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 #include <asm/uaccess.h>
135 #define IS_POSIX(fl) (fl->fl_flags & FL_POSIX)
136 #define IS_FLOCK(fl) (fl->fl_flags & FL_FLOCK)
137 #define IS_LEASE(fl) (fl->fl_flags & (FL_LEASE|FL_DELEG))
138 #define IS_OFDLCK(fl) (fl->fl_flags & FL_OFDLCK)
140 static bool lease_breaking(struct file_lock
*fl
)
142 return fl
->fl_flags
& (FL_UNLOCK_PENDING
| FL_DOWNGRADE_PENDING
);
145 static int target_leasetype(struct file_lock
*fl
)
147 if (fl
->fl_flags
& FL_UNLOCK_PENDING
)
149 if (fl
->fl_flags
& FL_DOWNGRADE_PENDING
)
154 int leases_enable
= 1;
155 int lease_break_time
= 45;
157 #define for_each_lock(inode, lockp) \
158 for (lockp = &inode->i_flock; *lockp != NULL; lockp = &(*lockp)->fl_next)
161 * The global file_lock_list is only used for displaying /proc/locks, so we
162 * keep a list on each CPU, with each list protected by its own spinlock via
163 * the file_lock_lglock. Note that alterations to the list also require that
164 * the relevant i_lock is held.
166 DEFINE_STATIC_LGLOCK(file_lock_lglock
);
167 static DEFINE_PER_CPU(struct hlist_head
, file_lock_list
);
170 * The blocked_hash is used to find POSIX lock loops for deadlock detection.
171 * It is protected by blocked_lock_lock.
173 * We hash locks by lockowner in order to optimize searching for the lock a
174 * particular lockowner is waiting on.
176 * FIXME: make this value scale via some heuristic? We generally will want more
177 * buckets when we have more lockowners holding locks, but that's a little
178 * difficult to determine without knowing what the workload will look like.
180 #define BLOCKED_HASH_BITS 7
181 static DEFINE_HASHTABLE(blocked_hash
, BLOCKED_HASH_BITS
);
184 * This lock protects the blocked_hash. Generally, if you're accessing it, you
185 * want to be holding this lock.
187 * In addition, it also protects the fl->fl_block list, and the fl->fl_next
188 * pointer for file_lock structures that are acting as lock requests (in
189 * contrast to those that are acting as records of acquired locks).
191 * Note that when we acquire this lock in order to change the above fields,
192 * we often hold the i_lock as well. In certain cases, when reading the fields
193 * protected by this lock, we can skip acquiring it iff we already hold the
196 * In particular, adding an entry to the fl_block list requires that you hold
197 * both the i_lock and the blocked_lock_lock (acquired in that order). Deleting
198 * an entry from the list however only requires the file_lock_lock.
200 static DEFINE_SPINLOCK(blocked_lock_lock
);
202 static struct kmem_cache
*filelock_cache __read_mostly
;
204 static void locks_init_lock_heads(struct file_lock
*fl
)
206 INIT_HLIST_NODE(&fl
->fl_link
);
207 INIT_LIST_HEAD(&fl
->fl_block
);
208 init_waitqueue_head(&fl
->fl_wait
);
211 /* Allocate an empty lock structure. */
212 struct file_lock
*locks_alloc_lock(void)
214 struct file_lock
*fl
= kmem_cache_zalloc(filelock_cache
, GFP_KERNEL
);
217 locks_init_lock_heads(fl
);
221 EXPORT_SYMBOL_GPL(locks_alloc_lock
);
223 void locks_release_private(struct file_lock
*fl
)
226 if (fl
->fl_ops
->fl_release_private
)
227 fl
->fl_ops
->fl_release_private(fl
);
233 EXPORT_SYMBOL_GPL(locks_release_private
);
235 /* Free a lock which is not in use. */
236 void locks_free_lock(struct file_lock
*fl
)
238 BUG_ON(waitqueue_active(&fl
->fl_wait
));
239 BUG_ON(!list_empty(&fl
->fl_block
));
240 BUG_ON(!hlist_unhashed(&fl
->fl_link
));
242 locks_release_private(fl
);
243 kmem_cache_free(filelock_cache
, fl
);
245 EXPORT_SYMBOL(locks_free_lock
);
247 void locks_init_lock(struct file_lock
*fl
)
249 memset(fl
, 0, sizeof(struct file_lock
));
250 locks_init_lock_heads(fl
);
253 EXPORT_SYMBOL(locks_init_lock
);
255 static void locks_copy_private(struct file_lock
*new, struct file_lock
*fl
)
258 if (fl
->fl_ops
->fl_copy_lock
)
259 fl
->fl_ops
->fl_copy_lock(new, fl
);
260 new->fl_ops
= fl
->fl_ops
;
263 new->fl_lmops
= fl
->fl_lmops
;
267 * Initialize a new lock from an existing file_lock structure.
269 void __locks_copy_lock(struct file_lock
*new, const struct file_lock
*fl
)
271 new->fl_owner
= fl
->fl_owner
;
272 new->fl_pid
= fl
->fl_pid
;
274 new->fl_flags
= fl
->fl_flags
;
275 new->fl_type
= fl
->fl_type
;
276 new->fl_start
= fl
->fl_start
;
277 new->fl_end
= fl
->fl_end
;
279 new->fl_lmops
= NULL
;
281 EXPORT_SYMBOL(__locks_copy_lock
);
283 void locks_copy_lock(struct file_lock
*new, struct file_lock
*fl
)
285 locks_release_private(new);
287 __locks_copy_lock(new, fl
);
288 new->fl_file
= fl
->fl_file
;
289 new->fl_ops
= fl
->fl_ops
;
290 new->fl_lmops
= fl
->fl_lmops
;
292 locks_copy_private(new, fl
);
295 EXPORT_SYMBOL(locks_copy_lock
);
297 static inline int flock_translate_cmd(int cmd
) {
299 return cmd
& (LOCK_MAND
| LOCK_RW
);
311 /* Fill in a file_lock structure with an appropriate FLOCK lock. */
312 static int flock_make_lock(struct file
*filp
, struct file_lock
**lock
,
315 struct file_lock
*fl
;
316 int type
= flock_translate_cmd(cmd
);
320 fl
= locks_alloc_lock();
325 fl
->fl_pid
= current
->tgid
;
326 fl
->fl_flags
= FL_FLOCK
;
328 fl
->fl_end
= OFFSET_MAX
;
334 static int assign_type(struct file_lock
*fl
, long type
)
348 static int flock64_to_posix_lock(struct file
*filp
, struct file_lock
*fl
,
351 switch (l
->l_whence
) {
356 fl
->fl_start
= filp
->f_pos
;
359 fl
->fl_start
= i_size_read(file_inode(filp
));
364 if (l
->l_start
> OFFSET_MAX
- fl
->fl_start
)
366 fl
->fl_start
+= l
->l_start
;
367 if (fl
->fl_start
< 0)
370 /* POSIX-1996 leaves the case l->l_len < 0 undefined;
371 POSIX-2001 defines it. */
373 if (l
->l_len
- 1 > OFFSET_MAX
- fl
->fl_start
)
375 fl
->fl_end
= fl
->fl_start
+ l
->l_len
- 1;
377 } else if (l
->l_len
< 0) {
378 if (fl
->fl_start
+ l
->l_len
< 0)
380 fl
->fl_end
= fl
->fl_start
- 1;
381 fl
->fl_start
+= l
->l_len
;
383 fl
->fl_end
= OFFSET_MAX
;
385 fl
->fl_owner
= current
->files
;
386 fl
->fl_pid
= current
->tgid
;
388 fl
->fl_flags
= FL_POSIX
;
392 return assign_type(fl
, l
->l_type
);
395 /* Verify a "struct flock" and copy it to a "struct file_lock" as a POSIX
398 static int flock_to_posix_lock(struct file
*filp
, struct file_lock
*fl
,
401 struct flock64 ll
= {
403 .l_whence
= l
->l_whence
,
404 .l_start
= l
->l_start
,
408 return flock64_to_posix_lock(filp
, fl
, &ll
);
411 /* default lease lock manager operations */
412 static void lease_break_callback(struct file_lock
*fl
)
414 kill_fasync(&fl
->fl_fasync
, SIGIO
, POLL_MSG
);
417 static const struct lock_manager_operations lease_manager_ops
= {
418 .lm_break
= lease_break_callback
,
419 .lm_change
= lease_modify
,
423 * Initialize a lease, use the default lock manager operations
425 static int lease_init(struct file
*filp
, long type
, struct file_lock
*fl
)
427 if (assign_type(fl
, type
) != 0)
430 fl
->fl_owner
= current
->files
;
431 fl
->fl_pid
= current
->tgid
;
434 fl
->fl_flags
= FL_LEASE
;
436 fl
->fl_end
= OFFSET_MAX
;
438 fl
->fl_lmops
= &lease_manager_ops
;
442 /* Allocate a file_lock initialised to this type of lease */
443 static struct file_lock
*lease_alloc(struct file
*filp
, long type
)
445 struct file_lock
*fl
= locks_alloc_lock();
449 return ERR_PTR(error
);
451 error
= lease_init(filp
, type
, fl
);
454 return ERR_PTR(error
);
459 /* Check if two locks overlap each other.
461 static inline int locks_overlap(struct file_lock
*fl1
, struct file_lock
*fl2
)
463 return ((fl1
->fl_end
>= fl2
->fl_start
) &&
464 (fl2
->fl_end
>= fl1
->fl_start
));
468 * Check whether two locks have the same owner.
470 static int posix_same_owner(struct file_lock
*fl1
, struct file_lock
*fl2
)
472 if (fl1
->fl_lmops
&& fl1
->fl_lmops
->lm_compare_owner
)
473 return fl2
->fl_lmops
== fl1
->fl_lmops
&&
474 fl1
->fl_lmops
->lm_compare_owner(fl1
, fl2
);
475 return fl1
->fl_owner
== fl2
->fl_owner
;
478 /* Must be called with the i_lock held! */
479 static void locks_insert_global_locks(struct file_lock
*fl
)
481 lg_local_lock(&file_lock_lglock
);
482 fl
->fl_link_cpu
= smp_processor_id();
483 hlist_add_head(&fl
->fl_link
, this_cpu_ptr(&file_lock_list
));
484 lg_local_unlock(&file_lock_lglock
);
487 /* Must be called with the i_lock held! */
488 static void locks_delete_global_locks(struct file_lock
*fl
)
491 * Avoid taking lock if already unhashed. This is safe since this check
492 * is done while holding the i_lock, and new insertions into the list
493 * also require that it be held.
495 if (hlist_unhashed(&fl
->fl_link
))
497 lg_local_lock_cpu(&file_lock_lglock
, fl
->fl_link_cpu
);
498 hlist_del_init(&fl
->fl_link
);
499 lg_local_unlock_cpu(&file_lock_lglock
, fl
->fl_link_cpu
);
503 posix_owner_key(struct file_lock
*fl
)
505 if (fl
->fl_lmops
&& fl
->fl_lmops
->lm_owner_key
)
506 return fl
->fl_lmops
->lm_owner_key(fl
);
507 return (unsigned long)fl
->fl_owner
;
510 static void locks_insert_global_blocked(struct file_lock
*waiter
)
512 hash_add(blocked_hash
, &waiter
->fl_link
, posix_owner_key(waiter
));
515 static void locks_delete_global_blocked(struct file_lock
*waiter
)
517 hash_del(&waiter
->fl_link
);
520 /* Remove waiter from blocker's block list.
521 * When blocker ends up pointing to itself then the list is empty.
523 * Must be called with blocked_lock_lock held.
525 static void __locks_delete_block(struct file_lock
*waiter
)
527 locks_delete_global_blocked(waiter
);
528 list_del_init(&waiter
->fl_block
);
529 waiter
->fl_next
= NULL
;
532 static void locks_delete_block(struct file_lock
*waiter
)
534 spin_lock(&blocked_lock_lock
);
535 __locks_delete_block(waiter
);
536 spin_unlock(&blocked_lock_lock
);
539 /* Insert waiter into blocker's block list.
540 * We use a circular list so that processes can be easily woken up in
541 * the order they blocked. The documentation doesn't require this but
542 * it seems like the reasonable thing to do.
544 * Must be called with both the i_lock and blocked_lock_lock held. The fl_block
545 * list itself is protected by the blocked_lock_lock, but by ensuring that the
546 * i_lock is also held on insertions we can avoid taking the blocked_lock_lock
547 * in some cases when we see that the fl_block list is empty.
549 static void __locks_insert_block(struct file_lock
*blocker
,
550 struct file_lock
*waiter
)
552 BUG_ON(!list_empty(&waiter
->fl_block
));
553 waiter
->fl_next
= blocker
;
554 list_add_tail(&waiter
->fl_block
, &blocker
->fl_block
);
555 if (IS_POSIX(blocker
) && !IS_OFDLCK(blocker
))
556 locks_insert_global_blocked(waiter
);
559 /* Must be called with i_lock held. */
560 static void locks_insert_block(struct file_lock
*blocker
,
561 struct file_lock
*waiter
)
563 spin_lock(&blocked_lock_lock
);
564 __locks_insert_block(blocker
, waiter
);
565 spin_unlock(&blocked_lock_lock
);
569 * Wake up processes blocked waiting for blocker.
571 * Must be called with the inode->i_lock held!
573 static void locks_wake_up_blocks(struct file_lock
*blocker
)
576 * Avoid taking global lock if list is empty. This is safe since new
577 * blocked requests are only added to the list under the i_lock, and
578 * the i_lock is always held here. Note that removal from the fl_block
579 * list does not require the i_lock, so we must recheck list_empty()
580 * after acquiring the blocked_lock_lock.
582 if (list_empty(&blocker
->fl_block
))
585 spin_lock(&blocked_lock_lock
);
586 while (!list_empty(&blocker
->fl_block
)) {
587 struct file_lock
*waiter
;
589 waiter
= list_first_entry(&blocker
->fl_block
,
590 struct file_lock
, fl_block
);
591 __locks_delete_block(waiter
);
592 if (waiter
->fl_lmops
&& waiter
->fl_lmops
->lm_notify
)
593 waiter
->fl_lmops
->lm_notify(waiter
);
595 wake_up(&waiter
->fl_wait
);
597 spin_unlock(&blocked_lock_lock
);
600 /* Insert file lock fl into an inode's lock list at the position indicated
601 * by pos. At the same time add the lock to the global file lock list.
603 * Must be called with the i_lock held!
605 static void locks_insert_lock(struct file_lock
**pos
, struct file_lock
*fl
)
607 fl
->fl_nspid
= get_pid(task_tgid(current
));
609 /* insert into file's list */
613 locks_insert_global_locks(fl
);
617 * locks_delete_lock - Delete a lock and then free it.
618 * @thisfl_p: pointer that points to the fl_next field of the previous
619 * inode->i_flock list entry
621 * Unlink a lock from all lists and free the namespace reference, but don't
622 * free it yet. Wake up processes that are blocked waiting for this lock and
623 * notify the FS that the lock has been cleared.
625 * Must be called with the i_lock held!
627 static void locks_unlink_lock(struct file_lock
**thisfl_p
)
629 struct file_lock
*fl
= *thisfl_p
;
631 locks_delete_global_locks(fl
);
633 *thisfl_p
= fl
->fl_next
;
637 put_pid(fl
->fl_nspid
);
641 locks_wake_up_blocks(fl
);
645 * Unlink a lock from all lists and free it.
647 * Must be called with i_lock held!
649 static void locks_delete_lock(struct file_lock
**thisfl_p
)
651 struct file_lock
*fl
= *thisfl_p
;
653 locks_unlink_lock(thisfl_p
);
657 /* Determine if lock sys_fl blocks lock caller_fl. Common functionality
658 * checks for shared/exclusive status of overlapping locks.
660 static int locks_conflict(struct file_lock
*caller_fl
, struct file_lock
*sys_fl
)
662 if (sys_fl
->fl_type
== F_WRLCK
)
664 if (caller_fl
->fl_type
== F_WRLCK
)
669 /* Determine if lock sys_fl blocks lock caller_fl. POSIX specific
670 * checking before calling the locks_conflict().
672 static int posix_locks_conflict(struct file_lock
*caller_fl
, struct file_lock
*sys_fl
)
674 /* POSIX locks owned by the same process do not conflict with
677 if (!IS_POSIX(sys_fl
) || posix_same_owner(caller_fl
, sys_fl
))
680 /* Check whether they overlap */
681 if (!locks_overlap(caller_fl
, sys_fl
))
684 return (locks_conflict(caller_fl
, sys_fl
));
687 /* Determine if lock sys_fl blocks lock caller_fl. FLOCK specific
688 * checking before calling the locks_conflict().
690 static int flock_locks_conflict(struct file_lock
*caller_fl
, struct file_lock
*sys_fl
)
692 /* FLOCK locks referring to the same filp do not conflict with
695 if (!IS_FLOCK(sys_fl
) || (caller_fl
->fl_file
== sys_fl
->fl_file
))
697 if ((caller_fl
->fl_type
& LOCK_MAND
) || (sys_fl
->fl_type
& LOCK_MAND
))
700 return (locks_conflict(caller_fl
, sys_fl
));
704 posix_test_lock(struct file
*filp
, struct file_lock
*fl
)
706 struct file_lock
*cfl
;
707 struct inode
*inode
= file_inode(filp
);
709 spin_lock(&inode
->i_lock
);
710 for (cfl
= file_inode(filp
)->i_flock
; cfl
; cfl
= cfl
->fl_next
) {
713 if (posix_locks_conflict(fl
, cfl
))
717 __locks_copy_lock(fl
, cfl
);
719 fl
->fl_pid
= pid_vnr(cfl
->fl_nspid
);
721 fl
->fl_type
= F_UNLCK
;
722 spin_unlock(&inode
->i_lock
);
725 EXPORT_SYMBOL(posix_test_lock
);
728 * Deadlock detection:
730 * We attempt to detect deadlocks that are due purely to posix file
733 * We assume that a task can be waiting for at most one lock at a time.
734 * So for any acquired lock, the process holding that lock may be
735 * waiting on at most one other lock. That lock in turns may be held by
736 * someone waiting for at most one other lock. Given a requested lock
737 * caller_fl which is about to wait for a conflicting lock block_fl, we
738 * follow this chain of waiters to ensure we are not about to create a
741 * Since we do this before we ever put a process to sleep on a lock, we
742 * are ensured that there is never a cycle; that is what guarantees that
743 * the while() loop in posix_locks_deadlock() eventually completes.
745 * Note: the above assumption may not be true when handling lock
746 * requests from a broken NFS client. It may also fail in the presence
747 * of tasks (such as posix threads) sharing the same open file table.
748 * To handle those cases, we just bail out after a few iterations.
750 * For FL_OFDLCK locks, the owner is the filp, not the files_struct.
751 * Because the owner is not even nominally tied to a thread of
752 * execution, the deadlock detection below can't reasonably work well. Just
755 * In principle, we could do a more limited deadlock detection on FL_OFDLCK
756 * locks that just checks for the case where two tasks are attempting to
757 * upgrade from read to write locks on the same inode.
760 #define MAX_DEADLK_ITERATIONS 10
762 /* Find a lock that the owner of the given block_fl is blocking on. */
763 static struct file_lock
*what_owner_is_waiting_for(struct file_lock
*block_fl
)
765 struct file_lock
*fl
;
767 hash_for_each_possible(blocked_hash
, fl
, fl_link
, posix_owner_key(block_fl
)) {
768 if (posix_same_owner(fl
, block_fl
))
774 /* Must be called with the blocked_lock_lock held! */
775 static int posix_locks_deadlock(struct file_lock
*caller_fl
,
776 struct file_lock
*block_fl
)
781 * This deadlock detector can't reasonably detect deadlocks with
782 * FL_OFDLCK locks, since they aren't owned by a process, per-se.
784 if (IS_OFDLCK(caller_fl
))
787 while ((block_fl
= what_owner_is_waiting_for(block_fl
))) {
788 if (i
++ > MAX_DEADLK_ITERATIONS
)
790 if (posix_same_owner(caller_fl
, block_fl
))
796 /* Try to create a FLOCK lock on filp. We always insert new FLOCK locks
797 * after any leases, but before any posix locks.
799 * Note that if called with an FL_EXISTS argument, the caller may determine
800 * whether or not a lock was successfully freed by testing the return
803 static int flock_lock_file(struct file
*filp
, struct file_lock
*request
)
805 struct file_lock
*new_fl
= NULL
;
806 struct file_lock
**before
;
807 struct inode
* inode
= file_inode(filp
);
811 if (!(request
->fl_flags
& FL_ACCESS
) && (request
->fl_type
!= F_UNLCK
)) {
812 new_fl
= locks_alloc_lock();
817 spin_lock(&inode
->i_lock
);
818 if (request
->fl_flags
& FL_ACCESS
)
821 for_each_lock(inode
, before
) {
822 struct file_lock
*fl
= *before
;
827 if (filp
!= fl
->fl_file
)
829 if (request
->fl_type
== fl
->fl_type
)
832 locks_delete_lock(before
);
836 if (request
->fl_type
== F_UNLCK
) {
837 if ((request
->fl_flags
& FL_EXISTS
) && !found
)
843 * If a higher-priority process was blocked on the old file lock,
844 * give it the opportunity to lock the file.
847 spin_unlock(&inode
->i_lock
);
849 spin_lock(&inode
->i_lock
);
853 for_each_lock(inode
, before
) {
854 struct file_lock
*fl
= *before
;
859 if (!flock_locks_conflict(request
, fl
))
862 if (!(request
->fl_flags
& FL_SLEEP
))
864 error
= FILE_LOCK_DEFERRED
;
865 locks_insert_block(fl
, request
);
868 if (request
->fl_flags
& FL_ACCESS
)
870 locks_copy_lock(new_fl
, request
);
871 locks_insert_lock(before
, new_fl
);
876 spin_unlock(&inode
->i_lock
);
878 locks_free_lock(new_fl
);
882 static int __posix_lock_file(struct inode
*inode
, struct file_lock
*request
, struct file_lock
*conflock
)
884 struct file_lock
*fl
;
885 struct file_lock
*new_fl
= NULL
;
886 struct file_lock
*new_fl2
= NULL
;
887 struct file_lock
*left
= NULL
;
888 struct file_lock
*right
= NULL
;
889 struct file_lock
**before
;
894 * We may need two file_lock structures for this operation,
895 * so we get them in advance to avoid races.
897 * In some cases we can be sure, that no new locks will be needed
899 if (!(request
->fl_flags
& FL_ACCESS
) &&
900 (request
->fl_type
!= F_UNLCK
||
901 request
->fl_start
!= 0 || request
->fl_end
!= OFFSET_MAX
)) {
902 new_fl
= locks_alloc_lock();
903 new_fl2
= locks_alloc_lock();
906 spin_lock(&inode
->i_lock
);
908 * New lock request. Walk all POSIX locks and look for conflicts. If
909 * there are any, either return error or put the request on the
910 * blocker's list of waiters and the global blocked_hash.
912 if (request
->fl_type
!= F_UNLCK
) {
913 for_each_lock(inode
, before
) {
917 if (!posix_locks_conflict(request
, fl
))
920 __locks_copy_lock(conflock
, fl
);
922 if (!(request
->fl_flags
& FL_SLEEP
))
925 * Deadlock detection and insertion into the blocked
926 * locks list must be done while holding the same lock!
929 spin_lock(&blocked_lock_lock
);
930 if (likely(!posix_locks_deadlock(request
, fl
))) {
931 error
= FILE_LOCK_DEFERRED
;
932 __locks_insert_block(fl
, request
);
934 spin_unlock(&blocked_lock_lock
);
939 /* If we're just looking for a conflict, we're done. */
941 if (request
->fl_flags
& FL_ACCESS
)
945 * Find the first old lock with the same owner as the new lock.
948 before
= &inode
->i_flock
;
950 /* First skip locks owned by other processes. */
951 while ((fl
= *before
) && (!IS_POSIX(fl
) ||
952 !posix_same_owner(request
, fl
))) {
953 before
= &fl
->fl_next
;
956 /* Process locks with this owner. */
957 while ((fl
= *before
) && posix_same_owner(request
, fl
)) {
958 /* Detect adjacent or overlapping regions (if same lock type)
960 if (request
->fl_type
== fl
->fl_type
) {
961 /* In all comparisons of start vs end, use
962 * "start - 1" rather than "end + 1". If end
963 * is OFFSET_MAX, end + 1 will become negative.
965 if (fl
->fl_end
< request
->fl_start
- 1)
967 /* If the next lock in the list has entirely bigger
968 * addresses than the new one, insert the lock here.
970 if (fl
->fl_start
- 1 > request
->fl_end
)
973 /* If we come here, the new and old lock are of the
974 * same type and adjacent or overlapping. Make one
975 * lock yielding from the lower start address of both
976 * locks to the higher end address.
978 if (fl
->fl_start
> request
->fl_start
)
979 fl
->fl_start
= request
->fl_start
;
981 request
->fl_start
= fl
->fl_start
;
982 if (fl
->fl_end
< request
->fl_end
)
983 fl
->fl_end
= request
->fl_end
;
985 request
->fl_end
= fl
->fl_end
;
987 locks_delete_lock(before
);
994 /* Processing for different lock types is a bit
997 if (fl
->fl_end
< request
->fl_start
)
999 if (fl
->fl_start
> request
->fl_end
)
1001 if (request
->fl_type
== F_UNLCK
)
1003 if (fl
->fl_start
< request
->fl_start
)
1005 /* If the next lock in the list has a higher end
1006 * address than the new one, insert the new one here.
1008 if (fl
->fl_end
> request
->fl_end
) {
1012 if (fl
->fl_start
>= request
->fl_start
) {
1013 /* The new lock completely replaces an old
1014 * one (This may happen several times).
1017 locks_delete_lock(before
);
1020 /* Replace the old lock with the new one.
1021 * Wake up anybody waiting for the old one,
1022 * as the change in lock type might satisfy
1025 locks_wake_up_blocks(fl
);
1026 fl
->fl_start
= request
->fl_start
;
1027 fl
->fl_end
= request
->fl_end
;
1028 fl
->fl_type
= request
->fl_type
;
1029 locks_release_private(fl
);
1030 locks_copy_private(fl
, request
);
1035 /* Go on to next lock.
1038 before
= &fl
->fl_next
;
1042 * The above code only modifies existing locks in case of merging or
1043 * replacing. If new lock(s) need to be inserted all modifications are
1044 * done below this, so it's safe yet to bail out.
1046 error
= -ENOLCK
; /* "no luck" */
1047 if (right
&& left
== right
&& !new_fl2
)
1052 if (request
->fl_type
== F_UNLCK
) {
1053 if (request
->fl_flags
& FL_EXISTS
)
1062 locks_copy_lock(new_fl
, request
);
1063 locks_insert_lock(before
, new_fl
);
1067 if (left
== right
) {
1068 /* The new lock breaks the old one in two pieces,
1069 * so we have to use the second new lock.
1073 locks_copy_lock(left
, right
);
1074 locks_insert_lock(before
, left
);
1076 right
->fl_start
= request
->fl_end
+ 1;
1077 locks_wake_up_blocks(right
);
1080 left
->fl_end
= request
->fl_start
- 1;
1081 locks_wake_up_blocks(left
);
1084 spin_unlock(&inode
->i_lock
);
1086 * Free any unused locks.
1089 locks_free_lock(new_fl
);
1091 locks_free_lock(new_fl2
);
1096 * posix_lock_file - Apply a POSIX-style lock to a file
1097 * @filp: The file to apply the lock to
1098 * @fl: The lock to be applied
1099 * @conflock: Place to return a copy of the conflicting lock, if found.
1101 * Add a POSIX style lock to a file.
1102 * We merge adjacent & overlapping locks whenever possible.
1103 * POSIX locks are sorted by owner task, then by starting address
1105 * Note that if called with an FL_EXISTS argument, the caller may determine
1106 * whether or not a lock was successfully freed by testing the return
1107 * value for -ENOENT.
1109 int posix_lock_file(struct file
*filp
, struct file_lock
*fl
,
1110 struct file_lock
*conflock
)
1112 return __posix_lock_file(file_inode(filp
), fl
, conflock
);
1114 EXPORT_SYMBOL(posix_lock_file
);
1117 * posix_lock_file_wait - Apply a POSIX-style lock to a file
1118 * @filp: The file to apply the lock to
1119 * @fl: The lock to be applied
1121 * Add a POSIX style lock to a file.
1122 * We merge adjacent & overlapping locks whenever possible.
1123 * POSIX locks are sorted by owner task, then by starting address
1125 int posix_lock_file_wait(struct file
*filp
, struct file_lock
*fl
)
1130 error
= posix_lock_file(filp
, fl
, NULL
);
1131 if (error
!= FILE_LOCK_DEFERRED
)
1133 error
= wait_event_interruptible(fl
->fl_wait
, !fl
->fl_next
);
1137 locks_delete_block(fl
);
1142 EXPORT_SYMBOL(posix_lock_file_wait
);
1145 * locks_mandatory_locked - Check for an active lock
1146 * @file: the file to check
1148 * Searches the inode's list of locks to find any POSIX locks which conflict.
1149 * This function is called from locks_verify_locked() only.
1151 int locks_mandatory_locked(struct file
*file
)
1153 struct inode
*inode
= file_inode(file
);
1154 fl_owner_t owner
= current
->files
;
1155 struct file_lock
*fl
;
1158 * Search the lock list for this inode for any POSIX locks.
1160 spin_lock(&inode
->i_lock
);
1161 for (fl
= inode
->i_flock
; fl
!= NULL
; fl
= fl
->fl_next
) {
1164 if (fl
->fl_owner
!= owner
&& fl
->fl_owner
!= (fl_owner_t
)file
)
1167 spin_unlock(&inode
->i_lock
);
1168 return fl
? -EAGAIN
: 0;
1172 * locks_mandatory_area - Check for a conflicting lock
1173 * @read_write: %FLOCK_VERIFY_WRITE for exclusive access, %FLOCK_VERIFY_READ
1175 * @inode: the file to check
1176 * @filp: how the file was opened (if it was)
1177 * @offset: start of area to check
1178 * @count: length of area to check
1180 * Searches the inode's list of locks to find any POSIX locks which conflict.
1181 * This function is called from rw_verify_area() and
1182 * locks_verify_truncate().
1184 int locks_mandatory_area(int read_write
, struct inode
*inode
,
1185 struct file
*filp
, loff_t offset
,
1188 struct file_lock fl
;
1192 locks_init_lock(&fl
);
1193 fl
.fl_pid
= current
->tgid
;
1195 fl
.fl_flags
= FL_POSIX
| FL_ACCESS
;
1196 if (filp
&& !(filp
->f_flags
& O_NONBLOCK
))
1198 fl
.fl_type
= (read_write
== FLOCK_VERIFY_WRITE
) ? F_WRLCK
: F_RDLCK
;
1199 fl
.fl_start
= offset
;
1200 fl
.fl_end
= offset
+ count
- 1;
1204 fl
.fl_owner
= (fl_owner_t
)filp
;
1205 fl
.fl_flags
&= ~FL_SLEEP
;
1206 error
= __posix_lock_file(inode
, &fl
, NULL
);
1212 fl
.fl_flags
|= FL_SLEEP
;
1213 fl
.fl_owner
= current
->files
;
1214 error
= __posix_lock_file(inode
, &fl
, NULL
);
1215 if (error
!= FILE_LOCK_DEFERRED
)
1217 error
= wait_event_interruptible(fl
.fl_wait
, !fl
.fl_next
);
1220 * If we've been sleeping someone might have
1221 * changed the permissions behind our back.
1223 if (__mandatory_lock(inode
))
1227 locks_delete_block(&fl
);
1234 EXPORT_SYMBOL(locks_mandatory_area
);
1236 static void lease_clear_pending(struct file_lock
*fl
, int arg
)
1240 fl
->fl_flags
&= ~FL_UNLOCK_PENDING
;
1243 fl
->fl_flags
&= ~FL_DOWNGRADE_PENDING
;
1247 /* We already had a lease on this file; just change its type */
1248 int lease_modify(struct file_lock
**before
, int arg
)
1250 struct file_lock
*fl
= *before
;
1251 int error
= assign_type(fl
, arg
);
1255 lease_clear_pending(fl
, arg
);
1256 locks_wake_up_blocks(fl
);
1257 if (arg
== F_UNLCK
) {
1258 struct file
*filp
= fl
->fl_file
;
1261 filp
->f_owner
.signum
= 0;
1262 fasync_helper(0, fl
->fl_file
, 0, &fl
->fl_fasync
);
1263 if (fl
->fl_fasync
!= NULL
) {
1264 printk(KERN_ERR
"locks_delete_lock: fasync == %p\n", fl
->fl_fasync
);
1265 fl
->fl_fasync
= NULL
;
1267 locks_delete_lock(before
);
1272 EXPORT_SYMBOL(lease_modify
);
1274 static bool past_time(unsigned long then
)
1277 /* 0 is a special value meaning "this never expires": */
1279 return time_after(jiffies
, then
);
1282 static void time_out_leases(struct inode
*inode
)
1284 struct file_lock
**before
;
1285 struct file_lock
*fl
;
1287 before
= &inode
->i_flock
;
1288 while ((fl
= *before
) && IS_LEASE(fl
) && lease_breaking(fl
)) {
1289 if (past_time(fl
->fl_downgrade_time
))
1290 lease_modify(before
, F_RDLCK
);
1291 if (past_time(fl
->fl_break_time
))
1292 lease_modify(before
, F_UNLCK
);
1293 if (fl
== *before
) /* lease_modify may have freed fl */
1294 before
= &fl
->fl_next
;
1298 static bool leases_conflict(struct file_lock
*lease
, struct file_lock
*breaker
)
1300 if ((breaker
->fl_flags
& FL_DELEG
) && (lease
->fl_flags
& FL_LEASE
))
1302 return locks_conflict(breaker
, lease
);
1306 * __break_lease - revoke all outstanding leases on file
1307 * @inode: the inode of the file to return
1308 * @mode: O_RDONLY: break only write leases; O_WRONLY or O_RDWR:
1310 * @type: FL_LEASE: break leases and delegations; FL_DELEG: break
1313 * break_lease (inlined for speed) has checked there already is at least
1314 * some kind of lock (maybe a lease) on this file. Leases are broken on
1315 * a call to open() or truncate(). This function can sleep unless you
1316 * specified %O_NONBLOCK to your open().
1318 int __break_lease(struct inode
*inode
, unsigned int mode
, unsigned int type
)
1321 struct file_lock
*new_fl
, *flock
;
1322 struct file_lock
*fl
;
1323 unsigned long break_time
;
1324 int i_have_this_lease
= 0;
1325 bool lease_conflict
= false;
1326 int want_write
= (mode
& O_ACCMODE
) != O_RDONLY
;
1328 new_fl
= lease_alloc(NULL
, want_write
? F_WRLCK
: F_RDLCK
);
1330 return PTR_ERR(new_fl
);
1331 new_fl
->fl_flags
= type
;
1333 spin_lock(&inode
->i_lock
);
1335 time_out_leases(inode
);
1337 flock
= inode
->i_flock
;
1338 if ((flock
== NULL
) || !IS_LEASE(flock
))
1341 for (fl
= flock
; fl
&& IS_LEASE(fl
); fl
= fl
->fl_next
) {
1342 if (leases_conflict(fl
, new_fl
)) {
1343 lease_conflict
= true;
1344 if (fl
->fl_owner
== current
->files
)
1345 i_have_this_lease
= 1;
1348 if (!lease_conflict
)
1352 if (lease_break_time
> 0) {
1353 break_time
= jiffies
+ lease_break_time
* HZ
;
1354 if (break_time
== 0)
1355 break_time
++; /* so that 0 means no break time */
1358 for (fl
= flock
; fl
&& IS_LEASE(fl
); fl
= fl
->fl_next
) {
1359 if (!leases_conflict(fl
, new_fl
))
1362 if (fl
->fl_flags
& FL_UNLOCK_PENDING
)
1364 fl
->fl_flags
|= FL_UNLOCK_PENDING
;
1365 fl
->fl_break_time
= break_time
;
1367 if (lease_breaking(flock
))
1369 fl
->fl_flags
|= FL_DOWNGRADE_PENDING
;
1370 fl
->fl_downgrade_time
= break_time
;
1372 fl
->fl_lmops
->lm_break(fl
);
1375 if (i_have_this_lease
|| (mode
& O_NONBLOCK
)) {
1376 error
= -EWOULDBLOCK
;
1381 break_time
= flock
->fl_break_time
;
1382 if (break_time
!= 0)
1383 break_time
-= jiffies
;
1384 if (break_time
== 0)
1386 locks_insert_block(flock
, new_fl
);
1387 spin_unlock(&inode
->i_lock
);
1388 error
= wait_event_interruptible_timeout(new_fl
->fl_wait
,
1389 !new_fl
->fl_next
, break_time
);
1390 spin_lock(&inode
->i_lock
);
1391 locks_delete_block(new_fl
);
1394 time_out_leases(inode
);
1396 * Wait for the next conflicting lease that has not been
1399 for (flock
= inode
->i_flock
; flock
&& IS_LEASE(flock
);
1400 flock
= flock
->fl_next
) {
1401 if (leases_conflict(new_fl
, flock
))
1408 spin_unlock(&inode
->i_lock
);
1409 locks_free_lock(new_fl
);
1413 EXPORT_SYMBOL(__break_lease
);
1416 * lease_get_mtime - get the last modified time of an inode
1418 * @time: pointer to a timespec which will contain the last modified time
1420 * This is to force NFS clients to flush their caches for files with
1421 * exclusive leases. The justification is that if someone has an
1422 * exclusive lease, then they could be modifying it.
1424 void lease_get_mtime(struct inode
*inode
, struct timespec
*time
)
1426 struct file_lock
*flock
= inode
->i_flock
;
1427 if (flock
&& IS_LEASE(flock
) && (flock
->fl_type
== F_WRLCK
))
1428 *time
= current_fs_time(inode
->i_sb
);
1430 *time
= inode
->i_mtime
;
1433 EXPORT_SYMBOL(lease_get_mtime
);
1436 * fcntl_getlease - Enquire what lease is currently active
1439 * The value returned by this function will be one of
1440 * (if no lease break is pending):
1442 * %F_RDLCK to indicate a shared lease is held.
1444 * %F_WRLCK to indicate an exclusive lease is held.
1446 * %F_UNLCK to indicate no lease is held.
1448 * (if a lease break is pending):
1450 * %F_RDLCK to indicate an exclusive lease needs to be
1451 * changed to a shared lease (or removed).
1453 * %F_UNLCK to indicate the lease needs to be removed.
1455 * XXX: sfr & willy disagree over whether F_INPROGRESS
1456 * should be returned to userspace.
1458 int fcntl_getlease(struct file
*filp
)
1460 struct file_lock
*fl
;
1461 struct inode
*inode
= file_inode(filp
);
1464 spin_lock(&inode
->i_lock
);
1465 time_out_leases(file_inode(filp
));
1466 for (fl
= file_inode(filp
)->i_flock
; fl
&& IS_LEASE(fl
);
1468 if (fl
->fl_file
== filp
) {
1469 type
= target_leasetype(fl
);
1473 spin_unlock(&inode
->i_lock
);
1478 * check_conflicting_open - see if the given dentry points to a file that has
1479 * an existing open that would conflict with the
1481 * @dentry: dentry to check
1482 * @arg: type of lease that we're trying to acquire
1484 * Check to see if there's an existing open fd on this file that would
1485 * conflict with the lease we're trying to set.
1488 check_conflicting_open(const struct dentry
*dentry
, const long arg
)
1491 struct inode
*inode
= dentry
->d_inode
;
1493 if ((arg
== F_RDLCK
) && (atomic_read(&inode
->i_writecount
) > 0))
1496 if ((arg
== F_WRLCK
) && ((d_count(dentry
) > 1) ||
1497 (atomic_read(&inode
->i_count
) > 1)))
1503 static int generic_add_lease(struct file
*filp
, long arg
, struct file_lock
**flp
)
1505 struct file_lock
*fl
, **before
, **my_before
= NULL
, *lease
;
1506 struct dentry
*dentry
= filp
->f_path
.dentry
;
1507 struct inode
*inode
= dentry
->d_inode
;
1508 bool is_deleg
= (*flp
)->fl_flags
& FL_DELEG
;
1513 * In the delegation case we need mutual exclusion with
1514 * a number of operations that take the i_mutex. We trylock
1515 * because delegations are an optional optimization, and if
1516 * there's some chance of a conflict--we'd rather not
1517 * bother, maybe that's a sign this just isn't a good file to
1518 * hand out a delegation on.
1520 if (is_deleg
&& !mutex_trylock(&inode
->i_mutex
))
1523 if (is_deleg
&& arg
== F_WRLCK
) {
1524 /* Write delegations are not currently supported: */
1525 mutex_unlock(&inode
->i_mutex
);
1530 error
= check_conflicting_open(dentry
, arg
);
1535 * At this point, we know that if there is an exclusive
1536 * lease on this file, then we hold it on this filp
1537 * (otherwise our open of this file would have blocked).
1538 * And if we are trying to acquire an exclusive lease,
1539 * then the file is not open by anyone (including us)
1540 * except for this filp.
1543 for (before
= &inode
->i_flock
;
1544 ((fl
= *before
) != NULL
) && IS_LEASE(fl
);
1545 before
= &fl
->fl_next
) {
1546 if (fl
->fl_file
== filp
) {
1551 * No exclusive leases if someone else has a lease on
1557 * Modifying our existing lease is OK, but no getting a
1558 * new lease if someone else is opening for write:
1560 if (fl
->fl_flags
& FL_UNLOCK_PENDING
)
1564 if (my_before
!= NULL
) {
1565 error
= lease
->fl_lmops
->lm_change(my_before
, arg
);
1575 locks_insert_lock(before
, lease
);
1577 * The check in break_lease() is lockless. It's possible for another
1578 * open to race in after we did the earlier check for a conflicting
1579 * open but before the lease was inserted. Check again for a
1580 * conflicting open and cancel the lease if there is one.
1582 * We also add a barrier here to ensure that the insertion of the lock
1583 * precedes these checks.
1586 error
= check_conflicting_open(dentry
, arg
);
1588 locks_unlink_lock(flp
);
1591 mutex_unlock(&inode
->i_mutex
);
1595 static int generic_delete_lease(struct file
*filp
, struct file_lock
**flp
)
1597 struct file_lock
*fl
, **before
;
1598 struct dentry
*dentry
= filp
->f_path
.dentry
;
1599 struct inode
*inode
= dentry
->d_inode
;
1601 for (before
= &inode
->i_flock
;
1602 ((fl
= *before
) != NULL
) && IS_LEASE(fl
);
1603 before
= &fl
->fl_next
) {
1604 if (fl
->fl_file
!= filp
)
1606 return (*flp
)->fl_lmops
->lm_change(before
, F_UNLCK
);
1612 * generic_setlease - sets a lease on an open file
1613 * @filp: file pointer
1614 * @arg: type of lease to obtain
1615 * @flp: input - file_lock to use, output - file_lock inserted
1617 * The (input) flp->fl_lmops->lm_break function is required
1620 * Called with inode->i_lock held.
1622 int generic_setlease(struct file
*filp
, long arg
, struct file_lock
**flp
)
1624 struct dentry
*dentry
= filp
->f_path
.dentry
;
1625 struct inode
*inode
= dentry
->d_inode
;
1628 if ((!uid_eq(current_fsuid(), inode
->i_uid
)) && !capable(CAP_LEASE
))
1630 if (!S_ISREG(inode
->i_mode
))
1632 error
= security_file_lock(filp
, arg
);
1636 time_out_leases(inode
);
1638 BUG_ON(!(*flp
)->fl_lmops
->lm_break
);
1642 return generic_delete_lease(filp
, flp
);
1645 return generic_add_lease(filp
, arg
, flp
);
1650 EXPORT_SYMBOL(generic_setlease
);
1652 static int __vfs_setlease(struct file
*filp
, long arg
, struct file_lock
**lease
)
1654 if (filp
->f_op
->setlease
)
1655 return filp
->f_op
->setlease(filp
, arg
, lease
);
1657 return generic_setlease(filp
, arg
, lease
);
1661 * vfs_setlease - sets a lease on an open file
1662 * @filp: file pointer
1663 * @arg: type of lease to obtain
1664 * @lease: file_lock to use
1666 * Call this to establish a lease on the file.
1667 * The (*lease)->fl_lmops->lm_break operation must be set; if not,
1668 * break_lease will oops!
1670 * This will call the filesystem's setlease file method, if
1671 * defined. Note that there is no getlease method; instead, the
1672 * filesystem setlease method should call back to setlease() to
1673 * add a lease to the inode's lease list, where fcntl_getlease() can
1674 * find it. Since fcntl_getlease() only reports whether the current
1675 * task holds a lease, a cluster filesystem need only do this for
1676 * leases held by processes on this node.
1678 * There is also no break_lease method; filesystems that
1679 * handle their own leases should break leases themselves from the
1680 * filesystem's open, create, and (on truncate) setattr methods.
1682 * Warning: the only current setlease methods exist only to disable
1683 * leases in certain cases. More vfs changes may be required to
1684 * allow a full filesystem lease implementation.
1687 int vfs_setlease(struct file
*filp
, long arg
, struct file_lock
**lease
)
1689 struct inode
*inode
= file_inode(filp
);
1692 spin_lock(&inode
->i_lock
);
1693 error
= __vfs_setlease(filp
, arg
, lease
);
1694 spin_unlock(&inode
->i_lock
);
1698 EXPORT_SYMBOL_GPL(vfs_setlease
);
1700 static int do_fcntl_delete_lease(struct file
*filp
)
1702 struct file_lock fl
, *flp
= &fl
;
1704 lease_init(filp
, F_UNLCK
, flp
);
1706 return vfs_setlease(filp
, F_UNLCK
, &flp
);
1709 static int do_fcntl_add_lease(unsigned int fd
, struct file
*filp
, long arg
)
1711 struct file_lock
*fl
, *ret
;
1712 struct inode
*inode
= file_inode(filp
);
1713 struct fasync_struct
*new;
1716 fl
= lease_alloc(filp
, arg
);
1720 new = fasync_alloc();
1722 locks_free_lock(fl
);
1726 spin_lock(&inode
->i_lock
);
1727 error
= __vfs_setlease(filp
, arg
, &ret
);
1729 spin_unlock(&inode
->i_lock
);
1730 locks_free_lock(fl
);
1731 goto out_free_fasync
;
1734 locks_free_lock(fl
);
1737 * fasync_insert_entry() returns the old entry if any.
1738 * If there was no old entry, then it used 'new' and
1739 * inserted it into the fasync list. Clear new so that
1740 * we don't release it here.
1742 if (!fasync_insert_entry(fd
, filp
, &ret
->fl_fasync
, new))
1745 error
= __f_setown(filp
, task_pid(current
), PIDTYPE_PID
, 0);
1746 spin_unlock(&inode
->i_lock
);
1755 * fcntl_setlease - sets a lease on an open file
1756 * @fd: open file descriptor
1757 * @filp: file pointer
1758 * @arg: type of lease to obtain
1760 * Call this fcntl to establish a lease on the file.
1761 * Note that you also need to call %F_SETSIG to
1762 * receive a signal when the lease is broken.
1764 int fcntl_setlease(unsigned int fd
, struct file
*filp
, long arg
)
1767 return do_fcntl_delete_lease(filp
);
1768 return do_fcntl_add_lease(fd
, filp
, arg
);
1772 * flock_lock_file_wait - Apply a FLOCK-style lock to a file
1773 * @filp: The file to apply the lock to
1774 * @fl: The lock to be applied
1776 * Add a FLOCK style lock to a file.
1778 int flock_lock_file_wait(struct file
*filp
, struct file_lock
*fl
)
1783 error
= flock_lock_file(filp
, fl
);
1784 if (error
!= FILE_LOCK_DEFERRED
)
1786 error
= wait_event_interruptible(fl
->fl_wait
, !fl
->fl_next
);
1790 locks_delete_block(fl
);
1796 EXPORT_SYMBOL(flock_lock_file_wait
);
1799 * sys_flock: - flock() system call.
1800 * @fd: the file descriptor to lock.
1801 * @cmd: the type of lock to apply.
1803 * Apply a %FL_FLOCK style lock to an open file descriptor.
1804 * The @cmd can be one of
1806 * %LOCK_SH -- a shared lock.
1808 * %LOCK_EX -- an exclusive lock.
1810 * %LOCK_UN -- remove an existing lock.
1812 * %LOCK_MAND -- a `mandatory' flock. This exists to emulate Windows Share Modes.
1814 * %LOCK_MAND can be combined with %LOCK_READ or %LOCK_WRITE to allow other
1815 * processes read and write access respectively.
1817 SYSCALL_DEFINE2(flock
, unsigned int, fd
, unsigned int, cmd
)
1819 struct fd f
= fdget(fd
);
1820 struct file_lock
*lock
;
1821 int can_sleep
, unlock
;
1828 can_sleep
= !(cmd
& LOCK_NB
);
1830 unlock
= (cmd
== LOCK_UN
);
1832 if (!unlock
&& !(cmd
& LOCK_MAND
) &&
1833 !(f
.file
->f_mode
& (FMODE_READ
|FMODE_WRITE
)))
1836 error
= flock_make_lock(f
.file
, &lock
, cmd
);
1840 lock
->fl_flags
|= FL_SLEEP
;
1842 error
= security_file_lock(f
.file
, lock
->fl_type
);
1846 if (f
.file
->f_op
->flock
)
1847 error
= f
.file
->f_op
->flock(f
.file
,
1848 (can_sleep
) ? F_SETLKW
: F_SETLK
,
1851 error
= flock_lock_file_wait(f
.file
, lock
);
1854 locks_free_lock(lock
);
1863 * vfs_test_lock - test file byte range lock
1864 * @filp: The file to test lock for
1865 * @fl: The lock to test; also used to hold result
1867 * Returns -ERRNO on failure. Indicates presence of conflicting lock by
1868 * setting conf->fl_type to something other than F_UNLCK.
1870 int vfs_test_lock(struct file
*filp
, struct file_lock
*fl
)
1872 if (filp
->f_op
->lock
)
1873 return filp
->f_op
->lock(filp
, F_GETLK
, fl
);
1874 posix_test_lock(filp
, fl
);
1877 EXPORT_SYMBOL_GPL(vfs_test_lock
);
1879 static int posix_lock_to_flock(struct flock
*flock
, struct file_lock
*fl
)
1881 flock
->l_pid
= IS_OFDLCK(fl
) ? -1 : fl
->fl_pid
;
1882 #if BITS_PER_LONG == 32
1884 * Make sure we can represent the posix lock via
1885 * legacy 32bit flock.
1887 if (fl
->fl_start
> OFFT_OFFSET_MAX
)
1889 if (fl
->fl_end
!= OFFSET_MAX
&& fl
->fl_end
> OFFT_OFFSET_MAX
)
1892 flock
->l_start
= fl
->fl_start
;
1893 flock
->l_len
= fl
->fl_end
== OFFSET_MAX
? 0 :
1894 fl
->fl_end
- fl
->fl_start
+ 1;
1895 flock
->l_whence
= 0;
1896 flock
->l_type
= fl
->fl_type
;
1900 #if BITS_PER_LONG == 32
1901 static void posix_lock_to_flock64(struct flock64
*flock
, struct file_lock
*fl
)
1903 flock
->l_pid
= IS_OFDLCK(fl
) ? -1 : fl
->fl_pid
;
1904 flock
->l_start
= fl
->fl_start
;
1905 flock
->l_len
= fl
->fl_end
== OFFSET_MAX
? 0 :
1906 fl
->fl_end
- fl
->fl_start
+ 1;
1907 flock
->l_whence
= 0;
1908 flock
->l_type
= fl
->fl_type
;
1912 /* Report the first existing lock that would conflict with l.
1913 * This implements the F_GETLK command of fcntl().
1915 int fcntl_getlk(struct file
*filp
, unsigned int cmd
, struct flock __user
*l
)
1917 struct file_lock file_lock
;
1922 if (copy_from_user(&flock
, l
, sizeof(flock
)))
1925 if ((flock
.l_type
!= F_RDLCK
) && (flock
.l_type
!= F_WRLCK
))
1928 error
= flock_to_posix_lock(filp
, &file_lock
, &flock
);
1932 if (cmd
== F_OFD_GETLK
) {
1934 if (flock
.l_pid
!= 0)
1938 file_lock
.fl_flags
|= FL_OFDLCK
;
1939 file_lock
.fl_owner
= (fl_owner_t
)filp
;
1942 error
= vfs_test_lock(filp
, &file_lock
);
1946 flock
.l_type
= file_lock
.fl_type
;
1947 if (file_lock
.fl_type
!= F_UNLCK
) {
1948 error
= posix_lock_to_flock(&flock
, &file_lock
);
1953 if (!copy_to_user(l
, &flock
, sizeof(flock
)))
1960 * vfs_lock_file - file byte range lock
1961 * @filp: The file to apply the lock to
1962 * @cmd: type of locking operation (F_SETLK, F_GETLK, etc.)
1963 * @fl: The lock to be applied
1964 * @conf: Place to return a copy of the conflicting lock, if found.
1966 * A caller that doesn't care about the conflicting lock may pass NULL
1967 * as the final argument.
1969 * If the filesystem defines a private ->lock() method, then @conf will
1970 * be left unchanged; so a caller that cares should initialize it to
1971 * some acceptable default.
1973 * To avoid blocking kernel daemons, such as lockd, that need to acquire POSIX
1974 * locks, the ->lock() interface may return asynchronously, before the lock has
1975 * been granted or denied by the underlying filesystem, if (and only if)
1976 * lm_grant is set. Callers expecting ->lock() to return asynchronously
1977 * will only use F_SETLK, not F_SETLKW; they will set FL_SLEEP if (and only if)
1978 * the request is for a blocking lock. When ->lock() does return asynchronously,
1979 * it must return FILE_LOCK_DEFERRED, and call ->lm_grant() when the lock
1980 * request completes.
1981 * If the request is for non-blocking lock the file system should return
1982 * FILE_LOCK_DEFERRED then try to get the lock and call the callback routine
1983 * with the result. If the request timed out the callback routine will return a
1984 * nonzero return code and the file system should release the lock. The file
1985 * system is also responsible to keep a corresponding posix lock when it
1986 * grants a lock so the VFS can find out which locks are locally held and do
1987 * the correct lock cleanup when required.
1988 * The underlying filesystem must not drop the kernel lock or call
1989 * ->lm_grant() before returning to the caller with a FILE_LOCK_DEFERRED
1992 int vfs_lock_file(struct file
*filp
, unsigned int cmd
, struct file_lock
*fl
, struct file_lock
*conf
)
1994 if (filp
->f_op
->lock
)
1995 return filp
->f_op
->lock(filp
, cmd
, fl
);
1997 return posix_lock_file(filp
, fl
, conf
);
1999 EXPORT_SYMBOL_GPL(vfs_lock_file
);
2001 static int do_lock_file_wait(struct file
*filp
, unsigned int cmd
,
2002 struct file_lock
*fl
)
2006 error
= security_file_lock(filp
, fl
->fl_type
);
2011 error
= vfs_lock_file(filp
, cmd
, fl
, NULL
);
2012 if (error
!= FILE_LOCK_DEFERRED
)
2014 error
= wait_event_interruptible(fl
->fl_wait
, !fl
->fl_next
);
2018 locks_delete_block(fl
);
2025 /* Ensure that fl->fl_filp has compatible f_mode for F_SETLK calls */
2027 check_fmode_for_setlk(struct file_lock
*fl
)
2029 switch (fl
->fl_type
) {
2031 if (!(fl
->fl_file
->f_mode
& FMODE_READ
))
2035 if (!(fl
->fl_file
->f_mode
& FMODE_WRITE
))
2041 /* Apply the lock described by l to an open file descriptor.
2042 * This implements both the F_SETLK and F_SETLKW commands of fcntl().
2044 int fcntl_setlk(unsigned int fd
, struct file
*filp
, unsigned int cmd
,
2045 struct flock __user
*l
)
2047 struct file_lock
*file_lock
= locks_alloc_lock();
2049 struct inode
*inode
;
2053 if (file_lock
== NULL
)
2057 * This might block, so we do it before checking the inode.
2060 if (copy_from_user(&flock
, l
, sizeof(flock
)))
2063 inode
= file_inode(filp
);
2065 /* Don't allow mandatory locks on files that may be memory mapped
2068 if (mandatory_lock(inode
) && mapping_writably_mapped(filp
->f_mapping
)) {
2074 error
= flock_to_posix_lock(filp
, file_lock
, &flock
);
2078 error
= check_fmode_for_setlk(file_lock
);
2083 * If the cmd is requesting file-private locks, then set the
2084 * FL_OFDLCK flag and override the owner.
2089 if (flock
.l_pid
!= 0)
2093 file_lock
->fl_flags
|= FL_OFDLCK
;
2094 file_lock
->fl_owner
= (fl_owner_t
)filp
;
2098 if (flock
.l_pid
!= 0)
2102 file_lock
->fl_flags
|= FL_OFDLCK
;
2103 file_lock
->fl_owner
= (fl_owner_t
)filp
;
2106 file_lock
->fl_flags
|= FL_SLEEP
;
2109 error
= do_lock_file_wait(filp
, cmd
, file_lock
);
2112 * Attempt to detect a close/fcntl race and recover by
2113 * releasing the lock that was just acquired.
2116 * we need that spin_lock here - it prevents reordering between
2117 * update of inode->i_flock and check for it done in close().
2118 * rcu_read_lock() wouldn't do.
2120 spin_lock(¤t
->files
->file_lock
);
2122 spin_unlock(¤t
->files
->file_lock
);
2123 if (!error
&& f
!= filp
&& flock
.l_type
!= F_UNLCK
) {
2124 flock
.l_type
= F_UNLCK
;
2129 locks_free_lock(file_lock
);
2133 #if BITS_PER_LONG == 32
2134 /* Report the first existing lock that would conflict with l.
2135 * This implements the F_GETLK command of fcntl().
2137 int fcntl_getlk64(struct file
*filp
, unsigned int cmd
, struct flock64 __user
*l
)
2139 struct file_lock file_lock
;
2140 struct flock64 flock
;
2144 if (copy_from_user(&flock
, l
, sizeof(flock
)))
2147 if ((flock
.l_type
!= F_RDLCK
) && (flock
.l_type
!= F_WRLCK
))
2150 error
= flock64_to_posix_lock(filp
, &file_lock
, &flock
);
2154 if (cmd
== F_OFD_GETLK
) {
2156 if (flock
.l_pid
!= 0)
2160 file_lock
.fl_flags
|= FL_OFDLCK
;
2161 file_lock
.fl_owner
= (fl_owner_t
)filp
;
2164 error
= vfs_test_lock(filp
, &file_lock
);
2168 flock
.l_type
= file_lock
.fl_type
;
2169 if (file_lock
.fl_type
!= F_UNLCK
)
2170 posix_lock_to_flock64(&flock
, &file_lock
);
2173 if (!copy_to_user(l
, &flock
, sizeof(flock
)))
2180 /* Apply the lock described by l to an open file descriptor.
2181 * This implements both the F_SETLK and F_SETLKW commands of fcntl().
2183 int fcntl_setlk64(unsigned int fd
, struct file
*filp
, unsigned int cmd
,
2184 struct flock64 __user
*l
)
2186 struct file_lock
*file_lock
= locks_alloc_lock();
2187 struct flock64 flock
;
2188 struct inode
*inode
;
2192 if (file_lock
== NULL
)
2196 * This might block, so we do it before checking the inode.
2199 if (copy_from_user(&flock
, l
, sizeof(flock
)))
2202 inode
= file_inode(filp
);
2204 /* Don't allow mandatory locks on files that may be memory mapped
2207 if (mandatory_lock(inode
) && mapping_writably_mapped(filp
->f_mapping
)) {
2213 error
= flock64_to_posix_lock(filp
, file_lock
, &flock
);
2217 error
= check_fmode_for_setlk(file_lock
);
2222 * If the cmd is requesting file-private locks, then set the
2223 * FL_OFDLCK flag and override the owner.
2228 if (flock
.l_pid
!= 0)
2232 file_lock
->fl_flags
|= FL_OFDLCK
;
2233 file_lock
->fl_owner
= (fl_owner_t
)filp
;
2237 if (flock
.l_pid
!= 0)
2241 file_lock
->fl_flags
|= FL_OFDLCK
;
2242 file_lock
->fl_owner
= (fl_owner_t
)filp
;
2245 file_lock
->fl_flags
|= FL_SLEEP
;
2248 error
= do_lock_file_wait(filp
, cmd
, file_lock
);
2251 * Attempt to detect a close/fcntl race and recover by
2252 * releasing the lock that was just acquired.
2254 spin_lock(¤t
->files
->file_lock
);
2256 spin_unlock(¤t
->files
->file_lock
);
2257 if (!error
&& f
!= filp
&& flock
.l_type
!= F_UNLCK
) {
2258 flock
.l_type
= F_UNLCK
;
2263 locks_free_lock(file_lock
);
2266 #endif /* BITS_PER_LONG == 32 */
2269 * This function is called when the file is being removed
2270 * from the task's fd array. POSIX locks belonging to this task
2271 * are deleted at this time.
2273 void locks_remove_posix(struct file
*filp
, fl_owner_t owner
)
2275 struct file_lock lock
;
2278 * If there are no locks held on this file, we don't need to call
2279 * posix_lock_file(). Another process could be setting a lock on this
2280 * file at the same time, but we wouldn't remove that lock anyway.
2282 if (!file_inode(filp
)->i_flock
)
2285 lock
.fl_type
= F_UNLCK
;
2286 lock
.fl_flags
= FL_POSIX
| FL_CLOSE
;
2288 lock
.fl_end
= OFFSET_MAX
;
2289 lock
.fl_owner
= owner
;
2290 lock
.fl_pid
= current
->tgid
;
2291 lock
.fl_file
= filp
;
2293 lock
.fl_lmops
= NULL
;
2295 vfs_lock_file(filp
, F_SETLK
, &lock
, NULL
);
2297 if (lock
.fl_ops
&& lock
.fl_ops
->fl_release_private
)
2298 lock
.fl_ops
->fl_release_private(&lock
);
2301 EXPORT_SYMBOL(locks_remove_posix
);
2304 * This function is called on the last close of an open file.
2306 void locks_remove_file(struct file
*filp
)
2308 struct inode
* inode
= file_inode(filp
);
2309 struct file_lock
*fl
;
2310 struct file_lock
**before
;
2312 if (!inode
->i_flock
)
2315 locks_remove_posix(filp
, (fl_owner_t
)filp
);
2317 if (filp
->f_op
->flock
) {
2318 struct file_lock fl
= {
2319 .fl_pid
= current
->tgid
,
2321 .fl_flags
= FL_FLOCK
,
2323 .fl_end
= OFFSET_MAX
,
2325 filp
->f_op
->flock(filp
, F_SETLKW
, &fl
);
2326 if (fl
.fl_ops
&& fl
.fl_ops
->fl_release_private
)
2327 fl
.fl_ops
->fl_release_private(&fl
);
2330 spin_lock(&inode
->i_lock
);
2331 before
= &inode
->i_flock
;
2333 while ((fl
= *before
) != NULL
) {
2334 if (fl
->fl_file
== filp
) {
2336 lease_modify(before
, F_UNLCK
);
2341 * There's a leftover lock on the list of a type that
2342 * we didn't expect to see. Most likely a classic
2343 * POSIX lock that ended up not getting released
2344 * properly, or that raced onto the list somehow. Log
2345 * some info about it and then just remove it from
2349 "leftover lock: dev=%u:%u ino=%lu type=%hhd flags=0x%x start=%lld end=%lld\n",
2350 MAJOR(inode
->i_sb
->s_dev
),
2351 MINOR(inode
->i_sb
->s_dev
), inode
->i_ino
,
2352 fl
->fl_type
, fl
->fl_flags
,
2353 fl
->fl_start
, fl
->fl_end
);
2355 locks_delete_lock(before
);
2358 before
= &fl
->fl_next
;
2360 spin_unlock(&inode
->i_lock
);
2364 * posix_unblock_lock - stop waiting for a file lock
2365 * @waiter: the lock which was waiting
2367 * lockd needs to block waiting for locks.
2370 posix_unblock_lock(struct file_lock
*waiter
)
2374 spin_lock(&blocked_lock_lock
);
2375 if (waiter
->fl_next
)
2376 __locks_delete_block(waiter
);
2379 spin_unlock(&blocked_lock_lock
);
2382 EXPORT_SYMBOL(posix_unblock_lock
);
2385 * vfs_cancel_lock - file byte range unblock lock
2386 * @filp: The file to apply the unblock to
2387 * @fl: The lock to be unblocked
2389 * Used by lock managers to cancel blocked requests
2391 int vfs_cancel_lock(struct file
*filp
, struct file_lock
*fl
)
2393 if (filp
->f_op
->lock
)
2394 return filp
->f_op
->lock(filp
, F_CANCELLK
, fl
);
2398 EXPORT_SYMBOL_GPL(vfs_cancel_lock
);
2400 #ifdef CONFIG_PROC_FS
2401 #include <linux/proc_fs.h>
2402 #include <linux/seq_file.h>
2404 struct locks_iterator
{
2409 static void lock_get_status(struct seq_file
*f
, struct file_lock
*fl
,
2410 loff_t id
, char *pfx
)
2412 struct inode
*inode
= NULL
;
2413 unsigned int fl_pid
;
2416 fl_pid
= pid_vnr(fl
->fl_nspid
);
2418 fl_pid
= fl
->fl_pid
;
2420 if (fl
->fl_file
!= NULL
)
2421 inode
= file_inode(fl
->fl_file
);
2423 seq_printf(f
, "%lld:%s ", id
, pfx
);
2425 if (fl
->fl_flags
& FL_ACCESS
)
2426 seq_printf(f
, "ACCESS");
2427 else if (IS_OFDLCK(fl
))
2428 seq_printf(f
, "OFDLCK");
2430 seq_printf(f
, "POSIX ");
2432 seq_printf(f
, " %s ",
2433 (inode
== NULL
) ? "*NOINODE*" :
2434 mandatory_lock(inode
) ? "MANDATORY" : "ADVISORY ");
2435 } else if (IS_FLOCK(fl
)) {
2436 if (fl
->fl_type
& LOCK_MAND
) {
2437 seq_printf(f
, "FLOCK MSNFS ");
2439 seq_printf(f
, "FLOCK ADVISORY ");
2441 } else if (IS_LEASE(fl
)) {
2442 seq_printf(f
, "LEASE ");
2443 if (lease_breaking(fl
))
2444 seq_printf(f
, "BREAKING ");
2445 else if (fl
->fl_file
)
2446 seq_printf(f
, "ACTIVE ");
2448 seq_printf(f
, "BREAKER ");
2450 seq_printf(f
, "UNKNOWN UNKNOWN ");
2452 if (fl
->fl_type
& LOCK_MAND
) {
2453 seq_printf(f
, "%s ",
2454 (fl
->fl_type
& LOCK_READ
)
2455 ? (fl
->fl_type
& LOCK_WRITE
) ? "RW " : "READ "
2456 : (fl
->fl_type
& LOCK_WRITE
) ? "WRITE" : "NONE ");
2458 seq_printf(f
, "%s ",
2459 (lease_breaking(fl
))
2460 ? (fl
->fl_type
== F_UNLCK
) ? "UNLCK" : "READ "
2461 : (fl
->fl_type
== F_WRLCK
) ? "WRITE" : "READ ");
2464 #ifdef WE_CAN_BREAK_LSLK_NOW
2465 seq_printf(f
, "%d %s:%ld ", fl_pid
,
2466 inode
->i_sb
->s_id
, inode
->i_ino
);
2468 /* userspace relies on this representation of dev_t ;-( */
2469 seq_printf(f
, "%d %02x:%02x:%ld ", fl_pid
,
2470 MAJOR(inode
->i_sb
->s_dev
),
2471 MINOR(inode
->i_sb
->s_dev
), inode
->i_ino
);
2474 seq_printf(f
, "%d <none>:0 ", fl_pid
);
2477 if (fl
->fl_end
== OFFSET_MAX
)
2478 seq_printf(f
, "%Ld EOF\n", fl
->fl_start
);
2480 seq_printf(f
, "%Ld %Ld\n", fl
->fl_start
, fl
->fl_end
);
2482 seq_printf(f
, "0 EOF\n");
2486 static int locks_show(struct seq_file
*f
, void *v
)
2488 struct locks_iterator
*iter
= f
->private;
2489 struct file_lock
*fl
, *bfl
;
2491 fl
= hlist_entry(v
, struct file_lock
, fl_link
);
2493 lock_get_status(f
, fl
, iter
->li_pos
, "");
2495 list_for_each_entry(bfl
, &fl
->fl_block
, fl_block
)
2496 lock_get_status(f
, bfl
, iter
->li_pos
, " ->");
2501 static void *locks_start(struct seq_file
*f
, loff_t
*pos
)
2502 __acquires(&blocked_lock_lock
)
2504 struct locks_iterator
*iter
= f
->private;
2506 iter
->li_pos
= *pos
+ 1;
2507 lg_global_lock(&file_lock_lglock
);
2508 spin_lock(&blocked_lock_lock
);
2509 return seq_hlist_start_percpu(&file_lock_list
, &iter
->li_cpu
, *pos
);
2512 static void *locks_next(struct seq_file
*f
, void *v
, loff_t
*pos
)
2514 struct locks_iterator
*iter
= f
->private;
2517 return seq_hlist_next_percpu(v
, &file_lock_list
, &iter
->li_cpu
, pos
);
2520 static void locks_stop(struct seq_file
*f
, void *v
)
2521 __releases(&blocked_lock_lock
)
2523 spin_unlock(&blocked_lock_lock
);
2524 lg_global_unlock(&file_lock_lglock
);
2527 static const struct seq_operations locks_seq_operations
= {
2528 .start
= locks_start
,
2534 static int locks_open(struct inode
*inode
, struct file
*filp
)
2536 return seq_open_private(filp
, &locks_seq_operations
,
2537 sizeof(struct locks_iterator
));
2540 static const struct file_operations proc_locks_operations
= {
2543 .llseek
= seq_lseek
,
2544 .release
= seq_release_private
,
2547 static int __init
proc_locks_init(void)
2549 proc_create("locks", 0, NULL
, &proc_locks_operations
);
2552 module_init(proc_locks_init
);
2556 * lock_may_read - checks that the region is free of locks
2557 * @inode: the inode that is being read
2558 * @start: the first byte to read
2559 * @len: the number of bytes to read
2561 * Emulates Windows locking requirements. Whole-file
2562 * mandatory locks (share modes) can prohibit a read and
2563 * byte-range POSIX locks can prohibit a read if they overlap.
2565 * N.B. this function is only ever called
2566 * from knfsd and ownership of locks is never checked.
2568 int lock_may_read(struct inode
*inode
, loff_t start
, unsigned long len
)
2570 struct file_lock
*fl
;
2573 spin_lock(&inode
->i_lock
);
2574 for (fl
= inode
->i_flock
; fl
!= NULL
; fl
= fl
->fl_next
) {
2576 if (fl
->fl_type
== F_RDLCK
)
2578 if ((fl
->fl_end
< start
) || (fl
->fl_start
> (start
+ len
)))
2580 } else if (IS_FLOCK(fl
)) {
2581 if (!(fl
->fl_type
& LOCK_MAND
))
2583 if (fl
->fl_type
& LOCK_READ
)
2590 spin_unlock(&inode
->i_lock
);
2594 EXPORT_SYMBOL(lock_may_read
);
2597 * lock_may_write - checks that the region is free of locks
2598 * @inode: the inode that is being written
2599 * @start: the first byte to write
2600 * @len: the number of bytes to write
2602 * Emulates Windows locking requirements. Whole-file
2603 * mandatory locks (share modes) can prohibit a write and
2604 * byte-range POSIX locks can prohibit a write if they overlap.
2606 * N.B. this function is only ever called
2607 * from knfsd and ownership of locks is never checked.
2609 int lock_may_write(struct inode
*inode
, loff_t start
, unsigned long len
)
2611 struct file_lock
*fl
;
2614 spin_lock(&inode
->i_lock
);
2615 for (fl
= inode
->i_flock
; fl
!= NULL
; fl
= fl
->fl_next
) {
2617 if ((fl
->fl_end
< start
) || (fl
->fl_start
> (start
+ len
)))
2619 } else if (IS_FLOCK(fl
)) {
2620 if (!(fl
->fl_type
& LOCK_MAND
))
2622 if (fl
->fl_type
& LOCK_WRITE
)
2629 spin_unlock(&inode
->i_lock
);
2633 EXPORT_SYMBOL(lock_may_write
);
2635 static int __init
filelock_init(void)
2639 filelock_cache
= kmem_cache_create("file_lock_cache",
2640 sizeof(struct file_lock
), 0, SLAB_PANIC
, NULL
);
2642 lg_lock_init(&file_lock_lglock
, "file_lock_lglock");
2644 for_each_possible_cpu(i
)
2645 INIT_HLIST_HEAD(per_cpu_ptr(&file_lock_list
, i
));
2650 core_initcall(filelock_init
);