kernel/fs/nfs/delegation.c

   1 /*
   2  * linux/fs/nfs/delegation.c
   3  *
   4  * Copyright (C) 2004 Trond Myklebust
   5  *
   6  * NFS file delegation management
   7  *
   8  */
   9 #include <linux/completion.h>
  10 #include <linux/kthread.h>
  11 #include <linux/module.h>
  12 #include <linux/sched.h>
  13 #include <linux/slab.h>
  14 #include <linux/spinlock.h>
  15
  16 #include <linux/nfs4.h>
  17 #include <linux/nfs_fs.h>
  18 #include <linux/nfs_xdr.h>
  19
  20 #include "nfs4_fs.h"
  21 #include "delegation.h"
  22 #include "internal.h"
  23 #include "nfs4trace.h"
  24
  25 static void nfs_free_delegation(struct nfs_delegation *delegation)
  26 {
  27         if (delegation->cred) {
  28                 put_rpccred(delegation->cred);
  29                 delegation->cred = NULL;
  30         }
  31         kfree_rcu(delegation, rcu);
  32 }
  33
  34 /**
  35  * nfs_mark_delegation_referenced - set delegation's REFERENCED flag
  36  * @delegation: delegation to process
  37  *
  38  */
  39 void nfs_mark_delegation_referenced(struct nfs_delegation *delegation)
  40 {
  41         set_bit(NFS_DELEGATION_REFERENCED, &delegation->flags);
  42 }
  43
  44 static bool
  45 nfs4_is_valid_delegation(const struct nfs_delegation *delegation,
  46                 fmode_t flags)
  47 {
  48         if (delegation != NULL && (delegation->type & flags) == flags &&
  49             !test_bit(NFS_DELEGATION_REVOKED, &delegation->flags) &&
  50             !test_bit(NFS_DELEGATION_RETURNING, &delegation->flags))
  51                 return true;
  52         return false;
  53 }
  54
  55 static int
  56 nfs4_do_check_delegation(struct inode *inode, fmode_t flags, bool mark)
  57 {
  58         struct nfs_delegation *delegation;
  59         int ret = 0;
  60
  61         flags &= FMODE_READ|FMODE_WRITE;
  62         rcu_read_lock();
  63         delegation = rcu_dereference(NFS_I(inode)->delegation);
  64         if (nfs4_is_valid_delegation(delegation, flags)) {
  65                 if (mark)
  66                         nfs_mark_delegation_referenced(delegation);
  67                 ret = 1;
  68         }
  69         rcu_read_unlock();
  70         return ret;
  71 }
  72 /**
  73  * nfs_have_delegation - check if inode has a delegation, mark it
  74  * NFS_DELEGATION_REFERENCED if there is one.
  75  * @inode: inode to check
  76  * @flags: delegation types to check for
  77  *
  78  * Returns one if inode has the indicated delegation, otherwise zero.
  79  */
  80 int nfs4_have_delegation(struct inode *inode, fmode_t flags)
  81 {
  82         return nfs4_do_check_delegation(inode, flags, true);
  83 }
  84
  85 /*
  86  * nfs4_check_delegation - check if inode has a delegation, do not mark
  87  * NFS_DELEGATION_REFERENCED if it has one.
  88  */
  89 int nfs4_check_delegation(struct inode *inode, fmode_t flags)
  90 {
  91         return nfs4_do_check_delegation(inode, flags, false);
  92 }
  93
  94 static int nfs_delegation_claim_locks(struct nfs_open_context *ctx, struct nfs4_state *state, const nfs4_stateid *stateid)
  95 {
  96         struct inode *inode = state->inode;
  97         struct file_lock *fl;
  98         struct file_lock_context *flctx = inode->i_flctx;
  99         struct list_head *list;
 100         int status = 0;
 101
 102         if (flctx == NULL)
 103                 goto out;
 104
 105         list = &flctx->flc_posix;
 106         spin_lock(&flctx->flc_lock);
 107 restart:
 108         list_for_each_entry(fl, list, fl_list) {
 109                 if (nfs_file_open_context(fl->fl_file) != ctx)
 110                         continue;
 111                 spin_unlock(&flctx->flc_lock);
 112                 status = nfs4_lock_delegation_recall(fl, state, stateid);
 113                 if (status < 0)
 114                         goto out;
 115                 spin_lock(&flctx->flc_lock);
 116         }
 117         if (list == &flctx->flc_posix) {
 118                 list = &flctx->flc_flock;
 119                 goto restart;
 120         }
 121         spin_unlock(&flctx->flc_lock);
 122 out:
 123         return status;
 124 }
 125
 126 static int nfs_delegation_claim_opens(struct inode *inode,
 127                 const nfs4_stateid *stateid, fmode_t type)
 128 {
 129         struct nfs_inode *nfsi = NFS_I(inode);
 130         struct nfs_open_context *ctx;
 131         struct nfs4_state_owner *sp;
 132         struct nfs4_state *state;
 133         unsigned int seq;
 134         int err;
 135
 136 again:
 137         spin_lock(&inode->i_lock);
 138         list_for_each_entry(ctx, &nfsi->open_files, list) {
 139                 state = ctx->state;
 140                 if (state == NULL)
 141                         continue;
 142                 if (!test_bit(NFS_DELEGATED_STATE, &state->flags))
 143                         continue;
 144                 if (!nfs4_valid_open_stateid(state))
 145                         continue;
 146                 if (!nfs4_stateid_match(&state->stateid, stateid))
 147                         continue;
 148                 get_nfs_open_context(ctx);
 149                 spin_unlock(&inode->i_lock);
 150                 sp = state->owner;
 151                 /* Block nfs4_proc_unlck */
 152                 mutex_lock(&sp->so_delegreturn_mutex);
 153                 seq = raw_seqcount_begin(&sp->so_reclaim_seqcount);
 154                 err = nfs4_open_delegation_recall(ctx, state, stateid, type);
 155                 if (!err)
 156                         err = nfs_delegation_claim_locks(ctx, state, stateid);
 157                 if (!err && read_seqcount_retry(&sp->so_reclaim_seqcount, seq))
 158                         err = -EAGAIN;
 159                 mutex_unlock(&sp->so_delegreturn_mutex);
 160                 put_nfs_open_context(ctx);
 161                 if (err != 0)
 162                         return err;
 163                 goto again;
 164         }
 165         spin_unlock(&inode->i_lock);
 166         return 0;
 167 }
 168
 169 /**
 170  * nfs_inode_reclaim_delegation - process a delegation reclaim request
 171  * @inode: inode to process
 172  * @cred: credential to use for request
 173  * @res: new delegation state from server
 174  *
 175  */
 176 void nfs_inode_reclaim_delegation(struct inode *inode, struct rpc_cred *cred,
 177                                   struct nfs_openres *res)
 178 {
 179         struct nfs_delegation *delegation;
 180         struct rpc_cred *oldcred = NULL;
 181
 182         rcu_read_lock();
 183         delegation = rcu_dereference(NFS_I(inode)->delegation);
 184         if (delegation != NULL) {
 185                 spin_lock(&delegation->lock);
 186                 if (delegation->inode != NULL) {
 187                         nfs4_stateid_copy(&delegation->stateid, &res->delegation);
 188                         delegation->type = res->delegation_type;
 189                         delegation->pagemod_limit = res->pagemod_limit;
 190                         oldcred = delegation->cred;
 191                         delegation->cred = get_rpccred(cred);
 192                         clear_bit(NFS_DELEGATION_NEED_RECLAIM,
 193                                   &delegation->flags);
 194                         spin_unlock(&delegation->lock);
 195                         rcu_read_unlock();
 196                         put_rpccred(oldcred);
 197                         trace_nfs4_reclaim_delegation(inode, res->delegation_type);
 198                 } else {
 199                         /* We appear to have raced with a delegation return. */
 200                         spin_unlock(&delegation->lock);
 201                         rcu_read_unlock();
 202                         nfs_inode_set_delegation(inode, cred, res);
 203                 }
 204         } else {
 205                 rcu_read_unlock();
 206         }
 207 }
 208
 209 static int nfs_do_return_delegation(struct inode *inode, struct nfs_delegation *delegation, int issync)
 210 {
 211         int res = 0;
 212
 213         if (!test_bit(NFS_DELEGATION_REVOKED, &delegation->flags))
 214                 res = nfs4_proc_delegreturn(inode,
 215                                 delegation->cred,
 216                                 &delegation->stateid,
 217                                 issync);
 218         nfs_free_delegation(delegation);
 219         return res;
 220 }
 221
 222 static struct inode *nfs_delegation_grab_inode(struct nfs_delegation *delegation)
 223 {
 224         struct inode *inode = NULL;
 225
 226         spin_lock(&delegation->lock);
 227         if (delegation->inode != NULL)
 228                 inode = igrab(delegation->inode);
 229         spin_unlock(&delegation->lock);
 230         return inode;
 231 }
 232
 233 static struct nfs_delegation *
 234 nfs_start_delegation_return_locked(struct nfs_inode *nfsi)
 235 {
 236         struct nfs_delegation *ret = NULL;
 237         struct nfs_delegation *delegation = rcu_dereference(nfsi->delegation);
 238
 239         if (delegation == NULL)
 240                 goto out;
 241         spin_lock(&delegation->lock);
 242         if (!test_and_set_bit(NFS_DELEGATION_RETURNING, &delegation->flags))
 243                 ret = delegation;
 244         spin_unlock(&delegation->lock);
 245 out:
 246         return ret;
 247 }
 248
 249 static struct nfs_delegation *
 250 nfs_start_delegation_return(struct nfs_inode *nfsi)
 251 {
 252         struct nfs_delegation *delegation;
 253
 254         rcu_read_lock();
 255         delegation = nfs_start_delegation_return_locked(nfsi);
 256         rcu_read_unlock();
 257         return delegation;
 258 }
 259
 260 static void
 261 nfs_abort_delegation_return(struct nfs_delegation *delegation,
 262                 struct nfs_client *clp)
 263 {
 264
 265         spin_lock(&delegation->lock);
 266         clear_bit(NFS_DELEGATION_RETURNING, &delegation->flags);
 267         set_bit(NFS_DELEGATION_RETURN, &delegation->flags);
 268         spin_unlock(&delegation->lock);
 269         set_bit(NFS4CLNT_DELEGRETURN, &clp->cl_state);
 270 }
 271
 272 static struct nfs_delegation *
 273 nfs_detach_delegation_locked(struct nfs_inode *nfsi,
 274                 struct nfs_delegation *delegation,
 275                 struct nfs_client *clp)
 276 {
 277         struct nfs_delegation *deleg_cur =
 278                 rcu_dereference_protected(nfsi->delegation,
 279                                 lockdep_is_held(&clp->cl_lock));
 280
 281         if (deleg_cur == NULL || delegation != deleg_cur)
 282                 return NULL;
 283
 284         spin_lock(&delegation->lock);
 285         set_bit(NFS_DELEGATION_RETURNING, &delegation->flags);
 286         list_del_rcu(&delegation->super_list);
 287         delegation->inode = NULL;
 288         rcu_assign_pointer(nfsi->delegation, NULL);
 289         spin_unlock(&delegation->lock);
 290         return delegation;
 291 }
 292
 293 static struct nfs_delegation *nfs_detach_delegation(struct nfs_inode *nfsi,
 294                 struct nfs_delegation *delegation,
 295                 struct nfs_server *server)
 296 {
 297         struct nfs_client *clp = server->nfs_client;
 298
 299         spin_lock(&clp->cl_lock);
 300         delegation = nfs_detach_delegation_locked(nfsi, delegation, clp);
 301         spin_unlock(&clp->cl_lock);
 302         return delegation;
 303 }
 304
 305 static struct nfs_delegation *
 306 nfs_inode_detach_delegation(struct inode *inode)
 307 {
 308         struct nfs_inode *nfsi = NFS_I(inode);
 309         struct nfs_server *server = NFS_SERVER(inode);
 310         struct nfs_delegation *delegation;
 311
 312         delegation = nfs_start_delegation_return(nfsi);
 313         if (delegation == NULL)
 314                 return NULL;
 315         return nfs_detach_delegation(nfsi, delegation, server);
 316 }
 317
 318 static void
 319 nfs_update_inplace_delegation(struct nfs_delegation *delegation,
 320                 const struct nfs_delegation *update)
 321 {
 322         if (nfs4_stateid_is_newer(&update->stateid, &delegation->stateid)) {
 323                 delegation->stateid.seqid = update->stateid.seqid;
 324                 smp_wmb();
 325                 delegation->type = update->type;
 326         }
 327 }
 328
 329 /**
 330  * nfs_inode_set_delegation - set up a delegation on an inode
 331  * @inode: inode to which delegation applies
 332  * @cred: cred to use for subsequent delegation processing
 333  * @res: new delegation state from server
 334  *
 335  * Returns zero on success, or a negative errno value.
 336  */
 337 int nfs_inode_set_delegation(struct inode *inode, struct rpc_cred *cred, struct nfs_openres *res)
 338 {
 339         struct nfs_server *server = NFS_SERVER(inode);
 340         struct nfs_client *clp = server->nfs_client;
 341         struct nfs_inode *nfsi = NFS_I(inode);
 342         struct nfs_delegation *delegation, *old_delegation;
 343         struct nfs_delegation *freeme = NULL;
 344         int status = 0;
 345
 346         delegation = kmalloc(sizeof(*delegation), GFP_NOFS);
 347         if (delegation == NULL)
 348                 return -ENOMEM;
 349         nfs4_stateid_copy(&delegation->stateid, &res->delegation);
 350         delegation->type = res->delegation_type;
 351         delegation->pagemod_limit = res->pagemod_limit;
 352         delegation->change_attr = inode->i_version;
 353         delegation->cred = get_rpccred(cred);
 354         delegation->inode = inode;
 355         delegation->flags = 1<<NFS_DELEGATION_REFERENCED;
 356         spin_lock_init(&delegation->lock);
 357
 358         spin_lock(&clp->cl_lock);
 359         old_delegation = rcu_dereference_protected(nfsi->delegation,
 360                                         lockdep_is_held(&clp->cl_lock));
 361         if (old_delegation != NULL) {
 362                 /* Is this an update of the existing delegation? */
 363                 if (nfs4_stateid_match_other(&old_delegation->stateid,
 364                                         &delegation->stateid)) {
 365                         nfs_update_inplace_delegation(old_delegation,
 366                                         delegation);
 367                         goto out;
 368                 }
 369                 /*
 370                  * Deal with broken servers that hand out two
 371                  * delegations for the same file.
 372                  * Allow for upgrades to a WRITE delegation, but
 373                  * nothing else.
 374                  */
 375                 dfprintk(FILE, "%s: server %s handed out "
 376                                 "a duplicate delegation!\n",
 377                                 __func__, clp->cl_hostname);
 378                 if (delegation->type == old_delegation->type ||
 379                     !(delegation->type & FMODE_WRITE)) {
 380                         freeme = delegation;
 381                         delegation = NULL;
 382                         goto out;
 383                 }
 384                 if (test_and_set_bit(NFS_DELEGATION_RETURNING,
 385                                         &old_delegation->flags))
 386                         goto out;
 387                 freeme = nfs_detach_delegation_locked(nfsi,
 388                                 old_delegation, clp);
 389                 if (freeme == NULL)
 390                         goto out;
 391         }
 392         list_add_tail_rcu(&delegation->super_list, &server->delegations);
 393         rcu_assign_pointer(nfsi->delegation, delegation);
 394         delegation = NULL;
 395
 396         /* Ensure we revalidate the attributes and page cache! */
 397         spin_lock(&inode->i_lock);
 398         nfsi->cache_validity |= NFS_INO_REVAL_FORCED;
 399         spin_unlock(&inode->i_lock);
 400         trace_nfs4_set_delegation(inode, res->delegation_type);
 401
 402 out:
 403         spin_unlock(&clp->cl_lock);
 404         if (delegation != NULL)
 405                 nfs_free_delegation(delegation);
 406         if (freeme != NULL)
 407                 nfs_do_return_delegation(inode, freeme, 0);
 408         return status;
 409 }
 410
 411 /*
 412  * Basic procedure for returning a delegation to the server
 413  */
 414 static int nfs_end_delegation_return(struct inode *inode, struct nfs_delegation *delegation, int issync)
 415 {
 416         struct nfs_client *clp = NFS_SERVER(inode)->nfs_client;
 417         struct nfs_inode *nfsi = NFS_I(inode);
 418         int err = 0;
 419
 420         if (delegation == NULL)
 421                 return 0;
 422         do {
 423                 if (test_bit(NFS_DELEGATION_REVOKED, &delegation->flags))
 424                         break;
 425                 err = nfs_delegation_claim_opens(inode, &delegation->stateid,
 426                                 delegation->type);
 427                 if (!issync || err != -EAGAIN)
 428                         break;
 429                 /*
 430                  * Guard against state recovery
 431                  */
 432                 err = nfs4_wait_clnt_recover(clp);
 433         } while (err == 0);
 434
 435         if (err) {
 436                 nfs_abort_delegation_return(delegation, clp);
 437                 goto out;
 438         }
 439         if (!nfs_detach_delegation(nfsi, delegation, NFS_SERVER(inode)))
 440                 goto out;
 441
 442         err = nfs_do_return_delegation(inode, delegation, issync);
 443 out:
 444         return err;
 445 }
 446
 447 static bool nfs_delegation_need_return(struct nfs_delegation *delegation)
 448 {
 449         bool ret = false;
 450
 451         if (test_bit(NFS_DELEGATION_RETURNING, &delegation->flags))
 452                 goto out;
 453         if (test_and_clear_bit(NFS_DELEGATION_RETURN, &delegation->flags))
 454                 ret = true;
 455         if (test_and_clear_bit(NFS_DELEGATION_RETURN_IF_CLOSED, &delegation->flags) && !ret) {
 456                 struct inode *inode;
 457
 458                 spin_lock(&delegation->lock);
 459                 inode = delegation->inode;
 460                 if (inode && list_empty(&NFS_I(inode)->open_files))
 461                         ret = true;
 462                 spin_unlock(&delegation->lock);
 463         }
 464 out:
 465         return ret;
 466 }
 467
 468 /**
 469  * nfs_client_return_marked_delegations - return previously marked delegations
 470  * @clp: nfs_client to process
 471  *
 472  * Note that this function is designed to be called by the state
 473  * manager thread. For this reason, it cannot flush the dirty data,
 474  * since that could deadlock in case of a state recovery error.
 475  *
 476  * Returns zero on success, or a negative errno value.
 477  */
 478 int nfs_client_return_marked_delegations(struct nfs_client *clp)
 479 {
 480         struct nfs_delegation *delegation;
 481         struct nfs_server *server;
 482         struct inode *inode;
 483         int err = 0;
 484
 485 restart:
 486         rcu_read_lock();
 487         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link) {
 488                 list_for_each_entry_rcu(delegation, &server->delegations,
 489                                                                 super_list) {
 490                         if (!nfs_delegation_need_return(delegation))
 491                                 continue;
 492                         if (!nfs_sb_active(server->super))
 493                                 continue;
 494                         inode = nfs_delegation_grab_inode(delegation);
 495                         if (inode == NULL) {
 496                                 rcu_read_unlock();
 497                                 nfs_sb_deactive(server->super);
 498                                 goto restart;
 499                         }
 500                         delegation = nfs_start_delegation_return_locked(NFS_I(inode));
 501                         rcu_read_unlock();
 502
 503                         err = nfs_end_delegation_return(inode, delegation, 0);
 504                         iput(inode);
 505                         nfs_sb_deactive(server->super);
 506                         if (!err)
 507                                 goto restart;
 508                         set_bit(NFS4CLNT_DELEGRETURN, &clp->cl_state);
 509                         return err;
 510                 }
 511         }
 512         rcu_read_unlock();
 513         return 0;
 514 }
 515
 516 /**
 517  * nfs_inode_return_delegation_noreclaim - return delegation, don't reclaim opens
 518  * @inode: inode to process
 519  *
 520  * Does not protect against delegation reclaims, therefore really only safe
 521  * to be called from nfs4_clear_inode().
 522  */
 523 void nfs_inode_return_delegation_noreclaim(struct inode *inode)
 524 {
 525         struct nfs_delegation *delegation;
 526
 527         delegation = nfs_inode_detach_delegation(inode);
 528         if (delegation != NULL)
 529                 nfs_do_return_delegation(inode, delegation, 1);
 530 }
 531
 532 /**
 533  * nfs_inode_return_delegation - synchronously return a delegation
 534  * @inode: inode to process
 535  *
 536  * This routine will always flush any dirty data to disk on the
 537  * assumption that if we need to return the delegation, then
 538  * we should stop caching.
 539  *
 540  * Returns zero on success, or a negative errno value.
 541  */
 542 int nfs4_inode_return_delegation(struct inode *inode)
 543 {
 544         struct nfs_inode *nfsi = NFS_I(inode);
 545         struct nfs_delegation *delegation;
 546         int err = 0;
 547
 548         nfs_wb_all(inode);
 549         delegation = nfs_start_delegation_return(nfsi);
 550         if (delegation != NULL)
 551                 err = nfs_end_delegation_return(inode, delegation, 1);
 552         return err;
 553 }
 554
 555 static void nfs_mark_return_if_closed_delegation(struct nfs_server *server,
 556                 struct nfs_delegation *delegation)
 557 {
 558         set_bit(NFS_DELEGATION_RETURN_IF_CLOSED, &delegation->flags);
 559         set_bit(NFS4CLNT_DELEGRETURN, &server->nfs_client->cl_state);
 560 }
 561
 562 static void nfs_mark_return_delegation(struct nfs_server *server,
 563                 struct nfs_delegation *delegation)
 564 {
 565         set_bit(NFS_DELEGATION_RETURN, &delegation->flags);
 566         set_bit(NFS4CLNT_DELEGRETURN, &server->nfs_client->cl_state);
 567 }
 568
 569 static bool nfs_server_mark_return_all_delegations(struct nfs_server *server)
 570 {
 571         struct nfs_delegation *delegation;
 572         bool ret = false;
 573
 574         list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
 575                 nfs_mark_return_delegation(server, delegation);
 576                 ret = true;
 577         }
 578         return ret;
 579 }
 580
 581 static void nfs_client_mark_return_all_delegations(struct nfs_client *clp)
 582 {
 583         struct nfs_server *server;
 584
 585         rcu_read_lock();
 586         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
 587                 nfs_server_mark_return_all_delegations(server);
 588         rcu_read_unlock();
 589 }
 590
 591 static void nfs_delegation_run_state_manager(struct nfs_client *clp)
 592 {
 593         if (test_bit(NFS4CLNT_DELEGRETURN, &clp->cl_state))
 594                 nfs4_schedule_state_manager(clp);
 595 }
 596
 597 /**
 598  * nfs_expire_all_delegations
 599  * @clp: client to process
 600  *
 601  */
 602 void nfs_expire_all_delegations(struct nfs_client *clp)
 603 {
 604         nfs_client_mark_return_all_delegations(clp);
 605         nfs_delegation_run_state_manager(clp);
 606 }
 607
 608 /**
 609  * nfs_super_return_all_delegations - return delegations for one superblock
 610  * @sb: sb to process
 611  *
 612  */
 613 void nfs_server_return_all_delegations(struct nfs_server *server)
 614 {
 615         struct nfs_client *clp = server->nfs_client;
 616         bool need_wait;
 617
 618         if (clp == NULL)
 619                 return;
 620
 621         rcu_read_lock();
 622         need_wait = nfs_server_mark_return_all_delegations(server);
 623         rcu_read_unlock();
 624
 625         if (need_wait) {
 626                 nfs4_schedule_state_manager(clp);
 627                 nfs4_wait_clnt_recover(clp);
 628         }
 629 }
 630
 631 static void nfs_mark_return_unused_delegation_types(struct nfs_server *server,
 632                                                  fmode_t flags)
 633 {
 634         struct nfs_delegation *delegation;
 635
 636         list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
 637                 if ((delegation->type == (FMODE_READ|FMODE_WRITE)) && !(flags & FMODE_WRITE))
 638                         continue;
 639                 if (delegation->type & flags)
 640                         nfs_mark_return_if_closed_delegation(server, delegation);
 641         }
 642 }
 643
 644 static void nfs_client_mark_return_unused_delegation_types(struct nfs_client *clp,
 645                                                         fmode_t flags)
 646 {
 647         struct nfs_server *server;
 648
 649         rcu_read_lock();
 650         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
 651                 nfs_mark_return_unused_delegation_types(server, flags);
 652         rcu_read_unlock();
 653 }
 654
 655 static void nfs_revoke_delegation(struct inode *inode)
 656 {
 657         struct nfs_delegation *delegation;
 658         rcu_read_lock();
 659         delegation = rcu_dereference(NFS_I(inode)->delegation);
 660         if (delegation != NULL) {
 661                 set_bit(NFS_DELEGATION_REVOKED, &delegation->flags);
 662                 nfs_mark_return_delegation(NFS_SERVER(inode), delegation);
 663         }
 664         rcu_read_unlock();
 665 }
 666
 667 void nfs_remove_bad_delegation(struct inode *inode)
 668 {
 669         struct nfs_delegation *delegation;
 670
 671         nfs_revoke_delegation(inode);
 672         delegation = nfs_inode_detach_delegation(inode);
 673         if (delegation) {
 674                 nfs_inode_find_state_and_recover(inode, &delegation->stateid);
 675                 nfs_free_delegation(delegation);
 676         }
 677 }
 678 EXPORT_SYMBOL_GPL(nfs_remove_bad_delegation);
 679
 680 /**
 681  * nfs_expire_unused_delegation_types
 682  * @clp: client to process
 683  * @flags: delegation types to expire
 684  *
 685  */
 686 void nfs_expire_unused_delegation_types(struct nfs_client *clp, fmode_t flags)
 687 {
 688         nfs_client_mark_return_unused_delegation_types(clp, flags);
 689         nfs_delegation_run_state_manager(clp);
 690 }
 691
 692 static void nfs_mark_return_unreferenced_delegations(struct nfs_server *server)
 693 {
 694         struct nfs_delegation *delegation;
 695
 696         list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
 697                 if (test_and_clear_bit(NFS_DELEGATION_REFERENCED, &delegation->flags))
 698                         continue;
 699                 nfs_mark_return_if_closed_delegation(server, delegation);
 700         }
 701 }
 702
 703 /**
 704  * nfs_expire_unreferenced_delegations - Eliminate unused delegations
 705  * @clp: nfs_client to process
 706  *
 707  */
 708 void nfs_expire_unreferenced_delegations(struct nfs_client *clp)
 709 {
 710         struct nfs_server *server;
 711
 712         rcu_read_lock();
 713         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
 714                 nfs_mark_return_unreferenced_delegations(server);
 715         rcu_read_unlock();
 716
 717         nfs_delegation_run_state_manager(clp);
 718 }
 719
 720 /**
 721  * nfs_async_inode_return_delegation - asynchronously return a delegation
 722  * @inode: inode to process
 723  * @stateid: state ID information
 724  *
 725  * Returns zero on success, or a negative errno value.
 726  */
 727 int nfs_async_inode_return_delegation(struct inode *inode,
 728                                       const nfs4_stateid *stateid)
 729 {
 730         struct nfs_server *server = NFS_SERVER(inode);
 731         struct nfs_client *clp = server->nfs_client;
 732         struct nfs_delegation *delegation;
 733
 734         rcu_read_lock();
 735         delegation = rcu_dereference(NFS_I(inode)->delegation);
 736         if (delegation == NULL)
 737                 goto out_enoent;
 738         if (stateid != NULL &&
 739             !clp->cl_mvops->match_stateid(&delegation->stateid, stateid))
 740                 goto out_enoent;
 741         nfs_mark_return_delegation(server, delegation);
 742         rcu_read_unlock();
 743
 744         nfs_delegation_run_state_manager(clp);
 745         return 0;
 746 out_enoent:
 747         rcu_read_unlock();
 748         return -ENOENT;
 749 }
 750
 751 static struct inode *
 752 nfs_delegation_find_inode_server(struct nfs_server *server,
 753                                  const struct nfs_fh *fhandle)
 754 {
 755         struct nfs_delegation *delegation;
 756         struct inode *res = NULL;
 757
 758         list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
 759                 spin_lock(&delegation->lock);
 760                 if (delegation->inode != NULL &&
 761                     nfs_compare_fh(fhandle, &NFS_I(delegation->inode)->fh) == 0) {
 762                         res = igrab(delegation->inode);
 763                 }
 764                 spin_unlock(&delegation->lock);
 765                 if (res != NULL)
 766                         break;
 767         }
 768         return res;
 769 }
 770
 771 /**
 772  * nfs_delegation_find_inode - retrieve the inode associated with a delegation
 773  * @clp: client state handle
 774  * @fhandle: filehandle from a delegation recall
 775  *
 776  * Returns pointer to inode matching "fhandle," or NULL if a matching inode
 777  * cannot be found.
 778  */
 779 struct inode *nfs_delegation_find_inode(struct nfs_client *clp,
 780                                         const struct nfs_fh *fhandle)
 781 {
 782         struct nfs_server *server;
 783         struct inode *res = NULL;
 784
 785         rcu_read_lock();
 786         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link) {
 787                 res = nfs_delegation_find_inode_server(server, fhandle);
 788                 if (res != NULL)
 789                         break;
 790         }
 791         rcu_read_unlock();
 792         return res;
 793 }
 794
 795 static void nfs_delegation_mark_reclaim_server(struct nfs_server *server)
 796 {
 797         struct nfs_delegation *delegation;
 798
 799         list_for_each_entry_rcu(delegation, &server->delegations, super_list)
 800                 set_bit(NFS_DELEGATION_NEED_RECLAIM, &delegation->flags);
 801 }
 802
 803 /**
 804  * nfs_delegation_mark_reclaim - mark all delegations as needing to be reclaimed
 805  * @clp: nfs_client to process
 806  *
 807  */
 808 void nfs_delegation_mark_reclaim(struct nfs_client *clp)
 809 {
 810         struct nfs_server *server;
 811
 812         rcu_read_lock();
 813         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
 814                 nfs_delegation_mark_reclaim_server(server);
 815         rcu_read_unlock();
 816 }
 817
 818 /**
 819  * nfs_delegation_reap_unclaimed - reap unclaimed delegations after reboot recovery is done
 820  * @clp: nfs_client to process
 821  *
 822  */
 823 void nfs_delegation_reap_unclaimed(struct nfs_client *clp)
 824 {
 825         struct nfs_delegation *delegation;
 826         struct nfs_server *server;
 827         struct inode *inode;
 828
 829 restart:
 830         rcu_read_lock();
 831         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link) {
 832                 list_for_each_entry_rcu(delegation, &server->delegations,
 833                                                                 super_list) {
 834                         if (test_bit(NFS_DELEGATION_RETURNING,
 835                                                 &delegation->flags))
 836                                 continue;
 837                         if (test_bit(NFS_DELEGATION_NEED_RECLAIM,
 838                                                 &delegation->flags) == 0)
 839                                 continue;
 840                         if (!nfs_sb_active(server->super))
 841                                 continue;
 842                         inode = nfs_delegation_grab_inode(delegation);
 843                         if (inode == NULL) {
 844                                 rcu_read_unlock();
 845                                 nfs_sb_deactive(server->super);
 846                                 goto restart;
 847                         }
 848                         delegation = nfs_start_delegation_return_locked(NFS_I(inode));
 849                         rcu_read_unlock();
 850                         if (delegation != NULL) {
 851                                 delegation = nfs_detach_delegation(NFS_I(inode),
 852                                         delegation, server);
 853                                 if (delegation != NULL)
 854                                         nfs_free_delegation(delegation);
 855                         }
 856                         iput(inode);
 857                         nfs_sb_deactive(server->super);
 858                         goto restart;
 859                 }
 860         }
 861         rcu_read_unlock();
 862 }
 863
 864 /**
 865  * nfs_delegations_present - check for existence of delegations
 866  * @clp: client state handle
 867  *
 868  * Returns one if there are any nfs_delegation structures attached
 869  * to this nfs_client.
 870  */
 871 int nfs_delegations_present(struct nfs_client *clp)
 872 {
 873         struct nfs_server *server;
 874         int ret = 0;
 875
 876         rcu_read_lock();
 877         list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
 878                 if (!list_empty(&server->delegations)) {
 879                         ret = 1;
 880                         break;
 881                 }
 882         rcu_read_unlock();
 883         return ret;
 884 }
 885
 886 /**
 887  * nfs4_copy_delegation_stateid - Copy inode's state ID information
 888  * @dst: stateid data structure to fill in
 889  * @inode: inode to check
 890  * @flags: delegation type requirement
 891  *
 892  * Returns "true" and fills in "dst->data" * if inode had a delegation,
 893  * otherwise "false" is returned.
 894  */
 895 bool nfs4_copy_delegation_stateid(nfs4_stateid *dst, struct inode *inode,
 896                 fmode_t flags)
 897 {
 898         struct nfs_inode *nfsi = NFS_I(inode);
 899         struct nfs_delegation *delegation;
 900         bool ret;
 901
 902         flags &= FMODE_READ|FMODE_WRITE;
 903         rcu_read_lock();
 904         delegation = rcu_dereference(nfsi->delegation);
 905         ret = nfs4_is_valid_delegation(delegation, flags);
 906         if (ret) {
 907                 nfs4_stateid_copy(dst, &delegation->stateid);
 908                 nfs_mark_delegation_referenced(delegation);
 909         }
 910         rcu_read_unlock();
 911         return ret;
 912 }
 913
 914 /**
 915  * nfs4_delegation_flush_on_close - Check if we must flush file on close
 916  * @inode: inode to check
 917  *
 918  * This function checks the number of outstanding writes to the file
 919  * against the delegation 'space_limit' field to see if
 920  * the spec requires us to flush the file on close.
 921  */
 922 bool nfs4_delegation_flush_on_close(const struct inode *inode)
 923 {
 924         struct nfs_inode *nfsi = NFS_I(inode);
 925         struct nfs_delegation *delegation;
 926         bool ret = true;
 927
 928         rcu_read_lock();
 929         delegation = rcu_dereference(nfsi->delegation);
 930         if (delegation == NULL || !(delegation->type & FMODE_WRITE))
 931                 goto out;
 932         if (nfsi->nrequests < delegation->pagemod_limit)
 933                 ret = false;
 934 out:
 935         rcu_read_unlock();
 936         return ret;
 937 }