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 (nfs4_is_valid_delegation(delegation, 0)) {
 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         return res;
 233 }
 234
 235 static struct inode *nfs_delegation_grab_inode(struct nfs_delegation *delegation)
 236 {
 237         struct inode *inode = NULL;
 238
 239         spin_lock(&delegation->lock);
 240         if (delegation->inode != NULL)
 241                 inode = igrab(delegation->inode);
 242         if (!inode)
 243                 set_bit(NFS_DELEGATION_INODE_FREEING, &delegation->flags);
 244         spin_unlock(&delegation->lock);
 245         return inode;
 246 }
 247
 248 static struct nfs_delegation *
 249 nfs_start_delegation_return_locked(struct nfs_inode *nfsi)
 250 {
 251         struct nfs_delegation *ret = NULL;
 252         struct nfs_delegation *delegation = rcu_dereference(nfsi->delegation);
 253
 254         if (delegation == NULL)
 255                 goto out;
 256         spin_lock(&delegation->lock);
 257         if (!test_and_set_bit(NFS_DELEGATION_RETURNING, &delegation->flags))
 258                 ret = delegation;
 259         spin_unlock(&delegation->lock);
 260 out:
 261         return ret;
 262 }
 263
 264 static struct nfs_delegation *
 265 nfs_start_delegation_return(struct nfs_inode *nfsi)
 266 {
 267         struct nfs_delegation *delegation;
 268
 269         rcu_read_lock();
 270         delegation = nfs_start_delegation_return_locked(nfsi);
 271         rcu_read_unlock();
 272         return delegation;
 273 }
 274
 275 static void
 276 nfs_abort_delegation_return(struct nfs_delegation *delegation,
 277                 struct nfs_client *clp)
 278 {
 279
 280         spin_lock(&delegation->lock);
 281         clear_bit(NFS_DELEGATION_RETURNING, &delegation->flags);
 282         set_bit(NFS_DELEGATION_RETURN, &delegation->flags);
 283         spin_unlock(&delegation->lock);
 284         set_bit(NFS4CLNT_DELEGRETURN, &clp->cl_state);
 285 }
 286
 287 static struct nfs_delegation *
 288 nfs_detach_delegation_locked(struct nfs_inode *nfsi,
 289                 struct nfs_delegation *delegation,
 290                 struct nfs_client *clp)
 291 {
 292         struct nfs_delegation *deleg_cur =
 293                 rcu_dereference_protected(nfsi->delegation,
 294                                 lockdep_is_held(&clp->cl_lock));
 295
 296         if (deleg_cur == NULL || delegation != deleg_cur)
 297                 return NULL;
 298
 299         spin_lock(&delegation->lock);
 300         if (!delegation->inode) {
 301                 spin_unlock(&delegation->lock);
 302                 return NULL;
 303         }
 304         list_del_rcu(&delegation->super_list);
 305         delegation->inode = NULL;
 306         rcu_assign_pointer(nfsi->delegation, NULL);
 307         spin_unlock(&delegation->lock);
 308         return delegation;
 309 }
 310
 311 static struct nfs_delegation *nfs_detach_delegation(struct nfs_inode *nfsi,
 312                 struct nfs_delegation *delegation,
 313                 struct nfs_server *server)
 314 {
 315         struct nfs_client *clp = server->nfs_client;
 316
 317         spin_lock(&clp->cl_lock);
 318         delegation = nfs_detach_delegation_locked(nfsi, delegation, clp);
 319         spin_unlock(&clp->cl_lock);
 320         return delegation;
 321 }
 322
 323 static struct nfs_delegation *
 324 nfs_inode_detach_delegation(struct inode *inode)
 325 {
 326         struct nfs_inode *nfsi = NFS_I(inode);
 327         struct nfs_server *server = NFS_SERVER(inode);
 328         struct nfs_delegation *delegation;
 329
 330         rcu_read_lock();
 331         delegation = rcu_dereference(nfsi->delegation);
 332         if (delegation != NULL)
 333                 delegation = nfs_detach_delegation(nfsi, delegation, server);
 334         rcu_read_unlock();
 335         return delegation;
 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                 goto add_new;
 389         /* Is this an update of the existing delegation? */
 390         if (nfs4_stateid_match_other(&old_delegation->stateid,
 391                                 &delegation->stateid)) {
 392                 spin_lock(&old_delegation->lock);
 393                 nfs_update_inplace_delegation(old_delegation,
 394                                 delegation);
 395                 spin_unlock(&old_delegation->lock);
 396                 goto out;
 397         }
 398         if (!test_bit(NFS_DELEGATION_REVOKED, &old_delegation->flags)) {
 399                 /*
 400                  * Deal with broken servers that hand out two
 401                  * delegations for the same file.
 402                  * Allow for upgrades to a WRITE delegation, but
 403                  * nothing else.
 404                  */
 405                 dfprintk(FILE, "%s: server %s handed out "
 406                                 "a duplicate delegation!\n",
 407                                 __func__, clp->cl_hostname);
 408                 if (delegation->type == old_delegation->type ||
 409                     !(delegation->type & FMODE_WRITE)) {
 410                         freeme = delegation;
 411                         delegation = NULL;
 412                         goto out;
 413                 }
 414                 if (test_and_set_bit(NFS_DELEGATION_RETURNING,
 415                                         &old_delegation->flags))
 416                         goto out;
 417         }
 418         freeme = nfs_detach_delegation_locked(nfsi, old_delegation, clp);
 419         if (freeme == NULL)
 420                 goto out;
 421 add_new:
 422         list_add_tail_rcu(&delegation->super_list, &server->delegations);
 423         rcu_assign_pointer(nfsi->delegation, delegation);
 424         delegation = NULL;
 425
 426         trace_nfs4_set_delegation(inode, type);
 427
 428         spin_lock(&inode->i_lock);
 429         if (NFS_I(inode)->cache_validity & (NFS_INO_INVALID_ATTR|NFS_INO_INVALID_ATIME))
 430                 NFS_I(inode)->cache_validity |= NFS_INO_REVAL_FORCED;
 431         spin_unlock(&inode->i_lock);
 432 out:
 433         spin_unlock(&clp->cl_lock);
 434         if (delegation != NULL)
 435                 nfs_free_delegation(delegation);
 436         if (freeme != NULL) {
 437                 nfs_do_return_delegation(inode, freeme, 0);
 438                 nfs_free_delegation(freeme);
 439         }
 440         return status;
 441 }
 442
 443 /*
 444  * Basic procedure for returning a delegation to the server
 445  */
 446 static int nfs_end_delegation_return(struct inode *inode, struct nfs_delegation *delegation, int issync)
 447 {
 448         struct nfs_client *clp = NFS_SERVER(inode)->nfs_client;
 449         int err = 0;
 450
 451         if (delegation == NULL)
 452                 return 0;
 453         do {
 454                 if (test_bit(NFS_DELEGATION_REVOKED, &delegation->flags))
 455                         break;
 456                 err = nfs_delegation_claim_opens(inode, &delegation->stateid,
 457                                 delegation->type);
 458                 if (!issync || err != -EAGAIN)
 459                         break;
 460                 /*
 461                  * Guard against state recovery
 462                  */
 463                 err = nfs4_wait_clnt_recover(clp);
 464         } while (err == 0);
 465
 466         if (err) {
 467                 nfs_abort_delegation_return(delegation, clp);
 468                 goto out;
 469         }
 470
 471         err = nfs_do_return_delegation(inode, delegation, issync);
 472 out:
 473         return err;
 474 }
 475
 476 static bool nfs_delegation_need_return(struct nfs_delegation *delegation)
 477 {
 478         bool ret = false;
 479
 480         if (test_and_clear_bit(NFS_DELEGATION_RETURN, &delegation->flags))
 481                 ret = true;
 482         if (test_and_clear_bit(NFS_DELEGATION_RETURN_IF_CLOSED, &delegation->flags) && !ret) {
 483                 struct inode *inode;
 484
 485                 spin_lock(&delegation->lock);
 486                 inode = delegation->inode;
 487                 if (inode && list_empty(&NFS_I(inode)->open_files))
 488                         ret = true;
 489                 spin_unlock(&delegation->lock);
 490         }
 491         if (test_bit(NFS_DELEGATION_RETURNING, &delegation->flags) ||
 492             test_bit(NFS_DELEGATION_REVOKED, &delegation->flags))
 493                 ret = false;
 494
 495         return ret;
 496 }
 497
 498 /**
 499  * nfs_client_return_marked_delegations - return previously marked delegations
 500  * @clp: nfs_client to process
 501  *
 502  * Note that this function is designed to be called by the state
 503  * manager thread. For this reason, it cannot flush the dirty data,
 504  * since that could deadlock in case of a state recovery error.
 505  *
 506  * Returns zero on success, or a negative errno value.
 507  */
 508 int nfs_client_return_marked_delegations(struct nfs_client *clp)
 509 {
 510         struct nfs_delegation *delegation;
 511         struct nfs_delegation *prev;
 512         struct nfs_server *server;
 513         struct inode *inode;
 514         struct inode *place_holder = NULL;
 515         struct nfs_delegation *place_holder_deleg = NULL;
 516         int err = 0;
 517
 518 restart:
 519         /*
 520          * To avoid quadratic looping we hold a reference
 521          * to an inode place_holder.  Each time we restart, we
 522          * list nfs_servers from the server of that inode, and
 523          * delegation in the server from the delegations of that
 524          * inode.
 525          * prev is an RCU-protected pointer to a delegation which
 526          * wasn't marked for return and might be a good choice for
 527          * the next place_holder.
 528          */
 529         rcu_read_lock();
 530         prev = NULL;
 531         if (place_holder)
 532                 server = NFS_SERVER(place_holder);
 533         else
 534                 server = list_entry_rcu(clp->cl_superblocks.next,
 535                                         struct nfs_server, client_link);
 536         list_for_each_entry_from_rcu(server, &clp->cl_superblocks, client_link) {
 537                 delegation = NULL;
 538                 if (place_holder && server == NFS_SERVER(place_holder))
 539                         delegation = rcu_dereference(NFS_I(place_holder)->delegation);
 540                 if (!delegation || delegation != place_holder_deleg)
 541                         delegation = list_entry_rcu(server->delegations.next,
 542                                                     struct nfs_delegation, super_list);
 543                 list_for_each_entry_from_rcu(delegation, &server->delegations, super_list) {
 544                         struct inode *to_put = NULL;
 545
 546                         if (!nfs_delegation_need_return(delegation)) {
 547                                 prev = delegation;
 548                                 continue;
 549                         }
 550                         if (!nfs_sb_active(server->super))
 551                                 break; /* continue in outer loop */
 552
 553                         if (prev) {
 554                                 struct inode *tmp;
 555
 556                                 tmp = nfs_delegation_grab_inode(prev);
 557                                 if (tmp) {
 558                                         to_put = place_holder;
 559                                         place_holder = tmp;
 560                                         place_holder_deleg = prev;
 561                                 }
 562                         }
 563
 564                         inode = nfs_delegation_grab_inode(delegation);
 565                         if (inode == NULL) {
 566                                 rcu_read_unlock();
 567                                 if (to_put)
 568                                         iput(to_put);
 569                                 nfs_sb_deactive(server->super);
 570                                 goto restart;
 571                         }
 572                         delegation = nfs_start_delegation_return_locked(NFS_I(inode));
 573                         rcu_read_unlock();
 574
 575                         if (to_put)
 576                                 iput(to_put);
 577
 578                         err = nfs_end_delegation_return(inode, delegation, 0);
 579                         iput(inode);
 580                         nfs_sb_deactive(server->super);
 581                         cond_resched();
 582                         if (!err)
 583                                 goto restart;
 584                         set_bit(NFS4CLNT_DELEGRETURN, &clp->cl_state);
 585                         if (place_holder)
 586                                 iput(place_holder);
 587                         return err;
 588                 }
 589         }
 590         rcu_read_unlock();
 591         if (place_holder)
 592                 iput(place_holder);
 593         return 0;
 594 }
 595
 596 /**
 597  * nfs_inode_evict_delegation - return delegation, don't reclaim opens
 598  * @inode: inode to process
 599  *
 600  * Does not protect against delegation reclaims, therefore really only safe
 601  * to be called from nfs4_clear_inode(). Guaranteed to always free
 602  * the delegation structure.
 603  */
 604 void nfs_inode_evict_delegation(struct inode *inode)
 605 {
 606         struct nfs_delegation *delegation;
 607
 608         delegation = nfs_inode_detach_delegation(inode);
 609         if (delegation != NULL) {
 610                 set_bit(NFS_DELEGATION_INODE_FREEING, &delegation->flags);
 611                 nfs_do_return_delegation(inode, delegation, 1);
 612                 nfs_free_delegation(delegation);
 613         }
 614 }
 615
 616 /**
 617  * nfs_inode_return_delegation - synchronously return a delegation
 618  * @inode: inode to process
 619  *
 620  * This routine will always flush any dirty data to disk on the
 621  * assumption that if we need to return the delegation, then
 622  * we should stop caching.
 623  *
 624  * Returns zero on success, or a negative errno value.
 625  */
 626 int nfs4_inode_return_delegation(struct inode *inode)
 627 {
 628         struct nfs_inode *nfsi = NFS_I(inode);
 629         struct nfs_delegation *delegation;
 630         int err = 0;
 631
 632         nfs_wb_all(inode);
 633         delegation = nfs_start_delegation_return(nfsi);
 634         if (delegation != NULL)
 635                 err = nfs_end_delegation_return(inode, delegation, 1);
 636         return err;
 637 }
 638
 639 /**
 640  * nfs4_inode_make_writeable
 641  * @inode: pointer to inode
 642  *
 643  * Make the inode writeable by returning the delegation if necessary
 644  *
 645  * Returns zero on success, or a negative errno value.
 646  */
 647 int nfs4_inode_make_writeable(struct inode *inode)
 648 {
 649         struct nfs_delegation *delegation;
 650
 651         rcu_read_lock();
 652         delegation = nfs4_get_valid_delegation(inode);
 653         if (delegation == NULL ||
 654             (nfs4_has_session(NFS_SERVER(inode)->nfs_client) &&
 655              (delegation->type & FMODE_WRITE))) {
 656                 rcu_read_unlock();
 657                 return 0;
 658         }
 659         rcu_read_unlock();
 660         return nfs4_inode_return_delegation(inode);
 661 }
 662
 663 static void nfs_mark_return_if_closed_delegation(struct nfs_server *server,
 664                 struct nfs_delegation *delegation)
 665 {
 666         set_bit(NFS_DELEGATION_RETURN_IF_CLOSED, &delegation->flags);
 667         set_bit(NFS4CLNT_DELEGRETURN, &server->nfs_client->cl_state);
 668 }
 669
 670 static void nfs_mark_return_delegation(struct nfs_server *server,
 671                 struct nfs_delegation *delegation)
 672 {
 673         set_bit(NFS_DELEGATION_RETURN, &delegation->flags);
 674         set_bit(NFS4CLNT_DELEGRETURN, &server->nfs_client->cl_state);
 675 }
 676
 677 static bool nfs_server_mark_return_all_delegations(struct nfs_server *server)
 678 {
 679         struct nfs_delegation *delegation;
 680         bool ret = false;
 681
 682         list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
 683                 nfs_mark_return_delegation(server, delegation);
 684                 ret = true;
 685         }
 686         return ret;
 687 }
 688
 689 static void nfs_client_mark_return_all_delegations(struct nfs_client *clp)
 690 {
 691         struct nfs_server *server;
 692
 693         rcu_read_lock();
 694         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
 695                 nfs_server_mark_return_all_delegations(server);
 696         rcu_read_unlock();
 697 }
 698
 699 static void nfs_delegation_run_state_manager(struct nfs_client *clp)
 700 {
 701         if (test_bit(NFS4CLNT_DELEGRETURN, &clp->cl_state))
 702                 nfs4_schedule_state_manager(clp);
 703 }
 704
 705 /**
 706  * nfs_expire_all_delegations
 707  * @clp: client to process
 708  *
 709  */
 710 void nfs_expire_all_delegations(struct nfs_client *clp)
 711 {
 712         nfs_client_mark_return_all_delegations(clp);
 713         nfs_delegation_run_state_manager(clp);
 714 }
 715
 716 /**
 717  * nfs_super_return_all_delegations - return delegations for one superblock
 718  * @server: pointer to nfs_server to process
 719  *
 720  */
 721 void nfs_server_return_all_delegations(struct nfs_server *server)
 722 {
 723         struct nfs_client *clp = server->nfs_client;
 724         bool need_wait;
 725
 726         if (clp == NULL)
 727                 return;
 728
 729         rcu_read_lock();
 730         need_wait = nfs_server_mark_return_all_delegations(server);
 731         rcu_read_unlock();
 732
 733         if (need_wait) {
 734                 nfs4_schedule_state_manager(clp);
 735                 nfs4_wait_clnt_recover(clp);
 736         }
 737 }
 738
 739 static void nfs_mark_return_unused_delegation_types(struct nfs_server *server,
 740                                                  fmode_t flags)
 741 {
 742         struct nfs_delegation *delegation;
 743
 744         list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
 745                 if ((delegation->type == (FMODE_READ|FMODE_WRITE)) && !(flags & FMODE_WRITE))
 746                         continue;
 747                 if (delegation->type & flags)
 748                         nfs_mark_return_if_closed_delegation(server, delegation);
 749         }
 750 }
 751
 752 static void nfs_client_mark_return_unused_delegation_types(struct nfs_client *clp,
 753                                                         fmode_t flags)
 754 {
 755         struct nfs_server *server;
 756
 757         rcu_read_lock();
 758         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
 759                 nfs_mark_return_unused_delegation_types(server, flags);
 760         rcu_read_unlock();
 761 }
 762
 763 static void nfs_mark_delegation_revoked(struct nfs_server *server,
 764                 struct nfs_delegation *delegation)
 765 {
 766         set_bit(NFS_DELEGATION_REVOKED, &delegation->flags);
 767         delegation->stateid.type = NFS4_INVALID_STATEID_TYPE;
 768 }
 769
 770 static void nfs_revoke_delegation(struct inode *inode,
 771                 const nfs4_stateid *stateid)
 772 {
 773         struct nfs_delegation *delegation;
 774         nfs4_stateid tmp;
 775         bool ret = false;
 776
 777         rcu_read_lock();
 778         delegation = rcu_dereference(NFS_I(inode)->delegation);
 779         if (delegation == NULL)
 780                 goto out;
 781         if (stateid == NULL) {
 782                 nfs4_stateid_copy(&tmp, &delegation->stateid);
 783                 stateid = &tmp;
 784         } else {
 785                 if (!nfs4_stateid_match_other(stateid, &delegation->stateid))
 786                         goto out;
 787                 spin_lock(&delegation->lock);
 788                 if (stateid->seqid) {
 789                         if (nfs4_stateid_is_newer(&delegation->stateid, stateid)) {
 790                                 spin_unlock(&delegation->lock);
 791                                 goto out;
 792                         }
 793                         delegation->stateid.seqid = stateid->seqid;
 794                 }
 795                 spin_unlock(&delegation->lock);
 796         }
 797         nfs_mark_delegation_revoked(NFS_SERVER(inode), delegation);
 798         ret = true;
 799 out:
 800         rcu_read_unlock();
 801         if (ret)
 802                 nfs_inode_find_state_and_recover(inode, stateid);
 803 }
 804
 805 void nfs_remove_bad_delegation(struct inode *inode,
 806                 const nfs4_stateid *stateid)
 807 {
 808         nfs_revoke_delegation(inode, stateid);
 809 }
 810 EXPORT_SYMBOL_GPL(nfs_remove_bad_delegation);
 811
 812 void nfs_delegation_mark_returned(struct inode *inode,
 813                 const nfs4_stateid *stateid)
 814 {
 815         struct nfs_delegation *delegation;
 816
 817         if (!inode)
 818                 return;
 819
 820         rcu_read_lock();
 821         delegation = rcu_dereference(NFS_I(inode)->delegation);
 822         if (!delegation)
 823                 goto out_rcu_unlock;
 824
 825         spin_lock(&delegation->lock);
 826         if (!nfs4_stateid_match_other(stateid, &delegation->stateid))
 827                 goto out_spin_unlock;
 828         if (stateid->seqid) {
 829                 /* If delegation->stateid is newer, dont mark as returned */
 830                 if (nfs4_stateid_is_newer(&delegation->stateid, stateid))
 831                         goto out_clear_returning;
 832                 if (delegation->stateid.seqid != stateid->seqid)
 833                         delegation->stateid.seqid = stateid->seqid;
 834         }
 835
 836         nfs_mark_delegation_revoked(NFS_SERVER(inode), delegation);
 837
 838 out_clear_returning:
 839         clear_bit(NFS_DELEGATION_RETURNING, &delegation->flags);
 840 out_spin_unlock:
 841         spin_unlock(&delegation->lock);
 842 out_rcu_unlock:
 843         rcu_read_unlock();
 844
 845         nfs_inode_find_state_and_recover(inode, stateid);
 846 }
 847
 848 /**
 849  * nfs_expire_unused_delegation_types
 850  * @clp: client to process
 851  * @flags: delegation types to expire
 852  *
 853  */
 854 void nfs_expire_unused_delegation_types(struct nfs_client *clp, fmode_t flags)
 855 {
 856         nfs_client_mark_return_unused_delegation_types(clp, flags);
 857         nfs_delegation_run_state_manager(clp);
 858 }
 859
 860 static void nfs_mark_return_unreferenced_delegations(struct nfs_server *server)
 861 {
 862         struct nfs_delegation *delegation;
 863
 864         list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
 865                 if (test_and_clear_bit(NFS_DELEGATION_REFERENCED, &delegation->flags))
 866                         continue;
 867                 nfs_mark_return_if_closed_delegation(server, delegation);
 868         }
 869 }
 870
 871 /**
 872  * nfs_expire_unreferenced_delegations - Eliminate unused delegations
 873  * @clp: nfs_client to process
 874  *
 875  */
 876 void nfs_expire_unreferenced_delegations(struct nfs_client *clp)
 877 {
 878         struct nfs_server *server;
 879
 880         rcu_read_lock();
 881         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
 882                 nfs_mark_return_unreferenced_delegations(server);
 883         rcu_read_unlock();
 884
 885         nfs_delegation_run_state_manager(clp);
 886 }
 887
 888 /**
 889  * nfs_async_inode_return_delegation - asynchronously return a delegation
 890  * @inode: inode to process
 891  * @stateid: state ID information
 892  *
 893  * Returns zero on success, or a negative errno value.
 894  */
 895 int nfs_async_inode_return_delegation(struct inode *inode,
 896                                       const nfs4_stateid *stateid)
 897 {
 898         struct nfs_server *server = NFS_SERVER(inode);
 899         struct nfs_client *clp = server->nfs_client;
 900         struct nfs_delegation *delegation;
 901
 902         rcu_read_lock();
 903         delegation = nfs4_get_valid_delegation(inode);
 904         if (delegation == NULL)
 905                 goto out_enoent;
 906         if (stateid != NULL &&
 907             !clp->cl_mvops->match_stateid(&delegation->stateid, stateid))
 908                 goto out_enoent;
 909         nfs_mark_return_delegation(server, delegation);
 910         rcu_read_unlock();
 911
 912         nfs_delegation_run_state_manager(clp);
 913         return 0;
 914 out_enoent:
 915         rcu_read_unlock();
 916         return -ENOENT;
 917 }
 918
 919 static struct inode *
 920 nfs_delegation_find_inode_server(struct nfs_server *server,
 921                                  const struct nfs_fh *fhandle)
 922 {
 923         struct nfs_delegation *delegation;
 924         struct inode *freeme, *res = NULL;
 925
 926         list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
 927                 spin_lock(&delegation->lock);
 928                 if (delegation->inode != NULL &&
 929                     !test_bit(NFS_DELEGATION_REVOKED, &delegation->flags) &&
 930                     nfs_compare_fh(fhandle, &NFS_I(delegation->inode)->fh) == 0) {
 931                         freeme = igrab(delegation->inode);
 932                         if (freeme && nfs_sb_active(freeme->i_sb))
 933                                 res = freeme;
 934                         spin_unlock(&delegation->lock);
 935                         if (res != NULL)
 936                                 return res;
 937                         if (freeme) {
 938                                 rcu_read_unlock();
 939                                 iput(freeme);
 940                                 rcu_read_lock();
 941                         }
 942                         return ERR_PTR(-EAGAIN);
 943                 }
 944                 spin_unlock(&delegation->lock);
 945         }
 946         return ERR_PTR(-ENOENT);
 947 }
 948
 949 /**
 950  * nfs_delegation_find_inode - retrieve the inode associated with a delegation
 951  * @clp: client state handle
 952  * @fhandle: filehandle from a delegation recall
 953  *
 954  * Returns pointer to inode matching "fhandle," or NULL if a matching inode
 955  * cannot be found.
 956  */
 957 struct inode *nfs_delegation_find_inode(struct nfs_client *clp,
 958                                         const struct nfs_fh *fhandle)
 959 {
 960         struct nfs_server *server;
 961         struct inode *res;
 962
 963         rcu_read_lock();
 964         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link) {
 965                 res = nfs_delegation_find_inode_server(server, fhandle);
 966                 if (res != ERR_PTR(-ENOENT)) {
 967                         rcu_read_unlock();
 968                         return res;
 969                 }
 970         }
 971         rcu_read_unlock();
 972         return ERR_PTR(-ENOENT);
 973 }
 974
 975 static void nfs_delegation_mark_reclaim_server(struct nfs_server *server)
 976 {
 977         struct nfs_delegation *delegation;
 978
 979         list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
 980                 /*
 981                  * If the delegation may have been admin revoked, then we
 982                  * cannot reclaim it.
 983                  */
 984                 if (test_bit(NFS_DELEGATION_TEST_EXPIRED, &delegation->flags))
 985                         continue;
 986                 set_bit(NFS_DELEGATION_NEED_RECLAIM, &delegation->flags);
 987         }
 988 }
 989
 990 /**
 991  * nfs_delegation_mark_reclaim - mark all delegations as needing to be reclaimed
 992  * @clp: nfs_client to process
 993  *
 994  */
 995 void nfs_delegation_mark_reclaim(struct nfs_client *clp)
 996 {
 997         struct nfs_server *server;
 998
 999         rcu_read_lock();
1000         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
1001                 nfs_delegation_mark_reclaim_server(server);
1002         rcu_read_unlock();
1003 }
1004
1005 /**
1006  * nfs_delegation_reap_unclaimed - reap unclaimed delegations after reboot recovery is done
1007  * @clp: nfs_client to process
1008  *
1009  */
1010 void nfs_delegation_reap_unclaimed(struct nfs_client *clp)
1011 {
1012         struct nfs_delegation *delegation;
1013         struct nfs_server *server;
1014         struct inode *inode;
1015
1016 restart:
1017         rcu_read_lock();
1018         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link) {
1019                 list_for_each_entry_rcu(delegation, &server->delegations,
1020                                                                 super_list) {
1021                         if (test_bit(NFS_DELEGATION_INODE_FREEING,
1022                                                 &delegation->flags) ||
1023                             test_bit(NFS_DELEGATION_RETURNING,
1024                                                 &delegation->flags) ||
1025                             test_bit(NFS_DELEGATION_NEED_RECLAIM,
1026                                                 &delegation->flags) == 0)
1027                                 continue;
1028                         if (!nfs_sb_active(server->super))
1029                                 break; /* continue in outer loop */
1030                         inode = nfs_delegation_grab_inode(delegation);
1031                         if (inode == NULL) {
1032                                 rcu_read_unlock();
1033                                 nfs_sb_deactive(server->super);
1034                                 goto restart;
1035                         }
1036                         delegation = nfs_start_delegation_return_locked(NFS_I(inode));
1037                         rcu_read_unlock();
1038                         if (delegation != NULL) {
1039                                 delegation = nfs_detach_delegation(NFS_I(inode),
1040                                         delegation, server);
1041                                 if (delegation != NULL)
1042                                         nfs_free_delegation(delegation);
1043                         }
1044                         iput(inode);
1045                         nfs_sb_deactive(server->super);
1046                         cond_resched();
1047                         goto restart;
1048                 }
1049         }
1050         rcu_read_unlock();
1051 }
1052
1053 static inline bool nfs4_server_rebooted(const struct nfs_client *clp)
1054 {
1055         return (clp->cl_state & (BIT(NFS4CLNT_CHECK_LEASE) |
1056                                 BIT(NFS4CLNT_LEASE_EXPIRED) |
1057                                 BIT(NFS4CLNT_SESSION_RESET))) != 0;
1058 }
1059
1060 static void nfs_mark_test_expired_delegation(struct nfs_server *server,
1061             struct nfs_delegation *delegation)
1062 {
1063         if (delegation->stateid.type == NFS4_INVALID_STATEID_TYPE)
1064                 return;
1065         clear_bit(NFS_DELEGATION_NEED_RECLAIM, &delegation->flags);
1066         set_bit(NFS_DELEGATION_TEST_EXPIRED, &delegation->flags);
1067         set_bit(NFS4CLNT_DELEGATION_EXPIRED, &server->nfs_client->cl_state);
1068 }
1069
1070 static void nfs_inode_mark_test_expired_delegation(struct nfs_server *server,
1071                 struct inode *inode)
1072 {
1073         struct nfs_delegation *delegation;
1074
1075         rcu_read_lock();
1076         delegation = rcu_dereference(NFS_I(inode)->delegation);
1077         if (delegation)
1078                 nfs_mark_test_expired_delegation(server, delegation);
1079         rcu_read_unlock();
1080
1081 }
1082
1083 static void nfs_delegation_mark_test_expired_server(struct nfs_server *server)
1084 {
1085         struct nfs_delegation *delegation;
1086
1087         list_for_each_entry_rcu(delegation, &server->delegations, super_list)
1088                 nfs_mark_test_expired_delegation(server, delegation);
1089 }
1090
1091 /**
1092  * nfs_mark_test_expired_all_delegations - mark all delegations for testing
1093  * @clp: nfs_client to process
1094  *
1095  * Iterates through all the delegations associated with this server and
1096  * marks them as needing to be checked for validity.
1097  */
1098 void nfs_mark_test_expired_all_delegations(struct nfs_client *clp)
1099 {
1100         struct nfs_server *server;
1101
1102         rcu_read_lock();
1103         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
1104                 nfs_delegation_mark_test_expired_server(server);
1105         rcu_read_unlock();
1106 }
1107
1108 /**
1109  * nfs_test_expired_all_delegations - test all delegations for a client
1110  * @clp: nfs_client to process
1111  *
1112  * Helper for handling "recallable state revoked" status from server.
1113  */
1114 void nfs_test_expired_all_delegations(struct nfs_client *clp)
1115 {
1116         nfs_mark_test_expired_all_delegations(clp);
1117         nfs4_schedule_state_manager(clp);
1118 }
1119
1120 static void
1121 nfs_delegation_test_free_expired(struct inode *inode,
1122                 nfs4_stateid *stateid,
1123                 const struct cred *cred)
1124 {
1125         struct nfs_server *server = NFS_SERVER(inode);
1126         const struct nfs4_minor_version_ops *ops = server->nfs_client->cl_mvops;
1127         int status;
1128
1129         if (!cred)
1130                 return;
1131         status = ops->test_and_free_expired(server, stateid, cred);
1132         if (status == -NFS4ERR_EXPIRED || status == -NFS4ERR_BAD_STATEID)
1133                 nfs_remove_bad_delegation(inode, stateid);
1134 }
1135
1136 /**
1137  * nfs_reap_expired_delegations - reap expired delegations
1138  * @clp: nfs_client to process
1139  *
1140  * Iterates through all the delegations associated with this server and
1141  * checks if they have may have been revoked. This function is usually
1142  * expected to be called in cases where the server may have lost its
1143  * lease.
1144  */
1145 void nfs_reap_expired_delegations(struct nfs_client *clp)
1146 {
1147         struct nfs_delegation *delegation;
1148         struct nfs_server *server;
1149         struct inode *inode;
1150         const struct cred *cred;
1151         nfs4_stateid stateid;
1152
1153 restart:
1154         rcu_read_lock();
1155         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link) {
1156                 list_for_each_entry_rcu(delegation, &server->delegations,
1157                                                                 super_list) {
1158                         if (test_bit(NFS_DELEGATION_INODE_FREEING,
1159                                                 &delegation->flags) ||
1160                             test_bit(NFS_DELEGATION_RETURNING,
1161                                                 &delegation->flags) ||
1162                             test_bit(NFS_DELEGATION_TEST_EXPIRED,
1163                                                 &delegation->flags) == 0)
1164                                 continue;
1165                         if (!nfs_sb_active(server->super))
1166                                 break; /* continue in outer loop */
1167                         inode = nfs_delegation_grab_inode(delegation);
1168                         if (inode == NULL) {
1169                                 rcu_read_unlock();
1170                                 nfs_sb_deactive(server->super);
1171                                 goto restart;
1172                         }
1173                         cred = get_cred_rcu(delegation->cred);
1174                         nfs4_stateid_copy(&stateid, &delegation->stateid);
1175                         clear_bit(NFS_DELEGATION_TEST_EXPIRED, &delegation->flags);
1176                         rcu_read_unlock();
1177                         nfs_delegation_test_free_expired(inode, &stateid, cred);
1178                         put_cred(cred);
1179                         if (nfs4_server_rebooted(clp)) {
1180                                 nfs_inode_mark_test_expired_delegation(server,inode);
1181                                 iput(inode);
1182                                 nfs_sb_deactive(server->super);
1183                                 return;
1184                         }
1185                         iput(inode);
1186                         nfs_sb_deactive(server->super);
1187                         cond_resched();
1188                         goto restart;
1189                 }
1190         }
1191         rcu_read_unlock();
1192 }
1193
1194 void nfs_inode_find_delegation_state_and_recover(struct inode *inode,
1195                 const nfs4_stateid *stateid)
1196 {
1197         struct nfs_client *clp = NFS_SERVER(inode)->nfs_client;
1198         struct nfs_delegation *delegation;
1199         bool found = false;
1200
1201         rcu_read_lock();
1202         delegation = rcu_dereference(NFS_I(inode)->delegation);
1203         if (delegation &&
1204             nfs4_stateid_match_or_older(&delegation->stateid, stateid) &&
1205             !test_bit(NFS_DELEGATION_REVOKED, &delegation->flags)) {
1206                 nfs_mark_test_expired_delegation(NFS_SERVER(inode), delegation);
1207                 found = true;
1208         }
1209         rcu_read_unlock();
1210         if (found)
1211                 nfs4_schedule_state_manager(clp);
1212 }
1213
1214 /**
1215  * nfs_delegations_present - check for existence of delegations
1216  * @clp: client state handle
1217  *
1218  * Returns one if there are any nfs_delegation structures attached
1219  * to this nfs_client.
1220  */
1221 int nfs_delegations_present(struct nfs_client *clp)
1222 {
1223         struct nfs_server *server;
1224         int ret = 0;
1225
1226         rcu_read_lock();
1227         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
1228                 if (!list_empty(&server->delegations)) {
1229                         ret = 1;
1230                         break;
1231                 }
1232         rcu_read_unlock();
1233         return ret;
1234 }
1235
1236 /**
1237  * nfs4_refresh_delegation_stateid - Update delegation stateid seqid
1238  * @dst: stateid to refresh
1239  * @inode: inode to check
1240  *
1241  * Returns "true" and updates "dst->seqid" * if inode had a delegation
1242  * that matches our delegation stateid. Otherwise "false" is returned.
1243  */
1244 bool nfs4_refresh_delegation_stateid(nfs4_stateid *dst, struct inode *inode)
1245 {
1246         struct nfs_delegation *delegation;
1247         bool ret = false;
1248         if (!inode)
1249                 goto out;
1250
1251         rcu_read_lock();
1252         delegation = rcu_dereference(NFS_I(inode)->delegation);
1253         if (delegation != NULL &&
1254             nfs4_stateid_match_other(dst, &delegation->stateid) &&
1255             nfs4_stateid_is_newer(&delegation->stateid, dst) &&
1256             !test_bit(NFS_DELEGATION_REVOKED, &delegation->flags)) {
1257                 dst->seqid = delegation->stateid.seqid;
1258                 ret = true;
1259         }
1260         rcu_read_unlock();
1261 out:
1262         return ret;
1263 }
1264
1265 /**
1266  * nfs4_copy_delegation_stateid - Copy inode's state ID information
1267  * @inode: inode to check
1268  * @flags: delegation type requirement
1269  * @dst: stateid data structure to fill in
1270  * @cred: optional argument to retrieve credential
1271  *
1272  * Returns "true" and fills in "dst->data" * if inode had a delegation,
1273  * otherwise "false" is returned.
1274  */
1275 bool nfs4_copy_delegation_stateid(struct inode *inode, fmode_t flags,
1276                 nfs4_stateid *dst, const struct cred **cred)
1277 {
1278         struct nfs_inode *nfsi = NFS_I(inode);
1279         struct nfs_delegation *delegation;
1280         bool ret;
1281
1282         flags &= FMODE_READ|FMODE_WRITE;
1283         rcu_read_lock();
1284         delegation = rcu_dereference(nfsi->delegation);
1285         ret = nfs4_is_valid_delegation(delegation, flags);
1286         if (ret) {
1287                 nfs4_stateid_copy(dst, &delegation->stateid);
1288                 nfs_mark_delegation_referenced(delegation);
1289                 if (cred)
1290                         *cred = get_cred(delegation->cred);
1291         }
1292         rcu_read_unlock();
1293         return ret;
1294 }
1295
1296 /**
1297  * nfs4_delegation_flush_on_close - Check if we must flush file on close
1298  * @inode: inode to check
1299  *
1300  * This function checks the number of outstanding writes to the file
1301  * against the delegation 'space_limit' field to see if
1302  * the spec requires us to flush the file on close.
1303  */
1304 bool nfs4_delegation_flush_on_close(const struct inode *inode)
1305 {
1306         struct nfs_inode *nfsi = NFS_I(inode);
1307         struct nfs_delegation *delegation;
1308         bool ret = true;
1309
1310         rcu_read_lock();
1311         delegation = rcu_dereference(nfsi->delegation);
1312         if (delegation == NULL || !(delegation->type & FMODE_WRITE))
1313                 goto out;
1314         if (atomic_long_read(&nfsi->nrequests) < delegation->pagemod_limit)
1315                 ret = false;
1316 out:
1317         rcu_read_unlock();
1318         return ret;
1319 }