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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (C) 2017 Red Hat. All rights reserved.
4 *
5 * This file is released under the GPL.
6 */
7
8#include "dm-cache-background-tracker.h"
9
10/*----------------------------------------------------------------*/
11
12#define DM_MSG_PREFIX "dm-background-tracker"
13
14struct background_tracker {
15 unsigned int max_work;
16 atomic_t pending_promotes;
17 atomic_t pending_writebacks;
18 atomic_t pending_demotes;
19
20 struct list_head issued;
21 struct list_head queued;
22 struct rb_root pending;
23};
24
25struct kmem_cache *btracker_work_cache = NULL;
26
27struct background_tracker *btracker_create(unsigned int max_work)
28{
29 struct background_tracker *b = kmalloc_obj(*b);
30
31 if (!b) {
32 DMERR("couldn't create background_tracker");
33 return NULL;
34 }
35
36 b->max_work = max_work;
37 atomic_set(&b->pending_promotes, 0);
38 atomic_set(&b->pending_writebacks, 0);
39 atomic_set(&b->pending_demotes, 0);
40
41 INIT_LIST_HEAD(&b->issued);
42 INIT_LIST_HEAD(&b->queued);
43
44 b->pending = RB_ROOT;
45
46 return b;
47}
48EXPORT_SYMBOL_GPL(btracker_create);
49
50void btracker_destroy(struct background_tracker *b)
51{
52 struct bt_work *w, *tmp;
53
54 BUG_ON(!list_empty(&b->issued));
55 list_for_each_entry_safe (w, tmp, &b->queued, list) {
56 list_del(&w->list);
57 kmem_cache_free(btracker_work_cache, w);
58 }
59
60 kfree(b);
61}
62EXPORT_SYMBOL_GPL(btracker_destroy);
63
64static int cmp_oblock(dm_oblock_t lhs, dm_oblock_t rhs)
65{
66 if (from_oblock(lhs) < from_oblock(rhs))
67 return -1;
68
69 if (from_oblock(rhs) < from_oblock(lhs))
70 return 1;
71
72 return 0;
73}
74
75static bool __insert_pending(struct background_tracker *b,
76 struct bt_work *nw)
77{
78 int cmp;
79 struct bt_work *w;
80 struct rb_node **new = &b->pending.rb_node, *parent = NULL;
81
82 while (*new) {
83 w = container_of(*new, struct bt_work, node);
84
85 parent = *new;
86 cmp = cmp_oblock(w->work.oblock, nw->work.oblock);
87 if (cmp < 0)
88 new = &((*new)->rb_left);
89
90 else if (cmp > 0)
91 new = &((*new)->rb_right);
92
93 else
94 /* already present */
95 return false;
96 }
97
98 rb_link_node(&nw->node, parent, new);
99 rb_insert_color(&nw->node, &b->pending);
100
101 return true;
102}
103
104static struct bt_work *__find_pending(struct background_tracker *b,
105 dm_oblock_t oblock)
106{
107 int cmp;
108 struct bt_work *w;
109 struct rb_node **new = &b->pending.rb_node;
110
111 while (*new) {
112 w = container_of(*new, struct bt_work, node);
113
114 cmp = cmp_oblock(w->work.oblock, oblock);
115 if (cmp < 0)
116 new = &((*new)->rb_left);
117
118 else if (cmp > 0)
119 new = &((*new)->rb_right);
120
121 else
122 break;
123 }
124
125 return *new ? w : NULL;
126}
127
128
129static void update_stats(struct background_tracker *b, struct policy_work *w, int delta)
130{
131 switch (w->op) {
132 case POLICY_PROMOTE:
133 atomic_add(delta, &b->pending_promotes);
134 break;
135
136 case POLICY_DEMOTE:
137 atomic_add(delta, &b->pending_demotes);
138 break;
139
140 case POLICY_WRITEBACK:
141 atomic_add(delta, &b->pending_writebacks);
142 break;
143 }
144}
145
146unsigned int btracker_nr_demotions_queued(struct background_tracker *b)
147{
148 return atomic_read(&b->pending_demotes);
149}
150EXPORT_SYMBOL_GPL(btracker_nr_demotions_queued);
151
152static bool max_work_reached(struct background_tracker *b)
153{
154 return atomic_read(&b->pending_promotes) +
155 atomic_read(&b->pending_writebacks) +
156 atomic_read(&b->pending_demotes) >= b->max_work;
157}
158
159static struct bt_work *alloc_work(struct background_tracker *b)
160{
161 if (max_work_reached(b))
162 return NULL;
163
164 return kmem_cache_alloc(btracker_work_cache, GFP_NOWAIT);
165}
166
167int btracker_queue(struct background_tracker *b,
168 struct policy_work *work,
169 struct policy_work **pwork)
170{
171 struct bt_work *w;
172
173 if (pwork)
174 *pwork = NULL;
175
176 w = alloc_work(b);
177 if (!w)
178 return -ENOMEM;
179
180 memcpy(&w->work, work, sizeof(*work));
181
182 if (!__insert_pending(b, w)) {
183 /*
184 * There was a race, we'll just ignore this second
185 * bit of work for the same oblock.
186 */
187 kmem_cache_free(btracker_work_cache, w);
188 return -EINVAL;
189 }
190
191 if (pwork) {
192 *pwork = &w->work;
193 list_add(&w->list, &b->issued);
194 } else
195 list_add(&w->list, &b->queued);
196 update_stats(b, &w->work, 1);
197
198 return 0;
199}
200EXPORT_SYMBOL_GPL(btracker_queue);
201
202/*
203 * Returns -ENODATA if there's no work.
204 */
205int btracker_issue(struct background_tracker *b, struct policy_work **work)
206{
207 struct bt_work *w;
208
209 if (list_empty(&b->queued))
210 return -ENODATA;
211
212 w = list_first_entry(&b->queued, struct bt_work, list);
213 list_move(&w->list, &b->issued);
214 *work = &w->work;
215
216 return 0;
217}
218EXPORT_SYMBOL_GPL(btracker_issue);
219
220void btracker_complete(struct background_tracker *b,
221 struct policy_work *op)
222{
223 struct bt_work *w = container_of(op, struct bt_work, work);
224
225 update_stats(b, &w->work, -1);
226 rb_erase(&w->node, &b->pending);
227 list_del(&w->list);
228 kmem_cache_free(btracker_work_cache, w);
229}
230EXPORT_SYMBOL_GPL(btracker_complete);
231
232bool btracker_promotion_already_present(struct background_tracker *b,
233 dm_oblock_t oblock)
234{
235 return __find_pending(b, oblock) != NULL;
236}
237EXPORT_SYMBOL_GPL(btracker_promotion_already_present);
238
239/*----------------------------------------------------------------*/