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 bt_work {
15 struct list_head list;
16 struct rb_node node;
17 struct policy_work work;
18};
19
20struct background_tracker {
21 unsigned int max_work;
22 atomic_t pending_promotes;
23 atomic_t pending_writebacks;
24 atomic_t pending_demotes;
25
26 struct list_head issued;
27 struct list_head queued;
28 struct rb_root pending;
29
30 struct kmem_cache *work_cache;
31};
32
33struct background_tracker *btracker_create(unsigned int max_work)
34{
35 struct background_tracker *b = kmalloc(size: sizeof(*b), GFP_KERNEL);
36
37 if (!b) {
38 DMERR("couldn't create background_tracker");
39 return NULL;
40 }
41
42 b->max_work = max_work;
43 atomic_set(v: &b->pending_promotes, i: 0);
44 atomic_set(v: &b->pending_writebacks, i: 0);
45 atomic_set(v: &b->pending_demotes, i: 0);
46
47 INIT_LIST_HEAD(list: &b->issued);
48 INIT_LIST_HEAD(list: &b->queued);
49
50 b->pending = RB_ROOT;
51 b->work_cache = KMEM_CACHE(bt_work, 0);
52 if (!b->work_cache) {
53 DMERR("couldn't create mempool for background work items");
54 kfree(objp: b);
55 b = NULL;
56 }
57
58 return b;
59}
60EXPORT_SYMBOL_GPL(btracker_create);
61
62void btracker_destroy(struct background_tracker *b)
63{
64 struct bt_work *w, *tmp;
65
66 BUG_ON(!list_empty(&b->issued));
67 list_for_each_entry_safe (w, tmp, &b->queued, list) {
68 list_del(entry: &w->list);
69 kmem_cache_free(s: b->work_cache, objp: w);
70 }
71
72 kmem_cache_destroy(s: b->work_cache);
73 kfree(objp: b);
74}
75EXPORT_SYMBOL_GPL(btracker_destroy);
76
77static int cmp_oblock(dm_oblock_t lhs, dm_oblock_t rhs)
78{
79 if (from_oblock(b: lhs) < from_oblock(b: rhs))
80 return -1;
81
82 if (from_oblock(b: rhs) < from_oblock(b: lhs))
83 return 1;
84
85 return 0;
86}
87
88static bool __insert_pending(struct background_tracker *b,
89 struct bt_work *nw)
90{
91 int cmp;
92 struct bt_work *w;
93 struct rb_node **new = &b->pending.rb_node, *parent = NULL;
94
95 while (*new) {
96 w = container_of(*new, struct bt_work, node);
97
98 parent = *new;
99 cmp = cmp_oblock(lhs: w->work.oblock, rhs: nw->work.oblock);
100 if (cmp < 0)
101 new = &((*new)->rb_left);
102
103 else if (cmp > 0)
104 new = &((*new)->rb_right);
105
106 else
107 /* already present */
108 return false;
109 }
110
111 rb_link_node(node: &nw->node, parent, rb_link: new);
112 rb_insert_color(&nw->node, &b->pending);
113
114 return true;
115}
116
117static struct bt_work *__find_pending(struct background_tracker *b,
118 dm_oblock_t oblock)
119{
120 int cmp;
121 struct bt_work *w;
122 struct rb_node **new = &b->pending.rb_node;
123
124 while (*new) {
125 w = container_of(*new, struct bt_work, node);
126
127 cmp = cmp_oblock(lhs: w->work.oblock, rhs: oblock);
128 if (cmp < 0)
129 new = &((*new)->rb_left);
130
131 else if (cmp > 0)
132 new = &((*new)->rb_right);
133
134 else
135 break;
136 }
137
138 return *new ? w : NULL;
139}
140
141
142static void update_stats(struct background_tracker *b, struct policy_work *w, int delta)
143{
144 switch (w->op) {
145 case POLICY_PROMOTE:
146 atomic_add(i: delta, v: &b->pending_promotes);
147 break;
148
149 case POLICY_DEMOTE:
150 atomic_add(i: delta, v: &b->pending_demotes);
151 break;
152
153 case POLICY_WRITEBACK:
154 atomic_add(i: delta, v: &b->pending_writebacks);
155 break;
156 }
157}
158
159unsigned int btracker_nr_writebacks_queued(struct background_tracker *b)
160{
161 return atomic_read(v: &b->pending_writebacks);
162}
163EXPORT_SYMBOL_GPL(btracker_nr_writebacks_queued);
164
165unsigned int btracker_nr_demotions_queued(struct background_tracker *b)
166{
167 return atomic_read(v: &b->pending_demotes);
168}
169EXPORT_SYMBOL_GPL(btracker_nr_demotions_queued);
170
171static bool max_work_reached(struct background_tracker *b)
172{
173 return atomic_read(v: &b->pending_promotes) +
174 atomic_read(v: &b->pending_writebacks) +
175 atomic_read(v: &b->pending_demotes) >= b->max_work;
176}
177
178static struct bt_work *alloc_work(struct background_tracker *b)
179{
180 if (max_work_reached(b))
181 return NULL;
182
183 return kmem_cache_alloc(cachep: b->work_cache, GFP_NOWAIT);
184}
185
186int btracker_queue(struct background_tracker *b,
187 struct policy_work *work,
188 struct policy_work **pwork)
189{
190 struct bt_work *w;
191
192 if (pwork)
193 *pwork = NULL;
194
195 w = alloc_work(b);
196 if (!w)
197 return -ENOMEM;
198
199 memcpy(&w->work, work, sizeof(*work));
200
201 if (!__insert_pending(b, nw: w)) {
202 /*
203 * There was a race, we'll just ignore this second
204 * bit of work for the same oblock.
205 */
206 kmem_cache_free(s: b->work_cache, objp: w);
207 return -EINVAL;
208 }
209
210 if (pwork) {
211 *pwork = &w->work;
212 list_add(new: &w->list, head: &b->issued);
213 } else
214 list_add(new: &w->list, head: &b->queued);
215 update_stats(b, w: &w->work, delta: 1);
216
217 return 0;
218}
219EXPORT_SYMBOL_GPL(btracker_queue);
220
221/*
222 * Returns -ENODATA if there's no work.
223 */
224int btracker_issue(struct background_tracker *b, struct policy_work **work)
225{
226 struct bt_work *w;
227
228 if (list_empty(head: &b->queued))
229 return -ENODATA;
230
231 w = list_first_entry(&b->queued, struct bt_work, list);
232 list_move(list: &w->list, head: &b->issued);
233 *work = &w->work;
234
235 return 0;
236}
237EXPORT_SYMBOL_GPL(btracker_issue);
238
239void btracker_complete(struct background_tracker *b,
240 struct policy_work *op)
241{
242 struct bt_work *w = container_of(op, struct bt_work, work);
243
244 update_stats(b, w: &w->work, delta: -1);
245 rb_erase(&w->node, &b->pending);
246 list_del(entry: &w->list);
247 kmem_cache_free(s: b->work_cache, objp: w);
248}
249EXPORT_SYMBOL_GPL(btracker_complete);
250
251bool btracker_promotion_already_present(struct background_tracker *b,
252 dm_oblock_t oblock)
253{
254 return __find_pending(b, oblock) != NULL;
255}
256EXPORT_SYMBOL_GPL(btracker_promotion_already_present);
257
258/*----------------------------------------------------------------*/
259

source code of linux/drivers/md/dm-cache-background-tracker.c