Merge tag 'counter-fixes-for-6.6a' of git://git.kernel.org/pub/scm/linux/kernel/git...
[platform/kernel/linux-starfive.git] / mm / shmem_quota.c
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);
119         struct rb_node *node = ((struct rb_root *)info->dqi_priv)->rb_node;
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);
129         while (node) {
130                 entry = rb_entry(node, struct quota_id, node);
131
132                 if (id < entry->id)
133                         node = node->rb_left;
134                 else if (id > entry->id)
135                         node = node->rb_right;
136                 else
137                         goto got_next_id;
138         }
139
140         if (!entry) {
141                 ret = -ENOENT;
142                 goto out_unlock;
143         }
144
145         if (id > entry->id) {
146                 node = rb_next(&entry->node);
147                 if (!node) {
148                         ret = -ENOENT;
149                         goto out_unlock;
150                 }
151                 entry = rb_entry(node, struct quota_id, node);
152         }
153
154 got_next_id:
155         *qid = make_kqid(&init_user_ns, qid->type, entry->id);
156 out_unlock:
157         up_read(&dqopt->dqio_sem);
158         return ret;
159 }
160
161 /*
162  * Load dquot with limits from existing entry, or create the new entry if
163  * it does not exist.
164  */
165 static int shmem_acquire_dquot(struct dquot *dquot)
166 {
167         struct mem_dqinfo *info = sb_dqinfo(dquot->dq_sb, dquot->dq_id.type);
168         struct rb_node **n = &((struct rb_root *)info->dqi_priv)->rb_node;
169         struct shmem_sb_info *sbinfo = dquot->dq_sb->s_fs_info;
170         struct rb_node *parent = NULL, *new_node = NULL;
171         struct quota_id *new_entry, *entry;
172         qid_t id = from_kqid(&init_user_ns, dquot->dq_id);
173         struct quota_info *dqopt = sb_dqopt(dquot->dq_sb);
174         int ret = 0;
175
176         mutex_lock(&dquot->dq_lock);
177
178         down_write(&dqopt->dqio_sem);
179         while (*n) {
180                 parent = *n;
181                 entry = rb_entry(parent, struct quota_id, node);
182
183                 if (id < entry->id)
184                         n = &(*n)->rb_left;
185                 else if (id > entry->id)
186                         n = &(*n)->rb_right;
187                 else
188                         goto found;
189         }
190
191         /* We don't have entry for this id yet, create it */
192         new_entry = kzalloc(sizeof(struct quota_id), GFP_NOFS);
193         if (!new_entry) {
194                 ret = -ENOMEM;
195                 goto out_unlock;
196         }
197
198         new_entry->id = id;
199         if (dquot->dq_id.type == USRQUOTA) {
200                 new_entry->bhardlimit = sbinfo->qlimits.usrquota_bhardlimit;
201                 new_entry->ihardlimit = sbinfo->qlimits.usrquota_ihardlimit;
202         } else if (dquot->dq_id.type == GRPQUOTA) {
203                 new_entry->bhardlimit = sbinfo->qlimits.grpquota_bhardlimit;
204                 new_entry->ihardlimit = sbinfo->qlimits.grpquota_ihardlimit;
205         }
206
207         new_node = &new_entry->node;
208         rb_link_node(new_node, parent, n);
209         rb_insert_color(new_node, (struct rb_root *)info->dqi_priv);
210         entry = new_entry;
211
212 found:
213         /* Load the stored limits from the tree */
214         spin_lock(&dquot->dq_dqb_lock);
215         dquot->dq_dqb.dqb_bhardlimit = entry->bhardlimit;
216         dquot->dq_dqb.dqb_bsoftlimit = entry->bsoftlimit;
217         dquot->dq_dqb.dqb_ihardlimit = entry->ihardlimit;
218         dquot->dq_dqb.dqb_isoftlimit = entry->isoftlimit;
219
220         if (!dquot->dq_dqb.dqb_bhardlimit &&
221             !dquot->dq_dqb.dqb_bsoftlimit &&
222             !dquot->dq_dqb.dqb_ihardlimit &&
223             !dquot->dq_dqb.dqb_isoftlimit)
224                 set_bit(DQ_FAKE_B, &dquot->dq_flags);
225         spin_unlock(&dquot->dq_dqb_lock);
226
227         /* Make sure flags update is visible after dquot has been filled */
228         smp_mb__before_atomic();
229         set_bit(DQ_ACTIVE_B, &dquot->dq_flags);
230 out_unlock:
231         up_write(&dqopt->dqio_sem);
232         mutex_unlock(&dquot->dq_lock);
233         return ret;
234 }
235
236 static bool shmem_is_empty_dquot(struct dquot *dquot)
237 {
238         struct shmem_sb_info *sbinfo = dquot->dq_sb->s_fs_info;
239         qsize_t bhardlimit;
240         qsize_t ihardlimit;
241
242         if (dquot->dq_id.type == USRQUOTA) {
243                 bhardlimit = sbinfo->qlimits.usrquota_bhardlimit;
244                 ihardlimit = sbinfo->qlimits.usrquota_ihardlimit;
245         } else if (dquot->dq_id.type == GRPQUOTA) {
246                 bhardlimit = sbinfo->qlimits.grpquota_bhardlimit;
247                 ihardlimit = sbinfo->qlimits.grpquota_ihardlimit;
248         }
249
250         if (test_bit(DQ_FAKE_B, &dquot->dq_flags) ||
251                 (dquot->dq_dqb.dqb_curspace == 0 &&
252                  dquot->dq_dqb.dqb_curinodes == 0 &&
253                  dquot->dq_dqb.dqb_bhardlimit == bhardlimit &&
254                  dquot->dq_dqb.dqb_ihardlimit == ihardlimit))
255                 return true;
256
257         return false;
258 }
259 /*
260  * Store limits from dquot in the tree unless it's fake. If it is fake
261  * remove the id from the tree since there is no useful information in
262  * there.
263  */
264 static int shmem_release_dquot(struct dquot *dquot)
265 {
266         struct mem_dqinfo *info = sb_dqinfo(dquot->dq_sb, dquot->dq_id.type);
267         struct rb_node *node = ((struct rb_root *)info->dqi_priv)->rb_node;
268         qid_t id = from_kqid(&init_user_ns, dquot->dq_id);
269         struct quota_info *dqopt = sb_dqopt(dquot->dq_sb);
270         struct quota_id *entry = NULL;
271
272         mutex_lock(&dquot->dq_lock);
273         /* Check whether we are not racing with some other dqget() */
274         if (dquot_is_busy(dquot))
275                 goto out_dqlock;
276
277         down_write(&dqopt->dqio_sem);
278         while (node) {
279                 entry = rb_entry(node, struct quota_id, node);
280
281                 if (id < entry->id)
282                         node = node->rb_left;
283                 else if (id > entry->id)
284                         node = node->rb_right;
285                 else
286                         goto found;
287         }
288
289         /* We should always find the entry in the rb tree */
290         WARN_ONCE(1, "quota id %u from dquot %p, not in rb tree!\n", id, dquot);
291         up_write(&dqopt->dqio_sem);
292         mutex_unlock(&dquot->dq_lock);
293         return -ENOENT;
294
295 found:
296         if (shmem_is_empty_dquot(dquot)) {
297                 /* Remove entry from the tree */
298                 rb_erase(&entry->node, info->dqi_priv);
299                 kfree(entry);
300         } else {
301                 /* Store the limits in the tree */
302                 spin_lock(&dquot->dq_dqb_lock);
303                 entry->bhardlimit = dquot->dq_dqb.dqb_bhardlimit;
304                 entry->bsoftlimit = dquot->dq_dqb.dqb_bsoftlimit;
305                 entry->ihardlimit = dquot->dq_dqb.dqb_ihardlimit;
306                 entry->isoftlimit = dquot->dq_dqb.dqb_isoftlimit;
307                 spin_unlock(&dquot->dq_dqb_lock);
308         }
309
310         clear_bit(DQ_ACTIVE_B, &dquot->dq_flags);
311         up_write(&dqopt->dqio_sem);
312
313 out_dqlock:
314         mutex_unlock(&dquot->dq_lock);
315         return 0;
316 }
317
318 static int shmem_mark_dquot_dirty(struct dquot *dquot)
319 {
320         return 0;
321 }
322
323 static int shmem_dquot_write_info(struct super_block *sb, int type)
324 {
325         return 0;
326 }
327
328 static const struct quota_format_ops shmem_format_ops = {
329         .check_quota_file       = shmem_check_quota_file,
330         .read_file_info         = shmem_read_file_info,
331         .write_file_info        = shmem_write_file_info,
332         .free_file_info         = shmem_free_file_info,
333 };
334
335 struct quota_format_type shmem_quota_format = {
336         .qf_fmt_id = QFMT_SHMEM,
337         .qf_ops = &shmem_format_ops,
338         .qf_owner = THIS_MODULE
339 };
340
341 const struct dquot_operations shmem_quota_operations = {
342         .acquire_dquot          = shmem_acquire_dquot,
343         .release_dquot          = shmem_release_dquot,
344         .alloc_dquot            = dquot_alloc,
345         .destroy_dquot          = dquot_destroy,
346         .write_info             = shmem_dquot_write_info,
347         .mark_dirty             = shmem_mark_dquot_dirty,
348         .get_next_id            = shmem_get_next_id,
349 };
350 #endif /* CONFIG_TMPFS_QUOTA */