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/types.h>
  24 #include <linux/slab.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 #include <linux/kthread.h>
  34
  35 #define NLMDBG_FACILITY         NLMDBG_SVCLOCK
  36
  37 #ifdef CONFIG_LOCKD_V4
  38 #define nlm_deadlock    nlm4_deadlock
  39 #else
  40 #define nlm_deadlock    nlm_lck_denied
  41 #endif
  42
  43 static void nlmsvc_release_block(struct nlm_block *block);
  44 static void     nlmsvc_insert_block(struct nlm_block *block, unsigned long);
  45 static void     nlmsvc_remove_block(struct nlm_block *block);
  46
  47 static int nlmsvc_setgrantargs(struct nlm_rqst *call, struct nlm_lock *lock);
  48 static void nlmsvc_freegrantargs(struct nlm_rqst *call);
  49 static const struct rpc_call_ops nlmsvc_grant_ops;
  50
  51 /*
  52  * The list of blocked locks to retry
  53  */
  54 static LIST_HEAD(nlm_blocked);
  55
  56 /*
  57  * Insert a blocked lock into the global list
  58  */
  59 static void
  60 nlmsvc_insert_block(struct nlm_block *block, unsigned long when)
  61 {
  62         struct nlm_block *b;
  63         struct list_head *pos;
  64
  65         dprintk("lockd: nlmsvc_insert_block(%p, %ld)\n", block, when);
  66         if (list_empty(&block->b_list)) {
  67                 kref_get(&block->b_count);
  68         } else {
  69                 list_del_init(&block->b_list);
  70         }
  71
  72         pos = &nlm_blocked;
  73         if (when != NLM_NEVER) {
  74                 if ((when += jiffies) == NLM_NEVER)
  75                         when ++;
  76                 list_for_each(pos, &nlm_blocked) {
  77                         b = list_entry(pos, struct nlm_block, b_list);
  78                         if (time_after(b->b_when,when) || b->b_when == NLM_NEVER)
  79                                 break;
  80                 }
  81                 /* On normal exit from the loop, pos == &nlm_blocked,
  82                  * so we will be adding to the end of the list - good
  83                  */
  84         }
  85
  86         list_add_tail(&block->b_list, pos);
  87         block->b_when = when;
  88 }
  89
  90 /*
  91  * Remove a block from the global list
  92  */
  93 static inline void
  94 nlmsvc_remove_block(struct nlm_block *block)
  95 {
  96         if (!list_empty(&block->b_list)) {
  97                 list_del_init(&block->b_list);
  98                 nlmsvc_release_block(block);
  99         }
 100 }
 101
 102 /*
 103  * Find a block for a given lock
 104  */
 105 static struct nlm_block *
 106 nlmsvc_lookup_block(struct nlm_file *file, struct nlm_lock *lock)
 107 {
 108         struct nlm_block        *block;
 109         struct file_lock        *fl;
 110
 111         dprintk("lockd: nlmsvc_lookup_block f=%p pd=%d %Ld-%Ld ty=%d\n",
 112                                 file, lock->fl.fl_pid,
 113                                 (long long)lock->fl.fl_start,
 114                                 (long long)lock->fl.fl_end, lock->fl.fl_type);
 115         list_for_each_entry(block, &nlm_blocked, b_list) {
 116                 fl = &block->b_call->a_args.lock.fl;
 117                 dprintk("lockd: check f=%p pd=%d %Ld-%Ld ty=%d cookie=%s\n",
 118                                 block->b_file, fl->fl_pid,
 119                                 (long long)fl->fl_start,
 120                                 (long long)fl->fl_end, fl->fl_type,
 121                                 nlmdbg_cookie2a(&block->b_call->a_args.cookie));
 122                 if (block->b_file == file && nlm_compare_locks(fl, &lock->fl)) {
 123                         kref_get(&block->b_count);
 124                         return block;
 125                 }
 126         }
 127
 128         return NULL;
 129 }
 130
 131 static inline int nlm_cookie_match(struct nlm_cookie *a, struct nlm_cookie *b)
 132 {
 133         if (a->len != b->len)
 134                 return 0;
 135         if (memcmp(a->data, b->data, a->len))
 136                 return 0;
 137         return 1;
 138 }
 139
 140 /*
 141  * Find a block with a given NLM cookie.
 142  */
 143 static inline struct nlm_block *
 144 nlmsvc_find_block(struct nlm_cookie *cookie)
 145 {
 146         struct nlm_block *block;
 147
 148         list_for_each_entry(block, &nlm_blocked, b_list) {
 149                 if (nlm_cookie_match(&block->b_call->a_args.cookie,cookie))
 150                         goto found;
 151         }
 152
 153         return NULL;
 154
 155 found:
 156         dprintk("nlmsvc_find_block(%s): block=%p\n", nlmdbg_cookie2a(cookie), block);
 157         kref_get(&block->b_count);
 158         return block;
 159 }
 160
 161 /*
 162  * Create a block and initialize it.
 163  *
 164  * Note: we explicitly set the cookie of the grant reply to that of
 165  * the blocked lock request. The spec explicitly mentions that the client
 166  * should _not_ rely on the callback containing the same cookie as the
 167  * request, but (as I found out later) that's because some implementations
 168  * do just this. Never mind the standards comittees, they support our
 169  * logging industries.
 170  *
 171  * 10 years later: I hope we can safely ignore these old and broken
 172  * clients by now. Let's fix this so we can uniquely identify an incoming
 173  * GRANTED_RES message by cookie, without having to rely on the client's IP
 174  * address. --okir
 175  */
 176 static struct nlm_block *
 177 nlmsvc_create_block(struct svc_rqst *rqstp, struct nlm_host *host,
 178                     struct nlm_file *file, struct nlm_lock *lock,
 179                     struct nlm_cookie *cookie)
 180 {
 181         struct nlm_block        *block;
 182         struct nlm_rqst         *call = NULL;
 183
 184         nlm_get_host(host);
 185         call = nlm_alloc_call(host);
 186         if (call == NULL)
 187                 return NULL;
 188
 189         /* Allocate memory for block, and initialize arguments */
 190         block = kzalloc(sizeof(*block), GFP_KERNEL);
 191         if (block == NULL)
 192                 goto failed;
 193         kref_init(&block->b_count);
 194         INIT_LIST_HEAD(&block->b_list);
 195         INIT_LIST_HEAD(&block->b_flist);
 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         nlmclnt_next_cookie(&call->a_args.cookie);
 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         block->b_fl = NULL;
 212         file->f_count++;
 213
 214         /* Add to file's list of blocks */
 215         list_add(&block->b_flist, &file->f_blocks);
 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.
 233  * It is the caller's responsibility to check whether the file
 234  * can be closed hereafter.
 235  */
 236 static int nlmsvc_unlink_block(struct nlm_block *block)
 237 {
 238         int status;
 239         dprintk("lockd: unlinking block %p...\n", block);
 240
 241         /* Remove block from list */
 242         status = posix_unblock_lock(block->b_file->f_file, &block->b_call->a_args.lock.fl);
 243         nlmsvc_remove_block(block);
 244         return status;
 245 }
 246
 247 static void nlmsvc_free_block(struct kref *kref)
 248 {
 249         struct nlm_block *block = container_of(kref, struct nlm_block, b_count);
 250         struct nlm_file         *file = block->b_file;
 251
 252         dprintk("lockd: freeing block %p...\n", block);
 253
 254         /* Remove block from file's list of blocks */
 255         mutex_lock(&file->f_mutex);
 256         list_del_init(&block->b_flist);
 257         mutex_unlock(&file->f_mutex);
 258
 259         nlmsvc_freegrantargs(block->b_call);
 260         nlm_release_call(block->b_call);
 261         nlm_release_file(block->b_file);
 262         kfree(block->b_fl);
 263         kfree(block);
 264 }
 265
 266 static void nlmsvc_release_block(struct nlm_block *block)
 267 {
 268         if (block != NULL)
 269                 kref_put(&block->b_count, nlmsvc_free_block);
 270 }
 271
 272 /*
 273  * Loop over all blocks and delete blocks held by
 274  * a matching host.
 275  */
 276 void nlmsvc_traverse_blocks(struct nlm_host *host,
 277                         struct nlm_file *file,
 278                         nlm_host_match_fn_t match)
 279 {
 280         struct nlm_block *block, *next;
 281
 282 restart:
 283         mutex_lock(&file->f_mutex);
 284         list_for_each_entry_safe(block, next, &file->f_blocks, b_flist) {
 285                 if (!match(block->b_host, host))
 286                         continue;
 287                 /* Do not destroy blocks that are not on
 288                  * the global retry list - why? */
 289                 if (list_empty(&block->b_list))
 290                         continue;
 291                 kref_get(&block->b_count);
 292                 mutex_unlock(&file->f_mutex);
 293                 nlmsvc_unlink_block(block);
 294                 nlmsvc_release_block(block);
 295                 goto restart;
 296         }
 297         mutex_unlock(&file->f_mutex);
 298 }
 299
 300 /*
 301  * Initialize arguments for GRANTED call. The nlm_rqst structure
 302  * has been cleared already.
 303  */
 304 static int nlmsvc_setgrantargs(struct nlm_rqst *call, struct nlm_lock *lock)
 305 {
 306         locks_copy_lock(&call->a_args.lock.fl, &lock->fl);
 307         memcpy(&call->a_args.lock.fh, &lock->fh, sizeof(call->a_args.lock.fh));
 308         call->a_args.lock.caller = utsname()->nodename;
 309         call->a_args.lock.oh.len = lock->oh.len;
 310
 311         /* set default data area */
 312         call->a_args.lock.oh.data = call->a_owner;
 313         call->a_args.lock.svid = lock->fl.fl_pid;
 314
 315         if (lock->oh.len > NLMCLNT_OHSIZE) {
 316                 void *data = kmalloc(lock->oh.len, GFP_KERNEL);
 317                 if (!data)
 318                         return 0;
 319                 call->a_args.lock.oh.data = (u8 *) data;
 320         }
 321
 322         memcpy(call->a_args.lock.oh.data, lock->oh.data, lock->oh.len);
 323         return 1;
 324 }
 325
 326 static void nlmsvc_freegrantargs(struct nlm_rqst *call)
 327 {
 328         if (call->a_args.lock.oh.data != call->a_owner)
 329                 kfree(call->a_args.lock.oh.data);
 330
 331         locks_release_private(&call->a_args.lock.fl);
 332 }
 333
 334 /*
 335  * Deferred lock request handling for non-blocking lock
 336  */
 337 static __be32
 338 nlmsvc_defer_lock_rqst(struct svc_rqst *rqstp, struct nlm_block *block)
 339 {
 340         __be32 status = nlm_lck_denied_nolocks;
 341
 342         block->b_flags |= B_QUEUED;
 343
 344         nlmsvc_insert_block(block, NLM_TIMEOUT);
 345
 346         block->b_cache_req = &rqstp->rq_chandle;
 347         if (rqstp->rq_chandle.defer) {
 348                 block->b_deferred_req =
 349                         rqstp->rq_chandle.defer(block->b_cache_req);
 350                 if (block->b_deferred_req != NULL)
 351                         status = nlm_drop_reply;
 352         }
 353         dprintk("lockd: nlmsvc_defer_lock_rqst block %p flags %d status %d\n",
 354                 block, block->b_flags, ntohl(status));
 355
 356         return status;
 357 }
 358
 359 /*
 360  * Attempt to establish a lock, and if it can't be granted, block it
 361  * if required.
 362  */
 363 __be32
 364 nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file,
 365             struct nlm_host *host, struct nlm_lock *lock, int wait,
 366             struct nlm_cookie *cookie, int reclaim)
 367 {
 368         struct nlm_block        *block = NULL;
 369         int                     error;
 370         __be32                  ret;
 371
 372         dprintk("lockd: nlmsvc_lock(%s/%ld, ty=%d, pi=%d, %Ld-%Ld, bl=%d)\n",
 373                                 file->f_file->f_path.dentry->d_inode->i_sb->s_id,
 374                                 file->f_file->f_path.dentry->d_inode->i_ino,
 375                                 lock->fl.fl_type, lock->fl.fl_pid,
 376                                 (long long)lock->fl.fl_start,
 377                                 (long long)lock->fl.fl_end,
 378                                 wait);
 379
 380         /* Lock file against concurrent access */
 381         mutex_lock(&file->f_mutex);
 382         /* Get existing block (in case client is busy-waiting)
 383          * or create new block
 384          */
 385         block = nlmsvc_lookup_block(file, lock);
 386         if (block == NULL) {
 387                 block = nlmsvc_create_block(rqstp, host, file, lock, cookie);
 388                 ret = nlm_lck_denied_nolocks;
 389                 if (block == NULL)
 390                         goto out;
 391                 lock = &block->b_call->a_args.lock;
 392         } else
 393                 lock->fl.fl_flags &= ~FL_SLEEP;
 394
 395         if (block->b_flags & B_QUEUED) {
 396                 dprintk("lockd: nlmsvc_lock deferred block %p flags %d\n",
 397                                                         block, block->b_flags);
 398                 if (block->b_granted) {
 399                         nlmsvc_unlink_block(block);
 400                         ret = nlm_granted;
 401                         goto out;
 402                 }
 403                 if (block->b_flags & B_TIMED_OUT) {
 404                         nlmsvc_unlink_block(block);
 405                         ret = nlm_lck_denied;
 406                         goto out;
 407                 }
 408                 ret = nlm_drop_reply;
 409                 goto out;
 410         }
 411
 412         if (locks_in_grace() && !reclaim) {
 413                 ret = nlm_lck_denied_grace_period;
 414                 goto out;
 415         }
 416         if (reclaim && !locks_in_grace()) {
 417                 ret = nlm_lck_denied_grace_period;
 418                 goto out;
 419         }
 420
 421         if (!wait)
 422                 lock->fl.fl_flags &= ~FL_SLEEP;
 423         error = vfs_lock_file(file->f_file, F_SETLK, &lock->fl, NULL);
 424         lock->fl.fl_flags &= ~FL_SLEEP;
 425
 426         dprintk("lockd: vfs_lock_file returned %d\n", error);
 427         switch (error) {
 428                 case 0:
 429                         ret = nlm_granted;
 430                         goto out;
 431                 case -EAGAIN:
 432                         /*
 433                          * If this is a blocking request for an
 434                          * already pending lock request then we need
 435                          * to put it back on lockd's block list
 436                          */
 437                         if (wait)
 438                                 break;
 439                         ret = nlm_lck_denied;
 440                         goto out;
 441                 case FILE_LOCK_DEFERRED:
 442                         if (wait)
 443                                 break;
 444                         /* Filesystem lock operation is in progress
 445                            Add it to the queue waiting for callback */
 446                         ret = nlmsvc_defer_lock_rqst(rqstp, block);
 447                         goto out;
 448                 case -EDEADLK:
 449                         ret = nlm_deadlock;
 450                         goto out;
 451                 default:                        /* includes ENOLCK */
 452                         ret = nlm_lck_denied_nolocks;
 453                         goto out;
 454         }
 455
 456         ret = nlm_lck_blocked;
 457
 458         /* Append to list of blocked */
 459         nlmsvc_insert_block(block, NLM_NEVER);
 460 out:
 461         mutex_unlock(&file->f_mutex);
 462         nlmsvc_release_block(block);
 463         dprintk("lockd: nlmsvc_lock returned %u\n", ret);
 464         return ret;
 465 }
 466
 467 /*
 468  * Test for presence of a conflicting lock.
 469  */
 470 __be32
 471 nlmsvc_testlock(struct svc_rqst *rqstp, struct nlm_file *file,
 472                 struct nlm_host *host, struct nlm_lock *lock,
 473                 struct nlm_lock *conflock, struct nlm_cookie *cookie)
 474 {
 475         struct nlm_block        *block = NULL;
 476         int                     error;
 477         __be32                  ret;
 478
 479         dprintk("lockd: nlmsvc_testlock(%s/%ld, ty=%d, %Ld-%Ld)\n",
 480                                 file->f_file->f_path.dentry->d_inode->i_sb->s_id,
 481                                 file->f_file->f_path.dentry->d_inode->i_ino,
 482                                 lock->fl.fl_type,
 483                                 (long long)lock->fl.fl_start,
 484                                 (long long)lock->fl.fl_end);
 485
 486         /* Get existing block (in case client is busy-waiting) */
 487         block = nlmsvc_lookup_block(file, lock);
 488
 489         if (block == NULL) {
 490                 struct file_lock *conf = kzalloc(sizeof(*conf), GFP_KERNEL);
 491
 492                 if (conf == NULL)
 493                         return nlm_granted;
 494                 block = nlmsvc_create_block(rqstp, host, file, lock, cookie);
 495                 if (block == NULL) {
 496                         kfree(conf);
 497                         return nlm_granted;
 498                 }
 499                 block->b_fl = conf;
 500         }
 501         if (block->b_flags & B_QUEUED) {
 502                 dprintk("lockd: nlmsvc_testlock deferred block %p flags %d fl %p\n",
 503                         block, block->b_flags, block->b_fl);
 504                 if (block->b_flags & B_TIMED_OUT) {
 505                         nlmsvc_unlink_block(block);
 506                         ret = nlm_lck_denied;
 507                         goto out;
 508                 }
 509                 if (block->b_flags & B_GOT_CALLBACK) {
 510                         nlmsvc_unlink_block(block);
 511                         if (block->b_fl != NULL
 512                                         && block->b_fl->fl_type != F_UNLCK) {
 513                                 lock->fl = *block->b_fl;
 514                                 goto conf_lock;
 515                         } else {
 516                                 ret = nlm_granted;
 517                                 goto out;
 518                         }
 519                 }
 520                 ret = nlm_drop_reply;
 521                 goto out;
 522         }
 523
 524         if (locks_in_grace()) {
 525                 ret = nlm_lck_denied_grace_period;
 526                 goto out;
 527         }
 528         error = vfs_test_lock(file->f_file, &lock->fl);
 529         if (error == FILE_LOCK_DEFERRED) {
 530                 ret = nlmsvc_defer_lock_rqst(rqstp, block);
 531                 goto out;
 532         }
 533         if (error) {
 534                 ret = nlm_lck_denied_nolocks;
 535                 goto out;
 536         }
 537         if (lock->fl.fl_type == F_UNLCK) {
 538                 ret = nlm_granted;
 539                 goto out;
 540         }
 541
 542 conf_lock:
 543         dprintk("lockd: conflicting lock(ty=%d, %Ld-%Ld)\n",
 544                 lock->fl.fl_type, (long long)lock->fl.fl_start,
 545                 (long long)lock->fl.fl_end);
 546         conflock->caller = "somehost";  /* FIXME */
 547         conflock->len = strlen(conflock->caller);
 548         conflock->oh.len = 0;           /* don't return OH info */
 549         conflock->svid = lock->fl.fl_pid;
 550         conflock->fl.fl_type = lock->fl.fl_type;
 551         conflock->fl.fl_start = lock->fl.fl_start;
 552         conflock->fl.fl_end = lock->fl.fl_end;
 553         ret = nlm_lck_denied;
 554 out:
 555         if (block)
 556                 nlmsvc_release_block(block);
 557         return ret;
 558 }
 559
 560 /*
 561  * Remove a lock.
 562  * This implies a CANCEL call: We send a GRANT_MSG, the client replies
 563  * with a GRANT_RES call which gets lost, and calls UNLOCK immediately
 564  * afterwards. In this case the block will still be there, and hence
 565  * must be removed.
 566  */
 567 __be32
 568 nlmsvc_unlock(struct nlm_file *file, struct nlm_lock *lock)
 569 {
 570         int     error;
 571
 572         dprintk("lockd: nlmsvc_unlock(%s/%ld, pi=%d, %Ld-%Ld)\n",
 573                                 file->f_file->f_path.dentry->d_inode->i_sb->s_id,
 574                                 file->f_file->f_path.dentry->d_inode->i_ino,
 575                                 lock->fl.fl_pid,
 576                                 (long long)lock->fl.fl_start,
 577                                 (long long)lock->fl.fl_end);
 578
 579         /* First, cancel any lock that might be there */
 580         nlmsvc_cancel_blocked(file, lock);
 581
 582         lock->fl.fl_type = F_UNLCK;
 583         error = vfs_lock_file(file->f_file, F_SETLK, &lock->fl, NULL);
 584
 585         return (error < 0)? nlm_lck_denied_nolocks : nlm_granted;
 586 }
 587
 588 /*
 589  * Cancel a previously blocked request.
 590  *
 591  * A cancel request always overrides any grant that may currently
 592  * be in progress.
 593  * The calling procedure must check whether the file can be closed.
 594  */
 595 __be32
 596 nlmsvc_cancel_blocked(struct nlm_file *file, struct nlm_lock *lock)
 597 {
 598         struct nlm_block        *block;
 599         int status = 0;
 600
 601         dprintk("lockd: nlmsvc_cancel(%s/%ld, pi=%d, %Ld-%Ld)\n",
 602                                 file->f_file->f_path.dentry->d_inode->i_sb->s_id,
 603                                 file->f_file->f_path.dentry->d_inode->i_ino,
 604                                 lock->fl.fl_pid,
 605                                 (long long)lock->fl.fl_start,
 606                                 (long long)lock->fl.fl_end);
 607
 608         if (locks_in_grace())
 609                 return nlm_lck_denied_grace_period;
 610
 611         mutex_lock(&file->f_mutex);
 612         block = nlmsvc_lookup_block(file, lock);
 613         mutex_unlock(&file->f_mutex);
 614         if (block != NULL) {
 615                 vfs_cancel_lock(block->b_file->f_file,
 616                                 &block->b_call->a_args.lock.fl);
 617                 status = nlmsvc_unlink_block(block);
 618                 nlmsvc_release_block(block);
 619         }
 620         return status ? nlm_lck_denied : nlm_granted;
 621 }
 622
 623 /*
 624  * This is a callback from the filesystem for VFS file lock requests.
 625  * It will be used if fl_grant is defined and the filesystem can not
 626  * respond to the request immediately.
 627  * For GETLK request it will copy the reply to the nlm_block.
 628  * For SETLK or SETLKW request it will get the local posix lock.
 629  * In all cases it will move the block to the head of nlm_blocked q where
 630  * nlmsvc_retry_blocked() can send back a reply for SETLKW or revisit the
 631  * deferred rpc for GETLK and SETLK.
 632  */
 633 static void
 634 nlmsvc_update_deferred_block(struct nlm_block *block, struct file_lock *conf,
 635                              int result)
 636 {
 637         block->b_flags |= B_GOT_CALLBACK;
 638         if (result == 0)
 639                 block->b_granted = 1;
 640         else
 641                 block->b_flags |= B_TIMED_OUT;
 642         if (conf) {
 643                 if (block->b_fl)
 644                         __locks_copy_lock(block->b_fl, conf);
 645         }
 646 }
 647
 648 static int nlmsvc_grant_deferred(struct file_lock *fl, struct file_lock *conf,
 649                                         int result)
 650 {
 651         struct nlm_block *block;
 652         int rc = -ENOENT;
 653
 654         lock_kernel();
 655         list_for_each_entry(block, &nlm_blocked, b_list) {
 656                 if (nlm_compare_locks(&block->b_call->a_args.lock.fl, fl)) {
 657                         dprintk("lockd: nlmsvc_notify_blocked block %p flags %d\n",
 658                                                         block, block->b_flags);
 659                         if (block->b_flags & B_QUEUED) {
 660                                 if (block->b_flags & B_TIMED_OUT) {
 661                                         rc = -ENOLCK;
 662                                         break;
 663                                 }
 664                                 nlmsvc_update_deferred_block(block, conf, result);
 665                         } else if (result == 0)
 666                                 block->b_granted = 1;
 667
 668                         nlmsvc_insert_block(block, 0);
 669                         svc_wake_up(block->b_daemon);
 670                         rc = 0;
 671                         break;
 672                 }
 673         }
 674         unlock_kernel();
 675         if (rc == -ENOENT)
 676                 printk(KERN_WARNING "lockd: grant for unknown block\n");
 677         return rc;
 678 }
 679
 680 /*
 681  * Unblock a blocked lock request. This is a callback invoked from the
 682  * VFS layer when a lock on which we blocked is removed.
 683  *
 684  * This function doesn't grant the blocked lock instantly, but rather moves
 685  * the block to the head of nlm_blocked where it can be picked up by lockd.
 686  */
 687 static void
 688 nlmsvc_notify_blocked(struct file_lock *fl)
 689 {
 690         struct nlm_block        *block;
 691
 692         dprintk("lockd: VFS unblock notification for block %p\n", fl);
 693         list_for_each_entry(block, &nlm_blocked, b_list) {
 694                 if (nlm_compare_locks(&block->b_call->a_args.lock.fl, fl)) {
 695                         nlmsvc_insert_block(block, 0);
 696                         svc_wake_up(block->b_daemon);
 697                         return;
 698                 }
 699         }
 700
 701         printk(KERN_WARNING "lockd: notification for unknown block!\n");
 702 }
 703
 704 static int nlmsvc_same_owner(struct file_lock *fl1, struct file_lock *fl2)
 705 {
 706         return fl1->fl_owner == fl2->fl_owner && fl1->fl_pid == fl2->fl_pid;
 707 }
 708
 709 const struct lock_manager_operations nlmsvc_lock_operations = {
 710         .fl_compare_owner = nlmsvc_same_owner,
 711         .fl_notify = nlmsvc_notify_blocked,
 712         .fl_grant = nlmsvc_grant_deferred,
 713 };
 714
 715 /*
 716  * Try to claim a lock that was previously blocked.
 717  *
 718  * Note that we use both the RPC_GRANTED_MSG call _and_ an async
 719  * RPC thread when notifying the client. This seems like overkill...
 720  * Here's why:
 721  *  -   we don't want to use a synchronous RPC thread, otherwise
 722  *      we might find ourselves hanging on a dead portmapper.
 723  *  -   Some lockd implementations (e.g. HP) don't react to
 724  *      RPC_GRANTED calls; they seem to insist on RPC_GRANTED_MSG calls.
 725  */
 726 static void
 727 nlmsvc_grant_blocked(struct nlm_block *block)
 728 {
 729         struct nlm_file         *file = block->b_file;
 730         struct nlm_lock         *lock = &block->b_call->a_args.lock;
 731         int                     error;
 732
 733         dprintk("lockd: grant blocked lock %p\n", block);
 734
 735         kref_get(&block->b_count);
 736
 737         /* Unlink block request from list */
 738         nlmsvc_unlink_block(block);
 739
 740         /* If b_granted is true this means we've been here before.
 741          * Just retry the grant callback, possibly refreshing the RPC
 742          * binding */
 743         if (block->b_granted) {
 744                 nlm_rebind_host(block->b_host);
 745                 goto callback;
 746         }
 747
 748         /* Try the lock operation again */
 749         lock->fl.fl_flags |= FL_SLEEP;
 750         error = vfs_lock_file(file->f_file, F_SETLK, &lock->fl, NULL);
 751         lock->fl.fl_flags &= ~FL_SLEEP;
 752
 753         switch (error) {
 754         case 0:
 755                 break;
 756         case FILE_LOCK_DEFERRED:
 757                 dprintk("lockd: lock still blocked error %d\n", error);
 758                 nlmsvc_insert_block(block, NLM_NEVER);
 759                 nlmsvc_release_block(block);
 760                 return;
 761         default:
 762                 printk(KERN_WARNING "lockd: unexpected error %d in %s!\n",
 763                                 -error, __func__);
 764                 nlmsvc_insert_block(block, 10 * HZ);
 765                 nlmsvc_release_block(block);
 766                 return;
 767         }
 768
 769 callback:
 770         /* Lock was granted by VFS. */
 771         dprintk("lockd: GRANTing blocked lock.\n");
 772         block->b_granted = 1;
 773
 774         /* keep block on the list, but don't reattempt until the RPC
 775          * completes or the submission fails
 776          */
 777         nlmsvc_insert_block(block, NLM_NEVER);
 778
 779         /* Call the client -- use a soft RPC task since nlmsvc_retry_blocked
 780          * will queue up a new one if this one times out
 781          */
 782         error = nlm_async_call(block->b_call, NLMPROC_GRANTED_MSG,
 783                                 &nlmsvc_grant_ops);
 784
 785         /* RPC submission failed, wait a bit and retry */
 786         if (error < 0)
 787                 nlmsvc_insert_block(block, 10 * HZ);
 788 }
 789
 790 /*
 791  * This is the callback from the RPC layer when the NLM_GRANTED_MSG
 792  * RPC call has succeeded or timed out.
 793  * Like all RPC callbacks, it is invoked by the rpciod process, so it
 794  * better not sleep. Therefore, we put the blocked lock on the nlm_blocked
 795  * chain once more in order to have it removed by lockd itself (which can
 796  * then sleep on the file semaphore without disrupting e.g. the nfs client).
 797  */
 798 static void nlmsvc_grant_callback(struct rpc_task *task, void *data)
 799 {
 800         struct nlm_rqst         *call = data;
 801         struct nlm_block        *block = call->a_block;
 802         unsigned long           timeout;
 803
 804         dprintk("lockd: GRANT_MSG RPC callback\n");
 805
 806         lock_kernel();
 807         /* if the block is not on a list at this point then it has
 808          * been invalidated. Don't try to requeue it.
 809          *
 810          * FIXME: it's possible that the block is removed from the list
 811          * after this check but before the nlmsvc_insert_block. In that
 812          * case it will be added back. Perhaps we need better locking
 813          * for nlm_blocked?
 814          */
 815         if (list_empty(&block->b_list))
 816                 goto out;
 817
 818         /* Technically, we should down the file semaphore here. Since we
 819          * move the block towards the head of the queue only, no harm
 820          * can be done, though. */
 821         if (task->tk_status < 0) {
 822                 /* RPC error: Re-insert for retransmission */
 823                 timeout = 10 * HZ;
 824         } else {
 825                 /* Call was successful, now wait for client callback */
 826                 timeout = 60 * HZ;
 827         }
 828         nlmsvc_insert_block(block, timeout);
 829         svc_wake_up(block->b_daemon);
 830 out:
 831         unlock_kernel();
 832 }
 833
 834 static void nlmsvc_grant_release(void *data)
 835 {
 836         struct nlm_rqst         *call = data;
 837
 838         lock_kernel();
 839         nlmsvc_release_block(call->a_block);
 840         unlock_kernel();
 841 }
 842
 843 static const struct rpc_call_ops nlmsvc_grant_ops = {
 844         .rpc_call_done = nlmsvc_grant_callback,
 845         .rpc_release = nlmsvc_grant_release,
 846 };
 847
 848 /*
 849  * We received a GRANT_RES callback. Try to find the corresponding
 850  * block.
 851  */
 852 void
 853 nlmsvc_grant_reply(struct nlm_cookie *cookie, __be32 status)
 854 {
 855         struct nlm_block        *block;
 856
 857         dprintk("grant_reply: looking for cookie %x, s=%d \n",
 858                 *(unsigned int *)(cookie->data), status);
 859         if (!(block = nlmsvc_find_block(cookie)))
 860                 return;
 861
 862         if (block) {
 863                 if (status == nlm_lck_denied_grace_period) {
 864                         /* Try again in a couple of seconds */
 865                         nlmsvc_insert_block(block, 10 * HZ);
 866                 } else {
 867                         /* Lock is now held by client, or has been rejected.
 868                          * In both cases, the block should be removed. */
 869                         nlmsvc_unlink_block(block);
 870                 }
 871         }
 872         nlmsvc_release_block(block);
 873 }
 874
 875 /* Helper function to handle retry of a deferred block.
 876  * If it is a blocking lock, call grant_blocked.
 877  * For a non-blocking lock or test lock, revisit the request.
 878  */
 879 static void
 880 retry_deferred_block(struct nlm_block *block)
 881 {
 882         if (!(block->b_flags & B_GOT_CALLBACK))
 883                 block->b_flags |= B_TIMED_OUT;
 884         nlmsvc_insert_block(block, NLM_TIMEOUT);
 885         dprintk("revisit block %p flags %d\n",  block, block->b_flags);
 886         if (block->b_deferred_req) {
 887                 block->b_deferred_req->revisit(block->b_deferred_req, 0);
 888                 block->b_deferred_req = NULL;
 889         }
 890 }
 891
 892 /*
 893  * Retry all blocked locks that have been notified. This is where lockd
 894  * picks up locks that can be granted, or grant notifications that must
 895  * be retransmitted.
 896  */
 897 unsigned long
 898 nlmsvc_retry_blocked(void)
 899 {
 900         unsigned long   timeout = MAX_SCHEDULE_TIMEOUT;
 901         struct nlm_block *block;
 902
 903         while (!list_empty(&nlm_blocked) && !kthread_should_stop()) {
 904                 block = list_entry(nlm_blocked.next, struct nlm_block, b_list);
 905
 906                 if (block->b_when == NLM_NEVER)
 907                         break;
 908                 if (time_after(block->b_when, jiffies)) {
 909                         timeout = block->b_when - jiffies;
 910                         break;
 911                 }
 912
 913                 dprintk("nlmsvc_retry_blocked(%p, when=%ld)\n",
 914                         block, block->b_when);
 915                 if (block->b_flags & B_QUEUED) {
 916                         dprintk("nlmsvc_retry_blocked delete block (%p, granted=%d, flags=%d)\n",
 917                                 block, block->b_granted, block->b_flags);
 918                         retry_deferred_block(block);
 919                 } else
 920                         nlmsvc_grant_blocked(block);
 921         }
 922
 923         return timeout;
 924 }