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