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