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         const struct cred *cred;
 259         int res = 0;
 260
 261         if (!test_bit(NFS_DELEGATION_REVOKED, &delegation->flags)) {
 262                 spin_lock(&delegation->lock);
 263                 cred = get_cred(delegation->cred);
 264                 spin_unlock(&delegation->lock);
 265                 res = nfs4_proc_delegreturn(inode, cred,
 266                                 &delegation->stateid,
 267                                 issync);
 268                 put_cred(cred);
 269         }
 270         return res;
 271 }
 272
 273 static struct inode *nfs_delegation_grab_inode(struct nfs_delegation *delegation)
 274 {
 275         struct inode *inode = NULL;
 276
 277         spin_lock(&delegation->lock);
 278         if (delegation->inode != NULL)
 279                 inode = igrab(delegation->inode);
 280         if (!inode)
 281                 set_bit(NFS_DELEGATION_INODE_FREEING, &delegation->flags);
 282         spin_unlock(&delegation->lock);
 283         return inode;
 284 }
 285
 286 static struct nfs_delegation *
 287 nfs_start_delegation_return_locked(struct nfs_inode *nfsi)
 288 {
 289         struct nfs_delegation *ret = NULL;
 290         struct nfs_delegation *delegation = rcu_dereference(nfsi->delegation);
 291
 292         if (delegation == NULL)
 293                 goto out;
 294         spin_lock(&delegation->lock);
 295         if (!test_and_set_bit(NFS_DELEGATION_RETURNING, &delegation->flags)) {
 296                 /* Refcount matched in nfs_end_delegation_return() */
 297                 ret = nfs_get_delegation(delegation);
 298         }
 299         spin_unlock(&delegation->lock);
 300         if (ret)
 301                 nfs_clear_verifier_delegated(&nfsi->vfs_inode);
 302 out:
 303         return ret;
 304 }
 305
 306 static struct nfs_delegation *
 307 nfs_start_delegation_return(struct nfs_inode *nfsi)
 308 {
 309         struct nfs_delegation *delegation;
 310
 311         rcu_read_lock();
 312         delegation = nfs_start_delegation_return_locked(nfsi);
 313         rcu_read_unlock();
 314         return delegation;
 315 }
 316
 317 static void
 318 nfs_abort_delegation_return(struct nfs_delegation *delegation,
 319                 struct nfs_client *clp)
 320 {
 321
 322         spin_lock(&delegation->lock);
 323         clear_bit(NFS_DELEGATION_RETURNING, &delegation->flags);
 324         set_bit(NFS_DELEGATION_RETURN, &delegation->flags);
 325         spin_unlock(&delegation->lock);
 326         set_bit(NFS4CLNT_DELEGRETURN, &clp->cl_state);
 327 }
 328
 329 static struct nfs_delegation *
 330 nfs_detach_delegation_locked(struct nfs_inode *nfsi,
 331                 struct nfs_delegation *delegation,
 332                 struct nfs_client *clp)
 333 {
 334         struct nfs_delegation *deleg_cur =
 335                 rcu_dereference_protected(nfsi->delegation,
 336                                 lockdep_is_held(&clp->cl_lock));
 337
 338         if (deleg_cur == NULL || delegation != deleg_cur)
 339                 return NULL;
 340
 341         spin_lock(&delegation->lock);
 342         if (!delegation->inode) {
 343                 spin_unlock(&delegation->lock);
 344                 return NULL;
 345         }
 346         list_del_rcu(&delegation->super_list);
 347         delegation->inode = NULL;
 348         rcu_assign_pointer(nfsi->delegation, NULL);
 349         spin_unlock(&delegation->lock);
 350         return delegation;
 351 }
 352
 353 static struct nfs_delegation *nfs_detach_delegation(struct nfs_inode *nfsi,
 354                 struct nfs_delegation *delegation,
 355                 struct nfs_server *server)
 356 {
 357         struct nfs_client *clp = server->nfs_client;
 358
 359         spin_lock(&clp->cl_lock);
 360         delegation = nfs_detach_delegation_locked(nfsi, delegation, clp);
 361         spin_unlock(&clp->cl_lock);
 362         return delegation;
 363 }
 364
 365 static struct nfs_delegation *
 366 nfs_inode_detach_delegation(struct inode *inode)
 367 {
 368         struct nfs_inode *nfsi = NFS_I(inode);
 369         struct nfs_server *server = NFS_SERVER(inode);
 370         struct nfs_delegation *delegation;
 371
 372         rcu_read_lock();
 373         delegation = rcu_dereference(nfsi->delegation);
 374         if (delegation != NULL)
 375                 delegation = nfs_detach_delegation(nfsi, delegation, server);
 376         rcu_read_unlock();
 377         return delegation;
 378 }
 379
 380 static void
 381 nfs_update_inplace_delegation(struct nfs_delegation *delegation,
 382                 const struct nfs_delegation *update)
 383 {
 384         if (nfs4_stateid_is_newer(&update->stateid, &delegation->stateid)) {
 385                 delegation->stateid.seqid = update->stateid.seqid;
 386                 smp_wmb();
 387                 delegation->type = update->type;
 388                 if (test_and_clear_bit(NFS_DELEGATION_REVOKED, &delegation->flags))
 389                         atomic_long_inc(&nfs_active_delegations);
 390         }
 391 }
 392
 393 /**
 394  * nfs_inode_set_delegation - set up a delegation on an inode
 395  * @inode: inode to which delegation applies
 396  * @cred: cred to use for subsequent delegation processing
 397  * @type: delegation type
 398  * @stateid: delegation stateid
 399  * @pagemod_limit: write delegation "space_limit"
 400  *
 401  * Returns zero on success, or a negative errno value.
 402  */
 403 int nfs_inode_set_delegation(struct inode *inode, const struct cred *cred,
 404                                   fmode_t type,
 405                                   const nfs4_stateid *stateid,
 406                                   unsigned long pagemod_limit)
 407 {
 408         struct nfs_server *server = NFS_SERVER(inode);
 409         struct nfs_client *clp = server->nfs_client;
 410         struct nfs_inode *nfsi = NFS_I(inode);
 411         struct nfs_delegation *delegation, *old_delegation;
 412         struct nfs_delegation *freeme = NULL;
 413         int status = 0;
 414
 415         delegation = kmalloc(sizeof(*delegation), GFP_NOFS);
 416         if (delegation == NULL)
 417                 return -ENOMEM;
 418         nfs4_stateid_copy(&delegation->stateid, stateid);
 419         refcount_set(&delegation->refcount, 1);
 420         delegation->type = type;
 421         delegation->pagemod_limit = pagemod_limit;
 422         delegation->change_attr = inode_peek_iversion_raw(inode);
 423         delegation->cred = get_cred(cred);
 424         delegation->inode = inode;
 425         delegation->flags = 1<<NFS_DELEGATION_REFERENCED;
 426         spin_lock_init(&delegation->lock);
 427
 428         spin_lock(&clp->cl_lock);
 429         old_delegation = rcu_dereference_protected(nfsi->delegation,
 430                                         lockdep_is_held(&clp->cl_lock));
 431         if (old_delegation == NULL)
 432                 goto add_new;
 433         /* Is this an update of the existing delegation? */
 434         if (nfs4_stateid_match_other(&old_delegation->stateid,
 435                                 &delegation->stateid)) {
 436                 spin_lock(&old_delegation->lock);
 437                 nfs_update_inplace_delegation(old_delegation,
 438                                 delegation);
 439                 spin_unlock(&old_delegation->lock);
 440                 goto out;
 441         }
 442         if (!test_bit(NFS_DELEGATION_REVOKED, &old_delegation->flags)) {
 443                 /*
 444                  * Deal with broken servers that hand out two
 445                  * delegations for the same file.
 446                  * Allow for upgrades to a WRITE delegation, but
 447                  * nothing else.
 448                  */
 449                 dfprintk(FILE, "%s: server %s handed out "
 450                                 "a duplicate delegation!\n",
 451                                 __func__, clp->cl_hostname);
 452                 if (delegation->type == old_delegation->type ||
 453                     !(delegation->type & FMODE_WRITE)) {
 454                         freeme = delegation;
 455                         delegation = NULL;
 456                         goto out;
 457                 }
 458                 if (test_and_set_bit(NFS_DELEGATION_RETURNING,
 459                                         &old_delegation->flags))
 460                         goto out;
 461         }
 462         freeme = nfs_detach_delegation_locked(nfsi, old_delegation, clp);
 463         if (freeme == NULL)
 464                 goto out;
 465 add_new:
 466         list_add_tail_rcu(&delegation->super_list, &server->delegations);
 467         rcu_assign_pointer(nfsi->delegation, delegation);
 468         delegation = NULL;
 469
 470         atomic_long_inc(&nfs_active_delegations);
 471
 472         trace_nfs4_set_delegation(inode, type);
 473
 474         spin_lock(&inode->i_lock);
 475         if (NFS_I(inode)->cache_validity & (NFS_INO_INVALID_ATTR|NFS_INO_INVALID_ATIME))
 476                 NFS_I(inode)->cache_validity |= NFS_INO_REVAL_FORCED;
 477         spin_unlock(&inode->i_lock);
 478 out:
 479         spin_unlock(&clp->cl_lock);
 480         if (delegation != NULL)
 481                 __nfs_free_delegation(delegation);
 482         if (freeme != NULL) {
 483                 nfs_do_return_delegation(inode, freeme, 0);
 484                 nfs_free_delegation(freeme);
 485         }
 486         return status;
 487 }
 488
 489 /*
 490  * Basic procedure for returning a delegation to the server
 491  */
 492 static int nfs_end_delegation_return(struct inode *inode, struct nfs_delegation *delegation, int issync)
 493 {
 494         struct nfs_client *clp = NFS_SERVER(inode)->nfs_client;
 495         int err = 0;
 496
 497         if (delegation == NULL)
 498                 return 0;
 499         do {
 500                 if (test_bit(NFS_DELEGATION_REVOKED, &delegation->flags))
 501                         break;
 502                 err = nfs_delegation_claim_opens(inode, &delegation->stateid,
 503                                 delegation->type);
 504                 if (!issync || err != -EAGAIN)
 505                         break;
 506                 /*
 507                  * Guard against state recovery
 508                  */
 509                 err = nfs4_wait_clnt_recover(clp);
 510         } while (err == 0);
 511
 512         if (err) {
 513                 nfs_abort_delegation_return(delegation, clp);
 514                 goto out;
 515         }
 516
 517         err = nfs_do_return_delegation(inode, delegation, issync);
 518 out:
 519         /* Refcount matched in nfs_start_delegation_return_locked() */
 520         nfs_put_delegation(delegation);
 521         return err;
 522 }
 523
 524 static bool nfs_delegation_need_return(struct nfs_delegation *delegation)
 525 {
 526         bool ret = false;
 527
 528         if (test_and_clear_bit(NFS_DELEGATION_RETURN, &delegation->flags))
 529                 ret = true;
 530         else if (test_bit(NFS_DELEGATION_RETURN_IF_CLOSED, &delegation->flags)) {
 531                 struct inode *inode;
 532
 533                 spin_lock(&delegation->lock);
 534                 inode = delegation->inode;
 535                 if (inode && list_empty(&NFS_I(inode)->open_files))
 536                         ret = true;
 537                 spin_unlock(&delegation->lock);
 538         }
 539         if (ret)
 540                 clear_bit(NFS_DELEGATION_RETURN_IF_CLOSED, &delegation->flags);
 541         if (test_bit(NFS_DELEGATION_RETURNING, &delegation->flags) ||
 542             test_bit(NFS_DELEGATION_REVOKED, &delegation->flags))
 543                 ret = false;
 544
 545         return ret;
 546 }
 547
 548 /**
 549  * nfs_client_return_marked_delegations - return previously marked delegations
 550  * @clp: nfs_client to process
 551  *
 552  * Note that this function is designed to be called by the state
 553  * manager thread. For this reason, it cannot flush the dirty data,
 554  * since that could deadlock in case of a state recovery error.
 555  *
 556  * Returns zero on success, or a negative errno value.
 557  */
 558 int nfs_client_return_marked_delegations(struct nfs_client *clp)
 559 {
 560         struct nfs_delegation *delegation;
 561         struct nfs_delegation *prev;
 562         struct nfs_server *server;
 563         struct inode *inode;
 564         struct inode *place_holder = NULL;
 565         struct nfs_delegation *place_holder_deleg = NULL;
 566         int err = 0;
 567
 568 restart:
 569         /*
 570          * To avoid quadratic looping we hold a reference
 571          * to an inode place_holder.  Each time we restart, we
 572          * list nfs_servers from the server of that inode, and
 573          * delegation in the server from the delegations of that
 574          * inode.
 575          * prev is an RCU-protected pointer to a delegation which
 576          * wasn't marked for return and might be a good choice for
 577          * the next place_holder.
 578          */
 579         rcu_read_lock();
 580         prev = NULL;
 581         if (place_holder)
 582                 server = NFS_SERVER(place_holder);
 583         else
 584                 server = list_entry_rcu(clp->cl_superblocks.next,
 585                                         struct nfs_server, client_link);
 586         list_for_each_entry_from_rcu(server, &clp->cl_superblocks, client_link) {
 587                 delegation = NULL;
 588                 if (place_holder && server == NFS_SERVER(place_holder))
 589                         delegation = rcu_dereference(NFS_I(place_holder)->delegation);
 590                 if (!delegation || delegation != place_holder_deleg)
 591                         delegation = list_entry_rcu(server->delegations.next,
 592                                                     struct nfs_delegation, super_list);
 593                 list_for_each_entry_from_rcu(delegation, &server->delegations, super_list) {
 594                         struct inode *to_put = NULL;
 595
 596                         if (!nfs_delegation_need_return(delegation)) {
 597                                 prev = delegation;
 598                                 continue;
 599                         }
 600                         if (!nfs_sb_active(server->super))
 601                                 break; /* continue in outer loop */
 602
 603                         if (prev) {
 604                                 struct inode *tmp;
 605
 606                                 tmp = nfs_delegation_grab_inode(prev);
 607                                 if (tmp) {
 608                                         to_put = place_holder;
 609                                         place_holder = tmp;
 610                                         place_holder_deleg = prev;
 611                                 }
 612                         }
 613
 614                         inode = nfs_delegation_grab_inode(delegation);
 615                         if (inode == NULL) {
 616                                 rcu_read_unlock();
 617                                 if (to_put)
 618                                         iput(to_put);
 619                                 nfs_sb_deactive(server->super);
 620                                 goto restart;
 621                         }
 622                         delegation = nfs_start_delegation_return_locked(NFS_I(inode));
 623                         rcu_read_unlock();
 624
 625                         if (to_put)
 626                                 iput(to_put);
 627
 628                         err = nfs_end_delegation_return(inode, delegation, 0);
 629                         iput(inode);
 630                         nfs_sb_deactive(server->super);
 631                         cond_resched();
 632                         if (!err)
 633                                 goto restart;
 634                         set_bit(NFS4CLNT_DELEGRETURN, &clp->cl_state);
 635                         if (place_holder)
 636                                 iput(place_holder);
 637                         return err;
 638                 }
 639         }
 640         rcu_read_unlock();
 641         if (place_holder)
 642                 iput(place_holder);
 643         return 0;
 644 }
 645
 646 /**
 647  * nfs_inode_evict_delegation - return delegation, don't reclaim opens
 648  * @inode: inode to process
 649  *
 650  * Does not protect against delegation reclaims, therefore really only safe
 651  * to be called from nfs4_clear_inode(). Guaranteed to always free
 652  * the delegation structure.
 653  */
 654 void nfs_inode_evict_delegation(struct inode *inode)
 655 {
 656         struct nfs_delegation *delegation;
 657
 658         delegation = nfs_inode_detach_delegation(inode);
 659         if (delegation != NULL) {
 660                 set_bit(NFS_DELEGATION_RETURNING, &delegation->flags);
 661                 set_bit(NFS_DELEGATION_INODE_FREEING, &delegation->flags);
 662                 nfs_do_return_delegation(inode, delegation, 1);
 663                 nfs_free_delegation(delegation);
 664         }
 665 }
 666
 667 /**
 668  * nfs_inode_return_delegation - synchronously return a delegation
 669  * @inode: inode to process
 670  *
 671  * This routine will always flush any dirty data to disk on the
 672  * assumption that if we need to return the delegation, then
 673  * we should stop caching.
 674  *
 675  * Returns zero on success, or a negative errno value.
 676  */
 677 int nfs4_inode_return_delegation(struct inode *inode)
 678 {
 679         struct nfs_inode *nfsi = NFS_I(inode);
 680         struct nfs_delegation *delegation;
 681         int err = 0;
 682
 683         nfs_wb_all(inode);
 684         delegation = nfs_start_delegation_return(nfsi);
 685         if (delegation != NULL)
 686                 err = nfs_end_delegation_return(inode, delegation, 1);
 687         return err;
 688 }
 689
 690 /**
 691  * nfs_inode_return_delegation_on_close - asynchronously return a delegation
 692  * @inode: inode to process
 693  *
 694  * This routine is called on file close in order to determine if the
 695  * inode delegation needs to be returned immediately.
 696  */
 697 void nfs4_inode_return_delegation_on_close(struct inode *inode)
 698 {
 699         struct nfs_delegation *delegation;
 700         struct nfs_delegation *ret = NULL;
 701
 702         if (!inode)
 703                 return;
 704         rcu_read_lock();
 705         delegation = nfs4_get_valid_delegation(inode);
 706         if (!delegation)
 707                 goto out;
 708         if (test_bit(NFS_DELEGATION_RETURN_IF_CLOSED, &delegation->flags) ||
 709             atomic_long_read(&nfs_active_delegations) >= nfs_delegation_watermark) {
 710                 spin_lock(&delegation->lock);
 711                 if (delegation->inode &&
 712                     list_empty(&NFS_I(inode)->open_files) &&
 713                     !test_and_set_bit(NFS_DELEGATION_RETURNING, &delegation->flags)) {
 714                         clear_bit(NFS_DELEGATION_RETURN_IF_CLOSED, &delegation->flags);
 715                         /* Refcount matched in nfs_end_delegation_return() */
 716                         ret = nfs_get_delegation(delegation);
 717                 }
 718                 spin_unlock(&delegation->lock);
 719                 if (ret)
 720                         nfs_clear_verifier_delegated(inode);
 721         }
 722 out:
 723         rcu_read_unlock();
 724         nfs_end_delegation_return(inode, ret, 0);
 725 }
 726
 727 /**
 728  * nfs4_inode_make_writeable
 729  * @inode: pointer to inode
 730  *
 731  * Make the inode writeable by returning the delegation if necessary
 732  *
 733  * Returns zero on success, or a negative errno value.
 734  */
 735 int nfs4_inode_make_writeable(struct inode *inode)
 736 {
 737         struct nfs_delegation *delegation;
 738
 739         rcu_read_lock();
 740         delegation = nfs4_get_valid_delegation(inode);
 741         if (delegation == NULL ||
 742             (nfs4_has_session(NFS_SERVER(inode)->nfs_client) &&
 743              (delegation->type & FMODE_WRITE))) {
 744                 rcu_read_unlock();
 745                 return 0;
 746         }
 747         rcu_read_unlock();
 748         return nfs4_inode_return_delegation(inode);
 749 }
 750
 751 static void nfs_mark_return_if_closed_delegation(struct nfs_server *server,
 752                 struct nfs_delegation *delegation)
 753 {
 754         set_bit(NFS_DELEGATION_RETURN_IF_CLOSED, &delegation->flags);
 755         set_bit(NFS4CLNT_DELEGRETURN, &server->nfs_client->cl_state);
 756 }
 757
 758 static void nfs_mark_return_delegation(struct nfs_server *server,
 759                 struct nfs_delegation *delegation)
 760 {
 761         set_bit(NFS_DELEGATION_RETURN, &delegation->flags);
 762         set_bit(NFS4CLNT_DELEGRETURN, &server->nfs_client->cl_state);
 763 }
 764
 765 static bool nfs_server_mark_return_all_delegations(struct nfs_server *server)
 766 {
 767         struct nfs_delegation *delegation;
 768         bool ret = false;
 769
 770         list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
 771                 nfs_mark_return_delegation(server, delegation);
 772                 ret = true;
 773         }
 774         return ret;
 775 }
 776
 777 static void nfs_client_mark_return_all_delegations(struct nfs_client *clp)
 778 {
 779         struct nfs_server *server;
 780
 781         rcu_read_lock();
 782         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
 783                 nfs_server_mark_return_all_delegations(server);
 784         rcu_read_unlock();
 785 }
 786
 787 static void nfs_delegation_run_state_manager(struct nfs_client *clp)
 788 {
 789         if (test_bit(NFS4CLNT_DELEGRETURN, &clp->cl_state))
 790                 nfs4_schedule_state_manager(clp);
 791 }
 792
 793 /**
 794  * nfs_expire_all_delegations
 795  * @clp: client to process
 796  *
 797  */
 798 void nfs_expire_all_delegations(struct nfs_client *clp)
 799 {
 800         nfs_client_mark_return_all_delegations(clp);
 801         nfs_delegation_run_state_manager(clp);
 802 }
 803
 804 /**
 805  * nfs_super_return_all_delegations - return delegations for one superblock
 806  * @server: pointer to nfs_server to process
 807  *
 808  */
 809 void nfs_server_return_all_delegations(struct nfs_server *server)
 810 {
 811         struct nfs_client *clp = server->nfs_client;
 812         bool need_wait;
 813
 814         if (clp == NULL)
 815                 return;
 816
 817         rcu_read_lock();
 818         need_wait = nfs_server_mark_return_all_delegations(server);
 819         rcu_read_unlock();
 820
 821         if (need_wait) {
 822                 nfs4_schedule_state_manager(clp);
 823                 nfs4_wait_clnt_recover(clp);
 824         }
 825 }
 826
 827 static void nfs_mark_return_unused_delegation_types(struct nfs_server *server,
 828                                                  fmode_t flags)
 829 {
 830         struct nfs_delegation *delegation;
 831
 832         list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
 833                 if ((delegation->type == (FMODE_READ|FMODE_WRITE)) && !(flags & FMODE_WRITE))
 834                         continue;
 835                 if (delegation->type & flags)
 836                         nfs_mark_return_if_closed_delegation(server, delegation);
 837         }
 838 }
 839
 840 static void nfs_client_mark_return_unused_delegation_types(struct nfs_client *clp,
 841                                                         fmode_t flags)
 842 {
 843         struct nfs_server *server;
 844
 845         rcu_read_lock();
 846         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
 847                 nfs_mark_return_unused_delegation_types(server, flags);
 848         rcu_read_unlock();
 849 }
 850
 851 static void nfs_revoke_delegation(struct inode *inode,
 852                 const nfs4_stateid *stateid)
 853 {
 854         struct nfs_delegation *delegation;
 855         nfs4_stateid tmp;
 856         bool ret = false;
 857
 858         rcu_read_lock();
 859         delegation = rcu_dereference(NFS_I(inode)->delegation);
 860         if (delegation == NULL)
 861                 goto out;
 862         if (stateid == NULL) {
 863                 nfs4_stateid_copy(&tmp, &delegation->stateid);
 864                 stateid = &tmp;
 865         } else {
 866                 if (!nfs4_stateid_match_other(stateid, &delegation->stateid))
 867                         goto out;
 868                 spin_lock(&delegation->lock);
 869                 if (stateid->seqid) {
 870                         if (nfs4_stateid_is_newer(&delegation->stateid, stateid)) {
 871                                 spin_unlock(&delegation->lock);
 872                                 goto out;
 873                         }
 874                         delegation->stateid.seqid = stateid->seqid;
 875                 }
 876                 spin_unlock(&delegation->lock);
 877         }
 878         nfs_mark_delegation_revoked(delegation);
 879         ret = true;
 880 out:
 881         rcu_read_unlock();
 882         if (ret)
 883                 nfs_inode_find_state_and_recover(inode, stateid);
 884 }
 885
 886 void nfs_remove_bad_delegation(struct inode *inode,
 887                 const nfs4_stateid *stateid)
 888 {
 889         nfs_revoke_delegation(inode, stateid);
 890 }
 891 EXPORT_SYMBOL_GPL(nfs_remove_bad_delegation);
 892
 893 void nfs_delegation_mark_returned(struct inode *inode,
 894                 const nfs4_stateid *stateid)
 895 {
 896         struct nfs_delegation *delegation;
 897
 898         if (!inode)
 899                 return;
 900
 901         rcu_read_lock();
 902         delegation = rcu_dereference(NFS_I(inode)->delegation);
 903         if (!delegation)
 904                 goto out_rcu_unlock;
 905
 906         spin_lock(&delegation->lock);
 907         if (!nfs4_stateid_match_other(stateid, &delegation->stateid))
 908                 goto out_spin_unlock;
 909         if (stateid->seqid) {
 910                 /* If delegation->stateid is newer, dont mark as returned */
 911                 if (nfs4_stateid_is_newer(&delegation->stateid, stateid))
 912                         goto out_clear_returning;
 913                 if (delegation->stateid.seqid != stateid->seqid)
 914                         delegation->stateid.seqid = stateid->seqid;
 915         }
 916
 917         nfs_mark_delegation_revoked(delegation);
 918
 919 out_clear_returning:
 920         clear_bit(NFS_DELEGATION_RETURNING, &delegation->flags);
 921 out_spin_unlock:
 922         spin_unlock(&delegation->lock);
 923 out_rcu_unlock:
 924         rcu_read_unlock();
 925
 926         nfs_inode_find_state_and_recover(inode, stateid);
 927 }
 928
 929 /**
 930  * nfs_expire_unused_delegation_types
 931  * @clp: client to process
 932  * @flags: delegation types to expire
 933  *
 934  */
 935 void nfs_expire_unused_delegation_types(struct nfs_client *clp, fmode_t flags)
 936 {
 937         nfs_client_mark_return_unused_delegation_types(clp, flags);
 938         nfs_delegation_run_state_manager(clp);
 939 }
 940
 941 static void nfs_mark_return_unreferenced_delegations(struct nfs_server *server)
 942 {
 943         struct nfs_delegation *delegation;
 944
 945         list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
 946                 if (test_and_clear_bit(NFS_DELEGATION_REFERENCED, &delegation->flags))
 947                         continue;
 948                 nfs_mark_return_if_closed_delegation(server, delegation);
 949         }
 950 }
 951
 952 /**
 953  * nfs_expire_unreferenced_delegations - Eliminate unused delegations
 954  * @clp: nfs_client to process
 955  *
 956  */
 957 void nfs_expire_unreferenced_delegations(struct nfs_client *clp)
 958 {
 959         struct nfs_server *server;
 960
 961         rcu_read_lock();
 962         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
 963                 nfs_mark_return_unreferenced_delegations(server);
 964         rcu_read_unlock();
 965
 966         nfs_delegation_run_state_manager(clp);
 967 }
 968
 969 /**
 970  * nfs_async_inode_return_delegation - asynchronously return a delegation
 971  * @inode: inode to process
 972  * @stateid: state ID information
 973  *
 974  * Returns zero on success, or a negative errno value.
 975  */
 976 int nfs_async_inode_return_delegation(struct inode *inode,
 977                                       const nfs4_stateid *stateid)
 978 {
 979         struct nfs_server *server = NFS_SERVER(inode);
 980         struct nfs_client *clp = server->nfs_client;
 981         struct nfs_delegation *delegation;
 982
 983         rcu_read_lock();
 984         delegation = nfs4_get_valid_delegation(inode);
 985         if (delegation == NULL)
 986                 goto out_enoent;
 987         if (stateid != NULL &&
 988             !clp->cl_mvops->match_stateid(&delegation->stateid, stateid))
 989                 goto out_enoent;
 990         nfs_mark_return_delegation(server, delegation);
 991         rcu_read_unlock();
 992
 993         nfs_delegation_run_state_manager(clp);
 994         return 0;
 995 out_enoent:
 996         rcu_read_unlock();
 997         return -ENOENT;
 998 }
 999
1000 static struct inode *
1001 nfs_delegation_find_inode_server(struct nfs_server *server,
1002                                  const struct nfs_fh *fhandle)
1003 {
1004         struct nfs_delegation *delegation;
1005         struct inode *freeme, *res = NULL;
1006
1007         list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
1008                 spin_lock(&delegation->lock);
1009                 if (delegation->inode != NULL &&
1010                     !test_bit(NFS_DELEGATION_REVOKED, &delegation->flags) &&
1011                     nfs_compare_fh(fhandle, &NFS_I(delegation->inode)->fh) == 0) {
1012                         freeme = igrab(delegation->inode);
1013                         if (freeme && nfs_sb_active(freeme->i_sb))
1014                                 res = freeme;
1015                         spin_unlock(&delegation->lock);
1016                         if (res != NULL)
1017                                 return res;
1018                         if (freeme) {
1019                                 rcu_read_unlock();
1020                                 iput(freeme);
1021                                 rcu_read_lock();
1022                         }
1023                         return ERR_PTR(-EAGAIN);
1024                 }
1025                 spin_unlock(&delegation->lock);
1026         }
1027         return ERR_PTR(-ENOENT);
1028 }
1029
1030 /**
1031  * nfs_delegation_find_inode - retrieve the inode associated with a delegation
1032  * @clp: client state handle
1033  * @fhandle: filehandle from a delegation recall
1034  *
1035  * Returns pointer to inode matching "fhandle," or NULL if a matching inode
1036  * cannot be found.
1037  */
1038 struct inode *nfs_delegation_find_inode(struct nfs_client *clp,
1039                                         const struct nfs_fh *fhandle)
1040 {
1041         struct nfs_server *server;
1042         struct inode *res;
1043
1044         rcu_read_lock();
1045         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link) {
1046                 res = nfs_delegation_find_inode_server(server, fhandle);
1047                 if (res != ERR_PTR(-ENOENT)) {
1048                         rcu_read_unlock();
1049                         return res;
1050                 }
1051         }
1052         rcu_read_unlock();
1053         return ERR_PTR(-ENOENT);
1054 }
1055
1056 static void nfs_delegation_mark_reclaim_server(struct nfs_server *server)
1057 {
1058         struct nfs_delegation *delegation;
1059
1060         list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
1061                 /*
1062                  * If the delegation may have been admin revoked, then we
1063                  * cannot reclaim it.
1064                  */
1065                 if (test_bit(NFS_DELEGATION_TEST_EXPIRED, &delegation->flags))
1066                         continue;
1067                 set_bit(NFS_DELEGATION_NEED_RECLAIM, &delegation->flags);
1068         }
1069 }
1070
1071 /**
1072  * nfs_delegation_mark_reclaim - mark all delegations as needing to be reclaimed
1073  * @clp: nfs_client to process
1074  *
1075  */
1076 void nfs_delegation_mark_reclaim(struct nfs_client *clp)
1077 {
1078         struct nfs_server *server;
1079
1080         rcu_read_lock();
1081         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
1082                 nfs_delegation_mark_reclaim_server(server);
1083         rcu_read_unlock();
1084 }
1085
1086 /**
1087  * nfs_delegation_reap_unclaimed - reap unclaimed delegations after reboot recovery is done
1088  * @clp: nfs_client to process
1089  *
1090  */
1091 void nfs_delegation_reap_unclaimed(struct nfs_client *clp)
1092 {
1093         struct nfs_delegation *delegation;
1094         struct nfs_server *server;
1095         struct inode *inode;
1096
1097 restart:
1098         rcu_read_lock();
1099         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link) {
1100                 list_for_each_entry_rcu(delegation, &server->delegations,
1101                                                                 super_list) {
1102                         if (test_bit(NFS_DELEGATION_INODE_FREEING,
1103                                                 &delegation->flags) ||
1104                             test_bit(NFS_DELEGATION_RETURNING,
1105                                                 &delegation->flags) ||
1106                             test_bit(NFS_DELEGATION_NEED_RECLAIM,
1107                                                 &delegation->flags) == 0)
1108                                 continue;
1109                         if (!nfs_sb_active(server->super))
1110                                 break; /* continue in outer loop */
1111                         inode = nfs_delegation_grab_inode(delegation);
1112                         if (inode == NULL) {
1113                                 rcu_read_unlock();
1114                                 nfs_sb_deactive(server->super);
1115                                 goto restart;
1116                         }
1117                         delegation = nfs_start_delegation_return_locked(NFS_I(inode));
1118                         rcu_read_unlock();
1119                         if (delegation != NULL) {
1120                                 if (nfs_detach_delegation(NFS_I(inode), delegation,
1121                                                         server) != NULL)
1122                                         nfs_free_delegation(delegation);
1123                                 /* Match nfs_start_delegation_return_locked */
1124                                 nfs_put_delegation(delegation);
1125                         }
1126                         iput(inode);
1127                         nfs_sb_deactive(server->super);
1128                         cond_resched();
1129                         goto restart;
1130                 }
1131         }
1132         rcu_read_unlock();
1133 }
1134
1135 static inline bool nfs4_server_rebooted(const struct nfs_client *clp)
1136 {
1137         return (clp->cl_state & (BIT(NFS4CLNT_CHECK_LEASE) |
1138                                 BIT(NFS4CLNT_LEASE_EXPIRED) |
1139                                 BIT(NFS4CLNT_SESSION_RESET))) != 0;
1140 }
1141
1142 static void nfs_mark_test_expired_delegation(struct nfs_server *server,
1143             struct nfs_delegation *delegation)
1144 {
1145         if (delegation->stateid.type == NFS4_INVALID_STATEID_TYPE)
1146                 return;
1147         clear_bit(NFS_DELEGATION_NEED_RECLAIM, &delegation->flags);
1148         set_bit(NFS_DELEGATION_TEST_EXPIRED, &delegation->flags);
1149         set_bit(NFS4CLNT_DELEGATION_EXPIRED, &server->nfs_client->cl_state);
1150 }
1151
1152 static void nfs_inode_mark_test_expired_delegation(struct nfs_server *server,
1153                 struct inode *inode)
1154 {
1155         struct nfs_delegation *delegation;
1156
1157         rcu_read_lock();
1158         delegation = rcu_dereference(NFS_I(inode)->delegation);
1159         if (delegation)
1160                 nfs_mark_test_expired_delegation(server, delegation);
1161         rcu_read_unlock();
1162
1163 }
1164
1165 static void nfs_delegation_mark_test_expired_server(struct nfs_server *server)
1166 {
1167         struct nfs_delegation *delegation;
1168
1169         list_for_each_entry_rcu(delegation, &server->delegations, super_list)
1170                 nfs_mark_test_expired_delegation(server, delegation);
1171 }
1172
1173 /**
1174  * nfs_mark_test_expired_all_delegations - mark all delegations for testing
1175  * @clp: nfs_client to process
1176  *
1177  * Iterates through all the delegations associated with this server and
1178  * marks them as needing to be checked for validity.
1179  */
1180 void nfs_mark_test_expired_all_delegations(struct nfs_client *clp)
1181 {
1182         struct nfs_server *server;
1183
1184         rcu_read_lock();
1185         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
1186                 nfs_delegation_mark_test_expired_server(server);
1187         rcu_read_unlock();
1188 }
1189
1190 /**
1191  * nfs_test_expired_all_delegations - test all delegations for a client
1192  * @clp: nfs_client to process
1193  *
1194  * Helper for handling "recallable state revoked" status from server.
1195  */
1196 void nfs_test_expired_all_delegations(struct nfs_client *clp)
1197 {
1198         nfs_mark_test_expired_all_delegations(clp);
1199         nfs4_schedule_state_manager(clp);
1200 }
1201
1202 static void
1203 nfs_delegation_test_free_expired(struct inode *inode,
1204                 nfs4_stateid *stateid,
1205                 const struct cred *cred)
1206 {
1207         struct nfs_server *server = NFS_SERVER(inode);
1208         const struct nfs4_minor_version_ops *ops = server->nfs_client->cl_mvops;
1209         int status;
1210
1211         if (!cred)
1212                 return;
1213         status = ops->test_and_free_expired(server, stateid, cred);
1214         if (status == -NFS4ERR_EXPIRED || status == -NFS4ERR_BAD_STATEID)
1215                 nfs_remove_bad_delegation(inode, stateid);
1216 }
1217
1218 /**
1219  * nfs_reap_expired_delegations - reap expired delegations
1220  * @clp: nfs_client to process
1221  *
1222  * Iterates through all the delegations associated with this server and
1223  * checks if they have may have been revoked. This function is usually
1224  * expected to be called in cases where the server may have lost its
1225  * lease.
1226  */
1227 void nfs_reap_expired_delegations(struct nfs_client *clp)
1228 {
1229         struct nfs_delegation *delegation;
1230         struct nfs_server *server;
1231         struct inode *inode;
1232         const struct cred *cred;
1233         nfs4_stateid stateid;
1234
1235 restart:
1236         rcu_read_lock();
1237         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link) {
1238                 list_for_each_entry_rcu(delegation, &server->delegations,
1239                                                                 super_list) {
1240                         if (test_bit(NFS_DELEGATION_INODE_FREEING,
1241                                                 &delegation->flags) ||
1242                             test_bit(NFS_DELEGATION_RETURNING,
1243                                                 &delegation->flags) ||
1244                             test_bit(NFS_DELEGATION_TEST_EXPIRED,
1245                                                 &delegation->flags) == 0)
1246                                 continue;
1247                         if (!nfs_sb_active(server->super))
1248                                 break; /* continue in outer loop */
1249                         inode = nfs_delegation_grab_inode(delegation);
1250                         if (inode == NULL) {
1251                                 rcu_read_unlock();
1252                                 nfs_sb_deactive(server->super);
1253                                 goto restart;
1254                         }
1255                         cred = get_cred_rcu(delegation->cred);
1256                         nfs4_stateid_copy(&stateid, &delegation->stateid);
1257                         clear_bit(NFS_DELEGATION_TEST_EXPIRED, &delegation->flags);
1258                         rcu_read_unlock();
1259                         nfs_delegation_test_free_expired(inode, &stateid, cred);
1260                         put_cred(cred);
1261                         if (nfs4_server_rebooted(clp)) {
1262                                 nfs_inode_mark_test_expired_delegation(server,inode);
1263                                 iput(inode);
1264                                 nfs_sb_deactive(server->super);
1265                                 return;
1266                         }
1267                         iput(inode);
1268                         nfs_sb_deactive(server->super);
1269                         cond_resched();
1270                         goto restart;
1271                 }
1272         }
1273         rcu_read_unlock();
1274 }
1275
1276 void nfs_inode_find_delegation_state_and_recover(struct inode *inode,
1277                 const nfs4_stateid *stateid)
1278 {
1279         struct nfs_client *clp = NFS_SERVER(inode)->nfs_client;
1280         struct nfs_delegation *delegation;
1281         bool found = false;
1282
1283         rcu_read_lock();
1284         delegation = rcu_dereference(NFS_I(inode)->delegation);
1285         if (delegation &&
1286             nfs4_stateid_match_or_older(&delegation->stateid, stateid) &&
1287             !test_bit(NFS_DELEGATION_REVOKED, &delegation->flags)) {
1288                 nfs_mark_test_expired_delegation(NFS_SERVER(inode), delegation);
1289                 found = true;
1290         }
1291         rcu_read_unlock();
1292         if (found)
1293                 nfs4_schedule_state_manager(clp);
1294 }
1295
1296 /**
1297  * nfs_delegations_present - check for existence of delegations
1298  * @clp: client state handle
1299  *
1300  * Returns one if there are any nfs_delegation structures attached
1301  * to this nfs_client.
1302  */
1303 int nfs_delegations_present(struct nfs_client *clp)
1304 {
1305         struct nfs_server *server;
1306         int ret = 0;
1307
1308         rcu_read_lock();
1309         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
1310                 if (!list_empty(&server->delegations)) {
1311                         ret = 1;
1312                         break;
1313                 }
1314         rcu_read_unlock();
1315         return ret;
1316 }
1317
1318 /**
1319  * nfs4_refresh_delegation_stateid - Update delegation stateid seqid
1320  * @dst: stateid to refresh
1321  * @inode: inode to check
1322  *
1323  * Returns "true" and updates "dst->seqid" * if inode had a delegation
1324  * that matches our delegation stateid. Otherwise "false" is returned.
1325  */
1326 bool nfs4_refresh_delegation_stateid(nfs4_stateid *dst, struct inode *inode)
1327 {
1328         struct nfs_delegation *delegation;
1329         bool ret = false;
1330         if (!inode)
1331                 goto out;
1332
1333         rcu_read_lock();
1334         delegation = rcu_dereference(NFS_I(inode)->delegation);
1335         if (delegation != NULL &&
1336             nfs4_stateid_match_other(dst, &delegation->stateid) &&
1337             nfs4_stateid_is_newer(&delegation->stateid, dst) &&
1338             !test_bit(NFS_DELEGATION_REVOKED, &delegation->flags)) {
1339                 dst->seqid = delegation->stateid.seqid;
1340                 ret = true;
1341         }
1342         rcu_read_unlock();
1343 out:
1344         return ret;
1345 }
1346
1347 /**
1348  * nfs4_copy_delegation_stateid - Copy inode's state ID information
1349  * @inode: inode to check
1350  * @flags: delegation type requirement
1351  * @dst: stateid data structure to fill in
1352  * @cred: optional argument to retrieve credential
1353  *
1354  * Returns "true" and fills in "dst->data" * if inode had a delegation,
1355  * otherwise "false" is returned.
1356  */
1357 bool nfs4_copy_delegation_stateid(struct inode *inode, fmode_t flags,
1358                 nfs4_stateid *dst, const struct cred **cred)
1359 {
1360         struct nfs_inode *nfsi = NFS_I(inode);
1361         struct nfs_delegation *delegation;
1362         bool ret;
1363
1364         flags &= FMODE_READ|FMODE_WRITE;
1365         rcu_read_lock();
1366         delegation = rcu_dereference(nfsi->delegation);
1367         ret = nfs4_is_valid_delegation(delegation, flags);
1368         if (ret) {
1369                 nfs4_stateid_copy(dst, &delegation->stateid);
1370                 nfs_mark_delegation_referenced(delegation);
1371                 if (cred)
1372                         *cred = get_cred(delegation->cred);
1373         }
1374         rcu_read_unlock();
1375         return ret;
1376 }
1377
1378 /**
1379  * nfs4_delegation_flush_on_close - Check if we must flush file on close
1380  * @inode: inode to check
1381  *
1382  * This function checks the number of outstanding writes to the file
1383  * against the delegation 'space_limit' field to see if
1384  * the spec requires us to flush the file on close.
1385  */
1386 bool nfs4_delegation_flush_on_close(const struct inode *inode)
1387 {
1388         struct nfs_inode *nfsi = NFS_I(inode);
1389         struct nfs_delegation *delegation;
1390         bool ret = true;
1391
1392         rcu_read_lock();
1393         delegation = rcu_dereference(nfsi->delegation);
1394         if (delegation == NULL || !(delegation->type & FMODE_WRITE))
1395                 goto out;
1396         if (atomic_long_read(&nfsi->nrequests) < delegation->pagemod_limit)
1397                 ret = false;
1398 out:
1399         rcu_read_unlock();
1400         return ret;
1401 }
1402
1403 module_param_named(delegation_watermark, nfs_delegation_watermark, uint, 0644);