fs/nfs/delegation.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * linux/fs/nfs/delegation.c
   4  *
   5  * Copyright (C) 2004 Trond Myklebust
   6  *
   7  * NFS file delegation management
   8  *
   9  */
  10 #include <linux/completion.h>
  11 #include <linux/kthread.h>
  12 #include <linux/module.h>
  13 #include <linux/sched.h>
  14 #include <linux/slab.h>
  15 #include <linux/spinlock.h>
  16 #include <linux/iversion.h>
  17
  18 #include <linux/nfs4.h>
  19 #include <linux/nfs_fs.h>
  20 #include <linux/nfs_xdr.h>
  21
  22 #include "nfs4_fs.h"
  23 #include "nfs4session.h"
  24 #include "delegation.h"
  25 #include "internal.h"
  26 #include "nfs4trace.h"
  27
  28 #define NFS_DEFAULT_DELEGATION_WATERMARK (5000U)
  29
  30 static atomic_long_t nfs_active_delegations;
  31 static unsigned nfs_delegation_watermark = NFS_DEFAULT_DELEGATION_WATERMARK;
  32
  33 static void __nfs_free_delegation(struct nfs_delegation *delegation)
  34 {
  35         put_cred(delegation->cred);
  36         delegation->cred = NULL;
  37         kfree_rcu(delegation, rcu);
  38 }
  39
  40 static void nfs_mark_delegation_revoked(struct nfs_delegation *delegation)
  41 {
  42         if (!test_and_set_bit(NFS_DELEGATION_REVOKED, &delegation->flags)) {
  43                 delegation->stateid.type = NFS4_INVALID_STATEID_TYPE;
  44                 atomic_long_dec(&nfs_active_delegations);
  45                 if (!test_bit(NFS_DELEGATION_RETURNING, &delegation->flags))
  46                         nfs_clear_verifier_delegated(delegation->inode);
  47         }
  48 }
  49
  50 static struct nfs_delegation *nfs_get_delegation(struct nfs_delegation *delegation)
  51 {
  52         refcount_inc(&delegation->refcount);
  53         return delegation;
  54 }
  55
  56 static void nfs_put_delegation(struct nfs_delegation *delegation)
  57 {
  58         if (refcount_dec_and_test(&delegation->refcount))
  59                 __nfs_free_delegation(delegation);
  60 }
  61
  62 static void nfs_free_delegation(struct nfs_delegation *delegation)
  63 {
  64         nfs_mark_delegation_revoked(delegation);
  65         nfs_put_delegation(delegation);
  66 }
  67
  68 /**
  69  * nfs_mark_delegation_referenced - set delegation's REFERENCED flag
  70  * @delegation: delegation to process
  71  *
  72  */
  73 void nfs_mark_delegation_referenced(struct nfs_delegation *delegation)
  74 {
  75         set_bit(NFS_DELEGATION_REFERENCED, &delegation->flags);
  76 }
  77
  78 static void nfs_mark_return_delegation(struct nfs_server *server,
  79                                        struct nfs_delegation *delegation)
  80 {
  81         set_bit(NFS_DELEGATION_RETURN, &delegation->flags);
  82         set_bit(NFS4CLNT_DELEGRETURN, &server->nfs_client->cl_state);
  83 }
  84
  85 static bool
  86 nfs4_is_valid_delegation(const struct nfs_delegation *delegation,
  87                 fmode_t flags)
  88 {
  89         if (delegation != NULL && (delegation->type & flags) == flags &&
  90             !test_bit(NFS_DELEGATION_REVOKED, &delegation->flags) &&
  91             !test_bit(NFS_DELEGATION_RETURNING, &delegation->flags))
  92                 return true;
  93         return false;
  94 }
  95
  96 struct nfs_delegation *nfs4_get_valid_delegation(const struct inode *inode)
  97 {
  98         struct nfs_delegation *delegation;
  99
 100         delegation = rcu_dereference(NFS_I(inode)->delegation);
 101         if (nfs4_is_valid_delegation(delegation, 0))
 102                 return delegation;
 103         return NULL;
 104 }
 105
 106 static int
 107 nfs4_do_check_delegation(struct inode *inode, fmode_t flags, bool mark)
 108 {
 109         struct nfs_delegation *delegation;
 110         int ret = 0;
 111
 112         flags &= FMODE_READ|FMODE_WRITE;
 113         rcu_read_lock();
 114         delegation = rcu_dereference(NFS_I(inode)->delegation);
 115         if (nfs4_is_valid_delegation(delegation, flags)) {
 116                 if (mark)
 117                         nfs_mark_delegation_referenced(delegation);
 118                 ret = 1;
 119         }
 120         rcu_read_unlock();
 121         return ret;
 122 }
 123 /**
 124  * nfs4_have_delegation - check if inode has a delegation, mark it
 125  * NFS_DELEGATION_REFERENCED if there is one.
 126  * @inode: inode to check
 127  * @flags: delegation types to check for
 128  *
 129  * Returns one if inode has the indicated delegation, otherwise zero.
 130  */
 131 int nfs4_have_delegation(struct inode *inode, fmode_t flags)
 132 {
 133         return nfs4_do_check_delegation(inode, flags, true);
 134 }
 135
 136 /*
 137  * nfs4_check_delegation - check if inode has a delegation, do not mark
 138  * NFS_DELEGATION_REFERENCED if it has one.
 139  */
 140 int nfs4_check_delegation(struct inode *inode, fmode_t flags)
 141 {
 142         return nfs4_do_check_delegation(inode, flags, false);
 143 }
 144
 145 static int nfs_delegation_claim_locks(struct nfs4_state *state, const nfs4_stateid *stateid)
 146 {
 147         struct inode *inode = state->inode;
 148         struct file_lock *fl;
 149         struct file_lock_context *flctx = locks_inode_context(inode);
 150         struct list_head *list;
 151         int status = 0;
 152
 153         if (flctx == NULL)
 154                 goto out;
 155
 156         list = &flctx->flc_posix;
 157         spin_lock(&flctx->flc_lock);
 158 restart:
 159         for_each_file_lock(fl, list) {
 160                 if (nfs_file_open_context(fl->c.flc_file)->state != state)
 161                         continue;
 162                 spin_unlock(&flctx->flc_lock);
 163                 status = nfs4_lock_delegation_recall(fl, state, stateid);
 164                 if (status < 0)
 165                         goto out;
 166                 spin_lock(&flctx->flc_lock);
 167         }
 168         if (list == &flctx->flc_posix) {
 169                 list = &flctx->flc_flock;
 170                 goto restart;
 171         }
 172         spin_unlock(&flctx->flc_lock);
 173 out:
 174         return status;
 175 }
 176
 177 static int nfs_delegation_claim_opens(struct inode *inode,
 178                 const nfs4_stateid *stateid, fmode_t type)
 179 {
 180         struct nfs_inode *nfsi = NFS_I(inode);
 181         struct nfs_open_context *ctx;
 182         struct nfs4_state_owner *sp;
 183         struct nfs4_state *state;
 184         unsigned int seq;
 185         int err;
 186
 187 again:
 188         rcu_read_lock();
 189         list_for_each_entry_rcu(ctx, &nfsi->open_files, list) {
 190                 state = ctx->state;
 191                 if (state == NULL)
 192                         continue;
 193                 if (!test_bit(NFS_DELEGATED_STATE, &state->flags))
 194                         continue;
 195                 if (!nfs4_valid_open_stateid(state))
 196                         continue;
 197                 if (!nfs4_stateid_match(&state->stateid, stateid))
 198                         continue;
 199                 if (!get_nfs_open_context(ctx))
 200                         continue;
 201                 rcu_read_unlock();
 202                 sp = state->owner;
 203                 /* Block nfs4_proc_unlck */
 204                 mutex_lock(&sp->so_delegreturn_mutex);
 205                 seq = raw_seqcount_begin(&sp->so_reclaim_seqcount);
 206                 err = nfs4_open_delegation_recall(ctx, state, stateid);
 207                 if (!err)
 208                         err = nfs_delegation_claim_locks(state, stateid);
 209                 if (!err && read_seqcount_retry(&sp->so_reclaim_seqcount, seq))
 210                         err = -EAGAIN;
 211                 mutex_unlock(&sp->so_delegreturn_mutex);
 212                 put_nfs_open_context(ctx);
 213                 if (err != 0)
 214                         return err;
 215                 goto again;
 216         }
 217         rcu_read_unlock();
 218         return 0;
 219 }
 220
 221 /**
 222  * nfs_inode_reclaim_delegation - process a delegation reclaim request
 223  * @inode: inode to process
 224  * @cred: credential to use for request
 225  * @type: delegation type
 226  * @stateid: delegation stateid
 227  * @pagemod_limit: write delegation "space_limit"
 228  *
 229  */
 230 void nfs_inode_reclaim_delegation(struct inode *inode, const struct cred *cred,
 231                                   fmode_t type, const nfs4_stateid *stateid,
 232                                   unsigned long pagemod_limit)
 233 {
 234         struct nfs_delegation *delegation;
 235         const struct cred *oldcred = NULL;
 236
 237         rcu_read_lock();
 238         delegation = rcu_dereference(NFS_I(inode)->delegation);
 239         if (delegation != NULL) {
 240                 spin_lock(&delegation->lock);
 241                 nfs4_stateid_copy(&delegation->stateid, stateid);
 242                 delegation->type = type;
 243                 delegation->pagemod_limit = pagemod_limit;
 244                 oldcred = delegation->cred;
 245                 delegation->cred = get_cred(cred);
 246                 clear_bit(NFS_DELEGATION_NEED_RECLAIM, &delegation->flags);
 247                 if (test_and_clear_bit(NFS_DELEGATION_REVOKED,
 248                                        &delegation->flags))
 249                         atomic_long_inc(&nfs_active_delegations);
 250                 spin_unlock(&delegation->lock);
 251                 rcu_read_unlock();
 252                 put_cred(oldcred);
 253                 trace_nfs4_reclaim_delegation(inode, type);
 254         } else {
 255                 rcu_read_unlock();
 256                 nfs_inode_set_delegation(inode, cred, type, stateid,
 257                                          pagemod_limit);
 258         }
 259 }
 260
 261 static int nfs_do_return_delegation(struct inode *inode, struct nfs_delegation *delegation, int issync)
 262 {
 263         const struct cred *cred;
 264         int res = 0;
 265
 266         if (!test_bit(NFS_DELEGATION_REVOKED, &delegation->flags)) {
 267                 spin_lock(&delegation->lock);
 268                 cred = get_cred(delegation->cred);
 269                 spin_unlock(&delegation->lock);
 270                 res = nfs4_proc_delegreturn(inode, cred,
 271                                 &delegation->stateid,
 272                                 issync);
 273                 put_cred(cred);
 274         }
 275         return res;
 276 }
 277
 278 static struct inode *nfs_delegation_grab_inode(struct nfs_delegation *delegation)
 279 {
 280         struct inode *inode = NULL;
 281
 282         spin_lock(&delegation->lock);
 283         if (delegation->inode != NULL)
 284                 inode = igrab(delegation->inode);
 285         if (!inode)
 286                 set_bit(NFS_DELEGATION_INODE_FREEING, &delegation->flags);
 287         spin_unlock(&delegation->lock);
 288         return inode;
 289 }
 290
 291 static struct nfs_delegation *
 292 nfs_start_delegation_return_locked(struct nfs_inode *nfsi)
 293 {
 294         struct nfs_delegation *ret = NULL;
 295         struct nfs_delegation *delegation = rcu_dereference(nfsi->delegation);
 296
 297         if (delegation == NULL)
 298                 goto out;
 299         spin_lock(&delegation->lock);
 300         if (!test_and_set_bit(NFS_DELEGATION_RETURNING, &delegation->flags)) {
 301                 clear_bit(NFS_DELEGATION_RETURN_DELAYED, &delegation->flags);
 302                 /* Refcount matched in nfs_end_delegation_return() */
 303                 ret = nfs_get_delegation(delegation);
 304         }
 305         spin_unlock(&delegation->lock);
 306         if (ret)
 307                 nfs_clear_verifier_delegated(&nfsi->vfs_inode);
 308 out:
 309         return ret;
 310 }
 311
 312 static struct nfs_delegation *
 313 nfs_start_delegation_return(struct nfs_inode *nfsi)
 314 {
 315         struct nfs_delegation *delegation;
 316
 317         rcu_read_lock();
 318         delegation = nfs_start_delegation_return_locked(nfsi);
 319         rcu_read_unlock();
 320         return delegation;
 321 }
 322
 323 static void nfs_abort_delegation_return(struct nfs_delegation *delegation,
 324                                         struct nfs_client *clp, int err)
 325 {
 326
 327         spin_lock(&delegation->lock);
 328         clear_bit(NFS_DELEGATION_RETURNING, &delegation->flags);
 329         if (err == -EAGAIN) {
 330                 set_bit(NFS_DELEGATION_RETURN_DELAYED, &delegation->flags);
 331                 set_bit(NFS4CLNT_DELEGRETURN_DELAYED, &clp->cl_state);
 332         }
 333         spin_unlock(&delegation->lock);
 334 }
 335
 336 static struct nfs_delegation *
 337 nfs_detach_delegation_locked(struct nfs_inode *nfsi,
 338                 struct nfs_delegation *delegation,
 339                 struct nfs_client *clp)
 340 {
 341         struct nfs_delegation *deleg_cur =
 342                 rcu_dereference_protected(nfsi->delegation,
 343                                 lockdep_is_held(&clp->cl_lock));
 344
 345         if (deleg_cur == NULL || delegation != deleg_cur)
 346                 return NULL;
 347
 348         spin_lock(&delegation->lock);
 349         if (!delegation->inode) {
 350                 spin_unlock(&delegation->lock);
 351                 return NULL;
 352         }
 353         list_del_rcu(&delegation->super_list);
 354         delegation->inode = NULL;
 355         rcu_assign_pointer(nfsi->delegation, NULL);
 356         spin_unlock(&delegation->lock);
 357         return delegation;
 358 }
 359
 360 static struct nfs_delegation *nfs_detach_delegation(struct nfs_inode *nfsi,
 361                 struct nfs_delegation *delegation,
 362                 struct nfs_server *server)
 363 {
 364         struct nfs_client *clp = server->nfs_client;
 365
 366         spin_lock(&clp->cl_lock);
 367         delegation = nfs_detach_delegation_locked(nfsi, delegation, clp);
 368         spin_unlock(&clp->cl_lock);
 369         return delegation;
 370 }
 371
 372 static struct nfs_delegation *
 373 nfs_inode_detach_delegation(struct inode *inode)
 374 {
 375         struct nfs_inode *nfsi = NFS_I(inode);
 376         struct nfs_server *server = NFS_SERVER(inode);
 377         struct nfs_delegation *delegation;
 378
 379         rcu_read_lock();
 380         delegation = rcu_dereference(nfsi->delegation);
 381         if (delegation != NULL)
 382                 delegation = nfs_detach_delegation(nfsi, delegation, server);
 383         rcu_read_unlock();
 384         return delegation;
 385 }
 386
 387 static void
 388 nfs_update_delegation_cred(struct nfs_delegation *delegation,
 389                 const struct cred *cred)
 390 {
 391         const struct cred *old;
 392
 393         if (cred_fscmp(delegation->cred, cred) != 0) {
 394                 old = xchg(&delegation->cred, get_cred(cred));
 395                 put_cred(old);
 396         }
 397 }
 398
 399 static void
 400 nfs_update_inplace_delegation(struct nfs_delegation *delegation,
 401                 const struct nfs_delegation *update)
 402 {
 403         if (nfs4_stateid_is_newer(&update->stateid, &delegation->stateid)) {
 404                 delegation->stateid.seqid = update->stateid.seqid;
 405                 smp_wmb();
 406                 delegation->type = update->type;
 407                 delegation->pagemod_limit = update->pagemod_limit;
 408                 if (test_bit(NFS_DELEGATION_REVOKED, &delegation->flags)) {
 409                         delegation->change_attr = update->change_attr;
 410                         nfs_update_delegation_cred(delegation, update->cred);
 411                         /* smp_mb__before_atomic() is implicit due to xchg() */
 412                         clear_bit(NFS_DELEGATION_REVOKED, &delegation->flags);
 413                         atomic_long_inc(&nfs_active_delegations);
 414                 }
 415         }
 416 }
 417
 418 /**
 419  * nfs_inode_set_delegation - set up a delegation on an inode
 420  * @inode: inode to which delegation applies
 421  * @cred: cred to use for subsequent delegation processing
 422  * @type: delegation type
 423  * @stateid: delegation stateid
 424  * @pagemod_limit: write delegation "space_limit"
 425  *
 426  * Returns zero on success, or a negative errno value.
 427  */
 428 int nfs_inode_set_delegation(struct inode *inode, const struct cred *cred,
 429                                   fmode_t type,
 430                                   const nfs4_stateid *stateid,
 431                                   unsigned long pagemod_limit)
 432 {
 433         struct nfs_server *server = NFS_SERVER(inode);
 434         struct nfs_client *clp = server->nfs_client;
 435         struct nfs_inode *nfsi = NFS_I(inode);
 436         struct nfs_delegation *delegation, *old_delegation;
 437         struct nfs_delegation *freeme = NULL;
 438         int status = 0;
 439
 440         delegation = kmalloc(sizeof(*delegation), GFP_KERNEL_ACCOUNT);
 441         if (delegation == NULL)
 442                 return -ENOMEM;
 443         nfs4_stateid_copy(&delegation->stateid, stateid);
 444         refcount_set(&delegation->refcount, 1);
 445         delegation->type = type;
 446         delegation->pagemod_limit = pagemod_limit;
 447         delegation->change_attr = inode_peek_iversion_raw(inode);
 448         delegation->cred = get_cred(cred);
 449         delegation->inode = inode;
 450         delegation->flags = 1<<NFS_DELEGATION_REFERENCED;
 451         delegation->test_gen = 0;
 452         spin_lock_init(&delegation->lock);
 453
 454         spin_lock(&clp->cl_lock);
 455         old_delegation = rcu_dereference_protected(nfsi->delegation,
 456                                         lockdep_is_held(&clp->cl_lock));
 457         if (old_delegation == NULL)
 458                 goto add_new;
 459         /* Is this an update of the existing delegation? */
 460         if (nfs4_stateid_match_other(&old_delegation->stateid,
 461                                 &delegation->stateid)) {
 462                 spin_lock(&old_delegation->lock);
 463                 nfs_update_inplace_delegation(old_delegation,
 464                                 delegation);
 465                 spin_unlock(&old_delegation->lock);
 466                 goto out;
 467         }
 468         if (!test_bit(NFS_DELEGATION_REVOKED, &old_delegation->flags)) {
 469                 /*
 470                  * Deal with broken servers that hand out two
 471                  * delegations for the same file.
 472                  * Allow for upgrades to a WRITE delegation, but
 473                  * nothing else.
 474                  */
 475                 dfprintk(FILE, "%s: server %s handed out "
 476                                 "a duplicate delegation!\n",
 477                                 __func__, clp->cl_hostname);
 478                 if (delegation->type == old_delegation->type ||
 479                     !(delegation->type & FMODE_WRITE)) {
 480                         freeme = delegation;
 481                         delegation = NULL;
 482                         goto out;
 483                 }
 484                 if (test_and_set_bit(NFS_DELEGATION_RETURNING,
 485                                         &old_delegation->flags))
 486                         goto out;
 487         }
 488         freeme = nfs_detach_delegation_locked(nfsi, old_delegation, clp);
 489         if (freeme == NULL)
 490                 goto out;
 491 add_new:
 492         /*
 493          * If we didn't revalidate the change attribute before setting
 494          * the delegation, then pre-emptively ask for a full attribute
 495          * cache revalidation.
 496          */
 497         spin_lock(&inode->i_lock);
 498         if (NFS_I(inode)->cache_validity & NFS_INO_INVALID_CHANGE)
 499                 nfs_set_cache_invalid(inode,
 500                         NFS_INO_INVALID_ATIME | NFS_INO_INVALID_CTIME |
 501                         NFS_INO_INVALID_MTIME | NFS_INO_INVALID_SIZE |
 502                         NFS_INO_INVALID_BLOCKS | NFS_INO_INVALID_NLINK |
 503                         NFS_INO_INVALID_OTHER | NFS_INO_INVALID_DATA |
 504                         NFS_INO_INVALID_ACCESS | NFS_INO_INVALID_ACL |
 505                         NFS_INO_INVALID_XATTR);
 506         spin_unlock(&inode->i_lock);
 507
 508         list_add_tail_rcu(&delegation->super_list, &server->delegations);
 509         rcu_assign_pointer(nfsi->delegation, delegation);
 510         delegation = NULL;
 511
 512         atomic_long_inc(&nfs_active_delegations);
 513
 514         trace_nfs4_set_delegation(inode, type);
 515 out:
 516         spin_unlock(&clp->cl_lock);
 517         if (delegation != NULL)
 518                 __nfs_free_delegation(delegation);
 519         if (freeme != NULL) {
 520                 nfs_do_return_delegation(inode, freeme, 0);
 521                 nfs_free_delegation(freeme);
 522         }
 523         return status;
 524 }
 525
 526 /*
 527  * Basic procedure for returning a delegation to the server
 528  */
 529 static int nfs_end_delegation_return(struct inode *inode, struct nfs_delegation *delegation, int issync)
 530 {
 531         struct nfs_client *clp = NFS_SERVER(inode)->nfs_client;
 532         unsigned int mode = O_WRONLY | O_RDWR;
 533         int err = 0;
 534
 535         if (delegation == NULL)
 536                 return 0;
 537
 538         if (!issync)
 539                 mode |= O_NONBLOCK;
 540         /* Recall of any remaining application leases */
 541         err = break_lease(inode, mode);
 542
 543         while (err == 0) {
 544                 if (test_bit(NFS_DELEGATION_REVOKED, &delegation->flags))
 545                         break;
 546                 err = nfs_delegation_claim_opens(inode, &delegation->stateid,
 547                                 delegation->type);
 548                 if (!issync || err != -EAGAIN)
 549                         break;
 550                 /*
 551                  * Guard against state recovery
 552                  */
 553                 err = nfs4_wait_clnt_recover(clp);
 554         }
 555
 556         if (err) {
 557                 nfs_abort_delegation_return(delegation, clp, err);
 558                 goto out;
 559         }
 560
 561         err = nfs_do_return_delegation(inode, delegation, issync);
 562 out:
 563         /* Refcount matched in nfs_start_delegation_return_locked() */
 564         nfs_put_delegation(delegation);
 565         return err;
 566 }
 567
 568 static bool nfs_delegation_need_return(struct nfs_delegation *delegation)
 569 {
 570         bool ret = false;
 571
 572         if (test_and_clear_bit(NFS_DELEGATION_RETURN, &delegation->flags))
 573                 ret = true;
 574         else if (test_bit(NFS_DELEGATION_RETURN_IF_CLOSED, &delegation->flags)) {
 575                 struct inode *inode;
 576
 577                 spin_lock(&delegation->lock);
 578                 inode = delegation->inode;
 579                 if (inode && list_empty(&NFS_I(inode)->open_files))
 580                         ret = true;
 581                 spin_unlock(&delegation->lock);
 582         }
 583         if (ret)
 584                 clear_bit(NFS_DELEGATION_RETURN_IF_CLOSED, &delegation->flags);
 585         if (test_bit(NFS_DELEGATION_RETURNING, &delegation->flags) ||
 586             test_bit(NFS_DELEGATION_RETURN_DELAYED, &delegation->flags) ||
 587             test_bit(NFS_DELEGATION_REVOKED, &delegation->flags))
 588                 ret = false;
 589
 590         return ret;
 591 }
 592
 593 static int nfs_server_return_marked_delegations(struct nfs_server *server,
 594                 void __always_unused *data)
 595 {
 596         struct nfs_delegation *delegation;
 597         struct nfs_delegation *prev;
 598         struct inode *inode;
 599         struct inode *place_holder = NULL;
 600         struct nfs_delegation *place_holder_deleg = NULL;
 601         int err = 0;
 602
 603 restart:
 604         /*
 605          * To avoid quadratic looping we hold a reference
 606          * to an inode place_holder.  Each time we restart, we
 607          * list delegation in the server from the delegations
 608          * of that inode.
 609          * prev is an RCU-protected pointer to a delegation which
 610          * wasn't marked for return and might be a good choice for
 611          * the next place_holder.
 612          */
 613         prev = NULL;
 614         delegation = NULL;
 615         rcu_read_lock();
 616         if (place_holder)
 617                 delegation = rcu_dereference(NFS_I(place_holder)->delegation);
 618         if (!delegation || delegation != place_holder_deleg)
 619                 delegation = list_entry_rcu(server->delegations.next,
 620                                             struct nfs_delegation, super_list);
 621         list_for_each_entry_from_rcu(delegation, &server->delegations, super_list) {
 622                 struct inode *to_put = NULL;
 623
 624                 if (test_bit(NFS_DELEGATION_INODE_FREEING, &delegation->flags))
 625                         continue;
 626                 if (!nfs_delegation_need_return(delegation)) {
 627                         if (nfs4_is_valid_delegation(delegation, 0))
 628                                 prev = delegation;
 629                         continue;
 630                 }
 631
 632                 if (prev) {
 633                         struct inode *tmp = nfs_delegation_grab_inode(prev);
 634                         if (tmp) {
 635                                 to_put = place_holder;
 636                                 place_holder = tmp;
 637                                 place_holder_deleg = prev;
 638                         }
 639                 }
 640
 641                 inode = nfs_delegation_grab_inode(delegation);
 642                 if (inode == NULL) {
 643                         rcu_read_unlock();
 644                         iput(to_put);
 645                         goto restart;
 646                 }
 647                 delegation = nfs_start_delegation_return_locked(NFS_I(inode));
 648                 rcu_read_unlock();
 649
 650                 iput(to_put);
 651
 652                 err = nfs_end_delegation_return(inode, delegation, 0);
 653                 iput(inode);
 654                 cond_resched();
 655                 if (!err)
 656                         goto restart;
 657                 set_bit(NFS4CLNT_DELEGRETURN, &server->nfs_client->cl_state);
 658                 goto out;
 659         }
 660         rcu_read_unlock();
 661 out:
 662         iput(place_holder);
 663         return err;
 664 }
 665
 666 static bool nfs_server_clear_delayed_delegations(struct nfs_server *server)
 667 {
 668         struct nfs_delegation *d;
 669         bool ret = false;
 670
 671         list_for_each_entry_rcu (d, &server->delegations, super_list) {
 672                 if (!test_bit(NFS_DELEGATION_RETURN_DELAYED, &d->flags))
 673                         continue;
 674                 nfs_mark_return_delegation(server, d);
 675                 clear_bit(NFS_DELEGATION_RETURN_DELAYED, &d->flags);
 676                 ret = true;
 677         }
 678         return ret;
 679 }
 680
 681 static bool nfs_client_clear_delayed_delegations(struct nfs_client *clp)
 682 {
 683         struct nfs_server *server;
 684         bool ret = false;
 685
 686         if (!test_and_clear_bit(NFS4CLNT_DELEGRETURN_DELAYED, &clp->cl_state))
 687                 goto out;
 688         rcu_read_lock();
 689         list_for_each_entry_rcu (server, &clp->cl_superblocks, client_link) {
 690                 if (nfs_server_clear_delayed_delegations(server))
 691                         ret = true;
 692         }
 693         rcu_read_unlock();
 694 out:
 695         return ret;
 696 }
 697
 698 /**
 699  * nfs_client_return_marked_delegations - return previously marked delegations
 700  * @clp: nfs_client to process
 701  *
 702  * Note that this function is designed to be called by the state
 703  * manager thread. For this reason, it cannot flush the dirty data,
 704  * since that could deadlock in case of a state recovery error.
 705  *
 706  * Returns zero on success, or a negative errno value.
 707  */
 708 int nfs_client_return_marked_delegations(struct nfs_client *clp)
 709 {
 710         int err = nfs_client_for_each_server(
 711                 clp, nfs_server_return_marked_delegations, NULL);
 712         if (err)
 713                 return err;
 714         /* If a return was delayed, sleep to prevent hard looping */
 715         if (nfs_client_clear_delayed_delegations(clp))
 716                 ssleep(1);
 717         return 0;
 718 }
 719
 720 /**
 721  * nfs_inode_evict_delegation - return delegation, don't reclaim opens
 722  * @inode: inode to process
 723  *
 724  * Does not protect against delegation reclaims, therefore really only safe
 725  * to be called from nfs4_clear_inode(). Guaranteed to always free
 726  * the delegation structure.
 727  */
 728 void nfs_inode_evict_delegation(struct inode *inode)
 729 {
 730         struct nfs_delegation *delegation;
 731
 732         delegation = nfs_inode_detach_delegation(inode);
 733         if (delegation != NULL) {
 734                 set_bit(NFS_DELEGATION_RETURNING, &delegation->flags);
 735                 set_bit(NFS_DELEGATION_INODE_FREEING, &delegation->flags);
 736                 nfs_do_return_delegation(inode, delegation, 1);
 737                 nfs_free_delegation(delegation);
 738         }
 739 }
 740
 741 /**
 742  * nfs4_inode_return_delegation - synchronously return a delegation
 743  * @inode: inode to process
 744  *
 745  * This routine will always flush any dirty data to disk on the
 746  * assumption that if we need to return the delegation, then
 747  * we should stop caching.
 748  *
 749  * Returns zero on success, or a negative errno value.
 750  */
 751 int nfs4_inode_return_delegation(struct inode *inode)
 752 {
 753         struct nfs_inode *nfsi = NFS_I(inode);
 754         struct nfs_delegation *delegation;
 755
 756         delegation = nfs_start_delegation_return(nfsi);
 757         if (delegation != NULL) {
 758                 /* Synchronous recall of any application leases */
 759                 break_lease(inode, O_WRONLY | O_RDWR);
 760                 if (S_ISREG(inode->i_mode))
 761                         nfs_wb_all(inode);
 762                 return nfs_end_delegation_return(inode, delegation, 1);
 763         }
 764         return 0;
 765 }
 766
 767 /**
 768  * nfs4_inode_return_delegation_on_close - asynchronously return a delegation
 769  * @inode: inode to process
 770  *
 771  * This routine is called on file close in order to determine if the
 772  * inode delegation needs to be returned immediately.
 773  */
 774 void nfs4_inode_return_delegation_on_close(struct inode *inode)
 775 {
 776         struct nfs_delegation *delegation;
 777         struct nfs_delegation *ret = NULL;
 778
 779         if (!inode)
 780                 return;
 781         rcu_read_lock();
 782         delegation = nfs4_get_valid_delegation(inode);
 783         if (!delegation)
 784                 goto out;
 785         if (test_bit(NFS_DELEGATION_RETURN_IF_CLOSED, &delegation->flags) ||
 786             atomic_long_read(&nfs_active_delegations) >= nfs_delegation_watermark) {
 787                 spin_lock(&delegation->lock);
 788                 if (delegation->inode &&
 789                     list_empty(&NFS_I(inode)->open_files) &&
 790                     !test_and_set_bit(NFS_DELEGATION_RETURNING, &delegation->flags)) {
 791                         clear_bit(NFS_DELEGATION_RETURN_IF_CLOSED, &delegation->flags);
 792                         /* Refcount matched in nfs_end_delegation_return() */
 793                         ret = nfs_get_delegation(delegation);
 794                 }
 795                 spin_unlock(&delegation->lock);
 796                 if (ret)
 797                         nfs_clear_verifier_delegated(inode);
 798         }
 799 out:
 800         rcu_read_unlock();
 801         nfs_end_delegation_return(inode, ret, 0);
 802 }
 803
 804 /**
 805  * nfs4_inode_make_writeable
 806  * @inode: pointer to inode
 807  *
 808  * Make the inode writeable by returning the delegation if necessary
 809  *
 810  * Returns zero on success, or a negative errno value.
 811  */
 812 int nfs4_inode_make_writeable(struct inode *inode)
 813 {
 814         struct nfs_delegation *delegation;
 815
 816         rcu_read_lock();
 817         delegation = nfs4_get_valid_delegation(inode);
 818         if (delegation == NULL ||
 819             (nfs4_has_session(NFS_SERVER(inode)->nfs_client) &&
 820              (delegation->type & FMODE_WRITE))) {
 821                 rcu_read_unlock();
 822                 return 0;
 823         }
 824         rcu_read_unlock();
 825         return nfs4_inode_return_delegation(inode);
 826 }
 827
 828 static void nfs_mark_return_if_closed_delegation(struct nfs_server *server,
 829                 struct nfs_delegation *delegation)
 830 {
 831         set_bit(NFS_DELEGATION_RETURN_IF_CLOSED, &delegation->flags);
 832         set_bit(NFS4CLNT_DELEGRETURN, &server->nfs_client->cl_state);
 833 }
 834
 835 static bool nfs_server_mark_return_all_delegations(struct nfs_server *server)
 836 {
 837         struct nfs_delegation *delegation;
 838         bool ret = false;
 839
 840         list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
 841                 nfs_mark_return_delegation(server, delegation);
 842                 ret = true;
 843         }
 844         return ret;
 845 }
 846
 847 static void nfs_client_mark_return_all_delegations(struct nfs_client *clp)
 848 {
 849         struct nfs_server *server;
 850
 851         rcu_read_lock();
 852         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
 853                 nfs_server_mark_return_all_delegations(server);
 854         rcu_read_unlock();
 855 }
 856
 857 static void nfs_delegation_run_state_manager(struct nfs_client *clp)
 858 {
 859         if (test_bit(NFS4CLNT_DELEGRETURN, &clp->cl_state))
 860                 nfs4_schedule_state_manager(clp);
 861 }
 862
 863 /**
 864  * nfs_expire_all_delegations
 865  * @clp: client to process
 866  *
 867  */
 868 void nfs_expire_all_delegations(struct nfs_client *clp)
 869 {
 870         nfs_client_mark_return_all_delegations(clp);
 871         nfs_delegation_run_state_manager(clp);
 872 }
 873
 874 /**
 875  * nfs_server_return_all_delegations - return delegations for one superblock
 876  * @server: pointer to nfs_server to process
 877  *
 878  */
 879 void nfs_server_return_all_delegations(struct nfs_server *server)
 880 {
 881         struct nfs_client *clp = server->nfs_client;
 882         bool need_wait;
 883
 884         if (clp == NULL)
 885                 return;
 886
 887         rcu_read_lock();
 888         need_wait = nfs_server_mark_return_all_delegations(server);
 889         rcu_read_unlock();
 890
 891         if (need_wait) {
 892                 nfs4_schedule_state_manager(clp);
 893                 nfs4_wait_clnt_recover(clp);
 894         }
 895 }
 896
 897 static void nfs_mark_return_unused_delegation_types(struct nfs_server *server,
 898                                                  fmode_t flags)
 899 {
 900         struct nfs_delegation *delegation;
 901
 902         list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
 903                 if ((delegation->type == (FMODE_READ|FMODE_WRITE)) && !(flags & FMODE_WRITE))
 904                         continue;
 905                 if (delegation->type & flags)
 906                         nfs_mark_return_if_closed_delegation(server, delegation);
 907         }
 908 }
 909
 910 static void nfs_client_mark_return_unused_delegation_types(struct nfs_client *clp,
 911                                                         fmode_t flags)
 912 {
 913         struct nfs_server *server;
 914
 915         rcu_read_lock();
 916         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
 917                 nfs_mark_return_unused_delegation_types(server, flags);
 918         rcu_read_unlock();
 919 }
 920
 921 static void nfs_revoke_delegation(struct inode *inode,
 922                 const nfs4_stateid *stateid)
 923 {
 924         struct nfs_delegation *delegation;
 925         nfs4_stateid tmp;
 926         bool ret = false;
 927
 928         rcu_read_lock();
 929         delegation = rcu_dereference(NFS_I(inode)->delegation);
 930         if (delegation == NULL)
 931                 goto out;
 932         if (stateid == NULL) {
 933                 nfs4_stateid_copy(&tmp, &delegation->stateid);
 934                 stateid = &tmp;
 935         } else {
 936                 if (!nfs4_stateid_match_other(stateid, &delegation->stateid))
 937                         goto out;
 938                 spin_lock(&delegation->lock);
 939                 if (stateid->seqid) {
 940                         if (nfs4_stateid_is_newer(&delegation->stateid, stateid)) {
 941                                 spin_unlock(&delegation->lock);
 942                                 goto out;
 943                         }
 944                         delegation->stateid.seqid = stateid->seqid;
 945                 }
 946                 spin_unlock(&delegation->lock);
 947         }
 948         nfs_mark_delegation_revoked(delegation);
 949         ret = true;
 950 out:
 951         rcu_read_unlock();
 952         if (ret)
 953                 nfs_inode_find_state_and_recover(inode, stateid);
 954 }
 955
 956 void nfs_remove_bad_delegation(struct inode *inode,
 957                 const nfs4_stateid *stateid)
 958 {
 959         nfs_revoke_delegation(inode, stateid);
 960 }
 961 EXPORT_SYMBOL_GPL(nfs_remove_bad_delegation);
 962
 963 void nfs_delegation_mark_returned(struct inode *inode,
 964                 const nfs4_stateid *stateid)
 965 {
 966         struct nfs_delegation *delegation;
 967
 968         if (!inode)
 969                 return;
 970
 971         rcu_read_lock();
 972         delegation = rcu_dereference(NFS_I(inode)->delegation);
 973         if (!delegation)
 974                 goto out_rcu_unlock;
 975
 976         spin_lock(&delegation->lock);
 977         if (!nfs4_stateid_match_other(stateid, &delegation->stateid))
 978                 goto out_spin_unlock;
 979         if (stateid->seqid) {
 980                 /* If delegation->stateid is newer, dont mark as returned */
 981                 if (nfs4_stateid_is_newer(&delegation->stateid, stateid))
 982                         goto out_clear_returning;
 983                 if (delegation->stateid.seqid != stateid->seqid)
 984                         delegation->stateid.seqid = stateid->seqid;
 985         }
 986
 987         nfs_mark_delegation_revoked(delegation);
 988
 989 out_clear_returning:
 990         clear_bit(NFS_DELEGATION_RETURNING, &delegation->flags);
 991 out_spin_unlock:
 992         spin_unlock(&delegation->lock);
 993 out_rcu_unlock:
 994         rcu_read_unlock();
 995
 996         nfs_inode_find_state_and_recover(inode, stateid);
 997 }
 998
 999 /**
1000  * nfs_expire_unused_delegation_types
1001  * @clp: client to process
1002  * @flags: delegation types to expire
1003  *
1004  */
1005 void nfs_expire_unused_delegation_types(struct nfs_client *clp, fmode_t flags)
1006 {
1007         nfs_client_mark_return_unused_delegation_types(clp, flags);
1008         nfs_delegation_run_state_manager(clp);
1009 }
1010
1011 static void nfs_mark_return_unreferenced_delegations(struct nfs_server *server)
1012 {
1013         struct nfs_delegation *delegation;
1014
1015         list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
1016                 if (test_and_clear_bit(NFS_DELEGATION_REFERENCED, &delegation->flags))
1017                         continue;
1018                 nfs_mark_return_if_closed_delegation(server, delegation);
1019         }
1020 }
1021
1022 /**
1023  * nfs_expire_unreferenced_delegations - Eliminate unused delegations
1024  * @clp: nfs_client to process
1025  *
1026  */
1027 void nfs_expire_unreferenced_delegations(struct nfs_client *clp)
1028 {
1029         struct nfs_server *server;
1030
1031         rcu_read_lock();
1032         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
1033                 nfs_mark_return_unreferenced_delegations(server);
1034         rcu_read_unlock();
1035
1036         nfs_delegation_run_state_manager(clp);
1037 }
1038
1039 /**
1040  * nfs_async_inode_return_delegation - asynchronously return a delegation
1041  * @inode: inode to process
1042  * @stateid: state ID information
1043  *
1044  * Returns zero on success, or a negative errno value.
1045  */
1046 int nfs_async_inode_return_delegation(struct inode *inode,
1047                                       const nfs4_stateid *stateid)
1048 {
1049         struct nfs_server *server = NFS_SERVER(inode);
1050         struct nfs_client *clp = server->nfs_client;
1051         struct nfs_delegation *delegation;
1052
1053         rcu_read_lock();
1054         delegation = nfs4_get_valid_delegation(inode);
1055         if (delegation == NULL)
1056                 goto out_enoent;
1057         if (stateid != NULL &&
1058             !clp->cl_mvops->match_stateid(&delegation->stateid, stateid))
1059                 goto out_enoent;
1060         nfs_mark_return_delegation(server, delegation);
1061         rcu_read_unlock();
1062
1063         /* If there are any application leases or delegations, recall them */
1064         break_lease(inode, O_WRONLY | O_RDWR | O_NONBLOCK);
1065
1066         nfs_delegation_run_state_manager(clp);
1067         return 0;
1068 out_enoent:
1069         rcu_read_unlock();
1070         return -ENOENT;
1071 }
1072
1073 static struct inode *
1074 nfs_delegation_find_inode_server(struct nfs_server *server,
1075                                  const struct nfs_fh *fhandle)
1076 {
1077         struct nfs_delegation *delegation;
1078         struct super_block *freeme = NULL;
1079         struct inode *res = NULL;
1080
1081         list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
1082                 spin_lock(&delegation->lock);
1083                 if (delegation->inode != NULL &&
1084                     !test_bit(NFS_DELEGATION_REVOKED, &delegation->flags) &&
1085                     nfs_compare_fh(fhandle, &NFS_I(delegation->inode)->fh) == 0) {
1086                         if (nfs_sb_active(server->super)) {
1087                                 freeme = server->super;
1088                                 res = igrab(delegation->inode);
1089                         }
1090                         spin_unlock(&delegation->lock);
1091                         if (res != NULL)
1092                                 return res;
1093                         if (freeme) {
1094                                 rcu_read_unlock();
1095                                 nfs_sb_deactive(freeme);
1096                                 rcu_read_lock();
1097                         }
1098                         return ERR_PTR(-EAGAIN);
1099                 }
1100                 spin_unlock(&delegation->lock);
1101         }
1102         return ERR_PTR(-ENOENT);
1103 }
1104
1105 /**
1106  * nfs_delegation_find_inode - retrieve the inode associated with a delegation
1107  * @clp: client state handle
1108  * @fhandle: filehandle from a delegation recall
1109  *
1110  * Returns pointer to inode matching "fhandle," or NULL if a matching inode
1111  * cannot be found.
1112  */
1113 struct inode *nfs_delegation_find_inode(struct nfs_client *clp,
1114                                         const struct nfs_fh *fhandle)
1115 {
1116         struct nfs_server *server;
1117         struct inode *res;
1118
1119         rcu_read_lock();
1120         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link) {
1121                 res = nfs_delegation_find_inode_server(server, fhandle);
1122                 if (res != ERR_PTR(-ENOENT)) {
1123                         rcu_read_unlock();
1124                         return res;
1125                 }
1126         }
1127         rcu_read_unlock();
1128         return ERR_PTR(-ENOENT);
1129 }
1130
1131 static void nfs_delegation_mark_reclaim_server(struct nfs_server *server)
1132 {
1133         struct nfs_delegation *delegation;
1134
1135         list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
1136                 /*
1137                  * If the delegation may have been admin revoked, then we
1138                  * cannot reclaim it.
1139                  */
1140                 if (test_bit(NFS_DELEGATION_TEST_EXPIRED, &delegation->flags))
1141                         continue;
1142                 set_bit(NFS_DELEGATION_NEED_RECLAIM, &delegation->flags);
1143         }
1144 }
1145
1146 /**
1147  * nfs_delegation_mark_reclaim - mark all delegations as needing to be reclaimed
1148  * @clp: nfs_client to process
1149  *
1150  */
1151 void nfs_delegation_mark_reclaim(struct nfs_client *clp)
1152 {
1153         struct nfs_server *server;
1154
1155         rcu_read_lock();
1156         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
1157                 nfs_delegation_mark_reclaim_server(server);
1158         rcu_read_unlock();
1159 }
1160
1161 static int nfs_server_reap_unclaimed_delegations(struct nfs_server *server,
1162                 void __always_unused *data)
1163 {
1164         struct nfs_delegation *delegation;
1165         struct inode *inode;
1166 restart:
1167         rcu_read_lock();
1168 restart_locked:
1169         list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
1170                 if (test_bit(NFS_DELEGATION_INODE_FREEING,
1171                                         &delegation->flags) ||
1172                     test_bit(NFS_DELEGATION_RETURNING,
1173                                         &delegation->flags) ||
1174                     test_bit(NFS_DELEGATION_NEED_RECLAIM,
1175                                         &delegation->flags) == 0)
1176                         continue;
1177                 inode = nfs_delegation_grab_inode(delegation);
1178                 if (inode == NULL)
1179                         goto restart_locked;
1180                 delegation = nfs_start_delegation_return_locked(NFS_I(inode));
1181                 rcu_read_unlock();
1182                 if (delegation != NULL) {
1183                         if (nfs_detach_delegation(NFS_I(inode), delegation,
1184                                                 server) != NULL)
1185                                 nfs_free_delegation(delegation);
1186                         /* Match nfs_start_delegation_return_locked */
1187                         nfs_put_delegation(delegation);
1188                 }
1189                 iput(inode);
1190                 cond_resched();
1191                 goto restart;
1192         }
1193         rcu_read_unlock();
1194         return 0;
1195 }
1196
1197 /**
1198  * nfs_delegation_reap_unclaimed - reap unclaimed delegations after reboot recovery is done
1199  * @clp: nfs_client to process
1200  *
1201  */
1202 void nfs_delegation_reap_unclaimed(struct nfs_client *clp)
1203 {
1204         nfs_client_for_each_server(clp, nfs_server_reap_unclaimed_delegations,
1205                         NULL);
1206 }
1207
1208 static inline bool nfs4_server_rebooted(const struct nfs_client *clp)
1209 {
1210         return (clp->cl_state & (BIT(NFS4CLNT_CHECK_LEASE) |
1211                                 BIT(NFS4CLNT_LEASE_EXPIRED) |
1212                                 BIT(NFS4CLNT_SESSION_RESET))) != 0;
1213 }
1214
1215 static void nfs_mark_test_expired_delegation(struct nfs_server *server,
1216             struct nfs_delegation *delegation)
1217 {
1218         if (delegation->stateid.type == NFS4_INVALID_STATEID_TYPE)
1219                 return;
1220         clear_bit(NFS_DELEGATION_NEED_RECLAIM, &delegation->flags);
1221         set_bit(NFS_DELEGATION_TEST_EXPIRED, &delegation->flags);
1222         set_bit(NFS4CLNT_DELEGATION_EXPIRED, &server->nfs_client->cl_state);
1223 }
1224
1225 static void nfs_inode_mark_test_expired_delegation(struct nfs_server *server,
1226                 struct inode *inode)
1227 {
1228         struct nfs_delegation *delegation;
1229
1230         rcu_read_lock();
1231         delegation = rcu_dereference(NFS_I(inode)->delegation);
1232         if (delegation)
1233                 nfs_mark_test_expired_delegation(server, delegation);
1234         rcu_read_unlock();
1235
1236 }
1237
1238 static void nfs_delegation_mark_test_expired_server(struct nfs_server *server)
1239 {
1240         struct nfs_delegation *delegation;
1241
1242         list_for_each_entry_rcu(delegation, &server->delegations, super_list)
1243                 nfs_mark_test_expired_delegation(server, delegation);
1244 }
1245
1246 /**
1247  * nfs_mark_test_expired_all_delegations - mark all delegations for testing
1248  * @clp: nfs_client to process
1249  *
1250  * Iterates through all the delegations associated with this server and
1251  * marks them as needing to be checked for validity.
1252  */
1253 void nfs_mark_test_expired_all_delegations(struct nfs_client *clp)
1254 {
1255         struct nfs_server *server;
1256
1257         rcu_read_lock();
1258         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
1259                 nfs_delegation_mark_test_expired_server(server);
1260         rcu_read_unlock();
1261 }
1262
1263 /**
1264  * nfs_test_expired_all_delegations - test all delegations for a client
1265  * @clp: nfs_client to process
1266  *
1267  * Helper for handling "recallable state revoked" status from server.
1268  */
1269 void nfs_test_expired_all_delegations(struct nfs_client *clp)
1270 {
1271         nfs_mark_test_expired_all_delegations(clp);
1272         nfs4_schedule_state_manager(clp);
1273 }
1274
1275 static void
1276 nfs_delegation_test_free_expired(struct inode *inode,
1277                 nfs4_stateid *stateid,
1278                 const struct cred *cred)
1279 {
1280         struct nfs_server *server = NFS_SERVER(inode);
1281         const struct nfs4_minor_version_ops *ops = server->nfs_client->cl_mvops;
1282         int status;
1283
1284         if (!cred)
1285                 return;
1286         status = ops->test_and_free_expired(server, stateid, cred);
1287         if (status == -NFS4ERR_EXPIRED || status == -NFS4ERR_BAD_STATEID)
1288                 nfs_remove_bad_delegation(inode, stateid);
1289 }
1290
1291 static int nfs_server_reap_expired_delegations(struct nfs_server *server,
1292                 void __always_unused *data)
1293 {
1294         struct nfs_delegation *delegation;
1295         struct inode *inode;
1296         const struct cred *cred;
1297         nfs4_stateid stateid;
1298         unsigned long gen = ++server->delegation_gen;
1299
1300 restart:
1301         rcu_read_lock();
1302 restart_locked:
1303         list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
1304                 if (test_bit(NFS_DELEGATION_INODE_FREEING,
1305                                         &delegation->flags) ||
1306                     test_bit(NFS_DELEGATION_RETURNING,
1307                                         &delegation->flags) ||
1308                     test_bit(NFS_DELEGATION_TEST_EXPIRED,
1309                                         &delegation->flags) == 0 ||
1310                         delegation->test_gen == gen)
1311                         continue;
1312                 inode = nfs_delegation_grab_inode(delegation);
1313                 if (inode == NULL)
1314                         goto restart_locked;
1315                 spin_lock(&delegation->lock);
1316                 cred = get_cred_rcu(delegation->cred);
1317                 nfs4_stateid_copy(&stateid, &delegation->stateid);
1318                 spin_unlock(&delegation->lock);
1319                 delegation->test_gen = gen;
1320                 clear_bit(NFS_DELEGATION_TEST_EXPIRED, &delegation->flags);
1321                 rcu_read_unlock();
1322                 nfs_delegation_test_free_expired(inode, &stateid, cred);
1323                 put_cred(cred);
1324                 if (!nfs4_server_rebooted(server->nfs_client)) {
1325                         iput(inode);
1326                         cond_resched();
1327                         goto restart;
1328                 }
1329                 nfs_inode_mark_test_expired_delegation(server,inode);
1330                 iput(inode);
1331                 return -EAGAIN;
1332         }
1333         rcu_read_unlock();
1334         return 0;
1335 }
1336
1337 /**
1338  * nfs_reap_expired_delegations - reap expired delegations
1339  * @clp: nfs_client to process
1340  *
1341  * Iterates through all the delegations associated with this server and
1342  * checks if they have may have been revoked. This function is usually
1343  * expected to be called in cases where the server may have lost its
1344  * lease.
1345  */
1346 void nfs_reap_expired_delegations(struct nfs_client *clp)
1347 {
1348         nfs_client_for_each_server(clp, nfs_server_reap_expired_delegations,
1349                         NULL);
1350 }
1351
1352 void nfs_inode_find_delegation_state_and_recover(struct inode *inode,
1353                 const nfs4_stateid *stateid)
1354 {
1355         struct nfs_client *clp = NFS_SERVER(inode)->nfs_client;
1356         struct nfs_delegation *delegation;
1357         bool found = false;
1358
1359         rcu_read_lock();
1360         delegation = rcu_dereference(NFS_I(inode)->delegation);
1361         if (delegation &&
1362             nfs4_stateid_match_or_older(&delegation->stateid, stateid) &&
1363             !test_bit(NFS_DELEGATION_REVOKED, &delegation->flags)) {
1364                 nfs_mark_test_expired_delegation(NFS_SERVER(inode), delegation);
1365                 found = true;
1366         }
1367         rcu_read_unlock();
1368         if (found)
1369                 nfs4_schedule_state_manager(clp);
1370 }
1371
1372 /**
1373  * nfs_delegations_present - check for existence of delegations
1374  * @clp: client state handle
1375  *
1376  * Returns one if there are any nfs_delegation structures attached
1377  * to this nfs_client.
1378  */
1379 int nfs_delegations_present(struct nfs_client *clp)
1380 {
1381         struct nfs_server *server;
1382         int ret = 0;
1383
1384         rcu_read_lock();
1385         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
1386                 if (!list_empty(&server->delegations)) {
1387                         ret = 1;
1388                         break;
1389                 }
1390         rcu_read_unlock();
1391         return ret;
1392 }
1393
1394 /**
1395  * nfs4_refresh_delegation_stateid - Update delegation stateid seqid
1396  * @dst: stateid to refresh
1397  * @inode: inode to check
1398  *
1399  * Returns "true" and updates "dst->seqid" * if inode had a delegation
1400  * that matches our delegation stateid. Otherwise "false" is returned.
1401  */
1402 bool nfs4_refresh_delegation_stateid(nfs4_stateid *dst, struct inode *inode)
1403 {
1404         struct nfs_delegation *delegation;
1405         bool ret = false;
1406         if (!inode)
1407                 goto out;
1408
1409         rcu_read_lock();
1410         delegation = rcu_dereference(NFS_I(inode)->delegation);
1411         if (delegation != NULL &&
1412             nfs4_stateid_match_other(dst, &delegation->stateid) &&
1413             nfs4_stateid_is_newer(&delegation->stateid, dst) &&
1414             !test_bit(NFS_DELEGATION_REVOKED, &delegation->flags)) {
1415                 dst->seqid = delegation->stateid.seqid;
1416                 ret = true;
1417         }
1418         rcu_read_unlock();
1419 out:
1420         return ret;
1421 }
1422
1423 /**
1424  * nfs4_copy_delegation_stateid - Copy inode's state ID information
1425  * @inode: inode to check
1426  * @flags: delegation type requirement
1427  * @dst: stateid data structure to fill in
1428  * @cred: optional argument to retrieve credential
1429  *
1430  * Returns "true" and fills in "dst->data" * if inode had a delegation,
1431  * otherwise "false" is returned.
1432  */
1433 bool nfs4_copy_delegation_stateid(struct inode *inode, fmode_t flags,
1434                 nfs4_stateid *dst, const struct cred **cred)
1435 {
1436         struct nfs_inode *nfsi = NFS_I(inode);
1437         struct nfs_delegation *delegation;
1438         bool ret = false;
1439
1440         flags &= FMODE_READ|FMODE_WRITE;
1441         rcu_read_lock();
1442         delegation = rcu_dereference(nfsi->delegation);
1443         if (!delegation)
1444                 goto out;
1445         spin_lock(&delegation->lock);
1446         ret = nfs4_is_valid_delegation(delegation, flags);
1447         if (ret) {
1448                 nfs4_stateid_copy(dst, &delegation->stateid);
1449                 nfs_mark_delegation_referenced(delegation);
1450                 if (cred)
1451                         *cred = get_cred(delegation->cred);
1452         }
1453         spin_unlock(&delegation->lock);
1454 out:
1455         rcu_read_unlock();
1456         return ret;
1457 }
1458
1459 /**
1460  * nfs4_delegation_flush_on_close - Check if we must flush file on close
1461  * @inode: inode to check
1462  *
1463  * This function checks the number of outstanding writes to the file
1464  * against the delegation 'space_limit' field to see if
1465  * the spec requires us to flush the file on close.
1466  */
1467 bool nfs4_delegation_flush_on_close(const struct inode *inode)
1468 {
1469         struct nfs_inode *nfsi = NFS_I(inode);
1470         struct nfs_delegation *delegation;
1471         bool ret = true;
1472
1473         rcu_read_lock();
1474         delegation = rcu_dereference(nfsi->delegation);
1475         if (delegation == NULL || !(delegation->type & FMODE_WRITE))
1476                 goto out;
1477         if (atomic_long_read(&nfsi->nrequests) < delegation->pagemod_limit)
1478                 ret = false;
1479 out:
1480         rcu_read_unlock();
1481         return ret;
1482 }
1483
1484 module_param_named(delegation_watermark, nfs_delegation_watermark, uint, 0644);