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/errno.h>
  25 #include <linux/kernel.h>
  26 #include <linux/sched.h>
  27 #include <linux/smp_lock.h>
  28 #include <linux/sunrpc/clnt.h>
  29 #include <linux/sunrpc/svc.h>
  30 #include <linux/lockd/nlm.h>
  31 #include <linux/lockd/lockd.h>
  32 #include <linux/kthread.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 void     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 LIST_HEAD(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 *b;
  62         struct list_head *pos;
  63
  64         dprintk("lockd: nlmsvc_insert_block(%p, %ld)\n", block, when);
  65         if (list_empty(&block->b_list)) {
  66                 kref_get(&block->b_count);
  67         } else {
  68                 list_del_init(&block->b_list);
  69         }
  70
  71         pos = &nlm_blocked;
  72         if (when != NLM_NEVER) {
  73                 if ((when += jiffies) == NLM_NEVER)
  74                         when ++;
  75                 list_for_each(pos, &nlm_blocked) {
  76                         b = list_entry(pos, struct nlm_block, b_list);
  77                         if (time_after(b->b_when,when) || b->b_when == NLM_NEVER)
  78                                 break;
  79                 }
  80                 /* On normal exit from the loop, pos == &nlm_blocked,
  81                  * so we will be adding to the end of the list - good
  82                  */
  83         }
  84
  85         list_add_tail(&block->b_list, pos);
  86         block->b_when = when;
  87 }
  88
  89 /*
  90  * Remove a block from the global list
  91  */
  92 static inline void
  93 nlmsvc_remove_block(struct nlm_block *block)
  94 {
  95         if (!list_empty(&block->b_list)) {
  96                 list_del_init(&block->b_list);
  97                 nlmsvc_release_block(block);
  98         }
  99 }
 100
 101 /*
 102  * Find a block for a given lock
 103  */
 104 static struct nlm_block *
 105 nlmsvc_lookup_block(struct nlm_file *file, struct nlm_lock *lock)
 106 {
 107         struct nlm_block        *block;
 108         struct file_lock        *fl;
 109
 110         dprintk("lockd: nlmsvc_lookup_block f=%p pd=%d %Ld-%Ld ty=%d\n",
 111                                 file, lock->fl.fl_pid,
 112                                 (long long)lock->fl.fl_start,
 113                                 (long long)lock->fl.fl_end, lock->fl.fl_type);
 114         list_for_each_entry(block, &nlm_blocked, b_list) {
 115                 fl = &block->b_call->a_args.lock.fl;
 116                 dprintk("lockd: check f=%p pd=%d %Ld-%Ld ty=%d cookie=%s\n",
 117                                 block->b_file, fl->fl_pid,
 118                                 (long long)fl->fl_start,
 119                                 (long long)fl->fl_end, fl->fl_type,
 120                                 nlmdbg_cookie2a(&block->b_call->a_args.cookie));
 121                 if (block->b_file == file && nlm_compare_locks(fl, &lock->fl)) {
 122                         kref_get(&block->b_count);
 123                         return block;
 124                 }
 125         }
 126
 127         return NULL;
 128 }
 129
 130 static inline int nlm_cookie_match(struct nlm_cookie *a, struct nlm_cookie *b)
 131 {
 132         if (a->len != b->len)
 133                 return 0;
 134         if (memcmp(a->data, b->data, a->len))
 135                 return 0;
 136         return 1;
 137 }
 138
 139 /*
 140  * Find a block with a given NLM cookie.
 141  */
 142 static inline struct nlm_block *
 143 nlmsvc_find_block(struct nlm_cookie *cookie)
 144 {
 145         struct nlm_block *block;
 146
 147         list_for_each_entry(block, &nlm_blocked, b_list) {
 148                 if (nlm_cookie_match(&block->b_call->a_args.cookie,cookie))
 149                         goto found;
 150         }
 151
 152         return NULL;
 153
 154 found:
 155         dprintk("nlmsvc_find_block(%s): block=%p\n", nlmdbg_cookie2a(cookie), block);
 156         kref_get(&block->b_count);
 157         return block;
 158 }
 159
 160 /*
 161  * Create a block and initialize it.
 162  *
 163  * Note: we explicitly set the cookie of the grant reply to that of
 164  * the blocked lock request. The spec explicitly mentions that the client
 165  * should _not_ rely on the callback containing the same cookie as the
 166  * request, but (as I found out later) that's because some implementations
 167  * do just this. Never mind the standards comittees, they support our
 168  * logging industries.
 169  *
 170  * 10 years later: I hope we can safely ignore these old and broken
 171  * clients by now. Let's fix this so we can uniquely identify an incoming
 172  * GRANTED_RES message by cookie, without having to rely on the client's IP
 173  * address. --okir
 174  */
 175 static struct nlm_block *
 176 nlmsvc_create_block(struct svc_rqst *rqstp, struct nlm_host *host,
 177                     struct nlm_file *file, struct nlm_lock *lock,
 178                     struct nlm_cookie *cookie)
 179 {
 180         struct nlm_block        *block;
 181         struct nlm_rqst         *call = NULL;
 182
 183         call = nlm_alloc_call(host);
 184         if (call == NULL)
 185                 return NULL;
 186
 187         /* Allocate memory for block, and initialize arguments */
 188         block = kzalloc(sizeof(*block), GFP_KERNEL);
 189         if (block == NULL)
 190                 goto failed;
 191         kref_init(&block->b_count);
 192         INIT_LIST_HEAD(&block->b_list);
 193         INIT_LIST_HEAD(&block->b_flist);
 194
 195         if (!nlmsvc_setgrantargs(call, lock))
 196                 goto failed_free;
 197
 198         /* Set notifier function for VFS, and init args */
 199         call->a_args.lock.fl.fl_flags |= FL_SLEEP;
 200         call->a_args.lock.fl.fl_lmops = &nlmsvc_lock_operations;
 201         nlmclnt_next_cookie(&call->a_args.cookie);
 202
 203         dprintk("lockd: created block %p...\n", block);
 204
 205         /* Create and initialize the block */
 206         block->b_daemon = rqstp->rq_server;
 207         block->b_host   = host;
 208         block->b_file   = file;
 209         block->b_fl = NULL;
 210         file->f_count++;
 211
 212         /* Add to file's list of blocks */
 213         list_add(&block->b_flist, &file->f_blocks);
 214
 215         /* Set up RPC arguments for callback */
 216         block->b_call = call;
 217         call->a_flags   = RPC_TASK_ASYNC;
 218         call->a_block = block;
 219
 220         return block;
 221
 222 failed_free:
 223         kfree(block);
 224 failed:
 225         nlm_release_call(call);
 226         return NULL;
 227 }
 228
 229 /*
 230  * Delete a block.
 231  * It is the caller's responsibility to check whether the file
 232  * can be closed hereafter.
 233  */
 234 static int nlmsvc_unlink_block(struct nlm_block *block)
 235 {
 236         int status;
 237         dprintk("lockd: unlinking block %p...\n", block);
 238
 239         /* Remove block from list */
 240         status = posix_unblock_lock(block->b_file->f_file, &block->b_call->a_args.lock.fl);
 241         nlmsvc_remove_block(block);
 242         return status;
 243 }
 244
 245 static void nlmsvc_free_block(struct kref *kref)
 246 {
 247         struct nlm_block *block = container_of(kref, struct nlm_block, b_count);
 248         struct nlm_file         *file = block->b_file;
 249
 250         dprintk("lockd: freeing block %p...\n", block);
 251
 252         /* Remove block from file's list of blocks */
 253         mutex_lock(&file->f_mutex);
 254         list_del_init(&block->b_flist);
 255         mutex_unlock(&file->f_mutex);
 256
 257         nlmsvc_freegrantargs(block->b_call);
 258         nlm_release_call(block->b_call);
 259         nlm_release_file(block->b_file);
 260         kfree(block->b_fl);
 261         kfree(block);
 262 }
 263
 264 static void nlmsvc_release_block(struct nlm_block *block)
 265 {
 266         if (block != NULL)
 267                 kref_put(&block->b_count, nlmsvc_free_block);
 268 }
 269
 270 /*
 271  * Loop over all blocks and delete blocks held by
 272  * a matching host.
 273  */
 274 void nlmsvc_traverse_blocks(struct nlm_host *host,
 275                         struct nlm_file *file,
 276                         nlm_host_match_fn_t match)
 277 {
 278         struct nlm_block *block, *next;
 279
 280 restart:
 281         mutex_lock(&file->f_mutex);
 282         list_for_each_entry_safe(block, next, &file->f_blocks, b_flist) {
 283                 if (!match(block->b_host, host))
 284                         continue;
 285                 /* Do not destroy blocks that are not on
 286                  * the global retry list - why? */
 287                 if (list_empty(&block->b_list))
 288                         continue;
 289                 kref_get(&block->b_count);
 290                 mutex_unlock(&file->f_mutex);
 291                 nlmsvc_unlink_block(block);
 292                 nlmsvc_release_block(block);
 293                 goto restart;
 294         }
 295         mutex_unlock(&file->f_mutex);
 296 }
 297
 298 /*
 299  * Initialize arguments for GRANTED call. The nlm_rqst structure
 300  * has been cleared already.
 301  */
 302 static int nlmsvc_setgrantargs(struct nlm_rqst *call, struct nlm_lock *lock)
 303 {
 304         locks_copy_lock(&call->a_args.lock.fl, &lock->fl);
 305         memcpy(&call->a_args.lock.fh, &lock->fh, sizeof(call->a_args.lock.fh));
 306         call->a_args.lock.caller = utsname()->nodename;
 307         call->a_args.lock.oh.len = lock->oh.len;
 308
 309         /* set default data area */
 310         call->a_args.lock.oh.data = call->a_owner;
 311         call->a_args.lock.svid = lock->fl.fl_pid;
 312
 313         if (lock->oh.len > NLMCLNT_OHSIZE) {
 314                 void *data = kmalloc(lock->oh.len, GFP_KERNEL);
 315                 if (!data)
 316                         return 0;
 317                 call->a_args.lock.oh.data = (u8 *) data;
 318         }
 319
 320         memcpy(call->a_args.lock.oh.data, lock->oh.data, lock->oh.len);
 321         return 1;
 322 }
 323
 324 static void nlmsvc_freegrantargs(struct nlm_rqst *call)
 325 {
 326         if (call->a_args.lock.oh.data != call->a_owner)
 327                 kfree(call->a_args.lock.oh.data);
 328 }
 329
 330 /*
 331  * Deferred lock request handling for non-blocking lock
 332  */
 333 static __be32
 334 nlmsvc_defer_lock_rqst(struct svc_rqst *rqstp, struct nlm_block *block)
 335 {
 336         __be32 status = nlm_lck_denied_nolocks;
 337
 338         block->b_flags |= B_QUEUED;
 339
 340         nlmsvc_insert_block(block, NLM_TIMEOUT);
 341
 342         block->b_cache_req = &rqstp->rq_chandle;
 343         if (rqstp->rq_chandle.defer) {
 344                 block->b_deferred_req =
 345                         rqstp->rq_chandle.defer(block->b_cache_req);
 346                 if (block->b_deferred_req != NULL)
 347                         status = nlm_drop_reply;
 348         }
 349         dprintk("lockd: nlmsvc_defer_lock_rqst block %p flags %d status %d\n",
 350                 block, block->b_flags, ntohl(status));
 351
 352         return status;
 353 }
 354
 355 /*
 356  * Attempt to establish a lock, and if it can't be granted, block it
 357  * if required.
 358  */
 359 __be32
 360 nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file,
 361             struct nlm_host *host, struct nlm_lock *lock, int wait,
 362             struct nlm_cookie *cookie)
 363 {
 364         struct nlm_block        *block = NULL;
 365         int                     error;
 366         __be32                  ret;
 367
 368         dprintk("lockd: nlmsvc_lock(%s/%ld, ty=%d, pi=%d, %Ld-%Ld, bl=%d)\n",
 369                                 file->f_file->f_path.dentry->d_inode->i_sb->s_id,
 370                                 file->f_file->f_path.dentry->d_inode->i_ino,
 371                                 lock->fl.fl_type, lock->fl.fl_pid,
 372                                 (long long)lock->fl.fl_start,
 373                                 (long long)lock->fl.fl_end,
 374                                 wait);
 375
 376         /* Lock file against concurrent access */
 377         mutex_lock(&file->f_mutex);
 378         /* Get existing block (in case client is busy-waiting)
 379          * or create new block
 380          */
 381         block = nlmsvc_lookup_block(file, lock);
 382         if (block == NULL) {
 383                 block = nlmsvc_create_block(rqstp, nlm_get_host(host), file,
 384                                             lock, cookie);
 385                 ret = nlm_lck_denied_nolocks;
 386                 if (block == NULL)
 387                         goto out;
 388                 lock = &block->b_call->a_args.lock;
 389         } else
 390                 lock->fl.fl_flags &= ~FL_SLEEP;
 391
 392         if (block->b_flags & B_QUEUED) {
 393                 dprintk("lockd: nlmsvc_lock deferred block %p flags %d\n",
 394                                                         block, block->b_flags);
 395                 if (block->b_granted) {
 396                         nlmsvc_unlink_block(block);
 397                         ret = nlm_granted;
 398                         goto out;
 399                 }
 400                 if (block->b_flags & B_TIMED_OUT) {
 401                         nlmsvc_unlink_block(block);
 402                         ret = nlm_lck_denied;
 403                         goto out;
 404                 }
 405                 ret = nlm_drop_reply;
 406                 goto out;
 407         }
 408
 409         if (!wait)
 410                 lock->fl.fl_flags &= ~FL_SLEEP;
 411         error = vfs_lock_file(file->f_file, F_SETLK, &lock->fl, NULL);
 412         lock->fl.fl_flags &= ~FL_SLEEP;
 413
 414         dprintk("lockd: vfs_lock_file returned %d\n", error);
 415         switch (error) {
 416                 case 0:
 417                         ret = nlm_granted;
 418                         goto out;
 419                 case -EAGAIN:
 420                         ret = nlm_lck_denied;
 421                         break;
 422                 case -EINPROGRESS:
 423                         if (wait)
 424                                 break;
 425                         /* Filesystem lock operation is in progress
 426                            Add it to the queue waiting for callback */
 427                         ret = nlmsvc_defer_lock_rqst(rqstp, block);
 428                         goto out;
 429                 case -EDEADLK:
 430                         ret = nlm_deadlock;
 431                         goto out;
 432                 default:                        /* includes ENOLCK */
 433                         ret = nlm_lck_denied_nolocks;
 434                         goto out;
 435         }
 436
 437         ret = nlm_lck_denied;
 438         if (!wait)
 439                 goto out;
 440
 441         ret = nlm_lck_blocked;
 442
 443         /* Append to list of blocked */
 444         nlmsvc_insert_block(block, NLM_NEVER);
 445 out:
 446         mutex_unlock(&file->f_mutex);
 447         nlmsvc_release_block(block);
 448         dprintk("lockd: nlmsvc_lock returned %u\n", ret);
 449         return ret;
 450 }
 451
 452 /*
 453  * Test for presence of a conflicting lock.
 454  */
 455 __be32
 456 nlmsvc_testlock(struct svc_rqst *rqstp, struct nlm_file *file,
 457                 struct nlm_host *host, struct nlm_lock *lock,
 458                 struct nlm_lock *conflock, struct nlm_cookie *cookie)
 459 {
 460         struct nlm_block        *block = NULL;
 461         int                     error;
 462         __be32                  ret;
 463
 464         dprintk("lockd: nlmsvc_testlock(%s/%ld, ty=%d, %Ld-%Ld)\n",
 465                                 file->f_file->f_path.dentry->d_inode->i_sb->s_id,
 466                                 file->f_file->f_path.dentry->d_inode->i_ino,
 467                                 lock->fl.fl_type,
 468                                 (long long)lock->fl.fl_start,
 469                                 (long long)lock->fl.fl_end);
 470
 471         /* Get existing block (in case client is busy-waiting) */
 472         block = nlmsvc_lookup_block(file, lock);
 473
 474         if (block == NULL) {
 475                 struct file_lock *conf = kzalloc(sizeof(*conf), GFP_KERNEL);
 476
 477                 if (conf == NULL)
 478                         return nlm_granted;
 479                 nlm_get_host(host);
 480                 block = nlmsvc_create_block(rqstp, host, file, lock, cookie);
 481                 if (block == NULL) {
 482                         kfree(conf);
 483                         return nlm_granted;
 484                 }
 485                 block->b_fl = conf;
 486         }
 487         if (block->b_flags & B_QUEUED) {
 488                 dprintk("lockd: nlmsvc_testlock deferred block %p flags %d fl %p\n",
 489                         block, block->b_flags, block->b_fl);
 490                 if (block->b_flags & B_TIMED_OUT) {
 491                         nlmsvc_unlink_block(block);
 492                         ret = nlm_lck_denied;
 493                         goto out;
 494                 }
 495                 if (block->b_flags & B_GOT_CALLBACK) {
 496                         nlmsvc_unlink_block(block);
 497                         if (block->b_fl != NULL
 498                                         && block->b_fl->fl_type != F_UNLCK) {
 499                                 lock->fl = *block->b_fl;
 500                                 goto conf_lock;
 501                         } else {
 502                                 ret = nlm_granted;
 503                                 goto out;
 504                         }
 505                 }
 506                 ret = nlm_drop_reply;
 507                 goto out;
 508         }
 509
 510         error = vfs_test_lock(file->f_file, &lock->fl);
 511         if (error == -EINPROGRESS) {
 512                 ret = nlmsvc_defer_lock_rqst(rqstp, block);
 513                 goto out;
 514         }
 515         if (error) {
 516                 ret = nlm_lck_denied_nolocks;
 517                 goto out;
 518         }
 519         if (lock->fl.fl_type == F_UNLCK) {
 520                 ret = nlm_granted;
 521                 goto out;
 522         }
 523
 524 conf_lock:
 525         dprintk("lockd: conflicting lock(ty=%d, %Ld-%Ld)\n",
 526                 lock->fl.fl_type, (long long)lock->fl.fl_start,
 527                 (long long)lock->fl.fl_end);
 528         conflock->caller = "somehost";  /* FIXME */
 529         conflock->len = strlen(conflock->caller);
 530         conflock->oh.len = 0;           /* don't return OH info */
 531         conflock->svid = lock->fl.fl_pid;
 532         conflock->fl.fl_type = lock->fl.fl_type;
 533         conflock->fl.fl_start = lock->fl.fl_start;
 534         conflock->fl.fl_end = lock->fl.fl_end;
 535         ret = nlm_lck_denied;
 536 out:
 537         if (block)
 538                 nlmsvc_release_block(block);
 539         return ret;
 540 }
 541
 542 /*
 543  * Remove a lock.
 544  * This implies a CANCEL call: We send a GRANT_MSG, the client replies
 545  * with a GRANT_RES call which gets lost, and calls UNLOCK immediately
 546  * afterwards. In this case the block will still be there, and hence
 547  * must be removed.
 548  */
 549 __be32
 550 nlmsvc_unlock(struct nlm_file *file, struct nlm_lock *lock)
 551 {
 552         int     error;
 553
 554         dprintk("lockd: nlmsvc_unlock(%s/%ld, pi=%d, %Ld-%Ld)\n",
 555                                 file->f_file->f_path.dentry->d_inode->i_sb->s_id,
 556                                 file->f_file->f_path.dentry->d_inode->i_ino,
 557                                 lock->fl.fl_pid,
 558                                 (long long)lock->fl.fl_start,
 559                                 (long long)lock->fl.fl_end);
 560
 561         /* First, cancel any lock that might be there */
 562         nlmsvc_cancel_blocked(file, lock);
 563
 564         lock->fl.fl_type = F_UNLCK;
 565         error = vfs_lock_file(file->f_file, F_SETLK, &lock->fl, NULL);
 566
 567         return (error < 0)? nlm_lck_denied_nolocks : nlm_granted;
 568 }
 569
 570 /*
 571  * Cancel a previously blocked request.
 572  *
 573  * A cancel request always overrides any grant that may currently
 574  * be in progress.
 575  * The calling procedure must check whether the file can be closed.
 576  */
 577 __be32
 578 nlmsvc_cancel_blocked(struct nlm_file *file, struct nlm_lock *lock)
 579 {
 580         struct nlm_block        *block;
 581         int status = 0;
 582
 583         dprintk("lockd: nlmsvc_cancel(%s/%ld, pi=%d, %Ld-%Ld)\n",
 584                                 file->f_file->f_path.dentry->d_inode->i_sb->s_id,
 585                                 file->f_file->f_path.dentry->d_inode->i_ino,
 586                                 lock->fl.fl_pid,
 587                                 (long long)lock->fl.fl_start,
 588                                 (long long)lock->fl.fl_end);
 589
 590         mutex_lock(&file->f_mutex);
 591         block = nlmsvc_lookup_block(file, lock);
 592         mutex_unlock(&file->f_mutex);
 593         if (block != NULL) {
 594                 vfs_cancel_lock(block->b_file->f_file,
 595                                 &block->b_call->a_args.lock.fl);
 596                 status = nlmsvc_unlink_block(block);
 597                 nlmsvc_release_block(block);
 598         }
 599         return status ? nlm_lck_denied : nlm_granted;
 600 }
 601
 602 /*
 603  * This is a callback from the filesystem for VFS file lock requests.
 604  * It will be used if fl_grant is defined and the filesystem can not
 605  * respond to the request immediately.
 606  * For GETLK request it will copy the reply to the nlm_block.
 607  * For SETLK or SETLKW request it will get the local posix lock.
 608  * In all cases it will move the block to the head of nlm_blocked q where
 609  * nlmsvc_retry_blocked() can send back a reply for SETLKW or revisit the
 610  * deferred rpc for GETLK and SETLK.
 611  */
 612 static void
 613 nlmsvc_update_deferred_block(struct nlm_block *block, struct file_lock *conf,
 614                              int result)
 615 {
 616         block->b_flags |= B_GOT_CALLBACK;
 617         if (result == 0)
 618                 block->b_granted = 1;
 619         else
 620                 block->b_flags |= B_TIMED_OUT;
 621         if (conf) {
 622                 if (block->b_fl)
 623                         __locks_copy_lock(block->b_fl, conf);
 624         }
 625 }
 626
 627 static int nlmsvc_grant_deferred(struct file_lock *fl, struct file_lock *conf,
 628                                         int result)
 629 {
 630         struct nlm_block *block;
 631         int rc = -ENOENT;
 632
 633         lock_kernel();
 634         list_for_each_entry(block, &nlm_blocked, b_list) {
 635                 if (nlm_compare_locks(&block->b_call->a_args.lock.fl, fl)) {
 636                         dprintk("lockd: nlmsvc_notify_blocked block %p flags %d\n",
 637                                                         block, block->b_flags);
 638                         if (block->b_flags & B_QUEUED) {
 639                                 if (block->b_flags & B_TIMED_OUT) {
 640                                         rc = -ENOLCK;
 641                                         break;
 642                                 }
 643                                 nlmsvc_update_deferred_block(block, conf, result);
 644                         } else if (result == 0)
 645                                 block->b_granted = 1;
 646
 647                         nlmsvc_insert_block(block, 0);
 648                         svc_wake_up(block->b_daemon);
 649                         rc = 0;
 650                         break;
 651                 }
 652         }
 653         unlock_kernel();
 654         if (rc == -ENOENT)
 655                 printk(KERN_WARNING "lockd: grant for unknown block\n");
 656         return rc;
 657 }
 658
 659 /*
 660  * Unblock a blocked lock request. This is a callback invoked from the
 661  * VFS layer when a lock on which we blocked is removed.
 662  *
 663  * This function doesn't grant the blocked lock instantly, but rather moves
 664  * the block to the head of nlm_blocked where it can be picked up by lockd.
 665  */
 666 static void
 667 nlmsvc_notify_blocked(struct file_lock *fl)
 668 {
 669         struct nlm_block        *block;
 670
 671         dprintk("lockd: VFS unblock notification for block %p\n", fl);
 672         list_for_each_entry(block, &nlm_blocked, b_list) {
 673                 if (nlm_compare_locks(&block->b_call->a_args.lock.fl, fl)) {
 674                         nlmsvc_insert_block(block, 0);
 675                         svc_wake_up(block->b_daemon);
 676                         return;
 677                 }
 678         }
 679
 680         printk(KERN_WARNING "lockd: notification for unknown block!\n");
 681 }
 682
 683 static int nlmsvc_same_owner(struct file_lock *fl1, struct file_lock *fl2)
 684 {
 685         return fl1->fl_owner == fl2->fl_owner && fl1->fl_pid == fl2->fl_pid;
 686 }
 687
 688 struct lock_manager_operations nlmsvc_lock_operations = {
 689         .fl_compare_owner = nlmsvc_same_owner,
 690         .fl_notify = nlmsvc_notify_blocked,
 691         .fl_grant = nlmsvc_grant_deferred,
 692 };
 693
 694 /*
 695  * Try to claim a lock that was previously blocked.
 696  *
 697  * Note that we use both the RPC_GRANTED_MSG call _and_ an async
 698  * RPC thread when notifying the client. This seems like overkill...
 699  * Here's why:
 700  *  -   we don't want to use a synchronous RPC thread, otherwise
 701  *      we might find ourselves hanging on a dead portmapper.
 702  *  -   Some lockd implementations (e.g. HP) don't react to
 703  *      RPC_GRANTED calls; they seem to insist on RPC_GRANTED_MSG calls.
 704  */
 705 static void
 706 nlmsvc_grant_blocked(struct nlm_block *block)
 707 {
 708         struct nlm_file         *file = block->b_file;
 709         struct nlm_lock         *lock = &block->b_call->a_args.lock;
 710         int                     error;
 711
 712         dprintk("lockd: grant blocked lock %p\n", block);
 713
 714         kref_get(&block->b_count);
 715
 716         /* Unlink block request from list */
 717         nlmsvc_unlink_block(block);
 718
 719         /* If b_granted is true this means we've been here before.
 720          * Just retry the grant callback, possibly refreshing the RPC
 721          * binding */
 722         if (block->b_granted) {
 723                 nlm_rebind_host(block->b_host);
 724                 goto callback;
 725         }
 726
 727         /* Try the lock operation again */
 728         lock->fl.fl_flags |= FL_SLEEP;
 729         error = vfs_lock_file(file->f_file, F_SETLK, &lock->fl, NULL);
 730         lock->fl.fl_flags &= ~FL_SLEEP;
 731
 732         switch (error) {
 733         case 0:
 734                 break;
 735         case -EAGAIN:
 736         case -EINPROGRESS:
 737                 dprintk("lockd: lock still blocked error %d\n", error);
 738                 nlmsvc_insert_block(block, NLM_NEVER);
 739                 nlmsvc_release_block(block);
 740                 return;
 741         default:
 742                 printk(KERN_WARNING "lockd: unexpected error %d in %s!\n",
 743                                 -error, __func__);
 744                 nlmsvc_insert_block(block, 10 * HZ);
 745                 nlmsvc_release_block(block);
 746                 return;
 747         }
 748
 749 callback:
 750         /* Lock was granted by VFS. */
 751         dprintk("lockd: GRANTing blocked lock.\n");
 752         block->b_granted = 1;
 753
 754         /* keep block on the list, but don't reattempt until the RPC
 755          * completes or the submission fails
 756          */
 757         nlmsvc_insert_block(block, NLM_NEVER);
 758
 759         /* Call the client -- use a soft RPC task since nlmsvc_retry_blocked
 760          * will queue up a new one if this one times out
 761          */
 762         error = nlm_async_call(block->b_call, NLMPROC_GRANTED_MSG,
 763                                 &nlmsvc_grant_ops);
 764
 765         /* RPC submission failed, wait a bit and retry */
 766         if (error < 0)
 767                 nlmsvc_insert_block(block, 10 * HZ);
 768 }
 769
 770 /*
 771  * This is the callback from the RPC layer when the NLM_GRANTED_MSG
 772  * RPC call has succeeded or timed out.
 773  * Like all RPC callbacks, it is invoked by the rpciod process, so it
 774  * better not sleep. Therefore, we put the blocked lock on the nlm_blocked
 775  * chain once more in order to have it removed by lockd itself (which can
 776  * then sleep on the file semaphore without disrupting e.g. the nfs client).
 777  */
 778 static void nlmsvc_grant_callback(struct rpc_task *task, void *data)
 779 {
 780         struct nlm_rqst         *call = data;
 781         struct nlm_block        *block = call->a_block;
 782         unsigned long           timeout;
 783
 784         dprintk("lockd: GRANT_MSG RPC callback\n");
 785
 786         /* if the block is not on a list at this point then it has
 787          * been invalidated. Don't try to requeue it.
 788          *
 789          * FIXME: it's possible that the block is removed from the list
 790          * after this check but before the nlmsvc_insert_block. In that
 791          * case it will be added back. Perhaps we need better locking
 792          * for nlm_blocked?
 793          */
 794         if (list_empty(&block->b_list))
 795                 return;
 796
 797         /* Technically, we should down the file semaphore here. Since we
 798          * move the block towards the head of the queue only, no harm
 799          * can be done, though. */
 800         if (task->tk_status < 0) {
 801                 /* RPC error: Re-insert for retransmission */
 802                 timeout = 10 * HZ;
 803         } else {
 804                 /* Call was successful, now wait for client callback */
 805                 timeout = 60 * HZ;
 806         }
 807         nlmsvc_insert_block(block, timeout);
 808         svc_wake_up(block->b_daemon);
 809 }
 810
 811 static void nlmsvc_grant_release(void *data)
 812 {
 813         struct nlm_rqst         *call = data;
 814
 815         nlmsvc_release_block(call->a_block);
 816 }
 817
 818 static const struct rpc_call_ops nlmsvc_grant_ops = {
 819         .rpc_call_done = nlmsvc_grant_callback,
 820         .rpc_release = nlmsvc_grant_release,
 821 };
 822
 823 /*
 824  * We received a GRANT_RES callback. Try to find the corresponding
 825  * block.
 826  */
 827 void
 828 nlmsvc_grant_reply(struct nlm_cookie *cookie, __be32 status)
 829 {
 830         struct nlm_block        *block;
 831
 832         dprintk("grant_reply: looking for cookie %x, s=%d \n",
 833                 *(unsigned int *)(cookie->data), status);
 834         if (!(block = nlmsvc_find_block(cookie)))
 835                 return;
 836
 837         if (block) {
 838                 if (status == nlm_lck_denied_grace_period) {
 839                         /* Try again in a couple of seconds */
 840                         nlmsvc_insert_block(block, 10 * HZ);
 841                 } else {
 842                         /* Lock is now held by client, or has been rejected.
 843                          * In both cases, the block should be removed. */
 844                         nlmsvc_unlink_block(block);
 845                 }
 846         }
 847         nlmsvc_release_block(block);
 848 }
 849
 850 /* Helper function to handle retry of a deferred block.
 851  * If it is a blocking lock, call grant_blocked.
 852  * For a non-blocking lock or test lock, revisit the request.
 853  */
 854 static void
 855 retry_deferred_block(struct nlm_block *block)
 856 {
 857         if (!(block->b_flags & B_GOT_CALLBACK))
 858                 block->b_flags |= B_TIMED_OUT;
 859         nlmsvc_insert_block(block, NLM_TIMEOUT);
 860         dprintk("revisit block %p flags %d\n",  block, block->b_flags);
 861         if (block->b_deferred_req) {
 862                 block->b_deferred_req->revisit(block->b_deferred_req, 0);
 863                 block->b_deferred_req = NULL;
 864         }
 865 }
 866
 867 /*
 868  * Retry all blocked locks that have been notified. This is where lockd
 869  * picks up locks that can be granted, or grant notifications that must
 870  * be retransmitted.
 871  */
 872 unsigned long
 873 nlmsvc_retry_blocked(void)
 874 {
 875         unsigned long   timeout = MAX_SCHEDULE_TIMEOUT;
 876         struct nlm_block *block;
 877
 878         while (!list_empty(&nlm_blocked) && !kthread_should_stop()) {
 879                 block = list_entry(nlm_blocked.next, struct nlm_block, b_list);
 880
 881                 if (block->b_when == NLM_NEVER)
 882                         break;
 883                 if (time_after(block->b_when, jiffies)) {
 884                         timeout = block->b_when - jiffies;
 885                         break;
 886                 }
 887
 888                 dprintk("nlmsvc_retry_blocked(%p, when=%ld)\n",
 889                         block, block->b_when);
 890                 if (block->b_flags & B_QUEUED) {
 891                         dprintk("nlmsvc_retry_blocked delete block (%p, granted=%d, flags=%d)\n",
 892                                 block, block->b_granted, block->b_flags);
 893                         retry_deferred_block(block);
 894                 } else
 895                         nlmsvc_grant_blocked(block);
 896         }
 897
 898         return timeout;
 899 }