1 #define MSNFS /* HACK HACK */
5 * Provide support for fcntl()'s F_GETLK, F_SETLK, and F_SETLKW calls.
6 * Doug Evans (dje@spiff.uucp), August 07, 1992
8 * Deadlock detection added.
9 * FIXME: one thing isn't handled yet:
10 * - mandatory locks (requires lots of changes elsewhere)
11 * Kelly Carmichael (kelly@[142.24.8.65]), September 17, 1994.
13 * Miscellaneous edits, and a total rewrite of posix_lock_file() code.
14 * Kai Petzke (wpp@marie.physik.tu-berlin.de), 1994
16 * Converted file_lock_table to a linked list from an array, which eliminates
17 * the limits on how many active file locks are open.
18 * Chad Page (pageone@netcom.com), November 27, 1994
20 * Removed dependency on file descriptors. dup()'ed file descriptors now
21 * get the same locks as the original file descriptors, and a close() on
22 * any file descriptor removes ALL the locks on the file for the current
23 * process. Since locks still depend on the process id, locks are inherited
24 * after an exec() but not after a fork(). This agrees with POSIX, and both
25 * BSD and SVR4 practice.
26 * Andy Walker (andy@lysaker.kvaerner.no), February 14, 1995
28 * Scrapped free list which is redundant now that we allocate locks
29 * dynamically with kmalloc()/kfree().
30 * Andy Walker (andy@lysaker.kvaerner.no), February 21, 1995
32 * Implemented two lock personalities - FL_FLOCK and FL_POSIX.
34 * FL_POSIX locks are created with calls to fcntl() and lockf() through the
35 * fcntl() system call. They have the semantics described above.
37 * FL_FLOCK locks are created with calls to flock(), through the flock()
38 * system call, which is new. Old C libraries implement flock() via fcntl()
39 * and will continue to use the old, broken implementation.
41 * FL_FLOCK locks follow the 4.4 BSD flock() semantics. They are associated
42 * with a file pointer (filp). As a result they can be shared by a parent
43 * process and its children after a fork(). They are removed when the last
44 * file descriptor referring to the file pointer is closed (unless explicitly
47 * FL_FLOCK locks never deadlock, an existing lock is always removed before
48 * upgrading from shared to exclusive (or vice versa). When this happens
49 * any processes blocked by the current lock are woken up and allowed to
50 * run before the new lock is applied.
51 * Andy Walker (andy@lysaker.kvaerner.no), June 09, 1995
53 * Removed some race conditions in flock_lock_file(), marked other possible
54 * races. Just grep for FIXME to see them.
55 * Dmitry Gorodchanin (pgmdsg@ibi.com), February 09, 1996.
57 * Addressed Dmitry's concerns. Deadlock checking no longer recursive.
58 * Lock allocation changed to GFP_ATOMIC as we can't afford to sleep
59 * once we've checked for blocking and deadlocking.
60 * Andy Walker (andy@lysaker.kvaerner.no), April 03, 1996.
62 * Initial implementation of mandatory locks. SunOS turned out to be
63 * a rotten model, so I implemented the "obvious" semantics.
64 * See 'linux/Documentation/mandatory.txt' for details.
65 * Andy Walker (andy@lysaker.kvaerner.no), April 06, 1996.
67 * Don't allow mandatory locks on mmap()'ed files. Added simple functions to
68 * check if a file has mandatory locks, used by mmap(), open() and creat() to
69 * see if system call should be rejected. Ref. HP-UX/SunOS/Solaris Reference
71 * Andy Walker (andy@lysaker.kvaerner.no), April 09, 1996.
73 * Tidied up block list handling. Added '/proc/locks' interface.
74 * Andy Walker (andy@lysaker.kvaerner.no), April 24, 1996.
76 * Fixed deadlock condition for pathological code that mixes calls to
77 * flock() and fcntl().
78 * Andy Walker (andy@lysaker.kvaerner.no), April 29, 1996.
80 * Allow only one type of locking scheme (FL_POSIX or FL_FLOCK) to be in use
81 * for a given file at a time. Changed the CONFIG_LOCK_MANDATORY scheme to
82 * guarantee sensible behaviour in the case where file system modules might
83 * be compiled with different options than the kernel itself.
84 * Andy Walker (andy@lysaker.kvaerner.no), May 15, 1996.
86 * Added a couple of missing wake_up() calls. Thanks to Thomas Meckel
87 * (Thomas.Meckel@mni.fh-giessen.de) for spotting this.
88 * Andy Walker (andy@lysaker.kvaerner.no), May 15, 1996.
90 * Changed FL_POSIX locks to use the block list in the same way as FL_FLOCK
91 * locks. Changed process synchronisation to avoid dereferencing locks that
92 * have already been freed.
93 * Andy Walker (andy@lysaker.kvaerner.no), Sep 21, 1996.
95 * Made the block list a circular list to minimise searching in the list.
96 * Andy Walker (andy@lysaker.kvaerner.no), Sep 25, 1996.
98 * Made mandatory locking a mount option. Default is not to allow mandatory
100 * Andy Walker (andy@lysaker.kvaerner.no), Oct 04, 1996.
102 * Some adaptations for NFS support.
103 * Olaf Kirch (okir@monad.swb.de), Dec 1996,
105 * Fixed /proc/locks interface so that we can't overrun the buffer we are handed.
106 * Andy Walker (andy@lysaker.kvaerner.no), May 12, 1997.
108 * Use slab allocator instead of kmalloc/kfree.
109 * Use generic list implementation from <linux/list.h>.
110 * Sped up posix_locks_deadlock by only considering blocked locks.
111 * Matthew Wilcox <willy@thepuffingroup.com>, March, 2000.
113 * Leases and LOCK_MAND
114 * Matthew Wilcox <willy@linuxcare.com>, June, 2000.
115 * Stephen Rothwell <sfr@canb.auug.org.au>, June, 2000.
118 #include <linux/slab.h>
119 #include <linux/file.h>
120 #include <linux/smp_lock.h>
121 #include <linux/init.h>
122 #include <linux/capability.h>
123 #include <linux/sched.h>
124 #include <linux/timer.h>
126 #include <asm/semaphore.h>
127 #include <asm/uaccess.h>
129 int leases_enable = 1;
130 int lease_break_time = 45;
132 LIST_HEAD(file_lock_list);
133 static LIST_HEAD(blocked_list);
135 static kmem_cache_t *filelock_cache;
137 /* Allocate an empty lock structure. */
138 static struct file_lock *locks_alloc_lock(void)
140 return kmem_cache_alloc(filelock_cache, SLAB_KERNEL);
143 /* Free a lock which is not in use. */
144 static inline void locks_free_lock(struct file_lock *fl)
150 if (waitqueue_active(&fl->fl_wait))
151 panic("Attempting to free lock with active wait queue");
153 if (!list_empty(&fl->fl_block))
154 panic("Attempting to free lock with active block list");
156 if (!list_empty(&fl->fl_link))
157 panic("Attempting to free lock on active lock list");
159 kmem_cache_free(filelock_cache, fl);
162 void locks_init_lock(struct file_lock *fl)
164 INIT_LIST_HEAD(&fl->fl_link);
165 INIT_LIST_HEAD(&fl->fl_block);
166 init_waitqueue_head(&fl->fl_wait);
168 fl->fl_fasync = NULL;
174 fl->fl_start = fl->fl_end = 0;
175 fl->fl_notify = NULL;
176 fl->fl_insert = NULL;
177 fl->fl_remove = NULL;
181 * Initialises the fields of the file lock which are invariant for
184 static void init_once(void *foo, kmem_cache_t *cache, unsigned long flags)
186 struct file_lock *lock = (struct file_lock *) foo;
188 if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) !=
189 SLAB_CTOR_CONSTRUCTOR)
192 locks_init_lock(lock);
196 * Initialize a new lock from an existing file_lock structure.
198 void locks_copy_lock(struct file_lock *new, struct file_lock *fl)
200 new->fl_owner = fl->fl_owner;
201 new->fl_pid = fl->fl_pid;
202 new->fl_file = fl->fl_file;
203 new->fl_flags = fl->fl_flags;
204 new->fl_type = fl->fl_type;
205 new->fl_start = fl->fl_start;
206 new->fl_end = fl->fl_end;
207 new->fl_notify = fl->fl_notify;
208 new->fl_insert = fl->fl_insert;
209 new->fl_remove = fl->fl_remove;
210 new->fl_u = fl->fl_u;
213 /* Fill in a file_lock structure with an appropriate FLOCK lock. */
214 static struct file_lock *flock_make_lock(struct file *filp, unsigned int type)
216 struct file_lock *fl = locks_alloc_lock();
222 fl->fl_pid = current->pid;
223 fl->fl_flags = FL_FLOCK;
226 fl->fl_end = OFFSET_MAX;
227 fl->fl_notify = NULL;
228 fl->fl_insert = NULL;
229 fl->fl_remove = NULL;
234 static int assign_type(struct file_lock *fl, int type)
248 /* Verify a "struct flock" and copy it to a "struct file_lock" as a POSIX
251 static int flock_to_posix_lock(struct file *filp, struct file_lock *fl,
256 switch (l->l_whence) {
264 start = filp->f_dentry->d_inode->i_size;
270 /* POSIX-1996 leaves the case l->l_len < 0 undefined;
271 POSIX-2001 defines it. */
277 end = start + l->l_len - 1;
282 if (l->l_len > 0 && end < 0)
284 fl->fl_start = start; /* we record the absolute position */
287 fl->fl_end = OFFSET_MAX;
289 fl->fl_owner = current->files;
290 fl->fl_pid = current->pid;
292 fl->fl_flags = FL_POSIX;
293 fl->fl_notify = NULL;
294 fl->fl_insert = NULL;
295 fl->fl_remove = NULL;
297 return assign_type(fl, l->l_type);
300 #if BITS_PER_LONG == 32
301 static int flock64_to_posix_lock(struct file *filp, struct file_lock *fl,
306 switch (l->l_whence) {
314 start = filp->f_dentry->d_inode->i_size;
320 if (((start += l->l_start) < 0) || (l->l_len < 0))
322 fl->fl_end = start + l->l_len - 1;
323 if (l->l_len > 0 && fl->fl_end < 0)
325 fl->fl_start = start; /* we record the absolute position */
327 fl->fl_end = OFFSET_MAX;
329 fl->fl_owner = current->files;
330 fl->fl_pid = current->pid;
332 fl->fl_flags = FL_POSIX;
333 fl->fl_notify = NULL;
334 fl->fl_insert = NULL;
335 fl->fl_remove = NULL;
341 fl->fl_type = l->l_type;
351 /* Allocate a file_lock initialised to this type of lease */
352 static int lease_alloc(struct file *filp, int type, struct file_lock **flp)
354 struct file_lock *fl = locks_alloc_lock();
358 fl->fl_owner = current->files;
359 fl->fl_pid = current->pid;
362 fl->fl_flags = FL_LEASE;
363 if (assign_type(fl, type) != 0) {
368 fl->fl_end = OFFSET_MAX;
369 fl->fl_notify = NULL;
370 fl->fl_insert = NULL;
371 fl->fl_remove = NULL;
377 /* Check if two locks overlap each other.
379 static inline int locks_overlap(struct file_lock *fl1, struct file_lock *fl2)
381 return ((fl1->fl_end >= fl2->fl_start) &&
382 (fl2->fl_end >= fl1->fl_start));
386 * Check whether two locks have the same owner
387 * N.B. Do we need the test on PID as well as owner?
388 * (Clone tasks should be considered as one "owner".)
391 locks_same_owner(struct file_lock *fl1, struct file_lock *fl2)
393 return (fl1->fl_owner == fl2->fl_owner) &&
394 (fl1->fl_pid == fl2->fl_pid);
397 /* Remove waiter from blocker's block list.
398 * When blocker ends up pointing to itself then the list is empty.
400 static void locks_delete_block(struct file_lock *waiter)
402 list_del(&waiter->fl_block);
403 INIT_LIST_HEAD(&waiter->fl_block);
404 list_del(&waiter->fl_link);
405 INIT_LIST_HEAD(&waiter->fl_link);
406 waiter->fl_next = NULL;
409 /* Insert waiter into blocker's block list.
410 * We use a circular list so that processes can be easily woken up in
411 * the order they blocked. The documentation doesn't require this but
412 * it seems like the reasonable thing to do.
414 static void locks_insert_block(struct file_lock *blocker,
415 struct file_lock *waiter)
417 if (!list_empty(&waiter->fl_block)) {
418 printk(KERN_ERR "locks_insert_block: removing duplicated lock "
419 "(pid=%d %Ld-%Ld type=%d)\n", waiter->fl_pid,
420 waiter->fl_start, waiter->fl_end, waiter->fl_type);
421 locks_delete_block(waiter);
423 list_add_tail(&waiter->fl_block, &blocker->fl_block);
424 waiter->fl_next = blocker;
425 list_add(&waiter->fl_link, &blocked_list);
429 void locks_notify_blocked(struct file_lock *waiter)
431 if (waiter->fl_notify)
432 waiter->fl_notify(waiter);
434 wake_up(&waiter->fl_wait);
437 /* Wake up processes blocked waiting for blocker.
438 * If told to wait then schedule the processes until the block list
439 * is empty, otherwise empty the block list ourselves.
441 static void locks_wake_up_blocks(struct file_lock *blocker, unsigned int wait)
443 while (!list_empty(&blocker->fl_block)) {
444 struct file_lock *waiter = list_entry(blocker->fl_block.next, struct file_lock, fl_block);
447 locks_notify_blocked(waiter);
448 /* Let the blocked process remove waiter from the
449 * block list when it gets scheduled.
453 /* Remove waiter from the block list, because by the
454 * time it wakes up blocker won't exist any more.
456 locks_delete_block(waiter);
457 locks_notify_blocked(waiter);
462 /* Insert file lock fl into an inode's lock list at the position indicated
463 * by pos. At the same time add the lock to the global file lock list.
465 static void locks_insert_lock(struct file_lock **pos, struct file_lock *fl)
467 list_add(&fl->fl_link, &file_lock_list);
469 /* insert into file's list */
478 * Remove lock from the lock lists
480 static inline void _unhash_lock(struct file_lock **thisfl_p)
482 struct file_lock *fl = *thisfl_p;
484 *thisfl_p = fl->fl_next;
487 list_del_init(&fl->fl_link);
491 * Wake up processes that are blocked waiting for this lock,
492 * notify the FS that the lock has been cleared and
493 * finally free the lock.
495 static inline void _delete_lock(struct file_lock *fl, unsigned int wait)
497 fasync_helper(0, fl->fl_file, 0, &fl->fl_fasync);
498 if (fl->fl_fasync != NULL){
499 printk(KERN_ERR "locks_delete_lock: fasync == %p\n", fl->fl_fasync);
500 fl->fl_fasync = NULL;
506 locks_wake_up_blocks(fl, wait);
511 * Delete a lock and then free it.
513 static void locks_delete_lock(struct file_lock **thisfl_p, unsigned int wait)
515 struct file_lock *fl = *thisfl_p;
517 _unhash_lock(thisfl_p);
518 _delete_lock(fl, wait);
522 * Call back client filesystem in order to get it to unregister a lock,
523 * then delete lock. Essentially useful only in locks_remove_*().
524 * Note: this must be called with the semaphore already held!
526 static inline void locks_unlock_delete(struct file_lock **thisfl_p)
528 struct file_lock *fl = *thisfl_p;
529 int (*lock)(struct file *, int, struct file_lock *);
531 _unhash_lock(thisfl_p);
532 if (fl->fl_file->f_op &&
533 (lock = fl->fl_file->f_op->lock) != NULL) {
534 fl->fl_type = F_UNLCK;
535 lock(fl->fl_file, F_SETLK, fl);
540 /* Determine if lock sys_fl blocks lock caller_fl. Common functionality
541 * checks for shared/exclusive status of overlapping locks.
543 static int locks_conflict(struct file_lock *caller_fl, struct file_lock *sys_fl)
545 switch (caller_fl->fl_type) {
547 return (sys_fl->fl_type == F_WRLCK);
553 printk(KERN_ERR "locks_conflict(): impossible lock type - %d\n",
557 return (0); /* This should never happen */
560 /* Determine if lock sys_fl blocks lock caller_fl. POSIX specific
561 * checking before calling the locks_conflict().
563 static int posix_locks_conflict(struct file_lock *caller_fl, struct file_lock *sys_fl)
565 /* POSIX locks owned by the same process do not conflict with
568 if (!(sys_fl->fl_flags & FL_POSIX) ||
569 locks_same_owner(caller_fl, sys_fl))
572 /* Check whether they overlap */
573 if (!locks_overlap(caller_fl, sys_fl))
576 return (locks_conflict(caller_fl, sys_fl));
579 /* Determine if lock sys_fl blocks lock caller_fl. FLOCK specific
580 * checking before calling the locks_conflict().
582 static int flock_locks_conflict(struct file_lock *caller_fl, struct file_lock *sys_fl)
584 /* FLOCK locks referring to the same filp do not conflict with
587 if (!(sys_fl->fl_flags & FL_FLOCK) ||
588 (caller_fl->fl_file == sys_fl->fl_file))
591 if ((caller_fl->fl_type & LOCK_MAND) || (sys_fl->fl_type & LOCK_MAND))
595 return (locks_conflict(caller_fl, sys_fl));
598 static int interruptible_sleep_on_locked(wait_queue_head_t *fl_wait, int timeout)
601 DECLARE_WAITQUEUE(wait, current);
603 current->state = TASK_INTERRUPTIBLE;
604 add_wait_queue(fl_wait, &wait);
608 result = schedule_timeout(timeout);
609 if (signal_pending(current))
610 result = -ERESTARTSYS;
611 remove_wait_queue(fl_wait, &wait);
612 current->state = TASK_RUNNING;
616 static int locks_block_on(struct file_lock *blocker, struct file_lock *waiter)
619 locks_insert_block(blocker, waiter);
620 result = interruptible_sleep_on_locked(&waiter->fl_wait, 0);
621 locks_delete_block(waiter);
625 static int locks_block_on_timeout(struct file_lock *blocker, struct file_lock *waiter, int time)
628 locks_insert_block(blocker, waiter);
629 result = interruptible_sleep_on_locked(&waiter->fl_wait, time);
630 locks_delete_block(waiter);
635 posix_test_lock(struct file *filp, struct file_lock *fl)
637 struct file_lock *cfl;
640 for (cfl = filp->f_dentry->d_inode->i_flock; cfl; cfl = cfl->fl_next) {
641 if (!(cfl->fl_flags & FL_POSIX))
643 if (posix_locks_conflict(cfl, fl))
651 /* This function tests for deadlock condition before putting a process to
652 * sleep. The detection scheme is no longer recursive. Recursive was neat,
653 * but dangerous - we risked stack corruption if the lock data was bad, or
654 * if the recursion was too deep for any other reason.
656 * We rely on the fact that a task can only be on one lock's wait queue
657 * at a time. When we find blocked_task on a wait queue we can re-search
658 * with blocked_task equal to that queue's owner, until either blocked_task
659 * isn't found, or blocked_task is found on a queue owned by my_task.
661 * Note: the above assumption may not be true when handling lock requests
662 * from a broken NFS client. But broken NFS clients have a lot more to
663 * worry about than proper deadlock detection anyway... --okir
665 int posix_locks_deadlock(struct file_lock *caller_fl,
666 struct file_lock *block_fl)
668 struct list_head *tmp;
669 fl_owner_t caller_owner, blocked_owner;
670 unsigned int caller_pid, blocked_pid;
672 caller_owner = caller_fl->fl_owner;
673 caller_pid = caller_fl->fl_pid;
674 blocked_owner = block_fl->fl_owner;
675 blocked_pid = block_fl->fl_pid;
678 if (caller_owner == blocked_owner && caller_pid == blocked_pid)
680 list_for_each(tmp, &blocked_list) {
681 struct file_lock *fl = list_entry(tmp, struct file_lock, fl_link);
682 if ((fl->fl_owner == blocked_owner)
683 && (fl->fl_pid == blocked_pid)) {
685 blocked_owner = fl->fl_owner;
686 blocked_pid = fl->fl_pid;
693 int locks_mandatory_locked(struct inode *inode)
695 fl_owner_t owner = current->files;
696 struct file_lock *fl;
699 * Search the lock list for this inode for any POSIX locks.
702 for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) {
703 if (!(fl->fl_flags & FL_POSIX))
705 if (fl->fl_owner != owner)
709 return fl ? -EAGAIN : 0;
712 int locks_mandatory_area(int read_write, struct inode *inode,
713 struct file *filp, loff_t offset,
716 struct file_lock *fl;
717 struct file_lock *new_fl = locks_alloc_lock();
723 new_fl->fl_owner = current->files;
724 new_fl->fl_pid = current->pid;
725 new_fl->fl_file = filp;
726 new_fl->fl_flags = FL_POSIX | FL_ACCESS;
727 new_fl->fl_type = (read_write == FLOCK_VERIFY_WRITE) ? F_WRLCK : F_RDLCK;
728 new_fl->fl_start = offset;
729 new_fl->fl_end = offset + count - 1;
735 /* Search the lock list for this inode for locks that conflict with
736 * the proposed read/write.
738 for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) {
739 if (!(fl->fl_flags & FL_POSIX))
741 if (fl->fl_start > new_fl->fl_end)
743 if (posix_locks_conflict(new_fl, fl)) {
745 if (filp && (filp->f_flags & O_NONBLOCK))
748 if (posix_locks_deadlock(new_fl, fl))
751 error = locks_block_on(fl, new_fl);
756 * If we've been sleeping someone might have
757 * changed the permissions behind our back.
759 if ((inode->i_mode & (S_ISGID | S_IXGRP)) != S_ISGID)
764 locks_free_lock(new_fl);
769 /* Try to create a FLOCK lock on filp. We always insert new FLOCK locks
770 * at the head of the list, but that's secret knowledge known only to
771 * flock_lock_file and posix_lock_file.
773 static int flock_lock_file(struct file *filp, unsigned int lock_type,
776 struct file_lock *fl;
777 struct file_lock *new_fl = NULL;
778 struct file_lock **before;
779 struct inode * inode = filp->f_dentry->d_inode;
781 int unlock = (lock_type == F_UNLCK);
784 * If we need a new lock, get it in advance to avoid races.
788 new_fl = flock_make_lock(filp, lock_type);
796 before = &inode->i_flock;
797 while (((fl = *before) != NULL) && (fl->fl_flags & FL_FLOCK)) {
798 if (filp == fl->fl_file) {
799 if (lock_type == fl->fl_type)
804 before = &fl->fl_next;
806 /* change means that we are changing the type of an existing lock,
807 * or else unlocking it.
810 /* N.B. What if the wait argument is false? */
811 locks_delete_lock(before, !unlock);
813 * If we waited, another lock may have been added ...
822 for (fl = inode->i_flock; (fl != NULL) && (fl->fl_flags & FL_FLOCK);
824 if (!flock_locks_conflict(new_fl, fl))
829 error = locks_block_on(fl, new_fl);
834 locks_insert_lock(&inode->i_flock, new_fl);
840 locks_free_lock(new_fl);
846 * @filp: The file to apply the lock to
847 * @caller: The lock to be applied
848 * @wait: 1 to retry automatically, 0 to return -EAGAIN
850 * Add a POSIX style lock to a file.
851 * We merge adjacent locks whenever possible. POSIX locks are sorted by owner
852 * task, then by starting address
855 * To make freeing a lock much faster, we keep a pointer to the lock before the
856 * actual one. But the real gain of the new coding was, that lock_it() and
857 * unlock_it() became one function.
859 * To all purists: Yes, I use a few goto's. Just pass on to the next function.
862 int posix_lock_file(struct file *filp, struct file_lock *caller,
865 struct file_lock *fl;
866 struct file_lock *new_fl, *new_fl2;
867 struct file_lock *left = NULL;
868 struct file_lock *right = NULL;
869 struct file_lock **before;
870 struct inode * inode = filp->f_dentry->d_inode;
871 int error, added = 0;
874 * We may need two file_lock structures for this operation,
875 * so we get them in advance to avoid races.
877 new_fl = locks_alloc_lock();
878 new_fl2 = locks_alloc_lock();
879 error = -ENOLCK; /* "no luck" */
880 if (!(new_fl && new_fl2))
884 if (caller->fl_type != F_UNLCK) {
886 for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) {
887 if (!(fl->fl_flags & FL_POSIX))
889 if (!posix_locks_conflict(caller, fl))
895 if (posix_locks_deadlock(caller, fl))
898 error = locks_block_on(fl, caller);
906 * We've allocated the new locks in advance, so there are no
907 * errors possible (and no blocking operations) from here on.
909 * Find the first old lock with the same owner as the new lock.
912 before = &inode->i_flock;
914 /* First skip locks owned by other processes.
916 while ((fl = *before) && (!(fl->fl_flags & FL_POSIX) ||
917 !locks_same_owner(caller, fl))) {
918 before = &fl->fl_next;
921 /* Process locks with this owner.
923 while ((fl = *before) && locks_same_owner(caller, fl)) {
924 /* Detect adjacent or overlapping regions (if same lock type)
926 if (caller->fl_type == fl->fl_type) {
927 if (fl->fl_end < caller->fl_start - 1)
929 /* If the next lock in the list has entirely bigger
930 * addresses than the new one, insert the lock here.
932 if (fl->fl_start > caller->fl_end + 1)
935 /* If we come here, the new and old lock are of the
936 * same type and adjacent or overlapping. Make one
937 * lock yielding from the lower start address of both
938 * locks to the higher end address.
940 if (fl->fl_start > caller->fl_start)
941 fl->fl_start = caller->fl_start;
943 caller->fl_start = fl->fl_start;
944 if (fl->fl_end < caller->fl_end)
945 fl->fl_end = caller->fl_end;
947 caller->fl_end = fl->fl_end;
949 locks_delete_lock(before, 0);
956 /* Processing for different lock types is a bit
959 if (fl->fl_end < caller->fl_start)
961 if (fl->fl_start > caller->fl_end)
963 if (caller->fl_type == F_UNLCK)
965 if (fl->fl_start < caller->fl_start)
967 /* If the next lock in the list has a higher end
968 * address than the new one, insert the new one here.
970 if (fl->fl_end > caller->fl_end) {
974 if (fl->fl_start >= caller->fl_start) {
975 /* The new lock completely replaces an old
976 * one (This may happen several times).
979 locks_delete_lock(before, 0);
982 /* Replace the old lock with the new one.
983 * Wake up anybody waiting for the old one,
984 * as the change in lock type might satisfy
987 locks_wake_up_blocks(fl, 0); /* This cannot schedule()! */
988 fl->fl_start = caller->fl_start;
989 fl->fl_end = caller->fl_end;
990 fl->fl_type = caller->fl_type;
991 fl->fl_u = caller->fl_u;
996 /* Go on to next lock.
999 before = &fl->fl_next;
1004 if (caller->fl_type == F_UNLCK)
1006 locks_copy_lock(new_fl, caller);
1007 locks_insert_lock(before, new_fl);
1011 if (left == right) {
1012 /* The new lock breaks the old one in two pieces,
1013 * so we have to use the second new lock.
1017 locks_copy_lock(left, right);
1018 locks_insert_lock(before, left);
1020 right->fl_start = caller->fl_end + 1;
1021 locks_wake_up_blocks(right, 0);
1024 left->fl_end = caller->fl_start - 1;
1025 locks_wake_up_blocks(left, 0);
1031 * Free any unused locks.
1034 locks_free_lock(new_fl);
1036 locks_free_lock(new_fl2);
1040 static inline int flock_translate_cmd(int cmd) {
1042 if (cmd & LOCK_MAND)
1043 return cmd & (LOCK_MAND | LOCK_RW);
1045 switch (cmd &~ LOCK_NB) {
1056 /* We already had a lease on this file; just change its type */
1057 static int lease_modify(struct file_lock **before, int arg)
1059 struct file_lock *fl = *before;
1060 int error = assign_type(fl, arg);
1064 locks_wake_up_blocks(fl, 0);
1065 if (arg == F_UNLCK) {
1066 struct file *filp = fl->fl_file;
1068 filp->f_owner.pid = 0;
1069 filp->f_owner.uid = 0;
1070 filp->f_owner.euid = 0;
1071 filp->f_owner.signum = 0;
1072 locks_delete_lock(before, 0);
1077 static void time_out_leases(struct inode *inode)
1079 struct file_lock **before;
1080 struct file_lock *fl;
1082 before = &inode->i_flock;
1083 while ((fl = *before) && (fl->fl_flags & FL_LEASE)
1084 && (fl->fl_type & F_INPROGRESS)) {
1085 if ((fl->fl_break_time == 0)
1086 || time_before(jiffies, fl->fl_break_time)) {
1087 before = &fl->fl_next;
1090 lease_modify(before, fl->fl_type & ~F_INPROGRESS);
1091 if (fl == *before) /* lease_modify may have freed fl */
1092 before = &fl->fl_next;
1097 * __get_lease - revoke all outstanding leases on file
1098 * @inode: the inode of the file to return
1099 * @mode: the open mode (read or write)
1101 * get_lease (inlined for speed) has checked there already
1102 * is a lease on this file. Leases are broken on a call to open()
1103 * or truncate(). This function can sleep unless you
1104 * specified %O_NONBLOCK to your open().
1106 int __get_lease(struct inode *inode, unsigned int mode)
1108 int error = 0, future;
1109 struct file_lock *new_fl, *flock;
1110 struct file_lock *fl;
1112 unsigned long break_time;
1113 int i_have_this_lease = 0;
1115 alloc_err = lease_alloc(NULL, mode & FMODE_WRITE ? F_WRLCK : F_RDLCK,
1120 time_out_leases(inode);
1122 flock = inode->i_flock;
1123 if ((flock == NULL) || (flock->fl_flags & FL_LEASE) == 0)
1126 for (fl = flock; fl && (fl->fl_flags & FL_LEASE); fl = fl->fl_next)
1127 if (fl->fl_owner == current->files)
1128 i_have_this_lease = 1;
1130 if (mode & FMODE_WRITE) {
1131 /* If we want write access, we have to revoke any lease. */
1132 future = F_UNLCK | F_INPROGRESS;
1133 } else if (flock->fl_type & F_INPROGRESS) {
1134 /* If the lease is already being broken, we just leave it */
1135 future = flock->fl_type;
1136 } else if (flock->fl_type & F_WRLCK) {
1137 /* Downgrade the exclusive lease to a read-only lease. */
1138 future = F_RDLCK | F_INPROGRESS;
1140 /* the existing lease was read-only, so we can read too. */
1144 if (alloc_err && !i_have_this_lease && ((mode & O_NONBLOCK) == 0)) {
1150 if (lease_break_time > 0) {
1151 break_time = jiffies + lease_break_time * HZ;
1152 if (break_time == 0)
1153 break_time++; /* so that 0 means no break time */
1156 for (fl = flock; fl && (fl->fl_flags & FL_LEASE); fl = fl->fl_next) {
1157 if (fl->fl_type != future) {
1158 fl->fl_type = future;
1159 fl->fl_break_time = break_time;
1160 kill_fasync(&fl->fl_fasync, SIGIO, POLL_MSG);
1164 if (i_have_this_lease || (mode & O_NONBLOCK)) {
1165 error = -EWOULDBLOCK;
1170 break_time = flock->fl_break_time;
1171 if (break_time != 0) {
1172 break_time -= jiffies;
1173 if (break_time == 0)
1176 error = locks_block_on_timeout(flock, new_fl, break_time);
1179 time_out_leases(inode);
1180 /* Wait for the next lease that has not been broken yet */
1181 for (flock = inode->i_flock;
1182 flock && (flock->fl_flags & FL_LEASE);
1183 flock = flock->fl_next) {
1184 if (flock->fl_type & F_INPROGRESS)
1193 locks_free_lock(new_fl);
1201 * This is to force NFS clients to flush their caches for files with
1202 * exclusive leases. The justification is that if someone has an
1203 * exclusive lease, then they could be modifiying it.
1205 time_t lease_get_mtime(struct inode *inode)
1207 struct file_lock *flock = inode->i_flock;
1208 if (flock && (flock->fl_flags & FL_LEASE) && (flock->fl_type & F_WRLCK))
1209 return CURRENT_TIME;
1210 return inode->i_mtime;
1214 * fcntl_getlease - Enquire what lease is currently active
1217 * The value returned by this function will be one of
1218 * (if no lease break is pending):
1220 * %F_RDLCK to indicate a shared lease is held.
1222 * %F_WRLCK to indicate an exclusive lease is held.
1224 * %F_UNLCK to indicate no lease is held.
1226 * (if a lease break is pending):
1228 * %F_RDLCK to indicate an exclusive lease needs to be
1229 * changed to a shared lease (or removed).
1231 * %F_UNLCK to indicate the lease needs to be removed.
1233 * XXX: sfr & willy disagree over whether F_INPROGRESS
1234 * should be returned to userspace.
1236 int fcntl_getlease(struct file *filp)
1238 struct file_lock *fl;
1242 time_out_leases(filp->f_dentry->d_inode);
1243 for (fl = filp->f_dentry->d_inode->i_flock;
1244 fl && (fl->fl_flags & FL_LEASE);
1246 if (fl->fl_file == filp) {
1247 type = fl->fl_type & ~F_INPROGRESS;
1256 * fcntl_setlease - sets a lease on an open file
1257 * @fd: open file descriptor
1258 * @filp: file pointer
1259 * @arg: type of lease to obtain
1261 * Call this fcntl to establish a lease on the file.
1262 * Note that you also need to call %F_SETSIG to
1263 * receive a signal when the lease is broken.
1265 int fcntl_setlease(unsigned int fd, struct file *filp, long arg)
1267 struct file_lock *fl, **before, **my_before = NULL;
1268 struct dentry *dentry;
1269 struct inode *inode;
1270 int error, rdlease_count = 0, wrlease_count = 0;
1272 dentry = filp->f_dentry;
1273 inode = dentry->d_inode;
1275 if ((current->fsuid != inode->i_uid) && !capable(CAP_LEASE))
1277 if (!S_ISREG(inode->i_mode))
1282 time_out_leases(inode);
1285 * FIXME: What about F_RDLCK and files open for writing?
1288 if ((arg == F_WRLCK)
1289 && ((atomic_read(&dentry->d_count) > 1)
1290 || (atomic_read(&inode->i_count) > 1)))
1294 * At this point, we know that if there is an exclusive
1295 * lease on this file, then we hold it on this filp
1296 * (otherwise our open of this file would have blocked).
1297 * And if we are trying to acquire an exclusive lease,
1298 * then the file is not open by anyone (including us)
1299 * except for this filp.
1301 for (before = &inode->i_flock;
1302 ((fl = *before) != NULL) && (fl->fl_flags & FL_LEASE);
1303 before = &fl->fl_next) {
1304 if (fl->fl_file == filp)
1306 else if (fl->fl_type == (F_INPROGRESS | F_UNLCK))
1308 * Someone is in the process of opening this
1309 * file for writing so we may not take an
1310 * exclusive lease on it.
1317 if ((arg == F_RDLCK && (wrlease_count > 0)) ||
1318 (arg == F_WRLCK && ((rdlease_count + wrlease_count) > 0)))
1321 if (my_before != NULL) {
1322 error = lease_modify(my_before, arg);
1334 error = lease_alloc(filp, arg, &fl);
1338 error = fasync_helper(fd, filp, 1, &fl->fl_fasync);
1340 locks_free_lock(fl);
1343 fl->fl_next = *before;
1345 list_add(&fl->fl_link, &file_lock_list);
1346 filp->f_owner.pid = current->pid;
1347 filp->f_owner.uid = current->uid;
1348 filp->f_owner.euid = current->euid;
1355 * sys_flock: - flock() system call.
1356 * @fd: the file descriptor to lock.
1357 * @cmd: the type of lock to apply.
1359 * Apply a %FL_FLOCK style lock to an open file descriptor.
1360 * The @cmd can be one of
1362 * %LOCK_SH -- a shared lock.
1364 * %LOCK_EX -- an exclusive lock.
1366 * %LOCK_UN -- remove an existing lock.
1368 * %LOCK_MAND -- a `mandatory' flock. This exists to emulate Windows Share Modes.
1370 * %LOCK_MAND can be combined with %LOCK_READ or %LOCK_WRITE to allow other
1371 * processes read and write access respectively.
1373 asmlinkage long sys_flock(unsigned int fd, unsigned int cmd)
1383 error = flock_translate_cmd(cmd);
1389 if ((type != F_UNLCK)
1391 && !(type & LOCK_MAND)
1393 && !(filp->f_mode & 3))
1397 error = flock_lock_file(filp, type,
1398 (cmd & (LOCK_UN | LOCK_NB)) ? 0 : 1);
1407 /* Report the first existing lock that would conflict with l.
1408 * This implements the F_GETLK command of fcntl().
1410 int fcntl_getlk(unsigned int fd, struct flock *l)
1413 struct file_lock *fl, file_lock;
1418 if (copy_from_user(&flock, l, sizeof(flock)))
1421 if ((flock.l_type != F_RDLCK) && (flock.l_type != F_WRLCK))
1429 error = flock_to_posix_lock(filp, &file_lock, &flock);
1433 if (filp->f_op && filp->f_op->lock) {
1434 error = filp->f_op->lock(filp, F_GETLK, &file_lock);
1437 else if (error == LOCK_USE_CLNT)
1438 /* Bypass for NFS with no locking - 2.0.36 compat */
1439 fl = posix_test_lock(filp, &file_lock);
1441 fl = (file_lock.fl_type == F_UNLCK ? NULL : &file_lock);
1443 fl = posix_test_lock(filp, &file_lock);
1446 flock.l_type = F_UNLCK;
1448 flock.l_pid = fl->fl_pid;
1449 #if BITS_PER_LONG == 32
1451 * Make sure we can represent the posix lock via
1452 * legacy 32bit flock.
1455 if (fl->fl_start > OFFT_OFFSET_MAX)
1457 if ((fl->fl_end != OFFSET_MAX)
1458 && (fl->fl_end > OFFT_OFFSET_MAX))
1461 flock.l_start = fl->fl_start;
1462 flock.l_len = fl->fl_end == OFFSET_MAX ? 0 :
1463 fl->fl_end - fl->fl_start + 1;
1465 flock.l_type = fl->fl_type;
1468 if (!copy_to_user(l, &flock, sizeof(flock)))
1477 /* Apply the lock described by l to an open file descriptor.
1478 * This implements both the F_SETLK and F_SETLKW commands of fcntl().
1480 int fcntl_setlk(unsigned int fd, unsigned int cmd, struct flock *l)
1483 struct file_lock *file_lock = locks_alloc_lock();
1485 struct inode *inode;
1488 if (file_lock == NULL)
1492 * This might block, so we do it before checking the inode.
1495 if (copy_from_user(&flock, l, sizeof(flock)))
1498 /* Get arguments and validate them ...
1507 inode = filp->f_dentry->d_inode;
1509 /* Don't allow mandatory locks on files that may be memory mapped
1512 if (IS_MANDLOCK(inode) &&
1513 (inode->i_mode & (S_ISGID | S_IXGRP)) == S_ISGID) {
1514 struct address_space *mapping = inode->i_mapping;
1516 if (mapping->i_mmap_shared != NULL) {
1522 error = flock_to_posix_lock(filp, file_lock, &flock);
1527 switch (flock.l_type) {
1529 if (!(filp->f_mode & FMODE_READ))
1533 if (!(filp->f_mode & FMODE_WRITE))
1541 /* warn a bit for now, but don't overdo it */
1543 static int count = 0;
1547 "fcntl_setlk() called by process %d (%s) with broken flock() emulation\n",
1548 current->pid, current->comm);
1551 if (!(filp->f_mode & 3))
1560 if (filp->f_op && filp->f_op->lock != NULL) {
1561 error = filp->f_op->lock(filp, cmd, file_lock);
1565 error = posix_lock_file(filp, file_lock, cmd == F_SETLKW);
1570 locks_free_lock(file_lock);
1574 #if BITS_PER_LONG == 32
1575 /* Report the first existing lock that would conflict with l.
1576 * This implements the F_GETLK command of fcntl().
1578 int fcntl_getlk64(unsigned int fd, struct flock64 *l)
1581 struct file_lock *fl, file_lock;
1582 struct flock64 flock;
1586 if (copy_from_user(&flock, l, sizeof(flock)))
1589 if ((flock.l_type != F_RDLCK) && (flock.l_type != F_WRLCK))
1597 error = flock64_to_posix_lock(filp, &file_lock, &flock);
1601 if (filp->f_op && filp->f_op->lock) {
1602 error = filp->f_op->lock(filp, F_GETLK, &file_lock);
1605 else if (error == LOCK_USE_CLNT)
1606 /* Bypass for NFS with no locking - 2.0.36 compat */
1607 fl = posix_test_lock(filp, &file_lock);
1609 fl = (file_lock.fl_type == F_UNLCK ? NULL : &file_lock);
1611 fl = posix_test_lock(filp, &file_lock);
1614 flock.l_type = F_UNLCK;
1616 flock.l_pid = fl->fl_pid;
1617 flock.l_start = fl->fl_start;
1618 flock.l_len = fl->fl_end == OFFSET_MAX ? 0 :
1619 fl->fl_end - fl->fl_start + 1;
1621 flock.l_type = fl->fl_type;
1624 if (!copy_to_user(l, &flock, sizeof(flock)))
1633 /* Apply the lock described by l to an open file descriptor.
1634 * This implements both the F_SETLK and F_SETLKW commands of fcntl().
1636 int fcntl_setlk64(unsigned int fd, unsigned int cmd, struct flock64 *l)
1639 struct file_lock *file_lock = locks_alloc_lock();
1640 struct flock64 flock;
1641 struct inode *inode;
1644 if (file_lock == NULL)
1648 * This might block, so we do it before checking the inode.
1651 if (copy_from_user(&flock, l, sizeof(flock)))
1654 /* Get arguments and validate them ...
1663 inode = filp->f_dentry->d_inode;
1665 /* Don't allow mandatory locks on files that may be memory mapped
1668 if (IS_MANDLOCK(inode) &&
1669 (inode->i_mode & (S_ISGID | S_IXGRP)) == S_ISGID) {
1670 struct address_space *mapping = inode->i_mapping;
1672 if (mapping->i_mmap_shared != NULL) {
1678 error = flock64_to_posix_lock(filp, file_lock, &flock);
1683 switch (flock.l_type) {
1685 if (!(filp->f_mode & FMODE_READ))
1689 if (!(filp->f_mode & FMODE_WRITE))
1701 if (filp->f_op && filp->f_op->lock != NULL) {
1702 error = filp->f_op->lock(filp, cmd, file_lock);
1706 error = posix_lock_file(filp, file_lock, cmd == F_SETLKW64);
1711 locks_free_lock(file_lock);
1714 #endif /* BITS_PER_LONG == 32 */
1717 * This function is called when the file is being removed
1718 * from the task's fd array.
1720 void locks_remove_posix(struct file *filp, fl_owner_t owner)
1722 struct inode * inode = filp->f_dentry->d_inode;
1723 struct file_lock *fl;
1724 struct file_lock **before;
1727 * For POSIX locks we free all locks on this file for the given task.
1729 if (!inode->i_flock) {
1731 * Notice that something might be grabbing a lock right now.
1732 * Consider it as a race won by us - event is async, so even if
1733 * we miss the lock added we can trivially consider it as added
1734 * after we went through this call.
1739 before = &inode->i_flock;
1740 while ((fl = *before) != NULL) {
1741 if ((fl->fl_flags & FL_POSIX) && fl->fl_owner == owner) {
1742 struct file *filp = fl->fl_file;
1743 /* Note: locks_unlock_delete() can sleep, and
1744 * so we may race with the call to sys_close()
1745 * by the thread that actually owns this filp.
1748 locks_unlock_delete(before);
1750 before = &inode->i_flock;
1753 before = &fl->fl_next;
1759 * This function is called on the last close of an open file.
1761 void locks_remove_flock(struct file *filp)
1763 struct inode * inode = filp->f_dentry->d_inode;
1764 struct file_lock *fl;
1765 struct file_lock **before;
1767 if (!inode->i_flock)
1771 before = &inode->i_flock;
1773 while ((fl = *before) != NULL) {
1774 if (fl->fl_file == filp) {
1775 if (fl->fl_flags & FL_FLOCK) {
1776 locks_delete_lock(before, 0);
1779 if (fl->fl_flags & FL_LEASE) {
1780 lease_modify(before, F_UNLCK);
1784 before = &fl->fl_next;
1790 * posix_block_lock - blocks waiting for a file lock
1791 * @blocker: the lock which is blocking
1792 * @waiter: the lock which conflicts and has to wait
1794 * lockd needs to block waiting for locks.
1797 posix_block_lock(struct file_lock *blocker, struct file_lock *waiter)
1799 locks_insert_block(blocker, waiter);
1803 * posix_unblock_lock - stop waiting for a file lock
1804 * @waiter: the lock which was waiting
1806 * lockd needs to block waiting for locks.
1809 posix_unblock_lock(struct file_lock *waiter)
1811 if (!list_empty(&waiter->fl_block))
1812 locks_delete_block(waiter);
1815 static void lock_get_status(char* out, struct file_lock *fl, int id, char *pfx)
1817 struct inode *inode = NULL;
1819 if (fl->fl_file != NULL)
1820 inode = fl->fl_file->f_dentry->d_inode;
1822 out += sprintf(out, "%d:%s ", id, pfx);
1823 if (fl->fl_flags & FL_POSIX) {
1824 out += sprintf(out, "%6s %s ",
1825 (fl->fl_flags & FL_ACCESS) ? "ACCESS" : "POSIX ",
1826 (inode == NULL) ? "*NOINODE*" :
1827 (IS_MANDLOCK(inode) &&
1828 (inode->i_mode & (S_IXGRP | S_ISGID)) == S_ISGID) ?
1829 "MANDATORY" : "ADVISORY ");
1830 } else if (fl->fl_flags & FL_FLOCK) {
1832 if (fl->fl_type & LOCK_MAND) {
1833 out += sprintf(out, "FLOCK MSNFS ");
1836 out += sprintf(out, "FLOCK ADVISORY ");
1837 } else if (fl->fl_flags & FL_LEASE) {
1838 out += sprintf(out, "LEASE ");
1839 if (fl->fl_type & F_INPROGRESS)
1840 out += sprintf(out, "BREAKING ");
1841 else if (fl->fl_file)
1842 out += sprintf(out, "ACTIVE ");
1844 out += sprintf(out, "BREAKER ");
1846 out += sprintf(out, "UNKNOWN UNKNOWN ");
1849 if (fl->fl_type & LOCK_MAND) {
1850 out += sprintf(out, "%s ",
1851 (fl->fl_type & LOCK_READ)
1852 ? (fl->fl_type & LOCK_WRITE) ? "RW " : "READ "
1853 : (fl->fl_type & LOCK_WRITE) ? "WRITE" : "NONE ");
1856 out += sprintf(out, "%s ",
1857 (fl->fl_type & F_INPROGRESS)
1858 ? (fl->fl_type & F_UNLCK) ? "UNLCK" : "READ "
1859 : (fl->fl_type & F_WRLCK) ? "WRITE" : "READ ");
1860 out += sprintf(out, "%d %s:%ld ",
1862 inode ? kdevname(inode->i_dev) : "<none>",
1863 inode ? inode->i_ino : 0);
1864 out += sprintf(out, "%Ld ", fl->fl_start);
1865 if (fl->fl_end == OFFSET_MAX)
1866 out += sprintf(out, "EOF ");
1868 out += sprintf(out, "%Ld ", fl->fl_end);
1869 sprintf(out, "%08lx %08lx %08lx %08lx %08lx\n",
1870 (long)fl, (long)fl->fl_link.prev, (long)fl->fl_link.next,
1871 (long)fl->fl_next, (long)fl->fl_block.next);
1874 static void move_lock_status(char **p, off_t* pos, off_t offset)
1878 if(*pos >= offset) {
1879 /* the complete line is valid */
1884 if(*pos+len > offset) {
1885 /* use the second part of the line */
1886 int i = offset-*pos;
1887 memmove(*p,*p+i,len-i);
1892 /* discard the complete line */
1897 * get_locks_status - reports lock usage in /proc/locks
1898 * @buffer: address in userspace to write into
1900 * @offset: how far we are through the buffer
1901 * @length: how much to read
1904 int get_locks_status(char *buffer, char **start, off_t offset, int length)
1906 struct list_head *tmp;
1912 list_for_each(tmp, &file_lock_list) {
1913 struct list_head *btmp;
1914 struct file_lock *fl = list_entry(tmp, struct file_lock, fl_link);
1915 lock_get_status(q, fl, ++i, "");
1916 move_lock_status(&q, &pos, offset);
1918 if(pos >= offset+length)
1921 list_for_each(btmp, &fl->fl_block) {
1922 struct file_lock *bfl = list_entry(btmp,
1923 struct file_lock, fl_block);
1924 lock_get_status(q, bfl, i, " ->");
1925 move_lock_status(&q, &pos, offset);
1927 if(pos >= offset+length)
1934 if(q-buffer < length)
1939 void steal_locks(fl_owner_t from)
1941 struct list_head *tmp;
1943 if (from == current->files)
1947 list_for_each(tmp, &file_lock_list) {
1948 struct file_lock *fl = list_entry(tmp, struct file_lock,
1950 if (fl->fl_owner == from)
1951 fl->fl_owner = current->files;
1958 * lock_may_read - checks that the region is free of locks
1959 * @inode: the inode that is being read
1960 * @start: the first byte to read
1961 * @len: the number of bytes to read
1963 * Emulates Windows locking requirements. Whole-file
1964 * mandatory locks (share modes) can prohibit a read and
1965 * byte-range POSIX locks can prohibit a read if they overlap.
1967 * N.B. this function is only ever called
1968 * from knfsd and ownership of locks is never checked.
1970 int lock_may_read(struct inode *inode, loff_t start, unsigned long len)
1972 struct file_lock *fl;
1975 for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) {
1976 if (fl->fl_flags == FL_POSIX) {
1977 if (fl->fl_type == F_RDLCK)
1979 if ((fl->fl_end < start) || (fl->fl_start > (start + len)))
1981 } else if (fl->fl_flags == FL_FLOCK) {
1982 if (!(fl->fl_type & LOCK_MAND))
1984 if (fl->fl_type & LOCK_READ)
1996 * lock_may_write - checks that the region is free of locks
1997 * @inode: the inode that is being written
1998 * @start: the first byte to write
1999 * @len: the number of bytes to write
2001 * Emulates Windows locking requirements. Whole-file
2002 * mandatory locks (share modes) can prohibit a write and
2003 * byte-range POSIX locks can prohibit a write if they overlap.
2005 * N.B. this function is only ever called
2006 * from knfsd and ownership of locks is never checked.
2008 int lock_may_write(struct inode *inode, loff_t start, unsigned long len)
2010 struct file_lock *fl;
2013 for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) {
2014 if (fl->fl_flags == FL_POSIX) {
2015 if ((fl->fl_end < start) || (fl->fl_start > (start + len)))
2017 } else if (fl->fl_flags == FL_FLOCK) {
2018 if (!(fl->fl_type & LOCK_MAND))
2020 if (fl->fl_type & LOCK_WRITE)
2032 static int __init filelock_init(void)
2034 filelock_cache = kmem_cache_create("file_lock_cache",
2035 sizeof(struct file_lock), 0, 0, init_once, NULL);
2036 if (!filelock_cache)
2037 panic("cannot create file lock slab cache");
2041 module_init(filelock_init)