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 | |
21 | struct prison_region { |
22 | spinlock_t lock; |
23 | struct rb_root cell; |
24 | } ____cacheline_aligned_in_smp; |
25 | |
26 | struct dm_bio_prison { |
27 | mempool_t cell_pool; |
28 | unsigned int num_locks; |
29 | struct prison_region regions[] __counted_by(num_locks); |
30 | }; |
31 | |
32 | static 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 | */ |
40 | struct 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(pool: &prison->cell_pool, MIN_CELLS, kc: _cell_cache); |
58 | if (ret) { |
59 | kfree(objp: prison); |
60 | return NULL; |
61 | } |
62 | |
63 | return prison; |
64 | } |
65 | EXPORT_SYMBOL_GPL(dm_bio_prison_create); |
66 | |
67 | void dm_bio_prison_destroy(struct dm_bio_prison *prison) |
68 | { |
69 | mempool_exit(pool: &prison->cell_pool); |
70 | kfree(objp: prison); |
71 | } |
72 | EXPORT_SYMBOL_GPL(dm_bio_prison_destroy); |
73 | |
74 | struct dm_bio_prison_cell *dm_bio_prison_alloc_cell(struct dm_bio_prison *prison, gfp_t gfp) |
75 | { |
76 | return mempool_alloc(pool: &prison->cell_pool, gfp_mask: gfp); |
77 | } |
78 | EXPORT_SYMBOL_GPL(dm_bio_prison_alloc_cell); |
79 | |
80 | void 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 | } |
85 | EXPORT_SYMBOL_GPL(dm_bio_prison_free_cell); |
86 | |
87 | static 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 | |
96 | static 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 | |
120 | static 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 | |
126 | bool 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 | } |
136 | EXPORT_SYMBOL(dm_cell_key_has_valid_range); |
137 | |
138 | static 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 | |
175 | static 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 | |
191 | int 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 | } |
199 | EXPORT_SYMBOL_GPL(dm_bio_detain); |
200 | |
201 | int 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 | } |
208 | EXPORT_SYMBOL_GPL(dm_get_cell); |
209 | |
210 | /* |
211 | * @inmates must have been initialised prior to this call |
212 | */ |
213 | static 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(bl: inmates, bio: cell->holder); |
222 | bio_list_merge(bl: inmates, bl2: &cell->bios); |
223 | } |
224 | } |
225 | |
226 | void 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(key: &cell->key, num_locks: prison->num_locks); |
231 | |
232 | spin_lock_irq(lock: &prison->regions[l].lock); |
233 | __cell_release(root: &prison->regions[l].cell, cell, inmates: bios); |
234 | spin_unlock_irq(lock: &prison->regions[l].lock); |
235 | } |
236 | EXPORT_SYMBOL_GPL(dm_cell_release); |
237 | |
238 | /* |
239 | * Sometimes we don't want the holder, just the additional bios. |
240 | */ |
241 | static 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(bl: inmates, bl2: &cell->bios); |
247 | } |
248 | |
249 | void 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(key: &cell->key, num_locks: prison->num_locks); |
254 | unsigned long flags; |
255 | |
256 | spin_lock_irqsave(&prison->regions[l].lock, flags); |
257 | __cell_release_no_holder(root: &prison->regions[l].cell, cell, inmates); |
258 | spin_unlock_irqrestore(lock: &prison->regions[l].lock, flags); |
259 | } |
260 | EXPORT_SYMBOL_GPL(dm_cell_release_no_holder); |
261 | |
262 | void 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(bl: &bios); |
269 | dm_cell_release(prison, cell, &bios); |
270 | |
271 | while ((bio = bio_list_pop(bl: &bios))) { |
272 | bio->bi_status = error; |
273 | bio_endio(bio); |
274 | } |
275 | } |
276 | EXPORT_SYMBOL_GPL(dm_cell_error); |
277 | |
278 | void 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(key: &cell->key, num_locks: prison->num_locks); |
284 | spin_lock_irq(lock: &prison->regions[l].lock); |
285 | visit_fn(context, cell); |
286 | rb_erase(&cell->node, &prison->regions[l].cell); |
287 | spin_unlock_irq(lock: &prison->regions[l].lock); |
288 | } |
289 | EXPORT_SYMBOL_GPL(dm_cell_visit_release); |
290 | |
291 | static int __promote_or_release(struct rb_root *root, |
292 | struct dm_bio_prison_cell *cell) |
293 | { |
294 | if (bio_list_empty(bl: &cell->bios)) { |
295 | rb_erase(&cell->node, root); |
296 | return 1; |
297 | } |
298 | |
299 | cell->holder = bio_list_pop(bl: &cell->bios); |
300 | return 0; |
301 | } |
302 | |
303 | int 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(key: &cell->key, num_locks: prison->num_locks); |
308 | |
309 | spin_lock_irq(lock: &prison->regions[l].lock); |
310 | r = __promote_or_release(root: &prison->regions[l].cell, cell); |
311 | spin_unlock_irq(lock: &prison->regions[l].lock); |
312 | |
313 | return r; |
314 | } |
315 | EXPORT_SYMBOL_GPL(dm_cell_promote_or_release); |
316 | |
317 | /*----------------------------------------------------------------*/ |
318 | |
319 | #define DEFERRED_SET_SIZE 64 |
320 | |
321 | struct dm_deferred_entry { |
322 | struct dm_deferred_set *ds; |
323 | unsigned int count; |
324 | struct list_head work_items; |
325 | }; |
326 | |
327 | struct 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 | |
334 | struct dm_deferred_set *dm_deferred_set_create(void) |
335 | { |
336 | int i; |
337 | struct dm_deferred_set *ds; |
338 | |
339 | ds = kmalloc(size: 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(list: &ds->entries[i].work_items); |
350 | } |
351 | |
352 | return ds; |
353 | } |
354 | EXPORT_SYMBOL_GPL(dm_deferred_set_create); |
355 | |
356 | void dm_deferred_set_destroy(struct dm_deferred_set *ds) |
357 | { |
358 | kfree(objp: ds); |
359 | } |
360 | EXPORT_SYMBOL_GPL(dm_deferred_set_destroy); |
361 | |
362 | struct 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(lock: &ds->lock, flags); |
371 | |
372 | return entry; |
373 | } |
374 | EXPORT_SYMBOL_GPL(dm_deferred_entry_inc); |
375 | |
376 | static unsigned int ds_next(unsigned int index) |
377 | { |
378 | return (index + 1) % DEFERRED_SET_SIZE; |
379 | } |
380 | |
381 | static 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(list: &ds->entries[ds->sweeper].work_items, head); |
386 | ds->sweeper = ds_next(index: ds->sweeper); |
387 | } |
388 | |
389 | if ((ds->sweeper == ds->current_entry) && !ds->entries[ds->sweeper].count) |
390 | list_splice_init(list: &ds->entries[ds->sweeper].work_items, head); |
391 | } |
392 | |
393 | void 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(ds: entry->ds, head); |
401 | spin_unlock_irqrestore(lock: &entry->ds->lock, flags); |
402 | } |
403 | EXPORT_SYMBOL_GPL(dm_deferred_entry_dec); |
404 | |
405 | /* |
406 | * Returns 1 if deferred or 0 if no pending items to delay job. |
407 | */ |
408 | int 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(lock: &ds->lock); |
414 | if ((ds->sweeper == ds->current_entry) && |
415 | !ds->entries[ds->current_entry].count) |
416 | r = 0; |
417 | else { |
418 | list_add(new: work, head: &ds->entries[ds->current_entry].work_items); |
419 | next_entry = ds_next(index: ds->current_entry); |
420 | if (!ds->entries[next_entry].count) |
421 | ds->current_entry = next_entry; |
422 | } |
423 | spin_unlock_irq(lock: &ds->lock); |
424 | |
425 | return r; |
426 | } |
427 | EXPORT_SYMBOL_GPL(dm_deferred_set_add_work); |
428 | |
429 | /*----------------------------------------------------------------*/ |
430 | |
431 | static 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 | |
440 | static void dm_bio_prison_exit_v1(void) |
441 | { |
442 | kmem_cache_destroy(s: _cell_cache); |
443 | _cell_cache = NULL; |
444 | } |
445 | |
446 | static int (*_inits[])(void) __initdata = { |
447 | dm_bio_prison_init_v1, |
448 | dm_bio_prison_init_v2, |
449 | }; |
450 | |
451 | static void (*_exits[])(void) = { |
452 | dm_bio_prison_exit_v1, |
453 | dm_bio_prison_exit_v2, |
454 | }; |
455 | |
456 | static 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 | |
470 | bad: |
471 | while (i--) |
472 | _exits[i](); |
473 | |
474 | return r; |
475 | } |
476 | |
477 | static 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 | */ |
488 | module_init(dm_bio_prison_init); |
489 | module_exit(dm_bio_prison_exit); |
490 | |
491 | MODULE_DESCRIPTION(DM_NAME " bio prison" ); |
492 | MODULE_AUTHOR("Joe Thornber <dm-devel@redhat.com>" ); |
493 | MODULE_LICENSE("GPL" ); |
494 | |