fs/nfs/delegation.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * linux/fs/nfs/delegation.c
   4  *
   5  * Copyright (C) 2004 Trond Myklebust
   6  *
   7  * NFS file delegation management
   8  *
   9  */
  10 #include <linux/completion.h>
  11 #include <linux/kthread.h>
  12 #include <linux/module.h>
  13 #include <linux/sched.h>
  14 #include <linux/slab.h>
  15 #include <linux/spinlock.h>
  16 #include <linux/iversion.h>
  17
  18 #include <linux/nfs4.h>
  19 #include <linux/nfs_fs.h>
  20 #include <linux/nfs_xdr.h>
  21
  22 #include "nfs4_fs.h"
  23 #include "nfs4session.h"
  24 #include "delegation.h"
  25 #include "internal.h"
  26 #include "nfs4trace.h"
  27
  28 static void nfs_free_delegation(struct nfs_delegation *delegation)
  29 {
  30         put_cred(delegation->cred);
  31         delegation->cred = NULL;
  32         kfree_rcu(delegation, rcu);
  33 }
  34
  35 /**
  36  * nfs_mark_delegation_referenced - set delegation's REFERENCED flag
  37  * @delegation: delegation to process
  38  *
  39  */
  40 void nfs_mark_delegation_referenced(struct nfs_delegation *delegation)
  41 {
  42         set_bit(NFS_DELEGATION_REFERENCED, &delegation->flags);
  43 }
  44
  45 static bool
  46 nfs4_is_valid_delegation(const struct nfs_delegation *delegation,
  47                 fmode_t flags)
  48 {
  49         if (delegation != NULL && (delegation->type & flags) == flags &&
  50             !test_bit(NFS_DELEGATION_REVOKED, &delegation->flags) &&
  51             !test_bit(NFS_DELEGATION_RETURNING, &delegation->flags))
  52                 return true;
  53         return false;
  54 }
  55
  56 struct nfs_delegation *nfs4_get_valid_delegation(const struct inode *inode)
  57 {
  58         struct nfs_delegation *delegation;
  59
  60         delegation = rcu_dereference(NFS_I(inode)->delegation);
  61         if (nfs4_is_valid_delegation(delegation, 0))
  62                 return delegation;
  63         return NULL;
  64 }
  65
  66 static int
  67 nfs4_do_check_delegation(struct inode *inode, fmode_t flags, bool mark)
  68 {
  69         struct nfs_delegation *delegation;
  70         int ret = 0;
  71
  72         flags &= FMODE_READ|FMODE_WRITE;
  73         rcu_read_lock();
  74         delegation = rcu_dereference(NFS_I(inode)->delegation);
  75         if (nfs4_is_valid_delegation(delegation, flags)) {
  76                 if (mark)
  77                         nfs_mark_delegation_referenced(delegation);
  78                 ret = 1;
  79         }
  80         rcu_read_unlock();
  81         return ret;
  82 }
  83 /**
  84  * nfs_have_delegation - check if inode has a delegation, mark it
  85  * NFS_DELEGATION_REFERENCED if there is one.
  86  * @inode: inode to check
  87  * @flags: delegation types to check for
  88  *
  89  * Returns one if inode has the indicated delegation, otherwise zero.
  90  */
  91 int nfs4_have_delegation(struct inode *inode, fmode_t flags)
  92 {
  93         return nfs4_do_check_delegation(inode, flags, true);
  94 }
  95
  96 /*
  97  * nfs4_check_delegation - check if inode has a delegation, do not mark
  98  * NFS_DELEGATION_REFERENCED if it has one.
  99  */
 100 int nfs4_check_delegation(struct inode *inode, fmode_t flags)
 101 {
 102         return nfs4_do_check_delegation(inode, flags, false);
 103 }
 104
 105 static int nfs_delegation_claim_locks(struct nfs4_state *state, const nfs4_stateid *stateid)
 106 {
 107         struct inode *inode = state->inode;
 108         struct file_lock *fl;
 109         struct file_lock_context *flctx = inode->i_flctx;
 110         struct list_head *list;
 111         int status = 0;
 112
 113         if (flctx == NULL)
 114                 goto out;
 115
 116         list = &flctx->flc_posix;
 117         spin_lock(&flctx->flc_lock);
 118 restart:
 119         list_for_each_entry(fl, list, fl_list) {
 120                 if (nfs_file_open_context(fl->fl_file)->state != state)
 121                         continue;
 122                 spin_unlock(&flctx->flc_lock);
 123                 status = nfs4_lock_delegation_recall(fl, state, stateid);
 124                 if (status < 0)
 125                         goto out;
 126                 spin_lock(&flctx->flc_lock);
 127         }
 128         if (list == &flctx->flc_posix) {
 129                 list = &flctx->flc_flock;
 130                 goto restart;
 131         }
 132         spin_unlock(&flctx->flc_lock);
 133 out:
 134         return status;
 135 }
 136
 137 static int nfs_delegation_claim_opens(struct inode *inode,
 138                 const nfs4_stateid *stateid, fmode_t type)
 139 {
 140         struct nfs_inode *nfsi = NFS_I(inode);
 141         struct nfs_open_context *ctx;
 142         struct nfs4_state_owner *sp;
 143         struct nfs4_state *state;
 144         unsigned int seq;
 145         int err;
 146
 147 again:
 148         rcu_read_lock();
 149         list_for_each_entry_rcu(ctx, &nfsi->open_files, list) {
 150                 state = ctx->state;
 151                 if (state == NULL)
 152                         continue;
 153                 if (!test_bit(NFS_DELEGATED_STATE, &state->flags))
 154                         continue;
 155                 if (!nfs4_valid_open_stateid(state))
 156                         continue;
 157                 if (!nfs4_stateid_match(&state->stateid, stateid))
 158                         continue;
 159                 if (!get_nfs_open_context(ctx))
 160                         continue;
 161                 rcu_read_unlock();
 162                 sp = state->owner;
 163                 /* Block nfs4_proc_unlck */
 164                 mutex_lock(&sp->so_delegreturn_mutex);
 165                 seq = raw_seqcount_begin(&sp->so_reclaim_seqcount);
 166                 err = nfs4_open_delegation_recall(ctx, state, stateid);
 167                 if (!err)
 168                         err = nfs_delegation_claim_locks(state, stateid);
 169                 if (!err && read_seqcount_retry(&sp->so_reclaim_seqcount, seq))
 170                         err = -EAGAIN;
 171                 mutex_unlock(&sp->so_delegreturn_mutex);
 172                 put_nfs_open_context(ctx);
 173                 if (err != 0)
 174                         return err;
 175                 goto again;
 176         }
 177         rcu_read_unlock();
 178         return 0;
 179 }
 180
 181 /**
 182  * nfs_inode_reclaim_delegation - process a delegation reclaim request
 183  * @inode: inode to process
 184  * @cred: credential to use for request
 185  * @type: delegation type
 186  * @stateid: delegation stateid
 187  * @pagemod_limit: write delegation "space_limit"
 188  *
 189  */
 190 void nfs_inode_reclaim_delegation(struct inode *inode, const struct cred *cred,
 191                                   fmode_t type,
 192                                   const nfs4_stateid *stateid,
 193                                   unsigned long pagemod_limit)
 194 {
 195         struct nfs_delegation *delegation;
 196         const struct cred *oldcred = NULL;
 197
 198         rcu_read_lock();
 199         delegation = rcu_dereference(NFS_I(inode)->delegation);
 200         if (delegation != NULL) {
 201                 spin_lock(&delegation->lock);
 202                 if (delegation->inode != NULL) {
 203                         nfs4_stateid_copy(&delegation->stateid, stateid);
 204                         delegation->type = type;
 205                         delegation->pagemod_limit = pagemod_limit;
 206                         oldcred = delegation->cred;
 207                         delegation->cred = get_cred(cred);
 208                         clear_bit(NFS_DELEGATION_NEED_RECLAIM,
 209                                   &delegation->flags);
 210                         spin_unlock(&delegation->lock);
 211                         rcu_read_unlock();
 212                         put_cred(oldcred);
 213                         trace_nfs4_reclaim_delegation(inode, type);
 214                         return;
 215                 }
 216                 /* We appear to have raced with a delegation return. */
 217                 spin_unlock(&delegation->lock);
 218         }
 219         rcu_read_unlock();
 220         nfs_inode_set_delegation(inode, cred, type, stateid, pagemod_limit);
 221 }
 222
 223 static int nfs_do_return_delegation(struct inode *inode, struct nfs_delegation *delegation, int issync)
 224 {
 225         int res = 0;
 226
 227         if (!test_bit(NFS_DELEGATION_REVOKED, &delegation->flags))
 228                 res = nfs4_proc_delegreturn(inode,
 229                                 delegation->cred,
 230                                 &delegation->stateid,
 231                                 issync);
 232         nfs_free_delegation(delegation);
 233         return res;
 234 }
 235
 236 static struct inode *nfs_delegation_grab_inode(struct nfs_delegation *delegation)
 237 {
 238         struct inode *inode = NULL;
 239
 240         spin_lock(&delegation->lock);
 241         if (delegation->inode != NULL)
 242                 inode = igrab(delegation->inode);
 243         if (!inode)
 244                 set_bit(NFS_DELEGATION_INODE_FREEING, &delegation->flags);
 245         spin_unlock(&delegation->lock);
 246         return inode;
 247 }
 248
 249 static struct nfs_delegation *
 250 nfs_start_delegation_return_locked(struct nfs_inode *nfsi)
 251 {
 252         struct nfs_delegation *ret = NULL;
 253         struct nfs_delegation *delegation = rcu_dereference(nfsi->delegation);
 254
 255         if (delegation == NULL)
 256                 goto out;
 257         spin_lock(&delegation->lock);
 258         if (!test_and_set_bit(NFS_DELEGATION_RETURNING, &delegation->flags))
 259                 ret = delegation;
 260         spin_unlock(&delegation->lock);
 261 out:
 262         return ret;
 263 }
 264
 265 static struct nfs_delegation *
 266 nfs_start_delegation_return(struct nfs_inode *nfsi)
 267 {
 268         struct nfs_delegation *delegation;
 269
 270         rcu_read_lock();
 271         delegation = nfs_start_delegation_return_locked(nfsi);
 272         rcu_read_unlock();
 273         return delegation;
 274 }
 275
 276 static void
 277 nfs_abort_delegation_return(struct nfs_delegation *delegation,
 278                 struct nfs_client *clp)
 279 {
 280
 281         spin_lock(&delegation->lock);
 282         clear_bit(NFS_DELEGATION_RETURNING, &delegation->flags);
 283         set_bit(NFS_DELEGATION_RETURN, &delegation->flags);
 284         spin_unlock(&delegation->lock);
 285         set_bit(NFS4CLNT_DELEGRETURN, &clp->cl_state);
 286 }
 287
 288 static struct nfs_delegation *
 289 nfs_detach_delegation_locked(struct nfs_inode *nfsi,
 290                 struct nfs_delegation *delegation,
 291                 struct nfs_client *clp)
 292 {
 293         struct nfs_delegation *deleg_cur =
 294                 rcu_dereference_protected(nfsi->delegation,
 295                                 lockdep_is_held(&clp->cl_lock));
 296
 297         if (deleg_cur == NULL || delegation != deleg_cur)
 298                 return NULL;
 299
 300         spin_lock(&delegation->lock);
 301         if (!delegation->inode) {
 302                 spin_unlock(&delegation->lock);
 303                 return NULL;
 304         }
 305         set_bit(NFS_DELEGATION_RETURNING, &delegation->flags);
 306         list_del_rcu(&delegation->super_list);
 307         delegation->inode = NULL;
 308         rcu_assign_pointer(nfsi->delegation, NULL);
 309         spin_unlock(&delegation->lock);
 310         return delegation;
 311 }
 312
 313 static struct nfs_delegation *nfs_detach_delegation(struct nfs_inode *nfsi,
 314                 struct nfs_delegation *delegation,
 315                 struct nfs_server *server)
 316 {
 317         struct nfs_client *clp = server->nfs_client;
 318
 319         spin_lock(&clp->cl_lock);
 320         delegation = nfs_detach_delegation_locked(nfsi, delegation, clp);
 321         spin_unlock(&clp->cl_lock);
 322         return delegation;
 323 }
 324
 325 static struct nfs_delegation *
 326 nfs_inode_detach_delegation(struct inode *inode)
 327 {
 328         struct nfs_inode *nfsi = NFS_I(inode);
 329         struct nfs_server *server = NFS_SERVER(inode);
 330         struct nfs_delegation *delegation;
 331
 332         delegation = nfs_start_delegation_return(nfsi);
 333         if (delegation == NULL)
 334                 return NULL;
 335         return nfs_detach_delegation(nfsi, delegation, server);
 336 }
 337
 338 static void
 339 nfs_update_inplace_delegation(struct nfs_delegation *delegation,
 340                 const struct nfs_delegation *update)
 341 {
 342         if (nfs4_stateid_is_newer(&update->stateid, &delegation->stateid)) {
 343                 delegation->stateid.seqid = update->stateid.seqid;
 344                 smp_wmb();
 345                 delegation->type = update->type;
 346                 clear_bit(NFS_DELEGATION_REVOKED, &delegation->flags);
 347         }
 348 }
 349
 350 /**
 351  * nfs_inode_set_delegation - set up a delegation on an inode
 352  * @inode: inode to which delegation applies
 353  * @cred: cred to use for subsequent delegation processing
 354  * @type: delegation type
 355  * @stateid: delegation stateid
 356  * @pagemod_limit: write delegation "space_limit"
 357  *
 358  * Returns zero on success, or a negative errno value.
 359  */
 360 int nfs_inode_set_delegation(struct inode *inode, const struct cred *cred,
 361                                   fmode_t type,
 362                                   const nfs4_stateid *stateid,
 363                                   unsigned long pagemod_limit)
 364 {
 365         struct nfs_server *server = NFS_SERVER(inode);
 366         struct nfs_client *clp = server->nfs_client;
 367         struct nfs_inode *nfsi = NFS_I(inode);
 368         struct nfs_delegation *delegation, *old_delegation;
 369         struct nfs_delegation *freeme = NULL;
 370         int status = 0;
 371
 372         delegation = kmalloc(sizeof(*delegation), GFP_NOFS);
 373         if (delegation == NULL)
 374                 return -ENOMEM;
 375         nfs4_stateid_copy(&delegation->stateid, stateid);
 376         delegation->type = type;
 377         delegation->pagemod_limit = pagemod_limit;
 378         delegation->change_attr = inode_peek_iversion_raw(inode);
 379         delegation->cred = get_cred(cred);
 380         delegation->inode = inode;
 381         delegation->flags = 1<<NFS_DELEGATION_REFERENCED;
 382         spin_lock_init(&delegation->lock);
 383
 384         spin_lock(&clp->cl_lock);
 385         old_delegation = rcu_dereference_protected(nfsi->delegation,
 386                                         lockdep_is_held(&clp->cl_lock));
 387         if (old_delegation != NULL) {
 388                 /* Is this an update of the existing delegation? */
 389                 if (nfs4_stateid_match_other(&old_delegation->stateid,
 390                                         &delegation->stateid)) {
 391                         spin_lock(&old_delegation->lock);
 392                         nfs_update_inplace_delegation(old_delegation,
 393                                         delegation);
 394                         spin_unlock(&old_delegation->lock);
 395                         goto out;
 396                 }
 397                 /*
 398                  * Deal with broken servers that hand out two
 399                  * delegations for the same file.
 400                  * Allow for upgrades to a WRITE delegation, but
 401                  * nothing else.
 402                  */
 403                 dfprintk(FILE, "%s: server %s handed out "
 404                                 "a duplicate delegation!\n",
 405                                 __func__, clp->cl_hostname);
 406                 if (delegation->type == old_delegation->type ||
 407                     !(delegation->type & FMODE_WRITE)) {
 408                         freeme = delegation;
 409                         delegation = NULL;
 410                         goto out;
 411                 }
 412                 if (test_and_set_bit(NFS_DELEGATION_RETURNING,
 413                                         &old_delegation->flags))
 414                         goto out;
 415                 freeme = nfs_detach_delegation_locked(nfsi,
 416                                 old_delegation, clp);
 417                 if (freeme == NULL)
 418                         goto out;
 419         }
 420         list_add_tail_rcu(&delegation->super_list, &server->delegations);
 421         rcu_assign_pointer(nfsi->delegation, delegation);
 422         delegation = NULL;
 423
 424         trace_nfs4_set_delegation(inode, type);
 425
 426         spin_lock(&inode->i_lock);
 427         if (NFS_I(inode)->cache_validity & (NFS_INO_INVALID_ATTR|NFS_INO_INVALID_ATIME))
 428                 NFS_I(inode)->cache_validity |= NFS_INO_REVAL_FORCED;
 429         spin_unlock(&inode->i_lock);
 430 out:
 431         spin_unlock(&clp->cl_lock);
 432         if (delegation != NULL)
 433                 nfs_free_delegation(delegation);
 434         if (freeme != NULL)
 435                 nfs_do_return_delegation(inode, freeme, 0);
 436         return status;
 437 }
 438
 439 /*
 440  * Basic procedure for returning a delegation to the server
 441  */
 442 static int nfs_end_delegation_return(struct inode *inode, struct nfs_delegation *delegation, int issync)
 443 {
 444         struct nfs_client *clp = NFS_SERVER(inode)->nfs_client;
 445         struct nfs_inode *nfsi = NFS_I(inode);
 446         int err = 0;
 447
 448         if (delegation == NULL)
 449                 return 0;
 450         do {
 451                 if (test_bit(NFS_DELEGATION_REVOKED, &delegation->flags))
 452                         break;
 453                 err = nfs_delegation_claim_opens(inode, &delegation->stateid,
 454                                 delegation->type);
 455                 if (!issync || err != -EAGAIN)
 456                         break;
 457                 /*
 458                  * Guard against state recovery
 459                  */
 460                 err = nfs4_wait_clnt_recover(clp);
 461         } while (err == 0);
 462
 463         if (err) {
 464                 nfs_abort_delegation_return(delegation, clp);
 465                 goto out;
 466         }
 467         if (!nfs_detach_delegation(nfsi, delegation, NFS_SERVER(inode)))
 468                 goto out;
 469
 470         err = nfs_do_return_delegation(inode, delegation, issync);
 471 out:
 472         return err;
 473 }
 474
 475 static bool nfs_delegation_need_return(struct nfs_delegation *delegation)
 476 {
 477         bool ret = false;
 478
 479         if (test_and_clear_bit(NFS_DELEGATION_RETURN, &delegation->flags))
 480                 ret = true;
 481         if (test_and_clear_bit(NFS_DELEGATION_RETURN_IF_CLOSED, &delegation->flags) && !ret) {
 482                 struct inode *inode;
 483
 484                 spin_lock(&delegation->lock);
 485                 inode = delegation->inode;
 486                 if (inode && list_empty(&NFS_I(inode)->open_files))
 487                         ret = true;
 488                 spin_unlock(&delegation->lock);
 489         }
 490         if (test_bit(NFS_DELEGATION_RETURNING, &delegation->flags) ||
 491             test_bit(NFS_DELEGATION_REVOKED, &delegation->flags))
 492                 ret = false;
 493
 494         return ret;
 495 }
 496
 497 /**
 498  * nfs_client_return_marked_delegations - return previously marked delegations
 499  * @clp: nfs_client to process
 500  *
 501  * Note that this function is designed to be called by the state
 502  * manager thread. For this reason, it cannot flush the dirty data,
 503  * since that could deadlock in case of a state recovery error.
 504  *
 505  * Returns zero on success, or a negative errno value.
 506  */
 507 int nfs_client_return_marked_delegations(struct nfs_client *clp)
 508 {
 509         struct nfs_delegation *delegation;
 510         struct nfs_delegation *prev;
 511         struct nfs_server *server;
 512         struct inode *inode;
 513         struct inode *place_holder = NULL;
 514         struct nfs_delegation *place_holder_deleg = NULL;
 515         int err = 0;
 516
 517 restart:
 518         /*
 519          * To avoid quadratic looping we hold a reference
 520          * to an inode place_holder.  Each time we restart, we
 521          * list nfs_servers from the server of that inode, and
 522          * delegation in the server from the delegations of that
 523          * inode.
 524          * prev is an RCU-protected pointer to a delegation which
 525          * wasn't marked for return and might be a good choice for
 526          * the next place_holder.
 527          */
 528         rcu_read_lock();
 529         prev = NULL;
 530         if (place_holder)
 531                 server = NFS_SERVER(place_holder);
 532         else
 533                 server = list_entry_rcu(clp->cl_superblocks.next,
 534                                         struct nfs_server, client_link);
 535         list_for_each_entry_from_rcu(server, &clp->cl_superblocks, client_link) {
 536                 delegation = NULL;
 537                 if (place_holder && server == NFS_SERVER(place_holder))
 538                         delegation = rcu_dereference(NFS_I(place_holder)->delegation);
 539                 if (!delegation || delegation != place_holder_deleg)
 540                         delegation = list_entry_rcu(server->delegations.next,
 541                                                     struct nfs_delegation, super_list);
 542                 list_for_each_entry_from_rcu(delegation, &server->delegations, super_list) {
 543                         struct inode *to_put = NULL;
 544
 545                         if (!nfs_delegation_need_return(delegation)) {
 546                                 prev = delegation;
 547                                 continue;
 548                         }
 549                         if (!nfs_sb_active(server->super))
 550                                 break; /* continue in outer loop */
 551
 552                         if (prev) {
 553                                 struct inode *tmp;
 554
 555                                 tmp = nfs_delegation_grab_inode(prev);
 556                                 if (tmp) {
 557                                         to_put = place_holder;
 558                                         place_holder = tmp;
 559                                         place_holder_deleg = prev;
 560                                 }
 561                         }
 562
 563                         inode = nfs_delegation_grab_inode(delegation);
 564                         if (inode == NULL) {
 565                                 rcu_read_unlock();
 566                                 if (to_put)
 567                                         iput(to_put);
 568                                 nfs_sb_deactive(server->super);
 569                                 goto restart;
 570                         }
 571                         delegation = nfs_start_delegation_return_locked(NFS_I(inode));
 572                         rcu_read_unlock();
 573
 574                         if (to_put)
 575                                 iput(to_put);
 576
 577                         err = nfs_end_delegation_return(inode, delegation, 0);
 578                         iput(inode);
 579                         nfs_sb_deactive(server->super);
 580                         cond_resched();
 581                         if (!err)
 582                                 goto restart;
 583                         set_bit(NFS4CLNT_DELEGRETURN, &clp->cl_state);
 584                         if (place_holder)
 585                                 iput(place_holder);
 586                         return err;
 587                 }
 588         }
 589         rcu_read_unlock();
 590         if (place_holder)
 591                 iput(place_holder);
 592         return 0;
 593 }
 594
 595 /**
 596  * nfs_inode_evict_delegation - return delegation, don't reclaim opens
 597  * @inode: inode to process
 598  *
 599  * Does not protect against delegation reclaims, therefore really only safe
 600  * to be called from nfs4_clear_inode(). Guaranteed to always free
 601  * the delegation structure.
 602  */
 603 void nfs_inode_evict_delegation(struct inode *inode)
 604 {
 605         struct nfs_delegation *delegation;
 606
 607         delegation = nfs_inode_detach_delegation(inode);
 608         if (delegation != NULL) {
 609                 set_bit(NFS_DELEGATION_INODE_FREEING, &delegation->flags);
 610                 nfs_do_return_delegation(inode, delegation, 1);
 611         }
 612 }
 613
 614 /**
 615  * nfs_inode_return_delegation - synchronously return a delegation
 616  * @inode: inode to process
 617  *
 618  * This routine will always flush any dirty data to disk on the
 619  * assumption that if we need to return the delegation, then
 620  * we should stop caching.
 621  *
 622  * Returns zero on success, or a negative errno value.
 623  */
 624 int nfs4_inode_return_delegation(struct inode *inode)
 625 {
 626         struct nfs_inode *nfsi = NFS_I(inode);
 627         struct nfs_delegation *delegation;
 628         int err = 0;
 629
 630         nfs_wb_all(inode);
 631         delegation = nfs_start_delegation_return(nfsi);
 632         if (delegation != NULL)
 633                 err = nfs_end_delegation_return(inode, delegation, 1);
 634         return err;
 635 }
 636
 637 /**
 638  * nfs4_inode_make_writeable
 639  * @inode: pointer to inode
 640  *
 641  * Make the inode writeable by returning the delegation if necessary
 642  *
 643  * Returns zero on success, or a negative errno value.
 644  */
 645 int nfs4_inode_make_writeable(struct inode *inode)
 646 {
 647         if (!nfs4_has_session(NFS_SERVER(inode)->nfs_client) ||
 648             !nfs4_check_delegation(inode, FMODE_WRITE))
 649                 return nfs4_inode_return_delegation(inode);
 650         return 0;
 651 }
 652
 653 static void nfs_mark_return_if_closed_delegation(struct nfs_server *server,
 654                 struct nfs_delegation *delegation)
 655 {
 656         set_bit(NFS_DELEGATION_RETURN_IF_CLOSED, &delegation->flags);
 657         set_bit(NFS4CLNT_DELEGRETURN, &server->nfs_client->cl_state);
 658 }
 659
 660 static void nfs_mark_return_delegation(struct nfs_server *server,
 661                 struct nfs_delegation *delegation)
 662 {
 663         set_bit(NFS_DELEGATION_RETURN, &delegation->flags);
 664         set_bit(NFS4CLNT_DELEGRETURN, &server->nfs_client->cl_state);
 665 }
 666
 667 static bool nfs_server_mark_return_all_delegations(struct nfs_server *server)
 668 {
 669         struct nfs_delegation *delegation;
 670         bool ret = false;
 671
 672         list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
 673                 nfs_mark_return_delegation(server, delegation);
 674                 ret = true;
 675         }
 676         return ret;
 677 }
 678
 679 static void nfs_client_mark_return_all_delegations(struct nfs_client *clp)
 680 {
 681         struct nfs_server *server;
 682
 683         rcu_read_lock();
 684         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
 685                 nfs_server_mark_return_all_delegations(server);
 686         rcu_read_unlock();
 687 }
 688
 689 static void nfs_delegation_run_state_manager(struct nfs_client *clp)
 690 {
 691         if (test_bit(NFS4CLNT_DELEGRETURN, &clp->cl_state))
 692                 nfs4_schedule_state_manager(clp);
 693 }
 694
 695 /**
 696  * nfs_expire_all_delegations
 697  * @clp: client to process
 698  *
 699  */
 700 void nfs_expire_all_delegations(struct nfs_client *clp)
 701 {
 702         nfs_client_mark_return_all_delegations(clp);
 703         nfs_delegation_run_state_manager(clp);
 704 }
 705
 706 /**
 707  * nfs_super_return_all_delegations - return delegations for one superblock
 708  * @server: pointer to nfs_server to process
 709  *
 710  */
 711 void nfs_server_return_all_delegations(struct nfs_server *server)
 712 {
 713         struct nfs_client *clp = server->nfs_client;
 714         bool need_wait;
 715
 716         if (clp == NULL)
 717                 return;
 718
 719         rcu_read_lock();
 720         need_wait = nfs_server_mark_return_all_delegations(server);
 721         rcu_read_unlock();
 722
 723         if (need_wait) {
 724                 nfs4_schedule_state_manager(clp);
 725                 nfs4_wait_clnt_recover(clp);
 726         }
 727 }
 728
 729 static void nfs_mark_return_unused_delegation_types(struct nfs_server *server,
 730                                                  fmode_t flags)
 731 {
 732         struct nfs_delegation *delegation;
 733
 734         list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
 735                 if ((delegation->type == (FMODE_READ|FMODE_WRITE)) && !(flags & FMODE_WRITE))
 736                         continue;
 737                 if (delegation->type & flags)
 738                         nfs_mark_return_if_closed_delegation(server, delegation);
 739         }
 740 }
 741
 742 static void nfs_client_mark_return_unused_delegation_types(struct nfs_client *clp,
 743                                                         fmode_t flags)
 744 {
 745         struct nfs_server *server;
 746
 747         rcu_read_lock();
 748         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
 749                 nfs_mark_return_unused_delegation_types(server, flags);
 750         rcu_read_unlock();
 751 }
 752
 753 static void nfs_mark_delegation_revoked(struct nfs_server *server,
 754                 struct nfs_delegation *delegation)
 755 {
 756         set_bit(NFS_DELEGATION_REVOKED, &delegation->flags);
 757         delegation->stateid.type = NFS4_INVALID_STATEID_TYPE;
 758         nfs_mark_return_delegation(server, delegation);
 759 }
 760
 761 static bool nfs_revoke_delegation(struct inode *inode,
 762                 const nfs4_stateid *stateid)
 763 {
 764         struct nfs_delegation *delegation;
 765         nfs4_stateid tmp;
 766         bool ret = false;
 767
 768         rcu_read_lock();
 769         delegation = rcu_dereference(NFS_I(inode)->delegation);
 770         if (delegation == NULL)
 771                 goto out;
 772         if (stateid == NULL) {
 773                 nfs4_stateid_copy(&tmp, &delegation->stateid);
 774                 stateid = &tmp;
 775         } else {
 776                 if (!nfs4_stateid_match_other(stateid, &delegation->stateid))
 777                         goto out;
 778                 spin_lock(&delegation->lock);
 779                 if (stateid->seqid) {
 780                         if (nfs4_stateid_is_newer(&delegation->stateid, stateid)) {
 781                                 spin_unlock(&delegation->lock);
 782                                 goto out;
 783                         }
 784                         delegation->stateid.seqid = stateid->seqid;
 785                 }
 786                 spin_unlock(&delegation->lock);
 787         }
 788         nfs_mark_delegation_revoked(NFS_SERVER(inode), delegation);
 789         ret = true;
 790 out:
 791         rcu_read_unlock();
 792         if (ret)
 793                 nfs_inode_find_state_and_recover(inode, stateid);
 794         return ret;
 795 }
 796
 797 void nfs_remove_bad_delegation(struct inode *inode,
 798                 const nfs4_stateid *stateid)
 799 {
 800         struct nfs_delegation *delegation;
 801
 802         if (!nfs_revoke_delegation(inode, stateid))
 803                 return;
 804         delegation = nfs_inode_detach_delegation(inode);
 805         if (delegation)
 806                 nfs_free_delegation(delegation);
 807 }
 808 EXPORT_SYMBOL_GPL(nfs_remove_bad_delegation);
 809
 810 void nfs_delegation_mark_returned(struct inode *inode,
 811                 const nfs4_stateid *stateid)
 812 {
 813         struct nfs_delegation *delegation;
 814
 815         if (!inode)
 816                 return;
 817
 818         rcu_read_lock();
 819         delegation = rcu_dereference(NFS_I(inode)->delegation);
 820         if (!delegation)
 821                 goto out_rcu_unlock;
 822
 823         spin_lock(&delegation->lock);
 824         if (!nfs4_stateid_match_other(stateid, &delegation->stateid))
 825                 goto out_spin_unlock;
 826         if (stateid->seqid) {
 827                 /* If delegation->stateid is newer, dont mark as returned */
 828                 if (nfs4_stateid_is_newer(&delegation->stateid, stateid))
 829                         goto out_clear_returning;
 830                 if (delegation->stateid.seqid != stateid->seqid)
 831                         delegation->stateid.seqid = stateid->seqid;
 832         }
 833
 834         set_bit(NFS_DELEGATION_REVOKED, &delegation->flags);
 835
 836 out_clear_returning:
 837         clear_bit(NFS_DELEGATION_RETURNING, &delegation->flags);
 838 out_spin_unlock:
 839         spin_unlock(&delegation->lock);
 840 out_rcu_unlock:
 841         rcu_read_unlock();
 842
 843         nfs_inode_find_state_and_recover(inode, stateid);
 844 }
 845
 846 /**
 847  * nfs_expire_unused_delegation_types
 848  * @clp: client to process
 849  * @flags: delegation types to expire
 850  *
 851  */
 852 void nfs_expire_unused_delegation_types(struct nfs_client *clp, fmode_t flags)
 853 {
 854         nfs_client_mark_return_unused_delegation_types(clp, flags);
 855         nfs_delegation_run_state_manager(clp);
 856 }
 857
 858 static void nfs_mark_return_unreferenced_delegations(struct nfs_server *server)
 859 {
 860         struct nfs_delegation *delegation;
 861
 862         list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
 863                 if (test_and_clear_bit(NFS_DELEGATION_REFERENCED, &delegation->flags))
 864                         continue;
 865                 nfs_mark_return_if_closed_delegation(server, delegation);
 866         }
 867 }
 868
 869 /**
 870  * nfs_expire_unreferenced_delegations - Eliminate unused delegations
 871  * @clp: nfs_client to process
 872  *
 873  */
 874 void nfs_expire_unreferenced_delegations(struct nfs_client *clp)
 875 {
 876         struct nfs_server *server;
 877
 878         rcu_read_lock();
 879         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
 880                 nfs_mark_return_unreferenced_delegations(server);
 881         rcu_read_unlock();
 882
 883         nfs_delegation_run_state_manager(clp);
 884 }
 885
 886 /**
 887  * nfs_async_inode_return_delegation - asynchronously return a delegation
 888  * @inode: inode to process
 889  * @stateid: state ID information
 890  *
 891  * Returns zero on success, or a negative errno value.
 892  */
 893 int nfs_async_inode_return_delegation(struct inode *inode,
 894                                       const nfs4_stateid *stateid)
 895 {
 896         struct nfs_server *server = NFS_SERVER(inode);
 897         struct nfs_client *clp = server->nfs_client;
 898         struct nfs_delegation *delegation;
 899
 900         rcu_read_lock();
 901         delegation = nfs4_get_valid_delegation(inode);
 902         if (delegation == NULL)
 903                 goto out_enoent;
 904         if (stateid != NULL &&
 905             !clp->cl_mvops->match_stateid(&delegation->stateid, stateid))
 906                 goto out_enoent;
 907         nfs_mark_return_delegation(server, delegation);
 908         rcu_read_unlock();
 909
 910         nfs_delegation_run_state_manager(clp);
 911         return 0;
 912 out_enoent:
 913         rcu_read_unlock();
 914         return -ENOENT;
 915 }
 916
 917 static struct inode *
 918 nfs_delegation_find_inode_server(struct nfs_server *server,
 919                                  const struct nfs_fh *fhandle)
 920 {
 921         struct nfs_delegation *delegation;
 922         struct inode *freeme, *res = NULL;
 923
 924         list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
 925                 spin_lock(&delegation->lock);
 926                 if (delegation->inode != NULL &&
 927                     !test_bit(NFS_DELEGATION_REVOKED, &delegation->flags) &&
 928                     nfs_compare_fh(fhandle, &NFS_I(delegation->inode)->fh) == 0) {
 929                         freeme = igrab(delegation->inode);
 930                         if (freeme && nfs_sb_active(freeme->i_sb))
 931                                 res = freeme;
 932                         spin_unlock(&delegation->lock);
 933                         if (res != NULL)
 934                                 return res;
 935                         if (freeme) {
 936                                 rcu_read_unlock();
 937                                 iput(freeme);
 938                                 rcu_read_lock();
 939                         }
 940                         return ERR_PTR(-EAGAIN);
 941                 }
 942                 spin_unlock(&delegation->lock);
 943         }
 944         return ERR_PTR(-ENOENT);
 945 }
 946
 947 /**
 948  * nfs_delegation_find_inode - retrieve the inode associated with a delegation
 949  * @clp: client state handle
 950  * @fhandle: filehandle from a delegation recall
 951  *
 952  * Returns pointer to inode matching "fhandle," or NULL if a matching inode
 953  * cannot be found.
 954  */
 955 struct inode *nfs_delegation_find_inode(struct nfs_client *clp,
 956                                         const struct nfs_fh *fhandle)
 957 {
 958         struct nfs_server *server;
 959         struct inode *res;
 960
 961         rcu_read_lock();
 962         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link) {
 963                 res = nfs_delegation_find_inode_server(server, fhandle);
 964                 if (res != ERR_PTR(-ENOENT)) {
 965                         rcu_read_unlock();
 966                         return res;
 967                 }
 968         }
 969         rcu_read_unlock();
 970         return ERR_PTR(-ENOENT);
 971 }
 972
 973 static void nfs_delegation_mark_reclaim_server(struct nfs_server *server)
 974 {
 975         struct nfs_delegation *delegation;
 976
 977         list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
 978                 /*
 979                  * If the delegation may have been admin revoked, then we
 980                  * cannot reclaim it.
 981                  */
 982                 if (test_bit(NFS_DELEGATION_TEST_EXPIRED, &delegation->flags))
 983                         continue;
 984                 set_bit(NFS_DELEGATION_NEED_RECLAIM, &delegation->flags);
 985         }
 986 }
 987
 988 /**
 989  * nfs_delegation_mark_reclaim - mark all delegations as needing to be reclaimed
 990  * @clp: nfs_client to process
 991  *
 992  */
 993 void nfs_delegation_mark_reclaim(struct nfs_client *clp)
 994 {
 995         struct nfs_server *server;
 996
 997         rcu_read_lock();
 998         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
 999                 nfs_delegation_mark_reclaim_server(server);
1000         rcu_read_unlock();
1001 }
1002
1003 /**
1004  * nfs_delegation_reap_unclaimed - reap unclaimed delegations after reboot recovery is done
1005  * @clp: nfs_client to process
1006  *
1007  */
1008 void nfs_delegation_reap_unclaimed(struct nfs_client *clp)
1009 {
1010         struct nfs_delegation *delegation;
1011         struct nfs_server *server;
1012         struct inode *inode;
1013
1014 restart:
1015         rcu_read_lock();
1016         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link) {
1017                 list_for_each_entry_rcu(delegation, &server->delegations,
1018                                                                 super_list) {
1019                         if (test_bit(NFS_DELEGATION_INODE_FREEING,
1020                                                 &delegation->flags) ||
1021                             test_bit(NFS_DELEGATION_RETURNING,
1022                                                 &delegation->flags) ||
1023                             test_bit(NFS_DELEGATION_NEED_RECLAIM,
1024                                                 &delegation->flags) == 0)
1025                                 continue;
1026                         if (!nfs_sb_active(server->super))
1027                                 break; /* continue in outer loop */
1028                         inode = nfs_delegation_grab_inode(delegation);
1029                         if (inode == NULL) {
1030                                 rcu_read_unlock();
1031                                 nfs_sb_deactive(server->super);
1032                                 goto restart;
1033                         }
1034                         delegation = nfs_start_delegation_return_locked(NFS_I(inode));
1035                         rcu_read_unlock();
1036                         if (delegation != NULL) {
1037                                 delegation = nfs_detach_delegation(NFS_I(inode),
1038                                         delegation, server);
1039                                 if (delegation != NULL)
1040                                         nfs_free_delegation(delegation);
1041                         }
1042                         iput(inode);
1043                         nfs_sb_deactive(server->super);
1044                         cond_resched();
1045                         goto restart;
1046                 }
1047         }
1048         rcu_read_unlock();
1049 }
1050
1051 static inline bool nfs4_server_rebooted(const struct nfs_client *clp)
1052 {
1053         return (clp->cl_state & (BIT(NFS4CLNT_CHECK_LEASE) |
1054                                 BIT(NFS4CLNT_LEASE_EXPIRED) |
1055                                 BIT(NFS4CLNT_SESSION_RESET))) != 0;
1056 }
1057
1058 static void nfs_mark_test_expired_delegation(struct nfs_server *server,
1059             struct nfs_delegation *delegation)
1060 {
1061         if (delegation->stateid.type == NFS4_INVALID_STATEID_TYPE)
1062                 return;
1063         clear_bit(NFS_DELEGATION_NEED_RECLAIM, &delegation->flags);
1064         set_bit(NFS_DELEGATION_TEST_EXPIRED, &delegation->flags);
1065         set_bit(NFS4CLNT_DELEGATION_EXPIRED, &server->nfs_client->cl_state);
1066 }
1067
1068 static void nfs_inode_mark_test_expired_delegation(struct nfs_server *server,
1069                 struct inode *inode)
1070 {
1071         struct nfs_delegation *delegation;
1072
1073         rcu_read_lock();
1074         delegation = rcu_dereference(NFS_I(inode)->delegation);
1075         if (delegation)
1076                 nfs_mark_test_expired_delegation(server, delegation);
1077         rcu_read_unlock();
1078
1079 }
1080
1081 static void nfs_delegation_mark_test_expired_server(struct nfs_server *server)
1082 {
1083         struct nfs_delegation *delegation;
1084
1085         list_for_each_entry_rcu(delegation, &server->delegations, super_list)
1086                 nfs_mark_test_expired_delegation(server, delegation);
1087 }
1088
1089 /**
1090  * nfs_mark_test_expired_all_delegations - mark all delegations for testing
1091  * @clp: nfs_client to process
1092  *
1093  * Iterates through all the delegations associated with this server and
1094  * marks them as needing to be checked for validity.
1095  */
1096 void nfs_mark_test_expired_all_delegations(struct nfs_client *clp)
1097 {
1098         struct nfs_server *server;
1099
1100         rcu_read_lock();
1101         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
1102                 nfs_delegation_mark_test_expired_server(server);
1103         rcu_read_unlock();
1104 }
1105
1106 /**
1107  * nfs_test_expired_all_delegations - test all delegations for a client
1108  * @clp: nfs_client to process
1109  *
1110  * Helper for handling "recallable state revoked" status from server.
1111  */
1112 void nfs_test_expired_all_delegations(struct nfs_client *clp)
1113 {
1114         nfs_mark_test_expired_all_delegations(clp);
1115         nfs4_schedule_state_manager(clp);
1116 }
1117
1118 static void
1119 nfs_delegation_test_free_expired(struct inode *inode,
1120                 nfs4_stateid *stateid,
1121                 const struct cred *cred)
1122 {
1123         struct nfs_server *server = NFS_SERVER(inode);
1124         const struct nfs4_minor_version_ops *ops = server->nfs_client->cl_mvops;
1125         int status;
1126
1127         if (!cred)
1128                 return;
1129         status = ops->test_and_free_expired(server, stateid, cred);
1130         if (status == -NFS4ERR_EXPIRED || status == -NFS4ERR_BAD_STATEID)
1131                 nfs_remove_bad_delegation(inode, stateid);
1132 }
1133
1134 /**
1135  * nfs_reap_expired_delegations - reap expired delegations
1136  * @clp: nfs_client to process
1137  *
1138  * Iterates through all the delegations associated with this server and
1139  * checks if they have may have been revoked. This function is usually
1140  * expected to be called in cases where the server may have lost its
1141  * lease.
1142  */
1143 void nfs_reap_expired_delegations(struct nfs_client *clp)
1144 {
1145         struct nfs_delegation *delegation;
1146         struct nfs_server *server;
1147         struct inode *inode;
1148         const struct cred *cred;
1149         nfs4_stateid stateid;
1150
1151 restart:
1152         rcu_read_lock();
1153         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link) {
1154                 list_for_each_entry_rcu(delegation, &server->delegations,
1155                                                                 super_list) {
1156                         if (test_bit(NFS_DELEGATION_INODE_FREEING,
1157                                                 &delegation->flags) ||
1158                             test_bit(NFS_DELEGATION_RETURNING,
1159                                                 &delegation->flags) ||
1160                             test_bit(NFS_DELEGATION_TEST_EXPIRED,
1161                                                 &delegation->flags) == 0)
1162                                 continue;
1163                         if (!nfs_sb_active(server->super))
1164                                 break; /* continue in outer loop */
1165                         inode = nfs_delegation_grab_inode(delegation);
1166                         if (inode == NULL) {
1167                                 rcu_read_unlock();
1168                                 nfs_sb_deactive(server->super);
1169                                 goto restart;
1170                         }
1171                         cred = get_cred_rcu(delegation->cred);
1172                         nfs4_stateid_copy(&stateid, &delegation->stateid);
1173                         clear_bit(NFS_DELEGATION_TEST_EXPIRED, &delegation->flags);
1174                         rcu_read_unlock();
1175                         nfs_delegation_test_free_expired(inode, &stateid, cred);
1176                         put_cred(cred);
1177                         if (nfs4_server_rebooted(clp)) {
1178                                 nfs_inode_mark_test_expired_delegation(server,inode);
1179                                 iput(inode);
1180                                 nfs_sb_deactive(server->super);
1181                                 return;
1182                         }
1183                         iput(inode);
1184                         nfs_sb_deactive(server->super);
1185                         cond_resched();
1186                         goto restart;
1187                 }
1188         }
1189         rcu_read_unlock();
1190 }
1191
1192 void nfs_inode_find_delegation_state_and_recover(struct inode *inode,
1193                 const nfs4_stateid *stateid)
1194 {
1195         struct nfs_client *clp = NFS_SERVER(inode)->nfs_client;
1196         struct nfs_delegation *delegation;
1197         bool found = false;
1198
1199         rcu_read_lock();
1200         delegation = rcu_dereference(NFS_I(inode)->delegation);
1201         if (delegation &&
1202             nfs4_stateid_match_other(&delegation->stateid, stateid)) {
1203                 nfs_mark_test_expired_delegation(NFS_SERVER(inode), delegation);
1204                 found = true;
1205         }
1206         rcu_read_unlock();
1207         if (found)
1208                 nfs4_schedule_state_manager(clp);
1209 }
1210
1211 /**
1212  * nfs_delegations_present - check for existence of delegations
1213  * @clp: client state handle
1214  *
1215  * Returns one if there are any nfs_delegation structures attached
1216  * to this nfs_client.
1217  */
1218 int nfs_delegations_present(struct nfs_client *clp)
1219 {
1220         struct nfs_server *server;
1221         int ret = 0;
1222
1223         rcu_read_lock();
1224         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
1225                 if (!list_empty(&server->delegations)) {
1226                         ret = 1;
1227                         break;
1228                 }
1229         rcu_read_unlock();
1230         return ret;
1231 }
1232
1233 /**
1234  * nfs4_refresh_delegation_stateid - Update delegation stateid seqid
1235  * @dst: stateid to refresh
1236  * @inode: inode to check
1237  *
1238  * Returns "true" and updates "dst->seqid" * if inode had a delegation
1239  * that matches our delegation stateid. Otherwise "false" is returned.
1240  */
1241 bool nfs4_refresh_delegation_stateid(nfs4_stateid *dst, struct inode *inode)
1242 {
1243         struct nfs_delegation *delegation;
1244         bool ret = false;
1245         if (!inode)
1246                 goto out;
1247
1248         rcu_read_lock();
1249         delegation = rcu_dereference(NFS_I(inode)->delegation);
1250         if (delegation != NULL &&
1251             nfs4_stateid_match_other(dst, &delegation->stateid) &&
1252             !test_bit(NFS_DELEGATION_REVOKED, &delegation->flags)) {
1253                 dst->seqid = delegation->stateid.seqid;
1254                 ret = true;
1255         }
1256         rcu_read_unlock();
1257 out:
1258         return ret;
1259 }
1260
1261 /**
1262  * nfs4_copy_delegation_stateid - Copy inode's state ID information
1263  * @inode: inode to check
1264  * @flags: delegation type requirement
1265  * @dst: stateid data structure to fill in
1266  * @cred: optional argument to retrieve credential
1267  *
1268  * Returns "true" and fills in "dst->data" * if inode had a delegation,
1269  * otherwise "false" is returned.
1270  */
1271 bool nfs4_copy_delegation_stateid(struct inode *inode, fmode_t flags,
1272                 nfs4_stateid *dst, const struct cred **cred)
1273 {
1274         struct nfs_inode *nfsi = NFS_I(inode);
1275         struct nfs_delegation *delegation;
1276         bool ret;
1277
1278         flags &= FMODE_READ|FMODE_WRITE;
1279         rcu_read_lock();
1280         delegation = rcu_dereference(nfsi->delegation);
1281         ret = nfs4_is_valid_delegation(delegation, flags);
1282         if (ret) {
1283                 nfs4_stateid_copy(dst, &delegation->stateid);
1284                 nfs_mark_delegation_referenced(delegation);
1285                 if (cred)
1286                         *cred = get_cred(delegation->cred);
1287         }
1288         rcu_read_unlock();
1289         return ret;
1290 }
1291
1292 /**
1293  * nfs4_delegation_flush_on_close - Check if we must flush file on close
1294  * @inode: inode to check
1295  *
1296  * This function checks the number of outstanding writes to the file
1297  * against the delegation 'space_limit' field to see if
1298  * the spec requires us to flush the file on close.
1299  */
1300 bool nfs4_delegation_flush_on_close(const struct inode *inode)
1301 {
1302         struct nfs_inode *nfsi = NFS_I(inode);
1303         struct nfs_delegation *delegation;
1304         bool ret = true;
1305
1306         rcu_read_lock();
1307         delegation = rcu_dereference(nfsi->delegation);
1308         if (delegation == NULL || !(delegation->type & FMODE_WRITE))
1309                 goto out;
1310         if (atomic_long_read(&nfsi->nrequests) < delegation->pagemod_limit)
1311                 ret = false;
1312 out:
1313         rcu_read_unlock();
1314         return ret;
1315 }