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
|
/*
* Copyright (C) 2017 Red Hat. All rights reserved.
*
* This file is released under the GPL.
*/
#include "dm-cache-background-tracker.h"
/*----------------------------------------------------------------*/
#define DM_MSG_PREFIX "dm-background-tracker"
struct bt_work {
struct list_head list;
struct rb_node node;
struct policy_work work;
};
struct background_tracker {
unsigned max_work;
atomic_t pending_promotes;
atomic_t pending_writebacks;
atomic_t pending_demotes;
struct list_head issued;
struct list_head queued;
struct rb_root pending;
struct kmem_cache *work_cache;
};
struct background_tracker *btracker_create(unsigned max_work)
{
struct background_tracker *b = kmalloc(sizeof(*b), GFP_KERNEL);
if (!b) {
DMERR("couldn't create background_tracker");
return NULL;
}
b->max_work = max_work;
atomic_set(&b->pending_promotes, 0);
atomic_set(&b->pending_writebacks, 0);
atomic_set(&b->pending_demotes, 0);
INIT_LIST_HEAD(&b->issued);
INIT_LIST_HEAD(&b->queued);
b->pending = RB_ROOT;
b->work_cache = KMEM_CACHE(bt_work, 0);
if (!b->work_cache) {
DMERR("couldn't create mempool for background work items");
kfree(b);
b = NULL;
}
return b;
}
EXPORT_SYMBOL_GPL(btracker_create);
void btracker_destroy(struct background_tracker *b)
{
kmem_cache_destroy(b->work_cache);
kfree(b);
}
EXPORT_SYMBOL_GPL(btracker_destroy);
static int cmp_oblock(dm_oblock_t lhs, dm_oblock_t rhs)
{
if (from_oblock(lhs) < from_oblock(rhs))
return -1;
if (from_oblock(rhs) < from_oblock(lhs))
return 1;
return 0;
}
static bool __insert_pending(struct background_tracker *b,
struct bt_work *nw)
{
int cmp;
struct bt_work *w;
struct rb_node **new = &b->pending.rb_node, *parent = NULL;
while (*new) {
w = container_of(*new, struct bt_work, node);
parent = *new;
cmp = cmp_oblock(w->work.oblock, nw->work.oblock);
if (cmp < 0)
new = &((*new)->rb_left);
else if (cmp > 0)
new = &((*new)->rb_right);
else
/* already present */
return false;
}
rb_link_node(&nw->node, parent, new);
rb_insert_color(&nw->node, &b->pending);
return true;
}
static struct bt_work *__find_pending(struct background_tracker *b,
dm_oblock_t oblock)
{
int cmp;
struct bt_work *w;
struct rb_node **new = &b->pending.rb_node;
while (*new) {
w = container_of(*new, struct bt_work, node);
cmp = cmp_oblock(w->work.oblock, oblock);
if (cmp < 0)
new = &((*new)->rb_left);
else if (cmp > 0)
new = &((*new)->rb_right);
else
break;
}
return *new ? w : NULL;
}
static void update_stats(struct background_tracker *b, struct policy_work *w, int delta)
{
switch (w->op) {
case POLICY_PROMOTE:
atomic_add(delta, &b->pending_promotes);
break;
case POLICY_DEMOTE:
atomic_add(delta, &b->pending_demotes);
break;
case POLICY_WRITEBACK:
atomic_add(delta, &b->pending_writebacks);
break;
}
}
unsigned btracker_nr_writebacks_queued(struct background_tracker *b)
{
return atomic_read(&b->pending_writebacks);
}
EXPORT_SYMBOL_GPL(btracker_nr_writebacks_queued);
unsigned btracker_nr_demotions_queued(struct background_tracker *b)
{
return atomic_read(&b->pending_demotes);
}
EXPORT_SYMBOL_GPL(btracker_nr_demotions_queued);
static bool max_work_reached(struct background_tracker *b)
{
return atomic_read(&b->pending_promotes) +
atomic_read(&b->pending_writebacks) +
atomic_read(&b->pending_demotes) >= b->max_work;
}
struct bt_work *alloc_work(struct background_tracker *b)
{
if (max_work_reached(b))
return NULL;
return kmem_cache_alloc(b->work_cache, GFP_NOWAIT);
}
int btracker_queue(struct background_tracker *b,
struct policy_work *work,
struct policy_work **pwork)
{
struct bt_work *w;
if (pwork)
*pwork = NULL;
w = alloc_work(b);
if (!w)
return -ENOMEM;
memcpy(&w->work, work, sizeof(*work));
if (!__insert_pending(b, w)) {
/*
* There was a race, we'll just ignore this second
* bit of work for the same oblock.
*/
kmem_cache_free(b->work_cache, w);
return -EINVAL;
}
if (pwork) {
*pwork = &w->work;
list_add(&w->list, &b->issued);
} else
list_add(&w->list, &b->queued);
update_stats(b, &w->work, 1);
return 0;
}
EXPORT_SYMBOL_GPL(btracker_queue);
/*
* Returns -ENODATA if there's no work.
*/
int btracker_issue(struct background_tracker *b, struct policy_work **work)
{
struct bt_work *w;
if (list_empty(&b->queued))
return -ENODATA;
w = list_first_entry(&b->queued, struct bt_work, list);
list_move(&w->list, &b->issued);
*work = &w->work;
return 0;
}
EXPORT_SYMBOL_GPL(btracker_issue);
void btracker_complete(struct background_tracker *b,
struct policy_work *op)
{
struct bt_work *w = container_of(op, struct bt_work, work);
update_stats(b, &w->work, -1);
rb_erase(&w->node, &b->pending);
list_del(&w->list);
kmem_cache_free(b->work_cache, w);
}
EXPORT_SYMBOL_GPL(btracker_complete);
bool btracker_promotion_already_present(struct background_tracker *b,
dm_oblock_t oblock)
{
return __find_pending(b, oblock) != NULL;
}
EXPORT_SYMBOL_GPL(btracker_promotion_already_present);
/*----------------------------------------------------------------*/
|
