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(objp: 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(pool: &prison->cell_pool);
70 kfree(objp: 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(element: cell, pool: &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(bl: &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(block: (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(lhs: key, rhs: &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(bl: &cell->bios, bio: inmate);
161 *cell_result = cell;
162 return 1;
163 }
164 }
165
166 __setup_new_cell(key, holder: inmate, cell: cell_prealloc);
167 *cell_result = cell_prealloc;
168
169 rb_link_node(node: &cell_prealloc->node, parent, rb_link: 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, num_locks: prison->num_locks);
183
184 spin_lock_irq(lock: &prison->regions[l].lock);
185 r = __bio_detain(root: &prison->regions[l].cell, key, inmate, cell_prealloc, cell_result);
186 spin_unlock_irq(lock: &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
201/*
202 * @inmates must have been initialised prior to this call
203 */
204static void __cell_release(struct rb_root *root,
205 struct dm_bio_prison_cell *cell,
206 struct bio_list *inmates)
207{
208 rb_erase(&cell->node, root);
209
210 if (inmates) {
211 if (cell->holder)
212 bio_list_add(bl: inmates, bio: cell->holder);
213 bio_list_merge(bl: inmates, bl2: &cell->bios);
214 }
215}
216
217void dm_cell_release(struct dm_bio_prison *prison,
218 struct dm_bio_prison_cell *cell,
219 struct bio_list *bios)
220{
221 unsigned l = lock_nr(key: &cell->key, num_locks: prison->num_locks);
222
223 spin_lock_irq(lock: &prison->regions[l].lock);
224 __cell_release(root: &prison->regions[l].cell, cell, inmates: bios);
225 spin_unlock_irq(lock: &prison->regions[l].lock);
226}
227EXPORT_SYMBOL_GPL(dm_cell_release);
228
229/*
230 * Sometimes we don't want the holder, just the additional bios.
231 */
232static void __cell_release_no_holder(struct rb_root *root,
233 struct dm_bio_prison_cell *cell,
234 struct bio_list *inmates)
235{
236 rb_erase(&cell->node, root);
237 bio_list_merge(bl: inmates, bl2: &cell->bios);
238}
239
240void dm_cell_release_no_holder(struct dm_bio_prison *prison,
241 struct dm_bio_prison_cell *cell,
242 struct bio_list *inmates)
243{
244 unsigned l = lock_nr(key: &cell->key, num_locks: prison->num_locks);
245 unsigned long flags;
246
247 spin_lock_irqsave(&prison->regions[l].lock, flags);
248 __cell_release_no_holder(root: &prison->regions[l].cell, cell, inmates);
249 spin_unlock_irqrestore(lock: &prison->regions[l].lock, flags);
250}
251EXPORT_SYMBOL_GPL(dm_cell_release_no_holder);
252
253void dm_cell_error(struct dm_bio_prison *prison,
254 struct dm_bio_prison_cell *cell, blk_status_t error)
255{
256 struct bio_list bios;
257 struct bio *bio;
258
259 bio_list_init(bl: &bios);
260 dm_cell_release(prison, cell, &bios);
261
262 while ((bio = bio_list_pop(bl: &bios))) {
263 bio->bi_status = error;
264 bio_endio(bio);
265 }
266}
267EXPORT_SYMBOL_GPL(dm_cell_error);
268
269void dm_cell_visit_release(struct dm_bio_prison *prison,
270 void (*visit_fn)(void *, struct dm_bio_prison_cell *),
271 void *context,
272 struct dm_bio_prison_cell *cell)
273{
274 unsigned l = lock_nr(key: &cell->key, num_locks: prison->num_locks);
275 spin_lock_irq(lock: &prison->regions[l].lock);
276 visit_fn(context, cell);
277 rb_erase(&cell->node, &prison->regions[l].cell);
278 spin_unlock_irq(lock: &prison->regions[l].lock);
279}
280EXPORT_SYMBOL_GPL(dm_cell_visit_release);
281
282/*----------------------------------------------------------------*/
283
284#define DEFERRED_SET_SIZE 64
285
286struct dm_deferred_entry {
287 struct dm_deferred_set *ds;
288 unsigned int count;
289 struct list_head work_items;
290};
291
292struct dm_deferred_set {
293 spinlock_t lock;
294 unsigned int current_entry;
295 unsigned int 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(list: &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(objp: 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(lock: &ds->lock, flags);
336
337 return entry;
338}
339EXPORT_SYMBOL_GPL(dm_deferred_entry_inc);
340
341static unsigned int ds_next(unsigned int 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(list: &ds->entries[ds->sweeper].work_items, head);
351 ds->sweeper = ds_next(index: ds->sweeper);
352 }
353
354 if ((ds->sweeper == ds->current_entry) && !ds->entries[ds->sweeper].count)
355 list_splice_init(list: &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(ds: entry->ds, head);
366 spin_unlock_irqrestore(lock: &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 int next_entry;
377
378 spin_lock_irq(lock: &ds->lock);
379 if ((ds->sweeper == ds->current_entry) &&
380 !ds->entries[ds->current_entry].count)
381 r = 0;
382 else {
383 list_add(new: work, head: &ds->entries[ds->current_entry].work_items);
384 next_entry = ds_next(index: ds->current_entry);
385 if (!ds->entries[next_entry].count)
386 ds->current_entry = next_entry;
387 }
388 spin_unlock_irq(lock: &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(s: _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
435bad:
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@lists.linux.dev>");
458MODULE_LICENSE("GPL");
459

source code of linux/drivers/md/dm-bio-prison-v1.c