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 static int nfs_server_return_marked_delegations(struct nfs_server *server,
 567                 void __always_unused *data)
 568 {
 569         struct nfs_delegation *delegation;
 570         struct nfs_delegation *prev;
 571         struct inode *inode;
 572         struct inode *place_holder = NULL;
 573         struct nfs_delegation *place_holder_deleg = NULL;
 574         int err = 0;
 575
 576 restart:
 577         /*
 578          * To avoid quadratic looping we hold a reference
 579          * to an inode place_holder.  Each time we restart, we
 580          * list delegation in the server from the delegations
 581          * of that inode.
 582          * prev is an RCU-protected pointer to a delegation which
 583          * wasn't marked for return and might be a good choice for
 584          * the next place_holder.
 585          */
 586         prev = NULL;
 587         delegation = NULL;
 588         rcu_read_lock();
 589         if (place_holder)
 590                 delegation = rcu_dereference(NFS_I(place_holder)->delegation);
 591         if (!delegation || delegation != place_holder_deleg)
 592                 delegation = list_entry_rcu(server->delegations.next,
 593                                             struct nfs_delegation, super_list);
 594         list_for_each_entry_from_rcu(delegation, &server->delegations, super_list) {
 595                 struct inode *to_put = NULL;
 596
 597                 if (test_bit(NFS_DELEGATION_INODE_FREEING, &delegation->flags))
 598                         continue;
 599                 if (!nfs_delegation_need_return(delegation)) {
 600                         if (nfs4_is_valid_delegation(delegation, 0))
 601                                 prev = delegation;
 602                         continue;
 603                 }
 604
 605                 if (prev) {
 606                         struct inode *tmp = nfs_delegation_grab_inode(prev);
 607                         if (tmp) {
 608                                 to_put = place_holder;
 609                                 place_holder = tmp;
 610                                 place_holder_deleg = prev;
 611                         }
 612                 }
 613
 614                 inode = nfs_delegation_grab_inode(delegation);
 615                 if (inode == NULL) {
 616                         rcu_read_unlock();
 617                         iput(to_put);
 618                         goto restart;
 619                 }
 620                 delegation = nfs_start_delegation_return_locked(NFS_I(inode));
 621                 rcu_read_unlock();
 622
 623                 iput(to_put);
 624
 625                 err = nfs_end_delegation_return(inode, delegation, 0);
 626                 iput(inode);
 627                 cond_resched();
 628                 if (!err)
 629                         goto restart;
 630                 set_bit(NFS4CLNT_DELEGRETURN, &server->nfs_client->cl_state);
 631                 goto out;
 632         }
 633         rcu_read_unlock();
 634 out:
 635         iput(place_holder);
 636         return err;
 637 }
 638
 639 /**
 640  * nfs_client_return_marked_delegations - return previously marked delegations
 641  * @clp: nfs_client to process
 642  *
 643  * Note that this function is designed to be called by the state
 644  * manager thread. For this reason, it cannot flush the dirty data,
 645  * since that could deadlock in case of a state recovery error.
 646  *
 647  * Returns zero on success, or a negative errno value.
 648  */
 649 int nfs_client_return_marked_delegations(struct nfs_client *clp)
 650 {
 651         return nfs_client_for_each_server(clp,
 652                         nfs_server_return_marked_delegations, NULL);
 653 }
 654
 655 /**
 656  * nfs_inode_evict_delegation - return delegation, don't reclaim opens
 657  * @inode: inode to process
 658  *
 659  * Does not protect against delegation reclaims, therefore really only safe
 660  * to be called from nfs4_clear_inode(). Guaranteed to always free
 661  * the delegation structure.
 662  */
 663 void nfs_inode_evict_delegation(struct inode *inode)
 664 {
 665         struct nfs_delegation *delegation;
 666
 667         delegation = nfs_inode_detach_delegation(inode);
 668         if (delegation != NULL) {
 669                 set_bit(NFS_DELEGATION_RETURNING, &delegation->flags);
 670                 set_bit(NFS_DELEGATION_INODE_FREEING, &delegation->flags);
 671                 nfs_do_return_delegation(inode, delegation, 1);
 672                 nfs_free_delegation(delegation);
 673         }
 674 }
 675
 676 /**
 677  * nfs_inode_return_delegation - synchronously return a delegation
 678  * @inode: inode to process
 679  *
 680  * This routine will always flush any dirty data to disk on the
 681  * assumption that if we need to return the delegation, then
 682  * we should stop caching.
 683  *
 684  * Returns zero on success, or a negative errno value.
 685  */
 686 int nfs4_inode_return_delegation(struct inode *inode)
 687 {
 688         struct nfs_inode *nfsi = NFS_I(inode);
 689         struct nfs_delegation *delegation;
 690         int err = 0;
 691
 692         nfs_wb_all(inode);
 693         delegation = nfs_start_delegation_return(nfsi);
 694         if (delegation != NULL)
 695                 err = nfs_end_delegation_return(inode, delegation, 1);
 696         return err;
 697 }
 698
 699 /**
 700  * nfs_inode_return_delegation_on_close - asynchronously return a delegation
 701  * @inode: inode to process
 702  *
 703  * This routine is called on file close in order to determine if the
 704  * inode delegation needs to be returned immediately.
 705  */
 706 void nfs4_inode_return_delegation_on_close(struct inode *inode)
 707 {
 708         struct nfs_delegation *delegation;
 709         struct nfs_delegation *ret = NULL;
 710
 711         if (!inode)
 712                 return;
 713         rcu_read_lock();
 714         delegation = nfs4_get_valid_delegation(inode);
 715         if (!delegation)
 716                 goto out;
 717         if (test_bit(NFS_DELEGATION_RETURN_IF_CLOSED, &delegation->flags) ||
 718             atomic_long_read(&nfs_active_delegations) >= nfs_delegation_watermark) {
 719                 spin_lock(&delegation->lock);
 720                 if (delegation->inode &&
 721                     list_empty(&NFS_I(inode)->open_files) &&
 722                     !test_and_set_bit(NFS_DELEGATION_RETURNING, &delegation->flags)) {
 723                         clear_bit(NFS_DELEGATION_RETURN_IF_CLOSED, &delegation->flags);
 724                         /* Refcount matched in nfs_end_delegation_return() */
 725                         ret = nfs_get_delegation(delegation);
 726                 }
 727                 spin_unlock(&delegation->lock);
 728                 if (ret)
 729                         nfs_clear_verifier_delegated(inode);
 730         }
 731 out:
 732         rcu_read_unlock();
 733         nfs_end_delegation_return(inode, ret, 0);
 734 }
 735
 736 /**
 737  * nfs4_inode_make_writeable
 738  * @inode: pointer to inode
 739  *
 740  * Make the inode writeable by returning the delegation if necessary
 741  *
 742  * Returns zero on success, or a negative errno value.
 743  */
 744 int nfs4_inode_make_writeable(struct inode *inode)
 745 {
 746         struct nfs_delegation *delegation;
 747
 748         rcu_read_lock();
 749         delegation = nfs4_get_valid_delegation(inode);
 750         if (delegation == NULL ||
 751             (nfs4_has_session(NFS_SERVER(inode)->nfs_client) &&
 752              (delegation->type & FMODE_WRITE))) {
 753                 rcu_read_unlock();
 754                 return 0;
 755         }
 756         rcu_read_unlock();
 757         return nfs4_inode_return_delegation(inode);
 758 }
 759
 760 static void nfs_mark_return_if_closed_delegation(struct nfs_server *server,
 761                 struct nfs_delegation *delegation)
 762 {
 763         set_bit(NFS_DELEGATION_RETURN_IF_CLOSED, &delegation->flags);
 764         set_bit(NFS4CLNT_DELEGRETURN, &server->nfs_client->cl_state);
 765 }
 766
 767 static void nfs_mark_return_delegation(struct nfs_server *server,
 768                 struct nfs_delegation *delegation)
 769 {
 770         set_bit(NFS_DELEGATION_RETURN, &delegation->flags);
 771         set_bit(NFS4CLNT_DELEGRETURN, &server->nfs_client->cl_state);
 772 }
 773
 774 static bool nfs_server_mark_return_all_delegations(struct nfs_server *server)
 775 {
 776         struct nfs_delegation *delegation;
 777         bool ret = false;
 778
 779         list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
 780                 nfs_mark_return_delegation(server, delegation);
 781                 ret = true;
 782         }
 783         return ret;
 784 }
 785
 786 static void nfs_client_mark_return_all_delegations(struct nfs_client *clp)
 787 {
 788         struct nfs_server *server;
 789
 790         rcu_read_lock();
 791         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
 792                 nfs_server_mark_return_all_delegations(server);
 793         rcu_read_unlock();
 794 }
 795
 796 static void nfs_delegation_run_state_manager(struct nfs_client *clp)
 797 {
 798         if (test_bit(NFS4CLNT_DELEGRETURN, &clp->cl_state))
 799                 nfs4_schedule_state_manager(clp);
 800 }
 801
 802 /**
 803  * nfs_expire_all_delegations
 804  * @clp: client to process
 805  *
 806  */
 807 void nfs_expire_all_delegations(struct nfs_client *clp)
 808 {
 809         nfs_client_mark_return_all_delegations(clp);
 810         nfs_delegation_run_state_manager(clp);
 811 }
 812
 813 /**
 814  * nfs_super_return_all_delegations - return delegations for one superblock
 815  * @server: pointer to nfs_server to process
 816  *
 817  */
 818 void nfs_server_return_all_delegations(struct nfs_server *server)
 819 {
 820         struct nfs_client *clp = server->nfs_client;
 821         bool need_wait;
 822
 823         if (clp == NULL)
 824                 return;
 825
 826         rcu_read_lock();
 827         need_wait = nfs_server_mark_return_all_delegations(server);
 828         rcu_read_unlock();
 829
 830         if (need_wait) {
 831                 nfs4_schedule_state_manager(clp);
 832                 nfs4_wait_clnt_recover(clp);
 833         }
 834 }
 835
 836 static void nfs_mark_return_unused_delegation_types(struct nfs_server *server,
 837                                                  fmode_t flags)
 838 {
 839         struct nfs_delegation *delegation;
 840
 841         list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
 842                 if ((delegation->type == (FMODE_READ|FMODE_WRITE)) && !(flags & FMODE_WRITE))
 843                         continue;
 844                 if (delegation->type & flags)
 845                         nfs_mark_return_if_closed_delegation(server, delegation);
 846         }
 847 }
 848
 849 static void nfs_client_mark_return_unused_delegation_types(struct nfs_client *clp,
 850                                                         fmode_t flags)
 851 {
 852         struct nfs_server *server;
 853
 854         rcu_read_lock();
 855         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
 856                 nfs_mark_return_unused_delegation_types(server, flags);
 857         rcu_read_unlock();
 858 }
 859
 860 static void nfs_revoke_delegation(struct inode *inode,
 861                 const nfs4_stateid *stateid)
 862 {
 863         struct nfs_delegation *delegation;
 864         nfs4_stateid tmp;
 865         bool ret = false;
 866
 867         rcu_read_lock();
 868         delegation = rcu_dereference(NFS_I(inode)->delegation);
 869         if (delegation == NULL)
 870                 goto out;
 871         if (stateid == NULL) {
 872                 nfs4_stateid_copy(&tmp, &delegation->stateid);
 873                 stateid = &tmp;
 874         } else {
 875                 if (!nfs4_stateid_match_other(stateid, &delegation->stateid))
 876                         goto out;
 877                 spin_lock(&delegation->lock);
 878                 if (stateid->seqid) {
 879                         if (nfs4_stateid_is_newer(&delegation->stateid, stateid)) {
 880                                 spin_unlock(&delegation->lock);
 881                                 goto out;
 882                         }
 883                         delegation->stateid.seqid = stateid->seqid;
 884                 }
 885                 spin_unlock(&delegation->lock);
 886         }
 887         nfs_mark_delegation_revoked(delegation);
 888         ret = true;
 889 out:
 890         rcu_read_unlock();
 891         if (ret)
 892                 nfs_inode_find_state_and_recover(inode, stateid);
 893 }
 894
 895 void nfs_remove_bad_delegation(struct inode *inode,
 896                 const nfs4_stateid *stateid)
 897 {
 898         nfs_revoke_delegation(inode, stateid);
 899 }
 900 EXPORT_SYMBOL_GPL(nfs_remove_bad_delegation);
 901
 902 void nfs_delegation_mark_returned(struct inode *inode,
 903                 const nfs4_stateid *stateid)
 904 {
 905         struct nfs_delegation *delegation;
 906
 907         if (!inode)
 908                 return;
 909
 910         rcu_read_lock();
 911         delegation = rcu_dereference(NFS_I(inode)->delegation);
 912         if (!delegation)
 913                 goto out_rcu_unlock;
 914
 915         spin_lock(&delegation->lock);
 916         if (!nfs4_stateid_match_other(stateid, &delegation->stateid))
 917                 goto out_spin_unlock;
 918         if (stateid->seqid) {
 919                 /* If delegation->stateid is newer, dont mark as returned */
 920                 if (nfs4_stateid_is_newer(&delegation->stateid, stateid))
 921                         goto out_clear_returning;
 922                 if (delegation->stateid.seqid != stateid->seqid)
 923                         delegation->stateid.seqid = stateid->seqid;
 924         }
 925
 926         nfs_mark_delegation_revoked(delegation);
 927
 928 out_clear_returning:
 929         clear_bit(NFS_DELEGATION_RETURNING, &delegation->flags);
 930 out_spin_unlock:
 931         spin_unlock(&delegation->lock);
 932 out_rcu_unlock:
 933         rcu_read_unlock();
 934
 935         nfs_inode_find_state_and_recover(inode, stateid);
 936 }
 937
 938 /**
 939  * nfs_expire_unused_delegation_types
 940  * @clp: client to process
 941  * @flags: delegation types to expire
 942  *
 943  */
 944 void nfs_expire_unused_delegation_types(struct nfs_client *clp, fmode_t flags)
 945 {
 946         nfs_client_mark_return_unused_delegation_types(clp, flags);
 947         nfs_delegation_run_state_manager(clp);
 948 }
 949
 950 static void nfs_mark_return_unreferenced_delegations(struct nfs_server *server)
 951 {
 952         struct nfs_delegation *delegation;
 953
 954         list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
 955                 if (test_and_clear_bit(NFS_DELEGATION_REFERENCED, &delegation->flags))
 956                         continue;
 957                 nfs_mark_return_if_closed_delegation(server, delegation);
 958         }
 959 }
 960
 961 /**
 962  * nfs_expire_unreferenced_delegations - Eliminate unused delegations
 963  * @clp: nfs_client to process
 964  *
 965  */
 966 void nfs_expire_unreferenced_delegations(struct nfs_client *clp)
 967 {
 968         struct nfs_server *server;
 969
 970         rcu_read_lock();
 971         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
 972                 nfs_mark_return_unreferenced_delegations(server);
 973         rcu_read_unlock();
 974
 975         nfs_delegation_run_state_manager(clp);
 976 }
 977
 978 /**
 979  * nfs_async_inode_return_delegation - asynchronously return a delegation
 980  * @inode: inode to process
 981  * @stateid: state ID information
 982  *
 983  * Returns zero on success, or a negative errno value.
 984  */
 985 int nfs_async_inode_return_delegation(struct inode *inode,
 986                                       const nfs4_stateid *stateid)
 987 {
 988         struct nfs_server *server = NFS_SERVER(inode);
 989         struct nfs_client *clp = server->nfs_client;
 990         struct nfs_delegation *delegation;
 991
 992         rcu_read_lock();
 993         delegation = nfs4_get_valid_delegation(inode);
 994         if (delegation == NULL)
 995                 goto out_enoent;
 996         if (stateid != NULL &&
 997             !clp->cl_mvops->match_stateid(&delegation->stateid, stateid))
 998                 goto out_enoent;
 999         nfs_mark_return_delegation(server, delegation);
1000         rcu_read_unlock();
1001
1002         nfs_delegation_run_state_manager(clp);
1003         return 0;
1004 out_enoent:
1005         rcu_read_unlock();
1006         return -ENOENT;
1007 }
1008
1009 static struct inode *
1010 nfs_delegation_find_inode_server(struct nfs_server *server,
1011                                  const struct nfs_fh *fhandle)
1012 {
1013         struct nfs_delegation *delegation;
1014         struct inode *freeme, *res = NULL;
1015
1016         list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
1017                 spin_lock(&delegation->lock);
1018                 if (delegation->inode != NULL &&
1019                     !test_bit(NFS_DELEGATION_REVOKED, &delegation->flags) &&
1020                     nfs_compare_fh(fhandle, &NFS_I(delegation->inode)->fh) == 0) {
1021                         freeme = igrab(delegation->inode);
1022                         if (freeme && nfs_sb_active(freeme->i_sb))
1023                                 res = freeme;
1024                         spin_unlock(&delegation->lock);
1025                         if (res != NULL)
1026                                 return res;
1027                         if (freeme) {
1028                                 rcu_read_unlock();
1029                                 iput(freeme);
1030                                 rcu_read_lock();
1031                         }
1032                         return ERR_PTR(-EAGAIN);
1033                 }
1034                 spin_unlock(&delegation->lock);
1035         }
1036         return ERR_PTR(-ENOENT);
1037 }
1038
1039 /**
1040  * nfs_delegation_find_inode - retrieve the inode associated with a delegation
1041  * @clp: client state handle
1042  * @fhandle: filehandle from a delegation recall
1043  *
1044  * Returns pointer to inode matching "fhandle," or NULL if a matching inode
1045  * cannot be found.
1046  */
1047 struct inode *nfs_delegation_find_inode(struct nfs_client *clp,
1048                                         const struct nfs_fh *fhandle)
1049 {
1050         struct nfs_server *server;
1051         struct inode *res;
1052
1053         rcu_read_lock();
1054         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link) {
1055                 res = nfs_delegation_find_inode_server(server, fhandle);
1056                 if (res != ERR_PTR(-ENOENT)) {
1057                         rcu_read_unlock();
1058                         return res;
1059                 }
1060         }
1061         rcu_read_unlock();
1062         return ERR_PTR(-ENOENT);
1063 }
1064
1065 static void nfs_delegation_mark_reclaim_server(struct nfs_server *server)
1066 {
1067         struct nfs_delegation *delegation;
1068
1069         list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
1070                 /*
1071                  * If the delegation may have been admin revoked, then we
1072                  * cannot reclaim it.
1073                  */
1074                 if (test_bit(NFS_DELEGATION_TEST_EXPIRED, &delegation->flags))
1075                         continue;
1076                 set_bit(NFS_DELEGATION_NEED_RECLAIM, &delegation->flags);
1077         }
1078 }
1079
1080 /**
1081  * nfs_delegation_mark_reclaim - mark all delegations as needing to be reclaimed
1082  * @clp: nfs_client to process
1083  *
1084  */
1085 void nfs_delegation_mark_reclaim(struct nfs_client *clp)
1086 {
1087         struct nfs_server *server;
1088
1089         rcu_read_lock();
1090         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
1091                 nfs_delegation_mark_reclaim_server(server);
1092         rcu_read_unlock();
1093 }
1094
1095 static int nfs_server_reap_unclaimed_delegations(struct nfs_server *server,
1096                 void __always_unused *data)
1097 {
1098         struct nfs_delegation *delegation;
1099         struct inode *inode;
1100 restart:
1101         rcu_read_lock();
1102 restart_locked:
1103         list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
1104                 if (test_bit(NFS_DELEGATION_INODE_FREEING,
1105                                         &delegation->flags) ||
1106                     test_bit(NFS_DELEGATION_RETURNING,
1107                                         &delegation->flags) ||
1108                     test_bit(NFS_DELEGATION_NEED_RECLAIM,
1109                                         &delegation->flags) == 0)
1110                         continue;
1111                 inode = nfs_delegation_grab_inode(delegation);
1112                 if (inode == NULL)
1113                         goto restart_locked;
1114                 delegation = nfs_start_delegation_return_locked(NFS_I(inode));
1115                 rcu_read_unlock();
1116                 if (delegation != NULL) {
1117                         if (nfs_detach_delegation(NFS_I(inode), delegation,
1118                                                 server) != NULL)
1119                                 nfs_free_delegation(delegation);
1120                         /* Match nfs_start_delegation_return_locked */
1121                         nfs_put_delegation(delegation);
1122                 }
1123                 iput(inode);
1124                 cond_resched();
1125                 goto restart;
1126         }
1127         rcu_read_unlock();
1128         return 0;
1129 }
1130
1131 /**
1132  * nfs_delegation_reap_unclaimed - reap unclaimed delegations after reboot recovery is done
1133  * @clp: nfs_client to process
1134  *
1135  */
1136 void nfs_delegation_reap_unclaimed(struct nfs_client *clp)
1137 {
1138         nfs_client_for_each_server(clp, nfs_server_reap_unclaimed_delegations,
1139                         NULL);
1140 }
1141
1142 static inline bool nfs4_server_rebooted(const struct nfs_client *clp)
1143 {
1144         return (clp->cl_state & (BIT(NFS4CLNT_CHECK_LEASE) |
1145                                 BIT(NFS4CLNT_LEASE_EXPIRED) |
1146                                 BIT(NFS4CLNT_SESSION_RESET))) != 0;
1147 }
1148
1149 static void nfs_mark_test_expired_delegation(struct nfs_server *server,
1150             struct nfs_delegation *delegation)
1151 {
1152         if (delegation->stateid.type == NFS4_INVALID_STATEID_TYPE)
1153                 return;
1154         clear_bit(NFS_DELEGATION_NEED_RECLAIM, &delegation->flags);
1155         set_bit(NFS_DELEGATION_TEST_EXPIRED, &delegation->flags);
1156         set_bit(NFS4CLNT_DELEGATION_EXPIRED, &server->nfs_client->cl_state);
1157 }
1158
1159 static void nfs_inode_mark_test_expired_delegation(struct nfs_server *server,
1160                 struct inode *inode)
1161 {
1162         struct nfs_delegation *delegation;
1163
1164         rcu_read_lock();
1165         delegation = rcu_dereference(NFS_I(inode)->delegation);
1166         if (delegation)
1167                 nfs_mark_test_expired_delegation(server, delegation);
1168         rcu_read_unlock();
1169
1170 }
1171
1172 static void nfs_delegation_mark_test_expired_server(struct nfs_server *server)
1173 {
1174         struct nfs_delegation *delegation;
1175
1176         list_for_each_entry_rcu(delegation, &server->delegations, super_list)
1177                 nfs_mark_test_expired_delegation(server, delegation);
1178 }
1179
1180 /**
1181  * nfs_mark_test_expired_all_delegations - mark all delegations for testing
1182  * @clp: nfs_client to process
1183  *
1184  * Iterates through all the delegations associated with this server and
1185  * marks them as needing to be checked for validity.
1186  */
1187 void nfs_mark_test_expired_all_delegations(struct nfs_client *clp)
1188 {
1189         struct nfs_server *server;
1190
1191         rcu_read_lock();
1192         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
1193                 nfs_delegation_mark_test_expired_server(server);
1194         rcu_read_unlock();
1195 }
1196
1197 /**
1198  * nfs_test_expired_all_delegations - test all delegations for a client
1199  * @clp: nfs_client to process
1200  *
1201  * Helper for handling "recallable state revoked" status from server.
1202  */
1203 void nfs_test_expired_all_delegations(struct nfs_client *clp)
1204 {
1205         nfs_mark_test_expired_all_delegations(clp);
1206         nfs4_schedule_state_manager(clp);
1207 }
1208
1209 static void
1210 nfs_delegation_test_free_expired(struct inode *inode,
1211                 nfs4_stateid *stateid,
1212                 const struct cred *cred)
1213 {
1214         struct nfs_server *server = NFS_SERVER(inode);
1215         const struct nfs4_minor_version_ops *ops = server->nfs_client->cl_mvops;
1216         int status;
1217
1218         if (!cred)
1219                 return;
1220         status = ops->test_and_free_expired(server, stateid, cred);
1221         if (status == -NFS4ERR_EXPIRED || status == -NFS4ERR_BAD_STATEID)
1222                 nfs_remove_bad_delegation(inode, stateid);
1223 }
1224
1225 static int nfs_server_reap_expired_delegations(struct nfs_server *server,
1226                 void __always_unused *data)
1227 {
1228         struct nfs_delegation *delegation;
1229         struct inode *inode;
1230         const struct cred *cred;
1231         nfs4_stateid stateid;
1232 restart:
1233         rcu_read_lock();
1234 restart_locked:
1235         list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
1236                 if (test_bit(NFS_DELEGATION_INODE_FREEING,
1237                                         &delegation->flags) ||
1238                     test_bit(NFS_DELEGATION_RETURNING,
1239                                         &delegation->flags) ||
1240                     test_bit(NFS_DELEGATION_TEST_EXPIRED,
1241                                         &delegation->flags) == 0)
1242                         continue;
1243                 inode = nfs_delegation_grab_inode(delegation);
1244                 if (inode == NULL)
1245                         goto restart_locked;
1246                 spin_lock(&delegation->lock);
1247                 cred = get_cred_rcu(delegation->cred);
1248                 nfs4_stateid_copy(&stateid, &delegation->stateid);
1249                 spin_unlock(&delegation->lock);
1250                 clear_bit(NFS_DELEGATION_TEST_EXPIRED, &delegation->flags);
1251                 rcu_read_unlock();
1252                 nfs_delegation_test_free_expired(inode, &stateid, cred);
1253                 put_cred(cred);
1254                 if (!nfs4_server_rebooted(server->nfs_client)) {
1255                         iput(inode);
1256                         cond_resched();
1257                         goto restart;
1258                 }
1259                 nfs_inode_mark_test_expired_delegation(server,inode);
1260                 iput(inode);
1261                 return -EAGAIN;
1262         }
1263         rcu_read_unlock();
1264         return 0;
1265 }
1266
1267 /**
1268  * nfs_reap_expired_delegations - reap expired delegations
1269  * @clp: nfs_client to process
1270  *
1271  * Iterates through all the delegations associated with this server and
1272  * checks if they have may have been revoked. This function is usually
1273  * expected to be called in cases where the server may have lost its
1274  * lease.
1275  */
1276 void nfs_reap_expired_delegations(struct nfs_client *clp)
1277 {
1278         nfs_client_for_each_server(clp, nfs_server_reap_expired_delegations,
1279                         NULL);
1280 }
1281
1282 void nfs_inode_find_delegation_state_and_recover(struct inode *inode,
1283                 const nfs4_stateid *stateid)
1284 {
1285         struct nfs_client *clp = NFS_SERVER(inode)->nfs_client;
1286         struct nfs_delegation *delegation;
1287         bool found = false;
1288
1289         rcu_read_lock();
1290         delegation = rcu_dereference(NFS_I(inode)->delegation);
1291         if (delegation &&
1292             nfs4_stateid_match_or_older(&delegation->stateid, stateid) &&
1293             !test_bit(NFS_DELEGATION_REVOKED, &delegation->flags)) {
1294                 nfs_mark_test_expired_delegation(NFS_SERVER(inode), delegation);
1295                 found = true;
1296         }
1297         rcu_read_unlock();
1298         if (found)
1299                 nfs4_schedule_state_manager(clp);
1300 }
1301
1302 /**
1303  * nfs_delegations_present - check for existence of delegations
1304  * @clp: client state handle
1305  *
1306  * Returns one if there are any nfs_delegation structures attached
1307  * to this nfs_client.
1308  */
1309 int nfs_delegations_present(struct nfs_client *clp)
1310 {
1311         struct nfs_server *server;
1312         int ret = 0;
1313
1314         rcu_read_lock();
1315         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
1316                 if (!list_empty(&server->delegations)) {
1317                         ret = 1;
1318                         break;
1319                 }
1320         rcu_read_unlock();
1321         return ret;
1322 }
1323
1324 /**
1325  * nfs4_refresh_delegation_stateid - Update delegation stateid seqid
1326  * @dst: stateid to refresh
1327  * @inode: inode to check
1328  *
1329  * Returns "true" and updates "dst->seqid" * if inode had a delegation
1330  * that matches our delegation stateid. Otherwise "false" is returned.
1331  */
1332 bool nfs4_refresh_delegation_stateid(nfs4_stateid *dst, struct inode *inode)
1333 {
1334         struct nfs_delegation *delegation;
1335         bool ret = false;
1336         if (!inode)
1337                 goto out;
1338
1339         rcu_read_lock();
1340         delegation = rcu_dereference(NFS_I(inode)->delegation);
1341         if (delegation != NULL &&
1342             nfs4_stateid_match_other(dst, &delegation->stateid) &&
1343             nfs4_stateid_is_newer(&delegation->stateid, dst) &&
1344             !test_bit(NFS_DELEGATION_REVOKED, &delegation->flags)) {
1345                 dst->seqid = delegation->stateid.seqid;
1346                 ret = true;
1347         }
1348         rcu_read_unlock();
1349 out:
1350         return ret;
1351 }
1352
1353 /**
1354  * nfs4_copy_delegation_stateid - Copy inode's state ID information
1355  * @inode: inode to check
1356  * @flags: delegation type requirement
1357  * @dst: stateid data structure to fill in
1358  * @cred: optional argument to retrieve credential
1359  *
1360  * Returns "true" and fills in "dst->data" * if inode had a delegation,
1361  * otherwise "false" is returned.
1362  */
1363 bool nfs4_copy_delegation_stateid(struct inode *inode, fmode_t flags,
1364                 nfs4_stateid *dst, const struct cred **cred)
1365 {
1366         struct nfs_inode *nfsi = NFS_I(inode);
1367         struct nfs_delegation *delegation;
1368         bool ret = false;
1369
1370         flags &= FMODE_READ|FMODE_WRITE;
1371         rcu_read_lock();
1372         delegation = rcu_dereference(nfsi->delegation);
1373         if (!delegation)
1374                 goto out;
1375         spin_lock(&delegation->lock);
1376         ret = nfs4_is_valid_delegation(delegation, flags);
1377         if (ret) {
1378                 nfs4_stateid_copy(dst, &delegation->stateid);
1379                 nfs_mark_delegation_referenced(delegation);
1380                 if (cred)
1381                         *cred = get_cred(delegation->cred);
1382         }
1383         spin_unlock(&delegation->lock);
1384 out:
1385         rcu_read_unlock();
1386         return ret;
1387 }
1388
1389 /**
1390  * nfs4_delegation_flush_on_close - Check if we must flush file on close
1391  * @inode: inode to check
1392  *
1393  * This function checks the number of outstanding writes to the file
1394  * against the delegation 'space_limit' field to see if
1395  * the spec requires us to flush the file on close.
1396  */
1397 bool nfs4_delegation_flush_on_close(const struct inode *inode)
1398 {
1399         struct nfs_inode *nfsi = NFS_I(inode);
1400         struct nfs_delegation *delegation;
1401         bool ret = true;
1402
1403         rcu_read_lock();
1404         delegation = rcu_dereference(nfsi->delegation);
1405         if (delegation == NULL || !(delegation->type & FMODE_WRITE))
1406                 goto out;
1407         if (atomic_long_read(&nfsi->nrequests) < delegation->pagemod_limit)
1408                 ret = false;
1409 out:
1410         rcu_read_unlock();
1411         return ret;
1412 }
1413
1414 module_param_named(delegation_watermark, nfs_delegation_watermark, uint, 0644);