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