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 void nlmsvc_locks_init_private(struct file_lock *fl, struct nlm_host *host, 399 pid_t pid) 400 { 401 fl->fl_owner = nlmsvc_find_lockowner(host, pid); 402 } 403 404 /* 405 * Initialize arguments for GRANTED call. The nlm_rqst structure 406 * has been cleared already. 407 */ 408 static int nlmsvc_setgrantargs(struct nlm_rqst *call, struct nlm_lock *lock) 409 { 410 locks_copy_lock(&call->a_args.lock.fl, &lock->fl); 411 memcpy(&call->a_args.lock.fh, &lock->fh, sizeof(call->a_args.lock.fh)); 412 call->a_args.lock.caller = utsname()->nodename; 413 call->a_args.lock.oh.len = lock->oh.len; 414 415 /* set default data area */ 416 call->a_args.lock.oh.data = call->a_owner; 417 call->a_args.lock.svid = ((struct nlm_lockowner *)lock->fl.fl_owner)->pid; 418 419 if (lock->oh.len > NLMCLNT_OHSIZE) { 420 void *data = kmalloc(lock->oh.len, GFP_KERNEL); 421 if (!data) 422 return 0; 423 call->a_args.lock.oh.data = (u8 *) data; 424 } 425 426 memcpy(call->a_args.lock.oh.data, lock->oh.data, lock->oh.len); 427 return 1; 428 } 429 430 static void nlmsvc_freegrantargs(struct nlm_rqst *call) 431 { 432 if (call->a_args.lock.oh.data != call->a_owner) 433 kfree(call->a_args.lock.oh.data); 434 435 locks_release_private(&call->a_args.lock.fl); 436 } 437 438 /* 439 * Deferred lock request handling for non-blocking lock 440 */ 441 static __be32 442 nlmsvc_defer_lock_rqst(struct svc_rqst *rqstp, struct nlm_block *block) 443 { 444 __be32 status = nlm_lck_denied_nolocks; 445 446 block->b_flags |= B_QUEUED; 447 448 nlmsvc_insert_block(block, NLM_TIMEOUT); 449 450 block->b_cache_req = &rqstp->rq_chandle; 451 if (rqstp->rq_chandle.defer) { 452 block->b_deferred_req = 453 rqstp->rq_chandle.defer(block->b_cache_req); 454 if (block->b_deferred_req != NULL) 455 status = nlm_drop_reply; 456 } 457 dprintk("lockd: nlmsvc_defer_lock_rqst block %p flags %d status %d\n", 458 block, block->b_flags, ntohl(status)); 459 460 return status; 461 } 462 463 /* 464 * Attempt to establish a lock, and if it can't be granted, block it 465 * if required. 466 */ 467 __be32 468 nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file, 469 struct nlm_host *host, struct nlm_lock *lock, int wait, 470 struct nlm_cookie *cookie, int reclaim) 471 { 472 struct nlm_block *block = NULL; 473 int error; 474 int mode; 475 __be32 ret; 476 477 dprintk("lockd: nlmsvc_lock(%s/%ld, ty=%d, pi=%d, %Ld-%Ld, bl=%d)\n", 478 nlmsvc_file_inode(file)->i_sb->s_id, 479 nlmsvc_file_inode(file)->i_ino, 480 lock->fl.fl_type, lock->fl.fl_pid, 481 (long long)lock->fl.fl_start, 482 (long long)lock->fl.fl_end, 483 wait); 484 485 /* Lock file against concurrent access */ 486 mutex_lock(&file->f_mutex); 487 /* Get existing block (in case client is busy-waiting) 488 * or create new block 489 */ 490 block = nlmsvc_lookup_block(file, lock); 491 if (block == NULL) { 492 block = nlmsvc_create_block(rqstp, host, file, lock, cookie); 493 ret = nlm_lck_denied_nolocks; 494 if (block == NULL) 495 goto out; 496 lock = &block->b_call->a_args.lock; 497 } else 498 lock->fl.fl_flags &= ~FL_SLEEP; 499 500 if (block->b_flags & B_QUEUED) { 501 dprintk("lockd: nlmsvc_lock deferred block %p flags %d\n", 502 block, block->b_flags); 503 if (block->b_granted) { 504 nlmsvc_unlink_block(block); 505 ret = nlm_granted; 506 goto out; 507 } 508 if (block->b_flags & B_TIMED_OUT) { 509 nlmsvc_unlink_block(block); 510 ret = nlm_lck_denied; 511 goto out; 512 } 513 ret = nlm_drop_reply; 514 goto out; 515 } 516 517 if (locks_in_grace(SVC_NET(rqstp)) && !reclaim) { 518 ret = nlm_lck_denied_grace_period; 519 goto out; 520 } 521 if (reclaim && !locks_in_grace(SVC_NET(rqstp))) { 522 ret = nlm_lck_denied_grace_period; 523 goto out; 524 } 525 526 if (!wait) 527 lock->fl.fl_flags &= ~FL_SLEEP; 528 mode = lock_to_openmode(&lock->fl); 529 error = vfs_lock_file(file->f_file[mode], F_SETLK, &lock->fl, NULL); 530 lock->fl.fl_flags &= ~FL_SLEEP; 531 532 dprintk("lockd: vfs_lock_file returned %d\n", error); 533 switch (error) { 534 case 0: 535 ret = nlm_granted; 536 goto out; 537 case -EAGAIN: 538 /* 539 * If this is a blocking request for an 540 * already pending lock request then we need 541 * to put it back on lockd's block list 542 */ 543 if (wait) 544 break; 545 ret = nlm_lck_denied; 546 goto out; 547 case FILE_LOCK_DEFERRED: 548 if (wait) 549 break; 550 /* Filesystem lock operation is in progress 551 Add it to the queue waiting for callback */ 552 ret = nlmsvc_defer_lock_rqst(rqstp, block); 553 goto out; 554 case -EDEADLK: 555 ret = nlm_deadlock; 556 goto out; 557 default: /* includes ENOLCK */ 558 ret = nlm_lck_denied_nolocks; 559 goto out; 560 } 561 562 ret = nlm_lck_blocked; 563 564 /* Append to list of blocked */ 565 nlmsvc_insert_block(block, NLM_NEVER); 566 out: 567 mutex_unlock(&file->f_mutex); 568 nlmsvc_release_block(block); 569 dprintk("lockd: nlmsvc_lock returned %u\n", ret); 570 return ret; 571 } 572 573 /* 574 * Test for presence of a conflicting lock. 575 */ 576 __be32 577 nlmsvc_testlock(struct svc_rqst *rqstp, struct nlm_file *file, 578 struct nlm_host *host, struct nlm_lock *lock, 579 struct nlm_lock *conflock, struct nlm_cookie *cookie) 580 { 581 int error; 582 int mode; 583 __be32 ret; 584 struct nlm_lockowner *test_owner; 585 586 dprintk("lockd: nlmsvc_testlock(%s/%ld, ty=%d, %Ld-%Ld)\n", 587 nlmsvc_file_inode(file)->i_sb->s_id, 588 nlmsvc_file_inode(file)->i_ino, 589 lock->fl.fl_type, 590 (long long)lock->fl.fl_start, 591 (long long)lock->fl.fl_end); 592 593 if (locks_in_grace(SVC_NET(rqstp))) { 594 ret = nlm_lck_denied_grace_period; 595 goto out; 596 } 597 598 /* If there's a conflicting lock, remember to clean up the test lock */ 599 test_owner = (struct nlm_lockowner *)lock->fl.fl_owner; 600 601 mode = lock_to_openmode(&lock->fl); 602 error = vfs_test_lock(file->f_file[mode], &lock->fl); 603 if (error) { 604 /* We can't currently deal with deferred test requests */ 605 if (error == FILE_LOCK_DEFERRED) 606 WARN_ON_ONCE(1); 607 608 ret = nlm_lck_denied_nolocks; 609 goto out; 610 } 611 612 if (lock->fl.fl_type == F_UNLCK) { 613 ret = nlm_granted; 614 goto out; 615 } 616 617 dprintk("lockd: conflicting lock(ty=%d, %Ld-%Ld)\n", 618 lock->fl.fl_type, (long long)lock->fl.fl_start, 619 (long long)lock->fl.fl_end); 620 conflock->caller = "somehost"; /* FIXME */ 621 conflock->len = strlen(conflock->caller); 622 conflock->oh.len = 0; /* don't return OH info */ 623 conflock->svid = lock->fl.fl_pid; 624 conflock->fl.fl_type = lock->fl.fl_type; 625 conflock->fl.fl_start = lock->fl.fl_start; 626 conflock->fl.fl_end = lock->fl.fl_end; 627 locks_release_private(&lock->fl); 628 629 /* Clean up the test lock */ 630 lock->fl.fl_owner = NULL; 631 nlmsvc_put_lockowner(test_owner); 632 633 ret = nlm_lck_denied; 634 out: 635 return ret; 636 } 637 638 /* 639 * Remove a lock. 640 * This implies a CANCEL call: We send a GRANT_MSG, the client replies 641 * with a GRANT_RES call which gets lost, and calls UNLOCK immediately 642 * afterwards. In this case the block will still be there, and hence 643 * must be removed. 644 */ 645 __be32 646 nlmsvc_unlock(struct net *net, struct nlm_file *file, struct nlm_lock *lock) 647 { 648 int error = 0; 649 650 dprintk("lockd: nlmsvc_unlock(%s/%ld, pi=%d, %Ld-%Ld)\n", 651 nlmsvc_file_inode(file)->i_sb->s_id, 652 nlmsvc_file_inode(file)->i_ino, 653 lock->fl.fl_pid, 654 (long long)lock->fl.fl_start, 655 (long long)lock->fl.fl_end); 656 657 /* First, cancel any lock that might be there */ 658 nlmsvc_cancel_blocked(net, file, lock); 659 660 lock->fl.fl_type = F_UNLCK; 661 if (file->f_file[O_RDONLY]) 662 error = vfs_lock_file(file->f_file[O_RDONLY], F_SETLK, 663 &lock->fl, NULL); 664 if (file->f_file[O_WRONLY]) 665 error = vfs_lock_file(file->f_file[O_WRONLY], F_SETLK, 666 &lock->fl, NULL); 667 668 return (error < 0)? nlm_lck_denied_nolocks : nlm_granted; 669 } 670 671 /* 672 * Cancel a previously blocked request. 673 * 674 * A cancel request always overrides any grant that may currently 675 * be in progress. 676 * The calling procedure must check whether the file can be closed. 677 */ 678 __be32 679 nlmsvc_cancel_blocked(struct net *net, struct nlm_file *file, struct nlm_lock *lock) 680 { 681 struct nlm_block *block; 682 int status = 0; 683 int mode; 684 685 dprintk("lockd: nlmsvc_cancel(%s/%ld, pi=%d, %Ld-%Ld)\n", 686 nlmsvc_file_inode(file)->i_sb->s_id, 687 nlmsvc_file_inode(file)->i_ino, 688 lock->fl.fl_pid, 689 (long long)lock->fl.fl_start, 690 (long long)lock->fl.fl_end); 691 692 if (locks_in_grace(net)) 693 return nlm_lck_denied_grace_period; 694 695 mutex_lock(&file->f_mutex); 696 block = nlmsvc_lookup_block(file, lock); 697 mutex_unlock(&file->f_mutex); 698 if (block != NULL) { 699 mode = lock_to_openmode(&lock->fl); 700 vfs_cancel_lock(block->b_file->f_file[mode], 701 &block->b_call->a_args.lock.fl); 702 status = nlmsvc_unlink_block(block); 703 nlmsvc_release_block(block); 704 } 705 return status ? nlm_lck_denied : nlm_granted; 706 } 707 708 /* 709 * This is a callback from the filesystem for VFS file lock requests. 710 * It will be used if lm_grant is defined and the filesystem can not 711 * respond to the request immediately. 712 * For SETLK or SETLKW request it will get the local posix lock. 713 * In all cases it will move the block to the head of nlm_blocked q where 714 * nlmsvc_retry_blocked() can send back a reply for SETLKW or revisit the 715 * deferred rpc for GETLK and SETLK. 716 */ 717 static void 718 nlmsvc_update_deferred_block(struct nlm_block *block, int result) 719 { 720 block->b_flags |= B_GOT_CALLBACK; 721 if (result == 0) 722 block->b_granted = 1; 723 else 724 block->b_flags |= B_TIMED_OUT; 725 } 726 727 static int nlmsvc_grant_deferred(struct file_lock *fl, int result) 728 { 729 struct nlm_block *block; 730 int rc = -ENOENT; 731 732 spin_lock(&nlm_blocked_lock); 733 list_for_each_entry(block, &nlm_blocked, b_list) { 734 if (nlm_compare_locks(&block->b_call->a_args.lock.fl, fl)) { 735 dprintk("lockd: nlmsvc_notify_blocked block %p flags %d\n", 736 block, block->b_flags); 737 if (block->b_flags & B_QUEUED) { 738 if (block->b_flags & B_TIMED_OUT) { 739 rc = -ENOLCK; 740 break; 741 } 742 nlmsvc_update_deferred_block(block, result); 743 } else if (result == 0) 744 block->b_granted = 1; 745 746 nlmsvc_insert_block_locked(block, 0); 747 svc_wake_up(block->b_daemon); 748 rc = 0; 749 break; 750 } 751 } 752 spin_unlock(&nlm_blocked_lock); 753 if (rc == -ENOENT) 754 printk(KERN_WARNING "lockd: grant for unknown block\n"); 755 return rc; 756 } 757 758 /* 759 * Unblock a blocked lock request. This is a callback invoked from the 760 * VFS layer when a lock on which we blocked is removed. 761 * 762 * This function doesn't grant the blocked lock instantly, but rather moves 763 * the block to the head of nlm_blocked where it can be picked up by lockd. 764 */ 765 static void 766 nlmsvc_notify_blocked(struct file_lock *fl) 767 { 768 struct nlm_block *block; 769 770 dprintk("lockd: VFS unblock notification for block %p\n", fl); 771 spin_lock(&nlm_blocked_lock); 772 list_for_each_entry(block, &nlm_blocked, b_list) { 773 if (nlm_compare_locks(&block->b_call->a_args.lock.fl, fl)) { 774 nlmsvc_insert_block_locked(block, 0); 775 spin_unlock(&nlm_blocked_lock); 776 svc_wake_up(block->b_daemon); 777 return; 778 } 779 } 780 spin_unlock(&nlm_blocked_lock); 781 printk(KERN_WARNING "lockd: notification for unknown block!\n"); 782 } 783 784 static fl_owner_t nlmsvc_get_owner(fl_owner_t owner) 785 { 786 return nlmsvc_get_lockowner(owner); 787 } 788 789 static void nlmsvc_put_owner(fl_owner_t owner) 790 { 791 nlmsvc_put_lockowner(owner); 792 } 793 794 const struct lock_manager_operations nlmsvc_lock_operations = { 795 .lm_notify = nlmsvc_notify_blocked, 796 .lm_grant = nlmsvc_grant_deferred, 797 .lm_get_owner = nlmsvc_get_owner, 798 .lm_put_owner = nlmsvc_put_owner, 799 }; 800 801 /* 802 * Try to claim a lock that was previously blocked. 803 * 804 * Note that we use both the RPC_GRANTED_MSG call _and_ an async 805 * RPC thread when notifying the client. This seems like overkill... 806 * Here's why: 807 * - we don't want to use a synchronous RPC thread, otherwise 808 * we might find ourselves hanging on a dead portmapper. 809 * - Some lockd implementations (e.g. HP) don't react to 810 * RPC_GRANTED calls; they seem to insist on RPC_GRANTED_MSG calls. 811 */ 812 static void 813 nlmsvc_grant_blocked(struct nlm_block *block) 814 { 815 struct nlm_file *file = block->b_file; 816 struct nlm_lock *lock = &block->b_call->a_args.lock; 817 int mode; 818 int error; 819 loff_t fl_start, fl_end; 820 821 dprintk("lockd: grant blocked lock %p\n", block); 822 823 kref_get(&block->b_count); 824 825 /* Unlink block request from list */ 826 nlmsvc_unlink_block(block); 827 828 /* If b_granted is true this means we've been here before. 829 * Just retry the grant callback, possibly refreshing the RPC 830 * binding */ 831 if (block->b_granted) { 832 nlm_rebind_host(block->b_host); 833 goto callback; 834 } 835 836 /* Try the lock operation again */ 837 /* vfs_lock_file() can mangle fl_start and fl_end, but we need 838 * them unchanged for the GRANT_MSG 839 */ 840 lock->fl.fl_flags |= FL_SLEEP; 841 fl_start = lock->fl.fl_start; 842 fl_end = lock->fl.fl_end; 843 mode = lock_to_openmode(&lock->fl); 844 error = vfs_lock_file(file->f_file[mode], F_SETLK, &lock->fl, NULL); 845 lock->fl.fl_flags &= ~FL_SLEEP; 846 lock->fl.fl_start = fl_start; 847 lock->fl.fl_end = fl_end; 848 849 switch (error) { 850 case 0: 851 break; 852 case FILE_LOCK_DEFERRED: 853 dprintk("lockd: lock still blocked error %d\n", error); 854 nlmsvc_insert_block(block, NLM_NEVER); 855 nlmsvc_release_block(block); 856 return; 857 default: 858 printk(KERN_WARNING "lockd: unexpected error %d in %s!\n", 859 -error, __func__); 860 nlmsvc_insert_block(block, 10 * HZ); 861 nlmsvc_release_block(block); 862 return; 863 } 864 865 callback: 866 /* Lock was granted by VFS. */ 867 dprintk("lockd: GRANTing blocked lock.\n"); 868 block->b_granted = 1; 869 870 /* keep block on the list, but don't reattempt until the RPC 871 * completes or the submission fails 872 */ 873 nlmsvc_insert_block(block, NLM_NEVER); 874 875 /* Call the client -- use a soft RPC task since nlmsvc_retry_blocked 876 * will queue up a new one if this one times out 877 */ 878 error = nlm_async_call(block->b_call, NLMPROC_GRANTED_MSG, 879 &nlmsvc_grant_ops); 880 881 /* RPC submission failed, wait a bit and retry */ 882 if (error < 0) 883 nlmsvc_insert_block(block, 10 * HZ); 884 } 885 886 /* 887 * This is the callback from the RPC layer when the NLM_GRANTED_MSG 888 * RPC call has succeeded or timed out. 889 * Like all RPC callbacks, it is invoked by the rpciod process, so it 890 * better not sleep. Therefore, we put the blocked lock on the nlm_blocked 891 * chain once more in order to have it removed by lockd itself (which can 892 * then sleep on the file semaphore without disrupting e.g. the nfs client). 893 */ 894 static void nlmsvc_grant_callback(struct rpc_task *task, void *data) 895 { 896 struct nlm_rqst *call = data; 897 struct nlm_block *block = call->a_block; 898 unsigned long timeout; 899 900 dprintk("lockd: GRANT_MSG RPC callback\n"); 901 902 spin_lock(&nlm_blocked_lock); 903 /* if the block is not on a list at this point then it has 904 * been invalidated. Don't try to requeue it. 905 * 906 * FIXME: it's possible that the block is removed from the list 907 * after this check but before the nlmsvc_insert_block. In that 908 * case it will be added back. Perhaps we need better locking 909 * for nlm_blocked? 910 */ 911 if (list_empty(&block->b_list)) 912 goto out; 913 914 /* Technically, we should down the file semaphore here. Since we 915 * move the block towards the head of the queue only, no harm 916 * can be done, though. */ 917 if (task->tk_status < 0) { 918 /* RPC error: Re-insert for retransmission */ 919 timeout = 10 * HZ; 920 } else { 921 /* Call was successful, now wait for client callback */ 922 timeout = 60 * HZ; 923 } 924 nlmsvc_insert_block_locked(block, timeout); 925 svc_wake_up(block->b_daemon); 926 out: 927 spin_unlock(&nlm_blocked_lock); 928 } 929 930 /* 931 * FIXME: nlmsvc_release_block() grabs a mutex. This is not allowed for an 932 * .rpc_release rpc_call_op 933 */ 934 static void nlmsvc_grant_release(void *data) 935 { 936 struct nlm_rqst *call = data; 937 nlmsvc_release_block(call->a_block); 938 } 939 940 static const struct rpc_call_ops nlmsvc_grant_ops = { 941 .rpc_call_done = nlmsvc_grant_callback, 942 .rpc_release = nlmsvc_grant_release, 943 }; 944 945 /* 946 * We received a GRANT_RES callback. Try to find the corresponding 947 * block. 948 */ 949 void 950 nlmsvc_grant_reply(struct nlm_cookie *cookie, __be32 status) 951 { 952 struct nlm_block *block; 953 954 dprintk("grant_reply: looking for cookie %x, s=%d \n", 955 *(unsigned int *)(cookie->data), status); 956 if (!(block = nlmsvc_find_block(cookie))) 957 return; 958 959 if (status == nlm_lck_denied_grace_period) { 960 /* Try again in a couple of seconds */ 961 nlmsvc_insert_block(block, 10 * HZ); 962 } else { 963 /* 964 * Lock is now held by client, or has been rejected. 965 * In both cases, the block should be removed. 966 */ 967 nlmsvc_unlink_block(block); 968 } 969 nlmsvc_release_block(block); 970 } 971 972 /* Helper function to handle retry of a deferred block. 973 * If it is a blocking lock, call grant_blocked. 974 * For a non-blocking lock or test lock, revisit the request. 975 */ 976 static void 977 retry_deferred_block(struct nlm_block *block) 978 { 979 if (!(block->b_flags & B_GOT_CALLBACK)) 980 block->b_flags |= B_TIMED_OUT; 981 nlmsvc_insert_block(block, NLM_TIMEOUT); 982 dprintk("revisit block %p flags %d\n", block, block->b_flags); 983 if (block->b_deferred_req) { 984 block->b_deferred_req->revisit(block->b_deferred_req, 0); 985 block->b_deferred_req = NULL; 986 } 987 } 988 989 /* 990 * Retry all blocked locks that have been notified. This is where lockd 991 * picks up locks that can be granted, or grant notifications that must 992 * be retransmitted. 993 */ 994 unsigned long 995 nlmsvc_retry_blocked(void) 996 { 997 unsigned long timeout = MAX_SCHEDULE_TIMEOUT; 998 struct nlm_block *block; 999 1000 spin_lock(&nlm_blocked_lock); 1001 while (!list_empty(&nlm_blocked) && !kthread_should_stop()) { 1002 block = list_entry(nlm_blocked.next, struct nlm_block, b_list); 1003 1004 if (block->b_when == NLM_NEVER) 1005 break; 1006 if (time_after(block->b_when, jiffies)) { 1007 timeout = block->b_when - jiffies; 1008 break; 1009 } 1010 spin_unlock(&nlm_blocked_lock); 1011 1012 dprintk("nlmsvc_retry_blocked(%p, when=%ld)\n", 1013 block, block->b_when); 1014 if (block->b_flags & B_QUEUED) { 1015 dprintk("nlmsvc_retry_blocked delete block (%p, granted=%d, flags=%d)\n", 1016 block, block->b_granted, block->b_flags); 1017 retry_deferred_block(block); 1018 } else 1019 nlmsvc_grant_blocked(block); 1020 spin_lock(&nlm_blocked_lock); 1021 } 1022 spin_unlock(&nlm_blocked_lock); 1023 1024 return timeout; 1025 } 1026