fs/nfs/delegation.c

   1 /*
   2  * linux/fs/nfs/delegation.c
   3  *
   4  * Copyright (C) 2004 Trond Myklebust
   5  *
   6  * NFS file delegation management
   7  *
   8  */
   9 #include <linux/completion.h>
  10 #include <linux/kthread.h>
  11 #include <linux/module.h>
  12 #include <linux/sched.h>
  13 #include <linux/slab.h>
  14 #include <linux/spinlock.h>
  15
  16 #include <linux/nfs4.h>
  17 #include <linux/nfs_fs.h>
  18 #include <linux/nfs_xdr.h>
  19
  20 #include "nfs4_fs.h"
  21 #include "delegation.h"
  22 #include "internal.h"
  23
  24 static void nfs_free_delegation(struct nfs_delegation *delegation)
  25 {
  26         if (delegation->cred) {
  27                 put_rpccred(delegation->cred);
  28                 delegation->cred = NULL;
  29         }
  30         kfree_rcu(delegation, rcu);
  31 }
  32
  33 /**
  34  * nfs_mark_delegation_referenced - set delegation's REFERENCED flag
  35  * @delegation: delegation to process
  36  *
  37  */
  38 void nfs_mark_delegation_referenced(struct nfs_delegation *delegation)
  39 {
  40         set_bit(NFS_DELEGATION_REFERENCED, &delegation->flags);
  41 }
  42
  43 /**
  44  * nfs_have_delegation - check if inode has a delegation
  45  * @inode: inode to check
  46  * @flags: delegation types to check for
  47  *
  48  * Returns one if inode has the indicated delegation, otherwise zero.
  49  */
  50 int nfs_have_delegation(struct inode *inode, fmode_t flags)
  51 {
  52         struct nfs_delegation *delegation;
  53         int ret = 0;
  54
  55         flags &= FMODE_READ|FMODE_WRITE;
  56         rcu_read_lock();
  57         delegation = rcu_dereference(NFS_I(inode)->delegation);
  58         if (delegation != NULL && (delegation->type & flags) == flags) {
  59                 nfs_mark_delegation_referenced(delegation);
  60                 ret = 1;
  61         }
  62         rcu_read_unlock();
  63         return ret;
  64 }
  65
  66 static int nfs_delegation_claim_locks(struct nfs_open_context *ctx, struct nfs4_state *state)
  67 {
  68         struct inode *inode = state->inode;
  69         struct file_lock *fl;
  70         int status = 0;
  71
  72         if (inode->i_flock == NULL)
  73                 goto out;
  74
  75         /* Protect inode->i_flock using the file locks lock */
  76         lock_flocks();
  77         for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) {
  78                 if (!(fl->fl_flags & (FL_POSIX|FL_FLOCK)))
  79                         continue;
  80                 if (nfs_file_open_context(fl->fl_file) != ctx)
  81                         continue;
  82                 unlock_flocks();
  83                 status = nfs4_lock_delegation_recall(state, fl);
  84                 if (status < 0)
  85                         goto out;
  86                 lock_flocks();
  87         }
  88         unlock_flocks();
  89 out:
  90         return status;
  91 }
  92
  93 static int nfs_delegation_claim_opens(struct inode *inode, const nfs4_stateid *stateid)
  94 {
  95         struct nfs_inode *nfsi = NFS_I(inode);
  96         struct nfs_open_context *ctx;
  97         struct nfs4_state *state;
  98         int err;
  99
 100 again:
 101         spin_lock(&inode->i_lock);
 102         list_for_each_entry(ctx, &nfsi->open_files, list) {
 103                 state = ctx->state;
 104                 if (state == NULL)
 105                         continue;
 106                 if (!test_bit(NFS_DELEGATED_STATE, &state->flags))
 107                         continue;
 108                 if (memcmp(state->stateid.data, stateid->data, sizeof(state->stateid.data)) != 0)
 109                         continue;
 110                 get_nfs_open_context(ctx);
 111                 spin_unlock(&inode->i_lock);
 112                 err = nfs4_open_delegation_recall(ctx, state, stateid);
 113                 if (err >= 0)
 114                         err = nfs_delegation_claim_locks(ctx, state);
 115                 put_nfs_open_context(ctx);
 116                 if (err != 0)
 117                         return err;
 118                 goto again;
 119         }
 120         spin_unlock(&inode->i_lock);
 121         return 0;
 122 }
 123
 124 /**
 125  * nfs_inode_reclaim_delegation - process a delegation reclaim request
 126  * @inode: inode to process
 127  * @cred: credential to use for request
 128  * @res: new delegation state from server
 129  *
 130  */
 131 void nfs_inode_reclaim_delegation(struct inode *inode, struct rpc_cred *cred,
 132                                   struct nfs_openres *res)
 133 {
 134         struct nfs_delegation *delegation;
 135         struct rpc_cred *oldcred = NULL;
 136
 137         rcu_read_lock();
 138         delegation = rcu_dereference(NFS_I(inode)->delegation);
 139         if (delegation != NULL) {
 140                 spin_lock(&delegation->lock);
 141                 if (delegation->inode != NULL) {
 142                         memcpy(delegation->stateid.data, res->delegation.data,
 143                                sizeof(delegation->stateid.data));
 144                         delegation->type = res->delegation_type;
 145                         delegation->maxsize = res->maxsize;
 146                         oldcred = delegation->cred;
 147                         delegation->cred = get_rpccred(cred);
 148                         clear_bit(NFS_DELEGATION_NEED_RECLAIM,
 149                                   &delegation->flags);
 150                         NFS_I(inode)->delegation_state = delegation->type;
 151                         spin_unlock(&delegation->lock);
 152                         put_rpccred(oldcred);
 153                         rcu_read_unlock();
 154                 } else {
 155                         /* We appear to have raced with a delegation return. */
 156                         spin_unlock(&delegation->lock);
 157                         rcu_read_unlock();
 158                         nfs_inode_set_delegation(inode, cred, res);
 159                 }
 160         } else {
 161                 rcu_read_unlock();
 162         }
 163 }
 164
 165 static int nfs_do_return_delegation(struct inode *inode, struct nfs_delegation *delegation, int issync)
 166 {
 167         int res = 0;
 168
 169         res = nfs4_proc_delegreturn(inode, delegation->cred, &delegation->stateid, issync);
 170         nfs_free_delegation(delegation);
 171         return res;
 172 }
 173
 174 static struct inode *nfs_delegation_grab_inode(struct nfs_delegation *delegation)
 175 {
 176         struct inode *inode = NULL;
 177
 178         spin_lock(&delegation->lock);
 179         if (delegation->inode != NULL)
 180                 inode = igrab(delegation->inode);
 181         spin_unlock(&delegation->lock);
 182         return inode;
 183 }
 184
 185 static struct nfs_delegation *
 186 nfs_detach_delegation_locked(struct nfs_inode *nfsi,
 187                              struct nfs_server *server)
 188 {
 189         struct nfs_delegation *delegation =
 190                 rcu_dereference_protected(nfsi->delegation,
 191                                 lockdep_is_held(&server->nfs_client->cl_lock));
 192
 193         if (delegation == NULL)
 194                 goto nomatch;
 195
 196         spin_lock(&delegation->lock);
 197         list_del_rcu(&delegation->super_list);
 198         delegation->inode = NULL;
 199         nfsi->delegation_state = 0;
 200         rcu_assign_pointer(nfsi->delegation, NULL);
 201         spin_unlock(&delegation->lock);
 202         return delegation;
 203 nomatch:
 204         return NULL;
 205 }
 206
 207 static struct nfs_delegation *nfs_detach_delegation(struct nfs_inode *nfsi,
 208                                                     struct nfs_server *server)
 209 {
 210         struct nfs_client *clp = server->nfs_client;
 211         struct nfs_delegation *delegation;
 212
 213         spin_lock(&clp->cl_lock);
 214         delegation = nfs_detach_delegation_locked(nfsi, server);
 215         spin_unlock(&clp->cl_lock);
 216         return delegation;
 217 }
 218
 219 /**
 220  * nfs_inode_set_delegation - set up a delegation on an inode
 221  * @inode: inode to which delegation applies
 222  * @cred: cred to use for subsequent delegation processing
 223  * @res: new delegation state from server
 224  *
 225  * Returns zero on success, or a negative errno value.
 226  */
 227 int nfs_inode_set_delegation(struct inode *inode, struct rpc_cred *cred, struct nfs_openres *res)
 228 {
 229         struct nfs_server *server = NFS_SERVER(inode);
 230         struct nfs_client *clp = server->nfs_client;
 231         struct nfs_inode *nfsi = NFS_I(inode);
 232         struct nfs_delegation *delegation, *old_delegation;
 233         struct nfs_delegation *freeme = NULL;
 234         int status = 0;
 235
 236         delegation = kmalloc(sizeof(*delegation), GFP_NOFS);
 237         if (delegation == NULL)
 238                 return -ENOMEM;
 239         memcpy(delegation->stateid.data, res->delegation.data,
 240                         sizeof(delegation->stateid.data));
 241         delegation->type = res->delegation_type;
 242         delegation->maxsize = res->maxsize;
 243         delegation->change_attr = inode->i_version;
 244         delegation->cred = get_rpccred(cred);
 245         delegation->inode = inode;
 246         delegation->flags = 1<<NFS_DELEGATION_REFERENCED;
 247         spin_lock_init(&delegation->lock);
 248
 249         spin_lock(&clp->cl_lock);
 250         old_delegation = rcu_dereference_protected(nfsi->delegation,
 251                                         lockdep_is_held(&clp->cl_lock));
 252         if (old_delegation != NULL) {
 253                 if (memcmp(&delegation->stateid, &old_delegation->stateid,
 254                                         sizeof(old_delegation->stateid)) == 0 &&
 255                                 delegation->type == old_delegation->type) {
 256                         goto out;
 257                 }
 258                 /*
 259                  * Deal with broken servers that hand out two
 260                  * delegations for the same file.
 261                  */
 262                 dfprintk(FILE, "%s: server %s handed out "
 263                                 "a duplicate delegation!\n",
 264                                 __func__, clp->cl_hostname);
 265                 if (delegation->type <= old_delegation->type) {
 266                         freeme = delegation;
 267                         delegation = NULL;
 268                         goto out;
 269                 }
 270                 freeme = nfs_detach_delegation_locked(nfsi, server);
 271         }
 272         list_add_rcu(&delegation->super_list, &server->delegations);
 273         nfsi->delegation_state = delegation->type;
 274         rcu_assign_pointer(nfsi->delegation, delegation);
 275         delegation = NULL;
 276
 277         /* Ensure we revalidate the attributes and page cache! */
 278         spin_lock(&inode->i_lock);
 279         nfsi->cache_validity |= NFS_INO_REVAL_FORCED;
 280         spin_unlock(&inode->i_lock);
 281
 282 out:
 283         spin_unlock(&clp->cl_lock);
 284         if (delegation != NULL)
 285                 nfs_free_delegation(delegation);
 286         if (freeme != NULL)
 287                 nfs_do_return_delegation(inode, freeme, 0);
 288         return status;
 289 }
 290
 291 /*
 292  * Basic procedure for returning a delegation to the server
 293  */
 294 static int __nfs_inode_return_delegation(struct inode *inode, struct nfs_delegation *delegation, int issync)
 295 {
 296         struct nfs_inode *nfsi = NFS_I(inode);
 297         int err;
 298
 299         /*
 300          * Guard against new delegated open/lock/unlock calls and against
 301          * state recovery
 302          */
 303         down_write(&nfsi->rwsem);
 304         err = nfs_delegation_claim_opens(inode, &delegation->stateid);
 305         up_write(&nfsi->rwsem);
 306         if (err)
 307                 goto out;
 308
 309         err = nfs_do_return_delegation(inode, delegation, issync);
 310 out:
 311         return err;
 312 }
 313
 314 /**
 315  * nfs_client_return_marked_delegations - return previously marked delegations
 316  * @clp: nfs_client to process
 317  *
 318  * Returns zero on success, or a negative errno value.
 319  */
 320 int nfs_client_return_marked_delegations(struct nfs_client *clp)
 321 {
 322         struct nfs_delegation *delegation;
 323         struct nfs_server *server;
 324         struct inode *inode;
 325         int err = 0;
 326
 327 restart:
 328         rcu_read_lock();
 329         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link) {
 330                 list_for_each_entry_rcu(delegation, &server->delegations,
 331                                                                 super_list) {
 332                         if (!test_and_clear_bit(NFS_DELEGATION_RETURN,
 333                                                         &delegation->flags))
 334                                 continue;
 335                         inode = nfs_delegation_grab_inode(delegation);
 336                         if (inode == NULL)
 337                                 continue;
 338                         delegation = nfs_detach_delegation(NFS_I(inode),
 339                                                                 server);
 340                         rcu_read_unlock();
 341
 342                         if (delegation != NULL) {
 343                                 filemap_flush(inode->i_mapping);
 344                                 err = __nfs_inode_return_delegation(inode,
 345                                                                 delegation, 0);
 346                         }
 347                         iput(inode);
 348                         if (!err)
 349                                 goto restart;
 350                         set_bit(NFS4CLNT_DELEGRETURN, &clp->cl_state);
 351                         return err;
 352                 }
 353         }
 354         rcu_read_unlock();
 355         return 0;
 356 }
 357
 358 /**
 359  * nfs_inode_return_delegation_noreclaim - return delegation, don't reclaim opens
 360  * @inode: inode to process
 361  *
 362  * Does not protect against delegation reclaims, therefore really only safe
 363  * to be called from nfs4_clear_inode().
 364  */
 365 void nfs_inode_return_delegation_noreclaim(struct inode *inode)
 366 {
 367         struct nfs_server *server = NFS_SERVER(inode);
 368         struct nfs_inode *nfsi = NFS_I(inode);
 369         struct nfs_delegation *delegation;
 370
 371         if (rcu_access_pointer(nfsi->delegation) != NULL) {
 372                 delegation = nfs_detach_delegation(nfsi, server);
 373                 if (delegation != NULL)
 374                         nfs_do_return_delegation(inode, delegation, 0);
 375         }
 376 }
 377
 378 /**
 379  * nfs_inode_return_delegation - synchronously return a delegation
 380  * @inode: inode to process
 381  *
 382  * Returns zero on success, or a negative errno value.
 383  */
 384 int nfs_inode_return_delegation(struct inode *inode)
 385 {
 386         struct nfs_server *server = NFS_SERVER(inode);
 387         struct nfs_inode *nfsi = NFS_I(inode);
 388         struct nfs_delegation *delegation;
 389         int err = 0;
 390
 391         if (rcu_access_pointer(nfsi->delegation) != NULL) {
 392                 delegation = nfs_detach_delegation(nfsi, server);
 393                 if (delegation != NULL) {
 394                         nfs_wb_all(inode);
 395                         err = __nfs_inode_return_delegation(inode, delegation, 1);
 396                 }
 397         }
 398         return err;
 399 }
 400
 401 static void nfs_mark_return_delegation(struct nfs_server *server,
 402                 struct nfs_delegation *delegation)
 403 {
 404         set_bit(NFS_DELEGATION_RETURN, &delegation->flags);
 405         set_bit(NFS4CLNT_DELEGRETURN, &server->nfs_client->cl_state);
 406 }
 407
 408 /**
 409  * nfs_super_return_all_delegations - return delegations for one superblock
 410  * @sb: sb to process
 411  *
 412  */
 413 void nfs_super_return_all_delegations(struct super_block *sb)
 414 {
 415         struct nfs_server *server = NFS_SB(sb);
 416         struct nfs_client *clp = server->nfs_client;
 417         struct nfs_delegation *delegation;
 418
 419         if (clp == NULL)
 420                 return;
 421
 422         rcu_read_lock();
 423         list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
 424                 spin_lock(&delegation->lock);
 425                 set_bit(NFS_DELEGATION_RETURN, &delegation->flags);
 426                 spin_unlock(&delegation->lock);
 427         }
 428         rcu_read_unlock();
 429
 430         if (nfs_client_return_marked_delegations(clp) != 0)
 431                 nfs4_schedule_state_manager(clp);
 432 }
 433
 434 static void nfs_mark_return_all_delegation_types(struct nfs_server *server,
 435                                                  fmode_t flags)
 436 {
 437         struct nfs_delegation *delegation;
 438
 439         list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
 440                 if ((delegation->type == (FMODE_READ|FMODE_WRITE)) && !(flags & FMODE_WRITE))
 441                         continue;
 442                 if (delegation->type & flags)
 443                         nfs_mark_return_delegation(server, delegation);
 444         }
 445 }
 446
 447 static void nfs_client_mark_return_all_delegation_types(struct nfs_client *clp,
 448                                                         fmode_t flags)
 449 {
 450         struct nfs_server *server;
 451
 452         rcu_read_lock();
 453         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
 454                 nfs_mark_return_all_delegation_types(server, flags);
 455         rcu_read_unlock();
 456 }
 457
 458 static void nfs_client_mark_return_all_delegations(struct nfs_client *clp)
 459 {
 460         nfs_client_mark_return_all_delegation_types(clp, FMODE_READ|FMODE_WRITE);
 461 }
 462
 463 static void nfs_delegation_run_state_manager(struct nfs_client *clp)
 464 {
 465         if (test_bit(NFS4CLNT_DELEGRETURN, &clp->cl_state))
 466                 nfs4_schedule_state_manager(clp);
 467 }
 468
 469 /**
 470  * nfs_expire_all_delegation_types
 471  * @clp: client to process
 472  * @flags: delegation types to expire
 473  *
 474  */
 475 void nfs_expire_all_delegation_types(struct nfs_client *clp, fmode_t flags)
 476 {
 477         nfs_client_mark_return_all_delegation_types(clp, flags);
 478         nfs_delegation_run_state_manager(clp);
 479 }
 480
 481 /**
 482  * nfs_expire_all_delegations
 483  * @clp: client to process
 484  *
 485  */
 486 void nfs_expire_all_delegations(struct nfs_client *clp)
 487 {
 488         nfs_expire_all_delegation_types(clp, FMODE_READ|FMODE_WRITE);
 489 }
 490
 491 /**
 492  * nfs_handle_cb_pathdown - return all delegations after NFS4ERR_CB_PATH_DOWN
 493  * @clp: client to process
 494  *
 495  */
 496 void nfs_handle_cb_pathdown(struct nfs_client *clp)
 497 {
 498         if (clp == NULL)
 499                 return;
 500         nfs_client_mark_return_all_delegations(clp);
 501 }
 502
 503 static void nfs_mark_return_unreferenced_delegations(struct nfs_server *server)
 504 {
 505         struct nfs_delegation *delegation;
 506
 507         list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
 508                 if (test_and_clear_bit(NFS_DELEGATION_REFERENCED, &delegation->flags))
 509                         continue;
 510                 nfs_mark_return_delegation(server, delegation);
 511         }
 512 }
 513
 514 /**
 515  * nfs_expire_unreferenced_delegations - Eliminate unused delegations
 516  * @clp: nfs_client to process
 517  *
 518  */
 519 void nfs_expire_unreferenced_delegations(struct nfs_client *clp)
 520 {
 521         struct nfs_server *server;
 522
 523         rcu_read_lock();
 524         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
 525                 nfs_mark_return_unreferenced_delegations(server);
 526         rcu_read_unlock();
 527
 528         nfs_delegation_run_state_manager(clp);
 529 }
 530
 531 /**
 532  * nfs_async_inode_return_delegation - asynchronously return a delegation
 533  * @inode: inode to process
 534  * @stateid: state ID information from CB_RECALL arguments
 535  *
 536  * Returns zero on success, or a negative errno value.
 537  */
 538 int nfs_async_inode_return_delegation(struct inode *inode,
 539                                       const nfs4_stateid *stateid)
 540 {
 541         struct nfs_server *server = NFS_SERVER(inode);
 542         struct nfs_client *clp = server->nfs_client;
 543         struct nfs_delegation *delegation;
 544
 545         rcu_read_lock();
 546         delegation = rcu_dereference(NFS_I(inode)->delegation);
 547
 548         if (!clp->cl_mvops->validate_stateid(delegation, stateid)) {
 549                 rcu_read_unlock();
 550                 return -ENOENT;
 551         }
 552         nfs_mark_return_delegation(server, delegation);
 553         rcu_read_unlock();
 554
 555         nfs_delegation_run_state_manager(clp);
 556         return 0;
 557 }
 558
 559 static struct inode *
 560 nfs_delegation_find_inode_server(struct nfs_server *server,
 561                                  const struct nfs_fh *fhandle)
 562 {
 563         struct nfs_delegation *delegation;
 564         struct inode *res = NULL;
 565
 566         list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
 567                 spin_lock(&delegation->lock);
 568                 if (delegation->inode != NULL &&
 569                     nfs_compare_fh(fhandle, &NFS_I(delegation->inode)->fh) == 0) {
 570                         res = igrab(delegation->inode);
 571                 }
 572                 spin_unlock(&delegation->lock);
 573                 if (res != NULL)
 574                         break;
 575         }
 576         return res;
 577 }
 578
 579 /**
 580  * nfs_delegation_find_inode - retrieve the inode associated with a delegation
 581  * @clp: client state handle
 582  * @fhandle: filehandle from a delegation recall
 583  *
 584  * Returns pointer to inode matching "fhandle," or NULL if a matching inode
 585  * cannot be found.
 586  */
 587 struct inode *nfs_delegation_find_inode(struct nfs_client *clp,
 588                                         const struct nfs_fh *fhandle)
 589 {
 590         struct nfs_server *server;
 591         struct inode *res = NULL;
 592
 593         rcu_read_lock();
 594         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link) {
 595                 res = nfs_delegation_find_inode_server(server, fhandle);
 596                 if (res != NULL)
 597                         break;
 598         }
 599         rcu_read_unlock();
 600         return res;
 601 }
 602
 603 static void nfs_delegation_mark_reclaim_server(struct nfs_server *server)
 604 {
 605         struct nfs_delegation *delegation;
 606
 607         list_for_each_entry_rcu(delegation, &server->delegations, super_list)
 608                 set_bit(NFS_DELEGATION_NEED_RECLAIM, &delegation->flags);
 609 }
 610
 611 /**
 612  * nfs_delegation_mark_reclaim - mark all delegations as needing to be reclaimed
 613  * @clp: nfs_client to process
 614  *
 615  */
 616 void nfs_delegation_mark_reclaim(struct nfs_client *clp)
 617 {
 618         struct nfs_server *server;
 619
 620         rcu_read_lock();
 621         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
 622                 nfs_delegation_mark_reclaim_server(server);
 623         rcu_read_unlock();
 624 }
 625
 626 /**
 627  * nfs_delegation_reap_unclaimed - reap unclaimed delegations after reboot recovery is done
 628  * @clp: nfs_client to process
 629  *
 630  */
 631 void nfs_delegation_reap_unclaimed(struct nfs_client *clp)
 632 {
 633         struct nfs_delegation *delegation;
 634         struct nfs_server *server;
 635         struct inode *inode;
 636
 637 restart:
 638         rcu_read_lock();
 639         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link) {
 640                 list_for_each_entry_rcu(delegation, &server->delegations,
 641                                                                 super_list) {
 642                         if (test_bit(NFS_DELEGATION_NEED_RECLAIM,
 643                                                 &delegation->flags) == 0)
 644                                 continue;
 645                         inode = nfs_delegation_grab_inode(delegation);
 646                         if (inode == NULL)
 647                                 continue;
 648                         delegation = nfs_detach_delegation(NFS_I(inode),
 649                                                                 server);
 650                         rcu_read_unlock();
 651
 652                         if (delegation != NULL)
 653                                 nfs_free_delegation(delegation);
 654                         iput(inode);
 655                         goto restart;
 656                 }
 657         }
 658         rcu_read_unlock();
 659 }
 660
 661 /**
 662  * nfs_delegations_present - check for existence of delegations
 663  * @clp: client state handle
 664  *
 665  * Returns one if there are any nfs_delegation structures attached
 666  * to this nfs_client.
 667  */
 668 int nfs_delegations_present(struct nfs_client *clp)
 669 {
 670         struct nfs_server *server;
 671         int ret = 0;
 672
 673         rcu_read_lock();
 674         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
 675                 if (!list_empty(&server->delegations)) {
 676                         ret = 1;
 677                         break;
 678                 }
 679         rcu_read_unlock();
 680         return ret;
 681 }
 682
 683 /**
 684  * nfs4_copy_delegation_stateid - Copy inode's state ID information
 685  * @dst: stateid data structure to fill in
 686  * @inode: inode to check
 687  *
 688  * Returns one and fills in "dst->data" * if inode had a delegation,
 689  * otherwise zero is returned.
 690  */
 691 int nfs4_copy_delegation_stateid(nfs4_stateid *dst, struct inode *inode)
 692 {
 693         struct nfs_inode *nfsi = NFS_I(inode);
 694         struct nfs_delegation *delegation;
 695         int ret = 0;
 696
 697         rcu_read_lock();
 698         delegation = rcu_dereference(nfsi->delegation);
 699         if (delegation != NULL) {
 700                 memcpy(dst->data, delegation->stateid.data, sizeof(dst->data));
 701                 ret = 1;
 702         }
 703         rcu_read_unlock();
 704         return ret;
 705 }