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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (C) 2018 HUAWEI, Inc.
4 * https://www.huawei.com/
5 */
6#include "internal.h"
7
8struct page *erofs_allocpage(struct page **pagepool, gfp_t gfp)
9{
10 struct page *page = *pagepool;
11
12 if (page) {
13 DBG_BUGON(page_ref_count(page) != 1);
14 *pagepool = (struct page *)page_private(page);
15 } else {
16 page = alloc_page(gfp);
17 }
18 return page;
19}
20
21void erofs_release_pages(struct page **pagepool)
22{
23 while (*pagepool) {
24 struct page *page = *pagepool;
25
26 *pagepool = (struct page *)page_private(page);
27 put_page(page);
28 }
29}
30
31#ifdef CONFIG_EROFS_FS_ZIP
32/* global shrink count (for all mounted EROFS instances) */
33static atomic_long_t erofs_global_shrink_cnt;
34
35static bool erofs_workgroup_get(struct erofs_workgroup *grp)
36{
37 if (lockref_get_not_zero(&grp->lockref))
38 return true;
39
40 spin_lock(&grp->lockref.lock);
41 if (__lockref_is_dead(&grp->lockref)) {
42 spin_unlock(&grp->lockref.lock);
43 return false;
44 }
45
46 if (!grp->lockref.count++)
47 atomic_long_dec(&erofs_global_shrink_cnt);
48 spin_unlock(&grp->lockref.lock);
49 return true;
50}
51
52struct erofs_workgroup *erofs_find_workgroup(struct super_block *sb,
53 pgoff_t index)
54{
55 struct erofs_sb_info *sbi = EROFS_SB(sb);
56 struct erofs_workgroup *grp;
57
58repeat:
59 rcu_read_lock();
60 grp = xa_load(&sbi->managed_pslots, index);
61 if (grp) {
62 if (!erofs_workgroup_get(grp)) {
63 /* prefer to relax rcu read side */
64 rcu_read_unlock();
65 goto repeat;
66 }
67
68 DBG_BUGON(index != grp->index);
69 }
70 rcu_read_unlock();
71 return grp;
72}
73
74struct erofs_workgroup *erofs_insert_workgroup(struct super_block *sb,
75 struct erofs_workgroup *grp)
76{
77 struct erofs_sb_info *const sbi = EROFS_SB(sb);
78 struct erofs_workgroup *pre;
79
80 DBG_BUGON(grp->lockref.count < 1);
81repeat:
82 xa_lock(&sbi->managed_pslots);
83 pre = __xa_cmpxchg(&sbi->managed_pslots, grp->index,
84 NULL, grp, GFP_KERNEL);
85 if (pre) {
86 if (xa_is_err(pre)) {
87 pre = ERR_PTR(xa_err(pre));
88 } else if (!erofs_workgroup_get(pre)) {
89 /* try to legitimize the current in-tree one */
90 xa_unlock(&sbi->managed_pslots);
91 cond_resched();
92 goto repeat;
93 }
94 grp = pre;
95 }
96 xa_unlock(&sbi->managed_pslots);
97 return grp;
98}
99
100static void __erofs_workgroup_free(struct erofs_workgroup *grp)
101{
102 atomic_long_dec(&erofs_global_shrink_cnt);
103 erofs_workgroup_free_rcu(grp);
104}
105
106void erofs_workgroup_put(struct erofs_workgroup *grp)
107{
108 if (lockref_put_or_lock(&grp->lockref))
109 return;
110
111 DBG_BUGON(__lockref_is_dead(&grp->lockref));
112 if (grp->lockref.count == 1)
113 atomic_long_inc(&erofs_global_shrink_cnt);
114 --grp->lockref.count;
115 spin_unlock(&grp->lockref.lock);
116}
117
118static bool erofs_try_to_release_workgroup(struct erofs_sb_info *sbi,
119 struct erofs_workgroup *grp)
120{
121 int free = false;
122
123 spin_lock(&grp->lockref.lock);
124 if (grp->lockref.count)
125 goto out;
126
127 /*
128 * Note that all cached pages should be detached before deleted from
129 * the XArray. Otherwise some cached pages could be still attached to
130 * the orphan old workgroup when the new one is available in the tree.
131 */
132 if (erofs_try_to_free_all_cached_pages(sbi, grp))
133 goto out;
134
135 /*
136 * It's impossible to fail after the workgroup is freezed,
137 * however in order to avoid some race conditions, add a
138 * DBG_BUGON to observe this in advance.
139 */
140 DBG_BUGON(__xa_erase(&sbi->managed_pslots, grp->index) != grp);
141
142 lockref_mark_dead(&grp->lockref);
143 free = true;
144out:
145 spin_unlock(&grp->lockref.lock);
146 if (free)
147 __erofs_workgroup_free(grp);
148 return free;
149}
150
151static unsigned long erofs_shrink_workstation(struct erofs_sb_info *sbi,
152 unsigned long nr_shrink)
153{
154 struct erofs_workgroup *grp;
155 unsigned int freed = 0;
156 unsigned long index;
157
158 xa_lock(&sbi->managed_pslots);
159 xa_for_each(&sbi->managed_pslots, index, grp) {
160 /* try to shrink each valid workgroup */
161 if (!erofs_try_to_release_workgroup(sbi, grp))
162 continue;
163 xa_unlock(&sbi->managed_pslots);
164
165 ++freed;
166 if (!--nr_shrink)
167 return freed;
168 xa_lock(&sbi->managed_pslots);
169 }
170 xa_unlock(&sbi->managed_pslots);
171 return freed;
172}
173
174/* protected by 'erofs_sb_list_lock' */
175static unsigned int shrinker_run_no;
176
177/* protects the mounted 'erofs_sb_list' */
178static DEFINE_SPINLOCK(erofs_sb_list_lock);
179static LIST_HEAD(erofs_sb_list);
180
181void erofs_shrinker_register(struct super_block *sb)
182{
183 struct erofs_sb_info *sbi = EROFS_SB(sb);
184
185 mutex_init(&sbi->umount_mutex);
186
187 spin_lock(&erofs_sb_list_lock);
188 list_add(&sbi->list, &erofs_sb_list);
189 spin_unlock(&erofs_sb_list_lock);
190}
191
192void erofs_shrinker_unregister(struct super_block *sb)
193{
194 struct erofs_sb_info *const sbi = EROFS_SB(sb);
195
196 mutex_lock(&sbi->umount_mutex);
197 /* clean up all remaining workgroups in memory */
198 erofs_shrink_workstation(sbi, ~0UL);
199
200 spin_lock(&erofs_sb_list_lock);
201 list_del(&sbi->list);
202 spin_unlock(&erofs_sb_list_lock);
203 mutex_unlock(&sbi->umount_mutex);
204}
205
206static unsigned long erofs_shrink_count(struct shrinker *shrink,
207 struct shrink_control *sc)
208{
209 return atomic_long_read(&erofs_global_shrink_cnt);
210}
211
212static unsigned long erofs_shrink_scan(struct shrinker *shrink,
213 struct shrink_control *sc)
214{
215 struct erofs_sb_info *sbi;
216 struct list_head *p;
217
218 unsigned long nr = sc->nr_to_scan;
219 unsigned int run_no;
220 unsigned long freed = 0;
221
222 spin_lock(&erofs_sb_list_lock);
223 do {
224 run_no = ++shrinker_run_no;
225 } while (run_no == 0);
226
227 /* Iterate over all mounted superblocks and try to shrink them */
228 p = erofs_sb_list.next;
229 while (p != &erofs_sb_list) {
230 sbi = list_entry(p, struct erofs_sb_info, list);
231
232 /*
233 * We move the ones we do to the end of the list, so we stop
234 * when we see one we have already done.
235 */
236 if (sbi->shrinker_run_no == run_no)
237 break;
238
239 if (!mutex_trylock(&sbi->umount_mutex)) {
240 p = p->next;
241 continue;
242 }
243
244 spin_unlock(&erofs_sb_list_lock);
245 sbi->shrinker_run_no = run_no;
246
247 freed += erofs_shrink_workstation(sbi, nr - freed);
248
249 spin_lock(&erofs_sb_list_lock);
250 /* Get the next list element before we move this one */
251 p = p->next;
252
253 /*
254 * Move this one to the end of the list to provide some
255 * fairness.
256 */
257 list_move_tail(&sbi->list, &erofs_sb_list);
258 mutex_unlock(&sbi->umount_mutex);
259
260 if (freed >= nr)
261 break;
262 }
263 spin_unlock(&erofs_sb_list_lock);
264 return freed;
265}
266
267static struct shrinker *erofs_shrinker_info;
268
269int __init erofs_init_shrinker(void)
270{
271 erofs_shrinker_info = shrinker_alloc(0, "erofs-shrinker");
272 if (!erofs_shrinker_info)
273 return -ENOMEM;
274
275 erofs_shrinker_info->count_objects = erofs_shrink_count;
276 erofs_shrinker_info->scan_objects = erofs_shrink_scan;
277
278 shrinker_register(erofs_shrinker_info);
279
280 return 0;
281}
282
283void erofs_exit_shrinker(void)
284{
285 shrinker_free(erofs_shrinker_info);
286}
287#endif /* !CONFIG_EROFS_FS_ZIP */
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (C) 2018 HUAWEI, Inc.
4 * https://www.huawei.com/
5 * Created by Gao Xiang <gaoxiang25@huawei.com>
6 */
7#include "internal.h"
8#include <linux/pagevec.h>
9
10struct page *erofs_allocpage(struct list_head *pool, gfp_t gfp)
11{
12 struct page *page;
13
14 if (!list_empty(pool)) {
15 page = lru_to_page(pool);
16 DBG_BUGON(page_ref_count(page) != 1);
17 list_del(&page->lru);
18 } else {
19 page = alloc_page(gfp);
20 }
21 return page;
22}
23
24#if (EROFS_PCPUBUF_NR_PAGES > 0)
25static struct {
26 u8 data[PAGE_SIZE * EROFS_PCPUBUF_NR_PAGES];
27} ____cacheline_aligned_in_smp erofs_pcpubuf[NR_CPUS];
28
29void *erofs_get_pcpubuf(unsigned int pagenr)
30{
31 preempt_disable();
32 return &erofs_pcpubuf[smp_processor_id()].data[pagenr * PAGE_SIZE];
33}
34#endif
35
36#ifdef CONFIG_EROFS_FS_ZIP
37/* global shrink count (for all mounted EROFS instances) */
38static atomic_long_t erofs_global_shrink_cnt;
39
40static int erofs_workgroup_get(struct erofs_workgroup *grp)
41{
42 int o;
43
44repeat:
45 o = erofs_wait_on_workgroup_freezed(grp);
46 if (o <= 0)
47 return -1;
48
49 if (atomic_cmpxchg(&grp->refcount, o, o + 1) != o)
50 goto repeat;
51
52 /* decrease refcount paired by erofs_workgroup_put */
53 if (o == 1)
54 atomic_long_dec(&erofs_global_shrink_cnt);
55 return 0;
56}
57
58struct erofs_workgroup *erofs_find_workgroup(struct super_block *sb,
59 pgoff_t index)
60{
61 struct erofs_sb_info *sbi = EROFS_SB(sb);
62 struct erofs_workgroup *grp;
63
64repeat:
65 rcu_read_lock();
66 grp = xa_load(&sbi->managed_pslots, index);
67 if (grp) {
68 if (erofs_workgroup_get(grp)) {
69 /* prefer to relax rcu read side */
70 rcu_read_unlock();
71 goto repeat;
72 }
73
74 DBG_BUGON(index != grp->index);
75 }
76 rcu_read_unlock();
77 return grp;
78}
79
80struct erofs_workgroup *erofs_insert_workgroup(struct super_block *sb,
81 struct erofs_workgroup *grp)
82{
83 struct erofs_sb_info *const sbi = EROFS_SB(sb);
84 struct erofs_workgroup *pre;
85
86 /*
87 * Bump up a reference count before making this visible
88 * to others for the XArray in order to avoid potential
89 * UAF without serialized by xa_lock.
90 */
91 atomic_inc(&grp->refcount);
92
93repeat:
94 xa_lock(&sbi->managed_pslots);
95 pre = __xa_cmpxchg(&sbi->managed_pslots, grp->index,
96 NULL, grp, GFP_NOFS);
97 if (pre) {
98 if (xa_is_err(pre)) {
99 pre = ERR_PTR(xa_err(pre));
100 } else if (erofs_workgroup_get(pre)) {
101 /* try to legitimize the current in-tree one */
102 xa_unlock(&sbi->managed_pslots);
103 cond_resched();
104 goto repeat;
105 }
106 atomic_dec(&grp->refcount);
107 grp = pre;
108 }
109 xa_unlock(&sbi->managed_pslots);
110 return grp;
111}
112
113static void __erofs_workgroup_free(struct erofs_workgroup *grp)
114{
115 atomic_long_dec(&erofs_global_shrink_cnt);
116 erofs_workgroup_free_rcu(grp);
117}
118
119int erofs_workgroup_put(struct erofs_workgroup *grp)
120{
121 int count = atomic_dec_return(&grp->refcount);
122
123 if (count == 1)
124 atomic_long_inc(&erofs_global_shrink_cnt);
125 else if (!count)
126 __erofs_workgroup_free(grp);
127 return count;
128}
129
130static bool erofs_try_to_release_workgroup(struct erofs_sb_info *sbi,
131 struct erofs_workgroup *grp)
132{
133 /*
134 * If managed cache is on, refcount of workgroups
135 * themselves could be < 0 (freezed). In other words,
136 * there is no guarantee that all refcounts > 0.
137 */
138 if (!erofs_workgroup_try_to_freeze(grp, 1))
139 return false;
140
141 /*
142 * Note that all cached pages should be unattached
143 * before deleted from the XArray. Otherwise some
144 * cached pages could be still attached to the orphan
145 * old workgroup when the new one is available in the tree.
146 */
147 if (erofs_try_to_free_all_cached_pages(sbi, grp)) {
148 erofs_workgroup_unfreeze(grp, 1);
149 return false;
150 }
151
152 /*
153 * It's impossible to fail after the workgroup is freezed,
154 * however in order to avoid some race conditions, add a
155 * DBG_BUGON to observe this in advance.
156 */
157 DBG_BUGON(xa_erase(&sbi->managed_pslots, grp->index) != grp);
158
159 /* last refcount should be connected with its managed pslot. */
160 erofs_workgroup_unfreeze(grp, 0);
161 __erofs_workgroup_free(grp);
162 return true;
163}
164
165static unsigned long erofs_shrink_workstation(struct erofs_sb_info *sbi,
166 unsigned long nr_shrink)
167{
168 struct erofs_workgroup *grp;
169 unsigned int freed = 0;
170 unsigned long index;
171
172 xa_for_each(&sbi->managed_pslots, index, grp) {
173 /* try to shrink each valid workgroup */
174 if (!erofs_try_to_release_workgroup(sbi, grp))
175 continue;
176
177 ++freed;
178 if (!--nr_shrink)
179 break;
180 }
181 return freed;
182}
183
184/* protected by 'erofs_sb_list_lock' */
185static unsigned int shrinker_run_no;
186
187/* protects the mounted 'erofs_sb_list' */
188static DEFINE_SPINLOCK(erofs_sb_list_lock);
189static LIST_HEAD(erofs_sb_list);
190
191void erofs_shrinker_register(struct super_block *sb)
192{
193 struct erofs_sb_info *sbi = EROFS_SB(sb);
194
195 mutex_init(&sbi->umount_mutex);
196
197 spin_lock(&erofs_sb_list_lock);
198 list_add(&sbi->list, &erofs_sb_list);
199 spin_unlock(&erofs_sb_list_lock);
200}
201
202void erofs_shrinker_unregister(struct super_block *sb)
203{
204 struct erofs_sb_info *const sbi = EROFS_SB(sb);
205
206 mutex_lock(&sbi->umount_mutex);
207 /* clean up all remaining workgroups in memory */
208 erofs_shrink_workstation(sbi, ~0UL);
209
210 spin_lock(&erofs_sb_list_lock);
211 list_del(&sbi->list);
212 spin_unlock(&erofs_sb_list_lock);
213 mutex_unlock(&sbi->umount_mutex);
214}
215
216static unsigned long erofs_shrink_count(struct shrinker *shrink,
217 struct shrink_control *sc)
218{
219 return atomic_long_read(&erofs_global_shrink_cnt);
220}
221
222static unsigned long erofs_shrink_scan(struct shrinker *shrink,
223 struct shrink_control *sc)
224{
225 struct erofs_sb_info *sbi;
226 struct list_head *p;
227
228 unsigned long nr = sc->nr_to_scan;
229 unsigned int run_no;
230 unsigned long freed = 0;
231
232 spin_lock(&erofs_sb_list_lock);
233 do {
234 run_no = ++shrinker_run_no;
235 } while (run_no == 0);
236
237 /* Iterate over all mounted superblocks and try to shrink them */
238 p = erofs_sb_list.next;
239 while (p != &erofs_sb_list) {
240 sbi = list_entry(p, struct erofs_sb_info, list);
241
242 /*
243 * We move the ones we do to the end of the list, so we stop
244 * when we see one we have already done.
245 */
246 if (sbi->shrinker_run_no == run_no)
247 break;
248
249 if (!mutex_trylock(&sbi->umount_mutex)) {
250 p = p->next;
251 continue;
252 }
253
254 spin_unlock(&erofs_sb_list_lock);
255 sbi->shrinker_run_no = run_no;
256
257 freed += erofs_shrink_workstation(sbi, nr - freed);
258
259 spin_lock(&erofs_sb_list_lock);
260 /* Get the next list element before we move this one */
261 p = p->next;
262
263 /*
264 * Move this one to the end of the list to provide some
265 * fairness.
266 */
267 list_move_tail(&sbi->list, &erofs_sb_list);
268 mutex_unlock(&sbi->umount_mutex);
269
270 if (freed >= nr)
271 break;
272 }
273 spin_unlock(&erofs_sb_list_lock);
274 return freed;
275}
276
277static struct shrinker erofs_shrinker_info = {
278 .scan_objects = erofs_shrink_scan,
279 .count_objects = erofs_shrink_count,
280 .seeks = DEFAULT_SEEKS,
281};
282
283int __init erofs_init_shrinker(void)
284{
285 return register_shrinker(&erofs_shrinker_info);
286}
287
288void erofs_exit_shrinker(void)
289{
290 unregister_shrinker(&erofs_shrinker_info);
291}
292#endif /* !CONFIG_EROFS_FS_ZIP */
293