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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 "block/block-io.h" | |
29 | #include "qapi/error.h" | |
30 | #include "qcow2.h" | |
31 | #include "qemu/bswap.h" | |
32 | #include "qemu/memalign.h" | |
33 | #include "trace.h" | |
34 | ||
35 | int coroutine_fn qcow2_shrink_l1_table(BlockDriverState *bs, | |
36 | uint64_t exact_size) | |
37 | { | |
38 | BDRVQcow2State *s = bs->opaque; | |
39 | int new_l1_size, i, ret; | |
40 | ||
41 | if (exact_size >= s->l1_size) { | |
42 | return 0; | |
43 | } | |
44 | ||
45 | new_l1_size = exact_size; | |
46 | ||
47 | #ifdef DEBUG_ALLOC2 | |
48 | fprintf(stderr, "shrink l1_table from %d to %d\n", s->l1_size, new_l1_size); | |
49 | #endif | |
50 | ||
51 | BLKDBG_CO_EVENT(bs->file, BLKDBG_L1_SHRINK_WRITE_TABLE); | |
52 | ret = bdrv_co_pwrite_zeroes(bs->file, | |
53 | s->l1_table_offset + new_l1_size * L1E_SIZE, | |
54 | (s->l1_size - new_l1_size) * L1E_SIZE, 0); | |
55 | if (ret < 0) { | |
56 | goto fail; | |
57 | } | |
58 | ||
59 | ret = bdrv_co_flush(bs->file->bs); | |
60 | if (ret < 0) { | |
61 | goto fail; | |
62 | } | |
63 | ||
64 | BLKDBG_CO_EVENT(bs->file, BLKDBG_L1_SHRINK_FREE_L2_CLUSTERS); | |
65 | for (i = s->l1_size - 1; i > new_l1_size - 1; i--) { | |
66 | if ((s->l1_table[i] & L1E_OFFSET_MASK) == 0) { | |
67 | continue; | |
68 | } | |
69 | qcow2_free_clusters(bs, s->l1_table[i] & L1E_OFFSET_MASK, | |
70 | s->cluster_size, QCOW2_DISCARD_ALWAYS); | |
71 | s->l1_table[i] = 0; | |
72 | } | |
73 | return 0; | |
74 | ||
75 | fail: | |
76 | /* | |
77 | * If the write in the l1_table failed the image may contain a partially | |
78 | * overwritten l1_table. In this case it would be better to clear the | |
79 | * l1_table in memory to avoid possible image corruption. | |
80 | */ | |
81 | memset(s->l1_table + new_l1_size, 0, | |
82 | (s->l1_size - new_l1_size) * L1E_SIZE); | |
83 | return ret; | |
84 | } | |
85 | ||
86 | int qcow2_grow_l1_table(BlockDriverState *bs, uint64_t min_size, | |
87 | bool exact_size) | |
88 | { | |
89 | BDRVQcow2State *s = bs->opaque; | |
90 | int new_l1_size2, ret, i; | |
91 | uint64_t *new_l1_table; | |
92 | int64_t old_l1_table_offset, old_l1_size; | |
93 | int64_t new_l1_table_offset, new_l1_size; | |
94 | uint8_t data[12]; | |
95 | ||
96 | if (min_size <= s->l1_size) | |
97 | return 0; | |
98 | ||
99 | /* Do a sanity check on min_size before trying to calculate new_l1_size | |
100 | * (this prevents overflows during the while loop for the calculation of | |
101 | * new_l1_size) */ | |
102 | if (min_size > INT_MAX / L1E_SIZE) { | |
103 | return -EFBIG; | |
104 | } | |
105 | ||
106 | if (exact_size) { | |
107 | new_l1_size = min_size; | |
108 | } else { | |
109 | /* Bump size up to reduce the number of times we have to grow */ | |
110 | new_l1_size = s->l1_size; | |
111 | if (new_l1_size == 0) { | |
112 | new_l1_size = 1; | |
113 | } | |
114 | while (min_size > new_l1_size) { | |
115 | new_l1_size = DIV_ROUND_UP(new_l1_size * 3, 2); | |
116 | } | |
117 | } | |
118 | ||
119 | QEMU_BUILD_BUG_ON(QCOW_MAX_L1_SIZE > INT_MAX); | |
120 | if (new_l1_size > QCOW_MAX_L1_SIZE / L1E_SIZE) { | |
121 | return -EFBIG; | |
122 | } | |
123 | ||
124 | #ifdef DEBUG_ALLOC2 | |
125 | fprintf(stderr, "grow l1_table from %d to %" PRId64 "\n", | |
126 | s->l1_size, new_l1_size); | |
127 | #endif | |
128 | ||
129 | new_l1_size2 = L1E_SIZE * new_l1_size; | |
130 | new_l1_table = qemu_try_blockalign(bs->file->bs, new_l1_size2); | |
131 | if (new_l1_table == NULL) { | |
132 | return -ENOMEM; | |
133 | } | |
134 | memset(new_l1_table, 0, new_l1_size2); | |
135 | ||
136 | if (s->l1_size) { | |
137 | memcpy(new_l1_table, s->l1_table, s->l1_size * L1E_SIZE); | |
138 | } | |
139 | ||
140 | /* write new table (align to cluster) */ | |
141 | BLKDBG_EVENT(bs->file, BLKDBG_L1_GROW_ALLOC_TABLE); | |
142 | new_l1_table_offset = qcow2_alloc_clusters(bs, new_l1_size2); | |
143 | if (new_l1_table_offset < 0) { | |
144 | qemu_vfree(new_l1_table); | |
145 | return new_l1_table_offset; | |
146 | } | |
147 | ||
148 | ret = qcow2_cache_flush(bs, s->refcount_block_cache); | |
149 | if (ret < 0) { | |
150 | goto fail; | |
151 | } | |
152 | ||
153 | /* the L1 position has not yet been updated, so these clusters must | |
154 | * indeed be completely free */ | |
155 | ret = qcow2_pre_write_overlap_check(bs, 0, new_l1_table_offset, | |
156 | new_l1_size2, false); | |
157 | if (ret < 0) { | |
158 | goto fail; | |
159 | } | |
160 | ||
161 | BLKDBG_EVENT(bs->file, BLKDBG_L1_GROW_WRITE_TABLE); | |
162 | for(i = 0; i < s->l1_size; i++) | |
163 | new_l1_table[i] = cpu_to_be64(new_l1_table[i]); | |
164 | ret = bdrv_pwrite_sync(bs->file, new_l1_table_offset, new_l1_size2, | |
165 | new_l1_table, 0); | |
166 | if (ret < 0) | |
167 | goto fail; | |
168 | for(i = 0; i < s->l1_size; i++) | |
169 | new_l1_table[i] = be64_to_cpu(new_l1_table[i]); | |
170 | ||
171 | /* set new table */ | |
172 | BLKDBG_EVENT(bs->file, BLKDBG_L1_GROW_ACTIVATE_TABLE); | |
173 | stl_be_p(data, new_l1_size); | |
174 | stq_be_p(data + 4, new_l1_table_offset); | |
175 | ret = bdrv_pwrite_sync(bs->file, offsetof(QCowHeader, l1_size), | |
176 | sizeof(data), data, 0); | |
177 | if (ret < 0) { | |
178 | goto fail; | |
179 | } | |
180 | qemu_vfree(s->l1_table); | |
181 | old_l1_table_offset = s->l1_table_offset; | |
182 | s->l1_table_offset = new_l1_table_offset; | |
183 | s->l1_table = new_l1_table; | |
184 | old_l1_size = s->l1_size; | |
185 | s->l1_size = new_l1_size; | |
186 | qcow2_free_clusters(bs, old_l1_table_offset, old_l1_size * L1E_SIZE, | |
187 | QCOW2_DISCARD_OTHER); | |
188 | return 0; | |
189 | fail: | |
190 | qemu_vfree(new_l1_table); | |
191 | qcow2_free_clusters(bs, new_l1_table_offset, new_l1_size2, | |
192 | QCOW2_DISCARD_OTHER); | |
193 | return ret; | |
194 | } | |
195 | ||
196 | /* | |
197 | * l2_load | |
198 | * | |
199 | * @bs: The BlockDriverState | |
200 | * @offset: A guest offset, used to calculate what slice of the L2 | |
201 | * table to load. | |
202 | * @l2_offset: Offset to the L2 table in the image file. | |
203 | * @l2_slice: Location to store the pointer to the L2 slice. | |
204 | * | |
205 | * Loads a L2 slice into memory (L2 slices are the parts of L2 tables | |
206 | * that are loaded by the qcow2 cache). If the slice is in the cache, | |
207 | * the cache is used; otherwise the L2 slice is loaded from the image | |
208 | * file. | |
209 | */ | |
210 | static int l2_load(BlockDriverState *bs, uint64_t offset, | |
211 | uint64_t l2_offset, uint64_t **l2_slice) | |
212 | { | |
213 | BDRVQcow2State *s = bs->opaque; | |
214 | int start_of_slice = l2_entry_size(s) * | |
215 | (offset_to_l2_index(s, offset) - offset_to_l2_slice_index(s, offset)); | |
216 | ||
217 | return qcow2_cache_get(bs, s->l2_table_cache, l2_offset + start_of_slice, | |
218 | (void **)l2_slice); | |
219 | } | |
220 | ||
221 | /* | |
222 | * Writes an L1 entry to disk (note that depending on the alignment | |
223 | * requirements this function may write more that just one entry in | |
224 | * order to prevent bdrv_pwrite from performing a read-modify-write) | |
225 | */ | |
226 | int qcow2_write_l1_entry(BlockDriverState *bs, int l1_index) | |
227 | { | |
228 | BDRVQcow2State *s = bs->opaque; | |
229 | int l1_start_index; | |
230 | int i, ret; | |
231 | int bufsize = MAX(L1E_SIZE, | |
232 | MIN(bs->file->bs->bl.request_alignment, s->cluster_size)); | |
233 | int nentries = bufsize / L1E_SIZE; | |
234 | g_autofree uint64_t *buf = g_try_new0(uint64_t, nentries); | |
235 | ||
236 | if (buf == NULL) { | |
237 | return -ENOMEM; | |
238 | } | |
239 | ||
240 | l1_start_index = QEMU_ALIGN_DOWN(l1_index, nentries); | |
241 | for (i = 0; i < MIN(nentries, s->l1_size - l1_start_index); i++) { | |
242 | buf[i] = cpu_to_be64(s->l1_table[l1_start_index + i]); | |
243 | } | |
244 | ||
245 | ret = qcow2_pre_write_overlap_check(bs, QCOW2_OL_ACTIVE_L1, | |
246 | s->l1_table_offset + L1E_SIZE * l1_start_index, bufsize, false); | |
247 | if (ret < 0) { | |
248 | return ret; | |
249 | } | |
250 | ||
251 | BLKDBG_EVENT(bs->file, BLKDBG_L1_UPDATE); | |
252 | ret = bdrv_pwrite_sync(bs->file, | |
253 | s->l1_table_offset + L1E_SIZE * l1_start_index, | |
254 | bufsize, buf, 0); | |
255 | if (ret < 0) { | |
256 | return ret; | |
257 | } | |
258 | ||
259 | return 0; | |
260 | } | |
261 | ||
262 | /* | |
263 | * l2_allocate | |
264 | * | |
265 | * Allocate a new l2 entry in the file. If l1_index points to an already | |
266 | * used entry in the L2 table (i.e. we are doing a copy on write for the L2 | |
267 | * table) copy the contents of the old L2 table into the newly allocated one. | |
268 | * Otherwise the new table is initialized with zeros. | |
269 | * | |
270 | */ | |
271 | ||
272 | static int l2_allocate(BlockDriverState *bs, int l1_index) | |
273 | { | |
274 | BDRVQcow2State *s = bs->opaque; | |
275 | uint64_t old_l2_offset; | |
276 | uint64_t *l2_slice = NULL; | |
277 | unsigned slice, slice_size2, n_slices; | |
278 | int64_t l2_offset; | |
279 | int ret; | |
280 | ||
281 | old_l2_offset = s->l1_table[l1_index]; | |
282 | ||
283 | trace_qcow2_l2_allocate(bs, l1_index); | |
284 | ||
285 | /* allocate a new l2 entry */ | |
286 | ||
287 | l2_offset = qcow2_alloc_clusters(bs, s->l2_size * l2_entry_size(s)); | |
288 | if (l2_offset < 0) { | |
289 | ret = l2_offset; | |
290 | goto fail; | |
291 | } | |
292 | ||
293 | /* The offset must fit in the offset field of the L1 table entry */ | |
294 | assert((l2_offset & L1E_OFFSET_MASK) == l2_offset); | |
295 | ||
296 | /* If we're allocating the table at offset 0 then something is wrong */ | |
297 | if (l2_offset == 0) { | |
298 | qcow2_signal_corruption(bs, true, -1, -1, "Preventing invalid " | |
299 | "allocation of L2 table at offset 0"); | |
300 | ret = -EIO; | |
301 | goto fail; | |
302 | } | |
303 | ||
304 | ret = qcow2_cache_flush(bs, s->refcount_block_cache); | |
305 | if (ret < 0) { | |
306 | goto fail; | |
307 | } | |
308 | ||
309 | /* allocate a new entry in the l2 cache */ | |
310 | ||
311 | slice_size2 = s->l2_slice_size * l2_entry_size(s); | |
312 | n_slices = s->cluster_size / slice_size2; | |
313 | ||
314 | trace_qcow2_l2_allocate_get_empty(bs, l1_index); | |
315 | for (slice = 0; slice < n_slices; slice++) { | |
316 | ret = qcow2_cache_get_empty(bs, s->l2_table_cache, | |
317 | l2_offset + slice * slice_size2, | |
318 | (void **) &l2_slice); | |
319 | if (ret < 0) { | |
320 | goto fail; | |
321 | } | |
322 | ||
323 | if ((old_l2_offset & L1E_OFFSET_MASK) == 0) { | |
324 | /* if there was no old l2 table, clear the new slice */ | |
325 | memset(l2_slice, 0, slice_size2); | |
326 | } else { | |
327 | uint64_t *old_slice; | |
328 | uint64_t old_l2_slice_offset = | |
329 | (old_l2_offset & L1E_OFFSET_MASK) + slice * slice_size2; | |
330 | ||
331 | /* if there was an old l2 table, read a slice from the disk */ | |
332 | BLKDBG_EVENT(bs->file, BLKDBG_L2_ALLOC_COW_READ); | |
333 | ret = qcow2_cache_get(bs, s->l2_table_cache, old_l2_slice_offset, | |
334 | (void **) &old_slice); | |
335 | if (ret < 0) { | |
336 | goto fail; | |
337 | } | |
338 | ||
339 | memcpy(l2_slice, old_slice, slice_size2); | |
340 | ||
341 | qcow2_cache_put(s->l2_table_cache, (void **) &old_slice); | |
342 | } | |
343 | ||
344 | /* write the l2 slice to the file */ | |
345 | BLKDBG_EVENT(bs->file, BLKDBG_L2_ALLOC_WRITE); | |
346 | ||
347 | trace_qcow2_l2_allocate_write_l2(bs, l1_index); | |
348 | qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_slice); | |
349 | qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice); | |
350 | } | |
351 | ||
352 | ret = qcow2_cache_flush(bs, s->l2_table_cache); | |
353 | if (ret < 0) { | |
354 | goto fail; | |
355 | } | |
356 | ||
357 | /* update the L1 entry */ | |
358 | trace_qcow2_l2_allocate_write_l1(bs, l1_index); | |
359 | s->l1_table[l1_index] = l2_offset | QCOW_OFLAG_COPIED; | |
360 | ret = qcow2_write_l1_entry(bs, l1_index); | |
361 | if (ret < 0) { | |
362 | goto fail; | |
363 | } | |
364 | ||
365 | trace_qcow2_l2_allocate_done(bs, l1_index, 0); | |
366 | return 0; | |
367 | ||
368 | fail: | |
369 | trace_qcow2_l2_allocate_done(bs, l1_index, ret); | |
370 | if (l2_slice != NULL) { | |
371 | qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice); | |
372 | } | |
373 | s->l1_table[l1_index] = old_l2_offset; | |
374 | if (l2_offset > 0) { | |
375 | qcow2_free_clusters(bs, l2_offset, s->l2_size * l2_entry_size(s), | |
376 | QCOW2_DISCARD_ALWAYS); | |
377 | } | |
378 | return ret; | |
379 | } | |
380 | ||
381 | /* | |
382 | * For a given L2 entry, count the number of contiguous subclusters of | |
383 | * the same type starting from @sc_from. Compressed clusters are | |
384 | * treated as if they were divided into subclusters of size | |
385 | * s->subcluster_size. | |
386 | * | |
387 | * Return the number of contiguous subclusters and set @type to the | |
388 | * subcluster type. | |
389 | * | |
390 | * If the L2 entry is invalid return -errno and set @type to | |
391 | * QCOW2_SUBCLUSTER_INVALID. | |
392 | */ | |
393 | static int qcow2_get_subcluster_range_type(BlockDriverState *bs, | |
394 | uint64_t l2_entry, | |
395 | uint64_t l2_bitmap, | |
396 | unsigned sc_from, | |
397 | QCow2SubclusterType *type) | |
398 | { | |
399 | BDRVQcow2State *s = bs->opaque; | |
400 | uint32_t val; | |
401 | ||
402 | *type = qcow2_get_subcluster_type(bs, l2_entry, l2_bitmap, sc_from); | |
403 | ||
404 | if (*type == QCOW2_SUBCLUSTER_INVALID) { | |
405 | return -EINVAL; | |
406 | } else if (!has_subclusters(s) || *type == QCOW2_SUBCLUSTER_COMPRESSED) { | |
407 | return s->subclusters_per_cluster - sc_from; | |
408 | } | |
409 | ||
410 | switch (*type) { | |
411 | case QCOW2_SUBCLUSTER_NORMAL: | |
412 | val = l2_bitmap | QCOW_OFLAG_SUB_ALLOC_RANGE(0, sc_from); | |
413 | return cto32(val) - sc_from; | |
414 | ||
415 | case QCOW2_SUBCLUSTER_ZERO_PLAIN: | |
416 | case QCOW2_SUBCLUSTER_ZERO_ALLOC: | |
417 | val = (l2_bitmap | QCOW_OFLAG_SUB_ZERO_RANGE(0, sc_from)) >> 32; | |
418 | return cto32(val) - sc_from; | |
419 | ||
420 | case QCOW2_SUBCLUSTER_UNALLOCATED_PLAIN: | |
421 | case QCOW2_SUBCLUSTER_UNALLOCATED_ALLOC: | |
422 | val = ((l2_bitmap >> 32) | l2_bitmap) | |
423 | & ~QCOW_OFLAG_SUB_ALLOC_RANGE(0, sc_from); | |
424 | return ctz32(val) - sc_from; | |
425 | ||
426 | default: | |
427 | g_assert_not_reached(); | |
428 | } | |
429 | } | |
430 | ||
431 | /* | |
432 | * Return the number of contiguous subclusters of the exact same type | |
433 | * in a given L2 slice, starting from cluster @l2_index, subcluster | |
434 | * @sc_index. Allocated subclusters are required to be contiguous in | |
435 | * the image file. | |
436 | * At most @nb_clusters are checked (note that this means clusters, | |
437 | * not subclusters). | |
438 | * Compressed clusters are always processed one by one but for the | |
439 | * purpose of this count they are treated as if they were divided into | |
440 | * subclusters of size s->subcluster_size. | |
441 | * On failure return -errno and update @l2_index to point to the | |
442 | * invalid entry. | |
443 | */ | |
444 | static int count_contiguous_subclusters(BlockDriverState *bs, int nb_clusters, | |
445 | unsigned sc_index, uint64_t *l2_slice, | |
446 | unsigned *l2_index) | |
447 | { | |
448 | BDRVQcow2State *s = bs->opaque; | |
449 | int i, count = 0; | |
450 | bool check_offset = false; | |
451 | uint64_t expected_offset = 0; | |
452 | QCow2SubclusterType expected_type = QCOW2_SUBCLUSTER_NORMAL, type; | |
453 | ||
454 | assert(*l2_index + nb_clusters <= s->l2_slice_size); | |
455 | ||
456 | for (i = 0; i < nb_clusters; i++) { | |
457 | unsigned first_sc = (i == 0) ? sc_index : 0; | |
458 | uint64_t l2_entry = get_l2_entry(s, l2_slice, *l2_index + i); | |
459 | uint64_t l2_bitmap = get_l2_bitmap(s, l2_slice, *l2_index + i); | |
460 | int ret = qcow2_get_subcluster_range_type(bs, l2_entry, l2_bitmap, | |
461 | first_sc, &type); | |
462 | if (ret < 0) { | |
463 | *l2_index += i; /* Point to the invalid entry */ | |
464 | return -EIO; | |
465 | } | |
466 | if (i == 0) { | |
467 | if (type == QCOW2_SUBCLUSTER_COMPRESSED) { | |
468 | /* Compressed clusters are always processed one by one */ | |
469 | return ret; | |
470 | } | |
471 | expected_type = type; | |
472 | expected_offset = l2_entry & L2E_OFFSET_MASK; | |
473 | check_offset = (type == QCOW2_SUBCLUSTER_NORMAL || | |
474 | type == QCOW2_SUBCLUSTER_ZERO_ALLOC || | |
475 | type == QCOW2_SUBCLUSTER_UNALLOCATED_ALLOC); | |
476 | } else if (type != expected_type) { | |
477 | break; | |
478 | } else if (check_offset) { | |
479 | expected_offset += s->cluster_size; | |
480 | if (expected_offset != (l2_entry & L2E_OFFSET_MASK)) { | |
481 | break; | |
482 | } | |
483 | } | |
484 | count += ret; | |
485 | /* Stop if there are type changes before the end of the cluster */ | |
486 | if (first_sc + ret < s->subclusters_per_cluster) { | |
487 | break; | |
488 | } | |
489 | } | |
490 | ||
491 | return count; | |
492 | } | |
493 | ||
494 | static int coroutine_fn GRAPH_RDLOCK | |
495 | do_perform_cow_read(BlockDriverState *bs, uint64_t src_cluster_offset, | |
496 | unsigned offset_in_cluster, QEMUIOVector *qiov) | |
497 | { | |
498 | int ret; | |
499 | ||
500 | if (qiov->size == 0) { | |
501 | return 0; | |
502 | } | |
503 | ||
504 | BLKDBG_CO_EVENT(bs->file, BLKDBG_COW_READ); | |
505 | ||
506 | if (!bs->drv) { | |
507 | return -ENOMEDIUM; | |
508 | } | |
509 | ||
510 | /* | |
511 | * We never deal with requests that don't satisfy | |
512 | * bdrv_check_qiov_request(), and aligning requests to clusters never | |
513 | * breaks this condition. So, do some assertions before calling | |
514 | * bs->drv->bdrv_co_preadv_part() which has int64_t arguments. | |
515 | */ | |
516 | assert(src_cluster_offset <= INT64_MAX); | |
517 | assert(src_cluster_offset + offset_in_cluster <= INT64_MAX); | |
518 | /* Cast qiov->size to uint64_t to silence a compiler warning on -m32 */ | |
519 | assert((uint64_t)qiov->size <= INT64_MAX); | |
520 | bdrv_check_qiov_request(src_cluster_offset + offset_in_cluster, qiov->size, | |
521 | qiov, 0, &error_abort); | |
522 | /* | |
523 | * Call .bdrv_co_readv() directly instead of using the public block-layer | |
524 | * interface. This avoids double I/O throttling and request tracking, | |
525 | * which can lead to deadlock when block layer copy-on-read is enabled. | |
526 | */ | |
527 | ret = bs->drv->bdrv_co_preadv_part(bs, | |
528 | src_cluster_offset + offset_in_cluster, | |
529 | qiov->size, qiov, 0, 0); | |
530 | if (ret < 0) { | |
531 | return ret; | |
532 | } | |
533 | ||
534 | return 0; | |
535 | } | |
536 | ||
537 | static int coroutine_fn GRAPH_RDLOCK | |
538 | do_perform_cow_write(BlockDriverState *bs, uint64_t cluster_offset, | |
539 | unsigned offset_in_cluster, QEMUIOVector *qiov) | |
540 | { | |
541 | BDRVQcow2State *s = bs->opaque; | |
542 | int ret; | |
543 | ||
544 | if (qiov->size == 0) { | |
545 | return 0; | |
546 | } | |
547 | ||
548 | ret = qcow2_pre_write_overlap_check(bs, 0, | |
549 | cluster_offset + offset_in_cluster, qiov->size, true); | |
550 | if (ret < 0) { | |
551 | return ret; | |
552 | } | |
553 | ||
554 | BLKDBG_CO_EVENT(bs->file, BLKDBG_COW_WRITE); | |
555 | ret = bdrv_co_pwritev(s->data_file, cluster_offset + offset_in_cluster, | |
556 | qiov->size, qiov, 0); | |
557 | if (ret < 0) { | |
558 | return ret; | |
559 | } | |
560 | ||
561 | return 0; | |
562 | } | |
563 | ||
564 | ||
565 | /* | |
566 | * get_host_offset | |
567 | * | |
568 | * For a given offset of the virtual disk find the equivalent host | |
569 | * offset in the qcow2 file and store it in *host_offset. Neither | |
570 | * offset needs to be aligned to a cluster boundary. | |
571 | * | |
572 | * If the cluster is unallocated then *host_offset will be 0. | |
573 | * If the cluster is compressed then *host_offset will contain the l2 entry. | |
574 | * | |
575 | * On entry, *bytes is the maximum number of contiguous bytes starting at | |
576 | * offset that we are interested in. | |
577 | * | |
578 | * On exit, *bytes is the number of bytes starting at offset that have the same | |
579 | * subcluster type and (if applicable) are stored contiguously in the image | |
580 | * file. The subcluster type is stored in *subcluster_type. | |
581 | * Compressed clusters are always processed one by one. | |
582 | * | |
583 | * Returns 0 on success, -errno in error cases. | |
584 | */ | |
585 | int qcow2_get_host_offset(BlockDriverState *bs, uint64_t offset, | |
586 | unsigned int *bytes, uint64_t *host_offset, | |
587 | QCow2SubclusterType *subcluster_type) | |
588 | { | |
589 | BDRVQcow2State *s = bs->opaque; | |
590 | unsigned int l2_index, sc_index; | |
591 | uint64_t l1_index, l2_offset, *l2_slice, l2_entry, l2_bitmap; | |
592 | int sc; | |
593 | unsigned int offset_in_cluster; | |
594 | uint64_t bytes_available, bytes_needed, nb_clusters; | |
595 | QCow2SubclusterType type; | |
596 | int ret; | |
597 | ||
598 | offset_in_cluster = offset_into_cluster(s, offset); | |
599 | bytes_needed = (uint64_t) *bytes + offset_in_cluster; | |
600 | ||
601 | /* compute how many bytes there are between the start of the cluster | |
602 | * containing offset and the end of the l2 slice that contains | |
603 | * the entry pointing to it */ | |
604 | bytes_available = | |
605 | ((uint64_t) (s->l2_slice_size - offset_to_l2_slice_index(s, offset))) | |
606 | << s->cluster_bits; | |
607 | ||
608 | if (bytes_needed > bytes_available) { | |
609 | bytes_needed = bytes_available; | |
610 | } | |
611 | ||
612 | *host_offset = 0; | |
613 | ||
614 | /* seek to the l2 offset in the l1 table */ | |
615 | ||
616 | l1_index = offset_to_l1_index(s, offset); | |
617 | if (l1_index >= s->l1_size) { | |
618 | type = QCOW2_SUBCLUSTER_UNALLOCATED_PLAIN; | |
619 | goto out; | |
620 | } | |
621 | ||
622 | l2_offset = s->l1_table[l1_index] & L1E_OFFSET_MASK; | |
623 | if (!l2_offset) { | |
624 | type = QCOW2_SUBCLUSTER_UNALLOCATED_PLAIN; | |
625 | goto out; | |
626 | } | |
627 | ||
628 | if (offset_into_cluster(s, l2_offset)) { | |
629 | qcow2_signal_corruption(bs, true, -1, -1, "L2 table offset %#" PRIx64 | |
630 | " unaligned (L1 index: %#" PRIx64 ")", | |
631 | l2_offset, l1_index); | |
632 | return -EIO; | |
633 | } | |
634 | ||
635 | /* load the l2 slice in memory */ | |
636 | ||
637 | ret = l2_load(bs, offset, l2_offset, &l2_slice); | |
638 | if (ret < 0) { | |
639 | return ret; | |
640 | } | |
641 | ||
642 | /* find the cluster offset for the given disk offset */ | |
643 | ||
644 | l2_index = offset_to_l2_slice_index(s, offset); | |
645 | sc_index = offset_to_sc_index(s, offset); | |
646 | l2_entry = get_l2_entry(s, l2_slice, l2_index); | |
647 | l2_bitmap = get_l2_bitmap(s, l2_slice, l2_index); | |
648 | ||
649 | nb_clusters = size_to_clusters(s, bytes_needed); | |
650 | /* bytes_needed <= *bytes + offset_in_cluster, both of which are unsigned | |
651 | * integers; the minimum cluster size is 512, so this assertion is always | |
652 | * true */ | |
653 | assert(nb_clusters <= INT_MAX); | |
654 | ||
655 | type = qcow2_get_subcluster_type(bs, l2_entry, l2_bitmap, sc_index); | |
656 | if (s->qcow_version < 3 && (type == QCOW2_SUBCLUSTER_ZERO_PLAIN || | |
657 | type == QCOW2_SUBCLUSTER_ZERO_ALLOC)) { | |
658 | qcow2_signal_corruption(bs, true, -1, -1, "Zero cluster entry found" | |
659 | " in pre-v3 image (L2 offset: %#" PRIx64 | |
660 | ", L2 index: %#x)", l2_offset, l2_index); | |
661 | ret = -EIO; | |
662 | goto fail; | |
663 | } | |
664 | switch (type) { | |
665 | case QCOW2_SUBCLUSTER_INVALID: | |
666 | break; /* This is handled by count_contiguous_subclusters() below */ | |
667 | case QCOW2_SUBCLUSTER_COMPRESSED: | |
668 | if (has_data_file(bs)) { | |
669 | qcow2_signal_corruption(bs, true, -1, -1, "Compressed cluster " | |
670 | "entry found in image with external data " | |
671 | "file (L2 offset: %#" PRIx64 ", L2 index: " | |
672 | "%#x)", l2_offset, l2_index); | |
673 | ret = -EIO; | |
674 | goto fail; | |
675 | } | |
676 | *host_offset = l2_entry; | |
677 | break; | |
678 | case QCOW2_SUBCLUSTER_ZERO_PLAIN: | |
679 | case QCOW2_SUBCLUSTER_UNALLOCATED_PLAIN: | |
680 | break; | |
681 | case QCOW2_SUBCLUSTER_ZERO_ALLOC: | |
682 | case QCOW2_SUBCLUSTER_NORMAL: | |
683 | case QCOW2_SUBCLUSTER_UNALLOCATED_ALLOC: { | |
684 | uint64_t host_cluster_offset = l2_entry & L2E_OFFSET_MASK; | |
685 | *host_offset = host_cluster_offset + offset_in_cluster; | |
686 | if (offset_into_cluster(s, host_cluster_offset)) { | |
687 | qcow2_signal_corruption(bs, true, -1, -1, | |
688 | "Cluster allocation offset %#" | |
689 | PRIx64 " unaligned (L2 offset: %#" PRIx64 | |
690 | ", L2 index: %#x)", host_cluster_offset, | |
691 | l2_offset, l2_index); | |
692 | ret = -EIO; | |
693 | goto fail; | |
694 | } | |
695 | if (has_data_file(bs) && *host_offset != offset) { | |
696 | qcow2_signal_corruption(bs, true, -1, -1, | |
697 | "External data file host cluster offset %#" | |
698 | PRIx64 " does not match guest cluster " | |
699 | "offset: %#" PRIx64 | |
700 | ", L2 index: %#x)", host_cluster_offset, | |
701 | offset - offset_in_cluster, l2_index); | |
702 | ret = -EIO; | |
703 | goto fail; | |
704 | } | |
705 | break; | |
706 | } | |
707 | default: | |
708 | abort(); | |
709 | } | |
710 | ||
711 | sc = count_contiguous_subclusters(bs, nb_clusters, sc_index, | |
712 | l2_slice, &l2_index); | |
713 | if (sc < 0) { | |
714 | qcow2_signal_corruption(bs, true, -1, -1, "Invalid cluster entry found " | |
715 | " (L2 offset: %#" PRIx64 ", L2 index: %#x)", | |
716 | l2_offset, l2_index); | |
717 | ret = -EIO; | |
718 | goto fail; | |
719 | } | |
720 | qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice); | |
721 | ||
722 | bytes_available = ((int64_t)sc + sc_index) << s->subcluster_bits; | |
723 | ||
724 | out: | |
725 | if (bytes_available > bytes_needed) { | |
726 | bytes_available = bytes_needed; | |
727 | } | |
728 | ||
729 | /* bytes_available <= bytes_needed <= *bytes + offset_in_cluster; | |
730 | * subtracting offset_in_cluster will therefore definitely yield something | |
731 | * not exceeding UINT_MAX */ | |
732 | assert(bytes_available - offset_in_cluster <= UINT_MAX); | |
733 | *bytes = bytes_available - offset_in_cluster; | |
734 | ||
735 | *subcluster_type = type; | |
736 | ||
737 | return 0; | |
738 | ||
739 | fail: | |
740 | qcow2_cache_put(s->l2_table_cache, (void **)&l2_slice); | |
741 | return ret; | |
742 | } | |
743 | ||
744 | /* | |
745 | * get_cluster_table | |
746 | * | |
747 | * for a given disk offset, load (and allocate if needed) | |
748 | * the appropriate slice of its l2 table. | |
749 | * | |
750 | * the cluster index in the l2 slice is given to the caller. | |
751 | * | |
752 | * Returns 0 on success, -errno in failure case | |
753 | */ | |
754 | static int get_cluster_table(BlockDriverState *bs, uint64_t offset, | |
755 | uint64_t **new_l2_slice, | |
756 | int *new_l2_index) | |
757 | { | |
758 | BDRVQcow2State *s = bs->opaque; | |
759 | unsigned int l2_index; | |
760 | uint64_t l1_index, l2_offset; | |
761 | uint64_t *l2_slice = NULL; | |
762 | int ret; | |
763 | ||
764 | /* seek to the l2 offset in the l1 table */ | |
765 | ||
766 | l1_index = offset_to_l1_index(s, offset); | |
767 | if (l1_index >= s->l1_size) { | |
768 | ret = qcow2_grow_l1_table(bs, l1_index + 1, false); | |
769 | if (ret < 0) { | |
770 | return ret; | |
771 | } | |
772 | } | |
773 | ||
774 | assert(l1_index < s->l1_size); | |
775 | l2_offset = s->l1_table[l1_index] & L1E_OFFSET_MASK; | |
776 | if (offset_into_cluster(s, l2_offset)) { | |
777 | qcow2_signal_corruption(bs, true, -1, -1, "L2 table offset %#" PRIx64 | |
778 | " unaligned (L1 index: %#" PRIx64 ")", | |
779 | l2_offset, l1_index); | |
780 | return -EIO; | |
781 | } | |
782 | ||
783 | if (!(s->l1_table[l1_index] & QCOW_OFLAG_COPIED)) { | |
784 | /* First allocate a new L2 table (and do COW if needed) */ | |
785 | ret = l2_allocate(bs, l1_index); | |
786 | if (ret < 0) { | |
787 | return ret; | |
788 | } | |
789 | ||
790 | /* Then decrease the refcount of the old table */ | |
791 | if (l2_offset) { | |
792 | qcow2_free_clusters(bs, l2_offset, s->l2_size * l2_entry_size(s), | |
793 | QCOW2_DISCARD_OTHER); | |
794 | } | |
795 | ||
796 | /* Get the offset of the newly-allocated l2 table */ | |
797 | l2_offset = s->l1_table[l1_index] & L1E_OFFSET_MASK; | |
798 | assert(offset_into_cluster(s, l2_offset) == 0); | |
799 | } | |
800 | ||
801 | /* load the l2 slice in memory */ | |
802 | ret = l2_load(bs, offset, l2_offset, &l2_slice); | |
803 | if (ret < 0) { | |
804 | return ret; | |
805 | } | |
806 | ||
807 | /* find the cluster offset for the given disk offset */ | |
808 | ||
809 | l2_index = offset_to_l2_slice_index(s, offset); | |
810 | ||
811 | *new_l2_slice = l2_slice; | |
812 | *new_l2_index = l2_index; | |
813 | ||
814 | return 0; | |
815 | } | |
816 | ||
817 | /* | |
818 | * alloc_compressed_cluster_offset | |
819 | * | |
820 | * For a given offset on the virtual disk, allocate a new compressed cluster | |
821 | * and put the host offset of the cluster into *host_offset. If a cluster is | |
822 | * already allocated at the offset, return an error. | |
823 | * | |
824 | * Return 0 on success and -errno in error cases | |
825 | */ | |
826 | int coroutine_fn GRAPH_RDLOCK | |
827 | qcow2_alloc_compressed_cluster_offset(BlockDriverState *bs, uint64_t offset, | |
828 | int compressed_size, uint64_t *host_offset) | |
829 | { | |
830 | BDRVQcow2State *s = bs->opaque; | |
831 | int l2_index, ret; | |
832 | uint64_t *l2_slice; | |
833 | int64_t cluster_offset; | |
834 | int nb_csectors; | |
835 | ||
836 | if (has_data_file(bs)) { | |
837 | return 0; | |
838 | } | |
839 | ||
840 | ret = get_cluster_table(bs, offset, &l2_slice, &l2_index); | |
841 | if (ret < 0) { | |
842 | return ret; | |
843 | } | |
844 | ||
845 | /* Compression can't overwrite anything. Fail if the cluster was already | |
846 | * allocated. */ | |
847 | cluster_offset = get_l2_entry(s, l2_slice, l2_index); | |
848 | if (cluster_offset & L2E_OFFSET_MASK) { | |
849 | qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice); | |
850 | return -EIO; | |
851 | } | |
852 | ||
853 | cluster_offset = qcow2_alloc_bytes(bs, compressed_size); | |
854 | if (cluster_offset < 0) { | |
855 | qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice); | |
856 | return cluster_offset; | |
857 | } | |
858 | ||
859 | nb_csectors = | |
860 | (cluster_offset + compressed_size - 1) / QCOW2_COMPRESSED_SECTOR_SIZE - | |
861 | (cluster_offset / QCOW2_COMPRESSED_SECTOR_SIZE); | |
862 | ||
863 | /* The offset and size must fit in their fields of the L2 table entry */ | |
864 | assert((cluster_offset & s->cluster_offset_mask) == cluster_offset); | |
865 | assert((nb_csectors & s->csize_mask) == nb_csectors); | |
866 | ||
867 | cluster_offset |= QCOW_OFLAG_COMPRESSED | | |
868 | ((uint64_t)nb_csectors << s->csize_shift); | |
869 | ||
870 | /* update L2 table */ | |
871 | ||
872 | /* compressed clusters never have the copied flag */ | |
873 | ||
874 | BLKDBG_CO_EVENT(bs->file, BLKDBG_L2_UPDATE_COMPRESSED); | |
875 | qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_slice); | |
876 | set_l2_entry(s, l2_slice, l2_index, cluster_offset); | |
877 | if (has_subclusters(s)) { | |
878 | set_l2_bitmap(s, l2_slice, l2_index, 0); | |
879 | } | |
880 | qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice); | |
881 | ||
882 | *host_offset = cluster_offset & s->cluster_offset_mask; | |
883 | return 0; | |
884 | } | |
885 | ||
886 | static int coroutine_fn GRAPH_RDLOCK | |
887 | perform_cow(BlockDriverState *bs, QCowL2Meta *m) | |
888 | { | |
889 | BDRVQcow2State *s = bs->opaque; | |
890 | Qcow2COWRegion *start = &m->cow_start; | |
891 | Qcow2COWRegion *end = &m->cow_end; | |
892 | unsigned buffer_size; | |
893 | unsigned data_bytes = end->offset - (start->offset + start->nb_bytes); | |
894 | bool merge_reads; | |
895 | uint8_t *start_buffer, *end_buffer; | |
896 | QEMUIOVector qiov; | |
897 | int ret; | |
898 | ||
899 | assert(start->nb_bytes <= UINT_MAX - end->nb_bytes); | |
900 | assert(start->nb_bytes + end->nb_bytes <= UINT_MAX - data_bytes); | |
901 | assert(start->offset + start->nb_bytes <= end->offset); | |
902 | ||
903 | if ((start->nb_bytes == 0 && end->nb_bytes == 0) || m->skip_cow) { | |
904 | return 0; | |
905 | } | |
906 | ||
907 | /* If we have to read both the start and end COW regions and the | |
908 | * middle region is not too large then perform just one read | |
909 | * operation */ | |
910 | merge_reads = start->nb_bytes && end->nb_bytes && data_bytes <= 16384; | |
911 | if (merge_reads) { | |
912 | buffer_size = start->nb_bytes + data_bytes + end->nb_bytes; | |
913 | } else { | |
914 | /* If we have to do two reads, add some padding in the middle | |
915 | * if necessary to make sure that the end region is optimally | |
916 | * aligned. */ | |
917 | size_t align = bdrv_opt_mem_align(bs); | |
918 | assert(align > 0 && align <= UINT_MAX); | |
919 | assert(QEMU_ALIGN_UP(start->nb_bytes, align) <= | |
920 | UINT_MAX - end->nb_bytes); | |
921 | buffer_size = QEMU_ALIGN_UP(start->nb_bytes, align) + end->nb_bytes; | |
922 | } | |
923 | ||
924 | /* Reserve a buffer large enough to store all the data that we're | |
925 | * going to read */ | |
926 | start_buffer = qemu_try_blockalign(bs, buffer_size); | |
927 | if (start_buffer == NULL) { | |
928 | return -ENOMEM; | |
929 | } | |
930 | /* The part of the buffer where the end region is located */ | |
931 | end_buffer = start_buffer + buffer_size - end->nb_bytes; | |
932 | ||
933 | qemu_iovec_init(&qiov, 2 + (m->data_qiov ? | |
934 | qemu_iovec_subvec_niov(m->data_qiov, | |
935 | m->data_qiov_offset, | |
936 | data_bytes) | |
937 | : 0)); | |
938 | ||
939 | qemu_co_mutex_unlock(&s->lock); | |
940 | /* First we read the existing data from both COW regions. We | |
941 | * either read the whole region in one go, or the start and end | |
942 | * regions separately. */ | |
943 | if (merge_reads) { | |
944 | qemu_iovec_add(&qiov, start_buffer, buffer_size); | |
945 | ret = do_perform_cow_read(bs, m->offset, start->offset, &qiov); | |
946 | } else { | |
947 | qemu_iovec_add(&qiov, start_buffer, start->nb_bytes); | |
948 | ret = do_perform_cow_read(bs, m->offset, start->offset, &qiov); | |
949 | if (ret < 0) { | |
950 | goto fail; | |
951 | } | |
952 | ||
953 | qemu_iovec_reset(&qiov); | |
954 | qemu_iovec_add(&qiov, end_buffer, end->nb_bytes); | |
955 | ret = do_perform_cow_read(bs, m->offset, end->offset, &qiov); | |
956 | } | |
957 | if (ret < 0) { | |
958 | goto fail; | |
959 | } | |
960 | ||
961 | /* Encrypt the data if necessary before writing it */ | |
962 | if (bs->encrypted) { | |
963 | ret = qcow2_co_encrypt(bs, | |
964 | m->alloc_offset + start->offset, | |
965 | m->offset + start->offset, | |
966 | start_buffer, start->nb_bytes); | |
967 | if (ret < 0) { | |
968 | goto fail; | |
969 | } | |
970 | ||
971 | ret = qcow2_co_encrypt(bs, | |
972 | m->alloc_offset + end->offset, | |
973 | m->offset + end->offset, | |
974 | end_buffer, end->nb_bytes); | |
975 | if (ret < 0) { | |
976 | goto fail; | |
977 | } | |
978 | } | |
979 | ||
980 | /* And now we can write everything. If we have the guest data we | |
981 | * can write everything in one single operation */ | |
982 | if (m->data_qiov) { | |
983 | qemu_iovec_reset(&qiov); | |
984 | if (start->nb_bytes) { | |
985 | qemu_iovec_add(&qiov, start_buffer, start->nb_bytes); | |
986 | } | |
987 | qemu_iovec_concat(&qiov, m->data_qiov, m->data_qiov_offset, data_bytes); | |
988 | if (end->nb_bytes) { | |
989 | qemu_iovec_add(&qiov, end_buffer, end->nb_bytes); | |
990 | } | |
991 | /* NOTE: we have a write_aio blkdebug event here followed by | |
992 | * a cow_write one in do_perform_cow_write(), but there's only | |
993 | * one single I/O operation */ | |
994 | BLKDBG_CO_EVENT(bs->file, BLKDBG_WRITE_AIO); | |
995 | ret = do_perform_cow_write(bs, m->alloc_offset, start->offset, &qiov); | |
996 | } else { | |
997 | /* If there's no guest data then write both COW regions separately */ | |
998 | qemu_iovec_reset(&qiov); | |
999 | qemu_iovec_add(&qiov, start_buffer, start->nb_bytes); | |
1000 | ret = do_perform_cow_write(bs, m->alloc_offset, start->offset, &qiov); | |
1001 | if (ret < 0) { | |
1002 | goto fail; | |
1003 | } | |
1004 | ||
1005 | qemu_iovec_reset(&qiov); | |
1006 | qemu_iovec_add(&qiov, end_buffer, end->nb_bytes); | |
1007 | ret = do_perform_cow_write(bs, m->alloc_offset, end->offset, &qiov); | |
1008 | } | |
1009 | ||
1010 | fail: | |
1011 | qemu_co_mutex_lock(&s->lock); | |
1012 | ||
1013 | /* | |
1014 | * Before we update the L2 table to actually point to the new cluster, we | |
1015 | * need to be sure that the refcounts have been increased and COW was | |
1016 | * handled. | |
1017 | */ | |
1018 | if (ret == 0) { | |
1019 | qcow2_cache_depends_on_flush(s->l2_table_cache); | |
1020 | } | |
1021 | ||
1022 | qemu_vfree(start_buffer); | |
1023 | qemu_iovec_destroy(&qiov); | |
1024 | return ret; | |
1025 | } | |
1026 | ||
1027 | int coroutine_fn qcow2_alloc_cluster_link_l2(BlockDriverState *bs, | |
1028 | QCowL2Meta *m) | |
1029 | { | |
1030 | BDRVQcow2State *s = bs->opaque; | |
1031 | int i, j = 0, l2_index, ret; | |
1032 | uint64_t *old_cluster, *l2_slice; | |
1033 | uint64_t cluster_offset = m->alloc_offset; | |
1034 | ||
1035 | trace_qcow2_cluster_link_l2(qemu_coroutine_self(), m->nb_clusters); | |
1036 | assert(m->nb_clusters > 0); | |
1037 | ||
1038 | old_cluster = g_try_new(uint64_t, m->nb_clusters); | |
1039 | if (old_cluster == NULL) { | |
1040 | ret = -ENOMEM; | |
1041 | goto err; | |
1042 | } | |
1043 | ||
1044 | /* copy content of unmodified sectors */ | |
1045 | ret = perform_cow(bs, m); | |
1046 | if (ret < 0) { | |
1047 | goto err; | |
1048 | } | |
1049 | ||
1050 | /* Update L2 table. */ | |
1051 | if (s->use_lazy_refcounts) { | |
1052 | qcow2_mark_dirty(bs); | |
1053 | } | |
1054 | if (qcow2_need_accurate_refcounts(s)) { | |
1055 | qcow2_cache_set_dependency(bs, s->l2_table_cache, | |
1056 | s->refcount_block_cache); | |
1057 | } | |
1058 | ||
1059 | ret = get_cluster_table(bs, m->offset, &l2_slice, &l2_index); | |
1060 | if (ret < 0) { | |
1061 | goto err; | |
1062 | } | |
1063 | qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_slice); | |
1064 | ||
1065 | assert(l2_index + m->nb_clusters <= s->l2_slice_size); | |
1066 | assert(m->cow_end.offset + m->cow_end.nb_bytes <= | |
1067 | m->nb_clusters << s->cluster_bits); | |
1068 | for (i = 0; i < m->nb_clusters; i++) { | |
1069 | uint64_t offset = cluster_offset + ((uint64_t)i << s->cluster_bits); | |
1070 | /* if two concurrent writes happen to the same unallocated cluster | |
1071 | * each write allocates separate cluster and writes data concurrently. | |
1072 | * The first one to complete updates l2 table with pointer to its | |
1073 | * cluster the second one has to do RMW (which is done above by | |
1074 | * perform_cow()), update l2 table with its cluster pointer and free | |
1075 | * old cluster. This is what this loop does */ | |
1076 | if (get_l2_entry(s, l2_slice, l2_index + i) != 0) { | |
1077 | old_cluster[j++] = get_l2_entry(s, l2_slice, l2_index + i); | |
1078 | } | |
1079 | ||
1080 | /* The offset must fit in the offset field of the L2 table entry */ | |
1081 | assert((offset & L2E_OFFSET_MASK) == offset); | |
1082 | ||
1083 | set_l2_entry(s, l2_slice, l2_index + i, offset | QCOW_OFLAG_COPIED); | |
1084 | ||
1085 | /* Update bitmap with the subclusters that were just written */ | |
1086 | if (has_subclusters(s) && !m->prealloc) { | |
1087 | uint64_t l2_bitmap = get_l2_bitmap(s, l2_slice, l2_index + i); | |
1088 | unsigned written_from = m->cow_start.offset; | |
1089 | unsigned written_to = m->cow_end.offset + m->cow_end.nb_bytes; | |
1090 | int first_sc, last_sc; | |
1091 | /* Narrow written_from and written_to down to the current cluster */ | |
1092 | written_from = MAX(written_from, i << s->cluster_bits); | |
1093 | written_to = MIN(written_to, (i + 1) << s->cluster_bits); | |
1094 | assert(written_from < written_to); | |
1095 | first_sc = offset_to_sc_index(s, written_from); | |
1096 | last_sc = offset_to_sc_index(s, written_to - 1); | |
1097 | l2_bitmap |= QCOW_OFLAG_SUB_ALLOC_RANGE(first_sc, last_sc + 1); | |
1098 | l2_bitmap &= ~QCOW_OFLAG_SUB_ZERO_RANGE(first_sc, last_sc + 1); | |
1099 | set_l2_bitmap(s, l2_slice, l2_index + i, l2_bitmap); | |
1100 | } | |
1101 | } | |
1102 | ||
1103 | ||
1104 | qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice); | |
1105 | ||
1106 | /* | |
1107 | * If this was a COW, we need to decrease the refcount of the old cluster. | |
1108 | * | |
1109 | * Don't discard clusters that reach a refcount of 0 (e.g. compressed | |
1110 | * clusters), the next write will reuse them anyway. | |
1111 | */ | |
1112 | if (!m->keep_old_clusters && j != 0) { | |
1113 | for (i = 0; i < j; i++) { | |
1114 | qcow2_free_any_cluster(bs, old_cluster[i], QCOW2_DISCARD_NEVER); | |
1115 | } | |
1116 | } | |
1117 | ||
1118 | ret = 0; | |
1119 | err: | |
1120 | g_free(old_cluster); | |
1121 | return ret; | |
1122 | } | |
1123 | ||
1124 | /** | |
1125 | * Frees the allocated clusters because the request failed and they won't | |
1126 | * actually be linked. | |
1127 | */ | |
1128 | void coroutine_fn qcow2_alloc_cluster_abort(BlockDriverState *bs, QCowL2Meta *m) | |
1129 | { | |
1130 | BDRVQcow2State *s = bs->opaque; | |
1131 | if (!has_data_file(bs) && !m->keep_old_clusters) { | |
1132 | qcow2_free_clusters(bs, m->alloc_offset, | |
1133 | m->nb_clusters << s->cluster_bits, | |
1134 | QCOW2_DISCARD_NEVER); | |
1135 | } | |
1136 | } | |
1137 | ||
1138 | /* | |
1139 | * For a given write request, create a new QCowL2Meta structure, add | |
1140 | * it to @m and the BDRVQcow2State.cluster_allocs list. If the write | |
1141 | * request does not need copy-on-write or changes to the L2 metadata | |
1142 | * then this function does nothing. | |
1143 | * | |
1144 | * @host_cluster_offset points to the beginning of the first cluster. | |
1145 | * | |
1146 | * @guest_offset and @bytes indicate the offset and length of the | |
1147 | * request. | |
1148 | * | |
1149 | * @l2_slice contains the L2 entries of all clusters involved in this | |
1150 | * write request. | |
1151 | * | |
1152 | * If @keep_old is true it means that the clusters were already | |
1153 | * allocated and will be overwritten. If false then the clusters are | |
1154 | * new and we have to decrease the reference count of the old ones. | |
1155 | * | |
1156 | * Returns 0 on success, -errno on failure. | |
1157 | */ | |
1158 | static int coroutine_fn calculate_l2_meta(BlockDriverState *bs, | |
1159 | uint64_t host_cluster_offset, | |
1160 | uint64_t guest_offset, unsigned bytes, | |
1161 | uint64_t *l2_slice, QCowL2Meta **m, | |
1162 | bool keep_old) | |
1163 | { | |
1164 | BDRVQcow2State *s = bs->opaque; | |
1165 | int sc_index, l2_index = offset_to_l2_slice_index(s, guest_offset); | |
1166 | uint64_t l2_entry, l2_bitmap; | |
1167 | unsigned cow_start_from, cow_end_to; | |
1168 | unsigned cow_start_to = offset_into_cluster(s, guest_offset); | |
1169 | unsigned cow_end_from = cow_start_to + bytes; | |
1170 | unsigned nb_clusters = size_to_clusters(s, cow_end_from); | |
1171 | QCowL2Meta *old_m = *m; | |
1172 | QCow2SubclusterType type; | |
1173 | int i; | |
1174 | bool skip_cow = keep_old; | |
1175 | ||
1176 | assert(nb_clusters <= s->l2_slice_size - l2_index); | |
1177 | ||
1178 | /* Check the type of all affected subclusters */ | |
1179 | for (i = 0; i < nb_clusters; i++) { | |
1180 | l2_entry = get_l2_entry(s, l2_slice, l2_index + i); | |
1181 | l2_bitmap = get_l2_bitmap(s, l2_slice, l2_index + i); | |
1182 | if (skip_cow) { | |
1183 | unsigned write_from = MAX(cow_start_to, i << s->cluster_bits); | |
1184 | unsigned write_to = MIN(cow_end_from, (i + 1) << s->cluster_bits); | |
1185 | int first_sc = offset_to_sc_index(s, write_from); | |
1186 | int last_sc = offset_to_sc_index(s, write_to - 1); | |
1187 | int cnt = qcow2_get_subcluster_range_type(bs, l2_entry, l2_bitmap, | |
1188 | first_sc, &type); | |
1189 | /* Is any of the subclusters of type != QCOW2_SUBCLUSTER_NORMAL ? */ | |
1190 | if (type != QCOW2_SUBCLUSTER_NORMAL || first_sc + cnt <= last_sc) { | |
1191 | skip_cow = false; | |
1192 | } | |
1193 | } else { | |
1194 | /* If we can't skip the cow we can still look for invalid entries */ | |
1195 | type = qcow2_get_subcluster_type(bs, l2_entry, l2_bitmap, 0); | |
1196 | } | |
1197 | if (type == QCOW2_SUBCLUSTER_INVALID) { | |
1198 | int l1_index = offset_to_l1_index(s, guest_offset); | |
1199 | uint64_t l2_offset = s->l1_table[l1_index] & L1E_OFFSET_MASK; | |
1200 | qcow2_signal_corruption(bs, true, -1, -1, "Invalid cluster " | |
1201 | "entry found (L2 offset: %#" PRIx64 | |
1202 | ", L2 index: %#x)", | |
1203 | l2_offset, l2_index + i); | |
1204 | return -EIO; | |
1205 | } | |
1206 | } | |
1207 | ||
1208 | if (skip_cow) { | |
1209 | return 0; | |
1210 | } | |
1211 | ||
1212 | /* Get the L2 entry of the first cluster */ | |
1213 | l2_entry = get_l2_entry(s, l2_slice, l2_index); | |
1214 | l2_bitmap = get_l2_bitmap(s, l2_slice, l2_index); | |
1215 | sc_index = offset_to_sc_index(s, guest_offset); | |
1216 | type = qcow2_get_subcluster_type(bs, l2_entry, l2_bitmap, sc_index); | |
1217 | ||
1218 | if (!keep_old) { | |
1219 | switch (type) { | |
1220 | case QCOW2_SUBCLUSTER_COMPRESSED: | |
1221 | cow_start_from = 0; | |
1222 | break; | |
1223 | case QCOW2_SUBCLUSTER_NORMAL: | |
1224 | case QCOW2_SUBCLUSTER_ZERO_ALLOC: | |
1225 | case QCOW2_SUBCLUSTER_UNALLOCATED_ALLOC: | |
1226 | if (has_subclusters(s)) { | |
1227 | /* Skip all leading zero and unallocated subclusters */ | |
1228 | uint32_t alloc_bitmap = l2_bitmap & QCOW_L2_BITMAP_ALL_ALLOC; | |
1229 | cow_start_from = | |
1230 | MIN(sc_index, ctz32(alloc_bitmap)) << s->subcluster_bits; | |
1231 | } else { | |
1232 | cow_start_from = 0; | |
1233 | } | |
1234 | break; | |
1235 | case QCOW2_SUBCLUSTER_ZERO_PLAIN: | |
1236 | case QCOW2_SUBCLUSTER_UNALLOCATED_PLAIN: | |
1237 | cow_start_from = sc_index << s->subcluster_bits; | |
1238 | break; | |
1239 | default: | |
1240 | g_assert_not_reached(); | |
1241 | } | |
1242 | } else { | |
1243 | switch (type) { | |
1244 | case QCOW2_SUBCLUSTER_NORMAL: | |
1245 | cow_start_from = cow_start_to; | |
1246 | break; | |
1247 | case QCOW2_SUBCLUSTER_ZERO_ALLOC: | |
1248 | case QCOW2_SUBCLUSTER_UNALLOCATED_ALLOC: | |
1249 | cow_start_from = sc_index << s->subcluster_bits; | |
1250 | break; | |
1251 | default: | |
1252 | g_assert_not_reached(); | |
1253 | } | |
1254 | } | |
1255 | ||
1256 | /* Get the L2 entry of the last cluster */ | |
1257 | l2_index += nb_clusters - 1; | |
1258 | l2_entry = get_l2_entry(s, l2_slice, l2_index); | |
1259 | l2_bitmap = get_l2_bitmap(s, l2_slice, l2_index); | |
1260 | sc_index = offset_to_sc_index(s, guest_offset + bytes - 1); | |
1261 | type = qcow2_get_subcluster_type(bs, l2_entry, l2_bitmap, sc_index); | |
1262 | ||
1263 | if (!keep_old) { | |
1264 | switch (type) { | |
1265 | case QCOW2_SUBCLUSTER_COMPRESSED: | |
1266 | cow_end_to = ROUND_UP(cow_end_from, s->cluster_size); | |
1267 | break; | |
1268 | case QCOW2_SUBCLUSTER_NORMAL: | |
1269 | case QCOW2_SUBCLUSTER_ZERO_ALLOC: | |
1270 | case QCOW2_SUBCLUSTER_UNALLOCATED_ALLOC: | |
1271 | cow_end_to = ROUND_UP(cow_end_from, s->cluster_size); | |
1272 | if (has_subclusters(s)) { | |
1273 | /* Skip all trailing zero and unallocated subclusters */ | |
1274 | uint32_t alloc_bitmap = l2_bitmap & QCOW_L2_BITMAP_ALL_ALLOC; | |
1275 | cow_end_to -= | |
1276 | MIN(s->subclusters_per_cluster - sc_index - 1, | |
1277 | clz32(alloc_bitmap)) << s->subcluster_bits; | |
1278 | } | |
1279 | break; | |
1280 | case QCOW2_SUBCLUSTER_ZERO_PLAIN: | |
1281 | case QCOW2_SUBCLUSTER_UNALLOCATED_PLAIN: | |
1282 | cow_end_to = ROUND_UP(cow_end_from, s->subcluster_size); | |
1283 | break; | |
1284 | default: | |
1285 | g_assert_not_reached(); | |
1286 | } | |
1287 | } else { | |
1288 | switch (type) { | |
1289 | case QCOW2_SUBCLUSTER_NORMAL: | |
1290 | cow_end_to = cow_end_from; | |
1291 | break; | |
1292 | case QCOW2_SUBCLUSTER_ZERO_ALLOC: | |
1293 | case QCOW2_SUBCLUSTER_UNALLOCATED_ALLOC: | |
1294 | cow_end_to = ROUND_UP(cow_end_from, s->subcluster_size); | |
1295 | break; | |
1296 | default: | |
1297 | g_assert_not_reached(); | |
1298 | } | |
1299 | } | |
1300 | ||
1301 | *m = g_malloc0(sizeof(**m)); | |
1302 | **m = (QCowL2Meta) { | |
1303 | .next = old_m, | |
1304 | ||
1305 | .alloc_offset = host_cluster_offset, | |
1306 | .offset = start_of_cluster(s, guest_offset), | |
1307 | .nb_clusters = nb_clusters, | |
1308 | ||
1309 | .keep_old_clusters = keep_old, | |
1310 | ||
1311 | .cow_start = { | |
1312 | .offset = cow_start_from, | |
1313 | .nb_bytes = cow_start_to - cow_start_from, | |
1314 | }, | |
1315 | .cow_end = { | |
1316 | .offset = cow_end_from, | |
1317 | .nb_bytes = cow_end_to - cow_end_from, | |
1318 | }, | |
1319 | }; | |
1320 | ||
1321 | qemu_co_queue_init(&(*m)->dependent_requests); | |
1322 | QLIST_INSERT_HEAD(&s->cluster_allocs, *m, next_in_flight); | |
1323 | ||
1324 | return 0; | |
1325 | } | |
1326 | ||
1327 | /* | |
1328 | * Returns true if writing to the cluster pointed to by @l2_entry | |
1329 | * requires a new allocation (that is, if the cluster is unallocated | |
1330 | * or has refcount > 1 and therefore cannot be written in-place). | |
1331 | */ | |
1332 | static bool cluster_needs_new_alloc(BlockDriverState *bs, uint64_t l2_entry) | |
1333 | { | |
1334 | switch (qcow2_get_cluster_type(bs, l2_entry)) { | |
1335 | case QCOW2_CLUSTER_NORMAL: | |
1336 | case QCOW2_CLUSTER_ZERO_ALLOC: | |
1337 | if (l2_entry & QCOW_OFLAG_COPIED) { | |
1338 | return false; | |
1339 | } | |
1340 | /* fallthrough */ | |
1341 | case QCOW2_CLUSTER_UNALLOCATED: | |
1342 | case QCOW2_CLUSTER_COMPRESSED: | |
1343 | case QCOW2_CLUSTER_ZERO_PLAIN: | |
1344 | return true; | |
1345 | default: | |
1346 | abort(); | |
1347 | } | |
1348 | } | |
1349 | ||
1350 | /* | |
1351 | * Returns the number of contiguous clusters that can be written to | |
1352 | * using one single write request, starting from @l2_index. | |
1353 | * At most @nb_clusters are checked. | |
1354 | * | |
1355 | * If @new_alloc is true this counts clusters that are either | |
1356 | * unallocated, or allocated but with refcount > 1 (so they need to be | |
1357 | * newly allocated and COWed). | |
1358 | * | |
1359 | * If @new_alloc is false this counts clusters that are already | |
1360 | * allocated and can be overwritten in-place (this includes clusters | |
1361 | * of type QCOW2_CLUSTER_ZERO_ALLOC). | |
1362 | */ | |
1363 | static int count_single_write_clusters(BlockDriverState *bs, int nb_clusters, | |
1364 | uint64_t *l2_slice, int l2_index, | |
1365 | bool new_alloc) | |
1366 | { | |
1367 | BDRVQcow2State *s = bs->opaque; | |
1368 | uint64_t l2_entry = get_l2_entry(s, l2_slice, l2_index); | |
1369 | uint64_t expected_offset = l2_entry & L2E_OFFSET_MASK; | |
1370 | int i; | |
1371 | ||
1372 | for (i = 0; i < nb_clusters; i++) { | |
1373 | l2_entry = get_l2_entry(s, l2_slice, l2_index + i); | |
1374 | if (cluster_needs_new_alloc(bs, l2_entry) != new_alloc) { | |
1375 | break; | |
1376 | } | |
1377 | if (!new_alloc) { | |
1378 | if (expected_offset != (l2_entry & L2E_OFFSET_MASK)) { | |
1379 | break; | |
1380 | } | |
1381 | expected_offset += s->cluster_size; | |
1382 | } | |
1383 | } | |
1384 | ||
1385 | assert(i <= nb_clusters); | |
1386 | return i; | |
1387 | } | |
1388 | ||
1389 | /* | |
1390 | * Check if there already is an AIO write request in flight which allocates | |
1391 | * the same cluster. In this case we need to wait until the previous | |
1392 | * request has completed and updated the L2 table accordingly. | |
1393 | * | |
1394 | * Returns: | |
1395 | * 0 if there was no dependency. *cur_bytes indicates the number of | |
1396 | * bytes from guest_offset that can be read before the next | |
1397 | * dependency must be processed (or the request is complete) | |
1398 | * | |
1399 | * -EAGAIN if we had to wait for another request, previously gathered | |
1400 | * information on cluster allocation may be invalid now. The caller | |
1401 | * must start over anyway, so consider *cur_bytes undefined. | |
1402 | */ | |
1403 | static int coroutine_fn handle_dependencies(BlockDriverState *bs, | |
1404 | uint64_t guest_offset, | |
1405 | uint64_t *cur_bytes, QCowL2Meta **m) | |
1406 | { | |
1407 | BDRVQcow2State *s = bs->opaque; | |
1408 | QCowL2Meta *old_alloc; | |
1409 | uint64_t bytes = *cur_bytes; | |
1410 | ||
1411 | QLIST_FOREACH(old_alloc, &s->cluster_allocs, next_in_flight) { | |
1412 | ||
1413 | uint64_t start = guest_offset; | |
1414 | uint64_t end = start + bytes; | |
1415 | uint64_t old_start = start_of_cluster(s, l2meta_cow_start(old_alloc)); | |
1416 | uint64_t old_end = ROUND_UP(l2meta_cow_end(old_alloc), s->cluster_size); | |
1417 | ||
1418 | if (end <= old_start || start >= old_end) { | |
1419 | /* No intersection */ | |
1420 | continue; | |
1421 | } | |
1422 | ||
1423 | if (old_alloc->keep_old_clusters && | |
1424 | (end <= l2meta_cow_start(old_alloc) || | |
1425 | start >= l2meta_cow_end(old_alloc))) | |
1426 | { | |
1427 | /* | |
1428 | * Clusters intersect but COW areas don't. And cluster itself is | |
1429 | * already allocated. So, there is no actual conflict. | |
1430 | */ | |
1431 | continue; | |
1432 | } | |
1433 | ||
1434 | /* Conflict */ | |
1435 | ||
1436 | if (start < old_start) { | |
1437 | /* Stop at the start of a running allocation */ | |
1438 | bytes = old_start - start; | |
1439 | } else { | |
1440 | bytes = 0; | |
1441 | } | |
1442 | ||
1443 | /* | |
1444 | * Stop if an l2meta already exists. After yielding, it wouldn't | |
1445 | * be valid any more, so we'd have to clean up the old L2Metas | |
1446 | * and deal with requests depending on them before starting to | |
1447 | * gather new ones. Not worth the trouble. | |
1448 | */ | |
1449 | if (bytes == 0 && *m) { | |
1450 | *cur_bytes = 0; | |
1451 | return 0; | |
1452 | } | |
1453 | ||
1454 | if (bytes == 0) { | |
1455 | /* | |
1456 | * Wait for the dependency to complete. We need to recheck | |
1457 | * the free/allocated clusters when we continue. | |
1458 | */ | |
1459 | qemu_co_queue_wait(&old_alloc->dependent_requests, &s->lock); | |
1460 | return -EAGAIN; | |
1461 | } | |
1462 | } | |
1463 | ||
1464 | /* Make sure that existing clusters and new allocations are only used up to | |
1465 | * the next dependency if we shortened the request above */ | |
1466 | *cur_bytes = bytes; | |
1467 | ||
1468 | return 0; | |
1469 | } | |
1470 | ||
1471 | /* | |
1472 | * Checks how many already allocated clusters that don't require a new | |
1473 | * allocation there are at the given guest_offset (up to *bytes). | |
1474 | * If *host_offset is not INV_OFFSET, only physically contiguous clusters | |
1475 | * beginning at this host offset are counted. | |
1476 | * | |
1477 | * Note that guest_offset may not be cluster aligned. In this case, the | |
1478 | * returned *host_offset points to exact byte referenced by guest_offset and | |
1479 | * therefore isn't cluster aligned as well. | |
1480 | * | |
1481 | * Returns: | |
1482 | * 0: if no allocated clusters are available at the given offset. | |
1483 | * *bytes is normally unchanged. It is set to 0 if the cluster | |
1484 | * is allocated and can be overwritten in-place but doesn't have | |
1485 | * the right physical offset. | |
1486 | * | |
1487 | * 1: if allocated clusters that can be overwritten in place are | |
1488 | * available at the requested offset. *bytes may have decreased | |
1489 | * and describes the length of the area that can be written to. | |
1490 | * | |
1491 | * -errno: in error cases | |
1492 | */ | |
1493 | static int coroutine_fn handle_copied(BlockDriverState *bs, | |
1494 | uint64_t guest_offset, uint64_t *host_offset, uint64_t *bytes, | |
1495 | QCowL2Meta **m) | |
1496 | { | |
1497 | BDRVQcow2State *s = bs->opaque; | |
1498 | int l2_index; | |
1499 | uint64_t l2_entry, cluster_offset; | |
1500 | uint64_t *l2_slice; | |
1501 | uint64_t nb_clusters; | |
1502 | unsigned int keep_clusters; | |
1503 | int ret; | |
1504 | ||
1505 | trace_qcow2_handle_copied(qemu_coroutine_self(), guest_offset, *host_offset, | |
1506 | *bytes); | |
1507 | ||
1508 | assert(*host_offset == INV_OFFSET || offset_into_cluster(s, guest_offset) | |
1509 | == offset_into_cluster(s, *host_offset)); | |
1510 | ||
1511 | /* | |
1512 | * Calculate the number of clusters to look for. We stop at L2 slice | |
1513 | * boundaries to keep things simple. | |
1514 | */ | |
1515 | nb_clusters = | |
1516 | size_to_clusters(s, offset_into_cluster(s, guest_offset) + *bytes); | |
1517 | ||
1518 | l2_index = offset_to_l2_slice_index(s, guest_offset); | |
1519 | nb_clusters = MIN(nb_clusters, s->l2_slice_size - l2_index); | |
1520 | /* Limit total byte count to BDRV_REQUEST_MAX_BYTES */ | |
1521 | nb_clusters = MIN(nb_clusters, BDRV_REQUEST_MAX_BYTES >> s->cluster_bits); | |
1522 | ||
1523 | /* Find L2 entry for the first involved cluster */ | |
1524 | ret = get_cluster_table(bs, guest_offset, &l2_slice, &l2_index); | |
1525 | if (ret < 0) { | |
1526 | return ret; | |
1527 | } | |
1528 | ||
1529 | l2_entry = get_l2_entry(s, l2_slice, l2_index); | |
1530 | cluster_offset = l2_entry & L2E_OFFSET_MASK; | |
1531 | ||
1532 | if (!cluster_needs_new_alloc(bs, l2_entry)) { | |
1533 | if (offset_into_cluster(s, cluster_offset)) { | |
1534 | qcow2_signal_corruption(bs, true, -1, -1, "%s cluster offset " | |
1535 | "%#" PRIx64 " unaligned (guest offset: %#" | |
1536 | PRIx64 ")", l2_entry & QCOW_OFLAG_ZERO ? | |
1537 | "Preallocated zero" : "Data", | |
1538 | cluster_offset, guest_offset); | |
1539 | ret = -EIO; | |
1540 | goto out; | |
1541 | } | |
1542 | ||
1543 | /* If a specific host_offset is required, check it */ | |
1544 | if (*host_offset != INV_OFFSET && cluster_offset != *host_offset) { | |
1545 | *bytes = 0; | |
1546 | ret = 0; | |
1547 | goto out; | |
1548 | } | |
1549 | ||
1550 | /* We keep all QCOW_OFLAG_COPIED clusters */ | |
1551 | keep_clusters = count_single_write_clusters(bs, nb_clusters, l2_slice, | |
1552 | l2_index, false); | |
1553 | assert(keep_clusters <= nb_clusters); | |
1554 | ||
1555 | *bytes = MIN(*bytes, | |
1556 | keep_clusters * s->cluster_size | |
1557 | - offset_into_cluster(s, guest_offset)); | |
1558 | assert(*bytes != 0); | |
1559 | ||
1560 | ret = calculate_l2_meta(bs, cluster_offset, guest_offset, | |
1561 | *bytes, l2_slice, m, true); | |
1562 | if (ret < 0) { | |
1563 | goto out; | |
1564 | } | |
1565 | ||
1566 | ret = 1; | |
1567 | } else { | |
1568 | ret = 0; | |
1569 | } | |
1570 | ||
1571 | /* Cleanup */ | |
1572 | out: | |
1573 | qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice); | |
1574 | ||
1575 | /* Only return a host offset if we actually made progress. Otherwise we | |
1576 | * would make requirements for handle_alloc() that it can't fulfill */ | |
1577 | if (ret > 0) { | |
1578 | *host_offset = cluster_offset + offset_into_cluster(s, guest_offset); | |
1579 | } | |
1580 | ||
1581 | return ret; | |
1582 | } | |
1583 | ||
1584 | /* | |
1585 | * Allocates new clusters for the given guest_offset. | |
1586 | * | |
1587 | * At most *nb_clusters are allocated, and on return *nb_clusters is updated to | |
1588 | * contain the number of clusters that have been allocated and are contiguous | |
1589 | * in the image file. | |
1590 | * | |
1591 | * If *host_offset is not INV_OFFSET, it specifies the offset in the image file | |
1592 | * at which the new clusters must start. *nb_clusters can be 0 on return in | |
1593 | * this case if the cluster at host_offset is already in use. If *host_offset | |
1594 | * is INV_OFFSET, the clusters can be allocated anywhere in the image file. | |
1595 | * | |
1596 | * *host_offset is updated to contain the offset into the image file at which | |
1597 | * the first allocated cluster starts. | |
1598 | * | |
1599 | * Return 0 on success and -errno in error cases. -EAGAIN means that the | |
1600 | * function has been waiting for another request and the allocation must be | |
1601 | * restarted, but the whole request should not be failed. | |
1602 | */ | |
1603 | static int coroutine_fn do_alloc_cluster_offset(BlockDriverState *bs, | |
1604 | uint64_t guest_offset, | |
1605 | uint64_t *host_offset, | |
1606 | uint64_t *nb_clusters) | |
1607 | { | |
1608 | BDRVQcow2State *s = bs->opaque; | |
1609 | ||
1610 | trace_qcow2_do_alloc_clusters_offset(qemu_coroutine_self(), guest_offset, | |
1611 | *host_offset, *nb_clusters); | |
1612 | ||
1613 | if (has_data_file(bs)) { | |
1614 | assert(*host_offset == INV_OFFSET || | |
1615 | *host_offset == start_of_cluster(s, guest_offset)); | |
1616 | *host_offset = start_of_cluster(s, guest_offset); | |
1617 | return 0; | |
1618 | } | |
1619 | ||
1620 | /* Allocate new clusters */ | |
1621 | trace_qcow2_cluster_alloc_phys(qemu_coroutine_self()); | |
1622 | if (*host_offset == INV_OFFSET) { | |
1623 | int64_t cluster_offset = | |
1624 | qcow2_alloc_clusters(bs, *nb_clusters * s->cluster_size); | |
1625 | if (cluster_offset < 0) { | |
1626 | return cluster_offset; | |
1627 | } | |
1628 | *host_offset = cluster_offset; | |
1629 | return 0; | |
1630 | } else { | |
1631 | int64_t ret = qcow2_alloc_clusters_at(bs, *host_offset, *nb_clusters); | |
1632 | if (ret < 0) { | |
1633 | return ret; | |
1634 | } | |
1635 | *nb_clusters = ret; | |
1636 | return 0; | |
1637 | } | |
1638 | } | |
1639 | ||
1640 | /* | |
1641 | * Allocates new clusters for an area that is either still unallocated or | |
1642 | * cannot be overwritten in-place. If *host_offset is not INV_OFFSET, | |
1643 | * clusters are only allocated if the new allocation can match the specified | |
1644 | * host offset. | |
1645 | * | |
1646 | * Note that guest_offset may not be cluster aligned. In this case, the | |
1647 | * returned *host_offset points to exact byte referenced by guest_offset and | |
1648 | * therefore isn't cluster aligned as well. | |
1649 | * | |
1650 | * Returns: | |
1651 | * 0: if no clusters could be allocated. *bytes is set to 0, | |
1652 | * *host_offset is left unchanged. | |
1653 | * | |
1654 | * 1: if new clusters were allocated. *bytes may be decreased if the | |
1655 | * new allocation doesn't cover all of the requested area. | |
1656 | * *host_offset is updated to contain the host offset of the first | |
1657 | * newly allocated cluster. | |
1658 | * | |
1659 | * -errno: in error cases | |
1660 | */ | |
1661 | static int coroutine_fn handle_alloc(BlockDriverState *bs, | |
1662 | uint64_t guest_offset, uint64_t *host_offset, uint64_t *bytes, | |
1663 | QCowL2Meta **m) | |
1664 | { | |
1665 | BDRVQcow2State *s = bs->opaque; | |
1666 | int l2_index; | |
1667 | uint64_t *l2_slice; | |
1668 | uint64_t nb_clusters; | |
1669 | int ret; | |
1670 | ||
1671 | uint64_t alloc_cluster_offset; | |
1672 | ||
1673 | trace_qcow2_handle_alloc(qemu_coroutine_self(), guest_offset, *host_offset, | |
1674 | *bytes); | |
1675 | assert(*bytes > 0); | |
1676 | ||
1677 | /* | |
1678 | * Calculate the number of clusters to look for. We stop at L2 slice | |
1679 | * boundaries to keep things simple. | |
1680 | */ | |
1681 | nb_clusters = | |
1682 | size_to_clusters(s, offset_into_cluster(s, guest_offset) + *bytes); | |
1683 | ||
1684 | l2_index = offset_to_l2_slice_index(s, guest_offset); | |
1685 | nb_clusters = MIN(nb_clusters, s->l2_slice_size - l2_index); | |
1686 | /* Limit total allocation byte count to BDRV_REQUEST_MAX_BYTES */ | |
1687 | nb_clusters = MIN(nb_clusters, BDRV_REQUEST_MAX_BYTES >> s->cluster_bits); | |
1688 | ||
1689 | /* Find L2 entry for the first involved cluster */ | |
1690 | ret = get_cluster_table(bs, guest_offset, &l2_slice, &l2_index); | |
1691 | if (ret < 0) { | |
1692 | return ret; | |
1693 | } | |
1694 | ||
1695 | nb_clusters = count_single_write_clusters(bs, nb_clusters, | |
1696 | l2_slice, l2_index, true); | |
1697 | ||
1698 | /* This function is only called when there were no non-COW clusters, so if | |
1699 | * we can't find any unallocated or COW clusters either, something is | |
1700 | * wrong with our code. */ | |
1701 | assert(nb_clusters > 0); | |
1702 | ||
1703 | /* Allocate at a given offset in the image file */ | |
1704 | alloc_cluster_offset = *host_offset == INV_OFFSET ? INV_OFFSET : | |
1705 | start_of_cluster(s, *host_offset); | |
1706 | ret = do_alloc_cluster_offset(bs, guest_offset, &alloc_cluster_offset, | |
1707 | &nb_clusters); | |
1708 | if (ret < 0) { | |
1709 | goto out; | |
1710 | } | |
1711 | ||
1712 | /* Can't extend contiguous allocation */ | |
1713 | if (nb_clusters == 0) { | |
1714 | *bytes = 0; | |
1715 | ret = 0; | |
1716 | goto out; | |
1717 | } | |
1718 | ||
1719 | assert(alloc_cluster_offset != INV_OFFSET); | |
1720 | ||
1721 | /* | |
1722 | * Save info needed for meta data update. | |
1723 | * | |
1724 | * requested_bytes: Number of bytes from the start of the first | |
1725 | * newly allocated cluster to the end of the (possibly shortened | |
1726 | * before) write request. | |
1727 | * | |
1728 | * avail_bytes: Number of bytes from the start of the first | |
1729 | * newly allocated to the end of the last newly allocated cluster. | |
1730 | * | |
1731 | * nb_bytes: The number of bytes from the start of the first | |
1732 | * newly allocated cluster to the end of the area that the write | |
1733 | * request actually writes to (excluding COW at the end) | |
1734 | */ | |
1735 | uint64_t requested_bytes = *bytes + offset_into_cluster(s, guest_offset); | |
1736 | int avail_bytes = nb_clusters << s->cluster_bits; | |
1737 | int nb_bytes = MIN(requested_bytes, avail_bytes); | |
1738 | ||
1739 | *host_offset = alloc_cluster_offset + offset_into_cluster(s, guest_offset); | |
1740 | *bytes = MIN(*bytes, nb_bytes - offset_into_cluster(s, guest_offset)); | |
1741 | assert(*bytes != 0); | |
1742 | ||
1743 | ret = calculate_l2_meta(bs, alloc_cluster_offset, guest_offset, *bytes, | |
1744 | l2_slice, m, false); | |
1745 | if (ret < 0) { | |
1746 | goto out; | |
1747 | } | |
1748 | ||
1749 | ret = 1; | |
1750 | ||
1751 | out: | |
1752 | qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice); | |
1753 | return ret; | |
1754 | } | |
1755 | ||
1756 | /* | |
1757 | * For a given area on the virtual disk defined by @offset and @bytes, | |
1758 | * find the corresponding area on the qcow2 image, allocating new | |
1759 | * clusters (or subclusters) if necessary. The result can span a | |
1760 | * combination of allocated and previously unallocated clusters. | |
1761 | * | |
1762 | * Note that offset may not be cluster aligned. In this case, the returned | |
1763 | * *host_offset points to exact byte referenced by offset and therefore | |
1764 | * isn't cluster aligned as well. | |
1765 | * | |
1766 | * On return, @host_offset is set to the beginning of the requested | |
1767 | * area. This area is guaranteed to be contiguous on the qcow2 file | |
1768 | * but it can be smaller than initially requested. In this case @bytes | |
1769 | * is updated with the actual size. | |
1770 | * | |
1771 | * If any clusters or subclusters were allocated then @m contains a | |
1772 | * list with the information of all the affected regions. Note that | |
1773 | * this can happen regardless of whether this function succeeds or | |
1774 | * not. The caller is responsible for updating the L2 metadata of the | |
1775 | * allocated clusters (on success) or freeing them (on failure), and | |
1776 | * for clearing the contents of @m afterwards in both cases. | |
1777 | * | |
1778 | * If the request conflicts with another write request in flight, the coroutine | |
1779 | * is queued and will be reentered when the dependency has completed. | |
1780 | * | |
1781 | * Return 0 on success and -errno in error cases | |
1782 | */ | |
1783 | int coroutine_fn qcow2_alloc_host_offset(BlockDriverState *bs, uint64_t offset, | |
1784 | unsigned int *bytes, | |
1785 | uint64_t *host_offset, | |
1786 | QCowL2Meta **m) | |
1787 | { | |
1788 | BDRVQcow2State *s = bs->opaque; | |
1789 | uint64_t start, remaining; | |
1790 | uint64_t cluster_offset; | |
1791 | uint64_t cur_bytes; | |
1792 | int ret; | |
1793 | ||
1794 | trace_qcow2_alloc_clusters_offset(qemu_coroutine_self(), offset, *bytes); | |
1795 | ||
1796 | again: | |
1797 | start = offset; | |
1798 | remaining = *bytes; | |
1799 | cluster_offset = INV_OFFSET; | |
1800 | *host_offset = INV_OFFSET; | |
1801 | cur_bytes = 0; | |
1802 | *m = NULL; | |
1803 | ||
1804 | while (true) { | |
1805 | ||
1806 | if (*host_offset == INV_OFFSET && cluster_offset != INV_OFFSET) { | |
1807 | *host_offset = cluster_offset; | |
1808 | } | |
1809 | ||
1810 | assert(remaining >= cur_bytes); | |
1811 | ||
1812 | start += cur_bytes; | |
1813 | remaining -= cur_bytes; | |
1814 | ||
1815 | if (cluster_offset != INV_OFFSET) { | |
1816 | cluster_offset += cur_bytes; | |
1817 | } | |
1818 | ||
1819 | if (remaining == 0) { | |
1820 | break; | |
1821 | } | |
1822 | ||
1823 | cur_bytes = remaining; | |
1824 | ||
1825 | /* | |
1826 | * Now start gathering as many contiguous clusters as possible: | |
1827 | * | |
1828 | * 1. Check for overlaps with in-flight allocations | |
1829 | * | |
1830 | * a) Overlap not in the first cluster -> shorten this request and | |
1831 | * let the caller handle the rest in its next loop iteration. | |
1832 | * | |
1833 | * b) Real overlaps of two requests. Yield and restart the search | |
1834 | * for contiguous clusters (the situation could have changed | |
1835 | * while we were sleeping) | |
1836 | * | |
1837 | * c) TODO: Request starts in the same cluster as the in-flight | |
1838 | * allocation ends. Shorten the COW of the in-fight allocation, | |
1839 | * set cluster_offset to write to the same cluster and set up | |
1840 | * the right synchronisation between the in-flight request and | |
1841 | * the new one. | |
1842 | */ | |
1843 | ret = handle_dependencies(bs, start, &cur_bytes, m); | |
1844 | if (ret == -EAGAIN) { | |
1845 | /* Currently handle_dependencies() doesn't yield if we already had | |
1846 | * an allocation. If it did, we would have to clean up the L2Meta | |
1847 | * structs before starting over. */ | |
1848 | assert(*m == NULL); | |
1849 | goto again; | |
1850 | } else if (ret < 0) { | |
1851 | return ret; | |
1852 | } else if (cur_bytes == 0) { | |
1853 | break; | |
1854 | } else { | |
1855 | /* handle_dependencies() may have decreased cur_bytes (shortened | |
1856 | * the allocations below) so that the next dependency is processed | |
1857 | * correctly during the next loop iteration. */ | |
1858 | } | |
1859 | ||
1860 | /* | |
1861 | * 2. Count contiguous COPIED clusters. | |
1862 | */ | |
1863 | ret = handle_copied(bs, start, &cluster_offset, &cur_bytes, m); | |
1864 | if (ret < 0) { | |
1865 | return ret; | |
1866 | } else if (ret) { | |
1867 | continue; | |
1868 | } else if (cur_bytes == 0) { | |
1869 | break; | |
1870 | } | |
1871 | ||
1872 | /* | |
1873 | * 3. If the request still hasn't completed, allocate new clusters, | |
1874 | * considering any cluster_offset of steps 1c or 2. | |
1875 | */ | |
1876 | ret = handle_alloc(bs, start, &cluster_offset, &cur_bytes, m); | |
1877 | if (ret < 0) { | |
1878 | return ret; | |
1879 | } else if (ret) { | |
1880 | continue; | |
1881 | } else { | |
1882 | assert(cur_bytes == 0); | |
1883 | break; | |
1884 | } | |
1885 | } | |
1886 | ||
1887 | *bytes -= remaining; | |
1888 | assert(*bytes > 0); | |
1889 | assert(*host_offset != INV_OFFSET); | |
1890 | assert(offset_into_cluster(s, *host_offset) == | |
1891 | offset_into_cluster(s, offset)); | |
1892 | ||
1893 | return 0; | |
1894 | } | |
1895 | ||
1896 | /* | |
1897 | * This discards as many clusters of nb_clusters as possible at once (i.e. | |
1898 | * all clusters in the same L2 slice) and returns the number of discarded | |
1899 | * clusters. | |
1900 | */ | |
1901 | static int discard_in_l2_slice(BlockDriverState *bs, uint64_t offset, | |
1902 | uint64_t nb_clusters, | |
1903 | enum qcow2_discard_type type, bool full_discard) | |
1904 | { | |
1905 | BDRVQcow2State *s = bs->opaque; | |
1906 | uint64_t *l2_slice; | |
1907 | int l2_index; | |
1908 | int ret; | |
1909 | int i; | |
1910 | ||
1911 | ret = get_cluster_table(bs, offset, &l2_slice, &l2_index); | |
1912 | if (ret < 0) { | |
1913 | return ret; | |
1914 | } | |
1915 | ||
1916 | /* Limit nb_clusters to one L2 slice */ | |
1917 | nb_clusters = MIN(nb_clusters, s->l2_slice_size - l2_index); | |
1918 | assert(nb_clusters <= INT_MAX); | |
1919 | ||
1920 | for (i = 0; i < nb_clusters; i++) { | |
1921 | uint64_t old_l2_entry = get_l2_entry(s, l2_slice, l2_index + i); | |
1922 | uint64_t old_l2_bitmap = get_l2_bitmap(s, l2_slice, l2_index + i); | |
1923 | uint64_t new_l2_entry = old_l2_entry; | |
1924 | uint64_t new_l2_bitmap = old_l2_bitmap; | |
1925 | QCow2ClusterType cluster_type = | |
1926 | qcow2_get_cluster_type(bs, old_l2_entry); | |
1927 | bool keep_reference = (cluster_type != QCOW2_CLUSTER_COMPRESSED) && | |
1928 | !full_discard && | |
1929 | (s->discard_no_unref && | |
1930 | type == QCOW2_DISCARD_REQUEST); | |
1931 | ||
1932 | /* | |
1933 | * If full_discard is true, the cluster should not read back as zeroes, | |
1934 | * but rather fall through to the backing file. | |
1935 | * | |
1936 | * If full_discard is false, make sure that a discarded area reads back | |
1937 | * as zeroes for v3 images (we cannot do it for v2 without actually | |
1938 | * writing a zero-filled buffer). We can skip the operation if the | |
1939 | * cluster is already marked as zero, or if it's unallocated and we | |
1940 | * don't have a backing file. | |
1941 | * | |
1942 | * TODO We might want to use bdrv_block_status(bs) here, but we're | |
1943 | * holding s->lock, so that doesn't work today. | |
1944 | */ | |
1945 | if (full_discard) { | |
1946 | new_l2_entry = new_l2_bitmap = 0; | |
1947 | } else if (bs->backing || qcow2_cluster_is_allocated(cluster_type)) { | |
1948 | if (has_subclusters(s)) { | |
1949 | if (keep_reference) { | |
1950 | new_l2_entry = old_l2_entry; | |
1951 | } else { | |
1952 | new_l2_entry = 0; | |
1953 | } | |
1954 | new_l2_bitmap = QCOW_L2_BITMAP_ALL_ZEROES; | |
1955 | } else { | |
1956 | if (s->qcow_version >= 3) { | |
1957 | if (keep_reference) { | |
1958 | new_l2_entry |= QCOW_OFLAG_ZERO; | |
1959 | } else { | |
1960 | new_l2_entry = QCOW_OFLAG_ZERO; | |
1961 | } | |
1962 | } else { | |
1963 | new_l2_entry = 0; | |
1964 | } | |
1965 | } | |
1966 | } | |
1967 | ||
1968 | if (old_l2_entry == new_l2_entry && old_l2_bitmap == new_l2_bitmap) { | |
1969 | continue; | |
1970 | } | |
1971 | ||
1972 | /* First remove L2 entries */ | |
1973 | qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_slice); | |
1974 | set_l2_entry(s, l2_slice, l2_index + i, new_l2_entry); | |
1975 | if (has_subclusters(s)) { | |
1976 | set_l2_bitmap(s, l2_slice, l2_index + i, new_l2_bitmap); | |
1977 | } | |
1978 | if (!keep_reference) { | |
1979 | /* Then decrease the refcount */ | |
1980 | qcow2_free_any_cluster(bs, old_l2_entry, type); | |
1981 | } else if (s->discard_passthrough[type] && | |
1982 | (cluster_type == QCOW2_CLUSTER_NORMAL || | |
1983 | cluster_type == QCOW2_CLUSTER_ZERO_ALLOC)) { | |
1984 | /* If we keep the reference, pass on the discard still */ | |
1985 | bdrv_pdiscard(s->data_file, old_l2_entry & L2E_OFFSET_MASK, | |
1986 | s->cluster_size); | |
1987 | } | |
1988 | } | |
1989 | ||
1990 | qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice); | |
1991 | ||
1992 | return nb_clusters; | |
1993 | } | |
1994 | ||
1995 | int qcow2_cluster_discard(BlockDriverState *bs, uint64_t offset, | |
1996 | uint64_t bytes, enum qcow2_discard_type type, | |
1997 | bool full_discard) | |
1998 | { | |
1999 | BDRVQcow2State *s = bs->opaque; | |
2000 | uint64_t end_offset = offset + bytes; | |
2001 | uint64_t nb_clusters; | |
2002 | int64_t cleared; | |
2003 | int ret; | |
2004 | ||
2005 | /* Caller must pass aligned values, except at image end */ | |
2006 | assert(QEMU_IS_ALIGNED(offset, s->cluster_size)); | |
2007 | assert(QEMU_IS_ALIGNED(end_offset, s->cluster_size) || | |
2008 | end_offset == bs->total_sectors << BDRV_SECTOR_BITS); | |
2009 | ||
2010 | nb_clusters = size_to_clusters(s, bytes); | |
2011 | ||
2012 | s->cache_discards = true; | |
2013 | ||
2014 | /* Each L2 slice is handled by its own loop iteration */ | |
2015 | while (nb_clusters > 0) { | |
2016 | cleared = discard_in_l2_slice(bs, offset, nb_clusters, type, | |
2017 | full_discard); | |
2018 | if (cleared < 0) { | |
2019 | ret = cleared; | |
2020 | goto fail; | |
2021 | } | |
2022 | ||
2023 | nb_clusters -= cleared; | |
2024 | offset += (cleared * s->cluster_size); | |
2025 | } | |
2026 | ||
2027 | ret = 0; | |
2028 | fail: | |
2029 | s->cache_discards = false; | |
2030 | qcow2_process_discards(bs, ret); | |
2031 | ||
2032 | return ret; | |
2033 | } | |
2034 | ||
2035 | /* | |
2036 | * This zeroes as many clusters of nb_clusters as possible at once (i.e. | |
2037 | * all clusters in the same L2 slice) and returns the number of zeroed | |
2038 | * clusters. | |
2039 | */ | |
2040 | static int coroutine_fn | |
2041 | zero_in_l2_slice(BlockDriverState *bs, uint64_t offset, | |
2042 | uint64_t nb_clusters, int flags) | |
2043 | { | |
2044 | BDRVQcow2State *s = bs->opaque; | |
2045 | uint64_t *l2_slice; | |
2046 | int l2_index; | |
2047 | int ret; | |
2048 | int i; | |
2049 | ||
2050 | ret = get_cluster_table(bs, offset, &l2_slice, &l2_index); | |
2051 | if (ret < 0) { | |
2052 | return ret; | |
2053 | } | |
2054 | ||
2055 | /* Limit nb_clusters to one L2 slice */ | |
2056 | nb_clusters = MIN(nb_clusters, s->l2_slice_size - l2_index); | |
2057 | assert(nb_clusters <= INT_MAX); | |
2058 | ||
2059 | for (i = 0; i < nb_clusters; i++) { | |
2060 | uint64_t old_l2_entry = get_l2_entry(s, l2_slice, l2_index + i); | |
2061 | uint64_t old_l2_bitmap = get_l2_bitmap(s, l2_slice, l2_index + i); | |
2062 | QCow2ClusterType type = qcow2_get_cluster_type(bs, old_l2_entry); | |
2063 | bool unmap = (type == QCOW2_CLUSTER_COMPRESSED) || | |
2064 | ((flags & BDRV_REQ_MAY_UNMAP) && qcow2_cluster_is_allocated(type)); | |
2065 | uint64_t new_l2_entry = unmap ? 0 : old_l2_entry; | |
2066 | uint64_t new_l2_bitmap = old_l2_bitmap; | |
2067 | ||
2068 | if (has_subclusters(s)) { | |
2069 | new_l2_bitmap = QCOW_L2_BITMAP_ALL_ZEROES; | |
2070 | } else { | |
2071 | new_l2_entry |= QCOW_OFLAG_ZERO; | |
2072 | } | |
2073 | ||
2074 | if (old_l2_entry == new_l2_entry && old_l2_bitmap == new_l2_bitmap) { | |
2075 | continue; | |
2076 | } | |
2077 | ||
2078 | /* First update L2 entries */ | |
2079 | qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_slice); | |
2080 | set_l2_entry(s, l2_slice, l2_index + i, new_l2_entry); | |
2081 | if (has_subclusters(s)) { | |
2082 | set_l2_bitmap(s, l2_slice, l2_index + i, new_l2_bitmap); | |
2083 | } | |
2084 | ||
2085 | /* Then decrease the refcount */ | |
2086 | if (unmap) { | |
2087 | qcow2_free_any_cluster(bs, old_l2_entry, QCOW2_DISCARD_REQUEST); | |
2088 | } | |
2089 | } | |
2090 | ||
2091 | qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice); | |
2092 | ||
2093 | return nb_clusters; | |
2094 | } | |
2095 | ||
2096 | static int coroutine_fn | |
2097 | zero_l2_subclusters(BlockDriverState *bs, uint64_t offset, | |
2098 | unsigned nb_subclusters) | |
2099 | { | |
2100 | BDRVQcow2State *s = bs->opaque; | |
2101 | uint64_t *l2_slice; | |
2102 | uint64_t old_l2_bitmap, l2_bitmap; | |
2103 | int l2_index, ret, sc = offset_to_sc_index(s, offset); | |
2104 | ||
2105 | /* For full clusters use zero_in_l2_slice() instead */ | |
2106 | assert(nb_subclusters > 0 && nb_subclusters < s->subclusters_per_cluster); | |
2107 | assert(sc + nb_subclusters <= s->subclusters_per_cluster); | |
2108 | assert(offset_into_subcluster(s, offset) == 0); | |
2109 | ||
2110 | ret = get_cluster_table(bs, offset, &l2_slice, &l2_index); | |
2111 | if (ret < 0) { | |
2112 | return ret; | |
2113 | } | |
2114 | ||
2115 | switch (qcow2_get_cluster_type(bs, get_l2_entry(s, l2_slice, l2_index))) { | |
2116 | case QCOW2_CLUSTER_COMPRESSED: | |
2117 | ret = -ENOTSUP; /* We cannot partially zeroize compressed clusters */ | |
2118 | goto out; | |
2119 | case QCOW2_CLUSTER_NORMAL: | |
2120 | case QCOW2_CLUSTER_UNALLOCATED: | |
2121 | break; | |
2122 | default: | |
2123 | g_assert_not_reached(); | |
2124 | } | |
2125 | ||
2126 | old_l2_bitmap = l2_bitmap = get_l2_bitmap(s, l2_slice, l2_index); | |
2127 | ||
2128 | l2_bitmap |= QCOW_OFLAG_SUB_ZERO_RANGE(sc, sc + nb_subclusters); | |
2129 | l2_bitmap &= ~QCOW_OFLAG_SUB_ALLOC_RANGE(sc, sc + nb_subclusters); | |
2130 | ||
2131 | if (old_l2_bitmap != l2_bitmap) { | |
2132 | set_l2_bitmap(s, l2_slice, l2_index, l2_bitmap); | |
2133 | qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_slice); | |
2134 | } | |
2135 | ||
2136 | ret = 0; | |
2137 | out: | |
2138 | qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice); | |
2139 | ||
2140 | return ret; | |
2141 | } | |
2142 | ||
2143 | int coroutine_fn qcow2_subcluster_zeroize(BlockDriverState *bs, uint64_t offset, | |
2144 | uint64_t bytes, int flags) | |
2145 | { | |
2146 | BDRVQcow2State *s = bs->opaque; | |
2147 | uint64_t end_offset = offset + bytes; | |
2148 | uint64_t nb_clusters; | |
2149 | unsigned head, tail; | |
2150 | int64_t cleared; | |
2151 | int ret; | |
2152 | ||
2153 | /* If we have to stay in sync with an external data file, zero out | |
2154 | * s->data_file first. */ | |
2155 | if (data_file_is_raw(bs)) { | |
2156 | assert(has_data_file(bs)); | |
2157 | ret = bdrv_co_pwrite_zeroes(s->data_file, offset, bytes, flags); | |
2158 | if (ret < 0) { | |
2159 | return ret; | |
2160 | } | |
2161 | } | |
2162 | ||
2163 | /* Caller must pass aligned values, except at image end */ | |
2164 | assert(offset_into_subcluster(s, offset) == 0); | |
2165 | assert(offset_into_subcluster(s, end_offset) == 0 || | |
2166 | end_offset >= bs->total_sectors << BDRV_SECTOR_BITS); | |
2167 | ||
2168 | /* | |
2169 | * The zero flag is only supported by version 3 and newer. However, if we | |
2170 | * have no backing file, we can resort to discard in version 2. | |
2171 | */ | |
2172 | if (s->qcow_version < 3) { | |
2173 | if (!bs->backing) { | |
2174 | return qcow2_cluster_discard(bs, offset, bytes, | |
2175 | QCOW2_DISCARD_REQUEST, false); | |
2176 | } | |
2177 | return -ENOTSUP; | |
2178 | } | |
2179 | ||
2180 | head = MIN(end_offset, ROUND_UP(offset, s->cluster_size)) - offset; | |
2181 | offset += head; | |
2182 | ||
2183 | tail = (end_offset >= bs->total_sectors << BDRV_SECTOR_BITS) ? 0 : | |
2184 | end_offset - MAX(offset, start_of_cluster(s, end_offset)); | |
2185 | end_offset -= tail; | |
2186 | ||
2187 | s->cache_discards = true; | |
2188 | ||
2189 | if (head) { | |
2190 | ret = zero_l2_subclusters(bs, offset - head, | |
2191 | size_to_subclusters(s, head)); | |
2192 | if (ret < 0) { | |
2193 | goto fail; | |
2194 | } | |
2195 | } | |
2196 | ||
2197 | /* Each L2 slice is handled by its own loop iteration */ | |
2198 | nb_clusters = size_to_clusters(s, end_offset - offset); | |
2199 | ||
2200 | while (nb_clusters > 0) { | |
2201 | cleared = zero_in_l2_slice(bs, offset, nb_clusters, flags); | |
2202 | if (cleared < 0) { | |
2203 | ret = cleared; | |
2204 | goto fail; | |
2205 | } | |
2206 | ||
2207 | nb_clusters -= cleared; | |
2208 | offset += (cleared * s->cluster_size); | |
2209 | } | |
2210 | ||
2211 | if (tail) { | |
2212 | ret = zero_l2_subclusters(bs, end_offset, size_to_subclusters(s, tail)); | |
2213 | if (ret < 0) { | |
2214 | goto fail; | |
2215 | } | |
2216 | } | |
2217 | ||
2218 | ret = 0; | |
2219 | fail: | |
2220 | s->cache_discards = false; | |
2221 | qcow2_process_discards(bs, ret); | |
2222 | ||
2223 | return ret; | |
2224 | } | |
2225 | ||
2226 | /* | |
2227 | * Expands all zero clusters in a specific L1 table (or deallocates them, for | |
2228 | * non-backed non-pre-allocated zero clusters). | |
2229 | * | |
2230 | * l1_entries and *visited_l1_entries are used to keep track of progress for | |
2231 | * status_cb(). l1_entries contains the total number of L1 entries and | |
2232 | * *visited_l1_entries counts all visited L1 entries. | |
2233 | */ | |
2234 | static int expand_zero_clusters_in_l1(BlockDriverState *bs, uint64_t *l1_table, | |
2235 | int l1_size, int64_t *visited_l1_entries, | |
2236 | int64_t l1_entries, | |
2237 | BlockDriverAmendStatusCB *status_cb, | |
2238 | void *cb_opaque) | |
2239 | { | |
2240 | BDRVQcow2State *s = bs->opaque; | |
2241 | bool is_active_l1 = (l1_table == s->l1_table); | |
2242 | uint64_t *l2_slice = NULL; | |
2243 | unsigned slice, slice_size2, n_slices; | |
2244 | int ret; | |
2245 | int i, j; | |
2246 | ||
2247 | /* qcow2_downgrade() is not allowed in images with subclusters */ | |
2248 | assert(!has_subclusters(s)); | |
2249 | ||
2250 | slice_size2 = s->l2_slice_size * l2_entry_size(s); | |
2251 | n_slices = s->cluster_size / slice_size2; | |
2252 | ||
2253 | if (!is_active_l1) { | |
2254 | /* inactive L2 tables require a buffer to be stored in when loading | |
2255 | * them from disk */ | |
2256 | l2_slice = qemu_try_blockalign(bs->file->bs, slice_size2); | |
2257 | if (l2_slice == NULL) { | |
2258 | return -ENOMEM; | |
2259 | } | |
2260 | } | |
2261 | ||
2262 | for (i = 0; i < l1_size; i++) { | |
2263 | uint64_t l2_offset = l1_table[i] & L1E_OFFSET_MASK; | |
2264 | uint64_t l2_refcount; | |
2265 | ||
2266 | if (!l2_offset) { | |
2267 | /* unallocated */ | |
2268 | (*visited_l1_entries)++; | |
2269 | if (status_cb) { | |
2270 | status_cb(bs, *visited_l1_entries, l1_entries, cb_opaque); | |
2271 | } | |
2272 | continue; | |
2273 | } | |
2274 | ||
2275 | if (offset_into_cluster(s, l2_offset)) { | |
2276 | qcow2_signal_corruption(bs, true, -1, -1, "L2 table offset %#" | |
2277 | PRIx64 " unaligned (L1 index: %#x)", | |
2278 | l2_offset, i); | |
2279 | ret = -EIO; | |
2280 | goto fail; | |
2281 | } | |
2282 | ||
2283 | ret = qcow2_get_refcount(bs, l2_offset >> s->cluster_bits, | |
2284 | &l2_refcount); | |
2285 | if (ret < 0) { | |
2286 | goto fail; | |
2287 | } | |
2288 | ||
2289 | for (slice = 0; slice < n_slices; slice++) { | |
2290 | uint64_t slice_offset = l2_offset + slice * slice_size2; | |
2291 | bool l2_dirty = false; | |
2292 | if (is_active_l1) { | |
2293 | /* get active L2 tables from cache */ | |
2294 | ret = qcow2_cache_get(bs, s->l2_table_cache, slice_offset, | |
2295 | (void **)&l2_slice); | |
2296 | } else { | |
2297 | /* load inactive L2 tables from disk */ | |
2298 | ret = bdrv_pread(bs->file, slice_offset, slice_size2, | |
2299 | l2_slice, 0); | |
2300 | } | |
2301 | if (ret < 0) { | |
2302 | goto fail; | |
2303 | } | |
2304 | ||
2305 | for (j = 0; j < s->l2_slice_size; j++) { | |
2306 | uint64_t l2_entry = get_l2_entry(s, l2_slice, j); | |
2307 | int64_t offset = l2_entry & L2E_OFFSET_MASK; | |
2308 | QCow2ClusterType cluster_type = | |
2309 | qcow2_get_cluster_type(bs, l2_entry); | |
2310 | ||
2311 | if (cluster_type != QCOW2_CLUSTER_ZERO_PLAIN && | |
2312 | cluster_type != QCOW2_CLUSTER_ZERO_ALLOC) { | |
2313 | continue; | |
2314 | } | |
2315 | ||
2316 | if (cluster_type == QCOW2_CLUSTER_ZERO_PLAIN) { | |
2317 | if (!bs->backing) { | |
2318 | /* | |
2319 | * not backed; therefore we can simply deallocate the | |
2320 | * cluster. No need to call set_l2_bitmap(), this | |
2321 | * function doesn't support images with subclusters. | |
2322 | */ | |
2323 | set_l2_entry(s, l2_slice, j, 0); | |
2324 | l2_dirty = true; | |
2325 | continue; | |
2326 | } | |
2327 | ||
2328 | offset = qcow2_alloc_clusters(bs, s->cluster_size); | |
2329 | if (offset < 0) { | |
2330 | ret = offset; | |
2331 | goto fail; | |
2332 | } | |
2333 | ||
2334 | /* The offset must fit in the offset field */ | |
2335 | assert((offset & L2E_OFFSET_MASK) == offset); | |
2336 | ||
2337 | if (l2_refcount > 1) { | |
2338 | /* For shared L2 tables, set the refcount accordingly | |
2339 | * (it is already 1 and needs to be l2_refcount) */ | |
2340 | ret = qcow2_update_cluster_refcount( | |
2341 | bs, offset >> s->cluster_bits, | |
2342 | refcount_diff(1, l2_refcount), false, | |
2343 | QCOW2_DISCARD_OTHER); | |
2344 | if (ret < 0) { | |
2345 | qcow2_free_clusters(bs, offset, s->cluster_size, | |
2346 | QCOW2_DISCARD_OTHER); | |
2347 | goto fail; | |
2348 | } | |
2349 | } | |
2350 | } | |
2351 | ||
2352 | if (offset_into_cluster(s, offset)) { | |
2353 | int l2_index = slice * s->l2_slice_size + j; | |
2354 | qcow2_signal_corruption( | |
2355 | bs, true, -1, -1, | |
2356 | "Cluster allocation offset " | |
2357 | "%#" PRIx64 " unaligned (L2 offset: %#" | |
2358 | PRIx64 ", L2 index: %#x)", offset, | |
2359 | l2_offset, l2_index); | |
2360 | if (cluster_type == QCOW2_CLUSTER_ZERO_PLAIN) { | |
2361 | qcow2_free_clusters(bs, offset, s->cluster_size, | |
2362 | QCOW2_DISCARD_ALWAYS); | |
2363 | } | |
2364 | ret = -EIO; | |
2365 | goto fail; | |
2366 | } | |
2367 | ||
2368 | ret = qcow2_pre_write_overlap_check(bs, 0, offset, | |
2369 | s->cluster_size, true); | |
2370 | if (ret < 0) { | |
2371 | if (cluster_type == QCOW2_CLUSTER_ZERO_PLAIN) { | |
2372 | qcow2_free_clusters(bs, offset, s->cluster_size, | |
2373 | QCOW2_DISCARD_ALWAYS); | |
2374 | } | |
2375 | goto fail; | |
2376 | } | |
2377 | ||
2378 | ret = bdrv_pwrite_zeroes(s->data_file, offset, | |
2379 | s->cluster_size, 0); | |
2380 | if (ret < 0) { | |
2381 | if (cluster_type == QCOW2_CLUSTER_ZERO_PLAIN) { | |
2382 | qcow2_free_clusters(bs, offset, s->cluster_size, | |
2383 | QCOW2_DISCARD_ALWAYS); | |
2384 | } | |
2385 | goto fail; | |
2386 | } | |
2387 | ||
2388 | if (l2_refcount == 1) { | |
2389 | set_l2_entry(s, l2_slice, j, offset | QCOW_OFLAG_COPIED); | |
2390 | } else { | |
2391 | set_l2_entry(s, l2_slice, j, offset); | |
2392 | } | |
2393 | /* | |
2394 | * No need to call set_l2_bitmap() after set_l2_entry() because | |
2395 | * this function doesn't support images with subclusters. | |
2396 | */ | |
2397 | l2_dirty = true; | |
2398 | } | |
2399 | ||
2400 | if (is_active_l1) { | |
2401 | if (l2_dirty) { | |
2402 | qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_slice); | |
2403 | qcow2_cache_depends_on_flush(s->l2_table_cache); | |
2404 | } | |
2405 | qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice); | |
2406 | } else { | |
2407 | if (l2_dirty) { | |
2408 | ret = qcow2_pre_write_overlap_check( | |
2409 | bs, QCOW2_OL_INACTIVE_L2 | QCOW2_OL_ACTIVE_L2, | |
2410 | slice_offset, slice_size2, false); | |
2411 | if (ret < 0) { | |
2412 | goto fail; | |
2413 | } | |
2414 | ||
2415 | ret = bdrv_pwrite(bs->file, slice_offset, slice_size2, | |
2416 | l2_slice, 0); | |
2417 | if (ret < 0) { | |
2418 | goto fail; | |
2419 | } | |
2420 | } | |
2421 | } | |
2422 | } | |
2423 | ||
2424 | (*visited_l1_entries)++; | |
2425 | if (status_cb) { | |
2426 | status_cb(bs, *visited_l1_entries, l1_entries, cb_opaque); | |
2427 | } | |
2428 | } | |
2429 | ||
2430 | ret = 0; | |
2431 | ||
2432 | fail: | |
2433 | if (l2_slice) { | |
2434 | if (!is_active_l1) { | |
2435 | qemu_vfree(l2_slice); | |
2436 | } else { | |
2437 | qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice); | |
2438 | } | |
2439 | } | |
2440 | return ret; | |
2441 | } | |
2442 | ||
2443 | /* | |
2444 | * For backed images, expands all zero clusters on the image. For non-backed | |
2445 | * images, deallocates all non-pre-allocated zero clusters (and claims the | |
2446 | * allocation for pre-allocated ones). This is important for downgrading to a | |
2447 | * qcow2 version which doesn't yet support metadata zero clusters. | |
2448 | */ | |
2449 | int qcow2_expand_zero_clusters(BlockDriverState *bs, | |
2450 | BlockDriverAmendStatusCB *status_cb, | |
2451 | void *cb_opaque) | |
2452 | { | |
2453 | BDRVQcow2State *s = bs->opaque; | |
2454 | uint64_t *l1_table = NULL; | |
2455 | int64_t l1_entries = 0, visited_l1_entries = 0; | |
2456 | int ret; | |
2457 | int i, j; | |
2458 | ||
2459 | if (status_cb) { | |
2460 | l1_entries = s->l1_size; | |
2461 | for (i = 0; i < s->nb_snapshots; i++) { | |
2462 | l1_entries += s->snapshots[i].l1_size; | |
2463 | } | |
2464 | } | |
2465 | ||
2466 | ret = expand_zero_clusters_in_l1(bs, s->l1_table, s->l1_size, | |
2467 | &visited_l1_entries, l1_entries, | |
2468 | status_cb, cb_opaque); | |
2469 | if (ret < 0) { | |
2470 | goto fail; | |
2471 | } | |
2472 | ||
2473 | /* Inactive L1 tables may point to active L2 tables - therefore it is | |
2474 | * necessary to flush the L2 table cache before trying to access the L2 | |
2475 | * tables pointed to by inactive L1 entries (else we might try to expand | |
2476 | * zero clusters that have already been expanded); furthermore, it is also | |
2477 | * necessary to empty the L2 table cache, since it may contain tables which | |
2478 | * are now going to be modified directly on disk, bypassing the cache. | |
2479 | * qcow2_cache_empty() does both for us. */ | |
2480 | ret = qcow2_cache_empty(bs, s->l2_table_cache); | |
2481 | if (ret < 0) { | |
2482 | goto fail; | |
2483 | } | |
2484 | ||
2485 | for (i = 0; i < s->nb_snapshots; i++) { | |
2486 | int l1_size2; | |
2487 | uint64_t *new_l1_table; | |
2488 | Error *local_err = NULL; | |
2489 | ||
2490 | ret = qcow2_validate_table(bs, s->snapshots[i].l1_table_offset, | |
2491 | s->snapshots[i].l1_size, L1E_SIZE, | |
2492 | QCOW_MAX_L1_SIZE, "Snapshot L1 table", | |
2493 | &local_err); | |
2494 | if (ret < 0) { | |
2495 | error_report_err(local_err); | |
2496 | goto fail; | |
2497 | } | |
2498 | ||
2499 | l1_size2 = s->snapshots[i].l1_size * L1E_SIZE; | |
2500 | new_l1_table = g_try_realloc(l1_table, l1_size2); | |
2501 | ||
2502 | if (!new_l1_table) { | |
2503 | ret = -ENOMEM; | |
2504 | goto fail; | |
2505 | } | |
2506 | ||
2507 | l1_table = new_l1_table; | |
2508 | ||
2509 | ret = bdrv_pread(bs->file, s->snapshots[i].l1_table_offset, l1_size2, | |
2510 | l1_table, 0); | |
2511 | if (ret < 0) { | |
2512 | goto fail; | |
2513 | } | |
2514 | ||
2515 | for (j = 0; j < s->snapshots[i].l1_size; j++) { | |
2516 | be64_to_cpus(&l1_table[j]); | |
2517 | } | |
2518 | ||
2519 | ret = expand_zero_clusters_in_l1(bs, l1_table, s->snapshots[i].l1_size, | |
2520 | &visited_l1_entries, l1_entries, | |
2521 | status_cb, cb_opaque); | |
2522 | if (ret < 0) { | |
2523 | goto fail; | |
2524 | } | |
2525 | } | |
2526 | ||
2527 | ret = 0; | |
2528 | ||
2529 | fail: | |
2530 | g_free(l1_table); | |
2531 | return ret; | |
2532 | } | |
2533 | ||
2534 | void qcow2_parse_compressed_l2_entry(BlockDriverState *bs, uint64_t l2_entry, | |
2535 | uint64_t *coffset, int *csize) | |
2536 | { | |
2537 | BDRVQcow2State *s = bs->opaque; | |
2538 | int nb_csectors; | |
2539 | ||
2540 | assert(qcow2_get_cluster_type(bs, l2_entry) == QCOW2_CLUSTER_COMPRESSED); | |
2541 | ||
2542 | *coffset = l2_entry & s->cluster_offset_mask; | |
2543 | ||
2544 | nb_csectors = ((l2_entry >> s->csize_shift) & s->csize_mask) + 1; | |
2545 | *csize = nb_csectors * QCOW2_COMPRESSED_SECTOR_SIZE - | |
2546 | (*coffset & (QCOW2_COMPRESSED_SECTOR_SIZE - 1)); | |
2547 | } |