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         else if (test_bit(NFS_DELEGATION_RETURN_IF_CLOSED, &delegation->flags)) {
 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 (ret)
 492                 clear_bit(NFS_DELEGATION_RETURN_IF_CLOSED, &delegation->flags);
 493         if (test_bit(NFS_DELEGATION_RETURNING, &delegation->flags) ||
 494             test_bit(NFS_DELEGATION_REVOKED, &delegation->flags))
 495                 ret = false;
 496
 497         return ret;
 498 }
 499
 500 /**
 501  * nfs_client_return_marked_delegations - return previously marked delegations
 502  * @clp: nfs_client to process
 503  *
 504  * Note that this function is designed to be called by the state
 505  * manager thread. For this reason, it cannot flush the dirty data,
 506  * since that could deadlock in case of a state recovery error.
 507  *
 508  * Returns zero on success, or a negative errno value.
 509  */
 510 int nfs_client_return_marked_delegations(struct nfs_client *clp)
 511 {
 512         struct nfs_delegation *delegation;
 513         struct nfs_delegation *prev;
 514         struct nfs_server *server;
 515         struct inode *inode;
 516         struct inode *place_holder = NULL;
 517         struct nfs_delegation *place_holder_deleg = NULL;
 518         int err = 0;
 519
 520 restart:
 521         /*
 522          * To avoid quadratic looping we hold a reference
 523          * to an inode place_holder.  Each time we restart, we
 524          * list nfs_servers from the server of that inode, and
 525          * delegation in the server from the delegations of that
 526          * inode.
 527          * prev is an RCU-protected pointer to a delegation which
 528          * wasn't marked for return and might be a good choice for
 529          * the next place_holder.
 530          */
 531         rcu_read_lock();
 532         prev = NULL;
 533         if (place_holder)
 534                 server = NFS_SERVER(place_holder);
 535         else
 536                 server = list_entry_rcu(clp->cl_superblocks.next,
 537                                         struct nfs_server, client_link);
 538         list_for_each_entry_from_rcu(server, &clp->cl_superblocks, client_link) {
 539                 delegation = NULL;
 540                 if (place_holder && server == NFS_SERVER(place_holder))
 541                         delegation = rcu_dereference(NFS_I(place_holder)->delegation);
 542                 if (!delegation || delegation != place_holder_deleg)
 543                         delegation = list_entry_rcu(server->delegations.next,
 544                                                     struct nfs_delegation, super_list);
 545                 list_for_each_entry_from_rcu(delegation, &server->delegations, super_list) {
 546                         struct inode *to_put = NULL;
 547
 548                         if (!nfs_delegation_need_return(delegation)) {
 549                                 prev = delegation;
 550                                 continue;
 551                         }
 552                         if (!nfs_sb_active(server->super))
 553                                 break; /* continue in outer loop */
 554
 555                         if (prev) {
 556                                 struct inode *tmp;
 557
 558                                 tmp = nfs_delegation_grab_inode(prev);
 559                                 if (tmp) {
 560                                         to_put = place_holder;
 561                                         place_holder = tmp;
 562                                         place_holder_deleg = prev;
 563                                 }
 564                         }
 565
 566                         inode = nfs_delegation_grab_inode(delegation);
 567                         if (inode == NULL) {
 568                                 rcu_read_unlock();
 569                                 if (to_put)
 570                                         iput(to_put);
 571                                 nfs_sb_deactive(server->super);
 572                                 goto restart;
 573                         }
 574                         delegation = nfs_start_delegation_return_locked(NFS_I(inode));
 575                         rcu_read_unlock();
 576
 577                         if (to_put)
 578                                 iput(to_put);
 579
 580                         err = nfs_end_delegation_return(inode, delegation, 0);
 581                         iput(inode);
 582                         nfs_sb_deactive(server->super);
 583                         cond_resched();
 584                         if (!err)
 585                                 goto restart;
 586                         set_bit(NFS4CLNT_DELEGRETURN, &clp->cl_state);
 587                         if (place_holder)
 588                                 iput(place_holder);
 589                         return err;
 590                 }
 591         }
 592         rcu_read_unlock();
 593         if (place_holder)
 594                 iput(place_holder);
 595         return 0;
 596 }
 597
 598 /**
 599  * nfs_inode_evict_delegation - return delegation, don't reclaim opens
 600  * @inode: inode to process
 601  *
 602  * Does not protect against delegation reclaims, therefore really only safe
 603  * to be called from nfs4_clear_inode(). Guaranteed to always free
 604  * the delegation structure.
 605  */
 606 void nfs_inode_evict_delegation(struct inode *inode)
 607 {
 608         struct nfs_delegation *delegation;
 609
 610         delegation = nfs_inode_detach_delegation(inode);
 611         if (delegation != NULL) {
 612                 set_bit(NFS_DELEGATION_RETURNING, &delegation->flags);
 613                 set_bit(NFS_DELEGATION_INODE_FREEING, &delegation->flags);
 614                 nfs_do_return_delegation(inode, delegation, 1);
 615                 nfs_free_delegation(delegation);
 616         }
 617 }
 618
 619 /**
 620  * nfs_inode_return_delegation - synchronously return a delegation
 621  * @inode: inode to process
 622  *
 623  * This routine will always flush any dirty data to disk on the
 624  * assumption that if we need to return the delegation, then
 625  * we should stop caching.
 626  *
 627  * Returns zero on success, or a negative errno value.
 628  */
 629 int nfs4_inode_return_delegation(struct inode *inode)
 630 {
 631         struct nfs_inode *nfsi = NFS_I(inode);
 632         struct nfs_delegation *delegation;
 633         int err = 0;
 634
 635         nfs_wb_all(inode);
 636         delegation = nfs_start_delegation_return(nfsi);
 637         if (delegation != NULL)
 638                 err = nfs_end_delegation_return(inode, delegation, 1);
 639         return err;
 640 }
 641
 642 /**
 643  * nfs_inode_return_delegation_on_close - asynchronously return a delegation
 644  * @inode: inode to process
 645  *
 646  * This routine is called on file close in order to determine if the
 647  * inode delegation needs to be returned immediately.
 648  */
 649 void nfs4_inode_return_delegation_on_close(struct inode *inode)
 650 {
 651         struct nfs_delegation *delegation;
 652         struct nfs_delegation *ret = NULL;
 653
 654         if (!inode)
 655                 return;
 656         rcu_read_lock();
 657         delegation = nfs4_get_valid_delegation(inode);
 658         if (!delegation)
 659                 goto out;
 660         if (test_bit(NFS_DELEGATION_RETURN_IF_CLOSED, &delegation->flags)) {
 661                 spin_lock(&delegation->lock);
 662                 if (delegation->inode &&
 663                     list_empty(&NFS_I(inode)->open_files) &&
 664                     !test_and_set_bit(NFS_DELEGATION_RETURNING, &delegation->flags)) {
 665                         clear_bit(NFS_DELEGATION_RETURN_IF_CLOSED, &delegation->flags);
 666                         ret = delegation;
 667                 }
 668                 spin_unlock(&delegation->lock);
 669         }
 670 out:
 671         rcu_read_unlock();
 672         nfs_end_delegation_return(inode, ret, 0);
 673 }
 674
 675 /**
 676  * nfs4_inode_make_writeable
 677  * @inode: pointer to inode
 678  *
 679  * Make the inode writeable by returning the delegation if necessary
 680  *
 681  * Returns zero on success, or a negative errno value.
 682  */
 683 int nfs4_inode_make_writeable(struct inode *inode)
 684 {
 685         struct nfs_delegation *delegation;
 686
 687         rcu_read_lock();
 688         delegation = nfs4_get_valid_delegation(inode);
 689         if (delegation == NULL ||
 690             (nfs4_has_session(NFS_SERVER(inode)->nfs_client) &&
 691              (delegation->type & FMODE_WRITE))) {
 692                 rcu_read_unlock();
 693                 return 0;
 694         }
 695         rcu_read_unlock();
 696         return nfs4_inode_return_delegation(inode);
 697 }
 698
 699 static void nfs_mark_return_if_closed_delegation(struct nfs_server *server,
 700                 struct nfs_delegation *delegation)
 701 {
 702         set_bit(NFS_DELEGATION_RETURN_IF_CLOSED, &delegation->flags);
 703         set_bit(NFS4CLNT_DELEGRETURN, &server->nfs_client->cl_state);
 704 }
 705
 706 static void nfs_mark_return_delegation(struct nfs_server *server,
 707                 struct nfs_delegation *delegation)
 708 {
 709         set_bit(NFS_DELEGATION_RETURN, &delegation->flags);
 710         set_bit(NFS4CLNT_DELEGRETURN, &server->nfs_client->cl_state);
 711 }
 712
 713 static bool nfs_server_mark_return_all_delegations(struct nfs_server *server)
 714 {
 715         struct nfs_delegation *delegation;
 716         bool ret = false;
 717
 718         list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
 719                 nfs_mark_return_delegation(server, delegation);
 720                 ret = true;
 721         }
 722         return ret;
 723 }
 724
 725 static void nfs_client_mark_return_all_delegations(struct nfs_client *clp)
 726 {
 727         struct nfs_server *server;
 728
 729         rcu_read_lock();
 730         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
 731                 nfs_server_mark_return_all_delegations(server);
 732         rcu_read_unlock();
 733 }
 734
 735 static void nfs_delegation_run_state_manager(struct nfs_client *clp)
 736 {
 737         if (test_bit(NFS4CLNT_DELEGRETURN, &clp->cl_state))
 738                 nfs4_schedule_state_manager(clp);
 739 }
 740
 741 /**
 742  * nfs_expire_all_delegations
 743  * @clp: client to process
 744  *
 745  */
 746 void nfs_expire_all_delegations(struct nfs_client *clp)
 747 {
 748         nfs_client_mark_return_all_delegations(clp);
 749         nfs_delegation_run_state_manager(clp);
 750 }
 751
 752 /**
 753  * nfs_super_return_all_delegations - return delegations for one superblock
 754  * @server: pointer to nfs_server to process
 755  *
 756  */
 757 void nfs_server_return_all_delegations(struct nfs_server *server)
 758 {
 759         struct nfs_client *clp = server->nfs_client;
 760         bool need_wait;
 761
 762         if (clp == NULL)
 763                 return;
 764
 765         rcu_read_lock();
 766         need_wait = nfs_server_mark_return_all_delegations(server);
 767         rcu_read_unlock();
 768
 769         if (need_wait) {
 770                 nfs4_schedule_state_manager(clp);
 771                 nfs4_wait_clnt_recover(clp);
 772         }
 773 }
 774
 775 static void nfs_mark_return_unused_delegation_types(struct nfs_server *server,
 776                                                  fmode_t flags)
 777 {
 778         struct nfs_delegation *delegation;
 779
 780         list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
 781                 if ((delegation->type == (FMODE_READ|FMODE_WRITE)) && !(flags & FMODE_WRITE))
 782                         continue;
 783                 if (delegation->type & flags)
 784                         nfs_mark_return_if_closed_delegation(server, delegation);
 785         }
 786 }
 787
 788 static void nfs_client_mark_return_unused_delegation_types(struct nfs_client *clp,
 789                                                         fmode_t flags)
 790 {
 791         struct nfs_server *server;
 792
 793         rcu_read_lock();
 794         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
 795                 nfs_mark_return_unused_delegation_types(server, flags);
 796         rcu_read_unlock();
 797 }
 798
 799 static void nfs_mark_delegation_revoked(struct nfs_server *server,
 800                 struct nfs_delegation *delegation)
 801 {
 802         set_bit(NFS_DELEGATION_REVOKED, &delegation->flags);
 803         delegation->stateid.type = NFS4_INVALID_STATEID_TYPE;
 804 }
 805
 806 static void nfs_revoke_delegation(struct inode *inode,
 807                 const nfs4_stateid *stateid)
 808 {
 809         struct nfs_delegation *delegation;
 810         nfs4_stateid tmp;
 811         bool ret = false;
 812
 813         rcu_read_lock();
 814         delegation = rcu_dereference(NFS_I(inode)->delegation);
 815         if (delegation == NULL)
 816                 goto out;
 817         if (stateid == NULL) {
 818                 nfs4_stateid_copy(&tmp, &delegation->stateid);
 819                 stateid = &tmp;
 820         } else {
 821                 if (!nfs4_stateid_match_other(stateid, &delegation->stateid))
 822                         goto out;
 823                 spin_lock(&delegation->lock);
 824                 if (stateid->seqid) {
 825                         if (nfs4_stateid_is_newer(&delegation->stateid, stateid)) {
 826                                 spin_unlock(&delegation->lock);
 827                                 goto out;
 828                         }
 829                         delegation->stateid.seqid = stateid->seqid;
 830                 }
 831                 spin_unlock(&delegation->lock);
 832         }
 833         nfs_mark_delegation_revoked(NFS_SERVER(inode), delegation);
 834         ret = true;
 835 out:
 836         rcu_read_unlock();
 837         if (ret)
 838                 nfs_inode_find_state_and_recover(inode, stateid);
 839 }
 840
 841 void nfs_remove_bad_delegation(struct inode *inode,
 842                 const nfs4_stateid *stateid)
 843 {
 844         nfs_revoke_delegation(inode, stateid);
 845 }
 846 EXPORT_SYMBOL_GPL(nfs_remove_bad_delegation);
 847
 848 void nfs_delegation_mark_returned(struct inode *inode,
 849                 const nfs4_stateid *stateid)
 850 {
 851         struct nfs_delegation *delegation;
 852
 853         if (!inode)
 854                 return;
 855
 856         rcu_read_lock();
 857         delegation = rcu_dereference(NFS_I(inode)->delegation);
 858         if (!delegation)
 859                 goto out_rcu_unlock;
 860
 861         spin_lock(&delegation->lock);
 862         if (!nfs4_stateid_match_other(stateid, &delegation->stateid))
 863                 goto out_spin_unlock;
 864         if (stateid->seqid) {
 865                 /* If delegation->stateid is newer, dont mark as returned */
 866                 if (nfs4_stateid_is_newer(&delegation->stateid, stateid))
 867                         goto out_clear_returning;
 868                 if (delegation->stateid.seqid != stateid->seqid)
 869                         delegation->stateid.seqid = stateid->seqid;
 870         }
 871
 872         nfs_mark_delegation_revoked(NFS_SERVER(inode), delegation);
 873
 874 out_clear_returning:
 875         clear_bit(NFS_DELEGATION_RETURNING, &delegation->flags);
 876 out_spin_unlock:
 877         spin_unlock(&delegation->lock);
 878 out_rcu_unlock:
 879         rcu_read_unlock();
 880
 881         nfs_inode_find_state_and_recover(inode, stateid);
 882 }
 883
 884 /**
 885  * nfs_expire_unused_delegation_types
 886  * @clp: client to process
 887  * @flags: delegation types to expire
 888  *
 889  */
 890 void nfs_expire_unused_delegation_types(struct nfs_client *clp, fmode_t flags)
 891 {
 892         nfs_client_mark_return_unused_delegation_types(clp, flags);
 893         nfs_delegation_run_state_manager(clp);
 894 }
 895
 896 static void nfs_mark_return_unreferenced_delegations(struct nfs_server *server)
 897 {
 898         struct nfs_delegation *delegation;
 899
 900         list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
 901                 if (test_and_clear_bit(NFS_DELEGATION_REFERENCED, &delegation->flags))
 902                         continue;
 903                 nfs_mark_return_if_closed_delegation(server, delegation);
 904         }
 905 }
 906
 907 /**
 908  * nfs_expire_unreferenced_delegations - Eliminate unused delegations
 909  * @clp: nfs_client to process
 910  *
 911  */
 912 void nfs_expire_unreferenced_delegations(struct nfs_client *clp)
 913 {
 914         struct nfs_server *server;
 915
 916         rcu_read_lock();
 917         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
 918                 nfs_mark_return_unreferenced_delegations(server);
 919         rcu_read_unlock();
 920
 921         nfs_delegation_run_state_manager(clp);
 922 }
 923
 924 /**
 925  * nfs_async_inode_return_delegation - asynchronously return a delegation
 926  * @inode: inode to process
 927  * @stateid: state ID information
 928  *
 929  * Returns zero on success, or a negative errno value.
 930  */
 931 int nfs_async_inode_return_delegation(struct inode *inode,
 932                                       const nfs4_stateid *stateid)
 933 {
 934         struct nfs_server *server = NFS_SERVER(inode);
 935         struct nfs_client *clp = server->nfs_client;
 936         struct nfs_delegation *delegation;
 937
 938         rcu_read_lock();
 939         delegation = nfs4_get_valid_delegation(inode);
 940         if (delegation == NULL)
 941                 goto out_enoent;
 942         if (stateid != NULL &&
 943             !clp->cl_mvops->match_stateid(&delegation->stateid, stateid))
 944                 goto out_enoent;
 945         nfs_mark_return_delegation(server, delegation);
 946         rcu_read_unlock();
 947
 948         nfs_delegation_run_state_manager(clp);
 949         return 0;
 950 out_enoent:
 951         rcu_read_unlock();
 952         return -ENOENT;
 953 }
 954
 955 static struct inode *
 956 nfs_delegation_find_inode_server(struct nfs_server *server,
 957                                  const struct nfs_fh *fhandle)
 958 {
 959         struct nfs_delegation *delegation;
 960         struct inode *freeme, *res = NULL;
 961
 962         list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
 963                 spin_lock(&delegation->lock);
 964                 if (delegation->inode != NULL &&
 965                     !test_bit(NFS_DELEGATION_REVOKED, &delegation->flags) &&
 966                     nfs_compare_fh(fhandle, &NFS_I(delegation->inode)->fh) == 0) {
 967                         freeme = igrab(delegation->inode);
 968                         if (freeme && nfs_sb_active(freeme->i_sb))
 969                                 res = freeme;
 970                         spin_unlock(&delegation->lock);
 971                         if (res != NULL)
 972                                 return res;
 973                         if (freeme) {
 974                                 rcu_read_unlock();
 975                                 iput(freeme);
 976                                 rcu_read_lock();
 977                         }
 978                         return ERR_PTR(-EAGAIN);
 979                 }
 980                 spin_unlock(&delegation->lock);
 981         }
 982         return ERR_PTR(-ENOENT);
 983 }
 984
 985 /**
 986  * nfs_delegation_find_inode - retrieve the inode associated with a delegation
 987  * @clp: client state handle
 988  * @fhandle: filehandle from a delegation recall
 989  *
 990  * Returns pointer to inode matching "fhandle," or NULL if a matching inode
 991  * cannot be found.
 992  */
 993 struct inode *nfs_delegation_find_inode(struct nfs_client *clp,
 994                                         const struct nfs_fh *fhandle)
 995 {
 996         struct nfs_server *server;
 997         struct inode *res;
 998
 999         rcu_read_lock();
1000         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link) {
1001                 res = nfs_delegation_find_inode_server(server, fhandle);
1002                 if (res != ERR_PTR(-ENOENT)) {
1003                         rcu_read_unlock();
1004                         return res;
1005                 }
1006         }
1007         rcu_read_unlock();
1008         return ERR_PTR(-ENOENT);
1009 }
1010
1011 static void nfs_delegation_mark_reclaim_server(struct nfs_server *server)
1012 {
1013         struct nfs_delegation *delegation;
1014
1015         list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
1016                 /*
1017                  * If the delegation may have been admin revoked, then we
1018                  * cannot reclaim it.
1019                  */
1020                 if (test_bit(NFS_DELEGATION_TEST_EXPIRED, &delegation->flags))
1021                         continue;
1022                 set_bit(NFS_DELEGATION_NEED_RECLAIM, &delegation->flags);
1023         }
1024 }
1025
1026 /**
1027  * nfs_delegation_mark_reclaim - mark all delegations as needing to be reclaimed
1028  * @clp: nfs_client to process
1029  *
1030  */
1031 void nfs_delegation_mark_reclaim(struct nfs_client *clp)
1032 {
1033         struct nfs_server *server;
1034
1035         rcu_read_lock();
1036         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
1037                 nfs_delegation_mark_reclaim_server(server);
1038         rcu_read_unlock();
1039 }
1040
1041 /**
1042  * nfs_delegation_reap_unclaimed - reap unclaimed delegations after reboot recovery is done
1043  * @clp: nfs_client to process
1044  *
1045  */
1046 void nfs_delegation_reap_unclaimed(struct nfs_client *clp)
1047 {
1048         struct nfs_delegation *delegation;
1049         struct nfs_server *server;
1050         struct inode *inode;
1051
1052 restart:
1053         rcu_read_lock();
1054         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link) {
1055                 list_for_each_entry_rcu(delegation, &server->delegations,
1056                                                                 super_list) {
1057                         if (test_bit(NFS_DELEGATION_INODE_FREEING,
1058                                                 &delegation->flags) ||
1059                             test_bit(NFS_DELEGATION_RETURNING,
1060                                                 &delegation->flags) ||
1061                             test_bit(NFS_DELEGATION_NEED_RECLAIM,
1062                                                 &delegation->flags) == 0)
1063                                 continue;
1064                         if (!nfs_sb_active(server->super))
1065                                 break; /* continue in outer loop */
1066                         inode = nfs_delegation_grab_inode(delegation);
1067                         if (inode == NULL) {
1068                                 rcu_read_unlock();
1069                                 nfs_sb_deactive(server->super);
1070                                 goto restart;
1071                         }
1072                         delegation = nfs_start_delegation_return_locked(NFS_I(inode));
1073                         rcu_read_unlock();
1074                         if (delegation != NULL) {
1075                                 delegation = nfs_detach_delegation(NFS_I(inode),
1076                                         delegation, server);
1077                                 if (delegation != NULL)
1078                                         nfs_free_delegation(delegation);
1079                         }
1080                         iput(inode);
1081                         nfs_sb_deactive(server->super);
1082                         cond_resched();
1083                         goto restart;
1084                 }
1085         }
1086         rcu_read_unlock();
1087 }
1088
1089 static inline bool nfs4_server_rebooted(const struct nfs_client *clp)
1090 {
1091         return (clp->cl_state & (BIT(NFS4CLNT_CHECK_LEASE) |
1092                                 BIT(NFS4CLNT_LEASE_EXPIRED) |
1093                                 BIT(NFS4CLNT_SESSION_RESET))) != 0;
1094 }
1095
1096 static void nfs_mark_test_expired_delegation(struct nfs_server *server,
1097             struct nfs_delegation *delegation)
1098 {
1099         if (delegation->stateid.type == NFS4_INVALID_STATEID_TYPE)
1100                 return;
1101         clear_bit(NFS_DELEGATION_NEED_RECLAIM, &delegation->flags);
1102         set_bit(NFS_DELEGATION_TEST_EXPIRED, &delegation->flags);
1103         set_bit(NFS4CLNT_DELEGATION_EXPIRED, &server->nfs_client->cl_state);
1104 }
1105
1106 static void nfs_inode_mark_test_expired_delegation(struct nfs_server *server,
1107                 struct inode *inode)
1108 {
1109         struct nfs_delegation *delegation;
1110
1111         rcu_read_lock();
1112         delegation = rcu_dereference(NFS_I(inode)->delegation);
1113         if (delegation)
1114                 nfs_mark_test_expired_delegation(server, delegation);
1115         rcu_read_unlock();
1116
1117 }
1118
1119 static void nfs_delegation_mark_test_expired_server(struct nfs_server *server)
1120 {
1121         struct nfs_delegation *delegation;
1122
1123         list_for_each_entry_rcu(delegation, &server->delegations, super_list)
1124                 nfs_mark_test_expired_delegation(server, delegation);
1125 }
1126
1127 /**
1128  * nfs_mark_test_expired_all_delegations - mark all delegations for testing
1129  * @clp: nfs_client to process
1130  *
1131  * Iterates through all the delegations associated with this server and
1132  * marks them as needing to be checked for validity.
1133  */
1134 void nfs_mark_test_expired_all_delegations(struct nfs_client *clp)
1135 {
1136         struct nfs_server *server;
1137
1138         rcu_read_lock();
1139         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
1140                 nfs_delegation_mark_test_expired_server(server);
1141         rcu_read_unlock();
1142 }
1143
1144 /**
1145  * nfs_test_expired_all_delegations - test all delegations for a client
1146  * @clp: nfs_client to process
1147  *
1148  * Helper for handling "recallable state revoked" status from server.
1149  */
1150 void nfs_test_expired_all_delegations(struct nfs_client *clp)
1151 {
1152         nfs_mark_test_expired_all_delegations(clp);
1153         nfs4_schedule_state_manager(clp);
1154 }
1155
1156 static void
1157 nfs_delegation_test_free_expired(struct inode *inode,
1158                 nfs4_stateid *stateid,
1159                 const struct cred *cred)
1160 {
1161         struct nfs_server *server = NFS_SERVER(inode);
1162         const struct nfs4_minor_version_ops *ops = server->nfs_client->cl_mvops;
1163         int status;
1164
1165         if (!cred)
1166                 return;
1167         status = ops->test_and_free_expired(server, stateid, cred);
1168         if (status == -NFS4ERR_EXPIRED || status == -NFS4ERR_BAD_STATEID)
1169                 nfs_remove_bad_delegation(inode, stateid);
1170 }
1171
1172 /**
1173  * nfs_reap_expired_delegations - reap expired delegations
1174  * @clp: nfs_client to process
1175  *
1176  * Iterates through all the delegations associated with this server and
1177  * checks if they have may have been revoked. This function is usually
1178  * expected to be called in cases where the server may have lost its
1179  * lease.
1180  */
1181 void nfs_reap_expired_delegations(struct nfs_client *clp)
1182 {
1183         struct nfs_delegation *delegation;
1184         struct nfs_server *server;
1185         struct inode *inode;
1186         const struct cred *cred;
1187         nfs4_stateid stateid;
1188
1189 restart:
1190         rcu_read_lock();
1191         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link) {
1192                 list_for_each_entry_rcu(delegation, &server->delegations,
1193                                                                 super_list) {
1194                         if (test_bit(NFS_DELEGATION_INODE_FREEING,
1195                                                 &delegation->flags) ||
1196                             test_bit(NFS_DELEGATION_RETURNING,
1197                                                 &delegation->flags) ||
1198                             test_bit(NFS_DELEGATION_TEST_EXPIRED,
1199                                                 &delegation->flags) == 0)
1200                                 continue;
1201                         if (!nfs_sb_active(server->super))
1202                                 break; /* continue in outer loop */
1203                         inode = nfs_delegation_grab_inode(delegation);
1204                         if (inode == NULL) {
1205                                 rcu_read_unlock();
1206                                 nfs_sb_deactive(server->super);
1207                                 goto restart;
1208                         }
1209                         cred = get_cred_rcu(delegation->cred);
1210                         nfs4_stateid_copy(&stateid, &delegation->stateid);
1211                         clear_bit(NFS_DELEGATION_TEST_EXPIRED, &delegation->flags);
1212                         rcu_read_unlock();
1213                         nfs_delegation_test_free_expired(inode, &stateid, cred);
1214                         put_cred(cred);
1215                         if (nfs4_server_rebooted(clp)) {
1216                                 nfs_inode_mark_test_expired_delegation(server,inode);
1217                                 iput(inode);
1218                                 nfs_sb_deactive(server->super);
1219                                 return;
1220                         }
1221                         iput(inode);
1222                         nfs_sb_deactive(server->super);
1223                         cond_resched();
1224                         goto restart;
1225                 }
1226         }
1227         rcu_read_unlock();
1228 }
1229
1230 void nfs_inode_find_delegation_state_and_recover(struct inode *inode,
1231                 const nfs4_stateid *stateid)
1232 {
1233         struct nfs_client *clp = NFS_SERVER(inode)->nfs_client;
1234         struct nfs_delegation *delegation;
1235         bool found = false;
1236
1237         rcu_read_lock();
1238         delegation = rcu_dereference(NFS_I(inode)->delegation);
1239         if (delegation &&
1240             nfs4_stateid_match_or_older(&delegation->stateid, stateid) &&
1241             !test_bit(NFS_DELEGATION_REVOKED, &delegation->flags)) {
1242                 nfs_mark_test_expired_delegation(NFS_SERVER(inode), delegation);
1243                 found = true;
1244         }
1245         rcu_read_unlock();
1246         if (found)
1247                 nfs4_schedule_state_manager(clp);
1248 }
1249
1250 /**
1251  * nfs_delegations_present - check for existence of delegations
1252  * @clp: client state handle
1253  *
1254  * Returns one if there are any nfs_delegation structures attached
1255  * to this nfs_client.
1256  */
1257 int nfs_delegations_present(struct nfs_client *clp)
1258 {
1259         struct nfs_server *server;
1260         int ret = 0;
1261
1262         rcu_read_lock();
1263         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
1264                 if (!list_empty(&server->delegations)) {
1265                         ret = 1;
1266                         break;
1267                 }
1268         rcu_read_unlock();
1269         return ret;
1270 }
1271
1272 /**
1273  * nfs4_refresh_delegation_stateid - Update delegation stateid seqid
1274  * @dst: stateid to refresh
1275  * @inode: inode to check
1276  *
1277  * Returns "true" and updates "dst->seqid" * if inode had a delegation
1278  * that matches our delegation stateid. Otherwise "false" is returned.
1279  */
1280 bool nfs4_refresh_delegation_stateid(nfs4_stateid *dst, struct inode *inode)
1281 {
1282         struct nfs_delegation *delegation;
1283         bool ret = false;
1284         if (!inode)
1285                 goto out;
1286
1287         rcu_read_lock();
1288         delegation = rcu_dereference(NFS_I(inode)->delegation);
1289         if (delegation != NULL &&
1290             nfs4_stateid_match_other(dst, &delegation->stateid) &&
1291             nfs4_stateid_is_newer(&delegation->stateid, dst) &&
1292             !test_bit(NFS_DELEGATION_REVOKED, &delegation->flags)) {
1293                 dst->seqid = delegation->stateid.seqid;
1294                 ret = true;
1295         }
1296         rcu_read_unlock();
1297 out:
1298         return ret;
1299 }
1300
1301 /**
1302  * nfs4_copy_delegation_stateid - Copy inode's state ID information
1303  * @inode: inode to check
1304  * @flags: delegation type requirement
1305  * @dst: stateid data structure to fill in
1306  * @cred: optional argument to retrieve credential
1307  *
1308  * Returns "true" and fills in "dst->data" * if inode had a delegation,
1309  * otherwise "false" is returned.
1310  */
1311 bool nfs4_copy_delegation_stateid(struct inode *inode, fmode_t flags,
1312                 nfs4_stateid *dst, const struct cred **cred)
1313 {
1314         struct nfs_inode *nfsi = NFS_I(inode);
1315         struct nfs_delegation *delegation;
1316         bool ret;
1317
1318         flags &= FMODE_READ|FMODE_WRITE;
1319         rcu_read_lock();
1320         delegation = rcu_dereference(nfsi->delegation);
1321         ret = nfs4_is_valid_delegation(delegation, flags);
1322         if (ret) {
1323                 nfs4_stateid_copy(dst, &delegation->stateid);
1324                 nfs_mark_delegation_referenced(delegation);
1325                 if (cred)
1326                         *cred = get_cred(delegation->cred);
1327         }
1328         rcu_read_unlock();
1329         return ret;
1330 }
1331
1332 /**
1333  * nfs4_delegation_flush_on_close - Check if we must flush file on close
1334  * @inode: inode to check
1335  *
1336  * This function checks the number of outstanding writes to the file
1337  * against the delegation 'space_limit' field to see if
1338  * the spec requires us to flush the file on close.
1339  */
1340 bool nfs4_delegation_flush_on_close(const struct inode *inode)
1341 {
1342         struct nfs_inode *nfsi = NFS_I(inode);
1343         struct nfs_delegation *delegation;
1344         bool ret = true;
1345
1346         rcu_read_lock();
1347         delegation = rcu_dereference(nfsi->delegation);
1348         if (delegation == NULL || !(delegation->type & FMODE_WRITE))
1349                 goto out;
1350         if (atomic_long_read(&nfsi->nrequests) < delegation->pagemod_limit)
1351                 ret = false;
1352 out:
1353         rcu_read_unlock();
1354         return ret;
1355 }