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_del(&zombie->link);
 127         list_add_tail(&zombie->link, &cell->sv_list);
 128         afs_get_server(zombie);
 129         afs_kafstimod_del_timer(&zombie->timeout);
 130         spin_unlock(&cell->sv_gylock);
 131         write_unlock(&cell->sv_lock);
 132
 133         kfree(server);
 134
 135         *_server = zombie;
 136         _leave(" = 0 (%p)", zombie);
 137         return 0;
 138
 139 } /* end afs_server_lookup() */
 140
 141 /*****************************************************************************/
 142 /*
 143  * destroy a server record
 144  * - removes from the cell list
 145  */
 146 void afs_put_server(struct afs_server *server)
 147 {
 148         struct afs_cell *cell;
 149
 150         if (!server)
 151                 return;
 152
 153         _enter("%p", server);
 154
 155         cell = server->cell;
 156
 157         /* sanity check */
 158         BUG_ON(atomic_read(&server->usage) <= 0);
 159
 160         /* to prevent a race, the decrement and the dequeue must be effectively
 161          * atomic */
 162         write_lock(&cell->sv_lock);
 163
 164         if (likely(!atomic_dec_and_test(&server->usage))) {
 165                 write_unlock(&cell->sv_lock);
 166                 _leave("");
 167                 return;
 168         }
 169
 170         spin_lock(&cell->sv_gylock);
 171         list_del(&server->link);
 172         list_add_tail(&server->link, &cell->sv_graveyard);
 173
 174         /* time out in 10 secs */
 175         afs_kafstimod_add_timer(&server->timeout, 10 * HZ);
 176
 177         spin_unlock(&cell->sv_gylock);
 178         write_unlock(&cell->sv_lock);
 179
 180         _leave(" [killed]");
 181 } /* end afs_put_server() */
 182
 183 /*****************************************************************************/
 184 /*
 185  * timeout server record
 186  * - removes from the cell's graveyard if the usage count is zero
 187  */
 188 void afs_server_do_timeout(struct afs_server *server)
 189 {
 190         struct rxrpc_peer *peer;
 191         struct afs_cell *cell;
 192         int loop;
 193
 194         _enter("%p", server);
 195
 196         cell = server->cell;
 197
 198         BUG_ON(atomic_read(&server->usage) < 0);
 199
 200         /* remove from graveyard if still dead */
 201         spin_lock(&cell->vl_gylock);
 202         if (atomic_read(&server->usage) == 0)
 203                 list_del_init(&server->link);
 204         else
 205                 server = NULL;
 206         spin_unlock(&cell->vl_gylock);
 207
 208         if (!server) {
 209                 _leave("");
 210                 return; /* resurrected */
 211         }
 212
 213         /* we can now destroy it properly */
 214         afs_put_cell(cell);
 215
 216         /* uncross-point the structs under a global lock */
 217         spin_lock(&afs_server_peer_lock);
 218         peer = server->peer;
 219         if (peer) {
 220                 server->peer = NULL;
 221                 peer->user = NULL;
 222         }
 223         spin_unlock(&afs_server_peer_lock);
 224
 225         /* finish cleaning up the server */
 226         for (loop = AFS_SERVER_CONN_LIST_SIZE - 1; loop >= 0; loop--)
 227                 if (server->fs_conn[loop])
 228                         rxrpc_put_connection(server->fs_conn[loop]);
 229
 230         if (server->vlserver)
 231                 rxrpc_put_connection(server->vlserver);
 232
 233         kfree(server);
 234
 235         _leave(" [destroyed]");
 236 } /* end afs_server_do_timeout() */
 237
 238 /*****************************************************************************/
 239 /*
 240  * get a callslot on a connection to the fileserver on the specified server
 241  */
 242 int afs_server_request_callslot(struct afs_server *server,
 243                                 struct afs_server_callslot *callslot)
 244 {
 245         struct afs_server_callslot *pcallslot;
 246         struct rxrpc_connection *conn;
 247         int nconn, ret;
 248
 249         _enter("%p,",server);
 250
 251         INIT_LIST_HEAD(&callslot->link);
 252         callslot->task = current;
 253         callslot->conn = NULL;
 254         callslot->nconn = -1;
 255         callslot->ready = 0;
 256
 257         ret = 0;
 258         conn = NULL;
 259
 260         /* get hold of a callslot first */
 261         spin_lock(&server->fs_lock);
 262
 263         /* resurrect the server if it's death timeout has expired */
 264         if (server->fs_state) {
 265                 if (time_before(jiffies, server->fs_dead_jif)) {
 266                         ret = server->fs_state;
 267                         spin_unlock(&server->fs_lock);
 268                         _leave(" = %d [still dead]", ret);
 269                         return ret;
 270                 }
 271
 272                 server->fs_state = 0;
 273         }
 274
 275         /* try and find a connection that has spare callslots */
 276         for (nconn = 0; nconn < AFS_SERVER_CONN_LIST_SIZE; nconn++) {
 277                 if (server->fs_conn_cnt[nconn] > 0) {
 278                         server->fs_conn_cnt[nconn]--;
 279                         spin_unlock(&server->fs_lock);
 280                         callslot->nconn = nconn;
 281                         goto obtained_slot;
 282                 }
 283         }
 284
 285         /* none were available - wait interruptibly for one to become
 286          * available */
 287         set_current_state(TASK_INTERRUPTIBLE);
 288         list_add_tail(&callslot->link, &server->fs_callq);
 289         spin_unlock(&server->fs_lock);
 290
 291         while (!callslot->ready && !signal_pending(current)) {
 292                 schedule();
 293                 set_current_state(TASK_INTERRUPTIBLE);
 294         }
 295
 296         set_current_state(TASK_RUNNING);
 297
 298         /* even if we were interrupted we may still be queued */
 299         if (!callslot->ready) {
 300                 spin_lock(&server->fs_lock);
 301                 list_del_init(&callslot->link);
 302                 spin_unlock(&server->fs_lock);
 303         }
 304
 305         nconn = callslot->nconn;
 306
 307         /* if interrupted, we must release any slot we also got before
 308          * returning an error */
 309         if (signal_pending(current)) {
 310                 ret = -EINTR;
 311                 goto error_release;
 312         }
 313
 314         /* if we were woken up with an error, then pass that error back to the
 315          * called */
 316         if (nconn < 0) {
 317                 _leave(" = %d", callslot->errno);
 318                 return callslot->errno;
 319         }
 320
 321         /* were we given a connection directly? */
 322         if (callslot->conn) {
 323                 /* yes - use it */
 324                 _leave(" = 0 (nc=%d)", nconn);
 325                 return 0;
 326         }
 327
 328         /* got a callslot, but no connection */
 329  obtained_slot:
 330
 331         /* need to get hold of the RxRPC connection */
 332         down_write(&server->sem);
 333
 334         /* quick check to see if there's an outstanding error */
 335         ret = server->fs_state;
 336         if (ret)
 337                 goto error_release_upw;
 338
 339         if (server->fs_conn[nconn]) {
 340                 /* reuse an existing connection */
 341                 rxrpc_get_connection(server->fs_conn[nconn]);
 342                 callslot->conn = server->fs_conn[nconn];
 343         }
 344         else {
 345                 /* create a new connection */
 346                 ret = rxrpc_create_connection(afs_transport,
 347                                               htons(7000),
 348                                               server->addr.s_addr,
 349                                               FS_SERVICE_ID,
 350                                               NULL,
 351                                               &server->fs_conn[nconn]);
 352
 353                 if (ret < 0)
 354                         goto error_release_upw;
 355
 356                 callslot->conn = server->fs_conn[0];
 357                 rxrpc_get_connection(callslot->conn);
 358         }
 359
 360         up_write(&server->sem);
 361
 362         _leave(" = 0");
 363         return 0;
 364
 365         /* handle an error occurring */
 366  error_release_upw:
 367         up_write(&server->sem);
 368
 369  error_release:
 370         /* either release the callslot or pass it along to another deserving
 371          * task */
 372         spin_lock(&server->fs_lock);
 373
 374         if (nconn < 0) {
 375                 /* no callslot allocated */
 376         }
 377         else if (list_empty(&server->fs_callq)) {
 378                 /* no one waiting */
 379                 server->fs_conn_cnt[nconn]++;
 380                 spin_unlock(&server->fs_lock);
 381         }
 382         else {
 383                 /* someone's waiting - dequeue them and wake them up */
 384                 pcallslot = list_entry(server->fs_callq.next,
 385                                        struct afs_server_callslot, link);
 386                 list_del_init(&pcallslot->link);
 387
 388                 pcallslot->errno = server->fs_state;
 389                 if (!pcallslot->errno) {
 390                         /* pass them out callslot details */
 391                         callslot->conn = xchg(&pcallslot->conn,
 392                                               callslot->conn);
 393                         pcallslot->nconn = nconn;
 394                         callslot->nconn = nconn = -1;
 395                 }
 396                 pcallslot->ready = 1;
 397                 wake_up_process(pcallslot->task);
 398                 spin_unlock(&server->fs_lock);
 399         }
 400
 401         rxrpc_put_connection(callslot->conn);
 402         callslot->conn = NULL;
 403
 404         _leave(" = %d", ret);
 405         return ret;
 406
 407 } /* end afs_server_request_callslot() */
 408
 409 /*****************************************************************************/
 410 /*
 411  * release a callslot back to the server
 412  * - transfers the RxRPC connection to the next pending callslot if possible
 413  */
 414 void afs_server_release_callslot(struct afs_server *server,
 415                                  struct afs_server_callslot *callslot)
 416 {
 417         struct afs_server_callslot *pcallslot;
 418
 419         _enter("{ad=%08x,cnt=%u},{%d}",
 420                ntohl(server->addr.s_addr),
 421                server->fs_conn_cnt[callslot->nconn],
 422                callslot->nconn);
 423
 424         BUG_ON(callslot->nconn < 0);
 425
 426         spin_lock(&server->fs_lock);
 427
 428         if (list_empty(&server->fs_callq)) {
 429                 /* no one waiting */
 430                 server->fs_conn_cnt[callslot->nconn]++;
 431                 spin_unlock(&server->fs_lock);
 432         }
 433         else {
 434                 /* someone's waiting - dequeue them and wake them up */
 435                 pcallslot = list_entry(server->fs_callq.next,
 436                                        struct afs_server_callslot, link);
 437                 list_del_init(&pcallslot->link);
 438
 439                 pcallslot->errno = server->fs_state;
 440                 if (!pcallslot->errno) {
 441                         /* pass them out callslot details */
 442                         callslot->conn = xchg(&pcallslot->conn, callslot->conn);
 443                         pcallslot->nconn = callslot->nconn;
 444                         callslot->nconn = -1;
 445                 }
 446
 447                 pcallslot->ready = 1;
 448                 wake_up_process(pcallslot->task);
 449                 spin_unlock(&server->fs_lock);
 450         }
 451
 452         rxrpc_put_connection(callslot->conn);
 453
 454         _leave("");
 455 } /* end afs_server_release_callslot() */
 456
 457 /*****************************************************************************/
 458 /*
 459  * get a handle to a connection to the vlserver (volume location) on the
 460  * specified server
 461  */
 462 int afs_server_get_vlconn(struct afs_server *server,
 463                           struct rxrpc_connection **_conn)
 464 {
 465         struct rxrpc_connection *conn;
 466         int ret;
 467
 468         _enter("%p,", server);
 469
 470         ret = 0;
 471         conn = NULL;
 472         down_read(&server->sem);
 473
 474         if (server->vlserver) {
 475                 /* reuse an existing connection */
 476                 rxrpc_get_connection(server->vlserver);
 477                 conn = server->vlserver;
 478                 up_read(&server->sem);
 479         }
 480         else {
 481                 /* create a new connection */
 482                 up_read(&server->sem);
 483                 down_write(&server->sem);
 484                 if (!server->vlserver) {
 485                         ret = rxrpc_create_connection(afs_transport,
 486                                                       htons(7003),
 487                                                       server->addr.s_addr,
 488                                                       VL_SERVICE_ID,
 489                                                       NULL,
 490                                                       &server->vlserver);
 491                 }
 492                 if (ret == 0) {
 493                         rxrpc_get_connection(server->vlserver);
 494                         conn = server->vlserver;
 495                 }
 496                 up_write(&server->sem);
 497         }
 498
 499         *_conn = conn;
 500         _leave(" = %d", ret);
 501         return ret;
 502 } /* end afs_server_get_vlconn() */