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_do_free_delegation(struct nfs_delegation *delegation)
  25 {
  26         kfree(delegation);
  27 }
  28
  29 static void nfs_free_delegation_callback(struct rcu_head *head)
  30 {
  31         struct nfs_delegation *delegation = container_of(head, struct nfs_delegation, rcu);
  32
  33         nfs_do_free_delegation(delegation);
  34 }
  35
  36 static void nfs_free_delegation(struct nfs_delegation *delegation)
  37 {
  38         if (delegation->cred) {
  39                 put_rpccred(delegation->cred);
  40                 delegation->cred = NULL;
  41         }
  42         call_rcu(&delegation->rcu, nfs_free_delegation_callback);
  43 }
  44
  45 /**
  46  * nfs_mark_delegation_referenced - set delegation's REFERENCED flag
  47  * @delegation: delegation to process
  48  *
  49  */
  50 void nfs_mark_delegation_referenced(struct nfs_delegation *delegation)
  51 {
  52         set_bit(NFS_DELEGATION_REFERENCED, &delegation->flags);
  53 }
  54
  55 /**
  56  * nfs_have_delegation - check if inode has a delegation
  57  * @inode: inode to check
  58  * @flags: delegation types to check for
  59  *
  60  * Returns one if inode has the indicated delegation, otherwise zero.
  61  */
  62 int nfs_have_delegation(struct inode *inode, fmode_t flags)
  63 {
  64         struct nfs_delegation *delegation;
  65         int ret = 0;
  66
  67         flags &= FMODE_READ|FMODE_WRITE;
  68         rcu_read_lock();
  69         delegation = rcu_dereference(NFS_I(inode)->delegation);
  70         if (delegation != NULL && (delegation->type & flags) == flags) {
  71                 nfs_mark_delegation_referenced(delegation);
  72                 ret = 1;
  73         }
  74         rcu_read_unlock();
  75         return ret;
  76 }
  77
  78 static int nfs_delegation_claim_locks(struct nfs_open_context *ctx, struct nfs4_state *state)
  79 {
  80         struct inode *inode = state->inode;
  81         struct file_lock *fl;
  82         int status = 0;
  83
  84         if (inode->i_flock == NULL)
  85                 goto out;
  86
  87         /* Protect inode->i_flock using the file locks lock */
  88         lock_flocks();
  89         for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) {
  90                 if (!(fl->fl_flags & (FL_POSIX|FL_FLOCK)))
  91                         continue;
  92                 if (nfs_file_open_context(fl->fl_file) != ctx)
  93                         continue;
  94                 unlock_flocks();
  95                 status = nfs4_lock_delegation_recall(state, fl);
  96                 if (status < 0)
  97                         goto out;
  98                 lock_flocks();
  99         }
 100         unlock_flocks();
 101 out:
 102         return status;
 103 }
 104
 105 static int nfs_delegation_claim_opens(struct inode *inode, const nfs4_stateid *stateid)
 106 {
 107         struct nfs_inode *nfsi = NFS_I(inode);
 108         struct nfs_open_context *ctx;
 109         struct nfs4_state *state;
 110         int err;
 111
 112 again:
 113         spin_lock(&inode->i_lock);
 114         list_for_each_entry(ctx, &nfsi->open_files, list) {
 115                 state = ctx->state;
 116                 if (state == NULL)
 117                         continue;
 118                 if (!test_bit(NFS_DELEGATED_STATE, &state->flags))
 119                         continue;
 120                 if (memcmp(state->stateid.data, stateid->data, sizeof(state->stateid.data)) != 0)
 121                         continue;
 122                 get_nfs_open_context(ctx);
 123                 spin_unlock(&inode->i_lock);
 124                 err = nfs4_open_delegation_recall(ctx, state, stateid);
 125                 if (err >= 0)
 126                         err = nfs_delegation_claim_locks(ctx, state);
 127                 put_nfs_open_context(ctx);
 128                 if (err != 0)
 129                         return err;
 130                 goto again;
 131         }
 132         spin_unlock(&inode->i_lock);
 133         return 0;
 134 }
 135
 136 /**
 137  * nfs_inode_reclaim_delegation - process a delegation reclaim request
 138  * @inode: inode to process
 139  * @cred: credential to use for request
 140  * @res: new delegation state from server
 141  *
 142  */
 143 void nfs_inode_reclaim_delegation(struct inode *inode, struct rpc_cred *cred,
 144                                   struct nfs_openres *res)
 145 {
 146         struct nfs_delegation *delegation;
 147         struct rpc_cred *oldcred = NULL;
 148
 149         rcu_read_lock();
 150         delegation = rcu_dereference(NFS_I(inode)->delegation);
 151         if (delegation != NULL) {
 152                 spin_lock(&delegation->lock);
 153                 if (delegation->inode != NULL) {
 154                         memcpy(delegation->stateid.data, res->delegation.data,
 155                                sizeof(delegation->stateid.data));
 156                         delegation->type = res->delegation_type;
 157                         delegation->maxsize = res->maxsize;
 158                         oldcred = delegation->cred;
 159                         delegation->cred = get_rpccred(cred);
 160                         clear_bit(NFS_DELEGATION_NEED_RECLAIM,
 161                                   &delegation->flags);
 162                         NFS_I(inode)->delegation_state = delegation->type;
 163                         spin_unlock(&delegation->lock);
 164                         put_rpccred(oldcred);
 165                         rcu_read_unlock();
 166                 } else {
 167                         /* We appear to have raced with a delegation return. */
 168                         spin_unlock(&delegation->lock);
 169                         rcu_read_unlock();
 170                         nfs_inode_set_delegation(inode, cred, res);
 171                 }
 172         } else {
 173                 rcu_read_unlock();
 174         }
 175 }
 176
 177 static int nfs_do_return_delegation(struct inode *inode, struct nfs_delegation *delegation, int issync)
 178 {
 179         int res = 0;
 180
 181         res = nfs4_proc_delegreturn(inode, delegation->cred, &delegation->stateid, issync);
 182         nfs_free_delegation(delegation);
 183         return res;
 184 }
 185
 186 static struct inode *nfs_delegation_grab_inode(struct nfs_delegation *delegation)
 187 {
 188         struct inode *inode = NULL;
 189
 190         spin_lock(&delegation->lock);
 191         if (delegation->inode != NULL)
 192                 inode = igrab(delegation->inode);
 193         spin_unlock(&delegation->lock);
 194         return inode;
 195 }
 196
 197 static struct nfs_delegation *
 198 nfs_detach_delegation_locked(struct nfs_inode *nfsi,
 199                              struct nfs_server *server)
 200 {
 201         struct nfs_delegation *delegation =
 202                 rcu_dereference_protected(nfsi->delegation,
 203                                 lockdep_is_held(&server->nfs_client->cl_lock));
 204
 205         if (delegation == NULL)
 206                 goto nomatch;
 207
 208         spin_lock(&delegation->lock);
 209         list_del_rcu(&delegation->super_list);
 210         delegation->inode = NULL;
 211         nfsi->delegation_state = 0;
 212         rcu_assign_pointer(nfsi->delegation, NULL);
 213         spin_unlock(&delegation->lock);
 214         return delegation;
 215 nomatch:
 216         return NULL;
 217 }
 218
 219 static struct nfs_delegation *nfs_detach_delegation(struct nfs_inode *nfsi,
 220                                                     struct nfs_server *server)
 221 {
 222         struct nfs_client *clp = server->nfs_client;
 223         struct nfs_delegation *delegation;
 224
 225         spin_lock(&clp->cl_lock);
 226         delegation = nfs_detach_delegation_locked(nfsi, server);
 227         spin_unlock(&clp->cl_lock);
 228         return delegation;
 229 }
 230
 231 /**
 232  * nfs_inode_set_delegation - set up a delegation on an inode
 233  * @inode: inode to which delegation applies
 234  * @cred: cred to use for subsequent delegation processing
 235  * @res: new delegation state from server
 236  *
 237  * Returns zero on success, or a negative errno value.
 238  */
 239 int nfs_inode_set_delegation(struct inode *inode, struct rpc_cred *cred, struct nfs_openres *res)
 240 {
 241         struct nfs_server *server = NFS_SERVER(inode);
 242         struct nfs_client *clp = server->nfs_client;
 243         struct nfs_inode *nfsi = NFS_I(inode);
 244         struct nfs_delegation *delegation, *old_delegation;
 245         struct nfs_delegation *freeme = NULL;
 246         int status = 0;
 247
 248         delegation = kmalloc(sizeof(*delegation), GFP_NOFS);
 249         if (delegation == NULL)
 250                 return -ENOMEM;
 251         memcpy(delegation->stateid.data, res->delegation.data,
 252                         sizeof(delegation->stateid.data));
 253         delegation->type = res->delegation_type;
 254         delegation->maxsize = res->maxsize;
 255         delegation->change_attr = nfsi->change_attr;
 256         delegation->cred = get_rpccred(cred);
 257         delegation->inode = inode;
 258         delegation->flags = 1<<NFS_DELEGATION_REFERENCED;
 259         spin_lock_init(&delegation->lock);
 260
 261         spin_lock(&clp->cl_lock);
 262         old_delegation = rcu_dereference_protected(nfsi->delegation,
 263                                         lockdep_is_held(&clp->cl_lock));
 264         if (old_delegation != NULL) {
 265                 if (memcmp(&delegation->stateid, &old_delegation->stateid,
 266                                         sizeof(old_delegation->stateid)) == 0 &&
 267                                 delegation->type == old_delegation->type) {
 268                         goto out;
 269                 }
 270                 /*
 271                  * Deal with broken servers that hand out two
 272                  * delegations for the same file.
 273                  */
 274                 dfprintk(FILE, "%s: server %s handed out "
 275                                 "a duplicate delegation!\n",
 276                                 __func__, clp->cl_hostname);
 277                 if (delegation->type <= old_delegation->type) {
 278                         freeme = delegation;
 279                         delegation = NULL;
 280                         goto out;
 281                 }
 282                 freeme = nfs_detach_delegation_locked(nfsi, server);
 283         }
 284         list_add_rcu(&delegation->super_list, &server->delegations);
 285         nfsi->delegation_state = delegation->type;
 286         rcu_assign_pointer(nfsi->delegation, delegation);
 287         delegation = NULL;
 288
 289         /* Ensure we revalidate the attributes and page cache! */
 290         spin_lock(&inode->i_lock);
 291         nfsi->cache_validity |= NFS_INO_REVAL_FORCED;
 292         spin_unlock(&inode->i_lock);
 293
 294 out:
 295         spin_unlock(&clp->cl_lock);
 296         if (delegation != NULL)
 297                 nfs_free_delegation(delegation);
 298         if (freeme != NULL)
 299                 nfs_do_return_delegation(inode, freeme, 0);
 300         return status;
 301 }
 302
 303 /*
 304  * Basic procedure for returning a delegation to the server
 305  */
 306 static int __nfs_inode_return_delegation(struct inode *inode, struct nfs_delegation *delegation, int issync)
 307 {
 308         struct nfs_inode *nfsi = NFS_I(inode);
 309         int err;
 310
 311         /*
 312          * Guard against new delegated open/lock/unlock calls and against
 313          * state recovery
 314          */
 315         down_write(&nfsi->rwsem);
 316         err = nfs_delegation_claim_opens(inode, &delegation->stateid);
 317         up_write(&nfsi->rwsem);
 318         if (err)
 319                 goto out;
 320
 321         err = nfs_do_return_delegation(inode, delegation, issync);
 322 out:
 323         return err;
 324 }
 325
 326 /**
 327  * nfs_client_return_marked_delegations - return previously marked delegations
 328  * @clp: nfs_client to process
 329  *
 330  * Returns zero on success, or a negative errno value.
 331  */
 332 int nfs_client_return_marked_delegations(struct nfs_client *clp)
 333 {
 334         struct nfs_delegation *delegation;
 335         struct nfs_server *server;
 336         struct inode *inode;
 337         int err = 0;
 338
 339 restart:
 340         rcu_read_lock();
 341         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link) {
 342                 list_for_each_entry_rcu(delegation, &server->delegations,
 343                                                                 super_list) {
 344                         if (!test_and_clear_bit(NFS_DELEGATION_RETURN,
 345                                                         &delegation->flags))
 346                                 continue;
 347                         inode = nfs_delegation_grab_inode(delegation);
 348                         if (inode == NULL)
 349                                 continue;
 350                         delegation = nfs_detach_delegation(NFS_I(inode),
 351                                                                 server);
 352                         rcu_read_unlock();
 353
 354                         if (delegation != NULL) {
 355                                 filemap_flush(inode->i_mapping);
 356                                 err = __nfs_inode_return_delegation(inode,
 357                                                                 delegation, 0);
 358                         }
 359                         iput(inode);
 360                         if (!err)
 361                                 goto restart;
 362                         set_bit(NFS4CLNT_DELEGRETURN, &clp->cl_state);
 363                         return err;
 364                 }
 365         }
 366         rcu_read_unlock();
 367         return 0;
 368 }
 369
 370 /**
 371  * nfs_inode_return_delegation_noreclaim - return delegation, don't reclaim opens
 372  * @inode: inode to process
 373  *
 374  * Does not protect against delegation reclaims, therefore really only safe
 375  * to be called from nfs4_clear_inode().
 376  */
 377 void nfs_inode_return_delegation_noreclaim(struct inode *inode)
 378 {
 379         struct nfs_server *server = NFS_SERVER(inode);
 380         struct nfs_inode *nfsi = NFS_I(inode);
 381         struct nfs_delegation *delegation;
 382
 383         if (rcu_access_pointer(nfsi->delegation) != NULL) {
 384                 delegation = nfs_detach_delegation(nfsi, server);
 385                 if (delegation != NULL)
 386                         nfs_do_return_delegation(inode, delegation, 0);
 387         }
 388 }
 389
 390 /**
 391  * nfs_inode_return_delegation - synchronously return a delegation
 392  * @inode: inode to process
 393  *
 394  * Returns zero on success, or a negative errno value.
 395  */
 396 int nfs_inode_return_delegation(struct inode *inode)
 397 {
 398         struct nfs_server *server = NFS_SERVER(inode);
 399         struct nfs_inode *nfsi = NFS_I(inode);
 400         struct nfs_delegation *delegation;
 401         int err = 0;
 402
 403         if (rcu_access_pointer(nfsi->delegation) != NULL) {
 404                 delegation = nfs_detach_delegation(nfsi, server);
 405                 if (delegation != NULL) {
 406                         nfs_wb_all(inode);
 407                         err = __nfs_inode_return_delegation(inode, delegation, 1);
 408                 }
 409         }
 410         return err;
 411 }
 412
 413 static void nfs_mark_return_delegation(struct nfs_delegation *delegation)
 414 {
 415         struct nfs_client *clp = NFS_SERVER(delegation->inode)->nfs_client;
 416
 417         set_bit(NFS_DELEGATION_RETURN, &delegation->flags);
 418         set_bit(NFS4CLNT_DELEGRETURN, &clp->cl_state);
 419 }
 420
 421 /**
 422  * nfs_super_return_all_delegations - return delegations for one superblock
 423  * @sb: sb to process
 424  *
 425  */
 426 void nfs_super_return_all_delegations(struct super_block *sb)
 427 {
 428         struct nfs_server *server = NFS_SB(sb);
 429         struct nfs_client *clp = server->nfs_client;
 430         struct nfs_delegation *delegation;
 431
 432         if (clp == NULL)
 433                 return;
 434
 435         rcu_read_lock();
 436         list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
 437                 spin_lock(&delegation->lock);
 438                 set_bit(NFS_DELEGATION_RETURN, &delegation->flags);
 439                 spin_unlock(&delegation->lock);
 440         }
 441         rcu_read_unlock();
 442
 443         if (nfs_client_return_marked_delegations(clp) != 0)
 444                 nfs4_schedule_state_manager(clp);
 445 }
 446
 447 static void nfs_mark_return_all_delegation_types(struct nfs_server *server,
 448                                                  fmode_t flags)
 449 {
 450         struct nfs_delegation *delegation;
 451
 452         list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
 453                 if ((delegation->type == (FMODE_READ|FMODE_WRITE)) && !(flags & FMODE_WRITE))
 454                         continue;
 455                 if (delegation->type & flags)
 456                         nfs_mark_return_delegation(delegation);
 457         }
 458 }
 459
 460 static void nfs_client_mark_return_all_delegation_types(struct nfs_client *clp,
 461                                                         fmode_t flags)
 462 {
 463         struct nfs_server *server;
 464
 465         rcu_read_lock();
 466         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
 467                 nfs_mark_return_all_delegation_types(server, flags);
 468         rcu_read_unlock();
 469 }
 470
 471 static void nfs_client_mark_return_all_delegations(struct nfs_client *clp)
 472 {
 473         nfs_client_mark_return_all_delegation_types(clp, FMODE_READ|FMODE_WRITE);
 474 }
 475
 476 static void nfs_delegation_run_state_manager(struct nfs_client *clp)
 477 {
 478         if (test_bit(NFS4CLNT_DELEGRETURN, &clp->cl_state))
 479                 nfs4_schedule_state_manager(clp);
 480 }
 481
 482 /**
 483  * nfs_expire_all_delegation_types
 484  * @clp: client to process
 485  * @flags: delegation types to expire
 486  *
 487  */
 488 void nfs_expire_all_delegation_types(struct nfs_client *clp, fmode_t flags)
 489 {
 490         nfs_client_mark_return_all_delegation_types(clp, flags);
 491         nfs_delegation_run_state_manager(clp);
 492 }
 493
 494 /**
 495  * nfs_expire_all_delegations
 496  * @clp: client to process
 497  *
 498  */
 499 void nfs_expire_all_delegations(struct nfs_client *clp)
 500 {
 501         nfs_expire_all_delegation_types(clp, FMODE_READ|FMODE_WRITE);
 502 }
 503
 504 /**
 505  * nfs_handle_cb_pathdown - return all delegations after NFS4ERR_CB_PATH_DOWN
 506  * @clp: client to process
 507  *
 508  */
 509 void nfs_handle_cb_pathdown(struct nfs_client *clp)
 510 {
 511         if (clp == NULL)
 512                 return;
 513         nfs_client_mark_return_all_delegations(clp);
 514 }
 515
 516 static void nfs_mark_return_unreferenced_delegations(struct nfs_server *server)
 517 {
 518         struct nfs_delegation *delegation;
 519
 520         list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
 521                 if (test_and_clear_bit(NFS_DELEGATION_REFERENCED, &delegation->flags))
 522                         continue;
 523                 nfs_mark_return_delegation(delegation);
 524         }
 525 }
 526
 527 /**
 528  * nfs_expire_unreferenced_delegations - Eliminate unused delegations
 529  * @clp: nfs_client to process
 530  *
 531  */
 532 void nfs_expire_unreferenced_delegations(struct nfs_client *clp)
 533 {
 534         struct nfs_server *server;
 535
 536         rcu_read_lock();
 537         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
 538                 nfs_mark_return_unreferenced_delegations(server);
 539         rcu_read_unlock();
 540
 541         nfs_delegation_run_state_manager(clp);
 542 }
 543
 544 /**
 545  * nfs_async_inode_return_delegation - asynchronously return a delegation
 546  * @inode: inode to process
 547  * @stateid: state ID information from CB_RECALL arguments
 548  *
 549  * Returns zero on success, or a negative errno value.
 550  */
 551 int nfs_async_inode_return_delegation(struct inode *inode,
 552                                       const nfs4_stateid *stateid)
 553 {
 554         struct nfs_client *clp = NFS_SERVER(inode)->nfs_client;
 555         struct nfs_delegation *delegation;
 556
 557         rcu_read_lock();
 558         delegation = rcu_dereference(NFS_I(inode)->delegation);
 559
 560         if (!clp->cl_mvops->validate_stateid(delegation, stateid)) {
 561                 rcu_read_unlock();
 562                 return -ENOENT;
 563         }
 564         nfs_mark_return_delegation(delegation);
 565         rcu_read_unlock();
 566
 567         nfs_delegation_run_state_manager(clp);
 568         return 0;
 569 }
 570
 571 static struct inode *
 572 nfs_delegation_find_inode_server(struct nfs_server *server,
 573                                  const struct nfs_fh *fhandle)
 574 {
 575         struct nfs_delegation *delegation;
 576         struct inode *res = NULL;
 577
 578         list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
 579                 spin_lock(&delegation->lock);
 580                 if (delegation->inode != NULL &&
 581                     nfs_compare_fh(fhandle, &NFS_I(delegation->inode)->fh) == 0) {
 582                         res = igrab(delegation->inode);
 583                 }
 584                 spin_unlock(&delegation->lock);
 585                 if (res != NULL)
 586                         break;
 587         }
 588         return res;
 589 }
 590
 591 /**
 592  * nfs_delegation_find_inode - retrieve the inode associated with a delegation
 593  * @clp: client state handle
 594  * @fhandle: filehandle from a delegation recall
 595  *
 596  * Returns pointer to inode matching "fhandle," or NULL if a matching inode
 597  * cannot be found.
 598  */
 599 struct inode *nfs_delegation_find_inode(struct nfs_client *clp,
 600                                         const struct nfs_fh *fhandle)
 601 {
 602         struct nfs_server *server;
 603         struct inode *res = NULL;
 604
 605         rcu_read_lock();
 606         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link) {
 607                 res = nfs_delegation_find_inode_server(server, fhandle);
 608                 if (res != NULL)
 609                         break;
 610         }
 611         rcu_read_unlock();
 612         return res;
 613 }
 614
 615 static void nfs_delegation_mark_reclaim_server(struct nfs_server *server)
 616 {
 617         struct nfs_delegation *delegation;
 618
 619         list_for_each_entry_rcu(delegation, &server->delegations, super_list)
 620                 set_bit(NFS_DELEGATION_NEED_RECLAIM, &delegation->flags);
 621 }
 622
 623 /**
 624  * nfs_delegation_mark_reclaim - mark all delegations as needing to be reclaimed
 625  * @clp: nfs_client to process
 626  *
 627  */
 628 void nfs_delegation_mark_reclaim(struct nfs_client *clp)
 629 {
 630         struct nfs_server *server;
 631
 632         rcu_read_lock();
 633         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
 634                 nfs_delegation_mark_reclaim_server(server);
 635         rcu_read_unlock();
 636 }
 637
 638 /**
 639  * nfs_delegation_reap_unclaimed - reap unclaimed delegations after reboot recovery is done
 640  * @clp: nfs_client to process
 641  *
 642  */
 643 void nfs_delegation_reap_unclaimed(struct nfs_client *clp)
 644 {
 645         struct nfs_delegation *delegation;
 646         struct nfs_server *server;
 647         struct inode *inode;
 648
 649 restart:
 650         rcu_read_lock();
 651         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link) {
 652                 list_for_each_entry_rcu(delegation, &server->delegations,
 653                                                                 super_list) {
 654                         if (test_bit(NFS_DELEGATION_NEED_RECLAIM,
 655                                                 &delegation->flags) == 0)
 656                                 continue;
 657                         inode = nfs_delegation_grab_inode(delegation);
 658                         if (inode == NULL)
 659                                 continue;
 660                         delegation = nfs_detach_delegation(NFS_I(inode),
 661                                                                 server);
 662                         rcu_read_unlock();
 663
 664                         if (delegation != NULL)
 665                                 nfs_free_delegation(delegation);
 666                         iput(inode);
 667                         goto restart;
 668                 }
 669         }
 670         rcu_read_unlock();
 671 }
 672
 673 /**
 674  * nfs_delegations_present - check for existence of delegations
 675  * @clp: client state handle
 676  *
 677  * Returns one if there are any nfs_delegation structures attached
 678  * to this nfs_client.
 679  */
 680 int nfs_delegations_present(struct nfs_client *clp)
 681 {
 682         struct nfs_server *server;
 683         int ret = 0;
 684
 685         rcu_read_lock();
 686         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
 687                 if (!list_empty(&server->delegations)) {
 688                         ret = 1;
 689                         break;
 690                 }
 691         rcu_read_unlock();
 692         return ret;
 693 }
 694
 695 /**
 696  * nfs4_copy_delegation_stateid - Copy inode's state ID information
 697  * @dst: stateid data structure to fill in
 698  * @inode: inode to check
 699  *
 700  * Returns one and fills in "dst->data" * if inode had a delegation,
 701  * otherwise zero is returned.
 702  */
 703 int nfs4_copy_delegation_stateid(nfs4_stateid *dst, struct inode *inode)
 704 {
 705         struct nfs_inode *nfsi = NFS_I(inode);
 706         struct nfs_delegation *delegation;
 707         int ret = 0;
 708
 709         rcu_read_lock();
 710         delegation = rcu_dereference(nfsi->delegation);
 711         if (delegation != NULL) {
 712                 memcpy(dst->data, delegation->stateid.data, sizeof(dst->data));
 713                 ret = 1;
 714         }
 715         rcu_read_unlock();
 716         return ret;
 717 }