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 static const char *const afs_voltypes[] = { "R/W", "R/O", "BAK" }; 16 17 /* 18 * Allocate a volume record and load it up from a vldb record. 19 */ 20 static struct afs_volume *afs_alloc_volume(struct afs_fs_context *params, 21 struct afs_vldb_entry *vldb, 22 unsigned long type_mask) 23 { 24 struct afs_server_list *slist; 25 struct afs_volume *volume; 26 int ret = -ENOMEM, nr_servers = 0, i; 27 28 for (i = 0; i < vldb->nr_servers; i++) 29 if (vldb->fs_mask[i] & type_mask) 30 nr_servers++; 31 32 volume = kzalloc(sizeof(struct afs_volume), GFP_KERNEL); 33 if (!volume) 34 goto error_0; 35 36 volume->vid = vldb->vid[params->type]; 37 volume->update_at = ktime_get_real_seconds() + afs_volume_record_life; 38 volume->cell = afs_get_cell(params->cell); 39 volume->type = params->type; 40 volume->type_force = params->force; 41 volume->name_len = vldb->name_len; 42 43 atomic_set(&volume->usage, 1); 44 INIT_LIST_HEAD(&volume->proc_link); 45 rwlock_init(&volume->servers_lock); 46 memcpy(volume->name, vldb->name, vldb->name_len + 1); 47 48 slist = afs_alloc_server_list(params->cell, params->key, vldb, type_mask); 49 if (IS_ERR(slist)) { 50 ret = PTR_ERR(slist); 51 goto error_1; 52 } 53 54 refcount_set(&slist->usage, 1); 55 volume->servers = slist; 56 return volume; 57 58 error_1: 59 afs_put_cell(params->net, volume->cell); 60 kfree(volume); 61 error_0: 62 return ERR_PTR(ret); 63 } 64 65 /* 66 * Look up a VLDB record for a volume. 67 */ 68 static struct afs_vldb_entry *afs_vl_lookup_vldb(struct afs_cell *cell, 69 struct key *key, 70 const char *volname, 71 size_t volnamesz) 72 { 73 struct afs_vldb_entry *vldb = ERR_PTR(-EDESTADDRREQ); 74 struct afs_vl_cursor vc; 75 int ret; 76 77 if (!afs_begin_vlserver_operation(&vc, cell, key)) 78 return ERR_PTR(-ERESTARTSYS); 79 80 while (afs_select_vlserver(&vc)) { 81 vldb = afs_vl_get_entry_by_name_u(&vc, volname, volnamesz); 82 } 83 84 ret = afs_end_vlserver_operation(&vc); 85 return ret < 0 ? ERR_PTR(ret) : vldb; 86 } 87 88 /* 89 * Look up a volume in the VL server and create a candidate volume record for 90 * it. 91 * 92 * The volume name can be one of the following: 93 * "%[cell:]volume[.]" R/W volume 94 * "#[cell:]volume[.]" R/O or R/W volume (rwparent=0), 95 * or R/W (rwparent=1) volume 96 * "%[cell:]volume.readonly" R/O volume 97 * "#[cell:]volume.readonly" R/O volume 98 * "%[cell:]volume.backup" Backup volume 99 * "#[cell:]volume.backup" Backup volume 100 * 101 * The cell name is optional, and defaults to the current cell. 102 * 103 * See "The Rules of Mount Point Traversal" in Chapter 5 of the AFS SysAdmin 104 * Guide 105 * - Rule 1: Explicit type suffix forces access of that type or nothing 106 * (no suffix, then use Rule 2 & 3) 107 * - Rule 2: If parent volume is R/O, then mount R/O volume by preference, R/W 108 * if not available 109 * - Rule 3: If parent volume is R/W, then only mount R/W volume unless 110 * explicitly told otherwise 111 */ 112 struct afs_volume *afs_create_volume(struct afs_fs_context *params) 113 { 114 struct afs_vldb_entry *vldb; 115 struct afs_volume *volume; 116 unsigned long type_mask = 1UL << params->type; 117 118 vldb = afs_vl_lookup_vldb(params->cell, params->key, 119 params->volname, params->volnamesz); 120 if (IS_ERR(vldb)) 121 return ERR_CAST(vldb); 122 123 if (test_bit(AFS_VLDB_QUERY_ERROR, &vldb->flags)) { 124 volume = ERR_PTR(vldb->error); 125 goto error; 126 } 127 128 /* Make the final decision on the type we want */ 129 volume = ERR_PTR(-ENOMEDIUM); 130 if (params->force) { 131 if (!(vldb->flags & type_mask)) 132 goto error; 133 } else if (test_bit(AFS_VLDB_HAS_RO, &vldb->flags)) { 134 params->type = AFSVL_ROVOL; 135 } else if (test_bit(AFS_VLDB_HAS_RW, &vldb->flags)) { 136 params->type = AFSVL_RWVOL; 137 } else { 138 goto error; 139 } 140 141 type_mask = 1UL << params->type; 142 volume = afs_alloc_volume(params, vldb, type_mask); 143 144 error: 145 kfree(vldb); 146 return volume; 147 } 148 149 /* 150 * Destroy a volume record 151 */ 152 static void afs_destroy_volume(struct afs_net *net, struct afs_volume *volume) 153 { 154 _enter("%p", volume); 155 156 #ifdef CONFIG_AFS_FSCACHE 157 ASSERTCMP(volume->cache, ==, NULL); 158 #endif 159 160 afs_put_serverlist(net, volume->servers); 161 afs_put_cell(net, volume->cell); 162 kfree(volume); 163 164 _leave(" [destroyed]"); 165 } 166 167 /* 168 * Drop a reference on a volume record. 169 */ 170 void afs_put_volume(struct afs_cell *cell, struct afs_volume *volume) 171 { 172 if (volume) { 173 _enter("%s", volume->name); 174 175 if (atomic_dec_and_test(&volume->usage)) 176 afs_destroy_volume(cell->net, volume); 177 } 178 } 179 180 /* 181 * Activate a volume. 182 */ 183 void afs_activate_volume(struct afs_volume *volume) 184 { 185 #ifdef CONFIG_AFS_FSCACHE 186 volume->cache = fscache_acquire_cookie(volume->cell->cache, 187 &afs_volume_cache_index_def, 188 &volume->vid, sizeof(volume->vid), 189 NULL, 0, 190 volume, 0, true); 191 #endif 192 193 write_lock(&volume->cell->proc_lock); 194 list_add_tail(&volume->proc_link, &volume->cell->proc_volumes); 195 write_unlock(&volume->cell->proc_lock); 196 } 197 198 /* 199 * Deactivate a volume. 200 */ 201 void afs_deactivate_volume(struct afs_volume *volume) 202 { 203 _enter("%s", volume->name); 204 205 write_lock(&volume->cell->proc_lock); 206 list_del_init(&volume->proc_link); 207 write_unlock(&volume->cell->proc_lock); 208 209 #ifdef CONFIG_AFS_FSCACHE 210 fscache_relinquish_cookie(volume->cache, NULL, 211 test_bit(AFS_VOLUME_DELETED, &volume->flags)); 212 volume->cache = NULL; 213 #endif 214 215 _leave(""); 216 } 217 218 /* 219 * Query the VL service to update the volume status. 220 */ 221 static int afs_update_volume_status(struct afs_volume *volume, struct key *key) 222 { 223 struct afs_server_list *new, *old, *discard; 224 struct afs_vldb_entry *vldb; 225 char idbuf[16]; 226 int ret, idsz; 227 228 _enter(""); 229 230 /* We look up an ID by passing it as a decimal string in the 231 * operation's name parameter. 232 */ 233 idsz = sprintf(idbuf, "%llu", volume->vid); 234 235 vldb = afs_vl_lookup_vldb(volume->cell, key, idbuf, idsz); 236 if (IS_ERR(vldb)) { 237 ret = PTR_ERR(vldb); 238 goto error; 239 } 240 241 /* See if the volume got renamed. */ 242 if (vldb->name_len != volume->name_len || 243 memcmp(vldb->name, volume->name, vldb->name_len) != 0) { 244 /* TODO: Use RCU'd string. */ 245 memcpy(volume->name, vldb->name, AFS_MAXVOLNAME); 246 volume->name_len = vldb->name_len; 247 } 248 249 /* See if the volume's server list got updated. */ 250 new = afs_alloc_server_list(volume->cell, key, 251 vldb, (1 << volume->type)); 252 if (IS_ERR(new)) { 253 ret = PTR_ERR(new); 254 goto error_vldb; 255 } 256 257 write_lock(&volume->servers_lock); 258 259 discard = new; 260 old = volume->servers; 261 if (afs_annotate_server_list(new, old)) { 262 new->seq = volume->servers_seq + 1; 263 volume->servers = new; 264 smp_wmb(); 265 volume->servers_seq++; 266 discard = old; 267 } 268 269 volume->update_at = ktime_get_real_seconds() + afs_volume_record_life; 270 clear_bit(AFS_VOLUME_NEEDS_UPDATE, &volume->flags); 271 write_unlock(&volume->servers_lock); 272 ret = 0; 273 274 afs_put_serverlist(volume->cell->net, discard); 275 error_vldb: 276 kfree(vldb); 277 error: 278 _leave(" = %d", ret); 279 return ret; 280 } 281 282 /* 283 * Make sure the volume record is up to date. 284 */ 285 int afs_check_volume_status(struct afs_volume *volume, struct key *key) 286 { 287 time64_t now = ktime_get_real_seconds(); 288 int ret, retries = 0; 289 290 _enter(""); 291 292 if (volume->update_at <= now) 293 set_bit(AFS_VOLUME_NEEDS_UPDATE, &volume->flags); 294 295 retry: 296 if (!test_bit(AFS_VOLUME_NEEDS_UPDATE, &volume->flags) && 297 !test_bit(AFS_VOLUME_WAIT, &volume->flags)) { 298 _leave(" = 0"); 299 return 0; 300 } 301 302 if (!test_and_set_bit_lock(AFS_VOLUME_UPDATING, &volume->flags)) { 303 ret = afs_update_volume_status(volume, key); 304 clear_bit_unlock(AFS_VOLUME_WAIT, &volume->flags); 305 clear_bit_unlock(AFS_VOLUME_UPDATING, &volume->flags); 306 wake_up_bit(&volume->flags, AFS_VOLUME_WAIT); 307 _leave(" = %d", ret); 308 return ret; 309 } 310 311 if (!test_bit(AFS_VOLUME_WAIT, &volume->flags)) { 312 _leave(" = 0 [no wait]"); 313 return 0; 314 } 315 316 ret = wait_on_bit(&volume->flags, AFS_VOLUME_WAIT, TASK_INTERRUPTIBLE); 317 if (ret == -ERESTARTSYS) { 318 _leave(" = %d", ret); 319 return ret; 320 } 321 322 retries++; 323 if (retries == 4) { 324 _leave(" = -ESTALE"); 325 return -ESTALE; 326 } 327 goto retry; 328 } 329