1/*
2 * Block driver for the QCOW version 2 format
3 *
4 * Copyright (c) 2004-2006 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 <zlib.h>
27
28#include "qapi/error.h"
29#include "qcow2.h"
30#include "qemu/bswap.h"
31#include "trace.h"
32
33int qcow2_shrink_l1_table(BlockDriverState *bs, uint64_t exact_size)
34{
35 BDRVQcow2State *s = bs->opaque;
36 int new_l1_size, i, ret;
37
38 if (exact_size >= s->l1_size) {
39 return 0;
40 }
41
42 new_l1_size = exact_size;
43
44#ifdef DEBUG_ALLOC2
45 fprintf(stderr, "shrink l1_table from %d to %d\n", s->l1_size, new_l1_size);
46#endif
47
48 BLKDBG_EVENT(bs->file, BLKDBG_L1_SHRINK_WRITE_TABLE);
49 ret = bdrv_pwrite_zeroes(bs->file, s->l1_table_offset +
50 new_l1_size * sizeof(uint64_t),
51 (s->l1_size - new_l1_size) * sizeof(uint64_t), 0);
52 if (ret < 0) {
53 goto fail;
54 }
55
56 ret = bdrv_flush(bs->file->bs);
57 if (ret < 0) {
58 goto fail;
59 }
60
61 BLKDBG_EVENT(bs->file, BLKDBG_L1_SHRINK_FREE_L2_CLUSTERS);
62 for (i = s->l1_size - 1; i > new_l1_size - 1; i--) {
63 if ((s->l1_table[i] & L1E_OFFSET_MASK) == 0) {
64 continue;
65 }
66 qcow2_free_clusters(bs, s->l1_table[i] & L1E_OFFSET_MASK,
67 s->cluster_size, QCOW2_DISCARD_ALWAYS);
68 s->l1_table[i] = 0;
69 }
70 return 0;
71
72fail:
73 /*
74 * If the write in the l1_table failed the image may contain a partially
75 * overwritten l1_table. In this case it would be better to clear the
76 * l1_table in memory to avoid possible image corruption.
77 */
78 memset(s->l1_table + new_l1_size, 0,
79 (s->l1_size - new_l1_size) * sizeof(uint64_t));
80 return ret;
81}
82
83int qcow2_grow_l1_table(BlockDriverState *bs, uint64_t min_size,
84 bool exact_size)
85{
86 BDRVQcow2State *s = bs->opaque;
87 int new_l1_size2, ret, i;
88 uint64_t *new_l1_table;
89 int64_t old_l1_table_offset, old_l1_size;
90 int64_t new_l1_table_offset, new_l1_size;
91 uint8_t data[12];
92
93 if (min_size <= s->l1_size)
94 return 0;
95
96 /* Do a sanity check on min_size before trying to calculate new_l1_size
97 * (this prevents overflows during the while loop for the calculation of
98 * new_l1_size) */
99 if (min_size > INT_MAX / sizeof(uint64_t)) {
100 return -EFBIG;
101 }
102
103 if (exact_size) {
104 new_l1_size = min_size;
105 } else {
106 /* Bump size up to reduce the number of times we have to grow */
107 new_l1_size = s->l1_size;
108 if (new_l1_size == 0) {
109 new_l1_size = 1;
110 }
111 while (min_size > new_l1_size) {
112 new_l1_size = DIV_ROUND_UP(new_l1_size * 3, 2);
113 }
114 }
115
116 QEMU_BUILD_BUG_ON(QCOW_MAX_L1_SIZE > INT_MAX);
117 if (new_l1_size > QCOW_MAX_L1_SIZE / sizeof(uint64_t)) {
118 return -EFBIG;
119 }
120
121#ifdef DEBUG_ALLOC2
122 fprintf(stderr, "grow l1_table from %d to %" PRId64 "\n",
123 s->l1_size, new_l1_size);
124#endif
125
126 new_l1_size2 = sizeof(uint64_t) * new_l1_size;
127 new_l1_table = qemu_try_blockalign(bs->file->bs,
128 ROUND_UP(new_l1_size2, 512));
129 if (new_l1_table == NULL) {
130 return -ENOMEM;
131 }
132 memset(new_l1_table, 0, ROUND_UP(new_l1_size2, 512));
133
134 if (s->l1_size) {
135 memcpy(new_l1_table, s->l1_table, s->l1_size * sizeof(uint64_t));
136 }
137
138 /* write new table (align to cluster) */
139 BLKDBG_EVENT(bs->file, BLKDBG_L1_GROW_ALLOC_TABLE);
140 new_l1_table_offset = qcow2_alloc_clusters(bs, new_l1_size2);
141 if (new_l1_table_offset < 0) {
142 qemu_vfree(new_l1_table);
143 return new_l1_table_offset;
144 }
145
146 ret = qcow2_cache_flush(bs, s->refcount_block_cache);
147 if (ret < 0) {
148 goto fail;
149 }
150
151 /* the L1 position has not yet been updated, so these clusters must
152 * indeed be completely free */
153 ret = qcow2_pre_write_overlap_check(bs, 0, new_l1_table_offset,
154 new_l1_size2, false);
155 if (ret < 0) {
156 goto fail;
157 }
158
159 BLKDBG_EVENT(bs->file, BLKDBG_L1_GROW_WRITE_TABLE);
160 for(i = 0; i < s->l1_size; i++)
161 new_l1_table[i] = cpu_to_be64(new_l1_table[i]);
162 ret = bdrv_pwrite_sync(bs->file, new_l1_table_offset,
163 new_l1_table, new_l1_size2);
164 if (ret < 0)
165 goto fail;
166 for(i = 0; i < s->l1_size; i++)
167 new_l1_table[i] = be64_to_cpu(new_l1_table[i]);
168
169 /* set new table */
170 BLKDBG_EVENT(bs->file, BLKDBG_L1_GROW_ACTIVATE_TABLE);
171 stl_be_p(data, new_l1_size);
172 stq_be_p(data + 4, new_l1_table_offset);
173 ret = bdrv_pwrite_sync(bs->file, offsetof(QCowHeader, l1_size),
174 data, sizeof(data));
175 if (ret < 0) {
176 goto fail;
177 }
178 qemu_vfree(s->l1_table);
179 old_l1_table_offset = s->l1_table_offset;
180 s->l1_table_offset = new_l1_table_offset;
181 s->l1_table = new_l1_table;
182 old_l1_size = s->l1_size;
183 s->l1_size = new_l1_size;
184 qcow2_free_clusters(bs, old_l1_table_offset, old_l1_size * sizeof(uint64_t),
185 QCOW2_DISCARD_OTHER);
186 return 0;
187 fail:
188 qemu_vfree(new_l1_table);
189 qcow2_free_clusters(bs, new_l1_table_offset, new_l1_size2,
190 QCOW2_DISCARD_OTHER);
191 return ret;
192}
193
194/*
195 * l2_load
196 *
197 * @bs: The BlockDriverState
198 * @offset: A guest offset, used to calculate what slice of the L2
199 * table to load.
200 * @l2_offset: Offset to the L2 table in the image file.
201 * @l2_slice: Location to store the pointer to the L2 slice.
202 *
203 * Loads a L2 slice into memory (L2 slices are the parts of L2 tables
204 * that are loaded by the qcow2 cache). If the slice is in the cache,
205 * the cache is used; otherwise the L2 slice is loaded from the image
206 * file.
207 */
208static int l2_load(BlockDriverState *bs, uint64_t offset,
209 uint64_t l2_offset, uint64_t **l2_slice)
210{
211 BDRVQcow2State *s = bs->opaque;
212 int start_of_slice = sizeof(uint64_t) *
213 (offset_to_l2_index(s, offset) - offset_to_l2_slice_index(s, offset));
214
215 return qcow2_cache_get(bs, s->l2_table_cache, l2_offset + start_of_slice,
216 (void **)l2_slice);
217}
218
219/*
220 * Writes one sector of the L1 table to the disk (can't update single entries
221 * and we really don't want bdrv_pread to perform a read-modify-write)
222 */
223#define L1_ENTRIES_PER_SECTOR (512 / 8)
224int qcow2_write_l1_entry(BlockDriverState *bs, int l1_index)
225{
226 BDRVQcow2State *s = bs->opaque;
227 uint64_t buf[L1_ENTRIES_PER_SECTOR] = { 0 };
228 int l1_start_index;
229 int i, ret;
230
231 l1_start_index = l1_index & ~(L1_ENTRIES_PER_SECTOR - 1);
232 for (i = 0; i < L1_ENTRIES_PER_SECTOR && l1_start_index + i < s->l1_size;
233 i++)
234 {
235 buf[i] = cpu_to_be64(s->l1_table[l1_start_index + i]);
236 }
237
238 ret = qcow2_pre_write_overlap_check(bs, QCOW2_OL_ACTIVE_L1,
239 s->l1_table_offset + 8 * l1_start_index, sizeof(buf), false);
240 if (ret < 0) {
241 return ret;
242 }
243
244 BLKDBG_EVENT(bs->file, BLKDBG_L1_UPDATE);
245 ret = bdrv_pwrite_sync(bs->file,
246 s->l1_table_offset + 8 * l1_start_index,
247 buf, sizeof(buf));
248 if (ret < 0) {
249 return ret;
250 }
251
252 return 0;
253}
254
255/*
256 * l2_allocate
257 *
258 * Allocate a new l2 entry in the file. If l1_index points to an already
259 * used entry in the L2 table (i.e. we are doing a copy on write for the L2
260 * table) copy the contents of the old L2 table into the newly allocated one.
261 * Otherwise the new table is initialized with zeros.
262 *
263 */
264
265static int l2_allocate(BlockDriverState *bs, int l1_index)
266{
267 BDRVQcow2State *s = bs->opaque;
268 uint64_t old_l2_offset;
269 uint64_t *l2_slice = NULL;
270 unsigned slice, slice_size2, n_slices;
271 int64_t l2_offset;
272 int ret;
273
274 old_l2_offset = s->l1_table[l1_index];
275
276 trace_qcow2_l2_allocate(bs, l1_index);
277
278 /* allocate a new l2 entry */
279
280 l2_offset = qcow2_alloc_clusters(bs, s->l2_size * sizeof(uint64_t));
281 if (l2_offset < 0) {
282 ret = l2_offset;
283 goto fail;
284 }
285
286 /* The offset must fit in the offset field of the L1 table entry */
287 assert((l2_offset & L1E_OFFSET_MASK) == l2_offset);
288
289 /* If we're allocating the table at offset 0 then something is wrong */
290 if (l2_offset == 0) {
291 qcow2_signal_corruption(bs, true, -1, -1, "Preventing invalid "
292 "allocation of L2 table at offset 0");
293 ret = -EIO;
294 goto fail;
295 }
296
297 ret = qcow2_cache_flush(bs, s->refcount_block_cache);
298 if (ret < 0) {
299 goto fail;
300 }
301
302 /* allocate a new entry in the l2 cache */
303
304 slice_size2 = s->l2_slice_size * sizeof(uint64_t);
305 n_slices = s->cluster_size / slice_size2;
306
307 trace_qcow2_l2_allocate_get_empty(bs, l1_index);
308 for (slice = 0; slice < n_slices; slice++) {
309 ret = qcow2_cache_get_empty(bs, s->l2_table_cache,
310 l2_offset + slice * slice_size2,
311 (void **) &l2_slice);
312 if (ret < 0) {
313 goto fail;
314 }
315
316 if ((old_l2_offset & L1E_OFFSET_MASK) == 0) {
317 /* if there was no old l2 table, clear the new slice */
318 memset(l2_slice, 0, slice_size2);
319 } else {
320 uint64_t *old_slice;
321 uint64_t old_l2_slice_offset =
322 (old_l2_offset & L1E_OFFSET_MASK) + slice * slice_size2;
323
324 /* if there was an old l2 table, read a slice from the disk */
325 BLKDBG_EVENT(bs->file, BLKDBG_L2_ALLOC_COW_READ);
326 ret = qcow2_cache_get(bs, s->l2_table_cache, old_l2_slice_offset,
327 (void **) &old_slice);
328 if (ret < 0) {
329 goto fail;
330 }
331
332 memcpy(l2_slice, old_slice, slice_size2);
333
334 qcow2_cache_put(s->l2_table_cache, (void **) &old_slice);
335 }
336
337 /* write the l2 slice to the file */
338 BLKDBG_EVENT(bs->file, BLKDBG_L2_ALLOC_WRITE);
339
340 trace_qcow2_l2_allocate_write_l2(bs, l1_index);
341 qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_slice);
342 qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice);
343 }
344
345 ret = qcow2_cache_flush(bs, s->l2_table_cache);
346 if (ret < 0) {
347 goto fail;
348 }
349
350 /* update the L1 entry */
351 trace_qcow2_l2_allocate_write_l1(bs, l1_index);
352 s->l1_table[l1_index] = l2_offset | QCOW_OFLAG_COPIED;
353 ret = qcow2_write_l1_entry(bs, l1_index);
354 if (ret < 0) {
355 goto fail;
356 }
357
358 trace_qcow2_l2_allocate_done(bs, l1_index, 0);
359 return 0;
360
361fail:
362 trace_qcow2_l2_allocate_done(bs, l1_index, ret);
363 if (l2_slice != NULL) {
364 qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice);
365 }
366 s->l1_table[l1_index] = old_l2_offset;
367 if (l2_offset > 0) {
368 qcow2_free_clusters(bs, l2_offset, s->l2_size * sizeof(uint64_t),
369 QCOW2_DISCARD_ALWAYS);
370 }
371 return ret;
372}
373
374/*
375 * Checks how many clusters in a given L2 slice are contiguous in the image
376 * file. As soon as one of the flags in the bitmask stop_flags changes compared
377 * to the first cluster, the search is stopped and the cluster is not counted
378 * as contiguous. (This allows it, for example, to stop at the first compressed
379 * cluster which may require a different handling)
380 */
381static int count_contiguous_clusters(BlockDriverState *bs, int nb_clusters,
382 int cluster_size, uint64_t *l2_slice, uint64_t stop_flags)
383{
384 int i;
385 QCow2ClusterType first_cluster_type;
386 uint64_t mask = stop_flags | L2E_OFFSET_MASK | QCOW_OFLAG_COMPRESSED;
387 uint64_t first_entry = be64_to_cpu(l2_slice[0]);
388 uint64_t offset = first_entry & mask;
389
390 first_cluster_type = qcow2_get_cluster_type(bs, first_entry);
391 if (first_cluster_type == QCOW2_CLUSTER_UNALLOCATED) {
392 return 0;
393 }
394
395 /* must be allocated */
396 assert(first_cluster_type == QCOW2_CLUSTER_NORMAL ||
397 first_cluster_type == QCOW2_CLUSTER_ZERO_ALLOC);
398
399 for (i = 0; i < nb_clusters; i++) {
400 uint64_t l2_entry = be64_to_cpu(l2_slice[i]) & mask;
401 if (offset + (uint64_t) i * cluster_size != l2_entry) {
402 break;
403 }
404 }
405
406 return i;
407}
408
409/*
410 * Checks how many consecutive unallocated clusters in a given L2
411 * slice have the same cluster type.
412 */
413static int count_contiguous_clusters_unallocated(BlockDriverState *bs,
414 int nb_clusters,
415 uint64_t *l2_slice,
416 QCow2ClusterType wanted_type)
417{
418 int i;
419
420 assert(wanted_type == QCOW2_CLUSTER_ZERO_PLAIN ||
421 wanted_type == QCOW2_CLUSTER_UNALLOCATED);
422 for (i = 0; i < nb_clusters; i++) {
423 uint64_t entry = be64_to_cpu(l2_slice[i]);
424 QCow2ClusterType type = qcow2_get_cluster_type(bs, entry);
425
426 if (type != wanted_type) {
427 break;
428 }
429 }
430
431 return i;
432}
433
434static int coroutine_fn do_perform_cow_read(BlockDriverState *bs,
435 uint64_t src_cluster_offset,
436 unsigned offset_in_cluster,
437 QEMUIOVector *qiov)
438{
439 int ret;
440
441 if (qiov->size == 0) {
442 return 0;
443 }
444
445 BLKDBG_EVENT(bs->file, BLKDBG_COW_READ);
446
447 if (!bs->drv) {
448 return -ENOMEDIUM;
449 }
450
451 /* Call .bdrv_co_readv() directly instead of using the public block-layer
452 * interface. This avoids double I/O throttling and request tracking,
453 * which can lead to deadlock when block layer copy-on-read is enabled.
454 */
455 ret = bs->drv->bdrv_co_preadv_part(bs,
456 src_cluster_offset + offset_in_cluster,
457 qiov->size, qiov, 0, 0);
458 if (ret < 0) {
459 return ret;
460 }
461
462 return 0;
463}
464
465static bool coroutine_fn do_perform_cow_encrypt(BlockDriverState *bs,
466 uint64_t src_cluster_offset,
467 uint64_t cluster_offset,
468 unsigned offset_in_cluster,
469 uint8_t *buffer,
470 unsigned bytes)
471{
472 if (bytes && bs->encrypted) {
473 BDRVQcow2State *s = bs->opaque;
474 assert((offset_in_cluster & ~BDRV_SECTOR_MASK) == 0);
475 assert((bytes & ~BDRV_SECTOR_MASK) == 0);
476 assert(s->crypto);
477 if (qcow2_co_encrypt(bs, cluster_offset,
478 src_cluster_offset + offset_in_cluster,
479 buffer, bytes) < 0) {
480 return false;
481 }
482 }
483 return true;
484}
485
486static int coroutine_fn do_perform_cow_write(BlockDriverState *bs,
487 uint64_t cluster_offset,
488 unsigned offset_in_cluster,
489 QEMUIOVector *qiov)
490{
491 BDRVQcow2State *s = bs->opaque;
492 int ret;
493
494 if (qiov->size == 0) {
495 return 0;
496 }
497
498 ret = qcow2_pre_write_overlap_check(bs, 0,
499 cluster_offset + offset_in_cluster, qiov->size, true);
500 if (ret < 0) {
501 return ret;
502 }
503
504 BLKDBG_EVENT(bs->file, BLKDBG_COW_WRITE);
505 ret = bdrv_co_pwritev(s->data_file, cluster_offset + offset_in_cluster,
506 qiov->size, qiov, 0);
507 if (ret < 0) {
508 return ret;
509 }
510
511 return 0;
512}
513
514
515/*
516 * get_cluster_offset
517 *
518 * For a given offset of the virtual disk, find the cluster type and offset in
519 * the qcow2 file. The offset is stored in *cluster_offset.
520 *
521 * On entry, *bytes is the maximum number of contiguous bytes starting at
522 * offset that we are interested in.
523 *
524 * On exit, *bytes is the number of bytes starting at offset that have the same
525 * cluster type and (if applicable) are stored contiguously in the image file.
526 * Compressed clusters are always returned one by one.
527 *
528 * Returns the cluster type (QCOW2_CLUSTER_*) on success, -errno in error
529 * cases.
530 */
531int qcow2_get_cluster_offset(BlockDriverState *bs, uint64_t offset,
532 unsigned int *bytes, uint64_t *cluster_offset)
533{
534 BDRVQcow2State *s = bs->opaque;
535 unsigned int l2_index;
536 uint64_t l1_index, l2_offset, *l2_slice;
537 int c;
538 unsigned int offset_in_cluster;
539 uint64_t bytes_available, bytes_needed, nb_clusters;
540 QCow2ClusterType type;
541 int ret;
542
543 offset_in_cluster = offset_into_cluster(s, offset);
544 bytes_needed = (uint64_t) *bytes + offset_in_cluster;
545
546 /* compute how many bytes there are between the start of the cluster
547 * containing offset and the end of the l2 slice that contains
548 * the entry pointing to it */
549 bytes_available =
550 ((uint64_t) (s->l2_slice_size - offset_to_l2_slice_index(s, offset)))
551 << s->cluster_bits;
552
553 if (bytes_needed > bytes_available) {
554 bytes_needed = bytes_available;
555 }
556
557 *cluster_offset = 0;
558
559 /* seek to the l2 offset in the l1 table */
560
561 l1_index = offset_to_l1_index(s, offset);
562 if (l1_index >= s->l1_size) {
563 type = QCOW2_CLUSTER_UNALLOCATED;
564 goto out;
565 }
566
567 l2_offset = s->l1_table[l1_index] & L1E_OFFSET_MASK;
568 if (!l2_offset) {
569 type = QCOW2_CLUSTER_UNALLOCATED;
570 goto out;
571 }
572
573 if (offset_into_cluster(s, l2_offset)) {
574 qcow2_signal_corruption(bs, true, -1, -1, "L2 table offset %#" PRIx64
575 " unaligned (L1 index: %#" PRIx64 ")",
576 l2_offset, l1_index);
577 return -EIO;
578 }
579
580 /* load the l2 slice in memory */
581
582 ret = l2_load(bs, offset, l2_offset, &l2_slice);
583 if (ret < 0) {
584 return ret;
585 }
586
587 /* find the cluster offset for the given disk offset */
588
589 l2_index = offset_to_l2_slice_index(s, offset);
590 *cluster_offset = be64_to_cpu(l2_slice[l2_index]);
591
592 nb_clusters = size_to_clusters(s, bytes_needed);
593 /* bytes_needed <= *bytes + offset_in_cluster, both of which are unsigned
594 * integers; the minimum cluster size is 512, so this assertion is always
595 * true */
596 assert(nb_clusters <= INT_MAX);
597
598 type = qcow2_get_cluster_type(bs, *cluster_offset);
599 if (s->qcow_version < 3 && (type == QCOW2_CLUSTER_ZERO_PLAIN ||
600 type == QCOW2_CLUSTER_ZERO_ALLOC)) {
601 qcow2_signal_corruption(bs, true, -1, -1, "Zero cluster entry found"
602 " in pre-v3 image (L2 offset: %#" PRIx64
603 ", L2 index: %#x)", l2_offset, l2_index);
604 ret = -EIO;
605 goto fail;
606 }
607 switch (type) {
608 case QCOW2_CLUSTER_COMPRESSED:
609 if (has_data_file(bs)) {
610 qcow2_signal_corruption(bs, true, -1, -1, "Compressed cluster "
611 "entry found in image with external data "
612 "file (L2 offset: %#" PRIx64 ", L2 index: "
613 "%#x)", l2_offset, l2_index);
614 ret = -EIO;
615 goto fail;
616 }
617 /* Compressed clusters can only be processed one by one */
618 c = 1;
619 *cluster_offset &= L2E_COMPRESSED_OFFSET_SIZE_MASK;
620 break;
621 case QCOW2_CLUSTER_ZERO_PLAIN:
622 case QCOW2_CLUSTER_UNALLOCATED:
623 /* how many empty clusters ? */
624 c = count_contiguous_clusters_unallocated(bs, nb_clusters,
625 &l2_slice[l2_index], type);
626 *cluster_offset = 0;
627 break;
628 case QCOW2_CLUSTER_ZERO_ALLOC:
629 case QCOW2_CLUSTER_NORMAL:
630 /* how many allocated clusters ? */
631 c = count_contiguous_clusters(bs, nb_clusters, s->cluster_size,
632 &l2_slice[l2_index], QCOW_OFLAG_ZERO);
633 *cluster_offset &= L2E_OFFSET_MASK;
634 if (offset_into_cluster(s, *cluster_offset)) {
635 qcow2_signal_corruption(bs, true, -1, -1,
636 "Cluster allocation offset %#"
637 PRIx64 " unaligned (L2 offset: %#" PRIx64
638 ", L2 index: %#x)", *cluster_offset,
639 l2_offset, l2_index);
640 ret = -EIO;
641 goto fail;
642 }
643 if (has_data_file(bs) && *cluster_offset != offset - offset_in_cluster)
644 {
645 qcow2_signal_corruption(bs, true, -1, -1,
646 "External data file host cluster offset %#"
647 PRIx64 " does not match guest cluster "
648 "offset: %#" PRIx64
649 ", L2 index: %#x)", *cluster_offset,
650 offset - offset_in_cluster, l2_index);
651 ret = -EIO;
652 goto fail;
653 }
654 break;
655 default:
656 abort();
657 }
658
659 qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice);
660
661 bytes_available = (int64_t)c * s->cluster_size;
662
663out:
664 if (bytes_available > bytes_needed) {
665 bytes_available = bytes_needed;
666 }
667
668 /* bytes_available <= bytes_needed <= *bytes + offset_in_cluster;
669 * subtracting offset_in_cluster will therefore definitely yield something
670 * not exceeding UINT_MAX */
671 assert(bytes_available - offset_in_cluster <= UINT_MAX);
672 *bytes = bytes_available - offset_in_cluster;
673
674 return type;
675
676fail:
677 qcow2_cache_put(s->l2_table_cache, (void **)&l2_slice);
678 return ret;
679}
680
681/*
682 * get_cluster_table
683 *
684 * for a given disk offset, load (and allocate if needed)
685 * the appropriate slice of its l2 table.
686 *
687 * the cluster index in the l2 slice is given to the caller.
688 *
689 * Returns 0 on success, -errno in failure case
690 */
691static int get_cluster_table(BlockDriverState *bs, uint64_t offset,
692 uint64_t **new_l2_slice,
693 int *new_l2_index)
694{
695 BDRVQcow2State *s = bs->opaque;
696 unsigned int l2_index;
697 uint64_t l1_index, l2_offset;
698 uint64_t *l2_slice = NULL;
699 int ret;
700
701 /* seek to the l2 offset in the l1 table */
702
703 l1_index = offset_to_l1_index(s, offset);
704 if (l1_index >= s->l1_size) {
705 ret = qcow2_grow_l1_table(bs, l1_index + 1, false);
706 if (ret < 0) {
707 return ret;
708 }
709 }
710
711 assert(l1_index < s->l1_size);
712 l2_offset = s->l1_table[l1_index] & L1E_OFFSET_MASK;
713 if (offset_into_cluster(s, l2_offset)) {
714 qcow2_signal_corruption(bs, true, -1, -1, "L2 table offset %#" PRIx64
715 " unaligned (L1 index: %#" PRIx64 ")",
716 l2_offset, l1_index);
717 return -EIO;
718 }
719
720 if (!(s->l1_table[l1_index] & QCOW_OFLAG_COPIED)) {
721 /* First allocate a new L2 table (and do COW if needed) */
722 ret = l2_allocate(bs, l1_index);
723 if (ret < 0) {
724 return ret;
725 }
726
727 /* Then decrease the refcount of the old table */
728 if (l2_offset) {
729 qcow2_free_clusters(bs, l2_offset, s->l2_size * sizeof(uint64_t),
730 QCOW2_DISCARD_OTHER);
731 }
732
733 /* Get the offset of the newly-allocated l2 table */
734 l2_offset = s->l1_table[l1_index] & L1E_OFFSET_MASK;
735 assert(offset_into_cluster(s, l2_offset) == 0);
736 }
737
738 /* load the l2 slice in memory */
739 ret = l2_load(bs, offset, l2_offset, &l2_slice);
740 if (ret < 0) {
741 return ret;
742 }
743
744 /* find the cluster offset for the given disk offset */
745
746 l2_index = offset_to_l2_slice_index(s, offset);
747
748 *new_l2_slice = l2_slice;
749 *new_l2_index = l2_index;
750
751 return 0;
752}
753
754/*
755 * alloc_compressed_cluster_offset
756 *
757 * For a given offset on the virtual disk, allocate a new compressed cluster
758 * and put the host offset of the cluster into *host_offset. If a cluster is
759 * already allocated at the offset, return an error.
760 *
761 * Return 0 on success and -errno in error cases
762 */
763int qcow2_alloc_compressed_cluster_offset(BlockDriverState *bs,
764 uint64_t offset,
765 int compressed_size,
766 uint64_t *host_offset)
767{
768 BDRVQcow2State *s = bs->opaque;
769 int l2_index, ret;
770 uint64_t *l2_slice;
771 int64_t cluster_offset;
772 int nb_csectors;
773
774 if (has_data_file(bs)) {
775 return 0;
776 }
777
778 ret = get_cluster_table(bs, offset, &l2_slice, &l2_index);
779 if (ret < 0) {
780 return ret;
781 }
782
783 /* Compression can't overwrite anything. Fail if the cluster was already
784 * allocated. */
785 cluster_offset = be64_to_cpu(l2_slice[l2_index]);
786 if (cluster_offset & L2E_OFFSET_MASK) {
787 qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice);
788 return -EIO;
789 }
790
791 cluster_offset = qcow2_alloc_bytes(bs, compressed_size);
792 if (cluster_offset < 0) {
793 qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice);
794 return cluster_offset;
795 }
796
797 nb_csectors =
798 (cluster_offset + compressed_size - 1) / QCOW2_COMPRESSED_SECTOR_SIZE -
799 (cluster_offset / QCOW2_COMPRESSED_SECTOR_SIZE);
800
801 cluster_offset |= QCOW_OFLAG_COMPRESSED |
802 ((uint64_t)nb_csectors << s->csize_shift);
803
804 /* update L2 table */
805
806 /* compressed clusters never have the copied flag */
807
808 BLKDBG_EVENT(bs->file, BLKDBG_L2_UPDATE_COMPRESSED);
809 qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_slice);
810 l2_slice[l2_index] = cpu_to_be64(cluster_offset);
811 qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice);
812
813 *host_offset = cluster_offset & s->cluster_offset_mask;
814 return 0;
815}
816
817static int perform_cow(BlockDriverState *bs, QCowL2Meta *m)
818{
819 BDRVQcow2State *s = bs->opaque;
820 Qcow2COWRegion *start = &m->cow_start;
821 Qcow2COWRegion *end = &m->cow_end;
822 unsigned buffer_size;
823 unsigned data_bytes = end->offset - (start->offset + start->nb_bytes);
824 bool merge_reads;
825 uint8_t *start_buffer, *end_buffer;
826 QEMUIOVector qiov;
827 int ret;
828
829 assert(start->nb_bytes <= UINT_MAX - end->nb_bytes);
830 assert(start->nb_bytes + end->nb_bytes <= UINT_MAX - data_bytes);
831 assert(start->offset + start->nb_bytes <= end->offset);
832
833 if ((start->nb_bytes == 0 && end->nb_bytes == 0) || m->skip_cow) {
834 return 0;
835 }
836
837 /* If we have to read both the start and end COW regions and the
838 * middle region is not too large then perform just one read
839 * operation */
840 merge_reads = start->nb_bytes && end->nb_bytes && data_bytes <= 16384;
841 if (merge_reads) {
842 buffer_size = start->nb_bytes + data_bytes + end->nb_bytes;
843 } else {
844 /* If we have to do two reads, add some padding in the middle
845 * if necessary to make sure that the end region is optimally
846 * aligned. */
847 size_t align = bdrv_opt_mem_align(bs);
848 assert(align > 0 && align <= UINT_MAX);
849 assert(QEMU_ALIGN_UP(start->nb_bytes, align) <=
850 UINT_MAX - end->nb_bytes);
851 buffer_size = QEMU_ALIGN_UP(start->nb_bytes, align) + end->nb_bytes;
852 }
853
854 /* Reserve a buffer large enough to store all the data that we're
855 * going to read */
856 start_buffer = qemu_try_blockalign(bs, buffer_size);
857 if (start_buffer == NULL) {
858 return -ENOMEM;
859 }
860 /* The part of the buffer where the end region is located */
861 end_buffer = start_buffer + buffer_size - end->nb_bytes;
862
863 qemu_iovec_init(&qiov, 2 + (m->data_qiov ?
864 qemu_iovec_subvec_niov(m->data_qiov,
865 m->data_qiov_offset,
866 data_bytes)
867 : 0));
868
869 qemu_co_mutex_unlock(&s->lock);
870 /* First we read the existing data from both COW regions. We
871 * either read the whole region in one go, or the start and end
872 * regions separately. */
873 if (merge_reads) {
874 qemu_iovec_add(&qiov, start_buffer, buffer_size);
875 ret = do_perform_cow_read(bs, m->offset, start->offset, &qiov);
876 } else {
877 qemu_iovec_add(&qiov, start_buffer, start->nb_bytes);
878 ret = do_perform_cow_read(bs, m->offset, start->offset, &qiov);
879 if (ret < 0) {
880 goto fail;
881 }
882
883 qemu_iovec_reset(&qiov);
884 qemu_iovec_add(&qiov, end_buffer, end->nb_bytes);
885 ret = do_perform_cow_read(bs, m->offset, end->offset, &qiov);
886 }
887 if (ret < 0) {
888 goto fail;
889 }
890
891 /* Encrypt the data if necessary before writing it */
892 if (bs->encrypted) {
893 if (!do_perform_cow_encrypt(bs, m->offset, m->alloc_offset,
894 start->offset, start_buffer,
895 start->nb_bytes) ||
896 !do_perform_cow_encrypt(bs, m->offset, m->alloc_offset,
897 end->offset, end_buffer, end->nb_bytes)) {
898 ret = -EIO;
899 goto fail;
900 }
901 }
902
903 /* And now we can write everything. If we have the guest data we
904 * can write everything in one single operation */
905 if (m->data_qiov) {
906 qemu_iovec_reset(&qiov);
907 if (start->nb_bytes) {
908 qemu_iovec_add(&qiov, start_buffer, start->nb_bytes);
909 }
910 qemu_iovec_concat(&qiov, m->data_qiov, m->data_qiov_offset, data_bytes);
911 if (end->nb_bytes) {
912 qemu_iovec_add(&qiov, end_buffer, end->nb_bytes);
913 }
914 /* NOTE: we have a write_aio blkdebug event here followed by
915 * a cow_write one in do_perform_cow_write(), but there's only
916 * one single I/O operation */
917 BLKDBG_EVENT(bs->file, BLKDBG_WRITE_AIO);
918 ret = do_perform_cow_write(bs, m->alloc_offset, start->offset, &qiov);
919 } else {
920 /* If there's no guest data then write both COW regions separately */
921 qemu_iovec_reset(&qiov);
922 qemu_iovec_add(&qiov, start_buffer, start->nb_bytes);
923 ret = do_perform_cow_write(bs, m->alloc_offset, start->offset, &qiov);
924 if (ret < 0) {
925 goto fail;
926 }
927
928 qemu_iovec_reset(&qiov);
929 qemu_iovec_add(&qiov, end_buffer, end->nb_bytes);
930 ret = do_perform_cow_write(bs, m->alloc_offset, end->offset, &qiov);
931 }
932
933fail:
934 qemu_co_mutex_lock(&s->lock);
935
936 /*
937 * Before we update the L2 table to actually point to the new cluster, we
938 * need to be sure that the refcounts have been increased and COW was
939 * handled.
940 */
941 if (ret == 0) {
942 qcow2_cache_depends_on_flush(s->l2_table_cache);
943 }
944
945 qemu_vfree(start_buffer);
946 qemu_iovec_destroy(&qiov);
947 return ret;
948}
949
950int qcow2_alloc_cluster_link_l2(BlockDriverState *bs, QCowL2Meta *m)
951{
952 BDRVQcow2State *s = bs->opaque;
953 int i, j = 0, l2_index, ret;
954 uint64_t *old_cluster, *l2_slice;
955 uint64_t cluster_offset = m->alloc_offset;
956
957 trace_qcow2_cluster_link_l2(qemu_coroutine_self(), m->nb_clusters);
958 assert(m->nb_clusters > 0);
959
960 old_cluster = g_try_new(uint64_t, m->nb_clusters);
961 if (old_cluster == NULL) {
962 ret = -ENOMEM;
963 goto err;
964 }
965
966 /* copy content of unmodified sectors */
967 ret = perform_cow(bs, m);
968 if (ret < 0) {
969 goto err;
970 }
971
972 /* Update L2 table. */
973 if (s->use_lazy_refcounts) {
974 qcow2_mark_dirty(bs);
975 }
976 if (qcow2_need_accurate_refcounts(s)) {
977 qcow2_cache_set_dependency(bs, s->l2_table_cache,
978 s->refcount_block_cache);
979 }
980
981 ret = get_cluster_table(bs, m->offset, &l2_slice, &l2_index);
982 if (ret < 0) {
983 goto err;
984 }
985 qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_slice);
986
987 assert(l2_index + m->nb_clusters <= s->l2_slice_size);
988 for (i = 0; i < m->nb_clusters; i++) {
989 /* if two concurrent writes happen to the same unallocated cluster
990 * each write allocates separate cluster and writes data concurrently.
991 * The first one to complete updates l2 table with pointer to its
992 * cluster the second one has to do RMW (which is done above by
993 * perform_cow()), update l2 table with its cluster pointer and free
994 * old cluster. This is what this loop does */
995 if (l2_slice[l2_index + i] != 0) {
996 old_cluster[j++] = l2_slice[l2_index + i];
997 }
998
999 l2_slice[l2_index + i] = cpu_to_be64((cluster_offset +
1000 (i << s->cluster_bits)) | QCOW_OFLAG_COPIED);
1001 }
1002
1003
1004 qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice);
1005
1006 /*
1007 * If this was a COW, we need to decrease the refcount of the old cluster.
1008 *
1009 * Don't discard clusters that reach a refcount of 0 (e.g. compressed
1010 * clusters), the next write will reuse them anyway.
1011 */
1012 if (!m->keep_old_clusters && j != 0) {
1013 for (i = 0; i < j; i++) {
1014 qcow2_free_any_clusters(bs, be64_to_cpu(old_cluster[i]), 1,
1015 QCOW2_DISCARD_NEVER);
1016 }
1017 }
1018
1019 ret = 0;
1020err:
1021 g_free(old_cluster);
1022 return ret;
1023 }
1024
1025/**
1026 * Frees the allocated clusters because the request failed and they won't
1027 * actually be linked.
1028 */
1029void qcow2_alloc_cluster_abort(BlockDriverState *bs, QCowL2Meta *m)
1030{
1031 BDRVQcow2State *s = bs->opaque;
1032 qcow2_free_clusters(bs, m->alloc_offset, m->nb_clusters << s->cluster_bits,
1033 QCOW2_DISCARD_NEVER);
1034}
1035
1036/*
1037 * Returns the number of contiguous clusters that can be used for an allocating
1038 * write, but require COW to be performed (this includes yet unallocated space,
1039 * which must copy from the backing file)
1040 */
1041static int count_cow_clusters(BlockDriverState *bs, int nb_clusters,
1042 uint64_t *l2_slice, int l2_index)
1043{
1044 int i;
1045
1046 for (i = 0; i < nb_clusters; i++) {
1047 uint64_t l2_entry = be64_to_cpu(l2_slice[l2_index + i]);
1048 QCow2ClusterType cluster_type = qcow2_get_cluster_type(bs, l2_entry);
1049
1050 switch(cluster_type) {
1051 case QCOW2_CLUSTER_NORMAL:
1052 if (l2_entry & QCOW_OFLAG_COPIED) {
1053 goto out;
1054 }
1055 break;
1056 case QCOW2_CLUSTER_UNALLOCATED:
1057 case QCOW2_CLUSTER_COMPRESSED:
1058 case QCOW2_CLUSTER_ZERO_PLAIN:
1059 case QCOW2_CLUSTER_ZERO_ALLOC:
1060 break;
1061 default:
1062 abort();
1063 }
1064 }
1065
1066out:
1067 assert(i <= nb_clusters);
1068 return i;
1069}
1070
1071/*
1072 * Check if there already is an AIO write request in flight which allocates
1073 * the same cluster. In this case we need to wait until the previous
1074 * request has completed and updated the L2 table accordingly.
1075 *
1076 * Returns:
1077 * 0 if there was no dependency. *cur_bytes indicates the number of
1078 * bytes from guest_offset that can be read before the next
1079 * dependency must be processed (or the request is complete)
1080 *
1081 * -EAGAIN if we had to wait for another request, previously gathered
1082 * information on cluster allocation may be invalid now. The caller
1083 * must start over anyway, so consider *cur_bytes undefined.
1084 */
1085static int handle_dependencies(BlockDriverState *bs, uint64_t guest_offset,
1086 uint64_t *cur_bytes, QCowL2Meta **m)
1087{
1088 BDRVQcow2State *s = bs->opaque;
1089 QCowL2Meta *old_alloc;
1090 uint64_t bytes = *cur_bytes;
1091
1092 QLIST_FOREACH(old_alloc, &s->cluster_allocs, next_in_flight) {
1093
1094 uint64_t start = guest_offset;
1095 uint64_t end = start + bytes;
1096 uint64_t old_start = l2meta_cow_start(old_alloc);
1097 uint64_t old_end = l2meta_cow_end(old_alloc);
1098
1099 if (end <= old_start || start >= old_end) {
1100 /* No intersection */
1101 } else {
1102 if (start < old_start) {
1103 /* Stop at the start of a running allocation */
1104 bytes = old_start - start;
1105 } else {
1106 bytes = 0;
1107 }
1108
1109 /* Stop if already an l2meta exists. After yielding, it wouldn't
1110 * be valid any more, so we'd have to clean up the old L2Metas
1111 * and deal with requests depending on them before starting to
1112 * gather new ones. Not worth the trouble. */
1113 if (bytes == 0 && *m) {
1114 *cur_bytes = 0;
1115 return 0;
1116 }
1117
1118 if (bytes == 0) {
1119 /* Wait for the dependency to complete. We need to recheck
1120 * the free/allocated clusters when we continue. */
1121 qemu_co_queue_wait(&old_alloc->dependent_requests, &s->lock);
1122 return -EAGAIN;
1123 }
1124 }
1125 }
1126
1127 /* Make sure that existing clusters and new allocations are only used up to
1128 * the next dependency if we shortened the request above */
1129 *cur_bytes = bytes;
1130
1131 return 0;
1132}
1133
1134/*
1135 * Checks how many already allocated clusters that don't require a copy on
1136 * write there are at the given guest_offset (up to *bytes). If *host_offset is
1137 * not INV_OFFSET, only physically contiguous clusters beginning at this host
1138 * offset are counted.
1139 *
1140 * Note that guest_offset may not be cluster aligned. In this case, the
1141 * returned *host_offset points to exact byte referenced by guest_offset and
1142 * therefore isn't cluster aligned as well.
1143 *
1144 * Returns:
1145 * 0: if no allocated clusters are available at the given offset.
1146 * *bytes is normally unchanged. It is set to 0 if the cluster
1147 * is allocated and doesn't need COW, but doesn't have the right
1148 * physical offset.
1149 *
1150 * 1: if allocated clusters that don't require a COW are available at
1151 * the requested offset. *bytes may have decreased and describes
1152 * the length of the area that can be written to.
1153 *
1154 * -errno: in error cases
1155 */
1156static int handle_copied(BlockDriverState *bs, uint64_t guest_offset,
1157 uint64_t *host_offset, uint64_t *bytes, QCowL2Meta **m)
1158{
1159 BDRVQcow2State *s = bs->opaque;
1160 int l2_index;
1161 uint64_t cluster_offset;
1162 uint64_t *l2_slice;
1163 uint64_t nb_clusters;
1164 unsigned int keep_clusters;
1165 int ret;
1166
1167 trace_qcow2_handle_copied(qemu_coroutine_self(), guest_offset, *host_offset,
1168 *bytes);
1169
1170 assert(*host_offset == INV_OFFSET || offset_into_cluster(s, guest_offset)
1171 == offset_into_cluster(s, *host_offset));
1172
1173 /*
1174 * Calculate the number of clusters to look for. We stop at L2 slice
1175 * boundaries to keep things simple.
1176 */
1177 nb_clusters =
1178 size_to_clusters(s, offset_into_cluster(s, guest_offset) + *bytes);
1179
1180 l2_index = offset_to_l2_slice_index(s, guest_offset);
1181 nb_clusters = MIN(nb_clusters, s->l2_slice_size - l2_index);
1182 assert(nb_clusters <= INT_MAX);
1183
1184 /* Find L2 entry for the first involved cluster */
1185 ret = get_cluster_table(bs, guest_offset, &l2_slice, &l2_index);
1186 if (ret < 0) {
1187 return ret;
1188 }
1189
1190 cluster_offset = be64_to_cpu(l2_slice[l2_index]);
1191
1192 /* Check how many clusters are already allocated and don't need COW */
1193 if (qcow2_get_cluster_type(bs, cluster_offset) == QCOW2_CLUSTER_NORMAL
1194 && (cluster_offset & QCOW_OFLAG_COPIED))
1195 {
1196 /* If a specific host_offset is required, check it */
1197 bool offset_matches =
1198 (cluster_offset & L2E_OFFSET_MASK) == *host_offset;
1199
1200 if (offset_into_cluster(s, cluster_offset & L2E_OFFSET_MASK)) {
1201 qcow2_signal_corruption(bs, true, -1, -1, "Data cluster offset "
1202 "%#llx unaligned (guest offset: %#" PRIx64
1203 ")", cluster_offset & L2E_OFFSET_MASK,
1204 guest_offset);
1205 ret = -EIO;
1206 goto out;
1207 }
1208
1209 if (*host_offset != INV_OFFSET && !offset_matches) {
1210 *bytes = 0;
1211 ret = 0;
1212 goto out;
1213 }
1214
1215 /* We keep all QCOW_OFLAG_COPIED clusters */
1216 keep_clusters =
1217 count_contiguous_clusters(bs, nb_clusters, s->cluster_size,
1218 &l2_slice[l2_index],
1219 QCOW_OFLAG_COPIED | QCOW_OFLAG_ZERO);
1220 assert(keep_clusters <= nb_clusters);
1221
1222 *bytes = MIN(*bytes,
1223 keep_clusters * s->cluster_size
1224 - offset_into_cluster(s, guest_offset));
1225
1226 ret = 1;
1227 } else {
1228 ret = 0;
1229 }
1230
1231 /* Cleanup */
1232out:
1233 qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice);
1234
1235 /* Only return a host offset if we actually made progress. Otherwise we
1236 * would make requirements for handle_alloc() that it can't fulfill */
1237 if (ret > 0) {
1238 *host_offset = (cluster_offset & L2E_OFFSET_MASK)
1239 + offset_into_cluster(s, guest_offset);
1240 }
1241
1242 return ret;
1243}
1244
1245/*
1246 * Allocates new clusters for the given guest_offset.
1247 *
1248 * At most *nb_clusters are allocated, and on return *nb_clusters is updated to
1249 * contain the number of clusters that have been allocated and are contiguous
1250 * in the image file.
1251 *
1252 * If *host_offset is not INV_OFFSET, it specifies the offset in the image file
1253 * at which the new clusters must start. *nb_clusters can be 0 on return in
1254 * this case if the cluster at host_offset is already in use. If *host_offset
1255 * is INV_OFFSET, the clusters can be allocated anywhere in the image file.
1256 *
1257 * *host_offset is updated to contain the offset into the image file at which
1258 * the first allocated cluster starts.
1259 *
1260 * Return 0 on success and -errno in error cases. -EAGAIN means that the
1261 * function has been waiting for another request and the allocation must be
1262 * restarted, but the whole request should not be failed.
1263 */
1264static int do_alloc_cluster_offset(BlockDriverState *bs, uint64_t guest_offset,
1265 uint64_t *host_offset, uint64_t *nb_clusters)
1266{
1267 BDRVQcow2State *s = bs->opaque;
1268
1269 trace_qcow2_do_alloc_clusters_offset(qemu_coroutine_self(), guest_offset,
1270 *host_offset, *nb_clusters);
1271
1272 if (has_data_file(bs)) {
1273 assert(*host_offset == INV_OFFSET ||
1274 *host_offset == start_of_cluster(s, guest_offset));
1275 *host_offset = start_of_cluster(s, guest_offset);
1276 return 0;
1277 }
1278
1279 /* Allocate new clusters */
1280 trace_qcow2_cluster_alloc_phys(qemu_coroutine_self());
1281 if (*host_offset == INV_OFFSET) {
1282 int64_t cluster_offset =
1283 qcow2_alloc_clusters(bs, *nb_clusters * s->cluster_size);
1284 if (cluster_offset < 0) {
1285 return cluster_offset;
1286 }
1287 *host_offset = cluster_offset;
1288 return 0;
1289 } else {
1290 int64_t ret = qcow2_alloc_clusters_at(bs, *host_offset, *nb_clusters);
1291 if (ret < 0) {
1292 return ret;
1293 }
1294 *nb_clusters = ret;
1295 return 0;
1296 }
1297}
1298
1299/*
1300 * Allocates new clusters for an area that either is yet unallocated or needs a
1301 * copy on write. If *host_offset is not INV_OFFSET, clusters are only
1302 * allocated if the new allocation can match the specified host offset.
1303 *
1304 * Note that guest_offset may not be cluster aligned. In this case, the
1305 * returned *host_offset points to exact byte referenced by guest_offset and
1306 * therefore isn't cluster aligned as well.
1307 *
1308 * Returns:
1309 * 0: if no clusters could be allocated. *bytes is set to 0,
1310 * *host_offset is left unchanged.
1311 *
1312 * 1: if new clusters were allocated. *bytes may be decreased if the
1313 * new allocation doesn't cover all of the requested area.
1314 * *host_offset is updated to contain the host offset of the first
1315 * newly allocated cluster.
1316 *
1317 * -errno: in error cases
1318 */
1319static int handle_alloc(BlockDriverState *bs, uint64_t guest_offset,
1320 uint64_t *host_offset, uint64_t *bytes, QCowL2Meta **m)
1321{
1322 BDRVQcow2State *s = bs->opaque;
1323 int l2_index;
1324 uint64_t *l2_slice;
1325 uint64_t entry;
1326 uint64_t nb_clusters;
1327 int ret;
1328 bool keep_old_clusters = false;
1329
1330 uint64_t alloc_cluster_offset = INV_OFFSET;
1331
1332 trace_qcow2_handle_alloc(qemu_coroutine_self(), guest_offset, *host_offset,
1333 *bytes);
1334 assert(*bytes > 0);
1335
1336 /*
1337 * Calculate the number of clusters to look for. We stop at L2 slice
1338 * boundaries to keep things simple.
1339 */
1340 nb_clusters =
1341 size_to_clusters(s, offset_into_cluster(s, guest_offset) + *bytes);
1342
1343 l2_index = offset_to_l2_slice_index(s, guest_offset);
1344 nb_clusters = MIN(nb_clusters, s->l2_slice_size - l2_index);
1345 assert(nb_clusters <= INT_MAX);
1346
1347 /* Find L2 entry for the first involved cluster */
1348 ret = get_cluster_table(bs, guest_offset, &l2_slice, &l2_index);
1349 if (ret < 0) {
1350 return ret;
1351 }
1352
1353 entry = be64_to_cpu(l2_slice[l2_index]);
1354
1355 /* For the moment, overwrite compressed clusters one by one */
1356 if (entry & QCOW_OFLAG_COMPRESSED) {
1357 nb_clusters = 1;
1358 } else {
1359 nb_clusters = count_cow_clusters(bs, nb_clusters, l2_slice, l2_index);
1360 }
1361
1362 /* This function is only called when there were no non-COW clusters, so if
1363 * we can't find any unallocated or COW clusters either, something is
1364 * wrong with our code. */
1365 assert(nb_clusters > 0);
1366
1367 if (qcow2_get_cluster_type(bs, entry) == QCOW2_CLUSTER_ZERO_ALLOC &&
1368 (entry & QCOW_OFLAG_COPIED) &&
1369 (*host_offset == INV_OFFSET ||
1370 start_of_cluster(s, *host_offset) == (entry & L2E_OFFSET_MASK)))
1371 {
1372 int preallocated_nb_clusters;
1373
1374 if (offset_into_cluster(s, entry & L2E_OFFSET_MASK)) {
1375 qcow2_signal_corruption(bs, true, -1, -1, "Preallocated zero "
1376 "cluster offset %#llx unaligned (guest "
1377 "offset: %#" PRIx64 ")",
1378 entry & L2E_OFFSET_MASK, guest_offset);
1379 ret = -EIO;
1380 goto fail;
1381 }
1382
1383 /* Try to reuse preallocated zero clusters; contiguous normal clusters
1384 * would be fine, too, but count_cow_clusters() above has limited
1385 * nb_clusters already to a range of COW clusters */
1386 preallocated_nb_clusters =
1387 count_contiguous_clusters(bs, nb_clusters, s->cluster_size,
1388 &l2_slice[l2_index], QCOW_OFLAG_COPIED);
1389 assert(preallocated_nb_clusters > 0);
1390
1391 nb_clusters = preallocated_nb_clusters;
1392 alloc_cluster_offset = entry & L2E_OFFSET_MASK;
1393
1394 /* We want to reuse these clusters, so qcow2_alloc_cluster_link_l2()
1395 * should not free them. */
1396 keep_old_clusters = true;
1397 }
1398
1399 qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice);
1400
1401 if (alloc_cluster_offset == INV_OFFSET) {
1402 /* Allocate, if necessary at a given offset in the image file */
1403 alloc_cluster_offset = *host_offset == INV_OFFSET ? INV_OFFSET :
1404 start_of_cluster(s, *host_offset);
1405 ret = do_alloc_cluster_offset(bs, guest_offset, &alloc_cluster_offset,
1406 &nb_clusters);
1407 if (ret < 0) {
1408 goto fail;
1409 }
1410
1411 /* Can't extend contiguous allocation */
1412 if (nb_clusters == 0) {
1413 *bytes = 0;
1414 return 0;
1415 }
1416
1417 assert(alloc_cluster_offset != INV_OFFSET);
1418 }
1419
1420 /*
1421 * Save info needed for meta data update.
1422 *
1423 * requested_bytes: Number of bytes from the start of the first
1424 * newly allocated cluster to the end of the (possibly shortened
1425 * before) write request.
1426 *
1427 * avail_bytes: Number of bytes from the start of the first
1428 * newly allocated to the end of the last newly allocated cluster.
1429 *
1430 * nb_bytes: The number of bytes from the start of the first
1431 * newly allocated cluster to the end of the area that the write
1432 * request actually writes to (excluding COW at the end)
1433 */
1434 uint64_t requested_bytes = *bytes + offset_into_cluster(s, guest_offset);
1435 int avail_bytes = MIN(INT_MAX, nb_clusters << s->cluster_bits);
1436 int nb_bytes = MIN(requested_bytes, avail_bytes);
1437 QCowL2Meta *old_m = *m;
1438
1439 *m = g_malloc0(sizeof(**m));
1440
1441 **m = (QCowL2Meta) {
1442 .next = old_m,
1443
1444 .alloc_offset = alloc_cluster_offset,
1445 .offset = start_of_cluster(s, guest_offset),
1446 .nb_clusters = nb_clusters,
1447
1448 .keep_old_clusters = keep_old_clusters,
1449
1450 .cow_start = {
1451 .offset = 0,
1452 .nb_bytes = offset_into_cluster(s, guest_offset),
1453 },
1454 .cow_end = {
1455 .offset = nb_bytes,
1456 .nb_bytes = avail_bytes - nb_bytes,
1457 },
1458 };
1459 qemu_co_queue_init(&(*m)->dependent_requests);
1460 QLIST_INSERT_HEAD(&s->cluster_allocs, *m, next_in_flight);
1461
1462 *host_offset = alloc_cluster_offset + offset_into_cluster(s, guest_offset);
1463 *bytes = MIN(*bytes, nb_bytes - offset_into_cluster(s, guest_offset));
1464 assert(*bytes != 0);
1465
1466 return 1;
1467
1468fail:
1469 if (*m && (*m)->nb_clusters > 0) {
1470 QLIST_REMOVE(*m, next_in_flight);
1471 }
1472 return ret;
1473}
1474
1475/*
1476 * alloc_cluster_offset
1477 *
1478 * For a given offset on the virtual disk, find the cluster offset in qcow2
1479 * file. If the offset is not found, allocate a new cluster.
1480 *
1481 * If the cluster was already allocated, m->nb_clusters is set to 0 and
1482 * other fields in m are meaningless.
1483 *
1484 * If the cluster is newly allocated, m->nb_clusters is set to the number of
1485 * contiguous clusters that have been allocated. In this case, the other
1486 * fields of m are valid and contain information about the first allocated
1487 * cluster.
1488 *
1489 * If the request conflicts with another write request in flight, the coroutine
1490 * is queued and will be reentered when the dependency has completed.
1491 *
1492 * Return 0 on success and -errno in error cases
1493 */
1494int qcow2_alloc_cluster_offset(BlockDriverState *bs, uint64_t offset,
1495 unsigned int *bytes, uint64_t *host_offset,
1496 QCowL2Meta **m)
1497{
1498 BDRVQcow2State *s = bs->opaque;
1499 uint64_t start, remaining;
1500 uint64_t cluster_offset;
1501 uint64_t cur_bytes;
1502 int ret;
1503
1504 trace_qcow2_alloc_clusters_offset(qemu_coroutine_self(), offset, *bytes);
1505
1506again:
1507 start = offset;
1508 remaining = *bytes;
1509 cluster_offset = INV_OFFSET;
1510 *host_offset = INV_OFFSET;
1511 cur_bytes = 0;
1512 *m = NULL;
1513
1514 while (true) {
1515
1516 if (*host_offset == INV_OFFSET && cluster_offset != INV_OFFSET) {
1517 *host_offset = start_of_cluster(s, cluster_offset);
1518 }
1519
1520 assert(remaining >= cur_bytes);
1521
1522 start += cur_bytes;
1523 remaining -= cur_bytes;
1524
1525 if (cluster_offset != INV_OFFSET) {
1526 cluster_offset += cur_bytes;
1527 }
1528
1529 if (remaining == 0) {
1530 break;
1531 }
1532
1533 cur_bytes = remaining;
1534
1535 /*
1536 * Now start gathering as many contiguous clusters as possible:
1537 *
1538 * 1. Check for overlaps with in-flight allocations
1539 *
1540 * a) Overlap not in the first cluster -> shorten this request and
1541 * let the caller handle the rest in its next loop iteration.
1542 *
1543 * b) Real overlaps of two requests. Yield and restart the search
1544 * for contiguous clusters (the situation could have changed
1545 * while we were sleeping)
1546 *
1547 * c) TODO: Request starts in the same cluster as the in-flight
1548 * allocation ends. Shorten the COW of the in-fight allocation,
1549 * set cluster_offset to write to the same cluster and set up
1550 * the right synchronisation between the in-flight request and
1551 * the new one.
1552 */
1553 ret = handle_dependencies(bs, start, &cur_bytes, m);
1554 if (ret == -EAGAIN) {
1555 /* Currently handle_dependencies() doesn't yield if we already had
1556 * an allocation. If it did, we would have to clean up the L2Meta
1557 * structs before starting over. */
1558 assert(*m == NULL);
1559 goto again;
1560 } else if (ret < 0) {
1561 return ret;
1562 } else if (cur_bytes == 0) {
1563 break;
1564 } else {
1565 /* handle_dependencies() may have decreased cur_bytes (shortened
1566 * the allocations below) so that the next dependency is processed
1567 * correctly during the next loop iteration. */
1568 }
1569
1570 /*
1571 * 2. Count contiguous COPIED clusters.
1572 */
1573 ret = handle_copied(bs, start, &cluster_offset, &cur_bytes, m);
1574 if (ret < 0) {
1575 return ret;
1576 } else if (ret) {
1577 continue;
1578 } else if (cur_bytes == 0) {
1579 break;
1580 }
1581
1582 /*
1583 * 3. If the request still hasn't completed, allocate new clusters,
1584 * considering any cluster_offset of steps 1c or 2.
1585 */
1586 ret = handle_alloc(bs, start, &cluster_offset, &cur_bytes, m);
1587 if (ret < 0) {
1588 return ret;
1589 } else if (ret) {
1590 continue;
1591 } else {
1592 assert(cur_bytes == 0);
1593 break;
1594 }
1595 }
1596
1597 *bytes -= remaining;
1598 assert(*bytes > 0);
1599 assert(*host_offset != INV_OFFSET);
1600
1601 return 0;
1602}
1603
1604/*
1605 * This discards as many clusters of nb_clusters as possible at once (i.e.
1606 * all clusters in the same L2 slice) and returns the number of discarded
1607 * clusters.
1608 */
1609static int discard_in_l2_slice(BlockDriverState *bs, uint64_t offset,
1610 uint64_t nb_clusters,
1611 enum qcow2_discard_type type, bool full_discard)
1612{
1613 BDRVQcow2State *s = bs->opaque;
1614 uint64_t *l2_slice;
1615 int l2_index;
1616 int ret;
1617 int i;
1618
1619 ret = get_cluster_table(bs, offset, &l2_slice, &l2_index);
1620 if (ret < 0) {
1621 return ret;
1622 }
1623
1624 /* Limit nb_clusters to one L2 slice */
1625 nb_clusters = MIN(nb_clusters, s->l2_slice_size - l2_index);
1626 assert(nb_clusters <= INT_MAX);
1627
1628 for (i = 0; i < nb_clusters; i++) {
1629 uint64_t old_l2_entry;
1630
1631 old_l2_entry = be64_to_cpu(l2_slice[l2_index + i]);
1632
1633 /*
1634 * If full_discard is false, make sure that a discarded area reads back
1635 * as zeroes for v3 images (we cannot do it for v2 without actually
1636 * writing a zero-filled buffer). We can skip the operation if the
1637 * cluster is already marked as zero, or if it's unallocated and we
1638 * don't have a backing file.
1639 *
1640 * TODO We might want to use bdrv_block_status(bs) here, but we're
1641 * holding s->lock, so that doesn't work today.
1642 *
1643 * If full_discard is true, the sector should not read back as zeroes,
1644 * but rather fall through to the backing file.
1645 */
1646 switch (qcow2_get_cluster_type(bs, old_l2_entry)) {
1647 case QCOW2_CLUSTER_UNALLOCATED:
1648 if (full_discard || !bs->backing) {
1649 continue;
1650 }
1651 break;
1652
1653 case QCOW2_CLUSTER_ZERO_PLAIN:
1654 if (!full_discard) {
1655 continue;
1656 }
1657 break;
1658
1659 case QCOW2_CLUSTER_ZERO_ALLOC:
1660 case QCOW2_CLUSTER_NORMAL:
1661 case QCOW2_CLUSTER_COMPRESSED:
1662 break;
1663
1664 default:
1665 abort();
1666 }
1667
1668 /* First remove L2 entries */
1669 qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_slice);
1670 if (!full_discard && s->qcow_version >= 3) {
1671 l2_slice[l2_index + i] = cpu_to_be64(QCOW_OFLAG_ZERO);
1672 } else {
1673 l2_slice[l2_index + i] = cpu_to_be64(0);
1674 }
1675
1676 /* Then decrease the refcount */
1677 qcow2_free_any_clusters(bs, old_l2_entry, 1, type);
1678 }
1679
1680 qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice);
1681
1682 return nb_clusters;
1683}
1684
1685int qcow2_cluster_discard(BlockDriverState *bs, uint64_t offset,
1686 uint64_t bytes, enum qcow2_discard_type type,
1687 bool full_discard)
1688{
1689 BDRVQcow2State *s = bs->opaque;
1690 uint64_t end_offset = offset + bytes;
1691 uint64_t nb_clusters;
1692 int64_t cleared;
1693 int ret;
1694
1695 /* Caller must pass aligned values, except at image end */
1696 assert(QEMU_IS_ALIGNED(offset, s->cluster_size));
1697 assert(QEMU_IS_ALIGNED(end_offset, s->cluster_size) ||
1698 end_offset == bs->total_sectors << BDRV_SECTOR_BITS);
1699
1700 nb_clusters = size_to_clusters(s, bytes);
1701
1702 s->cache_discards = true;
1703
1704 /* Each L2 slice is handled by its own loop iteration */
1705 while (nb_clusters > 0) {
1706 cleared = discard_in_l2_slice(bs, offset, nb_clusters, type,
1707 full_discard);
1708 if (cleared < 0) {
1709 ret = cleared;
1710 goto fail;
1711 }
1712
1713 nb_clusters -= cleared;
1714 offset += (cleared * s->cluster_size);
1715 }
1716
1717 ret = 0;
1718fail:
1719 s->cache_discards = false;
1720 qcow2_process_discards(bs, ret);
1721
1722 return ret;
1723}
1724
1725/*
1726 * This zeroes as many clusters of nb_clusters as possible at once (i.e.
1727 * all clusters in the same L2 slice) and returns the number of zeroed
1728 * clusters.
1729 */
1730static int zero_in_l2_slice(BlockDriverState *bs, uint64_t offset,
1731 uint64_t nb_clusters, int flags)
1732{
1733 BDRVQcow2State *s = bs->opaque;
1734 uint64_t *l2_slice;
1735 int l2_index;
1736 int ret;
1737 int i;
1738 bool unmap = !!(flags & BDRV_REQ_MAY_UNMAP);
1739
1740 ret = get_cluster_table(bs, offset, &l2_slice, &l2_index);
1741 if (ret < 0) {
1742 return ret;
1743 }
1744
1745 /* Limit nb_clusters to one L2 slice */
1746 nb_clusters = MIN(nb_clusters, s->l2_slice_size - l2_index);
1747 assert(nb_clusters <= INT_MAX);
1748
1749 for (i = 0; i < nb_clusters; i++) {
1750 uint64_t old_offset;
1751 QCow2ClusterType cluster_type;
1752
1753 old_offset = be64_to_cpu(l2_slice[l2_index + i]);
1754
1755 /*
1756 * Minimize L2 changes if the cluster already reads back as
1757 * zeroes with correct allocation.
1758 */
1759 cluster_type = qcow2_get_cluster_type(bs, old_offset);
1760 if (cluster_type == QCOW2_CLUSTER_ZERO_PLAIN ||
1761 (cluster_type == QCOW2_CLUSTER_ZERO_ALLOC && !unmap)) {
1762 continue;
1763 }
1764
1765 qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_slice);
1766 if (cluster_type == QCOW2_CLUSTER_COMPRESSED || unmap) {
1767 l2_slice[l2_index + i] = cpu_to_be64(QCOW_OFLAG_ZERO);
1768 qcow2_free_any_clusters(bs, old_offset, 1, QCOW2_DISCARD_REQUEST);
1769 } else {
1770 l2_slice[l2_index + i] |= cpu_to_be64(QCOW_OFLAG_ZERO);
1771 }
1772 }
1773
1774 qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice);
1775
1776 return nb_clusters;
1777}
1778
1779int qcow2_cluster_zeroize(BlockDriverState *bs, uint64_t offset,
1780 uint64_t bytes, int flags)
1781{
1782 BDRVQcow2State *s = bs->opaque;
1783 uint64_t end_offset = offset + bytes;
1784 uint64_t nb_clusters;
1785 int64_t cleared;
1786 int ret;
1787
1788 /* If we have to stay in sync with an external data file, zero out
1789 * s->data_file first. */
1790 if (data_file_is_raw(bs)) {
1791 assert(has_data_file(bs));
1792 ret = bdrv_co_pwrite_zeroes(s->data_file, offset, bytes, flags);
1793 if (ret < 0) {
1794 return ret;
1795 }
1796 }
1797
1798 /* Caller must pass aligned values, except at image end */
1799 assert(QEMU_IS_ALIGNED(offset, s->cluster_size));
1800 assert(QEMU_IS_ALIGNED(end_offset, s->cluster_size) ||
1801 end_offset == bs->total_sectors << BDRV_SECTOR_BITS);
1802
1803 /* The zero flag is only supported by version 3 and newer */
1804 if (s->qcow_version < 3) {
1805 return -ENOTSUP;
1806 }
1807
1808 /* Each L2 slice is handled by its own loop iteration */
1809 nb_clusters = size_to_clusters(s, bytes);
1810
1811 s->cache_discards = true;
1812
1813 while (nb_clusters > 0) {
1814 cleared = zero_in_l2_slice(bs, offset, nb_clusters, flags);
1815 if (cleared < 0) {
1816 ret = cleared;
1817 goto fail;
1818 }
1819
1820 nb_clusters -= cleared;
1821 offset += (cleared * s->cluster_size);
1822 }
1823
1824 ret = 0;
1825fail:
1826 s->cache_discards = false;
1827 qcow2_process_discards(bs, ret);
1828
1829 return ret;
1830}
1831
1832/*
1833 * Expands all zero clusters in a specific L1 table (or deallocates them, for
1834 * non-backed non-pre-allocated zero clusters).
1835 *
1836 * l1_entries and *visited_l1_entries are used to keep track of progress for
1837 * status_cb(). l1_entries contains the total number of L1 entries and
1838 * *visited_l1_entries counts all visited L1 entries.
1839 */
1840static int expand_zero_clusters_in_l1(BlockDriverState *bs, uint64_t *l1_table,
1841 int l1_size, int64_t *visited_l1_entries,
1842 int64_t l1_entries,
1843 BlockDriverAmendStatusCB *status_cb,
1844 void *cb_opaque)
1845{
1846 BDRVQcow2State *s = bs->opaque;
1847 bool is_active_l1 = (l1_table == s->l1_table);
1848 uint64_t *l2_slice = NULL;
1849 unsigned slice, slice_size2, n_slices;
1850 int ret;
1851 int i, j;
1852
1853 slice_size2 = s->l2_slice_size * sizeof(uint64_t);
1854 n_slices = s->cluster_size / slice_size2;
1855
1856 if (!is_active_l1) {
1857 /* inactive L2 tables require a buffer to be stored in when loading
1858 * them from disk */
1859 l2_slice = qemu_try_blockalign(bs->file->bs, slice_size2);
1860 if (l2_slice == NULL) {
1861 return -ENOMEM;
1862 }
1863 }
1864
1865 for (i = 0; i < l1_size; i++) {
1866 uint64_t l2_offset = l1_table[i] & L1E_OFFSET_MASK;
1867 uint64_t l2_refcount;
1868
1869 if (!l2_offset) {
1870 /* unallocated */
1871 (*visited_l1_entries)++;
1872 if (status_cb) {
1873 status_cb(bs, *visited_l1_entries, l1_entries, cb_opaque);
1874 }
1875 continue;
1876 }
1877
1878 if (offset_into_cluster(s, l2_offset)) {
1879 qcow2_signal_corruption(bs, true, -1, -1, "L2 table offset %#"
1880 PRIx64 " unaligned (L1 index: %#x)",
1881 l2_offset, i);
1882 ret = -EIO;
1883 goto fail;
1884 }
1885
1886 ret = qcow2_get_refcount(bs, l2_offset >> s->cluster_bits,
1887 &l2_refcount);
1888 if (ret < 0) {
1889 goto fail;
1890 }
1891
1892 for (slice = 0; slice < n_slices; slice++) {
1893 uint64_t slice_offset = l2_offset + slice * slice_size2;
1894 bool l2_dirty = false;
1895 if (is_active_l1) {
1896 /* get active L2 tables from cache */
1897 ret = qcow2_cache_get(bs, s->l2_table_cache, slice_offset,
1898 (void **)&l2_slice);
1899 } else {
1900 /* load inactive L2 tables from disk */
1901 ret = bdrv_pread(bs->file, slice_offset, l2_slice, slice_size2);
1902 }
1903 if (ret < 0) {
1904 goto fail;
1905 }
1906
1907 for (j = 0; j < s->l2_slice_size; j++) {
1908 uint64_t l2_entry = be64_to_cpu(l2_slice[j]);
1909 int64_t offset = l2_entry & L2E_OFFSET_MASK;
1910 QCow2ClusterType cluster_type =
1911 qcow2_get_cluster_type(bs, l2_entry);
1912
1913 if (cluster_type != QCOW2_CLUSTER_ZERO_PLAIN &&
1914 cluster_type != QCOW2_CLUSTER_ZERO_ALLOC) {
1915 continue;
1916 }
1917
1918 if (cluster_type == QCOW2_CLUSTER_ZERO_PLAIN) {
1919 if (!bs->backing) {
1920 /* not backed; therefore we can simply deallocate the
1921 * cluster */
1922 l2_slice[j] = 0;
1923 l2_dirty = true;
1924 continue;
1925 }
1926
1927 offset = qcow2_alloc_clusters(bs, s->cluster_size);
1928 if (offset < 0) {
1929 ret = offset;
1930 goto fail;
1931 }
1932
1933 if (l2_refcount > 1) {
1934 /* For shared L2 tables, set the refcount accordingly
1935 * (it is already 1 and needs to be l2_refcount) */
1936 ret = qcow2_update_cluster_refcount(
1937 bs, offset >> s->cluster_bits,
1938 refcount_diff(1, l2_refcount), false,
1939 QCOW2_DISCARD_OTHER);
1940 if (ret < 0) {
1941 qcow2_free_clusters(bs, offset, s->cluster_size,
1942 QCOW2_DISCARD_OTHER);
1943 goto fail;
1944 }
1945 }
1946 }
1947
1948 if (offset_into_cluster(s, offset)) {
1949 int l2_index = slice * s->l2_slice_size + j;
1950 qcow2_signal_corruption(
1951 bs, true, -1, -1,
1952 "Cluster allocation offset "
1953 "%#" PRIx64 " unaligned (L2 offset: %#"
1954 PRIx64 ", L2 index: %#x)", offset,
1955 l2_offset, l2_index);
1956 if (cluster_type == QCOW2_CLUSTER_ZERO_PLAIN) {
1957 qcow2_free_clusters(bs, offset, s->cluster_size,
1958 QCOW2_DISCARD_ALWAYS);
1959 }
1960 ret = -EIO;
1961 goto fail;
1962 }
1963
1964 ret = qcow2_pre_write_overlap_check(bs, 0, offset,
1965 s->cluster_size, true);
1966 if (ret < 0) {
1967 if (cluster_type == QCOW2_CLUSTER_ZERO_PLAIN) {
1968 qcow2_free_clusters(bs, offset, s->cluster_size,
1969 QCOW2_DISCARD_ALWAYS);
1970 }
1971 goto fail;
1972 }
1973
1974 ret = bdrv_pwrite_zeroes(s->data_file, offset,
1975 s->cluster_size, 0);
1976 if (ret < 0) {
1977 if (cluster_type == QCOW2_CLUSTER_ZERO_PLAIN) {
1978 qcow2_free_clusters(bs, offset, s->cluster_size,
1979 QCOW2_DISCARD_ALWAYS);
1980 }
1981 goto fail;
1982 }
1983
1984 if (l2_refcount == 1) {
1985 l2_slice[j] = cpu_to_be64(offset | QCOW_OFLAG_COPIED);
1986 } else {
1987 l2_slice[j] = cpu_to_be64(offset);
1988 }
1989 l2_dirty = true;
1990 }
1991
1992 if (is_active_l1) {
1993 if (l2_dirty) {
1994 qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_slice);
1995 qcow2_cache_depends_on_flush(s->l2_table_cache);
1996 }
1997 qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice);
1998 } else {
1999 if (l2_dirty) {
2000 ret = qcow2_pre_write_overlap_check(
2001 bs, QCOW2_OL_INACTIVE_L2 | QCOW2_OL_ACTIVE_L2,
2002 slice_offset, slice_size2, false);
2003 if (ret < 0) {
2004 goto fail;
2005 }
2006
2007 ret = bdrv_pwrite(bs->file, slice_offset,
2008 l2_slice, slice_size2);
2009 if (ret < 0) {
2010 goto fail;
2011 }
2012 }
2013 }
2014 }
2015
2016 (*visited_l1_entries)++;
2017 if (status_cb) {
2018 status_cb(bs, *visited_l1_entries, l1_entries, cb_opaque);
2019 }
2020 }
2021
2022 ret = 0;
2023
2024fail:
2025 if (l2_slice) {
2026 if (!is_active_l1) {
2027 qemu_vfree(l2_slice);
2028 } else {
2029 qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice);
2030 }
2031 }
2032 return ret;
2033}
2034
2035/*
2036 * For backed images, expands all zero clusters on the image. For non-backed
2037 * images, deallocates all non-pre-allocated zero clusters (and claims the
2038 * allocation for pre-allocated ones). This is important for downgrading to a
2039 * qcow2 version which doesn't yet support metadata zero clusters.
2040 */
2041int qcow2_expand_zero_clusters(BlockDriverState *bs,
2042 BlockDriverAmendStatusCB *status_cb,
2043 void *cb_opaque)
2044{
2045 BDRVQcow2State *s = bs->opaque;
2046 uint64_t *l1_table = NULL;
2047 int64_t l1_entries = 0, visited_l1_entries = 0;
2048 int ret;
2049 int i, j;
2050
2051 if (status_cb) {
2052 l1_entries = s->l1_size;
2053 for (i = 0; i < s->nb_snapshots; i++) {
2054 l1_entries += s->snapshots[i].l1_size;
2055 }
2056 }
2057
2058 ret = expand_zero_clusters_in_l1(bs, s->l1_table, s->l1_size,
2059 &visited_l1_entries, l1_entries,
2060 status_cb, cb_opaque);
2061 if (ret < 0) {
2062 goto fail;
2063 }
2064
2065 /* Inactive L1 tables may point to active L2 tables - therefore it is
2066 * necessary to flush the L2 table cache before trying to access the L2
2067 * tables pointed to by inactive L1 entries (else we might try to expand
2068 * zero clusters that have already been expanded); furthermore, it is also
2069 * necessary to empty the L2 table cache, since it may contain tables which
2070 * are now going to be modified directly on disk, bypassing the cache.
2071 * qcow2_cache_empty() does both for us. */
2072 ret = qcow2_cache_empty(bs, s->l2_table_cache);
2073 if (ret < 0) {
2074 goto fail;
2075 }
2076
2077 for (i = 0; i < s->nb_snapshots; i++) {
2078 int l1_size2;
2079 uint64_t *new_l1_table;
2080 Error *local_err = NULL;
2081
2082 ret = qcow2_validate_table(bs, s->snapshots[i].l1_table_offset,
2083 s->snapshots[i].l1_size, sizeof(uint64_t),
2084 QCOW_MAX_L1_SIZE, "Snapshot L1 table",
2085 &local_err);
2086 if (ret < 0) {
2087 error_report_err(local_err);
2088 goto fail;
2089 }
2090
2091 l1_size2 = s->snapshots[i].l1_size * sizeof(uint64_t);
2092 new_l1_table = g_try_realloc(l1_table, l1_size2);
2093
2094 if (!new_l1_table) {
2095 ret = -ENOMEM;
2096 goto fail;
2097 }
2098
2099 l1_table = new_l1_table;
2100
2101 ret = bdrv_pread(bs->file, s->snapshots[i].l1_table_offset,
2102 l1_table, l1_size2);
2103 if (ret < 0) {
2104 goto fail;
2105 }
2106
2107 for (j = 0; j < s->snapshots[i].l1_size; j++) {
2108 be64_to_cpus(&l1_table[j]);
2109 }
2110
2111 ret = expand_zero_clusters_in_l1(bs, l1_table, s->snapshots[i].l1_size,
2112 &visited_l1_entries, l1_entries,
2113 status_cb, cb_opaque);
2114 if (ret < 0) {
2115 goto fail;
2116 }
2117 }
2118
2119 ret = 0;
2120
2121fail:
2122 g_free(l1_table);
2123 return ret;
2124}
2125