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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");