fs/lockd/svclock.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * linux/fs/lockd/svclock.c
   4  *
   5  * Handling of server-side locks, mostly of the blocked variety.
   6  * This is the ugliest part of lockd because we tread on very thin ice.
   7  * GRANT and CANCEL calls may get stuck, meet in mid-flight, etc.
   8  * IMNSHO introducing the grant callback into the NLM protocol was one
   9  * of the worst ideas Sun ever had. Except maybe for the idea of doing
  10  * NFS file locking at all.
  11  *
  12  * I'm trying hard to avoid race conditions by protecting most accesses
  13  * to a file's list of blocked locks through a semaphore. The global
  14  * list of blocked locks is not protected in this fashion however.
  15  * Therefore, some functions (such as the RPC callback for the async grant
  16  * call) move blocked locks towards the head of the list *while some other
  17  * process might be traversing it*. This should not be a problem in
  18  * practice, because this will only cause functions traversing the list
  19  * to visit some blocks twice.
  20  *
  21  * Copyright (C) 1996, Olaf Kirch <okir@monad.swb.de>
  22  */
  23
  24 #include <linux/types.h>
  25 #include <linux/slab.h>
  26 #include <linux/errno.h>
  27 #include <linux/kernel.h>
  28 #include <linux/sched.h>
  29 #include <linux/sunrpc/clnt.h>
  30 #include <linux/sunrpc/svc_xprt.h>
  31 #include <linux/lockd/nlm.h>
  32 #include <linux/lockd/lockd.h>
  33 #include <linux/kthread.h>
  34
  35 #define NLMDBG_FACILITY         NLMDBG_SVCLOCK
  36
  37 #ifdef CONFIG_LOCKD_V4
  38 #define nlm_deadlock    nlm4_deadlock
  39 #else
  40 #define nlm_deadlock    nlm_lck_denied
  41 #endif
  42
  43 static void nlmsvc_release_block(struct nlm_block *block);
  44 static void     nlmsvc_insert_block(struct nlm_block *block, unsigned long);
  45 static void     nlmsvc_remove_block(struct nlm_block *block);
  46
  47 static int nlmsvc_setgrantargs(struct nlm_rqst *call, struct nlm_lock *lock);
  48 static void nlmsvc_freegrantargs(struct nlm_rqst *call);
  49 static const struct rpc_call_ops nlmsvc_grant_ops;
  50
  51 /*
  52  * The list of blocked locks to retry
  53  */
  54 static LIST_HEAD(nlm_blocked);
  55 static DEFINE_SPINLOCK(nlm_blocked_lock);
  56
  57 #if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
  58 static const char *nlmdbg_cookie2a(const struct nlm_cookie *cookie)
  59 {
  60         /*
  61          * We can get away with a static buffer because this is only called
  62          * from lockd, which is single-threaded.
  63          */
  64         static char buf[2*NLM_MAXCOOKIELEN+1];
  65         unsigned int i, len = sizeof(buf);
  66         char *p = buf;
  67
  68         len--;  /* allow for trailing \0 */
  69         if (len < 3)
  70                 return "???";
  71         for (i = 0 ; i < cookie->len ; i++) {
  72                 if (len < 2) {
  73                         strcpy(p-3, "...");
  74                         break;
  75                 }
  76                 sprintf(p, "%02x", cookie->data[i]);
  77                 p += 2;
  78                 len -= 2;
  79         }
  80         *p = '\0';
  81
  82         return buf;
  83 }
  84 #endif
  85
  86 /*
  87  * Insert a blocked lock into the global list
  88  */
  89 static void
  90 nlmsvc_insert_block_locked(struct nlm_block *block, unsigned long when)
  91 {
  92         struct nlm_block *b;
  93         struct list_head *pos;
  94
  95         dprintk("lockd: nlmsvc_insert_block(%p, %ld)\n", block, when);
  96         if (list_empty(&block->b_list)) {
  97                 kref_get(&block->b_count);
  98         } else {
  99                 list_del_init(&block->b_list);
 100         }
 101
 102         pos = &nlm_blocked;
 103         if (when != NLM_NEVER) {
 104                 if ((when += jiffies) == NLM_NEVER)
 105                         when ++;
 106                 list_for_each(pos, &nlm_blocked) {
 107                         b = list_entry(pos, struct nlm_block, b_list);
 108                         if (time_after(b->b_when,when) || b->b_when == NLM_NEVER)
 109                                 break;
 110                 }
 111                 /* On normal exit from the loop, pos == &nlm_blocked,
 112                  * so we will be adding to the end of the list - good
 113                  */
 114         }
 115
 116         list_add_tail(&block->b_list, pos);
 117         block->b_when = when;
 118 }
 119
 120 static void nlmsvc_insert_block(struct nlm_block *block, unsigned long when)
 121 {
 122         spin_lock(&nlm_blocked_lock);
 123         nlmsvc_insert_block_locked(block, when);
 124         spin_unlock(&nlm_blocked_lock);
 125 }
 126
 127 /*
 128  * Remove a block from the global list
 129  */
 130 static inline void
 131 nlmsvc_remove_block(struct nlm_block *block)
 132 {
 133         if (!list_empty(&block->b_list)) {
 134                 spin_lock(&nlm_blocked_lock);
 135                 list_del_init(&block->b_list);
 136                 spin_unlock(&nlm_blocked_lock);
 137                 nlmsvc_release_block(block);
 138         }
 139 }
 140
 141 /*
 142  * Find a block for a given lock
 143  */
 144 static struct nlm_block *
 145 nlmsvc_lookup_block(struct nlm_file *file, struct nlm_lock *lock)
 146 {
 147         struct nlm_block        *block;
 148         struct file_lock        *fl;
 149
 150         dprintk("lockd: nlmsvc_lookup_block f=%p pd=%d %Ld-%Ld ty=%d\n",
 151                                 file, lock->fl.fl_pid,
 152                                 (long long)lock->fl.fl_start,
 153                                 (long long)lock->fl.fl_end, lock->fl.fl_type);
 154         list_for_each_entry(block, &nlm_blocked, b_list) {
 155                 fl = &block->b_call->a_args.lock.fl;
 156                 dprintk("lockd: check f=%p pd=%d %Ld-%Ld ty=%d cookie=%s\n",
 157                                 block->b_file, fl->fl_pid,
 158                                 (long long)fl->fl_start,
 159                                 (long long)fl->fl_end, fl->fl_type,
 160                                 nlmdbg_cookie2a(&block->b_call->a_args.cookie));
 161                 if (block->b_file == file && nlm_compare_locks(fl, &lock->fl)) {
 162                         kref_get(&block->b_count);
 163                         return block;
 164                 }
 165         }
 166
 167         return NULL;
 168 }
 169
 170 static inline int nlm_cookie_match(struct nlm_cookie *a, struct nlm_cookie *b)
 171 {
 172         if (a->len != b->len)
 173                 return 0;
 174         if (memcmp(a->data, b->data, a->len))
 175                 return 0;
 176         return 1;
 177 }
 178
 179 /*
 180  * Find a block with a given NLM cookie.
 181  */
 182 static inline struct nlm_block *
 183 nlmsvc_find_block(struct nlm_cookie *cookie)
 184 {
 185         struct nlm_block *block;
 186
 187         list_for_each_entry(block, &nlm_blocked, b_list) {
 188                 if (nlm_cookie_match(&block->b_call->a_args.cookie,cookie))
 189                         goto found;
 190         }
 191
 192         return NULL;
 193
 194 found:
 195         dprintk("nlmsvc_find_block(%s): block=%p\n", nlmdbg_cookie2a(cookie), block);
 196         kref_get(&block->b_count);
 197         return block;
 198 }
 199
 200 /*
 201  * Create a block and initialize it.
 202  *
 203  * Note: we explicitly set the cookie of the grant reply to that of
 204  * the blocked lock request. The spec explicitly mentions that the client
 205  * should _not_ rely on the callback containing the same cookie as the
 206  * request, but (as I found out later) that's because some implementations
 207  * do just this. Never mind the standards comittees, they support our
 208  * logging industries.
 209  *
 210  * 10 years later: I hope we can safely ignore these old and broken
 211  * clients by now. Let's fix this so we can uniquely identify an incoming
 212  * GRANTED_RES message by cookie, without having to rely on the client's IP
 213  * address. --okir
 214  */
 215 static struct nlm_block *
 216 nlmsvc_create_block(struct svc_rqst *rqstp, struct nlm_host *host,
 217                     struct nlm_file *file, struct nlm_lock *lock,
 218                     struct nlm_cookie *cookie)
 219 {
 220         struct nlm_block        *block;
 221         struct nlm_rqst         *call = NULL;
 222
 223         call = nlm_alloc_call(host);
 224         if (call == NULL)
 225                 return NULL;
 226
 227         /* Allocate memory for block, and initialize arguments */
 228         block = kzalloc(sizeof(*block), GFP_KERNEL);
 229         if (block == NULL)
 230                 goto failed;
 231         kref_init(&block->b_count);
 232         INIT_LIST_HEAD(&block->b_list);
 233         INIT_LIST_HEAD(&block->b_flist);
 234
 235         if (!nlmsvc_setgrantargs(call, lock))
 236                 goto failed_free;
 237
 238         /* Set notifier function for VFS, and init args */
 239         call->a_args.lock.fl.fl_flags |= FL_SLEEP;
 240         call->a_args.lock.fl.fl_lmops = &nlmsvc_lock_operations;
 241         nlmclnt_next_cookie(&call->a_args.cookie);
 242
 243         dprintk("lockd: created block %p...\n", block);
 244
 245         /* Create and initialize the block */
 246         block->b_daemon = rqstp->rq_server;
 247         block->b_host   = host;
 248         block->b_file   = file;
 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 = locks_delete_block(&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);
 299 }
 300
 301 static void nlmsvc_release_block(struct nlm_block *block)
 302 {
 303         if (block != NULL)
 304                 kref_put_mutex(&block->b_count, nlmsvc_free_block, &block->b_file->f_mutex);
 305 }
 306
 307 /*
 308  * Loop over all blocks and delete blocks held by
 309  * a matching host.
 310  */
 311 void nlmsvc_traverse_blocks(struct nlm_host *host,
 312                         struct nlm_file *file,
 313                         nlm_host_match_fn_t match)
 314 {
 315         struct nlm_block *block, *next;
 316
 317 restart:
 318         mutex_lock(&file->f_mutex);
 319         list_for_each_entry_safe(block, next, &file->f_blocks, b_flist) {
 320                 if (!match(block->b_host, host))
 321                         continue;
 322                 /* Do not destroy blocks that are not on
 323                  * the global retry list - why? */
 324                 if (list_empty(&block->b_list))
 325                         continue;
 326                 kref_get(&block->b_count);
 327                 mutex_unlock(&file->f_mutex);
 328                 nlmsvc_unlink_block(block);
 329                 nlmsvc_release_block(block);
 330                 goto restart;
 331         }
 332         mutex_unlock(&file->f_mutex);
 333 }
 334
 335 static struct nlm_lockowner *
 336 nlmsvc_get_lockowner(struct nlm_lockowner *lockowner)
 337 {
 338         refcount_inc(&lockowner->count);
 339         return lockowner;
 340 }
 341
 342 static void nlmsvc_put_lockowner(struct nlm_lockowner *lockowner)
 343 {
 344         if (!refcount_dec_and_lock(&lockowner->count, &lockowner->host->h_lock))
 345                 return;
 346         list_del(&lockowner->list);
 347         spin_unlock(&lockowner->host->h_lock);
 348         nlmsvc_release_host(lockowner->host);
 349         kfree(lockowner);
 350 }
 351
 352 static struct nlm_lockowner *__nlmsvc_find_lockowner(struct nlm_host *host, pid_t pid)
 353 {
 354         struct nlm_lockowner *lockowner;
 355         list_for_each_entry(lockowner, &host->h_lockowners, list) {
 356                 if (lockowner->pid != pid)
 357                         continue;
 358                 return nlmsvc_get_lockowner(lockowner);
 359         }
 360         return NULL;
 361 }
 362
 363 static struct nlm_lockowner *nlmsvc_find_lockowner(struct nlm_host *host, pid_t pid)
 364 {
 365         struct nlm_lockowner *res, *new = NULL;
 366
 367         spin_lock(&host->h_lock);
 368         res = __nlmsvc_find_lockowner(host, pid);
 369
 370         if (res == NULL) {
 371                 spin_unlock(&host->h_lock);
 372                 new = kmalloc(sizeof(*res), GFP_KERNEL);
 373                 spin_lock(&host->h_lock);
 374                 res = __nlmsvc_find_lockowner(host, pid);
 375                 if (res == NULL && new != NULL) {
 376                         res = new;
 377                         /* fs/locks.c will manage the refcount through lock_ops */
 378                         refcount_set(&new->count, 1);
 379                         new->pid = pid;
 380                         new->host = nlm_get_host(host);
 381                         list_add(&new->list, &host->h_lockowners);
 382                         new = NULL;
 383                 }
 384         }
 385
 386         spin_unlock(&host->h_lock);
 387         kfree(new);
 388         return res;
 389 }
 390
 391 void
 392 nlmsvc_release_lockowner(struct nlm_lock *lock)
 393 {
 394         if (lock->fl.fl_owner)
 395                 nlmsvc_put_lockowner(lock->fl.fl_owner);
 396 }
 397
 398 static void nlmsvc_locks_copy_lock(struct file_lock *new, struct file_lock *fl)
 399 {
 400         struct nlm_lockowner *nlm_lo = (struct nlm_lockowner *)fl->fl_owner;
 401         new->fl_owner = nlmsvc_get_lockowner(nlm_lo);
 402 }
 403
 404 static void nlmsvc_locks_release_private(struct file_lock *fl)
 405 {
 406         nlmsvc_put_lockowner((struct nlm_lockowner *)fl->fl_owner);
 407 }
 408
 409 static const struct file_lock_operations nlmsvc_lock_ops = {
 410         .fl_copy_lock = nlmsvc_locks_copy_lock,
 411         .fl_release_private = nlmsvc_locks_release_private,
 412 };
 413
 414 void nlmsvc_locks_init_private(struct file_lock *fl, struct nlm_host *host,
 415                                                 pid_t pid)
 416 {
 417         fl->fl_owner = nlmsvc_find_lockowner(host, pid);
 418         if (fl->fl_owner != NULL)
 419                 fl->fl_ops = &nlmsvc_lock_ops;
 420 }
 421
 422 /*
 423  * Initialize arguments for GRANTED call. The nlm_rqst structure
 424  * has been cleared already.
 425  */
 426 static int nlmsvc_setgrantargs(struct nlm_rqst *call, struct nlm_lock *lock)
 427 {
 428         locks_copy_lock(&call->a_args.lock.fl, &lock->fl);
 429         memcpy(&call->a_args.lock.fh, &lock->fh, sizeof(call->a_args.lock.fh));
 430         call->a_args.lock.caller = utsname()->nodename;
 431         call->a_args.lock.oh.len = lock->oh.len;
 432
 433         /* set default data area */
 434         call->a_args.lock.oh.data = call->a_owner;
 435         call->a_args.lock.svid = ((struct nlm_lockowner *)lock->fl.fl_owner)->pid;
 436
 437         if (lock->oh.len > NLMCLNT_OHSIZE) {
 438                 void *data = kmalloc(lock->oh.len, GFP_KERNEL);
 439                 if (!data)
 440                         return 0;
 441                 call->a_args.lock.oh.data = (u8 *) data;
 442         }
 443
 444         memcpy(call->a_args.lock.oh.data, lock->oh.data, lock->oh.len);
 445         return 1;
 446 }
 447
 448 static void nlmsvc_freegrantargs(struct nlm_rqst *call)
 449 {
 450         if (call->a_args.lock.oh.data != call->a_owner)
 451                 kfree(call->a_args.lock.oh.data);
 452
 453         locks_release_private(&call->a_args.lock.fl);
 454 }
 455
 456 /*
 457  * Deferred lock request handling for non-blocking lock
 458  */
 459 static __be32
 460 nlmsvc_defer_lock_rqst(struct svc_rqst *rqstp, struct nlm_block *block)
 461 {
 462         __be32 status = nlm_lck_denied_nolocks;
 463
 464         block->b_flags |= B_QUEUED;
 465
 466         nlmsvc_insert_block(block, NLM_TIMEOUT);
 467
 468         block->b_cache_req = &rqstp->rq_chandle;
 469         if (rqstp->rq_chandle.defer) {
 470                 block->b_deferred_req =
 471                         rqstp->rq_chandle.defer(block->b_cache_req);
 472                 if (block->b_deferred_req != NULL)
 473                         status = nlm_drop_reply;
 474         }
 475         dprintk("lockd: nlmsvc_defer_lock_rqst block %p flags %d status %d\n",
 476                 block, block->b_flags, ntohl(status));
 477
 478         return status;
 479 }
 480
 481 /*
 482  * Attempt to establish a lock, and if it can't be granted, block it
 483  * if required.
 484  */
 485 __be32
 486 nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file,
 487             struct nlm_host *host, struct nlm_lock *lock, int wait,
 488             struct nlm_cookie *cookie, int reclaim)
 489 {
 490         struct nlm_block        *block = NULL;
 491         int                     error;
 492         __be32                  ret;
 493
 494         dprintk("lockd: nlmsvc_lock(%s/%ld, ty=%d, pi=%d, %Ld-%Ld, bl=%d)\n",
 495                                 locks_inode(file->f_file)->i_sb->s_id,
 496                                 locks_inode(file->f_file)->i_ino,
 497                                 lock->fl.fl_type, lock->fl.fl_pid,
 498                                 (long long)lock->fl.fl_start,
 499                                 (long long)lock->fl.fl_end,
 500                                 wait);
 501
 502         /* Lock file against concurrent access */
 503         mutex_lock(&file->f_mutex);
 504         /* Get existing block (in case client is busy-waiting)
 505          * or create new block
 506          */
 507         block = nlmsvc_lookup_block(file, lock);
 508         if (block == NULL) {
 509                 block = nlmsvc_create_block(rqstp, host, file, lock, cookie);
 510                 ret = nlm_lck_denied_nolocks;
 511                 if (block == NULL)
 512                         goto out;
 513                 lock = &block->b_call->a_args.lock;
 514         } else
 515                 lock->fl.fl_flags &= ~FL_SLEEP;
 516
 517         if (block->b_flags & B_QUEUED) {
 518                 dprintk("lockd: nlmsvc_lock deferred block %p flags %d\n",
 519                                                         block, block->b_flags);
 520                 if (block->b_granted) {
 521                         nlmsvc_unlink_block(block);
 522                         ret = nlm_granted;
 523                         goto out;
 524                 }
 525                 if (block->b_flags & B_TIMED_OUT) {
 526                         nlmsvc_unlink_block(block);
 527                         ret = nlm_lck_denied;
 528                         goto out;
 529                 }
 530                 ret = nlm_drop_reply;
 531                 goto out;
 532         }
 533
 534         if (locks_in_grace(SVC_NET(rqstp)) && !reclaim) {
 535                 ret = nlm_lck_denied_grace_period;
 536                 goto out;
 537         }
 538         if (reclaim && !locks_in_grace(SVC_NET(rqstp))) {
 539                 ret = nlm_lck_denied_grace_period;
 540                 goto out;
 541         }
 542
 543         if (!wait)
 544                 lock->fl.fl_flags &= ~FL_SLEEP;
 545         error = vfs_lock_file(file->f_file, F_SETLK, &lock->fl, NULL);
 546         lock->fl.fl_flags &= ~FL_SLEEP;
 547
 548         dprintk("lockd: vfs_lock_file returned %d\n", error);
 549         switch (error) {
 550                 case 0:
 551                         ret = nlm_granted;
 552                         goto out;
 553                 case -EAGAIN:
 554                         /*
 555                          * If this is a blocking request for an
 556                          * already pending lock request then we need
 557                          * to put it back on lockd's block list
 558                          */
 559                         if (wait)
 560                                 break;
 561                         ret = nlm_lck_denied;
 562                         goto out;
 563                 case FILE_LOCK_DEFERRED:
 564                         if (wait)
 565                                 break;
 566                         /* Filesystem lock operation is in progress
 567                            Add it to the queue waiting for callback */
 568                         ret = nlmsvc_defer_lock_rqst(rqstp, block);
 569                         goto out;
 570                 case -EDEADLK:
 571                         ret = nlm_deadlock;
 572                         goto out;
 573                 default:                        /* includes ENOLCK */
 574                         ret = nlm_lck_denied_nolocks;
 575                         goto out;
 576         }
 577
 578         ret = nlm_lck_blocked;
 579
 580         /* Append to list of blocked */
 581         nlmsvc_insert_block(block, NLM_NEVER);
 582 out:
 583         mutex_unlock(&file->f_mutex);
 584         nlmsvc_release_block(block);
 585         dprintk("lockd: nlmsvc_lock returned %u\n", ret);
 586         return ret;
 587 }
 588
 589 /*
 590  * Test for presence of a conflicting lock.
 591  */
 592 __be32
 593 nlmsvc_testlock(struct svc_rqst *rqstp, struct nlm_file *file,
 594                 struct nlm_host *host, struct nlm_lock *lock,
 595                 struct nlm_lock *conflock, struct nlm_cookie *cookie)
 596 {
 597         int                     error;
 598         __be32                  ret;
 599         struct nlm_lockowner    *test_owner;
 600
 601         dprintk("lockd: nlmsvc_testlock(%s/%ld, ty=%d, %Ld-%Ld)\n",
 602                                 locks_inode(file->f_file)->i_sb->s_id,
 603                                 locks_inode(file->f_file)->i_ino,
 604                                 lock->fl.fl_type,
 605                                 (long long)lock->fl.fl_start,
 606                                 (long long)lock->fl.fl_end);
 607
 608         if (locks_in_grace(SVC_NET(rqstp))) {
 609                 ret = nlm_lck_denied_grace_period;
 610                 goto out;
 611         }
 612
 613         /* If there's a conflicting lock, remember to clean up the test lock */
 614         test_owner = (struct nlm_lockowner *)lock->fl.fl_owner;
 615
 616         error = vfs_test_lock(file->f_file, &lock->fl);
 617         if (error) {
 618                 /* We can't currently deal with deferred test requests */
 619                 if (error == FILE_LOCK_DEFERRED)
 620                         WARN_ON_ONCE(1);
 621
 622                 ret = nlm_lck_denied_nolocks;
 623                 goto out;
 624         }
 625
 626         if (lock->fl.fl_type == F_UNLCK) {
 627                 ret = nlm_granted;
 628                 goto out;
 629         }
 630
 631         dprintk("lockd: conflicting lock(ty=%d, %Ld-%Ld)\n",
 632                 lock->fl.fl_type, (long long)lock->fl.fl_start,
 633                 (long long)lock->fl.fl_end);
 634         conflock->caller = "somehost";  /* FIXME */
 635         conflock->len = strlen(conflock->caller);
 636         conflock->oh.len = 0;           /* don't return OH info */
 637         conflock->svid = ((struct nlm_lockowner *)lock->fl.fl_owner)->pid;
 638         conflock->fl.fl_type = lock->fl.fl_type;
 639         conflock->fl.fl_start = lock->fl.fl_start;
 640         conflock->fl.fl_end = lock->fl.fl_end;
 641         locks_release_private(&lock->fl);
 642
 643         /* Clean up the test lock */
 644         lock->fl.fl_owner = NULL;
 645         nlmsvc_put_lockowner(test_owner);
 646
 647         ret = nlm_lck_denied;
 648 out:
 649         return ret;
 650 }
 651
 652 /*
 653  * Remove a lock.
 654  * This implies a CANCEL call: We send a GRANT_MSG, the client replies
 655  * with a GRANT_RES call which gets lost, and calls UNLOCK immediately
 656  * afterwards. In this case the block will still be there, and hence
 657  * must be removed.
 658  */
 659 __be32
 660 nlmsvc_unlock(struct net *net, struct nlm_file *file, struct nlm_lock *lock)
 661 {
 662         int     error;
 663
 664         dprintk("lockd: nlmsvc_unlock(%s/%ld, pi=%d, %Ld-%Ld)\n",
 665                                 locks_inode(file->f_file)->i_sb->s_id,
 666                                 locks_inode(file->f_file)->i_ino,
 667                                 lock->fl.fl_pid,
 668                                 (long long)lock->fl.fl_start,
 669                                 (long long)lock->fl.fl_end);
 670
 671         /* First, cancel any lock that might be there */
 672         nlmsvc_cancel_blocked(net, file, lock);
 673
 674         lock->fl.fl_type = F_UNLCK;
 675         error = vfs_lock_file(file->f_file, F_SETLK, &lock->fl, NULL);
 676
 677         return (error < 0)? nlm_lck_denied_nolocks : nlm_granted;
 678 }
 679
 680 /*
 681  * Cancel a previously blocked request.
 682  *
 683  * A cancel request always overrides any grant that may currently
 684  * be in progress.
 685  * The calling procedure must check whether the file can be closed.
 686  */
 687 __be32
 688 nlmsvc_cancel_blocked(struct net *net, struct nlm_file *file, struct nlm_lock *lock)
 689 {
 690         struct nlm_block        *block;
 691         int status = 0;
 692
 693         dprintk("lockd: nlmsvc_cancel(%s/%ld, pi=%d, %Ld-%Ld)\n",
 694                                 locks_inode(file->f_file)->i_sb->s_id,
 695                                 locks_inode(file->f_file)->i_ino,
 696                                 lock->fl.fl_pid,
 697                                 (long long)lock->fl.fl_start,
 698                                 (long long)lock->fl.fl_end);
 699
 700         if (locks_in_grace(net))
 701                 return nlm_lck_denied_grace_period;
 702
 703         mutex_lock(&file->f_mutex);
 704         block = nlmsvc_lookup_block(file, lock);
 705         mutex_unlock(&file->f_mutex);
 706         if (block != NULL) {
 707                 vfs_cancel_lock(block->b_file->f_file,
 708                                 &block->b_call->a_args.lock.fl);
 709                 status = nlmsvc_unlink_block(block);
 710                 nlmsvc_release_block(block);
 711         }
 712         return status ? nlm_lck_denied : nlm_granted;
 713 }
 714
 715 /*
 716  * This is a callback from the filesystem for VFS file lock requests.
 717  * It will be used if lm_grant is defined and the filesystem can not
 718  * respond to the request immediately.
 719  * For SETLK or SETLKW request it will get the local posix lock.
 720  * In all cases it will move the block to the head of nlm_blocked q where
 721  * nlmsvc_retry_blocked() can send back a reply for SETLKW or revisit the
 722  * deferred rpc for GETLK and SETLK.
 723  */
 724 static void
 725 nlmsvc_update_deferred_block(struct nlm_block *block, int result)
 726 {
 727         block->b_flags |= B_GOT_CALLBACK;
 728         if (result == 0)
 729                 block->b_granted = 1;
 730         else
 731                 block->b_flags |= B_TIMED_OUT;
 732 }
 733
 734 static int nlmsvc_grant_deferred(struct file_lock *fl, int result)
 735 {
 736         struct nlm_block *block;
 737         int rc = -ENOENT;
 738
 739         spin_lock(&nlm_blocked_lock);
 740         list_for_each_entry(block, &nlm_blocked, b_list) {
 741                 if (nlm_compare_locks(&block->b_call->a_args.lock.fl, fl)) {
 742                         dprintk("lockd: nlmsvc_notify_blocked block %p flags %d\n",
 743                                                         block, block->b_flags);
 744                         if (block->b_flags & B_QUEUED) {
 745                                 if (block->b_flags & B_TIMED_OUT) {
 746                                         rc = -ENOLCK;
 747                                         break;
 748                                 }
 749                                 nlmsvc_update_deferred_block(block, result);
 750                         } else if (result == 0)
 751                                 block->b_granted = 1;
 752
 753                         nlmsvc_insert_block_locked(block, 0);
 754                         svc_wake_up(block->b_daemon);
 755                         rc = 0;
 756                         break;
 757                 }
 758         }
 759         spin_unlock(&nlm_blocked_lock);
 760         if (rc == -ENOENT)
 761                 printk(KERN_WARNING "lockd: grant for unknown block\n");
 762         return rc;
 763 }
 764
 765 /*
 766  * Unblock a blocked lock request. This is a callback invoked from the
 767  * VFS layer when a lock on which we blocked is removed.
 768  *
 769  * This function doesn't grant the blocked lock instantly, but rather moves
 770  * the block to the head of nlm_blocked where it can be picked up by lockd.
 771  */
 772 static void
 773 nlmsvc_notify_blocked(struct file_lock *fl)
 774 {
 775         struct nlm_block        *block;
 776
 777         dprintk("lockd: VFS unblock notification for block %p\n", fl);
 778         spin_lock(&nlm_blocked_lock);
 779         list_for_each_entry(block, &nlm_blocked, b_list) {
 780                 if (nlm_compare_locks(&block->b_call->a_args.lock.fl, fl)) {
 781                         nlmsvc_insert_block_locked(block, 0);
 782                         spin_unlock(&nlm_blocked_lock);
 783                         svc_wake_up(block->b_daemon);
 784                         return;
 785                 }
 786         }
 787         spin_unlock(&nlm_blocked_lock);
 788         printk(KERN_WARNING "lockd: notification for unknown block!\n");
 789 }
 790
 791 const struct lock_manager_operations nlmsvc_lock_operations = {
 792         .lm_notify = nlmsvc_notify_blocked,
 793         .lm_grant = nlmsvc_grant_deferred,
 794 };
 795
 796 /*
 797  * Try to claim a lock that was previously blocked.
 798  *
 799  * Note that we use both the RPC_GRANTED_MSG call _and_ an async
 800  * RPC thread when notifying the client. This seems like overkill...
 801  * Here's why:
 802  *  -   we don't want to use a synchronous RPC thread, otherwise
 803  *      we might find ourselves hanging on a dead portmapper.
 804  *  -   Some lockd implementations (e.g. HP) don't react to
 805  *      RPC_GRANTED calls; they seem to insist on RPC_GRANTED_MSG calls.
 806  */
 807 static void
 808 nlmsvc_grant_blocked(struct nlm_block *block)
 809 {
 810         struct nlm_file         *file = block->b_file;
 811         struct nlm_lock         *lock = &block->b_call->a_args.lock;
 812         int                     error;
 813         loff_t                  fl_start, fl_end;
 814
 815         dprintk("lockd: grant blocked lock %p\n", block);
 816
 817         kref_get(&block->b_count);
 818
 819         /* Unlink block request from list */
 820         nlmsvc_unlink_block(block);
 821
 822         /* If b_granted is true this means we've been here before.
 823          * Just retry the grant callback, possibly refreshing the RPC
 824          * binding */
 825         if (block->b_granted) {
 826                 nlm_rebind_host(block->b_host);
 827                 goto callback;
 828         }
 829
 830         /* Try the lock operation again */
 831         /* vfs_lock_file() can mangle fl_start and fl_end, but we need
 832          * them unchanged for the GRANT_MSG
 833          */
 834         lock->fl.fl_flags |= FL_SLEEP;
 835         fl_start = lock->fl.fl_start;
 836         fl_end = lock->fl.fl_end;
 837         error = vfs_lock_file(file->f_file, F_SETLK, &lock->fl, NULL);
 838         lock->fl.fl_flags &= ~FL_SLEEP;
 839         lock->fl.fl_start = fl_start;
 840         lock->fl.fl_end = fl_end;
 841
 842         switch (error) {
 843         case 0:
 844                 break;
 845         case FILE_LOCK_DEFERRED:
 846                 dprintk("lockd: lock still blocked error %d\n", error);
 847                 nlmsvc_insert_block(block, NLM_NEVER);
 848                 nlmsvc_release_block(block);
 849                 return;
 850         default:
 851                 printk(KERN_WARNING "lockd: unexpected error %d in %s!\n",
 852                                 -error, __func__);
 853                 nlmsvc_insert_block(block, 10 * HZ);
 854                 nlmsvc_release_block(block);
 855                 return;
 856         }
 857
 858 callback:
 859         /* Lock was granted by VFS. */
 860         dprintk("lockd: GRANTing blocked lock.\n");
 861         block->b_granted = 1;
 862
 863         /* keep block on the list, but don't reattempt until the RPC
 864          * completes or the submission fails
 865          */
 866         nlmsvc_insert_block(block, NLM_NEVER);
 867
 868         /* Call the client -- use a soft RPC task since nlmsvc_retry_blocked
 869          * will queue up a new one if this one times out
 870          */
 871         error = nlm_async_call(block->b_call, NLMPROC_GRANTED_MSG,
 872                                 &nlmsvc_grant_ops);
 873
 874         /* RPC submission failed, wait a bit and retry */
 875         if (error < 0)
 876                 nlmsvc_insert_block(block, 10 * HZ);
 877 }
 878
 879 /*
 880  * This is the callback from the RPC layer when the NLM_GRANTED_MSG
 881  * RPC call has succeeded or timed out.
 882  * Like all RPC callbacks, it is invoked by the rpciod process, so it
 883  * better not sleep. Therefore, we put the blocked lock on the nlm_blocked
 884  * chain once more in order to have it removed by lockd itself (which can
 885  * then sleep on the file semaphore without disrupting e.g. the nfs client).
 886  */
 887 static void nlmsvc_grant_callback(struct rpc_task *task, void *data)
 888 {
 889         struct nlm_rqst         *call = data;
 890         struct nlm_block        *block = call->a_block;
 891         unsigned long           timeout;
 892
 893         dprintk("lockd: GRANT_MSG RPC callback\n");
 894
 895         spin_lock(&nlm_blocked_lock);
 896         /* if the block is not on a list at this point then it has
 897          * been invalidated. Don't try to requeue it.
 898          *
 899          * FIXME: it's possible that the block is removed from the list
 900          * after this check but before the nlmsvc_insert_block. In that
 901          * case it will be added back. Perhaps we need better locking
 902          * for nlm_blocked?
 903          */
 904         if (list_empty(&block->b_list))
 905                 goto out;
 906
 907         /* Technically, we should down the file semaphore here. Since we
 908          * move the block towards the head of the queue only, no harm
 909          * can be done, though. */
 910         if (task->tk_status < 0) {
 911                 /* RPC error: Re-insert for retransmission */
 912                 timeout = 10 * HZ;
 913         } else {
 914                 /* Call was successful, now wait for client callback */
 915                 timeout = 60 * HZ;
 916         }
 917         nlmsvc_insert_block_locked(block, timeout);
 918         svc_wake_up(block->b_daemon);
 919 out:
 920         spin_unlock(&nlm_blocked_lock);
 921 }
 922
 923 /*
 924  * FIXME: nlmsvc_release_block() grabs a mutex.  This is not allowed for an
 925  * .rpc_release rpc_call_op
 926  */
 927 static void nlmsvc_grant_release(void *data)
 928 {
 929         struct nlm_rqst         *call = data;
 930         nlmsvc_release_block(call->a_block);
 931 }
 932
 933 static const struct rpc_call_ops nlmsvc_grant_ops = {
 934         .rpc_call_done = nlmsvc_grant_callback,
 935         .rpc_release = nlmsvc_grant_release,
 936 };
 937
 938 /*
 939  * We received a GRANT_RES callback. Try to find the corresponding
 940  * block.
 941  */
 942 void
 943 nlmsvc_grant_reply(struct nlm_cookie *cookie, __be32 status)
 944 {
 945         struct nlm_block        *block;
 946
 947         dprintk("grant_reply: looking for cookie %x, s=%d \n",
 948                 *(unsigned int *)(cookie->data), status);
 949         if (!(block = nlmsvc_find_block(cookie)))
 950                 return;
 951
 952         if (status == nlm_lck_denied_grace_period) {
 953                 /* Try again in a couple of seconds */
 954                 nlmsvc_insert_block(block, 10 * HZ);
 955         } else {
 956                 /*
 957                  * Lock is now held by client, or has been rejected.
 958                  * In both cases, the block should be removed.
 959                  */
 960                 nlmsvc_unlink_block(block);
 961         }
 962         nlmsvc_release_block(block);
 963 }
 964
 965 /* Helper function to handle retry of a deferred block.
 966  * If it is a blocking lock, call grant_blocked.
 967  * For a non-blocking lock or test lock, revisit the request.
 968  */
 969 static void
 970 retry_deferred_block(struct nlm_block *block)
 971 {
 972         if (!(block->b_flags & B_GOT_CALLBACK))
 973                 block->b_flags |= B_TIMED_OUT;
 974         nlmsvc_insert_block(block, NLM_TIMEOUT);
 975         dprintk("revisit block %p flags %d\n",  block, block->b_flags);
 976         if (block->b_deferred_req) {
 977                 block->b_deferred_req->revisit(block->b_deferred_req, 0);
 978                 block->b_deferred_req = NULL;
 979         }
 980 }
 981
 982 /*
 983  * Retry all blocked locks that have been notified. This is where lockd
 984  * picks up locks that can be granted, or grant notifications that must
 985  * be retransmitted.
 986  */
 987 unsigned long
 988 nlmsvc_retry_blocked(void)
 989 {
 990         unsigned long   timeout = MAX_SCHEDULE_TIMEOUT;
 991         struct nlm_block *block;
 992
 993         spin_lock(&nlm_blocked_lock);
 994         while (!list_empty(&nlm_blocked) && !kthread_should_stop()) {
 995                 block = list_entry(nlm_blocked.next, struct nlm_block, b_list);
 996
 997                 if (block->b_when == NLM_NEVER)
 998                         break;
 999                 if (time_after(block->b_when, jiffies)) {
1000                         timeout = block->b_when - jiffies;
1001                         break;
1002                 }
1003                 spin_unlock(&nlm_blocked_lock);
1004
1005                 dprintk("nlmsvc_retry_blocked(%p, when=%ld)\n",
1006                         block, block->b_when);
1007                 if (block->b_flags & B_QUEUED) {
1008                         dprintk("nlmsvc_retry_blocked delete block (%p, granted=%d, flags=%d)\n",
1009                                 block, block->b_granted, block->b_flags);
1010                         retry_deferred_block(block);
1011                 } else
1012                         nlmsvc_grant_blocked(block);
1013                 spin_lock(&nlm_blocked_lock);
1014         }
1015         spin_unlock(&nlm_blocked_lock);
1016
1017         return timeout;
1018 }