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 #define NFS_DEFAULT_DELEGATION_WATERMARK (5000U)
  29
  30 static atomic_long_t nfs_active_delegations;
  31 static unsigned nfs_delegation_watermark = NFS_DEFAULT_DELEGATION_WATERMARK;
  32
  33 static void __nfs_free_delegation(struct nfs_delegation *delegation)
  34 {
  35         put_cred(delegation->cred);
  36         delegation->cred = NULL;
  37         kfree_rcu(delegation, rcu);
  38 }
  39
  40 static void nfs_mark_delegation_revoked(struct nfs_delegation *delegation)
  41 {
  42         if (!test_and_set_bit(NFS_DELEGATION_REVOKED, &delegation->flags)) {
  43                 delegation->stateid.type = NFS4_INVALID_STATEID_TYPE;
  44                 atomic_long_dec(&nfs_active_delegations);
  45                 if (!test_bit(NFS_DELEGATION_RETURNING, &delegation->flags))
  46                         nfs_clear_verifier_delegated(delegation->inode);
  47         }
  48 }
  49
  50 static struct nfs_delegation *nfs_get_delegation(struct nfs_delegation *delegation)
  51 {
  52         refcount_inc(&delegation->refcount);
  53         return delegation;
  54 }
  55
  56 static void nfs_put_delegation(struct nfs_delegation *delegation)
  57 {
  58         if (refcount_dec_and_test(&delegation->refcount))
  59                 __nfs_free_delegation(delegation);
  60 }
  61
  62 static void nfs_free_delegation(struct nfs_delegation *delegation)
  63 {
  64         nfs_mark_delegation_revoked(delegation);
  65         nfs_put_delegation(delegation);
  66 }
  67
  68 /**
  69  * nfs_mark_delegation_referenced - set delegation's REFERENCED flag
  70  * @delegation: delegation to process
  71  *
  72  */
  73 void nfs_mark_delegation_referenced(struct nfs_delegation *delegation)
  74 {
  75         set_bit(NFS_DELEGATION_REFERENCED, &delegation->flags);
  76 }
  77
  78 static bool
  79 nfs4_is_valid_delegation(const struct nfs_delegation *delegation,
  80                 fmode_t flags)
  81 {
  82         if (delegation != NULL && (delegation->type & flags) == flags &&
  83             !test_bit(NFS_DELEGATION_REVOKED, &delegation->flags) &&
  84             !test_bit(NFS_DELEGATION_RETURNING, &delegation->flags))
  85                 return true;
  86         return false;
  87 }
  88
  89 struct nfs_delegation *nfs4_get_valid_delegation(const struct inode *inode)
  90 {
  91         struct nfs_delegation *delegation;
  92
  93         delegation = rcu_dereference(NFS_I(inode)->delegation);
  94         if (nfs4_is_valid_delegation(delegation, 0))
  95                 return delegation;
  96         return NULL;
  97 }
  98
  99 static int
 100 nfs4_do_check_delegation(struct inode *inode, fmode_t flags, bool mark)
 101 {
 102         struct nfs_delegation *delegation;
 103         int ret = 0;
 104
 105         flags &= FMODE_READ|FMODE_WRITE;
 106         rcu_read_lock();
 107         delegation = rcu_dereference(NFS_I(inode)->delegation);
 108         if (nfs4_is_valid_delegation(delegation, flags)) {
 109                 if (mark)
 110                         nfs_mark_delegation_referenced(delegation);
 111                 ret = 1;
 112         }
 113         rcu_read_unlock();
 114         return ret;
 115 }
 116 /**
 117  * nfs_have_delegation - check if inode has a delegation, mark it
 118  * NFS_DELEGATION_REFERENCED if there is one.
 119  * @inode: inode to check
 120  * @flags: delegation types to check for
 121  *
 122  * Returns one if inode has the indicated delegation, otherwise zero.
 123  */
 124 int nfs4_have_delegation(struct inode *inode, fmode_t flags)
 125 {
 126         return nfs4_do_check_delegation(inode, flags, true);
 127 }
 128
 129 /*
 130  * nfs4_check_delegation - check if inode has a delegation, do not mark
 131  * NFS_DELEGATION_REFERENCED if it has one.
 132  */
 133 int nfs4_check_delegation(struct inode *inode, fmode_t flags)
 134 {
 135         return nfs4_do_check_delegation(inode, flags, false);
 136 }
 137
 138 static int nfs_delegation_claim_locks(struct nfs4_state *state, const nfs4_stateid *stateid)
 139 {
 140         struct inode *inode = state->inode;
 141         struct file_lock *fl;
 142         struct file_lock_context *flctx = inode->i_flctx;
 143         struct list_head *list;
 144         int status = 0;
 145
 146         if (flctx == NULL)
 147                 goto out;
 148
 149         list = &flctx->flc_posix;
 150         spin_lock(&flctx->flc_lock);
 151 restart:
 152         list_for_each_entry(fl, list, fl_list) {
 153                 if (nfs_file_open_context(fl->fl_file)->state != state)
 154                         continue;
 155                 spin_unlock(&flctx->flc_lock);
 156                 status = nfs4_lock_delegation_recall(fl, state, stateid);
 157                 if (status < 0)
 158                         goto out;
 159                 spin_lock(&flctx->flc_lock);
 160         }
 161         if (list == &flctx->flc_posix) {
 162                 list = &flctx->flc_flock;
 163                 goto restart;
 164         }
 165         spin_unlock(&flctx->flc_lock);
 166 out:
 167         return status;
 168 }
 169
 170 static int nfs_delegation_claim_opens(struct inode *inode,
 171                 const nfs4_stateid *stateid, fmode_t type)
 172 {
 173         struct nfs_inode *nfsi = NFS_I(inode);
 174         struct nfs_open_context *ctx;
 175         struct nfs4_state_owner *sp;
 176         struct nfs4_state *state;
 177         unsigned int seq;
 178         int err;
 179
 180 again:
 181         rcu_read_lock();
 182         list_for_each_entry_rcu(ctx, &nfsi->open_files, list) {
 183                 state = ctx->state;
 184                 if (state == NULL)
 185                         continue;
 186                 if (!test_bit(NFS_DELEGATED_STATE, &state->flags))
 187                         continue;
 188                 if (!nfs4_valid_open_stateid(state))
 189                         continue;
 190                 if (!nfs4_stateid_match(&state->stateid, stateid))
 191                         continue;
 192                 if (!get_nfs_open_context(ctx))
 193                         continue;
 194                 rcu_read_unlock();
 195                 sp = state->owner;
 196                 /* Block nfs4_proc_unlck */
 197                 mutex_lock(&sp->so_delegreturn_mutex);
 198                 seq = raw_seqcount_begin(&sp->so_reclaim_seqcount);
 199                 err = nfs4_open_delegation_recall(ctx, state, stateid);
 200                 if (!err)
 201                         err = nfs_delegation_claim_locks(state, stateid);
 202                 if (!err && read_seqcount_retry(&sp->so_reclaim_seqcount, seq))
 203                         err = -EAGAIN;
 204                 mutex_unlock(&sp->so_delegreturn_mutex);
 205                 put_nfs_open_context(ctx);
 206                 if (err != 0)
 207                         return err;
 208                 goto again;
 209         }
 210         rcu_read_unlock();
 211         return 0;
 212 }
 213
 214 /**
 215  * nfs_inode_reclaim_delegation - process a delegation reclaim request
 216  * @inode: inode to process
 217  * @cred: credential to use for request
 218  * @type: delegation type
 219  * @stateid: delegation stateid
 220  * @pagemod_limit: write delegation "space_limit"
 221  *
 222  */
 223 void nfs_inode_reclaim_delegation(struct inode *inode, const struct cred *cred,
 224                                   fmode_t type,
 225                                   const nfs4_stateid *stateid,
 226                                   unsigned long pagemod_limit)
 227 {
 228         struct nfs_delegation *delegation;
 229         const struct cred *oldcred = NULL;
 230
 231         rcu_read_lock();
 232         delegation = rcu_dereference(NFS_I(inode)->delegation);
 233         if (delegation != NULL) {
 234                 spin_lock(&delegation->lock);
 235                 if (nfs4_is_valid_delegation(delegation, 0)) {
 236                         nfs4_stateid_copy(&delegation->stateid, stateid);
 237                         delegation->type = type;
 238                         delegation->pagemod_limit = pagemod_limit;
 239                         oldcred = delegation->cred;
 240                         delegation->cred = get_cred(cred);
 241                         clear_bit(NFS_DELEGATION_NEED_RECLAIM,
 242                                   &delegation->flags);
 243                         spin_unlock(&delegation->lock);
 244                         rcu_read_unlock();
 245                         put_cred(oldcred);
 246                         trace_nfs4_reclaim_delegation(inode, type);
 247                         return;
 248                 }
 249                 /* We appear to have raced with a delegation return. */
 250                 spin_unlock(&delegation->lock);
 251         }
 252         rcu_read_unlock();
 253         nfs_inode_set_delegation(inode, cred, type, stateid, pagemod_limit);
 254 }
 255
 256 static int nfs_do_return_delegation(struct inode *inode, struct nfs_delegation *delegation, int issync)
 257 {
 258         int res = 0;
 259
 260         if (!test_bit(NFS_DELEGATION_REVOKED, &delegation->flags))
 261                 res = nfs4_proc_delegreturn(inode,
 262                                 delegation->cred,
 263                                 &delegation->stateid,
 264                                 issync);
 265         return res;
 266 }
 267
 268 static struct inode *nfs_delegation_grab_inode(struct nfs_delegation *delegation)
 269 {
 270         struct inode *inode = NULL;
 271
 272         spin_lock(&delegation->lock);
 273         if (delegation->inode != NULL)
 274                 inode = igrab(delegation->inode);
 275         if (!inode)
 276                 set_bit(NFS_DELEGATION_INODE_FREEING, &delegation->flags);
 277         spin_unlock(&delegation->lock);
 278         return inode;
 279 }
 280
 281 static struct nfs_delegation *
 282 nfs_start_delegation_return_locked(struct nfs_inode *nfsi)
 283 {
 284         struct nfs_delegation *ret = NULL;
 285         struct nfs_delegation *delegation = rcu_dereference(nfsi->delegation);
 286
 287         if (delegation == NULL)
 288                 goto out;
 289         spin_lock(&delegation->lock);
 290         if (!test_and_set_bit(NFS_DELEGATION_RETURNING, &delegation->flags)) {
 291                 /* Refcount matched in nfs_end_delegation_return() */
 292                 ret = nfs_get_delegation(delegation);
 293         }
 294         spin_unlock(&delegation->lock);
 295         if (ret)
 296                 nfs_clear_verifier_delegated(&nfsi->vfs_inode);
 297 out:
 298         return ret;
 299 }
 300
 301 static struct nfs_delegation *
 302 nfs_start_delegation_return(struct nfs_inode *nfsi)
 303 {
 304         struct nfs_delegation *delegation;
 305
 306         rcu_read_lock();
 307         delegation = nfs_start_delegation_return_locked(nfsi);
 308         rcu_read_unlock();
 309         return delegation;
 310 }
 311
 312 static void
 313 nfs_abort_delegation_return(struct nfs_delegation *delegation,
 314                 struct nfs_client *clp)
 315 {
 316
 317         spin_lock(&delegation->lock);
 318         clear_bit(NFS_DELEGATION_RETURNING, &delegation->flags);
 319         set_bit(NFS_DELEGATION_RETURN, &delegation->flags);
 320         spin_unlock(&delegation->lock);
 321         set_bit(NFS4CLNT_DELEGRETURN, &clp->cl_state);
 322 }
 323
 324 static struct nfs_delegation *
 325 nfs_detach_delegation_locked(struct nfs_inode *nfsi,
 326                 struct nfs_delegation *delegation,
 327                 struct nfs_client *clp)
 328 {
 329         struct nfs_delegation *deleg_cur =
 330                 rcu_dereference_protected(nfsi->delegation,
 331                                 lockdep_is_held(&clp->cl_lock));
 332
 333         if (deleg_cur == NULL || delegation != deleg_cur)
 334                 return NULL;
 335
 336         spin_lock(&delegation->lock);
 337         if (!delegation->inode) {
 338                 spin_unlock(&delegation->lock);
 339                 return NULL;
 340         }
 341         list_del_rcu(&delegation->super_list);
 342         delegation->inode = NULL;
 343         rcu_assign_pointer(nfsi->delegation, NULL);
 344         spin_unlock(&delegation->lock);
 345         return delegation;
 346 }
 347
 348 static struct nfs_delegation *nfs_detach_delegation(struct nfs_inode *nfsi,
 349                 struct nfs_delegation *delegation,
 350                 struct nfs_server *server)
 351 {
 352         struct nfs_client *clp = server->nfs_client;
 353
 354         spin_lock(&clp->cl_lock);
 355         delegation = nfs_detach_delegation_locked(nfsi, delegation, clp);
 356         spin_unlock(&clp->cl_lock);
 357         return delegation;
 358 }
 359
 360 static struct nfs_delegation *
 361 nfs_inode_detach_delegation(struct inode *inode)
 362 {
 363         struct nfs_inode *nfsi = NFS_I(inode);
 364         struct nfs_server *server = NFS_SERVER(inode);
 365         struct nfs_delegation *delegation;
 366
 367         rcu_read_lock();
 368         delegation = rcu_dereference(nfsi->delegation);
 369         if (delegation != NULL)
 370                 delegation = nfs_detach_delegation(nfsi, delegation, server);
 371         rcu_read_unlock();
 372         return delegation;
 373 }
 374
 375 static void
 376 nfs_update_inplace_delegation(struct nfs_delegation *delegation,
 377                 const struct nfs_delegation *update)
 378 {
 379         if (nfs4_stateid_is_newer(&update->stateid, &delegation->stateid)) {
 380                 delegation->stateid.seqid = update->stateid.seqid;
 381                 smp_wmb();
 382                 delegation->type = update->type;
 383                 if (test_and_clear_bit(NFS_DELEGATION_REVOKED, &delegation->flags))
 384                         atomic_long_inc(&nfs_active_delegations);
 385         }
 386 }
 387
 388 /**
 389  * nfs_inode_set_delegation - set up a delegation on an inode
 390  * @inode: inode to which delegation applies
 391  * @cred: cred to use for subsequent delegation processing
 392  * @type: delegation type
 393  * @stateid: delegation stateid
 394  * @pagemod_limit: write delegation "space_limit"
 395  *
 396  * Returns zero on success, or a negative errno value.
 397  */
 398 int nfs_inode_set_delegation(struct inode *inode, const struct cred *cred,
 399                                   fmode_t type,
 400                                   const nfs4_stateid *stateid,
 401                                   unsigned long pagemod_limit)
 402 {
 403         struct nfs_server *server = NFS_SERVER(inode);
 404         struct nfs_client *clp = server->nfs_client;
 405         struct nfs_inode *nfsi = NFS_I(inode);
 406         struct nfs_delegation *delegation, *old_delegation;
 407         struct nfs_delegation *freeme = NULL;
 408         int status = 0;
 409
 410         delegation = kmalloc(sizeof(*delegation), GFP_NOFS);
 411         if (delegation == NULL)
 412                 return -ENOMEM;
 413         nfs4_stateid_copy(&delegation->stateid, stateid);
 414         refcount_set(&delegation->refcount, 1);
 415         delegation->type = type;
 416         delegation->pagemod_limit = pagemod_limit;
 417         delegation->change_attr = inode_peek_iversion_raw(inode);
 418         delegation->cred = get_cred(cred);
 419         delegation->inode = inode;
 420         delegation->flags = 1<<NFS_DELEGATION_REFERENCED;
 421         spin_lock_init(&delegation->lock);
 422
 423         spin_lock(&clp->cl_lock);
 424         old_delegation = rcu_dereference_protected(nfsi->delegation,
 425                                         lockdep_is_held(&clp->cl_lock));
 426         if (old_delegation == NULL)
 427                 goto add_new;
 428         /* Is this an update of the existing delegation? */
 429         if (nfs4_stateid_match_other(&old_delegation->stateid,
 430                                 &delegation->stateid)) {
 431                 spin_lock(&old_delegation->lock);
 432                 nfs_update_inplace_delegation(old_delegation,
 433                                 delegation);
 434                 spin_unlock(&old_delegation->lock);
 435                 goto out;
 436         }
 437         if (!test_bit(NFS_DELEGATION_REVOKED, &old_delegation->flags)) {
 438                 /*
 439                  * Deal with broken servers that hand out two
 440                  * delegations for the same file.
 441                  * Allow for upgrades to a WRITE delegation, but
 442                  * nothing else.
 443                  */
 444                 dfprintk(FILE, "%s: server %s handed out "
 445                                 "a duplicate delegation!\n",
 446                                 __func__, clp->cl_hostname);
 447                 if (delegation->type == old_delegation->type ||
 448                     !(delegation->type & FMODE_WRITE)) {
 449                         freeme = delegation;
 450                         delegation = NULL;
 451                         goto out;
 452                 }
 453                 if (test_and_set_bit(NFS_DELEGATION_RETURNING,
 454                                         &old_delegation->flags))
 455                         goto out;
 456         }
 457         freeme = nfs_detach_delegation_locked(nfsi, old_delegation, clp);
 458         if (freeme == NULL)
 459                 goto out;
 460 add_new:
 461         list_add_tail_rcu(&delegation->super_list, &server->delegations);
 462         rcu_assign_pointer(nfsi->delegation, delegation);
 463         delegation = NULL;
 464
 465         atomic_long_inc(&nfs_active_delegations);
 466
 467         trace_nfs4_set_delegation(inode, type);
 468
 469         spin_lock(&inode->i_lock);
 470         if (NFS_I(inode)->cache_validity & (NFS_INO_INVALID_ATTR|NFS_INO_INVALID_ATIME))
 471                 NFS_I(inode)->cache_validity |= NFS_INO_REVAL_FORCED;
 472         spin_unlock(&inode->i_lock);
 473 out:
 474         spin_unlock(&clp->cl_lock);
 475         if (delegation != NULL)
 476                 __nfs_free_delegation(delegation);
 477         if (freeme != NULL) {
 478                 nfs_do_return_delegation(inode, freeme, 0);
 479                 nfs_free_delegation(freeme);
 480         }
 481         return status;
 482 }
 483
 484 /*
 485  * Basic procedure for returning a delegation to the server
 486  */
 487 static int nfs_end_delegation_return(struct inode *inode, struct nfs_delegation *delegation, int issync)
 488 {
 489         struct nfs_client *clp = NFS_SERVER(inode)->nfs_client;
 490         int err = 0;
 491
 492         if (delegation == NULL)
 493                 return 0;
 494         do {
 495                 if (test_bit(NFS_DELEGATION_REVOKED, &delegation->flags))
 496                         break;
 497                 err = nfs_delegation_claim_opens(inode, &delegation->stateid,
 498                                 delegation->type);
 499                 if (!issync || err != -EAGAIN)
 500                         break;
 501                 /*
 502                  * Guard against state recovery
 503                  */
 504                 err = nfs4_wait_clnt_recover(clp);
 505         } while (err == 0);
 506
 507         if (err) {
 508                 nfs_abort_delegation_return(delegation, clp);
 509                 goto out;
 510         }
 511
 512         err = nfs_do_return_delegation(inode, delegation, issync);
 513 out:
 514         /* Refcount matched in nfs_start_delegation_return_locked() */
 515         nfs_put_delegation(delegation);
 516         return err;
 517 }
 518
 519 static bool nfs_delegation_need_return(struct nfs_delegation *delegation)
 520 {
 521         bool ret = false;
 522
 523         if (test_and_clear_bit(NFS_DELEGATION_RETURN, &delegation->flags))
 524                 ret = true;
 525         else if (test_bit(NFS_DELEGATION_RETURN_IF_CLOSED, &delegation->flags)) {
 526                 struct inode *inode;
 527
 528                 spin_lock(&delegation->lock);
 529                 inode = delegation->inode;
 530                 if (inode && list_empty(&NFS_I(inode)->open_files))
 531                         ret = true;
 532                 spin_unlock(&delegation->lock);
 533         }
 534         if (ret)
 535                 clear_bit(NFS_DELEGATION_RETURN_IF_CLOSED, &delegation->flags);
 536         if (test_bit(NFS_DELEGATION_RETURNING, &delegation->flags) ||
 537             test_bit(NFS_DELEGATION_REVOKED, &delegation->flags))
 538                 ret = false;
 539
 540         return ret;
 541 }
 542
 543 /**
 544  * nfs_client_return_marked_delegations - return previously marked delegations
 545  * @clp: nfs_client to process
 546  *
 547  * Note that this function is designed to be called by the state
 548  * manager thread. For this reason, it cannot flush the dirty data,
 549  * since that could deadlock in case of a state recovery error.
 550  *
 551  * Returns zero on success, or a negative errno value.
 552  */
 553 int nfs_client_return_marked_delegations(struct nfs_client *clp)
 554 {
 555         struct nfs_delegation *delegation;
 556         struct nfs_delegation *prev;
 557         struct nfs_server *server;
 558         struct inode *inode;
 559         struct inode *place_holder = NULL;
 560         struct nfs_delegation *place_holder_deleg = NULL;
 561         int err = 0;
 562
 563 restart:
 564         /*
 565          * To avoid quadratic looping we hold a reference
 566          * to an inode place_holder.  Each time we restart, we
 567          * list nfs_servers from the server of that inode, and
 568          * delegation in the server from the delegations of that
 569          * inode.
 570          * prev is an RCU-protected pointer to a delegation which
 571          * wasn't marked for return and might be a good choice for
 572          * the next place_holder.
 573          */
 574         rcu_read_lock();
 575         prev = NULL;
 576         if (place_holder)
 577                 server = NFS_SERVER(place_holder);
 578         else
 579                 server = list_entry_rcu(clp->cl_superblocks.next,
 580                                         struct nfs_server, client_link);
 581         list_for_each_entry_from_rcu(server, &clp->cl_superblocks, client_link) {
 582                 delegation = NULL;
 583                 if (place_holder && server == NFS_SERVER(place_holder))
 584                         delegation = rcu_dereference(NFS_I(place_holder)->delegation);
 585                 if (!delegation || delegation != place_holder_deleg)
 586                         delegation = list_entry_rcu(server->delegations.next,
 587                                                     struct nfs_delegation, super_list);
 588                 list_for_each_entry_from_rcu(delegation, &server->delegations, super_list) {
 589                         struct inode *to_put = NULL;
 590
 591                         if (!nfs_delegation_need_return(delegation)) {
 592                                 prev = delegation;
 593                                 continue;
 594                         }
 595                         if (!nfs_sb_active(server->super))
 596                                 break; /* continue in outer loop */
 597
 598                         if (prev) {
 599                                 struct inode *tmp;
 600
 601                                 tmp = nfs_delegation_grab_inode(prev);
 602                                 if (tmp) {
 603                                         to_put = place_holder;
 604                                         place_holder = tmp;
 605                                         place_holder_deleg = prev;
 606                                 }
 607                         }
 608
 609                         inode = nfs_delegation_grab_inode(delegation);
 610                         if (inode == NULL) {
 611                                 rcu_read_unlock();
 612                                 if (to_put)
 613                                         iput(to_put);
 614                                 nfs_sb_deactive(server->super);
 615                                 goto restart;
 616                         }
 617                         delegation = nfs_start_delegation_return_locked(NFS_I(inode));
 618                         rcu_read_unlock();
 619
 620                         if (to_put)
 621                                 iput(to_put);
 622
 623                         err = nfs_end_delegation_return(inode, delegation, 0);
 624                         iput(inode);
 625                         nfs_sb_deactive(server->super);
 626                         cond_resched();
 627                         if (!err)
 628                                 goto restart;
 629                         set_bit(NFS4CLNT_DELEGRETURN, &clp->cl_state);
 630                         if (place_holder)
 631                                 iput(place_holder);
 632                         return err;
 633                 }
 634         }
 635         rcu_read_unlock();
 636         if (place_holder)
 637                 iput(place_holder);
 638         return 0;
 639 }
 640
 641 /**
 642  * nfs_inode_evict_delegation - return delegation, don't reclaim opens
 643  * @inode: inode to process
 644  *
 645  * Does not protect against delegation reclaims, therefore really only safe
 646  * to be called from nfs4_clear_inode(). Guaranteed to always free
 647  * the delegation structure.
 648  */
 649 void nfs_inode_evict_delegation(struct inode *inode)
 650 {
 651         struct nfs_delegation *delegation;
 652
 653         delegation = nfs_inode_detach_delegation(inode);
 654         if (delegation != NULL) {
 655                 set_bit(NFS_DELEGATION_RETURNING, &delegation->flags);
 656                 set_bit(NFS_DELEGATION_INODE_FREEING, &delegation->flags);
 657                 nfs_do_return_delegation(inode, delegation, 1);
 658                 nfs_free_delegation(delegation);
 659         }
 660 }
 661
 662 /**
 663  * nfs_inode_return_delegation - synchronously return a delegation
 664  * @inode: inode to process
 665  *
 666  * This routine will always flush any dirty data to disk on the
 667  * assumption that if we need to return the delegation, then
 668  * we should stop caching.
 669  *
 670  * Returns zero on success, or a negative errno value.
 671  */
 672 int nfs4_inode_return_delegation(struct inode *inode)
 673 {
 674         struct nfs_inode *nfsi = NFS_I(inode);
 675         struct nfs_delegation *delegation;
 676         int err = 0;
 677
 678         nfs_wb_all(inode);
 679         delegation = nfs_start_delegation_return(nfsi);
 680         if (delegation != NULL)
 681                 err = nfs_end_delegation_return(inode, delegation, 1);
 682         return err;
 683 }
 684
 685 /**
 686  * nfs_inode_return_delegation_on_close - asynchronously return a delegation
 687  * @inode: inode to process
 688  *
 689  * This routine is called on file close in order to determine if the
 690  * inode delegation needs to be returned immediately.
 691  */
 692 void nfs4_inode_return_delegation_on_close(struct inode *inode)
 693 {
 694         struct nfs_delegation *delegation;
 695         struct nfs_delegation *ret = NULL;
 696
 697         if (!inode)
 698                 return;
 699         rcu_read_lock();
 700         delegation = nfs4_get_valid_delegation(inode);
 701         if (!delegation)
 702                 goto out;
 703         if (test_bit(NFS_DELEGATION_RETURN_IF_CLOSED, &delegation->flags) ||
 704             atomic_long_read(&nfs_active_delegations) >= nfs_delegation_watermark) {
 705                 spin_lock(&delegation->lock);
 706                 if (delegation->inode &&
 707                     list_empty(&NFS_I(inode)->open_files) &&
 708                     !test_and_set_bit(NFS_DELEGATION_RETURNING, &delegation->flags)) {
 709                         clear_bit(NFS_DELEGATION_RETURN_IF_CLOSED, &delegation->flags);
 710                         /* Refcount matched in nfs_end_delegation_return() */
 711                         ret = nfs_get_delegation(delegation);
 712                 }
 713                 spin_unlock(&delegation->lock);
 714                 if (ret)
 715                         nfs_clear_verifier_delegated(inode);
 716         }
 717 out:
 718         rcu_read_unlock();
 719         nfs_end_delegation_return(inode, ret, 0);
 720 }
 721
 722 /**
 723  * nfs4_inode_make_writeable
 724  * @inode: pointer to inode
 725  *
 726  * Make the inode writeable by returning the delegation if necessary
 727  *
 728  * Returns zero on success, or a negative errno value.
 729  */
 730 int nfs4_inode_make_writeable(struct inode *inode)
 731 {
 732         struct nfs_delegation *delegation;
 733
 734         rcu_read_lock();
 735         delegation = nfs4_get_valid_delegation(inode);
 736         if (delegation == NULL ||
 737             (nfs4_has_session(NFS_SERVER(inode)->nfs_client) &&
 738              (delegation->type & FMODE_WRITE))) {
 739                 rcu_read_unlock();
 740                 return 0;
 741         }
 742         rcu_read_unlock();
 743         return nfs4_inode_return_delegation(inode);
 744 }
 745
 746 static void nfs_mark_return_if_closed_delegation(struct nfs_server *server,
 747                 struct nfs_delegation *delegation)
 748 {
 749         set_bit(NFS_DELEGATION_RETURN_IF_CLOSED, &delegation->flags);
 750         set_bit(NFS4CLNT_DELEGRETURN, &server->nfs_client->cl_state);
 751 }
 752
 753 static void nfs_mark_return_delegation(struct nfs_server *server,
 754                 struct nfs_delegation *delegation)
 755 {
 756         set_bit(NFS_DELEGATION_RETURN, &delegation->flags);
 757         set_bit(NFS4CLNT_DELEGRETURN, &server->nfs_client->cl_state);
 758 }
 759
 760 static bool nfs_server_mark_return_all_delegations(struct nfs_server *server)
 761 {
 762         struct nfs_delegation *delegation;
 763         bool ret = false;
 764
 765         list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
 766                 nfs_mark_return_delegation(server, delegation);
 767                 ret = true;
 768         }
 769         return ret;
 770 }
 771
 772 static void nfs_client_mark_return_all_delegations(struct nfs_client *clp)
 773 {
 774         struct nfs_server *server;
 775
 776         rcu_read_lock();
 777         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
 778                 nfs_server_mark_return_all_delegations(server);
 779         rcu_read_unlock();
 780 }
 781
 782 static void nfs_delegation_run_state_manager(struct nfs_client *clp)
 783 {
 784         if (test_bit(NFS4CLNT_DELEGRETURN, &clp->cl_state))
 785                 nfs4_schedule_state_manager(clp);
 786 }
 787
 788 /**
 789  * nfs_expire_all_delegations
 790  * @clp: client to process
 791  *
 792  */
 793 void nfs_expire_all_delegations(struct nfs_client *clp)
 794 {
 795         nfs_client_mark_return_all_delegations(clp);
 796         nfs_delegation_run_state_manager(clp);
 797 }
 798
 799 /**
 800  * nfs_super_return_all_delegations - return delegations for one superblock
 801  * @server: pointer to nfs_server to process
 802  *
 803  */
 804 void nfs_server_return_all_delegations(struct nfs_server *server)
 805 {
 806         struct nfs_client *clp = server->nfs_client;
 807         bool need_wait;
 808
 809         if (clp == NULL)
 810                 return;
 811
 812         rcu_read_lock();
 813         need_wait = nfs_server_mark_return_all_delegations(server);
 814         rcu_read_unlock();
 815
 816         if (need_wait) {
 817                 nfs4_schedule_state_manager(clp);
 818                 nfs4_wait_clnt_recover(clp);
 819         }
 820 }
 821
 822 static void nfs_mark_return_unused_delegation_types(struct nfs_server *server,
 823                                                  fmode_t flags)
 824 {
 825         struct nfs_delegation *delegation;
 826
 827         list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
 828                 if ((delegation->type == (FMODE_READ|FMODE_WRITE)) && !(flags & FMODE_WRITE))
 829                         continue;
 830                 if (delegation->type & flags)
 831                         nfs_mark_return_if_closed_delegation(server, delegation);
 832         }
 833 }
 834
 835 static void nfs_client_mark_return_unused_delegation_types(struct nfs_client *clp,
 836                                                         fmode_t flags)
 837 {
 838         struct nfs_server *server;
 839
 840         rcu_read_lock();
 841         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
 842                 nfs_mark_return_unused_delegation_types(server, flags);
 843         rcu_read_unlock();
 844 }
 845
 846 static void nfs_revoke_delegation(struct inode *inode,
 847                 const nfs4_stateid *stateid)
 848 {
 849         struct nfs_delegation *delegation;
 850         nfs4_stateid tmp;
 851         bool ret = false;
 852
 853         rcu_read_lock();
 854         delegation = rcu_dereference(NFS_I(inode)->delegation);
 855         if (delegation == NULL)
 856                 goto out;
 857         if (stateid == NULL) {
 858                 nfs4_stateid_copy(&tmp, &delegation->stateid);
 859                 stateid = &tmp;
 860         } else {
 861                 if (!nfs4_stateid_match_other(stateid, &delegation->stateid))
 862                         goto out;
 863                 spin_lock(&delegation->lock);
 864                 if (stateid->seqid) {
 865                         if (nfs4_stateid_is_newer(&delegation->stateid, stateid)) {
 866                                 spin_unlock(&delegation->lock);
 867                                 goto out;
 868                         }
 869                         delegation->stateid.seqid = stateid->seqid;
 870                 }
 871                 spin_unlock(&delegation->lock);
 872         }
 873         nfs_mark_delegation_revoked(delegation);
 874         ret = true;
 875 out:
 876         rcu_read_unlock();
 877         if (ret)
 878                 nfs_inode_find_state_and_recover(inode, stateid);
 879 }
 880
 881 void nfs_remove_bad_delegation(struct inode *inode,
 882                 const nfs4_stateid *stateid)
 883 {
 884         nfs_revoke_delegation(inode, stateid);
 885 }
 886 EXPORT_SYMBOL_GPL(nfs_remove_bad_delegation);
 887
 888 void nfs_delegation_mark_returned(struct inode *inode,
 889                 const nfs4_stateid *stateid)
 890 {
 891         struct nfs_delegation *delegation;
 892
 893         if (!inode)
 894                 return;
 895
 896         rcu_read_lock();
 897         delegation = rcu_dereference(NFS_I(inode)->delegation);
 898         if (!delegation)
 899                 goto out_rcu_unlock;
 900
 901         spin_lock(&delegation->lock);
 902         if (!nfs4_stateid_match_other(stateid, &delegation->stateid))
 903                 goto out_spin_unlock;
 904         if (stateid->seqid) {
 905                 /* If delegation->stateid is newer, dont mark as returned */
 906                 if (nfs4_stateid_is_newer(&delegation->stateid, stateid))
 907                         goto out_clear_returning;
 908                 if (delegation->stateid.seqid != stateid->seqid)
 909                         delegation->stateid.seqid = stateid->seqid;
 910         }
 911
 912         nfs_mark_delegation_revoked(delegation);
 913
 914 out_clear_returning:
 915         clear_bit(NFS_DELEGATION_RETURNING, &delegation->flags);
 916 out_spin_unlock:
 917         spin_unlock(&delegation->lock);
 918 out_rcu_unlock:
 919         rcu_read_unlock();
 920
 921         nfs_inode_find_state_and_recover(inode, stateid);
 922 }
 923
 924 /**
 925  * nfs_expire_unused_delegation_types
 926  * @clp: client to process
 927  * @flags: delegation types to expire
 928  *
 929  */
 930 void nfs_expire_unused_delegation_types(struct nfs_client *clp, fmode_t flags)
 931 {
 932         nfs_client_mark_return_unused_delegation_types(clp, flags);
 933         nfs_delegation_run_state_manager(clp);
 934 }
 935
 936 static void nfs_mark_return_unreferenced_delegations(struct nfs_server *server)
 937 {
 938         struct nfs_delegation *delegation;
 939
 940         list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
 941                 if (test_and_clear_bit(NFS_DELEGATION_REFERENCED, &delegation->flags))
 942                         continue;
 943                 nfs_mark_return_if_closed_delegation(server, delegation);
 944         }
 945 }
 946
 947 /**
 948  * nfs_expire_unreferenced_delegations - Eliminate unused delegations
 949  * @clp: nfs_client to process
 950  *
 951  */
 952 void nfs_expire_unreferenced_delegations(struct nfs_client *clp)
 953 {
 954         struct nfs_server *server;
 955
 956         rcu_read_lock();
 957         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
 958                 nfs_mark_return_unreferenced_delegations(server);
 959         rcu_read_unlock();
 960
 961         nfs_delegation_run_state_manager(clp);
 962 }
 963
 964 /**
 965  * nfs_async_inode_return_delegation - asynchronously return a delegation
 966  * @inode: inode to process
 967  * @stateid: state ID information
 968  *
 969  * Returns zero on success, or a negative errno value.
 970  */
 971 int nfs_async_inode_return_delegation(struct inode *inode,
 972                                       const nfs4_stateid *stateid)
 973 {
 974         struct nfs_server *server = NFS_SERVER(inode);
 975         struct nfs_client *clp = server->nfs_client;
 976         struct nfs_delegation *delegation;
 977
 978         rcu_read_lock();
 979         delegation = nfs4_get_valid_delegation(inode);
 980         if (delegation == NULL)
 981                 goto out_enoent;
 982         if (stateid != NULL &&
 983             !clp->cl_mvops->match_stateid(&delegation->stateid, stateid))
 984                 goto out_enoent;
 985         nfs_mark_return_delegation(server, delegation);
 986         rcu_read_unlock();
 987
 988         nfs_delegation_run_state_manager(clp);
 989         return 0;
 990 out_enoent:
 991         rcu_read_unlock();
 992         return -ENOENT;
 993 }
 994
 995 static struct inode *
 996 nfs_delegation_find_inode_server(struct nfs_server *server,
 997                                  const struct nfs_fh *fhandle)
 998 {
 999         struct nfs_delegation *delegation;
1000         struct inode *freeme, *res = NULL;
1001
1002         list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
1003                 spin_lock(&delegation->lock);
1004                 if (delegation->inode != NULL &&
1005                     !test_bit(NFS_DELEGATION_REVOKED, &delegation->flags) &&
1006                     nfs_compare_fh(fhandle, &NFS_I(delegation->inode)->fh) == 0) {
1007                         freeme = igrab(delegation->inode);
1008                         if (freeme && nfs_sb_active(freeme->i_sb))
1009                                 res = freeme;
1010                         spin_unlock(&delegation->lock);
1011                         if (res != NULL)
1012                                 return res;
1013                         if (freeme) {
1014                                 rcu_read_unlock();
1015                                 iput(freeme);
1016                                 rcu_read_lock();
1017                         }
1018                         return ERR_PTR(-EAGAIN);
1019                 }
1020                 spin_unlock(&delegation->lock);
1021         }
1022         return ERR_PTR(-ENOENT);
1023 }
1024
1025 /**
1026  * nfs_delegation_find_inode - retrieve the inode associated with a delegation
1027  * @clp: client state handle
1028  * @fhandle: filehandle from a delegation recall
1029  *
1030  * Returns pointer to inode matching "fhandle," or NULL if a matching inode
1031  * cannot be found.
1032  */
1033 struct inode *nfs_delegation_find_inode(struct nfs_client *clp,
1034                                         const struct nfs_fh *fhandle)
1035 {
1036         struct nfs_server *server;
1037         struct inode *res;
1038
1039         rcu_read_lock();
1040         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link) {
1041                 res = nfs_delegation_find_inode_server(server, fhandle);
1042                 if (res != ERR_PTR(-ENOENT)) {
1043                         rcu_read_unlock();
1044                         return res;
1045                 }
1046         }
1047         rcu_read_unlock();
1048         return ERR_PTR(-ENOENT);
1049 }
1050
1051 static void nfs_delegation_mark_reclaim_server(struct nfs_server *server)
1052 {
1053         struct nfs_delegation *delegation;
1054
1055         list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
1056                 /*
1057                  * If the delegation may have been admin revoked, then we
1058                  * cannot reclaim it.
1059                  */
1060                 if (test_bit(NFS_DELEGATION_TEST_EXPIRED, &delegation->flags))
1061                         continue;
1062                 set_bit(NFS_DELEGATION_NEED_RECLAIM, &delegation->flags);
1063         }
1064 }
1065
1066 /**
1067  * nfs_delegation_mark_reclaim - mark all delegations as needing to be reclaimed
1068  * @clp: nfs_client to process
1069  *
1070  */
1071 void nfs_delegation_mark_reclaim(struct nfs_client *clp)
1072 {
1073         struct nfs_server *server;
1074
1075         rcu_read_lock();
1076         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
1077                 nfs_delegation_mark_reclaim_server(server);
1078         rcu_read_unlock();
1079 }
1080
1081 /**
1082  * nfs_delegation_reap_unclaimed - reap unclaimed delegations after reboot recovery is done
1083  * @clp: nfs_client to process
1084  *
1085  */
1086 void nfs_delegation_reap_unclaimed(struct nfs_client *clp)
1087 {
1088         struct nfs_delegation *delegation;
1089         struct nfs_server *server;
1090         struct inode *inode;
1091
1092 restart:
1093         rcu_read_lock();
1094         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link) {
1095                 list_for_each_entry_rcu(delegation, &server->delegations,
1096                                                                 super_list) {
1097                         if (test_bit(NFS_DELEGATION_INODE_FREEING,
1098                                                 &delegation->flags) ||
1099                             test_bit(NFS_DELEGATION_RETURNING,
1100                                                 &delegation->flags) ||
1101                             test_bit(NFS_DELEGATION_NEED_RECLAIM,
1102                                                 &delegation->flags) == 0)
1103                                 continue;
1104                         if (!nfs_sb_active(server->super))
1105                                 break; /* continue in outer loop */
1106                         inode = nfs_delegation_grab_inode(delegation);
1107                         if (inode == NULL) {
1108                                 rcu_read_unlock();
1109                                 nfs_sb_deactive(server->super);
1110                                 goto restart;
1111                         }
1112                         delegation = nfs_start_delegation_return_locked(NFS_I(inode));
1113                         rcu_read_unlock();
1114                         if (delegation != NULL) {
1115                                 if (nfs_detach_delegation(NFS_I(inode), delegation,
1116                                                         server) != NULL)
1117                                         nfs_free_delegation(delegation);
1118                                 /* Match nfs_start_delegation_return_locked */
1119                                 nfs_put_delegation(delegation);
1120                         }
1121                         iput(inode);
1122                         nfs_sb_deactive(server->super);
1123                         cond_resched();
1124                         goto restart;
1125                 }
1126         }
1127         rcu_read_unlock();
1128 }
1129
1130 static inline bool nfs4_server_rebooted(const struct nfs_client *clp)
1131 {
1132         return (clp->cl_state & (BIT(NFS4CLNT_CHECK_LEASE) |
1133                                 BIT(NFS4CLNT_LEASE_EXPIRED) |
1134                                 BIT(NFS4CLNT_SESSION_RESET))) != 0;
1135 }
1136
1137 static void nfs_mark_test_expired_delegation(struct nfs_server *server,
1138             struct nfs_delegation *delegation)
1139 {
1140         if (delegation->stateid.type == NFS4_INVALID_STATEID_TYPE)
1141                 return;
1142         clear_bit(NFS_DELEGATION_NEED_RECLAIM, &delegation->flags);
1143         set_bit(NFS_DELEGATION_TEST_EXPIRED, &delegation->flags);
1144         set_bit(NFS4CLNT_DELEGATION_EXPIRED, &server->nfs_client->cl_state);
1145 }
1146
1147 static void nfs_inode_mark_test_expired_delegation(struct nfs_server *server,
1148                 struct inode *inode)
1149 {
1150         struct nfs_delegation *delegation;
1151
1152         rcu_read_lock();
1153         delegation = rcu_dereference(NFS_I(inode)->delegation);
1154         if (delegation)
1155                 nfs_mark_test_expired_delegation(server, delegation);
1156         rcu_read_unlock();
1157
1158 }
1159
1160 static void nfs_delegation_mark_test_expired_server(struct nfs_server *server)
1161 {
1162         struct nfs_delegation *delegation;
1163
1164         list_for_each_entry_rcu(delegation, &server->delegations, super_list)
1165                 nfs_mark_test_expired_delegation(server, delegation);
1166 }
1167
1168 /**
1169  * nfs_mark_test_expired_all_delegations - mark all delegations for testing
1170  * @clp: nfs_client to process
1171  *
1172  * Iterates through all the delegations associated with this server and
1173  * marks them as needing to be checked for validity.
1174  */
1175 void nfs_mark_test_expired_all_delegations(struct nfs_client *clp)
1176 {
1177         struct nfs_server *server;
1178
1179         rcu_read_lock();
1180         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
1181                 nfs_delegation_mark_test_expired_server(server);
1182         rcu_read_unlock();
1183 }
1184
1185 /**
1186  * nfs_test_expired_all_delegations - test all delegations for a client
1187  * @clp: nfs_client to process
1188  *
1189  * Helper for handling "recallable state revoked" status from server.
1190  */
1191 void nfs_test_expired_all_delegations(struct nfs_client *clp)
1192 {
1193         nfs_mark_test_expired_all_delegations(clp);
1194         nfs4_schedule_state_manager(clp);
1195 }
1196
1197 static void
1198 nfs_delegation_test_free_expired(struct inode *inode,
1199                 nfs4_stateid *stateid,
1200                 const struct cred *cred)
1201 {
1202         struct nfs_server *server = NFS_SERVER(inode);
1203         const struct nfs4_minor_version_ops *ops = server->nfs_client->cl_mvops;
1204         int status;
1205
1206         if (!cred)
1207                 return;
1208         status = ops->test_and_free_expired(server, stateid, cred);
1209         if (status == -NFS4ERR_EXPIRED || status == -NFS4ERR_BAD_STATEID)
1210                 nfs_remove_bad_delegation(inode, stateid);
1211 }
1212
1213 /**
1214  * nfs_reap_expired_delegations - reap expired delegations
1215  * @clp: nfs_client to process
1216  *
1217  * Iterates through all the delegations associated with this server and
1218  * checks if they have may have been revoked. This function is usually
1219  * expected to be called in cases where the server may have lost its
1220  * lease.
1221  */
1222 void nfs_reap_expired_delegations(struct nfs_client *clp)
1223 {
1224         struct nfs_delegation *delegation;
1225         struct nfs_server *server;
1226         struct inode *inode;
1227         const struct cred *cred;
1228         nfs4_stateid stateid;
1229
1230 restart:
1231         rcu_read_lock();
1232         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link) {
1233                 list_for_each_entry_rcu(delegation, &server->delegations,
1234                                                                 super_list) {
1235                         if (test_bit(NFS_DELEGATION_INODE_FREEING,
1236                                                 &delegation->flags) ||
1237                             test_bit(NFS_DELEGATION_RETURNING,
1238                                                 &delegation->flags) ||
1239                             test_bit(NFS_DELEGATION_TEST_EXPIRED,
1240                                                 &delegation->flags) == 0)
1241                                 continue;
1242                         if (!nfs_sb_active(server->super))
1243                                 break; /* continue in outer loop */
1244                         inode = nfs_delegation_grab_inode(delegation);
1245                         if (inode == NULL) {
1246                                 rcu_read_unlock();
1247                                 nfs_sb_deactive(server->super);
1248                                 goto restart;
1249                         }
1250                         cred = get_cred_rcu(delegation->cred);
1251                         nfs4_stateid_copy(&stateid, &delegation->stateid);
1252                         clear_bit(NFS_DELEGATION_TEST_EXPIRED, &delegation->flags);
1253                         rcu_read_unlock();
1254                         nfs_delegation_test_free_expired(inode, &stateid, cred);
1255                         put_cred(cred);
1256                         if (nfs4_server_rebooted(clp)) {
1257                                 nfs_inode_mark_test_expired_delegation(server,inode);
1258                                 iput(inode);
1259                                 nfs_sb_deactive(server->super);
1260                                 return;
1261                         }
1262                         iput(inode);
1263                         nfs_sb_deactive(server->super);
1264                         cond_resched();
1265                         goto restart;
1266                 }
1267         }
1268         rcu_read_unlock();
1269 }
1270
1271 void nfs_inode_find_delegation_state_and_recover(struct inode *inode,
1272                 const nfs4_stateid *stateid)
1273 {
1274         struct nfs_client *clp = NFS_SERVER(inode)->nfs_client;
1275         struct nfs_delegation *delegation;
1276         bool found = false;
1277
1278         rcu_read_lock();
1279         delegation = rcu_dereference(NFS_I(inode)->delegation);
1280         if (delegation &&
1281             nfs4_stateid_match_or_older(&delegation->stateid, stateid) &&
1282             !test_bit(NFS_DELEGATION_REVOKED, &delegation->flags)) {
1283                 nfs_mark_test_expired_delegation(NFS_SERVER(inode), delegation);
1284                 found = true;
1285         }
1286         rcu_read_unlock();
1287         if (found)
1288                 nfs4_schedule_state_manager(clp);
1289 }
1290
1291 /**
1292  * nfs_delegations_present - check for existence of delegations
1293  * @clp: client state handle
1294  *
1295  * Returns one if there are any nfs_delegation structures attached
1296  * to this nfs_client.
1297  */
1298 int nfs_delegations_present(struct nfs_client *clp)
1299 {
1300         struct nfs_server *server;
1301         int ret = 0;
1302
1303         rcu_read_lock();
1304         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
1305                 if (!list_empty(&server->delegations)) {
1306                         ret = 1;
1307                         break;
1308                 }
1309         rcu_read_unlock();
1310         return ret;
1311 }
1312
1313 /**
1314  * nfs4_refresh_delegation_stateid - Update delegation stateid seqid
1315  * @dst: stateid to refresh
1316  * @inode: inode to check
1317  *
1318  * Returns "true" and updates "dst->seqid" * if inode had a delegation
1319  * that matches our delegation stateid. Otherwise "false" is returned.
1320  */
1321 bool nfs4_refresh_delegation_stateid(nfs4_stateid *dst, struct inode *inode)
1322 {
1323         struct nfs_delegation *delegation;
1324         bool ret = false;
1325         if (!inode)
1326                 goto out;
1327
1328         rcu_read_lock();
1329         delegation = rcu_dereference(NFS_I(inode)->delegation);
1330         if (delegation != NULL &&
1331             nfs4_stateid_match_other(dst, &delegation->stateid) &&
1332             nfs4_stateid_is_newer(&delegation->stateid, dst) &&
1333             !test_bit(NFS_DELEGATION_REVOKED, &delegation->flags)) {
1334                 dst->seqid = delegation->stateid.seqid;
1335                 ret = true;
1336         }
1337         rcu_read_unlock();
1338 out:
1339         return ret;
1340 }
1341
1342 /**
1343  * nfs4_copy_delegation_stateid - Copy inode's state ID information
1344  * @inode: inode to check
1345  * @flags: delegation type requirement
1346  * @dst: stateid data structure to fill in
1347  * @cred: optional argument to retrieve credential
1348  *
1349  * Returns "true" and fills in "dst->data" * if inode had a delegation,
1350  * otherwise "false" is returned.
1351  */
1352 bool nfs4_copy_delegation_stateid(struct inode *inode, fmode_t flags,
1353                 nfs4_stateid *dst, const struct cred **cred)
1354 {
1355         struct nfs_inode *nfsi = NFS_I(inode);
1356         struct nfs_delegation *delegation;
1357         bool ret;
1358
1359         flags &= FMODE_READ|FMODE_WRITE;
1360         rcu_read_lock();
1361         delegation = rcu_dereference(nfsi->delegation);
1362         ret = nfs4_is_valid_delegation(delegation, flags);
1363         if (ret) {
1364                 nfs4_stateid_copy(dst, &delegation->stateid);
1365                 nfs_mark_delegation_referenced(delegation);
1366                 if (cred)
1367                         *cred = get_cred(delegation->cred);
1368         }
1369         rcu_read_unlock();
1370         return ret;
1371 }
1372
1373 /**
1374  * nfs4_delegation_flush_on_close - Check if we must flush file on close
1375  * @inode: inode to check
1376  *
1377  * This function checks the number of outstanding writes to the file
1378  * against the delegation 'space_limit' field to see if
1379  * the spec requires us to flush the file on close.
1380  */
1381 bool nfs4_delegation_flush_on_close(const struct inode *inode)
1382 {
1383         struct nfs_inode *nfsi = NFS_I(inode);
1384         struct nfs_delegation *delegation;
1385         bool ret = true;
1386
1387         rcu_read_lock();
1388         delegation = rcu_dereference(nfsi->delegation);
1389         if (delegation == NULL || !(delegation->type & FMODE_WRITE))
1390                 goto out;
1391         if (atomic_long_read(&nfsi->nrequests) < delegation->pagemod_limit)
1392                 ret = false;
1393 out:
1394         rcu_read_unlock();
1395         return ret;
1396 }
1397
1398 module_param_named(delegation_watermark, nfs_delegation_watermark, uint, 0644);