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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; |
3de0a294 | 42 | bool depends_on_flush; |
72e80b89 | 43 | void *table_array; |
2693310e | 44 | uint64_t lru_counter; |
279621c0 | 45 | uint64_t cache_clean_lru_counter; |
49381094 KW |
46 | }; |
47 | ||
72e80b89 AG |
48 | static inline void *qcow2_cache_get_table_addr(BlockDriverState *bs, |
49 | Qcow2Cache *c, int table) | |
50 | { | |
ff99129a | 51 | BDRVQcow2State *s = bs->opaque; |
72e80b89 AG |
52 | return (uint8_t *) c->table_array + (size_t) table * s->cluster_size; |
53 | } | |
54 | ||
baf07d60 AG |
55 | static inline int qcow2_cache_get_table_idx(BlockDriverState *bs, |
56 | Qcow2Cache *c, void *table) | |
57 | { | |
ff99129a | 58 | BDRVQcow2State *s = bs->opaque; |
baf07d60 AG |
59 | ptrdiff_t table_offset = (uint8_t *) table - (uint8_t *) c->table_array; |
60 | int idx = table_offset / s->cluster_size; | |
61 | assert(idx >= 0 && idx < c->size && table_offset % s->cluster_size == 0); | |
62 | return idx; | |
63 | } | |
64 | ||
4efb1f7c HR |
65 | static inline const char *qcow2_cache_get_name(BDRVQcow2State *s, Qcow2Cache *c) |
66 | { | |
67 | if (c == s->refcount_block_cache) { | |
68 | return "refcount block"; | |
69 | } else if (c == s->l2_table_cache) { | |
70 | return "L2 table"; | |
71 | } else { | |
72 | /* Do not abort, because this is not critical */ | |
73 | return "unknown"; | |
74 | } | |
75 | } | |
76 | ||
355ee2d0 AG |
77 | static void qcow2_cache_table_release(BlockDriverState *bs, Qcow2Cache *c, |
78 | int i, int num_tables) | |
79 | { | |
2f2c8d6b AG |
80 | /* Using MADV_DONTNEED to discard memory is a Linux-specific feature */ |
81 | #ifdef CONFIG_LINUX | |
ff99129a | 82 | BDRVQcow2State *s = bs->opaque; |
355ee2d0 AG |
83 | void *t = qcow2_cache_get_table_addr(bs, c, i); |
84 | int align = getpagesize(); | |
85 | size_t mem_size = (size_t) s->cluster_size * num_tables; | |
86 | size_t offset = QEMU_ALIGN_UP((uintptr_t) t, align) - (uintptr_t) t; | |
87 | size_t length = QEMU_ALIGN_DOWN(mem_size - offset, align); | |
08546bcf | 88 | if (mem_size > offset && length > 0) { |
2f2c8d6b | 89 | madvise((uint8_t *) t + offset, length, MADV_DONTNEED); |
355ee2d0 AG |
90 | } |
91 | #endif | |
92 | } | |
93 | ||
279621c0 AG |
94 | static inline bool can_clean_entry(Qcow2Cache *c, int i) |
95 | { | |
96 | Qcow2CachedTable *t = &c->entries[i]; | |
97 | return t->ref == 0 && !t->dirty && t->offset != 0 && | |
98 | t->lru_counter <= c->cache_clean_lru_counter; | |
99 | } | |
100 | ||
101 | void qcow2_cache_clean_unused(BlockDriverState *bs, Qcow2Cache *c) | |
102 | { | |
103 | int i = 0; | |
104 | while (i < c->size) { | |
105 | int to_clean = 0; | |
106 | ||
107 | /* Skip the entries that we don't need to clean */ | |
108 | while (i < c->size && !can_clean_entry(c, i)) { | |
109 | i++; | |
110 | } | |
111 | ||
112 | /* And count how many we can clean in a row */ | |
113 | while (i < c->size && can_clean_entry(c, i)) { | |
114 | c->entries[i].offset = 0; | |
115 | c->entries[i].lru_counter = 0; | |
116 | i++; | |
117 | to_clean++; | |
118 | } | |
119 | ||
120 | if (to_clean > 0) { | |
121 | qcow2_cache_table_release(bs, c, i - to_clean, to_clean); | |
122 | } | |
123 | } | |
124 | ||
125 | c->cache_clean_lru_counter = c->lru_counter; | |
126 | } | |
127 | ||
6af4e9ea | 128 | Qcow2Cache *qcow2_cache_create(BlockDriverState *bs, int num_tables) |
49381094 | 129 | { |
ff99129a | 130 | BDRVQcow2State *s = bs->opaque; |
49381094 | 131 | Qcow2Cache *c; |
49381094 | 132 | |
02004bd4 | 133 | c = g_new0(Qcow2Cache, 1); |
49381094 | 134 | c->size = num_tables; |
02004bd4 | 135 | c->entries = g_try_new0(Qcow2CachedTable, num_tables); |
9a4f4c31 | 136 | c->table_array = qemu_try_blockalign(bs->file->bs, |
72e80b89 AG |
137 | (size_t) num_tables * s->cluster_size); |
138 | ||
139 | if (!c->entries || !c->table_array) { | |
140 | qemu_vfree(c->table_array); | |
141 | g_free(c->entries); | |
142 | g_free(c); | |
143 | c = NULL; | |
49381094 KW |
144 | } |
145 | ||
146 | return c; | |
147 | } | |
148 | ||
d1b4efe5 | 149 | int qcow2_cache_destroy(BlockDriverState *bs, Qcow2Cache *c) |
49381094 KW |
150 | { |
151 | int i; | |
152 | ||
153 | for (i = 0; i < c->size; i++) { | |
154 | assert(c->entries[i].ref == 0); | |
49381094 KW |
155 | } |
156 | ||
72e80b89 | 157 | qemu_vfree(c->table_array); |
7267c094 AL |
158 | g_free(c->entries); |
159 | g_free(c); | |
49381094 KW |
160 | |
161 | return 0; | |
162 | } | |
163 | ||
164 | static int qcow2_cache_flush_dependency(BlockDriverState *bs, Qcow2Cache *c) | |
165 | { | |
166 | int ret; | |
167 | ||
168 | ret = qcow2_cache_flush(bs, c->depends); | |
169 | if (ret < 0) { | |
170 | return ret; | |
171 | } | |
172 | ||
173 | c->depends = NULL; | |
3de0a294 KW |
174 | c->depends_on_flush = false; |
175 | ||
49381094 KW |
176 | return 0; |
177 | } | |
178 | ||
179 | static int qcow2_cache_entry_flush(BlockDriverState *bs, Qcow2Cache *c, int i) | |
180 | { | |
ff99129a | 181 | BDRVQcow2State *s = bs->opaque; |
3de0a294 | 182 | int ret = 0; |
49381094 KW |
183 | |
184 | if (!c->entries[i].dirty || !c->entries[i].offset) { | |
185 | return 0; | |
186 | } | |
187 | ||
3cce16f4 KW |
188 | trace_qcow2_cache_entry_flush(qemu_coroutine_self(), |
189 | c == s->l2_table_cache, i); | |
190 | ||
49381094 KW |
191 | if (c->depends) { |
192 | ret = qcow2_cache_flush_dependency(bs, c); | |
3de0a294 | 193 | } else if (c->depends_on_flush) { |
9a4f4c31 | 194 | ret = bdrv_flush(bs->file->bs); |
3de0a294 KW |
195 | if (ret >= 0) { |
196 | c->depends_on_flush = false; | |
49381094 KW |
197 | } |
198 | } | |
199 | ||
3de0a294 KW |
200 | if (ret < 0) { |
201 | return ret; | |
202 | } | |
203 | ||
cf93980e | 204 | if (c == s->refcount_block_cache) { |
231bb267 | 205 | ret = qcow2_pre_write_overlap_check(bs, QCOW2_OL_REFCOUNT_BLOCK, |
cf93980e HR |
206 | c->entries[i].offset, s->cluster_size); |
207 | } else if (c == s->l2_table_cache) { | |
231bb267 | 208 | ret = qcow2_pre_write_overlap_check(bs, QCOW2_OL_ACTIVE_L2, |
cf93980e HR |
209 | c->entries[i].offset, s->cluster_size); |
210 | } else { | |
231bb267 | 211 | ret = qcow2_pre_write_overlap_check(bs, 0, |
cf93980e HR |
212 | c->entries[i].offset, s->cluster_size); |
213 | } | |
214 | ||
215 | if (ret < 0) { | |
216 | return ret; | |
217 | } | |
218 | ||
29c1a730 KW |
219 | if (c == s->refcount_block_cache) { |
220 | BLKDBG_EVENT(bs->file, BLKDBG_REFBLOCK_UPDATE_PART); | |
221 | } else if (c == s->l2_table_cache) { | |
222 | BLKDBG_EVENT(bs->file, BLKDBG_L2_UPDATE); | |
223 | } | |
224 | ||
d9ca2ea2 | 225 | ret = bdrv_pwrite(bs->file, c->entries[i].offset, |
72e80b89 | 226 | qcow2_cache_get_table_addr(bs, c, i), s->cluster_size); |
49381094 KW |
227 | if (ret < 0) { |
228 | return ret; | |
229 | } | |
230 | ||
231 | c->entries[i].dirty = false; | |
232 | ||
233 | return 0; | |
234 | } | |
235 | ||
f3c3b87d | 236 | int qcow2_cache_write(BlockDriverState *bs, Qcow2Cache *c) |
49381094 | 237 | { |
ff99129a | 238 | BDRVQcow2State *s = bs->opaque; |
49381094 KW |
239 | int result = 0; |
240 | int ret; | |
241 | int i; | |
242 | ||
3cce16f4 KW |
243 | trace_qcow2_cache_flush(qemu_coroutine_self(), c == s->l2_table_cache); |
244 | ||
49381094 KW |
245 | for (i = 0; i < c->size; i++) { |
246 | ret = qcow2_cache_entry_flush(bs, c, i); | |
247 | if (ret < 0 && result != -ENOSPC) { | |
248 | result = ret; | |
249 | } | |
250 | } | |
251 | ||
f3c3b87d DL |
252 | return result; |
253 | } | |
254 | ||
255 | int qcow2_cache_flush(BlockDriverState *bs, Qcow2Cache *c) | |
256 | { | |
257 | int result = qcow2_cache_write(bs, c); | |
258 | ||
49381094 | 259 | if (result == 0) { |
f3c3b87d | 260 | int ret = bdrv_flush(bs->file->bs); |
49381094 KW |
261 | if (ret < 0) { |
262 | result = ret; | |
263 | } | |
264 | } | |
265 | ||
266 | return result; | |
267 | } | |
268 | ||
269 | int qcow2_cache_set_dependency(BlockDriverState *bs, Qcow2Cache *c, | |
270 | Qcow2Cache *dependency) | |
271 | { | |
272 | int ret; | |
273 | ||
274 | if (dependency->depends) { | |
275 | ret = qcow2_cache_flush_dependency(bs, dependency); | |
276 | if (ret < 0) { | |
277 | return ret; | |
278 | } | |
279 | } | |
280 | ||
281 | if (c->depends && (c->depends != dependency)) { | |
282 | ret = qcow2_cache_flush_dependency(bs, c); | |
283 | if (ret < 0) { | |
284 | return ret; | |
285 | } | |
286 | } | |
287 | ||
288 | c->depends = dependency; | |
289 | return 0; | |
290 | } | |
291 | ||
3de0a294 KW |
292 | void qcow2_cache_depends_on_flush(Qcow2Cache *c) |
293 | { | |
294 | c->depends_on_flush = true; | |
295 | } | |
296 | ||
e7108fea HR |
297 | int qcow2_cache_empty(BlockDriverState *bs, Qcow2Cache *c) |
298 | { | |
299 | int ret, i; | |
300 | ||
301 | ret = qcow2_cache_flush(bs, c); | |
302 | if (ret < 0) { | |
303 | return ret; | |
304 | } | |
305 | ||
306 | for (i = 0; i < c->size; i++) { | |
307 | assert(c->entries[i].ref == 0); | |
308 | c->entries[i].offset = 0; | |
2693310e | 309 | c->entries[i].lru_counter = 0; |
e7108fea HR |
310 | } |
311 | ||
355ee2d0 AG |
312 | qcow2_cache_table_release(bs, c, 0, c->size); |
313 | ||
2693310e AG |
314 | c->lru_counter = 0; |
315 | ||
e7108fea HR |
316 | return 0; |
317 | } | |
318 | ||
49381094 KW |
319 | static int qcow2_cache_do_get(BlockDriverState *bs, Qcow2Cache *c, |
320 | uint64_t offset, void **table, bool read_from_disk) | |
321 | { | |
ff99129a | 322 | BDRVQcow2State *s = bs->opaque; |
49381094 KW |
323 | int i; |
324 | int ret; | |
812e4082 | 325 | int lookup_index; |
fdfbca82 AG |
326 | uint64_t min_lru_counter = UINT64_MAX; |
327 | int min_lru_index = -1; | |
49381094 | 328 | |
4efb1f7c HR |
329 | assert(offset != 0); |
330 | ||
3cce16f4 KW |
331 | trace_qcow2_cache_get(qemu_coroutine_self(), c == s->l2_table_cache, |
332 | offset, read_from_disk); | |
333 | ||
4efb1f7c HR |
334 | if (offset_into_cluster(s, offset)) { |
335 | qcow2_signal_corruption(bs, true, -1, -1, "Cannot get entry from %s " | |
336 | "cache: Offset %#" PRIx64 " is unaligned", | |
337 | qcow2_cache_get_name(s, c), offset); | |
338 | return -EIO; | |
339 | } | |
340 | ||
49381094 | 341 | /* Check if the table is already cached */ |
812e4082 AG |
342 | i = lookup_index = (offset / s->cluster_size * 4) % c->size; |
343 | do { | |
fdfbca82 AG |
344 | const Qcow2CachedTable *t = &c->entries[i]; |
345 | if (t->offset == offset) { | |
49381094 KW |
346 | goto found; |
347 | } | |
fdfbca82 AG |
348 | if (t->ref == 0 && t->lru_counter < min_lru_counter) { |
349 | min_lru_counter = t->lru_counter; | |
350 | min_lru_index = i; | |
351 | } | |
812e4082 AG |
352 | if (++i == c->size) { |
353 | i = 0; | |
354 | } | |
355 | } while (i != lookup_index); | |
fdfbca82 AG |
356 | |
357 | if (min_lru_index == -1) { | |
358 | /* This can't happen in current synchronous code, but leave the check | |
359 | * here as a reminder for whoever starts using AIO with the cache */ | |
360 | abort(); | |
49381094 KW |
361 | } |
362 | ||
fdfbca82 AG |
363 | /* Cache miss: write a table back and replace it */ |
364 | i = min_lru_index; | |
3cce16f4 KW |
365 | trace_qcow2_cache_get_replace_entry(qemu_coroutine_self(), |
366 | c == s->l2_table_cache, i); | |
49381094 KW |
367 | |
368 | ret = qcow2_cache_entry_flush(bs, c, i); | |
369 | if (ret < 0) { | |
370 | return ret; | |
371 | } | |
372 | ||
3cce16f4 KW |
373 | trace_qcow2_cache_get_read(qemu_coroutine_self(), |
374 | c == s->l2_table_cache, i); | |
49381094 KW |
375 | c->entries[i].offset = 0; |
376 | if (read_from_disk) { | |
29c1a730 KW |
377 | if (c == s->l2_table_cache) { |
378 | BLKDBG_EVENT(bs->file, BLKDBG_L2_LOAD); | |
379 | } | |
380 | ||
cf2ab8fc | 381 | ret = bdrv_pread(bs->file, offset, |
9a4f4c31 | 382 | qcow2_cache_get_table_addr(bs, c, i), |
72e80b89 | 383 | s->cluster_size); |
49381094 KW |
384 | if (ret < 0) { |
385 | return ret; | |
386 | } | |
387 | } | |
388 | ||
49381094 KW |
389 | c->entries[i].offset = offset; |
390 | ||
391 | /* And return the right table */ | |
392 | found: | |
49381094 | 393 | c->entries[i].ref++; |
72e80b89 | 394 | *table = qcow2_cache_get_table_addr(bs, c, i); |
3cce16f4 KW |
395 | |
396 | trace_qcow2_cache_get_done(qemu_coroutine_self(), | |
397 | c == s->l2_table_cache, i); | |
398 | ||
49381094 KW |
399 | return 0; |
400 | } | |
401 | ||
402 | int qcow2_cache_get(BlockDriverState *bs, Qcow2Cache *c, uint64_t offset, | |
403 | void **table) | |
404 | { | |
405 | return qcow2_cache_do_get(bs, c, offset, table, true); | |
406 | } | |
407 | ||
408 | int qcow2_cache_get_empty(BlockDriverState *bs, Qcow2Cache *c, uint64_t offset, | |
409 | void **table) | |
410 | { | |
411 | return qcow2_cache_do_get(bs, c, offset, table, false); | |
412 | } | |
413 | ||
a3f1afb4 | 414 | void qcow2_cache_put(BlockDriverState *bs, Qcow2Cache *c, void **table) |
49381094 | 415 | { |
baf07d60 | 416 | int i = qcow2_cache_get_table_idx(bs, c, *table); |
49381094 | 417 | |
49381094 KW |
418 | c->entries[i].ref--; |
419 | *table = NULL; | |
420 | ||
2693310e AG |
421 | if (c->entries[i].ref == 0) { |
422 | c->entries[i].lru_counter = ++c->lru_counter; | |
423 | } | |
424 | ||
49381094 | 425 | assert(c->entries[i].ref >= 0); |
49381094 KW |
426 | } |
427 | ||
72e80b89 AG |
428 | void qcow2_cache_entry_mark_dirty(BlockDriverState *bs, Qcow2Cache *c, |
429 | void *table) | |
49381094 | 430 | { |
baf07d60 AG |
431 | int i = qcow2_cache_get_table_idx(bs, c, table); |
432 | assert(c->entries[i].offset != 0); | |
49381094 KW |
433 | c->entries[i].dirty = true; |
434 | } | |
f71c08ea PB |
435 | |
436 | void *qcow2_cache_is_table_offset(BlockDriverState *bs, Qcow2Cache *c, | |
437 | uint64_t offset) | |
438 | { | |
439 | int i; | |
440 | ||
441 | for (i = 0; i < c->size; i++) { | |
442 | if (c->entries[i].offset == offset) { | |
443 | return qcow2_cache_get_table_addr(bs, c, i); | |
444 | } | |
445 | } | |
446 | return NULL; | |
447 | } | |
448 | ||
449 | void qcow2_cache_discard(BlockDriverState *bs, Qcow2Cache *c, void *table) | |
450 | { | |
451 | int i = qcow2_cache_get_table_idx(bs, c, table); | |
452 | ||
453 | assert(c->entries[i].ref == 0); | |
454 | ||
455 | c->entries[i].offset = 0; | |
456 | c->entries[i].lru_counter = 0; | |
457 | c->entries[i].dirty = false; | |
458 | ||
459 | qcow2_cache_table_release(bs, c, i, 1); | |
460 | } |