 assert(!bytes || (offset & (align - 1)) == 0);
2015 if (bytes) {
2016 assert(align == pad.tail + bytes);
2017
2018 qemu_iovec_init_buf(&local_qiov, pad.tail_buf, align);
2019 ret = bdrv_aligned_pwritev(child, req, offset, align, align,
2020 &local_qiov, 0,
2021 flags & ~BDRV_REQ_ZERO_WRITE);
2022 }
2023
2024out:
2025 bdrv_padding_destroy(&pad);
2026
2027 return ret;
2028}
2029
2030/*
2031 * Handle a write request in coroutine context
2032 */
2033int coroutine_fn bdrv_co_pwritev(BdrvChild *child,
2034 int64_t offset, unsigned int bytes, QEMUIOVector *qiov,
2035 BdrvRequestFlags flags)
2036{
2037 return bdrv_co_pwritev_part(child, offset, bytes, qiov, 0, flags);
2038}
2039
2040int coroutine_fn bdrv_co_pwritev_part(BdrvChild *child,
2041 int64_t offset, unsigned int bytes, QEMUIOVector *qiov, size_t qiov_offset,
2042 BdrvRequestFlags flags)
2043{
2044 BlockDriverState *bs = child->bs;
2045 BdrvTrackedRequest req;
2046 uint64_t align = bs->bl.request_alignment;
2047 BdrvRequestPadding pad;
2048 int ret;
2049
2050 trace_bdrv_co_pwritev(child->bs, offset, bytes, flags);
2051
2052 if (!bs->drv) {
2053 return -ENOMEDIUM;
2054 }
2055
2056 ret = bdrv_check_byte_request(bs, offset, bytes);
2057 if (ret < 0) {
2058 return ret;
2059 }
2060
2061 bdrv_inc_in_flight(bs);
2062 /*
2063 * Align write if necessary by performing a read-modify-write cycle.
2064 * Pad qiov with the read parts and be sure to have a tracked request not
2065 * only for bdrv_aligned_pwritev, but also for the reads of the RMW cycle.
2066 */
2067 tracked_request_begin(&req, bs, offset, bytes, BDRV_TRACKED_WRITE);
2068
2069 if (flags & BDRV_REQ_ZERO_WRITE) {
2070 ret = bdrv_co_do_zero_pwritev(child, offset, bytes, flags, &req);
2071 goto out;
2072 }
2073
2074 if (bdrv_pad_request(bs, &qiov, &qiov_offset, &offset, &bytes, &pad)) {
2075 mark_request_serialising(&req, align);
2076 wait_serialising_requests(&req);
2077 bdrv_padding_rmw_read(child, &req, &pad, false);
2078 }
2079
2080 ret = bdrv_aligned_pwritev(child, &req, offset, bytes, align,
2081 qiov, qiov_offset, flags);
2082
2083 bdrv_padding_destroy(&pad);
2084
2085out:
2086 tracked_request_end(&req);
2087 bdrv_dec_in_flight(bs);
2088
2089 return ret;
2090}
2091
2092int coroutine_fn bdrv_co_pwrite_zeroes(BdrvChild *child, int64_t offset,
2093 int bytes, BdrvRequestFlags flags)
2094{
2095 trace_bdrv_co_pwrite_zeroes(child->bs, offset, bytes, flags);
2096
2097 if (!(child->bs->open_flags & BDRV_O_UNMAP)) {
2098 flags &= ~BDRV_REQ_MAY_UNMAP;
2099 }
2100
2101 return bdrv_co_pwritev(child, offset, bytes, NULL,
2102 BDRV_REQ_ZERO_WRITE | flags);
2103}
2104
2105/*
2106 * Flush ALL BDSes regardless of if they are reachable via a BlkBackend or not.
2107 */
2108int bdrv_flush_all(void)
2109{
2110 BdrvNextIterator it;
2111 BlockDriverState *bs = NULL;
2112 int result = 0;
2113
2114 for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
2115 AioContext *aio_context = bdrv_get_aio_context(bs);
2116 int ret;
2117
2118 aio_context_acquire(aio_context);
2119 ret = bdrv_flush(bs);
2120 if (ret < 0 && !result) {
2121 result = ret;
2122 }
2123 aio_context_release(aio_context);
2124 }
2125
2126 return result;
2127}
2128
2129
2130typedef struct BdrvCoBlockStatusData {
2131 BlockDriverState *bs;
2132 BlockDriverState *base;
2133 bool want_zero;
2134 int64_t offset;
2135 int64_t bytes;
2136 int64_t *pnum;
2137 int64_t *map;
2138 BlockDriverState **file;
2139 int ret;
2140 bool done;
2141} BdrvCoBlockStatusData;
2142
2143int coroutine_fn bdrv_co_block_status_from_file(BlockDriverState *bs,
2144 bool want_zero,
2145 int64_t offset,
2146 int64_t bytes,
2147 int64_t *pnum,
2148 int64_t *map,
2149 BlockDriverState **file)
2150{
2151 assert(bs->file && bs->file->bs);
2152 *pnum = bytes;
2153 *map = offset;
2154 *file = bs->file->bs;
2155 return BDRV_BLOCK_RAW | BDRV_BLOCK_OFFSET_VALID;
2156}
2157
2158int coroutine_fn bdrv_co_block_status_from_backing(BlockDriverState *bs,
2159 bool want_zero,
2160 int64_t offset,
2161 int64_t bytes,
2162 int64_t *pnum,
2163 int64_t *map,
2164 BlockDriverState **file)
2165{
2166 assert(bs->backing && bs->backing->bs);
2167 *pnum = bytes;
2168 *map = offset;
2169 *file = bs->backing->bs;
2170 return BDRV_BLOCK_RAW | BDRV_BLOCK_OFFSET_VALID;
2171}
2172
2173/*
2174 * Returns the allocation status of the specified sectors.
2175 * Drivers not implementing the functionality are assumed to not support
2176 * backing files, hence all their sectors are reported as allocated.
2177 *
2178 * If 'want_zero' is true, the caller is querying for mapping
2179 * purposes, with a focus on valid BDRV_BLOCK_OFFSET_VALID, _DATA, and
2180 * _ZERO where possible; otherwise, the result favors larger 'pnum',
2181 * with a focus on accurate BDRV_BLOCK_ALLOCATED.
2182 *
2183 * If 'offset' is beyond the end of the disk image the return value is
2184 * BDRV_BLOCK_EOF and 'pnum' is set to 0.
2185 *
2186 * 'bytes' is the max value 'pnum' should be set to. If bytes goes
2187 * beyond the end of the disk image it will be clamped; if 'pnum' is set to
2188 * the end of the image, then the returned value will include BDRV_BLOCK_EOF.
2189 *
2190 * 'pnum' is set to the number of bytes (including and immediately
2191 * following the specified offset) that are easily known to be in the
2192 * same allocated/unallocated state. Note that a second call starting
2193 * at the original offset plus returned pnum may have the same status.
2194 * The returned value is non-zero on success except at end-of-file.
2195 *
2196 * Returns negative errno on failure. Otherwise, if the
2197 * BDRV_BLOCK_OFFSET_VALID bit is set, 'map' and 'file' (if non-NULL) are
2198 * set to the host mapping and BDS corresponding to the guest offset.
2199 */
2200static int coroutine_fn bdrv_co_block_status(BlockDriverState *bs,
2201 bool want_zero,
2202 int64_t offset, int64_t bytes,
2203 int64_t *pnum, int64_t *map,
2204 BlockDriverState **file)
2205{
2206 int64_t total_size;
2207 int64_t n; /* bytes */
2208 int ret;
2209 int64_t local_map = 0;
2210 BlockDriverState *local_file = NULL;
2211 int64_t aligned_offset, aligned_bytes;
2212 uint32_t align;
2213
2214 assert(pnum);
2215 *pnum = 0;
2216 total_size = bdrv_getlength(bs);
2217 if (total_size < 0) {
2218 ret = total_size;
2219 goto early_out;
2220 }
2221
2222 if (offset >= total_size) {
2223 ret = BDRV_BLOCK_EOF;
2224 goto early_out;
2225 }
2226 if (!bytes) {
2227 ret = 0;
2228 goto early_out;
2229 }
2230
2231 n = total_size - offset;
2232 if (n < bytes) {
2233 bytes = n;
2234 }
2235
2236 /* Must be non-NULL or bdrv_getlength() would have failed */
2237 assert(bs->drv);
2238 if (!bs->drv->bdrv_co_block_status) {
2239 *pnum = bytes;
2240 ret = BDRV_BLOCK_DATA | BDRV_BLOCK_ALLOCATED;
2241 if (offset + bytes == total_size) {
2242 ret |= BDRV_BLOCK_EOF;
2243 }
2244 if (bs->drv->protocol_name) {
2245 ret |= BDRV_BLOCK_OFFSET_VALID;
2246 local_map = offset;
2247 local_file = bs;
2248 }
2249 goto early_out;
2250 }
2251
2252 bdrv_inc_in_flight(bs);
2253
2254 /* Round out to request_alignment boundaries */
2255 align = bs->bl.request_alignment;
2256 aligned_offset = QEMU_ALIGN_DOWN(offset, align);
2257 aligned_bytes = ROUND_UP(offset + bytes, align) - aligned_offset;
2258
2259 ret = bs->drv->bdrv_co_block_status(bs, want_zero, aligned_offset,
2260 aligned_bytes, pnum, &local_map,
2261 &local_file);
2262 if (ret < 0) {
2263 *pnum = 0;
2264 goto out;
2265 }
2266
2267 /*
2268 * The driver's result must be a non-zero multiple of request_alignment.
2269 * Clamp pnum and adjust map to original request.
2270 */
2271 assert(*pnum && QEMU_IS_ALIGNED(*pnum, align) &&
2272 align > offset - aligned_offset);
2273 if (ret & BDRV_BLOCK_RECURSE) {
2274 assert(ret & BDRV_BLOCK_DATA);
2275 assert(ret & BDRV_BLOCK_OFFSET_VALID);
2276 assert(!(ret & BDRV_BLOCK_ZERO));
2277 }
2278
2279 *pnum -= offset - aligned_offset;
2280 if (*pnum > bytes) {
2281 *pnum = bytes;
2282 }
2283 if (ret & BDRV_BLOCK_OFFSET_VALID) {
2284 local_map += offset - aligned_offset;
2285 }
2286
2287 if (ret & BDRV_BLOCK_RAW) {
2288 assert(ret & BDRV_BLOCK_OFFSET_VALID && local_file);
2289 ret = bdrv_co_block_status(local_file, want_zero, local_map,
2290 *pnum, pnum, &local_map, &local_file);
2291 goto out;
2292 }
2293
2294 if (ret & (BDRV_BLOCK_DATA | BDRV_BLOCK_ZERO)) {
2295 ret |= BDRV_BLOCK_ALLOCATED;
2296 } else if (want_zero) {
2297 if (bdrv_unallocated_blocks_are_zero(bs)) {
2298 ret |= BDRV_BLOCK_ZERO;
2299 } else if (bs->backing) {
2300 BlockDriverState *bs2 = bs->backing->bs;
2301 int64_t size2 = bdrv_getlength(bs2);
2302
2303 if (size2 >= 0 && offset >= size2) {
2304 ret |= BDRV_BLOCK_ZERO;
2305 }
2306 }
2307 }
2308
2309 if (want_zero && ret & BDRV_BLOCK_RECURSE &&
2310 local_file && local_file != bs &&
2311 (ret & BDRV_BLOCK_DATA) && !(ret & BDRV_BLOCK_ZERO) &&
2312 (ret & BDRV_BLOCK_OFFSET_VALID)) {
2313 int64_t file_pnum;
2314 int ret2;
2315
2316 ret2 = bdrv_co_block_status(local_file, want_zero, local_map,
2317 *pnum, &file_pnum, NULL, NULL);
2318 if (ret2 >= 0) {
2319 /* Ignore errors. This is just providing extra information, it
2320 * is useful but not necessary.
2321 */
2322 if (ret2 & BDRV_BLOCK_EOF &&
2323 (!file_pnum || ret2 & BDRV_BLOCK_ZERO)) {
2324 /*
2325 * It is valid for the format block driver to read
2326 * beyond the end of the underlying file's current
2327 * size; such areas read as zero.
2328 */
2329 ret |= BDRV_BLOCK_ZERO;
2330 } else {
2331 /* Limit request to the range reported by the protocol driver */
2332 *pnum = file_pnum;
2333 ret |= (ret2 & BDRV_BLOCK_ZERO);
2334 }
2335 }
2336 }
2337
2338out:
2339 bdrv_dec_in_flight(bs);
2340 if (ret >= 0 && offset + *pnum == total_size) {
2341 ret |= BDRV_BLOCK_EOF;
2342 }
2343early_out:
2344 if (file) {
2345 *file = local_file;
2346 }
2347 if (map) {
2348 *map = local_map;
2349 }
2350 return ret;
2351}
2352
2353static int coroutine_fn bdrv_co_block_status_above(BlockDriverState *bs,
2354 BlockDriverState *base,
2355 bool want_zero,
2356 int64_t offset,
2357 int64_t bytes,
2358 int64_t *pnum,
2359 int64_t *map,
2360 BlockDriverState **file)
2361{
2362 BlockDriverState *p;
2363 int ret = 0;
2364 bool first = true;
2365
2366 assert(bs != base);
2367 for (p = bs; p != base; p = backing_bs(p)) {
2368 ret = bdrv_co_block_status(p, want_zero, offset, bytes, pnum, map,
2369 file);
2370 if (ret < 0) {
2371 break;
2372 }
2373 if (ret & BDRV_BLOCK_ZERO && ret & BDRV_BLOCK_EOF && !first) {
2374 /*
2375 * Reading beyond the end of the file continues to read
2376 * zeroes, but we can only widen the result to the
2377 * unallocated length we learned from an earlier
2378 * iteration.
2379 */
2380 *pnum = bytes;
2381 }
2382 if (ret & (BDRV_BLOCK_ZERO | BDRV_BLOCK_DATA)) {
2383 break;
2384 }
2385 /* [offset, pnum] unallocated on this layer, which could be only
2386 * the first part of [offset, bytes]. */
2387 bytes = MIN(bytes, *pnum);
2388 first = false;
2389 }
2390 return ret;
2391}
2392
2393/* Coroutine wrapper for bdrv_block_status_above() */
2394static void coroutine_fn bdrv_block_status_above_co_entry(void *opaque)
2395{
2396 BdrvCoBlockStatusData *data = opaque;
2397
2398 data->ret = bdrv_co_block_status_above(data->bs, data->base,
2399 data->want_zero,
2400 data->offset, data->bytes,
2401 data->pnum, data->map, data->file);
2402 data->done = true;
2403 aio_wait_kick();
2404}
2405
2406/*
2407 * Synchronous wrapper around bdrv_co_block_status_above().
2408 *
2409 * See bdrv_co_block_status_above() for details.
2410 */
2411static int bdrv_common_block_status_above(BlockDriverState *bs,
2412 BlockDriverState *base,
2413 bool want_zero, int64_t offset,
2414 int64_t bytes, int64_t *pnum,
2415 int64_t *map,
2416 BlockDriverState **file)
2417{
2418 Coroutine *co;
2419 BdrvCoBlockStatusData data = {
2420 .bs = bs,
2421 .base = base,
2422 .want_zero = want_zero,
2423 .offset = offset,
2424 .bytes = bytes,
2425 .pnum = pnum,
2426 .map = map,
2427 .file = file,
2428 .done = false,
2429 };
2430
2431 if (qemu_in_coroutine()) {
2432 /* Fast-path if already in coroutine context */
2433 bdrv_block_status_above_co_entry(&data);
2434 } else {
2435 co = qemu_coroutine_create(bdrv_block_status_above_co_entry, &data);
2436 bdrv_coroutine_enter(bs, co);
2437 BDRV_POLL_WHILE(bs, !data.done);
2438 }
2439 return data.ret;
2440}
2441
2442int bdrv_block_status_above(BlockDriverState *bs, BlockDriverState *base,
2443 int64_t offset, int64_t bytes, int64_t *pnum,
2444 int64_t *map, BlockDriverState **file)
2445{
2446 return bdrv_common_block_status_above(bs, base, true, offset, bytes,
2447 pnum, map, file);
2448}
2449
2450int bdrv_block_status(BlockDriverState *bs, int64_t offset, int64_t bytes,
2451 int64_t *pnum, int64_t *map, BlockDriverState **file)
2452{
2453 return bdrv_block_status_above(bs, backing_bs(bs),
2454 offset, bytes, pnum, map, file);
2455}
2456
2457int coroutine_fn bdrv_is_allocated(BlockDriverState *bs, int64_t offset,
2458 int64_t bytes, int64_t *pnum)
2459{
2460 int ret;
2461 int64_t dummy;
2462
2463 ret = bdrv_common_block_status_above(bs, backing_bs(bs), false, offset,
2464 bytes, pnum ? pnum : &dummy, NULL,
2465 NULL);
2466 if (ret < 0) {
2467 return ret;
2468 }
2469 return !!(ret & BDRV_BLOCK_ALLOCATED);
2470}
2471
2472/*
2473 * Given an image chain: ... -> [BASE] -> [INTER1] -> [INTER2] -> [TOP]
2474 *
2475 * Return 1 if (a prefix of) the given range is allocated in any image
2476 * between BASE and TOP (BASE is only included if include_base is set).
2477 * BASE can be NULL to check if the given offset is allocated in any
2478 * image of the chain. Return 0 otherwise, or negative errno on
2479 * failure.
2480 *
2481 * 'pnum' is set to the number of bytes (including and immediately
2482 * following the specified offset) that are known to be in the same
2483 * allocated/unallocated state. Note that a subsequent call starting
2484 * at 'offset + *pnum' may return the same allocation status (in other
2485 * words, the result is not necessarily the maximum possible range);
2486 * but 'pnum' will only be 0 when end of file is reached.
2487 *
2488 */
2489int bdrv_is_allocated_above(BlockDriverState *top,
2490 BlockDriverState *base,
2491 bool include_base, int64_t offset,
2492 int64_t bytes, int64_t *pnum)
2493{
2494 BlockDriverState *intermediate;
2495 int ret;
2496 int64_t n = bytes;
2497
2498 assert(base || !include_base);
2499
2500 intermediate = top;
2501 while (include_base || intermediate != base) {
2502 int64_t pnum_inter;
2503 int64_t size_inter;
2504
2505 assert(intermediate);
2506 ret = bdrv_is_allocated(intermediate, offset, bytes, &pnum_inter);
2507 if (ret < 0) {
2508 return ret;
2509 }
2510 if (ret) {
2511 *pnum = pnum_inter;
2512 return 1;
2513 }
2514
2515 size_inter = bdrv_getlength(intermediate);
2516 if (size_inter < 0) {
2517 return size_inter;
2518 }
2519 if (n > pnum_inter &&
2520 (intermediate == top || offset + pnum_inter < size_inter)) {
2521 n = pnum_inter;
2522 }
2523
2524 if (intermediate == base) {
2525 break;
2526 }
2527
2528 intermediate = backing_bs(intermediate);
2529 }
2530
2531 *pnum = n;
2532 return 0;
2533}
2534
2535typedef struct BdrvVmstateCo {
2536 BlockDriverState *bs;
2537 QEMUIOVector *qiov;
2538 int64_t pos;
2539 bool is_read;
2540 int ret;
2541} BdrvVmstateCo;
2542
2543static int coroutine_fn
2544bdrv_co_rw_vmstate(BlockDriverState *bs, QEMUIOVector *qiov, int64_t pos,
2545 bool is_read)
2546{
2547 BlockDriver *drv = bs->drv;
2548 int ret = -ENOTSUP;
2549
2550 bdrv_inc_in_flight(bs);
2551
2552 if (!drv) {
2553 ret = -ENOMEDIUM;
2554 } else if (drv->bdrv_load_vmstate) {
2555 if (is_read) {
2556 ret = drv->bdrv_load_vmstate(bs, qiov, pos);
2557 } else {
2558 ret = drv->bdrv_save_vmstate(bs, qiov, pos);
2559 }
2560 } else if (bs->file) {
2561 ret = bdrv_co_rw_vmstate(bs->file->bs, qiov, pos, is_read);
2562 }
2563
2564 bdrv_dec_in_flight(bs);
2565 return ret;
2566}
2567
2568static void coroutine_fn bdrv_co_rw_vmstate_entry(void *opaque)
2569{
2570 BdrvVmstateCo *co = opaque;
2571 co->ret = bdrv_co_rw_vmstate(co->bs, co->qiov, co->pos, co->is_read);
2572 aio_wait_kick();
2573}
2574
2575static inline int
2576bdrv_rw_vmstate(BlockDriverState *bs, QEMUIOVector *qiov, int64_t pos,
2577 bool is_read)
2578{
2579 if (qemu_in_coroutine()) {
2580 return bdrv_co_rw_vmstate(bs, qiov, pos, is_read);
2581 } else {
2582 BdrvVmstateCo data = {
2583 .bs = bs,
2584 .qiov = qiov,
2585 .pos = pos,
2586 .is_read = is_read,
2587 .ret = -EINPROGRESS,
2588 };
2589 Coroutine *co = qemu_coroutine_create(bdrv_co_rw_vmstate_entry, &data);
2590
2591 bdrv_coroutine_enter(bs, co);
2592 BDRV_POLL_WHILE(bs, data.ret == -EINPROGRESS);
2593 return data.ret;
2594 }
2595}
2596
2597int bdrv_save_vmstate(BlockDriverState *bs, const uint8_t *buf,
2598 int64_t pos, int size)
2599{
2600 QEMUIOVector qiov = QEMU_IOVEC_INIT_BUF(qiov, buf, size);
2601 int ret;
2602
2603 ret = bdrv_writev_vmstate(bs, &qiov, pos);
2604 if (ret < 0) {
2605 return ret;
2606 }
2607
2608 return size;
2609}
2610
2611int bdrv_writev_vmstate(BlockDriverState *bs, QEMUIOVector *qiov, int64_t pos)
2612{
2613 return bdrv_rw_vmstate(bs, qiov, pos, false);
2614}
2615
2616int bdrv_load_vmstate(BlockDriverState *bs, uint8_t *buf,
2617 int64_t pos, int size)
2618{
2619 QEMUIOVector qiov = QEMU_IOVEC_INIT_BUF(qiov, buf, size);
2620 int ret;
2621
2622 ret = bdrv_readv_vmstate(bs, &qiov, pos);
2623 if (ret < 0) {
2624 return ret;
2625 }
2626
2627 return size;
2628}
2629
2630int bdrv_readv_vmstate(BlockDriverState *bs, QEMUIOVector *qiov, int64_t pos)
2631{
2632 return bdrv_rw_vmstate(bs, qiov, pos, true);
2633}
2634
2635/**************************************************************/
2636/* async I/Os */
2637
2638void bdrv_aio_cancel(BlockAIOCB *acb)
2639{
2640 qemu_aio_ref(acb);
2641 bdrv_aio_cancel_async(acb);
2642 while (acb->refcnt > 1) {
2643 if (acb->aiocb_info->get_aio_context) {
2644 aio_poll(acb->aiocb_info->get_aio_context(acb), true);
2645 } else if (acb->bs) {
2646 /* qemu_aio_ref and qemu_aio_unref are not thread-safe, so
2647 * assert that we're not using an I/O thread. Thread-safe
2648 * code should use bdrv_aio_cancel_async exclusively.
2649 */
2650 assert(bdrv_get_aio_context(acb->bs) == qemu_get_aio_context());
2651 aio_poll(bdrv_get_aio_context(acb->bs), true);
2652 } else {
2653 abort();
2654 }
2655 }
2656 qemu_aio_unref(acb);
2657}
2658
2659/* Async version of aio cancel. The caller is not blocked if the acb implements
2660 * cancel_async, otherwise we do nothing and let the request normally complete.
2661 * In either case the completion callback must be called. */
2662void bdrv_aio_cancel_async(BlockAIOCB *acb)
2663{
2664 if (acb->aiocb_info->cancel_async) {
2665 acb->aiocb_info->cancel_async(acb);
2666 }
2667}
2668
2669/**************************************************************/
2670/* Coroutine block device emulation */
2671
2672typedef struct FlushCo {
2673 BlockDriverState *bs;
2674 int ret;
2675} FlushCo;
2676
2677
2678static void coroutine_fn bdrv_flush_co_entry(void *opaque)
2679{
2680 FlushCo *rwco = opaque;
2681
2682 rwco->ret = bdrv_co_flush(rwco->bs);
2683 aio_wait_kick();
2684}
2685
2686int coroutine_fn bdrv_co_flush(BlockDriverState *bs)
2687{
2688 int current_gen;
2689 int ret = 0;
2690
2691 bdrv_inc_in_flight(bs);
2692
2693 if (!bdrv_is_inserted(bs) || bdrv_is_read_only(bs) ||
2694 bdrv_is_sg(bs)) {
2695 goto early_exit;
2696 }
2697
2698 qemu_co_mutex_lock(&bs->reqs_lock);
2699 current_gen = atomic_read(&bs->write_gen);
2700
2701 /* Wait until any previous flushes are completed */
2702 while (bs->active_flush_req) {
2703 qemu_co_queue_wait(&bs->flush_queue, &bs->reqs_lock);
2704 }
2705
2706 /* Flushes reach this point in nondecreasing current_gen order. */
2707 bs->active_flush_req = true;
2708 qemu_co_mutex_unlock(&bs->reqs_lock);
2709
2710 /* Write back all layers by calling one driver function */
2711 if (bs->drv->bdrv_co_flush) {
2712 ret = bs->drv->bdrv_co_flush(bs);
2713 goto out;
2714 }
2715
2716 /* Write back cached data to the OS even with cache=unsafe */
2717 BLKDBG_EVENT(bs->file, BLKDBG_FLUSH_TO_OS);
2718 if (bs->drv->bdrv_co_flush_to_os) {
2719 ret = bs->drv->bdrv_co_flush_to_os(bs);
2720 if (ret < 0) {
2721 goto out;
2722 }
2723 }
2724
2725 /* But don't actually force it to the disk with cache=unsafe */
2726 if (bs->open_flags & BDRV_O_NO_FLUSH) {
2727 goto flush_parent;
2728 }
2729
2730 /* Check if we really need to flush anything */
2731 if (bs->flushed_gen == current_gen) {
2732 goto flush_parent;
2733 }
2734
2735 BLKDBG_EVENT(bs->file, BLKDBG_FLUSH_TO_DISK);
2736 if (!bs->drv) {
2737 /* bs->drv->bdrv_co_flush() might have ejected the BDS
2738 * (even in case of apparent success) */
2739 ret = -ENOMEDIUM;
2740 goto out;
2741 }
2742 if (bs->drv->bdrv_co_flush_to_disk) {
2743 ret = bs->drv->bdrv_co_flush_to_disk(bs);
2744 } else if (bs->drv->bdrv_aio_flush) {
2745 BlockAIOCB *acb;
2746 CoroutineIOCompletion co = {
2747 .coroutine = qemu_coroutine_self(),
2748 };
2749
2750 acb = bs->drv->bdrv_aio_flush(bs, bdrv_co_io_em_complete, &co);
2751 if (acb == NULL) {
2752 ret = -EIO;
2753 } else {
2754 qemu_coroutine_yield();
2755 ret = co.ret;
2756 }
2757 } else {
2758 /*
2759 * Some block drivers always operate in either writethrough or unsafe
2760 * mode and don't support bdrv_flush therefore. Usually qemu doesn't
2761 * know how the server works (because the behaviour is hardcoded or
2762 * depends on server-side configuration), so we can't ensure that
2763 * everything is safe on disk. Returning an error doesn't work because
2764 * that would break guests even if the server operates in writethrough
2765 * mode.
2766 *
2767 * Let's hope the user knows what he's doing.
2768 */
2769 ret = 0;
2770 }
2771
2772 if (ret < 0) {
2773 goto out;
2774 }
2775
2776 /* Now flush the underlying protocol. It will also have BDRV_O_NO_FLUSH
2777 * in the case of cache=unsafe, so there are no useless flushes.
2778 */
2779flush_parent:
2780 ret = bs->file ? bdrv_co_flush(bs->file->bs) : 0;
2781out:
2782 /* Notify any pending flushes that we have completed */
2783 if (ret == 0) {
2784 bs->flushed_gen = current_gen;
2785 }
2786
2787 qemu_co_mutex_lock(&bs->reqs_lock);
2788 bs->active_flush_req = false;
2789 /* Return value is ignored - it's ok if wait queue is empty */
2790 qemu_co_queue_next(&bs->flush_queue);
2791 qemu_co_mutex_unlock(&bs->reqs_lock);
2792
2793early_exit:
2794 bdrv_dec_in_flight(bs);
2795 return ret;
2796}
2797
2798int bdrv_flush(BlockDriverState *bs)
2799{
2800 Coroutine *co;
2801 FlushCo flush_co = {
2802 .bs = bs,
2803 .ret = NOT_DONE,
2804 };
2805
2806 if (qemu_in_coroutine()) {
2807 /* Fast-path if already in coroutine context */
2808 bdrv_flush_co_entry(&flush_co);
2809 } else {
2810 co = qemu_coroutine_create(bdrv_flush_co_entry, &flush_co);
2811 bdrv_coroutine_enter(bs, co);
2812 BDRV_POLL_WHILE(bs, flush_co.ret == NOT_DONE);
2813 }
2814
2815 return flush_co.ret;
2816}
2817
2818typedef struct DiscardCo {
2819 BdrvChild *child;
2820 int64_t offset;
2821 int64_t bytes;
2822 int ret;
2823} DiscardCo;
2824static void coroutine_fn bdrv_pdiscard_co_entry(void *opaque)
2825{
2826 DiscardCo *rwco = opaque;
2827
2828 rwco->ret = bdrv_co_pdiscard(rwco->child, rwco->offset, rwco->bytes);
2829 aio_wait_kick();
2830}
2831
2832int coroutine_fn bdrv_co_pdiscard(BdrvChild *child, int64_t offset,
2833 int64_t bytes)
2834{
2835 BdrvTrackedRequest req;
2836 int max_pdiscard, ret;
2837 int head, tail, align;
2838 BlockDriverState *bs = child->bs;
2839
2840 if (!bs || !bs->drv || !bdrv_is_inserted(bs)) {
2841 return -ENOMEDIUM;
2842 }
2843
2844 if (bdrv_has_readonly_bitmaps(bs)) {
2845 return -EPERM;
2846 }
2847
2848 if (offset < 0 || bytes < 0 || bytes > INT64_MAX - offset) {
2849 return -EIO;
2850 }
2851
2852 /* Do nothing if disabled. */
2853 if (!(bs->open_flags & BDRV_O_UNMAP)) {
2854 return 0;
2855 }
2856
2857 if (!bs->drv->bdrv_co_pdiscard && !bs->drv->bdrv_aio_pdiscard) {
2858 return 0;
2859 }
2860
2861 /* Discard is advisory, but some devices track and coalesce
2862 * unaligned requests, so we must pass everything down rather than
2863 * round here. Still, most devices will just silently ignore
2864 * unaligned requests (by returning -ENOTSUP), so we must fragment
2865 * the request accordingly. */
2866 align = MAX(bs->bl.pdiscard_alignment, bs->bl.request_alignment);
2867 assert(align % bs->bl.request_alignment == 0);
2868 head = offset % align;
2869 tail = (offset + bytes) % align;
2870
2871 bdrv_inc_in_flight(bs);
2872 tracked_request_begin(&req, bs, offset, bytes, BDRV_TRACKED_DISCARD);
2873
2874 ret = bdrv_co_write_req_prepare(child, offset, bytes, &req, 0);
2875 if (ret < 0) {
2876 goto out;
2877 }
2878
2879 max_pdiscard = QEMU_ALIGN_DOWN(MIN_NON_ZERO(bs->bl.max_pdiscard, INT_MAX),
2880 align);
2881 assert(max_pdiscard >= bs->bl.request_alignment);
2882
2883 while (bytes > 0) {
2884 int64_t num = bytes;
2885
2886 if (head) {
2887 /* Make small requests to get to alignment boundaries. */
2888 num = MIN(bytes, align - head);
2889 if (!QEMU_IS_ALIGNED(num, bs->bl.request_alignment)) {
2890 num %= bs->bl.request_alignment;
2891 }
2892 head = (head + num) % align;
2893 assert(num < max_pdiscard);
2894 } else if (tail) {
2895 if (num > align) {
2896 /* Shorten the request to the last aligned cluster. */
2897 num -= tail;
2898 } else if (!QEMU_IS_ALIGNED(tail, bs->bl.request_alignment) &&
2899 tail > bs->bl.request_alignment) {
2900 tail %= bs->bl.request_alignment;
2901 num -= tail;
2902 }
2903 }
2904 /* limit request size */
2905 if (num > max_pdiscard) {
2906 num = max_pdiscard;
2907 }
2908
2909 if (!bs->drv) {
2910 ret = -ENOMEDIUM;
2911 goto out;
2912 }
2913 if (bs->drv->bdrv_co_pdiscard) {
2914 ret = bs->drv->bdrv_co_pdiscard(bs, offset, num);
2915 } else {
2916 BlockAIOCB *acb;
2917 CoroutineIOCompletion co = {
2918 .coroutine = qemu_coroutine_self(),
2919 };
2920
2921 acb = bs->drv->bdrv_aio_pdiscard(bs, offset, num,
2922 bdrv_co_io_em_complete, &co);
2923 if (acb == NULL) {
2924 ret = -EIO;
2925 goto out;
2926 } else {
2927 qemu_coroutine_yield();
2928 ret = co.ret;
2929 }
2930 }
2931 if (ret && ret != -ENOTSUP) {
2932 goto out;
2933 }
2934
2935 offset += num;
2936 bytes -= num;
2937 }
2938 ret = 0;
2939out:
2940 bdrv_co_write_req_finish(child, req.offset, req.bytes, &req, ret);
2941 tracked_request_end(&req);
2942 bdrv_dec_in_flight(bs);
2943 return ret;
2944}
2945
2946int bdrv_pdiscard(BdrvChild *child, int64_t offset, int64_t bytes)
2947{
2948 Coroutine *co;
2949 DiscardCo rwco = {
2950 .child = child,
2951 .offset = offset,
2952 .bytes = bytes,
2953 .ret = NOT_DONE,
2954 };
2955
2956 if (qemu_in_coroutine()) {
2957 /* Fast-path if already in coroutine context */
2958 bdrv_pdiscard_co_entry(&rwco);
2959 } else {
2960 co = qemu_coroutine_create(bdrv_pdiscard_co_entry, &rwco);
2961 bdrv_coroutine_enter(child->bs, co);
2962 BDRV_POLL_WHILE(child->bs, rwco.ret == NOT_DONE);
2963 }
2964
2965 return rwco.ret;
2966}
2967
2968int bdrv_co_ioctl(BlockDriverState *bs, int req, void *buf)
2969{
2970 BlockDriver *drv = bs->drv;
2971 CoroutineIOCompletion co = {
2972 .coroutine = qemu_coroutine_self(),
2973 };
2974 BlockAIOCB *acb;
2975
2976 bdrv_inc_in_flight(bs);
2977 if (!drv || (!drv->bdrv_aio_ioctl && !drv->bdrv_co_ioctl)) {
2978 co.ret = -ENOTSUP;
2979 goto out;
2980 }
2981
2982 if (drv->bdrv_co_ioctl) {
2983 co.ret = drv->bdrv_co_ioctl(bs, req, buf);
2984 } else {
2985 acb = drv->bdrv_aio_ioctl(bs, req, buf, bdrv_co_io_em_complete, &co);
2986 if (!acb) {
2987 co.ret = -ENOTSUP;
2988 goto out;
2989 }
2990 qemu_coroutine_yield();
2991 }
2992out:
2993 bdrv_dec_in_flight(bs);
2994 return co.ret;
2995}
2996
2997void *qemu_blockalign(BlockDriverState *bs, size_t size)
2998{
2999 return qemu_memalign(bdrv_opt_mem_align(bs), size);
3000}
3001
3002void *qemu_blockalign0(BlockDriverState *bs, size_t size)
3003{
3004 return memset(qemu_blockalign(bs, size), 0, size);
3005}
3006
3007void *qemu_try_blockalign(BlockDriverState *bs, size_t size)
3008{
3009 size_t align = bdrv_opt_mem_align(bs);
3010
3011 /* Ensure that NULL is never returned on success */
3012 assert(align > 0);
3013 if (size == 0) {
3014 size = align;
3015 }
3016
3017 return qemu_try_memalign(align, size);
3018}
3019
3020void *qemu_try_blockalign0(BlockDriverState *bs, size_t size)
3021{
3022 void *mem = qemu_try_blockalign(bs, size);
3023
3024 if (mem) {
3025 memset(mem, 0, size);
3026 }
3027
3028 return mem;
3029}
3030
3031/*
3032 * Check if all memory in this vector is sector aligned.
3033 */
3034bool bdrv_qiov_is_aligned(BlockDriverState *bs, QEMUIOVector *qiov)
3035{
3036 int i;
3037 size_t alignment = bdrv_min_mem_align(bs);
3038
3039 for (i = 0; i < qiov->niov; i++) {
3040 if ((uintptr_t) qiov->iov[i].iov_base % alignment) {
3041 return false;
3042 }
3043 if (qiov->iov[i].iov_len % alignment) {
3044 return false;
3045 }
3046 }
3047
3048 return true;
3049}
3050
3051void bdrv_add_before_write_notifier(BlockDriverState *bs,
3052 NotifierWithReturn *notifier)
3053{
3054 notifier_with_return_list_add(&bs->before_write_notifiers, notifier);
3055}
3056
3057void bdrv_io_plug(BlockDriverState *bs)
3058{
3059 BdrvChild *child;
3060
3061 QLIST_FOREACH(child, &bs->children, next) {
3062 bdrv_io_plug(child->bs);
3063 }
3064
3065 if (atomic_fetch_inc(&bs->io_plugged) == 0) {
3066 BlockDriver *drv = bs->drv;
3067 if (drv && drv->bdrv_io_plug) {
3068 drv->bdrv_io_plug(bs);
3069 }
3070 }
3071}
3072
3073void bdrv_io_unplug(BlockDriverState *bs)
3074{
3075 BdrvChild *child;
3076
3077 assert(bs->io_plugged);
3078 if (atomic_fetch_dec(&bs->io_plugged) == 1) {
3079 BlockDriver *drv = bs->drv;
3080 if (drv && drv->bdrv_io_unplug) {
3081 drv->bdrv_io_unplug(bs);
3082 }
3083 }
3084
3085 QLIST_FOREACH(child, &bs->children, next) {
3086 bdrv_io_unplug(child->bs);
3087 }
3088}
3089
3090void bdrv_register_buf(BlockDriverState *bs, void *host, size_t size)
3091{
3092 BdrvChild *child;
3093
3094 if (bs->drv && bs->drv->bdrv_register_buf) {
3095 bs->drv->bdrv_register_buf(bs, host, size);
3096 }
3097 QLIST_FOREACH(child, &bs->children, next) {
3098 bdrv_register_buf(child->bs, host, size);
3099 }
3100}
3101
3102void bdrv_unregister_buf(BlockDriverState *bs, void *host)
3103{
3104 BdrvChild *child;
3105
3106 if (bs->drv && bs->drv->bdrv_unregister_buf) {
3107 bs->drv->bdrv_unregister_buf(bs, host);
3108 }
3109 QLIST_FOREACH(child, &bs->children, next) {
3110 bdrv_unregister_buf(child->bs, host);
3111 }
3112}
3113
3114static int coroutine_fn bdrv_co_copy_range_internal(
3115 BdrvChild *src, uint64_t src_offset, BdrvChild *dst,
3116 uint64_t dst_offset, uint64_t bytes,
3117 BdrvRequestFlags read_flags, BdrvRequestFlags write_flags,
3118 bool recurse_src)
3119{
3120 BdrvTrackedRequest req;
3121 int ret;
3122
3123 /* TODO We can support BDRV_REQ_NO_FALLBACK here */
3124 assert(!(read_flags & BDRV_REQ_NO_FALLBACK));
3125 assert(!(write_flags & BDRV_REQ_NO_FALLBACK));
3126
3127 if (!dst || !dst->bs) {
3128 return -ENOMEDIUM;
3129 }
3130 ret = bdrv_check_byte_request(dst->bs, dst_offset, bytes);
3131 if (ret) {
3132 return ret;
3133 }
3134 if (write_flags & BDRV_REQ_ZERO_WRITE) {
3135 return bdrv_co_pwrite_zeroes(dst, dst_offset, bytes, write_flags);
3136 }
3137
3138 if (!src || !src->bs) {
3139 return -ENOMEDIUM;
3140 }
3141 ret = bdrv_check_byte_request(src->bs, src_offset, bytes);
3142 if (ret) {
3143 return ret;
3144 }
3145
3146 if (!src->bs->drv->bdrv_co_copy_range_from
3147 || !dst->bs->drv->bdrv_co_copy_range_to
3148 || src->bs->encrypted || dst->bs->encrypted) {
3149 return -ENOTSUP;
3150 }
3151
3152 if (recurse_src) {
3153 bdrv_inc_in_flight(src->bs);
3154 tracked_request_begin(&req, src->bs, src_offset, bytes,
3155 BDRV_TRACKED_READ);
3156
3157 /* BDRV_REQ_SERIALISING is only for write operation */
3158 assert(!(read_flags & BDRV_REQ_SERIALISING));
3159 if (!(read_flags & BDRV_REQ_NO_SERIALISING)) {
3160 wait_serialising_requests(&req);
3161 }
3162
3163 ret = src->bs->drv->bdrv_co_copy_range_from(src->bs,
3164 src, src_offset,
3165 dst, dst_offset,
3166 bytes,
3167 read_flags, write_flags);
3168
3169 tracked_request_end(&req);
3170 bdrv_dec_in_flight(src->bs);
3171 } else {
3172 bdrv_inc_in_flight(dst->bs);
3173 tracked_request_begin(&req, dst->bs, dst_offset, bytes,
3174 BDRV_TRACKED_WRITE);
3175 ret = bdrv_co_write_req_prepare(dst, dst_offset, bytes, &req,
3176 write_flags);
3177 if (!ret) {
3178 ret = dst->bs->drv->bdrv_co_copy_range_to(dst->bs,
3179 src, src_offset,
3180 dst, dst_offset,
3181 bytes,
3182 read_flags, write_flags);
3183 }
3184 bdrv_co_write_req_finish(dst, dst_offset, bytes, &req, ret);
3185 tracked_request_end(&req);
3186 bdrv_dec_in_flight(dst->bs);
3187 }
3188
3189 return ret;
3190}
3191
3192/* Copy range from @src to @dst.
3193 *
3194 * See the comment of bdrv_co_copy_range for the parameter and return value
3195 * semantics. */
3196int coroutine_fn bdrv_co_copy_range_from(BdrvChild *src, uint64_t src_offset,
3197 BdrvChild *dst, uint64_t dst_offset,
3198 uint64_t bytes,
3199 BdrvRequestFlags read_flags,
3200 BdrvRequestFlags write_flags)
3201{
3202 trace_bdrv_co_copy_range_from(src, src_offset, dst, dst_offset, bytes,
3203 read_flags, write_flags);
3204 return bdrv_co_copy_range_internal(src, src_offset, dst, dst_offset,
3205 bytes, read_flags, write_flags, true);
3206}
3207
3208/* Copy range from @src to @dst.
3209 *
3210 * See the comment of bdrv_co_copy_range for the parameter and return value
3211 * semantics. */
3212int coroutine_fn bdrv_co_copy_range_to(BdrvChild *src, uint64_t src_offset,
3213 BdrvChild *dst, uint64_t dst_offset,
3214 uint64_t bytes,
3215 BdrvRequestFlags read_flags,
3216 BdrvRequestFlags write_flags)
3217{
3218 trace_bdrv_co_copy_range_to(src, src_offset, dst, dst_offset, bytes,
3219 read_flags, write_flags);
3220 return bdrv_co_copy_range_internal(src, src_offset, dst, dst_offset,
3221 bytes, read_flags, write_flags, false);
3222}
3223
3224int coroutine_fn bdrv_co_copy_range(BdrvChild *src, uint64_t src_offset,
3225 BdrvChild *dst, uint64_t dst_offset,
3226 uint64_t bytes, BdrvRequestFlags read_flags,
3227 BdrvRequestFlags write_flags)
3228{
3229 return bdrv_co_copy_range_from(src, src_offset,
3230 dst, dst_offset,
3231 bytes, read_flags, write_flags);
3232}
3233
3234static void bdrv_parent_cb_resize(BlockDriverState *bs)
3235{
3236 BdrvChild *c;
3237 QLIST_FOREACH(c, &bs->parents, next_parent) {
3238 if (c->role->resize) {
3239 c->role->resize(c);
3240 }
3241 }
3242}
3243
3244/**
3245 * Truncate file to 'offset' bytes (needed only for file protocols)
3246 */
3247int coroutine_fn bdrv_co_truncate(BdrvChild *child, int64_t offset,
3248 PreallocMode prealloc, Error **errp)
3249{
3250 BlockDriverState *bs = child->bs;
3251 BlockDriver *drv = bs->drv;
3252 BdrvTrackedRequest req;
3253 int64_t old_size, new_bytes;
3254 int ret;
3255
3256
3257 /* if bs->drv == NULL, bs is closed, so there's nothing to do here */
3258 if (!drv) {
3259 error_setg(errp, "No medium inserted");
3260 return -ENOMEDIUM;
3261 }
3262 if (offset < 0) {
3263 error_setg(errp, "Image size cannot be negative");
3264 return -EINVAL;
3265 }
3266
3267 old_size = bdrv_getlength(bs);
3268 if (old_size < 0) {
3269 error_setg_errno(errp, -old_size, "Failed to get old image size");
3270 return old_size;
3271 }
3272
3273 if (offset > old_size) {
3274 new_bytes = offset - old_size;
3275 } else {
3276 new_bytes = 0;
3277 }
3278
3279 bdrv_inc_in_flight(bs);
3280 tracked_request_begin(&req, bs, offset - new_bytes, new_bytes,
3281 BDRV_TRACKED_TRUNCATE);
3282
3283 /* If we are growing the image and potentially using preallocation for the
3284 * new area, we need to make sure that no write requests are made to it
3285 * concurrently or they might be overwritten by preallocation. */
3286 if (new_bytes) {
3287 mark_request_serialising(&req, 1);
3288 }
3289 if (bs->read_only) {
3290 error_setg(errp, "Image is read-only");
3291 ret = -EACCES;
3292 goto out;
3293 }
3294 ret = bdrv_co_write_req_prepare(child, offset - new_bytes, new_bytes, &req,
3295 0);
3296 if (ret < 0) {
3297 error_setg_errno(errp, -ret,
3298 "Failed to prepare request for truncation");
3299 goto out;
3300 }
3301
3302 if (!drv->bdrv_co_truncate) {
3303 if (bs->file && drv->is_filter) {
3304 ret = bdrv_co_truncate(bs->file, offset, prealloc, errp);
3305 goto out;
3306 }
3307 error_setg(errp, "Image format driver does not support resize");
3308 ret = -ENOTSUP;
3309 goto out;
3310 }
3311
3312 ret = drv->bdrv_co_truncate(bs, offset, prealloc, errp);
3313 if (ret < 0) {
3314 goto out;
3315 }
3316 ret = refresh_total_sectors(bs, offset >> BDRV_SECTOR_BITS);
3317 if (ret < 0) {
3318 error_setg_errno(errp, -ret, "Could not refresh total sector count");
3319 } else {
3320 offset = bs->total_sectors * BDRV_SECTOR_SIZE;
3321 }
3322 /* It's possible that truncation succeeded but refresh_total_sectors
3323 * failed, but the latter doesn't affect how we should finish the request.
3324 * Pass 0 as the last parameter so that dirty bitmaps etc. are handled. */
3325 bdrv_co_write_req_finish(child, offset - new_bytes, new_bytes, &req, 0);
3326
3327out:
3328 tracked_request_end(&req);
3329 bdrv_dec_in_flight(bs);
3330
3331 return ret;
3332}
3333
3334typedef struct TruncateCo {
3335 BdrvChild *child;
3336 int64_t offset;
3337 PreallocMode prealloc;
3338 Error **errp;
3339 int ret;
3340} TruncateCo;
3341
3342static void coroutine_fn bdrv_truncate_co_entry(void *opaque)
3343{
3344 TruncateCo *tco = opaque;
3345 tco->ret = bdrv_co_truncate(tco->child, tco->offset, tco->prealloc,
3346 tco->errp);
3347 aio_wait_kick();
3348}
3349
3350int bdrv_truncate(BdrvChild *child, int64_t offset, PreallocMode prealloc,
3351 Error **errp)
3352{
3353 Coroutine *co;
3354 TruncateCo tco = {
3355 .child = child,
3356 .offset = offset,
3357 .prealloc = prealloc,
3358 .errp = errp,
3359 .ret = NOT_DONE,
3360 };
3361
3362 if (qemu_in_coroutine()) {
3363 /* Fast-path if already in coroutine context */
3364 bdrv_truncate_co_entry(&tco);
3365 } else {
3366 co = qemu_coroutine_create(bdrv_truncate_co_entry, &tco);
3367 bdrv_coroutine_enter(child->bs, co);
3368 BDRV_POLL_WHILE(child->bs, tco.ret == NOT_DONE);
3369 }
3370
3371 return tco.ret;
3372}
3373