1 /* 2 * linux/fs/locks.c 3 * 4 * Provide support for fcntl()'s F_GETLK, F_SETLK, and F_SETLKW calls. 5 * Doug Evans (dje@spiff.uucp), August 07, 1992 6 * 7 * Deadlock detection added. 8 * FIXME: one thing isn't handled yet: 9 * - mandatory locks (requires lots of changes elsewhere) 10 * Kelly Carmichael (kelly@[142.24.8.65]), September 17, 1994. 11 * 12 * Miscellaneous edits, and a total rewrite of posix_lock_file() code. 13 * Kai Petzke (wpp@marie.physik.tu-berlin.de), 1994 14 * 15 * Converted file_lock_table to a linked list from an array, which eliminates 16 * the limits on how many active file locks are open. 17 * Chad Page (pageone@netcom.com), November 27, 1994 18 * 19 * Removed dependency on file descriptors. dup()'ed file descriptors now 20 * get the same locks as the original file descriptors, and a close() on 21 * any file descriptor removes ALL the locks on the file for the current 22 * process. Since locks still depend on the process id, locks are inherited 23 * after an exec() but not after a fork(). This agrees with POSIX, and both 24 * BSD and SVR4 practice. 25 * Andy Walker (andy@lysaker.kvaerner.no), February 14, 1995 26 * 27 * Scrapped free list which is redundant now that we allocate locks 28 * dynamically with kmalloc()/kfree(). 29 * Andy Walker (andy@lysaker.kvaerner.no), February 21, 1995 30 * 31 * Implemented two lock personalities - FL_FLOCK and FL_POSIX. 32 * 33 * FL_POSIX locks are created with calls to fcntl() and lockf() through the 34 * fcntl() system call. They have the semantics described above. 35 * 36 * FL_FLOCK locks are created with calls to flock(), through the flock() 37 * system call, which is new. Old C libraries implement flock() via fcntl() 38 * and will continue to use the old, broken implementation. 39 * 40 * FL_FLOCK locks follow the 4.4 BSD flock() semantics. They are associated 41 * with a file pointer (filp). As a result they can be shared by a parent 42 * process and its children after a fork(). They are removed when the last 43 * file descriptor referring to the file pointer is closed (unless explicitly 44 * unlocked). 45 * 46 * FL_FLOCK locks never deadlock, an existing lock is always removed before 47 * upgrading from shared to exclusive (or vice versa). When this happens 48 * any processes blocked by the current lock are woken up and allowed to 49 * run before the new lock is applied. 50 * Andy Walker (andy@lysaker.kvaerner.no), June 09, 1995 51 * 52 * Removed some race conditions in flock_lock_file(), marked other possible 53 * races. Just grep for FIXME to see them. 54 * Dmitry Gorodchanin (pgmdsg@ibi.com), February 09, 1996. 55 * 56 * Addressed Dmitry's concerns. Deadlock checking no longer recursive. 57 * Lock allocation changed to GFP_ATOMIC as we can't afford to sleep 58 * once we've checked for blocking and deadlocking. 59 * Andy Walker (andy@lysaker.kvaerner.no), April 03, 1996. 60 * 61 * Initial implementation of mandatory locks. SunOS turned out to be 62 * a rotten model, so I implemented the "obvious" semantics. 63 * See 'Documentation/mandatory.txt' for details. 64 * Andy Walker (andy@lysaker.kvaerner.no), April 06, 1996. 65 * 66 * Don't allow mandatory locks on mmap()'ed files. Added simple functions to 67 * check if a file has mandatory locks, used by mmap(), open() and creat() to 68 * see if system call should be rejected. Ref. HP-UX/SunOS/Solaris Reference 69 * Manual, Section 2. 70 * Andy Walker (andy@lysaker.kvaerner.no), April 09, 1996. 71 * 72 * Tidied up block list handling. Added '/proc/locks' interface. 73 * Andy Walker (andy@lysaker.kvaerner.no), April 24, 1996. 74 * 75 * Fixed deadlock condition for pathological code that mixes calls to 76 * flock() and fcntl(). 77 * Andy Walker (andy@lysaker.kvaerner.no), April 29, 1996. 78 * 79 * Allow only one type of locking scheme (FL_POSIX or FL_FLOCK) to be in use 80 * for a given file at a time. Changed the CONFIG_LOCK_MANDATORY scheme to 81 * guarantee sensible behaviour in the case where file system modules might 82 * be compiled with different options than the kernel itself. 83 * Andy Walker (andy@lysaker.kvaerner.no), May 15, 1996. 84 * 85 * Added a couple of missing wake_up() calls. Thanks to Thomas Meckel 86 * (Thomas.Meckel@mni.fh-giessen.de) for spotting this. 87 * Andy Walker (andy@lysaker.kvaerner.no), May 15, 1996. 88 * 89 * Changed FL_POSIX locks to use the block list in the same way as FL_FLOCK 90 * locks. Changed process synchronisation to avoid dereferencing locks that 91 * have already been freed. 92 * Andy Walker (andy@lysaker.kvaerner.no), Sep 21, 1996. 93 * 94 * Made the block list a circular list to minimise searching in the list. 95 * Andy Walker (andy@lysaker.kvaerner.no), Sep 25, 1996. 96 * 97 * Made mandatory locking a mount option. Default is not to allow mandatory 98 * locking. 99 * Andy Walker (andy@lysaker.kvaerner.no), Oct 04, 1996. 100 * 101 * Some adaptations for NFS support. 102 * Olaf Kirch (okir@monad.swb.de), Dec 1996, 103 * 104 * Fixed /proc/locks interface so that we can't overrun the buffer we are handed. 105 * Andy Walker (andy@lysaker.kvaerner.no), May 12, 1997. 106 * 107 * Use slab allocator instead of kmalloc/kfree. 108 * Use generic list implementation from <linux/list.h>. 109 * Sped up posix_locks_deadlock by only considering blocked locks. 110 * Matthew Wilcox <willy@debian.org>, March, 2000. 111 * 112 * Leases and LOCK_MAND 113 * Matthew Wilcox <willy@debian.org>, June, 2000. 114 * Stephen Rothwell <sfr@canb.auug.org.au>, June, 2000. 115 */ 116 117 #include <linux/capability.h> 118 #include <linux/file.h> 119 #include <linux/fs.h> 120 #include <linux/init.h> 121 #include <linux/module.h> 122 #include <linux/security.h> 123 #include <linux/slab.h> 124 #include <linux/smp_lock.h> 125 #include <linux/syscalls.h> 126 #include <linux/time.h> 127 #include <linux/rcupdate.h> 128 129 #include <asm/semaphore.h> 130 #include <asm/uaccess.h> 131 132 #define IS_POSIX(fl) (fl->fl_flags & FL_POSIX) 133 #define IS_FLOCK(fl) (fl->fl_flags & FL_FLOCK) 134 #define IS_LEASE(fl) (fl->fl_flags & FL_LEASE) 135 136 int leases_enable = 1; 137 int lease_break_time = 45; 138 139 #define for_each_lock(inode, lockp) \ 140 for (lockp = &inode->i_flock; *lockp != NULL; lockp = &(*lockp)->fl_next) 141 142 static LIST_HEAD(file_lock_list); 143 static LIST_HEAD(blocked_list); 144 145 static struct kmem_cache *filelock_cache __read_mostly; 146 147 /* Allocate an empty lock structure. */ 148 static struct file_lock *locks_alloc_lock(void) 149 { 150 return kmem_cache_alloc(filelock_cache, GFP_KERNEL); 151 } 152 153 static void locks_release_private(struct file_lock *fl) 154 { 155 if (fl->fl_ops) { 156 if (fl->fl_ops->fl_release_private) 157 fl->fl_ops->fl_release_private(fl); 158 fl->fl_ops = NULL; 159 } 160 if (fl->fl_lmops) { 161 if (fl->fl_lmops->fl_release_private) 162 fl->fl_lmops->fl_release_private(fl); 163 fl->fl_lmops = NULL; 164 } 165 166 } 167 168 /* Free a lock which is not in use. */ 169 static void locks_free_lock(struct file_lock *fl) 170 { 171 BUG_ON(waitqueue_active(&fl->fl_wait)); 172 BUG_ON(!list_empty(&fl->fl_block)); 173 BUG_ON(!list_empty(&fl->fl_link)); 174 175 locks_release_private(fl); 176 kmem_cache_free(filelock_cache, fl); 177 } 178 179 void locks_init_lock(struct file_lock *fl) 180 { 181 INIT_LIST_HEAD(&fl->fl_link); 182 INIT_LIST_HEAD(&fl->fl_block); 183 init_waitqueue_head(&fl->fl_wait); 184 fl->fl_next = NULL; 185 fl->fl_fasync = NULL; 186 fl->fl_owner = NULL; 187 fl->fl_pid = 0; 188 fl->fl_file = NULL; 189 fl->fl_flags = 0; 190 fl->fl_type = 0; 191 fl->fl_start = fl->fl_end = 0; 192 fl->fl_ops = NULL; 193 fl->fl_lmops = NULL; 194 } 195 196 EXPORT_SYMBOL(locks_init_lock); 197 198 /* 199 * Initialises the fields of the file lock which are invariant for 200 * free file_locks. 201 */ 202 static void init_once(struct kmem_cache *cache, void *foo) 203 { 204 struct file_lock *lock = (struct file_lock *) foo; 205 206 locks_init_lock(lock); 207 } 208 209 static void locks_copy_private(struct file_lock *new, struct file_lock *fl) 210 { 211 if (fl->fl_ops) { 212 if (fl->fl_ops->fl_copy_lock) 213 fl->fl_ops->fl_copy_lock(new, fl); 214 new->fl_ops = fl->fl_ops; 215 } 216 if (fl->fl_lmops) { 217 if (fl->fl_lmops->fl_copy_lock) 218 fl->fl_lmops->fl_copy_lock(new, fl); 219 new->fl_lmops = fl->fl_lmops; 220 } 221 } 222 223 /* 224 * Initialize a new lock from an existing file_lock structure. 225 */ 226 static void __locks_copy_lock(struct file_lock *new, const struct file_lock *fl) 227 { 228 new->fl_owner = fl->fl_owner; 229 new->fl_pid = fl->fl_pid; 230 new->fl_file = NULL; 231 new->fl_flags = fl->fl_flags; 232 new->fl_type = fl->fl_type; 233 new->fl_start = fl->fl_start; 234 new->fl_end = fl->fl_end; 235 new->fl_ops = NULL; 236 new->fl_lmops = NULL; 237 } 238 239 void locks_copy_lock(struct file_lock *new, struct file_lock *fl) 240 { 241 locks_release_private(new); 242 243 __locks_copy_lock(new, fl); 244 new->fl_file = fl->fl_file; 245 new->fl_ops = fl->fl_ops; 246 new->fl_lmops = fl->fl_lmops; 247 248 locks_copy_private(new, fl); 249 } 250 251 EXPORT_SYMBOL(locks_copy_lock); 252 253 static inline int flock_translate_cmd(int cmd) { 254 if (cmd & LOCK_MAND) 255 return cmd & (LOCK_MAND | LOCK_RW); 256 switch (cmd) { 257 case LOCK_SH: 258 return F_RDLCK; 259 case LOCK_EX: 260 return F_WRLCK; 261 case LOCK_UN: 262 return F_UNLCK; 263 } 264 return -EINVAL; 265 } 266 267 /* Fill in a file_lock structure with an appropriate FLOCK lock. */ 268 static int flock_make_lock(struct file *filp, struct file_lock **lock, 269 unsigned int cmd) 270 { 271 struct file_lock *fl; 272 int type = flock_translate_cmd(cmd); 273 if (type < 0) 274 return type; 275 276 fl = locks_alloc_lock(); 277 if (fl == NULL) 278 return -ENOMEM; 279 280 fl->fl_file = filp; 281 fl->fl_pid = current->tgid; 282 fl->fl_flags = FL_FLOCK; 283 fl->fl_type = type; 284 fl->fl_end = OFFSET_MAX; 285 286 *lock = fl; 287 return 0; 288 } 289 290 static int assign_type(struct file_lock *fl, int type) 291 { 292 switch (type) { 293 case F_RDLCK: 294 case F_WRLCK: 295 case F_UNLCK: 296 fl->fl_type = type; 297 break; 298 default: 299 return -EINVAL; 300 } 301 return 0; 302 } 303 304 /* Verify a "struct flock" and copy it to a "struct file_lock" as a POSIX 305 * style lock. 306 */ 307 static int flock_to_posix_lock(struct file *filp, struct file_lock *fl, 308 struct flock *l) 309 { 310 off_t start, end; 311 312 switch (l->l_whence) { 313 case SEEK_SET: 314 start = 0; 315 break; 316 case SEEK_CUR: 317 start = filp->f_pos; 318 break; 319 case SEEK_END: 320 start = i_size_read(filp->f_path.dentry->d_inode); 321 break; 322 default: 323 return -EINVAL; 324 } 325 326 /* POSIX-1996 leaves the case l->l_len < 0 undefined; 327 POSIX-2001 defines it. */ 328 start += l->l_start; 329 if (start < 0) 330 return -EINVAL; 331 fl->fl_end = OFFSET_MAX; 332 if (l->l_len > 0) { 333 end = start + l->l_len - 1; 334 fl->fl_end = end; 335 } else if (l->l_len < 0) { 336 end = start - 1; 337 fl->fl_end = end; 338 start += l->l_len; 339 if (start < 0) 340 return -EINVAL; 341 } 342 fl->fl_start = start; /* we record the absolute position */ 343 if (fl->fl_end < fl->fl_start) 344 return -EOVERFLOW; 345 346 fl->fl_owner = current->files; 347 fl->fl_pid = current->tgid; 348 fl->fl_file = filp; 349 fl->fl_flags = FL_POSIX; 350 fl->fl_ops = NULL; 351 fl->fl_lmops = NULL; 352 353 return assign_type(fl, l->l_type); 354 } 355 356 #if BITS_PER_LONG == 32 357 static int flock64_to_posix_lock(struct file *filp, struct file_lock *fl, 358 struct flock64 *l) 359 { 360 loff_t start; 361 362 switch (l->l_whence) { 363 case SEEK_SET: 364 start = 0; 365 break; 366 case SEEK_CUR: 367 start = filp->f_pos; 368 break; 369 case SEEK_END: 370 start = i_size_read(filp->f_path.dentry->d_inode); 371 break; 372 default: 373 return -EINVAL; 374 } 375 376 start += l->l_start; 377 if (start < 0) 378 return -EINVAL; 379 fl->fl_end = OFFSET_MAX; 380 if (l->l_len > 0) { 381 fl->fl_end = start + l->l_len - 1; 382 } else if (l->l_len < 0) { 383 fl->fl_end = start - 1; 384 start += l->l_len; 385 if (start < 0) 386 return -EINVAL; 387 } 388 fl->fl_start = start; /* we record the absolute position */ 389 if (fl->fl_end < fl->fl_start) 390 return -EOVERFLOW; 391 392 fl->fl_owner = current->files; 393 fl->fl_pid = current->tgid; 394 fl->fl_file = filp; 395 fl->fl_flags = FL_POSIX; 396 fl->fl_ops = NULL; 397 fl->fl_lmops = NULL; 398 399 switch (l->l_type) { 400 case F_RDLCK: 401 case F_WRLCK: 402 case F_UNLCK: 403 fl->fl_type = l->l_type; 404 break; 405 default: 406 return -EINVAL; 407 } 408 409 return (0); 410 } 411 #endif 412 413 /* default lease lock manager operations */ 414 static void lease_break_callback(struct file_lock *fl) 415 { 416 kill_fasync(&fl->fl_fasync, SIGIO, POLL_MSG); 417 } 418 419 static void lease_release_private_callback(struct file_lock *fl) 420 { 421 if (!fl->fl_file) 422 return; 423 424 f_delown(fl->fl_file); 425 fl->fl_file->f_owner.signum = 0; 426 } 427 428 static int lease_mylease_callback(struct file_lock *fl, struct file_lock *try) 429 { 430 return fl->fl_file == try->fl_file; 431 } 432 433 static struct lock_manager_operations lease_manager_ops = { 434 .fl_break = lease_break_callback, 435 .fl_release_private = lease_release_private_callback, 436 .fl_mylease = lease_mylease_callback, 437 .fl_change = lease_modify, 438 }; 439 440 /* 441 * Initialize a lease, use the default lock manager operations 442 */ 443 static int lease_init(struct file *filp, int type, struct file_lock *fl) 444 { 445 if (assign_type(fl, type) != 0) 446 return -EINVAL; 447 448 fl->fl_owner = current->files; 449 fl->fl_pid = current->tgid; 450 451 fl->fl_file = filp; 452 fl->fl_flags = FL_LEASE; 453 fl->fl_start = 0; 454 fl->fl_end = OFFSET_MAX; 455 fl->fl_ops = NULL; 456 fl->fl_lmops = &lease_manager_ops; 457 return 0; 458 } 459 460 /* Allocate a file_lock initialised to this type of lease */ 461 static struct file_lock *lease_alloc(struct file *filp, int type) 462 { 463 struct file_lock *fl = locks_alloc_lock(); 464 int error = -ENOMEM; 465 466 if (fl == NULL) 467 return ERR_PTR(error); 468 469 error = lease_init(filp, type, fl); 470 if (error) { 471 locks_free_lock(fl); 472 return ERR_PTR(error); 473 } 474 return fl; 475 } 476 477 /* Check if two locks overlap each other. 478 */ 479 static inline int locks_overlap(struct file_lock *fl1, struct file_lock *fl2) 480 { 481 return ((fl1->fl_end >= fl2->fl_start) && 482 (fl2->fl_end >= fl1->fl_start)); 483 } 484 485 /* 486 * Check whether two locks have the same owner. 487 */ 488 static int posix_same_owner(struct file_lock *fl1, struct file_lock *fl2) 489 { 490 if (fl1->fl_lmops && fl1->fl_lmops->fl_compare_owner) 491 return fl2->fl_lmops == fl1->fl_lmops && 492 fl1->fl_lmops->fl_compare_owner(fl1, fl2); 493 return fl1->fl_owner == fl2->fl_owner; 494 } 495 496 /* Remove waiter from blocker's block list. 497 * When blocker ends up pointing to itself then the list is empty. 498 */ 499 static void __locks_delete_block(struct file_lock *waiter) 500 { 501 list_del_init(&waiter->fl_block); 502 list_del_init(&waiter->fl_link); 503 waiter->fl_next = NULL; 504 } 505 506 /* 507 */ 508 static void locks_delete_block(struct file_lock *waiter) 509 { 510 lock_kernel(); 511 __locks_delete_block(waiter); 512 unlock_kernel(); 513 } 514 515 /* Insert waiter into blocker's block list. 516 * We use a circular list so that processes can be easily woken up in 517 * the order they blocked. The documentation doesn't require this but 518 * it seems like the reasonable thing to do. 519 */ 520 static void locks_insert_block(struct file_lock *blocker, 521 struct file_lock *waiter) 522 { 523 BUG_ON(!list_empty(&waiter->fl_block)); 524 list_add_tail(&waiter->fl_block, &blocker->fl_block); 525 waiter->fl_next = blocker; 526 if (IS_POSIX(blocker)) 527 list_add(&waiter->fl_link, &blocked_list); 528 } 529 530 /* Wake up processes blocked waiting for blocker. 531 * If told to wait then schedule the processes until the block list 532 * is empty, otherwise empty the block list ourselves. 533 */ 534 static void locks_wake_up_blocks(struct file_lock *blocker) 535 { 536 while (!list_empty(&blocker->fl_block)) { 537 struct file_lock *waiter; 538 539 waiter = list_first_entry(&blocker->fl_block, 540 struct file_lock, fl_block); 541 __locks_delete_block(waiter); 542 if (waiter->fl_lmops && waiter->fl_lmops->fl_notify) 543 waiter->fl_lmops->fl_notify(waiter); 544 else 545 wake_up(&waiter->fl_wait); 546 } 547 } 548 549 /* Insert file lock fl into an inode's lock list at the position indicated 550 * by pos. At the same time add the lock to the global file lock list. 551 */ 552 static void locks_insert_lock(struct file_lock **pos, struct file_lock *fl) 553 { 554 list_add(&fl->fl_link, &file_lock_list); 555 556 /* insert into file's list */ 557 fl->fl_next = *pos; 558 *pos = fl; 559 560 if (fl->fl_ops && fl->fl_ops->fl_insert) 561 fl->fl_ops->fl_insert(fl); 562 } 563 564 /* 565 * Delete a lock and then free it. 566 * Wake up processes that are blocked waiting for this lock, 567 * notify the FS that the lock has been cleared and 568 * finally free the lock. 569 */ 570 static void locks_delete_lock(struct file_lock **thisfl_p) 571 { 572 struct file_lock *fl = *thisfl_p; 573 574 *thisfl_p = fl->fl_next; 575 fl->fl_next = NULL; 576 list_del_init(&fl->fl_link); 577 578 fasync_helper(0, fl->fl_file, 0, &fl->fl_fasync); 579 if (fl->fl_fasync != NULL) { 580 printk(KERN_ERR "locks_delete_lock: fasync == %p\n", fl->fl_fasync); 581 fl->fl_fasync = NULL; 582 } 583 584 if (fl->fl_ops && fl->fl_ops->fl_remove) 585 fl->fl_ops->fl_remove(fl); 586 587 locks_wake_up_blocks(fl); 588 locks_free_lock(fl); 589 } 590 591 /* Determine if lock sys_fl blocks lock caller_fl. Common functionality 592 * checks for shared/exclusive status of overlapping locks. 593 */ 594 static int locks_conflict(struct file_lock *caller_fl, struct file_lock *sys_fl) 595 { 596 if (sys_fl->fl_type == F_WRLCK) 597 return 1; 598 if (caller_fl->fl_type == F_WRLCK) 599 return 1; 600 return 0; 601 } 602 603 /* Determine if lock sys_fl blocks lock caller_fl. POSIX specific 604 * checking before calling the locks_conflict(). 605 */ 606 static int posix_locks_conflict(struct file_lock *caller_fl, struct file_lock *sys_fl) 607 { 608 /* POSIX locks owned by the same process do not conflict with 609 * each other. 610 */ 611 if (!IS_POSIX(sys_fl) || posix_same_owner(caller_fl, sys_fl)) 612 return (0); 613 614 /* Check whether they overlap */ 615 if (!locks_overlap(caller_fl, sys_fl)) 616 return 0; 617 618 return (locks_conflict(caller_fl, sys_fl)); 619 } 620 621 /* Determine if lock sys_fl blocks lock caller_fl. FLOCK specific 622 * checking before calling the locks_conflict(). 623 */ 624 static int flock_locks_conflict(struct file_lock *caller_fl, struct file_lock *sys_fl) 625 { 626 /* FLOCK locks referring to the same filp do not conflict with 627 * each other. 628 */ 629 if (!IS_FLOCK(sys_fl) || (caller_fl->fl_file == sys_fl->fl_file)) 630 return (0); 631 if ((caller_fl->fl_type & LOCK_MAND) || (sys_fl->fl_type & LOCK_MAND)) 632 return 0; 633 634 return (locks_conflict(caller_fl, sys_fl)); 635 } 636 637 static int interruptible_sleep_on_locked(wait_queue_head_t *fl_wait, int timeout) 638 { 639 int result = 0; 640 DECLARE_WAITQUEUE(wait, current); 641 642 __set_current_state(TASK_INTERRUPTIBLE); 643 add_wait_queue(fl_wait, &wait); 644 if (timeout == 0) 645 schedule(); 646 else 647 result = schedule_timeout(timeout); 648 if (signal_pending(current)) 649 result = -ERESTARTSYS; 650 remove_wait_queue(fl_wait, &wait); 651 __set_current_state(TASK_RUNNING); 652 return result; 653 } 654 655 static int locks_block_on_timeout(struct file_lock *blocker, struct file_lock *waiter, int time) 656 { 657 int result; 658 locks_insert_block(blocker, waiter); 659 result = interruptible_sleep_on_locked(&waiter->fl_wait, time); 660 __locks_delete_block(waiter); 661 return result; 662 } 663 664 void 665 posix_test_lock(struct file *filp, struct file_lock *fl) 666 { 667 struct file_lock *cfl; 668 669 lock_kernel(); 670 for (cfl = filp->f_path.dentry->d_inode->i_flock; cfl; cfl = cfl->fl_next) { 671 if (!IS_POSIX(cfl)) 672 continue; 673 if (posix_locks_conflict(fl, cfl)) 674 break; 675 } 676 if (cfl) 677 __locks_copy_lock(fl, cfl); 678 else 679 fl->fl_type = F_UNLCK; 680 unlock_kernel(); 681 return; 682 } 683 684 EXPORT_SYMBOL(posix_test_lock); 685 686 /* This function tests for deadlock condition before putting a process to 687 * sleep. The detection scheme is no longer recursive. Recursive was neat, 688 * but dangerous - we risked stack corruption if the lock data was bad, or 689 * if the recursion was too deep for any other reason. 690 * 691 * We rely on the fact that a task can only be on one lock's wait queue 692 * at a time. When we find blocked_task on a wait queue we can re-search 693 * with blocked_task equal to that queue's owner, until either blocked_task 694 * isn't found, or blocked_task is found on a queue owned by my_task. 695 * 696 * Note: the above assumption may not be true when handling lock requests 697 * from a broken NFS client. But broken NFS clients have a lot more to 698 * worry about than proper deadlock detection anyway... --okir 699 * 700 * However, the failure of this assumption (also possible in the case of 701 * multiple tasks sharing the same open file table) also means there's no 702 * guarantee that the loop below will terminate. As a hack, we give up 703 * after a few iterations. 704 */ 705 706 #define MAX_DEADLK_ITERATIONS 10 707 708 static int posix_locks_deadlock(struct file_lock *caller_fl, 709 struct file_lock *block_fl) 710 { 711 struct file_lock *fl; 712 int i = 0; 713 714 next_task: 715 if (posix_same_owner(caller_fl, block_fl)) 716 return 1; 717 list_for_each_entry(fl, &blocked_list, fl_link) { 718 if (posix_same_owner(fl, block_fl)) { 719 if (i++ > MAX_DEADLK_ITERATIONS) 720 return 0; 721 fl = fl->fl_next; 722 block_fl = fl; 723 goto next_task; 724 } 725 } 726 return 0; 727 } 728 729 /* Try to create a FLOCK lock on filp. We always insert new FLOCK locks 730 * after any leases, but before any posix locks. 731 * 732 * Note that if called with an FL_EXISTS argument, the caller may determine 733 * whether or not a lock was successfully freed by testing the return 734 * value for -ENOENT. 735 */ 736 static int flock_lock_file(struct file *filp, struct file_lock *request) 737 { 738 struct file_lock *new_fl = NULL; 739 struct file_lock **before; 740 struct inode * inode = filp->f_path.dentry->d_inode; 741 int error = 0; 742 int found = 0; 743 744 lock_kernel(); 745 if (request->fl_flags & FL_ACCESS) 746 goto find_conflict; 747 748 if (request->fl_type != F_UNLCK) { 749 error = -ENOMEM; 750 new_fl = locks_alloc_lock(); 751 if (new_fl == NULL) 752 goto out; 753 error = 0; 754 } 755 756 for_each_lock(inode, before) { 757 struct file_lock *fl = *before; 758 if (IS_POSIX(fl)) 759 break; 760 if (IS_LEASE(fl)) 761 continue; 762 if (filp != fl->fl_file) 763 continue; 764 if (request->fl_type == fl->fl_type) 765 goto out; 766 found = 1; 767 locks_delete_lock(before); 768 break; 769 } 770 771 if (request->fl_type == F_UNLCK) { 772 if ((request->fl_flags & FL_EXISTS) && !found) 773 error = -ENOENT; 774 goto out; 775 } 776 777 /* 778 * If a higher-priority process was blocked on the old file lock, 779 * give it the opportunity to lock the file. 780 */ 781 if (found) 782 cond_resched(); 783 784 find_conflict: 785 for_each_lock(inode, before) { 786 struct file_lock *fl = *before; 787 if (IS_POSIX(fl)) 788 break; 789 if (IS_LEASE(fl)) 790 continue; 791 if (!flock_locks_conflict(request, fl)) 792 continue; 793 error = -EAGAIN; 794 if (request->fl_flags & FL_SLEEP) 795 locks_insert_block(fl, request); 796 goto out; 797 } 798 if (request->fl_flags & FL_ACCESS) 799 goto out; 800 locks_copy_lock(new_fl, request); 801 locks_insert_lock(before, new_fl); 802 new_fl = NULL; 803 error = 0; 804 805 out: 806 unlock_kernel(); 807 if (new_fl) 808 locks_free_lock(new_fl); 809 return error; 810 } 811 812 static int __posix_lock_file(struct inode *inode, struct file_lock *request, struct file_lock *conflock) 813 { 814 struct file_lock *fl; 815 struct file_lock *new_fl = NULL; 816 struct file_lock *new_fl2 = NULL; 817 struct file_lock *left = NULL; 818 struct file_lock *right = NULL; 819 struct file_lock **before; 820 int error, added = 0; 821 822 /* 823 * We may need two file_lock structures for this operation, 824 * so we get them in advance to avoid races. 825 * 826 * In some cases we can be sure, that no new locks will be needed 827 */ 828 if (!(request->fl_flags & FL_ACCESS) && 829 (request->fl_type != F_UNLCK || 830 request->fl_start != 0 || request->fl_end != OFFSET_MAX)) { 831 new_fl = locks_alloc_lock(); 832 new_fl2 = locks_alloc_lock(); 833 } 834 835 lock_kernel(); 836 if (request->fl_type != F_UNLCK) { 837 for_each_lock(inode, before) { 838 fl = *before; 839 if (!IS_POSIX(fl)) 840 continue; 841 if (!posix_locks_conflict(request, fl)) 842 continue; 843 if (conflock) 844 locks_copy_lock(conflock, fl); 845 error = -EAGAIN; 846 if (!(request->fl_flags & FL_SLEEP)) 847 goto out; 848 error = -EDEADLK; 849 if (posix_locks_deadlock(request, fl)) 850 goto out; 851 error = -EAGAIN; 852 locks_insert_block(fl, request); 853 goto out; 854 } 855 } 856 857 /* If we're just looking for a conflict, we're done. */ 858 error = 0; 859 if (request->fl_flags & FL_ACCESS) 860 goto out; 861 862 /* 863 * Find the first old lock with the same owner as the new lock. 864 */ 865 866 before = &inode->i_flock; 867 868 /* First skip locks owned by other processes. */ 869 while ((fl = *before) && (!IS_POSIX(fl) || 870 !posix_same_owner(request, fl))) { 871 before = &fl->fl_next; 872 } 873 874 /* Process locks with this owner. */ 875 while ((fl = *before) && posix_same_owner(request, fl)) { 876 /* Detect adjacent or overlapping regions (if same lock type) 877 */ 878 if (request->fl_type == fl->fl_type) { 879 /* In all comparisons of start vs end, use 880 * "start - 1" rather than "end + 1". If end 881 * is OFFSET_MAX, end + 1 will become negative. 882 */ 883 if (fl->fl_end < request->fl_start - 1) 884 goto next_lock; 885 /* If the next lock in the list has entirely bigger 886 * addresses than the new one, insert the lock here. 887 */ 888 if (fl->fl_start - 1 > request->fl_end) 889 break; 890 891 /* If we come here, the new and old lock are of the 892 * same type and adjacent or overlapping. Make one 893 * lock yielding from the lower start address of both 894 * locks to the higher end address. 895 */ 896 if (fl->fl_start > request->fl_start) 897 fl->fl_start = request->fl_start; 898 else 899 request->fl_start = fl->fl_start; 900 if (fl->fl_end < request->fl_end) 901 fl->fl_end = request->fl_end; 902 else 903 request->fl_end = fl->fl_end; 904 if (added) { 905 locks_delete_lock(before); 906 continue; 907 } 908 request = fl; 909 added = 1; 910 } 911 else { 912 /* Processing for different lock types is a bit 913 * more complex. 914 */ 915 if (fl->fl_end < request->fl_start) 916 goto next_lock; 917 if (fl->fl_start > request->fl_end) 918 break; 919 if (request->fl_type == F_UNLCK) 920 added = 1; 921 if (fl->fl_start < request->fl_start) 922 left = fl; 923 /* If the next lock in the list has a higher end 924 * address than the new one, insert the new one here. 925 */ 926 if (fl->fl_end > request->fl_end) { 927 right = fl; 928 break; 929 } 930 if (fl->fl_start >= request->fl_start) { 931 /* The new lock completely replaces an old 932 * one (This may happen several times). 933 */ 934 if (added) { 935 locks_delete_lock(before); 936 continue; 937 } 938 /* Replace the old lock with the new one. 939 * Wake up anybody waiting for the old one, 940 * as the change in lock type might satisfy 941 * their needs. 942 */ 943 locks_wake_up_blocks(fl); 944 fl->fl_start = request->fl_start; 945 fl->fl_end = request->fl_end; 946 fl->fl_type = request->fl_type; 947 locks_release_private(fl); 948 locks_copy_private(fl, request); 949 request = fl; 950 added = 1; 951 } 952 } 953 /* Go on to next lock. 954 */ 955 next_lock: 956 before = &fl->fl_next; 957 } 958 959 /* 960 * The above code only modifies existing locks in case of 961 * merging or replacing. If new lock(s) need to be inserted 962 * all modifications are done bellow this, so it's safe yet to 963 * bail out. 964 */ 965 error = -ENOLCK; /* "no luck" */ 966 if (right && left == right && !new_fl2) 967 goto out; 968 969 error = 0; 970 if (!added) { 971 if (request->fl_type == F_UNLCK) { 972 if (request->fl_flags & FL_EXISTS) 973 error = -ENOENT; 974 goto out; 975 } 976 977 if (!new_fl) { 978 error = -ENOLCK; 979 goto out; 980 } 981 locks_copy_lock(new_fl, request); 982 locks_insert_lock(before, new_fl); 983 new_fl = NULL; 984 } 985 if (right) { 986 if (left == right) { 987 /* The new lock breaks the old one in two pieces, 988 * so we have to use the second new lock. 989 */ 990 left = new_fl2; 991 new_fl2 = NULL; 992 locks_copy_lock(left, right); 993 locks_insert_lock(before, left); 994 } 995 right->fl_start = request->fl_end + 1; 996 locks_wake_up_blocks(right); 997 } 998 if (left) { 999 left->fl_end = request->fl_start - 1; 1000 locks_wake_up_blocks(left); 1001 } 1002 out: 1003 unlock_kernel(); 1004 /* 1005 * Free any unused locks. 1006 */ 1007 if (new_fl) 1008 locks_free_lock(new_fl); 1009 if (new_fl2) 1010 locks_free_lock(new_fl2); 1011 return error; 1012 } 1013 1014 /** 1015 * posix_lock_file - Apply a POSIX-style lock to a file 1016 * @filp: The file to apply the lock to 1017 * @fl: The lock to be applied 1018 * @conflock: Place to return a copy of the conflicting lock, if found. 1019 * 1020 * Add a POSIX style lock to a file. 1021 * We merge adjacent & overlapping locks whenever possible. 1022 * POSIX locks are sorted by owner task, then by starting address 1023 * 1024 * Note that if called with an FL_EXISTS argument, the caller may determine 1025 * whether or not a lock was successfully freed by testing the return 1026 * value for -ENOENT. 1027 */ 1028 int posix_lock_file(struct file *filp, struct file_lock *fl, 1029 struct file_lock *conflock) 1030 { 1031 return __posix_lock_file(filp->f_path.dentry->d_inode, fl, conflock); 1032 } 1033 EXPORT_SYMBOL(posix_lock_file); 1034 1035 /** 1036 * posix_lock_file_wait - Apply a POSIX-style lock to a file 1037 * @filp: The file to apply the lock to 1038 * @fl: The lock to be applied 1039 * 1040 * Add a POSIX style lock to a file. 1041 * We merge adjacent & overlapping locks whenever possible. 1042 * POSIX locks are sorted by owner task, then by starting address 1043 */ 1044 int posix_lock_file_wait(struct file *filp, struct file_lock *fl) 1045 { 1046 int error; 1047 might_sleep (); 1048 for (;;) { 1049 error = posix_lock_file(filp, fl, NULL); 1050 if ((error != -EAGAIN) || !(fl->fl_flags & FL_SLEEP)) 1051 break; 1052 error = wait_event_interruptible(fl->fl_wait, !fl->fl_next); 1053 if (!error) 1054 continue; 1055 1056 locks_delete_block(fl); 1057 break; 1058 } 1059 return error; 1060 } 1061 EXPORT_SYMBOL(posix_lock_file_wait); 1062 1063 /** 1064 * locks_mandatory_locked - Check for an active lock 1065 * @inode: the file to check 1066 * 1067 * Searches the inode's list of locks to find any POSIX locks which conflict. 1068 * This function is called from locks_verify_locked() only. 1069 */ 1070 int locks_mandatory_locked(struct inode *inode) 1071 { 1072 fl_owner_t owner = current->files; 1073 struct file_lock *fl; 1074 1075 /* 1076 * Search the lock list for this inode for any POSIX locks. 1077 */ 1078 lock_kernel(); 1079 for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) { 1080 if (!IS_POSIX(fl)) 1081 continue; 1082 if (fl->fl_owner != owner) 1083 break; 1084 } 1085 unlock_kernel(); 1086 return fl ? -EAGAIN : 0; 1087 } 1088 1089 /** 1090 * locks_mandatory_area - Check for a conflicting lock 1091 * @read_write: %FLOCK_VERIFY_WRITE for exclusive access, %FLOCK_VERIFY_READ 1092 * for shared 1093 * @inode: the file to check 1094 * @filp: how the file was opened (if it was) 1095 * @offset: start of area to check 1096 * @count: length of area to check 1097 * 1098 * Searches the inode's list of locks to find any POSIX locks which conflict. 1099 * This function is called from rw_verify_area() and 1100 * locks_verify_truncate(). 1101 */ 1102 int locks_mandatory_area(int read_write, struct inode *inode, 1103 struct file *filp, loff_t offset, 1104 size_t count) 1105 { 1106 struct file_lock fl; 1107 int error; 1108 1109 locks_init_lock(&fl); 1110 fl.fl_owner = current->files; 1111 fl.fl_pid = current->tgid; 1112 fl.fl_file = filp; 1113 fl.fl_flags = FL_POSIX | FL_ACCESS; 1114 if (filp && !(filp->f_flags & O_NONBLOCK)) 1115 fl.fl_flags |= FL_SLEEP; 1116 fl.fl_type = (read_write == FLOCK_VERIFY_WRITE) ? F_WRLCK : F_RDLCK; 1117 fl.fl_start = offset; 1118 fl.fl_end = offset + count - 1; 1119 1120 for (;;) { 1121 error = __posix_lock_file(inode, &fl, NULL); 1122 if (error != -EAGAIN) 1123 break; 1124 if (!(fl.fl_flags & FL_SLEEP)) 1125 break; 1126 error = wait_event_interruptible(fl.fl_wait, !fl.fl_next); 1127 if (!error) { 1128 /* 1129 * If we've been sleeping someone might have 1130 * changed the permissions behind our back. 1131 */ 1132 if (__mandatory_lock(inode)) 1133 continue; 1134 } 1135 1136 locks_delete_block(&fl); 1137 break; 1138 } 1139 1140 return error; 1141 } 1142 1143 EXPORT_SYMBOL(locks_mandatory_area); 1144 1145 /* We already had a lease on this file; just change its type */ 1146 int lease_modify(struct file_lock **before, int arg) 1147 { 1148 struct file_lock *fl = *before; 1149 int error = assign_type(fl, arg); 1150 1151 if (error) 1152 return error; 1153 locks_wake_up_blocks(fl); 1154 if (arg == F_UNLCK) 1155 locks_delete_lock(before); 1156 return 0; 1157 } 1158 1159 EXPORT_SYMBOL(lease_modify); 1160 1161 static void time_out_leases(struct inode *inode) 1162 { 1163 struct file_lock **before; 1164 struct file_lock *fl; 1165 1166 before = &inode->i_flock; 1167 while ((fl = *before) && IS_LEASE(fl) && (fl->fl_type & F_INPROGRESS)) { 1168 if ((fl->fl_break_time == 0) 1169 || time_before(jiffies, fl->fl_break_time)) { 1170 before = &fl->fl_next; 1171 continue; 1172 } 1173 lease_modify(before, fl->fl_type & ~F_INPROGRESS); 1174 if (fl == *before) /* lease_modify may have freed fl */ 1175 before = &fl->fl_next; 1176 } 1177 } 1178 1179 /** 1180 * __break_lease - revoke all outstanding leases on file 1181 * @inode: the inode of the file to return 1182 * @mode: the open mode (read or write) 1183 * 1184 * break_lease (inlined for speed) has checked there already is at least 1185 * some kind of lock (maybe a lease) on this file. Leases are broken on 1186 * a call to open() or truncate(). This function can sleep unless you 1187 * specified %O_NONBLOCK to your open(). 1188 */ 1189 int __break_lease(struct inode *inode, unsigned int mode) 1190 { 1191 int error = 0, future; 1192 struct file_lock *new_fl, *flock; 1193 struct file_lock *fl; 1194 unsigned long break_time; 1195 int i_have_this_lease = 0; 1196 1197 new_fl = lease_alloc(NULL, mode & FMODE_WRITE ? F_WRLCK : F_RDLCK); 1198 1199 lock_kernel(); 1200 1201 time_out_leases(inode); 1202 1203 flock = inode->i_flock; 1204 if ((flock == NULL) || !IS_LEASE(flock)) 1205 goto out; 1206 1207 for (fl = flock; fl && IS_LEASE(fl); fl = fl->fl_next) 1208 if (fl->fl_owner == current->files) 1209 i_have_this_lease = 1; 1210 1211 if (mode & FMODE_WRITE) { 1212 /* If we want write access, we have to revoke any lease. */ 1213 future = F_UNLCK | F_INPROGRESS; 1214 } else if (flock->fl_type & F_INPROGRESS) { 1215 /* If the lease is already being broken, we just leave it */ 1216 future = flock->fl_type; 1217 } else if (flock->fl_type & F_WRLCK) { 1218 /* Downgrade the exclusive lease to a read-only lease. */ 1219 future = F_RDLCK | F_INPROGRESS; 1220 } else { 1221 /* the existing lease was read-only, so we can read too. */ 1222 goto out; 1223 } 1224 1225 if (IS_ERR(new_fl) && !i_have_this_lease 1226 && ((mode & O_NONBLOCK) == 0)) { 1227 error = PTR_ERR(new_fl); 1228 goto out; 1229 } 1230 1231 break_time = 0; 1232 if (lease_break_time > 0) { 1233 break_time = jiffies + lease_break_time * HZ; 1234 if (break_time == 0) 1235 break_time++; /* so that 0 means no break time */ 1236 } 1237 1238 for (fl = flock; fl && IS_LEASE(fl); fl = fl->fl_next) { 1239 if (fl->fl_type != future) { 1240 fl->fl_type = future; 1241 fl->fl_break_time = break_time; 1242 /* lease must have lmops break callback */ 1243 fl->fl_lmops->fl_break(fl); 1244 } 1245 } 1246 1247 if (i_have_this_lease || (mode & O_NONBLOCK)) { 1248 error = -EWOULDBLOCK; 1249 goto out; 1250 } 1251 1252 restart: 1253 break_time = flock->fl_break_time; 1254 if (break_time != 0) { 1255 break_time -= jiffies; 1256 if (break_time == 0) 1257 break_time++; 1258 } 1259 error = locks_block_on_timeout(flock, new_fl, break_time); 1260 if (error >= 0) { 1261 if (error == 0) 1262 time_out_leases(inode); 1263 /* Wait for the next lease that has not been broken yet */ 1264 for (flock = inode->i_flock; flock && IS_LEASE(flock); 1265 flock = flock->fl_next) { 1266 if (flock->fl_type & F_INPROGRESS) 1267 goto restart; 1268 } 1269 error = 0; 1270 } 1271 1272 out: 1273 unlock_kernel(); 1274 if (!IS_ERR(new_fl)) 1275 locks_free_lock(new_fl); 1276 return error; 1277 } 1278 1279 EXPORT_SYMBOL(__break_lease); 1280 1281 /** 1282 * lease_get_mtime 1283 * @inode: the inode 1284 * @time: pointer to a timespec which will contain the last modified time 1285 * 1286 * This is to force NFS clients to flush their caches for files with 1287 * exclusive leases. The justification is that if someone has an 1288 * exclusive lease, then they could be modifiying it. 1289 */ 1290 void lease_get_mtime(struct inode *inode, struct timespec *time) 1291 { 1292 struct file_lock *flock = inode->i_flock; 1293 if (flock && IS_LEASE(flock) && (flock->fl_type & F_WRLCK)) 1294 *time = current_fs_time(inode->i_sb); 1295 else 1296 *time = inode->i_mtime; 1297 } 1298 1299 EXPORT_SYMBOL(lease_get_mtime); 1300 1301 /** 1302 * fcntl_getlease - Enquire what lease is currently active 1303 * @filp: the file 1304 * 1305 * The value returned by this function will be one of 1306 * (if no lease break is pending): 1307 * 1308 * %F_RDLCK to indicate a shared lease is held. 1309 * 1310 * %F_WRLCK to indicate an exclusive lease is held. 1311 * 1312 * %F_UNLCK to indicate no lease is held. 1313 * 1314 * (if a lease break is pending): 1315 * 1316 * %F_RDLCK to indicate an exclusive lease needs to be 1317 * changed to a shared lease (or removed). 1318 * 1319 * %F_UNLCK to indicate the lease needs to be removed. 1320 * 1321 * XXX: sfr & willy disagree over whether F_INPROGRESS 1322 * should be returned to userspace. 1323 */ 1324 int fcntl_getlease(struct file *filp) 1325 { 1326 struct file_lock *fl; 1327 int type = F_UNLCK; 1328 1329 lock_kernel(); 1330 time_out_leases(filp->f_path.dentry->d_inode); 1331 for (fl = filp->f_path.dentry->d_inode->i_flock; fl && IS_LEASE(fl); 1332 fl = fl->fl_next) { 1333 if (fl->fl_file == filp) { 1334 type = fl->fl_type & ~F_INPROGRESS; 1335 break; 1336 } 1337 } 1338 unlock_kernel(); 1339 return type; 1340 } 1341 1342 /** 1343 * generic_setlease - sets a lease on an open file 1344 * @filp: file pointer 1345 * @arg: type of lease to obtain 1346 * @flp: input - file_lock to use, output - file_lock inserted 1347 * 1348 * The (input) flp->fl_lmops->fl_break function is required 1349 * by break_lease(). 1350 * 1351 * Called with kernel lock held. 1352 */ 1353 int generic_setlease(struct file *filp, long arg, struct file_lock **flp) 1354 { 1355 struct file_lock *fl, **before, **my_before = NULL, *lease; 1356 struct file_lock *new_fl = NULL; 1357 struct dentry *dentry = filp->f_path.dentry; 1358 struct inode *inode = dentry->d_inode; 1359 int error, rdlease_count = 0, wrlease_count = 0; 1360 1361 if ((current->fsuid != inode->i_uid) && !capable(CAP_LEASE)) 1362 return -EACCES; 1363 if (!S_ISREG(inode->i_mode)) 1364 return -EINVAL; 1365 error = security_file_lock(filp, arg); 1366 if (error) 1367 return error; 1368 1369 time_out_leases(inode); 1370 1371 BUG_ON(!(*flp)->fl_lmops->fl_break); 1372 1373 lease = *flp; 1374 1375 error = -EAGAIN; 1376 if ((arg == F_RDLCK) && (atomic_read(&inode->i_writecount) > 0)) 1377 goto out; 1378 if ((arg == F_WRLCK) 1379 && ((atomic_read(&dentry->d_count) > 1) 1380 || (atomic_read(&inode->i_count) > 1))) 1381 goto out; 1382 1383 error = -ENOMEM; 1384 new_fl = locks_alloc_lock(); 1385 if (new_fl == NULL) 1386 goto out; 1387 1388 /* 1389 * At this point, we know that if there is an exclusive 1390 * lease on this file, then we hold it on this filp 1391 * (otherwise our open of this file would have blocked). 1392 * And if we are trying to acquire an exclusive lease, 1393 * then the file is not open by anyone (including us) 1394 * except for this filp. 1395 */ 1396 for (before = &inode->i_flock; 1397 ((fl = *before) != NULL) && IS_LEASE(fl); 1398 before = &fl->fl_next) { 1399 if (lease->fl_lmops->fl_mylease(fl, lease)) 1400 my_before = before; 1401 else if (fl->fl_type == (F_INPROGRESS | F_UNLCK)) 1402 /* 1403 * Someone is in the process of opening this 1404 * file for writing so we may not take an 1405 * exclusive lease on it. 1406 */ 1407 wrlease_count++; 1408 else 1409 rdlease_count++; 1410 } 1411 1412 if ((arg == F_RDLCK && (wrlease_count > 0)) || 1413 (arg == F_WRLCK && ((rdlease_count + wrlease_count) > 0))) 1414 goto out; 1415 1416 if (my_before != NULL) { 1417 *flp = *my_before; 1418 error = lease->fl_lmops->fl_change(my_before, arg); 1419 goto out; 1420 } 1421 1422 error = 0; 1423 if (arg == F_UNLCK) 1424 goto out; 1425 1426 error = -EINVAL; 1427 if (!leases_enable) 1428 goto out; 1429 1430 locks_copy_lock(new_fl, lease); 1431 locks_insert_lock(before, new_fl); 1432 1433 *flp = new_fl; 1434 return 0; 1435 1436 out: 1437 if (new_fl != NULL) 1438 locks_free_lock(new_fl); 1439 return error; 1440 } 1441 EXPORT_SYMBOL(generic_setlease); 1442 1443 /** 1444 * vfs_setlease - sets a lease on an open file 1445 * @filp: file pointer 1446 * @arg: type of lease to obtain 1447 * @lease: file_lock to use 1448 * 1449 * Call this to establish a lease on the file. 1450 * The (*lease)->fl_lmops->fl_break operation must be set; if not, 1451 * break_lease will oops! 1452 * 1453 * This will call the filesystem's setlease file method, if 1454 * defined. Note that there is no getlease method; instead, the 1455 * filesystem setlease method should call back to setlease() to 1456 * add a lease to the inode's lease list, where fcntl_getlease() can 1457 * find it. Since fcntl_getlease() only reports whether the current 1458 * task holds a lease, a cluster filesystem need only do this for 1459 * leases held by processes on this node. 1460 * 1461 * There is also no break_lease method; filesystems that 1462 * handle their own leases shoud break leases themselves from the 1463 * filesystem's open, create, and (on truncate) setattr methods. 1464 * 1465 * Warning: the only current setlease methods exist only to disable 1466 * leases in certain cases. More vfs changes may be required to 1467 * allow a full filesystem lease implementation. 1468 */ 1469 1470 int vfs_setlease(struct file *filp, long arg, struct file_lock **lease) 1471 { 1472 int error; 1473 1474 lock_kernel(); 1475 if (filp->f_op && filp->f_op->setlease) 1476 error = filp->f_op->setlease(filp, arg, lease); 1477 else 1478 error = generic_setlease(filp, arg, lease); 1479 unlock_kernel(); 1480 1481 return error; 1482 } 1483 EXPORT_SYMBOL_GPL(vfs_setlease); 1484 1485 /** 1486 * fcntl_setlease - sets a lease on an open file 1487 * @fd: open file descriptor 1488 * @filp: file pointer 1489 * @arg: type of lease to obtain 1490 * 1491 * Call this fcntl to establish a lease on the file. 1492 * Note that you also need to call %F_SETSIG to 1493 * receive a signal when the lease is broken. 1494 */ 1495 int fcntl_setlease(unsigned int fd, struct file *filp, long arg) 1496 { 1497 struct file_lock fl, *flp = &fl; 1498 struct dentry *dentry = filp->f_path.dentry; 1499 struct inode *inode = dentry->d_inode; 1500 int error; 1501 1502 locks_init_lock(&fl); 1503 error = lease_init(filp, arg, &fl); 1504 if (error) 1505 return error; 1506 1507 lock_kernel(); 1508 1509 error = vfs_setlease(filp, arg, &flp); 1510 if (error || arg == F_UNLCK) 1511 goto out_unlock; 1512 1513 error = fasync_helper(fd, filp, 1, &flp->fl_fasync); 1514 if (error < 0) { 1515 /* remove lease just inserted by setlease */ 1516 flp->fl_type = F_UNLCK | F_INPROGRESS; 1517 flp->fl_break_time = jiffies - 10; 1518 time_out_leases(inode); 1519 goto out_unlock; 1520 } 1521 1522 error = __f_setown(filp, task_pid(current), PIDTYPE_PID, 0); 1523 out_unlock: 1524 unlock_kernel(); 1525 return error; 1526 } 1527 1528 /** 1529 * flock_lock_file_wait - Apply a FLOCK-style lock to a file 1530 * @filp: The file to apply the lock to 1531 * @fl: The lock to be applied 1532 * 1533 * Add a FLOCK style lock to a file. 1534 */ 1535 int flock_lock_file_wait(struct file *filp, struct file_lock *fl) 1536 { 1537 int error; 1538 might_sleep(); 1539 for (;;) { 1540 error = flock_lock_file(filp, fl); 1541 if ((error != -EAGAIN) || !(fl->fl_flags & FL_SLEEP)) 1542 break; 1543 error = wait_event_interruptible(fl->fl_wait, !fl->fl_next); 1544 if (!error) 1545 continue; 1546 1547 locks_delete_block(fl); 1548 break; 1549 } 1550 return error; 1551 } 1552 1553 EXPORT_SYMBOL(flock_lock_file_wait); 1554 1555 /** 1556 * sys_flock: - flock() system call. 1557 * @fd: the file descriptor to lock. 1558 * @cmd: the type of lock to apply. 1559 * 1560 * Apply a %FL_FLOCK style lock to an open file descriptor. 1561 * The @cmd can be one of 1562 * 1563 * %LOCK_SH -- a shared lock. 1564 * 1565 * %LOCK_EX -- an exclusive lock. 1566 * 1567 * %LOCK_UN -- remove an existing lock. 1568 * 1569 * %LOCK_MAND -- a `mandatory' flock. This exists to emulate Windows Share Modes. 1570 * 1571 * %LOCK_MAND can be combined with %LOCK_READ or %LOCK_WRITE to allow other 1572 * processes read and write access respectively. 1573 */ 1574 asmlinkage long sys_flock(unsigned int fd, unsigned int cmd) 1575 { 1576 struct file *filp; 1577 struct file_lock *lock; 1578 int can_sleep, unlock; 1579 int error; 1580 1581 error = -EBADF; 1582 filp = fget(fd); 1583 if (!filp) 1584 goto out; 1585 1586 can_sleep = !(cmd & LOCK_NB); 1587 cmd &= ~LOCK_NB; 1588 unlock = (cmd == LOCK_UN); 1589 1590 if (!unlock && !(cmd & LOCK_MAND) && !(filp->f_mode & 3)) 1591 goto out_putf; 1592 1593 error = flock_make_lock(filp, &lock, cmd); 1594 if (error) 1595 goto out_putf; 1596 if (can_sleep) 1597 lock->fl_flags |= FL_SLEEP; 1598 1599 error = security_file_lock(filp, cmd); 1600 if (error) 1601 goto out_free; 1602 1603 if (filp->f_op && filp->f_op->flock) 1604 error = filp->f_op->flock(filp, 1605 (can_sleep) ? F_SETLKW : F_SETLK, 1606 lock); 1607 else 1608 error = flock_lock_file_wait(filp, lock); 1609 1610 out_free: 1611 locks_free_lock(lock); 1612 1613 out_putf: 1614 fput(filp); 1615 out: 1616 return error; 1617 } 1618 1619 /** 1620 * vfs_test_lock - test file byte range lock 1621 * @filp: The file to test lock for 1622 * @fl: The lock to test; also used to hold result 1623 * 1624 * Returns -ERRNO on failure. Indicates presence of conflicting lock by 1625 * setting conf->fl_type to something other than F_UNLCK. 1626 */ 1627 int vfs_test_lock(struct file *filp, struct file_lock *fl) 1628 { 1629 if (filp->f_op && filp->f_op->lock) 1630 return filp->f_op->lock(filp, F_GETLK, fl); 1631 posix_test_lock(filp, fl); 1632 return 0; 1633 } 1634 EXPORT_SYMBOL_GPL(vfs_test_lock); 1635 1636 static int posix_lock_to_flock(struct flock *flock, struct file_lock *fl) 1637 { 1638 flock->l_pid = fl->fl_pid; 1639 #if BITS_PER_LONG == 32 1640 /* 1641 * Make sure we can represent the posix lock via 1642 * legacy 32bit flock. 1643 */ 1644 if (fl->fl_start > OFFT_OFFSET_MAX) 1645 return -EOVERFLOW; 1646 if (fl->fl_end != OFFSET_MAX && fl->fl_end > OFFT_OFFSET_MAX) 1647 return -EOVERFLOW; 1648 #endif 1649 flock->l_start = fl->fl_start; 1650 flock->l_len = fl->fl_end == OFFSET_MAX ? 0 : 1651 fl->fl_end - fl->fl_start + 1; 1652 flock->l_whence = 0; 1653 flock->l_type = fl->fl_type; 1654 return 0; 1655 } 1656 1657 #if BITS_PER_LONG == 32 1658 static void posix_lock_to_flock64(struct flock64 *flock, struct file_lock *fl) 1659 { 1660 flock->l_pid = fl->fl_pid; 1661 flock->l_start = fl->fl_start; 1662 flock->l_len = fl->fl_end == OFFSET_MAX ? 0 : 1663 fl->fl_end - fl->fl_start + 1; 1664 flock->l_whence = 0; 1665 flock->l_type = fl->fl_type; 1666 } 1667 #endif 1668 1669 /* Report the first existing lock that would conflict with l. 1670 * This implements the F_GETLK command of fcntl(). 1671 */ 1672 int fcntl_getlk(struct file *filp, struct flock __user *l) 1673 { 1674 struct file_lock file_lock; 1675 struct flock flock; 1676 int error; 1677 1678 error = -EFAULT; 1679 if (copy_from_user(&flock, l, sizeof(flock))) 1680 goto out; 1681 error = -EINVAL; 1682 if ((flock.l_type != F_RDLCK) && (flock.l_type != F_WRLCK)) 1683 goto out; 1684 1685 error = flock_to_posix_lock(filp, &file_lock, &flock); 1686 if (error) 1687 goto out; 1688 1689 error = vfs_test_lock(filp, &file_lock); 1690 if (error) 1691 goto out; 1692 1693 flock.l_type = file_lock.fl_type; 1694 if (file_lock.fl_type != F_UNLCK) { 1695 error = posix_lock_to_flock(&flock, &file_lock); 1696 if (error) 1697 goto out; 1698 } 1699 error = -EFAULT; 1700 if (!copy_to_user(l, &flock, sizeof(flock))) 1701 error = 0; 1702 out: 1703 return error; 1704 } 1705 1706 /** 1707 * vfs_lock_file - file byte range lock 1708 * @filp: The file to apply the lock to 1709 * @cmd: type of locking operation (F_SETLK, F_GETLK, etc.) 1710 * @fl: The lock to be applied 1711 * @conf: Place to return a copy of the conflicting lock, if found. 1712 * 1713 * A caller that doesn't care about the conflicting lock may pass NULL 1714 * as the final argument. 1715 * 1716 * If the filesystem defines a private ->lock() method, then @conf will 1717 * be left unchanged; so a caller that cares should initialize it to 1718 * some acceptable default. 1719 * 1720 * To avoid blocking kernel daemons, such as lockd, that need to acquire POSIX 1721 * locks, the ->lock() interface may return asynchronously, before the lock has 1722 * been granted or denied by the underlying filesystem, if (and only if) 1723 * fl_grant is set. Callers expecting ->lock() to return asynchronously 1724 * will only use F_SETLK, not F_SETLKW; they will set FL_SLEEP if (and only if) 1725 * the request is for a blocking lock. When ->lock() does return asynchronously, 1726 * it must return -EINPROGRESS, and call ->fl_grant() when the lock 1727 * request completes. 1728 * If the request is for non-blocking lock the file system should return 1729 * -EINPROGRESS then try to get the lock and call the callback routine with 1730 * the result. If the request timed out the callback routine will return a 1731 * nonzero return code and the file system should release the lock. The file 1732 * system is also responsible to keep a corresponding posix lock when it 1733 * grants a lock so the VFS can find out which locks are locally held and do 1734 * the correct lock cleanup when required. 1735 * The underlying filesystem must not drop the kernel lock or call 1736 * ->fl_grant() before returning to the caller with a -EINPROGRESS 1737 * return code. 1738 */ 1739 int vfs_lock_file(struct file *filp, unsigned int cmd, struct file_lock *fl, struct file_lock *conf) 1740 { 1741 if (filp->f_op && filp->f_op->lock) 1742 return filp->f_op->lock(filp, cmd, fl); 1743 else 1744 return posix_lock_file(filp, fl, conf); 1745 } 1746 EXPORT_SYMBOL_GPL(vfs_lock_file); 1747 1748 /* Apply the lock described by l to an open file descriptor. 1749 * This implements both the F_SETLK and F_SETLKW commands of fcntl(). 1750 */ 1751 int fcntl_setlk(unsigned int fd, struct file *filp, unsigned int cmd, 1752 struct flock __user *l) 1753 { 1754 struct file_lock *file_lock = locks_alloc_lock(); 1755 struct flock flock; 1756 struct inode *inode; 1757 int error; 1758 1759 if (file_lock == NULL) 1760 return -ENOLCK; 1761 1762 /* 1763 * This might block, so we do it before checking the inode. 1764 */ 1765 error = -EFAULT; 1766 if (copy_from_user(&flock, l, sizeof(flock))) 1767 goto out; 1768 1769 inode = filp->f_path.dentry->d_inode; 1770 1771 /* Don't allow mandatory locks on files that may be memory mapped 1772 * and shared. 1773 */ 1774 if (mandatory_lock(inode) && mapping_writably_mapped(filp->f_mapping)) { 1775 error = -EAGAIN; 1776 goto out; 1777 } 1778 1779 again: 1780 error = flock_to_posix_lock(filp, file_lock, &flock); 1781 if (error) 1782 goto out; 1783 if (cmd == F_SETLKW) { 1784 file_lock->fl_flags |= FL_SLEEP; 1785 } 1786 1787 error = -EBADF; 1788 switch (flock.l_type) { 1789 case F_RDLCK: 1790 if (!(filp->f_mode & FMODE_READ)) 1791 goto out; 1792 break; 1793 case F_WRLCK: 1794 if (!(filp->f_mode & FMODE_WRITE)) 1795 goto out; 1796 break; 1797 case F_UNLCK: 1798 break; 1799 default: 1800 error = -EINVAL; 1801 goto out; 1802 } 1803 1804 error = security_file_lock(filp, file_lock->fl_type); 1805 if (error) 1806 goto out; 1807 1808 for (;;) { 1809 error = vfs_lock_file(filp, cmd, file_lock, NULL); 1810 if (error != -EAGAIN || cmd == F_SETLK) 1811 break; 1812 error = wait_event_interruptible(file_lock->fl_wait, 1813 !file_lock->fl_next); 1814 if (!error) 1815 continue; 1816 1817 locks_delete_block(file_lock); 1818 break; 1819 } 1820 1821 /* 1822 * Attempt to detect a close/fcntl race and recover by 1823 * releasing the lock that was just acquired. 1824 */ 1825 if (!error && fcheck(fd) != filp && flock.l_type != F_UNLCK) { 1826 flock.l_type = F_UNLCK; 1827 goto again; 1828 } 1829 1830 out: 1831 locks_free_lock(file_lock); 1832 return error; 1833 } 1834 1835 #if BITS_PER_LONG == 32 1836 /* Report the first existing lock that would conflict with l. 1837 * This implements the F_GETLK command of fcntl(). 1838 */ 1839 int fcntl_getlk64(struct file *filp, struct flock64 __user *l) 1840 { 1841 struct file_lock file_lock; 1842 struct flock64 flock; 1843 int error; 1844 1845 error = -EFAULT; 1846 if (copy_from_user(&flock, l, sizeof(flock))) 1847 goto out; 1848 error = -EINVAL; 1849 if ((flock.l_type != F_RDLCK) && (flock.l_type != F_WRLCK)) 1850 goto out; 1851 1852 error = flock64_to_posix_lock(filp, &file_lock, &flock); 1853 if (error) 1854 goto out; 1855 1856 error = vfs_test_lock(filp, &file_lock); 1857 if (error) 1858 goto out; 1859 1860 flock.l_type = file_lock.fl_type; 1861 if (file_lock.fl_type != F_UNLCK) 1862 posix_lock_to_flock64(&flock, &file_lock); 1863 1864 error = -EFAULT; 1865 if (!copy_to_user(l, &flock, sizeof(flock))) 1866 error = 0; 1867 1868 out: 1869 return error; 1870 } 1871 1872 /* Apply the lock described by l to an open file descriptor. 1873 * This implements both the F_SETLK and F_SETLKW commands of fcntl(). 1874 */ 1875 int fcntl_setlk64(unsigned int fd, struct file *filp, unsigned int cmd, 1876 struct flock64 __user *l) 1877 { 1878 struct file_lock *file_lock = locks_alloc_lock(); 1879 struct flock64 flock; 1880 struct inode *inode; 1881 int error; 1882 1883 if (file_lock == NULL) 1884 return -ENOLCK; 1885 1886 /* 1887 * This might block, so we do it before checking the inode. 1888 */ 1889 error = -EFAULT; 1890 if (copy_from_user(&flock, l, sizeof(flock))) 1891 goto out; 1892 1893 inode = filp->f_path.dentry->d_inode; 1894 1895 /* Don't allow mandatory locks on files that may be memory mapped 1896 * and shared. 1897 */ 1898 if (mandatory_lock(inode) && mapping_writably_mapped(filp->f_mapping)) { 1899 error = -EAGAIN; 1900 goto out; 1901 } 1902 1903 again: 1904 error = flock64_to_posix_lock(filp, file_lock, &flock); 1905 if (error) 1906 goto out; 1907 if (cmd == F_SETLKW64) { 1908 file_lock->fl_flags |= FL_SLEEP; 1909 } 1910 1911 error = -EBADF; 1912 switch (flock.l_type) { 1913 case F_RDLCK: 1914 if (!(filp->f_mode & FMODE_READ)) 1915 goto out; 1916 break; 1917 case F_WRLCK: 1918 if (!(filp->f_mode & FMODE_WRITE)) 1919 goto out; 1920 break; 1921 case F_UNLCK: 1922 break; 1923 default: 1924 error = -EINVAL; 1925 goto out; 1926 } 1927 1928 error = security_file_lock(filp, file_lock->fl_type); 1929 if (error) 1930 goto out; 1931 1932 for (;;) { 1933 error = vfs_lock_file(filp, cmd, file_lock, NULL); 1934 if (error != -EAGAIN || cmd == F_SETLK64) 1935 break; 1936 error = wait_event_interruptible(file_lock->fl_wait, 1937 !file_lock->fl_next); 1938 if (!error) 1939 continue; 1940 1941 locks_delete_block(file_lock); 1942 break; 1943 } 1944 1945 /* 1946 * Attempt to detect a close/fcntl race and recover by 1947 * releasing the lock that was just acquired. 1948 */ 1949 if (!error && fcheck(fd) != filp && flock.l_type != F_UNLCK) { 1950 flock.l_type = F_UNLCK; 1951 goto again; 1952 } 1953 1954 out: 1955 locks_free_lock(file_lock); 1956 return error; 1957 } 1958 #endif /* BITS_PER_LONG == 32 */ 1959 1960 /* 1961 * This function is called when the file is being removed 1962 * from the task's fd array. POSIX locks belonging to this task 1963 * are deleted at this time. 1964 */ 1965 void locks_remove_posix(struct file *filp, fl_owner_t owner) 1966 { 1967 struct file_lock lock; 1968 1969 /* 1970 * If there are no locks held on this file, we don't need to call 1971 * posix_lock_file(). Another process could be setting a lock on this 1972 * file at the same time, but we wouldn't remove that lock anyway. 1973 */ 1974 if (!filp->f_path.dentry->d_inode->i_flock) 1975 return; 1976 1977 lock.fl_type = F_UNLCK; 1978 lock.fl_flags = FL_POSIX | FL_CLOSE; 1979 lock.fl_start = 0; 1980 lock.fl_end = OFFSET_MAX; 1981 lock.fl_owner = owner; 1982 lock.fl_pid = current->tgid; 1983 lock.fl_file = filp; 1984 lock.fl_ops = NULL; 1985 lock.fl_lmops = NULL; 1986 1987 vfs_lock_file(filp, F_SETLK, &lock, NULL); 1988 1989 if (lock.fl_ops && lock.fl_ops->fl_release_private) 1990 lock.fl_ops->fl_release_private(&lock); 1991 } 1992 1993 EXPORT_SYMBOL(locks_remove_posix); 1994 1995 /* 1996 * This function is called on the last close of an open file. 1997 */ 1998 void locks_remove_flock(struct file *filp) 1999 { 2000 struct inode * inode = filp->f_path.dentry->d_inode; 2001 struct file_lock *fl; 2002 struct file_lock **before; 2003 2004 if (!inode->i_flock) 2005 return; 2006 2007 if (filp->f_op && filp->f_op->flock) { 2008 struct file_lock fl = { 2009 .fl_pid = current->tgid, 2010 .fl_file = filp, 2011 .fl_flags = FL_FLOCK, 2012 .fl_type = F_UNLCK, 2013 .fl_end = OFFSET_MAX, 2014 }; 2015 filp->f_op->flock(filp, F_SETLKW, &fl); 2016 if (fl.fl_ops && fl.fl_ops->fl_release_private) 2017 fl.fl_ops->fl_release_private(&fl); 2018 } 2019 2020 lock_kernel(); 2021 before = &inode->i_flock; 2022 2023 while ((fl = *before) != NULL) { 2024 if (fl->fl_file == filp) { 2025 if (IS_FLOCK(fl)) { 2026 locks_delete_lock(before); 2027 continue; 2028 } 2029 if (IS_LEASE(fl)) { 2030 lease_modify(before, F_UNLCK); 2031 continue; 2032 } 2033 /* What? */ 2034 BUG(); 2035 } 2036 before = &fl->fl_next; 2037 } 2038 unlock_kernel(); 2039 } 2040 2041 /** 2042 * posix_unblock_lock - stop waiting for a file lock 2043 * @filp: how the file was opened 2044 * @waiter: the lock which was waiting 2045 * 2046 * lockd needs to block waiting for locks. 2047 */ 2048 int 2049 posix_unblock_lock(struct file *filp, struct file_lock *waiter) 2050 { 2051 int status = 0; 2052 2053 lock_kernel(); 2054 if (waiter->fl_next) 2055 __locks_delete_block(waiter); 2056 else 2057 status = -ENOENT; 2058 unlock_kernel(); 2059 return status; 2060 } 2061 2062 EXPORT_SYMBOL(posix_unblock_lock); 2063 2064 /** 2065 * vfs_cancel_lock - file byte range unblock lock 2066 * @filp: The file to apply the unblock to 2067 * @fl: The lock to be unblocked 2068 * 2069 * Used by lock managers to cancel blocked requests 2070 */ 2071 int vfs_cancel_lock(struct file *filp, struct file_lock *fl) 2072 { 2073 if (filp->f_op && filp->f_op->lock) 2074 return filp->f_op->lock(filp, F_CANCELLK, fl); 2075 return 0; 2076 } 2077 2078 EXPORT_SYMBOL_GPL(vfs_cancel_lock); 2079 2080 #ifdef CONFIG_PROC_FS 2081 #include <linux/seq_file.h> 2082 2083 static void lock_get_status(struct seq_file *f, struct file_lock *fl, 2084 int id, char *pfx) 2085 { 2086 struct inode *inode = NULL; 2087 2088 if (fl->fl_file != NULL) 2089 inode = fl->fl_file->f_path.dentry->d_inode; 2090 2091 seq_printf(f, "%d:%s ", id, pfx); 2092 if (IS_POSIX(fl)) { 2093 seq_printf(f, "%6s %s ", 2094 (fl->fl_flags & FL_ACCESS) ? "ACCESS" : "POSIX ", 2095 (inode == NULL) ? "*NOINODE*" : 2096 mandatory_lock(inode) ? "MANDATORY" : "ADVISORY "); 2097 } else if (IS_FLOCK(fl)) { 2098 if (fl->fl_type & LOCK_MAND) { 2099 seq_printf(f, "FLOCK MSNFS "); 2100 } else { 2101 seq_printf(f, "FLOCK ADVISORY "); 2102 } 2103 } else if (IS_LEASE(fl)) { 2104 seq_printf(f, "LEASE "); 2105 if (fl->fl_type & F_INPROGRESS) 2106 seq_printf(f, "BREAKING "); 2107 else if (fl->fl_file) 2108 seq_printf(f, "ACTIVE "); 2109 else 2110 seq_printf(f, "BREAKER "); 2111 } else { 2112 seq_printf(f, "UNKNOWN UNKNOWN "); 2113 } 2114 if (fl->fl_type & LOCK_MAND) { 2115 seq_printf(f, "%s ", 2116 (fl->fl_type & LOCK_READ) 2117 ? (fl->fl_type & LOCK_WRITE) ? "RW " : "READ " 2118 : (fl->fl_type & LOCK_WRITE) ? "WRITE" : "NONE "); 2119 } else { 2120 seq_printf(f, "%s ", 2121 (fl->fl_type & F_INPROGRESS) 2122 ? (fl->fl_type & F_UNLCK) ? "UNLCK" : "READ " 2123 : (fl->fl_type & F_WRLCK) ? "WRITE" : "READ "); 2124 } 2125 if (inode) { 2126 #ifdef WE_CAN_BREAK_LSLK_NOW 2127 seq_printf(f, "%d %s:%ld ", fl->fl_pid, 2128 inode->i_sb->s_id, inode->i_ino); 2129 #else 2130 /* userspace relies on this representation of dev_t ;-( */ 2131 seq_printf(f, "%d %02x:%02x:%ld ", fl->fl_pid, 2132 MAJOR(inode->i_sb->s_dev), 2133 MINOR(inode->i_sb->s_dev), inode->i_ino); 2134 #endif 2135 } else { 2136 seq_printf(f, "%d <none>:0 ", fl->fl_pid); 2137 } 2138 if (IS_POSIX(fl)) { 2139 if (fl->fl_end == OFFSET_MAX) 2140 seq_printf(f, "%Ld EOF\n", fl->fl_start); 2141 else 2142 seq_printf(f, "%Ld %Ld\n", fl->fl_start, fl->fl_end); 2143 } else { 2144 seq_printf(f, "0 EOF\n"); 2145 } 2146 } 2147 2148 static int locks_show(struct seq_file *f, void *v) 2149 { 2150 struct file_lock *fl, *bfl; 2151 2152 fl = list_entry(v, struct file_lock, fl_link); 2153 2154 lock_get_status(f, fl, (long)f->private, ""); 2155 2156 list_for_each_entry(bfl, &fl->fl_block, fl_block) 2157 lock_get_status(f, bfl, (long)f->private, " ->"); 2158 2159 f->private++; 2160 return 0; 2161 } 2162 2163 static void *locks_start(struct seq_file *f, loff_t *pos) 2164 { 2165 lock_kernel(); 2166 f->private = (void *)1; 2167 return seq_list_start(&file_lock_list, *pos); 2168 } 2169 2170 static void *locks_next(struct seq_file *f, void *v, loff_t *pos) 2171 { 2172 return seq_list_next(v, &file_lock_list, pos); 2173 } 2174 2175 static void locks_stop(struct seq_file *f, void *v) 2176 { 2177 unlock_kernel(); 2178 } 2179 2180 struct seq_operations locks_seq_operations = { 2181 .start = locks_start, 2182 .next = locks_next, 2183 .stop = locks_stop, 2184 .show = locks_show, 2185 }; 2186 #endif 2187 2188 /** 2189 * lock_may_read - checks that the region is free of locks 2190 * @inode: the inode that is being read 2191 * @start: the first byte to read 2192 * @len: the number of bytes to read 2193 * 2194 * Emulates Windows locking requirements. Whole-file 2195 * mandatory locks (share modes) can prohibit a read and 2196 * byte-range POSIX locks can prohibit a read if they overlap. 2197 * 2198 * N.B. this function is only ever called 2199 * from knfsd and ownership of locks is never checked. 2200 */ 2201 int lock_may_read(struct inode *inode, loff_t start, unsigned long len) 2202 { 2203 struct file_lock *fl; 2204 int result = 1; 2205 lock_kernel(); 2206 for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) { 2207 if (IS_POSIX(fl)) { 2208 if (fl->fl_type == F_RDLCK) 2209 continue; 2210 if ((fl->fl_end < start) || (fl->fl_start > (start + len))) 2211 continue; 2212 } else if (IS_FLOCK(fl)) { 2213 if (!(fl->fl_type & LOCK_MAND)) 2214 continue; 2215 if (fl->fl_type & LOCK_READ) 2216 continue; 2217 } else 2218 continue; 2219 result = 0; 2220 break; 2221 } 2222 unlock_kernel(); 2223 return result; 2224 } 2225 2226 EXPORT_SYMBOL(lock_may_read); 2227 2228 /** 2229 * lock_may_write - checks that the region is free of locks 2230 * @inode: the inode that is being written 2231 * @start: the first byte to write 2232 * @len: the number of bytes to write 2233 * 2234 * Emulates Windows locking requirements. Whole-file 2235 * mandatory locks (share modes) can prohibit a write and 2236 * byte-range POSIX locks can prohibit a write if they overlap. 2237 * 2238 * N.B. this function is only ever called 2239 * from knfsd and ownership of locks is never checked. 2240 */ 2241 int lock_may_write(struct inode *inode, loff_t start, unsigned long len) 2242 { 2243 struct file_lock *fl; 2244 int result = 1; 2245 lock_kernel(); 2246 for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) { 2247 if (IS_POSIX(fl)) { 2248 if ((fl->fl_end < start) || (fl->fl_start > (start + len))) 2249 continue; 2250 } else if (IS_FLOCK(fl)) { 2251 if (!(fl->fl_type & LOCK_MAND)) 2252 continue; 2253 if (fl->fl_type & LOCK_WRITE) 2254 continue; 2255 } else 2256 continue; 2257 result = 0; 2258 break; 2259 } 2260 unlock_kernel(); 2261 return result; 2262 } 2263 2264 EXPORT_SYMBOL(lock_may_write); 2265 2266 static int __init filelock_init(void) 2267 { 2268 filelock_cache = kmem_cache_create("file_lock_cache", 2269 sizeof(struct file_lock), 0, SLAB_PANIC, 2270 init_once); 2271 return 0; 2272 } 2273 2274 core_initcall(filelock_init); 2275