git.oblomov.eu Git - linux-2.6/blob - fs/lockd/svclock.c

   1 /*
   2  * linux/fs/lockd/svclock.c
   3  *
   4  * Handling of server-side locks, mostly of the blocked variety.
   5  * This is the ugliest part of lockd because we tread on very thin ice.
   6  * GRANT and CANCEL calls may get stuck, meet in mid-flight, etc.
   7  * IMNSHO introducing the grant callback into the NLM protocol was one
   8  * of the worst ideas Sun ever had. Except maybe for the idea of doing
   9  * NFS file locking at all.
  10  *
  11  * I'm trying hard to avoid race conditions by protecting most accesses
  12  * to a file's list of blocked locks through a semaphore. The global
  13  * list of blocked locks is not protected in this fashion however.
  14  * Therefore, some functions (such as the RPC callback for the async grant
  15  * call) move blocked locks towards the head of the list *while some other
  16  * process might be traversing it*. This should not be a problem in
  17  * practice, because this will only cause functions traversing the list
  18  * to visit some blocks twice.
  19  *
  20  * Copyright (C) 1996, Olaf Kirch <okir@monad.swb.de>
  21  */
  22
  23 #include <linux/config.h>
  24 #include <linux/types.h>
  25 #include <linux/errno.h>
  26 #include <linux/kernel.h>
  27 #include <linux/sched.h>
  28 #include <linux/smp_lock.h>
  29 #include <linux/sunrpc/clnt.h>
  30 #include <linux/sunrpc/svc.h>
  31 #include <linux/lockd/nlm.h>
  32 #include <linux/lockd/lockd.h>
  33
  34 #define NLMDBG_FACILITY         NLMDBG_SVCLOCK
  35
  36 #ifdef CONFIG_LOCKD_V4
  37 #define nlm_deadlock    nlm4_deadlock
  38 #else
  39 #define nlm_deadlock    nlm_lck_denied
  40 #endif
  41
  42 static void nlmsvc_release_block(struct nlm_block *block);
  43 static void     nlmsvc_insert_block(struct nlm_block *block, unsigned long);
  44 static int      nlmsvc_remove_block(struct nlm_block *block);
  45
  46 static int nlmsvc_setgrantargs(struct nlm_rqst *call, struct nlm_lock *lock);
  47 static void nlmsvc_freegrantargs(struct nlm_rqst *call);
  48 static const struct rpc_call_ops nlmsvc_grant_ops;
  49
  50 /*
  51  * The list of blocked locks to retry
  52  */
  53 static struct nlm_block *       nlm_blocked;
  54
  55 /*
  56  * Insert a blocked lock into the global list
  57  */
  58 static void
  59 nlmsvc_insert_block(struct nlm_block *block, unsigned long when)
  60 {
  61         struct nlm_block **bp, *b;
  62
  63         dprintk("lockd: nlmsvc_insert_block(%p, %ld)\n", block, when);
  64         kref_get(&block->b_count);
  65         if (block->b_queued)
  66                 nlmsvc_remove_block(block);
  67         bp = &nlm_blocked;
  68         if (when != NLM_NEVER) {
  69                 if ((when += jiffies) == NLM_NEVER)
  70                         when ++;
  71                 while ((b = *bp) && time_before_eq(b->b_when,when) && b->b_when != NLM_NEVER)
  72                         bp = &b->b_next;
  73         } else
  74                 while ((b = *bp) != 0)
  75                         bp = &b->b_next;
  76
  77         block->b_queued = 1;
  78         block->b_when = when;
  79         block->b_next = b;
  80         *bp = block;
  81 }
  82
  83 /*
  84  * Remove a block from the global list
  85  */
  86 static int
  87 nlmsvc_remove_block(struct nlm_block *block)
  88 {
  89         struct nlm_block **bp, *b;
  90
  91         if (!block->b_queued)
  92                 return 1;
  93         for (bp = &nlm_blocked; (b = *bp) != 0; bp = &b->b_next) {
  94                 if (b == block) {
  95                         *bp = block->b_next;
  96                         block->b_queued = 0;
  97                         nlmsvc_release_block(block);
  98                         return 1;
  99                 }
 100         }
 101
 102         return 0;
 103 }
 104
 105 /*
 106  * Find a block for a given lock
 107  */
 108 static struct nlm_block *
 109 nlmsvc_lookup_block(struct nlm_file *file, struct nlm_lock *lock)
 110 {
 111         struct nlm_block        **head, *block;
 112         struct file_lock        *fl;
 113
 114         dprintk("lockd: nlmsvc_lookup_block f=%p pd=%d %Ld-%Ld ty=%d\n",
 115                                 file, lock->fl.fl_pid,
 116                                 (long long)lock->fl.fl_start,
 117                                 (long long)lock->fl.fl_end, lock->fl.fl_type);
 118         for (head = &nlm_blocked; (block = *head) != 0; head = &block->b_next) {
 119                 fl = &block->b_call->a_args.lock.fl;
 120                 dprintk("lockd: check f=%p pd=%d %Ld-%Ld ty=%d cookie=%s\n",
 121                                 block->b_file, fl->fl_pid,
 122                                 (long long)fl->fl_start,
 123                                 (long long)fl->fl_end, fl->fl_type,
 124                                 nlmdbg_cookie2a(&block->b_call->a_args.cookie));
 125                 if (block->b_file == file && nlm_compare_locks(fl, &lock->fl)) {
 126                         kref_get(&block->b_count);
 127                         return block;
 128                 }
 129         }
 130
 131         return NULL;
 132 }
 133
 134 static inline int nlm_cookie_match(struct nlm_cookie *a, struct nlm_cookie *b)
 135 {
 136         if(a->len != b->len)
 137                 return 0;
 138         if(memcmp(a->data,b->data,a->len))
 139                 return 0;
 140         return 1;
 141 }
 142
 143 /*
 144  * Find a block with a given NLM cookie.
 145  */
 146 static inline struct nlm_block *
 147 nlmsvc_find_block(struct nlm_cookie *cookie,  struct sockaddr_in *sin)
 148 {
 149         struct nlm_block *block;
 150
 151         for (block = nlm_blocked; block; block = block->b_next) {
 152                 dprintk("cookie: head of blocked queue %p, block %p\n",
 153                         nlm_blocked, block);
 154                 if (nlm_cookie_match(&block->b_call->a_args.cookie,cookie)
 155                                 && nlm_cmp_addr(sin, &block->b_host->h_addr))
 156                         break;
 157         }
 158
 159         if (block != NULL)
 160                 kref_get(&block->b_count);
 161         return block;
 162 }
 163
 164 /*
 165  * Create a block and initialize it.
 166  *
 167  * Note: we explicitly set the cookie of the grant reply to that of
 168  * the blocked lock request. The spec explicitly mentions that the client
 169  * should _not_ rely on the callback containing the same cookie as the
 170  * request, but (as I found out later) that's because some implementations
 171  * do just this. Never mind the standards comittees, they support our
 172  * logging industries.
 173  */
 174 static inline struct nlm_block *
 175 nlmsvc_create_block(struct svc_rqst *rqstp, struct nlm_file *file,
 176                                 struct nlm_lock *lock, struct nlm_cookie *cookie)
 177 {
 178         struct nlm_block        *block;
 179         struct nlm_host         *host;
 180         struct nlm_rqst         *call = NULL;
 181
 182         /* Create host handle for callback */
 183         host = nlmsvc_lookup_host(rqstp);
 184         if (host == NULL)
 185                 return NULL;
 186
 187         call = nlm_alloc_call(host);
 188         if (call == NULL)
 189                 return NULL;
 190
 191         /* Allocate memory for block, and initialize arguments */
 192         block = kzalloc(sizeof(*block), GFP_KERNEL);
 193         if (block == NULL)
 194                 goto failed;
 195         kref_init(&block->b_count);
 196
 197         if (!nlmsvc_setgrantargs(call, lock))
 198                 goto failed_free;
 199
 200         /* Set notifier function for VFS, and init args */
 201         call->a_args.lock.fl.fl_flags |= FL_SLEEP;
 202         call->a_args.lock.fl.fl_lmops = &nlmsvc_lock_operations;
 203         call->a_args.cookie = *cookie;  /* see above */
 204
 205         dprintk("lockd: created block %p...\n", block);
 206
 207         /* Create and initialize the block */
 208         block->b_daemon = rqstp->rq_server;
 209         block->b_host   = host;
 210         block->b_file   = file;
 211         file->f_count++;
 212
 213         /* Add to file's list of blocks */
 214         block->b_fnext  = file->f_blocks;
 215         file->f_blocks  = block;
 216
 217         /* Set up RPC arguments for callback */
 218         block->b_call = call;
 219         call->a_flags   = RPC_TASK_ASYNC;
 220         call->a_block = block;
 221
 222         return block;
 223
 224 failed_free:
 225         kfree(block);
 226 failed:
 227         nlm_release_call(call);
 228         return NULL;
 229 }
 230
 231 /*
 232  * Delete a block. If the lock was cancelled or the grant callback
 233  * failed, unlock is set to 1.
 234  * It is the caller's responsibility to check whether the file
 235  * can be closed hereafter.
 236  */
 237 static int nlmsvc_unlink_block(struct nlm_block *block)
 238 {
 239         int status;
 240         dprintk("lockd: unlinking block %p...\n", block);
 241
 242         /* Remove block from list */
 243         status = posix_unblock_lock(block->b_file->f_file, &block->b_call->a_args.lock.fl);
 244         nlmsvc_remove_block(block);
 245         return status;
 246 }
 247
 248 static void nlmsvc_free_block(struct kref *kref)
 249 {
 250         struct nlm_block *block = container_of(kref, struct nlm_block, b_count);
 251         struct nlm_file         *file = block->b_file;
 252         struct nlm_block        **bp;
 253
 254         dprintk("lockd: freeing block %p...\n", block);
 255
 256         down(&file->f_sema);
 257         /* Remove block from file's list of blocks */
 258         for (bp = &file->f_blocks; *bp; bp = &(*bp)->b_fnext) {
 259                 if (*bp == block) {
 260                         *bp = block->b_fnext;
 261                         break;
 262                 }
 263         }
 264         up(&file->f_sema);
 265
 266         nlmsvc_freegrantargs(block->b_call);
 267         nlm_release_call(block->b_call);
 268         nlm_release_file(block->b_file);
 269         kfree(block);
 270 }
 271
 272 static void nlmsvc_release_block(struct nlm_block *block)
 273 {
 274         if (block != NULL)
 275                 kref_put(&block->b_count, nlmsvc_free_block);
 276 }
 277
 278 static void nlmsvc_act_mark(struct nlm_host *host, struct nlm_file *file)
 279 {
 280         struct nlm_block *block;
 281
 282         down(&file->f_sema);
 283         for (block = file->f_blocks; block != NULL; block = block->b_fnext)
 284                 block->b_host->h_inuse = 1;
 285         up(&file->f_sema);
 286 }
 287
 288 static void nlmsvc_act_unlock(struct nlm_host *host, struct nlm_file *file)
 289 {
 290         struct nlm_block *block;
 291
 292 restart:
 293         down(&file->f_sema);
 294         for (block = file->f_blocks; block != NULL; block = block->b_fnext) {
 295                 if (host != NULL && host != block->b_host)
 296                         continue;
 297                 if (!block->b_queued)
 298                         continue;
 299                 kref_get(&block->b_count);
 300                 up(&file->f_sema);
 301                 nlmsvc_unlink_block(block);
 302                 nlmsvc_release_block(block);
 303                 goto restart;
 304         }
 305         up(&file->f_sema);
 306 }
 307
 308 /*
 309  * Loop over all blocks and perform the action specified.
 310  * (NLM_ACT_CHECK handled by nlmsvc_inspect_file).
 311  */
 312 void
 313 nlmsvc_traverse_blocks(struct nlm_host *host, struct nlm_file *file, int action)
 314 {
 315         if (action == NLM_ACT_MARK)
 316                 nlmsvc_act_mark(host, file);
 317         else
 318                 nlmsvc_act_unlock(host, file);
 319 }
 320
 321 /*
 322  * Initialize arguments for GRANTED call. The nlm_rqst structure
 323  * has been cleared already.
 324  */
 325 static int nlmsvc_setgrantargs(struct nlm_rqst *call, struct nlm_lock *lock)
 326 {
 327         locks_copy_lock(&call->a_args.lock.fl, &lock->fl);
 328         memcpy(&call->a_args.lock.fh, &lock->fh, sizeof(call->a_args.lock.fh));
 329         call->a_args.lock.caller = system_utsname.nodename;
 330         call->a_args.lock.oh.len = lock->oh.len;
 331
 332         /* set default data area */
 333         call->a_args.lock.oh.data = call->a_owner;
 334         call->a_args.lock.svid = lock->fl.fl_pid;
 335
 336         if (lock->oh.len > NLMCLNT_OHSIZE) {
 337                 void *data = kmalloc(lock->oh.len, GFP_KERNEL);
 338                 if (!data)
 339                         return 0;
 340                 call->a_args.lock.oh.data = (u8 *) data;
 341         }
 342
 343         memcpy(call->a_args.lock.oh.data, lock->oh.data, lock->oh.len);
 344         return 1;
 345 }
 346
 347 static void nlmsvc_freegrantargs(struct nlm_rqst *call)
 348 {
 349         if (call->a_args.lock.oh.data != call->a_owner)
 350                 kfree(call->a_args.lock.oh.data);
 351 }
 352
 353 /*
 354  * Attempt to establish a lock, and if it can't be granted, block it
 355  * if required.
 356  */
 357 u32
 358 nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file,
 359                         struct nlm_lock *lock, int wait, struct nlm_cookie *cookie)
 360 {
 361         struct nlm_block        *block, *newblock = NULL;
 362         int                     error;
 363         u32                     ret;
 364
 365         dprintk("lockd: nlmsvc_lock(%s/%ld, ty=%d, pi=%d, %Ld-%Ld, bl=%d)\n",
 366                                 file->f_file->f_dentry->d_inode->i_sb->s_id,
 367                                 file->f_file->f_dentry->d_inode->i_ino,
 368                                 lock->fl.fl_type, lock->fl.fl_pid,
 369                                 (long long)lock->fl.fl_start,
 370                                 (long long)lock->fl.fl_end,
 371                                 wait);
 372
 373
 374         lock->fl.fl_flags &= ~FL_SLEEP;
 375 again:
 376         /* Lock file against concurrent access */
 377         down(&file->f_sema);
 378         /* Get existing block (in case client is busy-waiting) */
 379         block = nlmsvc_lookup_block(file, lock);
 380         if (block == NULL) {
 381                 if (newblock != NULL)
 382                         lock = &newblock->b_call->a_args.lock;
 383         } else
 384                 lock = &block->b_call->a_args.lock;
 385
 386         error = posix_lock_file(file->f_file, &lock->fl);
 387         lock->fl.fl_flags &= ~FL_SLEEP;
 388
 389         dprintk("lockd: posix_lock_file returned %d\n", error);
 390
 391         switch(error) {
 392                 case 0:
 393                         ret = nlm_granted;
 394                         goto out;
 395                 case -EAGAIN:
 396                         break;
 397                 case -EDEADLK:
 398                         ret = nlm_deadlock;
 399                         goto out;
 400                 default:                        /* includes ENOLCK */
 401                         ret = nlm_lck_denied_nolocks;
 402                         goto out;
 403         }
 404
 405         ret = nlm_lck_denied;
 406         if (!wait)
 407                 goto out;
 408
 409         ret = nlm_lck_blocked;
 410         if (block != NULL)
 411                 goto out;
 412
 413         /* If we don't have a block, create and initialize it. Then
 414          * retry because we may have slept in kmalloc. */
 415         /* We have to release f_sema as nlmsvc_create_block may try to
 416          * to claim it while doing host garbage collection */
 417         if (newblock == NULL) {
 418                 up(&file->f_sema);
 419                 dprintk("lockd: blocking on this lock (allocating).\n");
 420                 if (!(newblock = nlmsvc_create_block(rqstp, file, lock, cookie)))
 421                         return nlm_lck_denied_nolocks;
 422                 goto again;
 423         }
 424
 425         /* Append to list of blocked */
 426         nlmsvc_insert_block(newblock, NLM_NEVER);
 427 out:
 428         up(&file->f_sema);
 429         nlmsvc_release_block(newblock);
 430         nlmsvc_release_block(block);
 431         dprintk("lockd: nlmsvc_lock returned %u\n", ret);
 432         return ret;
 433 }
 434
 435 /*
 436  * Test for presence of a conflicting lock.
 437  */
 438 u32
 439 nlmsvc_testlock(struct nlm_file *file, struct nlm_lock *lock,
 440                                        struct nlm_lock *conflock)
 441 {
 442         dprintk("lockd: nlmsvc_testlock(%s/%ld, ty=%d, %Ld-%Ld)\n",
 443                                 file->f_file->f_dentry->d_inode->i_sb->s_id,
 444                                 file->f_file->f_dentry->d_inode->i_ino,
 445                                 lock->fl.fl_type,
 446                                 (long long)lock->fl.fl_start,
 447                                 (long long)lock->fl.fl_end);
 448
 449         if (posix_test_lock(file->f_file, &lock->fl, &conflock->fl)) {
 450                 dprintk("lockd: conflicting lock(ty=%d, %Ld-%Ld)\n",
 451                                 conflock->fl.fl_type,
 452                                 (long long)conflock->fl.fl_start,
 453                                 (long long)conflock->fl.fl_end);
 454                 conflock->caller = "somehost";  /* FIXME */
 455                 conflock->oh.len = 0;           /* don't return OH info */
 456                 conflock->svid = conflock->fl.fl_pid;
 457                 return nlm_lck_denied;
 458         }
 459
 460         return nlm_granted;
 461 }
 462
 463 /*
 464  * Remove a lock.
 465  * This implies a CANCEL call: We send a GRANT_MSG, the client replies
 466  * with a GRANT_RES call which gets lost, and calls UNLOCK immediately
 467  * afterwards. In this case the block will still be there, and hence
 468  * must be removed.
 469  */
 470 u32
 471 nlmsvc_unlock(struct nlm_file *file, struct nlm_lock *lock)
 472 {
 473         int     error;
 474
 475         dprintk("lockd: nlmsvc_unlock(%s/%ld, pi=%d, %Ld-%Ld)\n",
 476                                 file->f_file->f_dentry->d_inode->i_sb->s_id,
 477                                 file->f_file->f_dentry->d_inode->i_ino,
 478                                 lock->fl.fl_pid,
 479                                 (long long)lock->fl.fl_start,
 480                                 (long long)lock->fl.fl_end);
 481
 482         /* First, cancel any lock that might be there */
 483         nlmsvc_cancel_blocked(file, lock);
 484
 485         lock->fl.fl_type = F_UNLCK;
 486         error = posix_lock_file(file->f_file, &lock->fl);
 487
 488         return (error < 0)? nlm_lck_denied_nolocks : nlm_granted;
 489 }
 490
 491 /*
 492  * Cancel a previously blocked request.
 493  *
 494  * A cancel request always overrides any grant that may currently
 495  * be in progress.
 496  * The calling procedure must check whether the file can be closed.
 497  */
 498 u32
 499 nlmsvc_cancel_blocked(struct nlm_file *file, struct nlm_lock *lock)
 500 {
 501         struct nlm_block        *block;
 502         int status = 0;
 503
 504         dprintk("lockd: nlmsvc_cancel(%s/%ld, pi=%d, %Ld-%Ld)\n",
 505                                 file->f_file->f_dentry->d_inode->i_sb->s_id,
 506                                 file->f_file->f_dentry->d_inode->i_ino,
 507                                 lock->fl.fl_pid,
 508                                 (long long)lock->fl.fl_start,
 509                                 (long long)lock->fl.fl_end);
 510
 511         down(&file->f_sema);
 512         block = nlmsvc_lookup_block(file, lock);
 513         up(&file->f_sema);
 514         if (block != NULL) {
 515                 status = nlmsvc_unlink_block(block);
 516                 nlmsvc_release_block(block);
 517         }
 518         return status ? nlm_lck_denied : nlm_granted;
 519 }
 520
 521 /*
 522  * Unblock a blocked lock request. This is a callback invoked from the
 523  * VFS layer when a lock on which we blocked is removed.
 524  *
 525  * This function doesn't grant the blocked lock instantly, but rather moves
 526  * the block to the head of nlm_blocked where it can be picked up by lockd.
 527  */
 528 static void
 529 nlmsvc_notify_blocked(struct file_lock *fl)
 530 {
 531         struct nlm_block        **bp, *block;
 532
 533         dprintk("lockd: VFS unblock notification for block %p\n", fl);
 534         for (bp = &nlm_blocked; (block = *bp) != 0; bp = &block->b_next) {
 535                 if (nlm_compare_locks(&block->b_call->a_args.lock.fl, fl)) {
 536                         nlmsvc_insert_block(block, 0);
 537                         svc_wake_up(block->b_daemon);
 538                         return;
 539                 }
 540         }
 541
 542         printk(KERN_WARNING "lockd: notification for unknown block!\n");
 543 }
 544
 545 static int nlmsvc_same_owner(struct file_lock *fl1, struct file_lock *fl2)
 546 {
 547         return fl1->fl_owner == fl2->fl_owner && fl1->fl_pid == fl2->fl_pid;
 548 }
 549
 550 struct lock_manager_operations nlmsvc_lock_operations = {
 551         .fl_compare_owner = nlmsvc_same_owner,
 552         .fl_notify = nlmsvc_notify_blocked,
 553 };
 554
 555 /*
 556  * Try to claim a lock that was previously blocked.
 557  *
 558  * Note that we use both the RPC_GRANTED_MSG call _and_ an async
 559  * RPC thread when notifying the client. This seems like overkill...
 560  * Here's why:
 561  *  -   we don't want to use a synchronous RPC thread, otherwise
 562  *      we might find ourselves hanging on a dead portmapper.
 563  *  -   Some lockd implementations (e.g. HP) don't react to
 564  *      RPC_GRANTED calls; they seem to insist on RPC_GRANTED_MSG calls.
 565  */
 566 static void
 567 nlmsvc_grant_blocked(struct nlm_block *block)
 568 {
 569         struct nlm_file         *file = block->b_file;
 570         struct nlm_lock         *lock = &block->b_call->a_args.lock;
 571         int                     error;
 572
 573         dprintk("lockd: grant blocked lock %p\n", block);
 574
 575         /* Unlink block request from list */
 576         nlmsvc_unlink_block(block);
 577
 578         /* If b_granted is true this means we've been here before.
 579          * Just retry the grant callback, possibly refreshing the RPC
 580          * binding */
 581         if (block->b_granted) {
 582                 nlm_rebind_host(block->b_host);
 583                 goto callback;
 584         }
 585
 586         /* Try the lock operation again */
 587         lock->fl.fl_flags |= FL_SLEEP;
 588         error = posix_lock_file(file->f_file, &lock->fl);
 589         lock->fl.fl_flags &= ~FL_SLEEP;
 590
 591         switch (error) {
 592         case 0:
 593                 break;
 594         case -EAGAIN:
 595                 dprintk("lockd: lock still blocked\n");
 596                 nlmsvc_insert_block(block, NLM_NEVER);
 597                 return;
 598         default:
 599                 printk(KERN_WARNING "lockd: unexpected error %d in %s!\n",
 600                                 -error, __FUNCTION__);
 601                 nlmsvc_insert_block(block, 10 * HZ);
 602                 return;
 603         }
 604
 605 callback:
 606         /* Lock was granted by VFS. */
 607         dprintk("lockd: GRANTing blocked lock.\n");
 608         block->b_granted = 1;
 609
 610         /* Schedule next grant callback in 30 seconds */
 611         nlmsvc_insert_block(block, 30 * HZ);
 612
 613         /* Call the client */
 614         kref_get(&block->b_count);
 615         if (nlm_async_call(block->b_call, NLMPROC_GRANTED_MSG,
 616                                                 &nlmsvc_grant_ops) < 0)
 617                 nlmsvc_release_block(block);
 618 }
 619
 620 /*
 621  * This is the callback from the RPC layer when the NLM_GRANTED_MSG
 622  * RPC call has succeeded or timed out.
 623  * Like all RPC callbacks, it is invoked by the rpciod process, so it
 624  * better not sleep. Therefore, we put the blocked lock on the nlm_blocked
 625  * chain once more in order to have it removed by lockd itself (which can
 626  * then sleep on the file semaphore without disrupting e.g. the nfs client).
 627  */
 628 static void nlmsvc_grant_callback(struct rpc_task *task, void *data)
 629 {
 630         struct nlm_rqst         *call = data;
 631         struct nlm_block        *block = call->a_block;
 632         unsigned long           timeout;
 633
 634         dprintk("lockd: GRANT_MSG RPC callback\n");
 635
 636         /* Technically, we should down the file semaphore here. Since we
 637          * move the block towards the head of the queue only, no harm
 638          * can be done, though. */
 639         if (task->tk_status < 0) {
 640                 /* RPC error: Re-insert for retransmission */
 641                 timeout = 10 * HZ;
 642         } else if (block->b_done) {
 643                 /* Block already removed, kill it for real */
 644                 timeout = 0;
 645         } else {
 646                 /* Call was successful, now wait for client callback */
 647                 timeout = 60 * HZ;
 648         }
 649         nlmsvc_insert_block(block, timeout);
 650         svc_wake_up(block->b_daemon);
 651 }
 652
 653 static void nlmsvc_grant_release(void *data)
 654 {
 655         struct nlm_rqst         *call = data;
 656
 657         nlmsvc_release_block(call->a_block);
 658 }
 659
 660 static const struct rpc_call_ops nlmsvc_grant_ops = {
 661         .rpc_call_done = nlmsvc_grant_callback,
 662         .rpc_release = nlmsvc_grant_release,
 663 };
 664
 665 /*
 666  * We received a GRANT_RES callback. Try to find the corresponding
 667  * block.
 668  */
 669 void
 670 nlmsvc_grant_reply(struct svc_rqst *rqstp, struct nlm_cookie *cookie, u32 status)
 671 {
 672         struct nlm_block        *block;
 673         struct nlm_file         *file;
 674
 675         dprintk("grant_reply: looking for cookie %x, host (%08x), s=%d \n",
 676                 *(unsigned int *)(cookie->data),
 677                 ntohl(rqstp->rq_addr.sin_addr.s_addr), status);
 678         if (!(block = nlmsvc_find_block(cookie, &rqstp->rq_addr)))
 679                 return;
 680         file = block->b_file;
 681
 682         if (block) {
 683                 if (status == NLM_LCK_DENIED_GRACE_PERIOD) {
 684                         /* Try again in a couple of seconds */
 685                         nlmsvc_insert_block(block, 10 * HZ);
 686                 } else {
 687                         /* Lock is now held by client, or has been rejected.
 688                          * In both cases, the block should be removed. */
 689                         nlmsvc_unlink_block(block);
 690                 }
 691         }
 692         nlmsvc_release_block(block);
 693 }
 694
 695 /*
 696  * Retry all blocked locks that have been notified. This is where lockd
 697  * picks up locks that can be granted, or grant notifications that must
 698  * be retransmitted.
 699  */
 700 unsigned long
 701 nlmsvc_retry_blocked(void)
 702 {
 703         struct nlm_block        *block;
 704
 705         dprintk("nlmsvc_retry_blocked(%p, when=%ld)\n",
 706                         nlm_blocked,
 707                         nlm_blocked? nlm_blocked->b_when : 0);
 708         while ((block = nlm_blocked) != 0) {
 709                 if (block->b_when == NLM_NEVER)
 710                         break;
 711                 if (time_after(block->b_when,jiffies))
 712                         break;
 713                 dprintk("nlmsvc_retry_blocked(%p, when=%ld, done=%d)\n",
 714                         block, block->b_when, block->b_done);
 715                 kref_get(&block->b_count);
 716                 if (block->b_done)
 717                         nlmsvc_unlink_block(block);
 718                 else
 719                         nlmsvc_grant_blocked(block);
 720                 nlmsvc_release_block(block);
 721         }
 722
 723         if ((block = nlm_blocked) && block->b_when != NLM_NEVER)
 724                 return (block->b_when - jiffies);
 725
 726         return MAX_SCHEDULE_TIMEOUT;
 727 }