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1/*
2 * Copyright (C) 2012 Red Hat, Inc.
3 *
4 * This file is released under the GPL.
5 */
6
7#include "dm.h"
8#include "dm-bio-prison-v1.h"
9#include "dm-bio-prison-v2.h"
10
11#include <linux/spinlock.h>
12#include <linux/mempool.h>
13#include <linux/module.h>
14#include <linux/slab.h>
15
16/*----------------------------------------------------------------*/
17
18#define MIN_CELLS 1024
19
20struct dm_bio_prison {
21 spinlock_t lock;
22 struct rb_root cells;
23 mempool_t cell_pool;
24};
25
26static struct kmem_cache *_cell_cache;
27
28/*----------------------------------------------------------------*/
29
30/*
31 * @nr_cells should be the number of cells you want in use _concurrently_.
32 * Don't confuse it with the number of distinct keys.
33 */
34struct dm_bio_prison *dm_bio_prison_create(void)
35{
36 struct dm_bio_prison *prison = kzalloc(sizeof(*prison), GFP_KERNEL);
37 int ret;
38
39 if (!prison)
40 return NULL;
41
42 spin_lock_init(&prison->lock);
43
44 ret = mempool_init_slab_pool(&prison->cell_pool, MIN_CELLS, _cell_cache);
45 if (ret) {
46 kfree(prison);
47 return NULL;
48 }
49
50 prison->cells = RB_ROOT;
51
52 return prison;
53}
54EXPORT_SYMBOL_GPL(dm_bio_prison_create);
55
56void dm_bio_prison_destroy(struct dm_bio_prison *prison)
57{
58 mempool_exit(&prison->cell_pool);
59 kfree(prison);
60}
61EXPORT_SYMBOL_GPL(dm_bio_prison_destroy);
62
63struct dm_bio_prison_cell *dm_bio_prison_alloc_cell(struct dm_bio_prison *prison, gfp_t gfp)
64{
65 return mempool_alloc(&prison->cell_pool, gfp);
66}
67EXPORT_SYMBOL_GPL(dm_bio_prison_alloc_cell);
68
69void dm_bio_prison_free_cell(struct dm_bio_prison *prison,
70 struct dm_bio_prison_cell *cell)
71{
72 mempool_free(cell, &prison->cell_pool);
73}
74EXPORT_SYMBOL_GPL(dm_bio_prison_free_cell);
75
76static void __setup_new_cell(struct dm_cell_key *key,
77 struct bio *holder,
78 struct dm_bio_prison_cell *cell)
79{
80 memcpy(&cell->key, key, sizeof(cell->key));
81 cell->holder = holder;
82 bio_list_init(&cell->bios);
83}
84
85static int cmp_keys(struct dm_cell_key *lhs,
86 struct dm_cell_key *rhs)
87{
88 if (lhs->virtual < rhs->virtual)
89 return -1;
90
91 if (lhs->virtual > rhs->virtual)
92 return 1;
93
94 if (lhs->dev < rhs->dev)
95 return -1;
96
97 if (lhs->dev > rhs->dev)
98 return 1;
99
100 if (lhs->block_end <= rhs->block_begin)
101 return -1;
102
103 if (lhs->block_begin >= rhs->block_end)
104 return 1;
105
106 return 0;
107}
108
109static int __bio_detain(struct dm_bio_prison *prison,
110 struct dm_cell_key *key,
111 struct bio *inmate,
112 struct dm_bio_prison_cell *cell_prealloc,
113 struct dm_bio_prison_cell **cell_result)
114{
115 int r;
116 struct rb_node **new = &prison->cells.rb_node, *parent = NULL;
117
118 while (*new) {
119 struct dm_bio_prison_cell *cell =
120 rb_entry(*new, struct dm_bio_prison_cell, node);
121
122 r = cmp_keys(key, &cell->key);
123
124 parent = *new;
125 if (r < 0)
126 new = &((*new)->rb_left);
127 else if (r > 0)
128 new = &((*new)->rb_right);
129 else {
130 if (inmate)
131 bio_list_add(&cell->bios, inmate);
132 *cell_result = cell;
133 return 1;
134 }
135 }
136
137 __setup_new_cell(key, inmate, cell_prealloc);
138 *cell_result = cell_prealloc;
139
140 rb_link_node(&cell_prealloc->node, parent, new);
141 rb_insert_color(&cell_prealloc->node, &prison->cells);
142
143 return 0;
144}
145
146static int bio_detain(struct dm_bio_prison *prison,
147 struct dm_cell_key *key,
148 struct bio *inmate,
149 struct dm_bio_prison_cell *cell_prealloc,
150 struct dm_bio_prison_cell **cell_result)
151{
152 int r;
153
154 spin_lock_irq(&prison->lock);
155 r = __bio_detain(prison, key, inmate, cell_prealloc, cell_result);
156 spin_unlock_irq(&prison->lock);
157
158 return r;
159}
160
161int dm_bio_detain(struct dm_bio_prison *prison,
162 struct dm_cell_key *key,
163 struct bio *inmate,
164 struct dm_bio_prison_cell *cell_prealloc,
165 struct dm_bio_prison_cell **cell_result)
166{
167 return bio_detain(prison, key, inmate, cell_prealloc, cell_result);
168}
169EXPORT_SYMBOL_GPL(dm_bio_detain);
170
171int dm_get_cell(struct dm_bio_prison *prison,
172 struct dm_cell_key *key,
173 struct dm_bio_prison_cell *cell_prealloc,
174 struct dm_bio_prison_cell **cell_result)
175{
176 return bio_detain(prison, key, NULL, cell_prealloc, cell_result);
177}
178EXPORT_SYMBOL_GPL(dm_get_cell);
179
180/*
181 * @inmates must have been initialised prior to this call
182 */
183static void __cell_release(struct dm_bio_prison *prison,
184 struct dm_bio_prison_cell *cell,
185 struct bio_list *inmates)
186{
187 rb_erase(&cell->node, &prison->cells);
188
189 if (inmates) {
190 if (cell->holder)
191 bio_list_add(inmates, cell->holder);
192 bio_list_merge(inmates, &cell->bios);
193 }
194}
195
196void dm_cell_release(struct dm_bio_prison *prison,
197 struct dm_bio_prison_cell *cell,
198 struct bio_list *bios)
199{
200 spin_lock_irq(&prison->lock);
201 __cell_release(prison, cell, bios);
202 spin_unlock_irq(&prison->lock);
203}
204EXPORT_SYMBOL_GPL(dm_cell_release);
205
206/*
207 * Sometimes we don't want the holder, just the additional bios.
208 */
209static void __cell_release_no_holder(struct dm_bio_prison *prison,
210 struct dm_bio_prison_cell *cell,
211 struct bio_list *inmates)
212{
213 rb_erase(&cell->node, &prison->cells);
214 bio_list_merge(inmates, &cell->bios);
215}
216
217void dm_cell_release_no_holder(struct dm_bio_prison *prison,
218 struct dm_bio_prison_cell *cell,
219 struct bio_list *inmates)
220{
221 unsigned long flags;
222
223 spin_lock_irqsave(&prison->lock, flags);
224 __cell_release_no_holder(prison, cell, inmates);
225 spin_unlock_irqrestore(&prison->lock, flags);
226}
227EXPORT_SYMBOL_GPL(dm_cell_release_no_holder);
228
229void dm_cell_error(struct dm_bio_prison *prison,
230 struct dm_bio_prison_cell *cell, blk_status_t error)
231{
232 struct bio_list bios;
233 struct bio *bio;
234
235 bio_list_init(&bios);
236 dm_cell_release(prison, cell, &bios);
237
238 while ((bio = bio_list_pop(&bios))) {
239 bio->bi_status = error;
240 bio_endio(bio);
241 }
242}
243EXPORT_SYMBOL_GPL(dm_cell_error);
244
245void dm_cell_visit_release(struct dm_bio_prison *prison,
246 void (*visit_fn)(void *, struct dm_bio_prison_cell *),
247 void *context,
248 struct dm_bio_prison_cell *cell)
249{
250 spin_lock_irq(&prison->lock);
251 visit_fn(context, cell);
252 rb_erase(&cell->node, &prison->cells);
253 spin_unlock_irq(&prison->lock);
254}
255EXPORT_SYMBOL_GPL(dm_cell_visit_release);
256
257static int __promote_or_release(struct dm_bio_prison *prison,
258 struct dm_bio_prison_cell *cell)
259{
260 if (bio_list_empty(&cell->bios)) {
261 rb_erase(&cell->node, &prison->cells);
262 return 1;
263 }
264
265 cell->holder = bio_list_pop(&cell->bios);
266 return 0;
267}
268
269int dm_cell_promote_or_release(struct dm_bio_prison *prison,
270 struct dm_bio_prison_cell *cell)
271{
272 int r;
273
274 spin_lock_irq(&prison->lock);
275 r = __promote_or_release(prison, cell);
276 spin_unlock_irq(&prison->lock);
277
278 return r;
279}
280EXPORT_SYMBOL_GPL(dm_cell_promote_or_release);
281
282/*----------------------------------------------------------------*/
283
284#define DEFERRED_SET_SIZE 64
285
286struct dm_deferred_entry {
287 struct dm_deferred_set *ds;
288 unsigned count;
289 struct list_head work_items;
290};
291
292struct dm_deferred_set {
293 spinlock_t lock;
294 unsigned current_entry;
295 unsigned sweeper;
296 struct dm_deferred_entry entries[DEFERRED_SET_SIZE];
297};
298
299struct dm_deferred_set *dm_deferred_set_create(void)
300{
301 int i;
302 struct dm_deferred_set *ds;
303
304 ds = kmalloc(sizeof(*ds), GFP_KERNEL);
305 if (!ds)
306 return NULL;
307
308 spin_lock_init(&ds->lock);
309 ds->current_entry = 0;
310 ds->sweeper = 0;
311 for (i = 0; i < DEFERRED_SET_SIZE; i++) {
312 ds->entries[i].ds = ds;
313 ds->entries[i].count = 0;
314 INIT_LIST_HEAD(&ds->entries[i].work_items);
315 }
316
317 return ds;
318}
319EXPORT_SYMBOL_GPL(dm_deferred_set_create);
320
321void dm_deferred_set_destroy(struct dm_deferred_set *ds)
322{
323 kfree(ds);
324}
325EXPORT_SYMBOL_GPL(dm_deferred_set_destroy);
326
327struct dm_deferred_entry *dm_deferred_entry_inc(struct dm_deferred_set *ds)
328{
329 unsigned long flags;
330 struct dm_deferred_entry *entry;
331
332 spin_lock_irqsave(&ds->lock, flags);
333 entry = ds->entries + ds->current_entry;
334 entry->count++;
335 spin_unlock_irqrestore(&ds->lock, flags);
336
337 return entry;
338}
339EXPORT_SYMBOL_GPL(dm_deferred_entry_inc);
340
341static unsigned ds_next(unsigned index)
342{
343 return (index + 1) % DEFERRED_SET_SIZE;
344}
345
346static void __sweep(struct dm_deferred_set *ds, struct list_head *head)
347{
348 while ((ds->sweeper != ds->current_entry) &&
349 !ds->entries[ds->sweeper].count) {
350 list_splice_init(&ds->entries[ds->sweeper].work_items, head);
351 ds->sweeper = ds_next(ds->sweeper);
352 }
353
354 if ((ds->sweeper == ds->current_entry) && !ds->entries[ds->sweeper].count)
355 list_splice_init(&ds->entries[ds->sweeper].work_items, head);
356}
357
358void dm_deferred_entry_dec(struct dm_deferred_entry *entry, struct list_head *head)
359{
360 unsigned long flags;
361
362 spin_lock_irqsave(&entry->ds->lock, flags);
363 BUG_ON(!entry->count);
364 --entry->count;
365 __sweep(entry->ds, head);
366 spin_unlock_irqrestore(&entry->ds->lock, flags);
367}
368EXPORT_SYMBOL_GPL(dm_deferred_entry_dec);
369
370/*
371 * Returns 1 if deferred or 0 if no pending items to delay job.
372 */
373int dm_deferred_set_add_work(struct dm_deferred_set *ds, struct list_head *work)
374{
375 int r = 1;
376 unsigned next_entry;
377
378 spin_lock_irq(&ds->lock);
379 if ((ds->sweeper == ds->current_entry) &&
380 !ds->entries[ds->current_entry].count)
381 r = 0;
382 else {
383 list_add(work, &ds->entries[ds->current_entry].work_items);
384 next_entry = ds_next(ds->current_entry);
385 if (!ds->entries[next_entry].count)
386 ds->current_entry = next_entry;
387 }
388 spin_unlock_irq(&ds->lock);
389
390 return r;
391}
392EXPORT_SYMBOL_GPL(dm_deferred_set_add_work);
393
394/*----------------------------------------------------------------*/
395
396static int __init dm_bio_prison_init_v1(void)
397{
398 _cell_cache = KMEM_CACHE(dm_bio_prison_cell, 0);
399 if (!_cell_cache)
400 return -ENOMEM;
401
402 return 0;
403}
404
405static void dm_bio_prison_exit_v1(void)
406{
407 kmem_cache_destroy(_cell_cache);
408 _cell_cache = NULL;
409}
410
411static int (*_inits[])(void) __initdata = {
412 dm_bio_prison_init_v1,
413 dm_bio_prison_init_v2,
414};
415
416static void (*_exits[])(void) = {
417 dm_bio_prison_exit_v1,
418 dm_bio_prison_exit_v2,
419};
420
421static int __init dm_bio_prison_init(void)
422{
423 const int count = ARRAY_SIZE(_inits);
424
425 int r, i;
426
427 for (i = 0; i < count; i++) {
428 r = _inits[i]();
429 if (r)
430 goto bad;
431 }
432
433 return 0;
434
435 bad:
436 while (i--)
437 _exits[i]();
438
439 return r;
440}
441
442static void __exit dm_bio_prison_exit(void)
443{
444 int i = ARRAY_SIZE(_exits);
445
446 while (i--)
447 _exits[i]();
448}
449
450/*
451 * module hooks
452 */
453module_init(dm_bio_prison_init);
454module_exit(dm_bio_prison_exit);
455
456MODULE_DESCRIPTION(DM_NAME " bio prison");
457MODULE_AUTHOR("Joe Thornber <dm-devel@redhat.com>");
458MODULE_LICENSE("GPL");
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (C) 2012 Red Hat, Inc.
4 *
5 * This file is released under the GPL.
6 */
7
8#include "dm.h"
9#include "dm-bio-prison-v1.h"
10#include "dm-bio-prison-v2.h"
11
12#include <linux/spinlock.h>
13#include <linux/mempool.h>
14#include <linux/module.h>
15#include <linux/slab.h>
16
17/*----------------------------------------------------------------*/
18
19#define MIN_CELLS 1024
20
21struct prison_region {
22 spinlock_t lock;
23 struct rb_root cell;
24} ____cacheline_aligned_in_smp;
25
26struct dm_bio_prison {
27 mempool_t cell_pool;
28 unsigned int num_locks;
29 struct prison_region regions[] __counted_by(num_locks);
30};
31
32static struct kmem_cache *_cell_cache;
33
34/*----------------------------------------------------------------*/
35
36/*
37 * @nr_cells should be the number of cells you want in use _concurrently_.
38 * Don't confuse it with the number of distinct keys.
39 */
40struct dm_bio_prison *dm_bio_prison_create(void)
41{
42 int ret;
43 unsigned int i, num_locks;
44 struct dm_bio_prison *prison;
45
46 num_locks = dm_num_hash_locks();
47 prison = kzalloc(struct_size(prison, regions, num_locks), GFP_KERNEL);
48 if (!prison)
49 return NULL;
50 prison->num_locks = num_locks;
51
52 for (i = 0; i < prison->num_locks; i++) {
53 spin_lock_init(&prison->regions[i].lock);
54 prison->regions[i].cell = RB_ROOT;
55 }
56
57 ret = mempool_init_slab_pool(&prison->cell_pool, MIN_CELLS, _cell_cache);
58 if (ret) {
59 kfree(prison);
60 return NULL;
61 }
62
63 return prison;
64}
65EXPORT_SYMBOL_GPL(dm_bio_prison_create);
66
67void dm_bio_prison_destroy(struct dm_bio_prison *prison)
68{
69 mempool_exit(&prison->cell_pool);
70 kfree(prison);
71}
72EXPORT_SYMBOL_GPL(dm_bio_prison_destroy);
73
74struct dm_bio_prison_cell *dm_bio_prison_alloc_cell(struct dm_bio_prison *prison, gfp_t gfp)
75{
76 return mempool_alloc(&prison->cell_pool, gfp);
77}
78EXPORT_SYMBOL_GPL(dm_bio_prison_alloc_cell);
79
80void dm_bio_prison_free_cell(struct dm_bio_prison *prison,
81 struct dm_bio_prison_cell *cell)
82{
83 mempool_free(cell, &prison->cell_pool);
84}
85EXPORT_SYMBOL_GPL(dm_bio_prison_free_cell);
86
87static void __setup_new_cell(struct dm_cell_key *key,
88 struct bio *holder,
89 struct dm_bio_prison_cell *cell)
90{
91 memcpy(&cell->key, key, sizeof(cell->key));
92 cell->holder = holder;
93 bio_list_init(&cell->bios);
94}
95
96static int cmp_keys(struct dm_cell_key *lhs,
97 struct dm_cell_key *rhs)
98{
99 if (lhs->virtual < rhs->virtual)
100 return -1;
101
102 if (lhs->virtual > rhs->virtual)
103 return 1;
104
105 if (lhs->dev < rhs->dev)
106 return -1;
107
108 if (lhs->dev > rhs->dev)
109 return 1;
110
111 if (lhs->block_end <= rhs->block_begin)
112 return -1;
113
114 if (lhs->block_begin >= rhs->block_end)
115 return 1;
116
117 return 0;
118}
119
120static inline unsigned int lock_nr(struct dm_cell_key *key, unsigned int num_locks)
121{
122 return dm_hash_locks_index((key->block_begin >> BIO_PRISON_MAX_RANGE_SHIFT),
123 num_locks);
124}
125
126bool dm_cell_key_has_valid_range(struct dm_cell_key *key)
127{
128 if (WARN_ON_ONCE(key->block_end - key->block_begin > BIO_PRISON_MAX_RANGE))
129 return false;
130 if (WARN_ON_ONCE((key->block_begin >> BIO_PRISON_MAX_RANGE_SHIFT) !=
131 (key->block_end - 1) >> BIO_PRISON_MAX_RANGE_SHIFT))
132 return false;
133
134 return true;
135}
136EXPORT_SYMBOL(dm_cell_key_has_valid_range);
137
138static int __bio_detain(struct rb_root *root,
139 struct dm_cell_key *key,
140 struct bio *inmate,
141 struct dm_bio_prison_cell *cell_prealloc,
142 struct dm_bio_prison_cell **cell_result)
143{
144 int r;
145 struct rb_node **new = &root->rb_node, *parent = NULL;
146
147 while (*new) {
148 struct dm_bio_prison_cell *cell =
149 rb_entry(*new, struct dm_bio_prison_cell, node);
150
151 r = cmp_keys(key, &cell->key);
152
153 parent = *new;
154 if (r < 0)
155 new = &((*new)->rb_left);
156 else if (r > 0)
157 new = &((*new)->rb_right);
158 else {
159 if (inmate)
160 bio_list_add(&cell->bios, inmate);
161 *cell_result = cell;
162 return 1;
163 }
164 }
165
166 __setup_new_cell(key, inmate, cell_prealloc);
167 *cell_result = cell_prealloc;
168
169 rb_link_node(&cell_prealloc->node, parent, new);
170 rb_insert_color(&cell_prealloc->node, root);
171
172 return 0;
173}
174
175static int bio_detain(struct dm_bio_prison *prison,
176 struct dm_cell_key *key,
177 struct bio *inmate,
178 struct dm_bio_prison_cell *cell_prealloc,
179 struct dm_bio_prison_cell **cell_result)
180{
181 int r;
182 unsigned l = lock_nr(key, prison->num_locks);
183
184 spin_lock_irq(&prison->regions[l].lock);
185 r = __bio_detain(&prison->regions[l].cell, key, inmate, cell_prealloc, cell_result);
186 spin_unlock_irq(&prison->regions[l].lock);
187
188 return r;
189}
190
191int dm_bio_detain(struct dm_bio_prison *prison,
192 struct dm_cell_key *key,
193 struct bio *inmate,
194 struct dm_bio_prison_cell *cell_prealloc,
195 struct dm_bio_prison_cell **cell_result)
196{
197 return bio_detain(prison, key, inmate, cell_prealloc, cell_result);
198}
199EXPORT_SYMBOL_GPL(dm_bio_detain);
200
201int dm_get_cell(struct dm_bio_prison *prison,
202 struct dm_cell_key *key,
203 struct dm_bio_prison_cell *cell_prealloc,
204 struct dm_bio_prison_cell **cell_result)
205{
206 return bio_detain(prison, key, NULL, cell_prealloc, cell_result);
207}
208EXPORT_SYMBOL_GPL(dm_get_cell);
209
210/*
211 * @inmates must have been initialised prior to this call
212 */
213static void __cell_release(struct rb_root *root,
214 struct dm_bio_prison_cell *cell,
215 struct bio_list *inmates)
216{
217 rb_erase(&cell->node, root);
218
219 if (inmates) {
220 if (cell->holder)
221 bio_list_add(inmates, cell->holder);
222 bio_list_merge(inmates, &cell->bios);
223 }
224}
225
226void dm_cell_release(struct dm_bio_prison *prison,
227 struct dm_bio_prison_cell *cell,
228 struct bio_list *bios)
229{
230 unsigned l = lock_nr(&cell->key, prison->num_locks);
231
232 spin_lock_irq(&prison->regions[l].lock);
233 __cell_release(&prison->regions[l].cell, cell, bios);
234 spin_unlock_irq(&prison->regions[l].lock);
235}
236EXPORT_SYMBOL_GPL(dm_cell_release);
237
238/*
239 * Sometimes we don't want the holder, just the additional bios.
240 */
241static void __cell_release_no_holder(struct rb_root *root,
242 struct dm_bio_prison_cell *cell,
243 struct bio_list *inmates)
244{
245 rb_erase(&cell->node, root);
246 bio_list_merge(inmates, &cell->bios);
247}
248
249void dm_cell_release_no_holder(struct dm_bio_prison *prison,
250 struct dm_bio_prison_cell *cell,
251 struct bio_list *inmates)
252{
253 unsigned l = lock_nr(&cell->key, prison->num_locks);
254 unsigned long flags;
255
256 spin_lock_irqsave(&prison->regions[l].lock, flags);
257 __cell_release_no_holder(&prison->regions[l].cell, cell, inmates);
258 spin_unlock_irqrestore(&prison->regions[l].lock, flags);
259}
260EXPORT_SYMBOL_GPL(dm_cell_release_no_holder);
261
262void dm_cell_error(struct dm_bio_prison *prison,
263 struct dm_bio_prison_cell *cell, blk_status_t error)
264{
265 struct bio_list bios;
266 struct bio *bio;
267
268 bio_list_init(&bios);
269 dm_cell_release(prison, cell, &bios);
270
271 while ((bio = bio_list_pop(&bios))) {
272 bio->bi_status = error;
273 bio_endio(bio);
274 }
275}
276EXPORT_SYMBOL_GPL(dm_cell_error);
277
278void dm_cell_visit_release(struct dm_bio_prison *prison,
279 void (*visit_fn)(void *, struct dm_bio_prison_cell *),
280 void *context,
281 struct dm_bio_prison_cell *cell)
282{
283 unsigned l = lock_nr(&cell->key, prison->num_locks);
284 spin_lock_irq(&prison->regions[l].lock);
285 visit_fn(context, cell);
286 rb_erase(&cell->node, &prison->regions[l].cell);
287 spin_unlock_irq(&prison->regions[l].lock);
288}
289EXPORT_SYMBOL_GPL(dm_cell_visit_release);
290
291static int __promote_or_release(struct rb_root *root,
292 struct dm_bio_prison_cell *cell)
293{
294 if (bio_list_empty(&cell->bios)) {
295 rb_erase(&cell->node, root);
296 return 1;
297 }
298
299 cell->holder = bio_list_pop(&cell->bios);
300 return 0;
301}
302
303int dm_cell_promote_or_release(struct dm_bio_prison *prison,
304 struct dm_bio_prison_cell *cell)
305{
306 int r;
307 unsigned l = lock_nr(&cell->key, prison->num_locks);
308
309 spin_lock_irq(&prison->regions[l].lock);
310 r = __promote_or_release(&prison->regions[l].cell, cell);
311 spin_unlock_irq(&prison->regions[l].lock);
312
313 return r;
314}
315EXPORT_SYMBOL_GPL(dm_cell_promote_or_release);
316
317/*----------------------------------------------------------------*/
318
319#define DEFERRED_SET_SIZE 64
320
321struct dm_deferred_entry {
322 struct dm_deferred_set *ds;
323 unsigned int count;
324 struct list_head work_items;
325};
326
327struct dm_deferred_set {
328 spinlock_t lock;
329 unsigned int current_entry;
330 unsigned int sweeper;
331 struct dm_deferred_entry entries[DEFERRED_SET_SIZE];
332};
333
334struct dm_deferred_set *dm_deferred_set_create(void)
335{
336 int i;
337 struct dm_deferred_set *ds;
338
339 ds = kmalloc(sizeof(*ds), GFP_KERNEL);
340 if (!ds)
341 return NULL;
342
343 spin_lock_init(&ds->lock);
344 ds->current_entry = 0;
345 ds->sweeper = 0;
346 for (i = 0; i < DEFERRED_SET_SIZE; i++) {
347 ds->entries[i].ds = ds;
348 ds->entries[i].count = 0;
349 INIT_LIST_HEAD(&ds->entries[i].work_items);
350 }
351
352 return ds;
353}
354EXPORT_SYMBOL_GPL(dm_deferred_set_create);
355
356void dm_deferred_set_destroy(struct dm_deferred_set *ds)
357{
358 kfree(ds);
359}
360EXPORT_SYMBOL_GPL(dm_deferred_set_destroy);
361
362struct dm_deferred_entry *dm_deferred_entry_inc(struct dm_deferred_set *ds)
363{
364 unsigned long flags;
365 struct dm_deferred_entry *entry;
366
367 spin_lock_irqsave(&ds->lock, flags);
368 entry = ds->entries + ds->current_entry;
369 entry->count++;
370 spin_unlock_irqrestore(&ds->lock, flags);
371
372 return entry;
373}
374EXPORT_SYMBOL_GPL(dm_deferred_entry_inc);
375
376static unsigned int ds_next(unsigned int index)
377{
378 return (index + 1) % DEFERRED_SET_SIZE;
379}
380
381static void __sweep(struct dm_deferred_set *ds, struct list_head *head)
382{
383 while ((ds->sweeper != ds->current_entry) &&
384 !ds->entries[ds->sweeper].count) {
385 list_splice_init(&ds->entries[ds->sweeper].work_items, head);
386 ds->sweeper = ds_next(ds->sweeper);
387 }
388
389 if ((ds->sweeper == ds->current_entry) && !ds->entries[ds->sweeper].count)
390 list_splice_init(&ds->entries[ds->sweeper].work_items, head);
391}
392
393void dm_deferred_entry_dec(struct dm_deferred_entry *entry, struct list_head *head)
394{
395 unsigned long flags;
396
397 spin_lock_irqsave(&entry->ds->lock, flags);
398 BUG_ON(!entry->count);
399 --entry->count;
400 __sweep(entry->ds, head);
401 spin_unlock_irqrestore(&entry->ds->lock, flags);
402}
403EXPORT_SYMBOL_GPL(dm_deferred_entry_dec);
404
405/*
406 * Returns 1 if deferred or 0 if no pending items to delay job.
407 */
408int dm_deferred_set_add_work(struct dm_deferred_set *ds, struct list_head *work)
409{
410 int r = 1;
411 unsigned int next_entry;
412
413 spin_lock_irq(&ds->lock);
414 if ((ds->sweeper == ds->current_entry) &&
415 !ds->entries[ds->current_entry].count)
416 r = 0;
417 else {
418 list_add(work, &ds->entries[ds->current_entry].work_items);
419 next_entry = ds_next(ds->current_entry);
420 if (!ds->entries[next_entry].count)
421 ds->current_entry = next_entry;
422 }
423 spin_unlock_irq(&ds->lock);
424
425 return r;
426}
427EXPORT_SYMBOL_GPL(dm_deferred_set_add_work);
428
429/*----------------------------------------------------------------*/
430
431static int __init dm_bio_prison_init_v1(void)
432{
433 _cell_cache = KMEM_CACHE(dm_bio_prison_cell, 0);
434 if (!_cell_cache)
435 return -ENOMEM;
436
437 return 0;
438}
439
440static void dm_bio_prison_exit_v1(void)
441{
442 kmem_cache_destroy(_cell_cache);
443 _cell_cache = NULL;
444}
445
446static int (*_inits[])(void) __initdata = {
447 dm_bio_prison_init_v1,
448 dm_bio_prison_init_v2,
449};
450
451static void (*_exits[])(void) = {
452 dm_bio_prison_exit_v1,
453 dm_bio_prison_exit_v2,
454};
455
456static int __init dm_bio_prison_init(void)
457{
458 const int count = ARRAY_SIZE(_inits);
459
460 int r, i;
461
462 for (i = 0; i < count; i++) {
463 r = _inits[i]();
464 if (r)
465 goto bad;
466 }
467
468 return 0;
469
470bad:
471 while (i--)
472 _exits[i]();
473
474 return r;
475}
476
477static void __exit dm_bio_prison_exit(void)
478{
479 int i = ARRAY_SIZE(_exits);
480
481 while (i--)
482 _exits[i]();
483}
484
485/*
486 * module hooks
487 */
488module_init(dm_bio_prison_init);
489module_exit(dm_bio_prison_exit);
490
491MODULE_DESCRIPTION(DM_NAME " bio prison");
492MODULE_AUTHOR("Joe Thornber <dm-devel@lists.linux.dev>");
493MODULE_LICENSE("GPL");