fs/nfs/delegation.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * linux/fs/nfs/delegation.c
   4  *
   5  * Copyright (C) 2004 Trond Myklebust
   6  *
   7  * NFS file delegation management
   8  *
   9  */
  10 #include <linux/completion.h>
  11 #include <linux/kthread.h>
  12 #include <linux/module.h>
  13 #include <linux/sched.h>
  14 #include <linux/slab.h>
  15 #include <linux/spinlock.h>
  16 #include <linux/iversion.h>
  17
  18 #include <linux/nfs4.h>
  19 #include <linux/nfs_fs.h>
  20 #include <linux/nfs_xdr.h>
  21
  22 #include "nfs4_fs.h"
  23 #include "nfs4session.h"
  24 #include "delegation.h"
  25 #include "internal.h"
  26 #include "nfs4trace.h"
  27
  28 #define NFS_DEFAULT_DELEGATION_WATERMARK (5000U)
  29
  30 static atomic_long_t nfs_active_delegations;
  31 static unsigned nfs_delegation_watermark = NFS_DEFAULT_DELEGATION_WATERMARK;
  32
  33 static void __nfs_free_delegation(struct nfs_delegation *delegation)
  34 {
  35         put_cred(delegation->cred);
  36         delegation->cred = NULL;
  37         kfree_rcu(delegation, rcu);
  38 }
  39
  40 static void nfs_mark_delegation_revoked(struct nfs_delegation *delegation)
  41 {
  42         if (!test_and_set_bit(NFS_DELEGATION_REVOKED, &delegation->flags)) {
  43                 delegation->stateid.type = NFS4_INVALID_STATEID_TYPE;
  44                 atomic_long_dec(&nfs_active_delegations);
  45                 if (!test_bit(NFS_DELEGATION_RETURNING, &delegation->flags))
  46                         nfs_clear_verifier_delegated(delegation->inode);
  47         }
  48 }
  49
  50 static struct nfs_delegation *nfs_get_delegation(struct nfs_delegation *delegation)
  51 {
  52         refcount_inc(&delegation->refcount);
  53         return delegation;
  54 }
  55
  56 static void nfs_put_delegation(struct nfs_delegation *delegation)
  57 {
  58         if (refcount_dec_and_test(&delegation->refcount))
  59                 __nfs_free_delegation(delegation);
  60 }
  61
  62 static void nfs_free_delegation(struct nfs_delegation *delegation)
  63 {
  64         nfs_mark_delegation_revoked(delegation);
  65         nfs_put_delegation(delegation);
  66 }
  67
  68 /**
  69  * nfs_mark_delegation_referenced - set delegation's REFERENCED flag
  70  * @delegation: delegation to process
  71  *
  72  */
  73 void nfs_mark_delegation_referenced(struct nfs_delegation *delegation)
  74 {
  75         set_bit(NFS_DELEGATION_REFERENCED, &delegation->flags);
  76 }
  77
  78 static bool
  79 nfs4_is_valid_delegation(const struct nfs_delegation *delegation,
  80                 fmode_t flags)
  81 {
  82         if (delegation != NULL && (delegation->type & flags) == flags &&
  83             !test_bit(NFS_DELEGATION_REVOKED, &delegation->flags) &&
  84             !test_bit(NFS_DELEGATION_RETURNING, &delegation->flags))
  85                 return true;
  86         return false;
  87 }
  88
  89 struct nfs_delegation *nfs4_get_valid_delegation(const struct inode *inode)
  90 {
  91         struct nfs_delegation *delegation;
  92
  93         delegation = rcu_dereference(NFS_I(inode)->delegation);
  94         if (nfs4_is_valid_delegation(delegation, 0))
  95                 return delegation;
  96         return NULL;
  97 }
  98
  99 static int
 100 nfs4_do_check_delegation(struct inode *inode, fmode_t flags, bool mark)
 101 {
 102         struct nfs_delegation *delegation;
 103         int ret = 0;
 104
 105         flags &= FMODE_READ|FMODE_WRITE;
 106         rcu_read_lock();
 107         delegation = rcu_dereference(NFS_I(inode)->delegation);
 108         if (nfs4_is_valid_delegation(delegation, flags)) {
 109                 if (mark)
 110                         nfs_mark_delegation_referenced(delegation);
 111                 ret = 1;
 112         }
 113         rcu_read_unlock();
 114         return ret;
 115 }
 116 /**
 117  * nfs_have_delegation - check if inode has a delegation, mark it
 118  * NFS_DELEGATION_REFERENCED if there is one.
 119  * @inode: inode to check
 120  * @flags: delegation types to check for
 121  *
 122  * Returns one if inode has the indicated delegation, otherwise zero.
 123  */
 124 int nfs4_have_delegation(struct inode *inode, fmode_t flags)
 125 {
 126         return nfs4_do_check_delegation(inode, flags, true);
 127 }
 128
 129 /*
 130  * nfs4_check_delegation - check if inode has a delegation, do not mark
 131  * NFS_DELEGATION_REFERENCED if it has one.
 132  */
 133 int nfs4_check_delegation(struct inode *inode, fmode_t flags)
 134 {
 135         return nfs4_do_check_delegation(inode, flags, false);
 136 }
 137
 138 static int nfs_delegation_claim_locks(struct nfs4_state *state, const nfs4_stateid *stateid)
 139 {
 140         struct inode *inode = state->inode;
 141         struct file_lock *fl;
 142         struct file_lock_context *flctx = inode->i_flctx;
 143         struct list_head *list;
 144         int status = 0;
 145
 146         if (flctx == NULL)
 147                 goto out;
 148
 149         list = &flctx->flc_posix;
 150         spin_lock(&flctx->flc_lock);
 151 restart:
 152         list_for_each_entry(fl, list, fl_list) {
 153                 if (nfs_file_open_context(fl->fl_file)->state != state)
 154                         continue;
 155                 spin_unlock(&flctx->flc_lock);
 156                 status = nfs4_lock_delegation_recall(fl, state, stateid);
 157                 if (status < 0)
 158                         goto out;
 159                 spin_lock(&flctx->flc_lock);
 160         }
 161         if (list == &flctx->flc_posix) {
 162                 list = &flctx->flc_flock;
 163                 goto restart;
 164         }
 165         spin_unlock(&flctx->flc_lock);
 166 out:
 167         return status;
 168 }
 169
 170 static int nfs_delegation_claim_opens(struct inode *inode,
 171                 const nfs4_stateid *stateid, fmode_t type)
 172 {
 173         struct nfs_inode *nfsi = NFS_I(inode);
 174         struct nfs_open_context *ctx;
 175         struct nfs4_state_owner *sp;
 176         struct nfs4_state *state;
 177         unsigned int seq;
 178         int err;
 179
 180 again:
 181         rcu_read_lock();
 182         list_for_each_entry_rcu(ctx, &nfsi->open_files, list) {
 183                 state = ctx->state;
 184                 if (state == NULL)
 185                         continue;
 186                 if (!test_bit(NFS_DELEGATED_STATE, &state->flags))
 187                         continue;
 188                 if (!nfs4_valid_open_stateid(state))
 189                         continue;
 190                 if (!nfs4_stateid_match(&state->stateid, stateid))
 191                         continue;
 192                 if (!get_nfs_open_context(ctx))
 193                         continue;
 194                 rcu_read_unlock();
 195                 sp = state->owner;
 196                 /* Block nfs4_proc_unlck */
 197                 mutex_lock(&sp->so_delegreturn_mutex);
 198                 seq = raw_seqcount_begin(&sp->so_reclaim_seqcount);
 199                 err = nfs4_open_delegation_recall(ctx, state, stateid);
 200                 if (!err)
 201                         err = nfs_delegation_claim_locks(state, stateid);
 202                 if (!err && read_seqcount_retry(&sp->so_reclaim_seqcount, seq))
 203                         err = -EAGAIN;
 204                 mutex_unlock(&sp->so_delegreturn_mutex);
 205                 put_nfs_open_context(ctx);
 206                 if (err != 0)
 207                         return err;
 208                 goto again;
 209         }
 210         rcu_read_unlock();
 211         return 0;
 212 }
 213
 214 /**
 215  * nfs_inode_reclaim_delegation - process a delegation reclaim request
 216  * @inode: inode to process
 217  * @cred: credential to use for request
 218  * @type: delegation type
 219  * @stateid: delegation stateid
 220  * @pagemod_limit: write delegation "space_limit"
 221  *
 222  */
 223 void nfs_inode_reclaim_delegation(struct inode *inode, const struct cred *cred,
 224                                   fmode_t type,
 225                                   const nfs4_stateid *stateid,
 226                                   unsigned long pagemod_limit)
 227 {
 228         struct nfs_delegation *delegation;
 229         const struct cred *oldcred = NULL;
 230
 231         rcu_read_lock();
 232         delegation = rcu_dereference(NFS_I(inode)->delegation);
 233         if (delegation != NULL) {
 234                 spin_lock(&delegation->lock);
 235                 if (nfs4_is_valid_delegation(delegation, 0)) {
 236                         nfs4_stateid_copy(&delegation->stateid, stateid);
 237                         delegation->type = type;
 238                         delegation->pagemod_limit = pagemod_limit;
 239                         oldcred = delegation->cred;
 240                         delegation->cred = get_cred(cred);
 241                         clear_bit(NFS_DELEGATION_NEED_RECLAIM,
 242                                   &delegation->flags);
 243                         spin_unlock(&delegation->lock);
 244                         rcu_read_unlock();
 245                         put_cred(oldcred);
 246                         trace_nfs4_reclaim_delegation(inode, type);
 247                         return;
 248                 }
 249                 /* We appear to have raced with a delegation return. */
 250                 spin_unlock(&delegation->lock);
 251         }
 252         rcu_read_unlock();
 253         nfs_inode_set_delegation(inode, cred, type, stateid, pagemod_limit);
 254 }
 255
 256 static int nfs_do_return_delegation(struct inode *inode, struct nfs_delegation *delegation, int issync)
 257 {
 258         const struct cred *cred;
 259         int res = 0;
 260
 261         if (!test_bit(NFS_DELEGATION_REVOKED, &delegation->flags)) {
 262                 spin_lock(&delegation->lock);
 263                 cred = get_cred(delegation->cred);
 264                 spin_unlock(&delegation->lock);
 265                 res = nfs4_proc_delegreturn(inode, cred,
 266                                 &delegation->stateid,
 267                                 issync);
 268                 put_cred(cred);
 269         }
 270         return res;
 271 }
 272
 273 static struct inode *nfs_delegation_grab_inode(struct nfs_delegation *delegation)
 274 {
 275         struct inode *inode = NULL;
 276
 277         spin_lock(&delegation->lock);
 278         if (delegation->inode != NULL)
 279                 inode = igrab(delegation->inode);
 280         if (!inode)
 281                 set_bit(NFS_DELEGATION_INODE_FREEING, &delegation->flags);
 282         spin_unlock(&delegation->lock);
 283         return inode;
 284 }
 285
 286 static struct nfs_delegation *
 287 nfs_start_delegation_return_locked(struct nfs_inode *nfsi)
 288 {
 289         struct nfs_delegation *ret = NULL;
 290         struct nfs_delegation *delegation = rcu_dereference(nfsi->delegation);
 291
 292         if (delegation == NULL)
 293                 goto out;
 294         spin_lock(&delegation->lock);
 295         if (!test_and_set_bit(NFS_DELEGATION_RETURNING, &delegation->flags)) {
 296                 /* Refcount matched in nfs_end_delegation_return() */
 297                 ret = nfs_get_delegation(delegation);
 298         }
 299         spin_unlock(&delegation->lock);
 300         if (ret)
 301                 nfs_clear_verifier_delegated(&nfsi->vfs_inode);
 302 out:
 303         return ret;
 304 }
 305
 306 static struct nfs_delegation *
 307 nfs_start_delegation_return(struct nfs_inode *nfsi)
 308 {
 309         struct nfs_delegation *delegation;
 310
 311         rcu_read_lock();
 312         delegation = nfs_start_delegation_return_locked(nfsi);
 313         rcu_read_unlock();
 314         return delegation;
 315 }
 316
 317 static void
 318 nfs_abort_delegation_return(struct nfs_delegation *delegation,
 319                 struct nfs_client *clp)
 320 {
 321
 322         spin_lock(&delegation->lock);
 323         clear_bit(NFS_DELEGATION_RETURNING, &delegation->flags);
 324         set_bit(NFS_DELEGATION_RETURN, &delegation->flags);
 325         spin_unlock(&delegation->lock);
 326         set_bit(NFS4CLNT_DELEGRETURN, &clp->cl_state);
 327 }
 328
 329 static struct nfs_delegation *
 330 nfs_detach_delegation_locked(struct nfs_inode *nfsi,
 331                 struct nfs_delegation *delegation,
 332                 struct nfs_client *clp)
 333 {
 334         struct nfs_delegation *deleg_cur =
 335                 rcu_dereference_protected(nfsi->delegation,
 336                                 lockdep_is_held(&clp->cl_lock));
 337
 338         if (deleg_cur == NULL || delegation != deleg_cur)
 339                 return NULL;
 340
 341         spin_lock(&delegation->lock);
 342         if (!delegation->inode) {
 343                 spin_unlock(&delegation->lock);
 344                 return NULL;
 345         }
 346         list_del_rcu(&delegation->super_list);
 347         delegation->inode = NULL;
 348         rcu_assign_pointer(nfsi->delegation, NULL);
 349         spin_unlock(&delegation->lock);
 350         return delegation;
 351 }
 352
 353 static struct nfs_delegation *nfs_detach_delegation(struct nfs_inode *nfsi,
 354                 struct nfs_delegation *delegation,
 355                 struct nfs_server *server)
 356 {
 357         struct nfs_client *clp = server->nfs_client;
 358
 359         spin_lock(&clp->cl_lock);
 360         delegation = nfs_detach_delegation_locked(nfsi, delegation, clp);
 361         spin_unlock(&clp->cl_lock);
 362         return delegation;
 363 }
 364
 365 static struct nfs_delegation *
 366 nfs_inode_detach_delegation(struct inode *inode)
 367 {
 368         struct nfs_inode *nfsi = NFS_I(inode);
 369         struct nfs_server *server = NFS_SERVER(inode);
 370         struct nfs_delegation *delegation;
 371
 372         rcu_read_lock();
 373         delegation = rcu_dereference(nfsi->delegation);
 374         if (delegation != NULL)
 375                 delegation = nfs_detach_delegation(nfsi, delegation, server);
 376         rcu_read_unlock();
 377         return delegation;
 378 }
 379
 380 static void
 381 nfs_update_delegation_cred(struct nfs_delegation *delegation,
 382                 const struct cred *cred)
 383 {
 384         const struct cred *old;
 385
 386         if (cred_fscmp(delegation->cred, cred) != 0) {
 387                 old = xchg(&delegation->cred, get_cred(cred));
 388                 put_cred(old);
 389         }
 390 }
 391
 392 static void
 393 nfs_update_inplace_delegation(struct nfs_delegation *delegation,
 394                 const struct nfs_delegation *update)
 395 {
 396         if (nfs4_stateid_is_newer(&update->stateid, &delegation->stateid)) {
 397                 delegation->stateid.seqid = update->stateid.seqid;
 398                 smp_wmb();
 399                 delegation->type = update->type;
 400                 delegation->pagemod_limit = update->pagemod_limit;
 401                 if (test_bit(NFS_DELEGATION_REVOKED, &delegation->flags)) {
 402                         delegation->change_attr = update->change_attr;
 403                         nfs_update_delegation_cred(delegation, update->cred);
 404                         /* smp_mb__before_atomic() is implicit due to xchg() */
 405                         clear_bit(NFS_DELEGATION_REVOKED, &delegation->flags);
 406                         atomic_long_inc(&nfs_active_delegations);
 407                 }
 408         }
 409 }
 410
 411 /**
 412  * nfs_inode_set_delegation - set up a delegation on an inode
 413  * @inode: inode to which delegation applies
 414  * @cred: cred to use for subsequent delegation processing
 415  * @type: delegation type
 416  * @stateid: delegation stateid
 417  * @pagemod_limit: write delegation "space_limit"
 418  *
 419  * Returns zero on success, or a negative errno value.
 420  */
 421 int nfs_inode_set_delegation(struct inode *inode, const struct cred *cred,
 422                                   fmode_t type,
 423                                   const nfs4_stateid *stateid,
 424                                   unsigned long pagemod_limit)
 425 {
 426         struct nfs_server *server = NFS_SERVER(inode);
 427         struct nfs_client *clp = server->nfs_client;
 428         struct nfs_inode *nfsi = NFS_I(inode);
 429         struct nfs_delegation *delegation, *old_delegation;
 430         struct nfs_delegation *freeme = NULL;
 431         int status = 0;
 432
 433         delegation = kmalloc(sizeof(*delegation), GFP_NOFS);
 434         if (delegation == NULL)
 435                 return -ENOMEM;
 436         nfs4_stateid_copy(&delegation->stateid, stateid);
 437         refcount_set(&delegation->refcount, 1);
 438         delegation->type = type;
 439         delegation->pagemod_limit = pagemod_limit;
 440         delegation->change_attr = inode_peek_iversion_raw(inode);
 441         delegation->cred = get_cred(cred);
 442         delegation->inode = inode;
 443         delegation->flags = 1<<NFS_DELEGATION_REFERENCED;
 444         spin_lock_init(&delegation->lock);
 445
 446         spin_lock(&clp->cl_lock);
 447         old_delegation = rcu_dereference_protected(nfsi->delegation,
 448                                         lockdep_is_held(&clp->cl_lock));
 449         if (old_delegation == NULL)
 450                 goto add_new;
 451         /* Is this an update of the existing delegation? */
 452         if (nfs4_stateid_match_other(&old_delegation->stateid,
 453                                 &delegation->stateid)) {
 454                 spin_lock(&old_delegation->lock);
 455                 nfs_update_inplace_delegation(old_delegation,
 456                                 delegation);
 457                 spin_unlock(&old_delegation->lock);
 458                 goto out;
 459         }
 460         if (!test_bit(NFS_DELEGATION_REVOKED, &old_delegation->flags)) {
 461                 /*
 462                  * Deal with broken servers that hand out two
 463                  * delegations for the same file.
 464                  * Allow for upgrades to a WRITE delegation, but
 465                  * nothing else.
 466                  */
 467                 dfprintk(FILE, "%s: server %s handed out "
 468                                 "a duplicate delegation!\n",
 469                                 __func__, clp->cl_hostname);
 470                 if (delegation->type == old_delegation->type ||
 471                     !(delegation->type & FMODE_WRITE)) {
 472                         freeme = delegation;
 473                         delegation = NULL;
 474                         goto out;
 475                 }
 476                 if (test_and_set_bit(NFS_DELEGATION_RETURNING,
 477                                         &old_delegation->flags))
 478                         goto out;
 479         }
 480         freeme = nfs_detach_delegation_locked(nfsi, old_delegation, clp);
 481         if (freeme == NULL)
 482                 goto out;
 483 add_new:
 484         list_add_tail_rcu(&delegation->super_list, &server->delegations);
 485         rcu_assign_pointer(nfsi->delegation, delegation);
 486         delegation = NULL;
 487
 488         atomic_long_inc(&nfs_active_delegations);
 489
 490         trace_nfs4_set_delegation(inode, type);
 491
 492         spin_lock(&inode->i_lock);
 493         if (NFS_I(inode)->cache_validity & (NFS_INO_INVALID_ATTR|NFS_INO_INVALID_ATIME))
 494                 NFS_I(inode)->cache_validity |= NFS_INO_REVAL_FORCED;
 495         spin_unlock(&inode->i_lock);
 496 out:
 497         spin_unlock(&clp->cl_lock);
 498         if (delegation != NULL)
 499                 __nfs_free_delegation(delegation);
 500         if (freeme != NULL) {
 501                 nfs_do_return_delegation(inode, freeme, 0);
 502                 nfs_free_delegation(freeme);
 503         }
 504         return status;
 505 }
 506
 507 /*
 508  * Basic procedure for returning a delegation to the server
 509  */
 510 static int nfs_end_delegation_return(struct inode *inode, struct nfs_delegation *delegation, int issync)
 511 {
 512         struct nfs_client *clp = NFS_SERVER(inode)->nfs_client;
 513         int err = 0;
 514
 515         if (delegation == NULL)
 516                 return 0;
 517         do {
 518                 if (test_bit(NFS_DELEGATION_REVOKED, &delegation->flags))
 519                         break;
 520                 err = nfs_delegation_claim_opens(inode, &delegation->stateid,
 521                                 delegation->type);
 522                 if (!issync || err != -EAGAIN)
 523                         break;
 524                 /*
 525                  * Guard against state recovery
 526                  */
 527                 err = nfs4_wait_clnt_recover(clp);
 528         } while (err == 0);
 529
 530         if (err) {
 531                 nfs_abort_delegation_return(delegation, clp);
 532                 goto out;
 533         }
 534
 535         err = nfs_do_return_delegation(inode, delegation, issync);
 536 out:
 537         /* Refcount matched in nfs_start_delegation_return_locked() */
 538         nfs_put_delegation(delegation);
 539         return err;
 540 }
 541
 542 static bool nfs_delegation_need_return(struct nfs_delegation *delegation)
 543 {
 544         bool ret = false;
 545
 546         if (test_and_clear_bit(NFS_DELEGATION_RETURN, &delegation->flags))
 547                 ret = true;
 548         else if (test_bit(NFS_DELEGATION_RETURN_IF_CLOSED, &delegation->flags)) {
 549                 struct inode *inode;
 550
 551                 spin_lock(&delegation->lock);
 552                 inode = delegation->inode;
 553                 if (inode && list_empty(&NFS_I(inode)->open_files))
 554                         ret = true;
 555                 spin_unlock(&delegation->lock);
 556         }
 557         if (ret)
 558                 clear_bit(NFS_DELEGATION_RETURN_IF_CLOSED, &delegation->flags);
 559         if (test_bit(NFS_DELEGATION_RETURNING, &delegation->flags) ||
 560             test_bit(NFS_DELEGATION_REVOKED, &delegation->flags))
 561                 ret = false;
 562
 563         return ret;
 564 }
 565
 566 /**
 567  * nfs_client_return_marked_delegations - return previously marked delegations
 568  * @clp: nfs_client to process
 569  *
 570  * Note that this function is designed to be called by the state
 571  * manager thread. For this reason, it cannot flush the dirty data,
 572  * since that could deadlock in case of a state recovery error.
 573  *
 574  * Returns zero on success, or a negative errno value.
 575  */
 576 int nfs_client_return_marked_delegations(struct nfs_client *clp)
 577 {
 578         struct nfs_delegation *delegation;
 579         struct nfs_delegation *prev;
 580         struct nfs_server *server;
 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 nfs_servers from the server of that inode, and
 591          * delegation in the server from the delegations of that
 592          * inode.
 593          * prev is an RCU-protected pointer to a delegation which
 594          * wasn't marked for return and might be a good choice for
 595          * the next place_holder.
 596          */
 597         rcu_read_lock();
 598         prev = NULL;
 599         if (place_holder)
 600                 server = NFS_SERVER(place_holder);
 601         else
 602                 server = list_entry_rcu(clp->cl_superblocks.next,
 603                                         struct nfs_server, client_link);
 604         list_for_each_entry_from_rcu(server, &clp->cl_superblocks, client_link) {
 605                 delegation = NULL;
 606                 if (place_holder && server == NFS_SERVER(place_holder))
 607                         delegation = rcu_dereference(NFS_I(place_holder)->delegation);
 608                 if (!delegation || delegation != place_holder_deleg)
 609                         delegation = list_entry_rcu(server->delegations.next,
 610                                                     struct nfs_delegation, super_list);
 611                 list_for_each_entry_from_rcu(delegation, &server->delegations, super_list) {
 612                         struct inode *to_put = NULL;
 613
 614                         if (!nfs_delegation_need_return(delegation)) {
 615                                 prev = delegation;
 616                                 continue;
 617                         }
 618                         if (!nfs_sb_active(server->super))
 619                                 break; /* continue in outer loop */
 620
 621                         if (prev) {
 622                                 struct inode *tmp;
 623
 624                                 tmp = nfs_delegation_grab_inode(prev);
 625                                 if (tmp) {
 626                                         to_put = place_holder;
 627                                         place_holder = tmp;
 628                                         place_holder_deleg = prev;
 629                                 }
 630                         }
 631
 632                         inode = nfs_delegation_grab_inode(delegation);
 633                         if (inode == NULL) {
 634                                 rcu_read_unlock();
 635                                 if (to_put)
 636                                         iput(to_put);
 637                                 nfs_sb_deactive(server->super);
 638                                 goto restart;
 639                         }
 640                         delegation = nfs_start_delegation_return_locked(NFS_I(inode));
 641                         rcu_read_unlock();
 642
 643                         if (to_put)
 644                                 iput(to_put);
 645
 646                         err = nfs_end_delegation_return(inode, delegation, 0);
 647                         iput(inode);
 648                         nfs_sb_deactive(server->super);
 649                         cond_resched();
 650                         if (!err)
 651                                 goto restart;
 652                         set_bit(NFS4CLNT_DELEGRETURN, &clp->cl_state);
 653                         if (place_holder)
 654                                 iput(place_holder);
 655                         return err;
 656                 }
 657         }
 658         rcu_read_unlock();
 659         if (place_holder)
 660                 iput(place_holder);
 661         return 0;
 662 }
 663
 664 /**
 665  * nfs_inode_evict_delegation - return delegation, don't reclaim opens
 666  * @inode: inode to process
 667  *
 668  * Does not protect against delegation reclaims, therefore really only safe
 669  * to be called from nfs4_clear_inode(). Guaranteed to always free
 670  * the delegation structure.
 671  */
 672 void nfs_inode_evict_delegation(struct inode *inode)
 673 {
 674         struct nfs_delegation *delegation;
 675
 676         delegation = nfs_inode_detach_delegation(inode);
 677         if (delegation != NULL) {
 678                 set_bit(NFS_DELEGATION_RETURNING, &delegation->flags);
 679                 set_bit(NFS_DELEGATION_INODE_FREEING, &delegation->flags);
 680                 nfs_do_return_delegation(inode, delegation, 1);
 681                 nfs_free_delegation(delegation);
 682         }
 683 }
 684
 685 /**
 686  * nfs_inode_return_delegation - synchronously return a delegation
 687  * @inode: inode to process
 688  *
 689  * This routine will always flush any dirty data to disk on the
 690  * assumption that if we need to return the delegation, then
 691  * we should stop caching.
 692  *
 693  * Returns zero on success, or a negative errno value.
 694  */
 695 int nfs4_inode_return_delegation(struct inode *inode)
 696 {
 697         struct nfs_inode *nfsi = NFS_I(inode);
 698         struct nfs_delegation *delegation;
 699         int err = 0;
 700
 701         nfs_wb_all(inode);
 702         delegation = nfs_start_delegation_return(nfsi);
 703         if (delegation != NULL)
 704                 err = nfs_end_delegation_return(inode, delegation, 1);
 705         return err;
 706 }
 707
 708 /**
 709  * nfs_inode_return_delegation_on_close - asynchronously return a delegation
 710  * @inode: inode to process
 711  *
 712  * This routine is called on file close in order to determine if the
 713  * inode delegation needs to be returned immediately.
 714  */
 715 void nfs4_inode_return_delegation_on_close(struct inode *inode)
 716 {
 717         struct nfs_delegation *delegation;
 718         struct nfs_delegation *ret = NULL;
 719
 720         if (!inode)
 721                 return;
 722         rcu_read_lock();
 723         delegation = nfs4_get_valid_delegation(inode);
 724         if (!delegation)
 725                 goto out;
 726         if (test_bit(NFS_DELEGATION_RETURN_IF_CLOSED, &delegation->flags) ||
 727             atomic_long_read(&nfs_active_delegations) >= nfs_delegation_watermark) {
 728                 spin_lock(&delegation->lock);
 729                 if (delegation->inode &&
 730                     list_empty(&NFS_I(inode)->open_files) &&
 731                     !test_and_set_bit(NFS_DELEGATION_RETURNING, &delegation->flags)) {
 732                         clear_bit(NFS_DELEGATION_RETURN_IF_CLOSED, &delegation->flags);
 733                         /* Refcount matched in nfs_end_delegation_return() */
 734                         ret = nfs_get_delegation(delegation);
 735                 }
 736                 spin_unlock(&delegation->lock);
 737                 if (ret)
 738                         nfs_clear_verifier_delegated(inode);
 739         }
 740 out:
 741         rcu_read_unlock();
 742         nfs_end_delegation_return(inode, ret, 0);
 743 }
 744
 745 /**
 746  * nfs4_inode_make_writeable
 747  * @inode: pointer to inode
 748  *
 749  * Make the inode writeable by returning the delegation if necessary
 750  *
 751  * Returns zero on success, or a negative errno value.
 752  */
 753 int nfs4_inode_make_writeable(struct inode *inode)
 754 {
 755         struct nfs_delegation *delegation;
 756
 757         rcu_read_lock();
 758         delegation = nfs4_get_valid_delegation(inode);
 759         if (delegation == NULL ||
 760             (nfs4_has_session(NFS_SERVER(inode)->nfs_client) &&
 761              (delegation->type & FMODE_WRITE))) {
 762                 rcu_read_unlock();
 763                 return 0;
 764         }
 765         rcu_read_unlock();
 766         return nfs4_inode_return_delegation(inode);
 767 }
 768
 769 static void nfs_mark_return_if_closed_delegation(struct nfs_server *server,
 770                 struct nfs_delegation *delegation)
 771 {
 772         set_bit(NFS_DELEGATION_RETURN_IF_CLOSED, &delegation->flags);
 773         set_bit(NFS4CLNT_DELEGRETURN, &server->nfs_client->cl_state);
 774 }
 775
 776 static void nfs_mark_return_delegation(struct nfs_server *server,
 777                 struct nfs_delegation *delegation)
 778 {
 779         set_bit(NFS_DELEGATION_RETURN, &delegation->flags);
 780         set_bit(NFS4CLNT_DELEGRETURN, &server->nfs_client->cl_state);
 781 }
 782
 783 static bool nfs_server_mark_return_all_delegations(struct nfs_server *server)
 784 {
 785         struct nfs_delegation *delegation;
 786         bool ret = false;
 787
 788         list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
 789                 nfs_mark_return_delegation(server, delegation);
 790                 ret = true;
 791         }
 792         return ret;
 793 }
 794
 795 static void nfs_client_mark_return_all_delegations(struct nfs_client *clp)
 796 {
 797         struct nfs_server *server;
 798
 799         rcu_read_lock();
 800         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
 801                 nfs_server_mark_return_all_delegations(server);
 802         rcu_read_unlock();
 803 }
 804
 805 static void nfs_delegation_run_state_manager(struct nfs_client *clp)
 806 {
 807         if (test_bit(NFS4CLNT_DELEGRETURN, &clp->cl_state))
 808                 nfs4_schedule_state_manager(clp);
 809 }
 810
 811 /**
 812  * nfs_expire_all_delegations
 813  * @clp: client to process
 814  *
 815  */
 816 void nfs_expire_all_delegations(struct nfs_client *clp)
 817 {
 818         nfs_client_mark_return_all_delegations(clp);
 819         nfs_delegation_run_state_manager(clp);
 820 }
 821
 822 /**
 823  * nfs_super_return_all_delegations - return delegations for one superblock
 824  * @server: pointer to nfs_server to process
 825  *
 826  */
 827 void nfs_server_return_all_delegations(struct nfs_server *server)
 828 {
 829         struct nfs_client *clp = server->nfs_client;
 830         bool need_wait;
 831
 832         if (clp == NULL)
 833                 return;
 834
 835         rcu_read_lock();
 836         need_wait = nfs_server_mark_return_all_delegations(server);
 837         rcu_read_unlock();
 838
 839         if (need_wait) {
 840                 nfs4_schedule_state_manager(clp);
 841                 nfs4_wait_clnt_recover(clp);
 842         }
 843 }
 844
 845 static void nfs_mark_return_unused_delegation_types(struct nfs_server *server,
 846                                                  fmode_t flags)
 847 {
 848         struct nfs_delegation *delegation;
 849
 850         list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
 851                 if ((delegation->type == (FMODE_READ|FMODE_WRITE)) && !(flags & FMODE_WRITE))
 852                         continue;
 853                 if (delegation->type & flags)
 854                         nfs_mark_return_if_closed_delegation(server, delegation);
 855         }
 856 }
 857
 858 static void nfs_client_mark_return_unused_delegation_types(struct nfs_client *clp,
 859                                                         fmode_t flags)
 860 {
 861         struct nfs_server *server;
 862
 863         rcu_read_lock();
 864         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
 865                 nfs_mark_return_unused_delegation_types(server, flags);
 866         rcu_read_unlock();
 867 }
 868
 869 static void nfs_revoke_delegation(struct inode *inode,
 870                 const nfs4_stateid *stateid)
 871 {
 872         struct nfs_delegation *delegation;
 873         nfs4_stateid tmp;
 874         bool ret = false;
 875
 876         rcu_read_lock();
 877         delegation = rcu_dereference(NFS_I(inode)->delegation);
 878         if (delegation == NULL)
 879                 goto out;
 880         if (stateid == NULL) {
 881                 nfs4_stateid_copy(&tmp, &delegation->stateid);
 882                 stateid = &tmp;
 883         } else {
 884                 if (!nfs4_stateid_match_other(stateid, &delegation->stateid))
 885                         goto out;
 886                 spin_lock(&delegation->lock);
 887                 if (stateid->seqid) {
 888                         if (nfs4_stateid_is_newer(&delegation->stateid, stateid)) {
 889                                 spin_unlock(&delegation->lock);
 890                                 goto out;
 891                         }
 892                         delegation->stateid.seqid = stateid->seqid;
 893                 }
 894                 spin_unlock(&delegation->lock);
 895         }
 896         nfs_mark_delegation_revoked(delegation);
 897         ret = true;
 898 out:
 899         rcu_read_unlock();
 900         if (ret)
 901                 nfs_inode_find_state_and_recover(inode, stateid);
 902 }
 903
 904 void nfs_remove_bad_delegation(struct inode *inode,
 905                 const nfs4_stateid *stateid)
 906 {
 907         nfs_revoke_delegation(inode, stateid);
 908 }
 909 EXPORT_SYMBOL_GPL(nfs_remove_bad_delegation);
 910
 911 void nfs_delegation_mark_returned(struct inode *inode,
 912                 const nfs4_stateid *stateid)
 913 {
 914         struct nfs_delegation *delegation;
 915
 916         if (!inode)
 917                 return;
 918
 919         rcu_read_lock();
 920         delegation = rcu_dereference(NFS_I(inode)->delegation);
 921         if (!delegation)
 922                 goto out_rcu_unlock;
 923
 924         spin_lock(&delegation->lock);
 925         if (!nfs4_stateid_match_other(stateid, &delegation->stateid))
 926                 goto out_spin_unlock;
 927         if (stateid->seqid) {
 928                 /* If delegation->stateid is newer, dont mark as returned */
 929                 if (nfs4_stateid_is_newer(&delegation->stateid, stateid))
 930                         goto out_clear_returning;
 931                 if (delegation->stateid.seqid != stateid->seqid)
 932                         delegation->stateid.seqid = stateid->seqid;
 933         }
 934
 935         nfs_mark_delegation_revoked(delegation);
 936
 937 out_clear_returning:
 938         clear_bit(NFS_DELEGATION_RETURNING, &delegation->flags);
 939 out_spin_unlock:
 940         spin_unlock(&delegation->lock);
 941 out_rcu_unlock:
 942         rcu_read_unlock();
 943
 944         nfs_inode_find_state_and_recover(inode, stateid);
 945 }
 946
 947 /**
 948  * nfs_expire_unused_delegation_types
 949  * @clp: client to process
 950  * @flags: delegation types to expire
 951  *
 952  */
 953 void nfs_expire_unused_delegation_types(struct nfs_client *clp, fmode_t flags)
 954 {
 955         nfs_client_mark_return_unused_delegation_types(clp, flags);
 956         nfs_delegation_run_state_manager(clp);
 957 }
 958
 959 static void nfs_mark_return_unreferenced_delegations(struct nfs_server *server)
 960 {
 961         struct nfs_delegation *delegation;
 962
 963         list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
 964                 if (test_and_clear_bit(NFS_DELEGATION_REFERENCED, &delegation->flags))
 965                         continue;
 966                 nfs_mark_return_if_closed_delegation(server, delegation);
 967         }
 968 }
 969
 970 /**
 971  * nfs_expire_unreferenced_delegations - Eliminate unused delegations
 972  * @clp: nfs_client to process
 973  *
 974  */
 975 void nfs_expire_unreferenced_delegations(struct nfs_client *clp)
 976 {
 977         struct nfs_server *server;
 978
 979         rcu_read_lock();
 980         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
 981                 nfs_mark_return_unreferenced_delegations(server);
 982         rcu_read_unlock();
 983
 984         nfs_delegation_run_state_manager(clp);
 985 }
 986
 987 /**
 988  * nfs_async_inode_return_delegation - asynchronously return a delegation
 989  * @inode: inode to process
 990  * @stateid: state ID information
 991  *
 992  * Returns zero on success, or a negative errno value.
 993  */
 994 int nfs_async_inode_return_delegation(struct inode *inode,
 995                                       const nfs4_stateid *stateid)
 996 {
 997         struct nfs_server *server = NFS_SERVER(inode);
 998         struct nfs_client *clp = server->nfs_client;
 999         struct nfs_delegation *delegation;
1000
1001         rcu_read_lock();
1002         delegation = nfs4_get_valid_delegation(inode);
1003         if (delegation == NULL)
1004                 goto out_enoent;
1005         if (stateid != NULL &&
1006             !clp->cl_mvops->match_stateid(&delegation->stateid, stateid))
1007                 goto out_enoent;
1008         nfs_mark_return_delegation(server, delegation);
1009         rcu_read_unlock();
1010
1011         nfs_delegation_run_state_manager(clp);
1012         return 0;
1013 out_enoent:
1014         rcu_read_unlock();
1015         return -ENOENT;
1016 }
1017
1018 static struct inode *
1019 nfs_delegation_find_inode_server(struct nfs_server *server,
1020                                  const struct nfs_fh *fhandle)
1021 {
1022         struct nfs_delegation *delegation;
1023         struct inode *freeme, *res = NULL;
1024
1025         list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
1026                 spin_lock(&delegation->lock);
1027                 if (delegation->inode != NULL &&
1028                     !test_bit(NFS_DELEGATION_REVOKED, &delegation->flags) &&
1029                     nfs_compare_fh(fhandle, &NFS_I(delegation->inode)->fh) == 0) {
1030                         freeme = igrab(delegation->inode);
1031                         if (freeme && nfs_sb_active(freeme->i_sb))
1032                                 res = freeme;
1033                         spin_unlock(&delegation->lock);
1034                         if (res != NULL)
1035                                 return res;
1036                         if (freeme) {
1037                                 rcu_read_unlock();
1038                                 iput(freeme);
1039                                 rcu_read_lock();
1040                         }
1041                         return ERR_PTR(-EAGAIN);
1042                 }
1043                 spin_unlock(&delegation->lock);
1044         }
1045         return ERR_PTR(-ENOENT);
1046 }
1047
1048 /**
1049  * nfs_delegation_find_inode - retrieve the inode associated with a delegation
1050  * @clp: client state handle
1051  * @fhandle: filehandle from a delegation recall
1052  *
1053  * Returns pointer to inode matching "fhandle," or NULL if a matching inode
1054  * cannot be found.
1055  */
1056 struct inode *nfs_delegation_find_inode(struct nfs_client *clp,
1057                                         const struct nfs_fh *fhandle)
1058 {
1059         struct nfs_server *server;
1060         struct inode *res;
1061
1062         rcu_read_lock();
1063         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link) {
1064                 res = nfs_delegation_find_inode_server(server, fhandle);
1065                 if (res != ERR_PTR(-ENOENT)) {
1066                         rcu_read_unlock();
1067                         return res;
1068                 }
1069         }
1070         rcu_read_unlock();
1071         return ERR_PTR(-ENOENT);
1072 }
1073
1074 static void nfs_delegation_mark_reclaim_server(struct nfs_server *server)
1075 {
1076         struct nfs_delegation *delegation;
1077
1078         list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
1079                 /*
1080                  * If the delegation may have been admin revoked, then we
1081                  * cannot reclaim it.
1082                  */
1083                 if (test_bit(NFS_DELEGATION_TEST_EXPIRED, &delegation->flags))
1084                         continue;
1085                 set_bit(NFS_DELEGATION_NEED_RECLAIM, &delegation->flags);
1086         }
1087 }
1088
1089 /**
1090  * nfs_delegation_mark_reclaim - mark all delegations as needing to be reclaimed
1091  * @clp: nfs_client to process
1092  *
1093  */
1094 void nfs_delegation_mark_reclaim(struct nfs_client *clp)
1095 {
1096         struct nfs_server *server;
1097
1098         rcu_read_lock();
1099         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
1100                 nfs_delegation_mark_reclaim_server(server);
1101         rcu_read_unlock();
1102 }
1103
1104 /**
1105  * nfs_delegation_reap_unclaimed - reap unclaimed delegations after reboot recovery is done
1106  * @clp: nfs_client to process
1107  *
1108  */
1109 void nfs_delegation_reap_unclaimed(struct nfs_client *clp)
1110 {
1111         struct nfs_delegation *delegation;
1112         struct nfs_server *server;
1113         struct inode *inode;
1114
1115 restart:
1116         rcu_read_lock();
1117         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link) {
1118                 list_for_each_entry_rcu(delegation, &server->delegations,
1119                                                                 super_list) {
1120                         if (test_bit(NFS_DELEGATION_INODE_FREEING,
1121                                                 &delegation->flags) ||
1122                             test_bit(NFS_DELEGATION_RETURNING,
1123                                                 &delegation->flags) ||
1124                             test_bit(NFS_DELEGATION_NEED_RECLAIM,
1125                                                 &delegation->flags) == 0)
1126                                 continue;
1127                         if (!nfs_sb_active(server->super))
1128                                 break; /* continue in outer loop */
1129                         inode = nfs_delegation_grab_inode(delegation);
1130                         if (inode == NULL) {
1131                                 rcu_read_unlock();
1132                                 nfs_sb_deactive(server->super);
1133                                 goto restart;
1134                         }
1135                         delegation = nfs_start_delegation_return_locked(NFS_I(inode));
1136                         rcu_read_unlock();
1137                         if (delegation != NULL) {
1138                                 if (nfs_detach_delegation(NFS_I(inode), delegation,
1139                                                         server) != NULL)
1140                                         nfs_free_delegation(delegation);
1141                                 /* Match nfs_start_delegation_return_locked */
1142                                 nfs_put_delegation(delegation);
1143                         }
1144                         iput(inode);
1145                         nfs_sb_deactive(server->super);
1146                         cond_resched();
1147                         goto restart;
1148                 }
1149         }
1150         rcu_read_unlock();
1151 }
1152
1153 static inline bool nfs4_server_rebooted(const struct nfs_client *clp)
1154 {
1155         return (clp->cl_state & (BIT(NFS4CLNT_CHECK_LEASE) |
1156                                 BIT(NFS4CLNT_LEASE_EXPIRED) |
1157                                 BIT(NFS4CLNT_SESSION_RESET))) != 0;
1158 }
1159
1160 static void nfs_mark_test_expired_delegation(struct nfs_server *server,
1161             struct nfs_delegation *delegation)
1162 {
1163         if (delegation->stateid.type == NFS4_INVALID_STATEID_TYPE)
1164                 return;
1165         clear_bit(NFS_DELEGATION_NEED_RECLAIM, &delegation->flags);
1166         set_bit(NFS_DELEGATION_TEST_EXPIRED, &delegation->flags);
1167         set_bit(NFS4CLNT_DELEGATION_EXPIRED, &server->nfs_client->cl_state);
1168 }
1169
1170 static void nfs_inode_mark_test_expired_delegation(struct nfs_server *server,
1171                 struct inode *inode)
1172 {
1173         struct nfs_delegation *delegation;
1174
1175         rcu_read_lock();
1176         delegation = rcu_dereference(NFS_I(inode)->delegation);
1177         if (delegation)
1178                 nfs_mark_test_expired_delegation(server, delegation);
1179         rcu_read_unlock();
1180
1181 }
1182
1183 static void nfs_delegation_mark_test_expired_server(struct nfs_server *server)
1184 {
1185         struct nfs_delegation *delegation;
1186
1187         list_for_each_entry_rcu(delegation, &server->delegations, super_list)
1188                 nfs_mark_test_expired_delegation(server, delegation);
1189 }
1190
1191 /**
1192  * nfs_mark_test_expired_all_delegations - mark all delegations for testing
1193  * @clp: nfs_client to process
1194  *
1195  * Iterates through all the delegations associated with this server and
1196  * marks them as needing to be checked for validity.
1197  */
1198 void nfs_mark_test_expired_all_delegations(struct nfs_client *clp)
1199 {
1200         struct nfs_server *server;
1201
1202         rcu_read_lock();
1203         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
1204                 nfs_delegation_mark_test_expired_server(server);
1205         rcu_read_unlock();
1206 }
1207
1208 /**
1209  * nfs_test_expired_all_delegations - test all delegations for a client
1210  * @clp: nfs_client to process
1211  *
1212  * Helper for handling "recallable state revoked" status from server.
1213  */
1214 void nfs_test_expired_all_delegations(struct nfs_client *clp)
1215 {
1216         nfs_mark_test_expired_all_delegations(clp);
1217         nfs4_schedule_state_manager(clp);
1218 }
1219
1220 static void
1221 nfs_delegation_test_free_expired(struct inode *inode,
1222                 nfs4_stateid *stateid,
1223                 const struct cred *cred)
1224 {
1225         struct nfs_server *server = NFS_SERVER(inode);
1226         const struct nfs4_minor_version_ops *ops = server->nfs_client->cl_mvops;
1227         int status;
1228
1229         if (!cred)
1230                 return;
1231         status = ops->test_and_free_expired(server, stateid, cred);
1232         if (status == -NFS4ERR_EXPIRED || status == -NFS4ERR_BAD_STATEID)
1233                 nfs_remove_bad_delegation(inode, stateid);
1234 }
1235
1236 /**
1237  * nfs_reap_expired_delegations - reap expired delegations
1238  * @clp: nfs_client to process
1239  *
1240  * Iterates through all the delegations associated with this server and
1241  * checks if they have may have been revoked. This function is usually
1242  * expected to be called in cases where the server may have lost its
1243  * lease.
1244  */
1245 void nfs_reap_expired_delegations(struct nfs_client *clp)
1246 {
1247         struct nfs_delegation *delegation;
1248         struct nfs_server *server;
1249         struct inode *inode;
1250         const struct cred *cred;
1251         nfs4_stateid stateid;
1252
1253 restart:
1254         rcu_read_lock();
1255         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link) {
1256                 list_for_each_entry_rcu(delegation, &server->delegations,
1257                                                                 super_list) {
1258                         if (test_bit(NFS_DELEGATION_INODE_FREEING,
1259                                                 &delegation->flags) ||
1260                             test_bit(NFS_DELEGATION_RETURNING,
1261                                                 &delegation->flags) ||
1262                             test_bit(NFS_DELEGATION_TEST_EXPIRED,
1263                                                 &delegation->flags) == 0)
1264                                 continue;
1265                         if (!nfs_sb_active(server->super))
1266                                 break; /* continue in outer loop */
1267                         inode = nfs_delegation_grab_inode(delegation);
1268                         if (inode == NULL) {
1269                                 rcu_read_unlock();
1270                                 nfs_sb_deactive(server->super);
1271                                 goto restart;
1272                         }
1273                         cred = get_cred_rcu(delegation->cred);
1274                         nfs4_stateid_copy(&stateid, &delegation->stateid);
1275                         clear_bit(NFS_DELEGATION_TEST_EXPIRED, &delegation->flags);
1276                         rcu_read_unlock();
1277                         nfs_delegation_test_free_expired(inode, &stateid, cred);
1278                         put_cred(cred);
1279                         if (nfs4_server_rebooted(clp)) {
1280                                 nfs_inode_mark_test_expired_delegation(server,inode);
1281                                 iput(inode);
1282                                 nfs_sb_deactive(server->super);
1283                                 return;
1284                         }
1285                         iput(inode);
1286                         nfs_sb_deactive(server->super);
1287                         cond_resched();
1288                         goto restart;
1289                 }
1290         }
1291         rcu_read_unlock();
1292 }
1293
1294 void nfs_inode_find_delegation_state_and_recover(struct inode *inode,
1295                 const nfs4_stateid *stateid)
1296 {
1297         struct nfs_client *clp = NFS_SERVER(inode)->nfs_client;
1298         struct nfs_delegation *delegation;
1299         bool found = false;
1300
1301         rcu_read_lock();
1302         delegation = rcu_dereference(NFS_I(inode)->delegation);
1303         if (delegation &&
1304             nfs4_stateid_match_or_older(&delegation->stateid, stateid) &&
1305             !test_bit(NFS_DELEGATION_REVOKED, &delegation->flags)) {
1306                 nfs_mark_test_expired_delegation(NFS_SERVER(inode), delegation);
1307                 found = true;
1308         }
1309         rcu_read_unlock();
1310         if (found)
1311                 nfs4_schedule_state_manager(clp);
1312 }
1313
1314 /**
1315  * nfs_delegations_present - check for existence of delegations
1316  * @clp: client state handle
1317  *
1318  * Returns one if there are any nfs_delegation structures attached
1319  * to this nfs_client.
1320  */
1321 int nfs_delegations_present(struct nfs_client *clp)
1322 {
1323         struct nfs_server *server;
1324         int ret = 0;
1325
1326         rcu_read_lock();
1327         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
1328                 if (!list_empty(&server->delegations)) {
1329                         ret = 1;
1330                         break;
1331                 }
1332         rcu_read_unlock();
1333         return ret;
1334 }
1335
1336 /**
1337  * nfs4_refresh_delegation_stateid - Update delegation stateid seqid
1338  * @dst: stateid to refresh
1339  * @inode: inode to check
1340  *
1341  * Returns "true" and updates "dst->seqid" * if inode had a delegation
1342  * that matches our delegation stateid. Otherwise "false" is returned.
1343  */
1344 bool nfs4_refresh_delegation_stateid(nfs4_stateid *dst, struct inode *inode)
1345 {
1346         struct nfs_delegation *delegation;
1347         bool ret = false;
1348         if (!inode)
1349                 goto out;
1350
1351         rcu_read_lock();
1352         delegation = rcu_dereference(NFS_I(inode)->delegation);
1353         if (delegation != NULL &&
1354             nfs4_stateid_match_other(dst, &delegation->stateid) &&
1355             nfs4_stateid_is_newer(&delegation->stateid, dst) &&
1356             !test_bit(NFS_DELEGATION_REVOKED, &delegation->flags)) {
1357                 dst->seqid = delegation->stateid.seqid;
1358                 ret = true;
1359         }
1360         rcu_read_unlock();
1361 out:
1362         return ret;
1363 }
1364
1365 /**
1366  * nfs4_copy_delegation_stateid - Copy inode's state ID information
1367  * @inode: inode to check
1368  * @flags: delegation type requirement
1369  * @dst: stateid data structure to fill in
1370  * @cred: optional argument to retrieve credential
1371  *
1372  * Returns "true" and fills in "dst->data" * if inode had a delegation,
1373  * otherwise "false" is returned.
1374  */
1375 bool nfs4_copy_delegation_stateid(struct inode *inode, fmode_t flags,
1376                 nfs4_stateid *dst, const struct cred **cred)
1377 {
1378         struct nfs_inode *nfsi = NFS_I(inode);
1379         struct nfs_delegation *delegation;
1380         bool ret;
1381
1382         flags &= FMODE_READ|FMODE_WRITE;
1383         rcu_read_lock();
1384         delegation = rcu_dereference(nfsi->delegation);
1385         ret = nfs4_is_valid_delegation(delegation, flags);
1386         if (ret) {
1387                 nfs4_stateid_copy(dst, &delegation->stateid);
1388                 nfs_mark_delegation_referenced(delegation);
1389                 if (cred)
1390                         *cred = get_cred(delegation->cred);
1391         }
1392         rcu_read_unlock();
1393         return ret;
1394 }
1395
1396 /**
1397  * nfs4_delegation_flush_on_close - Check if we must flush file on close
1398  * @inode: inode to check
1399  *
1400  * This function checks the number of outstanding writes to the file
1401  * against the delegation 'space_limit' field to see if
1402  * the spec requires us to flush the file on close.
1403  */
1404 bool nfs4_delegation_flush_on_close(const struct inode *inode)
1405 {
1406         struct nfs_inode *nfsi = NFS_I(inode);
1407         struct nfs_delegation *delegation;
1408         bool ret = true;
1409
1410         rcu_read_lock();
1411         delegation = rcu_dereference(nfsi->delegation);
1412         if (delegation == NULL || !(delegation->type & FMODE_WRITE))
1413                 goto out;
1414         if (atomic_long_read(&nfsi->nrequests) < delegation->pagemod_limit)
1415                 ret = false;
1416 out:
1417         rcu_read_unlock();
1418         return ret;
1419 }
1420
1421 module_param_named(delegation_watermark, nfs_delegation_watermark, uint, 0644);