fs/afs/volume.c

   1 /* AFS volume management
   2  *
   3  * Copyright (C) 2002, 2007 Red Hat, Inc. All Rights Reserved.
   4  * Written by David Howells (dhowells@redhat.com)
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License
   8  * as published by the Free Software Foundation; either version
   9  * 2 of the License, or (at your option) any later version.
  10  */
  11
  12 #include <linux/kernel.h>
  13 #include <linux/slab.h>
  14 #include "internal.h"
  15
  16 unsigned __read_mostly afs_volume_gc_delay = 10;
  17 unsigned __read_mostly afs_volume_record_life = 60 * 60;
  18
  19 static const char *const afs_voltypes[] = { "R/W", "R/O", "BAK" };
  20
  21 /*
  22  * Allocate a volume record and load it up from a vldb record.
  23  */
  24 static struct afs_volume *afs_alloc_volume(struct afs_fs_context *params,
  25                                            struct afs_vldb_entry *vldb,
  26                                            unsigned long type_mask)
  27 {
  28         struct afs_server_list *slist;
  29         struct afs_volume *volume;
  30         int ret = -ENOMEM, nr_servers = 0, i;
  31
  32         for (i = 0; i < vldb->nr_servers; i++)
  33                 if (vldb->fs_mask[i] & type_mask)
  34                         nr_servers++;
  35
  36         volume = kzalloc(sizeof(struct afs_volume), GFP_KERNEL);
  37         if (!volume)
  38                 goto error_0;
  39
  40         volume->vid             = vldb->vid[params->type];
  41         volume->update_at       = ktime_get_real_seconds() + afs_volume_record_life;
  42         volume->cell            = afs_get_cell(params->cell);
  43         volume->type            = params->type;
  44         volume->type_force      = params->force;
  45         volume->name_len        = vldb->name_len;
  46
  47         atomic_set(&volume->usage, 1);
  48         INIT_LIST_HEAD(&volume->proc_link);
  49         rwlock_init(&volume->servers_lock);
  50         memcpy(volume->name, vldb->name, vldb->name_len + 1);
  51
  52         slist = afs_alloc_server_list(params->cell, params->key, vldb, type_mask);
  53         if (IS_ERR(slist)) {
  54                 ret = PTR_ERR(slist);
  55                 goto error_1;
  56         }
  57
  58         refcount_set(&slist->usage, 1);
  59         volume->servers = slist;
  60         return volume;
  61
  62 error_1:
  63         afs_put_cell(params->net, volume->cell);
  64         kfree(volume);
  65 error_0:
  66         return ERR_PTR(ret);
  67 }
  68
  69 /*
  70  * Look up a VLDB record for a volume.
  71  */
  72 static struct afs_vldb_entry *afs_vl_lookup_vldb(struct afs_cell *cell,
  73                                                  struct key *key,
  74                                                  const char *volname,
  75                                                  size_t volnamesz)
  76 {
  77         struct afs_vldb_entry *vldb = ERR_PTR(-EDESTADDRREQ);
  78         struct afs_vl_cursor vc;
  79         int ret;
  80
  81         if (!afs_begin_vlserver_operation(&vc, cell, key))
  82                 return ERR_PTR(-ERESTARTSYS);
  83
  84         while (afs_select_vlserver(&vc)) {
  85                 vldb = afs_vl_get_entry_by_name_u(&vc, volname, volnamesz);
  86         }
  87
  88         ret = afs_end_vlserver_operation(&vc);
  89         return ret < 0 ? ERR_PTR(ret) : vldb;
  90 }
  91
  92 /*
  93  * Look up a volume in the VL server and create a candidate volume record for
  94  * it.
  95  *
  96  * The volume name can be one of the following:
  97  *      "%[cell:]volume[.]"             R/W volume
  98  *      "#[cell:]volume[.]"             R/O or R/W volume (rwparent=0),
  99  *                                       or R/W (rwparent=1) volume
 100  *      "%[cell:]volume.readonly"       R/O volume
 101  *      "#[cell:]volume.readonly"       R/O volume
 102  *      "%[cell:]volume.backup"         Backup volume
 103  *      "#[cell:]volume.backup"         Backup volume
 104  *
 105  * The cell name is optional, and defaults to the current cell.
 106  *
 107  * See "The Rules of Mount Point Traversal" in Chapter 5 of the AFS SysAdmin
 108  * Guide
 109  * - Rule 1: Explicit type suffix forces access of that type or nothing
 110  *           (no suffix, then use Rule 2 & 3)
 111  * - Rule 2: If parent volume is R/O, then mount R/O volume by preference, R/W
 112  *           if not available
 113  * - Rule 3: If parent volume is R/W, then only mount R/W volume unless
 114  *           explicitly told otherwise
 115  */
 116 struct afs_volume *afs_create_volume(struct afs_fs_context *params)
 117 {
 118         struct afs_vldb_entry *vldb;
 119         struct afs_volume *volume;
 120         unsigned long type_mask = 1UL << params->type;
 121
 122         vldb = afs_vl_lookup_vldb(params->cell, params->key,
 123                                   params->volname, params->volnamesz);
 124         if (IS_ERR(vldb))
 125                 return ERR_CAST(vldb);
 126
 127         if (test_bit(AFS_VLDB_QUERY_ERROR, &vldb->flags)) {
 128                 volume = ERR_PTR(vldb->error);
 129                 goto error;
 130         }
 131
 132         /* Make the final decision on the type we want */
 133         volume = ERR_PTR(-ENOMEDIUM);
 134         if (params->force) {
 135                 if (!(vldb->flags & type_mask))
 136                         goto error;
 137         } else if (test_bit(AFS_VLDB_HAS_RO, &vldb->flags)) {
 138                 params->type = AFSVL_ROVOL;
 139         } else if (test_bit(AFS_VLDB_HAS_RW, &vldb->flags)) {
 140                 params->type = AFSVL_RWVOL;
 141         } else {
 142                 goto error;
 143         }
 144
 145         type_mask = 1UL << params->type;
 146         volume = afs_alloc_volume(params, vldb, type_mask);
 147
 148 error:
 149         kfree(vldb);
 150         return volume;
 151 }
 152
 153 /*
 154  * Destroy a volume record
 155  */
 156 static void afs_destroy_volume(struct afs_net *net, struct afs_volume *volume)
 157 {
 158         _enter("%p", volume);
 159
 160 #ifdef CONFIG_AFS_FSCACHE
 161         ASSERTCMP(volume->cache, ==, NULL);
 162 #endif
 163
 164         afs_put_serverlist(net, volume->servers);
 165         afs_put_cell(net, volume->cell);
 166         kfree(volume);
 167
 168         _leave(" [destroyed]");
 169 }
 170
 171 /*
 172  * Drop a reference on a volume record.
 173  */
 174 void afs_put_volume(struct afs_cell *cell, struct afs_volume *volume)
 175 {
 176         if (volume) {
 177                 _enter("%s", volume->name);
 178
 179                 if (atomic_dec_and_test(&volume->usage))
 180                         afs_destroy_volume(cell->net, volume);
 181         }
 182 }
 183
 184 /*
 185  * Activate a volume.
 186  */
 187 void afs_activate_volume(struct afs_volume *volume)
 188 {
 189 #ifdef CONFIG_AFS_FSCACHE
 190         volume->cache = fscache_acquire_cookie(volume->cell->cache,
 191                                                &afs_volume_cache_index_def,
 192                                                &volume->vid, sizeof(volume->vid),
 193                                                NULL, 0,
 194                                                volume, 0, true);
 195 #endif
 196
 197         write_lock(&volume->cell->proc_lock);
 198         list_add_tail(&volume->proc_link, &volume->cell->proc_volumes);
 199         write_unlock(&volume->cell->proc_lock);
 200 }
 201
 202 /*
 203  * Deactivate a volume.
 204  */
 205 void afs_deactivate_volume(struct afs_volume *volume)
 206 {
 207         _enter("%s", volume->name);
 208
 209         write_lock(&volume->cell->proc_lock);
 210         list_del_init(&volume->proc_link);
 211         write_unlock(&volume->cell->proc_lock);
 212
 213 #ifdef CONFIG_AFS_FSCACHE
 214         fscache_relinquish_cookie(volume->cache, NULL,
 215                                   test_bit(AFS_VOLUME_DELETED, &volume->flags));
 216         volume->cache = NULL;
 217 #endif
 218
 219         _leave("");
 220 }
 221
 222 /*
 223  * Query the VL service to update the volume status.
 224  */
 225 static int afs_update_volume_status(struct afs_volume *volume, struct key *key)
 226 {
 227         struct afs_server_list *new, *old, *discard;
 228         struct afs_vldb_entry *vldb;
 229         char idbuf[16];
 230         int ret, idsz;
 231
 232         _enter("");
 233
 234         /* We look up an ID by passing it as a decimal string in the
 235          * operation's name parameter.
 236          */
 237         idsz = sprintf(idbuf, "%llu", volume->vid);
 238
 239         vldb = afs_vl_lookup_vldb(volume->cell, key, idbuf, idsz);
 240         if (IS_ERR(vldb)) {
 241                 ret = PTR_ERR(vldb);
 242                 goto error;
 243         }
 244
 245         /* See if the volume got renamed. */
 246         if (vldb->name_len != volume->name_len ||
 247             memcmp(vldb->name, volume->name, vldb->name_len) != 0) {
 248                 /* TODO: Use RCU'd string. */
 249                 memcpy(volume->name, vldb->name, AFS_MAXVOLNAME);
 250                 volume->name_len = vldb->name_len;
 251         }
 252
 253         /* See if the volume's server list got updated. */
 254         new = afs_alloc_server_list(volume->cell, key,
 255                                     vldb, (1 << volume->type));
 256         if (IS_ERR(new)) {
 257                 ret = PTR_ERR(new);
 258                 goto error_vldb;
 259         }
 260
 261         write_lock(&volume->servers_lock);
 262
 263         discard = new;
 264         old = volume->servers;
 265         if (afs_annotate_server_list(new, old)) {
 266                 new->seq = volume->servers_seq + 1;
 267                 volume->servers = new;
 268                 smp_wmb();
 269                 volume->servers_seq++;
 270                 discard = old;
 271         }
 272
 273         volume->update_at = ktime_get_real_seconds() + afs_volume_record_life;
 274         clear_bit(AFS_VOLUME_NEEDS_UPDATE, &volume->flags);
 275         write_unlock(&volume->servers_lock);
 276         ret = 0;
 277
 278         afs_put_serverlist(volume->cell->net, discard);
 279 error_vldb:
 280         kfree(vldb);
 281 error:
 282         _leave(" = %d", ret);
 283         return ret;
 284 }
 285
 286 /*
 287  * Make sure the volume record is up to date.
 288  */
 289 int afs_check_volume_status(struct afs_volume *volume, struct key *key)
 290 {
 291         time64_t now = ktime_get_real_seconds();
 292         int ret, retries = 0;
 293
 294         _enter("");
 295
 296         if (volume->update_at <= now)
 297                 set_bit(AFS_VOLUME_NEEDS_UPDATE, &volume->flags);
 298
 299 retry:
 300         if (!test_bit(AFS_VOLUME_NEEDS_UPDATE, &volume->flags) &&
 301             !test_bit(AFS_VOLUME_WAIT, &volume->flags)) {
 302                 _leave(" = 0");
 303                 return 0;
 304         }
 305
 306         if (!test_and_set_bit_lock(AFS_VOLUME_UPDATING, &volume->flags)) {
 307                 ret = afs_update_volume_status(volume, key);
 308                 clear_bit_unlock(AFS_VOLUME_WAIT, &volume->flags);
 309                 clear_bit_unlock(AFS_VOLUME_UPDATING, &volume->flags);
 310                 wake_up_bit(&volume->flags, AFS_VOLUME_WAIT);
 311                 _leave(" = %d", ret);
 312                 return ret;
 313         }
 314
 315         if (!test_bit(AFS_VOLUME_WAIT, &volume->flags)) {
 316                 _leave(" = 0 [no wait]");
 317                 return 0;
 318         }
 319
 320         ret = wait_on_bit(&volume->flags, AFS_VOLUME_WAIT, TASK_INTERRUPTIBLE);
 321         if (ret == -ERESTARTSYS) {
 322                 _leave(" = %d", ret);
 323                 return ret;
 324         }
 325
 326         retries++;
 327         if (retries == 4) {
 328                 _leave(" = -ESTALE");
 329                 return -ESTALE;
 330         }
 331         goto retry;
 332 }