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
12static unsigned __read_mostly afs_volume_record_life = 60 * 60;
13static atomic_t afs_volume_debug_id;
14
15static void afs_destroy_volume(struct work_struct *work);
16
17/*
18 * Insert a volume into a cell. If there's an existing volume record, that is
19 * returned instead with a ref held.
20 */
21static struct afs_volume *afs_insert_volume_into_cell(struct afs_cell *cell,
22 struct afs_volume *volume)
23{
24 struct afs_volume *p;
25 struct rb_node *parent = NULL, **pp;
26
27 write_seqlock(sl: &cell->volume_lock);
28
29 pp = &cell->volumes.rb_node;
30 while (*pp) {
31 parent = *pp;
32 p = rb_entry(parent, struct afs_volume, cell_node);
33 if (p->vid < volume->vid) {
34 pp = &(*pp)->rb_left;
35 } else if (p->vid > volume->vid) {
36 pp = &(*pp)->rb_right;
37 } else {
38 if (afs_try_get_volume(volume: p, reason: afs_volume_trace_get_cell_insert)) {
39 volume = p;
40 goto found;
41 }
42
43 set_bit(AFS_VOLUME_RM_TREE, addr: &volume->flags);
44 rb_replace_node_rcu(victim: &p->cell_node, new: &volume->cell_node, root: &cell->volumes);
45 }
46 }
47
48 rb_link_node_rcu(node: &volume->cell_node, parent, rb_link: pp);
49 rb_insert_color(&volume->cell_node, &cell->volumes);
50 hlist_add_head_rcu(n: &volume->proc_link, h: &cell->proc_volumes);
51
52found:
53 write_sequnlock(sl: &cell->volume_lock);
54 return volume;
55
56}
57
58static void afs_remove_volume_from_cell(struct afs_volume *volume)
59{
60 struct afs_cell *cell = volume->cell;
61
62 if (!hlist_unhashed(h: &volume->proc_link)) {
63 trace_afs_volume(debug_id: volume->debug_id, vid: volume->vid, ref: refcount_read(r: &volume->ref),
64 reason: afs_volume_trace_remove);
65 write_seqlock(sl: &cell->volume_lock);
66 hlist_del_rcu(n: &volume->proc_link);
67 if (!test_and_set_bit(AFS_VOLUME_RM_TREE, addr: &volume->flags))
68 rb_erase(&volume->cell_node, &cell->volumes);
69 write_sequnlock(sl: &cell->volume_lock);
70 }
71}
72
73/*
74 * Allocate a volume record and load it up from a vldb record.
75 */
76static struct afs_volume *afs_alloc_volume(struct afs_fs_context *params,
77 struct afs_vldb_entry *vldb,
78 struct afs_server_list **_slist)
79{
80 struct afs_server_list *slist;
81 struct afs_volume *volume;
82 int ret = -ENOMEM, i;
83
84 volume = kzalloc(sizeof(struct afs_volume), GFP_KERNEL);
85 if (!volume)
86 goto error_0;
87
88 volume->debug_id = atomic_inc_return(v: &afs_volume_debug_id);
89 volume->vid = vldb->vid[params->type];
90 volume->update_at = ktime_get_real_seconds() + afs_volume_record_life;
91 volume->cell = afs_get_cell(params->cell, afs_cell_trace_get_vol);
92 volume->type = params->type;
93 volume->type_force = params->force;
94 volume->name_len = vldb->name_len;
95 volume->creation_time = TIME64_MIN;
96 volume->update_time = TIME64_MIN;
97
98 refcount_set(r: &volume->ref, n: 1);
99 INIT_HLIST_NODE(h: &volume->proc_link);
100 INIT_WORK(&volume->destructor, afs_destroy_volume);
101 rwlock_init(&volume->servers_lock);
102 mutex_init(&volume->volsync_lock);
103 mutex_init(&volume->cb_check_lock);
104 rwlock_init(&volume->cb_v_break_lock);
105 INIT_LIST_HEAD(list: &volume->open_mmaps);
106 init_rwsem(&volume->open_mmaps_lock);
107 memcpy(volume->name, vldb->name, vldb->name_len + 1);
108
109 for (i = 0; i < AFS_MAXTYPES; i++)
110 volume->vids[i] = vldb->vid[i];
111
112 slist = afs_alloc_server_list(volume, key: params->key, vldb);
113 if (IS_ERR(ptr: slist)) {
114 ret = PTR_ERR(ptr: slist);
115 goto error_1;
116 }
117
118 *_slist = slist;
119 rcu_assign_pointer(volume->servers, slist);
120 trace_afs_volume(debug_id: volume->debug_id, vid: volume->vid, ref: 1, reason: afs_volume_trace_alloc);
121 return volume;
122
123error_1:
124 afs_put_cell(volume->cell, afs_cell_trace_put_vol);
125 kfree(objp: volume);
126error_0:
127 return ERR_PTR(error: ret);
128}
129
130/*
131 * Look up or allocate a volume record.
132 */
133static struct afs_volume *afs_lookup_volume(struct afs_fs_context *params,
134 struct afs_vldb_entry *vldb)
135{
136 struct afs_server_list *slist;
137 struct afs_volume *candidate, *volume;
138
139 candidate = afs_alloc_volume(params, vldb, slist: &slist);
140 if (IS_ERR(ptr: candidate))
141 return candidate;
142
143 volume = afs_insert_volume_into_cell(cell: params->cell, volume: candidate);
144 if (volume == candidate)
145 afs_attach_volume_to_servers(volume, slist);
146 else
147 afs_put_volume(volume: candidate, reason: afs_volume_trace_put_cell_dup);
148 return volume;
149}
150
151/*
152 * Look up a VLDB record for a volume.
153 */
154static struct afs_vldb_entry *afs_vl_lookup_vldb(struct afs_cell *cell,
155 struct key *key,
156 const char *volname,
157 size_t volnamesz)
158{
159 struct afs_vldb_entry *vldb = ERR_PTR(error: -EDESTADDRREQ);
160 struct afs_vl_cursor vc;
161 int ret;
162
163 if (!afs_begin_vlserver_operation(&vc, cell, key))
164 return ERR_PTR(error: -ERESTARTSYS);
165
166 while (afs_select_vlserver(&vc)) {
167 vldb = afs_vl_get_entry_by_name_u(&vc, volname, volnamesz);
168 }
169
170 ret = afs_end_vlserver_operation(&vc);
171 return ret < 0 ? ERR_PTR(error: ret) : vldb;
172}
173
174/*
175 * Look up a volume in the VL server and create a candidate volume record for
176 * it.
177 *
178 * The volume name can be one of the following:
179 * "%[cell:]volume[.]" R/W volume
180 * "#[cell:]volume[.]" R/O or R/W volume (rwparent=0),
181 * or R/W (rwparent=1) volume
182 * "%[cell:]volume.readonly" R/O volume
183 * "#[cell:]volume.readonly" R/O volume
184 * "%[cell:]volume.backup" Backup volume
185 * "#[cell:]volume.backup" Backup volume
186 *
187 * The cell name is optional, and defaults to the current cell.
188 *
189 * See "The Rules of Mount Point Traversal" in Chapter 5 of the AFS SysAdmin
190 * Guide
191 * - Rule 1: Explicit type suffix forces access of that type or nothing
192 * (no suffix, then use Rule 2 & 3)
193 * - Rule 2: If parent volume is R/O, then mount R/O volume by preference, R/W
194 * if not available
195 * - Rule 3: If parent volume is R/W, then only mount R/W volume unless
196 * explicitly told otherwise
197 */
198struct afs_volume *afs_create_volume(struct afs_fs_context *params)
199{
200 struct afs_vldb_entry *vldb;
201 struct afs_volume *volume;
202 unsigned long type_mask = 1UL << params->type;
203
204 vldb = afs_vl_lookup_vldb(cell: params->cell, key: params->key,
205 volname: params->volname, volnamesz: params->volnamesz);
206 if (IS_ERR(ptr: vldb))
207 return ERR_CAST(ptr: vldb);
208
209 if (test_bit(AFS_VLDB_QUERY_ERROR, &vldb->flags)) {
210 volume = ERR_PTR(error: vldb->error);
211 goto error;
212 }
213
214 /* Make the final decision on the type we want */
215 volume = ERR_PTR(error: -ENOMEDIUM);
216 if (params->force) {
217 if (!(vldb->flags & type_mask))
218 goto error;
219 } else if (test_bit(AFS_VLDB_HAS_RO, &vldb->flags)) {
220 params->type = AFSVL_ROVOL;
221 } else if (test_bit(AFS_VLDB_HAS_RW, &vldb->flags)) {
222 params->type = AFSVL_RWVOL;
223 } else {
224 goto error;
225 }
226
227 volume = afs_lookup_volume(params, vldb);
228
229error:
230 kfree(objp: vldb);
231 return volume;
232}
233
234/*
235 * Destroy a volume record
236 */
237static void afs_destroy_volume(struct work_struct *work)
238{
239 struct afs_volume *volume = container_of(work, struct afs_volume, destructor);
240 struct afs_server_list *slist = rcu_access_pointer(volume->servers);
241
242 _enter("%p", volume);
243
244#ifdef CONFIG_AFS_FSCACHE
245 ASSERTCMP(volume->cache, ==, NULL);
246#endif
247
248 afs_detach_volume_from_servers(volume, slist);
249 afs_remove_volume_from_cell(volume);
250 afs_put_serverlist(volume->cell->net, slist);
251 afs_put_cell(volume->cell, afs_cell_trace_put_vol);
252 trace_afs_volume(debug_id: volume->debug_id, vid: volume->vid, ref: refcount_read(r: &volume->ref),
253 reason: afs_volume_trace_free);
254 kfree_rcu(volume, rcu);
255
256 _leave(" [destroyed]");
257}
258
259/*
260 * Try to get a reference on a volume record.
261 */
262bool afs_try_get_volume(struct afs_volume *volume, enum afs_volume_trace reason)
263{
264 int r;
265
266 if (__refcount_inc_not_zero(r: &volume->ref, oldp: &r)) {
267 trace_afs_volume(debug_id: volume->debug_id, vid: volume->vid, ref: r + 1, reason);
268 return true;
269 }
270 return false;
271}
272
273/*
274 * Get a reference on a volume record.
275 */
276struct afs_volume *afs_get_volume(struct afs_volume *volume,
277 enum afs_volume_trace reason)
278{
279 if (volume) {
280 int r;
281
282 __refcount_inc(r: &volume->ref, oldp: &r);
283 trace_afs_volume(debug_id: volume->debug_id, vid: volume->vid, ref: r + 1, reason);
284 }
285 return volume;
286}
287
288
289/*
290 * Drop a reference on a volume record.
291 */
292void afs_put_volume(struct afs_volume *volume, enum afs_volume_trace reason)
293{
294 if (volume) {
295 unsigned int debug_id = volume->debug_id;
296 afs_volid_t vid = volume->vid;
297 bool zero;
298 int r;
299
300 zero = __refcount_dec_and_test(r: &volume->ref, oldp: &r);
301 trace_afs_volume(debug_id, vid, ref: r - 1, reason);
302 if (zero)
303 schedule_work(work: &volume->destructor);
304 }
305}
306
307/*
308 * Activate a volume.
309 */
310int afs_activate_volume(struct afs_volume *volume)
311{
312#ifdef CONFIG_AFS_FSCACHE
313 struct fscache_volume *vcookie;
314 char *name;
315
316 name = kasprintf(GFP_KERNEL, fmt: "afs,%s,%llx",
317 volume->cell->name, volume->vid);
318 if (!name)
319 return -ENOMEM;
320
321 vcookie = fscache_acquire_volume(volume_key: name, NULL, NULL, coherency_len: 0);
322 if (IS_ERR(ptr: vcookie)) {
323 if (vcookie != ERR_PTR(error: -EBUSY)) {
324 kfree(objp: name);
325 return PTR_ERR(ptr: vcookie);
326 }
327 pr_err("AFS: Cache volume key already in use (%s)\n", name);
328 vcookie = NULL;
329 }
330 volume->cache = vcookie;
331 kfree(objp: name);
332#endif
333 return 0;
334}
335
336/*
337 * Deactivate a volume.
338 */
339void afs_deactivate_volume(struct afs_volume *volume)
340{
341 _enter("%s", volume->name);
342
343#ifdef CONFIG_AFS_FSCACHE
344 fscache_relinquish_volume(volume: volume->cache, NULL,
345 test_bit(AFS_VOLUME_DELETED, &volume->flags));
346 volume->cache = NULL;
347#endif
348
349 _leave("");
350}
351
352/*
353 * Query the VL service to update the volume status.
354 */
355static int afs_update_volume_status(struct afs_volume *volume, struct key *key)
356{
357 struct afs_server_list *new, *old, *discard;
358 struct afs_vldb_entry *vldb;
359 char idbuf[24];
360 int ret, idsz;
361
362 _enter("");
363
364 /* We look up an ID by passing it as a decimal string in the
365 * operation's name parameter.
366 */
367 idsz = snprintf(buf: idbuf, size: sizeof(idbuf), fmt: "%llu", volume->vid);
368
369 vldb = afs_vl_lookup_vldb(cell: volume->cell, key, volname: idbuf, volnamesz: idsz);
370 if (IS_ERR(ptr: vldb)) {
371 ret = PTR_ERR(ptr: vldb);
372 goto error;
373 }
374
375 /* See if the volume got renamed. */
376 if (vldb->name_len != volume->name_len ||
377 memcmp(p: vldb->name, q: volume->name, size: vldb->name_len) != 0) {
378 /* TODO: Use RCU'd string. */
379 memcpy(volume->name, vldb->name, AFS_MAXVOLNAME);
380 volume->name_len = vldb->name_len;
381 }
382
383 /* See if the volume's server list got updated. */
384 new = afs_alloc_server_list(volume, key, vldb);
385 if (IS_ERR(ptr: new)) {
386 ret = PTR_ERR(ptr: new);
387 goto error_vldb;
388 }
389
390 write_lock(&volume->servers_lock);
391
392 discard = new;
393 old = rcu_dereference_protected(volume->servers,
394 lockdep_is_held(&volume->servers_lock));
395 if (afs_annotate_server_list(new, old)) {
396 new->seq = volume->servers_seq + 1;
397 rcu_assign_pointer(volume->servers, new);
398 smp_wmb();
399 volume->servers_seq++;
400 discard = old;
401 }
402
403 /* Check more often if replication is ongoing. */
404 if (new->ro_replicating)
405 volume->update_at = ktime_get_real_seconds() + 10 * 60;
406 else
407 volume->update_at = ktime_get_real_seconds() + afs_volume_record_life;
408 write_unlock(&volume->servers_lock);
409
410 if (discard == old)
411 afs_reattach_volume_to_servers(volume, slist: new, old);
412 afs_put_serverlist(volume->cell->net, discard);
413 ret = 0;
414error_vldb:
415 kfree(objp: vldb);
416error:
417 _leave(" = %d", ret);
418 return ret;
419}
420
421/*
422 * Make sure the volume record is up to date.
423 */
424int afs_check_volume_status(struct afs_volume *volume, struct afs_operation *op)
425{
426 int ret, retries = 0;
427
428 _enter("");
429
430retry:
431 if (test_bit(AFS_VOLUME_WAIT, &volume->flags))
432 goto wait;
433 if (volume->update_at <= ktime_get_real_seconds() ||
434 test_bit(AFS_VOLUME_NEEDS_UPDATE, &volume->flags))
435 goto update;
436 _leave(" = 0");
437 return 0;
438
439update:
440 if (!test_and_set_bit_lock(AFS_VOLUME_UPDATING, addr: &volume->flags)) {
441 clear_bit(AFS_VOLUME_NEEDS_UPDATE, addr: &volume->flags);
442 ret = afs_update_volume_status(volume, key: op->key);
443 if (ret < 0)
444 set_bit(AFS_VOLUME_NEEDS_UPDATE, addr: &volume->flags);
445 clear_bit_unlock(AFS_VOLUME_WAIT, addr: &volume->flags);
446 clear_bit_unlock(AFS_VOLUME_UPDATING, addr: &volume->flags);
447 wake_up_bit(word: &volume->flags, AFS_VOLUME_WAIT);
448 _leave(" = %d", ret);
449 return ret;
450 }
451
452wait:
453 if (!test_bit(AFS_VOLUME_WAIT, &volume->flags)) {
454 _leave(" = 0 [no wait]");
455 return 0;
456 }
457
458 ret = wait_on_bit(word: &volume->flags, AFS_VOLUME_WAIT,
459 mode: (op->flags & AFS_OPERATION_UNINTR) ?
460 TASK_UNINTERRUPTIBLE : TASK_INTERRUPTIBLE);
461 if (ret == -ERESTARTSYS) {
462 _leave(" = %d", ret);
463 return ret;
464 }
465
466 retries++;
467 if (retries == 4) {
468 _leave(" = -ESTALE");
469 return -ESTALE;
470 }
471 goto retry;
472}
473

source code of linux/fs/afs/volume.c