1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* AFS volume management
3 *
4 * Copyright (C) 2002, 2007 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells (dhowells@redhat.com)
6 */
7
8 #include <linux/kernel.h>
9 #include <linux/slab.h>
10 #include "internal.h"
11
12 unsigned __read_mostly afs_volume_gc_delay = 10;
13 unsigned __read_mostly afs_volume_record_life = 60 * 60;
14
15 /*
16 * Allocate a volume record and load it up from a vldb record.
17 */
afs_alloc_volume(struct afs_fs_context * params,struct afs_vldb_entry * vldb,unsigned long type_mask)18 static struct afs_volume *afs_alloc_volume(struct afs_fs_context *params,
19 struct afs_vldb_entry *vldb,
20 unsigned long type_mask)
21 {
22 struct afs_server_list *slist;
23 struct afs_volume *volume;
24 int ret = -ENOMEM, nr_servers = 0, i;
25
26 for (i = 0; i < vldb->nr_servers; i++)
27 if (vldb->fs_mask[i] & type_mask)
28 nr_servers++;
29
30 volume = kzalloc(sizeof(struct afs_volume), GFP_KERNEL);
31 if (!volume)
32 goto error_0;
33
34 volume->vid = vldb->vid[params->type];
35 volume->update_at = ktime_get_real_seconds() + afs_volume_record_life;
36 volume->cell = afs_get_cell(params->cell);
37 volume->type = params->type;
38 volume->type_force = params->force;
39 volume->name_len = vldb->name_len;
40
41 atomic_set(&volume->usage, 1);
42 INIT_LIST_HEAD(&volume->proc_link);
43 rwlock_init(&volume->servers_lock);
44 rwlock_init(&volume->cb_v_break_lock);
45 memcpy(volume->name, vldb->name, vldb->name_len + 1);
46
47 slist = afs_alloc_server_list(params->cell, params->key, vldb, type_mask);
48 if (IS_ERR(slist)) {
49 ret = PTR_ERR(slist);
50 goto error_1;
51 }
52
53 refcount_set(&slist->usage, 1);
54 volume->servers = slist;
55 return volume;
56
57 error_1:
58 afs_put_cell(params->net, volume->cell);
59 kfree(volume);
60 error_0:
61 return ERR_PTR(ret);
62 }
63
64 /*
65 * Look up a VLDB record for a volume.
66 */
afs_vl_lookup_vldb(struct afs_cell * cell,struct key * key,const char * volname,size_t volnamesz)67 static struct afs_vldb_entry *afs_vl_lookup_vldb(struct afs_cell *cell,
68 struct key *key,
69 const char *volname,
70 size_t volnamesz)
71 {
72 struct afs_vldb_entry *vldb = ERR_PTR(-EDESTADDRREQ);
73 struct afs_vl_cursor vc;
74 int ret;
75
76 if (!afs_begin_vlserver_operation(&vc, cell, key))
77 return ERR_PTR(-ERESTARTSYS);
78
79 while (afs_select_vlserver(&vc)) {
80 vldb = afs_vl_get_entry_by_name_u(&vc, volname, volnamesz);
81 }
82
83 ret = afs_end_vlserver_operation(&vc);
84 return ret < 0 ? ERR_PTR(ret) : vldb;
85 }
86
87 /*
88 * Look up a volume in the VL server and create a candidate volume record for
89 * it.
90 *
91 * The volume name can be one of the following:
92 * "%[cell:]volume[.]" R/W volume
93 * "#[cell:]volume[.]" R/O or R/W volume (rwparent=0),
94 * or R/W (rwparent=1) volume
95 * "%[cell:]volume.readonly" R/O volume
96 * "#[cell:]volume.readonly" R/O volume
97 * "%[cell:]volume.backup" Backup volume
98 * "#[cell:]volume.backup" Backup volume
99 *
100 * The cell name is optional, and defaults to the current cell.
101 *
102 * See "The Rules of Mount Point Traversal" in Chapter 5 of the AFS SysAdmin
103 * Guide
104 * - Rule 1: Explicit type suffix forces access of that type or nothing
105 * (no suffix, then use Rule 2 & 3)
106 * - Rule 2: If parent volume is R/O, then mount R/O volume by preference, R/W
107 * if not available
108 * - Rule 3: If parent volume is R/W, then only mount R/W volume unless
109 * explicitly told otherwise
110 */
afs_create_volume(struct afs_fs_context * params)111 struct afs_volume *afs_create_volume(struct afs_fs_context *params)
112 {
113 struct afs_vldb_entry *vldb;
114 struct afs_volume *volume;
115 unsigned long type_mask = 1UL << params->type;
116
117 vldb = afs_vl_lookup_vldb(params->cell, params->key,
118 params->volname, params->volnamesz);
119 if (IS_ERR(vldb))
120 return ERR_CAST(vldb);
121
122 if (test_bit(AFS_VLDB_QUERY_ERROR, &vldb->flags)) {
123 volume = ERR_PTR(vldb->error);
124 goto error;
125 }
126
127 /* Make the final decision on the type we want */
128 volume = ERR_PTR(-ENOMEDIUM);
129 if (params->force) {
130 if (!(vldb->flags & type_mask))
131 goto error;
132 } else if (test_bit(AFS_VLDB_HAS_RO, &vldb->flags)) {
133 params->type = AFSVL_ROVOL;
134 } else if (test_bit(AFS_VLDB_HAS_RW, &vldb->flags)) {
135 params->type = AFSVL_RWVOL;
136 } else {
137 goto error;
138 }
139
140 type_mask = 1UL << params->type;
141 volume = afs_alloc_volume(params, vldb, type_mask);
142
143 error:
144 kfree(vldb);
145 return volume;
146 }
147
148 /*
149 * Destroy a volume record
150 */
afs_destroy_volume(struct afs_net * net,struct afs_volume * volume)151 static void afs_destroy_volume(struct afs_net *net, struct afs_volume *volume)
152 {
153 _enter("%p", volume);
154
155 #ifdef CONFIG_AFS_FSCACHE
156 ASSERTCMP(volume->cache, ==, NULL);
157 #endif
158
159 afs_put_serverlist(net, volume->servers);
160 afs_put_cell(net, volume->cell);
161 kfree(volume);
162
163 _leave(" [destroyed]");
164 }
165
166 /*
167 * Drop a reference on a volume record.
168 */
afs_put_volume(struct afs_cell * cell,struct afs_volume * volume)169 void afs_put_volume(struct afs_cell *cell, struct afs_volume *volume)
170 {
171 if (volume) {
172 _enter("%s", volume->name);
173
174 if (atomic_dec_and_test(&volume->usage))
175 afs_destroy_volume(cell->net, volume);
176 }
177 }
178
179 /*
180 * Activate a volume.
181 */
afs_activate_volume(struct afs_volume * volume)182 void afs_activate_volume(struct afs_volume *volume)
183 {
184 #ifdef CONFIG_AFS_FSCACHE
185 volume->cache = fscache_acquire_cookie(volume->cell->cache,
186 &afs_volume_cache_index_def,
187 &volume->vid, sizeof(volume->vid),
188 NULL, 0,
189 volume, 0, true);
190 #endif
191
192 write_lock(&volume->cell->proc_lock);
193 list_add_tail(&volume->proc_link, &volume->cell->proc_volumes);
194 write_unlock(&volume->cell->proc_lock);
195 }
196
197 /*
198 * Deactivate a volume.
199 */
afs_deactivate_volume(struct afs_volume * volume)200 void afs_deactivate_volume(struct afs_volume *volume)
201 {
202 _enter("%s", volume->name);
203
204 write_lock(&volume->cell->proc_lock);
205 list_del_init(&volume->proc_link);
206 write_unlock(&volume->cell->proc_lock);
207
208 #ifdef CONFIG_AFS_FSCACHE
209 fscache_relinquish_cookie(volume->cache, NULL,
210 test_bit(AFS_VOLUME_DELETED, &volume->flags));
211 volume->cache = NULL;
212 #endif
213
214 _leave("");
215 }
216
217 /*
218 * Query the VL service to update the volume status.
219 */
afs_update_volume_status(struct afs_volume * volume,struct key * key)220 static int afs_update_volume_status(struct afs_volume *volume, struct key *key)
221 {
222 struct afs_server_list *new, *old, *discard;
223 struct afs_vldb_entry *vldb;
224 char idbuf[16];
225 int ret, idsz;
226
227 _enter("");
228
229 /* We look up an ID by passing it as a decimal string in the
230 * operation's name parameter.
231 */
232 idsz = sprintf(idbuf, "%llu", volume->vid);
233
234 vldb = afs_vl_lookup_vldb(volume->cell, key, idbuf, idsz);
235 if (IS_ERR(vldb)) {
236 ret = PTR_ERR(vldb);
237 goto error;
238 }
239
240 /* See if the volume got renamed. */
241 if (vldb->name_len != volume->name_len ||
242 memcmp(vldb->name, volume->name, vldb->name_len) != 0) {
243 /* TODO: Use RCU'd string. */
244 memcpy(volume->name, vldb->name, AFS_MAXVOLNAME);
245 volume->name_len = vldb->name_len;
246 }
247
248 /* See if the volume's server list got updated. */
249 new = afs_alloc_server_list(volume->cell, key,
250 vldb, (1 << volume->type));
251 if (IS_ERR(new)) {
252 ret = PTR_ERR(new);
253 goto error_vldb;
254 }
255
256 write_lock(&volume->servers_lock);
257
258 discard = new;
259 old = volume->servers;
260 if (afs_annotate_server_list(new, old)) {
261 new->seq = volume->servers_seq + 1;
262 volume->servers = new;
263 smp_wmb();
264 volume->servers_seq++;
265 discard = old;
266 }
267
268 volume->update_at = ktime_get_real_seconds() + afs_volume_record_life;
269 clear_bit(AFS_VOLUME_NEEDS_UPDATE, &volume->flags);
270 write_unlock(&volume->servers_lock);
271 ret = 0;
272
273 afs_put_serverlist(volume->cell->net, discard);
274 error_vldb:
275 kfree(vldb);
276 error:
277 _leave(" = %d", ret);
278 return ret;
279 }
280
281 /*
282 * Make sure the volume record is up to date.
283 */
afs_check_volume_status(struct afs_volume * volume,struct key * key)284 int afs_check_volume_status(struct afs_volume *volume, struct key *key)
285 {
286 time64_t now = ktime_get_real_seconds();
287 int ret, retries = 0;
288
289 _enter("");
290
291 if (volume->update_at <= now)
292 set_bit(AFS_VOLUME_NEEDS_UPDATE, &volume->flags);
293
294 retry:
295 if (!test_bit(AFS_VOLUME_NEEDS_UPDATE, &volume->flags) &&
296 !test_bit(AFS_VOLUME_WAIT, &volume->flags)) {
297 _leave(" = 0");
298 return 0;
299 }
300
301 if (!test_and_set_bit_lock(AFS_VOLUME_UPDATING, &volume->flags)) {
302 ret = afs_update_volume_status(volume, key);
303 clear_bit_unlock(AFS_VOLUME_WAIT, &volume->flags);
304 clear_bit_unlock(AFS_VOLUME_UPDATING, &volume->flags);
305 wake_up_bit(&volume->flags, AFS_VOLUME_WAIT);
306 _leave(" = %d", ret);
307 return ret;
308 }
309
310 if (!test_bit(AFS_VOLUME_WAIT, &volume->flags)) {
311 _leave(" = 0 [no wait]");
312 return 0;
313 }
314
315 ret = wait_on_bit(&volume->flags, AFS_VOLUME_WAIT, TASK_INTERRUPTIBLE);
316 if (ret == -ERESTARTSYS) {
317 _leave(" = %d", ret);
318 return ret;
319 }
320
321 retries++;
322 if (retries == 4) {
323 _leave(" = -ESTALE");
324 return -ESTALE;
325 }
326 goto retry;
327 }
328