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  * Note that this function is designed to be called by the state
 320  * manager thread. For this reason, it cannot flush the dirty data,
 321  * since that could deadlock in case of a state recovery error.
 322  *
 323  * Returns zero on success, or a negative errno value.
 324  */
 325 int nfs_client_return_marked_delegations(struct nfs_client *clp)
 326 {
 327         struct nfs_delegation *delegation;
 328         struct nfs_server *server;
 329         struct inode *inode;
 330         int err = 0;
 331
 332 restart:
 333         rcu_read_lock();
 334         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link) {
 335                 list_for_each_entry_rcu(delegation, &server->delegations,
 336                                                                 super_list) {
 337                         if (!test_and_clear_bit(NFS_DELEGATION_RETURN,
 338                                                         &delegation->flags))
 339                                 continue;
 340                         inode = nfs_delegation_grab_inode(delegation);
 341                         if (inode == NULL)
 342                                 continue;
 343                         delegation = nfs_detach_delegation(NFS_I(inode),
 344                                                                 server);
 345                         rcu_read_unlock();
 346
 347                         if (delegation != NULL)
 348                                 err = __nfs_inode_return_delegation(inode,
 349                                                                 delegation, 0);
 350                         iput(inode);
 351                         if (!err)
 352                                 goto restart;
 353                         set_bit(NFS4CLNT_DELEGRETURN, &clp->cl_state);
 354                         return err;
 355                 }
 356         }
 357         rcu_read_unlock();
 358         return 0;
 359 }
 360
 361 /**
 362  * nfs_inode_return_delegation_noreclaim - return delegation, don't reclaim opens
 363  * @inode: inode to process
 364  *
 365  * Does not protect against delegation reclaims, therefore really only safe
 366  * to be called from nfs4_clear_inode().
 367  */
 368 void nfs_inode_return_delegation_noreclaim(struct inode *inode)
 369 {
 370         struct nfs_server *server = NFS_SERVER(inode);
 371         struct nfs_inode *nfsi = NFS_I(inode);
 372         struct nfs_delegation *delegation;
 373
 374         if (rcu_access_pointer(nfsi->delegation) != NULL) {
 375                 delegation = nfs_detach_delegation(nfsi, server);
 376                 if (delegation != NULL)
 377                         nfs_do_return_delegation(inode, delegation, 0);
 378         }
 379 }
 380
 381 /**
 382  * nfs_inode_return_delegation - synchronously return a delegation
 383  * @inode: inode to process
 384  *
 385  * This routine will always flush any dirty data to disk on the
 386  * assumption that if we need to return the delegation, then
 387  * we should stop caching.
 388  *
 389  * Returns zero on success, or a negative errno value.
 390  */
 391 int nfs_inode_return_delegation(struct inode *inode)
 392 {
 393         struct nfs_server *server = NFS_SERVER(inode);
 394         struct nfs_inode *nfsi = NFS_I(inode);
 395         struct nfs_delegation *delegation;
 396         int err = 0;
 397
 398         nfs_wb_all(inode);
 399         if (rcu_access_pointer(nfsi->delegation) != NULL) {
 400                 delegation = nfs_detach_delegation(nfsi, server);
 401                 if (delegation != NULL) {
 402                         err = __nfs_inode_return_delegation(inode, delegation, 1);
 403                 }
 404         }
 405         return err;
 406 }
 407
 408 static void nfs_mark_return_delegation(struct nfs_server *server,
 409                 struct nfs_delegation *delegation)
 410 {
 411         set_bit(NFS_DELEGATION_RETURN, &delegation->flags);
 412         set_bit(NFS4CLNT_DELEGRETURN, &server->nfs_client->cl_state);
 413 }
 414
 415 /**
 416  * nfs_super_return_all_delegations - return delegations for one superblock
 417  * @sb: sb to process
 418  *
 419  */
 420 void nfs_super_return_all_delegations(struct super_block *sb)
 421 {
 422         struct nfs_server *server = NFS_SB(sb);
 423         struct nfs_client *clp = server->nfs_client;
 424         struct nfs_delegation *delegation;
 425
 426         if (clp == NULL)
 427                 return;
 428
 429         rcu_read_lock();
 430         list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
 431                 spin_lock(&delegation->lock);
 432                 set_bit(NFS_DELEGATION_RETURN, &delegation->flags);
 433                 spin_unlock(&delegation->lock);
 434         }
 435         rcu_read_unlock();
 436
 437         if (nfs_client_return_marked_delegations(clp) != 0)
 438                 nfs4_schedule_state_manager(clp);
 439 }
 440
 441 static void nfs_mark_return_all_delegation_types(struct nfs_server *server,
 442                                                  fmode_t flags)
 443 {
 444         struct nfs_delegation *delegation;
 445
 446         list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
 447                 if ((delegation->type == (FMODE_READ|FMODE_WRITE)) && !(flags & FMODE_WRITE))
 448                         continue;
 449                 if (delegation->type & flags)
 450                         nfs_mark_return_delegation(server, delegation);
 451         }
 452 }
 453
 454 static void nfs_client_mark_return_all_delegation_types(struct nfs_client *clp,
 455                                                         fmode_t flags)
 456 {
 457         struct nfs_server *server;
 458
 459         rcu_read_lock();
 460         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
 461                 nfs_mark_return_all_delegation_types(server, flags);
 462         rcu_read_unlock();
 463 }
 464
 465 static void nfs_delegation_run_state_manager(struct nfs_client *clp)
 466 {
 467         if (test_bit(NFS4CLNT_DELEGRETURN, &clp->cl_state))
 468                 nfs4_schedule_state_manager(clp);
 469 }
 470
 471 void nfs_remove_bad_delegation(struct inode *inode)
 472 {
 473         struct nfs_delegation *delegation;
 474
 475         delegation = nfs_detach_delegation(NFS_I(inode), NFS_SERVER(inode));
 476         if (delegation) {
 477                 nfs_inode_find_state_and_recover(inode, &delegation->stateid);
 478                 nfs_free_delegation(delegation);
 479         }
 480 }
 481 EXPORT_SYMBOL_GPL(nfs_remove_bad_delegation);
 482
 483 /**
 484  * nfs_expire_all_delegation_types
 485  * @clp: client to process
 486  * @flags: delegation types to expire
 487  *
 488  */
 489 void nfs_expire_all_delegation_types(struct nfs_client *clp, fmode_t flags)
 490 {
 491         nfs_client_mark_return_all_delegation_types(clp, flags);
 492         nfs_delegation_run_state_manager(clp);
 493 }
 494
 495 /**
 496  * nfs_expire_all_delegations
 497  * @clp: client to process
 498  *
 499  */
 500 void nfs_expire_all_delegations(struct nfs_client *clp)
 501 {
 502         nfs_expire_all_delegation_types(clp, FMODE_READ|FMODE_WRITE);
 503 }
 504
 505 static void nfs_mark_return_unreferenced_delegations(struct nfs_server *server)
 506 {
 507         struct nfs_delegation *delegation;
 508
 509         list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
 510                 if (test_and_clear_bit(NFS_DELEGATION_REFERENCED, &delegation->flags))
 511                         continue;
 512                 nfs_mark_return_delegation(server, delegation);
 513         }
 514 }
 515
 516 /**
 517  * nfs_expire_unreferenced_delegations - Eliminate unused delegations
 518  * @clp: nfs_client to process
 519  *
 520  */
 521 void nfs_expire_unreferenced_delegations(struct nfs_client *clp)
 522 {
 523         struct nfs_server *server;
 524
 525         rcu_read_lock();
 526         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
 527                 nfs_mark_return_unreferenced_delegations(server);
 528         rcu_read_unlock();
 529
 530         nfs_delegation_run_state_manager(clp);
 531 }
 532
 533 /**
 534  * nfs_async_inode_return_delegation - asynchronously return a delegation
 535  * @inode: inode to process
 536  * @stateid: state ID information
 537  *
 538  * Returns zero on success, or a negative errno value.
 539  */
 540 int nfs_async_inode_return_delegation(struct inode *inode,
 541                                       const nfs4_stateid *stateid)
 542 {
 543         struct nfs_server *server = NFS_SERVER(inode);
 544         struct nfs_client *clp = server->nfs_client;
 545         struct nfs_delegation *delegation;
 546
 547         filemap_flush(inode->i_mapping);
 548
 549         rcu_read_lock();
 550         delegation = rcu_dereference(NFS_I(inode)->delegation);
 551
 552         if (!clp->cl_mvops->match_stateid(&delegation->stateid, stateid)) {
 553                 rcu_read_unlock();
 554                 return -ENOENT;
 555         }
 556         nfs_mark_return_delegation(server, delegation);
 557         rcu_read_unlock();
 558
 559         nfs_delegation_run_state_manager(clp);
 560         return 0;
 561 }
 562
 563 static struct inode *
 564 nfs_delegation_find_inode_server(struct nfs_server *server,
 565                                  const struct nfs_fh *fhandle)
 566 {
 567         struct nfs_delegation *delegation;
 568         struct inode *res = NULL;
 569
 570         list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
 571                 spin_lock(&delegation->lock);
 572                 if (delegation->inode != NULL &&
 573                     nfs_compare_fh(fhandle, &NFS_I(delegation->inode)->fh) == 0) {
 574                         res = igrab(delegation->inode);
 575                 }
 576                 spin_unlock(&delegation->lock);
 577                 if (res != NULL)
 578                         break;
 579         }
 580         return res;
 581 }
 582
 583 /**
 584  * nfs_delegation_find_inode - retrieve the inode associated with a delegation
 585  * @clp: client state handle
 586  * @fhandle: filehandle from a delegation recall
 587  *
 588  * Returns pointer to inode matching "fhandle," or NULL if a matching inode
 589  * cannot be found.
 590  */
 591 struct inode *nfs_delegation_find_inode(struct nfs_client *clp,
 592                                         const struct nfs_fh *fhandle)
 593 {
 594         struct nfs_server *server;
 595         struct inode *res = NULL;
 596
 597         rcu_read_lock();
 598         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link) {
 599                 res = nfs_delegation_find_inode_server(server, fhandle);
 600                 if (res != NULL)
 601                         break;
 602         }
 603         rcu_read_unlock();
 604         return res;
 605 }
 606
 607 static void nfs_delegation_mark_reclaim_server(struct nfs_server *server)
 608 {
 609         struct nfs_delegation *delegation;
 610
 611         list_for_each_entry_rcu(delegation, &server->delegations, super_list)
 612                 set_bit(NFS_DELEGATION_NEED_RECLAIM, &delegation->flags);
 613 }
 614
 615 /**
 616  * nfs_delegation_mark_reclaim - mark all delegations as needing to be reclaimed
 617  * @clp: nfs_client to process
 618  *
 619  */
 620 void nfs_delegation_mark_reclaim(struct nfs_client *clp)
 621 {
 622         struct nfs_server *server;
 623
 624         rcu_read_lock();
 625         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
 626                 nfs_delegation_mark_reclaim_server(server);
 627         rcu_read_unlock();
 628 }
 629
 630 /**
 631  * nfs_delegation_reap_unclaimed - reap unclaimed delegations after reboot recovery is done
 632  * @clp: nfs_client to process
 633  *
 634  */
 635 void nfs_delegation_reap_unclaimed(struct nfs_client *clp)
 636 {
 637         struct nfs_delegation *delegation;
 638         struct nfs_server *server;
 639         struct inode *inode;
 640
 641 restart:
 642         rcu_read_lock();
 643         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link) {
 644                 list_for_each_entry_rcu(delegation, &server->delegations,
 645                                                                 super_list) {
 646                         if (test_bit(NFS_DELEGATION_NEED_RECLAIM,
 647                                                 &delegation->flags) == 0)
 648                                 continue;
 649                         inode = nfs_delegation_grab_inode(delegation);
 650                         if (inode == NULL)
 651                                 continue;
 652                         delegation = nfs_detach_delegation(NFS_I(inode),
 653                                                                 server);
 654                         rcu_read_unlock();
 655
 656                         if (delegation != NULL)
 657                                 nfs_free_delegation(delegation);
 658                         iput(inode);
 659                         goto restart;
 660                 }
 661         }
 662         rcu_read_unlock();
 663 }
 664
 665 /**
 666  * nfs_delegations_present - check for existence of delegations
 667  * @clp: client state handle
 668  *
 669  * Returns one if there are any nfs_delegation structures attached
 670  * to this nfs_client.
 671  */
 672 int nfs_delegations_present(struct nfs_client *clp)
 673 {
 674         struct nfs_server *server;
 675         int ret = 0;
 676
 677         rcu_read_lock();
 678         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
 679                 if (!list_empty(&server->delegations)) {
 680                         ret = 1;
 681                         break;
 682                 }
 683         rcu_read_unlock();
 684         return ret;
 685 }
 686
 687 /**
 688  * nfs4_copy_delegation_stateid - Copy inode's state ID information
 689  * @dst: stateid data structure to fill in
 690  * @inode: inode to check
 691  * @flags: delegation type requirement
 692  *
 693  * Returns "true" and fills in "dst->data" * if inode had a delegation,
 694  * otherwise "false" is returned.
 695  */
 696 bool nfs4_copy_delegation_stateid(nfs4_stateid *dst, struct inode *inode,
 697                 fmode_t flags)
 698 {
 699         struct nfs_inode *nfsi = NFS_I(inode);
 700         struct nfs_delegation *delegation;
 701         bool ret;
 702
 703         flags &= FMODE_READ|FMODE_WRITE;
 704         rcu_read_lock();
 705         delegation = rcu_dereference(nfsi->delegation);
 706         ret = (delegation != NULL && (delegation->type & flags) == flags);
 707         if (ret) {
 708                 nfs4_stateid_copy(dst, &delegation->stateid);
 709                 nfs_mark_delegation_referenced(delegation);
 710         }
 711         rcu_read_unlock();
 712         return ret;
 713 }