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  * nfs4_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         /*
 485          * If we didn't revalidate the change attribute before setting
 486          * the delegation, then pre-emptively ask for a full attribute
 487          * cache revalidation.
 488          */
 489         spin_lock(&inode->i_lock);
 490         if (NFS_I(inode)->cache_validity & NFS_INO_INVALID_CHANGE)
 491                 nfs_set_cache_invalid(inode,
 492                         NFS_INO_INVALID_ATIME | NFS_INO_INVALID_CTIME |
 493                         NFS_INO_INVALID_MTIME | NFS_INO_INVALID_SIZE |
 494                         NFS_INO_INVALID_BLOCKS | NFS_INO_INVALID_NLINK |
 495                         NFS_INO_INVALID_OTHER | NFS_INO_INVALID_DATA |
 496                         NFS_INO_INVALID_ACCESS | NFS_INO_INVALID_ACL |
 497                         NFS_INO_INVALID_XATTR);
 498         spin_unlock(&inode->i_lock);
 499
 500         list_add_tail_rcu(&delegation->super_list, &server->delegations);
 501         rcu_assign_pointer(nfsi->delegation, delegation);
 502         delegation = NULL;
 503
 504         atomic_long_inc(&nfs_active_delegations);
 505
 506         trace_nfs4_set_delegation(inode, type);
 507 out:
 508         spin_unlock(&clp->cl_lock);
 509         if (delegation != NULL)
 510                 __nfs_free_delegation(delegation);
 511         if (freeme != NULL) {
 512                 nfs_do_return_delegation(inode, freeme, 0);
 513                 nfs_free_delegation(freeme);
 514         }
 515         return status;
 516 }
 517
 518 /*
 519  * Basic procedure for returning a delegation to the server
 520  */
 521 static int nfs_end_delegation_return(struct inode *inode, struct nfs_delegation *delegation, int issync)
 522 {
 523         struct nfs_client *clp = NFS_SERVER(inode)->nfs_client;
 524         int err = 0;
 525
 526         if (delegation == NULL)
 527                 return 0;
 528         do {
 529                 if (test_bit(NFS_DELEGATION_REVOKED, &delegation->flags))
 530                         break;
 531                 err = nfs_delegation_claim_opens(inode, &delegation->stateid,
 532                                 delegation->type);
 533                 if (!issync || err != -EAGAIN)
 534                         break;
 535                 /*
 536                  * Guard against state recovery
 537                  */
 538                 err = nfs4_wait_clnt_recover(clp);
 539         } while (err == 0);
 540
 541         if (err) {
 542                 nfs_abort_delegation_return(delegation, clp);
 543                 goto out;
 544         }
 545
 546         err = nfs_do_return_delegation(inode, delegation, issync);
 547 out:
 548         /* Refcount matched in nfs_start_delegation_return_locked() */
 549         nfs_put_delegation(delegation);
 550         return err;
 551 }
 552
 553 static bool nfs_delegation_need_return(struct nfs_delegation *delegation)
 554 {
 555         bool ret = false;
 556
 557         if (test_and_clear_bit(NFS_DELEGATION_RETURN, &delegation->flags))
 558                 ret = true;
 559         else if (test_bit(NFS_DELEGATION_RETURN_IF_CLOSED, &delegation->flags)) {
 560                 struct inode *inode;
 561
 562                 spin_lock(&delegation->lock);
 563                 inode = delegation->inode;
 564                 if (inode && list_empty(&NFS_I(inode)->open_files))
 565                         ret = true;
 566                 spin_unlock(&delegation->lock);
 567         }
 568         if (ret)
 569                 clear_bit(NFS_DELEGATION_RETURN_IF_CLOSED, &delegation->flags);
 570         if (test_bit(NFS_DELEGATION_RETURNING, &delegation->flags) ||
 571             test_bit(NFS_DELEGATION_REVOKED, &delegation->flags))
 572                 ret = false;
 573
 574         return ret;
 575 }
 576
 577 static int nfs_server_return_marked_delegations(struct nfs_server *server,
 578                 void __always_unused *data)
 579 {
 580         struct nfs_delegation *delegation;
 581         struct nfs_delegation *prev;
 582         struct inode *inode;
 583         struct inode *place_holder = NULL;
 584         struct nfs_delegation *place_holder_deleg = NULL;
 585         int err = 0;
 586
 587 restart:
 588         /*
 589          * To avoid quadratic looping we hold a reference
 590          * to an inode place_holder.  Each time we restart, we
 591          * list delegation in the server from the delegations
 592          * of that inode.
 593          * prev is an RCU-protected pointer to a delegation which
 594          * wasn't marked for return and might be a good choice for
 595          * the next place_holder.
 596          */
 597         prev = NULL;
 598         delegation = NULL;
 599         rcu_read_lock();
 600         if (place_holder)
 601                 delegation = rcu_dereference(NFS_I(place_holder)->delegation);
 602         if (!delegation || delegation != place_holder_deleg)
 603                 delegation = list_entry_rcu(server->delegations.next,
 604                                             struct nfs_delegation, super_list);
 605         list_for_each_entry_from_rcu(delegation, &server->delegations, super_list) {
 606                 struct inode *to_put = NULL;
 607
 608                 if (test_bit(NFS_DELEGATION_INODE_FREEING, &delegation->flags))
 609                         continue;
 610                 if (!nfs_delegation_need_return(delegation)) {
 611                         if (nfs4_is_valid_delegation(delegation, 0))
 612                                 prev = delegation;
 613                         continue;
 614                 }
 615
 616                 if (prev) {
 617                         struct inode *tmp = nfs_delegation_grab_inode(prev);
 618                         if (tmp) {
 619                                 to_put = place_holder;
 620                                 place_holder = tmp;
 621                                 place_holder_deleg = prev;
 622                         }
 623                 }
 624
 625                 inode = nfs_delegation_grab_inode(delegation);
 626                 if (inode == NULL) {
 627                         rcu_read_unlock();
 628                         iput(to_put);
 629                         goto restart;
 630                 }
 631                 delegation = nfs_start_delegation_return_locked(NFS_I(inode));
 632                 rcu_read_unlock();
 633
 634                 iput(to_put);
 635
 636                 err = nfs_end_delegation_return(inode, delegation, 0);
 637                 iput(inode);
 638                 cond_resched();
 639                 if (!err)
 640                         goto restart;
 641                 set_bit(NFS4CLNT_DELEGRETURN, &server->nfs_client->cl_state);
 642                 goto out;
 643         }
 644         rcu_read_unlock();
 645 out:
 646         iput(place_holder);
 647         return err;
 648 }
 649
 650 /**
 651  * nfs_client_return_marked_delegations - return previously marked delegations
 652  * @clp: nfs_client to process
 653  *
 654  * Note that this function is designed to be called by the state
 655  * manager thread. For this reason, it cannot flush the dirty data,
 656  * since that could deadlock in case of a state recovery error.
 657  *
 658  * Returns zero on success, or a negative errno value.
 659  */
 660 int nfs_client_return_marked_delegations(struct nfs_client *clp)
 661 {
 662         return nfs_client_for_each_server(clp,
 663                         nfs_server_return_marked_delegations, NULL);
 664 }
 665
 666 /**
 667  * nfs_inode_evict_delegation - return delegation, don't reclaim opens
 668  * @inode: inode to process
 669  *
 670  * Does not protect against delegation reclaims, therefore really only safe
 671  * to be called from nfs4_clear_inode(). Guaranteed to always free
 672  * the delegation structure.
 673  */
 674 void nfs_inode_evict_delegation(struct inode *inode)
 675 {
 676         struct nfs_delegation *delegation;
 677
 678         delegation = nfs_inode_detach_delegation(inode);
 679         if (delegation != NULL) {
 680                 set_bit(NFS_DELEGATION_RETURNING, &delegation->flags);
 681                 set_bit(NFS_DELEGATION_INODE_FREEING, &delegation->flags);
 682                 nfs_do_return_delegation(inode, delegation, 1);
 683                 nfs_free_delegation(delegation);
 684         }
 685 }
 686
 687 /**
 688  * nfs4_inode_return_delegation - synchronously return a delegation
 689  * @inode: inode to process
 690  *
 691  * This routine will always flush any dirty data to disk on the
 692  * assumption that if we need to return the delegation, then
 693  * we should stop caching.
 694  *
 695  * Returns zero on success, or a negative errno value.
 696  */
 697 int nfs4_inode_return_delegation(struct inode *inode)
 698 {
 699         struct nfs_inode *nfsi = NFS_I(inode);
 700         struct nfs_delegation *delegation;
 701         int err = 0;
 702
 703         nfs_wb_all(inode);
 704         delegation = nfs_start_delegation_return(nfsi);
 705         if (delegation != NULL)
 706                 err = nfs_end_delegation_return(inode, delegation, 1);
 707         return err;
 708 }
 709
 710 /**
 711  * nfs4_inode_return_delegation_on_close - asynchronously return a delegation
 712  * @inode: inode to process
 713  *
 714  * This routine is called on file close in order to determine if the
 715  * inode delegation needs to be returned immediately.
 716  */
 717 void nfs4_inode_return_delegation_on_close(struct inode *inode)
 718 {
 719         struct nfs_delegation *delegation;
 720         struct nfs_delegation *ret = NULL;
 721
 722         if (!inode)
 723                 return;
 724         rcu_read_lock();
 725         delegation = nfs4_get_valid_delegation(inode);
 726         if (!delegation)
 727                 goto out;
 728         if (test_bit(NFS_DELEGATION_RETURN_IF_CLOSED, &delegation->flags) ||
 729             atomic_long_read(&nfs_active_delegations) >= nfs_delegation_watermark) {
 730                 spin_lock(&delegation->lock);
 731                 if (delegation->inode &&
 732                     list_empty(&NFS_I(inode)->open_files) &&
 733                     !test_and_set_bit(NFS_DELEGATION_RETURNING, &delegation->flags)) {
 734                         clear_bit(NFS_DELEGATION_RETURN_IF_CLOSED, &delegation->flags);
 735                         /* Refcount matched in nfs_end_delegation_return() */
 736                         ret = nfs_get_delegation(delegation);
 737                 }
 738                 spin_unlock(&delegation->lock);
 739                 if (ret)
 740                         nfs_clear_verifier_delegated(inode);
 741         }
 742 out:
 743         rcu_read_unlock();
 744         nfs_end_delegation_return(inode, ret, 0);
 745 }
 746
 747 /**
 748  * nfs4_inode_make_writeable
 749  * @inode: pointer to inode
 750  *
 751  * Make the inode writeable by returning the delegation if necessary
 752  *
 753  * Returns zero on success, or a negative errno value.
 754  */
 755 int nfs4_inode_make_writeable(struct inode *inode)
 756 {
 757         struct nfs_delegation *delegation;
 758
 759         rcu_read_lock();
 760         delegation = nfs4_get_valid_delegation(inode);
 761         if (delegation == NULL ||
 762             (nfs4_has_session(NFS_SERVER(inode)->nfs_client) &&
 763              (delegation->type & FMODE_WRITE))) {
 764                 rcu_read_unlock();
 765                 return 0;
 766         }
 767         rcu_read_unlock();
 768         return nfs4_inode_return_delegation(inode);
 769 }
 770
 771 static void nfs_mark_return_if_closed_delegation(struct nfs_server *server,
 772                 struct nfs_delegation *delegation)
 773 {
 774         set_bit(NFS_DELEGATION_RETURN_IF_CLOSED, &delegation->flags);
 775         set_bit(NFS4CLNT_DELEGRETURN, &server->nfs_client->cl_state);
 776 }
 777
 778 static void nfs_mark_return_delegation(struct nfs_server *server,
 779                 struct nfs_delegation *delegation)
 780 {
 781         set_bit(NFS_DELEGATION_RETURN, &delegation->flags);
 782         set_bit(NFS4CLNT_DELEGRETURN, &server->nfs_client->cl_state);
 783 }
 784
 785 static bool nfs_server_mark_return_all_delegations(struct nfs_server *server)
 786 {
 787         struct nfs_delegation *delegation;
 788         bool ret = false;
 789
 790         list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
 791                 nfs_mark_return_delegation(server, delegation);
 792                 ret = true;
 793         }
 794         return ret;
 795 }
 796
 797 static void nfs_client_mark_return_all_delegations(struct nfs_client *clp)
 798 {
 799         struct nfs_server *server;
 800
 801         rcu_read_lock();
 802         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
 803                 nfs_server_mark_return_all_delegations(server);
 804         rcu_read_unlock();
 805 }
 806
 807 static void nfs_delegation_run_state_manager(struct nfs_client *clp)
 808 {
 809         if (test_bit(NFS4CLNT_DELEGRETURN, &clp->cl_state))
 810                 nfs4_schedule_state_manager(clp);
 811 }
 812
 813 /**
 814  * nfs_expire_all_delegations
 815  * @clp: client to process
 816  *
 817  */
 818 void nfs_expire_all_delegations(struct nfs_client *clp)
 819 {
 820         nfs_client_mark_return_all_delegations(clp);
 821         nfs_delegation_run_state_manager(clp);
 822 }
 823
 824 /**
 825  * nfs_server_return_all_delegations - return delegations for one superblock
 826  * @server: pointer to nfs_server to process
 827  *
 828  */
 829 void nfs_server_return_all_delegations(struct nfs_server *server)
 830 {
 831         struct nfs_client *clp = server->nfs_client;
 832         bool need_wait;
 833
 834         if (clp == NULL)
 835                 return;
 836
 837         rcu_read_lock();
 838         need_wait = nfs_server_mark_return_all_delegations(server);
 839         rcu_read_unlock();
 840
 841         if (need_wait) {
 842                 nfs4_schedule_state_manager(clp);
 843                 nfs4_wait_clnt_recover(clp);
 844         }
 845 }
 846
 847 static void nfs_mark_return_unused_delegation_types(struct nfs_server *server,
 848                                                  fmode_t flags)
 849 {
 850         struct nfs_delegation *delegation;
 851
 852         list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
 853                 if ((delegation->type == (FMODE_READ|FMODE_WRITE)) && !(flags & FMODE_WRITE))
 854                         continue;
 855                 if (delegation->type & flags)
 856                         nfs_mark_return_if_closed_delegation(server, delegation);
 857         }
 858 }
 859
 860 static void nfs_client_mark_return_unused_delegation_types(struct nfs_client *clp,
 861                                                         fmode_t flags)
 862 {
 863         struct nfs_server *server;
 864
 865         rcu_read_lock();
 866         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
 867                 nfs_mark_return_unused_delegation_types(server, flags);
 868         rcu_read_unlock();
 869 }
 870
 871 static void nfs_revoke_delegation(struct inode *inode,
 872                 const nfs4_stateid *stateid)
 873 {
 874         struct nfs_delegation *delegation;
 875         nfs4_stateid tmp;
 876         bool ret = false;
 877
 878         rcu_read_lock();
 879         delegation = rcu_dereference(NFS_I(inode)->delegation);
 880         if (delegation == NULL)
 881                 goto out;
 882         if (stateid == NULL) {
 883                 nfs4_stateid_copy(&tmp, &delegation->stateid);
 884                 stateid = &tmp;
 885         } else {
 886                 if (!nfs4_stateid_match_other(stateid, &delegation->stateid))
 887                         goto out;
 888                 spin_lock(&delegation->lock);
 889                 if (stateid->seqid) {
 890                         if (nfs4_stateid_is_newer(&delegation->stateid, stateid)) {
 891                                 spin_unlock(&delegation->lock);
 892                                 goto out;
 893                         }
 894                         delegation->stateid.seqid = stateid->seqid;
 895                 }
 896                 spin_unlock(&delegation->lock);
 897         }
 898         nfs_mark_delegation_revoked(delegation);
 899         ret = true;
 900 out:
 901         rcu_read_unlock();
 902         if (ret)
 903                 nfs_inode_find_state_and_recover(inode, stateid);
 904 }
 905
 906 void nfs_remove_bad_delegation(struct inode *inode,
 907                 const nfs4_stateid *stateid)
 908 {
 909         nfs_revoke_delegation(inode, stateid);
 910 }
 911 EXPORT_SYMBOL_GPL(nfs_remove_bad_delegation);
 912
 913 void nfs_delegation_mark_returned(struct inode *inode,
 914                 const nfs4_stateid *stateid)
 915 {
 916         struct nfs_delegation *delegation;
 917
 918         if (!inode)
 919                 return;
 920
 921         rcu_read_lock();
 922         delegation = rcu_dereference(NFS_I(inode)->delegation);
 923         if (!delegation)
 924                 goto out_rcu_unlock;
 925
 926         spin_lock(&delegation->lock);
 927         if (!nfs4_stateid_match_other(stateid, &delegation->stateid))
 928                 goto out_spin_unlock;
 929         if (stateid->seqid) {
 930                 /* If delegation->stateid is newer, dont mark as returned */
 931                 if (nfs4_stateid_is_newer(&delegation->stateid, stateid))
 932                         goto out_clear_returning;
 933                 if (delegation->stateid.seqid != stateid->seqid)
 934                         delegation->stateid.seqid = stateid->seqid;
 935         }
 936
 937         nfs_mark_delegation_revoked(delegation);
 938
 939 out_clear_returning:
 940         clear_bit(NFS_DELEGATION_RETURNING, &delegation->flags);
 941 out_spin_unlock:
 942         spin_unlock(&delegation->lock);
 943 out_rcu_unlock:
 944         rcu_read_unlock();
 945
 946         nfs_inode_find_state_and_recover(inode, stateid);
 947 }
 948
 949 /**
 950  * nfs_expire_unused_delegation_types
 951  * @clp: client to process
 952  * @flags: delegation types to expire
 953  *
 954  */
 955 void nfs_expire_unused_delegation_types(struct nfs_client *clp, fmode_t flags)
 956 {
 957         nfs_client_mark_return_unused_delegation_types(clp, flags);
 958         nfs_delegation_run_state_manager(clp);
 959 }
 960
 961 static void nfs_mark_return_unreferenced_delegations(struct nfs_server *server)
 962 {
 963         struct nfs_delegation *delegation;
 964
 965         list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
 966                 if (test_and_clear_bit(NFS_DELEGATION_REFERENCED, &delegation->flags))
 967                         continue;
 968                 nfs_mark_return_if_closed_delegation(server, delegation);
 969         }
 970 }
 971
 972 /**
 973  * nfs_expire_unreferenced_delegations - Eliminate unused delegations
 974  * @clp: nfs_client to process
 975  *
 976  */
 977 void nfs_expire_unreferenced_delegations(struct nfs_client *clp)
 978 {
 979         struct nfs_server *server;
 980
 981         rcu_read_lock();
 982         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
 983                 nfs_mark_return_unreferenced_delegations(server);
 984         rcu_read_unlock();
 985
 986         nfs_delegation_run_state_manager(clp);
 987 }
 988
 989 /**
 990  * nfs_async_inode_return_delegation - asynchronously return a delegation
 991  * @inode: inode to process
 992  * @stateid: state ID information
 993  *
 994  * Returns zero on success, or a negative errno value.
 995  */
 996 int nfs_async_inode_return_delegation(struct inode *inode,
 997                                       const nfs4_stateid *stateid)
 998 {
 999         struct nfs_server *server = NFS_SERVER(inode);
1000         struct nfs_client *clp = server->nfs_client;
1001         struct nfs_delegation *delegation;
1002
1003         rcu_read_lock();
1004         delegation = nfs4_get_valid_delegation(inode);
1005         if (delegation == NULL)
1006                 goto out_enoent;
1007         if (stateid != NULL &&
1008             !clp->cl_mvops->match_stateid(&delegation->stateid, stateid))
1009                 goto out_enoent;
1010         nfs_mark_return_delegation(server, delegation);
1011         rcu_read_unlock();
1012
1013         nfs_delegation_run_state_manager(clp);
1014         return 0;
1015 out_enoent:
1016         rcu_read_unlock();
1017         return -ENOENT;
1018 }
1019
1020 static struct inode *
1021 nfs_delegation_find_inode_server(struct nfs_server *server,
1022                                  const struct nfs_fh *fhandle)
1023 {
1024         struct nfs_delegation *delegation;
1025         struct super_block *freeme = NULL;
1026         struct inode *res = NULL;
1027
1028         list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
1029                 spin_lock(&delegation->lock);
1030                 if (delegation->inode != NULL &&
1031                     !test_bit(NFS_DELEGATION_REVOKED, &delegation->flags) &&
1032                     nfs_compare_fh(fhandle, &NFS_I(delegation->inode)->fh) == 0) {
1033                         if (nfs_sb_active(server->super)) {
1034                                 freeme = server->super;
1035                                 res = igrab(delegation->inode);
1036                         }
1037                         spin_unlock(&delegation->lock);
1038                         if (res != NULL)
1039                                 return res;
1040                         if (freeme) {
1041                                 rcu_read_unlock();
1042                                 nfs_sb_deactive(freeme);
1043                                 rcu_read_lock();
1044                         }
1045                         return ERR_PTR(-EAGAIN);
1046                 }
1047                 spin_unlock(&delegation->lock);
1048         }
1049         return ERR_PTR(-ENOENT);
1050 }
1051
1052 /**
1053  * nfs_delegation_find_inode - retrieve the inode associated with a delegation
1054  * @clp: client state handle
1055  * @fhandle: filehandle from a delegation recall
1056  *
1057  * Returns pointer to inode matching "fhandle," or NULL if a matching inode
1058  * cannot be found.
1059  */
1060 struct inode *nfs_delegation_find_inode(struct nfs_client *clp,
1061                                         const struct nfs_fh *fhandle)
1062 {
1063         struct nfs_server *server;
1064         struct inode *res;
1065
1066         rcu_read_lock();
1067         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link) {
1068                 res = nfs_delegation_find_inode_server(server, fhandle);
1069                 if (res != ERR_PTR(-ENOENT)) {
1070                         rcu_read_unlock();
1071                         return res;
1072                 }
1073         }
1074         rcu_read_unlock();
1075         return ERR_PTR(-ENOENT);
1076 }
1077
1078 static void nfs_delegation_mark_reclaim_server(struct nfs_server *server)
1079 {
1080         struct nfs_delegation *delegation;
1081
1082         list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
1083                 /*
1084                  * If the delegation may have been admin revoked, then we
1085                  * cannot reclaim it.
1086                  */
1087                 if (test_bit(NFS_DELEGATION_TEST_EXPIRED, &delegation->flags))
1088                         continue;
1089                 set_bit(NFS_DELEGATION_NEED_RECLAIM, &delegation->flags);
1090         }
1091 }
1092
1093 /**
1094  * nfs_delegation_mark_reclaim - mark all delegations as needing to be reclaimed
1095  * @clp: nfs_client to process
1096  *
1097  */
1098 void nfs_delegation_mark_reclaim(struct nfs_client *clp)
1099 {
1100         struct nfs_server *server;
1101
1102         rcu_read_lock();
1103         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
1104                 nfs_delegation_mark_reclaim_server(server);
1105         rcu_read_unlock();
1106 }
1107
1108 static int nfs_server_reap_unclaimed_delegations(struct nfs_server *server,
1109                 void __always_unused *data)
1110 {
1111         struct nfs_delegation *delegation;
1112         struct inode *inode;
1113 restart:
1114         rcu_read_lock();
1115 restart_locked:
1116         list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
1117                 if (test_bit(NFS_DELEGATION_INODE_FREEING,
1118                                         &delegation->flags) ||
1119                     test_bit(NFS_DELEGATION_RETURNING,
1120                                         &delegation->flags) ||
1121                     test_bit(NFS_DELEGATION_NEED_RECLAIM,
1122                                         &delegation->flags) == 0)
1123                         continue;
1124                 inode = nfs_delegation_grab_inode(delegation);
1125                 if (inode == NULL)
1126                         goto restart_locked;
1127                 delegation = nfs_start_delegation_return_locked(NFS_I(inode));
1128                 rcu_read_unlock();
1129                 if (delegation != NULL) {
1130                         if (nfs_detach_delegation(NFS_I(inode), delegation,
1131                                                 server) != NULL)
1132                                 nfs_free_delegation(delegation);
1133                         /* Match nfs_start_delegation_return_locked */
1134                         nfs_put_delegation(delegation);
1135                 }
1136                 iput(inode);
1137                 cond_resched();
1138                 goto restart;
1139         }
1140         rcu_read_unlock();
1141         return 0;
1142 }
1143
1144 /**
1145  * nfs_delegation_reap_unclaimed - reap unclaimed delegations after reboot recovery is done
1146  * @clp: nfs_client to process
1147  *
1148  */
1149 void nfs_delegation_reap_unclaimed(struct nfs_client *clp)
1150 {
1151         nfs_client_for_each_server(clp, nfs_server_reap_unclaimed_delegations,
1152                         NULL);
1153 }
1154
1155 static inline bool nfs4_server_rebooted(const struct nfs_client *clp)
1156 {
1157         return (clp->cl_state & (BIT(NFS4CLNT_CHECK_LEASE) |
1158                                 BIT(NFS4CLNT_LEASE_EXPIRED) |
1159                                 BIT(NFS4CLNT_SESSION_RESET))) != 0;
1160 }
1161
1162 static void nfs_mark_test_expired_delegation(struct nfs_server *server,
1163             struct nfs_delegation *delegation)
1164 {
1165         if (delegation->stateid.type == NFS4_INVALID_STATEID_TYPE)
1166                 return;
1167         clear_bit(NFS_DELEGATION_NEED_RECLAIM, &delegation->flags);
1168         set_bit(NFS_DELEGATION_TEST_EXPIRED, &delegation->flags);
1169         set_bit(NFS4CLNT_DELEGATION_EXPIRED, &server->nfs_client->cl_state);
1170 }
1171
1172 static void nfs_inode_mark_test_expired_delegation(struct nfs_server *server,
1173                 struct inode *inode)
1174 {
1175         struct nfs_delegation *delegation;
1176
1177         rcu_read_lock();
1178         delegation = rcu_dereference(NFS_I(inode)->delegation);
1179         if (delegation)
1180                 nfs_mark_test_expired_delegation(server, delegation);
1181         rcu_read_unlock();
1182
1183 }
1184
1185 static void nfs_delegation_mark_test_expired_server(struct nfs_server *server)
1186 {
1187         struct nfs_delegation *delegation;
1188
1189         list_for_each_entry_rcu(delegation, &server->delegations, super_list)
1190                 nfs_mark_test_expired_delegation(server, delegation);
1191 }
1192
1193 /**
1194  * nfs_mark_test_expired_all_delegations - mark all delegations for testing
1195  * @clp: nfs_client to process
1196  *
1197  * Iterates through all the delegations associated with this server and
1198  * marks them as needing to be checked for validity.
1199  */
1200 void nfs_mark_test_expired_all_delegations(struct nfs_client *clp)
1201 {
1202         struct nfs_server *server;
1203
1204         rcu_read_lock();
1205         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
1206                 nfs_delegation_mark_test_expired_server(server);
1207         rcu_read_unlock();
1208 }
1209
1210 /**
1211  * nfs_test_expired_all_delegations - test all delegations for a client
1212  * @clp: nfs_client to process
1213  *
1214  * Helper for handling "recallable state revoked" status from server.
1215  */
1216 void nfs_test_expired_all_delegations(struct nfs_client *clp)
1217 {
1218         nfs_mark_test_expired_all_delegations(clp);
1219         nfs4_schedule_state_manager(clp);
1220 }
1221
1222 static void
1223 nfs_delegation_test_free_expired(struct inode *inode,
1224                 nfs4_stateid *stateid,
1225                 const struct cred *cred)
1226 {
1227         struct nfs_server *server = NFS_SERVER(inode);
1228         const struct nfs4_minor_version_ops *ops = server->nfs_client->cl_mvops;
1229         int status;
1230
1231         if (!cred)
1232                 return;
1233         status = ops->test_and_free_expired(server, stateid, cred);
1234         if (status == -NFS4ERR_EXPIRED || status == -NFS4ERR_BAD_STATEID)
1235                 nfs_remove_bad_delegation(inode, stateid);
1236 }
1237
1238 static int nfs_server_reap_expired_delegations(struct nfs_server *server,
1239                 void __always_unused *data)
1240 {
1241         struct nfs_delegation *delegation;
1242         struct inode *inode;
1243         const struct cred *cred;
1244         nfs4_stateid stateid;
1245 restart:
1246         rcu_read_lock();
1247 restart_locked:
1248         list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
1249                 if (test_bit(NFS_DELEGATION_INODE_FREEING,
1250                                         &delegation->flags) ||
1251                     test_bit(NFS_DELEGATION_RETURNING,
1252                                         &delegation->flags) ||
1253                     test_bit(NFS_DELEGATION_TEST_EXPIRED,
1254                                         &delegation->flags) == 0)
1255                         continue;
1256                 inode = nfs_delegation_grab_inode(delegation);
1257                 if (inode == NULL)
1258                         goto restart_locked;
1259                 spin_lock(&delegation->lock);
1260                 cred = get_cred_rcu(delegation->cred);
1261                 nfs4_stateid_copy(&stateid, &delegation->stateid);
1262                 spin_unlock(&delegation->lock);
1263                 clear_bit(NFS_DELEGATION_TEST_EXPIRED, &delegation->flags);
1264                 rcu_read_unlock();
1265                 nfs_delegation_test_free_expired(inode, &stateid, cred);
1266                 put_cred(cred);
1267                 if (!nfs4_server_rebooted(server->nfs_client)) {
1268                         iput(inode);
1269                         cond_resched();
1270                         goto restart;
1271                 }
1272                 nfs_inode_mark_test_expired_delegation(server,inode);
1273                 iput(inode);
1274                 return -EAGAIN;
1275         }
1276         rcu_read_unlock();
1277         return 0;
1278 }
1279
1280 /**
1281  * nfs_reap_expired_delegations - reap expired delegations
1282  * @clp: nfs_client to process
1283  *
1284  * Iterates through all the delegations associated with this server and
1285  * checks if they have may have been revoked. This function is usually
1286  * expected to be called in cases where the server may have lost its
1287  * lease.
1288  */
1289 void nfs_reap_expired_delegations(struct nfs_client *clp)
1290 {
1291         nfs_client_for_each_server(clp, nfs_server_reap_expired_delegations,
1292                         NULL);
1293 }
1294
1295 void nfs_inode_find_delegation_state_and_recover(struct inode *inode,
1296                 const nfs4_stateid *stateid)
1297 {
1298         struct nfs_client *clp = NFS_SERVER(inode)->nfs_client;
1299         struct nfs_delegation *delegation;
1300         bool found = false;
1301
1302         rcu_read_lock();
1303         delegation = rcu_dereference(NFS_I(inode)->delegation);
1304         if (delegation &&
1305             nfs4_stateid_match_or_older(&delegation->stateid, stateid) &&
1306             !test_bit(NFS_DELEGATION_REVOKED, &delegation->flags)) {
1307                 nfs_mark_test_expired_delegation(NFS_SERVER(inode), delegation);
1308                 found = true;
1309         }
1310         rcu_read_unlock();
1311         if (found)
1312                 nfs4_schedule_state_manager(clp);
1313 }
1314
1315 /**
1316  * nfs_delegations_present - check for existence of delegations
1317  * @clp: client state handle
1318  *
1319  * Returns one if there are any nfs_delegation structures attached
1320  * to this nfs_client.
1321  */
1322 int nfs_delegations_present(struct nfs_client *clp)
1323 {
1324         struct nfs_server *server;
1325         int ret = 0;
1326
1327         rcu_read_lock();
1328         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
1329                 if (!list_empty(&server->delegations)) {
1330                         ret = 1;
1331                         break;
1332                 }
1333         rcu_read_unlock();
1334         return ret;
1335 }
1336
1337 /**
1338  * nfs4_refresh_delegation_stateid - Update delegation stateid seqid
1339  * @dst: stateid to refresh
1340  * @inode: inode to check
1341  *
1342  * Returns "true" and updates "dst->seqid" * if inode had a delegation
1343  * that matches our delegation stateid. Otherwise "false" is returned.
1344  */
1345 bool nfs4_refresh_delegation_stateid(nfs4_stateid *dst, struct inode *inode)
1346 {
1347         struct nfs_delegation *delegation;
1348         bool ret = false;
1349         if (!inode)
1350                 goto out;
1351
1352         rcu_read_lock();
1353         delegation = rcu_dereference(NFS_I(inode)->delegation);
1354         if (delegation != NULL &&
1355             nfs4_stateid_match_other(dst, &delegation->stateid) &&
1356             nfs4_stateid_is_newer(&delegation->stateid, dst) &&
1357             !test_bit(NFS_DELEGATION_REVOKED, &delegation->flags)) {
1358                 dst->seqid = delegation->stateid.seqid;
1359                 ret = true;
1360         }
1361         rcu_read_unlock();
1362 out:
1363         return ret;
1364 }
1365
1366 /**
1367  * nfs4_copy_delegation_stateid - Copy inode's state ID information
1368  * @inode: inode to check
1369  * @flags: delegation type requirement
1370  * @dst: stateid data structure to fill in
1371  * @cred: optional argument to retrieve credential
1372  *
1373  * Returns "true" and fills in "dst->data" * if inode had a delegation,
1374  * otherwise "false" is returned.
1375  */
1376 bool nfs4_copy_delegation_stateid(struct inode *inode, fmode_t flags,
1377                 nfs4_stateid *dst, const struct cred **cred)
1378 {
1379         struct nfs_inode *nfsi = NFS_I(inode);
1380         struct nfs_delegation *delegation;
1381         bool ret = false;
1382
1383         flags &= FMODE_READ|FMODE_WRITE;
1384         rcu_read_lock();
1385         delegation = rcu_dereference(nfsi->delegation);
1386         if (!delegation)
1387                 goto out;
1388         spin_lock(&delegation->lock);
1389         ret = nfs4_is_valid_delegation(delegation, flags);
1390         if (ret) {
1391                 nfs4_stateid_copy(dst, &delegation->stateid);
1392                 nfs_mark_delegation_referenced(delegation);
1393                 if (cred)
1394                         *cred = get_cred(delegation->cred);
1395         }
1396         spin_unlock(&delegation->lock);
1397 out:
1398         rcu_read_unlock();
1399         return ret;
1400 }
1401
1402 /**
1403  * nfs4_delegation_flush_on_close - Check if we must flush file on close
1404  * @inode: inode to check
1405  *
1406  * This function checks the number of outstanding writes to the file
1407  * against the delegation 'space_limit' field to see if
1408  * the spec requires us to flush the file on close.
1409  */
1410 bool nfs4_delegation_flush_on_close(const struct inode *inode)
1411 {
1412         struct nfs_inode *nfsi = NFS_I(inode);
1413         struct nfs_delegation *delegation;
1414         bool ret = true;
1415
1416         rcu_read_lock();
1417         delegation = rcu_dereference(nfsi->delegation);
1418         if (delegation == NULL || !(delegation->type & FMODE_WRITE))
1419                 goto out;
1420         if (atomic_long_read(&nfsi->nrequests) < delegation->pagemod_limit)
1421                 ret = false;
1422 out:
1423         rcu_read_unlock();
1424         return ret;
1425 }
1426
1427 module_param_named(delegation_watermark, nfs_delegation_watermark, uint, 0644);