Pileus Git - ~andy/linux/blob - fs/lockd/svclock.c

   1 /*
   2  * linux/fs/lockd/svclock.c
   3  *
   4  * Handling of server-side locks, mostly of the blocked variety.
   5  * This is the ugliest part of lockd because we tread on very thin ice.
   6  * GRANT and CANCEL calls may get stuck, meet in mid-flight, etc.
   7  * IMNSHO introducing the grant callback into the NLM protocol was one
   8  * of the worst ideas Sun ever had. Except maybe for the idea of doing
   9  * NFS file locking at all.
  10  *
  11  * I'm trying hard to avoid race conditions by protecting most accesses
  12  * to a file's list of blocked locks through a semaphore. The global
  13  * list of blocked locks is not protected in this fashion however.
  14  * Therefore, some functions (such as the RPC callback for the async grant
  15  * call) move blocked locks towards the head of the list *while some other
  16  * process might be traversing it*. This should not be a problem in
  17  * practice, because this will only cause functions traversing the list
  18  * to visit some blocks twice.
  19  *
  20  * Copyright (C) 1996, Olaf Kirch <okir@monad.swb.de>
  21  */
  22
  23 #include <linux/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
  33 #define NLMDBG_FACILITY         NLMDBG_SVCLOCK
  34
  35 #ifdef CONFIG_LOCKD_V4
  36 #define nlm_deadlock    nlm4_deadlock
  37 #else
  38 #define nlm_deadlock    nlm_lck_denied
  39 #endif
  40
  41 static void nlmsvc_release_block(struct nlm_block *block);
  42 static void     nlmsvc_insert_block(struct nlm_block *block, unsigned long);
  43 static void     nlmsvc_remove_block(struct nlm_block *block);
  44
  45 static int nlmsvc_setgrantargs(struct nlm_rqst *call, struct nlm_lock *lock);
  46 static void nlmsvc_freegrantargs(struct nlm_rqst *call);
  47 static const struct rpc_call_ops nlmsvc_grant_ops;
  48
  49 /*
  50  * The list of blocked locks to retry
  51  */
  52 static LIST_HEAD(nlm_blocked);
  53
  54 /*
  55  * Insert a blocked lock into the global list
  56  */
  57 static void
  58 nlmsvc_insert_block(struct nlm_block *block, unsigned long when)
  59 {
  60         struct nlm_block *b;
  61         struct list_head *pos;
  62
  63         dprintk("lockd: nlmsvc_insert_block(%p, %ld)\n", block, when);
  64         if (list_empty(&block->b_list)) {
  65                 kref_get(&block->b_count);
  66         } else {
  67                 list_del_init(&block->b_list);
  68         }
  69
  70         pos = &nlm_blocked;
  71         if (when != NLM_NEVER) {
  72                 if ((when += jiffies) == NLM_NEVER)
  73                         when ++;
  74                 list_for_each(pos, &nlm_blocked) {
  75                         b = list_entry(pos, struct nlm_block, b_list);
  76                         if (time_after(b->b_when,when) || b->b_when == NLM_NEVER)
  77                                 break;
  78                 }
  79                 /* On normal exit from the loop, pos == &nlm_blocked,
  80                  * so we will be adding to the end of the list - good
  81                  */
  82         }
  83
  84         list_add_tail(&block->b_list, pos);
  85         block->b_when = when;
  86 }
  87
  88 /*
  89  * Remove a block from the global list
  90  */
  91 static inline void
  92 nlmsvc_remove_block(struct nlm_block *block)
  93 {
  94         if (!list_empty(&block->b_list)) {
  95                 list_del_init(&block->b_list);
  96                 nlmsvc_release_block(block);
  97         }
  98 }
  99
 100 /*
 101  * Find a block for a given lock
 102  */
 103 static struct nlm_block *
 104 nlmsvc_lookup_block(struct nlm_file *file, struct nlm_lock *lock)
 105 {
 106         struct nlm_block        *block;
 107         struct file_lock        *fl;
 108
 109         dprintk("lockd: nlmsvc_lookup_block f=%p pd=%d %Ld-%Ld ty=%d\n",
 110                                 file, lock->fl.fl_pid,
 111                                 (long long)lock->fl.fl_start,
 112                                 (long long)lock->fl.fl_end, lock->fl.fl_type);
 113         list_for_each_entry(block, &nlm_blocked, b_list) {
 114                 fl = &block->b_call->a_args.lock.fl;
 115                 dprintk("lockd: check f=%p pd=%d %Ld-%Ld ty=%d cookie=%s\n",
 116                                 block->b_file, fl->fl_pid,
 117                                 (long long)fl->fl_start,
 118                                 (long long)fl->fl_end, fl->fl_type,
 119                                 nlmdbg_cookie2a(&block->b_call->a_args.cookie));
 120                 if (block->b_file == file && nlm_compare_locks(fl, &lock->fl)) {
 121                         kref_get(&block->b_count);
 122                         return block;
 123                 }
 124         }
 125
 126         return NULL;
 127 }
 128
 129 static inline int nlm_cookie_match(struct nlm_cookie *a, struct nlm_cookie *b)
 130 {
 131         if(a->len != b->len)
 132                 return 0;
 133         if(memcmp(a->data,b->data,a->len))
 134                 return 0;
 135         return 1;
 136 }
 137
 138 /*
 139  * Find a block with a given NLM cookie.
 140  */
 141 static inline struct nlm_block *
 142 nlmsvc_find_block(struct nlm_cookie *cookie)
 143 {
 144         struct nlm_block *block;
 145
 146         list_for_each_entry(block, &nlm_blocked, b_list) {
 147                 if (nlm_cookie_match(&block->b_call->a_args.cookie,cookie))
 148                         goto found;
 149         }
 150
 151         return NULL;
 152
 153 found:
 154         dprintk("nlmsvc_find_block(%s): block=%p\n", nlmdbg_cookie2a(cookie), block);
 155         kref_get(&block->b_count);
 156         return block;
 157 }
 158
 159 /*
 160  * Create a block and initialize it.
 161  *
 162  * Note: we explicitly set the cookie of the grant reply to that of
 163  * the blocked lock request. The spec explicitly mentions that the client
 164  * should _not_ rely on the callback containing the same cookie as the
 165  * request, but (as I found out later) that's because some implementations
 166  * do just this. Never mind the standards comittees, they support our
 167  * logging industries.
 168  *
 169  * 10 years later: I hope we can safely ignore these old and broken
 170  * clients by now. Let's fix this so we can uniquely identify an incoming
 171  * GRANTED_RES message by cookie, without having to rely on the client's IP
 172  * address. --okir
 173  */
 174 static inline struct nlm_block *
 175 nlmsvc_create_block(struct svc_rqst *rqstp, struct nlm_file *file,
 176                 struct nlm_lock *lock, struct nlm_cookie *cookie)
 177 {
 178         struct nlm_block        *block;
 179         struct nlm_host         *host;
 180         struct nlm_rqst         *call = NULL;
 181
 182         /* Create host handle for callback */
 183         host = nlmsvc_lookup_host(rqstp, lock->caller, lock->len);
 184         if (host == NULL)
 185                 return NULL;
 186
 187         call = nlm_alloc_call(host);
 188         if (call == NULL)
 189                 return NULL;
 190
 191         /* Allocate memory for block, and initialize arguments */
 192         block = kzalloc(sizeof(*block), GFP_KERNEL);
 193         if (block == NULL)
 194                 goto failed;
 195         kref_init(&block->b_count);
 196         INIT_LIST_HEAD(&block->b_list);
 197         INIT_LIST_HEAD(&block->b_flist);
 198
 199         if (!nlmsvc_setgrantargs(call, lock))
 200                 goto failed_free;
 201
 202         /* Set notifier function for VFS, and init args */
 203         call->a_args.lock.fl.fl_flags |= FL_SLEEP;
 204         call->a_args.lock.fl.fl_lmops = &nlmsvc_lock_operations;
 205         nlmclnt_next_cookie(&call->a_args.cookie);
 206
 207         dprintk("lockd: created block %p...\n", block);
 208
 209         /* Create and initialize the block */
 210         block->b_daemon = rqstp->rq_server;
 211         block->b_host   = host;
 212         block->b_file   = file;
 213         block->b_fl = NULL;
 214         file->f_count++;
 215
 216         /* Add to file's list of blocks */
 217         list_add(&block->b_flist, &file->f_blocks);
 218
 219         /* Set up RPC arguments for callback */
 220         block->b_call = call;
 221         call->a_flags   = RPC_TASK_ASYNC;
 222         call->a_block = block;
 223
 224         return block;
 225
 226 failed_free:
 227         kfree(block);
 228 failed:
 229         nlm_release_call(call);
 230         return NULL;
 231 }
 232
 233 /*
 234  * Delete a block. If the lock was cancelled or the grant callback
 235  * failed, unlock is set to 1.
 236  * It is the caller's responsibility to check whether the file
 237  * can be closed hereafter.
 238  */
 239 static int nlmsvc_unlink_block(struct nlm_block *block)
 240 {
 241         int status;
 242         dprintk("lockd: unlinking block %p...\n", block);
 243
 244         /* Remove block from list */
 245         status = posix_unblock_lock(block->b_file->f_file, &block->b_call->a_args.lock.fl);
 246         nlmsvc_remove_block(block);
 247         return status;
 248 }
 249
 250 static void nlmsvc_free_block(struct kref *kref)
 251 {
 252         struct nlm_block *block = container_of(kref, struct nlm_block, b_count);
 253         struct nlm_file         *file = block->b_file;
 254
 255         dprintk("lockd: freeing block %p...\n", block);
 256
 257         /* Remove block from file's list of blocks */
 258         mutex_lock(&file->f_mutex);
 259         list_del_init(&block->b_flist);
 260         mutex_unlock(&file->f_mutex);
 261
 262         nlmsvc_freegrantargs(block->b_call);
 263         nlm_release_call(block->b_call);
 264         nlm_release_file(block->b_file);
 265         kfree(block->b_fl);
 266         kfree(block);
 267 }
 268
 269 static void nlmsvc_release_block(struct nlm_block *block)
 270 {
 271         if (block != NULL)
 272                 kref_put(&block->b_count, nlmsvc_free_block);
 273 }
 274
 275 /*
 276  * Loop over all blocks and delete blocks held by
 277  * a matching host.
 278  */
 279 void nlmsvc_traverse_blocks(struct nlm_host *host,
 280                         struct nlm_file *file,
 281                         nlm_host_match_fn_t match)
 282 {
 283         struct nlm_block *block, *next;
 284
 285 restart:
 286         mutex_lock(&file->f_mutex);
 287         list_for_each_entry_safe(block, next, &file->f_blocks, b_flist) {
 288                 if (!match(block->b_host, host))
 289                         continue;
 290                 /* Do not destroy blocks that are not on
 291                  * the global retry list - why? */
 292                 if (list_empty(&block->b_list))
 293                         continue;
 294                 kref_get(&block->b_count);
 295                 mutex_unlock(&file->f_mutex);
 296                 nlmsvc_unlink_block(block);
 297                 nlmsvc_release_block(block);
 298                 goto restart;
 299         }
 300         mutex_unlock(&file->f_mutex);
 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 = 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                         return 0;
 322                 call->a_args.lock.oh.data = (u8 *) data;
 323         }
 324
 325         memcpy(call->a_args.lock.oh.data, lock->oh.data, lock->oh.len);
 326         return 1;
 327 }
 328
 329 static void nlmsvc_freegrantargs(struct nlm_rqst *call)
 330 {
 331         if (call->a_args.lock.oh.data != call->a_owner)
 332                 kfree(call->a_args.lock.oh.data);
 333 }
 334
 335 /*
 336  * Deferred lock request handling for non-blocking lock
 337  */
 338 static u32
 339 nlmsvc_defer_lock_rqst(struct svc_rqst *rqstp, struct nlm_block *block)
 340 {
 341         u32 status = nlm_lck_denied_nolocks;
 342
 343         block->b_flags |= B_QUEUED;
 344
 345         nlmsvc_insert_block(block, NLM_TIMEOUT);
 346
 347         block->b_cache_req = &rqstp->rq_chandle;
 348         if (rqstp->rq_chandle.defer) {
 349                 block->b_deferred_req =
 350                         rqstp->rq_chandle.defer(block->b_cache_req);
 351                 if (block->b_deferred_req != NULL)
 352                         status = nlm_drop_reply;
 353         }
 354         dprintk("lockd: nlmsvc_defer_lock_rqst block %p flags %d status %d\n",
 355                 block, block->b_flags, status);
 356
 357         return status;
 358 }
 359
 360 /*
 361  * Attempt to establish a lock, and if it can't be granted, block it
 362  * if required.
 363  */
 364 __be32
 365 nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file,
 366                         struct nlm_lock *lock, int wait, struct nlm_cookie *cookie)
 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
 381         /* Lock file against concurrent access */
 382         mutex_lock(&file->f_mutex);
 383         /* Get existing block (in case client is busy-waiting)
 384          * or create new block
 385          */
 386         block = nlmsvc_lookup_block(file, lock);
 387         if (block == NULL) {
 388                 block = nlmsvc_create_block(rqstp, file, lock, cookie);
 389                 ret = nlm_lck_denied_nolocks;
 390                 if (block == NULL)
 391                         goto out;
 392                 lock = &block->b_call->a_args.lock;
 393         } else
 394                 lock->fl.fl_flags &= ~FL_SLEEP;
 395
 396         error = posix_lock_file(file->f_file, &lock->fl, NULL);
 397         lock->fl.fl_flags &= ~FL_SLEEP;
 398
 399         dprintk("lockd: posix_lock_file returned %d\n", error);
 400
 401         switch(error) {
 402                 case 0:
 403                         ret = nlm_granted;
 404                         goto out;
 405                 case -EAGAIN:
 406                         break;
 407                 case -EDEADLK:
 408                         ret = nlm_deadlock;
 409                         goto out;
 410                 default:                        /* includes ENOLCK */
 411                         ret = nlm_lck_denied_nolocks;
 412                         goto out;
 413         }
 414
 415         ret = nlm_lck_denied;
 416         if (!wait)
 417                 goto out;
 418
 419         ret = nlm_lck_blocked;
 420
 421         /* Append to list of blocked */
 422         nlmsvc_insert_block(block, NLM_NEVER);
 423 out:
 424         mutex_unlock(&file->f_mutex);
 425         nlmsvc_release_block(block);
 426         dprintk("lockd: nlmsvc_lock returned %u\n", ret);
 427         return ret;
 428 }
 429
 430 /*
 431  * Test for presence of a conflicting lock.
 432  */
 433 __be32
 434 nlmsvc_testlock(struct svc_rqst *rqstp, struct nlm_file *file,
 435                 struct nlm_lock *lock, struct nlm_lock *conflock,
 436                 struct nlm_cookie *cookie)
 437 {
 438         struct nlm_block        *block = NULL;
 439         int                     error;
 440         __be32                  ret;
 441
 442         dprintk("lockd: nlmsvc_testlock(%s/%ld, ty=%d, %Ld-%Ld)\n",
 443                                 file->f_file->f_path.dentry->d_inode->i_sb->s_id,
 444                                 file->f_file->f_path.dentry->d_inode->i_ino,
 445                                 lock->fl.fl_type,
 446                                 (long long)lock->fl.fl_start,
 447                                 (long long)lock->fl.fl_end);
 448
 449         /* Get existing block (in case client is busy-waiting) */
 450         block = nlmsvc_lookup_block(file, lock);
 451
 452         if (block == NULL) {
 453                 struct file_lock *conf = kzalloc(sizeof(*conf), GFP_KERNEL);
 454
 455                 if (conf == NULL)
 456                         return nlm_granted;
 457                 block = nlmsvc_create_block(rqstp, file, lock, cookie);
 458                 if (block == NULL) {
 459                         kfree(conf);
 460                         return nlm_granted;
 461                 }
 462                 block->b_fl = conf;
 463         }
 464         if (block->b_flags & B_QUEUED) {
 465                 dprintk("lockd: nlmsvc_testlock deferred block %p flags %d fl %p\n",
 466                         block, block->b_flags, block->b_fl);
 467                 if (block->b_flags & B_TIMED_OUT) {
 468                         nlmsvc_unlink_block(block);
 469                         return nlm_lck_denied;
 470                 }
 471                 if (block->b_flags & B_GOT_CALLBACK) {
 472                         if (block->b_fl != NULL
 473                                         && block->b_fl->fl_type != F_UNLCK) {
 474                                 lock->fl = *block->b_fl;
 475                                 goto conf_lock;
 476                         }
 477                         else {
 478                                 nlmsvc_unlink_block(block);
 479                                 return nlm_granted;
 480                         }
 481                 }
 482                 return nlm_drop_reply;
 483         }
 484
 485         error = vfs_test_lock(file->f_file, &lock->fl);
 486         if (error == -EINPROGRESS)
 487                 return nlmsvc_defer_lock_rqst(rqstp, block);
 488         if (error) {
 489                 ret = nlm_lck_denied_nolocks;
 490                 goto out;
 491         }
 492         if (lock->fl.fl_type == F_UNLCK) {
 493                 ret = nlm_granted;
 494                 goto out;
 495         }
 496
 497 conf_lock:
 498         dprintk("lockd: conflicting lock(ty=%d, %Ld-%Ld)\n",
 499                 lock->fl.fl_type, (long long)lock->fl.fl_start,
 500                 (long long)lock->fl.fl_end);
 501         conflock->caller = "somehost";  /* FIXME */
 502         conflock->len = strlen(conflock->caller);
 503         conflock->oh.len = 0;           /* don't return OH info */
 504         conflock->svid = lock->fl.fl_pid;
 505         conflock->fl.fl_type = lock->fl.fl_type;
 506         conflock->fl.fl_start = lock->fl.fl_start;
 507         conflock->fl.fl_end = lock->fl.fl_end;
 508         ret = nlm_lck_denied;
 509 out:
 510         if (block)
 511                 nlmsvc_release_block(block);
 512         return ret;
 513 }
 514
 515 /*
 516  * Remove a lock.
 517  * This implies a CANCEL call: We send a GRANT_MSG, the client replies
 518  * with a GRANT_RES call which gets lost, and calls UNLOCK immediately
 519  * afterwards. In this case the block will still be there, and hence
 520  * must be removed.
 521  */
 522 __be32
 523 nlmsvc_unlock(struct nlm_file *file, struct nlm_lock *lock)
 524 {
 525         int     error;
 526
 527         dprintk("lockd: nlmsvc_unlock(%s/%ld, pi=%d, %Ld-%Ld)\n",
 528                                 file->f_file->f_path.dentry->d_inode->i_sb->s_id,
 529                                 file->f_file->f_path.dentry->d_inode->i_ino,
 530                                 lock->fl.fl_pid,
 531                                 (long long)lock->fl.fl_start,
 532                                 (long long)lock->fl.fl_end);
 533
 534         /* First, cancel any lock that might be there */
 535         nlmsvc_cancel_blocked(file, lock);
 536
 537         lock->fl.fl_type = F_UNLCK;
 538         error = posix_lock_file(file->f_file, &lock->fl, NULL);
 539
 540         return (error < 0)? nlm_lck_denied_nolocks : nlm_granted;
 541 }
 542
 543 /*
 544  * Cancel a previously blocked request.
 545  *
 546  * A cancel request always overrides any grant that may currently
 547  * be in progress.
 548  * The calling procedure must check whether the file can be closed.
 549  */
 550 __be32
 551 nlmsvc_cancel_blocked(struct nlm_file *file, struct nlm_lock *lock)
 552 {
 553         struct nlm_block        *block;
 554         int status = 0;
 555
 556         dprintk("lockd: nlmsvc_cancel(%s/%ld, pi=%d, %Ld-%Ld)\n",
 557                                 file->f_file->f_path.dentry->d_inode->i_sb->s_id,
 558                                 file->f_file->f_path.dentry->d_inode->i_ino,
 559                                 lock->fl.fl_pid,
 560                                 (long long)lock->fl.fl_start,
 561                                 (long long)lock->fl.fl_end);
 562
 563         mutex_lock(&file->f_mutex);
 564         block = nlmsvc_lookup_block(file, lock);
 565         mutex_unlock(&file->f_mutex);
 566         if (block != NULL) {
 567                 status = nlmsvc_unlink_block(block);
 568                 nlmsvc_release_block(block);
 569         }
 570         return status ? nlm_lck_denied : nlm_granted;
 571 }
 572
 573 /*
 574  * This is a callback from the filesystem for VFS file lock requests.
 575  * It will be used if fl_grant is defined and the filesystem can not
 576  * respond to the request immediately.
 577  * For GETLK request it will copy the reply to the nlm_block.
 578  * For SETLK or SETLKW request it will get the local posix lock.
 579  * In all cases it will move the block to the head of nlm_blocked q where
 580  * nlmsvc_retry_blocked() can send back a reply for SETLKW or revisit the
 581  * deferred rpc for GETLK and SETLK.
 582  */
 583 static void
 584 nlmsvc_update_deferred_block(struct nlm_block *block, struct file_lock *conf,
 585                              int result)
 586 {
 587         block->b_flags |= B_GOT_CALLBACK;
 588         if (result == 0)
 589                 block->b_granted = 1;
 590         else
 591                 block->b_flags |= B_TIMED_OUT;
 592         if (conf) {
 593                 if (block->b_fl)
 594                         locks_copy_lock(block->b_fl, conf);
 595         }
 596 }
 597
 598 static int nlmsvc_grant_deferred(struct file_lock *fl, struct file_lock *conf,
 599                                         int result)
 600 {
 601         struct nlm_block *block;
 602         int rc = -ENOENT;
 603
 604         lock_kernel();
 605         list_for_each_entry(block, &nlm_blocked, b_list) {
 606                 if (nlm_compare_locks(&block->b_call->a_args.lock.fl, fl)) {
 607                         dprintk("lockd: nlmsvc_notify_blocked block %p flags %d\n",
 608                                                         block, block->b_flags);
 609                         if (block->b_flags & B_QUEUED) {
 610                                 if (block->b_flags & B_TIMED_OUT) {
 611                                         rc = -ENOLCK;
 612                                         break;
 613                                 }
 614                                 nlmsvc_update_deferred_block(block, conf, result);
 615                         } else if (result == 0)
 616                                 block->b_granted = 1;
 617
 618                         nlmsvc_insert_block(block, 0);
 619                         svc_wake_up(block->b_daemon);
 620                         rc = 0;
 621                         break;
 622                 }
 623         }
 624         unlock_kernel();
 625         if (rc == -ENOENT)
 626                 printk(KERN_WARNING "lockd: grant for unknown block\n");
 627         return rc;
 628 }
 629
 630 /*
 631  * Unblock a blocked lock request. This is a callback invoked from the
 632  * VFS layer when a lock on which we blocked is removed.
 633  *
 634  * This function doesn't grant the blocked lock instantly, but rather moves
 635  * the block to the head of nlm_blocked where it can be picked up by lockd.
 636  */
 637 static void
 638 nlmsvc_notify_blocked(struct file_lock *fl)
 639 {
 640         struct nlm_block        *block;
 641
 642         dprintk("lockd: VFS unblock notification for block %p\n", fl);
 643         list_for_each_entry(block, &nlm_blocked, b_list) {
 644                 if (nlm_compare_locks(&block->b_call->a_args.lock.fl, fl)) {
 645                         nlmsvc_insert_block(block, 0);
 646                         svc_wake_up(block->b_daemon);
 647                         return;
 648                 }
 649         }
 650
 651         printk(KERN_WARNING "lockd: notification for unknown block!\n");
 652 }
 653
 654 static int nlmsvc_same_owner(struct file_lock *fl1, struct file_lock *fl2)
 655 {
 656         return fl1->fl_owner == fl2->fl_owner && fl1->fl_pid == fl2->fl_pid;
 657 }
 658
 659 struct lock_manager_operations nlmsvc_lock_operations = {
 660         .fl_compare_owner = nlmsvc_same_owner,
 661         .fl_notify = nlmsvc_notify_blocked,
 662         .fl_grant = nlmsvc_grant_deferred,
 663 };
 664
 665 /*
 666  * Try to claim a lock that was previously blocked.
 667  *
 668  * Note that we use both the RPC_GRANTED_MSG call _and_ an async
 669  * RPC thread when notifying the client. This seems like overkill...
 670  * Here's why:
 671  *  -   we don't want to use a synchronous RPC thread, otherwise
 672  *      we might find ourselves hanging on a dead portmapper.
 673  *  -   Some lockd implementations (e.g. HP) don't react to
 674  *      RPC_GRANTED calls; they seem to insist on RPC_GRANTED_MSG calls.
 675  */
 676 static void
 677 nlmsvc_grant_blocked(struct nlm_block *block)
 678 {
 679         struct nlm_file         *file = block->b_file;
 680         struct nlm_lock         *lock = &block->b_call->a_args.lock;
 681         int                     error;
 682
 683         dprintk("lockd: grant blocked lock %p\n", block);
 684
 685         kref_get(&block->b_count);
 686
 687         /* Unlink block request from list */
 688         nlmsvc_unlink_block(block);
 689
 690         /* If b_granted is true this means we've been here before.
 691          * Just retry the grant callback, possibly refreshing the RPC
 692          * binding */
 693         if (block->b_granted) {
 694                 nlm_rebind_host(block->b_host);
 695                 goto callback;
 696         }
 697
 698         /* Try the lock operation again */
 699         lock->fl.fl_flags |= FL_SLEEP;
 700         error = posix_lock_file(file->f_file, &lock->fl, NULL);
 701         lock->fl.fl_flags &= ~FL_SLEEP;
 702
 703         switch (error) {
 704         case 0:
 705                 break;
 706         case -EAGAIN:
 707                 dprintk("lockd: lock still blocked\n");
 708                 nlmsvc_insert_block(block, NLM_NEVER);
 709                 nlmsvc_release_block(block);
 710                 return;
 711         default:
 712                 printk(KERN_WARNING "lockd: unexpected error %d in %s!\n",
 713                                 -error, __FUNCTION__);
 714                 nlmsvc_insert_block(block, 10 * HZ);
 715                 nlmsvc_release_block(block);
 716                 return;
 717         }
 718
 719 callback:
 720         /* Lock was granted by VFS. */
 721         dprintk("lockd: GRANTing blocked lock.\n");
 722         block->b_granted = 1;
 723
 724         /* Schedule next grant callback in 30 seconds */
 725         nlmsvc_insert_block(block, 30 * HZ);
 726
 727         /* Call the client */
 728         nlm_async_call(block->b_call, NLMPROC_GRANTED_MSG, &nlmsvc_grant_ops);
 729 }
 730
 731 /*
 732  * This is the callback from the RPC layer when the NLM_GRANTED_MSG
 733  * RPC call has succeeded or timed out.
 734  * Like all RPC callbacks, it is invoked by the rpciod process, so it
 735  * better not sleep. Therefore, we put the blocked lock on the nlm_blocked
 736  * chain once more in order to have it removed by lockd itself (which can
 737  * then sleep on the file semaphore without disrupting e.g. the nfs client).
 738  */
 739 static void nlmsvc_grant_callback(struct rpc_task *task, void *data)
 740 {
 741         struct nlm_rqst         *call = data;
 742         struct nlm_block        *block = call->a_block;
 743         unsigned long           timeout;
 744
 745         dprintk("lockd: GRANT_MSG RPC callback\n");
 746
 747         /* Technically, we should down the file semaphore here. Since we
 748          * move the block towards the head of the queue only, no harm
 749          * can be done, though. */
 750         if (task->tk_status < 0) {
 751                 /* RPC error: Re-insert for retransmission */
 752                 timeout = 10 * HZ;
 753         } else {
 754                 /* Call was successful, now wait for client callback */
 755                 timeout = 60 * HZ;
 756         }
 757         nlmsvc_insert_block(block, timeout);
 758         svc_wake_up(block->b_daemon);
 759 }
 760
 761 static void nlmsvc_grant_release(void *data)
 762 {
 763         struct nlm_rqst         *call = data;
 764
 765         nlmsvc_release_block(call->a_block);
 766 }
 767
 768 static const struct rpc_call_ops nlmsvc_grant_ops = {
 769         .rpc_call_done = nlmsvc_grant_callback,
 770         .rpc_release = nlmsvc_grant_release,
 771 };
 772
 773 /*
 774  * We received a GRANT_RES callback. Try to find the corresponding
 775  * block.
 776  */
 777 void
 778 nlmsvc_grant_reply(struct nlm_cookie *cookie, __be32 status)
 779 {
 780         struct nlm_block        *block;
 781
 782         dprintk("grant_reply: looking for cookie %x, s=%d \n",
 783                 *(unsigned int *)(cookie->data), status);
 784         if (!(block = nlmsvc_find_block(cookie)))
 785                 return;
 786
 787         if (block) {
 788                 if (status == nlm_lck_denied_grace_period) {
 789                         /* Try again in a couple of seconds */
 790                         nlmsvc_insert_block(block, 10 * HZ);
 791                 } else {
 792                         /* Lock is now held by client, or has been rejected.
 793                          * In both cases, the block should be removed. */
 794                         nlmsvc_unlink_block(block);
 795                 }
 796         }
 797         nlmsvc_release_block(block);
 798 }
 799
 800 /* Helper function to handle retry of a deferred block.
 801  * If it is a blocking lock, call grant_blocked.
 802  * For a non-blocking lock or test lock, revisit the request.
 803  */
 804 static void
 805 retry_deferred_block(struct nlm_block *block)
 806 {
 807         if (!(block->b_flags & B_GOT_CALLBACK))
 808                 block->b_flags |= B_TIMED_OUT;
 809         nlmsvc_insert_block(block, NLM_TIMEOUT);
 810         dprintk("revisit block %p flags %d\n",  block, block->b_flags);
 811         if (block->b_deferred_req) {
 812                 block->b_deferred_req->revisit(block->b_deferred_req, 0);
 813                 block->b_deferred_req = NULL;
 814         }
 815 }
 816
 817 /*
 818  * Retry all blocked locks that have been notified. This is where lockd
 819  * picks up locks that can be granted, or grant notifications that must
 820  * be retransmitted.
 821  */
 822 unsigned long
 823 nlmsvc_retry_blocked(void)
 824 {
 825         unsigned long   timeout = MAX_SCHEDULE_TIMEOUT;
 826         struct nlm_block *block;
 827
 828         while (!list_empty(&nlm_blocked)) {
 829                 block = list_entry(nlm_blocked.next, struct nlm_block, b_list);
 830
 831                 if (block->b_when == NLM_NEVER)
 832                         break;
 833                 if (time_after(block->b_when,jiffies)) {
 834                         timeout = block->b_when - jiffies;
 835                         break;
 836                 }
 837
 838                 dprintk("nlmsvc_retry_blocked(%p, when=%ld)\n",
 839                         block, block->b_when);
 840                 if (block->b_flags & B_QUEUED) {
 841                         dprintk("nlmsvc_retry_blocked delete block (%p, granted=%d, flags=%d)\n",
 842                                 block, block->b_granted, block->b_flags);
 843                         retry_deferred_block(block);
 844                 } else
 845                         nlmsvc_grant_blocked(block);
 846         }
 847
 848         return timeout;
 849 }