1/*
2 * Copyright (C) 2012-2017 Red Hat, Inc.
3 *
4 * This file is released under the GPL.
5 */
6
7#include "dm.h"
8#include "dm-bio-prison-v2.h"
9
10#include <linux/spinlock.h>
11#include <linux/mempool.h>
12#include <linux/module.h>
13#include <linux/slab.h>
14#include <linux/rwsem.h>
15
16/*----------------------------------------------------------------*/
17
18#define MIN_CELLS 1024
19
20struct dm_bio_prison_v2 {
21 struct workqueue_struct *wq;
22
23 spinlock_t lock;
24 struct rb_root cells;
25 mempool_t cell_pool;
26};
27
28static struct kmem_cache *_cell_cache;
29
30/*----------------------------------------------------------------*/
31
32/*
33 * @nr_cells should be the number of cells you want in use _concurrently_.
34 * Don't confuse it with the number of distinct keys.
35 */
36struct dm_bio_prison_v2 *dm_bio_prison_create_v2(struct workqueue_struct *wq)
37{
38 struct dm_bio_prison_v2 *prison = kzalloc(sizeof(*prison), GFP_KERNEL);
39 int ret;
40
41 if (!prison)
42 return NULL;
43
44 prison->wq = wq;
45 spin_lock_init(&prison->lock);
46
47 ret = mempool_init_slab_pool(&prison->cell_pool, MIN_CELLS, _cell_cache);
48 if (ret) {
49 kfree(prison);
50 return NULL;
51 }
52
53 prison->cells = RB_ROOT;
54
55 return prison;
56}
57EXPORT_SYMBOL_GPL(dm_bio_prison_create_v2);
58
59void dm_bio_prison_destroy_v2(struct dm_bio_prison_v2 *prison)
60{
61 mempool_exit(&prison->cell_pool);
62 kfree(prison);
63}
64EXPORT_SYMBOL_GPL(dm_bio_prison_destroy_v2);
65
66struct dm_bio_prison_cell_v2 *dm_bio_prison_alloc_cell_v2(struct dm_bio_prison_v2 *prison, gfp_t gfp)
67{
68 return mempool_alloc(&prison->cell_pool, gfp);
69}
70EXPORT_SYMBOL_GPL(dm_bio_prison_alloc_cell_v2);
71
72void dm_bio_prison_free_cell_v2(struct dm_bio_prison_v2 *prison,
73 struct dm_bio_prison_cell_v2 *cell)
74{
75 mempool_free(cell, &prison->cell_pool);
76}
77EXPORT_SYMBOL_GPL(dm_bio_prison_free_cell_v2);
78
79static void __setup_new_cell(struct dm_cell_key_v2 *key,
80 struct dm_bio_prison_cell_v2 *cell)
81{
82 memset(cell, 0, sizeof(*cell));
83 memcpy(&cell->key, key, sizeof(cell->key));
84 bio_list_init(&cell->bios);
85}
86
87static int cmp_keys(struct dm_cell_key_v2 *lhs,
88 struct dm_cell_key_v2 *rhs)
89{
90 if (lhs->virtual < rhs->virtual)
91 return -1;
92
93 if (lhs->virtual > rhs->virtual)
94 return 1;
95
96 if (lhs->dev < rhs->dev)
97 return -1;
98
99 if (lhs->dev > rhs->dev)
100 return 1;
101
102 if (lhs->block_end <= rhs->block_begin)
103 return -1;
104
105 if (lhs->block_begin >= rhs->block_end)
106 return 1;
107
108 return 0;
109}
110
111/*
112 * Returns true if node found, otherwise it inserts a new one.
113 */
114static bool __find_or_insert(struct dm_bio_prison_v2 *prison,
115 struct dm_cell_key_v2 *key,
116 struct dm_bio_prison_cell_v2 *cell_prealloc,
117 struct dm_bio_prison_cell_v2 **result)
118{
119 int r;
120 struct rb_node **new = &prison->cells.rb_node, *parent = NULL;
121
122 while (*new) {
123 struct dm_bio_prison_cell_v2 *cell =
124 rb_entry(*new, struct dm_bio_prison_cell_v2, node);
125
126 r = cmp_keys(key, &cell->key);
127
128 parent = *new;
129 if (r < 0)
130 new = &((*new)->rb_left);
131
132 else if (r > 0)
133 new = &((*new)->rb_right);
134
135 else {
136 *result = cell;
137 return true;
138 }
139 }
140
141 __setup_new_cell(key, cell_prealloc);
142 *result = cell_prealloc;
143 rb_link_node(&cell_prealloc->node, parent, new);
144 rb_insert_color(&cell_prealloc->node, &prison->cells);
145
146 return false;
147}
148
149static bool __get(struct dm_bio_prison_v2 *prison,
150 struct dm_cell_key_v2 *key,
151 unsigned lock_level,
152 struct bio *inmate,
153 struct dm_bio_prison_cell_v2 *cell_prealloc,
154 struct dm_bio_prison_cell_v2 **cell)
155{
156 if (__find_or_insert(prison, key, cell_prealloc, cell)) {
157 if ((*cell)->exclusive_lock) {
158 if (lock_level <= (*cell)->exclusive_level) {
159 bio_list_add(&(*cell)->bios, inmate);
160 return false;
161 }
162 }
163
164 (*cell)->shared_count++;
165
166 } else
167 (*cell)->shared_count = 1;
168
169 return true;
170}
171
172bool dm_cell_get_v2(struct dm_bio_prison_v2 *prison,
173 struct dm_cell_key_v2 *key,
174 unsigned lock_level,
175 struct bio *inmate,
176 struct dm_bio_prison_cell_v2 *cell_prealloc,
177 struct dm_bio_prison_cell_v2 **cell_result)
178{
179 int r;
180 unsigned long flags;
181
182 spin_lock_irqsave(&prison->lock, flags);
183 r = __get(prison, key, lock_level, inmate, cell_prealloc, cell_result);
184 spin_unlock_irqrestore(&prison->lock, flags);
185
186 return r;
187}
188EXPORT_SYMBOL_GPL(dm_cell_get_v2);
189
190static bool __put(struct dm_bio_prison_v2 *prison,
191 struct dm_bio_prison_cell_v2 *cell)
192{
193 BUG_ON(!cell->shared_count);
194 cell->shared_count--;
195
196 // FIXME: shared locks granted above the lock level could starve this
197 if (!cell->shared_count) {
198 if (cell->exclusive_lock){
199 if (cell->quiesce_continuation) {
200 queue_work(prison->wq, cell->quiesce_continuation);
201 cell->quiesce_continuation = NULL;
202 }
203 } else {
204 rb_erase(&cell->node, &prison->cells);
205 return true;
206 }
207 }
208
209 return false;
210}
211
212bool dm_cell_put_v2(struct dm_bio_prison_v2 *prison,
213 struct dm_bio_prison_cell_v2 *cell)
214{
215 bool r;
216 unsigned long flags;
217
218 spin_lock_irqsave(&prison->lock, flags);
219 r = __put(prison, cell);
220 spin_unlock_irqrestore(&prison->lock, flags);
221
222 return r;
223}
224EXPORT_SYMBOL_GPL(dm_cell_put_v2);
225
226static int __lock(struct dm_bio_prison_v2 *prison,
227 struct dm_cell_key_v2 *key,
228 unsigned lock_level,
229 struct dm_bio_prison_cell_v2 *cell_prealloc,
230 struct dm_bio_prison_cell_v2 **cell_result)
231{
232 struct dm_bio_prison_cell_v2 *cell;
233
234 if (__find_or_insert(prison, key, cell_prealloc, &cell)) {
235 if (cell->exclusive_lock)
236 return -EBUSY;
237
238 cell->exclusive_lock = true;
239 cell->exclusive_level = lock_level;
240 *cell_result = cell;
241
242 // FIXME: we don't yet know what level these shared locks
243 // were taken at, so have to quiesce them all.
244 return cell->shared_count > 0;
245
246 } else {
247 cell = cell_prealloc;
248 cell->shared_count = 0;
249 cell->exclusive_lock = true;
250 cell->exclusive_level = lock_level;
251 *cell_result = cell;
252 }
253
254 return 0;
255}
256
257int dm_cell_lock_v2(struct dm_bio_prison_v2 *prison,
258 struct dm_cell_key_v2 *key,
259 unsigned lock_level,
260 struct dm_bio_prison_cell_v2 *cell_prealloc,
261 struct dm_bio_prison_cell_v2 **cell_result)
262{
263 int r;
264 unsigned long flags;
265
266 spin_lock_irqsave(&prison->lock, flags);
267 r = __lock(prison, key, lock_level, cell_prealloc, cell_result);
268 spin_unlock_irqrestore(&prison->lock, flags);
269
270 return r;
271}
272EXPORT_SYMBOL_GPL(dm_cell_lock_v2);
273
274static void __quiesce(struct dm_bio_prison_v2 *prison,
275 struct dm_bio_prison_cell_v2 *cell,
276 struct work_struct *continuation)
277{
278 if (!cell->shared_count)
279 queue_work(prison->wq, continuation);
280 else
281 cell->quiesce_continuation = continuation;
282}
283
284void dm_cell_quiesce_v2(struct dm_bio_prison_v2 *prison,
285 struct dm_bio_prison_cell_v2 *cell,
286 struct work_struct *continuation)
287{
288 unsigned long flags;
289
290 spin_lock_irqsave(&prison->lock, flags);
291 __quiesce(prison, cell, continuation);
292 spin_unlock_irqrestore(&prison->lock, flags);
293}
294EXPORT_SYMBOL_GPL(dm_cell_quiesce_v2);
295
296static int __promote(struct dm_bio_prison_v2 *prison,
297 struct dm_bio_prison_cell_v2 *cell,
298 unsigned new_lock_level)
299{
300 if (!cell->exclusive_lock)
301 return -EINVAL;
302
303 cell->exclusive_level = new_lock_level;
304 return cell->shared_count > 0;
305}
306
307int dm_cell_lock_promote_v2(struct dm_bio_prison_v2 *prison,
308 struct dm_bio_prison_cell_v2 *cell,
309 unsigned new_lock_level)
310{
311 int r;
312 unsigned long flags;
313
314 spin_lock_irqsave(&prison->lock, flags);
315 r = __promote(prison, cell, new_lock_level);
316 spin_unlock_irqrestore(&prison->lock, flags);
317
318 return r;
319}
320EXPORT_SYMBOL_GPL(dm_cell_lock_promote_v2);
321
322static bool __unlock(struct dm_bio_prison_v2 *prison,
323 struct dm_bio_prison_cell_v2 *cell,
324 struct bio_list *bios)
325{
326 BUG_ON(!cell->exclusive_lock);
327
328 bio_list_merge(bios, &cell->bios);
329 bio_list_init(&cell->bios);
330
331 if (cell->shared_count) {
332 cell->exclusive_lock = 0;
333 return false;
334 }
335
336 rb_erase(&cell->node, &prison->cells);
337 return true;
338}
339
340bool dm_cell_unlock_v2(struct dm_bio_prison_v2 *prison,
341 struct dm_bio_prison_cell_v2 *cell,
342 struct bio_list *bios)
343{
344 bool r;
345 unsigned long flags;
346
347 spin_lock_irqsave(&prison->lock, flags);
348 r = __unlock(prison, cell, bios);
349 spin_unlock_irqrestore(&prison->lock, flags);
350
351 return r;
352}
353EXPORT_SYMBOL_GPL(dm_cell_unlock_v2);
354
355/*----------------------------------------------------------------*/
356
357int __init dm_bio_prison_init_v2(void)
358{
359 _cell_cache = KMEM_CACHE(dm_bio_prison_cell_v2, 0);
360 if (!_cell_cache)
361 return -ENOMEM;
362
363 return 0;
364}
365
366void dm_bio_prison_exit_v2(void)
367{
368 kmem_cache_destroy(_cell_cache);
369 _cell_cache = NULL;
370}
371