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 void nfs_mark_return_delegation(struct nfs_server *server,
  79                                        struct nfs_delegation *delegation)
  80 {
  81         set_bit(NFS_DELEGATION_RETURN, &delegation->flags);
  82         set_bit(NFS4CLNT_DELEGRETURN, &server->nfs_client->cl_state);
  83 }
  84
  85 static bool
  86 nfs4_is_valid_delegation(const struct nfs_delegation *delegation,
  87                 fmode_t flags)
  88 {
  89         if (delegation != NULL && (delegation->type & flags) == flags &&
  90             !test_bit(NFS_DELEGATION_REVOKED, &delegation->flags) &&
  91             !test_bit(NFS_DELEGATION_RETURNING, &delegation->flags))
  92                 return true;
  93         return false;
  94 }
  95
  96 struct nfs_delegation *nfs4_get_valid_delegation(const struct inode *inode)
  97 {
  98         struct nfs_delegation *delegation;
  99
 100         delegation = rcu_dereference(NFS_I(inode)->delegation);
 101         if (nfs4_is_valid_delegation(delegation, 0))
 102                 return delegation;
 103         return NULL;
 104 }
 105
 106 static int
 107 nfs4_do_check_delegation(struct inode *inode, fmode_t flags, bool mark)
 108 {
 109         struct nfs_delegation *delegation;
 110         int ret = 0;
 111
 112         flags &= FMODE_READ|FMODE_WRITE;
 113         rcu_read_lock();
 114         delegation = rcu_dereference(NFS_I(inode)->delegation);
 115         if (nfs4_is_valid_delegation(delegation, flags)) {
 116                 if (mark)
 117                         nfs_mark_delegation_referenced(delegation);
 118                 ret = 1;
 119         }
 120         rcu_read_unlock();
 121         return ret;
 122 }
 123 /**
 124  * nfs_have_delegation - check if inode has a delegation, mark it
 125  * NFS_DELEGATION_REFERENCED if there is one.
 126  * @inode: inode to check
 127  * @flags: delegation types to check for
 128  *
 129  * Returns one if inode has the indicated delegation, otherwise zero.
 130  */
 131 int nfs4_have_delegation(struct inode *inode, fmode_t flags)
 132 {
 133         return nfs4_do_check_delegation(inode, flags, true);
 134 }
 135
 136 /*
 137  * nfs4_check_delegation - check if inode has a delegation, do not mark
 138  * NFS_DELEGATION_REFERENCED if it has one.
 139  */
 140 int nfs4_check_delegation(struct inode *inode, fmode_t flags)
 141 {
 142         return nfs4_do_check_delegation(inode, flags, false);
 143 }
 144
 145 static int nfs_delegation_claim_locks(struct nfs4_state *state, const nfs4_stateid *stateid)
 146 {
 147         struct inode *inode = state->inode;
 148         struct file_lock *fl;
 149         struct file_lock_context *flctx = inode->i_flctx;
 150         struct list_head *list;
 151         int status = 0;
 152
 153         if (flctx == NULL)
 154                 goto out;
 155
 156         list = &flctx->flc_posix;
 157         spin_lock(&flctx->flc_lock);
 158 restart:
 159         list_for_each_entry(fl, list, fl_list) {
 160                 if (nfs_file_open_context(fl->fl_file)->state != state)
 161                         continue;
 162                 spin_unlock(&flctx->flc_lock);
 163                 status = nfs4_lock_delegation_recall(fl, state, stateid);
 164                 if (status < 0)
 165                         goto out;
 166                 spin_lock(&flctx->flc_lock);
 167         }
 168         if (list == &flctx->flc_posix) {
 169                 list = &flctx->flc_flock;
 170                 goto restart;
 171         }
 172         spin_unlock(&flctx->flc_lock);
 173 out:
 174         return status;
 175 }
 176
 177 static int nfs_delegation_claim_opens(struct inode *inode,
 178                 const nfs4_stateid *stateid, fmode_t type)
 179 {
 180         struct nfs_inode *nfsi = NFS_I(inode);
 181         struct nfs_open_context *ctx;
 182         struct nfs4_state_owner *sp;
 183         struct nfs4_state *state;
 184         unsigned int seq;
 185         int err;
 186
 187 again:
 188         rcu_read_lock();
 189         list_for_each_entry_rcu(ctx, &nfsi->open_files, list) {
 190                 state = ctx->state;
 191                 if (state == NULL)
 192                         continue;
 193                 if (!test_bit(NFS_DELEGATED_STATE, &state->flags))
 194                         continue;
 195                 if (!nfs4_valid_open_stateid(state))
 196                         continue;
 197                 if (!nfs4_stateid_match(&state->stateid, stateid))
 198                         continue;
 199                 if (!get_nfs_open_context(ctx))
 200                         continue;
 201                 rcu_read_unlock();
 202                 sp = state->owner;
 203                 /* Block nfs4_proc_unlck */
 204                 mutex_lock(&sp->so_delegreturn_mutex);
 205                 seq = raw_seqcount_begin(&sp->so_reclaim_seqcount);
 206                 err = nfs4_open_delegation_recall(ctx, state, stateid);
 207                 if (!err)
 208                         err = nfs_delegation_claim_locks(state, stateid);
 209                 if (!err && read_seqcount_retry(&sp->so_reclaim_seqcount, seq))
 210                         err = -EAGAIN;
 211                 mutex_unlock(&sp->so_delegreturn_mutex);
 212                 put_nfs_open_context(ctx);
 213                 if (err != 0)
 214                         return err;
 215                 goto again;
 216         }
 217         rcu_read_unlock();
 218         return 0;
 219 }
 220
 221 /**
 222  * nfs_inode_reclaim_delegation - process a delegation reclaim request
 223  * @inode: inode to process
 224  * @cred: credential to use for request
 225  * @type: delegation type
 226  * @stateid: delegation stateid
 227  * @pagemod_limit: write delegation "space_limit"
 228  *
 229  */
 230 void nfs_inode_reclaim_delegation(struct inode *inode, const struct cred *cred,
 231                                   fmode_t type,
 232                                   const nfs4_stateid *stateid,
 233                                   unsigned long pagemod_limit)
 234 {
 235         struct nfs_delegation *delegation;
 236         const struct cred *oldcred = NULL;
 237
 238         rcu_read_lock();
 239         delegation = rcu_dereference(NFS_I(inode)->delegation);
 240         if (delegation != NULL) {
 241                 spin_lock(&delegation->lock);
 242                 if (nfs4_is_valid_delegation(delegation, 0)) {
 243                         nfs4_stateid_copy(&delegation->stateid, stateid);
 244                         delegation->type = type;
 245                         delegation->pagemod_limit = pagemod_limit;
 246                         oldcred = delegation->cred;
 247                         delegation->cred = get_cred(cred);
 248                         clear_bit(NFS_DELEGATION_NEED_RECLAIM,
 249                                   &delegation->flags);
 250                         spin_unlock(&delegation->lock);
 251                         rcu_read_unlock();
 252                         put_cred(oldcred);
 253                         trace_nfs4_reclaim_delegation(inode, type);
 254                         return;
 255                 }
 256                 /* We appear to have raced with a delegation return. */
 257                 spin_unlock(&delegation->lock);
 258         }
 259         rcu_read_unlock();
 260         nfs_inode_set_delegation(inode, cred, type, stateid, pagemod_limit);
 261 }
 262
 263 static int nfs_do_return_delegation(struct inode *inode, struct nfs_delegation *delegation, int issync)
 264 {
 265         const struct cred *cred;
 266         int res = 0;
 267
 268         if (!test_bit(NFS_DELEGATION_REVOKED, &delegation->flags)) {
 269                 spin_lock(&delegation->lock);
 270                 cred = get_cred(delegation->cred);
 271                 spin_unlock(&delegation->lock);
 272                 res = nfs4_proc_delegreturn(inode, cred,
 273                                 &delegation->stateid,
 274                                 issync);
 275                 put_cred(cred);
 276         }
 277         return res;
 278 }
 279
 280 static struct inode *nfs_delegation_grab_inode(struct nfs_delegation *delegation)
 281 {
 282         struct inode *inode = NULL;
 283
 284         spin_lock(&delegation->lock);
 285         if (delegation->inode != NULL)
 286                 inode = igrab(delegation->inode);
 287         if (!inode)
 288                 set_bit(NFS_DELEGATION_INODE_FREEING, &delegation->flags);
 289         spin_unlock(&delegation->lock);
 290         return inode;
 291 }
 292
 293 static struct nfs_delegation *
 294 nfs_start_delegation_return_locked(struct nfs_inode *nfsi)
 295 {
 296         struct nfs_delegation *ret = NULL;
 297         struct nfs_delegation *delegation = rcu_dereference(nfsi->delegation);
 298
 299         if (delegation == NULL)
 300                 goto out;
 301         spin_lock(&delegation->lock);
 302         if (!test_and_set_bit(NFS_DELEGATION_RETURNING, &delegation->flags)) {
 303                 clear_bit(NFS_DELEGATION_RETURN_DELAYED, &delegation->flags);
 304                 /* Refcount matched in nfs_end_delegation_return() */
 305                 ret = nfs_get_delegation(delegation);
 306         }
 307         spin_unlock(&delegation->lock);
 308         if (ret)
 309                 nfs_clear_verifier_delegated(&nfsi->vfs_inode);
 310 out:
 311         return ret;
 312 }
 313
 314 static struct nfs_delegation *
 315 nfs_start_delegation_return(struct nfs_inode *nfsi)
 316 {
 317         struct nfs_delegation *delegation;
 318
 319         rcu_read_lock();
 320         delegation = nfs_start_delegation_return_locked(nfsi);
 321         rcu_read_unlock();
 322         return delegation;
 323 }
 324
 325 static void nfs_abort_delegation_return(struct nfs_delegation *delegation,
 326                                         struct nfs_client *clp, int err)
 327 {
 328
 329         spin_lock(&delegation->lock);
 330         clear_bit(NFS_DELEGATION_RETURNING, &delegation->flags);
 331         if (err == -EAGAIN) {
 332                 set_bit(NFS_DELEGATION_RETURN_DELAYED, &delegation->flags);
 333                 set_bit(NFS4CLNT_DELEGRETURN_DELAYED, &clp->cl_state);
 334         }
 335         spin_unlock(&delegation->lock);
 336 }
 337
 338 static struct nfs_delegation *
 339 nfs_detach_delegation_locked(struct nfs_inode *nfsi,
 340                 struct nfs_delegation *delegation,
 341                 struct nfs_client *clp)
 342 {
 343         struct nfs_delegation *deleg_cur =
 344                 rcu_dereference_protected(nfsi->delegation,
 345                                 lockdep_is_held(&clp->cl_lock));
 346
 347         if (deleg_cur == NULL || delegation != deleg_cur)
 348                 return NULL;
 349
 350         spin_lock(&delegation->lock);
 351         if (!delegation->inode) {
 352                 spin_unlock(&delegation->lock);
 353                 return NULL;
 354         }
 355         list_del_rcu(&delegation->super_list);
 356         delegation->inode = NULL;
 357         rcu_assign_pointer(nfsi->delegation, NULL);
 358         spin_unlock(&delegation->lock);
 359         return delegation;
 360 }
 361
 362 static struct nfs_delegation *nfs_detach_delegation(struct nfs_inode *nfsi,
 363                 struct nfs_delegation *delegation,
 364                 struct nfs_server *server)
 365 {
 366         struct nfs_client *clp = server->nfs_client;
 367
 368         spin_lock(&clp->cl_lock);
 369         delegation = nfs_detach_delegation_locked(nfsi, delegation, clp);
 370         spin_unlock(&clp->cl_lock);
 371         return delegation;
 372 }
 373
 374 static struct nfs_delegation *
 375 nfs_inode_detach_delegation(struct inode *inode)
 376 {
 377         struct nfs_inode *nfsi = NFS_I(inode);
 378         struct nfs_server *server = NFS_SERVER(inode);
 379         struct nfs_delegation *delegation;
 380
 381         rcu_read_lock();
 382         delegation = rcu_dereference(nfsi->delegation);
 383         if (delegation != NULL)
 384                 delegation = nfs_detach_delegation(nfsi, delegation, server);
 385         rcu_read_unlock();
 386         return delegation;
 387 }
 388
 389 static void
 390 nfs_update_delegation_cred(struct nfs_delegation *delegation,
 391                 const struct cred *cred)
 392 {
 393         const struct cred *old;
 394
 395         if (cred_fscmp(delegation->cred, cred) != 0) {
 396                 old = xchg(&delegation->cred, get_cred(cred));
 397                 put_cred(old);
 398         }
 399 }
 400
 401 static void
 402 nfs_update_inplace_delegation(struct nfs_delegation *delegation,
 403                 const struct nfs_delegation *update)
 404 {
 405         if (nfs4_stateid_is_newer(&update->stateid, &delegation->stateid)) {
 406                 delegation->stateid.seqid = update->stateid.seqid;
 407                 smp_wmb();
 408                 delegation->type = update->type;
 409                 delegation->pagemod_limit = update->pagemod_limit;
 410                 if (test_bit(NFS_DELEGATION_REVOKED, &delegation->flags)) {
 411                         delegation->change_attr = update->change_attr;
 412                         nfs_update_delegation_cred(delegation, update->cred);
 413                         /* smp_mb__before_atomic() is implicit due to xchg() */
 414                         clear_bit(NFS_DELEGATION_REVOKED, &delegation->flags);
 415                         atomic_long_inc(&nfs_active_delegations);
 416                 }
 417         }
 418 }
 419
 420 /**
 421  * nfs_inode_set_delegation - set up a delegation on an inode
 422  * @inode: inode to which delegation applies
 423  * @cred: cred to use for subsequent delegation processing
 424  * @type: delegation type
 425  * @stateid: delegation stateid
 426  * @pagemod_limit: write delegation "space_limit"
 427  *
 428  * Returns zero on success, or a negative errno value.
 429  */
 430 int nfs_inode_set_delegation(struct inode *inode, const struct cred *cred,
 431                                   fmode_t type,
 432                                   const nfs4_stateid *stateid,
 433                                   unsigned long pagemod_limit)
 434 {
 435         struct nfs_server *server = NFS_SERVER(inode);
 436         struct nfs_client *clp = server->nfs_client;
 437         struct nfs_inode *nfsi = NFS_I(inode);
 438         struct nfs_delegation *delegation, *old_delegation;
 439         struct nfs_delegation *freeme = NULL;
 440         int status = 0;
 441
 442         delegation = kmalloc(sizeof(*delegation), GFP_NOFS);
 443         if (delegation == NULL)
 444                 return -ENOMEM;
 445         nfs4_stateid_copy(&delegation->stateid, stateid);
 446         refcount_set(&delegation->refcount, 1);
 447         delegation->type = type;
 448         delegation->pagemod_limit = pagemod_limit;
 449         delegation->change_attr = inode_peek_iversion_raw(inode);
 450         delegation->cred = get_cred(cred);
 451         delegation->inode = inode;
 452         delegation->flags = 1<<NFS_DELEGATION_REFERENCED;
 453         spin_lock_init(&delegation->lock);
 454
 455         spin_lock(&clp->cl_lock);
 456         old_delegation = rcu_dereference_protected(nfsi->delegation,
 457                                         lockdep_is_held(&clp->cl_lock));
 458         if (old_delegation == NULL)
 459                 goto add_new;
 460         /* Is this an update of the existing delegation? */
 461         if (nfs4_stateid_match_other(&old_delegation->stateid,
 462                                 &delegation->stateid)) {
 463                 spin_lock(&old_delegation->lock);
 464                 nfs_update_inplace_delegation(old_delegation,
 465                                 delegation);
 466                 spin_unlock(&old_delegation->lock);
 467                 goto out;
 468         }
 469         if (!test_bit(NFS_DELEGATION_REVOKED, &old_delegation->flags)) {
 470                 /*
 471                  * Deal with broken servers that hand out two
 472                  * delegations for the same file.
 473                  * Allow for upgrades to a WRITE delegation, but
 474                  * nothing else.
 475                  */
 476                 dfprintk(FILE, "%s: server %s handed out "
 477                                 "a duplicate delegation!\n",
 478                                 __func__, clp->cl_hostname);
 479                 if (delegation->type == old_delegation->type ||
 480                     !(delegation->type & FMODE_WRITE)) {
 481                         freeme = delegation;
 482                         delegation = NULL;
 483                         goto out;
 484                 }
 485                 if (test_and_set_bit(NFS_DELEGATION_RETURNING,
 486                                         &old_delegation->flags))
 487                         goto out;
 488         }
 489         freeme = nfs_detach_delegation_locked(nfsi, old_delegation, clp);
 490         if (freeme == NULL)
 491                 goto out;
 492 add_new:
 493         list_add_tail_rcu(&delegation->super_list, &server->delegations);
 494         rcu_assign_pointer(nfsi->delegation, delegation);
 495         delegation = NULL;
 496
 497         atomic_long_inc(&nfs_active_delegations);
 498
 499         trace_nfs4_set_delegation(inode, type);
 500
 501         spin_lock(&inode->i_lock);
 502         if (NFS_I(inode)->cache_validity & (NFS_INO_INVALID_ATTR|NFS_INO_INVALID_ATIME))
 503                 NFS_I(inode)->cache_validity |= NFS_INO_REVAL_FORCED;
 504         spin_unlock(&inode->i_lock);
 505 out:
 506         spin_unlock(&clp->cl_lock);
 507         if (delegation != NULL)
 508                 __nfs_free_delegation(delegation);
 509         if (freeme != NULL) {
 510                 nfs_do_return_delegation(inode, freeme, 0);
 511                 nfs_free_delegation(freeme);
 512         }
 513         return status;
 514 }
 515
 516 /*
 517  * Basic procedure for returning a delegation to the server
 518  */
 519 static int nfs_end_delegation_return(struct inode *inode, struct nfs_delegation *delegation, int issync)
 520 {
 521         struct nfs_client *clp = NFS_SERVER(inode)->nfs_client;
 522         int err = 0;
 523
 524         if (delegation == NULL)
 525                 return 0;
 526         do {
 527                 if (test_bit(NFS_DELEGATION_REVOKED, &delegation->flags))
 528                         break;
 529                 err = nfs_delegation_claim_opens(inode, &delegation->stateid,
 530                                 delegation->type);
 531                 if (!issync || err != -EAGAIN)
 532                         break;
 533                 /*
 534                  * Guard against state recovery
 535                  */
 536                 err = nfs4_wait_clnt_recover(clp);
 537         } while (err == 0);
 538
 539         if (err) {
 540                 nfs_abort_delegation_return(delegation, clp, err);
 541                 goto out;
 542         }
 543
 544         err = nfs_do_return_delegation(inode, delegation, issync);
 545 out:
 546         /* Refcount matched in nfs_start_delegation_return_locked() */
 547         nfs_put_delegation(delegation);
 548         return err;
 549 }
 550
 551 static bool nfs_delegation_need_return(struct nfs_delegation *delegation)
 552 {
 553         bool ret = false;
 554
 555         if (test_and_clear_bit(NFS_DELEGATION_RETURN, &delegation->flags))
 556                 ret = true;
 557         else if (test_bit(NFS_DELEGATION_RETURN_IF_CLOSED, &delegation->flags)) {
 558                 struct inode *inode;
 559
 560                 spin_lock(&delegation->lock);
 561                 inode = delegation->inode;
 562                 if (inode && list_empty(&NFS_I(inode)->open_files))
 563                         ret = true;
 564                 spin_unlock(&delegation->lock);
 565         }
 566         if (ret)
 567                 clear_bit(NFS_DELEGATION_RETURN_IF_CLOSED, &delegation->flags);
 568         if (test_bit(NFS_DELEGATION_RETURNING, &delegation->flags) ||
 569             test_bit(NFS_DELEGATION_RETURN_DELAYED, &delegation->flags) ||
 570             test_bit(NFS_DELEGATION_REVOKED, &delegation->flags))
 571                 ret = false;
 572
 573         return ret;
 574 }
 575
 576 static int nfs_server_return_marked_delegations(struct nfs_server *server,
 577                 void __always_unused *data)
 578 {
 579         struct nfs_delegation *delegation;
 580         struct nfs_delegation *prev;
 581         struct inode *inode;
 582         struct inode *place_holder = NULL;
 583         struct nfs_delegation *place_holder_deleg = NULL;
 584         int err = 0;
 585
 586 restart:
 587         /*
 588          * To avoid quadratic looping we hold a reference
 589          * to an inode place_holder.  Each time we restart, we
 590          * list delegation in the server from the delegations
 591          * of that inode.
 592          * prev is an RCU-protected pointer to a delegation which
 593          * wasn't marked for return and might be a good choice for
 594          * the next place_holder.
 595          */
 596         prev = NULL;
 597         delegation = NULL;
 598         rcu_read_lock();
 599         if (place_holder)
 600                 delegation = rcu_dereference(NFS_I(place_holder)->delegation);
 601         if (!delegation || delegation != place_holder_deleg)
 602                 delegation = list_entry_rcu(server->delegations.next,
 603                                             struct nfs_delegation, super_list);
 604         list_for_each_entry_from_rcu(delegation, &server->delegations, super_list) {
 605                 struct inode *to_put = NULL;
 606
 607                 if (test_bit(NFS_DELEGATION_INODE_FREEING, &delegation->flags))
 608                         continue;
 609                 if (!nfs_delegation_need_return(delegation)) {
 610                         if (nfs4_is_valid_delegation(delegation, 0))
 611                                 prev = delegation;
 612                         continue;
 613                 }
 614
 615                 if (prev) {
 616                         struct inode *tmp = nfs_delegation_grab_inode(prev);
 617                         if (tmp) {
 618                                 to_put = place_holder;
 619                                 place_holder = tmp;
 620                                 place_holder_deleg = prev;
 621                         }
 622                 }
 623
 624                 inode = nfs_delegation_grab_inode(delegation);
 625                 if (inode == NULL) {
 626                         rcu_read_unlock();
 627                         iput(to_put);
 628                         goto restart;
 629                 }
 630                 delegation = nfs_start_delegation_return_locked(NFS_I(inode));
 631                 rcu_read_unlock();
 632
 633                 iput(to_put);
 634
 635                 err = nfs_end_delegation_return(inode, delegation, 0);
 636                 iput(inode);
 637                 cond_resched();
 638                 if (!err)
 639                         goto restart;
 640                 set_bit(NFS4CLNT_DELEGRETURN, &server->nfs_client->cl_state);
 641                 goto out;
 642         }
 643         rcu_read_unlock();
 644 out:
 645         iput(place_holder);
 646         return err;
 647 }
 648
 649 static bool nfs_server_clear_delayed_delegations(struct nfs_server *server)
 650 {
 651         struct nfs_delegation *d;
 652         bool ret = false;
 653
 654         list_for_each_entry_rcu (d, &server->delegations, super_list) {
 655                 if (!test_bit(NFS_DELEGATION_RETURN_DELAYED, &d->flags))
 656                         continue;
 657                 nfs_mark_return_delegation(server, d);
 658                 clear_bit(NFS_DELEGATION_RETURN_DELAYED, &d->flags);
 659                 ret = true;
 660         }
 661         return ret;
 662 }
 663
 664 static bool nfs_client_clear_delayed_delegations(struct nfs_client *clp)
 665 {
 666         struct nfs_server *server;
 667         bool ret = false;
 668
 669         if (!test_and_clear_bit(NFS4CLNT_DELEGRETURN_DELAYED, &clp->cl_state))
 670                 goto out;
 671         rcu_read_lock();
 672         list_for_each_entry_rcu (server, &clp->cl_superblocks, client_link) {
 673                 if (nfs_server_clear_delayed_delegations(server))
 674                         ret = true;
 675         }
 676         rcu_read_unlock();
 677 out:
 678         return ret;
 679 }
 680
 681 /**
 682  * nfs_client_return_marked_delegations - return previously marked delegations
 683  * @clp: nfs_client to process
 684  *
 685  * Note that this function is designed to be called by the state
 686  * manager thread. For this reason, it cannot flush the dirty data,
 687  * since that could deadlock in case of a state recovery error.
 688  *
 689  * Returns zero on success, or a negative errno value.
 690  */
 691 int nfs_client_return_marked_delegations(struct nfs_client *clp)
 692 {
 693         int err = nfs_client_for_each_server(
 694                 clp, nfs_server_return_marked_delegations, NULL);
 695         if (err)
 696                 return err;
 697         /* If a return was delayed, sleep to prevent hard looping */
 698         if (nfs_client_clear_delayed_delegations(clp))
 699                 ssleep(1);
 700         return 0;
 701 }
 702
 703 /**
 704  * nfs_inode_evict_delegation - return delegation, don't reclaim opens
 705  * @inode: inode to process
 706  *
 707  * Does not protect against delegation reclaims, therefore really only safe
 708  * to be called from nfs4_clear_inode(). Guaranteed to always free
 709  * the delegation structure.
 710  */
 711 void nfs_inode_evict_delegation(struct inode *inode)
 712 {
 713         struct nfs_delegation *delegation;
 714
 715         delegation = nfs_inode_detach_delegation(inode);
 716         if (delegation != NULL) {
 717                 set_bit(NFS_DELEGATION_RETURNING, &delegation->flags);
 718                 set_bit(NFS_DELEGATION_INODE_FREEING, &delegation->flags);
 719                 nfs_do_return_delegation(inode, delegation, 1);
 720                 nfs_free_delegation(delegation);
 721         }
 722 }
 723
 724 /**
 725  * nfs_inode_return_delegation - synchronously return a delegation
 726  * @inode: inode to process
 727  *
 728  * This routine will always flush any dirty data to disk on the
 729  * assumption that if we need to return the delegation, then
 730  * we should stop caching.
 731  *
 732  * Returns zero on success, or a negative errno value.
 733  */
 734 int nfs4_inode_return_delegation(struct inode *inode)
 735 {
 736         struct nfs_inode *nfsi = NFS_I(inode);
 737         struct nfs_delegation *delegation;
 738         int err = 0;
 739
 740         nfs_wb_all(inode);
 741         delegation = nfs_start_delegation_return(nfsi);
 742         if (delegation != NULL)
 743                 err = nfs_end_delegation_return(inode, delegation, 1);
 744         return err;
 745 }
 746
 747 /**
 748  * nfs_inode_return_delegation_on_close - asynchronously return a delegation
 749  * @inode: inode to process
 750  *
 751  * This routine is called on file close in order to determine if the
 752  * inode delegation needs to be returned immediately.
 753  */
 754 void nfs4_inode_return_delegation_on_close(struct inode *inode)
 755 {
 756         struct nfs_delegation *delegation;
 757         struct nfs_delegation *ret = NULL;
 758
 759         if (!inode)
 760                 return;
 761         rcu_read_lock();
 762         delegation = nfs4_get_valid_delegation(inode);
 763         if (!delegation)
 764                 goto out;
 765         if (test_bit(NFS_DELEGATION_RETURN_IF_CLOSED, &delegation->flags) ||
 766             atomic_long_read(&nfs_active_delegations) >= nfs_delegation_watermark) {
 767                 spin_lock(&delegation->lock);
 768                 if (delegation->inode &&
 769                     list_empty(&NFS_I(inode)->open_files) &&
 770                     !test_and_set_bit(NFS_DELEGATION_RETURNING, &delegation->flags)) {
 771                         clear_bit(NFS_DELEGATION_RETURN_IF_CLOSED, &delegation->flags);
 772                         /* Refcount matched in nfs_end_delegation_return() */
 773                         ret = nfs_get_delegation(delegation);
 774                 }
 775                 spin_unlock(&delegation->lock);
 776                 if (ret)
 777                         nfs_clear_verifier_delegated(inode);
 778         }
 779 out:
 780         rcu_read_unlock();
 781         nfs_end_delegation_return(inode, ret, 0);
 782 }
 783
 784 /**
 785  * nfs4_inode_make_writeable
 786  * @inode: pointer to inode
 787  *
 788  * Make the inode writeable by returning the delegation if necessary
 789  *
 790  * Returns zero on success, or a negative errno value.
 791  */
 792 int nfs4_inode_make_writeable(struct inode *inode)
 793 {
 794         struct nfs_delegation *delegation;
 795
 796         rcu_read_lock();
 797         delegation = nfs4_get_valid_delegation(inode);
 798         if (delegation == NULL ||
 799             (nfs4_has_session(NFS_SERVER(inode)->nfs_client) &&
 800              (delegation->type & FMODE_WRITE))) {
 801                 rcu_read_unlock();
 802                 return 0;
 803         }
 804         rcu_read_unlock();
 805         return nfs4_inode_return_delegation(inode);
 806 }
 807
 808 static void nfs_mark_return_if_closed_delegation(struct nfs_server *server,
 809                 struct nfs_delegation *delegation)
 810 {
 811         set_bit(NFS_DELEGATION_RETURN_IF_CLOSED, &delegation->flags);
 812         set_bit(NFS4CLNT_DELEGRETURN, &server->nfs_client->cl_state);
 813 }
 814
 815 static bool nfs_server_mark_return_all_delegations(struct nfs_server *server)
 816 {
 817         struct nfs_delegation *delegation;
 818         bool ret = false;
 819
 820         list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
 821                 nfs_mark_return_delegation(server, delegation);
 822                 ret = true;
 823         }
 824         return ret;
 825 }
 826
 827 static void nfs_client_mark_return_all_delegations(struct nfs_client *clp)
 828 {
 829         struct nfs_server *server;
 830
 831         rcu_read_lock();
 832         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
 833                 nfs_server_mark_return_all_delegations(server);
 834         rcu_read_unlock();
 835 }
 836
 837 static void nfs_delegation_run_state_manager(struct nfs_client *clp)
 838 {
 839         if (test_bit(NFS4CLNT_DELEGRETURN, &clp->cl_state))
 840                 nfs4_schedule_state_manager(clp);
 841 }
 842
 843 /**
 844  * nfs_expire_all_delegations
 845  * @clp: client to process
 846  *
 847  */
 848 void nfs_expire_all_delegations(struct nfs_client *clp)
 849 {
 850         nfs_client_mark_return_all_delegations(clp);
 851         nfs_delegation_run_state_manager(clp);
 852 }
 853
 854 /**
 855  * nfs_super_return_all_delegations - return delegations for one superblock
 856  * @server: pointer to nfs_server to process
 857  *
 858  */
 859 void nfs_server_return_all_delegations(struct nfs_server *server)
 860 {
 861         struct nfs_client *clp = server->nfs_client;
 862         bool need_wait;
 863
 864         if (clp == NULL)
 865                 return;
 866
 867         rcu_read_lock();
 868         need_wait = nfs_server_mark_return_all_delegations(server);
 869         rcu_read_unlock();
 870
 871         if (need_wait) {
 872                 nfs4_schedule_state_manager(clp);
 873                 nfs4_wait_clnt_recover(clp);
 874         }
 875 }
 876
 877 static void nfs_mark_return_unused_delegation_types(struct nfs_server *server,
 878                                                  fmode_t flags)
 879 {
 880         struct nfs_delegation *delegation;
 881
 882         list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
 883                 if ((delegation->type == (FMODE_READ|FMODE_WRITE)) && !(flags & FMODE_WRITE))
 884                         continue;
 885                 if (delegation->type & flags)
 886                         nfs_mark_return_if_closed_delegation(server, delegation);
 887         }
 888 }
 889
 890 static void nfs_client_mark_return_unused_delegation_types(struct nfs_client *clp,
 891                                                         fmode_t flags)
 892 {
 893         struct nfs_server *server;
 894
 895         rcu_read_lock();
 896         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
 897                 nfs_mark_return_unused_delegation_types(server, flags);
 898         rcu_read_unlock();
 899 }
 900
 901 static void nfs_revoke_delegation(struct inode *inode,
 902                 const nfs4_stateid *stateid)
 903 {
 904         struct nfs_delegation *delegation;
 905         nfs4_stateid tmp;
 906         bool ret = false;
 907
 908         rcu_read_lock();
 909         delegation = rcu_dereference(NFS_I(inode)->delegation);
 910         if (delegation == NULL)
 911                 goto out;
 912         if (stateid == NULL) {
 913                 nfs4_stateid_copy(&tmp, &delegation->stateid);
 914                 stateid = &tmp;
 915         } else {
 916                 if (!nfs4_stateid_match_other(stateid, &delegation->stateid))
 917                         goto out;
 918                 spin_lock(&delegation->lock);
 919                 if (stateid->seqid) {
 920                         if (nfs4_stateid_is_newer(&delegation->stateid, stateid)) {
 921                                 spin_unlock(&delegation->lock);
 922                                 goto out;
 923                         }
 924                         delegation->stateid.seqid = stateid->seqid;
 925                 }
 926                 spin_unlock(&delegation->lock);
 927         }
 928         nfs_mark_delegation_revoked(delegation);
 929         ret = true;
 930 out:
 931         rcu_read_unlock();
 932         if (ret)
 933                 nfs_inode_find_state_and_recover(inode, stateid);
 934 }
 935
 936 void nfs_remove_bad_delegation(struct inode *inode,
 937                 const nfs4_stateid *stateid)
 938 {
 939         nfs_revoke_delegation(inode, stateid);
 940 }
 941 EXPORT_SYMBOL_GPL(nfs_remove_bad_delegation);
 942
 943 void nfs_delegation_mark_returned(struct inode *inode,
 944                 const nfs4_stateid *stateid)
 945 {
 946         struct nfs_delegation *delegation;
 947
 948         if (!inode)
 949                 return;
 950
 951         rcu_read_lock();
 952         delegation = rcu_dereference(NFS_I(inode)->delegation);
 953         if (!delegation)
 954                 goto out_rcu_unlock;
 955
 956         spin_lock(&delegation->lock);
 957         if (!nfs4_stateid_match_other(stateid, &delegation->stateid))
 958                 goto out_spin_unlock;
 959         if (stateid->seqid) {
 960                 /* If delegation->stateid is newer, dont mark as returned */
 961                 if (nfs4_stateid_is_newer(&delegation->stateid, stateid))
 962                         goto out_clear_returning;
 963                 if (delegation->stateid.seqid != stateid->seqid)
 964                         delegation->stateid.seqid = stateid->seqid;
 965         }
 966
 967         nfs_mark_delegation_revoked(delegation);
 968
 969 out_clear_returning:
 970         clear_bit(NFS_DELEGATION_RETURNING, &delegation->flags);
 971 out_spin_unlock:
 972         spin_unlock(&delegation->lock);
 973 out_rcu_unlock:
 974         rcu_read_unlock();
 975
 976         nfs_inode_find_state_and_recover(inode, stateid);
 977 }
 978
 979 /**
 980  * nfs_expire_unused_delegation_types
 981  * @clp: client to process
 982  * @flags: delegation types to expire
 983  *
 984  */
 985 void nfs_expire_unused_delegation_types(struct nfs_client *clp, fmode_t flags)
 986 {
 987         nfs_client_mark_return_unused_delegation_types(clp, flags);
 988         nfs_delegation_run_state_manager(clp);
 989 }
 990
 991 static void nfs_mark_return_unreferenced_delegations(struct nfs_server *server)
 992 {
 993         struct nfs_delegation *delegation;
 994
 995         list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
 996                 if (test_and_clear_bit(NFS_DELEGATION_REFERENCED, &delegation->flags))
 997                         continue;
 998                 nfs_mark_return_if_closed_delegation(server, delegation);
 999         }
1000 }
1001
1002 /**
1003  * nfs_expire_unreferenced_delegations - Eliminate unused delegations
1004  * @clp: nfs_client to process
1005  *
1006  */
1007 void nfs_expire_unreferenced_delegations(struct nfs_client *clp)
1008 {
1009         struct nfs_server *server;
1010
1011         rcu_read_lock();
1012         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
1013                 nfs_mark_return_unreferenced_delegations(server);
1014         rcu_read_unlock();
1015
1016         nfs_delegation_run_state_manager(clp);
1017 }
1018
1019 /**
1020  * nfs_async_inode_return_delegation - asynchronously return a delegation
1021  * @inode: inode to process
1022  * @stateid: state ID information
1023  *
1024  * Returns zero on success, or a negative errno value.
1025  */
1026 int nfs_async_inode_return_delegation(struct inode *inode,
1027                                       const nfs4_stateid *stateid)
1028 {
1029         struct nfs_server *server = NFS_SERVER(inode);
1030         struct nfs_client *clp = server->nfs_client;
1031         struct nfs_delegation *delegation;
1032
1033         rcu_read_lock();
1034         delegation = nfs4_get_valid_delegation(inode);
1035         if (delegation == NULL)
1036                 goto out_enoent;
1037         if (stateid != NULL &&
1038             !clp->cl_mvops->match_stateid(&delegation->stateid, stateid))
1039                 goto out_enoent;
1040         nfs_mark_return_delegation(server, delegation);
1041         rcu_read_unlock();
1042
1043         nfs_delegation_run_state_manager(clp);
1044         return 0;
1045 out_enoent:
1046         rcu_read_unlock();
1047         return -ENOENT;
1048 }
1049
1050 static struct inode *
1051 nfs_delegation_find_inode_server(struct nfs_server *server,
1052                                  const struct nfs_fh *fhandle)
1053 {
1054         struct nfs_delegation *delegation;
1055         struct super_block *freeme = NULL;
1056         struct inode *res = NULL;
1057
1058         list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
1059                 spin_lock(&delegation->lock);
1060                 if (delegation->inode != NULL &&
1061                     !test_bit(NFS_DELEGATION_REVOKED, &delegation->flags) &&
1062                     nfs_compare_fh(fhandle, &NFS_I(delegation->inode)->fh) == 0) {
1063                         if (nfs_sb_active(server->super)) {
1064                                 freeme = server->super;
1065                                 res = igrab(delegation->inode);
1066                         }
1067                         spin_unlock(&delegation->lock);
1068                         if (res != NULL)
1069                                 return res;
1070                         if (freeme) {
1071                                 rcu_read_unlock();
1072                                 nfs_sb_deactive(freeme);
1073                                 rcu_read_lock();
1074                         }
1075                         return ERR_PTR(-EAGAIN);
1076                 }
1077                 spin_unlock(&delegation->lock);
1078         }
1079         return ERR_PTR(-ENOENT);
1080 }
1081
1082 /**
1083  * nfs_delegation_find_inode - retrieve the inode associated with a delegation
1084  * @clp: client state handle
1085  * @fhandle: filehandle from a delegation recall
1086  *
1087  * Returns pointer to inode matching "fhandle," or NULL if a matching inode
1088  * cannot be found.
1089  */
1090 struct inode *nfs_delegation_find_inode(struct nfs_client *clp,
1091                                         const struct nfs_fh *fhandle)
1092 {
1093         struct nfs_server *server;
1094         struct inode *res;
1095
1096         rcu_read_lock();
1097         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link) {
1098                 res = nfs_delegation_find_inode_server(server, fhandle);
1099                 if (res != ERR_PTR(-ENOENT)) {
1100                         rcu_read_unlock();
1101                         return res;
1102                 }
1103         }
1104         rcu_read_unlock();
1105         return ERR_PTR(-ENOENT);
1106 }
1107
1108 static void nfs_delegation_mark_reclaim_server(struct nfs_server *server)
1109 {
1110         struct nfs_delegation *delegation;
1111
1112         list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
1113                 /*
1114                  * If the delegation may have been admin revoked, then we
1115                  * cannot reclaim it.
1116                  */
1117                 if (test_bit(NFS_DELEGATION_TEST_EXPIRED, &delegation->flags))
1118                         continue;
1119                 set_bit(NFS_DELEGATION_NEED_RECLAIM, &delegation->flags);
1120         }
1121 }
1122
1123 /**
1124  * nfs_delegation_mark_reclaim - mark all delegations as needing to be reclaimed
1125  * @clp: nfs_client to process
1126  *
1127  */
1128 void nfs_delegation_mark_reclaim(struct nfs_client *clp)
1129 {
1130         struct nfs_server *server;
1131
1132         rcu_read_lock();
1133         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
1134                 nfs_delegation_mark_reclaim_server(server);
1135         rcu_read_unlock();
1136 }
1137
1138 static int nfs_server_reap_unclaimed_delegations(struct nfs_server *server,
1139                 void __always_unused *data)
1140 {
1141         struct nfs_delegation *delegation;
1142         struct inode *inode;
1143 restart:
1144         rcu_read_lock();
1145 restart_locked:
1146         list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
1147                 if (test_bit(NFS_DELEGATION_INODE_FREEING,
1148                                         &delegation->flags) ||
1149                     test_bit(NFS_DELEGATION_RETURNING,
1150                                         &delegation->flags) ||
1151                     test_bit(NFS_DELEGATION_NEED_RECLAIM,
1152                                         &delegation->flags) == 0)
1153                         continue;
1154                 inode = nfs_delegation_grab_inode(delegation);
1155                 if (inode == NULL)
1156                         goto restart_locked;
1157                 delegation = nfs_start_delegation_return_locked(NFS_I(inode));
1158                 rcu_read_unlock();
1159                 if (delegation != NULL) {
1160                         if (nfs_detach_delegation(NFS_I(inode), delegation,
1161                                                 server) != NULL)
1162                                 nfs_free_delegation(delegation);
1163                         /* Match nfs_start_delegation_return_locked */
1164                         nfs_put_delegation(delegation);
1165                 }
1166                 iput(inode);
1167                 cond_resched();
1168                 goto restart;
1169         }
1170         rcu_read_unlock();
1171         return 0;
1172 }
1173
1174 /**
1175  * nfs_delegation_reap_unclaimed - reap unclaimed delegations after reboot recovery is done
1176  * @clp: nfs_client to process
1177  *
1178  */
1179 void nfs_delegation_reap_unclaimed(struct nfs_client *clp)
1180 {
1181         nfs_client_for_each_server(clp, nfs_server_reap_unclaimed_delegations,
1182                         NULL);
1183 }
1184
1185 static inline bool nfs4_server_rebooted(const struct nfs_client *clp)
1186 {
1187         return (clp->cl_state & (BIT(NFS4CLNT_CHECK_LEASE) |
1188                                 BIT(NFS4CLNT_LEASE_EXPIRED) |
1189                                 BIT(NFS4CLNT_SESSION_RESET))) != 0;
1190 }
1191
1192 static void nfs_mark_test_expired_delegation(struct nfs_server *server,
1193             struct nfs_delegation *delegation)
1194 {
1195         if (delegation->stateid.type == NFS4_INVALID_STATEID_TYPE)
1196                 return;
1197         clear_bit(NFS_DELEGATION_NEED_RECLAIM, &delegation->flags);
1198         set_bit(NFS_DELEGATION_TEST_EXPIRED, &delegation->flags);
1199         set_bit(NFS4CLNT_DELEGATION_EXPIRED, &server->nfs_client->cl_state);
1200 }
1201
1202 static void nfs_inode_mark_test_expired_delegation(struct nfs_server *server,
1203                 struct inode *inode)
1204 {
1205         struct nfs_delegation *delegation;
1206
1207         rcu_read_lock();
1208         delegation = rcu_dereference(NFS_I(inode)->delegation);
1209         if (delegation)
1210                 nfs_mark_test_expired_delegation(server, delegation);
1211         rcu_read_unlock();
1212
1213 }
1214
1215 static void nfs_delegation_mark_test_expired_server(struct nfs_server *server)
1216 {
1217         struct nfs_delegation *delegation;
1218
1219         list_for_each_entry_rcu(delegation, &server->delegations, super_list)
1220                 nfs_mark_test_expired_delegation(server, delegation);
1221 }
1222
1223 /**
1224  * nfs_mark_test_expired_all_delegations - mark all delegations for testing
1225  * @clp: nfs_client to process
1226  *
1227  * Iterates through all the delegations associated with this server and
1228  * marks them as needing to be checked for validity.
1229  */
1230 void nfs_mark_test_expired_all_delegations(struct nfs_client *clp)
1231 {
1232         struct nfs_server *server;
1233
1234         rcu_read_lock();
1235         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
1236                 nfs_delegation_mark_test_expired_server(server);
1237         rcu_read_unlock();
1238 }
1239
1240 /**
1241  * nfs_test_expired_all_delegations - test all delegations for a client
1242  * @clp: nfs_client to process
1243  *
1244  * Helper for handling "recallable state revoked" status from server.
1245  */
1246 void nfs_test_expired_all_delegations(struct nfs_client *clp)
1247 {
1248         nfs_mark_test_expired_all_delegations(clp);
1249         nfs4_schedule_state_manager(clp);
1250 }
1251
1252 static void
1253 nfs_delegation_test_free_expired(struct inode *inode,
1254                 nfs4_stateid *stateid,
1255                 const struct cred *cred)
1256 {
1257         struct nfs_server *server = NFS_SERVER(inode);
1258         const struct nfs4_minor_version_ops *ops = server->nfs_client->cl_mvops;
1259         int status;
1260
1261         if (!cred)
1262                 return;
1263         status = ops->test_and_free_expired(server, stateid, cred);
1264         if (status == -NFS4ERR_EXPIRED || status == -NFS4ERR_BAD_STATEID)
1265                 nfs_remove_bad_delegation(inode, stateid);
1266 }
1267
1268 static int nfs_server_reap_expired_delegations(struct nfs_server *server,
1269                 void __always_unused *data)
1270 {
1271         struct nfs_delegation *delegation;
1272         struct inode *inode;
1273         const struct cred *cred;
1274         nfs4_stateid stateid;
1275 restart:
1276         rcu_read_lock();
1277 restart_locked:
1278         list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
1279                 if (test_bit(NFS_DELEGATION_INODE_FREEING,
1280                                         &delegation->flags) ||
1281                     test_bit(NFS_DELEGATION_RETURNING,
1282                                         &delegation->flags) ||
1283                     test_bit(NFS_DELEGATION_TEST_EXPIRED,
1284                                         &delegation->flags) == 0)
1285                         continue;
1286                 inode = nfs_delegation_grab_inode(delegation);
1287                 if (inode == NULL)
1288                         goto restart_locked;
1289                 spin_lock(&delegation->lock);
1290                 cred = get_cred_rcu(delegation->cred);
1291                 nfs4_stateid_copy(&stateid, &delegation->stateid);
1292                 spin_unlock(&delegation->lock);
1293                 clear_bit(NFS_DELEGATION_TEST_EXPIRED, &delegation->flags);
1294                 rcu_read_unlock();
1295                 nfs_delegation_test_free_expired(inode, &stateid, cred);
1296                 put_cred(cred);
1297                 if (!nfs4_server_rebooted(server->nfs_client)) {
1298                         iput(inode);
1299                         cond_resched();
1300                         goto restart;
1301                 }
1302                 nfs_inode_mark_test_expired_delegation(server,inode);
1303                 iput(inode);
1304                 return -EAGAIN;
1305         }
1306         rcu_read_unlock();
1307         return 0;
1308 }
1309
1310 /**
1311  * nfs_reap_expired_delegations - reap expired delegations
1312  * @clp: nfs_client to process
1313  *
1314  * Iterates through all the delegations associated with this server and
1315  * checks if they have may have been revoked. This function is usually
1316  * expected to be called in cases where the server may have lost its
1317  * lease.
1318  */
1319 void nfs_reap_expired_delegations(struct nfs_client *clp)
1320 {
1321         nfs_client_for_each_server(clp, nfs_server_reap_expired_delegations,
1322                         NULL);
1323 }
1324
1325 void nfs_inode_find_delegation_state_and_recover(struct inode *inode,
1326                 const nfs4_stateid *stateid)
1327 {
1328         struct nfs_client *clp = NFS_SERVER(inode)->nfs_client;
1329         struct nfs_delegation *delegation;
1330         bool found = false;
1331
1332         rcu_read_lock();
1333         delegation = rcu_dereference(NFS_I(inode)->delegation);
1334         if (delegation &&
1335             nfs4_stateid_match_or_older(&delegation->stateid, stateid) &&
1336             !test_bit(NFS_DELEGATION_REVOKED, &delegation->flags)) {
1337                 nfs_mark_test_expired_delegation(NFS_SERVER(inode), delegation);
1338                 found = true;
1339         }
1340         rcu_read_unlock();
1341         if (found)
1342                 nfs4_schedule_state_manager(clp);
1343 }
1344
1345 /**
1346  * nfs_delegations_present - check for existence of delegations
1347  * @clp: client state handle
1348  *
1349  * Returns one if there are any nfs_delegation structures attached
1350  * to this nfs_client.
1351  */
1352 int nfs_delegations_present(struct nfs_client *clp)
1353 {
1354         struct nfs_server *server;
1355         int ret = 0;
1356
1357         rcu_read_lock();
1358         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
1359                 if (!list_empty(&server->delegations)) {
1360                         ret = 1;
1361                         break;
1362                 }
1363         rcu_read_unlock();
1364         return ret;
1365 }
1366
1367 /**
1368  * nfs4_refresh_delegation_stateid - Update delegation stateid seqid
1369  * @dst: stateid to refresh
1370  * @inode: inode to check
1371  *
1372  * Returns "true" and updates "dst->seqid" * if inode had a delegation
1373  * that matches our delegation stateid. Otherwise "false" is returned.
1374  */
1375 bool nfs4_refresh_delegation_stateid(nfs4_stateid *dst, struct inode *inode)
1376 {
1377         struct nfs_delegation *delegation;
1378         bool ret = false;
1379         if (!inode)
1380                 goto out;
1381
1382         rcu_read_lock();
1383         delegation = rcu_dereference(NFS_I(inode)->delegation);
1384         if (delegation != NULL &&
1385             nfs4_stateid_match_other(dst, &delegation->stateid) &&
1386             nfs4_stateid_is_newer(&delegation->stateid, dst) &&
1387             !test_bit(NFS_DELEGATION_REVOKED, &delegation->flags)) {
1388                 dst->seqid = delegation->stateid.seqid;
1389                 ret = true;
1390         }
1391         rcu_read_unlock();
1392 out:
1393         return ret;
1394 }
1395
1396 /**
1397  * nfs4_copy_delegation_stateid - Copy inode's state ID information
1398  * @inode: inode to check
1399  * @flags: delegation type requirement
1400  * @dst: stateid data structure to fill in
1401  * @cred: optional argument to retrieve credential
1402  *
1403  * Returns "true" and fills in "dst->data" * if inode had a delegation,
1404  * otherwise "false" is returned.
1405  */
1406 bool nfs4_copy_delegation_stateid(struct inode *inode, fmode_t flags,
1407                 nfs4_stateid *dst, const struct cred **cred)
1408 {
1409         struct nfs_inode *nfsi = NFS_I(inode);
1410         struct nfs_delegation *delegation;
1411         bool ret = false;
1412
1413         flags &= FMODE_READ|FMODE_WRITE;
1414         rcu_read_lock();
1415         delegation = rcu_dereference(nfsi->delegation);
1416         if (!delegation)
1417                 goto out;
1418         spin_lock(&delegation->lock);
1419         ret = nfs4_is_valid_delegation(delegation, flags);
1420         if (ret) {
1421                 nfs4_stateid_copy(dst, &delegation->stateid);
1422                 nfs_mark_delegation_referenced(delegation);
1423                 if (cred)
1424                         *cred = get_cred(delegation->cred);
1425         }
1426         spin_unlock(&delegation->lock);
1427 out:
1428         rcu_read_unlock();
1429         return ret;
1430 }
1431
1432 /**
1433  * nfs4_delegation_flush_on_close - Check if we must flush file on close
1434  * @inode: inode to check
1435  *
1436  * This function checks the number of outstanding writes to the file
1437  * against the delegation 'space_limit' field to see if
1438  * the spec requires us to flush the file on close.
1439  */
1440 bool nfs4_delegation_flush_on_close(const struct inode *inode)
1441 {
1442         struct nfs_inode *nfsi = NFS_I(inode);
1443         struct nfs_delegation *delegation;
1444         bool ret = true;
1445
1446         rcu_read_lock();
1447         delegation = rcu_dereference(nfsi->delegation);
1448         if (delegation == NULL || !(delegation->type & FMODE_WRITE))
1449                 goto out;
1450         if (atomic_long_read(&nfsi->nrequests) < delegation->pagemod_limit)
1451                 ret = false;
1452 out:
1453         rcu_read_unlock();
1454         return ret;
1455 }
1456
1457 module_param_named(delegation_watermark, nfs_delegation_watermark, uint, 0644);