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/sunrpc/clnt.h>
  29 #include <linux/sunrpc/svc_xprt.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 static DEFINE_SPINLOCK(nlm_blocked_lock);
  55
  56 #ifdef LOCKD_DEBUG
  57 static const char *nlmdbg_cookie2a(const struct nlm_cookie *cookie)
  58 {
  59         /*
  60          * We can get away with a static buffer because we're only
  61          * called with BKL held.
  62          */
  63         static char buf[2*NLM_MAXCOOKIELEN+1];
  64         unsigned int i, len = sizeof(buf);
  65         char *p = buf;
  66
  67         len--;  /* allow for trailing \0 */
  68         if (len < 3)
  69                 return "???";
  70         for (i = 0 ; i < cookie->len ; i++) {
  71                 if (len < 2) {
  72                         strcpy(p-3, "...");
  73                         break;
  74                 }
  75                 sprintf(p, "%02x", cookie->data[i]);
  76                 p += 2;
  77                 len -= 2;
  78         }
  79         *p = '\0';
  80
  81         return buf;
  82 }
  83 #endif
  84
  85 /*
  86  * Insert a blocked lock into the global list
  87  */
  88 static void
  89 nlmsvc_insert_block_locked(struct nlm_block *block, unsigned long when)
  90 {
  91         struct nlm_block *b;
  92         struct list_head *pos;
  93
  94         dprintk("lockd: nlmsvc_insert_block(%p, %ld)\n", block, when);
  95         if (list_empty(&block->b_list)) {
  96                 kref_get(&block->b_count);
  97         } else {
  98                 list_del_init(&block->b_list);
  99         }
 100
 101         pos = &nlm_blocked;
 102         if (when != NLM_NEVER) {
 103                 if ((when += jiffies) == NLM_NEVER)
 104                         when ++;
 105                 list_for_each(pos, &nlm_blocked) {
 106                         b = list_entry(pos, struct nlm_block, b_list);
 107                         if (time_after(b->b_when,when) || b->b_when == NLM_NEVER)
 108                                 break;
 109                 }
 110                 /* On normal exit from the loop, pos == &nlm_blocked,
 111                  * so we will be adding to the end of the list - good
 112                  */
 113         }
 114
 115         list_add_tail(&block->b_list, pos);
 116         block->b_when = when;
 117 }
 118
 119 static void nlmsvc_insert_block(struct nlm_block *block, unsigned long when)
 120 {
 121         spin_lock(&nlm_blocked_lock);
 122         nlmsvc_insert_block_locked(block, when);
 123         spin_unlock(&nlm_blocked_lock);
 124 }
 125
 126 /*
 127  * Remove a block from the global list
 128  */
 129 static inline void
 130 nlmsvc_remove_block(struct nlm_block *block)
 131 {
 132         if (!list_empty(&block->b_list)) {
 133                 spin_lock(&nlm_blocked_lock);
 134                 list_del_init(&block->b_list);
 135                 spin_unlock(&nlm_blocked_lock);
 136                 nlmsvc_release_block(block);
 137         }
 138 }
 139
 140 /*
 141  * Find a block for a given lock
 142  */
 143 static struct nlm_block *
 144 nlmsvc_lookup_block(struct nlm_file *file, struct nlm_lock *lock)
 145 {
 146         struct nlm_block        *block;
 147         struct file_lock        *fl;
 148
 149         dprintk("lockd: nlmsvc_lookup_block f=%p pd=%d %Ld-%Ld ty=%d\n",
 150                                 file, lock->fl.fl_pid,
 151                                 (long long)lock->fl.fl_start,
 152                                 (long long)lock->fl.fl_end, lock->fl.fl_type);
 153         list_for_each_entry(block, &nlm_blocked, b_list) {
 154                 fl = &block->b_call->a_args.lock.fl;
 155                 dprintk("lockd: check f=%p pd=%d %Ld-%Ld ty=%d cookie=%s\n",
 156                                 block->b_file, fl->fl_pid,
 157                                 (long long)fl->fl_start,
 158                                 (long long)fl->fl_end, fl->fl_type,
 159                                 nlmdbg_cookie2a(&block->b_call->a_args.cookie));
 160                 if (block->b_file == file && nlm_compare_locks(fl, &lock->fl)) {
 161                         kref_get(&block->b_count);
 162                         return block;
 163                 }
 164         }
 165
 166         return NULL;
 167 }
 168
 169 static inline int nlm_cookie_match(struct nlm_cookie *a, struct nlm_cookie *b)
 170 {
 171         if (a->len != b->len)
 172                 return 0;
 173         if (memcmp(a->data, b->data, a->len))
 174                 return 0;
 175         return 1;
 176 }
 177
 178 /*
 179  * Find a block with a given NLM cookie.
 180  */
 181 static inline struct nlm_block *
 182 nlmsvc_find_block(struct nlm_cookie *cookie)
 183 {
 184         struct nlm_block *block;
 185
 186         list_for_each_entry(block, &nlm_blocked, b_list) {
 187                 if (nlm_cookie_match(&block->b_call->a_args.cookie,cookie))
 188                         goto found;
 189         }
 190
 191         return NULL;
 192
 193 found:
 194         dprintk("nlmsvc_find_block(%s): block=%p\n", nlmdbg_cookie2a(cookie), block);
 195         kref_get(&block->b_count);
 196         return block;
 197 }
 198
 199 /*
 200  * Create a block and initialize it.
 201  *
 202  * Note: we explicitly set the cookie of the grant reply to that of
 203  * the blocked lock request. The spec explicitly mentions that the client
 204  * should _not_ rely on the callback containing the same cookie as the
 205  * request, but (as I found out later) that's because some implementations
 206  * do just this. Never mind the standards comittees, they support our
 207  * logging industries.
 208  *
 209  * 10 years later: I hope we can safely ignore these old and broken
 210  * clients by now. Let's fix this so we can uniquely identify an incoming
 211  * GRANTED_RES message by cookie, without having to rely on the client's IP
 212  * address. --okir
 213  */
 214 static struct nlm_block *
 215 nlmsvc_create_block(struct svc_rqst *rqstp, struct nlm_host *host,
 216                     struct nlm_file *file, struct nlm_lock *lock,
 217                     struct nlm_cookie *cookie)
 218 {
 219         struct nlm_block        *block;
 220         struct nlm_rqst         *call = NULL;
 221
 222         call = nlm_alloc_call(host);
 223         if (call == NULL)
 224                 return NULL;
 225
 226         /* Allocate memory for block, and initialize arguments */
 227         block = kzalloc(sizeof(*block), GFP_KERNEL);
 228         if (block == NULL)
 229                 goto failed;
 230         kref_init(&block->b_count);
 231         INIT_LIST_HEAD(&block->b_list);
 232         INIT_LIST_HEAD(&block->b_flist);
 233
 234         if (!nlmsvc_setgrantargs(call, lock))
 235                 goto failed_free;
 236
 237         /* Set notifier function for VFS, and init args */
 238         call->a_args.lock.fl.fl_flags |= FL_SLEEP;
 239         call->a_args.lock.fl.fl_lmops = &nlmsvc_lock_operations;
 240         nlmclnt_next_cookie(&call->a_args.cookie);
 241
 242         dprintk("lockd: created block %p...\n", block);
 243
 244         /* Create and initialize the block */
 245         block->b_daemon = rqstp->rq_server;
 246         block->b_host   = host;
 247         block->b_file   = file;
 248         block->b_fl = NULL;
 249         file->f_count++;
 250
 251         /* Add to file's list of blocks */
 252         list_add(&block->b_flist, &file->f_blocks);
 253
 254         /* Set up RPC arguments for callback */
 255         block->b_call = call;
 256         call->a_flags   = RPC_TASK_ASYNC;
 257         call->a_block = block;
 258
 259         return block;
 260
 261 failed_free:
 262         kfree(block);
 263 failed:
 264         nlmsvc_release_call(call);
 265         return NULL;
 266 }
 267
 268 /*
 269  * Delete a block.
 270  * It is the caller's responsibility to check whether the file
 271  * can be closed hereafter.
 272  */
 273 static int nlmsvc_unlink_block(struct nlm_block *block)
 274 {
 275         int status;
 276         dprintk("lockd: unlinking block %p...\n", block);
 277
 278         /* Remove block from list */
 279         status = posix_unblock_lock(&block->b_call->a_args.lock.fl);
 280         nlmsvc_remove_block(block);
 281         return status;
 282 }
 283
 284 static void nlmsvc_free_block(struct kref *kref)
 285 {
 286         struct nlm_block *block = container_of(kref, struct nlm_block, b_count);
 287         struct nlm_file         *file = block->b_file;
 288
 289         dprintk("lockd: freeing block %p...\n", block);
 290
 291         /* Remove block from file's list of blocks */
 292         list_del_init(&block->b_flist);
 293         mutex_unlock(&file->f_mutex);
 294
 295         nlmsvc_freegrantargs(block->b_call);
 296         nlmsvc_release_call(block->b_call);
 297         nlm_release_file(block->b_file);
 298         kfree(block->b_fl);
 299         kfree(block);
 300 }
 301
 302 static void nlmsvc_release_block(struct nlm_block *block)
 303 {
 304         if (block != NULL)
 305                 kref_put_mutex(&block->b_count, nlmsvc_free_block, &block->b_file->f_mutex);
 306 }
 307
 308 /*
 309  * Loop over all blocks and delete blocks held by
 310  * a matching host.
 311  */
 312 void nlmsvc_traverse_blocks(struct nlm_host *host,
 313                         struct nlm_file *file,
 314                         nlm_host_match_fn_t match)
 315 {
 316         struct nlm_block *block, *next;
 317
 318 restart:
 319         mutex_lock(&file->f_mutex);
 320         list_for_each_entry_safe(block, next, &file->f_blocks, b_flist) {
 321                 if (!match(block->b_host, host))
 322                         continue;
 323                 /* Do not destroy blocks that are not on
 324                  * the global retry list - why? */
 325                 if (list_empty(&block->b_list))
 326                         continue;
 327                 kref_get(&block->b_count);
 328                 mutex_unlock(&file->f_mutex);
 329                 nlmsvc_unlink_block(block);
 330                 nlmsvc_release_block(block);
 331                 goto restart;
 332         }
 333         mutex_unlock(&file->f_mutex);
 334 }
 335
 336 /*
 337  * Initialize arguments for GRANTED call. The nlm_rqst structure
 338  * has been cleared already.
 339  */
 340 static int nlmsvc_setgrantargs(struct nlm_rqst *call, struct nlm_lock *lock)
 341 {
 342         locks_copy_lock(&call->a_args.lock.fl, &lock->fl);
 343         memcpy(&call->a_args.lock.fh, &lock->fh, sizeof(call->a_args.lock.fh));
 344         call->a_args.lock.caller = utsname()->nodename;
 345         call->a_args.lock.oh.len = lock->oh.len;
 346
 347         /* set default data area */
 348         call->a_args.lock.oh.data = call->a_owner;
 349         call->a_args.lock.svid = lock->fl.fl_pid;
 350
 351         if (lock->oh.len > NLMCLNT_OHSIZE) {
 352                 void *data = kmalloc(lock->oh.len, GFP_KERNEL);
 353                 if (!data)
 354                         return 0;
 355                 call->a_args.lock.oh.data = (u8 *) data;
 356         }
 357
 358         memcpy(call->a_args.lock.oh.data, lock->oh.data, lock->oh.len);
 359         return 1;
 360 }
 361
 362 static void nlmsvc_freegrantargs(struct nlm_rqst *call)
 363 {
 364         if (call->a_args.lock.oh.data != call->a_owner)
 365                 kfree(call->a_args.lock.oh.data);
 366
 367         locks_release_private(&call->a_args.lock.fl);
 368 }
 369
 370 /*
 371  * Deferred lock request handling for non-blocking lock
 372  */
 373 static __be32
 374 nlmsvc_defer_lock_rqst(struct svc_rqst *rqstp, struct nlm_block *block)
 375 {
 376         __be32 status = nlm_lck_denied_nolocks;
 377
 378         block->b_flags |= B_QUEUED;
 379
 380         nlmsvc_insert_block(block, NLM_TIMEOUT);
 381
 382         block->b_cache_req = &rqstp->rq_chandle;
 383         if (rqstp->rq_chandle.defer) {
 384                 block->b_deferred_req =
 385                         rqstp->rq_chandle.defer(block->b_cache_req);
 386                 if (block->b_deferred_req != NULL)
 387                         status = nlm_drop_reply;
 388         }
 389         dprintk("lockd: nlmsvc_defer_lock_rqst block %p flags %d status %d\n",
 390                 block, block->b_flags, ntohl(status));
 391
 392         return status;
 393 }
 394
 395 /*
 396  * Attempt to establish a lock, and if it can't be granted, block it
 397  * if required.
 398  */
 399 __be32
 400 nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file,
 401             struct nlm_host *host, struct nlm_lock *lock, int wait,
 402             struct nlm_cookie *cookie, int reclaim)
 403 {
 404         struct nlm_block        *block = NULL;
 405         int                     error;
 406         __be32                  ret;
 407
 408         dprintk("lockd: nlmsvc_lock(%s/%ld, ty=%d, pi=%d, %Ld-%Ld, bl=%d)\n",
 409                                 file_inode(file->f_file)->i_sb->s_id,
 410                                 file_inode(file->f_file)->i_ino,
 411                                 lock->fl.fl_type, lock->fl.fl_pid,
 412                                 (long long)lock->fl.fl_start,
 413                                 (long long)lock->fl.fl_end,
 414                                 wait);
 415
 416         /* Lock file against concurrent access */
 417         mutex_lock(&file->f_mutex);
 418         /* Get existing block (in case client is busy-waiting)
 419          * or create new block
 420          */
 421         block = nlmsvc_lookup_block(file, lock);
 422         if (block == NULL) {
 423                 block = nlmsvc_create_block(rqstp, host, file, lock, cookie);
 424                 ret = nlm_lck_denied_nolocks;
 425                 if (block == NULL)
 426                         goto out;
 427                 lock = &block->b_call->a_args.lock;
 428         } else
 429                 lock->fl.fl_flags &= ~FL_SLEEP;
 430
 431         if (block->b_flags & B_QUEUED) {
 432                 dprintk("lockd: nlmsvc_lock deferred block %p flags %d\n",
 433                                                         block, block->b_flags);
 434                 if (block->b_granted) {
 435                         nlmsvc_unlink_block(block);
 436                         ret = nlm_granted;
 437                         goto out;
 438                 }
 439                 if (block->b_flags & B_TIMED_OUT) {
 440                         nlmsvc_unlink_block(block);
 441                         ret = nlm_lck_denied;
 442                         goto out;
 443                 }
 444                 ret = nlm_drop_reply;
 445                 goto out;
 446         }
 447
 448         if (locks_in_grace(SVC_NET(rqstp)) && !reclaim) {
 449                 ret = nlm_lck_denied_grace_period;
 450                 goto out;
 451         }
 452         if (reclaim && !locks_in_grace(SVC_NET(rqstp))) {
 453                 ret = nlm_lck_denied_grace_period;
 454                 goto out;
 455         }
 456
 457         if (!wait)
 458                 lock->fl.fl_flags &= ~FL_SLEEP;
 459         error = vfs_lock_file(file->f_file, F_SETLK, &lock->fl, NULL);
 460         lock->fl.fl_flags &= ~FL_SLEEP;
 461
 462         dprintk("lockd: vfs_lock_file returned %d\n", error);
 463         switch (error) {
 464                 case 0:
 465                         ret = nlm_granted;
 466                         goto out;
 467                 case -EAGAIN:
 468                         /*
 469                          * If this is a blocking request for an
 470                          * already pending lock request then we need
 471                          * to put it back on lockd's block list
 472                          */
 473                         if (wait)
 474                                 break;
 475                         ret = nlm_lck_denied;
 476                         goto out;
 477                 case FILE_LOCK_DEFERRED:
 478                         if (wait)
 479                                 break;
 480                         /* Filesystem lock operation is in progress
 481                            Add it to the queue waiting for callback */
 482                         ret = nlmsvc_defer_lock_rqst(rqstp, block);
 483                         goto out;
 484                 case -EDEADLK:
 485                         ret = nlm_deadlock;
 486                         goto out;
 487                 default:                        /* includes ENOLCK */
 488                         ret = nlm_lck_denied_nolocks;
 489                         goto out;
 490         }
 491
 492         ret = nlm_lck_blocked;
 493
 494         /* Append to list of blocked */
 495         nlmsvc_insert_block(block, NLM_NEVER);
 496 out:
 497         mutex_unlock(&file->f_mutex);
 498         nlmsvc_release_block(block);
 499         dprintk("lockd: nlmsvc_lock returned %u\n", ret);
 500         return ret;
 501 }
 502
 503 /*
 504  * Test for presence of a conflicting lock.
 505  */
 506 __be32
 507 nlmsvc_testlock(struct svc_rqst *rqstp, struct nlm_file *file,
 508                 struct nlm_host *host, struct nlm_lock *lock,
 509                 struct nlm_lock *conflock, struct nlm_cookie *cookie)
 510 {
 511         struct nlm_block        *block = NULL;
 512         int                     error;
 513         __be32                  ret;
 514
 515         dprintk("lockd: nlmsvc_testlock(%s/%ld, ty=%d, %Ld-%Ld)\n",
 516                                 file_inode(file->f_file)->i_sb->s_id,
 517                                 file_inode(file->f_file)->i_ino,
 518                                 lock->fl.fl_type,
 519                                 (long long)lock->fl.fl_start,
 520                                 (long long)lock->fl.fl_end);
 521
 522         /* Get existing block (in case client is busy-waiting) */
 523         block = nlmsvc_lookup_block(file, lock);
 524
 525         if (block == NULL) {
 526                 struct file_lock *conf = kzalloc(sizeof(*conf), GFP_KERNEL);
 527
 528                 if (conf == NULL)
 529                         return nlm_granted;
 530                 block = nlmsvc_create_block(rqstp, host, file, lock, cookie);
 531                 if (block == NULL) {
 532                         kfree(conf);
 533                         return nlm_granted;
 534                 }
 535                 block->b_fl = conf;
 536         }
 537         if (block->b_flags & B_QUEUED) {
 538                 dprintk("lockd: nlmsvc_testlock deferred block %p flags %d fl %p\n",
 539                         block, block->b_flags, block->b_fl);
 540                 if (block->b_flags & B_TIMED_OUT) {
 541                         nlmsvc_unlink_block(block);
 542                         ret = nlm_lck_denied;
 543                         goto out;
 544                 }
 545                 if (block->b_flags & B_GOT_CALLBACK) {
 546                         nlmsvc_unlink_block(block);
 547                         if (block->b_fl != NULL
 548                                         && block->b_fl->fl_type != F_UNLCK) {
 549                                 lock->fl = *block->b_fl;
 550                                 goto conf_lock;
 551                         } else {
 552                                 ret = nlm_granted;
 553                                 goto out;
 554                         }
 555                 }
 556                 ret = nlm_drop_reply;
 557                 goto out;
 558         }
 559
 560         if (locks_in_grace(SVC_NET(rqstp))) {
 561                 ret = nlm_lck_denied_grace_period;
 562                 goto out;
 563         }
 564         error = vfs_test_lock(file->f_file, &lock->fl);
 565         if (error == FILE_LOCK_DEFERRED) {
 566                 ret = nlmsvc_defer_lock_rqst(rqstp, block);
 567                 goto out;
 568         }
 569         if (error) {
 570                 ret = nlm_lck_denied_nolocks;
 571                 goto out;
 572         }
 573         if (lock->fl.fl_type == F_UNLCK) {
 574                 ret = nlm_granted;
 575                 goto out;
 576         }
 577
 578 conf_lock:
 579         dprintk("lockd: conflicting lock(ty=%d, %Ld-%Ld)\n",
 580                 lock->fl.fl_type, (long long)lock->fl.fl_start,
 581                 (long long)lock->fl.fl_end);
 582         conflock->caller = "somehost";  /* FIXME */
 583         conflock->len = strlen(conflock->caller);
 584         conflock->oh.len = 0;           /* don't return OH info */
 585         conflock->svid = lock->fl.fl_pid;
 586         conflock->fl.fl_type = lock->fl.fl_type;
 587         conflock->fl.fl_start = lock->fl.fl_start;
 588         conflock->fl.fl_end = lock->fl.fl_end;
 589         locks_release_private(&lock->fl);
 590         ret = nlm_lck_denied;
 591 out:
 592         if (block)
 593                 nlmsvc_release_block(block);
 594         return ret;
 595 }
 596
 597 /*
 598  * Remove a lock.
 599  * This implies a CANCEL call: We send a GRANT_MSG, the client replies
 600  * with a GRANT_RES call which gets lost, and calls UNLOCK immediately
 601  * afterwards. In this case the block will still be there, and hence
 602  * must be removed.
 603  */
 604 __be32
 605 nlmsvc_unlock(struct net *net, struct nlm_file *file, struct nlm_lock *lock)
 606 {
 607         int     error;
 608
 609         dprintk("lockd: nlmsvc_unlock(%s/%ld, pi=%d, %Ld-%Ld)\n",
 610                                 file_inode(file->f_file)->i_sb->s_id,
 611                                 file_inode(file->f_file)->i_ino,
 612                                 lock->fl.fl_pid,
 613                                 (long long)lock->fl.fl_start,
 614                                 (long long)lock->fl.fl_end);
 615
 616         /* First, cancel any lock that might be there */
 617         nlmsvc_cancel_blocked(net, file, lock);
 618
 619         lock->fl.fl_type = F_UNLCK;
 620         error = vfs_lock_file(file->f_file, F_SETLK, &lock->fl, NULL);
 621
 622         return (error < 0)? nlm_lck_denied_nolocks : nlm_granted;
 623 }
 624
 625 /*
 626  * Cancel a previously blocked request.
 627  *
 628  * A cancel request always overrides any grant that may currently
 629  * be in progress.
 630  * The calling procedure must check whether the file can be closed.
 631  */
 632 __be32
 633 nlmsvc_cancel_blocked(struct net *net, struct nlm_file *file, struct nlm_lock *lock)
 634 {
 635         struct nlm_block        *block;
 636         int status = 0;
 637
 638         dprintk("lockd: nlmsvc_cancel(%s/%ld, pi=%d, %Ld-%Ld)\n",
 639                                 file_inode(file->f_file)->i_sb->s_id,
 640                                 file_inode(file->f_file)->i_ino,
 641                                 lock->fl.fl_pid,
 642                                 (long long)lock->fl.fl_start,
 643                                 (long long)lock->fl.fl_end);
 644
 645         if (locks_in_grace(net))
 646                 return nlm_lck_denied_grace_period;
 647
 648         mutex_lock(&file->f_mutex);
 649         block = nlmsvc_lookup_block(file, lock);
 650         mutex_unlock(&file->f_mutex);
 651         if (block != NULL) {
 652                 vfs_cancel_lock(block->b_file->f_file,
 653                                 &block->b_call->a_args.lock.fl);
 654                 status = nlmsvc_unlink_block(block);
 655                 nlmsvc_release_block(block);
 656         }
 657         return status ? nlm_lck_denied : nlm_granted;
 658 }
 659
 660 /*
 661  * This is a callback from the filesystem for VFS file lock requests.
 662  * It will be used if lm_grant is defined and the filesystem can not
 663  * respond to the request immediately.
 664  * For GETLK request it will copy the reply to the nlm_block.
 665  * For SETLK or SETLKW request it will get the local posix lock.
 666  * In all cases it will move the block to the head of nlm_blocked q where
 667  * nlmsvc_retry_blocked() can send back a reply for SETLKW or revisit the
 668  * deferred rpc for GETLK and SETLK.
 669  */
 670 static void
 671 nlmsvc_update_deferred_block(struct nlm_block *block, int result)
 672 {
 673         block->b_flags |= B_GOT_CALLBACK;
 674         if (result == 0)
 675                 block->b_granted = 1;
 676         else
 677                 block->b_flags |= B_TIMED_OUT;
 678 }
 679
 680 static int nlmsvc_grant_deferred(struct file_lock *fl, int result)
 681 {
 682         struct nlm_block *block;
 683         int rc = -ENOENT;
 684
 685         spin_lock(&nlm_blocked_lock);
 686         list_for_each_entry(block, &nlm_blocked, b_list) {
 687                 if (nlm_compare_locks(&block->b_call->a_args.lock.fl, fl)) {
 688                         dprintk("lockd: nlmsvc_notify_blocked block %p flags %d\n",
 689                                                         block, block->b_flags);
 690                         if (block->b_flags & B_QUEUED) {
 691                                 if (block->b_flags & B_TIMED_OUT) {
 692                                         rc = -ENOLCK;
 693                                         break;
 694                                 }
 695                                 nlmsvc_update_deferred_block(block, result);
 696                         } else if (result == 0)
 697                                 block->b_granted = 1;
 698
 699                         nlmsvc_insert_block_locked(block, 0);
 700                         svc_wake_up(block->b_daemon);
 701                         rc = 0;
 702                         break;
 703                 }
 704         }
 705         spin_unlock(&nlm_blocked_lock);
 706         if (rc == -ENOENT)
 707                 printk(KERN_WARNING "lockd: grant for unknown block\n");
 708         return rc;
 709 }
 710
 711 /*
 712  * Unblock a blocked lock request. This is a callback invoked from the
 713  * VFS layer when a lock on which we blocked is removed.
 714  *
 715  * This function doesn't grant the blocked lock instantly, but rather moves
 716  * the block to the head of nlm_blocked where it can be picked up by lockd.
 717  */
 718 static void
 719 nlmsvc_notify_blocked(struct file_lock *fl)
 720 {
 721         struct nlm_block        *block;
 722
 723         dprintk("lockd: VFS unblock notification for block %p\n", fl);
 724         spin_lock(&nlm_blocked_lock);
 725         list_for_each_entry(block, &nlm_blocked, b_list) {
 726                 if (nlm_compare_locks(&block->b_call->a_args.lock.fl, fl)) {
 727                         nlmsvc_insert_block_locked(block, 0);
 728                         spin_unlock(&nlm_blocked_lock);
 729                         svc_wake_up(block->b_daemon);
 730                         return;
 731                 }
 732         }
 733         spin_unlock(&nlm_blocked_lock);
 734         printk(KERN_WARNING "lockd: notification for unknown block!\n");
 735 }
 736
 737 static int nlmsvc_same_owner(struct file_lock *fl1, struct file_lock *fl2)
 738 {
 739         return fl1->fl_owner == fl2->fl_owner && fl1->fl_pid == fl2->fl_pid;
 740 }
 741
 742 /*
 743  * Since NLM uses two "keys" for tracking locks, we need to hash them down
 744  * to one for the blocked_hash. Here, we're just xor'ing the host address
 745  * with the pid in order to create a key value for picking a hash bucket.
 746  */
 747 static unsigned long
 748 nlmsvc_owner_key(struct file_lock *fl)
 749 {
 750         return (unsigned long)fl->fl_owner ^ (unsigned long)fl->fl_pid;
 751 }
 752
 753 const struct lock_manager_operations nlmsvc_lock_operations = {
 754         .lm_compare_owner = nlmsvc_same_owner,
 755         .lm_owner_key = nlmsvc_owner_key,
 756         .lm_notify = nlmsvc_notify_blocked,
 757         .lm_grant = nlmsvc_grant_deferred,
 758 };
 759
 760 /*
 761  * Try to claim a lock that was previously blocked.
 762  *
 763  * Note that we use both the RPC_GRANTED_MSG call _and_ an async
 764  * RPC thread when notifying the client. This seems like overkill...
 765  * Here's why:
 766  *  -   we don't want to use a synchronous RPC thread, otherwise
 767  *      we might find ourselves hanging on a dead portmapper.
 768  *  -   Some lockd implementations (e.g. HP) don't react to
 769  *      RPC_GRANTED calls; they seem to insist on RPC_GRANTED_MSG calls.
 770  */
 771 static void
 772 nlmsvc_grant_blocked(struct nlm_block *block)
 773 {
 774         struct nlm_file         *file = block->b_file;
 775         struct nlm_lock         *lock = &block->b_call->a_args.lock;
 776         int                     error;
 777         loff_t                  fl_start, fl_end;
 778
 779         dprintk("lockd: grant blocked lock %p\n", block);
 780
 781         kref_get(&block->b_count);
 782
 783         /* Unlink block request from list */
 784         nlmsvc_unlink_block(block);
 785
 786         /* If b_granted is true this means we've been here before.
 787          * Just retry the grant callback, possibly refreshing the RPC
 788          * binding */
 789         if (block->b_granted) {
 790                 nlm_rebind_host(block->b_host);
 791                 goto callback;
 792         }
 793
 794         /* Try the lock operation again */
 795         /* vfs_lock_file() can mangle fl_start and fl_end, but we need
 796          * them unchanged for the GRANT_MSG
 797          */
 798         lock->fl.fl_flags |= FL_SLEEP;
 799         fl_start = lock->fl.fl_start;
 800         fl_end = lock->fl.fl_end;
 801         error = vfs_lock_file(file->f_file, F_SETLK, &lock->fl, NULL);
 802         lock->fl.fl_flags &= ~FL_SLEEP;
 803         lock->fl.fl_start = fl_start;
 804         lock->fl.fl_end = fl_end;
 805
 806         switch (error) {
 807         case 0:
 808                 break;
 809         case FILE_LOCK_DEFERRED:
 810                 dprintk("lockd: lock still blocked error %d\n", error);
 811                 nlmsvc_insert_block(block, NLM_NEVER);
 812                 nlmsvc_release_block(block);
 813                 return;
 814         default:
 815                 printk(KERN_WARNING "lockd: unexpected error %d in %s!\n",
 816                                 -error, __func__);
 817                 nlmsvc_insert_block(block, 10 * HZ);
 818                 nlmsvc_release_block(block);
 819                 return;
 820         }
 821
 822 callback:
 823         /* Lock was granted by VFS. */
 824         dprintk("lockd: GRANTing blocked lock.\n");
 825         block->b_granted = 1;
 826
 827         /* keep block on the list, but don't reattempt until the RPC
 828          * completes or the submission fails
 829          */
 830         nlmsvc_insert_block(block, NLM_NEVER);
 831
 832         /* Call the client -- use a soft RPC task since nlmsvc_retry_blocked
 833          * will queue up a new one if this one times out
 834          */
 835         error = nlm_async_call(block->b_call, NLMPROC_GRANTED_MSG,
 836                                 &nlmsvc_grant_ops);
 837
 838         /* RPC submission failed, wait a bit and retry */
 839         if (error < 0)
 840                 nlmsvc_insert_block(block, 10 * HZ);
 841 }
 842
 843 /*
 844  * This is the callback from the RPC layer when the NLM_GRANTED_MSG
 845  * RPC call has succeeded or timed out.
 846  * Like all RPC callbacks, it is invoked by the rpciod process, so it
 847  * better not sleep. Therefore, we put the blocked lock on the nlm_blocked
 848  * chain once more in order to have it removed by lockd itself (which can
 849  * then sleep on the file semaphore without disrupting e.g. the nfs client).
 850  */
 851 static void nlmsvc_grant_callback(struct rpc_task *task, void *data)
 852 {
 853         struct nlm_rqst         *call = data;
 854         struct nlm_block        *block = call->a_block;
 855         unsigned long           timeout;
 856
 857         dprintk("lockd: GRANT_MSG RPC callback\n");
 858
 859         spin_lock(&nlm_blocked_lock);
 860         /* if the block is not on a list at this point then it has
 861          * been invalidated. Don't try to requeue it.
 862          *
 863          * FIXME: it's possible that the block is removed from the list
 864          * after this check but before the nlmsvc_insert_block. In that
 865          * case it will be added back. Perhaps we need better locking
 866          * for nlm_blocked?
 867          */
 868         if (list_empty(&block->b_list))
 869                 goto out;
 870
 871         /* Technically, we should down the file semaphore here. Since we
 872          * move the block towards the head of the queue only, no harm
 873          * can be done, though. */
 874         if (task->tk_status < 0) {
 875                 /* RPC error: Re-insert for retransmission */
 876                 timeout = 10 * HZ;
 877         } else {
 878                 /* Call was successful, now wait for client callback */
 879                 timeout = 60 * HZ;
 880         }
 881         nlmsvc_insert_block_locked(block, timeout);
 882         svc_wake_up(block->b_daemon);
 883 out:
 884         spin_unlock(&nlm_blocked_lock);
 885 }
 886
 887 /*
 888  * FIXME: nlmsvc_release_block() grabs a mutex.  This is not allowed for an
 889  * .rpc_release rpc_call_op
 890  */
 891 static void nlmsvc_grant_release(void *data)
 892 {
 893         struct nlm_rqst         *call = data;
 894         nlmsvc_release_block(call->a_block);
 895 }
 896
 897 static const struct rpc_call_ops nlmsvc_grant_ops = {
 898         .rpc_call_done = nlmsvc_grant_callback,
 899         .rpc_release = nlmsvc_grant_release,
 900 };
 901
 902 /*
 903  * We received a GRANT_RES callback. Try to find the corresponding
 904  * block.
 905  */
 906 void
 907 nlmsvc_grant_reply(struct nlm_cookie *cookie, __be32 status)
 908 {
 909         struct nlm_block        *block;
 910
 911         dprintk("grant_reply: looking for cookie %x, s=%d \n",
 912                 *(unsigned int *)(cookie->data), status);
 913         if (!(block = nlmsvc_find_block(cookie)))
 914                 return;
 915
 916         if (block) {
 917                 if (status == nlm_lck_denied_grace_period) {
 918                         /* Try again in a couple of seconds */
 919                         nlmsvc_insert_block(block, 10 * HZ);
 920                 } else {
 921                         /* Lock is now held by client, or has been rejected.
 922                          * In both cases, the block should be removed. */
 923                         nlmsvc_unlink_block(block);
 924                 }
 925         }
 926         nlmsvc_release_block(block);
 927 }
 928
 929 /* Helper function to handle retry of a deferred block.
 930  * If it is a blocking lock, call grant_blocked.
 931  * For a non-blocking lock or test lock, revisit the request.
 932  */
 933 static void
 934 retry_deferred_block(struct nlm_block *block)
 935 {
 936         if (!(block->b_flags & B_GOT_CALLBACK))
 937                 block->b_flags |= B_TIMED_OUT;
 938         nlmsvc_insert_block(block, NLM_TIMEOUT);
 939         dprintk("revisit block %p flags %d\n",  block, block->b_flags);
 940         if (block->b_deferred_req) {
 941                 block->b_deferred_req->revisit(block->b_deferred_req, 0);
 942                 block->b_deferred_req = NULL;
 943         }
 944 }
 945
 946 /*
 947  * Retry all blocked locks that have been notified. This is where lockd
 948  * picks up locks that can be granted, or grant notifications that must
 949  * be retransmitted.
 950  */
 951 unsigned long
 952 nlmsvc_retry_blocked(void)
 953 {
 954         unsigned long   timeout = MAX_SCHEDULE_TIMEOUT;
 955         struct nlm_block *block;
 956
 957         spin_lock(&nlm_blocked_lock);
 958         while (!list_empty(&nlm_blocked) && !kthread_should_stop()) {
 959                 block = list_entry(nlm_blocked.next, struct nlm_block, b_list);
 960
 961                 if (block->b_when == NLM_NEVER)
 962                         break;
 963                 if (time_after(block->b_when, jiffies)) {
 964                         timeout = block->b_when - jiffies;
 965                         break;
 966                 }
 967                 spin_unlock(&nlm_blocked_lock);
 968
 969                 dprintk("nlmsvc_retry_blocked(%p, when=%ld)\n",
 970                         block, block->b_when);
 971                 if (block->b_flags & B_QUEUED) {
 972                         dprintk("nlmsvc_retry_blocked delete block (%p, granted=%d, flags=%d)\n",
 973                                 block, block->b_granted, block->b_flags);
 974                         retry_deferred_block(block);
 975                 } else
 976                         nlmsvc_grant_blocked(block);
 977                 spin_lock(&nlm_blocked_lock);
 978         }
 979         spin_unlock(&nlm_blocked_lock);
 980
 981         return timeout;
 982 }