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