Merge tag 'gpio-v3.13-3' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw...
[linux-2.6.git] / drivers / md / dm-bio-prison.c
blob85f0b7074257b02aa53cb62f464a163ed6a56469
1 /*
2 * Copyright (C) 2012 Red Hat, Inc.
4 * This file is released under the GPL.
5 */
7 #include "dm.h"
8 #include "dm-bio-prison.h"
10 #include <linux/spinlock.h>
11 #include <linux/mempool.h>
12 #include <linux/module.h>
13 #include <linux/slab.h>
15 /*----------------------------------------------------------------*/
17 struct dm_bio_prison {
18 spinlock_t lock;
19 mempool_t *cell_pool;
21 unsigned nr_buckets;
22 unsigned hash_mask;
23 struct hlist_head *cells;
26 /*----------------------------------------------------------------*/
28 static uint32_t calc_nr_buckets(unsigned nr_cells)
30 uint32_t n = 128;
32 nr_cells /= 4;
33 nr_cells = min(nr_cells, 8192u);
35 while (n < nr_cells)
36 n <<= 1;
38 return n;
41 static struct kmem_cache *_cell_cache;
44 * @nr_cells should be the number of cells you want in use _concurrently_.
45 * Don't confuse it with the number of distinct keys.
47 struct dm_bio_prison *dm_bio_prison_create(unsigned nr_cells)
49 unsigned i;
50 uint32_t nr_buckets = calc_nr_buckets(nr_cells);
51 size_t len = sizeof(struct dm_bio_prison) +
52 (sizeof(struct hlist_head) * nr_buckets);
53 struct dm_bio_prison *prison = kmalloc(len, GFP_KERNEL);
55 if (!prison)
56 return NULL;
58 spin_lock_init(&prison->lock);
59 prison->cell_pool = mempool_create_slab_pool(nr_cells, _cell_cache);
60 if (!prison->cell_pool) {
61 kfree(prison);
62 return NULL;
65 prison->nr_buckets = nr_buckets;
66 prison->hash_mask = nr_buckets - 1;
67 prison->cells = (struct hlist_head *) (prison + 1);
68 for (i = 0; i < nr_buckets; i++)
69 INIT_HLIST_HEAD(prison->cells + i);
71 return prison;
73 EXPORT_SYMBOL_GPL(dm_bio_prison_create);
75 void dm_bio_prison_destroy(struct dm_bio_prison *prison)
77 mempool_destroy(prison->cell_pool);
78 kfree(prison);
80 EXPORT_SYMBOL_GPL(dm_bio_prison_destroy);
82 struct dm_bio_prison_cell *dm_bio_prison_alloc_cell(struct dm_bio_prison *prison, gfp_t gfp)
84 return mempool_alloc(prison->cell_pool, gfp);
86 EXPORT_SYMBOL_GPL(dm_bio_prison_alloc_cell);
88 void dm_bio_prison_free_cell(struct dm_bio_prison *prison,
89 struct dm_bio_prison_cell *cell)
91 mempool_free(cell, prison->cell_pool);
93 EXPORT_SYMBOL_GPL(dm_bio_prison_free_cell);
95 static uint32_t hash_key(struct dm_bio_prison *prison, struct dm_cell_key *key)
97 const unsigned long BIG_PRIME = 4294967291UL;
98 uint64_t hash = key->block * BIG_PRIME;
100 return (uint32_t) (hash & prison->hash_mask);
103 static int keys_equal(struct dm_cell_key *lhs, struct dm_cell_key *rhs)
105 return (lhs->virtual == rhs->virtual) &&
106 (lhs->dev == rhs->dev) &&
107 (lhs->block == rhs->block);
110 static struct dm_bio_prison_cell *__search_bucket(struct hlist_head *bucket,
111 struct dm_cell_key *key)
113 struct dm_bio_prison_cell *cell;
115 hlist_for_each_entry(cell, bucket, list)
116 if (keys_equal(&cell->key, key))
117 return cell;
119 return NULL;
122 static void __setup_new_cell(struct dm_bio_prison *prison,
123 struct dm_cell_key *key,
124 struct bio *holder,
125 uint32_t hash,
126 struct dm_bio_prison_cell *cell)
128 memcpy(&cell->key, key, sizeof(cell->key));
129 cell->holder = holder;
130 bio_list_init(&cell->bios);
131 hlist_add_head(&cell->list, prison->cells + hash);
134 static int __bio_detain(struct dm_bio_prison *prison,
135 struct dm_cell_key *key,
136 struct bio *inmate,
137 struct dm_bio_prison_cell *cell_prealloc,
138 struct dm_bio_prison_cell **cell_result)
140 uint32_t hash = hash_key(prison, key);
141 struct dm_bio_prison_cell *cell;
143 cell = __search_bucket(prison->cells + hash, key);
144 if (cell) {
145 if (inmate)
146 bio_list_add(&cell->bios, inmate);
147 *cell_result = cell;
148 return 1;
151 __setup_new_cell(prison, key, inmate, hash, cell_prealloc);
152 *cell_result = cell_prealloc;
153 return 0;
156 static int bio_detain(struct dm_bio_prison *prison,
157 struct dm_cell_key *key,
158 struct bio *inmate,
159 struct dm_bio_prison_cell *cell_prealloc,
160 struct dm_bio_prison_cell **cell_result)
162 int r;
163 unsigned long flags;
165 spin_lock_irqsave(&prison->lock, flags);
166 r = __bio_detain(prison, key, inmate, cell_prealloc, cell_result);
167 spin_unlock_irqrestore(&prison->lock, flags);
169 return r;
172 int dm_bio_detain(struct dm_bio_prison *prison,
173 struct dm_cell_key *key,
174 struct bio *inmate,
175 struct dm_bio_prison_cell *cell_prealloc,
176 struct dm_bio_prison_cell **cell_result)
178 return bio_detain(prison, key, inmate, cell_prealloc, cell_result);
180 EXPORT_SYMBOL_GPL(dm_bio_detain);
182 int dm_get_cell(struct dm_bio_prison *prison,
183 struct dm_cell_key *key,
184 struct dm_bio_prison_cell *cell_prealloc,
185 struct dm_bio_prison_cell **cell_result)
187 return bio_detain(prison, key, NULL, cell_prealloc, cell_result);
189 EXPORT_SYMBOL_GPL(dm_get_cell);
192 * @inmates must have been initialised prior to this call
194 static void __cell_release(struct dm_bio_prison_cell *cell,
195 struct bio_list *inmates)
197 hlist_del(&cell->list);
199 if (inmates) {
200 if (cell->holder)
201 bio_list_add(inmates, cell->holder);
202 bio_list_merge(inmates, &cell->bios);
206 void dm_cell_release(struct dm_bio_prison *prison,
207 struct dm_bio_prison_cell *cell,
208 struct bio_list *bios)
210 unsigned long flags;
212 spin_lock_irqsave(&prison->lock, flags);
213 __cell_release(cell, bios);
214 spin_unlock_irqrestore(&prison->lock, flags);
216 EXPORT_SYMBOL_GPL(dm_cell_release);
219 * Sometimes we don't want the holder, just the additional bios.
221 static void __cell_release_no_holder(struct dm_bio_prison_cell *cell,
222 struct bio_list *inmates)
224 hlist_del(&cell->list);
225 bio_list_merge(inmates, &cell->bios);
228 void dm_cell_release_no_holder(struct dm_bio_prison *prison,
229 struct dm_bio_prison_cell *cell,
230 struct bio_list *inmates)
232 unsigned long flags;
234 spin_lock_irqsave(&prison->lock, flags);
235 __cell_release_no_holder(cell, inmates);
236 spin_unlock_irqrestore(&prison->lock, flags);
238 EXPORT_SYMBOL_GPL(dm_cell_release_no_holder);
240 void dm_cell_error(struct dm_bio_prison *prison,
241 struct dm_bio_prison_cell *cell)
243 struct bio_list bios;
244 struct bio *bio;
245 unsigned long flags;
247 bio_list_init(&bios);
249 spin_lock_irqsave(&prison->lock, flags);
250 __cell_release(cell, &bios);
251 spin_unlock_irqrestore(&prison->lock, flags);
253 while ((bio = bio_list_pop(&bios)))
254 bio_io_error(bio);
256 EXPORT_SYMBOL_GPL(dm_cell_error);
258 /*----------------------------------------------------------------*/
260 #define DEFERRED_SET_SIZE 64
262 struct dm_deferred_entry {
263 struct dm_deferred_set *ds;
264 unsigned count;
265 struct list_head work_items;
268 struct dm_deferred_set {
269 spinlock_t lock;
270 unsigned current_entry;
271 unsigned sweeper;
272 struct dm_deferred_entry entries[DEFERRED_SET_SIZE];
275 struct dm_deferred_set *dm_deferred_set_create(void)
277 int i;
278 struct dm_deferred_set *ds;
280 ds = kmalloc(sizeof(*ds), GFP_KERNEL);
281 if (!ds)
282 return NULL;
284 spin_lock_init(&ds->lock);
285 ds->current_entry = 0;
286 ds->sweeper = 0;
287 for (i = 0; i < DEFERRED_SET_SIZE; i++) {
288 ds->entries[i].ds = ds;
289 ds->entries[i].count = 0;
290 INIT_LIST_HEAD(&ds->entries[i].work_items);
293 return ds;
295 EXPORT_SYMBOL_GPL(dm_deferred_set_create);
297 void dm_deferred_set_destroy(struct dm_deferred_set *ds)
299 kfree(ds);
301 EXPORT_SYMBOL_GPL(dm_deferred_set_destroy);
303 struct dm_deferred_entry *dm_deferred_entry_inc(struct dm_deferred_set *ds)
305 unsigned long flags;
306 struct dm_deferred_entry *entry;
308 spin_lock_irqsave(&ds->lock, flags);
309 entry = ds->entries + ds->current_entry;
310 entry->count++;
311 spin_unlock_irqrestore(&ds->lock, flags);
313 return entry;
315 EXPORT_SYMBOL_GPL(dm_deferred_entry_inc);
317 static unsigned ds_next(unsigned index)
319 return (index + 1) % DEFERRED_SET_SIZE;
322 static void __sweep(struct dm_deferred_set *ds, struct list_head *head)
324 while ((ds->sweeper != ds->current_entry) &&
325 !ds->entries[ds->sweeper].count) {
326 list_splice_init(&ds->entries[ds->sweeper].work_items, head);
327 ds->sweeper = ds_next(ds->sweeper);
330 if ((ds->sweeper == ds->current_entry) && !ds->entries[ds->sweeper].count)
331 list_splice_init(&ds->entries[ds->sweeper].work_items, head);
334 void dm_deferred_entry_dec(struct dm_deferred_entry *entry, struct list_head *head)
336 unsigned long flags;
338 spin_lock_irqsave(&entry->ds->lock, flags);
339 BUG_ON(!entry->count);
340 --entry->count;
341 __sweep(entry->ds, head);
342 spin_unlock_irqrestore(&entry->ds->lock, flags);
344 EXPORT_SYMBOL_GPL(dm_deferred_entry_dec);
347 * Returns 1 if deferred or 0 if no pending items to delay job.
349 int dm_deferred_set_add_work(struct dm_deferred_set *ds, struct list_head *work)
351 int r = 1;
352 unsigned long flags;
353 unsigned next_entry;
355 spin_lock_irqsave(&ds->lock, flags);
356 if ((ds->sweeper == ds->current_entry) &&
357 !ds->entries[ds->current_entry].count)
358 r = 0;
359 else {
360 list_add(work, &ds->entries[ds->current_entry].work_items);
361 next_entry = ds_next(ds->current_entry);
362 if (!ds->entries[next_entry].count)
363 ds->current_entry = next_entry;
365 spin_unlock_irqrestore(&ds->lock, flags);
367 return r;
369 EXPORT_SYMBOL_GPL(dm_deferred_set_add_work);
371 /*----------------------------------------------------------------*/
373 static int __init dm_bio_prison_init(void)
375 _cell_cache = KMEM_CACHE(dm_bio_prison_cell, 0);
376 if (!_cell_cache)
377 return -ENOMEM;
379 return 0;
382 static void __exit dm_bio_prison_exit(void)
384 kmem_cache_destroy(_cell_cache);
385 _cell_cache = NULL;
389 * module hooks
391 module_init(dm_bio_prison_init);
392 module_exit(dm_bio_prison_exit);
394 MODULE_DESCRIPTION(DM_NAME " bio prison");
395 MODULE_AUTHOR("Joe Thornber <dm-devel@redhat.com>");
396 MODULE_LICENSE("GPL");