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eafc474e CM |
1 | // SPDX-License-Identifier: GPL-2.0-only |
2 | /* | |
3 | * In memory quota format relies on quota infrastructure to store dquot | |
4 | * information for us. While conventional quota formats for file systems | |
5 | * with persistent storage can load quota information into dquot from the | |
6 | * storage on-demand and hence quota dquot shrinker can free any dquot | |
7 | * that is not currently being used, it must be avoided here. Otherwise we | |
8 | * can lose valuable information, user provided limits, because there is | |
9 | * no persistent storage to load the information from afterwards. | |
10 | * | |
11 | * One information that in-memory quota format needs to keep track of is | |
12 | * a sorted list of ids for each quota type. This is done by utilizing | |
13 | * an rb tree which root is stored in mem_dqinfo->dqi_priv for each quota | |
14 | * type. | |
15 | * | |
16 | * This format can be used to support quota on file system without persistent | |
17 | * storage such as tmpfs. | |
18 | * | |
19 | * Author: Lukas Czerner <lczerner@redhat.com> | |
20 | * Carlos Maiolino <cmaiolino@redhat.com> | |
21 | * | |
22 | * Copyright (C) 2023 Red Hat, Inc. | |
23 | */ | |
24 | #include <linux/errno.h> | |
25 | #include <linux/fs.h> | |
26 | #include <linux/mount.h> | |
27 | #include <linux/kernel.h> | |
28 | #include <linux/init.h> | |
29 | #include <linux/module.h> | |
30 | #include <linux/slab.h> | |
31 | #include <linux/rbtree.h> | |
32 | #include <linux/shmem_fs.h> | |
33 | ||
34 | #include <linux/quotaops.h> | |
35 | #include <linux/quota.h> | |
36 | ||
37 | #ifdef CONFIG_TMPFS_QUOTA | |
38 | ||
39 | /* | |
40 | * The following constants define the amount of time given a user | |
41 | * before the soft limits are treated as hard limits (usually resulting | |
42 | * in an allocation failure). The timer is started when the user crosses | |
43 | * their soft limit, it is reset when they go below their soft limit. | |
44 | */ | |
45 | #define SHMEM_MAX_IQ_TIME 604800 /* (7*24*60*60) 1 week */ | |
46 | #define SHMEM_MAX_DQ_TIME 604800 /* (7*24*60*60) 1 week */ | |
47 | ||
48 | struct quota_id { | |
49 | struct rb_node node; | |
50 | qid_t id; | |
51 | qsize_t bhardlimit; | |
52 | qsize_t bsoftlimit; | |
53 | qsize_t ihardlimit; | |
54 | qsize_t isoftlimit; | |
55 | }; | |
56 | ||
57 | static int shmem_check_quota_file(struct super_block *sb, int type) | |
58 | { | |
59 | /* There is no real quota file, nothing to do */ | |
60 | return 1; | |
61 | } | |
62 | ||
63 | /* | |
64 | * There is no real quota file. Just allocate rb_root for quota ids and | |
65 | * set limits | |
66 | */ | |
67 | static int shmem_read_file_info(struct super_block *sb, int type) | |
68 | { | |
69 | struct quota_info *dqopt = sb_dqopt(sb); | |
70 | struct mem_dqinfo *info = &dqopt->info[type]; | |
71 | ||
72 | info->dqi_priv = kzalloc(sizeof(struct rb_root), GFP_NOFS); | |
73 | if (!info->dqi_priv) | |
74 | return -ENOMEM; | |
75 | ||
76 | info->dqi_max_spc_limit = SHMEM_QUOTA_MAX_SPC_LIMIT; | |
77 | info->dqi_max_ino_limit = SHMEM_QUOTA_MAX_INO_LIMIT; | |
78 | ||
79 | info->dqi_bgrace = SHMEM_MAX_DQ_TIME; | |
80 | info->dqi_igrace = SHMEM_MAX_IQ_TIME; | |
81 | info->dqi_flags = 0; | |
82 | ||
83 | return 0; | |
84 | } | |
85 | ||
86 | static int shmem_write_file_info(struct super_block *sb, int type) | |
87 | { | |
88 | /* There is no real quota file, nothing to do */ | |
89 | return 0; | |
90 | } | |
91 | ||
92 | /* | |
93 | * Free all the quota_id entries in the rb tree and rb_root. | |
94 | */ | |
95 | static int shmem_free_file_info(struct super_block *sb, int type) | |
96 | { | |
97 | struct mem_dqinfo *info = &sb_dqopt(sb)->info[type]; | |
98 | struct rb_root *root = info->dqi_priv; | |
99 | struct quota_id *entry; | |
100 | struct rb_node *node; | |
101 | ||
102 | info->dqi_priv = NULL; | |
103 | node = rb_first(root); | |
104 | while (node) { | |
105 | entry = rb_entry(node, struct quota_id, node); | |
106 | node = rb_next(&entry->node); | |
107 | ||
108 | rb_erase(&entry->node, root); | |
109 | kfree(entry); | |
110 | } | |
111 | ||
112 | kfree(root); | |
113 | return 0; | |
114 | } | |
115 | ||
116 | static int shmem_get_next_id(struct super_block *sb, struct kqid *qid) | |
117 | { | |
118 | struct mem_dqinfo *info = sb_dqinfo(sb, qid->type); | |
0a69b6b3 | 119 | struct rb_node *node; |
eafc474e CM |
120 | qid_t id = from_kqid(&init_user_ns, *qid); |
121 | struct quota_info *dqopt = sb_dqopt(sb); | |
122 | struct quota_id *entry = NULL; | |
123 | int ret = 0; | |
124 | ||
125 | if (!sb_has_quota_active(sb, qid->type)) | |
126 | return -ESRCH; | |
127 | ||
128 | down_read(&dqopt->dqio_sem); | |
0a69b6b3 | 129 | node = ((struct rb_root *)info->dqi_priv)->rb_node; |
eafc474e CM |
130 | while (node) { |
131 | entry = rb_entry(node, struct quota_id, node); | |
132 | ||
133 | if (id < entry->id) | |
134 | node = node->rb_left; | |
135 | else if (id > entry->id) | |
136 | node = node->rb_right; | |
137 | else | |
138 | goto got_next_id; | |
139 | } | |
140 | ||
141 | if (!entry) { | |
142 | ret = -ENOENT; | |
143 | goto out_unlock; | |
144 | } | |
145 | ||
146 | if (id > entry->id) { | |
147 | node = rb_next(&entry->node); | |
148 | if (!node) { | |
149 | ret = -ENOENT; | |
150 | goto out_unlock; | |
151 | } | |
152 | entry = rb_entry(node, struct quota_id, node); | |
153 | } | |
154 | ||
155 | got_next_id: | |
156 | *qid = make_kqid(&init_user_ns, qid->type, entry->id); | |
157 | out_unlock: | |
158 | up_read(&dqopt->dqio_sem); | |
159 | return ret; | |
160 | } | |
161 | ||
162 | /* | |
163 | * Load dquot with limits from existing entry, or create the new entry if | |
164 | * it does not exist. | |
165 | */ | |
166 | static int shmem_acquire_dquot(struct dquot *dquot) | |
167 | { | |
168 | struct mem_dqinfo *info = sb_dqinfo(dquot->dq_sb, dquot->dq_id.type); | |
0a69b6b3 | 169 | struct rb_node **n; |
de4c0e7c | 170 | struct shmem_sb_info *sbinfo = dquot->dq_sb->s_fs_info; |
eafc474e CM |
171 | struct rb_node *parent = NULL, *new_node = NULL; |
172 | struct quota_id *new_entry, *entry; | |
173 | qid_t id = from_kqid(&init_user_ns, dquot->dq_id); | |
174 | struct quota_info *dqopt = sb_dqopt(dquot->dq_sb); | |
175 | int ret = 0; | |
176 | ||
177 | mutex_lock(&dquot->dq_lock); | |
178 | ||
179 | down_write(&dqopt->dqio_sem); | |
0a69b6b3 CM |
180 | n = &((struct rb_root *)info->dqi_priv)->rb_node; |
181 | ||
eafc474e CM |
182 | while (*n) { |
183 | parent = *n; | |
184 | entry = rb_entry(parent, struct quota_id, node); | |
185 | ||
186 | if (id < entry->id) | |
187 | n = &(*n)->rb_left; | |
188 | else if (id > entry->id) | |
189 | n = &(*n)->rb_right; | |
190 | else | |
191 | goto found; | |
192 | } | |
193 | ||
194 | /* We don't have entry for this id yet, create it */ | |
195 | new_entry = kzalloc(sizeof(struct quota_id), GFP_NOFS); | |
196 | if (!new_entry) { | |
197 | ret = -ENOMEM; | |
198 | goto out_unlock; | |
199 | } | |
200 | ||
201 | new_entry->id = id; | |
de4c0e7c LC |
202 | if (dquot->dq_id.type == USRQUOTA) { |
203 | new_entry->bhardlimit = sbinfo->qlimits.usrquota_bhardlimit; | |
204 | new_entry->ihardlimit = sbinfo->qlimits.usrquota_ihardlimit; | |
205 | } else if (dquot->dq_id.type == GRPQUOTA) { | |
206 | new_entry->bhardlimit = sbinfo->qlimits.grpquota_bhardlimit; | |
207 | new_entry->ihardlimit = sbinfo->qlimits.grpquota_ihardlimit; | |
208 | } | |
209 | ||
eafc474e CM |
210 | new_node = &new_entry->node; |
211 | rb_link_node(new_node, parent, n); | |
212 | rb_insert_color(new_node, (struct rb_root *)info->dqi_priv); | |
213 | entry = new_entry; | |
214 | ||
215 | found: | |
216 | /* Load the stored limits from the tree */ | |
217 | spin_lock(&dquot->dq_dqb_lock); | |
218 | dquot->dq_dqb.dqb_bhardlimit = entry->bhardlimit; | |
219 | dquot->dq_dqb.dqb_bsoftlimit = entry->bsoftlimit; | |
220 | dquot->dq_dqb.dqb_ihardlimit = entry->ihardlimit; | |
221 | dquot->dq_dqb.dqb_isoftlimit = entry->isoftlimit; | |
222 | ||
223 | if (!dquot->dq_dqb.dqb_bhardlimit && | |
224 | !dquot->dq_dqb.dqb_bsoftlimit && | |
225 | !dquot->dq_dqb.dqb_ihardlimit && | |
226 | !dquot->dq_dqb.dqb_isoftlimit) | |
227 | set_bit(DQ_FAKE_B, &dquot->dq_flags); | |
228 | spin_unlock(&dquot->dq_dqb_lock); | |
229 | ||
230 | /* Make sure flags update is visible after dquot has been filled */ | |
231 | smp_mb__before_atomic(); | |
232 | set_bit(DQ_ACTIVE_B, &dquot->dq_flags); | |
233 | out_unlock: | |
234 | up_write(&dqopt->dqio_sem); | |
235 | mutex_unlock(&dquot->dq_lock); | |
236 | return ret; | |
237 | } | |
238 | ||
de4c0e7c LC |
239 | static bool shmem_is_empty_dquot(struct dquot *dquot) |
240 | { | |
241 | struct shmem_sb_info *sbinfo = dquot->dq_sb->s_fs_info; | |
242 | qsize_t bhardlimit; | |
243 | qsize_t ihardlimit; | |
244 | ||
245 | if (dquot->dq_id.type == USRQUOTA) { | |
246 | bhardlimit = sbinfo->qlimits.usrquota_bhardlimit; | |
247 | ihardlimit = sbinfo->qlimits.usrquota_ihardlimit; | |
248 | } else if (dquot->dq_id.type == GRPQUOTA) { | |
249 | bhardlimit = sbinfo->qlimits.grpquota_bhardlimit; | |
250 | ihardlimit = sbinfo->qlimits.grpquota_ihardlimit; | |
251 | } | |
252 | ||
253 | if (test_bit(DQ_FAKE_B, &dquot->dq_flags) || | |
254 | (dquot->dq_dqb.dqb_curspace == 0 && | |
255 | dquot->dq_dqb.dqb_curinodes == 0 && | |
256 | dquot->dq_dqb.dqb_bhardlimit == bhardlimit && | |
257 | dquot->dq_dqb.dqb_ihardlimit == ihardlimit)) | |
258 | return true; | |
259 | ||
260 | return false; | |
261 | } | |
eafc474e CM |
262 | /* |
263 | * Store limits from dquot in the tree unless it's fake. If it is fake | |
264 | * remove the id from the tree since there is no useful information in | |
265 | * there. | |
266 | */ | |
267 | static int shmem_release_dquot(struct dquot *dquot) | |
268 | { | |
269 | struct mem_dqinfo *info = sb_dqinfo(dquot->dq_sb, dquot->dq_id.type); | |
0a69b6b3 | 270 | struct rb_node *node; |
eafc474e CM |
271 | qid_t id = from_kqid(&init_user_ns, dquot->dq_id); |
272 | struct quota_info *dqopt = sb_dqopt(dquot->dq_sb); | |
273 | struct quota_id *entry = NULL; | |
274 | ||
275 | mutex_lock(&dquot->dq_lock); | |
276 | /* Check whether we are not racing with some other dqget() */ | |
277 | if (dquot_is_busy(dquot)) | |
278 | goto out_dqlock; | |
279 | ||
280 | down_write(&dqopt->dqio_sem); | |
0a69b6b3 | 281 | node = ((struct rb_root *)info->dqi_priv)->rb_node; |
eafc474e CM |
282 | while (node) { |
283 | entry = rb_entry(node, struct quota_id, node); | |
284 | ||
285 | if (id < entry->id) | |
286 | node = node->rb_left; | |
287 | else if (id > entry->id) | |
288 | node = node->rb_right; | |
289 | else | |
290 | goto found; | |
291 | } | |
292 | ||
293 | /* We should always find the entry in the rb tree */ | |
294 | WARN_ONCE(1, "quota id %u from dquot %p, not in rb tree!\n", id, dquot); | |
295 | up_write(&dqopt->dqio_sem); | |
296 | mutex_unlock(&dquot->dq_lock); | |
297 | return -ENOENT; | |
298 | ||
299 | found: | |
de4c0e7c | 300 | if (shmem_is_empty_dquot(dquot)) { |
eafc474e CM |
301 | /* Remove entry from the tree */ |
302 | rb_erase(&entry->node, info->dqi_priv); | |
303 | kfree(entry); | |
304 | } else { | |
305 | /* Store the limits in the tree */ | |
306 | spin_lock(&dquot->dq_dqb_lock); | |
307 | entry->bhardlimit = dquot->dq_dqb.dqb_bhardlimit; | |
308 | entry->bsoftlimit = dquot->dq_dqb.dqb_bsoftlimit; | |
309 | entry->ihardlimit = dquot->dq_dqb.dqb_ihardlimit; | |
310 | entry->isoftlimit = dquot->dq_dqb.dqb_isoftlimit; | |
311 | spin_unlock(&dquot->dq_dqb_lock); | |
312 | } | |
313 | ||
314 | clear_bit(DQ_ACTIVE_B, &dquot->dq_flags); | |
315 | up_write(&dqopt->dqio_sem); | |
316 | ||
317 | out_dqlock: | |
318 | mutex_unlock(&dquot->dq_lock); | |
319 | return 0; | |
320 | } | |
321 | ||
322 | static int shmem_mark_dquot_dirty(struct dquot *dquot) | |
323 | { | |
324 | return 0; | |
325 | } | |
326 | ||
327 | static int shmem_dquot_write_info(struct super_block *sb, int type) | |
328 | { | |
329 | return 0; | |
330 | } | |
331 | ||
332 | static const struct quota_format_ops shmem_format_ops = { | |
333 | .check_quota_file = shmem_check_quota_file, | |
334 | .read_file_info = shmem_read_file_info, | |
335 | .write_file_info = shmem_write_file_info, | |
336 | .free_file_info = shmem_free_file_info, | |
337 | }; | |
338 | ||
339 | struct quota_format_type shmem_quota_format = { | |
340 | .qf_fmt_id = QFMT_SHMEM, | |
341 | .qf_ops = &shmem_format_ops, | |
342 | .qf_owner = THIS_MODULE | |
343 | }; | |
344 | ||
345 | const struct dquot_operations shmem_quota_operations = { | |
346 | .acquire_dquot = shmem_acquire_dquot, | |
347 | .release_dquot = shmem_release_dquot, | |
348 | .alloc_dquot = dquot_alloc, | |
349 | .destroy_dquot = dquot_destroy, | |
350 | .write_info = shmem_dquot_write_info, | |
351 | .mark_dirty = shmem_mark_dquot_dirty, | |
352 | .get_next_id = shmem_get_next_id, | |
353 | }; | |
354 | #endif /* CONFIG_TMPFS_QUOTA */ |