Merge branch 'firewire-kernel-streaming' of git://git.alsa-project.org/alsa-kprivate
[firewire-audio.git] / fs / locks.c
blob0f3998291f78e4fa08b5d3c102f6d8dcc120247a
1 /*
2 * linux/fs/locks.c
4 * Provide support for fcntl()'s F_GETLK, F_SETLK, and F_SETLKW calls.
5 * Doug Evans (dje@spiff.uucp), August 07, 1992
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.
12 * Miscellaneous edits, and a total rewrite of posix_lock_file() code.
13 * Kai Petzke (wpp@marie.physik.tu-berlin.de), 1994
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
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
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
31 * Implemented two lock personalities - FL_FLOCK and FL_POSIX.
33 * FL_POSIX locks are created with calls to fcntl() and lockf() through the
34 * fcntl() system call. They have the semantics described above.
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.
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).
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
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.
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.
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.
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.
72 * Tidied up block list handling. Added '/proc/locks' interface.
73 * Andy Walker (andy@lysaker.kvaerner.no), April 24, 1996.
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.
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.
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.
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.
94 * Made the block list a circular list to minimise searching in the list.
95 * Andy Walker (andy@lysaker.kvaerner.no), Sep 25, 1996.
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.
101 * Some adaptations for NFS support.
102 * Olaf Kirch (okir@monad.swb.de), Dec 1996,
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.
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.
112 * Leases and LOCK_MAND
113 * Matthew Wilcox <willy@debian.org>, June, 2000.
114 * Stephen Rothwell <sfr@canb.auug.org.au>, June, 2000.
117 #include <linux/capability.h>
118 #include <linux/file.h>
119 #include <linux/fdtable.h>
120 #include <linux/fs.h>
121 #include <linux/init.h>
122 #include <linux/module.h>
123 #include <linux/security.h>
124 #include <linux/slab.h>
125 #include <linux/syscalls.h>
126 #include <linux/time.h>
127 #include <linux/rcupdate.h>
128 #include <linux/pid_namespace.h>
130 #include <asm/uaccess.h>
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)
136 int leases_enable = 1;
137 int lease_break_time = 45;
139 #define for_each_lock(inode, lockp) \
140 for (lockp = &inode->i_flock; *lockp != NULL; lockp = &(*lockp)->fl_next)
142 static LIST_HEAD(file_lock_list);
143 static LIST_HEAD(blocked_list);
144 static DEFINE_SPINLOCK(file_lock_lock);
147 * Protects the two list heads above, plus the inode->i_flock list
148 * FIXME: should use a spinlock, once lockd and ceph are ready.
150 void lock_flocks(void)
152 spin_lock(&file_lock_lock);
154 EXPORT_SYMBOL_GPL(lock_flocks);
156 void unlock_flocks(void)
158 spin_unlock(&file_lock_lock);
160 EXPORT_SYMBOL_GPL(unlock_flocks);
162 static struct kmem_cache *filelock_cache __read_mostly;
164 /* Allocate an empty lock structure. */
165 struct file_lock *locks_alloc_lock(void)
167 return kmem_cache_alloc(filelock_cache, GFP_KERNEL);
169 EXPORT_SYMBOL_GPL(locks_alloc_lock);
171 void locks_release_private(struct file_lock *fl)
173 if (fl->fl_ops) {
174 if (fl->fl_ops->fl_release_private)
175 fl->fl_ops->fl_release_private(fl);
176 fl->fl_ops = NULL;
178 if (fl->fl_lmops) {
179 if (fl->fl_lmops->fl_release_private)
180 fl->fl_lmops->fl_release_private(fl);
181 fl->fl_lmops = NULL;
185 EXPORT_SYMBOL_GPL(locks_release_private);
187 /* Free a lock which is not in use. */
188 void locks_free_lock(struct file_lock *fl)
190 BUG_ON(waitqueue_active(&fl->fl_wait));
191 BUG_ON(!list_empty(&fl->fl_block));
192 BUG_ON(!list_empty(&fl->fl_link));
194 locks_release_private(fl);
195 kmem_cache_free(filelock_cache, fl);
197 EXPORT_SYMBOL(locks_free_lock);
199 void locks_init_lock(struct file_lock *fl)
201 INIT_LIST_HEAD(&fl->fl_link);
202 INIT_LIST_HEAD(&fl->fl_block);
203 init_waitqueue_head(&fl->fl_wait);
204 fl->fl_next = NULL;
205 fl->fl_fasync = NULL;
206 fl->fl_owner = NULL;
207 fl->fl_pid = 0;
208 fl->fl_nspid = NULL;
209 fl->fl_file = NULL;
210 fl->fl_flags = 0;
211 fl->fl_type = 0;
212 fl->fl_start = fl->fl_end = 0;
213 fl->fl_ops = NULL;
214 fl->fl_lmops = NULL;
217 EXPORT_SYMBOL(locks_init_lock);
220 * Initialises the fields of the file lock which are invariant for
221 * free file_locks.
223 static void init_once(void *foo)
225 struct file_lock *lock = (struct file_lock *) foo;
227 locks_init_lock(lock);
230 static void locks_copy_private(struct file_lock *new, struct file_lock *fl)
232 if (fl->fl_ops) {
233 if (fl->fl_ops->fl_copy_lock)
234 fl->fl_ops->fl_copy_lock(new, fl);
235 new->fl_ops = fl->fl_ops;
237 if (fl->fl_lmops)
238 new->fl_lmops = fl->fl_lmops;
242 * Initialize a new lock from an existing file_lock structure.
244 void __locks_copy_lock(struct file_lock *new, const struct file_lock *fl)
246 new->fl_owner = fl->fl_owner;
247 new->fl_pid = fl->fl_pid;
248 new->fl_file = NULL;
249 new->fl_flags = fl->fl_flags;
250 new->fl_type = fl->fl_type;
251 new->fl_start = fl->fl_start;
252 new->fl_end = fl->fl_end;
253 new->fl_ops = NULL;
254 new->fl_lmops = NULL;
256 EXPORT_SYMBOL(__locks_copy_lock);
258 void locks_copy_lock(struct file_lock *new, struct file_lock *fl)
260 locks_release_private(new);
262 __locks_copy_lock(new, fl);
263 new->fl_file = fl->fl_file;
264 new->fl_ops = fl->fl_ops;
265 new->fl_lmops = fl->fl_lmops;
267 locks_copy_private(new, fl);
270 EXPORT_SYMBOL(locks_copy_lock);
272 static inline int flock_translate_cmd(int cmd) {
273 if (cmd & LOCK_MAND)
274 return cmd & (LOCK_MAND | LOCK_RW);
275 switch (cmd) {
276 case LOCK_SH:
277 return F_RDLCK;
278 case LOCK_EX:
279 return F_WRLCK;
280 case LOCK_UN:
281 return F_UNLCK;
283 return -EINVAL;
286 /* Fill in a file_lock structure with an appropriate FLOCK lock. */
287 static int flock_make_lock(struct file *filp, struct file_lock **lock,
288 unsigned int cmd)
290 struct file_lock *fl;
291 int type = flock_translate_cmd(cmd);
292 if (type < 0)
293 return type;
295 fl = locks_alloc_lock();
296 if (fl == NULL)
297 return -ENOMEM;
299 fl->fl_file = filp;
300 fl->fl_pid = current->tgid;
301 fl->fl_flags = FL_FLOCK;
302 fl->fl_type = type;
303 fl->fl_end = OFFSET_MAX;
305 *lock = fl;
306 return 0;
309 static int assign_type(struct file_lock *fl, int type)
311 switch (type) {
312 case F_RDLCK:
313 case F_WRLCK:
314 case F_UNLCK:
315 fl->fl_type = type;
316 break;
317 default:
318 return -EINVAL;
320 return 0;
323 /* Verify a "struct flock" and copy it to a "struct file_lock" as a POSIX
324 * style lock.
326 static int flock_to_posix_lock(struct file *filp, struct file_lock *fl,
327 struct flock *l)
329 off_t start, end;
331 switch (l->l_whence) {
332 case SEEK_SET:
333 start = 0;
334 break;
335 case SEEK_CUR:
336 start = filp->f_pos;
337 break;
338 case SEEK_END:
339 start = i_size_read(filp->f_path.dentry->d_inode);
340 break;
341 default:
342 return -EINVAL;
345 /* POSIX-1996 leaves the case l->l_len < 0 undefined;
346 POSIX-2001 defines it. */
347 start += l->l_start;
348 if (start < 0)
349 return -EINVAL;
350 fl->fl_end = OFFSET_MAX;
351 if (l->l_len > 0) {
352 end = start + l->l_len - 1;
353 fl->fl_end = end;
354 } else if (l->l_len < 0) {
355 end = start - 1;
356 fl->fl_end = end;
357 start += l->l_len;
358 if (start < 0)
359 return -EINVAL;
361 fl->fl_start = start; /* we record the absolute position */
362 if (fl->fl_end < fl->fl_start)
363 return -EOVERFLOW;
365 fl->fl_owner = current->files;
366 fl->fl_pid = current->tgid;
367 fl->fl_file = filp;
368 fl->fl_flags = FL_POSIX;
369 fl->fl_ops = NULL;
370 fl->fl_lmops = NULL;
372 return assign_type(fl, l->l_type);
375 #if BITS_PER_LONG == 32
376 static int flock64_to_posix_lock(struct file *filp, struct file_lock *fl,
377 struct flock64 *l)
379 loff_t start;
381 switch (l->l_whence) {
382 case SEEK_SET:
383 start = 0;
384 break;
385 case SEEK_CUR:
386 start = filp->f_pos;
387 break;
388 case SEEK_END:
389 start = i_size_read(filp->f_path.dentry->d_inode);
390 break;
391 default:
392 return -EINVAL;
395 start += l->l_start;
396 if (start < 0)
397 return -EINVAL;
398 fl->fl_end = OFFSET_MAX;
399 if (l->l_len > 0) {
400 fl->fl_end = start + l->l_len - 1;
401 } else if (l->l_len < 0) {
402 fl->fl_end = start - 1;
403 start += l->l_len;
404 if (start < 0)
405 return -EINVAL;
407 fl->fl_start = start; /* we record the absolute position */
408 if (fl->fl_end < fl->fl_start)
409 return -EOVERFLOW;
411 fl->fl_owner = current->files;
412 fl->fl_pid = current->tgid;
413 fl->fl_file = filp;
414 fl->fl_flags = FL_POSIX;
415 fl->fl_ops = NULL;
416 fl->fl_lmops = NULL;
418 switch (l->l_type) {
419 case F_RDLCK:
420 case F_WRLCK:
421 case F_UNLCK:
422 fl->fl_type = l->l_type;
423 break;
424 default:
425 return -EINVAL;
428 return (0);
430 #endif
432 /* default lease lock manager operations */
433 static void lease_break_callback(struct file_lock *fl)
435 kill_fasync(&fl->fl_fasync, SIGIO, POLL_MSG);
438 static void lease_release_private_callback(struct file_lock *fl)
440 if (!fl->fl_file)
441 return;
443 f_delown(fl->fl_file);
444 fl->fl_file->f_owner.signum = 0;
447 static const struct lock_manager_operations lease_manager_ops = {
448 .fl_break = lease_break_callback,
449 .fl_release_private = lease_release_private_callback,
450 .fl_change = lease_modify,
454 * Initialize a lease, use the default lock manager operations
456 static int lease_init(struct file *filp, int type, struct file_lock *fl)
458 if (assign_type(fl, type) != 0)
459 return -EINVAL;
461 fl->fl_owner = current->files;
462 fl->fl_pid = current->tgid;
464 fl->fl_file = filp;
465 fl->fl_flags = FL_LEASE;
466 fl->fl_start = 0;
467 fl->fl_end = OFFSET_MAX;
468 fl->fl_ops = NULL;
469 fl->fl_lmops = &lease_manager_ops;
470 return 0;
473 /* Allocate a file_lock initialised to this type of lease */
474 static struct file_lock *lease_alloc(struct file *filp, int type)
476 struct file_lock *fl = locks_alloc_lock();
477 int error = -ENOMEM;
479 if (fl == NULL)
480 return ERR_PTR(error);
482 error = lease_init(filp, type, fl);
483 if (error) {
484 locks_free_lock(fl);
485 return ERR_PTR(error);
487 return fl;
490 /* Check if two locks overlap each other.
492 static inline int locks_overlap(struct file_lock *fl1, struct file_lock *fl2)
494 return ((fl1->fl_end >= fl2->fl_start) &&
495 (fl2->fl_end >= fl1->fl_start));
499 * Check whether two locks have the same owner.
501 static int posix_same_owner(struct file_lock *fl1, struct file_lock *fl2)
503 if (fl1->fl_lmops && fl1->fl_lmops->fl_compare_owner)
504 return fl2->fl_lmops == fl1->fl_lmops &&
505 fl1->fl_lmops->fl_compare_owner(fl1, fl2);
506 return fl1->fl_owner == fl2->fl_owner;
509 /* Remove waiter from blocker's block list.
510 * When blocker ends up pointing to itself then the list is empty.
512 static void __locks_delete_block(struct file_lock *waiter)
514 list_del_init(&waiter->fl_block);
515 list_del_init(&waiter->fl_link);
516 waiter->fl_next = NULL;
521 static void locks_delete_block(struct file_lock *waiter)
523 lock_flocks();
524 __locks_delete_block(waiter);
525 unlock_flocks();
528 /* Insert waiter into blocker's block list.
529 * We use a circular list so that processes can be easily woken up in
530 * the order they blocked. The documentation doesn't require this but
531 * it seems like the reasonable thing to do.
533 static void locks_insert_block(struct file_lock *blocker,
534 struct file_lock *waiter)
536 BUG_ON(!list_empty(&waiter->fl_block));
537 list_add_tail(&waiter->fl_block, &blocker->fl_block);
538 waiter->fl_next = blocker;
539 if (IS_POSIX(blocker))
540 list_add(&waiter->fl_link, &blocked_list);
543 /* Wake up processes blocked waiting for blocker.
544 * If told to wait then schedule the processes until the block list
545 * is empty, otherwise empty the block list ourselves.
547 static void locks_wake_up_blocks(struct file_lock *blocker)
549 while (!list_empty(&blocker->fl_block)) {
550 struct file_lock *waiter;
552 waiter = list_first_entry(&blocker->fl_block,
553 struct file_lock, fl_block);
554 __locks_delete_block(waiter);
555 if (waiter->fl_lmops && waiter->fl_lmops->fl_notify)
556 waiter->fl_lmops->fl_notify(waiter);
557 else
558 wake_up(&waiter->fl_wait);
562 /* Insert file lock fl into an inode's lock list at the position indicated
563 * by pos. At the same time add the lock to the global file lock list.
565 static void locks_insert_lock(struct file_lock **pos, struct file_lock *fl)
567 list_add(&fl->fl_link, &file_lock_list);
569 fl->fl_nspid = get_pid(task_tgid(current));
571 /* insert into file's list */
572 fl->fl_next = *pos;
573 *pos = fl;
577 * Delete a lock and then free it.
578 * Wake up processes that are blocked waiting for this lock,
579 * notify the FS that the lock has been cleared and
580 * finally free the lock.
582 static void locks_delete_lock(struct file_lock **thisfl_p)
584 struct file_lock *fl = *thisfl_p;
586 *thisfl_p = fl->fl_next;
587 fl->fl_next = NULL;
588 list_del_init(&fl->fl_link);
590 fasync_helper(0, fl->fl_file, 0, &fl->fl_fasync);
591 if (fl->fl_fasync != NULL) {
592 printk(KERN_ERR "locks_delete_lock: fasync == %p\n", fl->fl_fasync);
593 fl->fl_fasync = NULL;
596 if (fl->fl_nspid) {
597 put_pid(fl->fl_nspid);
598 fl->fl_nspid = NULL;
601 locks_wake_up_blocks(fl);
602 locks_free_lock(fl);
605 /* Determine if lock sys_fl blocks lock caller_fl. Common functionality
606 * checks for shared/exclusive status of overlapping locks.
608 static int locks_conflict(struct file_lock *caller_fl, struct file_lock *sys_fl)
610 if (sys_fl->fl_type == F_WRLCK)
611 return 1;
612 if (caller_fl->fl_type == F_WRLCK)
613 return 1;
614 return 0;
617 /* Determine if lock sys_fl blocks lock caller_fl. POSIX specific
618 * checking before calling the locks_conflict().
620 static int posix_locks_conflict(struct file_lock *caller_fl, struct file_lock *sys_fl)
622 /* POSIX locks owned by the same process do not conflict with
623 * each other.
625 if (!IS_POSIX(sys_fl) || posix_same_owner(caller_fl, sys_fl))
626 return (0);
628 /* Check whether they overlap */
629 if (!locks_overlap(caller_fl, sys_fl))
630 return 0;
632 return (locks_conflict(caller_fl, sys_fl));
635 /* Determine if lock sys_fl blocks lock caller_fl. FLOCK specific
636 * checking before calling the locks_conflict().
638 static int flock_locks_conflict(struct file_lock *caller_fl, struct file_lock *sys_fl)
640 /* FLOCK locks referring to the same filp do not conflict with
641 * each other.
643 if (!IS_FLOCK(sys_fl) || (caller_fl->fl_file == sys_fl->fl_file))
644 return (0);
645 if ((caller_fl->fl_type & LOCK_MAND) || (sys_fl->fl_type & LOCK_MAND))
646 return 0;
648 return (locks_conflict(caller_fl, sys_fl));
651 void
652 posix_test_lock(struct file *filp, struct file_lock *fl)
654 struct file_lock *cfl;
656 lock_flocks();
657 for (cfl = filp->f_path.dentry->d_inode->i_flock; cfl; cfl = cfl->fl_next) {
658 if (!IS_POSIX(cfl))
659 continue;
660 if (posix_locks_conflict(fl, cfl))
661 break;
663 if (cfl) {
664 __locks_copy_lock(fl, cfl);
665 if (cfl->fl_nspid)
666 fl->fl_pid = pid_vnr(cfl->fl_nspid);
667 } else
668 fl->fl_type = F_UNLCK;
669 unlock_flocks();
670 return;
672 EXPORT_SYMBOL(posix_test_lock);
675 * Deadlock detection:
677 * We attempt to detect deadlocks that are due purely to posix file
678 * locks.
680 * We assume that a task can be waiting for at most one lock at a time.
681 * So for any acquired lock, the process holding that lock may be
682 * waiting on at most one other lock. That lock in turns may be held by
683 * someone waiting for at most one other lock. Given a requested lock
684 * caller_fl which is about to wait for a conflicting lock block_fl, we
685 * follow this chain of waiters to ensure we are not about to create a
686 * cycle.
688 * Since we do this before we ever put a process to sleep on a lock, we
689 * are ensured that there is never a cycle; that is what guarantees that
690 * the while() loop in posix_locks_deadlock() eventually completes.
692 * Note: the above assumption may not be true when handling lock
693 * requests from a broken NFS client. It may also fail in the presence
694 * of tasks (such as posix threads) sharing the same open file table.
696 * To handle those cases, we just bail out after a few iterations.
699 #define MAX_DEADLK_ITERATIONS 10
701 /* Find a lock that the owner of the given block_fl is blocking on. */
702 static struct file_lock *what_owner_is_waiting_for(struct file_lock *block_fl)
704 struct file_lock *fl;
706 list_for_each_entry(fl, &blocked_list, fl_link) {
707 if (posix_same_owner(fl, block_fl))
708 return fl->fl_next;
710 return NULL;
713 static int posix_locks_deadlock(struct file_lock *caller_fl,
714 struct file_lock *block_fl)
716 int i = 0;
718 while ((block_fl = what_owner_is_waiting_for(block_fl))) {
719 if (i++ > MAX_DEADLK_ITERATIONS)
720 return 0;
721 if (posix_same_owner(caller_fl, block_fl))
722 return 1;
724 return 0;
727 /* Try to create a FLOCK lock on filp. We always insert new FLOCK locks
728 * after any leases, but before any posix locks.
730 * Note that if called with an FL_EXISTS argument, the caller may determine
731 * whether or not a lock was successfully freed by testing the return
732 * value for -ENOENT.
734 static int flock_lock_file(struct file *filp, struct file_lock *request)
736 struct file_lock *new_fl = NULL;
737 struct file_lock **before;
738 struct inode * inode = filp->f_path.dentry->d_inode;
739 int error = 0;
740 int found = 0;
742 if (!(request->fl_flags & FL_ACCESS) && (request->fl_type != F_UNLCK)) {
743 new_fl = locks_alloc_lock();
744 if (!new_fl)
745 return -ENOMEM;
748 lock_flocks();
749 if (request->fl_flags & FL_ACCESS)
750 goto find_conflict;
752 for_each_lock(inode, before) {
753 struct file_lock *fl = *before;
754 if (IS_POSIX(fl))
755 break;
756 if (IS_LEASE(fl))
757 continue;
758 if (filp != fl->fl_file)
759 continue;
760 if (request->fl_type == fl->fl_type)
761 goto out;
762 found = 1;
763 locks_delete_lock(before);
764 break;
767 if (request->fl_type == F_UNLCK) {
768 if ((request->fl_flags & FL_EXISTS) && !found)
769 error = -ENOENT;
770 goto out;
774 * If a higher-priority process was blocked on the old file lock,
775 * give it the opportunity to lock the file.
777 if (found) {
778 unlock_flocks();
779 cond_resched();
780 lock_flocks();
783 find_conflict:
784 for_each_lock(inode, before) {
785 struct file_lock *fl = *before;
786 if (IS_POSIX(fl))
787 break;
788 if (IS_LEASE(fl))
789 continue;
790 if (!flock_locks_conflict(request, fl))
791 continue;
792 error = -EAGAIN;
793 if (!(request->fl_flags & FL_SLEEP))
794 goto out;
795 error = FILE_LOCK_DEFERRED;
796 locks_insert_block(fl, request);
797 goto out;
799 if (request->fl_flags & FL_ACCESS)
800 goto out;
801 locks_copy_lock(new_fl, request);
802 locks_insert_lock(before, new_fl);
803 new_fl = NULL;
804 error = 0;
806 out:
807 unlock_flocks();
808 if (new_fl)
809 locks_free_lock(new_fl);
810 return error;
813 static int __posix_lock_file(struct inode *inode, struct file_lock *request, struct file_lock *conflock)
815 struct file_lock *fl;
816 struct file_lock *new_fl = NULL;
817 struct file_lock *new_fl2 = NULL;
818 struct file_lock *left = NULL;
819 struct file_lock *right = NULL;
820 struct file_lock **before;
821 int error, added = 0;
824 * We may need two file_lock structures for this operation,
825 * so we get them in advance to avoid races.
827 * In some cases we can be sure, that no new locks will be needed
829 if (!(request->fl_flags & FL_ACCESS) &&
830 (request->fl_type != F_UNLCK ||
831 request->fl_start != 0 || request->fl_end != OFFSET_MAX)) {
832 new_fl = locks_alloc_lock();
833 new_fl2 = locks_alloc_lock();
836 lock_flocks();
837 if (request->fl_type != F_UNLCK) {
838 for_each_lock(inode, before) {
839 fl = *before;
840 if (!IS_POSIX(fl))
841 continue;
842 if (!posix_locks_conflict(request, fl))
843 continue;
844 if (conflock)
845 __locks_copy_lock(conflock, fl);
846 error = -EAGAIN;
847 if (!(request->fl_flags & FL_SLEEP))
848 goto out;
849 error = -EDEADLK;
850 if (posix_locks_deadlock(request, fl))
851 goto out;
852 error = FILE_LOCK_DEFERRED;
853 locks_insert_block(fl, request);
854 goto out;
858 /* If we're just looking for a conflict, we're done. */
859 error = 0;
860 if (request->fl_flags & FL_ACCESS)
861 goto out;
864 * Find the first old lock with the same owner as the new lock.
867 before = &inode->i_flock;
869 /* First skip locks owned by other processes. */
870 while ((fl = *before) && (!IS_POSIX(fl) ||
871 !posix_same_owner(request, fl))) {
872 before = &fl->fl_next;
875 /* Process locks with this owner. */
876 while ((fl = *before) && posix_same_owner(request, fl)) {
877 /* Detect adjacent or overlapping regions (if same lock type)
879 if (request->fl_type == fl->fl_type) {
880 /* In all comparisons of start vs end, use
881 * "start - 1" rather than "end + 1". If end
882 * is OFFSET_MAX, end + 1 will become negative.
884 if (fl->fl_end < request->fl_start - 1)
885 goto next_lock;
886 /* If the next lock in the list has entirely bigger
887 * addresses than the new one, insert the lock here.
889 if (fl->fl_start - 1 > request->fl_end)
890 break;
892 /* If we come here, the new and old lock are of the
893 * same type and adjacent or overlapping. Make one
894 * lock yielding from the lower start address of both
895 * locks to the higher end address.
897 if (fl->fl_start > request->fl_start)
898 fl->fl_start = request->fl_start;
899 else
900 request->fl_start = fl->fl_start;
901 if (fl->fl_end < request->fl_end)
902 fl->fl_end = request->fl_end;
903 else
904 request->fl_end = fl->fl_end;
905 if (added) {
906 locks_delete_lock(before);
907 continue;
909 request = fl;
910 added = 1;
912 else {
913 /* Processing for different lock types is a bit
914 * more complex.
916 if (fl->fl_end < request->fl_start)
917 goto next_lock;
918 if (fl->fl_start > request->fl_end)
919 break;
920 if (request->fl_type == F_UNLCK)
921 added = 1;
922 if (fl->fl_start < request->fl_start)
923 left = fl;
924 /* If the next lock in the list has a higher end
925 * address than the new one, insert the new one here.
927 if (fl->fl_end > request->fl_end) {
928 right = fl;
929 break;
931 if (fl->fl_start >= request->fl_start) {
932 /* The new lock completely replaces an old
933 * one (This may happen several times).
935 if (added) {
936 locks_delete_lock(before);
937 continue;
939 /* Replace the old lock with the new one.
940 * Wake up anybody waiting for the old one,
941 * as the change in lock type might satisfy
942 * their needs.
944 locks_wake_up_blocks(fl);
945 fl->fl_start = request->fl_start;
946 fl->fl_end = request->fl_end;
947 fl->fl_type = request->fl_type;
948 locks_release_private(fl);
949 locks_copy_private(fl, request);
950 request = fl;
951 added = 1;
954 /* Go on to next lock.
956 next_lock:
957 before = &fl->fl_next;
961 * The above code only modifies existing locks in case of
962 * merging or replacing. If new lock(s) need to be inserted
963 * all modifications are done bellow this, so it's safe yet to
964 * bail out.
966 error = -ENOLCK; /* "no luck" */
967 if (right && left == right && !new_fl2)
968 goto out;
970 error = 0;
971 if (!added) {
972 if (request->fl_type == F_UNLCK) {
973 if (request->fl_flags & FL_EXISTS)
974 error = -ENOENT;
975 goto out;
978 if (!new_fl) {
979 error = -ENOLCK;
980 goto out;
982 locks_copy_lock(new_fl, request);
983 locks_insert_lock(before, new_fl);
984 new_fl = NULL;
986 if (right) {
987 if (left == right) {
988 /* The new lock breaks the old one in two pieces,
989 * so we have to use the second new lock.
991 left = new_fl2;
992 new_fl2 = NULL;
993 locks_copy_lock(left, right);
994 locks_insert_lock(before, left);
996 right->fl_start = request->fl_end + 1;
997 locks_wake_up_blocks(right);
999 if (left) {
1000 left->fl_end = request->fl_start - 1;
1001 locks_wake_up_blocks(left);
1003 out:
1004 unlock_flocks();
1006 * Free any unused locks.
1008 if (new_fl)
1009 locks_free_lock(new_fl);
1010 if (new_fl2)
1011 locks_free_lock(new_fl2);
1012 return error;
1016 * posix_lock_file - Apply a POSIX-style lock to a file
1017 * @filp: The file to apply the lock to
1018 * @fl: The lock to be applied
1019 * @conflock: Place to return a copy of the conflicting lock, if found.
1021 * Add a POSIX style lock to a file.
1022 * We merge adjacent & overlapping locks whenever possible.
1023 * POSIX locks are sorted by owner task, then by starting address
1025 * Note that if called with an FL_EXISTS argument, the caller may determine
1026 * whether or not a lock was successfully freed by testing the return
1027 * value for -ENOENT.
1029 int posix_lock_file(struct file *filp, struct file_lock *fl,
1030 struct file_lock *conflock)
1032 return __posix_lock_file(filp->f_path.dentry->d_inode, fl, conflock);
1034 EXPORT_SYMBOL(posix_lock_file);
1037 * posix_lock_file_wait - Apply a POSIX-style lock to a file
1038 * @filp: The file to apply the lock to
1039 * @fl: The lock to be applied
1041 * Add a POSIX style lock to a file.
1042 * We merge adjacent & overlapping locks whenever possible.
1043 * POSIX locks are sorted by owner task, then by starting address
1045 int posix_lock_file_wait(struct file *filp, struct file_lock *fl)
1047 int error;
1048 might_sleep ();
1049 for (;;) {
1050 error = posix_lock_file(filp, fl, NULL);
1051 if (error != FILE_LOCK_DEFERRED)
1052 break;
1053 error = wait_event_interruptible(fl->fl_wait, !fl->fl_next);
1054 if (!error)
1055 continue;
1057 locks_delete_block(fl);
1058 break;
1060 return error;
1062 EXPORT_SYMBOL(posix_lock_file_wait);
1065 * locks_mandatory_locked - Check for an active lock
1066 * @inode: the file to check
1068 * Searches the inode's list of locks to find any POSIX locks which conflict.
1069 * This function is called from locks_verify_locked() only.
1071 int locks_mandatory_locked(struct inode *inode)
1073 fl_owner_t owner = current->files;
1074 struct file_lock *fl;
1077 * Search the lock list for this inode for any POSIX locks.
1079 lock_flocks();
1080 for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) {
1081 if (!IS_POSIX(fl))
1082 continue;
1083 if (fl->fl_owner != owner)
1084 break;
1086 unlock_flocks();
1087 return fl ? -EAGAIN : 0;
1091 * locks_mandatory_area - Check for a conflicting lock
1092 * @read_write: %FLOCK_VERIFY_WRITE for exclusive access, %FLOCK_VERIFY_READ
1093 * for shared
1094 * @inode: the file to check
1095 * @filp: how the file was opened (if it was)
1096 * @offset: start of area to check
1097 * @count: length of area to check
1099 * Searches the inode's list of locks to find any POSIX locks which conflict.
1100 * This function is called from rw_verify_area() and
1101 * locks_verify_truncate().
1103 int locks_mandatory_area(int read_write, struct inode *inode,
1104 struct file *filp, loff_t offset,
1105 size_t count)
1107 struct file_lock fl;
1108 int error;
1110 locks_init_lock(&fl);
1111 fl.fl_owner = current->files;
1112 fl.fl_pid = current->tgid;
1113 fl.fl_file = filp;
1114 fl.fl_flags = FL_POSIX | FL_ACCESS;
1115 if (filp && !(filp->f_flags & O_NONBLOCK))
1116 fl.fl_flags |= FL_SLEEP;
1117 fl.fl_type = (read_write == FLOCK_VERIFY_WRITE) ? F_WRLCK : F_RDLCK;
1118 fl.fl_start = offset;
1119 fl.fl_end = offset + count - 1;
1121 for (;;) {
1122 error = __posix_lock_file(inode, &fl, NULL);
1123 if (error != FILE_LOCK_DEFERRED)
1124 break;
1125 error = wait_event_interruptible(fl.fl_wait, !fl.fl_next);
1126 if (!error) {
1128 * If we've been sleeping someone might have
1129 * changed the permissions behind our back.
1131 if (__mandatory_lock(inode))
1132 continue;
1135 locks_delete_block(&fl);
1136 break;
1139 return error;
1142 EXPORT_SYMBOL(locks_mandatory_area);
1144 /* We already had a lease on this file; just change its type */
1145 int lease_modify(struct file_lock **before, int arg)
1147 struct file_lock *fl = *before;
1148 int error = assign_type(fl, arg);
1150 if (error)
1151 return error;
1152 locks_wake_up_blocks(fl);
1153 if (arg == F_UNLCK)
1154 locks_delete_lock(before);
1155 return 0;
1158 EXPORT_SYMBOL(lease_modify);
1160 static void time_out_leases(struct inode *inode)
1162 struct file_lock **before;
1163 struct file_lock *fl;
1165 before = &inode->i_flock;
1166 while ((fl = *before) && IS_LEASE(fl) && (fl->fl_type & F_INPROGRESS)) {
1167 if ((fl->fl_break_time == 0)
1168 || time_before(jiffies, fl->fl_break_time)) {
1169 before = &fl->fl_next;
1170 continue;
1172 lease_modify(before, fl->fl_type & ~F_INPROGRESS);
1173 if (fl == *before) /* lease_modify may have freed fl */
1174 before = &fl->fl_next;
1179 * __break_lease - revoke all outstanding leases on file
1180 * @inode: the inode of the file to return
1181 * @mode: the open mode (read or write)
1183 * break_lease (inlined for speed) has checked there already is at least
1184 * some kind of lock (maybe a lease) on this file. Leases are broken on
1185 * a call to open() or truncate(). This function can sleep unless you
1186 * specified %O_NONBLOCK to your open().
1188 int __break_lease(struct inode *inode, unsigned int mode)
1190 int error = 0, future;
1191 struct file_lock *new_fl, *flock;
1192 struct file_lock *fl;
1193 unsigned long break_time;
1194 int i_have_this_lease = 0;
1195 int want_write = (mode & O_ACCMODE) != O_RDONLY;
1197 new_fl = lease_alloc(NULL, want_write ? F_WRLCK : F_RDLCK);
1199 lock_flocks();
1201 time_out_leases(inode);
1203 flock = inode->i_flock;
1204 if ((flock == NULL) || !IS_LEASE(flock))
1205 goto out;
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;
1211 if (want_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;
1225 if (IS_ERR(new_fl) && !i_have_this_lease
1226 && ((mode & O_NONBLOCK) == 0)) {
1227 error = PTR_ERR(new_fl);
1228 goto out;
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 */
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);
1247 if (i_have_this_lease || (mode & O_NONBLOCK)) {
1248 error = -EWOULDBLOCK;
1249 goto out;
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++;
1259 locks_insert_block(flock, new_fl);
1260 unlock_flocks();
1261 error = wait_event_interruptible_timeout(new_fl->fl_wait,
1262 !new_fl->fl_next, break_time);
1263 lock_flocks();
1264 __locks_delete_block(new_fl);
1265 if (error >= 0) {
1266 if (error == 0)
1267 time_out_leases(inode);
1268 /* Wait for the next lease that has not been broken yet */
1269 for (flock = inode->i_flock; flock && IS_LEASE(flock);
1270 flock = flock->fl_next) {
1271 if (flock->fl_type & F_INPROGRESS)
1272 goto restart;
1274 error = 0;
1277 out:
1278 unlock_flocks();
1279 if (!IS_ERR(new_fl))
1280 locks_free_lock(new_fl);
1281 return error;
1284 EXPORT_SYMBOL(__break_lease);
1287 * lease_get_mtime - get the last modified time of an inode
1288 * @inode: the inode
1289 * @time: pointer to a timespec which will contain the last modified time
1291 * This is to force NFS clients to flush their caches for files with
1292 * exclusive leases. The justification is that if someone has an
1293 * exclusive lease, then they could be modifying it.
1295 void lease_get_mtime(struct inode *inode, struct timespec *time)
1297 struct file_lock *flock = inode->i_flock;
1298 if (flock && IS_LEASE(flock) && (flock->fl_type & F_WRLCK))
1299 *time = current_fs_time(inode->i_sb);
1300 else
1301 *time = inode->i_mtime;
1304 EXPORT_SYMBOL(lease_get_mtime);
1307 * fcntl_getlease - Enquire what lease is currently active
1308 * @filp: the file
1310 * The value returned by this function will be one of
1311 * (if no lease break is pending):
1313 * %F_RDLCK to indicate a shared lease is held.
1315 * %F_WRLCK to indicate an exclusive lease is held.
1317 * %F_UNLCK to indicate no lease is held.
1319 * (if a lease break is pending):
1321 * %F_RDLCK to indicate an exclusive lease needs to be
1322 * changed to a shared lease (or removed).
1324 * %F_UNLCK to indicate the lease needs to be removed.
1326 * XXX: sfr & willy disagree over whether F_INPROGRESS
1327 * should be returned to userspace.
1329 int fcntl_getlease(struct file *filp)
1331 struct file_lock *fl;
1332 int type = F_UNLCK;
1334 lock_flocks();
1335 time_out_leases(filp->f_path.dentry->d_inode);
1336 for (fl = filp->f_path.dentry->d_inode->i_flock; fl && IS_LEASE(fl);
1337 fl = fl->fl_next) {
1338 if (fl->fl_file == filp) {
1339 type = fl->fl_type & ~F_INPROGRESS;
1340 break;
1343 unlock_flocks();
1344 return type;
1348 * generic_setlease - sets a lease on an open file
1349 * @filp: file pointer
1350 * @arg: type of lease to obtain
1351 * @flp: input - file_lock to use, output - file_lock inserted
1353 * The (input) flp->fl_lmops->fl_break function is required
1354 * by break_lease().
1356 * Called with file_lock_lock held.
1358 int generic_setlease(struct file *filp, long arg, struct file_lock **flp)
1360 struct file_lock *fl, **before, **my_before = NULL, *lease;
1361 struct dentry *dentry = filp->f_path.dentry;
1362 struct inode *inode = dentry->d_inode;
1363 int error, rdlease_count = 0, wrlease_count = 0;
1365 lease = *flp;
1367 error = -EACCES;
1368 if ((current_fsuid() != inode->i_uid) && !capable(CAP_LEASE))
1369 goto out;
1370 error = -EINVAL;
1371 if (!S_ISREG(inode->i_mode))
1372 goto out;
1373 error = security_file_lock(filp, arg);
1374 if (error)
1375 goto out;
1377 time_out_leases(inode);
1379 BUG_ON(!(*flp)->fl_lmops->fl_break);
1381 if (arg != F_UNLCK) {
1382 error = -EAGAIN;
1383 if ((arg == F_RDLCK) && (atomic_read(&inode->i_writecount) > 0))
1384 goto out;
1385 if ((arg == F_WRLCK)
1386 && ((dentry->d_count > 1)
1387 || (atomic_read(&inode->i_count) > 1)))
1388 goto out;
1392 * At this point, we know that if there is an exclusive
1393 * lease on this file, then we hold it on this filp
1394 * (otherwise our open of this file would have blocked).
1395 * And if we are trying to acquire an exclusive lease,
1396 * then the file is not open by anyone (including us)
1397 * except for this filp.
1399 for (before = &inode->i_flock;
1400 ((fl = *before) != NULL) && IS_LEASE(fl);
1401 before = &fl->fl_next) {
1402 if (fl->fl_file == filp)
1403 my_before = before;
1404 else if (fl->fl_type == (F_INPROGRESS | F_UNLCK))
1406 * Someone is in the process of opening this
1407 * file for writing so we may not take an
1408 * exclusive lease on it.
1410 wrlease_count++;
1411 else
1412 rdlease_count++;
1415 error = -EAGAIN;
1416 if ((arg == F_RDLCK && (wrlease_count > 0)) ||
1417 (arg == F_WRLCK && ((rdlease_count + wrlease_count) > 0)))
1418 goto out;
1420 if (my_before != NULL) {
1421 error = lease->fl_lmops->fl_change(my_before, arg);
1422 if (!error)
1423 *flp = *my_before;
1424 goto out;
1427 if (arg == F_UNLCK)
1428 goto out;
1430 error = -EINVAL;
1431 if (!leases_enable)
1432 goto out;
1434 locks_insert_lock(before, lease);
1435 return 0;
1437 out:
1438 return error;
1440 EXPORT_SYMBOL(generic_setlease);
1442 static int __vfs_setlease(struct file *filp, long arg, struct file_lock **lease)
1444 if (filp->f_op && filp->f_op->setlease)
1445 return filp->f_op->setlease(filp, arg, lease);
1446 else
1447 return generic_setlease(filp, arg, lease);
1451 * vfs_setlease - sets a lease on an open file
1452 * @filp: file pointer
1453 * @arg: type of lease to obtain
1454 * @lease: file_lock to use
1456 * Call this to establish a lease on the file.
1457 * The (*lease)->fl_lmops->fl_break operation must be set; if not,
1458 * break_lease will oops!
1460 * This will call the filesystem's setlease file method, if
1461 * defined. Note that there is no getlease method; instead, the
1462 * filesystem setlease method should call back to setlease() to
1463 * add a lease to the inode's lease list, where fcntl_getlease() can
1464 * find it. Since fcntl_getlease() only reports whether the current
1465 * task holds a lease, a cluster filesystem need only do this for
1466 * leases held by processes on this node.
1468 * There is also no break_lease method; filesystems that
1469 * handle their own leases should break leases themselves from the
1470 * filesystem's open, create, and (on truncate) setattr methods.
1472 * Warning: the only current setlease methods exist only to disable
1473 * leases in certain cases. More vfs changes may be required to
1474 * allow a full filesystem lease implementation.
1477 int vfs_setlease(struct file *filp, long arg, struct file_lock **lease)
1479 int error;
1481 lock_flocks();
1482 error = __vfs_setlease(filp, arg, lease);
1483 unlock_flocks();
1485 return error;
1487 EXPORT_SYMBOL_GPL(vfs_setlease);
1489 static int do_fcntl_delete_lease(struct file *filp)
1491 struct file_lock fl, *flp = &fl;
1493 lease_init(filp, F_UNLCK, flp);
1495 return vfs_setlease(filp, F_UNLCK, &flp);
1498 static int do_fcntl_add_lease(unsigned int fd, struct file *filp, long arg)
1500 struct file_lock *fl, *ret;
1501 struct fasync_struct *new;
1502 int error;
1504 fl = lease_alloc(filp, arg);
1505 if (IS_ERR(fl))
1506 return PTR_ERR(fl);
1508 new = fasync_alloc();
1509 if (!new) {
1510 locks_free_lock(fl);
1511 return -ENOMEM;
1513 ret = fl;
1514 lock_flocks();
1515 error = __vfs_setlease(filp, arg, &ret);
1516 if (error) {
1517 unlock_flocks();
1518 locks_free_lock(fl);
1519 goto out_free_fasync;
1521 if (ret != fl)
1522 locks_free_lock(fl);
1525 * fasync_insert_entry() returns the old entry if any.
1526 * If there was no old entry, then it used 'new' and
1527 * inserted it into the fasync list. Clear new so that
1528 * we don't release it here.
1530 if (!fasync_insert_entry(fd, filp, &ret->fl_fasync, new))
1531 new = NULL;
1533 error = __f_setown(filp, task_pid(current), PIDTYPE_PID, 0);
1534 unlock_flocks();
1536 out_free_fasync:
1537 if (new)
1538 fasync_free(new);
1539 return error;
1543 * fcntl_setlease - sets a lease on an open file
1544 * @fd: open file descriptor
1545 * @filp: file pointer
1546 * @arg: type of lease to obtain
1548 * Call this fcntl to establish a lease on the file.
1549 * Note that you also need to call %F_SETSIG to
1550 * receive a signal when the lease is broken.
1552 int fcntl_setlease(unsigned int fd, struct file *filp, long arg)
1554 if (arg == F_UNLCK)
1555 return do_fcntl_delete_lease(filp);
1556 return do_fcntl_add_lease(fd, filp, arg);
1560 * flock_lock_file_wait - Apply a FLOCK-style lock to a file
1561 * @filp: The file to apply the lock to
1562 * @fl: The lock to be applied
1564 * Add a FLOCK style lock to a file.
1566 int flock_lock_file_wait(struct file *filp, struct file_lock *fl)
1568 int error;
1569 might_sleep();
1570 for (;;) {
1571 error = flock_lock_file(filp, fl);
1572 if (error != FILE_LOCK_DEFERRED)
1573 break;
1574 error = wait_event_interruptible(fl->fl_wait, !fl->fl_next);
1575 if (!error)
1576 continue;
1578 locks_delete_block(fl);
1579 break;
1581 return error;
1584 EXPORT_SYMBOL(flock_lock_file_wait);
1587 * sys_flock: - flock() system call.
1588 * @fd: the file descriptor to lock.
1589 * @cmd: the type of lock to apply.
1591 * Apply a %FL_FLOCK style lock to an open file descriptor.
1592 * The @cmd can be one of
1594 * %LOCK_SH -- a shared lock.
1596 * %LOCK_EX -- an exclusive lock.
1598 * %LOCK_UN -- remove an existing lock.
1600 * %LOCK_MAND -- a `mandatory' flock. This exists to emulate Windows Share Modes.
1602 * %LOCK_MAND can be combined with %LOCK_READ or %LOCK_WRITE to allow other
1603 * processes read and write access respectively.
1605 SYSCALL_DEFINE2(flock, unsigned int, fd, unsigned int, cmd)
1607 struct file *filp;
1608 struct file_lock *lock;
1609 int can_sleep, unlock;
1610 int error;
1612 error = -EBADF;
1613 filp = fget(fd);
1614 if (!filp)
1615 goto out;
1617 can_sleep = !(cmd & LOCK_NB);
1618 cmd &= ~LOCK_NB;
1619 unlock = (cmd == LOCK_UN);
1621 if (!unlock && !(cmd & LOCK_MAND) &&
1622 !(filp->f_mode & (FMODE_READ|FMODE_WRITE)))
1623 goto out_putf;
1625 error = flock_make_lock(filp, &lock, cmd);
1626 if (error)
1627 goto out_putf;
1628 if (can_sleep)
1629 lock->fl_flags |= FL_SLEEP;
1631 error = security_file_lock(filp, lock->fl_type);
1632 if (error)
1633 goto out_free;
1635 if (filp->f_op && filp->f_op->flock)
1636 error = filp->f_op->flock(filp,
1637 (can_sleep) ? F_SETLKW : F_SETLK,
1638 lock);
1639 else
1640 error = flock_lock_file_wait(filp, lock);
1642 out_free:
1643 locks_free_lock(lock);
1645 out_putf:
1646 fput(filp);
1647 out:
1648 return error;
1652 * vfs_test_lock - test file byte range lock
1653 * @filp: The file to test lock for
1654 * @fl: The lock to test; also used to hold result
1656 * Returns -ERRNO on failure. Indicates presence of conflicting lock by
1657 * setting conf->fl_type to something other than F_UNLCK.
1659 int vfs_test_lock(struct file *filp, struct file_lock *fl)
1661 if (filp->f_op && filp->f_op->lock)
1662 return filp->f_op->lock(filp, F_GETLK, fl);
1663 posix_test_lock(filp, fl);
1664 return 0;
1666 EXPORT_SYMBOL_GPL(vfs_test_lock);
1668 static int posix_lock_to_flock(struct flock *flock, struct file_lock *fl)
1670 flock->l_pid = fl->fl_pid;
1671 #if BITS_PER_LONG == 32
1673 * Make sure we can represent the posix lock via
1674 * legacy 32bit flock.
1676 if (fl->fl_start > OFFT_OFFSET_MAX)
1677 return -EOVERFLOW;
1678 if (fl->fl_end != OFFSET_MAX && fl->fl_end > OFFT_OFFSET_MAX)
1679 return -EOVERFLOW;
1680 #endif
1681 flock->l_start = fl->fl_start;
1682 flock->l_len = fl->fl_end == OFFSET_MAX ? 0 :
1683 fl->fl_end - fl->fl_start + 1;
1684 flock->l_whence = 0;
1685 flock->l_type = fl->fl_type;
1686 return 0;
1689 #if BITS_PER_LONG == 32
1690 static void posix_lock_to_flock64(struct flock64 *flock, struct file_lock *fl)
1692 flock->l_pid = fl->fl_pid;
1693 flock->l_start = fl->fl_start;
1694 flock->l_len = fl->fl_end == OFFSET_MAX ? 0 :
1695 fl->fl_end - fl->fl_start + 1;
1696 flock->l_whence = 0;
1697 flock->l_type = fl->fl_type;
1699 #endif
1701 /* Report the first existing lock that would conflict with l.
1702 * This implements the F_GETLK command of fcntl().
1704 int fcntl_getlk(struct file *filp, struct flock __user *l)
1706 struct file_lock file_lock;
1707 struct flock flock;
1708 int error;
1710 error = -EFAULT;
1711 if (copy_from_user(&flock, l, sizeof(flock)))
1712 goto out;
1713 error = -EINVAL;
1714 if ((flock.l_type != F_RDLCK) && (flock.l_type != F_WRLCK))
1715 goto out;
1717 error = flock_to_posix_lock(filp, &file_lock, &flock);
1718 if (error)
1719 goto out;
1721 error = vfs_test_lock(filp, &file_lock);
1722 if (error)
1723 goto out;
1725 flock.l_type = file_lock.fl_type;
1726 if (file_lock.fl_type != F_UNLCK) {
1727 error = posix_lock_to_flock(&flock, &file_lock);
1728 if (error)
1729 goto out;
1731 error = -EFAULT;
1732 if (!copy_to_user(l, &flock, sizeof(flock)))
1733 error = 0;
1734 out:
1735 return error;
1739 * vfs_lock_file - file byte range lock
1740 * @filp: The file to apply the lock to
1741 * @cmd: type of locking operation (F_SETLK, F_GETLK, etc.)
1742 * @fl: The lock to be applied
1743 * @conf: Place to return a copy of the conflicting lock, if found.
1745 * A caller that doesn't care about the conflicting lock may pass NULL
1746 * as the final argument.
1748 * If the filesystem defines a private ->lock() method, then @conf will
1749 * be left unchanged; so a caller that cares should initialize it to
1750 * some acceptable default.
1752 * To avoid blocking kernel daemons, such as lockd, that need to acquire POSIX
1753 * locks, the ->lock() interface may return asynchronously, before the lock has
1754 * been granted or denied by the underlying filesystem, if (and only if)
1755 * fl_grant is set. Callers expecting ->lock() to return asynchronously
1756 * will only use F_SETLK, not F_SETLKW; they will set FL_SLEEP if (and only if)
1757 * the request is for a blocking lock. When ->lock() does return asynchronously,
1758 * it must return FILE_LOCK_DEFERRED, and call ->fl_grant() when the lock
1759 * request completes.
1760 * If the request is for non-blocking lock the file system should return
1761 * FILE_LOCK_DEFERRED then try to get the lock and call the callback routine
1762 * with the result. If the request timed out the callback routine will return a
1763 * nonzero return code and the file system should release the lock. The file
1764 * system is also responsible to keep a corresponding posix lock when it
1765 * grants a lock so the VFS can find out which locks are locally held and do
1766 * the correct lock cleanup when required.
1767 * The underlying filesystem must not drop the kernel lock or call
1768 * ->fl_grant() before returning to the caller with a FILE_LOCK_DEFERRED
1769 * return code.
1771 int vfs_lock_file(struct file *filp, unsigned int cmd, struct file_lock *fl, struct file_lock *conf)
1773 if (filp->f_op && filp->f_op->lock)
1774 return filp->f_op->lock(filp, cmd, fl);
1775 else
1776 return posix_lock_file(filp, fl, conf);
1778 EXPORT_SYMBOL_GPL(vfs_lock_file);
1780 static int do_lock_file_wait(struct file *filp, unsigned int cmd,
1781 struct file_lock *fl)
1783 int error;
1785 error = security_file_lock(filp, fl->fl_type);
1786 if (error)
1787 return error;
1789 for (;;) {
1790 error = vfs_lock_file(filp, cmd, fl, NULL);
1791 if (error != FILE_LOCK_DEFERRED)
1792 break;
1793 error = wait_event_interruptible(fl->fl_wait, !fl->fl_next);
1794 if (!error)
1795 continue;
1797 locks_delete_block(fl);
1798 break;
1801 return error;
1804 /* Apply the lock described by l to an open file descriptor.
1805 * This implements both the F_SETLK and F_SETLKW commands of fcntl().
1807 int fcntl_setlk(unsigned int fd, struct file *filp, unsigned int cmd,
1808 struct flock __user *l)
1810 struct file_lock *file_lock = locks_alloc_lock();
1811 struct flock flock;
1812 struct inode *inode;
1813 struct file *f;
1814 int error;
1816 if (file_lock == NULL)
1817 return -ENOLCK;
1820 * This might block, so we do it before checking the inode.
1822 error = -EFAULT;
1823 if (copy_from_user(&flock, l, sizeof(flock)))
1824 goto out;
1826 inode = filp->f_path.dentry->d_inode;
1828 /* Don't allow mandatory locks on files that may be memory mapped
1829 * and shared.
1831 if (mandatory_lock(inode) && mapping_writably_mapped(filp->f_mapping)) {
1832 error = -EAGAIN;
1833 goto out;
1836 again:
1837 error = flock_to_posix_lock(filp, file_lock, &flock);
1838 if (error)
1839 goto out;
1840 if (cmd == F_SETLKW) {
1841 file_lock->fl_flags |= FL_SLEEP;
1844 error = -EBADF;
1845 switch (flock.l_type) {
1846 case F_RDLCK:
1847 if (!(filp->f_mode & FMODE_READ))
1848 goto out;
1849 break;
1850 case F_WRLCK:
1851 if (!(filp->f_mode & FMODE_WRITE))
1852 goto out;
1853 break;
1854 case F_UNLCK:
1855 break;
1856 default:
1857 error = -EINVAL;
1858 goto out;
1861 error = do_lock_file_wait(filp, cmd, file_lock);
1864 * Attempt to detect a close/fcntl race and recover by
1865 * releasing the lock that was just acquired.
1868 * we need that spin_lock here - it prevents reordering between
1869 * update of inode->i_flock and check for it done in close().
1870 * rcu_read_lock() wouldn't do.
1872 spin_lock(&current->files->file_lock);
1873 f = fcheck(fd);
1874 spin_unlock(&current->files->file_lock);
1875 if (!error && f != filp && flock.l_type != F_UNLCK) {
1876 flock.l_type = F_UNLCK;
1877 goto again;
1880 out:
1881 locks_free_lock(file_lock);
1882 return error;
1885 #if BITS_PER_LONG == 32
1886 /* Report the first existing lock that would conflict with l.
1887 * This implements the F_GETLK command of fcntl().
1889 int fcntl_getlk64(struct file *filp, struct flock64 __user *l)
1891 struct file_lock file_lock;
1892 struct flock64 flock;
1893 int error;
1895 error = -EFAULT;
1896 if (copy_from_user(&flock, l, sizeof(flock)))
1897 goto out;
1898 error = -EINVAL;
1899 if ((flock.l_type != F_RDLCK) && (flock.l_type != F_WRLCK))
1900 goto out;
1902 error = flock64_to_posix_lock(filp, &file_lock, &flock);
1903 if (error)
1904 goto out;
1906 error = vfs_test_lock(filp, &file_lock);
1907 if (error)
1908 goto out;
1910 flock.l_type = file_lock.fl_type;
1911 if (file_lock.fl_type != F_UNLCK)
1912 posix_lock_to_flock64(&flock, &file_lock);
1914 error = -EFAULT;
1915 if (!copy_to_user(l, &flock, sizeof(flock)))
1916 error = 0;
1918 out:
1919 return error;
1922 /* Apply the lock described by l to an open file descriptor.
1923 * This implements both the F_SETLK and F_SETLKW commands of fcntl().
1925 int fcntl_setlk64(unsigned int fd, struct file *filp, unsigned int cmd,
1926 struct flock64 __user *l)
1928 struct file_lock *file_lock = locks_alloc_lock();
1929 struct flock64 flock;
1930 struct inode *inode;
1931 struct file *f;
1932 int error;
1934 if (file_lock == NULL)
1935 return -ENOLCK;
1938 * This might block, so we do it before checking the inode.
1940 error = -EFAULT;
1941 if (copy_from_user(&flock, l, sizeof(flock)))
1942 goto out;
1944 inode = filp->f_path.dentry->d_inode;
1946 /* Don't allow mandatory locks on files that may be memory mapped
1947 * and shared.
1949 if (mandatory_lock(inode) && mapping_writably_mapped(filp->f_mapping)) {
1950 error = -EAGAIN;
1951 goto out;
1954 again:
1955 error = flock64_to_posix_lock(filp, file_lock, &flock);
1956 if (error)
1957 goto out;
1958 if (cmd == F_SETLKW64) {
1959 file_lock->fl_flags |= FL_SLEEP;
1962 error = -EBADF;
1963 switch (flock.l_type) {
1964 case F_RDLCK:
1965 if (!(filp->f_mode & FMODE_READ))
1966 goto out;
1967 break;
1968 case F_WRLCK:
1969 if (!(filp->f_mode & FMODE_WRITE))
1970 goto out;
1971 break;
1972 case F_UNLCK:
1973 break;
1974 default:
1975 error = -EINVAL;
1976 goto out;
1979 error = do_lock_file_wait(filp, cmd, file_lock);
1982 * Attempt to detect a close/fcntl race and recover by
1983 * releasing the lock that was just acquired.
1985 spin_lock(&current->files->file_lock);
1986 f = fcheck(fd);
1987 spin_unlock(&current->files->file_lock);
1988 if (!error && f != filp && flock.l_type != F_UNLCK) {
1989 flock.l_type = F_UNLCK;
1990 goto again;
1993 out:
1994 locks_free_lock(file_lock);
1995 return error;
1997 #endif /* BITS_PER_LONG == 32 */
2000 * This function is called when the file is being removed
2001 * from the task's fd array. POSIX locks belonging to this task
2002 * are deleted at this time.
2004 void locks_remove_posix(struct file *filp, fl_owner_t owner)
2006 struct file_lock lock;
2009 * If there are no locks held on this file, we don't need to call
2010 * posix_lock_file(). Another process could be setting a lock on this
2011 * file at the same time, but we wouldn't remove that lock anyway.
2013 if (!filp->f_path.dentry->d_inode->i_flock)
2014 return;
2016 lock.fl_type = F_UNLCK;
2017 lock.fl_flags = FL_POSIX | FL_CLOSE;
2018 lock.fl_start = 0;
2019 lock.fl_end = OFFSET_MAX;
2020 lock.fl_owner = owner;
2021 lock.fl_pid = current->tgid;
2022 lock.fl_file = filp;
2023 lock.fl_ops = NULL;
2024 lock.fl_lmops = NULL;
2026 vfs_lock_file(filp, F_SETLK, &lock, NULL);
2028 if (lock.fl_ops && lock.fl_ops->fl_release_private)
2029 lock.fl_ops->fl_release_private(&lock);
2032 EXPORT_SYMBOL(locks_remove_posix);
2035 * This function is called on the last close of an open file.
2037 void locks_remove_flock(struct file *filp)
2039 struct inode * inode = filp->f_path.dentry->d_inode;
2040 struct file_lock *fl;
2041 struct file_lock **before;
2043 if (!inode->i_flock)
2044 return;
2046 if (filp->f_op && filp->f_op->flock) {
2047 struct file_lock fl = {
2048 .fl_pid = current->tgid,
2049 .fl_file = filp,
2050 .fl_flags = FL_FLOCK,
2051 .fl_type = F_UNLCK,
2052 .fl_end = OFFSET_MAX,
2054 filp->f_op->flock(filp, F_SETLKW, &fl);
2055 if (fl.fl_ops && fl.fl_ops->fl_release_private)
2056 fl.fl_ops->fl_release_private(&fl);
2059 lock_flocks();
2060 before = &inode->i_flock;
2062 while ((fl = *before) != NULL) {
2063 if (fl->fl_file == filp) {
2064 if (IS_FLOCK(fl)) {
2065 locks_delete_lock(before);
2066 continue;
2068 if (IS_LEASE(fl)) {
2069 lease_modify(before, F_UNLCK);
2070 continue;
2072 /* What? */
2073 BUG();
2075 before = &fl->fl_next;
2077 unlock_flocks();
2081 * posix_unblock_lock - stop waiting for a file lock
2082 * @filp: how the file was opened
2083 * @waiter: the lock which was waiting
2085 * lockd needs to block waiting for locks.
2088 posix_unblock_lock(struct file *filp, struct file_lock *waiter)
2090 int status = 0;
2092 lock_flocks();
2093 if (waiter->fl_next)
2094 __locks_delete_block(waiter);
2095 else
2096 status = -ENOENT;
2097 unlock_flocks();
2098 return status;
2101 EXPORT_SYMBOL(posix_unblock_lock);
2104 * vfs_cancel_lock - file byte range unblock lock
2105 * @filp: The file to apply the unblock to
2106 * @fl: The lock to be unblocked
2108 * Used by lock managers to cancel blocked requests
2110 int vfs_cancel_lock(struct file *filp, struct file_lock *fl)
2112 if (filp->f_op && filp->f_op->lock)
2113 return filp->f_op->lock(filp, F_CANCELLK, fl);
2114 return 0;
2117 EXPORT_SYMBOL_GPL(vfs_cancel_lock);
2119 #ifdef CONFIG_PROC_FS
2120 #include <linux/proc_fs.h>
2121 #include <linux/seq_file.h>
2123 static void lock_get_status(struct seq_file *f, struct file_lock *fl,
2124 loff_t id, char *pfx)
2126 struct inode *inode = NULL;
2127 unsigned int fl_pid;
2129 if (fl->fl_nspid)
2130 fl_pid = pid_vnr(fl->fl_nspid);
2131 else
2132 fl_pid = fl->fl_pid;
2134 if (fl->fl_file != NULL)
2135 inode = fl->fl_file->f_path.dentry->d_inode;
2137 seq_printf(f, "%lld:%s ", id, pfx);
2138 if (IS_POSIX(fl)) {
2139 seq_printf(f, "%6s %s ",
2140 (fl->fl_flags & FL_ACCESS) ? "ACCESS" : "POSIX ",
2141 (inode == NULL) ? "*NOINODE*" :
2142 mandatory_lock(inode) ? "MANDATORY" : "ADVISORY ");
2143 } else if (IS_FLOCK(fl)) {
2144 if (fl->fl_type & LOCK_MAND) {
2145 seq_printf(f, "FLOCK MSNFS ");
2146 } else {
2147 seq_printf(f, "FLOCK ADVISORY ");
2149 } else if (IS_LEASE(fl)) {
2150 seq_printf(f, "LEASE ");
2151 if (fl->fl_type & F_INPROGRESS)
2152 seq_printf(f, "BREAKING ");
2153 else if (fl->fl_file)
2154 seq_printf(f, "ACTIVE ");
2155 else
2156 seq_printf(f, "BREAKER ");
2157 } else {
2158 seq_printf(f, "UNKNOWN UNKNOWN ");
2160 if (fl->fl_type & LOCK_MAND) {
2161 seq_printf(f, "%s ",
2162 (fl->fl_type & LOCK_READ)
2163 ? (fl->fl_type & LOCK_WRITE) ? "RW " : "READ "
2164 : (fl->fl_type & LOCK_WRITE) ? "WRITE" : "NONE ");
2165 } else {
2166 seq_printf(f, "%s ",
2167 (fl->fl_type & F_INPROGRESS)
2168 ? (fl->fl_type & F_UNLCK) ? "UNLCK" : "READ "
2169 : (fl->fl_type & F_WRLCK) ? "WRITE" : "READ ");
2171 if (inode) {
2172 #ifdef WE_CAN_BREAK_LSLK_NOW
2173 seq_printf(f, "%d %s:%ld ", fl_pid,
2174 inode->i_sb->s_id, inode->i_ino);
2175 #else
2176 /* userspace relies on this representation of dev_t ;-( */
2177 seq_printf(f, "%d %02x:%02x:%ld ", fl_pid,
2178 MAJOR(inode->i_sb->s_dev),
2179 MINOR(inode->i_sb->s_dev), inode->i_ino);
2180 #endif
2181 } else {
2182 seq_printf(f, "%d <none>:0 ", fl_pid);
2184 if (IS_POSIX(fl)) {
2185 if (fl->fl_end == OFFSET_MAX)
2186 seq_printf(f, "%Ld EOF\n", fl->fl_start);
2187 else
2188 seq_printf(f, "%Ld %Ld\n", fl->fl_start, fl->fl_end);
2189 } else {
2190 seq_printf(f, "0 EOF\n");
2194 static int locks_show(struct seq_file *f, void *v)
2196 struct file_lock *fl, *bfl;
2198 fl = list_entry(v, struct file_lock, fl_link);
2200 lock_get_status(f, fl, *((loff_t *)f->private), "");
2202 list_for_each_entry(bfl, &fl->fl_block, fl_block)
2203 lock_get_status(f, bfl, *((loff_t *)f->private), " ->");
2205 return 0;
2208 static void *locks_start(struct seq_file *f, loff_t *pos)
2210 loff_t *p = f->private;
2212 lock_flocks();
2213 *p = (*pos + 1);
2214 return seq_list_start(&file_lock_list, *pos);
2217 static void *locks_next(struct seq_file *f, void *v, loff_t *pos)
2219 loff_t *p = f->private;
2220 ++*p;
2221 return seq_list_next(v, &file_lock_list, pos);
2224 static void locks_stop(struct seq_file *f, void *v)
2226 unlock_flocks();
2229 static const struct seq_operations locks_seq_operations = {
2230 .start = locks_start,
2231 .next = locks_next,
2232 .stop = locks_stop,
2233 .show = locks_show,
2236 static int locks_open(struct inode *inode, struct file *filp)
2238 return seq_open_private(filp, &locks_seq_operations, sizeof(loff_t));
2241 static const struct file_operations proc_locks_operations = {
2242 .open = locks_open,
2243 .read = seq_read,
2244 .llseek = seq_lseek,
2245 .release = seq_release_private,
2248 static int __init proc_locks_init(void)
2250 proc_create("locks", 0, NULL, &proc_locks_operations);
2251 return 0;
2253 module_init(proc_locks_init);
2254 #endif
2257 * lock_may_read - checks that the region is free of locks
2258 * @inode: the inode that is being read
2259 * @start: the first byte to read
2260 * @len: the number of bytes to read
2262 * Emulates Windows locking requirements. Whole-file
2263 * mandatory locks (share modes) can prohibit a read and
2264 * byte-range POSIX locks can prohibit a read if they overlap.
2266 * N.B. this function is only ever called
2267 * from knfsd and ownership of locks is never checked.
2269 int lock_may_read(struct inode *inode, loff_t start, unsigned long len)
2271 struct file_lock *fl;
2272 int result = 1;
2273 lock_flocks();
2274 for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) {
2275 if (IS_POSIX(fl)) {
2276 if (fl->fl_type == F_RDLCK)
2277 continue;
2278 if ((fl->fl_end < start) || (fl->fl_start > (start + len)))
2279 continue;
2280 } else if (IS_FLOCK(fl)) {
2281 if (!(fl->fl_type & LOCK_MAND))
2282 continue;
2283 if (fl->fl_type & LOCK_READ)
2284 continue;
2285 } else
2286 continue;
2287 result = 0;
2288 break;
2290 unlock_flocks();
2291 return result;
2294 EXPORT_SYMBOL(lock_may_read);
2297 * lock_may_write - checks that the region is free of locks
2298 * @inode: the inode that is being written
2299 * @start: the first byte to write
2300 * @len: the number of bytes to write
2302 * Emulates Windows locking requirements. Whole-file
2303 * mandatory locks (share modes) can prohibit a write and
2304 * byte-range POSIX locks can prohibit a write if they overlap.
2306 * N.B. this function is only ever called
2307 * from knfsd and ownership of locks is never checked.
2309 int lock_may_write(struct inode *inode, loff_t start, unsigned long len)
2311 struct file_lock *fl;
2312 int result = 1;
2313 lock_flocks();
2314 for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) {
2315 if (IS_POSIX(fl)) {
2316 if ((fl->fl_end < start) || (fl->fl_start > (start + len)))
2317 continue;
2318 } else if (IS_FLOCK(fl)) {
2319 if (!(fl->fl_type & LOCK_MAND))
2320 continue;
2321 if (fl->fl_type & LOCK_WRITE)
2322 continue;
2323 } else
2324 continue;
2325 result = 0;
2326 break;
2328 unlock_flocks();
2329 return result;
2332 EXPORT_SYMBOL(lock_may_write);
2334 static int __init filelock_init(void)
2336 filelock_cache = kmem_cache_create("file_lock_cache",
2337 sizeof(struct file_lock), 0, SLAB_PANIC,
2338 init_once);
2339 return 0;
2342 core_initcall(filelock_init);