Home Home > GIT Browse
summaryrefslogtreecommitdiff
blob: 8ce3a1a588cfd064b0249ea0f90e32934b81858e (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
/*
 * Copyright (C) 2012-2017 Red Hat, Inc.
 *
 * This file is released under the GPL.
 */

#include "dm.h"
#include "dm-bio-prison-v2.h"

#include <linux/spinlock.h>
#include <linux/mempool.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/rwsem.h>

/*----------------------------------------------------------------*/

#define MIN_CELLS 1024

struct dm_bio_prison_v2 {
	struct workqueue_struct *wq;

	spinlock_t lock;
	mempool_t *cell_pool;
	struct rb_root cells;
};

static struct kmem_cache *_cell_cache;

/*----------------------------------------------------------------*/

/*
 * @nr_cells should be the number of cells you want in use _concurrently_.
 * Don't confuse it with the number of distinct keys.
 */
struct dm_bio_prison_v2 *dm_bio_prison_create_v2(struct workqueue_struct *wq)
{
	struct dm_bio_prison_v2 *prison = kmalloc(sizeof(*prison), GFP_KERNEL);

	if (!prison)
		return NULL;

	prison->wq = wq;
	spin_lock_init(&prison->lock);

	prison->cell_pool = mempool_create_slab_pool(MIN_CELLS, _cell_cache);
	if (!prison->cell_pool) {
		kfree(prison);
		return NULL;
	}

	prison->cells = RB_ROOT;

	return prison;
}
EXPORT_SYMBOL_GPL(dm_bio_prison_create_v2);

void dm_bio_prison_destroy_v2(struct dm_bio_prison_v2 *prison)
{
	mempool_destroy(prison->cell_pool);
	kfree(prison);
}
EXPORT_SYMBOL_GPL(dm_bio_prison_destroy_v2);

struct dm_bio_prison_cell_v2 *dm_bio_prison_alloc_cell_v2(struct dm_bio_prison_v2 *prison, gfp_t gfp)
{
	return mempool_alloc(prison->cell_pool, gfp);
}
EXPORT_SYMBOL_GPL(dm_bio_prison_alloc_cell_v2);

void dm_bio_prison_free_cell_v2(struct dm_bio_prison_v2 *prison,
				struct dm_bio_prison_cell_v2 *cell)
{
	mempool_free(cell, prison->cell_pool);
}
EXPORT_SYMBOL_GPL(dm_bio_prison_free_cell_v2);

static void __setup_new_cell(struct dm_cell_key_v2 *key,
			     struct dm_bio_prison_cell_v2 *cell)
{
	memset(cell, 0, sizeof(*cell));
	memcpy(&cell->key, key, sizeof(cell->key));
	bio_list_init(&cell->bios);
}

static int cmp_keys(struct dm_cell_key_v2 *lhs,
		    struct dm_cell_key_v2 *rhs)
{
	if (lhs->virtual < rhs->virtual)
		return -1;

	if (lhs->virtual > rhs->virtual)
		return 1;

	if (lhs->dev < rhs->dev)
		return -1;

	if (lhs->dev > rhs->dev)
		return 1;

	if (lhs->block_end <= rhs->block_begin)
		return -1;

	if (lhs->block_begin >= rhs->block_end)
		return 1;

	return 0;
}

/*
 * Returns true if node found, otherwise it inserts a new one.
 */
static bool __find_or_insert(struct dm_bio_prison_v2 *prison,
			     struct dm_cell_key_v2 *key,
			     struct dm_bio_prison_cell_v2 *cell_prealloc,
			     struct dm_bio_prison_cell_v2 **result)
{
	int r;
	struct rb_node **new = &prison->cells.rb_node, *parent = NULL;

	while (*new) {
		struct dm_bio_prison_cell_v2 *cell =
			rb_entry(*new, struct dm_bio_prison_cell_v2, node);

		r = cmp_keys(key, &cell->key);

		parent = *new;
		if (r < 0)
			new = &((*new)->rb_left);

		else if (r > 0)
			new = &((*new)->rb_right);

		else {
			*result = cell;
			return true;
		}
	}

	__setup_new_cell(key, cell_prealloc);
	*result = cell_prealloc;
	rb_link_node(&cell_prealloc->node, parent, new);
	rb_insert_color(&cell_prealloc->node, &prison->cells);

	return false;
}

static bool __get(struct dm_bio_prison_v2 *prison,
		  struct dm_cell_key_v2 *key,
		  unsigned lock_level,
		  struct bio *inmate,
		  struct dm_bio_prison_cell_v2 *cell_prealloc,
		  struct dm_bio_prison_cell_v2 **cell)
{
	if (__find_or_insert(prison, key, cell_prealloc, cell)) {
		if ((*cell)->exclusive_lock) {
			if (lock_level <= (*cell)->exclusive_level) {
				bio_list_add(&(*cell)->bios, inmate);
				return false;
			}
		}

		(*cell)->shared_count++;

	} else
		(*cell)->shared_count = 1;

	return true;
}

bool dm_cell_get_v2(struct dm_bio_prison_v2 *prison,
		    struct dm_cell_key_v2 *key,
		    unsigned lock_level,
		    struct bio *inmate,
		    struct dm_bio_prison_cell_v2 *cell_prealloc,
		    struct dm_bio_prison_cell_v2 **cell_result)
{
	int r;
	unsigned long flags;

	spin_lock_irqsave(&prison->lock, flags);
	r = __get(prison, key, lock_level, inmate, cell_prealloc, cell_result);
	spin_unlock_irqrestore(&prison->lock, flags);

	return r;
}
EXPORT_SYMBOL_GPL(dm_cell_get_v2);

static bool __put(struct dm_bio_prison_v2 *prison,
		  struct dm_bio_prison_cell_v2 *cell)
{
	BUG_ON(!cell->shared_count);
	cell->shared_count--;

	// FIXME: shared locks granted above the lock level could starve this
	if (!cell->shared_count) {
		if (cell->exclusive_lock){
			if (cell->quiesce_continuation) {
				queue_work(prison->wq, cell->quiesce_continuation);
				cell->quiesce_continuation = NULL;
			}
		} else {
			rb_erase(&cell->node, &prison->cells);
			return true;
		}
	}

	return false;
}

bool dm_cell_put_v2(struct dm_bio_prison_v2 *prison,
		    struct dm_bio_prison_cell_v2 *cell)
{
	bool r;
	unsigned long flags;

	spin_lock_irqsave(&prison->lock, flags);
	r = __put(prison, cell);
	spin_unlock_irqrestore(&prison->lock, flags);

	return r;
}
EXPORT_SYMBOL_GPL(dm_cell_put_v2);

static int __lock(struct dm_bio_prison_v2 *prison,
		  struct dm_cell_key_v2 *key,
		  unsigned lock_level,
		  struct dm_bio_prison_cell_v2 *cell_prealloc,
		  struct dm_bio_prison_cell_v2 **cell_result)
{
	struct dm_bio_prison_cell_v2 *cell;

	if (__find_or_insert(prison, key, cell_prealloc, &cell)) {
		if (cell->exclusive_lock)
			return -EBUSY;

		cell->exclusive_lock = true;
		cell->exclusive_level = lock_level;
		*cell_result = cell;

		// FIXME: we don't yet know what level these shared locks
		// were taken at, so have to quiesce them all.
		return cell->shared_count > 0;

	} else {
		cell = cell_prealloc;
		cell->shared_count = 0;
		cell->exclusive_lock = true;
		cell->exclusive_level = lock_level;
		*cell_result = cell;
	}

	return 0;
}

int dm_cell_lock_v2(struct dm_bio_prison_v2 *prison,
		    struct dm_cell_key_v2 *key,
		    unsigned lock_level,
		    struct dm_bio_prison_cell_v2 *cell_prealloc,
		    struct dm_bio_prison_cell_v2 **cell_result)
{
	int r;
	unsigned long flags;

	spin_lock_irqsave(&prison->lock, flags);
	r = __lock(prison, key, lock_level, cell_prealloc, cell_result);
	spin_unlock_irqrestore(&prison->lock, flags);

	return r;
}
EXPORT_SYMBOL_GPL(dm_cell_lock_v2);

static void __quiesce(struct dm_bio_prison_v2 *prison,
		      struct dm_bio_prison_cell_v2 *cell,
		      struct work_struct *continuation)
{
	if (!cell->shared_count)
		queue_work(prison->wq, continuation);
	else
		cell->quiesce_continuation = continuation;
}

void dm_cell_quiesce_v2(struct dm_bio_prison_v2 *prison,
			struct dm_bio_prison_cell_v2 *cell,
			struct work_struct *continuation)
{
	unsigned long flags;

	spin_lock_irqsave(&prison->lock, flags);
	__quiesce(prison, cell, continuation);
	spin_unlock_irqrestore(&prison->lock, flags);
}
EXPORT_SYMBOL_GPL(dm_cell_quiesce_v2);

static int __promote(struct dm_bio_prison_v2 *prison,
		     struct dm_bio_prison_cell_v2 *cell,
		     unsigned new_lock_level)
{
	if (!cell->exclusive_lock)
		return -EINVAL;

	cell->exclusive_level = new_lock_level;
	return cell->shared_count > 0;
}

int dm_cell_lock_promote_v2(struct dm_bio_prison_v2 *prison,
			    struct dm_bio_prison_cell_v2 *cell,
			    unsigned new_lock_level)
{
	int r;
	unsigned long flags;

	spin_lock_irqsave(&prison->lock, flags);
	r = __promote(prison, cell, new_lock_level);
	spin_unlock_irqrestore(&prison->lock, flags);

	return r;
}
EXPORT_SYMBOL_GPL(dm_cell_lock_promote_v2);

static bool __unlock(struct dm_bio_prison_v2 *prison,
		     struct dm_bio_prison_cell_v2 *cell,
		     struct bio_list *bios)
{
	BUG_ON(!cell->exclusive_lock);

	bio_list_merge(bios, &cell->bios);
	bio_list_init(&cell->bios);

	if (cell->shared_count) {
		cell->exclusive_lock = 0;
		return false;
	}

	rb_erase(&cell->node, &prison->cells);
	return true;
}

bool dm_cell_unlock_v2(struct dm_bio_prison_v2 *prison,
		       struct dm_bio_prison_cell_v2 *cell,
		       struct bio_list *bios)
{
	bool r;
	unsigned long flags;

	spin_lock_irqsave(&prison->lock, flags);
	r = __unlock(prison, cell, bios);
	spin_unlock_irqrestore(&prison->lock, flags);

	return r;
}
EXPORT_SYMBOL_GPL(dm_cell_unlock_v2);

/*----------------------------------------------------------------*/

int __init dm_bio_prison_init_v2(void)
{
	_cell_cache = KMEM_CACHE(dm_bio_prison_cell_v2, 0);
	if (!_cell_cache)
		return -ENOMEM;

	return 0;
}

void dm_bio_prison_exit_v2(void)
{
	kmem_cache_destroy(_cell_cache);
	_cell_cache = NULL;
}