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