fs/afs/server.c

   1 /* server.c: AFS server record management
   2  *
   3  * Copyright (C) 2002 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/sched.h>
  13 #include <linux/slab.h>
  14 #include <rxrpc/peer.h>
  15 #include <rxrpc/connection.h>
  16 #include "volume.h"
  17 #include "cell.h"
  18 #include "server.h"
  19 #include "transport.h"
  20 #include "vlclient.h"
  21 #include "kafstimod.h"
  22 #include "internal.h"
  23
  24 DEFINE_SPINLOCK(afs_server_peer_lock);
  25
  26 #define FS_SERVICE_ID           1       /* AFS Volume Location Service ID */
  27 #define VL_SERVICE_ID           52      /* AFS Volume Location Service ID */
  28
  29 static void __afs_server_timeout(struct afs_timer *timer)
  30 {
  31         struct afs_server *server =
  32                 list_entry(timer, struct afs_server, timeout);
  33
  34         _debug("SERVER TIMEOUT [%p{u=%d}]",
  35                server, atomic_read(&server->usage));
  36
  37         afs_server_do_timeout(server);
  38 }
  39
  40 static const struct afs_timer_ops afs_server_timer_ops = {
  41         .timed_out      = __afs_server_timeout,
  42 };
  43
  44 /*****************************************************************************/
  45 /*
  46  * lookup a server record in a cell
  47  * - TODO: search the cell's server list
  48  */
  49 int afs_server_lookup(struct afs_cell *cell, const struct in_addr *addr,
  50                       struct afs_server **_server)
  51 {
  52         struct afs_server *server, *active, *zombie;
  53         int loop;
  54
  55         _enter("%p,%08x,", cell, ntohl(addr->s_addr));
  56
  57         /* allocate and initialise a server record */
  58         server = kmalloc(sizeof(struct afs_server), GFP_KERNEL);
  59         if (!server) {
  60                 _leave(" = -ENOMEM");
  61                 return -ENOMEM;
  62         }
  63
  64         memset(server, 0, sizeof(struct afs_server));
  65         atomic_set(&server->usage, 1);
  66
  67         INIT_LIST_HEAD(&server->link);
  68         init_rwsem(&server->sem);
  69         INIT_LIST_HEAD(&server->fs_callq);
  70         spin_lock_init(&server->fs_lock);
  71         INIT_LIST_HEAD(&server->cb_promises);
  72         spin_lock_init(&server->cb_lock);
  73
  74         for (loop = 0; loop < AFS_SERVER_CONN_LIST_SIZE; loop++)
  75                 server->fs_conn_cnt[loop] = 4;
  76
  77         memcpy(&server->addr, addr, sizeof(struct in_addr));
  78         server->addr.s_addr = addr->s_addr;
  79
  80         afs_timer_init(&server->timeout, &afs_server_timer_ops);
  81
  82         /* add to the cell */
  83         write_lock(&cell->sv_lock);
  84
  85         /* check the active list */
  86         list_for_each_entry(active, &cell->sv_list, link) {
  87                 if (active->addr.s_addr == addr->s_addr)
  88                         goto use_active_server;
  89         }
  90
  91         /* check the inactive list */
  92         spin_lock(&cell->sv_gylock);
  93         list_for_each_entry(zombie, &cell->sv_graveyard, link) {
  94                 if (zombie->addr.s_addr == addr->s_addr)
  95                         goto resurrect_server;
  96         }
  97         spin_unlock(&cell->sv_gylock);
  98
  99         afs_get_cell(cell);
 100         server->cell = cell;
 101         list_add_tail(&server->link, &cell->sv_list);
 102
 103         write_unlock(&cell->sv_lock);
 104
 105         *_server = server;
 106         _leave(" = 0 (%p)", server);
 107         return 0;
 108
 109         /* found a matching active server */
 110  use_active_server:
 111         _debug("active server");
 112         afs_get_server(active);
 113         write_unlock(&cell->sv_lock);
 114
 115         kfree(server);
 116
 117         *_server = active;
 118         _leave(" = 0 (%p)", active);
 119         return 0;
 120
 121         /* found a matching server in the graveyard, so resurrect it and
 122          * dispose of the new record */
 123  resurrect_server:
 124         _debug("resurrecting server");
 125
 126         list_move_tail(&zombie->link, &cell->sv_list);
 127         afs_get_server(zombie);
 128         afs_kafstimod_del_timer(&zombie->timeout);
 129         spin_unlock(&cell->sv_gylock);
 130         write_unlock(&cell->sv_lock);
 131
 132         kfree(server);
 133
 134         *_server = zombie;
 135         _leave(" = 0 (%p)", zombie);
 136         return 0;
 137
 138 } /* end afs_server_lookup() */
 139
 140 /*****************************************************************************/
 141 /*
 142  * destroy a server record
 143  * - removes from the cell list
 144  */
 145 void afs_put_server(struct afs_server *server)
 146 {
 147         struct afs_cell *cell;
 148
 149         if (!server)
 150                 return;
 151
 152         _enter("%p", server);
 153
 154         cell = server->cell;
 155
 156         /* sanity check */
 157         BUG_ON(atomic_read(&server->usage) <= 0);
 158
 159         /* to prevent a race, the decrement and the dequeue must be effectively
 160          * atomic */
 161         write_lock(&cell->sv_lock);
 162
 163         if (likely(!atomic_dec_and_test(&server->usage))) {
 164                 write_unlock(&cell->sv_lock);
 165                 _leave("");
 166                 return;
 167         }
 168
 169         spin_lock(&cell->sv_gylock);
 170         list_move_tail(&server->link, &cell->sv_graveyard);
 171
 172         /* time out in 10 secs */
 173         afs_kafstimod_add_timer(&server->timeout, 10 * HZ);
 174
 175         spin_unlock(&cell->sv_gylock);
 176         write_unlock(&cell->sv_lock);
 177
 178         _leave(" [killed]");
 179 } /* end afs_put_server() */
 180
 181 /*****************************************************************************/
 182 /*
 183  * timeout server record
 184  * - removes from the cell's graveyard if the usage count is zero
 185  */
 186 void afs_server_do_timeout(struct afs_server *server)
 187 {
 188         struct rxrpc_peer *peer;
 189         struct afs_cell *cell;
 190         int loop;
 191
 192         _enter("%p", server);
 193
 194         cell = server->cell;
 195
 196         BUG_ON(atomic_read(&server->usage) < 0);
 197
 198         /* remove from graveyard if still dead */
 199         spin_lock(&cell->vl_gylock);
 200         if (atomic_read(&server->usage) == 0)
 201                 list_del_init(&server->link);
 202         else
 203                 server = NULL;
 204         spin_unlock(&cell->vl_gylock);
 205
 206         if (!server) {
 207                 _leave("");
 208                 return; /* resurrected */
 209         }
 210
 211         /* we can now destroy it properly */
 212         afs_put_cell(cell);
 213
 214         /* uncross-point the structs under a global lock */
 215         spin_lock(&afs_server_peer_lock);
 216         peer = server->peer;
 217         if (peer) {
 218                 server->peer = NULL;
 219                 peer->user = NULL;
 220         }
 221         spin_unlock(&afs_server_peer_lock);
 222
 223         /* finish cleaning up the server */
 224         for (loop = AFS_SERVER_CONN_LIST_SIZE - 1; loop >= 0; loop--)
 225                 if (server->fs_conn[loop])
 226                         rxrpc_put_connection(server->fs_conn[loop]);
 227
 228         if (server->vlserver)
 229                 rxrpc_put_connection(server->vlserver);
 230
 231         kfree(server);
 232
 233         _leave(" [destroyed]");
 234 } /* end afs_server_do_timeout() */
 235
 236 /*****************************************************************************/
 237 /*
 238  * get a callslot on a connection to the fileserver on the specified server
 239  */
 240 int afs_server_request_callslot(struct afs_server *server,
 241                                 struct afs_server_callslot *callslot)
 242 {
 243         struct afs_server_callslot *pcallslot;
 244         struct rxrpc_connection *conn;
 245         int nconn, ret;
 246
 247         _enter("%p,",server);
 248
 249         INIT_LIST_HEAD(&callslot->link);
 250         callslot->task = current;
 251         callslot->conn = NULL;
 252         callslot->nconn = -1;
 253         callslot->ready = 0;
 254
 255         ret = 0;
 256         conn = NULL;
 257
 258         /* get hold of a callslot first */
 259         spin_lock(&server->fs_lock);
 260
 261         /* resurrect the server if it's death timeout has expired */
 262         if (server->fs_state) {
 263                 if (time_before(jiffies, server->fs_dead_jif)) {
 264                         ret = server->fs_state;
 265                         spin_unlock(&server->fs_lock);
 266                         _leave(" = %d [still dead]", ret);
 267                         return ret;
 268                 }
 269
 270                 server->fs_state = 0;
 271         }
 272
 273         /* try and find a connection that has spare callslots */
 274         for (nconn = 0; nconn < AFS_SERVER_CONN_LIST_SIZE; nconn++) {
 275                 if (server->fs_conn_cnt[nconn] > 0) {
 276                         server->fs_conn_cnt[nconn]--;
 277                         spin_unlock(&server->fs_lock);
 278                         callslot->nconn = nconn;
 279                         goto obtained_slot;
 280                 }
 281         }
 282
 283         /* none were available - wait interruptibly for one to become
 284          * available */
 285         set_current_state(TASK_INTERRUPTIBLE);
 286         list_add_tail(&callslot->link, &server->fs_callq);
 287         spin_unlock(&server->fs_lock);
 288
 289         while (!callslot->ready && !signal_pending(current)) {
 290                 schedule();
 291                 set_current_state(TASK_INTERRUPTIBLE);
 292         }
 293
 294         set_current_state(TASK_RUNNING);
 295
 296         /* even if we were interrupted we may still be queued */
 297         if (!callslot->ready) {
 298                 spin_lock(&server->fs_lock);
 299                 list_del_init(&callslot->link);
 300                 spin_unlock(&server->fs_lock);
 301         }
 302
 303         nconn = callslot->nconn;
 304
 305         /* if interrupted, we must release any slot we also got before
 306          * returning an error */
 307         if (signal_pending(current)) {
 308                 ret = -EINTR;
 309                 goto error_release;
 310         }
 311
 312         /* if we were woken up with an error, then pass that error back to the
 313          * called */
 314         if (nconn < 0) {
 315                 _leave(" = %d", callslot->errno);
 316                 return callslot->errno;
 317         }
 318
 319         /* were we given a connection directly? */
 320         if (callslot->conn) {
 321                 /* yes - use it */
 322                 _leave(" = 0 (nc=%d)", nconn);
 323                 return 0;
 324         }
 325
 326         /* got a callslot, but no connection */
 327  obtained_slot:
 328
 329         /* need to get hold of the RxRPC connection */
 330         down_write(&server->sem);
 331
 332         /* quick check to see if there's an outstanding error */
 333         ret = server->fs_state;
 334         if (ret)
 335                 goto error_release_upw;
 336
 337         if (server->fs_conn[nconn]) {
 338                 /* reuse an existing connection */
 339                 rxrpc_get_connection(server->fs_conn[nconn]);
 340                 callslot->conn = server->fs_conn[nconn];
 341         }
 342         else {
 343                 /* create a new connection */
 344                 ret = rxrpc_create_connection(afs_transport,
 345                                               htons(7000),
 346                                               server->addr.s_addr,
 347                                               FS_SERVICE_ID,
 348                                               NULL,
 349                                               &server->fs_conn[nconn]);
 350
 351                 if (ret < 0)
 352                         goto error_release_upw;
 353
 354                 callslot->conn = server->fs_conn[0];
 355                 rxrpc_get_connection(callslot->conn);
 356         }
 357
 358         up_write(&server->sem);
 359
 360         _leave(" = 0");
 361         return 0;
 362
 363         /* handle an error occurring */
 364  error_release_upw:
 365         up_write(&server->sem);
 366
 367  error_release:
 368         /* either release the callslot or pass it along to another deserving
 369          * task */
 370         spin_lock(&server->fs_lock);
 371
 372         if (nconn < 0) {
 373                 /* no callslot allocated */
 374         }
 375         else if (list_empty(&server->fs_callq)) {
 376                 /* no one waiting */
 377                 server->fs_conn_cnt[nconn]++;
 378                 spin_unlock(&server->fs_lock);
 379         }
 380         else {
 381                 /* someone's waiting - dequeue them and wake them up */
 382                 pcallslot = list_entry(server->fs_callq.next,
 383                                        struct afs_server_callslot, link);
 384                 list_del_init(&pcallslot->link);
 385
 386                 pcallslot->errno = server->fs_state;
 387                 if (!pcallslot->errno) {
 388                         /* pass them out callslot details */
 389                         callslot->conn = xchg(&pcallslot->conn,
 390                                               callslot->conn);
 391                         pcallslot->nconn = nconn;
 392                         callslot->nconn = nconn = -1;
 393                 }
 394                 pcallslot->ready = 1;
 395                 wake_up_process(pcallslot->task);
 396                 spin_unlock(&server->fs_lock);
 397         }
 398
 399         rxrpc_put_connection(callslot->conn);
 400         callslot->conn = NULL;
 401
 402         _leave(" = %d", ret);
 403         return ret;
 404
 405 } /* end afs_server_request_callslot() */
 406
 407 /*****************************************************************************/
 408 /*
 409  * release a callslot back to the server
 410  * - transfers the RxRPC connection to the next pending callslot if possible
 411  */
 412 void afs_server_release_callslot(struct afs_server *server,
 413                                  struct afs_server_callslot *callslot)
 414 {
 415         struct afs_server_callslot *pcallslot;
 416
 417         _enter("{ad=%08x,cnt=%u},{%d}",
 418                ntohl(server->addr.s_addr),
 419                server->fs_conn_cnt[callslot->nconn],
 420                callslot->nconn);
 421
 422         BUG_ON(callslot->nconn < 0);
 423
 424         spin_lock(&server->fs_lock);
 425
 426         if (list_empty(&server->fs_callq)) {
 427                 /* no one waiting */
 428                 server->fs_conn_cnt[callslot->nconn]++;
 429                 spin_unlock(&server->fs_lock);
 430         }
 431         else {
 432                 /* someone's waiting - dequeue them and wake them up */
 433                 pcallslot = list_entry(server->fs_callq.next,
 434                                        struct afs_server_callslot, link);
 435                 list_del_init(&pcallslot->link);
 436
 437                 pcallslot->errno = server->fs_state;
 438                 if (!pcallslot->errno) {
 439                         /* pass them out callslot details */
 440                         callslot->conn = xchg(&pcallslot->conn, callslot->conn);
 441                         pcallslot->nconn = callslot->nconn;
 442                         callslot->nconn = -1;
 443                 }
 444
 445                 pcallslot->ready = 1;
 446                 wake_up_process(pcallslot->task);
 447                 spin_unlock(&server->fs_lock);
 448         }
 449
 450         rxrpc_put_connection(callslot->conn);
 451
 452         _leave("");
 453 } /* end afs_server_release_callslot() */
 454
 455 /*****************************************************************************/
 456 /*
 457  * get a handle to a connection to the vlserver (volume location) on the
 458  * specified server
 459  */
 460 int afs_server_get_vlconn(struct afs_server *server,
 461                           struct rxrpc_connection **_conn)
 462 {
 463         struct rxrpc_connection *conn;
 464         int ret;
 465
 466         _enter("%p,", server);
 467
 468         ret = 0;
 469         conn = NULL;
 470         down_read(&server->sem);
 471
 472         if (server->vlserver) {
 473                 /* reuse an existing connection */
 474                 rxrpc_get_connection(server->vlserver);
 475                 conn = server->vlserver;
 476                 up_read(&server->sem);
 477         }
 478         else {
 479                 /* create a new connection */
 480                 up_read(&server->sem);
 481                 down_write(&server->sem);
 482                 if (!server->vlserver) {
 483                         ret = rxrpc_create_connection(afs_transport,
 484                                                       htons(7003),
 485                                                       server->addr.s_addr,
 486                                                       VL_SERVICE_ID,
 487                                                       NULL,
 488                                                       &server->vlserver);
 489                 }
 490                 if (ret == 0) {
 491                         rxrpc_get_connection(server->vlserver);
 492                         conn = server->vlserver;
 493                 }
 494                 up_write(&server->sem);
 495         }
 496
 497         *_conn = conn;
 498         _leave(" = %d", ret);
 499         return ret;
 500 } /* end afs_server_get_vlconn() */