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