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/mandatory.txt' for details.
64 * Andy Walker (andy@lysaker.kvaerner.no), April 06, 1996.
66 * Don't allow mandatory locks on mmap()'ed files. Added simple functions to
67 * check if a file has mandatory locks, used by mmap(), open() and creat() to
68 * see if system call should be rejected. Ref. HP-UX/SunOS/Solaris Reference
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/fs.h>
120 #include <linux/init.h>
121 #include <linux/module.h>
122 #include <linux/security.h>
123 #include <linux/slab.h>
124 #include <linux/smp_lock.h>
125 #include <linux/time.h>
127 #include <asm/semaphore.h>
128 #include <asm/uaccess.h>
130 #define IS_POSIX(fl) (fl->fl_flags & FL_POSIX)
131 #define IS_FLOCK(fl) (fl->fl_flags & FL_FLOCK)
132 #define IS_LEASE(fl) (fl->fl_flags & FL_LEASE)
134 int leases_enable = 1;
135 int lease_break_time = 45;
137 #define for_each_lock(inode, lockp) \
138 for (lockp = &inode->i_flock; *lockp != NULL; lockp = &(*lockp)->fl_next)
140 LIST_HEAD(file_lock_list);
142 EXPORT_SYMBOL(file_lock_list);
144 static LIST_HEAD(blocked_list);
146 static kmem_cache_t *filelock_cache;
148 /* Allocate an empty lock structure. */
149 static struct file_lock *locks_alloc_lock(void)
151 return kmem_cache_alloc(filelock_cache, SLAB_KERNEL);
154 /* Free a lock which is not in use. */
155 static inline void locks_free_lock(struct file_lock *fl)
161 if (waitqueue_active(&fl->fl_wait))
162 panic("Attempting to free lock with active wait queue");
164 if (!list_empty(&fl->fl_block))
165 panic("Attempting to free lock with active block list");
167 if (!list_empty(&fl->fl_link))
168 panic("Attempting to free lock on active lock list");
171 if (fl->fl_ops->fl_release_private)
172 fl->fl_ops->fl_release_private(fl);
177 kmem_cache_free(filelock_cache, fl);
180 void locks_init_lock(struct file_lock *fl)
182 INIT_LIST_HEAD(&fl->fl_link);
183 INIT_LIST_HEAD(&fl->fl_block);
184 init_waitqueue_head(&fl->fl_wait);
186 fl->fl_fasync = NULL;
192 fl->fl_start = fl->fl_end = 0;
197 EXPORT_SYMBOL(locks_init_lock);
200 * Initialises the fields of the file lock which are invariant for
203 static void init_once(void *foo, kmem_cache_t *cache, unsigned long flags)
205 struct file_lock *lock = (struct file_lock *) foo;
207 if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) !=
208 SLAB_CTOR_CONSTRUCTOR)
211 locks_init_lock(lock);
215 * Initialize a new lock from an existing file_lock structure.
217 void locks_copy_lock(struct file_lock *new, struct file_lock *fl)
219 new->fl_owner = fl->fl_owner;
220 new->fl_pid = fl->fl_pid;
221 new->fl_file = fl->fl_file;
222 new->fl_flags = fl->fl_flags;
223 new->fl_type = fl->fl_type;
224 new->fl_start = fl->fl_start;
225 new->fl_end = fl->fl_end;
226 new->fl_ops = fl->fl_ops;
227 new->fl_lmops = fl->fl_lmops;
228 if (fl->fl_ops && fl->fl_ops->fl_copy_lock)
229 fl->fl_ops->fl_copy_lock(new, fl);
232 EXPORT_SYMBOL(locks_copy_lock);
234 static inline int flock_translate_cmd(int cmd) {
236 return cmd & (LOCK_MAND | LOCK_RW);
248 /* Fill in a file_lock structure with an appropriate FLOCK lock. */
249 static int flock_make_lock(struct file *filp, struct file_lock **lock,
252 struct file_lock *fl;
253 int type = flock_translate_cmd(cmd);
257 fl = locks_alloc_lock();
262 fl->fl_pid = current->tgid;
263 fl->fl_flags = FL_FLOCK;
265 fl->fl_end = OFFSET_MAX;
271 static int assign_type(struct file_lock *fl, int type)
285 /* Verify a "struct flock" and copy it to a "struct file_lock" as a POSIX
288 static int flock_to_posix_lock(struct file *filp, struct file_lock *fl,
293 switch (l->l_whence) {
301 start = i_size_read(filp->f_dentry->d_inode);
307 /* POSIX-1996 leaves the case l->l_len < 0 undefined;
308 POSIX-2001 defines it. */
310 end = start + l->l_len - 1;
318 if (l->l_len > 0 && end < 0)
321 fl->fl_start = start; /* we record the absolute position */
324 fl->fl_end = OFFSET_MAX;
326 fl->fl_owner = current->files;
327 fl->fl_pid = current->tgid;
329 fl->fl_flags = FL_POSIX;
333 return assign_type(fl, l->l_type);
336 #if BITS_PER_LONG == 32
337 static int flock64_to_posix_lock(struct file *filp, struct file_lock *fl,
342 switch (l->l_whence) {
350 start = i_size_read(filp->f_dentry->d_inode);
356 if (((start += l->l_start) < 0) || (l->l_len < 0))
358 fl->fl_end = start + l->l_len - 1;
359 if (l->l_len > 0 && fl->fl_end < 0)
361 fl->fl_start = start; /* we record the absolute position */
363 fl->fl_end = OFFSET_MAX;
365 fl->fl_owner = current->files;
366 fl->fl_pid = current->tgid;
368 fl->fl_flags = FL_POSIX;
376 fl->fl_type = l->l_type;
386 /* Allocate a file_lock initialised to this type of lease */
387 static int lease_alloc(struct file *filp, int type, struct file_lock **flp)
389 struct file_lock *fl = locks_alloc_lock();
393 fl->fl_owner = current->files;
394 fl->fl_pid = current->tgid;
397 fl->fl_flags = FL_LEASE;
398 if (assign_type(fl, type) != 0) {
403 fl->fl_end = OFFSET_MAX;
411 /* Check if two locks overlap each other.
413 static inline int locks_overlap(struct file_lock *fl1, struct file_lock *fl2)
415 return ((fl1->fl_end >= fl2->fl_start) &&
416 (fl2->fl_end >= fl1->fl_start));
420 * Check whether two locks have the same owner.
423 posix_same_owner(struct file_lock *fl1, struct file_lock *fl2)
425 if (fl1->fl_lmops && fl1->fl_lmops->fl_compare_owner)
426 return fl2->fl_lmops == fl1->fl_lmops &&
427 fl1->fl_lmops->fl_compare_owner(fl1, fl2);
428 return fl1->fl_owner == fl2->fl_owner;
431 /* Remove waiter from blocker's block list.
432 * When blocker ends up pointing to itself then the list is empty.
434 static inline void __locks_delete_block(struct file_lock *waiter)
436 list_del_init(&waiter->fl_block);
437 list_del_init(&waiter->fl_link);
438 waiter->fl_next = NULL;
443 static void locks_delete_block(struct file_lock *waiter)
446 __locks_delete_block(waiter);
450 /* Insert waiter into blocker's block list.
451 * We use a circular list so that processes can be easily woken up in
452 * the order they blocked. The documentation doesn't require this but
453 * it seems like the reasonable thing to do.
455 static void locks_insert_block(struct file_lock *blocker,
456 struct file_lock *waiter)
458 if (!list_empty(&waiter->fl_block)) {
459 printk(KERN_ERR "locks_insert_block: removing duplicated lock "
460 "(pid=%d %Ld-%Ld type=%d)\n", waiter->fl_pid,
461 waiter->fl_start, waiter->fl_end, waiter->fl_type);
462 __locks_delete_block(waiter);
464 list_add_tail(&waiter->fl_block, &blocker->fl_block);
465 waiter->fl_next = blocker;
466 if (IS_POSIX(blocker))
467 list_add(&waiter->fl_link, &blocked_list);
470 /* Wake up processes blocked waiting for blocker.
471 * If told to wait then schedule the processes until the block list
472 * is empty, otherwise empty the block list ourselves.
474 static void locks_wake_up_blocks(struct file_lock *blocker)
476 while (!list_empty(&blocker->fl_block)) {
477 struct file_lock *waiter = list_entry(blocker->fl_block.next,
478 struct file_lock, fl_block);
479 __locks_delete_block(waiter);
480 if (waiter->fl_lmops && waiter->fl_lmops->fl_notify)
481 waiter->fl_lmops->fl_notify(waiter);
483 wake_up(&waiter->fl_wait);
487 /* Insert file lock fl into an inode's lock list at the position indicated
488 * by pos. At the same time add the lock to the global file lock list.
490 static void locks_insert_lock(struct file_lock **pos, struct file_lock *fl)
492 list_add(&fl->fl_link, &file_lock_list);
494 /* insert into file's list */
498 if (fl->fl_ops && fl->fl_ops->fl_insert)
499 fl->fl_ops->fl_insert(fl);
503 * Delete a lock and then free it.
504 * Wake up processes that are blocked waiting for this lock,
505 * notify the FS that the lock has been cleared and
506 * finally free the lock.
508 static void locks_delete_lock(struct file_lock **thisfl_p)
510 struct file_lock *fl = *thisfl_p;
512 *thisfl_p = fl->fl_next;
514 list_del_init(&fl->fl_link);
516 fasync_helper(0, fl->fl_file, 0, &fl->fl_fasync);
517 if (fl->fl_fasync != NULL) {
518 printk(KERN_ERR "locks_delete_lock: fasync == %p\n", fl->fl_fasync);
519 fl->fl_fasync = NULL;
522 if (fl->fl_ops && fl->fl_ops->fl_remove)
523 fl->fl_ops->fl_remove(fl);
525 locks_wake_up_blocks(fl);
529 /* Determine if lock sys_fl blocks lock caller_fl. Common functionality
530 * checks for shared/exclusive status of overlapping locks.
532 static int locks_conflict(struct file_lock *caller_fl, struct file_lock *sys_fl)
534 if (sys_fl->fl_type == F_WRLCK)
536 if (caller_fl->fl_type == F_WRLCK)
541 /* Determine if lock sys_fl blocks lock caller_fl. POSIX specific
542 * checking before calling the locks_conflict().
544 static int posix_locks_conflict(struct file_lock *caller_fl, struct file_lock *sys_fl)
546 /* POSIX locks owned by the same process do not conflict with
549 if (!IS_POSIX(sys_fl) || posix_same_owner(caller_fl, sys_fl))
552 /* Check whether they overlap */
553 if (!locks_overlap(caller_fl, sys_fl))
556 return (locks_conflict(caller_fl, sys_fl));
559 /* Determine if lock sys_fl blocks lock caller_fl. FLOCK specific
560 * checking before calling the locks_conflict().
562 static int flock_locks_conflict(struct file_lock *caller_fl, struct file_lock *sys_fl)
564 /* FLOCK locks referring to the same filp do not conflict with
567 if (!IS_FLOCK(sys_fl) || (caller_fl->fl_file == sys_fl->fl_file))
569 if ((caller_fl->fl_type & LOCK_MAND) || (sys_fl->fl_type & LOCK_MAND))
572 return (locks_conflict(caller_fl, sys_fl));
575 static int interruptible_sleep_on_locked(wait_queue_head_t *fl_wait, int timeout)
578 DECLARE_WAITQUEUE(wait, current);
580 __set_current_state(TASK_INTERRUPTIBLE);
581 add_wait_queue(fl_wait, &wait);
585 result = schedule_timeout(timeout);
586 if (signal_pending(current))
587 result = -ERESTARTSYS;
588 remove_wait_queue(fl_wait, &wait);
589 __set_current_state(TASK_RUNNING);
593 static int locks_block_on_timeout(struct file_lock *blocker, struct file_lock *waiter, int time)
596 locks_insert_block(blocker, waiter);
597 result = interruptible_sleep_on_locked(&waiter->fl_wait, time);
598 __locks_delete_block(waiter);
603 posix_test_lock(struct file *filp, struct file_lock *fl)
605 struct file_lock *cfl;
608 for (cfl = filp->f_dentry->d_inode->i_flock; cfl; cfl = cfl->fl_next) {
611 if (posix_locks_conflict(cfl, fl))
619 EXPORT_SYMBOL(posix_test_lock);
621 /* This function tests for deadlock condition before putting a process to
622 * sleep. The detection scheme is no longer recursive. Recursive was neat,
623 * but dangerous - we risked stack corruption if the lock data was bad, or
624 * if the recursion was too deep for any other reason.
626 * We rely on the fact that a task can only be on one lock's wait queue
627 * at a time. When we find blocked_task on a wait queue we can re-search
628 * with blocked_task equal to that queue's owner, until either blocked_task
629 * isn't found, or blocked_task is found on a queue owned by my_task.
631 * Note: the above assumption may not be true when handling lock requests
632 * from a broken NFS client. But broken NFS clients have a lot more to
633 * worry about than proper deadlock detection anyway... --okir
635 int posix_locks_deadlock(struct file_lock *caller_fl,
636 struct file_lock *block_fl)
638 struct list_head *tmp;
641 if (posix_same_owner(caller_fl, block_fl))
643 list_for_each(tmp, &blocked_list) {
644 struct file_lock *fl = list_entry(tmp, struct file_lock, fl_link);
645 if (posix_same_owner(fl, block_fl)) {
654 EXPORT_SYMBOL(posix_locks_deadlock);
656 /* Try to create a FLOCK lock on filp. We always insert new FLOCK locks
657 * at the head of the list, but that's secret knowledge known only to
658 * flock_lock_file and posix_lock_file.
660 static int flock_lock_file(struct file *filp, struct file_lock *new_fl)
662 struct file_lock **before;
663 struct inode * inode = filp->f_dentry->d_inode;
668 for_each_lock(inode, before) {
669 struct file_lock *fl = *before;
674 if (filp != fl->fl_file)
676 if (new_fl->fl_type == fl->fl_type)
679 locks_delete_lock(before);
684 if (new_fl->fl_type == F_UNLCK)
688 * If a higher-priority process was blocked on the old file lock,
689 * give it the opportunity to lock the file.
695 for_each_lock(inode, before) {
696 struct file_lock *fl = *before;
701 if (!flock_locks_conflict(new_fl, fl))
704 if (new_fl->fl_flags & FL_SLEEP) {
705 locks_insert_block(fl, new_fl);
709 locks_insert_lock(&inode->i_flock, new_fl);
717 EXPORT_SYMBOL(posix_lock_file);
719 static int __posix_lock_file(struct inode *inode, struct file_lock *request)
721 struct file_lock *fl;
722 struct file_lock *new_fl, *new_fl2;
723 struct file_lock *left = NULL;
724 struct file_lock *right = NULL;
725 struct file_lock **before;
726 int error, added = 0;
729 * We may need two file_lock structures for this operation,
730 * so we get them in advance to avoid races.
732 new_fl = locks_alloc_lock();
733 new_fl2 = locks_alloc_lock();
736 if (request->fl_type != F_UNLCK) {
737 for_each_lock(inode, before) {
738 struct file_lock *fl = *before;
741 if (!posix_locks_conflict(request, fl))
744 if (!(request->fl_flags & FL_SLEEP))
747 if (posix_locks_deadlock(request, fl))
750 locks_insert_block(fl, request);
755 /* If we're just looking for a conflict, we're done. */
757 if (request->fl_flags & FL_ACCESS)
760 error = -ENOLCK; /* "no luck" */
761 if (!(new_fl && new_fl2))
765 * We've allocated the new locks in advance, so there are no
766 * errors possible (and no blocking operations) from here on.
768 * Find the first old lock with the same owner as the new lock.
771 before = &inode->i_flock;
773 /* First skip locks owned by other processes. */
774 while ((fl = *before) && (!IS_POSIX(fl) ||
775 !posix_same_owner(request, fl))) {
776 before = &fl->fl_next;
779 /* Process locks with this owner. */
780 while ((fl = *before) && posix_same_owner(request, fl)) {
781 /* Detect adjacent or overlapping regions (if same lock type)
783 if (request->fl_type == fl->fl_type) {
784 if (fl->fl_end < request->fl_start - 1)
786 /* If the next lock in the list has entirely bigger
787 * addresses than the new one, insert the lock here.
789 if (fl->fl_start > request->fl_end + 1)
792 /* If we come here, the new and old lock are of the
793 * same type and adjacent or overlapping. Make one
794 * lock yielding from the lower start address of both
795 * locks to the higher end address.
797 if (fl->fl_start > request->fl_start)
798 fl->fl_start = request->fl_start;
800 request->fl_start = fl->fl_start;
801 if (fl->fl_end < request->fl_end)
802 fl->fl_end = request->fl_end;
804 request->fl_end = fl->fl_end;
806 locks_delete_lock(before);
813 /* Processing for different lock types is a bit
816 if (fl->fl_end < request->fl_start)
818 if (fl->fl_start > request->fl_end)
820 if (request->fl_type == F_UNLCK)
822 if (fl->fl_start < request->fl_start)
824 /* If the next lock in the list has a higher end
825 * address than the new one, insert the new one here.
827 if (fl->fl_end > request->fl_end) {
831 if (fl->fl_start >= request->fl_start) {
832 /* The new lock completely replaces an old
833 * one (This may happen several times).
836 locks_delete_lock(before);
839 /* Replace the old lock with the new one.
840 * Wake up anybody waiting for the old one,
841 * as the change in lock type might satisfy
844 locks_wake_up_blocks(fl);
845 fl->fl_start = request->fl_start;
846 fl->fl_end = request->fl_end;
847 fl->fl_type = request->fl_type;
848 fl->fl_u = request->fl_u;
853 /* Go on to next lock.
856 before = &fl->fl_next;
861 if (request->fl_type == F_UNLCK)
863 locks_copy_lock(new_fl, request);
864 locks_insert_lock(before, new_fl);
869 /* The new lock breaks the old one in two pieces,
870 * so we have to use the second new lock.
874 locks_copy_lock(left, right);
875 locks_insert_lock(before, left);
877 right->fl_start = request->fl_end + 1;
878 locks_wake_up_blocks(right);
881 left->fl_end = request->fl_start - 1;
882 locks_wake_up_blocks(left);
887 * Free any unused locks.
890 locks_free_lock(new_fl);
892 locks_free_lock(new_fl2);
897 * posix_lock_file - Apply a POSIX-style lock to a file
898 * @filp: The file to apply the lock to
899 * @fl: The lock to be applied
901 * Add a POSIX style lock to a file.
902 * We merge adjacent & overlapping locks whenever possible.
903 * POSIX locks are sorted by owner task, then by starting address
905 int posix_lock_file(struct file *filp, struct file_lock *fl)
907 return __posix_lock_file(filp->f_dentry->d_inode, fl);
911 * posix_lock_file_wait - Apply a POSIX-style lock to a file
912 * @filp: The file to apply the lock to
913 * @fl: The lock to be applied
915 * Add a POSIX style lock to a file.
916 * We merge adjacent & overlapping locks whenever possible.
917 * POSIX locks are sorted by owner task, then by starting address
919 int posix_lock_file_wait(struct file *filp, struct file_lock *fl)
924 error = __posix_lock_file(filp->f_dentry->d_inode, fl);
925 if ((error != -EAGAIN) || !(fl->fl_flags & FL_SLEEP))
927 error = wait_event_interruptible(fl->fl_wait, !fl->fl_next);
931 locks_delete_block(fl);
936 EXPORT_SYMBOL(posix_lock_file_wait);
939 * locks_mandatory_locked - Check for an active lock
940 * @inode: the file to check
942 * Searches the inode's list of locks to find any POSIX locks which conflict.
943 * This function is called from locks_verify_locked() only.
945 int locks_mandatory_locked(struct inode *inode)
947 fl_owner_t owner = current->files;
948 struct file_lock *fl;
951 * Search the lock list for this inode for any POSIX locks.
954 for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) {
957 if (fl->fl_owner != owner)
961 return fl ? -EAGAIN : 0;
965 * locks_mandatory_area - Check for a conflicting lock
966 * @read_write: %FLOCK_VERIFY_WRITE for exclusive access, %FLOCK_VERIFY_READ
968 * @inode: the file to check
969 * @filp: how the file was opened (if it was)
970 * @offset: start of area to check
971 * @count: length of area to check
973 * Searches the inode's list of locks to find any POSIX locks which conflict.
974 * This function is called from locks_verify_area() and
975 * locks_verify_truncate().
977 int locks_mandatory_area(int read_write, struct inode *inode,
978 struct file *filp, loff_t offset,
984 locks_init_lock(&fl);
985 fl.fl_owner = current->files;
986 fl.fl_pid = current->tgid;
988 fl.fl_flags = FL_POSIX | FL_ACCESS;
989 if (filp && !(filp->f_flags & O_NONBLOCK))
990 fl.fl_flags |= FL_SLEEP;
991 fl.fl_type = (read_write == FLOCK_VERIFY_WRITE) ? F_WRLCK : F_RDLCK;
992 fl.fl_start = offset;
993 fl.fl_end = offset + count - 1;
996 error = __posix_lock_file(inode, &fl);
997 if (error != -EAGAIN)
999 if (!(fl.fl_flags & FL_SLEEP))
1001 error = wait_event_interruptible(fl.fl_wait, !fl.fl_next);
1004 * If we've been sleeping someone might have
1005 * changed the permissions behind our back.
1007 if ((inode->i_mode & (S_ISGID | S_IXGRP)) == S_ISGID)
1011 locks_delete_block(&fl);
1018 EXPORT_SYMBOL(locks_mandatory_area);
1020 /* We already had a lease on this file; just change its type */
1021 static int lease_modify(struct file_lock **before, int arg)
1023 struct file_lock *fl = *before;
1024 int error = assign_type(fl, arg);
1028 locks_wake_up_blocks(fl);
1029 if (arg == F_UNLCK) {
1030 struct file *filp = fl->fl_file;
1033 filp->f_owner.signum = 0;
1034 locks_delete_lock(before);
1039 static void time_out_leases(struct inode *inode)
1041 struct file_lock **before;
1042 struct file_lock *fl;
1044 before = &inode->i_flock;
1045 while ((fl = *before) && IS_LEASE(fl) && (fl->fl_type & F_INPROGRESS)) {
1046 if ((fl->fl_break_time == 0)
1047 || time_before(jiffies, fl->fl_break_time)) {
1048 before = &fl->fl_next;
1051 printk(KERN_INFO "lease broken - owner pid = %d\n", fl->fl_pid);
1052 lease_modify(before, fl->fl_type & ~F_INPROGRESS);
1053 if (fl == *before) /* lease_modify may have freed fl */
1054 before = &fl->fl_next;
1059 * __break_lease - revoke all outstanding leases on file
1060 * @inode: the inode of the file to return
1061 * @mode: the open mode (read or write)
1063 * break_lease (inlined for speed) has checked there already
1064 * is a lease on this file. Leases are broken on a call to open()
1065 * or truncate(). This function can sleep unless you
1066 * specified %O_NONBLOCK to your open().
1068 int __break_lease(struct inode *inode, unsigned int mode)
1070 int error = 0, future;
1071 struct file_lock *new_fl, *flock;
1072 struct file_lock *fl;
1074 unsigned long break_time;
1075 int i_have_this_lease = 0;
1077 alloc_err = lease_alloc(NULL, mode & FMODE_WRITE ? F_WRLCK : F_RDLCK,
1082 time_out_leases(inode);
1084 flock = inode->i_flock;
1085 if ((flock == NULL) || !IS_LEASE(flock))
1088 for (fl = flock; fl && IS_LEASE(fl); fl = fl->fl_next)
1089 if (fl->fl_owner == current->files)
1090 i_have_this_lease = 1;
1092 if (mode & FMODE_WRITE) {
1093 /* If we want write access, we have to revoke any lease. */
1094 future = F_UNLCK | F_INPROGRESS;
1095 } else if (flock->fl_type & F_INPROGRESS) {
1096 /* If the lease is already being broken, we just leave it */
1097 future = flock->fl_type;
1098 } else if (flock->fl_type & F_WRLCK) {
1099 /* Downgrade the exclusive lease to a read-only lease. */
1100 future = F_RDLCK | F_INPROGRESS;
1102 /* the existing lease was read-only, so we can read too. */
1106 if (alloc_err && !i_have_this_lease && ((mode & O_NONBLOCK) == 0)) {
1112 if (lease_break_time > 0) {
1113 break_time = jiffies + lease_break_time * HZ;
1114 if (break_time == 0)
1115 break_time++; /* so that 0 means no break time */
1118 for (fl = flock; fl && IS_LEASE(fl); fl = fl->fl_next) {
1119 if (fl->fl_type != future) {
1120 fl->fl_type = future;
1121 fl->fl_break_time = break_time;
1122 kill_fasync(&fl->fl_fasync, SIGIO, POLL_MSG);
1126 if (i_have_this_lease || (mode & O_NONBLOCK)) {
1127 error = -EWOULDBLOCK;
1132 break_time = flock->fl_break_time;
1133 if (break_time != 0) {
1134 break_time -= jiffies;
1135 if (break_time == 0)
1138 error = locks_block_on_timeout(flock, new_fl, break_time);
1141 time_out_leases(inode);
1142 /* Wait for the next lease that has not been broken yet */
1143 for (flock = inode->i_flock; flock && IS_LEASE(flock);
1144 flock = flock->fl_next) {
1145 if (flock->fl_type & F_INPROGRESS)
1154 locks_free_lock(new_fl);
1158 EXPORT_SYMBOL(__break_lease);
1163 * @time: pointer to a timespec which will contain the last modified time
1165 * This is to force NFS clients to flush their caches for files with
1166 * exclusive leases. The justification is that if someone has an
1167 * exclusive lease, then they could be modifiying it.
1169 void lease_get_mtime(struct inode *inode, struct timespec *time)
1171 struct file_lock *flock = inode->i_flock;
1172 if (flock && IS_LEASE(flock) && (flock->fl_type & F_WRLCK))
1173 *time = CURRENT_TIME;
1175 *time = inode->i_mtime;
1178 EXPORT_SYMBOL(lease_get_mtime);
1181 * fcntl_getlease - Enquire what lease is currently active
1184 * The value returned by this function will be one of
1185 * (if no lease break is pending):
1187 * %F_RDLCK to indicate a shared lease is held.
1189 * %F_WRLCK to indicate an exclusive lease is held.
1191 * %F_UNLCK to indicate no lease is held.
1193 * (if a lease break is pending):
1195 * %F_RDLCK to indicate an exclusive lease needs to be
1196 * changed to a shared lease (or removed).
1198 * %F_UNLCK to indicate the lease needs to be removed.
1200 * XXX: sfr & willy disagree over whether F_INPROGRESS
1201 * should be returned to userspace.
1203 int fcntl_getlease(struct file *filp)
1205 struct file_lock *fl;
1209 time_out_leases(filp->f_dentry->d_inode);
1210 for (fl = filp->f_dentry->d_inode->i_flock; fl && IS_LEASE(fl);
1212 if (fl->fl_file == filp) {
1213 type = fl->fl_type & ~F_INPROGRESS;
1222 * fcntl_setlease - sets a lease on an open file
1223 * @fd: open file descriptor
1224 * @filp: file pointer
1225 * @arg: type of lease to obtain
1227 * Call this fcntl to establish a lease on the file.
1228 * Note that you also need to call %F_SETSIG to
1229 * receive a signal when the lease is broken.
1231 int fcntl_setlease(unsigned int fd, struct file *filp, long arg)
1233 struct file_lock *fl, **before, **my_before = NULL;
1234 struct dentry *dentry;
1235 struct inode *inode;
1236 int error, rdlease_count = 0, wrlease_count = 0;
1238 dentry = filp->f_dentry;
1239 inode = dentry->d_inode;
1241 if ((current->fsuid != inode->i_uid) && !capable(CAP_LEASE))
1243 if (!S_ISREG(inode->i_mode))
1245 error = security_file_lock(filp, arg);
1251 time_out_leases(inode);
1254 * FIXME: What about F_RDLCK and files open for writing?
1257 if ((arg == F_WRLCK)
1258 && ((atomic_read(&dentry->d_count) > 1)
1259 || (atomic_read(&inode->i_count) > 1)))
1263 * At this point, we know that if there is an exclusive
1264 * lease on this file, then we hold it on this filp
1265 * (otherwise our open of this file would have blocked).
1266 * And if we are trying to acquire an exclusive lease,
1267 * then the file is not open by anyone (including us)
1268 * except for this filp.
1270 for (before = &inode->i_flock;
1271 ((fl = *before) != NULL) && IS_LEASE(fl);
1272 before = &fl->fl_next) {
1273 if (fl->fl_file == filp)
1275 else if (fl->fl_type == (F_INPROGRESS | F_UNLCK))
1277 * Someone is in the process of opening this
1278 * file for writing so we may not take an
1279 * exclusive lease on it.
1286 if ((arg == F_RDLCK && (wrlease_count > 0)) ||
1287 (arg == F_WRLCK && ((rdlease_count + wrlease_count) > 0)))
1290 if (my_before != NULL) {
1291 error = lease_modify(my_before, arg);
1303 error = lease_alloc(filp, arg, &fl);
1307 error = fasync_helper(fd, filp, 1, &fl->fl_fasync);
1309 locks_free_lock(fl);
1313 locks_insert_lock(before, fl);
1315 error = f_setown(filp, current->pid, 0);
1322 * flock_lock_file_wait - Apply a FLOCK-style lock to a file
1323 * @filp: The file to apply the lock to
1324 * @fl: The lock to be applied
1326 * Add a FLOCK style lock to a file.
1328 int flock_lock_file_wait(struct file *filp, struct file_lock *fl)
1333 error = flock_lock_file(filp, fl);
1334 if ((error != -EAGAIN) || !(fl->fl_flags & FL_SLEEP))
1336 error = wait_event_interruptible(fl->fl_wait, !fl->fl_next);
1340 locks_delete_block(fl);
1346 EXPORT_SYMBOL(flock_lock_file_wait);
1349 * sys_flock: - flock() system call.
1350 * @fd: the file descriptor to lock.
1351 * @cmd: the type of lock to apply.
1353 * Apply a %FL_FLOCK style lock to an open file descriptor.
1354 * The @cmd can be one of
1356 * %LOCK_SH -- a shared lock.
1358 * %LOCK_EX -- an exclusive lock.
1360 * %LOCK_UN -- remove an existing lock.
1362 * %LOCK_MAND -- a `mandatory' flock. This exists to emulate Windows Share Modes.
1364 * %LOCK_MAND can be combined with %LOCK_READ or %LOCK_WRITE to allow other
1365 * processes read and write access respectively.
1367 asmlinkage long sys_flock(unsigned int fd, unsigned int cmd)
1370 struct file_lock *lock;
1371 int can_sleep, unlock;
1379 can_sleep = !(cmd & LOCK_NB);
1381 unlock = (cmd == LOCK_UN);
1383 if (!unlock && !(cmd & LOCK_MAND) && !(filp->f_mode & 3))
1386 error = flock_make_lock(filp, &lock, cmd);
1390 lock->fl_flags |= FL_SLEEP;
1392 error = security_file_lock(filp, cmd);
1396 if (filp->f_op && filp->f_op->flock)
1397 error = filp->f_op->flock(filp,
1398 (can_sleep) ? F_SETLKW : F_SETLK,
1401 error = flock_lock_file_wait(filp, lock);
1404 if (list_empty(&lock->fl_link)) {
1405 locks_free_lock(lock);
1414 /* Report the first existing lock that would conflict with l.
1415 * This implements the F_GETLK command of fcntl().
1417 int fcntl_getlk(struct file *filp, struct flock __user *l)
1419 struct file_lock *fl, file_lock;
1424 if (copy_from_user(&flock, l, sizeof(flock)))
1427 if ((flock.l_type != F_RDLCK) && (flock.l_type != F_WRLCK))
1430 error = flock_to_posix_lock(filp, &file_lock, &flock);
1434 if (filp->f_op && filp->f_op->lock) {
1435 error = filp->f_op->lock(filp, F_GETLK, &file_lock);
1438 else if (error == LOCK_USE_CLNT)
1439 /* Bypass for NFS with no locking - 2.0.36 compat */
1440 fl = posix_test_lock(filp, &file_lock);
1442 fl = (file_lock.fl_type == F_UNLCK ? NULL : &file_lock);
1444 fl = posix_test_lock(filp, &file_lock);
1447 flock.l_type = F_UNLCK;
1449 flock.l_pid = fl->fl_pid;
1450 #if BITS_PER_LONG == 32
1452 * Make sure we can represent the posix lock via
1453 * legacy 32bit flock.
1456 if (fl->fl_start > OFFT_OFFSET_MAX)
1458 if ((fl->fl_end != OFFSET_MAX)
1459 && (fl->fl_end > OFFT_OFFSET_MAX))
1462 flock.l_start = fl->fl_start;
1463 flock.l_len = fl->fl_end == OFFSET_MAX ? 0 :
1464 fl->fl_end - fl->fl_start + 1;
1466 flock.l_type = fl->fl_type;
1469 if (!copy_to_user(l, &flock, sizeof(flock)))
1475 /* Apply the lock described by l to an open file descriptor.
1476 * This implements both the F_SETLK and F_SETLKW commands of fcntl().
1478 int fcntl_setlk(struct file *filp, unsigned int cmd, struct flock __user *l)
1480 struct file_lock *file_lock = locks_alloc_lock();
1482 struct inode *inode;
1485 if (file_lock == NULL)
1489 * This might block, so we do it before checking the inode.
1492 if (copy_from_user(&flock, l, sizeof(flock)))
1495 inode = filp->f_dentry->d_inode;
1497 /* Don't allow mandatory locks on files that may be memory mapped
1500 if (IS_MANDLOCK(inode) &&
1501 (inode->i_mode & (S_ISGID | S_IXGRP)) == S_ISGID &&
1502 mapping_writably_mapped(filp->f_mapping)) {
1507 error = flock_to_posix_lock(filp, file_lock, &flock);
1510 if (cmd == F_SETLKW) {
1511 file_lock->fl_flags |= FL_SLEEP;
1515 switch (flock.l_type) {
1517 if (!(filp->f_mode & FMODE_READ))
1521 if (!(filp->f_mode & FMODE_WRITE))
1531 error = security_file_lock(filp, file_lock->fl_type);
1535 if (filp->f_op && filp->f_op->lock != NULL) {
1536 error = filp->f_op->lock(filp, cmd, file_lock);
1541 error = __posix_lock_file(inode, file_lock);
1542 if ((error != -EAGAIN) || (cmd == F_SETLK))
1544 error = wait_event_interruptible(file_lock->fl_wait,
1545 !file_lock->fl_next);
1549 locks_delete_block(file_lock);
1554 locks_free_lock(file_lock);
1558 #if BITS_PER_LONG == 32
1559 /* Report the first existing lock that would conflict with l.
1560 * This implements the F_GETLK command of fcntl().
1562 int fcntl_getlk64(struct file *filp, struct flock64 __user *l)
1564 struct file_lock *fl, file_lock;
1565 struct flock64 flock;
1569 if (copy_from_user(&flock, l, sizeof(flock)))
1572 if ((flock.l_type != F_RDLCK) && (flock.l_type != F_WRLCK))
1575 error = flock64_to_posix_lock(filp, &file_lock, &flock);
1579 if (filp->f_op && filp->f_op->lock) {
1580 error = filp->f_op->lock(filp, F_GETLK, &file_lock);
1583 else if (error == LOCK_USE_CLNT)
1584 /* Bypass for NFS with no locking - 2.0.36 compat */
1585 fl = posix_test_lock(filp, &file_lock);
1587 fl = (file_lock.fl_type == F_UNLCK ? NULL : &file_lock);
1589 fl = posix_test_lock(filp, &file_lock);
1592 flock.l_type = F_UNLCK;
1594 flock.l_pid = fl->fl_pid;
1595 flock.l_start = fl->fl_start;
1596 flock.l_len = fl->fl_end == OFFSET_MAX ? 0 :
1597 fl->fl_end - fl->fl_start + 1;
1599 flock.l_type = fl->fl_type;
1602 if (!copy_to_user(l, &flock, sizeof(flock)))
1609 /* Apply the lock described by l to an open file descriptor.
1610 * This implements both the F_SETLK and F_SETLKW commands of fcntl().
1612 int fcntl_setlk64(struct file *filp, unsigned int cmd, struct flock64 __user *l)
1614 struct file_lock *file_lock = locks_alloc_lock();
1615 struct flock64 flock;
1616 struct inode *inode;
1619 if (file_lock == NULL)
1623 * This might block, so we do it before checking the inode.
1626 if (copy_from_user(&flock, l, sizeof(flock)))
1629 inode = filp->f_dentry->d_inode;
1631 /* Don't allow mandatory locks on files that may be memory mapped
1634 if (IS_MANDLOCK(inode) &&
1635 (inode->i_mode & (S_ISGID | S_IXGRP)) == S_ISGID &&
1636 mapping_writably_mapped(filp->f_mapping)) {
1641 error = flock64_to_posix_lock(filp, file_lock, &flock);
1644 if (cmd == F_SETLKW64) {
1645 file_lock->fl_flags |= FL_SLEEP;
1649 switch (flock.l_type) {
1651 if (!(filp->f_mode & FMODE_READ))
1655 if (!(filp->f_mode & FMODE_WRITE))
1665 error = security_file_lock(filp, file_lock->fl_type);
1669 if (filp->f_op && filp->f_op->lock != NULL) {
1670 error = filp->f_op->lock(filp, cmd, file_lock);
1675 error = __posix_lock_file(inode, file_lock);
1676 if ((error != -EAGAIN) || (cmd == F_SETLK64))
1678 error = wait_event_interruptible(file_lock->fl_wait,
1679 !file_lock->fl_next);
1683 locks_delete_block(file_lock);
1688 locks_free_lock(file_lock);
1691 #endif /* BITS_PER_LONG == 32 */
1694 * This function is called when the file is being removed
1695 * from the task's fd array. POSIX locks belonging to this task
1696 * are deleted at this time.
1698 void locks_remove_posix(struct file *filp, fl_owner_t owner)
1700 struct file_lock lock, **before;
1703 * If there are no locks held on this file, we don't need to call
1704 * posix_lock_file(). Another process could be setting a lock on this
1705 * file at the same time, but we wouldn't remove that lock anyway.
1707 before = &filp->f_dentry->d_inode->i_flock;
1708 if (*before == NULL)
1711 lock.fl_type = F_UNLCK;
1712 lock.fl_flags = FL_POSIX;
1714 lock.fl_end = OFFSET_MAX;
1715 lock.fl_owner = owner;
1716 lock.fl_pid = current->tgid;
1717 lock.fl_file = filp;
1719 lock.fl_lmops = NULL;
1721 if (filp->f_op && filp->f_op->lock != NULL) {
1722 filp->f_op->lock(filp, F_SETLK, &lock);
1726 /* Can't use posix_lock_file here; we need to remove it no matter
1727 * which pid we have.
1730 while (*before != NULL) {
1731 struct file_lock *fl = *before;
1732 if (IS_POSIX(fl) && posix_same_owner(fl, &lock)) {
1733 locks_delete_lock(before);
1736 before = &fl->fl_next;
1740 if (lock.fl_ops && lock.fl_ops->fl_release_private)
1741 lock.fl_ops->fl_release_private(&lock);
1744 EXPORT_SYMBOL(locks_remove_posix);
1747 * This function is called on the last close of an open file.
1749 void locks_remove_flock(struct file *filp)
1751 struct inode * inode = filp->f_dentry->d_inode;
1752 struct file_lock *fl;
1753 struct file_lock **before;
1755 if (!inode->i_flock)
1758 if (filp->f_op && filp->f_op->flock) {
1759 struct file_lock fl = { .fl_flags = FL_FLOCK,
1760 .fl_type = F_UNLCK };
1761 filp->f_op->flock(filp, F_SETLKW, &fl);
1765 before = &inode->i_flock;
1767 while ((fl = *before) != NULL) {
1768 if (fl->fl_file == filp) {
1770 * We might have a POSIX lock that was created at the same time
1771 * the filp was closed for the last time. Just remove that too,
1772 * regardless of ownership, since nobody can own it.
1774 if (IS_FLOCK(fl) || IS_POSIX(fl)) {
1775 locks_delete_lock(before);
1779 lease_modify(before, F_UNLCK);
1785 before = &fl->fl_next;
1791 * posix_block_lock - blocks waiting for a file lock
1792 * @blocker: the lock which is blocking
1793 * @waiter: the lock which conflicts and has to wait
1795 * lockd needs to block waiting for locks.
1798 posix_block_lock(struct file_lock *blocker, struct file_lock *waiter)
1800 locks_insert_block(blocker, waiter);
1803 EXPORT_SYMBOL(posix_block_lock);
1806 * posix_unblock_lock - stop waiting for a file lock
1807 * @filp: how the file was opened
1808 * @waiter: the lock which was waiting
1810 * lockd needs to block waiting for locks.
1813 posix_unblock_lock(struct file *filp, struct file_lock *waiter)
1816 * A remote machine may cancel the lock request after it's been
1817 * granted locally. If that happens, we need to delete the lock.
1820 if (waiter->fl_next) {
1821 __locks_delete_block(waiter);
1825 waiter->fl_type = F_UNLCK;
1826 posix_lock_file(filp, waiter);
1830 EXPORT_SYMBOL(posix_unblock_lock);
1832 static void lock_get_status(char* out, struct file_lock *fl, int id, char *pfx)
1834 struct inode *inode = NULL;
1836 if (fl->fl_file != NULL)
1837 inode = fl->fl_file->f_dentry->d_inode;
1839 out += sprintf(out, "%d:%s ", id, pfx);
1841 out += sprintf(out, "%6s %s ",
1842 (fl->fl_flags & FL_ACCESS) ? "ACCESS" : "POSIX ",
1843 (inode == NULL) ? "*NOINODE*" :
1844 (IS_MANDLOCK(inode) &&
1845 (inode->i_mode & (S_IXGRP | S_ISGID)) == S_ISGID) ?
1846 "MANDATORY" : "ADVISORY ");
1847 } else if (IS_FLOCK(fl)) {
1848 if (fl->fl_type & LOCK_MAND) {
1849 out += sprintf(out, "FLOCK MSNFS ");
1851 out += sprintf(out, "FLOCK ADVISORY ");
1853 } else if (IS_LEASE(fl)) {
1854 out += sprintf(out, "LEASE ");
1855 if (fl->fl_type & F_INPROGRESS)
1856 out += sprintf(out, "BREAKING ");
1857 else if (fl->fl_file)
1858 out += sprintf(out, "ACTIVE ");
1860 out += sprintf(out, "BREAKER ");
1862 out += sprintf(out, "UNKNOWN UNKNOWN ");
1864 if (fl->fl_type & LOCK_MAND) {
1865 out += sprintf(out, "%s ",
1866 (fl->fl_type & LOCK_READ)
1867 ? (fl->fl_type & LOCK_WRITE) ? "RW " : "READ "
1868 : (fl->fl_type & LOCK_WRITE) ? "WRITE" : "NONE ");
1870 out += sprintf(out, "%s ",
1871 (fl->fl_type & F_INPROGRESS)
1872 ? (fl->fl_type & F_UNLCK) ? "UNLCK" : "READ "
1873 : (fl->fl_type & F_WRLCK) ? "WRITE" : "READ ");
1876 #ifdef WE_CAN_BREAK_LSLK_NOW
1877 out += sprintf(out, "%d %s:%ld ", fl->fl_pid,
1878 inode->i_sb->s_id, inode->i_ino);
1880 /* userspace relies on this representation of dev_t ;-( */
1881 out += sprintf(out, "%d %02x:%02x:%ld ", fl->fl_pid,
1882 MAJOR(inode->i_sb->s_dev),
1883 MINOR(inode->i_sb->s_dev), inode->i_ino);
1886 out += sprintf(out, "%d <none>:0 ", fl->fl_pid);
1889 if (fl->fl_end == OFFSET_MAX)
1890 out += sprintf(out, "%Ld EOF\n", fl->fl_start);
1892 out += sprintf(out, "%Ld %Ld\n", fl->fl_start,
1895 out += sprintf(out, "0 EOF\n");
1899 static void move_lock_status(char **p, off_t* pos, off_t offset)
1903 if(*pos >= offset) {
1904 /* the complete line is valid */
1909 if(*pos+len > offset) {
1910 /* use the second part of the line */
1911 int i = offset-*pos;
1912 memmove(*p,*p+i,len-i);
1917 /* discard the complete line */
1922 * get_locks_status - reports lock usage in /proc/locks
1923 * @buffer: address in userspace to write into
1925 * @offset: how far we are through the buffer
1926 * @length: how much to read
1929 int get_locks_status(char *buffer, char **start, off_t offset, int length)
1931 struct list_head *tmp;
1937 list_for_each(tmp, &file_lock_list) {
1938 struct list_head *btmp;
1939 struct file_lock *fl = list_entry(tmp, struct file_lock, fl_link);
1940 lock_get_status(q, fl, ++i, "");
1941 move_lock_status(&q, &pos, offset);
1943 if(pos >= offset+length)
1946 list_for_each(btmp, &fl->fl_block) {
1947 struct file_lock *bfl = list_entry(btmp,
1948 struct file_lock, fl_block);
1949 lock_get_status(q, bfl, i, " ->");
1950 move_lock_status(&q, &pos, offset);
1952 if(pos >= offset+length)
1959 if(q-buffer < length)
1965 * lock_may_read - checks that the region is free of locks
1966 * @inode: the inode that is being read
1967 * @start: the first byte to read
1968 * @len: the number of bytes to read
1970 * Emulates Windows locking requirements. Whole-file
1971 * mandatory locks (share modes) can prohibit a read and
1972 * byte-range POSIX locks can prohibit a read if they overlap.
1974 * N.B. this function is only ever called
1975 * from knfsd and ownership of locks is never checked.
1977 int lock_may_read(struct inode *inode, loff_t start, unsigned long len)
1979 struct file_lock *fl;
1982 for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) {
1984 if (fl->fl_type == F_RDLCK)
1986 if ((fl->fl_end < start) || (fl->fl_start > (start + len)))
1988 } else if (IS_FLOCK(fl)) {
1989 if (!(fl->fl_type & LOCK_MAND))
1991 if (fl->fl_type & LOCK_READ)
2002 EXPORT_SYMBOL(lock_may_read);
2005 * lock_may_write - checks that the region is free of locks
2006 * @inode: the inode that is being written
2007 * @start: the first byte to write
2008 * @len: the number of bytes to write
2010 * Emulates Windows locking requirements. Whole-file
2011 * mandatory locks (share modes) can prohibit a write and
2012 * byte-range POSIX locks can prohibit a write if they overlap.
2014 * N.B. this function is only ever called
2015 * from knfsd and ownership of locks is never checked.
2017 int lock_may_write(struct inode *inode, loff_t start, unsigned long len)
2019 struct file_lock *fl;
2022 for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) {
2024 if ((fl->fl_end < start) || (fl->fl_start > (start + len)))
2026 } else if (IS_FLOCK(fl)) {
2027 if (!(fl->fl_type & LOCK_MAND))
2029 if (fl->fl_type & LOCK_WRITE)
2040 EXPORT_SYMBOL(lock_may_write);
2042 static inline void __steal_locks(struct file *file, fl_owner_t from)
2044 struct inode *inode = file->f_dentry->d_inode;
2045 struct file_lock *fl = inode->i_flock;
2048 if (fl->fl_file == file && fl->fl_owner == from)
2049 fl->fl_owner = current->files;
2054 /* When getting ready for executing a binary, we make sure that current
2055 * has a files_struct on its own. Before dropping the old files_struct,
2056 * we take over ownership of all locks for all file descriptors we own.
2057 * Note that we may accidentally steal a lock for a file that a sibling
2058 * has created since the unshare_files() call.
2060 void steal_locks(fl_owner_t from)
2062 struct files_struct *files = current->files;
2073 if (i >= files->max_fdset || i >= files->max_fds)
2075 set = files->open_fds->fds_bits[j++];
2078 struct file *file = files->fd[i];
2080 __steal_locks(file, from);
2088 EXPORT_SYMBOL(steal_locks);
2090 static int __init filelock_init(void)
2092 filelock_cache = kmem_cache_create("file_lock_cache",
2093 sizeof(struct file_lock), 0, SLAB_PANIC,
2098 core_initcall(filelock_init);