[GitHub/mt8127/android_kernel_alcatel_ttab.git] / drivers / md / dm-cache-policy-cleaner.c

/*
 * Copyright (C) 2012 Red Hat. All rights reserved.
 *
 * writeback cache policy supporting flushing out dirty cache blocks.
 *
 * This file is released under the GPL.
 */

#include "dm-cache-policy.h"
#include "dm.h"

#include <linux/hash.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>

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

#define DM_MSG_PREFIX "cache cleaner"

/* Cache entry struct. */
struct wb_cache_entry {
	struct list_head list;
	struct hlist_node hlist;

	dm_oblock_t oblock;
	dm_cblock_t cblock;
	bool dirty:1;
	bool pending:1;
};

struct hash {
	struct hlist_head *table;
	dm_block_t hash_bits;
	unsigned nr_buckets;
};

struct policy {
	struct dm_cache_policy policy;
	spinlock_t lock;

	struct list_head free;
	struct list_head clean;
	struct list_head clean_pending;
	struct list_head dirty;

	/*
	 * We know exactly how many cblocks will be needed,
	 * so we can allocate them up front.
	 */
	dm_cblock_t cache_size, nr_cblocks_allocated;
	struct wb_cache_entry *cblocks;
	struct hash chash;
};

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

/*
 * Low-level functions.
 */
static unsigned next_power(unsigned n, unsigned min)
{
	return roundup_pow_of_two(max(n, min));
}

static struct policy *to_policy(struct dm_cache_policy *p)
{
	return container_of(p, struct policy, policy);
}

static struct list_head *list_pop(struct list_head *q)
{
	struct list_head *r = q->next;

	list_del(r);

	return r;
}

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

/* Allocate/free various resources. */
static int alloc_hash(struct hash *hash, unsigned elts)
{
	hash->nr_buckets = next_power(elts >> 4, 16);
	hash->hash_bits = ffs(hash->nr_buckets) - 1;
	hash->table = vzalloc(sizeof(*hash->table) * hash->nr_buckets);

	return hash->table ? 0 : -ENOMEM;
}

static void free_hash(struct hash *hash)
{
	vfree(hash->table);
}

static int alloc_cache_blocks_with_hash(struct policy *p, dm_cblock_t cache_size)
{
	int r = -ENOMEM;

	p->cblocks = vzalloc(sizeof(*p->cblocks) * from_cblock(cache_size));
	if (p->cblocks) {
		unsigned u = from_cblock(cache_size);

		while (u--)
			list_add(&p->cblocks[u].list, &p->free);

		p->nr_cblocks_allocated = 0;

		/* Cache entries hash. */
		r = alloc_hash(&p->chash, from_cblock(cache_size));
		if (r)
			vfree(p->cblocks);
	}

	return r;
}

static void free_cache_blocks_and_hash(struct policy *p)
{
	free_hash(&p->chash);
	vfree(p->cblocks);
}

static struct wb_cache_entry *alloc_cache_entry(struct policy *p)
{
	struct wb_cache_entry *e;

	BUG_ON(from_cblock(p->nr_cblocks_allocated) >= from_cblock(p->cache_size));

	e = list_entry(list_pop(&p->free), struct wb_cache_entry, list);
	p->nr_cblocks_allocated = to_cblock(from_cblock(p->nr_cblocks_allocated) + 1);

	return e;
}

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

/* Hash functions (lookup, insert, remove). */
static struct wb_cache_entry *lookup_cache_entry(struct policy *p, dm_oblock_t oblock)
{
	struct hash *hash = &p->chash;
	unsigned h = hash_64(from_oblock(oblock), hash->hash_bits);
	struct wb_cache_entry *cur;
	struct hlist_head *bucket = &hash->table[h];

	hlist_for_each_entry(cur, bucket, hlist) {
		if (cur->oblock == oblock) {
			/* Move upfront bucket for faster access. */
			hlist_del(&cur->hlist);
			hlist_add_head(&cur->hlist, bucket);
			return cur;
		}
	}

	return NULL;
}

static void insert_cache_hash_entry(struct policy *p, struct wb_cache_entry *e)
{
	unsigned h = hash_64(from_oblock(e->oblock), p->chash.hash_bits);

	hlist_add_head(&e->hlist, &p->chash.table[h]);
}

static void remove_cache_hash_entry(struct wb_cache_entry *e)
{
	hlist_del(&e->hlist);
}

/* Public interface (see dm-cache-policy.h */
static int wb_map(struct dm_cache_policy *pe, dm_oblock_t oblock,
		  bool can_block, bool can_migrate, bool discarded_oblock,
		  struct bio *bio, struct policy_result *result)
{
	struct policy *p = to_policy(pe);
	struct wb_cache_entry *e;
	unsigned long flags;

	result->op = POLICY_MISS;

	if (can_block)
		spin_lock_irqsave(&p->lock, flags);

	else if (!spin_trylock_irqsave(&p->lock, flags))
		return -EWOULDBLOCK;

	e = lookup_cache_entry(p, oblock);
	if (e) {
		result->op = POLICY_HIT;
		result->cblock = e->cblock;

	}

	spin_unlock_irqrestore(&p->lock, flags);

	return 0;
}

static int wb_lookup(struct dm_cache_policy *pe, dm_oblock_t oblock, dm_cblock_t *cblock)
{
	int r;
	struct policy *p = to_policy(pe);
	struct wb_cache_entry *e;
	unsigned long flags;

	if (!spin_trylock_irqsave(&p->lock, flags))
		return -EWOULDBLOCK;

	e = lookup_cache_entry(p, oblock);
	if (e) {
		*cblock = e->cblock;
		r = 0;

	} else
		r = -ENOENT;

	spin_unlock_irqrestore(&p->lock, flags);

	return r;
}

static void __set_clear_dirty(struct dm_cache_policy *pe, dm_oblock_t oblock, bool set)
{
	struct policy *p = to_policy(pe);
	struct wb_cache_entry *e;

	e = lookup_cache_entry(p, oblock);
	BUG_ON(!e);

	if (set) {
		if (!e->dirty) {
			e->dirty = true;
			list_move(&e->list, &p->dirty);
		}

	} else {
		if (e->dirty) {
			e->pending = false;
			e->dirty = false;
			list_move(&e->list, &p->clean);
		}
	}
}

static void wb_set_dirty(struct dm_cache_policy *pe, dm_oblock_t oblock)
{
	struct policy *p = to_policy(pe);
	unsigned long flags;

	spin_lock_irqsave(&p->lock, flags);
	__set_clear_dirty(pe, oblock, true);
	spin_unlock_irqrestore(&p->lock, flags);
}

static void wb_clear_dirty(struct dm_cache_policy *pe, dm_oblock_t oblock)
{
	struct policy *p = to_policy(pe);
	unsigned long flags;

	spin_lock_irqsave(&p->lock, flags);
	__set_clear_dirty(pe, oblock, false);
	spin_unlock_irqrestore(&p->lock, flags);
}

static void add_cache_entry(struct policy *p, struct wb_cache_entry *e)
{
	insert_cache_hash_entry(p, e);
	if (e->dirty)
		list_add(&e->list, &p->dirty);
	else
		list_add(&e->list, &p->clean);
}

static int wb_load_mapping(struct dm_cache_policy *pe,
			   dm_oblock_t oblock, dm_cblock_t cblock,
			   uint32_t hint, bool hint_valid)
{
	int r;
	struct policy *p = to_policy(pe);
	struct wb_cache_entry *e = alloc_cache_entry(p);

	if (e) {
		e->cblock = cblock;
		e->oblock = oblock;
		e->dirty = false; /* blocks default to clean */
		add_cache_entry(p, e);
		r = 0;

	} else
		r = -ENOMEM;

	return r;
}

static void wb_destroy(struct dm_cache_policy *pe)
{
	struct policy *p = to_policy(pe);

	free_cache_blocks_and_hash(p);
	kfree(p);
}

static struct wb_cache_entry *__wb_force_remove_mapping(struct policy *p, dm_oblock_t oblock)
{
	struct wb_cache_entry *r = lookup_cache_entry(p, oblock);

	BUG_ON(!r);

	remove_cache_hash_entry(r);
	list_del(&r->list);

	return r;
}

static void wb_remove_mapping(struct dm_cache_policy *pe, dm_oblock_t oblock)
{
	struct policy *p = to_policy(pe);
	struct wb_cache_entry *e;
	unsigned long flags;

	spin_lock_irqsave(&p->lock, flags);
	e = __wb_force_remove_mapping(p, oblock);
	list_add_tail(&e->list, &p->free);
	BUG_ON(!from_cblock(p->nr_cblocks_allocated));
	p->nr_cblocks_allocated = to_cblock(from_cblock(p->nr_cblocks_allocated) - 1);
	spin_unlock_irqrestore(&p->lock, flags);
}

static void wb_force_mapping(struct dm_cache_policy *pe,
				dm_oblock_t current_oblock, dm_oblock_t oblock)
{
	struct policy *p = to_policy(pe);
	struct wb_cache_entry *e;
	unsigned long flags;

	spin_lock_irqsave(&p->lock, flags);
	e = __wb_force_remove_mapping(p, current_oblock);
	e->oblock = oblock;
	add_cache_entry(p, e);
	spin_unlock_irqrestore(&p->lock, flags);
}

static struct wb_cache_entry *get_next_dirty_entry(struct policy *p)
{
	struct list_head *l;
	struct wb_cache_entry *r;

	if (list_empty(&p->dirty))
		return NULL;

	l = list_pop(&p->dirty);
	r = container_of(l, struct wb_cache_entry, list);
	list_add(l, &p->clean_pending);

	return r;
}

static int wb_writeback_work(struct dm_cache_policy *pe,
			     dm_oblock_t *oblock,
			     dm_cblock_t *cblock)
{
	int r = -ENOENT;
	struct policy *p = to_policy(pe);
	struct wb_cache_entry *e;
	unsigned long flags;

	spin_lock_irqsave(&p->lock, flags);

	e = get_next_dirty_entry(p);
	if (e) {
		*oblock = e->oblock;
		*cblock = e->cblock;
		r = 0;
	}

	spin_unlock_irqrestore(&p->lock, flags);

	return r;
}

static dm_cblock_t wb_residency(struct dm_cache_policy *pe)
{
	return to_policy(pe)->nr_cblocks_allocated;
}

/* Init the policy plugin interface function pointers. */
static void init_policy_functions(struct policy *p)
{
	p->policy.destroy = wb_destroy;
	p->policy.map = wb_map;
	p->policy.lookup = wb_lookup;
	p->policy.set_dirty = wb_set_dirty;
	p->policy.clear_dirty = wb_clear_dirty;
	p->policy.load_mapping = wb_load_mapping;
	p->policy.walk_mappings = NULL;
	p->policy.remove_mapping = wb_remove_mapping;
	p->policy.writeback_work = wb_writeback_work;
	p->policy.force_mapping = wb_force_mapping;
	p->policy.residency = wb_residency;
	p->policy.tick = NULL;
}

static struct dm_cache_policy *wb_create(dm_cblock_t cache_size,
					 sector_t origin_size,
					 sector_t cache_block_size)
{
	int r;
	struct policy *p = kzalloc(sizeof(*p), GFP_KERNEL);

	if (!p)
		return NULL;

	init_policy_functions(p);
	INIT_LIST_HEAD(&p->free);
	INIT_LIST_HEAD(&p->clean);
	INIT_LIST_HEAD(&p->clean_pending);
	INIT_LIST_HEAD(&p->dirty);

	p->cache_size = cache_size;
	spin_lock_init(&p->lock);

	/* Allocate cache entry structs and add them to free list. */
	r = alloc_cache_blocks_with_hash(p, cache_size);
	if (!r)
		return &p->policy;

	kfree(p);

	return NULL;
}
/*----------------------------------------------------------------------------*/

static struct dm_cache_policy_type wb_policy_type = {
	.name = "cleaner",
	.version = {1, 0, 0},
	.hint_size = 0,
	.owner = THIS_MODULE,
	.create = wb_create
};

static int __init wb_init(void)
{
	int r = dm_cache_policy_register(&wb_policy_type);

	if (r < 0)
		DMERR("register failed %d", r);
	else
		DMINFO("version %u.%u.%u loaded",
		       wb_policy_type.version[0],
		       wb_policy_type.version[1],
		       wb_policy_type.version[2]);

	return r;
}

static void __exit wb_exit(void)
{
	dm_cache_policy_unregister(&wb_policy_type);
}

module_init(wb_init);
module_exit(wb_exit);

MODULE_AUTHOR("Heinz Mauelshagen <dm-devel@redhat.com>");
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("cleaner cache policy");
Commit	Line	Data
8735a813 HM	1	/*
	2	* Copyright (C) 2012 Red Hat. All rights reserved.
	3	*
	4	* writeback cache policy supporting flushing out dirty cache blocks.
	5	*
	6	* This file is released under the GPL.
	7	*/
	8
	9	#include "dm-cache-policy.h"
	10	#include "dm.h"
	11
	12	#include <linux/hash.h>
	13	#include <linux/module.h>
	14	#include <linux/slab.h>
	15	#include <linux/vmalloc.h>
	16
	17	/----------------------------------------------------------------/
	18
	19	#define DM_MSG_PREFIX "cache cleaner"
8735a813 HM	20
	21	/* Cache entry struct. */
	22	struct wb_cache_entry {
	23	struct list_head list;
	24	struct hlist_node hlist;
	25
	26	dm_oblock_t oblock;
	27	dm_cblock_t cblock;
	28	bool dirty:1;
	29	bool pending:1;
	30	};
	31
	32	struct hash {
	33	struct hlist_head *table;
	34	dm_block_t hash_bits;
	35	unsigned nr_buckets;
	36	};
	37
	38	struct policy {
	39	struct dm_cache_policy policy;
	40	spinlock_t lock;
	41
	42	struct list_head free;
	43	struct list_head clean;
	44	struct list_head clean_pending;
	45	struct list_head dirty;
	46
	47	/*
	48	* We know exactly how many cblocks will be needed,
	49	* so we can allocate them up front.
	50	*/
	51	dm_cblock_t cache_size, nr_cblocks_allocated;
	52	struct wb_cache_entry *cblocks;
	53	struct hash chash;
	54	};
	55
	56	/----------------------------------------------------------------------------/
	57
	58	/*
	59	* Low-level functions.
	60	*/
	61	static unsigned next_power(unsigned n, unsigned min)
	62	{
	63	return roundup_pow_of_two(max(n, min));
	64	}
	65
	66	static struct policy to_policy(struct dm_cache_policy p)
	67	{
	68	return container_of(p, struct policy, policy);
	69	}
	70
	71	static struct list_head list_pop(struct list_head q)
	72	{
	73	struct list_head *r = q->next;
	74
	75	list_del(r);
	76
	77	return r;
	78	}
	79
	80	/----------------------------------------------------------------------------/
	81
	82	/* Allocate/free various resources. */
	83	static int alloc_hash(struct hash *hash, unsigned elts)
84	{
85	hash->nr_buckets = next_power(elts >> 4, 16);
86	hash->hash_bits = ffs(hash->nr_buckets) - 1;
87	hash->table = vzalloc(sizeof(hash->table) hash->nr_buckets);
88
89	return hash->table ? 0 : -ENOMEM;
90	}
91
92	static void free_hash(struct hash *hash)
93	{
94	vfree(hash->table);
95	}
96
97	static int alloc_cache_blocks_with_hash(struct policy *p, dm_cblock_t cache_size)
98	{
99	int r = -ENOMEM;
100
101	p->cblocks = vzalloc(sizeof(p->cblocks) from_cblock(cache_size));
102	if (p->cblocks) {
103	unsigned u = from_cblock(cache_size);
104
105	while (u--)
106	list_add(&p->cblocks[u].list, &p->free);
107
108	p->nr_cblocks_allocated = 0;
109
110	/* Cache entries hash. */
111	r = alloc_hash(&p->chash, from_cblock(cache_size));
112	if (r)
113	vfree(p->cblocks);
114	}
115
116	return r;
117	}
118
119	static void free_cache_blocks_and_hash(struct policy *p)
120	{
121	free_hash(&p->chash);
122	vfree(p->cblocks);
123	}
124
125	static struct wb_cache_entry alloc_cache_entry(struct policy p)
126	{
127	struct wb_cache_entry *e;
128
129	BUG_ON(from_cblock(p->nr_cblocks_allocated) >= from_cblock(p->cache_size));
130
131	e = list_entry(list_pop(&p->free), struct wb_cache_entry, list);
132	p->nr_cblocks_allocated = to_cblock(from_cblock(p->nr_cblocks_allocated) + 1);
133
134	return e;
135	}
136
137	/----------------------------------------------------------------------------/
138
139	/* Hash functions (lookup, insert, remove). */
140	static struct wb_cache_entry lookup_cache_entry(struct policy p, dm_oblock_t oblock)
141	{
142	struct hash *hash = &p->chash;
143	unsigned h = hash_64(from_oblock(oblock), hash->hash_bits);
144	struct wb_cache_entry *cur;
145	struct hlist_head *bucket = &hash->table[h];
146
147	hlist_for_each_entry(cur, bucket, hlist) {
148	if (cur->oblock == oblock) {
149	/* Move upfront bucket for faster access. */
150	hlist_del(&cur->hlist);
151	hlist_add_head(&cur->hlist, bucket);
152	return cur;
153	}
154	}
155
156	return NULL;
157	}
158
159	static void insert_cache_hash_entry(struct policy p, struct wb_cache_entry e)
160	{
161	unsigned h = hash_64(from_oblock(e->oblock), p->chash.hash_bits);
162
163	hlist_add_head(&e->hlist, &p->chash.table[h]);
164	}
165
166	static void remove_cache_hash_entry(struct wb_cache_entry *e)
167	{
168	hlist_del(&e->hlist);
169	}
170
171	/* Public interface (see dm-cache-policy.h */
172	static int wb_map(struct dm_cache_policy *pe, dm_oblock_t oblock,
173	bool can_block, bool can_migrate, bool discarded_oblock,
174	struct bio bio, struct policy_result result)
175	{
176	struct policy *p = to_policy(pe);
177	struct wb_cache_entry *e;
178	unsigned long flags;
179
180	result->op = POLICY_MISS;
181
182	if (can_block)
183	spin_lock_irqsave(&p->lock, flags);
184
185	else if (!spin_trylock_irqsave(&p->lock, flags))
186	return -EWOULDBLOCK;
187
188	e = lookup_cache_entry(p, oblock);
189	if (e) {
190	result->op = POLICY_HIT;
191	result->cblock = e->cblock;
192
193	}
194
195	spin_unlock_irqrestore(&p->lock, flags);
196
197	return 0;
198	}
199
200	static int wb_lookup(struct dm_cache_policy pe, dm_oblock_t oblock, dm_cblock_t cblock)
201	{
202	int r;
203	struct policy *p = to_policy(pe);
204	struct wb_cache_entry *e;
205	unsigned long flags;
206
207	if (!spin_trylock_irqsave(&p->lock, flags))
208	return -EWOULDBLOCK;
209
210	e = lookup_cache_entry(p, oblock);
211	if (e) {
212	*cblock = e->cblock;
213	r = 0;
214
215	} else
216	r = -ENOENT;
217
218	spin_unlock_irqrestore(&p->lock, flags);
219
220	return r;
221	}
222
223	static void __set_clear_dirty(struct dm_cache_policy *pe, dm_oblock_t oblock, bool set)
224	{
225	struct policy *p = to_policy(pe);
226	struct wb_cache_entry *e;
227
228	e = lookup_cache_entry(p, oblock);
229	BUG_ON(!e);
230
231	if (set) {
232	if (!e->dirty) {
233	e->dirty = true;
234	list_move(&e->list, &p->dirty);
235	}
236
237	} else {
238	if (e->dirty) {
239	e->pending = false;
240	e->dirty = false;
241	list_move(&e->list, &p->clean);
242	}
243	}
244	}
245
246	static void wb_set_dirty(struct dm_cache_policy *pe, dm_oblock_t oblock)
247	{
248	struct policy *p = to_policy(pe);
249	unsigned long flags;
250
251	spin_lock_irqsave(&p->lock, flags);
252	__set_clear_dirty(pe, oblock, true);
253	spin_unlock_irqrestore(&p->lock, flags);
254	}
255
256	static void wb_clear_dirty(struct dm_cache_policy *pe, dm_oblock_t oblock)
257	{
258	struct policy *p = to_policy(pe);
259	unsigned long flags;
260
261	spin_lock_irqsave(&p->lock, flags);
262	__set_clear_dirty(pe, oblock, false);
263	spin_unlock_irqrestore(&p->lock, flags);
264	}
265
266	static void add_cache_entry(struct policy p, struct wb_cache_entry e)
267	{
268	insert_cache_hash_entry(p, e);
269	if (e->dirty)
270	list_add(&e->list, &p->dirty);
271	else
272	list_add(&e->list, &p->clean);
273	}
274
275	static int wb_load_mapping(struct dm_cache_policy *pe,
276	dm_oblock_t oblock, dm_cblock_t cblock,
277	uint32_t hint, bool hint_valid)
278	{
279	int r;
280	struct policy *p = to_policy(pe);
281	struct wb_cache_entry *e = alloc_cache_entry(p);
282
283	if (e) {
284	e->cblock = cblock;
285	e->oblock = oblock;
286	e->dirty = false; /* blocks default to clean */
287	add_cache_entry(p, e);
288	r = 0;
289
290	} else
291	r = -ENOMEM;
292
293	return r;
294	}
295
296	static void wb_destroy(struct dm_cache_policy *pe)
297	{
298	struct policy *p = to_policy(pe);
299
300	free_cache_blocks_and_hash(p);
301	kfree(p);
302	}
303
304	static struct wb_cache_entry __wb_force_remove_mapping(struct policy p, dm_oblock_t oblock)
305	{
306	struct wb_cache_entry *r = lookup_cache_entry(p, oblock);
307
308	BUG_ON(!r);
309
310	remove_cache_hash_entry(r);
311	list_del(&r->list);
312
313	return r;
314	}
315
316	static void wb_remove_mapping(struct dm_cache_policy *pe, dm_oblock_t oblock)
317	{
318	struct policy *p = to_policy(pe);
319	struct wb_cache_entry *e;
320	unsigned long flags;
321
322	spin_lock_irqsave(&p->lock, flags);
323	e = __wb_force_remove_mapping(p, oblock);
324	list_add_tail(&e->list, &p->free);
325	BUG_ON(!from_cblock(p->nr_cblocks_allocated));
326	p->nr_cblocks_allocated = to_cblock(from_cblock(p->nr_cblocks_allocated) - 1);
327	spin_unlock_irqrestore(&p->lock, flags);
328	}
329
330	static void wb_force_mapping(struct dm_cache_policy *pe,
331	dm_oblock_t current_oblock, dm_oblock_t oblock)
332	{
333	struct policy *p = to_policy(pe);
334	struct wb_cache_entry *e;
335	unsigned long flags;
336
337	spin_lock_irqsave(&p->lock, flags);
338	e = __wb_force_remove_mapping(p, current_oblock);
339	e->oblock = oblock;
340	add_cache_entry(p, e);
341	spin_unlock_irqrestore(&p->lock, flags);
342	}
343
344	static struct wb_cache_entry get_next_dirty_entry(struct policy p)
345	{
346	struct list_head *l;
347	struct wb_cache_entry *r;
348
349	if (list_empty(&p->dirty))
350	return NULL;
351
352	l = list_pop(&p->dirty);
353	r = container_of(l, struct wb_cache_entry, list);
354	list_add(l, &p->clean_pending);
355
356	return r;
357	}
358
359	static int wb_writeback_work(struct dm_cache_policy *pe,
360	dm_oblock_t *oblock,
361	dm_cblock_t *cblock)
362	{
363	int r = -ENOENT;
364	struct policy *p = to_policy(pe);
365	struct wb_cache_entry *e;
366	unsigned long flags;
367
368	spin_lock_irqsave(&p->lock, flags);
369
370	e = get_next_dirty_entry(p);
371	if (e) {
372	*oblock = e->oblock;
373	*cblock = e->cblock;
374	r = 0;
375	}
376
377	spin_unlock_irqrestore(&p->lock, flags);
378
379	return r;
380	}
381
382	static dm_cblock_t wb_residency(struct dm_cache_policy *pe)
383	{
384	return to_policy(pe)->nr_cblocks_allocated;
385	}
386
387	/* Init the policy plugin interface function pointers. */
388	static void init_policy_functions(struct policy *p)
389	{
390	p->policy.destroy = wb_destroy;
391	p->policy.map = wb_map;
392	p->policy.lookup = wb_lookup;
393	p->policy.set_dirty = wb_set_dirty;
394	p->policy.clear_dirty = wb_clear_dirty;
395	p->policy.load_mapping = wb_load_mapping;
396	p->policy.walk_mappings = NULL;
397	p->policy.remove_mapping = wb_remove_mapping;
398	p->policy.writeback_work = wb_writeback_work;
399	p->policy.force_mapping = wb_force_mapping;
400	p->policy.residency = wb_residency;
401	p->policy.tick = NULL;
402	}
403
404	static struct dm_cache_policy *wb_create(dm_cblock_t cache_size,
405	sector_t origin_size,
406	sector_t cache_block_size)
407	{
408	int r;
409	struct policy p = kzalloc(sizeof(p), GFP_KERNEL);
410
411	if (!p)
412	return NULL;
413
414	init_policy_functions(p);
415	INIT_LIST_HEAD(&p->free);
416	INIT_LIST_HEAD(&p->clean);
417	INIT_LIST_HEAD(&p->clean_pending);
418	INIT_LIST_HEAD(&p->dirty);
419
420	p->cache_size = cache_size;
421	spin_lock_init(&p->lock);
422
423	/* Allocate cache entry structs and add them to free list. */
424	r = alloc_cache_blocks_with_hash(p, cache_size);
425	if (!r)
426	return &p->policy;
427
428	kfree(p);
429
430	return NULL;
431	}
432	/----------------------------------------------------------------------------/
433
434	static struct dm_cache_policy_type wb_policy_type = {
435	.name = "cleaner",
4e7f506f	436	.version = {1, 0, 0},
8735a813 HM	437	.hint_size = 0,
	438	.owner = THIS_MODULE,
	439	.create = wb_create
	440	};
	441
	442	static int __init wb_init(void)
	443	{
	444	int r = dm_cache_policy_register(&wb_policy_type);
	445
	446	if (r < 0)
	447	DMERR("register failed %d", r);
	448	else
4e7f506f MS	449	DMINFO("version %u.%u.%u loaded",
	450	wb_policy_type.version[0],
	451	wb_policy_type.version[1],
	452	wb_policy_type.version[2]);
8735a813 HM	453
	454	return r;
	455	}
	456
	457	static void __exit wb_exit(void)
	458	{
	459	dm_cache_policy_unregister(&wb_policy_type);
	460	}
	461
	462	module_init(wb_init);
	463	module_exit(wb_exit);
	464
	465	MODULE_AUTHOR("Heinz Mauelshagen <dm-devel@redhat.com>");
	466	MODULE_LICENSE("GPL");
	467	MODULE_DESCRIPTION("cleaner cache policy");