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         }
  46 }
  47
  48 static void nfs_free_delegation(struct nfs_delegation *delegation)
  49 {
  50         nfs_mark_delegation_revoked(delegation);
  51         __nfs_free_delegation(delegation);
  52 }
  53
  54 /**
  55  * nfs_mark_delegation_referenced - set delegation's REFERENCED flag
  56  * @delegation: delegation to process
  57  *
  58  */
  59 void nfs_mark_delegation_referenced(struct nfs_delegation *delegation)
  60 {
  61         set_bit(NFS_DELEGATION_REFERENCED, &delegation->flags);
  62 }
  63
  64 static bool
  65 nfs4_is_valid_delegation(const struct nfs_delegation *delegation,
  66                 fmode_t flags)
  67 {
  68         if (delegation != NULL && (delegation->type & flags) == flags &&
  69             !test_bit(NFS_DELEGATION_REVOKED, &delegation->flags) &&
  70             !test_bit(NFS_DELEGATION_RETURNING, &delegation->flags))
  71                 return true;
  72         return false;
  73 }
  74
  75 struct nfs_delegation *nfs4_get_valid_delegation(const struct inode *inode)
  76 {
  77         struct nfs_delegation *delegation;
  78
  79         delegation = rcu_dereference(NFS_I(inode)->delegation);
  80         if (nfs4_is_valid_delegation(delegation, 0))
  81                 return delegation;
  82         return NULL;
  83 }
  84
  85 static int
  86 nfs4_do_check_delegation(struct inode *inode, fmode_t flags, bool mark)
  87 {
  88         struct nfs_delegation *delegation;
  89         int ret = 0;
  90
  91         flags &= FMODE_READ|FMODE_WRITE;
  92         rcu_read_lock();
  93         delegation = rcu_dereference(NFS_I(inode)->delegation);
  94         if (nfs4_is_valid_delegation(delegation, flags)) {
  95                 if (mark)
  96                         nfs_mark_delegation_referenced(delegation);
  97                 ret = 1;
  98         }
  99         rcu_read_unlock();
 100         return ret;
 101 }
 102 /**
 103  * nfs_have_delegation - check if inode has a delegation, mark it
 104  * NFS_DELEGATION_REFERENCED if there is one.
 105  * @inode: inode to check
 106  * @flags: delegation types to check for
 107  *
 108  * Returns one if inode has the indicated delegation, otherwise zero.
 109  */
 110 int nfs4_have_delegation(struct inode *inode, fmode_t flags)
 111 {
 112         return nfs4_do_check_delegation(inode, flags, true);
 113 }
 114
 115 /*
 116  * nfs4_check_delegation - check if inode has a delegation, do not mark
 117  * NFS_DELEGATION_REFERENCED if it has one.
 118  */
 119 int nfs4_check_delegation(struct inode *inode, fmode_t flags)
 120 {
 121         return nfs4_do_check_delegation(inode, flags, false);
 122 }
 123
 124 static int nfs_delegation_claim_locks(struct nfs4_state *state, const nfs4_stateid *stateid)
 125 {
 126         struct inode *inode = state->inode;
 127         struct file_lock *fl;
 128         struct file_lock_context *flctx = inode->i_flctx;
 129         struct list_head *list;
 130         int status = 0;
 131
 132         if (flctx == NULL)
 133                 goto out;
 134
 135         list = &flctx->flc_posix;
 136         spin_lock(&flctx->flc_lock);
 137 restart:
 138         list_for_each_entry(fl, list, fl_list) {
 139                 if (nfs_file_open_context(fl->fl_file)->state != state)
 140                         continue;
 141                 spin_unlock(&flctx->flc_lock);
 142                 status = nfs4_lock_delegation_recall(fl, state, stateid);
 143                 if (status < 0)
 144                         goto out;
 145                 spin_lock(&flctx->flc_lock);
 146         }
 147         if (list == &flctx->flc_posix) {
 148                 list = &flctx->flc_flock;
 149                 goto restart;
 150         }
 151         spin_unlock(&flctx->flc_lock);
 152 out:
 153         return status;
 154 }
 155
 156 static int nfs_delegation_claim_opens(struct inode *inode,
 157                 const nfs4_stateid *stateid, fmode_t type)
 158 {
 159         struct nfs_inode *nfsi = NFS_I(inode);
 160         struct nfs_open_context *ctx;
 161         struct nfs4_state_owner *sp;
 162         struct nfs4_state *state;
 163         unsigned int seq;
 164         int err;
 165
 166 again:
 167         rcu_read_lock();
 168         list_for_each_entry_rcu(ctx, &nfsi->open_files, list) {
 169                 state = ctx->state;
 170                 if (state == NULL)
 171                         continue;
 172                 if (!test_bit(NFS_DELEGATED_STATE, &state->flags))
 173                         continue;
 174                 if (!nfs4_valid_open_stateid(state))
 175                         continue;
 176                 if (!nfs4_stateid_match(&state->stateid, stateid))
 177                         continue;
 178                 if (!get_nfs_open_context(ctx))
 179                         continue;
 180                 rcu_read_unlock();
 181                 sp = state->owner;
 182                 /* Block nfs4_proc_unlck */
 183                 mutex_lock(&sp->so_delegreturn_mutex);
 184                 seq = raw_seqcount_begin(&sp->so_reclaim_seqcount);
 185                 err = nfs4_open_delegation_recall(ctx, state, stateid);
 186                 if (!err)
 187                         err = nfs_delegation_claim_locks(state, stateid);
 188                 if (!err && read_seqcount_retry(&sp->so_reclaim_seqcount, seq))
 189                         err = -EAGAIN;
 190                 mutex_unlock(&sp->so_delegreturn_mutex);
 191                 put_nfs_open_context(ctx);
 192                 if (err != 0)
 193                         return err;
 194                 goto again;
 195         }
 196         rcu_read_unlock();
 197         return 0;
 198 }
 199
 200 /**
 201  * nfs_inode_reclaim_delegation - process a delegation reclaim request
 202  * @inode: inode to process
 203  * @cred: credential to use for request
 204  * @type: delegation type
 205  * @stateid: delegation stateid
 206  * @pagemod_limit: write delegation "space_limit"
 207  *
 208  */
 209 void nfs_inode_reclaim_delegation(struct inode *inode, const struct cred *cred,
 210                                   fmode_t type,
 211                                   const nfs4_stateid *stateid,
 212                                   unsigned long pagemod_limit)
 213 {
 214         struct nfs_delegation *delegation;
 215         const struct cred *oldcred = NULL;
 216
 217         rcu_read_lock();
 218         delegation = rcu_dereference(NFS_I(inode)->delegation);
 219         if (delegation != NULL) {
 220                 spin_lock(&delegation->lock);
 221                 if (nfs4_is_valid_delegation(delegation, 0)) {
 222                         nfs4_stateid_copy(&delegation->stateid, stateid);
 223                         delegation->type = type;
 224                         delegation->pagemod_limit = pagemod_limit;
 225                         oldcred = delegation->cred;
 226                         delegation->cred = get_cred(cred);
 227                         clear_bit(NFS_DELEGATION_NEED_RECLAIM,
 228                                   &delegation->flags);
 229                         spin_unlock(&delegation->lock);
 230                         rcu_read_unlock();
 231                         put_cred(oldcred);
 232                         trace_nfs4_reclaim_delegation(inode, type);
 233                         return;
 234                 }
 235                 /* We appear to have raced with a delegation return. */
 236                 spin_unlock(&delegation->lock);
 237         }
 238         rcu_read_unlock();
 239         nfs_inode_set_delegation(inode, cred, type, stateid, pagemod_limit);
 240 }
 241
 242 static int nfs_do_return_delegation(struct inode *inode, struct nfs_delegation *delegation, int issync)
 243 {
 244         int res = 0;
 245
 246         if (!test_bit(NFS_DELEGATION_REVOKED, &delegation->flags))
 247                 res = nfs4_proc_delegreturn(inode,
 248                                 delegation->cred,
 249                                 &delegation->stateid,
 250                                 issync);
 251         return res;
 252 }
 253
 254 static struct inode *nfs_delegation_grab_inode(struct nfs_delegation *delegation)
 255 {
 256         struct inode *inode = NULL;
 257
 258         spin_lock(&delegation->lock);
 259         if (delegation->inode != NULL)
 260                 inode = igrab(delegation->inode);
 261         if (!inode)
 262                 set_bit(NFS_DELEGATION_INODE_FREEING, &delegation->flags);
 263         spin_unlock(&delegation->lock);
 264         return inode;
 265 }
 266
 267 static struct nfs_delegation *
 268 nfs_start_delegation_return_locked(struct nfs_inode *nfsi)
 269 {
 270         struct nfs_delegation *ret = NULL;
 271         struct nfs_delegation *delegation = rcu_dereference(nfsi->delegation);
 272
 273         if (delegation == NULL)
 274                 goto out;
 275         spin_lock(&delegation->lock);
 276         if (!test_and_set_bit(NFS_DELEGATION_RETURNING, &delegation->flags))
 277                 ret = delegation;
 278         spin_unlock(&delegation->lock);
 279 out:
 280         return ret;
 281 }
 282
 283 static struct nfs_delegation *
 284 nfs_start_delegation_return(struct nfs_inode *nfsi)
 285 {
 286         struct nfs_delegation *delegation;
 287
 288         rcu_read_lock();
 289         delegation = nfs_start_delegation_return_locked(nfsi);
 290         rcu_read_unlock();
 291         return delegation;
 292 }
 293
 294 static void
 295 nfs_abort_delegation_return(struct nfs_delegation *delegation,
 296                 struct nfs_client *clp)
 297 {
 298
 299         spin_lock(&delegation->lock);
 300         clear_bit(NFS_DELEGATION_RETURNING, &delegation->flags);
 301         set_bit(NFS_DELEGATION_RETURN, &delegation->flags);
 302         spin_unlock(&delegation->lock);
 303         set_bit(NFS4CLNT_DELEGRETURN, &clp->cl_state);
 304 }
 305
 306 static struct nfs_delegation *
 307 nfs_detach_delegation_locked(struct nfs_inode *nfsi,
 308                 struct nfs_delegation *delegation,
 309                 struct nfs_client *clp)
 310 {
 311         struct nfs_delegation *deleg_cur =
 312                 rcu_dereference_protected(nfsi->delegation,
 313                                 lockdep_is_held(&clp->cl_lock));
 314
 315         if (deleg_cur == NULL || delegation != deleg_cur)
 316                 return NULL;
 317
 318         spin_lock(&delegation->lock);
 319         if (!delegation->inode) {
 320                 spin_unlock(&delegation->lock);
 321                 return NULL;
 322         }
 323         list_del_rcu(&delegation->super_list);
 324         delegation->inode = NULL;
 325         rcu_assign_pointer(nfsi->delegation, NULL);
 326         spin_unlock(&delegation->lock);
 327         return delegation;
 328 }
 329
 330 static struct nfs_delegation *nfs_detach_delegation(struct nfs_inode *nfsi,
 331                 struct nfs_delegation *delegation,
 332                 struct nfs_server *server)
 333 {
 334         struct nfs_client *clp = server->nfs_client;
 335
 336         spin_lock(&clp->cl_lock);
 337         delegation = nfs_detach_delegation_locked(nfsi, delegation, clp);
 338         spin_unlock(&clp->cl_lock);
 339         return delegation;
 340 }
 341
 342 static struct nfs_delegation *
 343 nfs_inode_detach_delegation(struct inode *inode)
 344 {
 345         struct nfs_inode *nfsi = NFS_I(inode);
 346         struct nfs_server *server = NFS_SERVER(inode);
 347         struct nfs_delegation *delegation;
 348
 349         rcu_read_lock();
 350         delegation = rcu_dereference(nfsi->delegation);
 351         if (delegation != NULL)
 352                 delegation = nfs_detach_delegation(nfsi, delegation, server);
 353         rcu_read_unlock();
 354         return delegation;
 355 }
 356
 357 static void
 358 nfs_update_inplace_delegation(struct nfs_delegation *delegation,
 359                 const struct nfs_delegation *update)
 360 {
 361         if (nfs4_stateid_is_newer(&update->stateid, &delegation->stateid)) {
 362                 delegation->stateid.seqid = update->stateid.seqid;
 363                 smp_wmb();
 364                 delegation->type = update->type;
 365                 if (test_and_clear_bit(NFS_DELEGATION_REVOKED, &delegation->flags))
 366                         atomic_long_inc(&nfs_active_delegations);
 367         }
 368 }
 369
 370 /**
 371  * nfs_inode_set_delegation - set up a delegation on an inode
 372  * @inode: inode to which delegation applies
 373  * @cred: cred to use for subsequent delegation processing
 374  * @type: delegation type
 375  * @stateid: delegation stateid
 376  * @pagemod_limit: write delegation "space_limit"
 377  *
 378  * Returns zero on success, or a negative errno value.
 379  */
 380 int nfs_inode_set_delegation(struct inode *inode, const struct cred *cred,
 381                                   fmode_t type,
 382                                   const nfs4_stateid *stateid,
 383                                   unsigned long pagemod_limit)
 384 {
 385         struct nfs_server *server = NFS_SERVER(inode);
 386         struct nfs_client *clp = server->nfs_client;
 387         struct nfs_inode *nfsi = NFS_I(inode);
 388         struct nfs_delegation *delegation, *old_delegation;
 389         struct nfs_delegation *freeme = NULL;
 390         int status = 0;
 391
 392         delegation = kmalloc(sizeof(*delegation), GFP_NOFS);
 393         if (delegation == NULL)
 394                 return -ENOMEM;
 395         nfs4_stateid_copy(&delegation->stateid, stateid);
 396         delegation->type = type;
 397         delegation->pagemod_limit = pagemod_limit;
 398         delegation->change_attr = inode_peek_iversion_raw(inode);
 399         delegation->cred = get_cred(cred);
 400         delegation->inode = inode;
 401         delegation->flags = 1<<NFS_DELEGATION_REFERENCED;
 402         spin_lock_init(&delegation->lock);
 403
 404         spin_lock(&clp->cl_lock);
 405         old_delegation = rcu_dereference_protected(nfsi->delegation,
 406                                         lockdep_is_held(&clp->cl_lock));
 407         if (old_delegation == NULL)
 408                 goto add_new;
 409         /* Is this an update of the existing delegation? */
 410         if (nfs4_stateid_match_other(&old_delegation->stateid,
 411                                 &delegation->stateid)) {
 412                 spin_lock(&old_delegation->lock);
 413                 nfs_update_inplace_delegation(old_delegation,
 414                                 delegation);
 415                 spin_unlock(&old_delegation->lock);
 416                 goto out;
 417         }
 418         if (!test_bit(NFS_DELEGATION_REVOKED, &old_delegation->flags)) {
 419                 /*
 420                  * Deal with broken servers that hand out two
 421                  * delegations for the same file.
 422                  * Allow for upgrades to a WRITE delegation, but
 423                  * nothing else.
 424                  */
 425                 dfprintk(FILE, "%s: server %s handed out "
 426                                 "a duplicate delegation!\n",
 427                                 __func__, clp->cl_hostname);
 428                 if (delegation->type == old_delegation->type ||
 429                     !(delegation->type & FMODE_WRITE)) {
 430                         freeme = delegation;
 431                         delegation = NULL;
 432                         goto out;
 433                 }
 434                 if (test_and_set_bit(NFS_DELEGATION_RETURNING,
 435                                         &old_delegation->flags))
 436                         goto out;
 437         }
 438         freeme = nfs_detach_delegation_locked(nfsi, old_delegation, clp);
 439         if (freeme == NULL)
 440                 goto out;
 441 add_new:
 442         list_add_tail_rcu(&delegation->super_list, &server->delegations);
 443         rcu_assign_pointer(nfsi->delegation, delegation);
 444         delegation = NULL;
 445
 446         atomic_long_inc(&nfs_active_delegations);
 447
 448         trace_nfs4_set_delegation(inode, type);
 449
 450         spin_lock(&inode->i_lock);
 451         if (NFS_I(inode)->cache_validity & (NFS_INO_INVALID_ATTR|NFS_INO_INVALID_ATIME))
 452                 NFS_I(inode)->cache_validity |= NFS_INO_REVAL_FORCED;
 453         spin_unlock(&inode->i_lock);
 454 out:
 455         spin_unlock(&clp->cl_lock);
 456         if (delegation != NULL)
 457                 __nfs_free_delegation(delegation);
 458         if (freeme != NULL) {
 459                 nfs_do_return_delegation(inode, freeme, 0);
 460                 nfs_free_delegation(freeme);
 461         }
 462         return status;
 463 }
 464
 465 /*
 466  * Basic procedure for returning a delegation to the server
 467  */
 468 static int nfs_end_delegation_return(struct inode *inode, struct nfs_delegation *delegation, int issync)
 469 {
 470         struct nfs_client *clp = NFS_SERVER(inode)->nfs_client;
 471         int err = 0;
 472
 473         if (delegation == NULL)
 474                 return 0;
 475         do {
 476                 if (test_bit(NFS_DELEGATION_REVOKED, &delegation->flags))
 477                         break;
 478                 err = nfs_delegation_claim_opens(inode, &delegation->stateid,
 479                                 delegation->type);
 480                 if (!issync || err != -EAGAIN)
 481                         break;
 482                 /*
 483                  * Guard against state recovery
 484                  */
 485                 err = nfs4_wait_clnt_recover(clp);
 486         } while (err == 0);
 487
 488         if (err) {
 489                 nfs_abort_delegation_return(delegation, clp);
 490                 goto out;
 491         }
 492
 493         err = nfs_do_return_delegation(inode, delegation, issync);
 494 out:
 495         return err;
 496 }
 497
 498 static bool nfs_delegation_need_return(struct nfs_delegation *delegation)
 499 {
 500         bool ret = false;
 501
 502         if (test_and_clear_bit(NFS_DELEGATION_RETURN, &delegation->flags))
 503                 ret = true;
 504         else if (test_bit(NFS_DELEGATION_RETURN_IF_CLOSED, &delegation->flags)) {
 505                 struct inode *inode;
 506
 507                 spin_lock(&delegation->lock);
 508                 inode = delegation->inode;
 509                 if (inode && list_empty(&NFS_I(inode)->open_files))
 510                         ret = true;
 511                 spin_unlock(&delegation->lock);
 512         }
 513         if (ret)
 514                 clear_bit(NFS_DELEGATION_RETURN_IF_CLOSED, &delegation->flags);
 515         if (test_bit(NFS_DELEGATION_RETURNING, &delegation->flags) ||
 516             test_bit(NFS_DELEGATION_REVOKED, &delegation->flags))
 517                 ret = false;
 518
 519         return ret;
 520 }
 521
 522 /**
 523  * nfs_client_return_marked_delegations - return previously marked delegations
 524  * @clp: nfs_client to process
 525  *
 526  * Note that this function is designed to be called by the state
 527  * manager thread. For this reason, it cannot flush the dirty data,
 528  * since that could deadlock in case of a state recovery error.
 529  *
 530  * Returns zero on success, or a negative errno value.
 531  */
 532 int nfs_client_return_marked_delegations(struct nfs_client *clp)
 533 {
 534         struct nfs_delegation *delegation;
 535         struct nfs_delegation *prev;
 536         struct nfs_server *server;
 537         struct inode *inode;
 538         struct inode *place_holder = NULL;
 539         struct nfs_delegation *place_holder_deleg = NULL;
 540         int err = 0;
 541
 542 restart:
 543         /*
 544          * To avoid quadratic looping we hold a reference
 545          * to an inode place_holder.  Each time we restart, we
 546          * list nfs_servers from the server of that inode, and
 547          * delegation in the server from the delegations of that
 548          * inode.
 549          * prev is an RCU-protected pointer to a delegation which
 550          * wasn't marked for return and might be a good choice for
 551          * the next place_holder.
 552          */
 553         rcu_read_lock();
 554         prev = NULL;
 555         if (place_holder)
 556                 server = NFS_SERVER(place_holder);
 557         else
 558                 server = list_entry_rcu(clp->cl_superblocks.next,
 559                                         struct nfs_server, client_link);
 560         list_for_each_entry_from_rcu(server, &clp->cl_superblocks, client_link) {
 561                 delegation = NULL;
 562                 if (place_holder && server == NFS_SERVER(place_holder))
 563                         delegation = rcu_dereference(NFS_I(place_holder)->delegation);
 564                 if (!delegation || delegation != place_holder_deleg)
 565                         delegation = list_entry_rcu(server->delegations.next,
 566                                                     struct nfs_delegation, super_list);
 567                 list_for_each_entry_from_rcu(delegation, &server->delegations, super_list) {
 568                         struct inode *to_put = NULL;
 569
 570                         if (!nfs_delegation_need_return(delegation)) {
 571                                 prev = delegation;
 572                                 continue;
 573                         }
 574                         if (!nfs_sb_active(server->super))
 575                                 break; /* continue in outer loop */
 576
 577                         if (prev) {
 578                                 struct inode *tmp;
 579
 580                                 tmp = nfs_delegation_grab_inode(prev);
 581                                 if (tmp) {
 582                                         to_put = place_holder;
 583                                         place_holder = tmp;
 584                                         place_holder_deleg = prev;
 585                                 }
 586                         }
 587
 588                         inode = nfs_delegation_grab_inode(delegation);
 589                         if (inode == NULL) {
 590                                 rcu_read_unlock();
 591                                 if (to_put)
 592                                         iput(to_put);
 593                                 nfs_sb_deactive(server->super);
 594                                 goto restart;
 595                         }
 596                         delegation = nfs_start_delegation_return_locked(NFS_I(inode));
 597                         rcu_read_unlock();
 598
 599                         if (to_put)
 600                                 iput(to_put);
 601
 602                         err = nfs_end_delegation_return(inode, delegation, 0);
 603                         iput(inode);
 604                         nfs_sb_deactive(server->super);
 605                         cond_resched();
 606                         if (!err)
 607                                 goto restart;
 608                         set_bit(NFS4CLNT_DELEGRETURN, &clp->cl_state);
 609                         if (place_holder)
 610                                 iput(place_holder);
 611                         return err;
 612                 }
 613         }
 614         rcu_read_unlock();
 615         if (place_holder)
 616                 iput(place_holder);
 617         return 0;
 618 }
 619
 620 /**
 621  * nfs_inode_evict_delegation - return delegation, don't reclaim opens
 622  * @inode: inode to process
 623  *
 624  * Does not protect against delegation reclaims, therefore really only safe
 625  * to be called from nfs4_clear_inode(). Guaranteed to always free
 626  * the delegation structure.
 627  */
 628 void nfs_inode_evict_delegation(struct inode *inode)
 629 {
 630         struct nfs_delegation *delegation;
 631
 632         delegation = nfs_inode_detach_delegation(inode);
 633         if (delegation != NULL) {
 634                 set_bit(NFS_DELEGATION_RETURNING, &delegation->flags);
 635                 set_bit(NFS_DELEGATION_INODE_FREEING, &delegation->flags);
 636                 nfs_do_return_delegation(inode, delegation, 1);
 637                 nfs_free_delegation(delegation);
 638         }
 639 }
 640
 641 /**
 642  * nfs_inode_return_delegation - synchronously return a delegation
 643  * @inode: inode to process
 644  *
 645  * This routine will always flush any dirty data to disk on the
 646  * assumption that if we need to return the delegation, then
 647  * we should stop caching.
 648  *
 649  * Returns zero on success, or a negative errno value.
 650  */
 651 int nfs4_inode_return_delegation(struct inode *inode)
 652 {
 653         struct nfs_inode *nfsi = NFS_I(inode);
 654         struct nfs_delegation *delegation;
 655         int err = 0;
 656
 657         nfs_wb_all(inode);
 658         delegation = nfs_start_delegation_return(nfsi);
 659         if (delegation != NULL)
 660                 err = nfs_end_delegation_return(inode, delegation, 1);
 661         return err;
 662 }
 663
 664 /**
 665  * nfs_inode_return_delegation_on_close - asynchronously return a delegation
 666  * @inode: inode to process
 667  *
 668  * This routine is called on file close in order to determine if the
 669  * inode delegation needs to be returned immediately.
 670  */
 671 void nfs4_inode_return_delegation_on_close(struct inode *inode)
 672 {
 673         struct nfs_delegation *delegation;
 674         struct nfs_delegation *ret = NULL;
 675
 676         if (!inode)
 677                 return;
 678         rcu_read_lock();
 679         delegation = nfs4_get_valid_delegation(inode);
 680         if (!delegation)
 681                 goto out;
 682         if (test_bit(NFS_DELEGATION_RETURN_IF_CLOSED, &delegation->flags) ||
 683             atomic_long_read(&nfs_active_delegations) >= nfs_delegation_watermark) {
 684                 spin_lock(&delegation->lock);
 685                 if (delegation->inode &&
 686                     list_empty(&NFS_I(inode)->open_files) &&
 687                     !test_and_set_bit(NFS_DELEGATION_RETURNING, &delegation->flags)) {
 688                         clear_bit(NFS_DELEGATION_RETURN_IF_CLOSED, &delegation->flags);
 689                         ret = delegation;
 690                 }
 691                 spin_unlock(&delegation->lock);
 692         }
 693 out:
 694         rcu_read_unlock();
 695         nfs_end_delegation_return(inode, ret, 0);
 696 }
 697
 698 /**
 699  * nfs4_inode_make_writeable
 700  * @inode: pointer to inode
 701  *
 702  * Make the inode writeable by returning the delegation if necessary
 703  *
 704  * Returns zero on success, or a negative errno value.
 705  */
 706 int nfs4_inode_make_writeable(struct inode *inode)
 707 {
 708         struct nfs_delegation *delegation;
 709
 710         rcu_read_lock();
 711         delegation = nfs4_get_valid_delegation(inode);
 712         if (delegation == NULL ||
 713             (nfs4_has_session(NFS_SERVER(inode)->nfs_client) &&
 714              (delegation->type & FMODE_WRITE))) {
 715                 rcu_read_unlock();
 716                 return 0;
 717         }
 718         rcu_read_unlock();
 719         return nfs4_inode_return_delegation(inode);
 720 }
 721
 722 static void nfs_mark_return_if_closed_delegation(struct nfs_server *server,
 723                 struct nfs_delegation *delegation)
 724 {
 725         set_bit(NFS_DELEGATION_RETURN_IF_CLOSED, &delegation->flags);
 726         set_bit(NFS4CLNT_DELEGRETURN, &server->nfs_client->cl_state);
 727 }
 728
 729 static void nfs_mark_return_delegation(struct nfs_server *server,
 730                 struct nfs_delegation *delegation)
 731 {
 732         set_bit(NFS_DELEGATION_RETURN, &delegation->flags);
 733         set_bit(NFS4CLNT_DELEGRETURN, &server->nfs_client->cl_state);
 734 }
 735
 736 static bool nfs_server_mark_return_all_delegations(struct nfs_server *server)
 737 {
 738         struct nfs_delegation *delegation;
 739         bool ret = false;
 740
 741         list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
 742                 nfs_mark_return_delegation(server, delegation);
 743                 ret = true;
 744         }
 745         return ret;
 746 }
 747
 748 static void nfs_client_mark_return_all_delegations(struct nfs_client *clp)
 749 {
 750         struct nfs_server *server;
 751
 752         rcu_read_lock();
 753         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
 754                 nfs_server_mark_return_all_delegations(server);
 755         rcu_read_unlock();
 756 }
 757
 758 static void nfs_delegation_run_state_manager(struct nfs_client *clp)
 759 {
 760         if (test_bit(NFS4CLNT_DELEGRETURN, &clp->cl_state))
 761                 nfs4_schedule_state_manager(clp);
 762 }
 763
 764 /**
 765  * nfs_expire_all_delegations
 766  * @clp: client to process
 767  *
 768  */
 769 void nfs_expire_all_delegations(struct nfs_client *clp)
 770 {
 771         nfs_client_mark_return_all_delegations(clp);
 772         nfs_delegation_run_state_manager(clp);
 773 }
 774
 775 /**
 776  * nfs_super_return_all_delegations - return delegations for one superblock
 777  * @server: pointer to nfs_server to process
 778  *
 779  */
 780 void nfs_server_return_all_delegations(struct nfs_server *server)
 781 {
 782         struct nfs_client *clp = server->nfs_client;
 783         bool need_wait;
 784
 785         if (clp == NULL)
 786                 return;
 787
 788         rcu_read_lock();
 789         need_wait = nfs_server_mark_return_all_delegations(server);
 790         rcu_read_unlock();
 791
 792         if (need_wait) {
 793                 nfs4_schedule_state_manager(clp);
 794                 nfs4_wait_clnt_recover(clp);
 795         }
 796 }
 797
 798 static void nfs_mark_return_unused_delegation_types(struct nfs_server *server,
 799                                                  fmode_t flags)
 800 {
 801         struct nfs_delegation *delegation;
 802
 803         list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
 804                 if ((delegation->type == (FMODE_READ|FMODE_WRITE)) && !(flags & FMODE_WRITE))
 805                         continue;
 806                 if (delegation->type & flags)
 807                         nfs_mark_return_if_closed_delegation(server, delegation);
 808         }
 809 }
 810
 811 static void nfs_client_mark_return_unused_delegation_types(struct nfs_client *clp,
 812                                                         fmode_t flags)
 813 {
 814         struct nfs_server *server;
 815
 816         rcu_read_lock();
 817         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
 818                 nfs_mark_return_unused_delegation_types(server, flags);
 819         rcu_read_unlock();
 820 }
 821
 822 static void nfs_revoke_delegation(struct inode *inode,
 823                 const nfs4_stateid *stateid)
 824 {
 825         struct nfs_delegation *delegation;
 826         nfs4_stateid tmp;
 827         bool ret = false;
 828
 829         rcu_read_lock();
 830         delegation = rcu_dereference(NFS_I(inode)->delegation);
 831         if (delegation == NULL)
 832                 goto out;
 833         if (stateid == NULL) {
 834                 nfs4_stateid_copy(&tmp, &delegation->stateid);
 835                 stateid = &tmp;
 836         } else {
 837                 if (!nfs4_stateid_match_other(stateid, &delegation->stateid))
 838                         goto out;
 839                 spin_lock(&delegation->lock);
 840                 if (stateid->seqid) {
 841                         if (nfs4_stateid_is_newer(&delegation->stateid, stateid)) {
 842                                 spin_unlock(&delegation->lock);
 843                                 goto out;
 844                         }
 845                         delegation->stateid.seqid = stateid->seqid;
 846                 }
 847                 spin_unlock(&delegation->lock);
 848         }
 849         nfs_mark_delegation_revoked(delegation);
 850         ret = true;
 851 out:
 852         rcu_read_unlock();
 853         if (ret)
 854                 nfs_inode_find_state_and_recover(inode, stateid);
 855 }
 856
 857 void nfs_remove_bad_delegation(struct inode *inode,
 858                 const nfs4_stateid *stateid)
 859 {
 860         nfs_revoke_delegation(inode, stateid);
 861 }
 862 EXPORT_SYMBOL_GPL(nfs_remove_bad_delegation);
 863
 864 void nfs_delegation_mark_returned(struct inode *inode,
 865                 const nfs4_stateid *stateid)
 866 {
 867         struct nfs_delegation *delegation;
 868
 869         if (!inode)
 870                 return;
 871
 872         rcu_read_lock();
 873         delegation = rcu_dereference(NFS_I(inode)->delegation);
 874         if (!delegation)
 875                 goto out_rcu_unlock;
 876
 877         spin_lock(&delegation->lock);
 878         if (!nfs4_stateid_match_other(stateid, &delegation->stateid))
 879                 goto out_spin_unlock;
 880         if (stateid->seqid) {
 881                 /* If delegation->stateid is newer, dont mark as returned */
 882                 if (nfs4_stateid_is_newer(&delegation->stateid, stateid))
 883                         goto out_clear_returning;
 884                 if (delegation->stateid.seqid != stateid->seqid)
 885                         delegation->stateid.seqid = stateid->seqid;
 886         }
 887
 888         nfs_mark_delegation_revoked(delegation);
 889
 890 out_clear_returning:
 891         clear_bit(NFS_DELEGATION_RETURNING, &delegation->flags);
 892 out_spin_unlock:
 893         spin_unlock(&delegation->lock);
 894 out_rcu_unlock:
 895         rcu_read_unlock();
 896
 897         nfs_inode_find_state_and_recover(inode, stateid);
 898 }
 899
 900 /**
 901  * nfs_expire_unused_delegation_types
 902  * @clp: client to process
 903  * @flags: delegation types to expire
 904  *
 905  */
 906 void nfs_expire_unused_delegation_types(struct nfs_client *clp, fmode_t flags)
 907 {
 908         nfs_client_mark_return_unused_delegation_types(clp, flags);
 909         nfs_delegation_run_state_manager(clp);
 910 }
 911
 912 static void nfs_mark_return_unreferenced_delegations(struct nfs_server *server)
 913 {
 914         struct nfs_delegation *delegation;
 915
 916         list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
 917                 if (test_and_clear_bit(NFS_DELEGATION_REFERENCED, &delegation->flags))
 918                         continue;
 919                 nfs_mark_return_if_closed_delegation(server, delegation);
 920         }
 921 }
 922
 923 /**
 924  * nfs_expire_unreferenced_delegations - Eliminate unused delegations
 925  * @clp: nfs_client to process
 926  *
 927  */
 928 void nfs_expire_unreferenced_delegations(struct nfs_client *clp)
 929 {
 930         struct nfs_server *server;
 931
 932         rcu_read_lock();
 933         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
 934                 nfs_mark_return_unreferenced_delegations(server);
 935         rcu_read_unlock();
 936
 937         nfs_delegation_run_state_manager(clp);
 938 }
 939
 940 /**
 941  * nfs_async_inode_return_delegation - asynchronously return a delegation
 942  * @inode: inode to process
 943  * @stateid: state ID information
 944  *
 945  * Returns zero on success, or a negative errno value.
 946  */
 947 int nfs_async_inode_return_delegation(struct inode *inode,
 948                                       const nfs4_stateid *stateid)
 949 {
 950         struct nfs_server *server = NFS_SERVER(inode);
 951         struct nfs_client *clp = server->nfs_client;
 952         struct nfs_delegation *delegation;
 953
 954         rcu_read_lock();
 955         delegation = nfs4_get_valid_delegation(inode);
 956         if (delegation == NULL)
 957                 goto out_enoent;
 958         if (stateid != NULL &&
 959             !clp->cl_mvops->match_stateid(&delegation->stateid, stateid))
 960                 goto out_enoent;
 961         nfs_mark_return_delegation(server, delegation);
 962         rcu_read_unlock();
 963
 964         nfs_delegation_run_state_manager(clp);
 965         return 0;
 966 out_enoent:
 967         rcu_read_unlock();
 968         return -ENOENT;
 969 }
 970
 971 static struct inode *
 972 nfs_delegation_find_inode_server(struct nfs_server *server,
 973                                  const struct nfs_fh *fhandle)
 974 {
 975         struct nfs_delegation *delegation;
 976         struct inode *freeme, *res = NULL;
 977
 978         list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
 979                 spin_lock(&delegation->lock);
 980                 if (delegation->inode != NULL &&
 981                     !test_bit(NFS_DELEGATION_REVOKED, &delegation->flags) &&
 982                     nfs_compare_fh(fhandle, &NFS_I(delegation->inode)->fh) == 0) {
 983                         freeme = igrab(delegation->inode);
 984                         if (freeme && nfs_sb_active(freeme->i_sb))
 985                                 res = freeme;
 986                         spin_unlock(&delegation->lock);
 987                         if (res != NULL)
 988                                 return res;
 989                         if (freeme) {
 990                                 rcu_read_unlock();
 991                                 iput(freeme);
 992                                 rcu_read_lock();
 993                         }
 994                         return ERR_PTR(-EAGAIN);
 995                 }
 996                 spin_unlock(&delegation->lock);
 997         }
 998         return ERR_PTR(-ENOENT);
 999 }
1000
1001 /**
1002  * nfs_delegation_find_inode - retrieve the inode associated with a delegation
1003  * @clp: client state handle
1004  * @fhandle: filehandle from a delegation recall
1005  *
1006  * Returns pointer to inode matching "fhandle," or NULL if a matching inode
1007  * cannot be found.
1008  */
1009 struct inode *nfs_delegation_find_inode(struct nfs_client *clp,
1010                                         const struct nfs_fh *fhandle)
1011 {
1012         struct nfs_server *server;
1013         struct inode *res;
1014
1015         rcu_read_lock();
1016         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link) {
1017                 res = nfs_delegation_find_inode_server(server, fhandle);
1018                 if (res != ERR_PTR(-ENOENT)) {
1019                         rcu_read_unlock();
1020                         return res;
1021                 }
1022         }
1023         rcu_read_unlock();
1024         return ERR_PTR(-ENOENT);
1025 }
1026
1027 static void nfs_delegation_mark_reclaim_server(struct nfs_server *server)
1028 {
1029         struct nfs_delegation *delegation;
1030
1031         list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
1032                 /*
1033                  * If the delegation may have been admin revoked, then we
1034                  * cannot reclaim it.
1035                  */
1036                 if (test_bit(NFS_DELEGATION_TEST_EXPIRED, &delegation->flags))
1037                         continue;
1038                 set_bit(NFS_DELEGATION_NEED_RECLAIM, &delegation->flags);
1039         }
1040 }
1041
1042 /**
1043  * nfs_delegation_mark_reclaim - mark all delegations as needing to be reclaimed
1044  * @clp: nfs_client to process
1045  *
1046  */
1047 void nfs_delegation_mark_reclaim(struct nfs_client *clp)
1048 {
1049         struct nfs_server *server;
1050
1051         rcu_read_lock();
1052         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
1053                 nfs_delegation_mark_reclaim_server(server);
1054         rcu_read_unlock();
1055 }
1056
1057 /**
1058  * nfs_delegation_reap_unclaimed - reap unclaimed delegations after reboot recovery is done
1059  * @clp: nfs_client to process
1060  *
1061  */
1062 void nfs_delegation_reap_unclaimed(struct nfs_client *clp)
1063 {
1064         struct nfs_delegation *delegation;
1065         struct nfs_server *server;
1066         struct inode *inode;
1067
1068 restart:
1069         rcu_read_lock();
1070         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link) {
1071                 list_for_each_entry_rcu(delegation, &server->delegations,
1072                                                                 super_list) {
1073                         if (test_bit(NFS_DELEGATION_INODE_FREEING,
1074                                                 &delegation->flags) ||
1075                             test_bit(NFS_DELEGATION_RETURNING,
1076                                                 &delegation->flags) ||
1077                             test_bit(NFS_DELEGATION_NEED_RECLAIM,
1078                                                 &delegation->flags) == 0)
1079                                 continue;
1080                         if (!nfs_sb_active(server->super))
1081                                 break; /* continue in outer loop */
1082                         inode = nfs_delegation_grab_inode(delegation);
1083                         if (inode == NULL) {
1084                                 rcu_read_unlock();
1085                                 nfs_sb_deactive(server->super);
1086                                 goto restart;
1087                         }
1088                         delegation = nfs_start_delegation_return_locked(NFS_I(inode));
1089                         rcu_read_unlock();
1090                         if (delegation != NULL) {
1091                                 delegation = nfs_detach_delegation(NFS_I(inode),
1092                                         delegation, server);
1093                                 if (delegation != NULL)
1094                                         nfs_free_delegation(delegation);
1095                         }
1096                         iput(inode);
1097                         nfs_sb_deactive(server->super);
1098                         cond_resched();
1099                         goto restart;
1100                 }
1101         }
1102         rcu_read_unlock();
1103 }
1104
1105 static inline bool nfs4_server_rebooted(const struct nfs_client *clp)
1106 {
1107         return (clp->cl_state & (BIT(NFS4CLNT_CHECK_LEASE) |
1108                                 BIT(NFS4CLNT_LEASE_EXPIRED) |
1109                                 BIT(NFS4CLNT_SESSION_RESET))) != 0;
1110 }
1111
1112 static void nfs_mark_test_expired_delegation(struct nfs_server *server,
1113             struct nfs_delegation *delegation)
1114 {
1115         if (delegation->stateid.type == NFS4_INVALID_STATEID_TYPE)
1116                 return;
1117         clear_bit(NFS_DELEGATION_NEED_RECLAIM, &delegation->flags);
1118         set_bit(NFS_DELEGATION_TEST_EXPIRED, &delegation->flags);
1119         set_bit(NFS4CLNT_DELEGATION_EXPIRED, &server->nfs_client->cl_state);
1120 }
1121
1122 static void nfs_inode_mark_test_expired_delegation(struct nfs_server *server,
1123                 struct inode *inode)
1124 {
1125         struct nfs_delegation *delegation;
1126
1127         rcu_read_lock();
1128         delegation = rcu_dereference(NFS_I(inode)->delegation);
1129         if (delegation)
1130                 nfs_mark_test_expired_delegation(server, delegation);
1131         rcu_read_unlock();
1132
1133 }
1134
1135 static void nfs_delegation_mark_test_expired_server(struct nfs_server *server)
1136 {
1137         struct nfs_delegation *delegation;
1138
1139         list_for_each_entry_rcu(delegation, &server->delegations, super_list)
1140                 nfs_mark_test_expired_delegation(server, delegation);
1141 }
1142
1143 /**
1144  * nfs_mark_test_expired_all_delegations - mark all delegations for testing
1145  * @clp: nfs_client to process
1146  *
1147  * Iterates through all the delegations associated with this server and
1148  * marks them as needing to be checked for validity.
1149  */
1150 void nfs_mark_test_expired_all_delegations(struct nfs_client *clp)
1151 {
1152         struct nfs_server *server;
1153
1154         rcu_read_lock();
1155         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
1156                 nfs_delegation_mark_test_expired_server(server);
1157         rcu_read_unlock();
1158 }
1159
1160 /**
1161  * nfs_test_expired_all_delegations - test all delegations for a client
1162  * @clp: nfs_client to process
1163  *
1164  * Helper for handling "recallable state revoked" status from server.
1165  */
1166 void nfs_test_expired_all_delegations(struct nfs_client *clp)
1167 {
1168         nfs_mark_test_expired_all_delegations(clp);
1169         nfs4_schedule_state_manager(clp);
1170 }
1171
1172 static void
1173 nfs_delegation_test_free_expired(struct inode *inode,
1174                 nfs4_stateid *stateid,
1175                 const struct cred *cred)
1176 {
1177         struct nfs_server *server = NFS_SERVER(inode);
1178         const struct nfs4_minor_version_ops *ops = server->nfs_client->cl_mvops;
1179         int status;
1180
1181         if (!cred)
1182                 return;
1183         status = ops->test_and_free_expired(server, stateid, cred);
1184         if (status == -NFS4ERR_EXPIRED || status == -NFS4ERR_BAD_STATEID)
1185                 nfs_remove_bad_delegation(inode, stateid);
1186 }
1187
1188 /**
1189  * nfs_reap_expired_delegations - reap expired delegations
1190  * @clp: nfs_client to process
1191  *
1192  * Iterates through all the delegations associated with this server and
1193  * checks if they have may have been revoked. This function is usually
1194  * expected to be called in cases where the server may have lost its
1195  * lease.
1196  */
1197 void nfs_reap_expired_delegations(struct nfs_client *clp)
1198 {
1199         struct nfs_delegation *delegation;
1200         struct nfs_server *server;
1201         struct inode *inode;
1202         const struct cred *cred;
1203         nfs4_stateid stateid;
1204
1205 restart:
1206         rcu_read_lock();
1207         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link) {
1208                 list_for_each_entry_rcu(delegation, &server->delegations,
1209                                                                 super_list) {
1210                         if (test_bit(NFS_DELEGATION_INODE_FREEING,
1211                                                 &delegation->flags) ||
1212                             test_bit(NFS_DELEGATION_RETURNING,
1213                                                 &delegation->flags) ||
1214                             test_bit(NFS_DELEGATION_TEST_EXPIRED,
1215                                                 &delegation->flags) == 0)
1216                                 continue;
1217                         if (!nfs_sb_active(server->super))
1218                                 break; /* continue in outer loop */
1219                         inode = nfs_delegation_grab_inode(delegation);
1220                         if (inode == NULL) {
1221                                 rcu_read_unlock();
1222                                 nfs_sb_deactive(server->super);
1223                                 goto restart;
1224                         }
1225                         cred = get_cred_rcu(delegation->cred);
1226                         nfs4_stateid_copy(&stateid, &delegation->stateid);
1227                         clear_bit(NFS_DELEGATION_TEST_EXPIRED, &delegation->flags);
1228                         rcu_read_unlock();
1229                         nfs_delegation_test_free_expired(inode, &stateid, cred);
1230                         put_cred(cred);
1231                         if (nfs4_server_rebooted(clp)) {
1232                                 nfs_inode_mark_test_expired_delegation(server,inode);
1233                                 iput(inode);
1234                                 nfs_sb_deactive(server->super);
1235                                 return;
1236                         }
1237                         iput(inode);
1238                         nfs_sb_deactive(server->super);
1239                         cond_resched();
1240                         goto restart;
1241                 }
1242         }
1243         rcu_read_unlock();
1244 }
1245
1246 void nfs_inode_find_delegation_state_and_recover(struct inode *inode,
1247                 const nfs4_stateid *stateid)
1248 {
1249         struct nfs_client *clp = NFS_SERVER(inode)->nfs_client;
1250         struct nfs_delegation *delegation;
1251         bool found = false;
1252
1253         rcu_read_lock();
1254         delegation = rcu_dereference(NFS_I(inode)->delegation);
1255         if (delegation &&
1256             nfs4_stateid_match_or_older(&delegation->stateid, stateid) &&
1257             !test_bit(NFS_DELEGATION_REVOKED, &delegation->flags)) {
1258                 nfs_mark_test_expired_delegation(NFS_SERVER(inode), delegation);
1259                 found = true;
1260         }
1261         rcu_read_unlock();
1262         if (found)
1263                 nfs4_schedule_state_manager(clp);
1264 }
1265
1266 /**
1267  * nfs_delegations_present - check for existence of delegations
1268  * @clp: client state handle
1269  *
1270  * Returns one if there are any nfs_delegation structures attached
1271  * to this nfs_client.
1272  */
1273 int nfs_delegations_present(struct nfs_client *clp)
1274 {
1275         struct nfs_server *server;
1276         int ret = 0;
1277
1278         rcu_read_lock();
1279         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
1280                 if (!list_empty(&server->delegations)) {
1281                         ret = 1;
1282                         break;
1283                 }
1284         rcu_read_unlock();
1285         return ret;
1286 }
1287
1288 /**
1289  * nfs4_refresh_delegation_stateid - Update delegation stateid seqid
1290  * @dst: stateid to refresh
1291  * @inode: inode to check
1292  *
1293  * Returns "true" and updates "dst->seqid" * if inode had a delegation
1294  * that matches our delegation stateid. Otherwise "false" is returned.
1295  */
1296 bool nfs4_refresh_delegation_stateid(nfs4_stateid *dst, struct inode *inode)
1297 {
1298         struct nfs_delegation *delegation;
1299         bool ret = false;
1300         if (!inode)
1301                 goto out;
1302
1303         rcu_read_lock();
1304         delegation = rcu_dereference(NFS_I(inode)->delegation);
1305         if (delegation != NULL &&
1306             nfs4_stateid_match_other(dst, &delegation->stateid) &&
1307             nfs4_stateid_is_newer(&delegation->stateid, dst) &&
1308             !test_bit(NFS_DELEGATION_REVOKED, &delegation->flags)) {
1309                 dst->seqid = delegation->stateid.seqid;
1310                 ret = true;
1311         }
1312         rcu_read_unlock();
1313 out:
1314         return ret;
1315 }
1316
1317 /**
1318  * nfs4_copy_delegation_stateid - Copy inode's state ID information
1319  * @inode: inode to check
1320  * @flags: delegation type requirement
1321  * @dst: stateid data structure to fill in
1322  * @cred: optional argument to retrieve credential
1323  *
1324  * Returns "true" and fills in "dst->data" * if inode had a delegation,
1325  * otherwise "false" is returned.
1326  */
1327 bool nfs4_copy_delegation_stateid(struct inode *inode, fmode_t flags,
1328                 nfs4_stateid *dst, const struct cred **cred)
1329 {
1330         struct nfs_inode *nfsi = NFS_I(inode);
1331         struct nfs_delegation *delegation;
1332         bool ret;
1333
1334         flags &= FMODE_READ|FMODE_WRITE;
1335         rcu_read_lock();
1336         delegation = rcu_dereference(nfsi->delegation);
1337         ret = nfs4_is_valid_delegation(delegation, flags);
1338         if (ret) {
1339                 nfs4_stateid_copy(dst, &delegation->stateid);
1340                 nfs_mark_delegation_referenced(delegation);
1341                 if (cred)
1342                         *cred = get_cred(delegation->cred);
1343         }
1344         rcu_read_unlock();
1345         return ret;
1346 }
1347
1348 /**
1349  * nfs4_delegation_flush_on_close - Check if we must flush file on close
1350  * @inode: inode to check
1351  *
1352  * This function checks the number of outstanding writes to the file
1353  * against the delegation 'space_limit' field to see if
1354  * the spec requires us to flush the file on close.
1355  */
1356 bool nfs4_delegation_flush_on_close(const struct inode *inode)
1357 {
1358         struct nfs_inode *nfsi = NFS_I(inode);
1359         struct nfs_delegation *delegation;
1360         bool ret = true;
1361
1362         rcu_read_lock();
1363         delegation = rcu_dereference(nfsi->delegation);
1364         if (delegation == NULL || !(delegation->type & FMODE_WRITE))
1365                 goto out;
1366         if (atomic_long_read(&nfsi->nrequests) < delegation->pagemod_limit)
1367                 ret = false;
1368 out:
1369         rcu_read_unlock();
1370         return ret;
1371 }
1372
1373 module_param_named(delegation_watermark, nfs_delegation_watermark, uint, 0644);