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49381094 KW |
1 | /* |
2 | * L2/refcount table cache for the QCOW2 format | |
3 | * | |
4 | * Copyright (c) 2010 Kevin Wolf <kwolf@redhat.com> | |
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 | ||
80c71a24 | 25 | #include "qemu/osdep.h" |
737e150e | 26 | #include "block/block_int.h" |
49381094 KW |
27 | #include "qemu-common.h" |
28 | #include "qcow2.h" | |
3cce16f4 | 29 | #include "trace.h" |
49381094 KW |
30 | |
31 | typedef struct Qcow2CachedTable { | |
2693310e | 32 | int64_t offset; |
2693310e AG |
33 | uint64_t lru_counter; |
34 | int ref; | |
909c260c | 35 | bool dirty; |
49381094 KW |
36 | } Qcow2CachedTable; |
37 | ||
38 | struct Qcow2Cache { | |
d1b4efe5 AG |
39 | Qcow2CachedTable *entries; |
40 | struct Qcow2Cache *depends; | |
bf595021 | 41 | int size; |
03019d73 | 42 | int table_size; |
3de0a294 | 43 | bool depends_on_flush; |
72e80b89 | 44 | void *table_array; |
2693310e | 45 | uint64_t lru_counter; |
279621c0 | 46 | uint64_t cache_clean_lru_counter; |
49381094 KW |
47 | }; |
48 | ||
72e80b89 AG |
49 | static inline void *qcow2_cache_get_table_addr(BlockDriverState *bs, |
50 | Qcow2Cache *c, int table) | |
51 | { | |
03019d73 | 52 | return (uint8_t *) c->table_array + (size_t) table * c->table_size; |
72e80b89 AG |
53 | } |
54 | ||
baf07d60 AG |
55 | static inline int qcow2_cache_get_table_idx(BlockDriverState *bs, |
56 | Qcow2Cache *c, void *table) | |
57 | { | |
baf07d60 | 58 | ptrdiff_t table_offset = (uint8_t *) table - (uint8_t *) c->table_array; |
03019d73 AG |
59 | int idx = table_offset / c->table_size; |
60 | assert(idx >= 0 && idx < c->size && table_offset % c->table_size == 0); | |
baf07d60 AG |
61 | return idx; |
62 | } | |
63 | ||
4efb1f7c HR |
64 | static inline const char *qcow2_cache_get_name(BDRVQcow2State *s, Qcow2Cache *c) |
65 | { | |
66 | if (c == s->refcount_block_cache) { | |
67 | return "refcount block"; | |
68 | } else if (c == s->l2_table_cache) { | |
69 | return "L2 table"; | |
70 | } else { | |
71 | /* Do not abort, because this is not critical */ | |
72 | return "unknown"; | |
73 | } | |
74 | } | |
75 | ||
355ee2d0 AG |
76 | static void qcow2_cache_table_release(BlockDriverState *bs, Qcow2Cache *c, |
77 | int i, int num_tables) | |
78 | { | |
2f2c8d6b AG |
79 | /* Using MADV_DONTNEED to discard memory is a Linux-specific feature */ |
80 | #ifdef CONFIG_LINUX | |
355ee2d0 AG |
81 | void *t = qcow2_cache_get_table_addr(bs, c, i); |
82 | int align = getpagesize(); | |
03019d73 | 83 | size_t mem_size = (size_t) c->table_size * num_tables; |
355ee2d0 AG |
84 | size_t offset = QEMU_ALIGN_UP((uintptr_t) t, align) - (uintptr_t) t; |
85 | size_t length = QEMU_ALIGN_DOWN(mem_size - offset, align); | |
08546bcf | 86 | if (mem_size > offset && length > 0) { |
2f2c8d6b | 87 | madvise((uint8_t *) t + offset, length, MADV_DONTNEED); |
355ee2d0 AG |
88 | } |
89 | #endif | |
90 | } | |
91 | ||
279621c0 AG |
92 | static inline bool can_clean_entry(Qcow2Cache *c, int i) |
93 | { | |
94 | Qcow2CachedTable *t = &c->entries[i]; | |
95 | return t->ref == 0 && !t->dirty && t->offset != 0 && | |
96 | t->lru_counter <= c->cache_clean_lru_counter; | |
97 | } | |
98 | ||
99 | void qcow2_cache_clean_unused(BlockDriverState *bs, Qcow2Cache *c) | |
100 | { | |
101 | int i = 0; | |
102 | while (i < c->size) { | |
103 | int to_clean = 0; | |
104 | ||
105 | /* Skip the entries that we don't need to clean */ | |
106 | while (i < c->size && !can_clean_entry(c, i)) { | |
107 | i++; | |
108 | } | |
109 | ||
110 | /* And count how many we can clean in a row */ | |
111 | while (i < c->size && can_clean_entry(c, i)) { | |
112 | c->entries[i].offset = 0; | |
113 | c->entries[i].lru_counter = 0; | |
114 | i++; | |
115 | to_clean++; | |
116 | } | |
117 | ||
118 | if (to_clean > 0) { | |
119 | qcow2_cache_table_release(bs, c, i - to_clean, to_clean); | |
120 | } | |
121 | } | |
122 | ||
123 | c->cache_clean_lru_counter = c->lru_counter; | |
124 | } | |
125 | ||
6af4e9ea | 126 | Qcow2Cache *qcow2_cache_create(BlockDriverState *bs, int num_tables) |
49381094 | 127 | { |
ff99129a | 128 | BDRVQcow2State *s = bs->opaque; |
49381094 | 129 | Qcow2Cache *c; |
49381094 | 130 | |
02004bd4 | 131 | c = g_new0(Qcow2Cache, 1); |
49381094 | 132 | c->size = num_tables; |
03019d73 | 133 | c->table_size = s->cluster_size; |
02004bd4 | 134 | c->entries = g_try_new0(Qcow2CachedTable, num_tables); |
9a4f4c31 | 135 | c->table_array = qemu_try_blockalign(bs->file->bs, |
03019d73 | 136 | (size_t) num_tables * c->table_size); |
72e80b89 AG |
137 | |
138 | if (!c->entries || !c->table_array) { | |
139 | qemu_vfree(c->table_array); | |
140 | g_free(c->entries); | |
141 | g_free(c); | |
142 | c = NULL; | |
49381094 KW |
143 | } |
144 | ||
145 | return c; | |
146 | } | |
147 | ||
d1b4efe5 | 148 | int qcow2_cache_destroy(BlockDriverState *bs, Qcow2Cache *c) |
49381094 KW |
149 | { |
150 | int i; | |
151 | ||
152 | for (i = 0; i < c->size; i++) { | |
153 | assert(c->entries[i].ref == 0); | |
49381094 KW |
154 | } |
155 | ||
72e80b89 | 156 | qemu_vfree(c->table_array); |
7267c094 AL |
157 | g_free(c->entries); |
158 | g_free(c); | |
49381094 KW |
159 | |
160 | return 0; | |
161 | } | |
162 | ||
163 | static int qcow2_cache_flush_dependency(BlockDriverState *bs, Qcow2Cache *c) | |
164 | { | |
165 | int ret; | |
166 | ||
167 | ret = qcow2_cache_flush(bs, c->depends); | |
168 | if (ret < 0) { | |
169 | return ret; | |
170 | } | |
171 | ||
172 | c->depends = NULL; | |
3de0a294 KW |
173 | c->depends_on_flush = false; |
174 | ||
49381094 KW |
175 | return 0; |
176 | } | |
177 | ||
178 | static int qcow2_cache_entry_flush(BlockDriverState *bs, Qcow2Cache *c, int i) | |
179 | { | |
ff99129a | 180 | BDRVQcow2State *s = bs->opaque; |
3de0a294 | 181 | int ret = 0; |
49381094 KW |
182 | |
183 | if (!c->entries[i].dirty || !c->entries[i].offset) { | |
184 | return 0; | |
185 | } | |
186 | ||
3cce16f4 KW |
187 | trace_qcow2_cache_entry_flush(qemu_coroutine_self(), |
188 | c == s->l2_table_cache, i); | |
189 | ||
49381094 KW |
190 | if (c->depends) { |
191 | ret = qcow2_cache_flush_dependency(bs, c); | |
3de0a294 | 192 | } else if (c->depends_on_flush) { |
9a4f4c31 | 193 | ret = bdrv_flush(bs->file->bs); |
3de0a294 KW |
194 | if (ret >= 0) { |
195 | c->depends_on_flush = false; | |
49381094 KW |
196 | } |
197 | } | |
198 | ||
3de0a294 KW |
199 | if (ret < 0) { |
200 | return ret; | |
201 | } | |
202 | ||
cf93980e | 203 | if (c == s->refcount_block_cache) { |
231bb267 | 204 | ret = qcow2_pre_write_overlap_check(bs, QCOW2_OL_REFCOUNT_BLOCK, |
03019d73 | 205 | c->entries[i].offset, c->table_size); |
cf93980e | 206 | } else if (c == s->l2_table_cache) { |
231bb267 | 207 | ret = qcow2_pre_write_overlap_check(bs, QCOW2_OL_ACTIVE_L2, |
03019d73 | 208 | c->entries[i].offset, c->table_size); |
cf93980e | 209 | } else { |
231bb267 | 210 | ret = qcow2_pre_write_overlap_check(bs, 0, |
03019d73 | 211 | c->entries[i].offset, c->table_size); |
cf93980e HR |
212 | } |
213 | ||
214 | if (ret < 0) { | |
215 | return ret; | |
216 | } | |
217 | ||
29c1a730 KW |
218 | if (c == s->refcount_block_cache) { |
219 | BLKDBG_EVENT(bs->file, BLKDBG_REFBLOCK_UPDATE_PART); | |
220 | } else if (c == s->l2_table_cache) { | |
221 | BLKDBG_EVENT(bs->file, BLKDBG_L2_UPDATE); | |
222 | } | |
223 | ||
d9ca2ea2 | 224 | ret = bdrv_pwrite(bs->file, c->entries[i].offset, |
03019d73 | 225 | qcow2_cache_get_table_addr(bs, c, i), c->table_size); |
49381094 KW |
226 | if (ret < 0) { |
227 | return ret; | |
228 | } | |
229 | ||
230 | c->entries[i].dirty = false; | |
231 | ||
232 | return 0; | |
233 | } | |
234 | ||
f3c3b87d | 235 | int qcow2_cache_write(BlockDriverState *bs, Qcow2Cache *c) |
49381094 | 236 | { |
ff99129a | 237 | BDRVQcow2State *s = bs->opaque; |
49381094 KW |
238 | int result = 0; |
239 | int ret; | |
240 | int i; | |
241 | ||
3cce16f4 KW |
242 | trace_qcow2_cache_flush(qemu_coroutine_self(), c == s->l2_table_cache); |
243 | ||
49381094 KW |
244 | for (i = 0; i < c->size; i++) { |
245 | ret = qcow2_cache_entry_flush(bs, c, i); | |
246 | if (ret < 0 && result != -ENOSPC) { | |
247 | result = ret; | |
248 | } | |
249 | } | |
250 | ||
f3c3b87d DL |
251 | return result; |
252 | } | |
253 | ||
254 | int qcow2_cache_flush(BlockDriverState *bs, Qcow2Cache *c) | |
255 | { | |
256 | int result = qcow2_cache_write(bs, c); | |
257 | ||
49381094 | 258 | if (result == 0) { |
f3c3b87d | 259 | int ret = bdrv_flush(bs->file->bs); |
49381094 KW |
260 | if (ret < 0) { |
261 | result = ret; | |
262 | } | |
263 | } | |
264 | ||
265 | return result; | |
266 | } | |
267 | ||
268 | int qcow2_cache_set_dependency(BlockDriverState *bs, Qcow2Cache *c, | |
269 | Qcow2Cache *dependency) | |
270 | { | |
271 | int ret; | |
272 | ||
273 | if (dependency->depends) { | |
274 | ret = qcow2_cache_flush_dependency(bs, dependency); | |
275 | if (ret < 0) { | |
276 | return ret; | |
277 | } | |
278 | } | |
279 | ||
280 | if (c->depends && (c->depends != dependency)) { | |
281 | ret = qcow2_cache_flush_dependency(bs, c); | |
282 | if (ret < 0) { | |
283 | return ret; | |
284 | } | |
285 | } | |
286 | ||
287 | c->depends = dependency; | |
288 | return 0; | |
289 | } | |
290 | ||
3de0a294 KW |
291 | void qcow2_cache_depends_on_flush(Qcow2Cache *c) |
292 | { | |
293 | c->depends_on_flush = true; | |
294 | } | |
295 | ||
e7108fea HR |
296 | int qcow2_cache_empty(BlockDriverState *bs, Qcow2Cache *c) |
297 | { | |
298 | int ret, i; | |
299 | ||
300 | ret = qcow2_cache_flush(bs, c); | |
301 | if (ret < 0) { | |
302 | return ret; | |
303 | } | |
304 | ||
305 | for (i = 0; i < c->size; i++) { | |
306 | assert(c->entries[i].ref == 0); | |
307 | c->entries[i].offset = 0; | |
2693310e | 308 | c->entries[i].lru_counter = 0; |
e7108fea HR |
309 | } |
310 | ||
355ee2d0 AG |
311 | qcow2_cache_table_release(bs, c, 0, c->size); |
312 | ||
2693310e AG |
313 | c->lru_counter = 0; |
314 | ||
e7108fea HR |
315 | return 0; |
316 | } | |
317 | ||
49381094 KW |
318 | static int qcow2_cache_do_get(BlockDriverState *bs, Qcow2Cache *c, |
319 | uint64_t offset, void **table, bool read_from_disk) | |
320 | { | |
ff99129a | 321 | BDRVQcow2State *s = bs->opaque; |
49381094 KW |
322 | int i; |
323 | int ret; | |
812e4082 | 324 | int lookup_index; |
fdfbca82 AG |
325 | uint64_t min_lru_counter = UINT64_MAX; |
326 | int min_lru_index = -1; | |
49381094 | 327 | |
4efb1f7c HR |
328 | assert(offset != 0); |
329 | ||
3cce16f4 KW |
330 | trace_qcow2_cache_get(qemu_coroutine_self(), c == s->l2_table_cache, |
331 | offset, read_from_disk); | |
332 | ||
03019d73 | 333 | if (!QEMU_IS_ALIGNED(offset, c->table_size)) { |
4efb1f7c HR |
334 | qcow2_signal_corruption(bs, true, -1, -1, "Cannot get entry from %s " |
335 | "cache: Offset %#" PRIx64 " is unaligned", | |
336 | qcow2_cache_get_name(s, c), offset); | |
337 | return -EIO; | |
338 | } | |
339 | ||
49381094 | 340 | /* Check if the table is already cached */ |
03019d73 | 341 | i = lookup_index = (offset / c->table_size * 4) % c->size; |
812e4082 | 342 | do { |
fdfbca82 AG |
343 | const Qcow2CachedTable *t = &c->entries[i]; |
344 | if (t->offset == offset) { | |
49381094 KW |
345 | goto found; |
346 | } | |
fdfbca82 AG |
347 | if (t->ref == 0 && t->lru_counter < min_lru_counter) { |
348 | min_lru_counter = t->lru_counter; | |
349 | min_lru_index = i; | |
350 | } | |
812e4082 AG |
351 | if (++i == c->size) { |
352 | i = 0; | |
353 | } | |
354 | } while (i != lookup_index); | |
fdfbca82 AG |
355 | |
356 | if (min_lru_index == -1) { | |
357 | /* This can't happen in current synchronous code, but leave the check | |
358 | * here as a reminder for whoever starts using AIO with the cache */ | |
359 | abort(); | |
49381094 KW |
360 | } |
361 | ||
fdfbca82 AG |
362 | /* Cache miss: write a table back and replace it */ |
363 | i = min_lru_index; | |
3cce16f4 KW |
364 | trace_qcow2_cache_get_replace_entry(qemu_coroutine_self(), |
365 | c == s->l2_table_cache, i); | |
49381094 KW |
366 | |
367 | ret = qcow2_cache_entry_flush(bs, c, i); | |
368 | if (ret < 0) { | |
369 | return ret; | |
370 | } | |
371 | ||
3cce16f4 KW |
372 | trace_qcow2_cache_get_read(qemu_coroutine_self(), |
373 | c == s->l2_table_cache, i); | |
49381094 KW |
374 | c->entries[i].offset = 0; |
375 | if (read_from_disk) { | |
29c1a730 KW |
376 | if (c == s->l2_table_cache) { |
377 | BLKDBG_EVENT(bs->file, BLKDBG_L2_LOAD); | |
378 | } | |
379 | ||
cf2ab8fc | 380 | ret = bdrv_pread(bs->file, offset, |
9a4f4c31 | 381 | qcow2_cache_get_table_addr(bs, c, i), |
03019d73 | 382 | c->table_size); |
49381094 KW |
383 | if (ret < 0) { |
384 | return ret; | |
385 | } | |
386 | } | |
387 | ||
49381094 KW |
388 | c->entries[i].offset = offset; |
389 | ||
390 | /* And return the right table */ | |
391 | found: | |
49381094 | 392 | c->entries[i].ref++; |
72e80b89 | 393 | *table = qcow2_cache_get_table_addr(bs, c, i); |
3cce16f4 KW |
394 | |
395 | trace_qcow2_cache_get_done(qemu_coroutine_self(), | |
396 | c == s->l2_table_cache, i); | |
397 | ||
49381094 KW |
398 | return 0; |
399 | } | |
400 | ||
401 | int qcow2_cache_get(BlockDriverState *bs, Qcow2Cache *c, uint64_t offset, | |
402 | void **table) | |
403 | { | |
404 | return qcow2_cache_do_get(bs, c, offset, table, true); | |
405 | } | |
406 | ||
407 | int qcow2_cache_get_empty(BlockDriverState *bs, Qcow2Cache *c, uint64_t offset, | |
408 | void **table) | |
409 | { | |
410 | return qcow2_cache_do_get(bs, c, offset, table, false); | |
411 | } | |
412 | ||
a3f1afb4 | 413 | void qcow2_cache_put(BlockDriverState *bs, Qcow2Cache *c, void **table) |
49381094 | 414 | { |
baf07d60 | 415 | int i = qcow2_cache_get_table_idx(bs, c, *table); |
49381094 | 416 | |
49381094 KW |
417 | c->entries[i].ref--; |
418 | *table = NULL; | |
419 | ||
2693310e AG |
420 | if (c->entries[i].ref == 0) { |
421 | c->entries[i].lru_counter = ++c->lru_counter; | |
422 | } | |
423 | ||
49381094 | 424 | assert(c->entries[i].ref >= 0); |
49381094 KW |
425 | } |
426 | ||
72e80b89 AG |
427 | void qcow2_cache_entry_mark_dirty(BlockDriverState *bs, Qcow2Cache *c, |
428 | void *table) | |
49381094 | 429 | { |
baf07d60 AG |
430 | int i = qcow2_cache_get_table_idx(bs, c, table); |
431 | assert(c->entries[i].offset != 0); | |
49381094 KW |
432 | c->entries[i].dirty = true; |
433 | } | |
f71c08ea PB |
434 | |
435 | void *qcow2_cache_is_table_offset(BlockDriverState *bs, Qcow2Cache *c, | |
436 | uint64_t offset) | |
437 | { | |
438 | int i; | |
439 | ||
440 | for (i = 0; i < c->size; i++) { | |
441 | if (c->entries[i].offset == offset) { | |
442 | return qcow2_cache_get_table_addr(bs, c, i); | |
443 | } | |
444 | } | |
445 | return NULL; | |
446 | } | |
447 | ||
448 | void qcow2_cache_discard(BlockDriverState *bs, Qcow2Cache *c, void *table) | |
449 | { | |
450 | int i = qcow2_cache_get_table_idx(bs, c, table); | |
451 | ||
452 | assert(c->entries[i].ref == 0); | |
453 | ||
454 | c->entries[i].offset = 0; | |
455 | c->entries[i].lru_counter = 0; | |
456 | c->entries[i].dirty = false; | |
457 | ||
458 | qcow2_cache_table_release(bs, c, i, 1); | |
459 | } |