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Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * linux/fs/mbcache.c | |
3 | * (C) 2001-2002 Andreas Gruenbacher, <a.gruenbacher@computer.org> | |
4 | */ | |
5 | ||
6 | /* | |
7 | * Filesystem Meta Information Block Cache (mbcache) | |
8 | * | |
9 | * The mbcache caches blocks of block devices that need to be located | |
10 | * by their device/block number, as well as by other criteria (such | |
11 | * as the block's contents). | |
12 | * | |
13 | * There can only be one cache entry in a cache per device and block number. | |
14 | * Additional indexes need not be unique in this sense. The number of | |
15 | * additional indexes (=other criteria) can be hardwired at compile time | |
16 | * or specified at cache create time. | |
17 | * | |
18 | * Each cache entry is of fixed size. An entry may be `valid' or `invalid' | |
19 | * in the cache. A valid entry is in the main hash tables of the cache, | |
20 | * and may also be in the lru list. An invalid entry is not in any hashes | |
21 | * or lists. | |
22 | * | |
23 | * A valid cache entry is only in the lru list if no handles refer to it. | |
24 | * Invalid cache entries will be freed when the last handle to the cache | |
25 | * entry is released. Entries that cannot be freed immediately are put | |
26 | * back on the lru list. | |
27 | */ | |
28 | ||
29 | #include <linux/kernel.h> | |
30 | #include <linux/module.h> | |
31 | ||
32 | #include <linux/hash.h> | |
33 | #include <linux/fs.h> | |
34 | #include <linux/mm.h> | |
35 | #include <linux/slab.h> | |
36 | #include <linux/sched.h> | |
37 | #include <linux/init.h> | |
38 | #include <linux/mbcache.h> | |
39 | ||
40 | ||
41 | #ifdef MB_CACHE_DEBUG | |
42 | # define mb_debug(f...) do { \ | |
43 | printk(KERN_DEBUG f); \ | |
44 | printk("\n"); \ | |
45 | } while (0) | |
46 | #define mb_assert(c) do { if (!(c)) \ | |
47 | printk(KERN_ERR "assertion " #c " failed\n"); \ | |
48 | } while(0) | |
49 | #else | |
50 | # define mb_debug(f...) do { } while(0) | |
51 | # define mb_assert(c) do { } while(0) | |
52 | #endif | |
53 | #define mb_error(f...) do { \ | |
54 | printk(KERN_ERR f); \ | |
55 | printk("\n"); \ | |
56 | } while(0) | |
57 | ||
58 | #define MB_CACHE_WRITER ((unsigned short)~0U >> 1) | |
59 | ||
75c96f85 | 60 | static DECLARE_WAIT_QUEUE_HEAD(mb_cache_queue); |
1da177e4 LT |
61 | |
62 | MODULE_AUTHOR("Andreas Gruenbacher <a.gruenbacher@computer.org>"); | |
63 | MODULE_DESCRIPTION("Meta block cache (for extended attributes)"); | |
64 | MODULE_LICENSE("GPL"); | |
65 | ||
66 | EXPORT_SYMBOL(mb_cache_create); | |
67 | EXPORT_SYMBOL(mb_cache_shrink); | |
68 | EXPORT_SYMBOL(mb_cache_destroy); | |
69 | EXPORT_SYMBOL(mb_cache_entry_alloc); | |
70 | EXPORT_SYMBOL(mb_cache_entry_insert); | |
71 | EXPORT_SYMBOL(mb_cache_entry_release); | |
72 | EXPORT_SYMBOL(mb_cache_entry_free); | |
73 | EXPORT_SYMBOL(mb_cache_entry_get); | |
74 | #if !defined(MB_CACHE_INDEXES_COUNT) || (MB_CACHE_INDEXES_COUNT > 0) | |
75 | EXPORT_SYMBOL(mb_cache_entry_find_first); | |
76 | EXPORT_SYMBOL(mb_cache_entry_find_next); | |
77 | #endif | |
78 | ||
79 | struct mb_cache { | |
80 | struct list_head c_cache_list; | |
81 | const char *c_name; | |
1da177e4 LT |
82 | atomic_t c_entry_count; |
83 | int c_bucket_bits; | |
2aec7c52 | 84 | struct kmem_cache *c_entry_cache; |
1da177e4 | 85 | struct list_head *c_block_hash; |
2aec7c52 | 86 | struct list_head *c_index_hash; |
1da177e4 LT |
87 | }; |
88 | ||
89 | ||
90 | /* | |
91 | * Global data: list of all mbcache's, lru list, and a spinlock for | |
92 | * accessing cache data structures on SMP machines. The lru list is | |
93 | * global across all mbcaches. | |
94 | */ | |
95 | ||
96 | static LIST_HEAD(mb_cache_list); | |
97 | static LIST_HEAD(mb_cache_lru_list); | |
98 | static DEFINE_SPINLOCK(mb_cache_spinlock); | |
1da177e4 | 99 | |
1da177e4 LT |
100 | /* |
101 | * What the mbcache registers as to get shrunk dynamically. | |
102 | */ | |
103 | ||
7f8275d0 | 104 | static int mb_cache_shrink_fn(struct shrinker *shrink, int nr_to_scan, gfp_t gfp_mask); |
1da177e4 | 105 | |
8e1f936b RR |
106 | static struct shrinker mb_cache_shrinker = { |
107 | .shrink = mb_cache_shrink_fn, | |
108 | .seeks = DEFAULT_SEEKS, | |
109 | }; | |
1da177e4 LT |
110 | |
111 | static inline int | |
112 | __mb_cache_entry_is_hashed(struct mb_cache_entry *ce) | |
113 | { | |
114 | return !list_empty(&ce->e_block_list); | |
115 | } | |
116 | ||
117 | ||
858119e1 | 118 | static void |
1da177e4 LT |
119 | __mb_cache_entry_unhash(struct mb_cache_entry *ce) |
120 | { | |
1da177e4 LT |
121 | if (__mb_cache_entry_is_hashed(ce)) { |
122 | list_del_init(&ce->e_block_list); | |
2aec7c52 | 123 | list_del(&ce->e_index.o_list); |
1da177e4 LT |
124 | } |
125 | } | |
126 | ||
127 | ||
858119e1 | 128 | static void |
27496a8c | 129 | __mb_cache_entry_forget(struct mb_cache_entry *ce, gfp_t gfp_mask) |
1da177e4 LT |
130 | { |
131 | struct mb_cache *cache = ce->e_cache; | |
132 | ||
133 | mb_assert(!(ce->e_used || ce->e_queued)); | |
2aec7c52 AG |
134 | kmem_cache_free(cache->c_entry_cache, ce); |
135 | atomic_dec(&cache->c_entry_count); | |
1da177e4 LT |
136 | } |
137 | ||
138 | ||
858119e1 | 139 | static void |
1da177e4 | 140 | __mb_cache_entry_release_unlock(struct mb_cache_entry *ce) |
58f555e5 | 141 | __releases(mb_cache_spinlock) |
1da177e4 LT |
142 | { |
143 | /* Wake up all processes queuing for this cache entry. */ | |
144 | if (ce->e_queued) | |
145 | wake_up_all(&mb_cache_queue); | |
146 | if (ce->e_used >= MB_CACHE_WRITER) | |
147 | ce->e_used -= MB_CACHE_WRITER; | |
148 | ce->e_used--; | |
149 | if (!(ce->e_used || ce->e_queued)) { | |
150 | if (!__mb_cache_entry_is_hashed(ce)) | |
151 | goto forget; | |
152 | mb_assert(list_empty(&ce->e_lru_list)); | |
153 | list_add_tail(&ce->e_lru_list, &mb_cache_lru_list); | |
154 | } | |
155 | spin_unlock(&mb_cache_spinlock); | |
156 | return; | |
157 | forget: | |
158 | spin_unlock(&mb_cache_spinlock); | |
159 | __mb_cache_entry_forget(ce, GFP_KERNEL); | |
160 | } | |
161 | ||
162 | ||
163 | /* | |
164 | * mb_cache_shrink_fn() memory pressure callback | |
165 | * | |
166 | * This function is called by the kernel memory management when memory | |
167 | * gets low. | |
168 | * | |
7f8275d0 | 169 | * @shrink: (ignored) |
1da177e4 LT |
170 | * @nr_to_scan: Number of objects to scan |
171 | * @gfp_mask: (ignored) | |
172 | * | |
173 | * Returns the number of objects which are present in the cache. | |
174 | */ | |
175 | static int | |
7f8275d0 | 176 | mb_cache_shrink_fn(struct shrinker *shrink, int nr_to_scan, gfp_t gfp_mask) |
1da177e4 LT |
177 | { |
178 | LIST_HEAD(free_list); | |
179 | struct list_head *l, *ltmp; | |
180 | int count = 0; | |
181 | ||
182 | spin_lock(&mb_cache_spinlock); | |
183 | list_for_each(l, &mb_cache_list) { | |
184 | struct mb_cache *cache = | |
185 | list_entry(l, struct mb_cache, c_cache_list); | |
186 | mb_debug("cache %s (%d)", cache->c_name, | |
187 | atomic_read(&cache->c_entry_count)); | |
188 | count += atomic_read(&cache->c_entry_count); | |
189 | } | |
190 | mb_debug("trying to free %d entries", nr_to_scan); | |
191 | if (nr_to_scan == 0) { | |
192 | spin_unlock(&mb_cache_spinlock); | |
193 | goto out; | |
194 | } | |
195 | while (nr_to_scan-- && !list_empty(&mb_cache_lru_list)) { | |
196 | struct mb_cache_entry *ce = | |
197 | list_entry(mb_cache_lru_list.next, | |
198 | struct mb_cache_entry, e_lru_list); | |
199 | list_move_tail(&ce->e_lru_list, &free_list); | |
200 | __mb_cache_entry_unhash(ce); | |
201 | } | |
202 | spin_unlock(&mb_cache_spinlock); | |
203 | list_for_each_safe(l, ltmp, &free_list) { | |
204 | __mb_cache_entry_forget(list_entry(l, struct mb_cache_entry, | |
205 | e_lru_list), gfp_mask); | |
206 | } | |
207 | out: | |
208 | return (count / 100) * sysctl_vfs_cache_pressure; | |
209 | } | |
210 | ||
211 | ||
212 | /* | |
213 | * mb_cache_create() create a new cache | |
214 | * | |
215 | * All entries in one cache are equal size. Cache entries may be from | |
216 | * multiple devices. If this is the first mbcache created, registers | |
217 | * the cache with kernel memory management. Returns NULL if no more | |
218 | * memory was available. | |
219 | * | |
220 | * @name: name of the cache (informal) | |
1da177e4 LT |
221 | * @bucket_bits: log2(number of hash buckets) |
222 | */ | |
223 | struct mb_cache * | |
2aec7c52 | 224 | mb_cache_create(const char *name, int bucket_bits) |
1da177e4 | 225 | { |
2aec7c52 | 226 | int n, bucket_count = 1 << bucket_bits; |
1da177e4 LT |
227 | struct mb_cache *cache = NULL; |
228 | ||
2aec7c52 | 229 | cache = kmalloc(sizeof(struct mb_cache), GFP_KERNEL); |
1da177e4 | 230 | if (!cache) |
2aec7c52 | 231 | return NULL; |
1da177e4 | 232 | cache->c_name = name; |
1da177e4 LT |
233 | atomic_set(&cache->c_entry_count, 0); |
234 | cache->c_bucket_bits = bucket_bits; | |
1da177e4 LT |
235 | cache->c_block_hash = kmalloc(bucket_count * sizeof(struct list_head), |
236 | GFP_KERNEL); | |
237 | if (!cache->c_block_hash) | |
238 | goto fail; | |
239 | for (n=0; n<bucket_count; n++) | |
240 | INIT_LIST_HEAD(&cache->c_block_hash[n]); | |
2aec7c52 AG |
241 | cache->c_index_hash = kmalloc(bucket_count * sizeof(struct list_head), |
242 | GFP_KERNEL); | |
243 | if (!cache->c_index_hash) | |
244 | goto fail; | |
245 | for (n=0; n<bucket_count; n++) | |
246 | INIT_LIST_HEAD(&cache->c_index_hash[n]); | |
247 | cache->c_entry_cache = kmem_cache_create(name, | |
248 | sizeof(struct mb_cache_entry), 0, | |
20c2df83 | 249 | SLAB_RECLAIM_ACCOUNT|SLAB_MEM_SPREAD, NULL); |
1da177e4 | 250 | if (!cache->c_entry_cache) |
2aec7c52 | 251 | goto fail2; |
1da177e4 LT |
252 | |
253 | spin_lock(&mb_cache_spinlock); | |
254 | list_add(&cache->c_cache_list, &mb_cache_list); | |
255 | spin_unlock(&mb_cache_spinlock); | |
256 | return cache; | |
257 | ||
2aec7c52 AG |
258 | fail2: |
259 | kfree(cache->c_index_hash); | |
260 | ||
1da177e4 | 261 | fail: |
2aec7c52 AG |
262 | kfree(cache->c_block_hash); |
263 | kfree(cache); | |
1da177e4 LT |
264 | return NULL; |
265 | } | |
266 | ||
267 | ||
268 | /* | |
269 | * mb_cache_shrink() | |
270 | * | |
7f927fcc | 271 | * Removes all cache entries of a device from the cache. All cache entries |
1da177e4 LT |
272 | * currently in use cannot be freed, and thus remain in the cache. All others |
273 | * are freed. | |
274 | * | |
1da177e4 LT |
275 | * @bdev: which device's cache entries to shrink |
276 | */ | |
277 | void | |
8c52ab42 | 278 | mb_cache_shrink(struct block_device *bdev) |
1da177e4 LT |
279 | { |
280 | LIST_HEAD(free_list); | |
281 | struct list_head *l, *ltmp; | |
282 | ||
283 | spin_lock(&mb_cache_spinlock); | |
284 | list_for_each_safe(l, ltmp, &mb_cache_lru_list) { | |
285 | struct mb_cache_entry *ce = | |
286 | list_entry(l, struct mb_cache_entry, e_lru_list); | |
287 | if (ce->e_bdev == bdev) { | |
288 | list_move_tail(&ce->e_lru_list, &free_list); | |
289 | __mb_cache_entry_unhash(ce); | |
290 | } | |
291 | } | |
292 | spin_unlock(&mb_cache_spinlock); | |
293 | list_for_each_safe(l, ltmp, &free_list) { | |
294 | __mb_cache_entry_forget(list_entry(l, struct mb_cache_entry, | |
295 | e_lru_list), GFP_KERNEL); | |
296 | } | |
297 | } | |
298 | ||
299 | ||
300 | /* | |
301 | * mb_cache_destroy() | |
302 | * | |
303 | * Shrinks the cache to its minimum possible size (hopefully 0 entries), | |
304 | * and then destroys it. If this was the last mbcache, un-registers the | |
305 | * mbcache from kernel memory management. | |
306 | */ | |
307 | void | |
308 | mb_cache_destroy(struct mb_cache *cache) | |
309 | { | |
310 | LIST_HEAD(free_list); | |
311 | struct list_head *l, *ltmp; | |
1da177e4 LT |
312 | |
313 | spin_lock(&mb_cache_spinlock); | |
314 | list_for_each_safe(l, ltmp, &mb_cache_lru_list) { | |
315 | struct mb_cache_entry *ce = | |
316 | list_entry(l, struct mb_cache_entry, e_lru_list); | |
317 | if (ce->e_cache == cache) { | |
318 | list_move_tail(&ce->e_lru_list, &free_list); | |
319 | __mb_cache_entry_unhash(ce); | |
320 | } | |
321 | } | |
322 | list_del(&cache->c_cache_list); | |
323 | spin_unlock(&mb_cache_spinlock); | |
324 | ||
325 | list_for_each_safe(l, ltmp, &free_list) { | |
326 | __mb_cache_entry_forget(list_entry(l, struct mb_cache_entry, | |
327 | e_lru_list), GFP_KERNEL); | |
328 | } | |
329 | ||
330 | if (atomic_read(&cache->c_entry_count) > 0) { | |
331 | mb_error("cache %s: %d orphaned entries", | |
332 | cache->c_name, | |
333 | atomic_read(&cache->c_entry_count)); | |
334 | } | |
335 | ||
336 | kmem_cache_destroy(cache->c_entry_cache); | |
337 | ||
2aec7c52 | 338 | kfree(cache->c_index_hash); |
1da177e4 LT |
339 | kfree(cache->c_block_hash); |
340 | kfree(cache); | |
341 | } | |
342 | ||
343 | ||
344 | /* | |
345 | * mb_cache_entry_alloc() | |
346 | * | |
347 | * Allocates a new cache entry. The new entry will not be valid initially, | |
348 | * and thus cannot be looked up yet. It should be filled with data, and | |
349 | * then inserted into the cache using mb_cache_entry_insert(). Returns NULL | |
350 | * if no more memory was available. | |
351 | */ | |
352 | struct mb_cache_entry * | |
335e92e8 | 353 | mb_cache_entry_alloc(struct mb_cache *cache, gfp_t gfp_flags) |
1da177e4 LT |
354 | { |
355 | struct mb_cache_entry *ce; | |
356 | ||
335e92e8 | 357 | ce = kmem_cache_alloc(cache->c_entry_cache, gfp_flags); |
1da177e4 | 358 | if (ce) { |
f9e83489 | 359 | atomic_inc(&cache->c_entry_count); |
1da177e4 LT |
360 | INIT_LIST_HEAD(&ce->e_lru_list); |
361 | INIT_LIST_HEAD(&ce->e_block_list); | |
362 | ce->e_cache = cache; | |
363 | ce->e_used = 1 + MB_CACHE_WRITER; | |
364 | ce->e_queued = 0; | |
365 | } | |
366 | return ce; | |
367 | } | |
368 | ||
369 | ||
370 | /* | |
371 | * mb_cache_entry_insert() | |
372 | * | |
373 | * Inserts an entry that was allocated using mb_cache_entry_alloc() into | |
374 | * the cache. After this, the cache entry can be looked up, but is not yet | |
375 | * in the lru list as the caller still holds a handle to it. Returns 0 on | |
376 | * success, or -EBUSY if a cache entry for that device + inode exists | |
377 | * already (this may happen after a failed lookup, but when another process | |
378 | * has inserted the same cache entry in the meantime). | |
379 | * | |
380 | * @bdev: device the cache entry belongs to | |
381 | * @block: block number | |
2aec7c52 | 382 | * @key: lookup key |
1da177e4 LT |
383 | */ |
384 | int | |
385 | mb_cache_entry_insert(struct mb_cache_entry *ce, struct block_device *bdev, | |
2aec7c52 | 386 | sector_t block, unsigned int key) |
1da177e4 LT |
387 | { |
388 | struct mb_cache *cache = ce->e_cache; | |
389 | unsigned int bucket; | |
390 | struct list_head *l; | |
2aec7c52 | 391 | int error = -EBUSY; |
1da177e4 LT |
392 | |
393 | bucket = hash_long((unsigned long)bdev + (block & 0xffffffff), | |
394 | cache->c_bucket_bits); | |
395 | spin_lock(&mb_cache_spinlock); | |
396 | list_for_each_prev(l, &cache->c_block_hash[bucket]) { | |
397 | struct mb_cache_entry *ce = | |
398 | list_entry(l, struct mb_cache_entry, e_block_list); | |
399 | if (ce->e_bdev == bdev && ce->e_block == block) | |
400 | goto out; | |
401 | } | |
402 | __mb_cache_entry_unhash(ce); | |
403 | ce->e_bdev = bdev; | |
404 | ce->e_block = block; | |
405 | list_add(&ce->e_block_list, &cache->c_block_hash[bucket]); | |
2aec7c52 AG |
406 | ce->e_index.o_key = key; |
407 | bucket = hash_long(key, cache->c_bucket_bits); | |
408 | list_add(&ce->e_index.o_list, &cache->c_index_hash[bucket]); | |
1da177e4 LT |
409 | error = 0; |
410 | out: | |
411 | spin_unlock(&mb_cache_spinlock); | |
412 | return error; | |
413 | } | |
414 | ||
415 | ||
416 | /* | |
417 | * mb_cache_entry_release() | |
418 | * | |
419 | * Release a handle to a cache entry. When the last handle to a cache entry | |
420 | * is released it is either freed (if it is invalid) or otherwise inserted | |
421 | * in to the lru list. | |
422 | */ | |
423 | void | |
424 | mb_cache_entry_release(struct mb_cache_entry *ce) | |
425 | { | |
426 | spin_lock(&mb_cache_spinlock); | |
427 | __mb_cache_entry_release_unlock(ce); | |
428 | } | |
429 | ||
430 | ||
431 | /* | |
432 | * mb_cache_entry_free() | |
433 | * | |
434 | * This is equivalent to the sequence mb_cache_entry_takeout() -- | |
435 | * mb_cache_entry_release(). | |
436 | */ | |
437 | void | |
438 | mb_cache_entry_free(struct mb_cache_entry *ce) | |
439 | { | |
440 | spin_lock(&mb_cache_spinlock); | |
441 | mb_assert(list_empty(&ce->e_lru_list)); | |
442 | __mb_cache_entry_unhash(ce); | |
443 | __mb_cache_entry_release_unlock(ce); | |
444 | } | |
445 | ||
446 | ||
447 | /* | |
448 | * mb_cache_entry_get() | |
449 | * | |
450 | * Get a cache entry by device / block number. (There can only be one entry | |
451 | * in the cache per device and block.) Returns NULL if no such cache entry | |
452 | * exists. The returned cache entry is locked for exclusive access ("single | |
453 | * writer"). | |
454 | */ | |
455 | struct mb_cache_entry * | |
456 | mb_cache_entry_get(struct mb_cache *cache, struct block_device *bdev, | |
457 | sector_t block) | |
458 | { | |
459 | unsigned int bucket; | |
460 | struct list_head *l; | |
461 | struct mb_cache_entry *ce; | |
462 | ||
463 | bucket = hash_long((unsigned long)bdev + (block & 0xffffffff), | |
464 | cache->c_bucket_bits); | |
465 | spin_lock(&mb_cache_spinlock); | |
466 | list_for_each(l, &cache->c_block_hash[bucket]) { | |
467 | ce = list_entry(l, struct mb_cache_entry, e_block_list); | |
468 | if (ce->e_bdev == bdev && ce->e_block == block) { | |
469 | DEFINE_WAIT(wait); | |
470 | ||
471 | if (!list_empty(&ce->e_lru_list)) | |
472 | list_del_init(&ce->e_lru_list); | |
473 | ||
474 | while (ce->e_used > 0) { | |
475 | ce->e_queued++; | |
476 | prepare_to_wait(&mb_cache_queue, &wait, | |
477 | TASK_UNINTERRUPTIBLE); | |
478 | spin_unlock(&mb_cache_spinlock); | |
479 | schedule(); | |
480 | spin_lock(&mb_cache_spinlock); | |
481 | ce->e_queued--; | |
482 | } | |
483 | finish_wait(&mb_cache_queue, &wait); | |
484 | ce->e_used += 1 + MB_CACHE_WRITER; | |
485 | ||
486 | if (!__mb_cache_entry_is_hashed(ce)) { | |
487 | __mb_cache_entry_release_unlock(ce); | |
488 | return NULL; | |
489 | } | |
490 | goto cleanup; | |
491 | } | |
492 | } | |
493 | ce = NULL; | |
494 | ||
495 | cleanup: | |
496 | spin_unlock(&mb_cache_spinlock); | |
497 | return ce; | |
498 | } | |
499 | ||
500 | #if !defined(MB_CACHE_INDEXES_COUNT) || (MB_CACHE_INDEXES_COUNT > 0) | |
501 | ||
502 | static struct mb_cache_entry * | |
503 | __mb_cache_entry_find(struct list_head *l, struct list_head *head, | |
2aec7c52 | 504 | struct block_device *bdev, unsigned int key) |
1da177e4 LT |
505 | { |
506 | while (l != head) { | |
507 | struct mb_cache_entry *ce = | |
2aec7c52 AG |
508 | list_entry(l, struct mb_cache_entry, e_index.o_list); |
509 | if (ce->e_bdev == bdev && ce->e_index.o_key == key) { | |
1da177e4 LT |
510 | DEFINE_WAIT(wait); |
511 | ||
512 | if (!list_empty(&ce->e_lru_list)) | |
513 | list_del_init(&ce->e_lru_list); | |
514 | ||
515 | /* Incrementing before holding the lock gives readers | |
516 | priority over writers. */ | |
517 | ce->e_used++; | |
518 | while (ce->e_used >= MB_CACHE_WRITER) { | |
519 | ce->e_queued++; | |
520 | prepare_to_wait(&mb_cache_queue, &wait, | |
521 | TASK_UNINTERRUPTIBLE); | |
522 | spin_unlock(&mb_cache_spinlock); | |
523 | schedule(); | |
524 | spin_lock(&mb_cache_spinlock); | |
525 | ce->e_queued--; | |
526 | } | |
527 | finish_wait(&mb_cache_queue, &wait); | |
528 | ||
529 | if (!__mb_cache_entry_is_hashed(ce)) { | |
530 | __mb_cache_entry_release_unlock(ce); | |
531 | spin_lock(&mb_cache_spinlock); | |
532 | return ERR_PTR(-EAGAIN); | |
533 | } | |
534 | return ce; | |
535 | } | |
536 | l = l->next; | |
537 | } | |
538 | return NULL; | |
539 | } | |
540 | ||
541 | ||
542 | /* | |
543 | * mb_cache_entry_find_first() | |
544 | * | |
545 | * Find the first cache entry on a given device with a certain key in | |
546 | * an additional index. Additonal matches can be found with | |
547 | * mb_cache_entry_find_next(). Returns NULL if no match was found. The | |
548 | * returned cache entry is locked for shared access ("multiple readers"). | |
549 | * | |
550 | * @cache: the cache to search | |
1da177e4 LT |
551 | * @bdev: the device the cache entry should belong to |
552 | * @key: the key in the index | |
553 | */ | |
554 | struct mb_cache_entry * | |
2aec7c52 AG |
555 | mb_cache_entry_find_first(struct mb_cache *cache, struct block_device *bdev, |
556 | unsigned int key) | |
1da177e4 LT |
557 | { |
558 | unsigned int bucket = hash_long(key, cache->c_bucket_bits); | |
559 | struct list_head *l; | |
560 | struct mb_cache_entry *ce; | |
561 | ||
1da177e4 | 562 | spin_lock(&mb_cache_spinlock); |
2aec7c52 AG |
563 | l = cache->c_index_hash[bucket].next; |
564 | ce = __mb_cache_entry_find(l, &cache->c_index_hash[bucket], bdev, key); | |
1da177e4 LT |
565 | spin_unlock(&mb_cache_spinlock); |
566 | return ce; | |
567 | } | |
568 | ||
569 | ||
570 | /* | |
571 | * mb_cache_entry_find_next() | |
572 | * | |
573 | * Find the next cache entry on a given device with a certain key in an | |
574 | * additional index. Returns NULL if no match could be found. The previous | |
575 | * entry is atomatically released, so that mb_cache_entry_find_next() can | |
576 | * be called like this: | |
577 | * | |
578 | * entry = mb_cache_entry_find_first(); | |
579 | * while (entry) { | |
580 | * ... | |
581 | * entry = mb_cache_entry_find_next(entry, ...); | |
582 | * } | |
583 | * | |
584 | * @prev: The previous match | |
1da177e4 LT |
585 | * @bdev: the device the cache entry should belong to |
586 | * @key: the key in the index | |
587 | */ | |
588 | struct mb_cache_entry * | |
2aec7c52 | 589 | mb_cache_entry_find_next(struct mb_cache_entry *prev, |
1da177e4 LT |
590 | struct block_device *bdev, unsigned int key) |
591 | { | |
592 | struct mb_cache *cache = prev->e_cache; | |
593 | unsigned int bucket = hash_long(key, cache->c_bucket_bits); | |
594 | struct list_head *l; | |
595 | struct mb_cache_entry *ce; | |
596 | ||
1da177e4 | 597 | spin_lock(&mb_cache_spinlock); |
2aec7c52 AG |
598 | l = prev->e_index.o_list.next; |
599 | ce = __mb_cache_entry_find(l, &cache->c_index_hash[bucket], bdev, key); | |
1da177e4 LT |
600 | __mb_cache_entry_release_unlock(prev); |
601 | return ce; | |
602 | } | |
603 | ||
604 | #endif /* !defined(MB_CACHE_INDEXES_COUNT) || (MB_CACHE_INDEXES_COUNT > 0) */ | |
605 | ||
606 | static int __init init_mbcache(void) | |
607 | { | |
8e1f936b | 608 | register_shrinker(&mb_cache_shrinker); |
1da177e4 LT |
609 | return 0; |
610 | } | |
611 | ||
612 | static void __exit exit_mbcache(void) | |
613 | { | |
8e1f936b | 614 | unregister_shrinker(&mb_cache_shrinker); |
1da177e4 LT |
615 | } |
616 | ||
617 | module_init(init_mbcache) | |
618 | module_exit(exit_mbcache) | |
619 |