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
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/filesystems/mandatory-locking.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
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
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>
129 #include <linux/hashtable.h>
130 #include <linux/percpu.h>
131 #include <linux/lglock.h>
133 #define CREATE_TRACE_POINTS
134 #include <trace/events/filelock.h>
136 #include <asm/uaccess.h>
138 #define IS_POSIX(fl) (fl->fl_flags & FL_POSIX)
139 #define IS_FLOCK(fl) (fl->fl_flags & FL_FLOCK)
140 #define IS_LEASE(fl) (fl->fl_flags & (FL_LEASE|FL_DELEG))
141 #define IS_OFDLCK(fl) (fl->fl_flags & FL_OFDLCK)
143 static bool lease_breaking(struct file_lock *fl)
145 return fl->fl_flags & (FL_UNLOCK_PENDING | FL_DOWNGRADE_PENDING);
148 static int target_leasetype(struct file_lock *fl)
150 if (fl->fl_flags & FL_UNLOCK_PENDING)
152 if (fl->fl_flags & FL_DOWNGRADE_PENDING)
157 int leases_enable = 1;
158 int lease_break_time = 45;
160 #define for_each_lock(inode, lockp) \
161 for (lockp = &inode->i_flock; *lockp != NULL; lockp = &(*lockp)->fl_next)
164 * The global file_lock_list is only used for displaying /proc/locks, so we
165 * keep a list on each CPU, with each list protected by its own spinlock via
166 * the file_lock_lglock. Note that alterations to the list also require that
167 * the relevant i_lock is held.
169 DEFINE_STATIC_LGLOCK(file_lock_lglock);
170 static DEFINE_PER_CPU(struct hlist_head, file_lock_list);
173 * The blocked_hash is used to find POSIX lock loops for deadlock detection.
174 * It is protected by blocked_lock_lock.
176 * We hash locks by lockowner in order to optimize searching for the lock a
177 * particular lockowner is waiting on.
179 * FIXME: make this value scale via some heuristic? We generally will want more
180 * buckets when we have more lockowners holding locks, but that's a little
181 * difficult to determine without knowing what the workload will look like.
183 #define BLOCKED_HASH_BITS 7
184 static DEFINE_HASHTABLE(blocked_hash, BLOCKED_HASH_BITS);
187 * This lock protects the blocked_hash. Generally, if you're accessing it, you
188 * want to be holding this lock.
190 * In addition, it also protects the fl->fl_block list, and the fl->fl_next
191 * pointer for file_lock structures that are acting as lock requests (in
192 * contrast to those that are acting as records of acquired locks).
194 * Note that when we acquire this lock in order to change the above fields,
195 * we often hold the i_lock as well. In certain cases, when reading the fields
196 * protected by this lock, we can skip acquiring it iff we already hold the
199 * In particular, adding an entry to the fl_block list requires that you hold
200 * both the i_lock and the blocked_lock_lock (acquired in that order). Deleting
201 * an entry from the list however only requires the file_lock_lock.
203 static DEFINE_SPINLOCK(blocked_lock_lock);
205 static struct kmem_cache *flctx_cache __read_mostly;
206 static struct kmem_cache *filelock_cache __read_mostly;
208 static struct file_lock_context *
209 locks_get_lock_context(struct inode *inode)
211 struct file_lock_context *new;
213 if (likely(inode->i_flctx))
216 new = kmem_cache_alloc(flctx_cache, GFP_KERNEL);
220 INIT_LIST_HEAD(&new->flc_flock);
223 * Assign the pointer if it's not already assigned. If it is, then
224 * free the context we just allocated.
226 spin_lock(&inode->i_lock);
227 if (likely(!inode->i_flctx)) {
228 inode->i_flctx = new;
231 spin_unlock(&inode->i_lock);
234 kmem_cache_free(flctx_cache, new);
236 return inode->i_flctx;
240 locks_free_lock_context(struct file_lock_context *ctx)
243 WARN_ON_ONCE(!list_empty(&ctx->flc_flock));
244 kmem_cache_free(flctx_cache, ctx);
248 static void locks_init_lock_heads(struct file_lock *fl)
250 INIT_HLIST_NODE(&fl->fl_link);
251 INIT_LIST_HEAD(&fl->fl_list);
252 INIT_LIST_HEAD(&fl->fl_block);
253 init_waitqueue_head(&fl->fl_wait);
256 /* Allocate an empty lock structure. */
257 struct file_lock *locks_alloc_lock(void)
259 struct file_lock *fl = kmem_cache_zalloc(filelock_cache, GFP_KERNEL);
262 locks_init_lock_heads(fl);
266 EXPORT_SYMBOL_GPL(locks_alloc_lock);
268 void locks_release_private(struct file_lock *fl)
271 if (fl->fl_ops->fl_release_private)
272 fl->fl_ops->fl_release_private(fl);
277 if (fl->fl_lmops->lm_put_owner)
278 fl->fl_lmops->lm_put_owner(fl);
282 EXPORT_SYMBOL_GPL(locks_release_private);
284 /* Free a lock which is not in use. */
285 void locks_free_lock(struct file_lock *fl)
287 BUG_ON(waitqueue_active(&fl->fl_wait));
288 BUG_ON(!list_empty(&fl->fl_list));
289 BUG_ON(!list_empty(&fl->fl_block));
290 BUG_ON(!hlist_unhashed(&fl->fl_link));
292 locks_release_private(fl);
293 kmem_cache_free(filelock_cache, fl);
295 EXPORT_SYMBOL(locks_free_lock);
298 locks_dispose_list(struct list_head *dispose)
300 struct file_lock *fl;
302 while (!list_empty(dispose)) {
303 fl = list_first_entry(dispose, struct file_lock, fl_list);
304 list_del_init(&fl->fl_list);
309 void locks_init_lock(struct file_lock *fl)
311 memset(fl, 0, sizeof(struct file_lock));
312 locks_init_lock_heads(fl);
315 EXPORT_SYMBOL(locks_init_lock);
318 * Initialize a new lock from an existing file_lock structure.
320 void locks_copy_conflock(struct file_lock *new, struct file_lock *fl)
322 new->fl_owner = fl->fl_owner;
323 new->fl_pid = fl->fl_pid;
325 new->fl_flags = fl->fl_flags;
326 new->fl_type = fl->fl_type;
327 new->fl_start = fl->fl_start;
328 new->fl_end = fl->fl_end;
329 new->fl_lmops = fl->fl_lmops;
333 if (fl->fl_lmops->lm_get_owner)
334 fl->fl_lmops->lm_get_owner(new, fl);
337 EXPORT_SYMBOL(locks_copy_conflock);
339 void locks_copy_lock(struct file_lock *new, struct file_lock *fl)
341 /* "new" must be a freshly-initialized lock */
342 WARN_ON_ONCE(new->fl_ops);
344 locks_copy_conflock(new, fl);
346 new->fl_file = fl->fl_file;
347 new->fl_ops = fl->fl_ops;
350 if (fl->fl_ops->fl_copy_lock)
351 fl->fl_ops->fl_copy_lock(new, fl);
355 EXPORT_SYMBOL(locks_copy_lock);
357 static inline int flock_translate_cmd(int cmd) {
359 return cmd & (LOCK_MAND | LOCK_RW);
371 /* Fill in a file_lock structure with an appropriate FLOCK lock. */
372 static struct file_lock *
373 flock_make_lock(struct file *filp, unsigned int cmd)
375 struct file_lock *fl;
376 int type = flock_translate_cmd(cmd);
379 return ERR_PTR(type);
381 fl = locks_alloc_lock();
383 return ERR_PTR(-ENOMEM);
387 fl->fl_pid = current->tgid;
388 fl->fl_flags = FL_FLOCK;
390 fl->fl_end = OFFSET_MAX;
395 static int assign_type(struct file_lock *fl, long type)
409 static int flock64_to_posix_lock(struct file *filp, struct file_lock *fl,
412 switch (l->l_whence) {
417 fl->fl_start = filp->f_pos;
420 fl->fl_start = i_size_read(file_inode(filp));
425 if (l->l_start > OFFSET_MAX - fl->fl_start)
427 fl->fl_start += l->l_start;
428 if (fl->fl_start < 0)
431 /* POSIX-1996 leaves the case l->l_len < 0 undefined;
432 POSIX-2001 defines it. */
434 if (l->l_len - 1 > OFFSET_MAX - fl->fl_start)
436 fl->fl_end = fl->fl_start + l->l_len - 1;
438 } else if (l->l_len < 0) {
439 if (fl->fl_start + l->l_len < 0)
441 fl->fl_end = fl->fl_start - 1;
442 fl->fl_start += l->l_len;
444 fl->fl_end = OFFSET_MAX;
446 fl->fl_owner = current->files;
447 fl->fl_pid = current->tgid;
449 fl->fl_flags = FL_POSIX;
453 return assign_type(fl, l->l_type);
456 /* Verify a "struct flock" and copy it to a "struct file_lock" as a POSIX
459 static int flock_to_posix_lock(struct file *filp, struct file_lock *fl,
462 struct flock64 ll = {
464 .l_whence = l->l_whence,
465 .l_start = l->l_start,
469 return flock64_to_posix_lock(filp, fl, &ll);
472 /* default lease lock manager operations */
474 lease_break_callback(struct file_lock *fl)
476 kill_fasync(&fl->fl_fasync, SIGIO, POLL_MSG);
481 lease_setup(struct file_lock *fl, void **priv)
483 struct file *filp = fl->fl_file;
484 struct fasync_struct *fa = *priv;
487 * fasync_insert_entry() returns the old entry if any. If there was no
488 * old entry, then it used "priv" and inserted it into the fasync list.
489 * Clear the pointer to indicate that it shouldn't be freed.
491 if (!fasync_insert_entry(fa->fa_fd, filp, &fl->fl_fasync, fa))
494 __f_setown(filp, task_pid(current), PIDTYPE_PID, 0);
497 static const struct lock_manager_operations lease_manager_ops = {
498 .lm_break = lease_break_callback,
499 .lm_change = lease_modify,
500 .lm_setup = lease_setup,
504 * Initialize a lease, use the default lock manager operations
506 static int lease_init(struct file *filp, long type, struct file_lock *fl)
508 if (assign_type(fl, type) != 0)
512 fl->fl_pid = current->tgid;
515 fl->fl_flags = FL_LEASE;
517 fl->fl_end = OFFSET_MAX;
519 fl->fl_lmops = &lease_manager_ops;
523 /* Allocate a file_lock initialised to this type of lease */
524 static struct file_lock *lease_alloc(struct file *filp, long type)
526 struct file_lock *fl = locks_alloc_lock();
530 return ERR_PTR(error);
532 error = lease_init(filp, type, fl);
535 return ERR_PTR(error);
540 /* Check if two locks overlap each other.
542 static inline int locks_overlap(struct file_lock *fl1, struct file_lock *fl2)
544 return ((fl1->fl_end >= fl2->fl_start) &&
545 (fl2->fl_end >= fl1->fl_start));
549 * Check whether two locks have the same owner.
551 static int posix_same_owner(struct file_lock *fl1, struct file_lock *fl2)
553 if (fl1->fl_lmops && fl1->fl_lmops->lm_compare_owner)
554 return fl2->fl_lmops == fl1->fl_lmops &&
555 fl1->fl_lmops->lm_compare_owner(fl1, fl2);
556 return fl1->fl_owner == fl2->fl_owner;
559 /* Must be called with the i_lock held! */
560 static void locks_insert_global_locks(struct file_lock *fl)
562 lg_local_lock(&file_lock_lglock);
563 fl->fl_link_cpu = smp_processor_id();
564 hlist_add_head(&fl->fl_link, this_cpu_ptr(&file_lock_list));
565 lg_local_unlock(&file_lock_lglock);
568 /* Must be called with the i_lock held! */
569 static void locks_delete_global_locks(struct file_lock *fl)
572 * Avoid taking lock if already unhashed. This is safe since this check
573 * is done while holding the i_lock, and new insertions into the list
574 * also require that it be held.
576 if (hlist_unhashed(&fl->fl_link))
578 lg_local_lock_cpu(&file_lock_lglock, fl->fl_link_cpu);
579 hlist_del_init(&fl->fl_link);
580 lg_local_unlock_cpu(&file_lock_lglock, fl->fl_link_cpu);
584 posix_owner_key(struct file_lock *fl)
586 if (fl->fl_lmops && fl->fl_lmops->lm_owner_key)
587 return fl->fl_lmops->lm_owner_key(fl);
588 return (unsigned long)fl->fl_owner;
591 static void locks_insert_global_blocked(struct file_lock *waiter)
593 hash_add(blocked_hash, &waiter->fl_link, posix_owner_key(waiter));
596 static void locks_delete_global_blocked(struct file_lock *waiter)
598 hash_del(&waiter->fl_link);
601 /* Remove waiter from blocker's block list.
602 * When blocker ends up pointing to itself then the list is empty.
604 * Must be called with blocked_lock_lock held.
606 static void __locks_delete_block(struct file_lock *waiter)
608 locks_delete_global_blocked(waiter);
609 list_del_init(&waiter->fl_block);
610 waiter->fl_next = NULL;
613 static void locks_delete_block(struct file_lock *waiter)
615 spin_lock(&blocked_lock_lock);
616 __locks_delete_block(waiter);
617 spin_unlock(&blocked_lock_lock);
620 /* Insert waiter into blocker's block list.
621 * We use a circular list so that processes can be easily woken up in
622 * the order they blocked. The documentation doesn't require this but
623 * it seems like the reasonable thing to do.
625 * Must be called with both the i_lock and blocked_lock_lock held. The fl_block
626 * list itself is protected by the blocked_lock_lock, but by ensuring that the
627 * i_lock is also held on insertions we can avoid taking the blocked_lock_lock
628 * in some cases when we see that the fl_block list is empty.
630 static void __locks_insert_block(struct file_lock *blocker,
631 struct file_lock *waiter)
633 BUG_ON(!list_empty(&waiter->fl_block));
634 waiter->fl_next = blocker;
635 list_add_tail(&waiter->fl_block, &blocker->fl_block);
636 if (IS_POSIX(blocker) && !IS_OFDLCK(blocker))
637 locks_insert_global_blocked(waiter);
640 /* Must be called with i_lock held. */
641 static void locks_insert_block(struct file_lock *blocker,
642 struct file_lock *waiter)
644 spin_lock(&blocked_lock_lock);
645 __locks_insert_block(blocker, waiter);
646 spin_unlock(&blocked_lock_lock);
650 * Wake up processes blocked waiting for blocker.
652 * Must be called with the inode->i_lock held!
654 static void locks_wake_up_blocks(struct file_lock *blocker)
657 * Avoid taking global lock if list is empty. This is safe since new
658 * blocked requests are only added to the list under the i_lock, and
659 * the i_lock is always held here. Note that removal from the fl_block
660 * list does not require the i_lock, so we must recheck list_empty()
661 * after acquiring the blocked_lock_lock.
663 if (list_empty(&blocker->fl_block))
666 spin_lock(&blocked_lock_lock);
667 while (!list_empty(&blocker->fl_block)) {
668 struct file_lock *waiter;
670 waiter = list_first_entry(&blocker->fl_block,
671 struct file_lock, fl_block);
672 __locks_delete_block(waiter);
673 if (waiter->fl_lmops && waiter->fl_lmops->lm_notify)
674 waiter->fl_lmops->lm_notify(waiter);
676 wake_up(&waiter->fl_wait);
678 spin_unlock(&blocked_lock_lock);
681 /* Insert file lock fl into an inode's lock list at the position indicated
682 * by pos. At the same time add the lock to the global file lock list.
684 * Must be called with the i_lock held!
686 static void locks_insert_lock(struct file_lock **pos, struct file_lock *fl)
688 fl->fl_nspid = get_pid(task_tgid(current));
690 /* insert into file's list */
694 locks_insert_global_locks(fl);
698 * locks_delete_lock - Delete a lock and then free it.
699 * @thisfl_p: pointer that points to the fl_next field of the previous
700 * inode->i_flock list entry
702 * Unlink a lock from all lists and free the namespace reference, but don't
703 * free it yet. Wake up processes that are blocked waiting for this lock and
704 * notify the FS that the lock has been cleared.
706 * Must be called with the i_lock held!
708 static void locks_unlink_lock(struct file_lock **thisfl_p)
710 struct file_lock *fl = *thisfl_p;
712 locks_delete_global_locks(fl);
714 *thisfl_p = fl->fl_next;
718 put_pid(fl->fl_nspid);
722 locks_wake_up_blocks(fl);
726 * Unlink a lock from all lists and free it.
728 * Must be called with i_lock held!
730 static void locks_delete_lock(struct file_lock **thisfl_p,
731 struct list_head *dispose)
733 struct file_lock *fl = *thisfl_p;
735 locks_unlink_lock(thisfl_p);
737 list_add(&fl->fl_list, dispose);
742 /* Determine if lock sys_fl blocks lock caller_fl. Common functionality
743 * checks for shared/exclusive status of overlapping locks.
745 static int locks_conflict(struct file_lock *caller_fl, struct file_lock *sys_fl)
747 if (sys_fl->fl_type == F_WRLCK)
749 if (caller_fl->fl_type == F_WRLCK)
754 /* Determine if lock sys_fl blocks lock caller_fl. POSIX specific
755 * checking before calling the locks_conflict().
757 static int posix_locks_conflict(struct file_lock *caller_fl, struct file_lock *sys_fl)
759 /* POSIX locks owned by the same process do not conflict with
762 if (!IS_POSIX(sys_fl) || posix_same_owner(caller_fl, sys_fl))
765 /* Check whether they overlap */
766 if (!locks_overlap(caller_fl, sys_fl))
769 return (locks_conflict(caller_fl, sys_fl));
772 /* Determine if lock sys_fl blocks lock caller_fl. FLOCK specific
773 * checking before calling the locks_conflict().
775 static int flock_locks_conflict(struct file_lock *caller_fl, struct file_lock *sys_fl)
777 /* FLOCK locks referring to the same filp do not conflict with
780 if (!IS_FLOCK(sys_fl) || (caller_fl->fl_file == sys_fl->fl_file))
782 if ((caller_fl->fl_type & LOCK_MAND) || (sys_fl->fl_type & LOCK_MAND))
785 return (locks_conflict(caller_fl, sys_fl));
789 posix_test_lock(struct file *filp, struct file_lock *fl)
791 struct file_lock *cfl;
792 struct inode *inode = file_inode(filp);
794 spin_lock(&inode->i_lock);
795 for (cfl = file_inode(filp)->i_flock; cfl; cfl = cfl->fl_next) {
798 if (posix_locks_conflict(fl, cfl))
802 locks_copy_conflock(fl, cfl);
804 fl->fl_pid = pid_vnr(cfl->fl_nspid);
806 fl->fl_type = F_UNLCK;
807 spin_unlock(&inode->i_lock);
810 EXPORT_SYMBOL(posix_test_lock);
813 * Deadlock detection:
815 * We attempt to detect deadlocks that are due purely to posix file
818 * We assume that a task can be waiting for at most one lock at a time.
819 * So for any acquired lock, the process holding that lock may be
820 * waiting on at most one other lock. That lock in turns may be held by
821 * someone waiting for at most one other lock. Given a requested lock
822 * caller_fl which is about to wait for a conflicting lock block_fl, we
823 * follow this chain of waiters to ensure we are not about to create a
826 * Since we do this before we ever put a process to sleep on a lock, we
827 * are ensured that there is never a cycle; that is what guarantees that
828 * the while() loop in posix_locks_deadlock() eventually completes.
830 * Note: the above assumption may not be true when handling lock
831 * requests from a broken NFS client. It may also fail in the presence
832 * of tasks (such as posix threads) sharing the same open file table.
833 * To handle those cases, we just bail out after a few iterations.
835 * For FL_OFDLCK locks, the owner is the filp, not the files_struct.
836 * Because the owner is not even nominally tied to a thread of
837 * execution, the deadlock detection below can't reasonably work well. Just
840 * In principle, we could do a more limited deadlock detection on FL_OFDLCK
841 * locks that just checks for the case where two tasks are attempting to
842 * upgrade from read to write locks on the same inode.
845 #define MAX_DEADLK_ITERATIONS 10
847 /* Find a lock that the owner of the given block_fl is blocking on. */
848 static struct file_lock *what_owner_is_waiting_for(struct file_lock *block_fl)
850 struct file_lock *fl;
852 hash_for_each_possible(blocked_hash, fl, fl_link, posix_owner_key(block_fl)) {
853 if (posix_same_owner(fl, block_fl))
859 /* Must be called with the blocked_lock_lock held! */
860 static int posix_locks_deadlock(struct file_lock *caller_fl,
861 struct file_lock *block_fl)
866 * This deadlock detector can't reasonably detect deadlocks with
867 * FL_OFDLCK locks, since they aren't owned by a process, per-se.
869 if (IS_OFDLCK(caller_fl))
872 while ((block_fl = what_owner_is_waiting_for(block_fl))) {
873 if (i++ > MAX_DEADLK_ITERATIONS)
875 if (posix_same_owner(caller_fl, block_fl))
881 /* Try to create a FLOCK lock on filp. We always insert new FLOCK locks
882 * after any leases, but before any posix locks.
884 * Note that if called with an FL_EXISTS argument, the caller may determine
885 * whether or not a lock was successfully freed by testing the return
888 static int flock_lock_file(struct file *filp, struct file_lock *request)
890 struct file_lock *new_fl = NULL;
891 struct file_lock **before;
892 struct inode * inode = file_inode(filp);
897 if (!(request->fl_flags & FL_ACCESS) && (request->fl_type != F_UNLCK)) {
898 new_fl = locks_alloc_lock();
903 spin_lock(&inode->i_lock);
904 if (request->fl_flags & FL_ACCESS)
907 for_each_lock(inode, before) {
908 struct file_lock *fl = *before;
913 if (filp != fl->fl_file)
915 if (request->fl_type == fl->fl_type)
918 locks_delete_lock(before, &dispose);
922 if (request->fl_type == F_UNLCK) {
923 if ((request->fl_flags & FL_EXISTS) && !found)
929 * If a higher-priority process was blocked on the old file lock,
930 * give it the opportunity to lock the file.
933 spin_unlock(&inode->i_lock);
935 spin_lock(&inode->i_lock);
939 for_each_lock(inode, before) {
940 struct file_lock *fl = *before;
945 if (!flock_locks_conflict(request, fl))
948 if (!(request->fl_flags & FL_SLEEP))
950 error = FILE_LOCK_DEFERRED;
951 locks_insert_block(fl, request);
954 if (request->fl_flags & FL_ACCESS)
956 locks_copy_lock(new_fl, request);
957 locks_insert_lock(before, new_fl);
962 spin_unlock(&inode->i_lock);
964 locks_free_lock(new_fl);
965 locks_dispose_list(&dispose);
969 static int __posix_lock_file(struct inode *inode, struct file_lock *request, struct file_lock *conflock)
971 struct file_lock *fl;
972 struct file_lock *new_fl = NULL;
973 struct file_lock *new_fl2 = NULL;
974 struct file_lock *left = NULL;
975 struct file_lock *right = NULL;
976 struct file_lock **before;
982 * We may need two file_lock structures for this operation,
983 * so we get them in advance to avoid races.
985 * In some cases we can be sure, that no new locks will be needed
987 if (!(request->fl_flags & FL_ACCESS) &&
988 (request->fl_type != F_UNLCK ||
989 request->fl_start != 0 || request->fl_end != OFFSET_MAX)) {
990 new_fl = locks_alloc_lock();
991 new_fl2 = locks_alloc_lock();
994 spin_lock(&inode->i_lock);
996 * New lock request. Walk all POSIX locks and look for conflicts. If
997 * there are any, either return error or put the request on the
998 * blocker's list of waiters and the global blocked_hash.
1000 if (request->fl_type != F_UNLCK) {
1001 for_each_lock(inode, before) {
1005 if (!posix_locks_conflict(request, fl))
1008 locks_copy_conflock(conflock, fl);
1010 if (!(request->fl_flags & FL_SLEEP))
1013 * Deadlock detection and insertion into the blocked
1014 * locks list must be done while holding the same lock!
1017 spin_lock(&blocked_lock_lock);
1018 if (likely(!posix_locks_deadlock(request, fl))) {
1019 error = FILE_LOCK_DEFERRED;
1020 __locks_insert_block(fl, request);
1022 spin_unlock(&blocked_lock_lock);
1027 /* If we're just looking for a conflict, we're done. */
1029 if (request->fl_flags & FL_ACCESS)
1033 * Find the first old lock with the same owner as the new lock.
1036 before = &inode->i_flock;
1038 /* First skip locks owned by other processes. */
1039 while ((fl = *before) && (!IS_POSIX(fl) ||
1040 !posix_same_owner(request, fl))) {
1041 before = &fl->fl_next;
1044 /* Process locks with this owner. */
1045 while ((fl = *before) && posix_same_owner(request, fl)) {
1046 /* Detect adjacent or overlapping regions (if same lock type)
1048 if (request->fl_type == fl->fl_type) {
1049 /* In all comparisons of start vs end, use
1050 * "start - 1" rather than "end + 1". If end
1051 * is OFFSET_MAX, end + 1 will become negative.
1053 if (fl->fl_end < request->fl_start - 1)
1055 /* If the next lock in the list has entirely bigger
1056 * addresses than the new one, insert the lock here.
1058 if (fl->fl_start - 1 > request->fl_end)
1061 /* If we come here, the new and old lock are of the
1062 * same type and adjacent or overlapping. Make one
1063 * lock yielding from the lower start address of both
1064 * locks to the higher end address.
1066 if (fl->fl_start > request->fl_start)
1067 fl->fl_start = request->fl_start;
1069 request->fl_start = fl->fl_start;
1070 if (fl->fl_end < request->fl_end)
1071 fl->fl_end = request->fl_end;
1073 request->fl_end = fl->fl_end;
1075 locks_delete_lock(before, &dispose);
1082 /* Processing for different lock types is a bit
1085 if (fl->fl_end < request->fl_start)
1087 if (fl->fl_start > request->fl_end)
1089 if (request->fl_type == F_UNLCK)
1091 if (fl->fl_start < request->fl_start)
1093 /* If the next lock in the list has a higher end
1094 * address than the new one, insert the new one here.
1096 if (fl->fl_end > request->fl_end) {
1100 if (fl->fl_start >= request->fl_start) {
1101 /* The new lock completely replaces an old
1102 * one (This may happen several times).
1105 locks_delete_lock(before, &dispose);
1109 * Replace the old lock with new_fl, and
1110 * remove the old one. It's safe to do the
1111 * insert here since we know that we won't be
1112 * using new_fl later, and that the lock is
1113 * just replacing an existing lock.
1118 locks_copy_lock(new_fl, request);
1121 locks_delete_lock(before, &dispose);
1122 locks_insert_lock(before, request);
1126 /* Go on to next lock.
1129 before = &fl->fl_next;
1133 * The above code only modifies existing locks in case of merging or
1134 * replacing. If new lock(s) need to be inserted all modifications are
1135 * done below this, so it's safe yet to bail out.
1137 error = -ENOLCK; /* "no luck" */
1138 if (right && left == right && !new_fl2)
1143 if (request->fl_type == F_UNLCK) {
1144 if (request->fl_flags & FL_EXISTS)
1153 locks_copy_lock(new_fl, request);
1154 locks_insert_lock(before, new_fl);
1158 if (left == right) {
1159 /* The new lock breaks the old one in two pieces,
1160 * so we have to use the second new lock.
1164 locks_copy_lock(left, right);
1165 locks_insert_lock(before, left);
1167 right->fl_start = request->fl_end + 1;
1168 locks_wake_up_blocks(right);
1171 left->fl_end = request->fl_start - 1;
1172 locks_wake_up_blocks(left);
1175 spin_unlock(&inode->i_lock);
1177 * Free any unused locks.
1180 locks_free_lock(new_fl);
1182 locks_free_lock(new_fl2);
1183 locks_dispose_list(&dispose);
1188 * posix_lock_file - Apply a POSIX-style lock to a file
1189 * @filp: The file to apply the lock to
1190 * @fl: The lock to be applied
1191 * @conflock: Place to return a copy of the conflicting lock, if found.
1193 * Add a POSIX style lock to a file.
1194 * We merge adjacent & overlapping locks whenever possible.
1195 * POSIX locks are sorted by owner task, then by starting address
1197 * Note that if called with an FL_EXISTS argument, the caller may determine
1198 * whether or not a lock was successfully freed by testing the return
1199 * value for -ENOENT.
1201 int posix_lock_file(struct file *filp, struct file_lock *fl,
1202 struct file_lock *conflock)
1204 return __posix_lock_file(file_inode(filp), fl, conflock);
1206 EXPORT_SYMBOL(posix_lock_file);
1209 * posix_lock_file_wait - Apply a POSIX-style lock to a file
1210 * @filp: The file to apply the lock to
1211 * @fl: The lock to be applied
1213 * Add a POSIX style lock to a file.
1214 * We merge adjacent & overlapping locks whenever possible.
1215 * POSIX locks are sorted by owner task, then by starting address
1217 int posix_lock_file_wait(struct file *filp, struct file_lock *fl)
1222 error = posix_lock_file(filp, fl, NULL);
1223 if (error != FILE_LOCK_DEFERRED)
1225 error = wait_event_interruptible(fl->fl_wait, !fl->fl_next);
1229 locks_delete_block(fl);
1234 EXPORT_SYMBOL(posix_lock_file_wait);
1237 * locks_mandatory_locked - Check for an active lock
1238 * @file: the file to check
1240 * Searches the inode's list of locks to find any POSIX locks which conflict.
1241 * This function is called from locks_verify_locked() only.
1243 int locks_mandatory_locked(struct file *file)
1245 struct inode *inode = file_inode(file);
1246 struct file_lock *fl;
1249 * Search the lock list for this inode for any POSIX locks.
1251 spin_lock(&inode->i_lock);
1252 for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) {
1255 if (fl->fl_owner != current->files &&
1256 fl->fl_owner != file)
1259 spin_unlock(&inode->i_lock);
1260 return fl ? -EAGAIN : 0;
1264 * locks_mandatory_area - Check for a conflicting lock
1265 * @read_write: %FLOCK_VERIFY_WRITE for exclusive access, %FLOCK_VERIFY_READ
1267 * @inode: the file to check
1268 * @filp: how the file was opened (if it was)
1269 * @offset: start of area to check
1270 * @count: length of area to check
1272 * Searches the inode's list of locks to find any POSIX locks which conflict.
1273 * This function is called from rw_verify_area() and
1274 * locks_verify_truncate().
1276 int locks_mandatory_area(int read_write, struct inode *inode,
1277 struct file *filp, loff_t offset,
1280 struct file_lock fl;
1284 locks_init_lock(&fl);
1285 fl.fl_pid = current->tgid;
1287 fl.fl_flags = FL_POSIX | FL_ACCESS;
1288 if (filp && !(filp->f_flags & O_NONBLOCK))
1290 fl.fl_type = (read_write == FLOCK_VERIFY_WRITE) ? F_WRLCK : F_RDLCK;
1291 fl.fl_start = offset;
1292 fl.fl_end = offset + count - 1;
1297 fl.fl_flags &= ~FL_SLEEP;
1298 error = __posix_lock_file(inode, &fl, NULL);
1304 fl.fl_flags |= FL_SLEEP;
1305 fl.fl_owner = current->files;
1306 error = __posix_lock_file(inode, &fl, NULL);
1307 if (error != FILE_LOCK_DEFERRED)
1309 error = wait_event_interruptible(fl.fl_wait, !fl.fl_next);
1312 * If we've been sleeping someone might have
1313 * changed the permissions behind our back.
1315 if (__mandatory_lock(inode))
1319 locks_delete_block(&fl);
1326 EXPORT_SYMBOL(locks_mandatory_area);
1328 static void lease_clear_pending(struct file_lock *fl, int arg)
1332 fl->fl_flags &= ~FL_UNLOCK_PENDING;
1335 fl->fl_flags &= ~FL_DOWNGRADE_PENDING;
1339 /* We already had a lease on this file; just change its type */
1340 int lease_modify(struct file_lock **before, int arg, struct list_head *dispose)
1342 struct file_lock *fl = *before;
1343 int error = assign_type(fl, arg);
1347 lease_clear_pending(fl, arg);
1348 locks_wake_up_blocks(fl);
1349 if (arg == F_UNLCK) {
1350 struct file *filp = fl->fl_file;
1353 filp->f_owner.signum = 0;
1354 fasync_helper(0, fl->fl_file, 0, &fl->fl_fasync);
1355 if (fl->fl_fasync != NULL) {
1356 printk(KERN_ERR "locks_delete_lock: fasync == %p\n", fl->fl_fasync);
1357 fl->fl_fasync = NULL;
1359 locks_delete_lock(before, dispose);
1363 EXPORT_SYMBOL(lease_modify);
1365 static bool past_time(unsigned long then)
1368 /* 0 is a special value meaning "this never expires": */
1370 return time_after(jiffies, then);
1373 static void time_out_leases(struct inode *inode, struct list_head *dispose)
1375 struct file_lock **before;
1376 struct file_lock *fl;
1378 lockdep_assert_held(&inode->i_lock);
1380 before = &inode->i_flock;
1381 while ((fl = *before) && IS_LEASE(fl) && lease_breaking(fl)) {
1382 trace_time_out_leases(inode, fl);
1383 if (past_time(fl->fl_downgrade_time))
1384 lease_modify(before, F_RDLCK, dispose);
1385 if (past_time(fl->fl_break_time))
1386 lease_modify(before, F_UNLCK, dispose);
1387 if (fl == *before) /* lease_modify may have freed fl */
1388 before = &fl->fl_next;
1392 static bool leases_conflict(struct file_lock *lease, struct file_lock *breaker)
1394 if ((breaker->fl_flags & FL_DELEG) && (lease->fl_flags & FL_LEASE))
1396 return locks_conflict(breaker, lease);
1400 any_leases_conflict(struct inode *inode, struct file_lock *breaker)
1402 struct file_lock *fl;
1404 lockdep_assert_held(&inode->i_lock);
1406 for (fl = inode->i_flock ; fl && IS_LEASE(fl); fl = fl->fl_next) {
1407 if (leases_conflict(fl, breaker))
1414 * __break_lease - revoke all outstanding leases on file
1415 * @inode: the inode of the file to return
1416 * @mode: O_RDONLY: break only write leases; O_WRONLY or O_RDWR:
1418 * @type: FL_LEASE: break leases and delegations; FL_DELEG: break
1421 * break_lease (inlined for speed) has checked there already is at least
1422 * some kind of lock (maybe a lease) on this file. Leases are broken on
1423 * a call to open() or truncate(). This function can sleep unless you
1424 * specified %O_NONBLOCK to your open().
1426 int __break_lease(struct inode *inode, unsigned int mode, unsigned int type)
1429 struct file_lock *new_fl;
1430 struct file_lock *fl, **before;
1431 unsigned long break_time;
1432 int want_write = (mode & O_ACCMODE) != O_RDONLY;
1435 new_fl = lease_alloc(NULL, want_write ? F_WRLCK : F_RDLCK);
1437 return PTR_ERR(new_fl);
1438 new_fl->fl_flags = type;
1440 spin_lock(&inode->i_lock);
1442 time_out_leases(inode, &dispose);
1444 if (!any_leases_conflict(inode, new_fl))
1448 if (lease_break_time > 0) {
1449 break_time = jiffies + lease_break_time * HZ;
1450 if (break_time == 0)
1451 break_time++; /* so that 0 means no break time */
1454 for (before = &inode->i_flock;
1455 ((fl = *before) != NULL) && IS_LEASE(fl);
1456 before = &fl->fl_next) {
1457 if (!leases_conflict(fl, new_fl))
1460 if (fl->fl_flags & FL_UNLOCK_PENDING)
1462 fl->fl_flags |= FL_UNLOCK_PENDING;
1463 fl->fl_break_time = break_time;
1465 if (lease_breaking(inode->i_flock))
1467 fl->fl_flags |= FL_DOWNGRADE_PENDING;
1468 fl->fl_downgrade_time = break_time;
1470 if (fl->fl_lmops->lm_break(fl))
1471 locks_delete_lock(before, &dispose);
1474 fl = inode->i_flock;
1475 if (!fl || !IS_LEASE(fl))
1478 if (mode & O_NONBLOCK) {
1479 trace_break_lease_noblock(inode, new_fl);
1480 error = -EWOULDBLOCK;
1485 break_time = inode->i_flock->fl_break_time;
1486 if (break_time != 0)
1487 break_time -= jiffies;
1488 if (break_time == 0)
1490 locks_insert_block(inode->i_flock, new_fl);
1491 trace_break_lease_block(inode, new_fl);
1492 spin_unlock(&inode->i_lock);
1493 locks_dispose_list(&dispose);
1494 error = wait_event_interruptible_timeout(new_fl->fl_wait,
1495 !new_fl->fl_next, break_time);
1496 spin_lock(&inode->i_lock);
1497 trace_break_lease_unblock(inode, new_fl);
1498 locks_delete_block(new_fl);
1501 * Wait for the next conflicting lease that has not been
1505 time_out_leases(inode, &dispose);
1506 if (any_leases_conflict(inode, new_fl))
1513 spin_unlock(&inode->i_lock);
1514 locks_dispose_list(&dispose);
1515 locks_free_lock(new_fl);
1519 EXPORT_SYMBOL(__break_lease);
1522 * lease_get_mtime - get the last modified time of an inode
1524 * @time: pointer to a timespec which will contain the last modified time
1526 * This is to force NFS clients to flush their caches for files with
1527 * exclusive leases. The justification is that if someone has an
1528 * exclusive lease, then they could be modifying it.
1530 void lease_get_mtime(struct inode *inode, struct timespec *time)
1532 bool has_lease = false;
1533 struct file_lock *flock;
1535 if (inode->i_flock) {
1536 spin_lock(&inode->i_lock);
1537 flock = inode->i_flock;
1538 if (flock && IS_LEASE(flock) && (flock->fl_type == F_WRLCK))
1540 spin_unlock(&inode->i_lock);
1544 *time = current_fs_time(inode->i_sb);
1546 *time = inode->i_mtime;
1549 EXPORT_SYMBOL(lease_get_mtime);
1552 * fcntl_getlease - Enquire what lease is currently active
1555 * The value returned by this function will be one of
1556 * (if no lease break is pending):
1558 * %F_RDLCK to indicate a shared lease is held.
1560 * %F_WRLCK to indicate an exclusive lease is held.
1562 * %F_UNLCK to indicate no lease is held.
1564 * (if a lease break is pending):
1566 * %F_RDLCK to indicate an exclusive lease needs to be
1567 * changed to a shared lease (or removed).
1569 * %F_UNLCK to indicate the lease needs to be removed.
1571 * XXX: sfr & willy disagree over whether F_INPROGRESS
1572 * should be returned to userspace.
1574 int fcntl_getlease(struct file *filp)
1576 struct file_lock *fl;
1577 struct inode *inode = file_inode(filp);
1581 spin_lock(&inode->i_lock);
1582 time_out_leases(file_inode(filp), &dispose);
1583 for (fl = file_inode(filp)->i_flock; fl && IS_LEASE(fl);
1585 if (fl->fl_file == filp) {
1586 type = target_leasetype(fl);
1590 spin_unlock(&inode->i_lock);
1591 locks_dispose_list(&dispose);
1596 * check_conflicting_open - see if the given dentry points to a file that has
1597 * an existing open that would conflict with the
1599 * @dentry: dentry to check
1600 * @arg: type of lease that we're trying to acquire
1602 * Check to see if there's an existing open fd on this file that would
1603 * conflict with the lease we're trying to set.
1606 check_conflicting_open(const struct dentry *dentry, const long arg)
1609 struct inode *inode = dentry->d_inode;
1611 if ((arg == F_RDLCK) && (atomic_read(&inode->i_writecount) > 0))
1614 if ((arg == F_WRLCK) && ((d_count(dentry) > 1) ||
1615 (atomic_read(&inode->i_count) > 1)))
1622 generic_add_lease(struct file *filp, long arg, struct file_lock **flp, void **priv)
1624 struct file_lock *fl, **before, **my_before = NULL, *lease;
1625 struct dentry *dentry = filp->f_path.dentry;
1626 struct inode *inode = dentry->d_inode;
1627 bool is_deleg = (*flp)->fl_flags & FL_DELEG;
1632 trace_generic_add_lease(inode, lease);
1635 * In the delegation case we need mutual exclusion with
1636 * a number of operations that take the i_mutex. We trylock
1637 * because delegations are an optional optimization, and if
1638 * there's some chance of a conflict--we'd rather not
1639 * bother, maybe that's a sign this just isn't a good file to
1640 * hand out a delegation on.
1642 if (is_deleg && !mutex_trylock(&inode->i_mutex))
1645 if (is_deleg && arg == F_WRLCK) {
1646 /* Write delegations are not currently supported: */
1647 mutex_unlock(&inode->i_mutex);
1652 spin_lock(&inode->i_lock);
1653 time_out_leases(inode, &dispose);
1654 error = check_conflicting_open(dentry, arg);
1659 * At this point, we know that if there is an exclusive
1660 * lease on this file, then we hold it on this filp
1661 * (otherwise our open of this file would have blocked).
1662 * And if we are trying to acquire an exclusive lease,
1663 * then the file is not open by anyone (including us)
1664 * except for this filp.
1667 for (before = &inode->i_flock;
1668 ((fl = *before) != NULL) && IS_LEASE(fl);
1669 before = &fl->fl_next) {
1670 if (fl->fl_file == filp) {
1675 * No exclusive leases if someone else has a lease on
1681 * Modifying our existing lease is OK, but no getting a
1682 * new lease if someone else is opening for write:
1684 if (fl->fl_flags & FL_UNLOCK_PENDING)
1688 if (my_before != NULL) {
1690 error = lease->fl_lmops->lm_change(my_before, arg, &dispose);
1700 locks_insert_lock(before, lease);
1702 * The check in break_lease() is lockless. It's possible for another
1703 * open to race in after we did the earlier check for a conflicting
1704 * open but before the lease was inserted. Check again for a
1705 * conflicting open and cancel the lease if there is one.
1707 * We also add a barrier here to ensure that the insertion of the lock
1708 * precedes these checks.
1711 error = check_conflicting_open(dentry, arg);
1716 if (lease->fl_lmops->lm_setup)
1717 lease->fl_lmops->lm_setup(lease, priv);
1719 spin_unlock(&inode->i_lock);
1720 locks_dispose_list(&dispose);
1722 mutex_unlock(&inode->i_mutex);
1723 if (!error && !my_before)
1727 locks_unlink_lock(before);
1731 static int generic_delete_lease(struct file *filp)
1733 int error = -EAGAIN;
1734 struct file_lock *fl, **before;
1735 struct dentry *dentry = filp->f_path.dentry;
1736 struct inode *inode = dentry->d_inode;
1739 spin_lock(&inode->i_lock);
1740 time_out_leases(inode, &dispose);
1741 for (before = &inode->i_flock;
1742 ((fl = *before) != NULL) && IS_LEASE(fl);
1743 before = &fl->fl_next) {
1744 if (fl->fl_file == filp)
1747 trace_generic_delete_lease(inode, fl);
1748 if (fl && IS_LEASE(fl))
1749 error = fl->fl_lmops->lm_change(before, F_UNLCK, &dispose);
1750 spin_unlock(&inode->i_lock);
1751 locks_dispose_list(&dispose);
1756 * generic_setlease - sets a lease on an open file
1757 * @filp: file pointer
1758 * @arg: type of lease to obtain
1759 * @flp: input - file_lock to use, output - file_lock inserted
1760 * @priv: private data for lm_setup (may be NULL if lm_setup
1761 * doesn't require it)
1763 * The (input) flp->fl_lmops->lm_break function is required
1766 int generic_setlease(struct file *filp, long arg, struct file_lock **flp,
1769 struct dentry *dentry = filp->f_path.dentry;
1770 struct inode *inode = dentry->d_inode;
1773 if ((!uid_eq(current_fsuid(), inode->i_uid)) && !capable(CAP_LEASE))
1775 if (!S_ISREG(inode->i_mode))
1777 error = security_file_lock(filp, arg);
1783 return generic_delete_lease(filp);
1786 if (!(*flp)->fl_lmops->lm_break) {
1790 return generic_add_lease(filp, arg, flp, priv);
1795 EXPORT_SYMBOL(generic_setlease);
1798 * vfs_setlease - sets a lease on an open file
1799 * @filp: file pointer
1800 * @arg: type of lease to obtain
1801 * @lease: file_lock to use when adding a lease
1802 * @priv: private info for lm_setup when adding a lease (may be
1803 * NULL if lm_setup doesn't require it)
1805 * Call this to establish a lease on the file. The "lease" argument is not
1806 * used for F_UNLCK requests and may be NULL. For commands that set or alter
1807 * an existing lease, the (*lease)->fl_lmops->lm_break operation must be set;
1808 * if not, this function will return -ENOLCK (and generate a scary-looking
1811 * The "priv" pointer is passed directly to the lm_setup function as-is. It
1812 * may be NULL if the lm_setup operation doesn't require it.
1815 vfs_setlease(struct file *filp, long arg, struct file_lock **lease, void **priv)
1817 if (filp->f_op->setlease)
1818 return filp->f_op->setlease(filp, arg, lease, priv);
1820 return generic_setlease(filp, arg, lease, priv);
1822 EXPORT_SYMBOL_GPL(vfs_setlease);
1824 static int do_fcntl_add_lease(unsigned int fd, struct file *filp, long arg)
1826 struct file_lock *fl;
1827 struct fasync_struct *new;
1830 fl = lease_alloc(filp, arg);
1834 new = fasync_alloc();
1836 locks_free_lock(fl);
1841 error = vfs_setlease(filp, arg, &fl, (void **)&new);
1843 locks_free_lock(fl);
1850 * fcntl_setlease - sets a lease on an open file
1851 * @fd: open file descriptor
1852 * @filp: file pointer
1853 * @arg: type of lease to obtain
1855 * Call this fcntl to establish a lease on the file.
1856 * Note that you also need to call %F_SETSIG to
1857 * receive a signal when the lease is broken.
1859 int fcntl_setlease(unsigned int fd, struct file *filp, long arg)
1862 return vfs_setlease(filp, F_UNLCK, NULL, NULL);
1863 return do_fcntl_add_lease(fd, filp, arg);
1867 * flock_lock_file_wait - Apply a FLOCK-style lock to a file
1868 * @filp: The file to apply the lock to
1869 * @fl: The lock to be applied
1871 * Add a FLOCK style lock to a file.
1873 int flock_lock_file_wait(struct file *filp, struct file_lock *fl)
1878 error = flock_lock_file(filp, fl);
1879 if (error != FILE_LOCK_DEFERRED)
1881 error = wait_event_interruptible(fl->fl_wait, !fl->fl_next);
1885 locks_delete_block(fl);
1891 EXPORT_SYMBOL(flock_lock_file_wait);
1894 * sys_flock: - flock() system call.
1895 * @fd: the file descriptor to lock.
1896 * @cmd: the type of lock to apply.
1898 * Apply a %FL_FLOCK style lock to an open file descriptor.
1899 * The @cmd can be one of
1901 * %LOCK_SH -- a shared lock.
1903 * %LOCK_EX -- an exclusive lock.
1905 * %LOCK_UN -- remove an existing lock.
1907 * %LOCK_MAND -- a `mandatory' flock. This exists to emulate Windows Share Modes.
1909 * %LOCK_MAND can be combined with %LOCK_READ or %LOCK_WRITE to allow other
1910 * processes read and write access respectively.
1912 SYSCALL_DEFINE2(flock, unsigned int, fd, unsigned int, cmd)
1914 struct fd f = fdget(fd);
1915 struct file_lock *lock;
1916 int can_sleep, unlock;
1923 can_sleep = !(cmd & LOCK_NB);
1925 unlock = (cmd == LOCK_UN);
1927 if (!unlock && !(cmd & LOCK_MAND) &&
1928 !(f.file->f_mode & (FMODE_READ|FMODE_WRITE)))
1931 lock = flock_make_lock(f.file, cmd);
1933 error = PTR_ERR(lock);
1938 lock->fl_flags |= FL_SLEEP;
1940 error = security_file_lock(f.file, lock->fl_type);
1944 if (f.file->f_op->flock)
1945 error = f.file->f_op->flock(f.file,
1946 (can_sleep) ? F_SETLKW : F_SETLK,
1949 error = flock_lock_file_wait(f.file, lock);
1952 locks_free_lock(lock);
1961 * vfs_test_lock - test file byte range lock
1962 * @filp: The file to test lock for
1963 * @fl: The lock to test; also used to hold result
1965 * Returns -ERRNO on failure. Indicates presence of conflicting lock by
1966 * setting conf->fl_type to something other than F_UNLCK.
1968 int vfs_test_lock(struct file *filp, struct file_lock *fl)
1970 if (filp->f_op->lock)
1971 return filp->f_op->lock(filp, F_GETLK, fl);
1972 posix_test_lock(filp, fl);
1975 EXPORT_SYMBOL_GPL(vfs_test_lock);
1977 static int posix_lock_to_flock(struct flock *flock, struct file_lock *fl)
1979 flock->l_pid = IS_OFDLCK(fl) ? -1 : fl->fl_pid;
1980 #if BITS_PER_LONG == 32
1982 * Make sure we can represent the posix lock via
1983 * legacy 32bit flock.
1985 if (fl->fl_start > OFFT_OFFSET_MAX)
1987 if (fl->fl_end != OFFSET_MAX && fl->fl_end > OFFT_OFFSET_MAX)
1990 flock->l_start = fl->fl_start;
1991 flock->l_len = fl->fl_end == OFFSET_MAX ? 0 :
1992 fl->fl_end - fl->fl_start + 1;
1993 flock->l_whence = 0;
1994 flock->l_type = fl->fl_type;
1998 #if BITS_PER_LONG == 32
1999 static void posix_lock_to_flock64(struct flock64 *flock, struct file_lock *fl)
2001 flock->l_pid = IS_OFDLCK(fl) ? -1 : fl->fl_pid;
2002 flock->l_start = fl->fl_start;
2003 flock->l_len = fl->fl_end == OFFSET_MAX ? 0 :
2004 fl->fl_end - fl->fl_start + 1;
2005 flock->l_whence = 0;
2006 flock->l_type = fl->fl_type;
2010 /* Report the first existing lock that would conflict with l.
2011 * This implements the F_GETLK command of fcntl().
2013 int fcntl_getlk(struct file *filp, unsigned int cmd, struct flock __user *l)
2015 struct file_lock file_lock;
2020 if (copy_from_user(&flock, l, sizeof(flock)))
2023 if ((flock.l_type != F_RDLCK) && (flock.l_type != F_WRLCK))
2026 error = flock_to_posix_lock(filp, &file_lock, &flock);
2030 if (cmd == F_OFD_GETLK) {
2032 if (flock.l_pid != 0)
2036 file_lock.fl_flags |= FL_OFDLCK;
2037 file_lock.fl_owner = filp;
2040 error = vfs_test_lock(filp, &file_lock);
2044 flock.l_type = file_lock.fl_type;
2045 if (file_lock.fl_type != F_UNLCK) {
2046 error = posix_lock_to_flock(&flock, &file_lock);
2051 if (!copy_to_user(l, &flock, sizeof(flock)))
2054 locks_release_private(&file_lock);
2060 * vfs_lock_file - file byte range lock
2061 * @filp: The file to apply the lock to
2062 * @cmd: type of locking operation (F_SETLK, F_GETLK, etc.)
2063 * @fl: The lock to be applied
2064 * @conf: Place to return a copy of the conflicting lock, if found.
2066 * A caller that doesn't care about the conflicting lock may pass NULL
2067 * as the final argument.
2069 * If the filesystem defines a private ->lock() method, then @conf will
2070 * be left unchanged; so a caller that cares should initialize it to
2071 * some acceptable default.
2073 * To avoid blocking kernel daemons, such as lockd, that need to acquire POSIX
2074 * locks, the ->lock() interface may return asynchronously, before the lock has
2075 * been granted or denied by the underlying filesystem, if (and only if)
2076 * lm_grant is set. Callers expecting ->lock() to return asynchronously
2077 * will only use F_SETLK, not F_SETLKW; they will set FL_SLEEP if (and only if)
2078 * the request is for a blocking lock. When ->lock() does return asynchronously,
2079 * it must return FILE_LOCK_DEFERRED, and call ->lm_grant() when the lock
2080 * request completes.
2081 * If the request is for non-blocking lock the file system should return
2082 * FILE_LOCK_DEFERRED then try to get the lock and call the callback routine
2083 * with the result. If the request timed out the callback routine will return a
2084 * nonzero return code and the file system should release the lock. The file
2085 * system is also responsible to keep a corresponding posix lock when it
2086 * grants a lock so the VFS can find out which locks are locally held and do
2087 * the correct lock cleanup when required.
2088 * The underlying filesystem must not drop the kernel lock or call
2089 * ->lm_grant() before returning to the caller with a FILE_LOCK_DEFERRED
2092 int vfs_lock_file(struct file *filp, unsigned int cmd, struct file_lock *fl, struct file_lock *conf)
2094 if (filp->f_op->lock)
2095 return filp->f_op->lock(filp, cmd, fl);
2097 return posix_lock_file(filp, fl, conf);
2099 EXPORT_SYMBOL_GPL(vfs_lock_file);
2101 static int do_lock_file_wait(struct file *filp, unsigned int cmd,
2102 struct file_lock *fl)
2106 error = security_file_lock(filp, fl->fl_type);
2111 error = vfs_lock_file(filp, cmd, fl, NULL);
2112 if (error != FILE_LOCK_DEFERRED)
2114 error = wait_event_interruptible(fl->fl_wait, !fl->fl_next);
2118 locks_delete_block(fl);
2125 /* Ensure that fl->fl_filp has compatible f_mode for F_SETLK calls */
2127 check_fmode_for_setlk(struct file_lock *fl)
2129 switch (fl->fl_type) {
2131 if (!(fl->fl_file->f_mode & FMODE_READ))
2135 if (!(fl->fl_file->f_mode & FMODE_WRITE))
2141 /* Apply the lock described by l to an open file descriptor.
2142 * This implements both the F_SETLK and F_SETLKW commands of fcntl().
2144 int fcntl_setlk(unsigned int fd, struct file *filp, unsigned int cmd,
2145 struct flock __user *l)
2147 struct file_lock *file_lock = locks_alloc_lock();
2149 struct inode *inode;
2153 if (file_lock == NULL)
2157 * This might block, so we do it before checking the inode.
2160 if (copy_from_user(&flock, l, sizeof(flock)))
2163 inode = file_inode(filp);
2165 /* Don't allow mandatory locks on files that may be memory mapped
2168 if (mandatory_lock(inode) && mapping_writably_mapped(filp->f_mapping)) {
2174 error = flock_to_posix_lock(filp, file_lock, &flock);
2178 error = check_fmode_for_setlk(file_lock);
2183 * If the cmd is requesting file-private locks, then set the
2184 * FL_OFDLCK flag and override the owner.
2189 if (flock.l_pid != 0)
2193 file_lock->fl_flags |= FL_OFDLCK;
2194 file_lock->fl_owner = filp;
2198 if (flock.l_pid != 0)
2202 file_lock->fl_flags |= FL_OFDLCK;
2203 file_lock->fl_owner = filp;
2206 file_lock->fl_flags |= FL_SLEEP;
2209 error = do_lock_file_wait(filp, cmd, file_lock);
2212 * Attempt to detect a close/fcntl race and recover by
2213 * releasing the lock that was just acquired.
2216 * we need that spin_lock here - it prevents reordering between
2217 * update of inode->i_flock and check for it done in close().
2218 * rcu_read_lock() wouldn't do.
2220 spin_lock(¤t->files->file_lock);
2222 spin_unlock(¤t->files->file_lock);
2223 if (!error && f != filp && flock.l_type != F_UNLCK) {
2224 flock.l_type = F_UNLCK;
2229 locks_free_lock(file_lock);
2233 #if BITS_PER_LONG == 32
2234 /* Report the first existing lock that would conflict with l.
2235 * This implements the F_GETLK command of fcntl().
2237 int fcntl_getlk64(struct file *filp, unsigned int cmd, struct flock64 __user *l)
2239 struct file_lock file_lock;
2240 struct flock64 flock;
2244 if (copy_from_user(&flock, l, sizeof(flock)))
2247 if ((flock.l_type != F_RDLCK) && (flock.l_type != F_WRLCK))
2250 error = flock64_to_posix_lock(filp, &file_lock, &flock);
2254 if (cmd == F_OFD_GETLK) {
2256 if (flock.l_pid != 0)
2260 file_lock.fl_flags |= FL_OFDLCK;
2261 file_lock.fl_owner = filp;
2264 error = vfs_test_lock(filp, &file_lock);
2268 flock.l_type = file_lock.fl_type;
2269 if (file_lock.fl_type != F_UNLCK)
2270 posix_lock_to_flock64(&flock, &file_lock);
2273 if (!copy_to_user(l, &flock, sizeof(flock)))
2276 locks_release_private(&file_lock);
2281 /* Apply the lock described by l to an open file descriptor.
2282 * This implements both the F_SETLK and F_SETLKW commands of fcntl().
2284 int fcntl_setlk64(unsigned int fd, struct file *filp, unsigned int cmd,
2285 struct flock64 __user *l)
2287 struct file_lock *file_lock = locks_alloc_lock();
2288 struct flock64 flock;
2289 struct inode *inode;
2293 if (file_lock == NULL)
2297 * This might block, so we do it before checking the inode.
2300 if (copy_from_user(&flock, l, sizeof(flock)))
2303 inode = file_inode(filp);
2305 /* Don't allow mandatory locks on files that may be memory mapped
2308 if (mandatory_lock(inode) && mapping_writably_mapped(filp->f_mapping)) {
2314 error = flock64_to_posix_lock(filp, file_lock, &flock);
2318 error = check_fmode_for_setlk(file_lock);
2323 * If the cmd is requesting file-private locks, then set the
2324 * FL_OFDLCK flag and override the owner.
2329 if (flock.l_pid != 0)
2333 file_lock->fl_flags |= FL_OFDLCK;
2334 file_lock->fl_owner = filp;
2338 if (flock.l_pid != 0)
2342 file_lock->fl_flags |= FL_OFDLCK;
2343 file_lock->fl_owner = filp;
2346 file_lock->fl_flags |= FL_SLEEP;
2349 error = do_lock_file_wait(filp, cmd, file_lock);
2352 * Attempt to detect a close/fcntl race and recover by
2353 * releasing the lock that was just acquired.
2355 spin_lock(¤t->files->file_lock);
2357 spin_unlock(¤t->files->file_lock);
2358 if (!error && f != filp && flock.l_type != F_UNLCK) {
2359 flock.l_type = F_UNLCK;
2364 locks_free_lock(file_lock);
2367 #endif /* BITS_PER_LONG == 32 */
2370 * This function is called when the file is being removed
2371 * from the task's fd array. POSIX locks belonging to this task
2372 * are deleted at this time.
2374 void locks_remove_posix(struct file *filp, fl_owner_t owner)
2376 struct file_lock lock;
2379 * If there are no locks held on this file, we don't need to call
2380 * posix_lock_file(). Another process could be setting a lock on this
2381 * file at the same time, but we wouldn't remove that lock anyway.
2383 if (!file_inode(filp)->i_flock)
2386 lock.fl_type = F_UNLCK;
2387 lock.fl_flags = FL_POSIX | FL_CLOSE;
2389 lock.fl_end = OFFSET_MAX;
2390 lock.fl_owner = owner;
2391 lock.fl_pid = current->tgid;
2392 lock.fl_file = filp;
2394 lock.fl_lmops = NULL;
2396 vfs_lock_file(filp, F_SETLK, &lock, NULL);
2398 if (lock.fl_ops && lock.fl_ops->fl_release_private)
2399 lock.fl_ops->fl_release_private(&lock);
2402 EXPORT_SYMBOL(locks_remove_posix);
2405 locks_remove_flock(struct file *filp)
2407 struct file_lock fl = {
2409 .fl_pid = current->tgid,
2411 .fl_flags = FL_FLOCK,
2413 .fl_end = OFFSET_MAX,
2416 if (!file_inode(filp)->i_flock)
2419 if (filp->f_op->flock)
2420 filp->f_op->flock(filp, F_SETLKW, &fl);
2422 flock_lock_file(filp, &fl);
2424 if (fl.fl_ops && fl.fl_ops->fl_release_private)
2425 fl.fl_ops->fl_release_private(&fl);
2429 * This function is called on the last close of an open file.
2431 void locks_remove_file(struct file *filp)
2433 struct inode * inode = file_inode(filp);
2434 struct file_lock *fl;
2435 struct file_lock **before;
2438 /* remove any OFD locks */
2439 locks_remove_posix(filp, filp);
2441 /* remove flock locks */
2442 locks_remove_flock(filp);
2444 if (!inode->i_flock)
2447 spin_lock(&inode->i_lock);
2448 before = &inode->i_flock;
2450 while ((fl = *before) != NULL) {
2451 if (fl->fl_file == filp) {
2453 lease_modify(before, F_UNLCK, &dispose);
2458 * There's a leftover lock on the list of a type that
2459 * we didn't expect to see. Most likely a classic
2460 * POSIX lock that ended up not getting released
2461 * properly, or that raced onto the list somehow. Log
2462 * some info about it and then just remove it from
2465 WARN(1, "leftover lock: dev=%u:%u ino=%lu type=%hhd flags=0x%x start=%lld end=%lld\n",
2466 MAJOR(inode->i_sb->s_dev),
2467 MINOR(inode->i_sb->s_dev), inode->i_ino,
2468 fl->fl_type, fl->fl_flags,
2469 fl->fl_start, fl->fl_end);
2471 locks_delete_lock(before, &dispose);
2474 before = &fl->fl_next;
2476 spin_unlock(&inode->i_lock);
2477 locks_dispose_list(&dispose);
2481 * posix_unblock_lock - stop waiting for a file lock
2482 * @waiter: the lock which was waiting
2484 * lockd needs to block waiting for locks.
2487 posix_unblock_lock(struct file_lock *waiter)
2491 spin_lock(&blocked_lock_lock);
2492 if (waiter->fl_next)
2493 __locks_delete_block(waiter);
2496 spin_unlock(&blocked_lock_lock);
2499 EXPORT_SYMBOL(posix_unblock_lock);
2502 * vfs_cancel_lock - file byte range unblock lock
2503 * @filp: The file to apply the unblock to
2504 * @fl: The lock to be unblocked
2506 * Used by lock managers to cancel blocked requests
2508 int vfs_cancel_lock(struct file *filp, struct file_lock *fl)
2510 if (filp->f_op->lock)
2511 return filp->f_op->lock(filp, F_CANCELLK, fl);
2515 EXPORT_SYMBOL_GPL(vfs_cancel_lock);
2517 #ifdef CONFIG_PROC_FS
2518 #include <linux/proc_fs.h>
2519 #include <linux/seq_file.h>
2521 struct locks_iterator {
2526 static void lock_get_status(struct seq_file *f, struct file_lock *fl,
2527 loff_t id, char *pfx)
2529 struct inode *inode = NULL;
2530 unsigned int fl_pid;
2533 fl_pid = pid_vnr(fl->fl_nspid);
2535 fl_pid = fl->fl_pid;
2537 if (fl->fl_file != NULL)
2538 inode = file_inode(fl->fl_file);
2540 seq_printf(f, "%lld:%s ", id, pfx);
2542 if (fl->fl_flags & FL_ACCESS)
2543 seq_puts(f, "ACCESS");
2544 else if (IS_OFDLCK(fl))
2545 seq_puts(f, "OFDLCK");
2547 seq_puts(f, "POSIX ");
2549 seq_printf(f, " %s ",
2550 (inode == NULL) ? "*NOINODE*" :
2551 mandatory_lock(inode) ? "MANDATORY" : "ADVISORY ");
2552 } else if (IS_FLOCK(fl)) {
2553 if (fl->fl_type & LOCK_MAND) {
2554 seq_puts(f, "FLOCK MSNFS ");
2556 seq_puts(f, "FLOCK ADVISORY ");
2558 } else if (IS_LEASE(fl)) {
2559 if (fl->fl_flags & FL_DELEG)
2560 seq_puts(f, "DELEG ");
2562 seq_puts(f, "LEASE ");
2564 if (lease_breaking(fl))
2565 seq_puts(f, "BREAKING ");
2566 else if (fl->fl_file)
2567 seq_puts(f, "ACTIVE ");
2569 seq_puts(f, "BREAKER ");
2571 seq_puts(f, "UNKNOWN UNKNOWN ");
2573 if (fl->fl_type & LOCK_MAND) {
2574 seq_printf(f, "%s ",
2575 (fl->fl_type & LOCK_READ)
2576 ? (fl->fl_type & LOCK_WRITE) ? "RW " : "READ "
2577 : (fl->fl_type & LOCK_WRITE) ? "WRITE" : "NONE ");
2579 seq_printf(f, "%s ",
2580 (lease_breaking(fl))
2581 ? (fl->fl_type == F_UNLCK) ? "UNLCK" : "READ "
2582 : (fl->fl_type == F_WRLCK) ? "WRITE" : "READ ");
2585 #ifdef WE_CAN_BREAK_LSLK_NOW
2586 seq_printf(f, "%d %s:%ld ", fl_pid,
2587 inode->i_sb->s_id, inode->i_ino);
2589 /* userspace relies on this representation of dev_t ;-( */
2590 seq_printf(f, "%d %02x:%02x:%ld ", fl_pid,
2591 MAJOR(inode->i_sb->s_dev),
2592 MINOR(inode->i_sb->s_dev), inode->i_ino);
2595 seq_printf(f, "%d <none>:0 ", fl_pid);
2598 if (fl->fl_end == OFFSET_MAX)
2599 seq_printf(f, "%Ld EOF\n", fl->fl_start);
2601 seq_printf(f, "%Ld %Ld\n", fl->fl_start, fl->fl_end);
2603 seq_puts(f, "0 EOF\n");
2607 static int locks_show(struct seq_file *f, void *v)
2609 struct locks_iterator *iter = f->private;
2610 struct file_lock *fl, *bfl;
2612 fl = hlist_entry(v, struct file_lock, fl_link);
2614 lock_get_status(f, fl, iter->li_pos, "");
2616 list_for_each_entry(bfl, &fl->fl_block, fl_block)
2617 lock_get_status(f, bfl, iter->li_pos, " ->");
2622 static void *locks_start(struct seq_file *f, loff_t *pos)
2623 __acquires(&blocked_lock_lock)
2625 struct locks_iterator *iter = f->private;
2627 iter->li_pos = *pos + 1;
2628 lg_global_lock(&file_lock_lglock);
2629 spin_lock(&blocked_lock_lock);
2630 return seq_hlist_start_percpu(&file_lock_list, &iter->li_cpu, *pos);
2633 static void *locks_next(struct seq_file *f, void *v, loff_t *pos)
2635 struct locks_iterator *iter = f->private;
2638 return seq_hlist_next_percpu(v, &file_lock_list, &iter->li_cpu, pos);
2641 static void locks_stop(struct seq_file *f, void *v)
2642 __releases(&blocked_lock_lock)
2644 spin_unlock(&blocked_lock_lock);
2645 lg_global_unlock(&file_lock_lglock);
2648 static const struct seq_operations locks_seq_operations = {
2649 .start = locks_start,
2655 static int locks_open(struct inode *inode, struct file *filp)
2657 return seq_open_private(filp, &locks_seq_operations,
2658 sizeof(struct locks_iterator));
2661 static const struct file_operations proc_locks_operations = {
2664 .llseek = seq_lseek,
2665 .release = seq_release_private,
2668 static int __init proc_locks_init(void)
2670 proc_create("locks", 0, NULL, &proc_locks_operations);
2673 module_init(proc_locks_init);
2676 static int __init filelock_init(void)
2680 flctx_cache = kmem_cache_create("file_lock_ctx",
2681 sizeof(struct file_lock_context), 0, SLAB_PANIC, NULL);
2683 filelock_cache = kmem_cache_create("file_lock_cache",
2684 sizeof(struct file_lock), 0, SLAB_PANIC, NULL);
2686 lg_lock_init(&file_lock_lglock, "file_lock_lglock");
2688 for_each_possible_cpu(i)
2689 INIT_HLIST_HEAD(per_cpu_ptr(&file_lock_list, i));
2694 core_initcall(filelock_init);