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 (!nfs4_stateid_match(&state->stateid, stateid))
 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                         nfs4_stateid_copy(&delegation->stateid, &res->delegation);
 143                         delegation->type = res->delegation_type;
 144                         delegation->maxsize = res->maxsize;
 145                         oldcred = delegation->cred;
 146                         delegation->cred = get_rpccred(cred);
 147                         clear_bit(NFS_DELEGATION_NEED_RECLAIM,
 148                                   &delegation->flags);
 149                         NFS_I(inode)->delegation_state = delegation->type;
 150                         spin_unlock(&delegation->lock);
 151                         put_rpccred(oldcred);
 152                         rcu_read_unlock();
 153                 } else {
 154                         /* We appear to have raced with a delegation return. */
 155                         spin_unlock(&delegation->lock);
 156                         rcu_read_unlock();
 157                         nfs_inode_set_delegation(inode, cred, res);
 158                 }
 159         } else {
 160                 rcu_read_unlock();
 161         }
 162 }
 163
 164 static int nfs_do_return_delegation(struct inode *inode, struct nfs_delegation *delegation, int issync)
 165 {
 166         int res = 0;
 167
 168         res = nfs4_proc_delegreturn(inode, delegation->cred, &delegation->stateid, issync);
 169         nfs_free_delegation(delegation);
 170         return res;
 171 }
 172
 173 static struct inode *nfs_delegation_grab_inode(struct nfs_delegation *delegation)
 174 {
 175         struct inode *inode = NULL;
 176
 177         spin_lock(&delegation->lock);
 178         if (delegation->inode != NULL)
 179                 inode = igrab(delegation->inode);
 180         spin_unlock(&delegation->lock);
 181         return inode;
 182 }
 183
 184 static struct nfs_delegation *
 185 nfs_detach_delegation_locked(struct nfs_inode *nfsi,
 186                              struct nfs_server *server)
 187 {
 188         struct nfs_delegation *delegation =
 189                 rcu_dereference_protected(nfsi->delegation,
 190                                 lockdep_is_held(&server->nfs_client->cl_lock));
 191
 192         if (delegation == NULL)
 193                 goto nomatch;
 194
 195         spin_lock(&delegation->lock);
 196         list_del_rcu(&delegation->super_list);
 197         delegation->inode = NULL;
 198         nfsi->delegation_state = 0;
 199         rcu_assign_pointer(nfsi->delegation, NULL);
 200         spin_unlock(&delegation->lock);
 201         return delegation;
 202 nomatch:
 203         return NULL;
 204 }
 205
 206 static struct nfs_delegation *nfs_detach_delegation(struct nfs_inode *nfsi,
 207                                                     struct nfs_server *server)
 208 {
 209         struct nfs_client *clp = server->nfs_client;
 210         struct nfs_delegation *delegation;
 211
 212         spin_lock(&clp->cl_lock);
 213         delegation = nfs_detach_delegation_locked(nfsi, server);
 214         spin_unlock(&clp->cl_lock);
 215         return delegation;
 216 }
 217
 218 /**
 219  * nfs_inode_set_delegation - set up a delegation on an inode
 220  * @inode: inode to which delegation applies
 221  * @cred: cred to use for subsequent delegation processing
 222  * @res: new delegation state from server
 223  *
 224  * Returns zero on success, or a negative errno value.
 225  */
 226 int nfs_inode_set_delegation(struct inode *inode, struct rpc_cred *cred, struct nfs_openres *res)
 227 {
 228         struct nfs_server *server = NFS_SERVER(inode);
 229         struct nfs_client *clp = server->nfs_client;
 230         struct nfs_inode *nfsi = NFS_I(inode);
 231         struct nfs_delegation *delegation, *old_delegation;
 232         struct nfs_delegation *freeme = NULL;
 233         int status = 0;
 234
 235         delegation = kmalloc(sizeof(*delegation), GFP_NOFS);
 236         if (delegation == NULL)
 237                 return -ENOMEM;
 238         nfs4_stateid_copy(&delegation->stateid, &res->delegation);
 239         delegation->type = res->delegation_type;
 240         delegation->maxsize = res->maxsize;
 241         delegation->change_attr = inode->i_version;
 242         delegation->cred = get_rpccred(cred);
 243         delegation->inode = inode;
 244         delegation->flags = 1<<NFS_DELEGATION_REFERENCED;
 245         spin_lock_init(&delegation->lock);
 246
 247         spin_lock(&clp->cl_lock);
 248         old_delegation = rcu_dereference_protected(nfsi->delegation,
 249                                         lockdep_is_held(&clp->cl_lock));
 250         if (old_delegation != NULL) {
 251                 if (nfs4_stateid_match(&delegation->stateid,
 252                                         &old_delegation->stateid) &&
 253                                 delegation->type == old_delegation->type) {
 254                         goto out;
 255                 }
 256                 /*
 257                  * Deal with broken servers that hand out two
 258                  * delegations for the same file.
 259                  * Allow for upgrades to a WRITE delegation, but
 260                  * nothing else.
 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                     !(delegation->type & FMODE_WRITE)) {
 267                         freeme = delegation;
 268                         delegation = NULL;
 269                         goto out;
 270                 }
 271                 freeme = nfs_detach_delegation_locked(nfsi, server);
 272         }
 273         list_add_rcu(&delegation->super_list, &server->delegations);
 274         nfsi->delegation_state = delegation->type;
 275         rcu_assign_pointer(nfsi->delegation, delegation);
 276         delegation = NULL;
 277
 278         /* Ensure we revalidate the attributes and page cache! */
 279         spin_lock(&inode->i_lock);
 280         nfsi->cache_validity |= NFS_INO_REVAL_FORCED;
 281         spin_unlock(&inode->i_lock);
 282
 283 out:
 284         spin_unlock(&clp->cl_lock);
 285         if (delegation != NULL)
 286                 nfs_free_delegation(delegation);
 287         if (freeme != NULL)
 288                 nfs_do_return_delegation(inode, freeme, 0);
 289         return status;
 290 }
 291
 292 /*
 293  * Basic procedure for returning a delegation to the server
 294  */
 295 static int __nfs_inode_return_delegation(struct inode *inode, struct nfs_delegation *delegation, int issync)
 296 {
 297         struct nfs_inode *nfsi = NFS_I(inode);
 298         int err;
 299
 300         /*
 301          * Guard against new delegated open/lock/unlock calls and against
 302          * state recovery
 303          */
 304         down_write(&nfsi->rwsem);
 305         err = nfs_delegation_claim_opens(inode, &delegation->stateid);
 306         up_write(&nfsi->rwsem);
 307         if (err)
 308                 goto out;
 309
 310         err = nfs_do_return_delegation(inode, delegation, issync);
 311 out:
 312         return err;
 313 }
 314
 315 /**
 316  * nfs_client_return_marked_delegations - return previously marked delegations
 317  * @clp: nfs_client to process
 318  *
 319  * Returns zero on success, or a negative errno value.
 320  */
 321 int nfs_client_return_marked_delegations(struct nfs_client *clp)
 322 {
 323         struct nfs_delegation *delegation;
 324         struct nfs_server *server;
 325         struct inode *inode;
 326         int err = 0;
 327
 328 restart:
 329         rcu_read_lock();
 330         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link) {
 331                 list_for_each_entry_rcu(delegation, &server->delegations,
 332                                                                 super_list) {
 333                         if (!test_and_clear_bit(NFS_DELEGATION_RETURN,
 334                                                         &delegation->flags))
 335                                 continue;
 336                         inode = nfs_delegation_grab_inode(delegation);
 337                         if (inode == NULL)
 338                                 continue;
 339                         delegation = nfs_detach_delegation(NFS_I(inode),
 340                                                                 server);
 341                         rcu_read_unlock();
 342
 343                         if (delegation != NULL) {
 344                                 filemap_flush(inode->i_mapping);
 345                                 err = __nfs_inode_return_delegation(inode,
 346                                                                 delegation, 0);
 347                         }
 348                         iput(inode);
 349                         if (!err)
 350                                 goto restart;
 351                         set_bit(NFS4CLNT_DELEGRETURN, &clp->cl_state);
 352                         return err;
 353                 }
 354         }
 355         rcu_read_unlock();
 356         return 0;
 357 }
 358
 359 /**
 360  * nfs_inode_return_delegation_noreclaim - return delegation, don't reclaim opens
 361  * @inode: inode to process
 362  *
 363  * Does not protect against delegation reclaims, therefore really only safe
 364  * to be called from nfs4_clear_inode().
 365  */
 366 void nfs_inode_return_delegation_noreclaim(struct inode *inode)
 367 {
 368         struct nfs_server *server = NFS_SERVER(inode);
 369         struct nfs_inode *nfsi = NFS_I(inode);
 370         struct nfs_delegation *delegation;
 371
 372         if (rcu_access_pointer(nfsi->delegation) != NULL) {
 373                 delegation = nfs_detach_delegation(nfsi, server);
 374                 if (delegation != NULL)
 375                         nfs_do_return_delegation(inode, delegation, 0);
 376         }
 377 }
 378
 379 /**
 380  * nfs_inode_return_delegation - synchronously return a delegation
 381  * @inode: inode to process
 382  *
 383  * This routine will always flush any dirty data to disk on the
 384  * assumption that if we need to return the delegation, then
 385  * we should stop caching.
 386  *
 387  * Returns zero on success, or a negative errno value.
 388  */
 389 int nfs_inode_return_delegation(struct inode *inode)
 390 {
 391         struct nfs_server *server = NFS_SERVER(inode);
 392         struct nfs_inode *nfsi = NFS_I(inode);
 393         struct nfs_delegation *delegation;
 394         int err = 0;
 395
 396         nfs_wb_all(inode);
 397         if (rcu_access_pointer(nfsi->delegation) != NULL) {
 398                 delegation = nfs_detach_delegation(nfsi, server);
 399                 if (delegation != NULL) {
 400                         err = __nfs_inode_return_delegation(inode, delegation, 1);
 401                 }
 402         }
 403         return err;
 404 }
 405
 406 static void nfs_mark_return_delegation(struct nfs_server *server,
 407                 struct nfs_delegation *delegation)
 408 {
 409         set_bit(NFS_DELEGATION_RETURN, &delegation->flags);
 410         set_bit(NFS4CLNT_DELEGRETURN, &server->nfs_client->cl_state);
 411 }
 412
 413 /**
 414  * nfs_super_return_all_delegations - return delegations for one superblock
 415  * @sb: sb to process
 416  *
 417  */
 418 void nfs_super_return_all_delegations(struct super_block *sb)
 419 {
 420         struct nfs_server *server = NFS_SB(sb);
 421         struct nfs_client *clp = server->nfs_client;
 422         struct nfs_delegation *delegation;
 423
 424         if (clp == NULL)
 425                 return;
 426
 427         rcu_read_lock();
 428         list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
 429                 spin_lock(&delegation->lock);
 430                 set_bit(NFS_DELEGATION_RETURN, &delegation->flags);
 431                 spin_unlock(&delegation->lock);
 432         }
 433         rcu_read_unlock();
 434
 435         if (nfs_client_return_marked_delegations(clp) != 0)
 436                 nfs4_schedule_state_manager(clp);
 437 }
 438
 439 static void nfs_mark_return_all_delegation_types(struct nfs_server *server,
 440                                                  fmode_t flags)
 441 {
 442         struct nfs_delegation *delegation;
 443
 444         list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
 445                 if ((delegation->type == (FMODE_READ|FMODE_WRITE)) && !(flags & FMODE_WRITE))
 446                         continue;
 447                 if (delegation->type & flags)
 448                         nfs_mark_return_delegation(server, delegation);
 449         }
 450 }
 451
 452 static void nfs_client_mark_return_all_delegation_types(struct nfs_client *clp,
 453                                                         fmode_t flags)
 454 {
 455         struct nfs_server *server;
 456
 457         rcu_read_lock();
 458         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
 459                 nfs_mark_return_all_delegation_types(server, flags);
 460         rcu_read_unlock();
 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 void nfs_remove_bad_delegation(struct inode *inode)
 470 {
 471         struct nfs_delegation *delegation;
 472
 473         delegation = nfs_detach_delegation(NFS_I(inode), NFS_SERVER(inode));
 474         if (delegation) {
 475                 nfs_inode_find_state_and_recover(inode, &delegation->stateid);
 476                 nfs_free_delegation(delegation);
 477         }
 478 }
 479 EXPORT_SYMBOL_GPL(nfs_remove_bad_delegation);
 480
 481 /**
 482  * nfs_expire_all_delegation_types
 483  * @clp: client to process
 484  * @flags: delegation types to expire
 485  *
 486  */
 487 void nfs_expire_all_delegation_types(struct nfs_client *clp, fmode_t flags)
 488 {
 489         nfs_client_mark_return_all_delegation_types(clp, flags);
 490         nfs_delegation_run_state_manager(clp);
 491 }
 492
 493 /**
 494  * nfs_expire_all_delegations
 495  * @clp: client to process
 496  *
 497  */
 498 void nfs_expire_all_delegations(struct nfs_client *clp)
 499 {
 500         nfs_expire_all_delegation_types(clp, FMODE_READ|FMODE_WRITE);
 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
 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->match_stateid(&delegation->stateid, 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  * @flags: delegation type requirement
 688  *
 689  * Returns "true" and fills in "dst->data" * if inode had a delegation,
 690  * otherwise "false" is returned.
 691  */
 692 bool nfs4_copy_delegation_stateid(nfs4_stateid *dst, struct inode *inode,
 693                 fmode_t flags)
 694 {
 695         struct nfs_inode *nfsi = NFS_I(inode);
 696         struct nfs_delegation *delegation;
 697         bool ret;
 698
 699         flags &= FMODE_READ|FMODE_WRITE;
 700         rcu_read_lock();
 701         delegation = rcu_dereference(nfsi->delegation);
 702         ret = (delegation != NULL && (delegation->type & flags) == flags);
 703         if (ret) {
 704                 nfs4_stateid_copy(dst, &delegation->stateid);
 705                 nfs_mark_delegation_referenced(delegation);
 706         }
 707         rcu_read_unlock();
 708         return ret;
 709 }