blob: 1ad29c9b6252b28cc0e306fb893400293b598608 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * linux/fs/locks.c
3 *
4 * Provide support for fcntl()'s F_GETLK, F_SETLK, and F_SETLKW calls.
5 * Doug Evans (dje@spiff.uucp), August 07, 1992
6 *
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.
11 *
12 * Miscellaneous edits, and a total rewrite of posix_lock_file() code.
13 * Kai Petzke (wpp@marie.physik.tu-berlin.de), 1994
14 *
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
18 *
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
26 *
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
30 *
31 * Implemented two lock personalities - FL_FLOCK and FL_POSIX.
32 *
33 * FL_POSIX locks are created with calls to fcntl() and lockf() through the
34 * fcntl() system call. They have the semantics described above.
35 *
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.
39 *
40 * FL_FLOCK locks follow the 4.4 BSD flock() semantics. They are associated
41 * with a file pointer (filp). As a result they can be shared by a parent
42 * process and its children after a fork(). They are removed when the last
43 * file descriptor referring to the file pointer is closed (unless explicitly
44 * unlocked).
45 *
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
51 *
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.
55 *
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.
60 *
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.
65 *
66 * Don't allow mandatory locks on mmap()'ed files. Added simple functions to
67 * check if a file has mandatory locks, used by mmap(), open() and creat() to
68 * see if system call should be rejected. Ref. HP-UX/SunOS/Solaris Reference
69 * Manual, Section 2.
70 * Andy Walker (andy@lysaker.kvaerner.no), April 09, 1996.
71 *
72 * Tidied up block list handling. Added '/proc/locks' interface.
73 * Andy Walker (andy@lysaker.kvaerner.no), April 24, 1996.
74 *
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.
78 *
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.
84 *
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.
88 *
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.
93 *
94 * Made the block list a circular list to minimise searching in the list.
95 * Andy Walker (andy@lysaker.kvaerner.no), Sep 25, 1996.
96 *
97 * Made mandatory locking a mount option. Default is not to allow mandatory
98 * locking.
99 * Andy Walker (andy@lysaker.kvaerner.no), Oct 04, 1996.
100 *
101 * Some adaptations for NFS support.
102 * Olaf Kirch (okir@monad.swb.de), Dec 1996,
103 *
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.
106 *
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.
111 *
112 * Leases and LOCK_MAND
113 * Matthew Wilcox <willy@debian.org>, June, 2000.
114 * Stephen Rothwell <sfr@canb.auug.org.au>, June, 2000.
115 */
116
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/syscalls.h>
126#include <linux/time.h>
Dipankar Sarma4fb3a532005-09-16 19:28:13 -0700127#include <linux/rcupdate.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -0700128
129#include <asm/semaphore.h>
130#include <asm/uaccess.h>
131
132#define IS_POSIX(fl) (fl->fl_flags & FL_POSIX)
133#define IS_FLOCK(fl) (fl->fl_flags & FL_FLOCK)
134#define IS_LEASE(fl) (fl->fl_flags & FL_LEASE)
135
136int leases_enable = 1;
137int lease_break_time = 45;
138
139#define for_each_lock(inode, lockp) \
140 for (lockp = &inode->i_flock; *lockp != NULL; lockp = &(*lockp)->fl_next)
141
Christoph Hellwig26bcbf92006-03-20 13:44:40 -0500142static LIST_HEAD(file_lock_list);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700143static LIST_HEAD(blocked_list);
144
Eric Dumazetfa3536c2006-03-26 01:37:24 -0800145static kmem_cache_t *filelock_cache __read_mostly;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700146
147/* Allocate an empty lock structure. */
148static struct file_lock *locks_alloc_lock(void)
149{
150 return kmem_cache_alloc(filelock_cache, SLAB_KERNEL);
151}
152
Trond Myklebust47831f32006-03-20 13:44:05 -0500153static void locks_release_private(struct file_lock *fl)
154{
155 if (fl->fl_ops) {
156 if (fl->fl_ops->fl_release_private)
157 fl->fl_ops->fl_release_private(fl);
158 fl->fl_ops = NULL;
159 }
160 if (fl->fl_lmops) {
161 if (fl->fl_lmops->fl_release_private)
162 fl->fl_lmops->fl_release_private(fl);
163 fl->fl_lmops = NULL;
164 }
165
166}
167
Linus Torvalds1da177e2005-04-16 15:20:36 -0700168/* Free a lock which is not in use. */
Matt Mackall33443c42006-01-08 01:05:22 -0800169static void locks_free_lock(struct file_lock *fl)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700170{
Miklos Szeredi5ce29642006-03-31 02:30:29 -0800171 BUG_ON(waitqueue_active(&fl->fl_wait));
172 BUG_ON(!list_empty(&fl->fl_block));
173 BUG_ON(!list_empty(&fl->fl_link));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700174
Trond Myklebust47831f32006-03-20 13:44:05 -0500175 locks_release_private(fl);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700176 kmem_cache_free(filelock_cache, fl);
177}
178
179void locks_init_lock(struct file_lock *fl)
180{
181 INIT_LIST_HEAD(&fl->fl_link);
182 INIT_LIST_HEAD(&fl->fl_block);
183 init_waitqueue_head(&fl->fl_wait);
184 fl->fl_next = NULL;
185 fl->fl_fasync = NULL;
186 fl->fl_owner = NULL;
187 fl->fl_pid = 0;
188 fl->fl_file = NULL;
189 fl->fl_flags = 0;
190 fl->fl_type = 0;
191 fl->fl_start = fl->fl_end = 0;
192 fl->fl_ops = NULL;
193 fl->fl_lmops = NULL;
194}
195
196EXPORT_SYMBOL(locks_init_lock);
197
198/*
199 * Initialises the fields of the file lock which are invariant for
200 * free file_locks.
201 */
202static void init_once(void *foo, kmem_cache_t *cache, unsigned long flags)
203{
204 struct file_lock *lock = (struct file_lock *) foo;
205
206 if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) !=
207 SLAB_CTOR_CONSTRUCTOR)
208 return;
209
210 locks_init_lock(lock);
211}
212
Trond Myklebust47831f32006-03-20 13:44:05 -0500213static void locks_copy_private(struct file_lock *new, struct file_lock *fl)
214{
215 if (fl->fl_ops) {
216 if (fl->fl_ops->fl_copy_lock)
217 fl->fl_ops->fl_copy_lock(new, fl);
218 new->fl_ops = fl->fl_ops;
219 }
220 if (fl->fl_lmops) {
221 if (fl->fl_lmops->fl_copy_lock)
222 fl->fl_lmops->fl_copy_lock(new, fl);
223 new->fl_lmops = fl->fl_lmops;
224 }
225}
226
Linus Torvalds1da177e2005-04-16 15:20:36 -0700227/*
228 * Initialize a new lock from an existing file_lock structure.
229 */
Trond Myklebust09969052006-03-20 13:44:38 -0500230static void __locks_copy_lock(struct file_lock *new, const struct file_lock *fl)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700231{
232 new->fl_owner = fl->fl_owner;
233 new->fl_pid = fl->fl_pid;
Trond Myklebust09969052006-03-20 13:44:38 -0500234 new->fl_file = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700235 new->fl_flags = fl->fl_flags;
236 new->fl_type = fl->fl_type;
237 new->fl_start = fl->fl_start;
238 new->fl_end = fl->fl_end;
Trond Myklebust09969052006-03-20 13:44:38 -0500239 new->fl_ops = NULL;
240 new->fl_lmops = NULL;
241}
242
243void locks_copy_lock(struct file_lock *new, struct file_lock *fl)
244{
245 locks_release_private(new);
246
247 __locks_copy_lock(new, fl);
248 new->fl_file = fl->fl_file;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700249 new->fl_ops = fl->fl_ops;
250 new->fl_lmops = fl->fl_lmops;
Trond Myklebust47831f32006-03-20 13:44:05 -0500251
252 locks_copy_private(new, fl);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700253}
254
255EXPORT_SYMBOL(locks_copy_lock);
256
257static inline int flock_translate_cmd(int cmd) {
258 if (cmd & LOCK_MAND)
259 return cmd & (LOCK_MAND | LOCK_RW);
260 switch (cmd) {
261 case LOCK_SH:
262 return F_RDLCK;
263 case LOCK_EX:
264 return F_WRLCK;
265 case LOCK_UN:
266 return F_UNLCK;
267 }
268 return -EINVAL;
269}
270
271/* Fill in a file_lock structure with an appropriate FLOCK lock. */
272static int flock_make_lock(struct file *filp, struct file_lock **lock,
273 unsigned int cmd)
274{
275 struct file_lock *fl;
276 int type = flock_translate_cmd(cmd);
277 if (type < 0)
278 return type;
279
280 fl = locks_alloc_lock();
281 if (fl == NULL)
282 return -ENOMEM;
283
284 fl->fl_file = filp;
285 fl->fl_pid = current->tgid;
286 fl->fl_flags = FL_FLOCK;
287 fl->fl_type = type;
288 fl->fl_end = OFFSET_MAX;
289
290 *lock = fl;
291 return 0;
292}
293
294static int assign_type(struct file_lock *fl, int type)
295{
296 switch (type) {
297 case F_RDLCK:
298 case F_WRLCK:
299 case F_UNLCK:
300 fl->fl_type = type;
301 break;
302 default:
303 return -EINVAL;
304 }
305 return 0;
306}
307
308/* Verify a "struct flock" and copy it to a "struct file_lock" as a POSIX
309 * style lock.
310 */
311static int flock_to_posix_lock(struct file *filp, struct file_lock *fl,
312 struct flock *l)
313{
314 off_t start, end;
315
316 switch (l->l_whence) {
317 case 0: /*SEEK_SET*/
318 start = 0;
319 break;
320 case 1: /*SEEK_CUR*/
321 start = filp->f_pos;
322 break;
323 case 2: /*SEEK_END*/
324 start = i_size_read(filp->f_dentry->d_inode);
325 break;
326 default:
327 return -EINVAL;
328 }
329
330 /* POSIX-1996 leaves the case l->l_len < 0 undefined;
331 POSIX-2001 defines it. */
332 start += l->l_start;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700333 if (start < 0)
334 return -EINVAL;
Trond Myklebust4c780a42005-10-18 14:20:21 -0700335 fl->fl_end = OFFSET_MAX;
336 if (l->l_len > 0) {
337 end = start + l->l_len - 1;
338 fl->fl_end = end;
339 } else if (l->l_len < 0) {
340 end = start - 1;
341 fl->fl_end = end;
342 start += l->l_len;
343 if (start < 0)
344 return -EINVAL;
345 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700346 fl->fl_start = start; /* we record the absolute position */
Trond Myklebust4c780a42005-10-18 14:20:21 -0700347 if (fl->fl_end < fl->fl_start)
348 return -EOVERFLOW;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700349
350 fl->fl_owner = current->files;
351 fl->fl_pid = current->tgid;
352 fl->fl_file = filp;
353 fl->fl_flags = FL_POSIX;
354 fl->fl_ops = NULL;
355 fl->fl_lmops = NULL;
356
357 return assign_type(fl, l->l_type);
358}
359
360#if BITS_PER_LONG == 32
361static int flock64_to_posix_lock(struct file *filp, struct file_lock *fl,
362 struct flock64 *l)
363{
364 loff_t start;
365
366 switch (l->l_whence) {
367 case 0: /*SEEK_SET*/
368 start = 0;
369 break;
370 case 1: /*SEEK_CUR*/
371 start = filp->f_pos;
372 break;
373 case 2: /*SEEK_END*/
374 start = i_size_read(filp->f_dentry->d_inode);
375 break;
376 default:
377 return -EINVAL;
378 }
379
Trond Myklebust4c780a42005-10-18 14:20:21 -0700380 start += l->l_start;
381 if (start < 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700382 return -EINVAL;
Trond Myklebust4c780a42005-10-18 14:20:21 -0700383 fl->fl_end = OFFSET_MAX;
384 if (l->l_len > 0) {
385 fl->fl_end = start + l->l_len - 1;
386 } else if (l->l_len < 0) {
387 fl->fl_end = start - 1;
388 start += l->l_len;
389 if (start < 0)
390 return -EINVAL;
391 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700392 fl->fl_start = start; /* we record the absolute position */
Trond Myklebust4c780a42005-10-18 14:20:21 -0700393 if (fl->fl_end < fl->fl_start)
394 return -EOVERFLOW;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700395
396 fl->fl_owner = current->files;
397 fl->fl_pid = current->tgid;
398 fl->fl_file = filp;
399 fl->fl_flags = FL_POSIX;
400 fl->fl_ops = NULL;
401 fl->fl_lmops = NULL;
402
403 switch (l->l_type) {
404 case F_RDLCK:
405 case F_WRLCK:
406 case F_UNLCK:
407 fl->fl_type = l->l_type;
408 break;
409 default:
410 return -EINVAL;
411 }
412
413 return (0);
414}
415#endif
416
417/* default lease lock manager operations */
418static void lease_break_callback(struct file_lock *fl)
419{
420 kill_fasync(&fl->fl_fasync, SIGIO, POLL_MSG);
421}
422
423static void lease_release_private_callback(struct file_lock *fl)
424{
425 if (!fl->fl_file)
426 return;
427
428 f_delown(fl->fl_file);
429 fl->fl_file->f_owner.signum = 0;
430}
431
Adrian Bunk75c96f82005-05-05 16:16:09 -0700432static int lease_mylease_callback(struct file_lock *fl, struct file_lock *try)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700433{
434 return fl->fl_file == try->fl_file;
435}
436
Adrian Bunk75c96f82005-05-05 16:16:09 -0700437static struct lock_manager_operations lease_manager_ops = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700438 .fl_break = lease_break_callback,
439 .fl_release_private = lease_release_private_callback,
440 .fl_mylease = lease_mylease_callback,
441 .fl_change = lease_modify,
442};
443
444/*
445 * Initialize a lease, use the default lock manager operations
446 */
447static int lease_init(struct file *filp, int type, struct file_lock *fl)
448 {
Trond Myklebust75dff552006-05-07 23:02:42 -0400449 if (assign_type(fl, type) != 0)
450 return -EINVAL;
451
Linus Torvalds1da177e2005-04-16 15:20:36 -0700452 fl->fl_owner = current->files;
453 fl->fl_pid = current->tgid;
454
455 fl->fl_file = filp;
456 fl->fl_flags = FL_LEASE;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700457 fl->fl_start = 0;
458 fl->fl_end = OFFSET_MAX;
459 fl->fl_ops = NULL;
460 fl->fl_lmops = &lease_manager_ops;
461 return 0;
462}
463
464/* Allocate a file_lock initialised to this type of lease */
465static int lease_alloc(struct file *filp, int type, struct file_lock **flp)
466{
467 struct file_lock *fl = locks_alloc_lock();
Trond Myklebust75dff552006-05-07 23:02:42 -0400468 int error = -ENOMEM;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700469
470 if (fl == NULL)
Trond Myklebust75dff552006-05-07 23:02:42 -0400471 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700472
473 error = lease_init(filp, type, fl);
Trond Myklebust75dff552006-05-07 23:02:42 -0400474 if (error) {
475 locks_free_lock(fl);
476 fl = NULL;
477 }
478out:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700479 *flp = fl;
Trond Myklebust75dff552006-05-07 23:02:42 -0400480 return error;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700481}
482
483/* Check if two locks overlap each other.
484 */
485static inline int locks_overlap(struct file_lock *fl1, struct file_lock *fl2)
486{
487 return ((fl1->fl_end >= fl2->fl_start) &&
488 (fl2->fl_end >= fl1->fl_start));
489}
490
491/*
492 * Check whether two locks have the same owner.
493 */
Matt Mackall33443c42006-01-08 01:05:22 -0800494static int posix_same_owner(struct file_lock *fl1, struct file_lock *fl2)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700495{
496 if (fl1->fl_lmops && fl1->fl_lmops->fl_compare_owner)
497 return fl2->fl_lmops == fl1->fl_lmops &&
498 fl1->fl_lmops->fl_compare_owner(fl1, fl2);
499 return fl1->fl_owner == fl2->fl_owner;
500}
501
502/* Remove waiter from blocker's block list.
503 * When blocker ends up pointing to itself then the list is empty.
504 */
Matt Mackall33443c42006-01-08 01:05:22 -0800505static void __locks_delete_block(struct file_lock *waiter)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700506{
507 list_del_init(&waiter->fl_block);
508 list_del_init(&waiter->fl_link);
509 waiter->fl_next = NULL;
510}
511
512/*
513 */
514static void locks_delete_block(struct file_lock *waiter)
515{
516 lock_kernel();
517 __locks_delete_block(waiter);
518 unlock_kernel();
519}
520
521/* Insert waiter into blocker's block list.
522 * We use a circular list so that processes can be easily woken up in
523 * the order they blocked. The documentation doesn't require this but
524 * it seems like the reasonable thing to do.
525 */
526static void locks_insert_block(struct file_lock *blocker,
527 struct file_lock *waiter)
528{
J. Bruce Fields6dc0fe82006-03-26 01:37:24 -0800529 BUG_ON(!list_empty(&waiter->fl_block));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700530 list_add_tail(&waiter->fl_block, &blocker->fl_block);
531 waiter->fl_next = blocker;
532 if (IS_POSIX(blocker))
533 list_add(&waiter->fl_link, &blocked_list);
534}
535
536/* Wake up processes blocked waiting for blocker.
537 * If told to wait then schedule the processes until the block list
538 * is empty, otherwise empty the block list ourselves.
539 */
540static void locks_wake_up_blocks(struct file_lock *blocker)
541{
542 while (!list_empty(&blocker->fl_block)) {
543 struct file_lock *waiter = list_entry(blocker->fl_block.next,
544 struct file_lock, fl_block);
545 __locks_delete_block(waiter);
546 if (waiter->fl_lmops && waiter->fl_lmops->fl_notify)
547 waiter->fl_lmops->fl_notify(waiter);
548 else
549 wake_up(&waiter->fl_wait);
550 }
551}
552
553/* Insert file lock fl into an inode's lock list at the position indicated
554 * by pos. At the same time add the lock to the global file lock list.
555 */
556static void locks_insert_lock(struct file_lock **pos, struct file_lock *fl)
557{
558 list_add(&fl->fl_link, &file_lock_list);
559
560 /* insert into file's list */
561 fl->fl_next = *pos;
562 *pos = fl;
563
564 if (fl->fl_ops && fl->fl_ops->fl_insert)
565 fl->fl_ops->fl_insert(fl);
566}
567
568/*
569 * Delete a lock and then free it.
570 * Wake up processes that are blocked waiting for this lock,
571 * notify the FS that the lock has been cleared and
572 * finally free the lock.
573 */
574static void locks_delete_lock(struct file_lock **thisfl_p)
575{
576 struct file_lock *fl = *thisfl_p;
577
578 *thisfl_p = fl->fl_next;
579 fl->fl_next = NULL;
580 list_del_init(&fl->fl_link);
581
582 fasync_helper(0, fl->fl_file, 0, &fl->fl_fasync);
583 if (fl->fl_fasync != NULL) {
584 printk(KERN_ERR "locks_delete_lock: fasync == %p\n", fl->fl_fasync);
585 fl->fl_fasync = NULL;
586 }
587
588 if (fl->fl_ops && fl->fl_ops->fl_remove)
589 fl->fl_ops->fl_remove(fl);
590
591 locks_wake_up_blocks(fl);
592 locks_free_lock(fl);
593}
594
595/* Determine if lock sys_fl blocks lock caller_fl. Common functionality
596 * checks for shared/exclusive status of overlapping locks.
597 */
598static int locks_conflict(struct file_lock *caller_fl, struct file_lock *sys_fl)
599{
600 if (sys_fl->fl_type == F_WRLCK)
601 return 1;
602 if (caller_fl->fl_type == F_WRLCK)
603 return 1;
604 return 0;
605}
606
607/* Determine if lock sys_fl blocks lock caller_fl. POSIX specific
608 * checking before calling the locks_conflict().
609 */
610static int posix_locks_conflict(struct file_lock *caller_fl, struct file_lock *sys_fl)
611{
612 /* POSIX locks owned by the same process do not conflict with
613 * each other.
614 */
615 if (!IS_POSIX(sys_fl) || posix_same_owner(caller_fl, sys_fl))
616 return (0);
617
618 /* Check whether they overlap */
619 if (!locks_overlap(caller_fl, sys_fl))
620 return 0;
621
622 return (locks_conflict(caller_fl, sys_fl));
623}
624
625/* Determine if lock sys_fl blocks lock caller_fl. FLOCK specific
626 * checking before calling the locks_conflict().
627 */
628static int flock_locks_conflict(struct file_lock *caller_fl, struct file_lock *sys_fl)
629{
630 /* FLOCK locks referring to the same filp do not conflict with
631 * each other.
632 */
633 if (!IS_FLOCK(sys_fl) || (caller_fl->fl_file == sys_fl->fl_file))
634 return (0);
635 if ((caller_fl->fl_type & LOCK_MAND) || (sys_fl->fl_type & LOCK_MAND))
636 return 0;
637
638 return (locks_conflict(caller_fl, sys_fl));
639}
640
641static int interruptible_sleep_on_locked(wait_queue_head_t *fl_wait, int timeout)
642{
643 int result = 0;
644 DECLARE_WAITQUEUE(wait, current);
645
646 __set_current_state(TASK_INTERRUPTIBLE);
647 add_wait_queue(fl_wait, &wait);
648 if (timeout == 0)
649 schedule();
650 else
651 result = schedule_timeout(timeout);
652 if (signal_pending(current))
653 result = -ERESTARTSYS;
654 remove_wait_queue(fl_wait, &wait);
655 __set_current_state(TASK_RUNNING);
656 return result;
657}
658
659static int locks_block_on_timeout(struct file_lock *blocker, struct file_lock *waiter, int time)
660{
661 int result;
662 locks_insert_block(blocker, waiter);
663 result = interruptible_sleep_on_locked(&waiter->fl_wait, time);
664 __locks_delete_block(waiter);
665 return result;
666}
667
Andy Adamson8dc7c312006-03-20 13:44:26 -0500668int
669posix_test_lock(struct file *filp, struct file_lock *fl,
670 struct file_lock *conflock)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700671{
672 struct file_lock *cfl;
673
674 lock_kernel();
675 for (cfl = filp->f_dentry->d_inode->i_flock; cfl; cfl = cfl->fl_next) {
676 if (!IS_POSIX(cfl))
677 continue;
678 if (posix_locks_conflict(cfl, fl))
679 break;
680 }
Andy Adamson8dc7c312006-03-20 13:44:26 -0500681 if (cfl) {
Trond Myklebust09969052006-03-20 13:44:38 -0500682 __locks_copy_lock(conflock, cfl);
Andy Adamson8dc7c312006-03-20 13:44:26 -0500683 unlock_kernel();
684 return 1;
685 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700686 unlock_kernel();
Andy Adamson8dc7c312006-03-20 13:44:26 -0500687 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700688}
689
690EXPORT_SYMBOL(posix_test_lock);
691
692/* This function tests for deadlock condition before putting a process to
693 * sleep. The detection scheme is no longer recursive. Recursive was neat,
694 * but dangerous - we risked stack corruption if the lock data was bad, or
695 * if the recursion was too deep for any other reason.
696 *
697 * We rely on the fact that a task can only be on one lock's wait queue
698 * at a time. When we find blocked_task on a wait queue we can re-search
699 * with blocked_task equal to that queue's owner, until either blocked_task
700 * isn't found, or blocked_task is found on a queue owned by my_task.
701 *
702 * Note: the above assumption may not be true when handling lock requests
703 * from a broken NFS client. But broken NFS clients have a lot more to
704 * worry about than proper deadlock detection anyway... --okir
705 */
Adrian Bunkb0904e12006-06-23 02:05:13 -0700706static int posix_locks_deadlock(struct file_lock *caller_fl,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700707 struct file_lock *block_fl)
708{
709 struct list_head *tmp;
710
711next_task:
712 if (posix_same_owner(caller_fl, block_fl))
713 return 1;
714 list_for_each(tmp, &blocked_list) {
715 struct file_lock *fl = list_entry(tmp, struct file_lock, fl_link);
716 if (posix_same_owner(fl, block_fl)) {
717 fl = fl->fl_next;
718 block_fl = fl;
719 goto next_task;
720 }
721 }
722 return 0;
723}
724
Linus Torvalds1da177e2005-04-16 15:20:36 -0700725/* Try to create a FLOCK lock on filp. We always insert new FLOCK locks
726 * at the head of the list, but that's secret knowledge known only to
727 * flock_lock_file and posix_lock_file.
728 */
Trond Myklebust993dfa82006-03-31 02:30:55 -0800729static int flock_lock_file(struct file *filp, struct file_lock *request)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700730{
Trond Myklebust993dfa82006-03-31 02:30:55 -0800731 struct file_lock *new_fl = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700732 struct file_lock **before;
733 struct inode * inode = filp->f_dentry->d_inode;
734 int error = 0;
735 int found = 0;
736
737 lock_kernel();
738 for_each_lock(inode, before) {
739 struct file_lock *fl = *before;
740 if (IS_POSIX(fl))
741 break;
742 if (IS_LEASE(fl))
743 continue;
744 if (filp != fl->fl_file)
745 continue;
Trond Myklebust993dfa82006-03-31 02:30:55 -0800746 if (request->fl_type == fl->fl_type)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700747 goto out;
748 found = 1;
749 locks_delete_lock(before);
750 break;
751 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700752
Trond Myklebust993dfa82006-03-31 02:30:55 -0800753 if (request->fl_type == F_UNLCK)
754 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700755
Kirill Korotaev9cedc192006-06-14 17:59:35 +0400756 error = -ENOMEM;
Trond Myklebust993dfa82006-03-31 02:30:55 -0800757 new_fl = locks_alloc_lock();
758 if (new_fl == NULL)
759 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700760 /*
761 * If a higher-priority process was blocked on the old file lock,
762 * give it the opportunity to lock the file.
763 */
764 if (found)
765 cond_resched();
766
Linus Torvalds1da177e2005-04-16 15:20:36 -0700767 for_each_lock(inode, before) {
768 struct file_lock *fl = *before;
769 if (IS_POSIX(fl))
770 break;
771 if (IS_LEASE(fl))
772 continue;
Trond Myklebust993dfa82006-03-31 02:30:55 -0800773 if (!flock_locks_conflict(request, fl))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700774 continue;
775 error = -EAGAIN;
Trond Myklebust993dfa82006-03-31 02:30:55 -0800776 if (request->fl_flags & FL_SLEEP)
777 locks_insert_block(fl, request);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700778 goto out;
779 }
Trond Myklebust993dfa82006-03-31 02:30:55 -0800780 locks_copy_lock(new_fl, request);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700781 locks_insert_lock(&inode->i_flock, new_fl);
Trond Myklebust993dfa82006-03-31 02:30:55 -0800782 new_fl = NULL;
Kirill Korotaev9cedc192006-06-14 17:59:35 +0400783 error = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700784
785out:
786 unlock_kernel();
Trond Myklebust993dfa82006-03-31 02:30:55 -0800787 if (new_fl)
788 locks_free_lock(new_fl);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700789 return error;
790}
791
Andy Adamson5842add2006-03-26 01:37:26 -0800792static int __posix_lock_file_conf(struct inode *inode, struct file_lock *request, struct file_lock *conflock)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700793{
794 struct file_lock *fl;
Miklos Szeredi39005d02006-06-23 02:05:10 -0700795 struct file_lock *new_fl = NULL;
796 struct file_lock *new_fl2 = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700797 struct file_lock *left = NULL;
798 struct file_lock *right = NULL;
799 struct file_lock **before;
800 int error, added = 0;
801
802 /*
803 * We may need two file_lock structures for this operation,
804 * so we get them in advance to avoid races.
Miklos Szeredi39005d02006-06-23 02:05:10 -0700805 *
806 * In some cases we can be sure, that no new locks will be needed
Linus Torvalds1da177e2005-04-16 15:20:36 -0700807 */
Miklos Szeredi39005d02006-06-23 02:05:10 -0700808 if (!(request->fl_flags & FL_ACCESS) &&
809 (request->fl_type != F_UNLCK ||
810 request->fl_start != 0 || request->fl_end != OFFSET_MAX)) {
811 new_fl = locks_alloc_lock();
812 new_fl2 = locks_alloc_lock();
813 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700814
815 lock_kernel();
816 if (request->fl_type != F_UNLCK) {
817 for_each_lock(inode, before) {
818 struct file_lock *fl = *before;
819 if (!IS_POSIX(fl))
820 continue;
821 if (!posix_locks_conflict(request, fl))
822 continue;
Andy Adamson5842add2006-03-26 01:37:26 -0800823 if (conflock)
824 locks_copy_lock(conflock, fl);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700825 error = -EAGAIN;
826 if (!(request->fl_flags & FL_SLEEP))
827 goto out;
828 error = -EDEADLK;
829 if (posix_locks_deadlock(request, fl))
830 goto out;
831 error = -EAGAIN;
832 locks_insert_block(fl, request);
833 goto out;
834 }
835 }
836
837 /* If we're just looking for a conflict, we're done. */
838 error = 0;
839 if (request->fl_flags & FL_ACCESS)
840 goto out;
841
Linus Torvalds1da177e2005-04-16 15:20:36 -0700842 /*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700843 * Find the first old lock with the same owner as the new lock.
844 */
845
846 before = &inode->i_flock;
847
848 /* First skip locks owned by other processes. */
849 while ((fl = *before) && (!IS_POSIX(fl) ||
850 !posix_same_owner(request, fl))) {
851 before = &fl->fl_next;
852 }
853
854 /* Process locks with this owner. */
855 while ((fl = *before) && posix_same_owner(request, fl)) {
856 /* Detect adjacent or overlapping regions (if same lock type)
857 */
858 if (request->fl_type == fl->fl_type) {
Olaf Kirch449231d2005-08-25 16:25:35 -0700859 /* In all comparisons of start vs end, use
860 * "start - 1" rather than "end + 1". If end
861 * is OFFSET_MAX, end + 1 will become negative.
862 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700863 if (fl->fl_end < request->fl_start - 1)
864 goto next_lock;
865 /* If the next lock in the list has entirely bigger
866 * addresses than the new one, insert the lock here.
867 */
Olaf Kirch449231d2005-08-25 16:25:35 -0700868 if (fl->fl_start - 1 > request->fl_end)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700869 break;
870
871 /* If we come here, the new and old lock are of the
872 * same type and adjacent or overlapping. Make one
873 * lock yielding from the lower start address of both
874 * locks to the higher end address.
875 */
876 if (fl->fl_start > request->fl_start)
877 fl->fl_start = request->fl_start;
878 else
879 request->fl_start = fl->fl_start;
880 if (fl->fl_end < request->fl_end)
881 fl->fl_end = request->fl_end;
882 else
883 request->fl_end = fl->fl_end;
884 if (added) {
885 locks_delete_lock(before);
886 continue;
887 }
888 request = fl;
889 added = 1;
890 }
891 else {
892 /* Processing for different lock types is a bit
893 * more complex.
894 */
895 if (fl->fl_end < request->fl_start)
896 goto next_lock;
897 if (fl->fl_start > request->fl_end)
898 break;
899 if (request->fl_type == F_UNLCK)
900 added = 1;
901 if (fl->fl_start < request->fl_start)
902 left = fl;
903 /* If the next lock in the list has a higher end
904 * address than the new one, insert the new one here.
905 */
906 if (fl->fl_end > request->fl_end) {
907 right = fl;
908 break;
909 }
910 if (fl->fl_start >= request->fl_start) {
911 /* The new lock completely replaces an old
912 * one (This may happen several times).
913 */
914 if (added) {
915 locks_delete_lock(before);
916 continue;
917 }
918 /* Replace the old lock with the new one.
919 * Wake up anybody waiting for the old one,
920 * as the change in lock type might satisfy
921 * their needs.
922 */
923 locks_wake_up_blocks(fl);
924 fl->fl_start = request->fl_start;
925 fl->fl_end = request->fl_end;
926 fl->fl_type = request->fl_type;
Trond Myklebust47831f32006-03-20 13:44:05 -0500927 locks_release_private(fl);
928 locks_copy_private(fl, request);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700929 request = fl;
930 added = 1;
931 }
932 }
933 /* Go on to next lock.
934 */
935 next_lock:
936 before = &fl->fl_next;
937 }
938
Miklos Szeredi0d9a4902006-06-23 02:05:09 -0700939 /*
940 * The above code only modifies existing locks in case of
941 * merging or replacing. If new lock(s) need to be inserted
942 * all modifications are done bellow this, so it's safe yet to
943 * bail out.
944 */
945 error = -ENOLCK; /* "no luck" */
946 if (right && left == right && !new_fl2)
947 goto out;
948
Linus Torvalds1da177e2005-04-16 15:20:36 -0700949 error = 0;
950 if (!added) {
951 if (request->fl_type == F_UNLCK)
952 goto out;
Miklos Szeredi0d9a4902006-06-23 02:05:09 -0700953
954 if (!new_fl) {
955 error = -ENOLCK;
956 goto out;
957 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700958 locks_copy_lock(new_fl, request);
959 locks_insert_lock(before, new_fl);
960 new_fl = NULL;
961 }
962 if (right) {
963 if (left == right) {
964 /* The new lock breaks the old one in two pieces,
965 * so we have to use the second new lock.
966 */
967 left = new_fl2;
968 new_fl2 = NULL;
969 locks_copy_lock(left, right);
970 locks_insert_lock(before, left);
971 }
972 right->fl_start = request->fl_end + 1;
973 locks_wake_up_blocks(right);
974 }
975 if (left) {
976 left->fl_end = request->fl_start - 1;
977 locks_wake_up_blocks(left);
978 }
979 out:
980 unlock_kernel();
981 /*
982 * Free any unused locks.
983 */
984 if (new_fl)
985 locks_free_lock(new_fl);
986 if (new_fl2)
987 locks_free_lock(new_fl2);
988 return error;
989}
990
991/**
992 * posix_lock_file - Apply a POSIX-style lock to a file
993 * @filp: The file to apply the lock to
994 * @fl: The lock to be applied
995 *
996 * Add a POSIX style lock to a file.
997 * We merge adjacent & overlapping locks whenever possible.
998 * POSIX locks are sorted by owner task, then by starting address
999 */
1000int posix_lock_file(struct file *filp, struct file_lock *fl)
1001{
Andy Adamson5842add2006-03-26 01:37:26 -08001002 return __posix_lock_file_conf(filp->f_dentry->d_inode, fl, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001003}
Andy Adamson5842add2006-03-26 01:37:26 -08001004EXPORT_SYMBOL(posix_lock_file);
1005
1006/**
1007 * posix_lock_file_conf - Apply a POSIX-style lock to a file
1008 * @filp: The file to apply the lock to
1009 * @fl: The lock to be applied
1010 * @conflock: Place to return a copy of the conflicting lock, if found.
1011 *
1012 * Except for the conflock parameter, acts just like posix_lock_file.
1013 */
1014int posix_lock_file_conf(struct file *filp, struct file_lock *fl,
1015 struct file_lock *conflock)
1016{
1017 return __posix_lock_file_conf(filp->f_dentry->d_inode, fl, conflock);
1018}
1019EXPORT_SYMBOL(posix_lock_file_conf);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001020
1021/**
1022 * posix_lock_file_wait - Apply a POSIX-style lock to a file
1023 * @filp: The file to apply the lock to
1024 * @fl: The lock to be applied
1025 *
1026 * Add a POSIX style lock to a file.
1027 * We merge adjacent & overlapping locks whenever possible.
1028 * POSIX locks are sorted by owner task, then by starting address
1029 */
1030int posix_lock_file_wait(struct file *filp, struct file_lock *fl)
1031{
1032 int error;
1033 might_sleep ();
1034 for (;;) {
Andy Adamson5842add2006-03-26 01:37:26 -08001035 error = posix_lock_file(filp, fl);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001036 if ((error != -EAGAIN) || !(fl->fl_flags & FL_SLEEP))
1037 break;
1038 error = wait_event_interruptible(fl->fl_wait, !fl->fl_next);
1039 if (!error)
1040 continue;
1041
1042 locks_delete_block(fl);
1043 break;
1044 }
1045 return error;
1046}
1047EXPORT_SYMBOL(posix_lock_file_wait);
1048
1049/**
1050 * locks_mandatory_locked - Check for an active lock
1051 * @inode: the file to check
1052 *
1053 * Searches the inode's list of locks to find any POSIX locks which conflict.
1054 * This function is called from locks_verify_locked() only.
1055 */
1056int locks_mandatory_locked(struct inode *inode)
1057{
1058 fl_owner_t owner = current->files;
1059 struct file_lock *fl;
1060
1061 /*
1062 * Search the lock list for this inode for any POSIX locks.
1063 */
1064 lock_kernel();
1065 for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) {
1066 if (!IS_POSIX(fl))
1067 continue;
1068 if (fl->fl_owner != owner)
1069 break;
1070 }
1071 unlock_kernel();
1072 return fl ? -EAGAIN : 0;
1073}
1074
1075/**
1076 * locks_mandatory_area - Check for a conflicting lock
1077 * @read_write: %FLOCK_VERIFY_WRITE for exclusive access, %FLOCK_VERIFY_READ
1078 * for shared
1079 * @inode: the file to check
1080 * @filp: how the file was opened (if it was)
1081 * @offset: start of area to check
1082 * @count: length of area to check
1083 *
1084 * Searches the inode's list of locks to find any POSIX locks which conflict.
1085 * This function is called from rw_verify_area() and
1086 * locks_verify_truncate().
1087 */
1088int locks_mandatory_area(int read_write, struct inode *inode,
1089 struct file *filp, loff_t offset,
1090 size_t count)
1091{
1092 struct file_lock fl;
1093 int error;
1094
1095 locks_init_lock(&fl);
1096 fl.fl_owner = current->files;
1097 fl.fl_pid = current->tgid;
1098 fl.fl_file = filp;
1099 fl.fl_flags = FL_POSIX | FL_ACCESS;
1100 if (filp && !(filp->f_flags & O_NONBLOCK))
1101 fl.fl_flags |= FL_SLEEP;
1102 fl.fl_type = (read_write == FLOCK_VERIFY_WRITE) ? F_WRLCK : F_RDLCK;
1103 fl.fl_start = offset;
1104 fl.fl_end = offset + count - 1;
1105
1106 for (;;) {
Andy Adamson5842add2006-03-26 01:37:26 -08001107 error = __posix_lock_file_conf(inode, &fl, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001108 if (error != -EAGAIN)
1109 break;
1110 if (!(fl.fl_flags & FL_SLEEP))
1111 break;
1112 error = wait_event_interruptible(fl.fl_wait, !fl.fl_next);
1113 if (!error) {
1114 /*
1115 * If we've been sleeping someone might have
1116 * changed the permissions behind our back.
1117 */
1118 if ((inode->i_mode & (S_ISGID | S_IXGRP)) == S_ISGID)
1119 continue;
1120 }
1121
1122 locks_delete_block(&fl);
1123 break;
1124 }
1125
1126 return error;
1127}
1128
1129EXPORT_SYMBOL(locks_mandatory_area);
1130
1131/* We already had a lease on this file; just change its type */
1132int lease_modify(struct file_lock **before, int arg)
1133{
1134 struct file_lock *fl = *before;
1135 int error = assign_type(fl, arg);
1136
1137 if (error)
1138 return error;
1139 locks_wake_up_blocks(fl);
1140 if (arg == F_UNLCK)
1141 locks_delete_lock(before);
1142 return 0;
1143}
1144
1145EXPORT_SYMBOL(lease_modify);
1146
1147static void time_out_leases(struct inode *inode)
1148{
1149 struct file_lock **before;
1150 struct file_lock *fl;
1151
1152 before = &inode->i_flock;
1153 while ((fl = *before) && IS_LEASE(fl) && (fl->fl_type & F_INPROGRESS)) {
1154 if ((fl->fl_break_time == 0)
1155 || time_before(jiffies, fl->fl_break_time)) {
1156 before = &fl->fl_next;
1157 continue;
1158 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001159 lease_modify(before, fl->fl_type & ~F_INPROGRESS);
1160 if (fl == *before) /* lease_modify may have freed fl */
1161 before = &fl->fl_next;
1162 }
1163}
1164
1165/**
1166 * __break_lease - revoke all outstanding leases on file
1167 * @inode: the inode of the file to return
1168 * @mode: the open mode (read or write)
1169 *
1170 * break_lease (inlined for speed) has checked there already
1171 * is a lease on this file. Leases are broken on a call to open()
1172 * or truncate(). This function can sleep unless you
1173 * specified %O_NONBLOCK to your open().
1174 */
1175int __break_lease(struct inode *inode, unsigned int mode)
1176{
1177 int error = 0, future;
1178 struct file_lock *new_fl, *flock;
1179 struct file_lock *fl;
1180 int alloc_err;
1181 unsigned long break_time;
1182 int i_have_this_lease = 0;
1183
1184 alloc_err = lease_alloc(NULL, mode & FMODE_WRITE ? F_WRLCK : F_RDLCK,
1185 &new_fl);
1186
1187 lock_kernel();
1188
1189 time_out_leases(inode);
1190
1191 flock = inode->i_flock;
1192 if ((flock == NULL) || !IS_LEASE(flock))
1193 goto out;
1194
1195 for (fl = flock; fl && IS_LEASE(fl); fl = fl->fl_next)
1196 if (fl->fl_owner == current->files)
1197 i_have_this_lease = 1;
1198
1199 if (mode & FMODE_WRITE) {
1200 /* If we want write access, we have to revoke any lease. */
1201 future = F_UNLCK | F_INPROGRESS;
1202 } else if (flock->fl_type & F_INPROGRESS) {
1203 /* If the lease is already being broken, we just leave it */
1204 future = flock->fl_type;
1205 } else if (flock->fl_type & F_WRLCK) {
1206 /* Downgrade the exclusive lease to a read-only lease. */
1207 future = F_RDLCK | F_INPROGRESS;
1208 } else {
1209 /* the existing lease was read-only, so we can read too. */
1210 goto out;
1211 }
1212
1213 if (alloc_err && !i_have_this_lease && ((mode & O_NONBLOCK) == 0)) {
1214 error = alloc_err;
1215 goto out;
1216 }
1217
1218 break_time = 0;
1219 if (lease_break_time > 0) {
1220 break_time = jiffies + lease_break_time * HZ;
1221 if (break_time == 0)
1222 break_time++; /* so that 0 means no break time */
1223 }
1224
1225 for (fl = flock; fl && IS_LEASE(fl); fl = fl->fl_next) {
1226 if (fl->fl_type != future) {
1227 fl->fl_type = future;
1228 fl->fl_break_time = break_time;
1229 /* lease must have lmops break callback */
1230 fl->fl_lmops->fl_break(fl);
1231 }
1232 }
1233
1234 if (i_have_this_lease || (mode & O_NONBLOCK)) {
1235 error = -EWOULDBLOCK;
1236 goto out;
1237 }
1238
1239restart:
1240 break_time = flock->fl_break_time;
1241 if (break_time != 0) {
1242 break_time -= jiffies;
1243 if (break_time == 0)
1244 break_time++;
1245 }
1246 error = locks_block_on_timeout(flock, new_fl, break_time);
1247 if (error >= 0) {
1248 if (error == 0)
1249 time_out_leases(inode);
1250 /* Wait for the next lease that has not been broken yet */
1251 for (flock = inode->i_flock; flock && IS_LEASE(flock);
1252 flock = flock->fl_next) {
1253 if (flock->fl_type & F_INPROGRESS)
1254 goto restart;
1255 }
1256 error = 0;
1257 }
1258
1259out:
1260 unlock_kernel();
1261 if (!alloc_err)
1262 locks_free_lock(new_fl);
1263 return error;
1264}
1265
1266EXPORT_SYMBOL(__break_lease);
1267
1268/**
1269 * lease_get_mtime
1270 * @inode: the inode
1271 * @time: pointer to a timespec which will contain the last modified time
1272 *
1273 * This is to force NFS clients to flush their caches for files with
1274 * exclusive leases. The justification is that if someone has an
1275 * exclusive lease, then they could be modifiying it.
1276 */
1277void lease_get_mtime(struct inode *inode, struct timespec *time)
1278{
1279 struct file_lock *flock = inode->i_flock;
1280 if (flock && IS_LEASE(flock) && (flock->fl_type & F_WRLCK))
1281 *time = current_fs_time(inode->i_sb);
1282 else
1283 *time = inode->i_mtime;
1284}
1285
1286EXPORT_SYMBOL(lease_get_mtime);
1287
1288/**
1289 * fcntl_getlease - Enquire what lease is currently active
1290 * @filp: the file
1291 *
1292 * The value returned by this function will be one of
1293 * (if no lease break is pending):
1294 *
1295 * %F_RDLCK to indicate a shared lease is held.
1296 *
1297 * %F_WRLCK to indicate an exclusive lease is held.
1298 *
1299 * %F_UNLCK to indicate no lease is held.
1300 *
1301 * (if a lease break is pending):
1302 *
1303 * %F_RDLCK to indicate an exclusive lease needs to be
1304 * changed to a shared lease (or removed).
1305 *
1306 * %F_UNLCK to indicate the lease needs to be removed.
1307 *
1308 * XXX: sfr & willy disagree over whether F_INPROGRESS
1309 * should be returned to userspace.
1310 */
1311int fcntl_getlease(struct file *filp)
1312{
1313 struct file_lock *fl;
1314 int type = F_UNLCK;
1315
1316 lock_kernel();
1317 time_out_leases(filp->f_dentry->d_inode);
1318 for (fl = filp->f_dentry->d_inode->i_flock; fl && IS_LEASE(fl);
1319 fl = fl->fl_next) {
1320 if (fl->fl_file == filp) {
1321 type = fl->fl_type & ~F_INPROGRESS;
1322 break;
1323 }
1324 }
1325 unlock_kernel();
1326 return type;
1327}
1328
1329/**
1330 * __setlease - sets a lease on an open file
1331 * @filp: file pointer
1332 * @arg: type of lease to obtain
1333 * @flp: input - file_lock to use, output - file_lock inserted
1334 *
1335 * The (input) flp->fl_lmops->fl_break function is required
1336 * by break_lease().
1337 *
1338 * Called with kernel lock held.
1339 */
Adrian Bunk75c96f82005-05-05 16:16:09 -07001340static int __setlease(struct file *filp, long arg, struct file_lock **flp)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001341{
KAMBAROV, ZAUR7eaae282005-07-07 17:57:06 -07001342 struct file_lock *fl, **before, **my_before = NULL, *lease;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001343 struct dentry *dentry = filp->f_dentry;
1344 struct inode *inode = dentry->d_inode;
1345 int error, rdlease_count = 0, wrlease_count = 0;
1346
1347 time_out_leases(inode);
1348
1349 error = -EINVAL;
1350 if (!flp || !(*flp) || !(*flp)->fl_lmops || !(*flp)->fl_lmops->fl_break)
1351 goto out;
1352
KAMBAROV, ZAUR7eaae282005-07-07 17:57:06 -07001353 lease = *flp;
1354
Linus Torvalds1da177e2005-04-16 15:20:36 -07001355 error = -EAGAIN;
1356 if ((arg == F_RDLCK) && (atomic_read(&inode->i_writecount) > 0))
1357 goto out;
1358 if ((arg == F_WRLCK)
1359 && ((atomic_read(&dentry->d_count) > 1)
1360 || (atomic_read(&inode->i_count) > 1)))
1361 goto out;
1362
1363 /*
1364 * At this point, we know that if there is an exclusive
1365 * lease on this file, then we hold it on this filp
1366 * (otherwise our open of this file would have blocked).
1367 * And if we are trying to acquire an exclusive lease,
1368 * then the file is not open by anyone (including us)
1369 * except for this filp.
1370 */
1371 for (before = &inode->i_flock;
1372 ((fl = *before) != NULL) && IS_LEASE(fl);
1373 before = &fl->fl_next) {
1374 if (lease->fl_lmops->fl_mylease(fl, lease))
1375 my_before = before;
1376 else if (fl->fl_type == (F_INPROGRESS | F_UNLCK))
1377 /*
1378 * Someone is in the process of opening this
1379 * file for writing so we may not take an
1380 * exclusive lease on it.
1381 */
1382 wrlease_count++;
1383 else
1384 rdlease_count++;
1385 }
1386
1387 if ((arg == F_RDLCK && (wrlease_count > 0)) ||
1388 (arg == F_WRLCK && ((rdlease_count + wrlease_count) > 0)))
1389 goto out;
1390
1391 if (my_before != NULL) {
Trond Myklebust75dff552006-05-07 23:02:42 -04001392 *flp = *my_before;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001393 error = lease->fl_lmops->fl_change(my_before, arg);
1394 goto out;
1395 }
1396
1397 error = 0;
1398 if (arg == F_UNLCK)
1399 goto out;
1400
1401 error = -EINVAL;
1402 if (!leases_enable)
1403 goto out;
1404
1405 error = lease_alloc(filp, arg, &fl);
1406 if (error)
1407 goto out;
1408
1409 locks_copy_lock(fl, lease);
1410
1411 locks_insert_lock(before, fl);
1412
1413 *flp = fl;
1414out:
1415 return error;
1416}
1417
1418 /**
1419 * setlease - sets a lease on an open file
1420 * @filp: file pointer
1421 * @arg: type of lease to obtain
1422 * @lease: file_lock to use
1423 *
1424 * Call this to establish a lease on the file.
1425 * The fl_lmops fl_break function is required by break_lease
1426 */
1427
1428int setlease(struct file *filp, long arg, struct file_lock **lease)
1429{
1430 struct dentry *dentry = filp->f_dentry;
1431 struct inode *inode = dentry->d_inode;
1432 int error;
1433
1434 if ((current->fsuid != inode->i_uid) && !capable(CAP_LEASE))
1435 return -EACCES;
1436 if (!S_ISREG(inode->i_mode))
1437 return -EINVAL;
1438 error = security_file_lock(filp, arg);
1439 if (error)
1440 return error;
1441
1442 lock_kernel();
1443 error = __setlease(filp, arg, lease);
1444 unlock_kernel();
1445
1446 return error;
1447}
1448
1449EXPORT_SYMBOL(setlease);
1450
1451/**
1452 * fcntl_setlease - sets a lease on an open file
1453 * @fd: open file descriptor
1454 * @filp: file pointer
1455 * @arg: type of lease to obtain
1456 *
1457 * Call this fcntl to establish a lease on the file.
1458 * Note that you also need to call %F_SETSIG to
1459 * receive a signal when the lease is broken.
1460 */
1461int fcntl_setlease(unsigned int fd, struct file *filp, long arg)
1462{
1463 struct file_lock fl, *flp = &fl;
1464 struct dentry *dentry = filp->f_dentry;
1465 struct inode *inode = dentry->d_inode;
1466 int error;
1467
1468 if ((current->fsuid != inode->i_uid) && !capable(CAP_LEASE))
1469 return -EACCES;
1470 if (!S_ISREG(inode->i_mode))
1471 return -EINVAL;
1472 error = security_file_lock(filp, arg);
1473 if (error)
1474 return error;
1475
1476 locks_init_lock(&fl);
1477 error = lease_init(filp, arg, &fl);
1478 if (error)
1479 return error;
1480
1481 lock_kernel();
1482
1483 error = __setlease(filp, arg, &flp);
J. Bruce Fieldsdc15ae12005-11-10 19:08:00 -05001484 if (error || arg == F_UNLCK)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001485 goto out_unlock;
1486
1487 error = fasync_helper(fd, filp, 1, &flp->fl_fasync);
1488 if (error < 0) {
1489 /* remove lease just inserted by __setlease */
1490 flp->fl_type = F_UNLCK | F_INPROGRESS;
1491 flp->fl_break_time = jiffies- 10;
1492 time_out_leases(inode);
1493 goto out_unlock;
1494 }
1495
1496 error = f_setown(filp, current->pid, 0);
1497out_unlock:
1498 unlock_kernel();
1499 return error;
1500}
1501
1502/**
1503 * flock_lock_file_wait - Apply a FLOCK-style lock to a file
1504 * @filp: The file to apply the lock to
1505 * @fl: The lock to be applied
1506 *
1507 * Add a FLOCK style lock to a file.
1508 */
1509int flock_lock_file_wait(struct file *filp, struct file_lock *fl)
1510{
1511 int error;
1512 might_sleep();
1513 for (;;) {
1514 error = flock_lock_file(filp, fl);
1515 if ((error != -EAGAIN) || !(fl->fl_flags & FL_SLEEP))
1516 break;
1517 error = wait_event_interruptible(fl->fl_wait, !fl->fl_next);
1518 if (!error)
1519 continue;
1520
1521 locks_delete_block(fl);
1522 break;
1523 }
1524 return error;
1525}
1526
1527EXPORT_SYMBOL(flock_lock_file_wait);
1528
1529/**
1530 * sys_flock: - flock() system call.
1531 * @fd: the file descriptor to lock.
1532 * @cmd: the type of lock to apply.
1533 *
1534 * Apply a %FL_FLOCK style lock to an open file descriptor.
1535 * The @cmd can be one of
1536 *
1537 * %LOCK_SH -- a shared lock.
1538 *
1539 * %LOCK_EX -- an exclusive lock.
1540 *
1541 * %LOCK_UN -- remove an existing lock.
1542 *
1543 * %LOCK_MAND -- a `mandatory' flock. This exists to emulate Windows Share Modes.
1544 *
1545 * %LOCK_MAND can be combined with %LOCK_READ or %LOCK_WRITE to allow other
1546 * processes read and write access respectively.
1547 */
1548asmlinkage long sys_flock(unsigned int fd, unsigned int cmd)
1549{
1550 struct file *filp;
1551 struct file_lock *lock;
1552 int can_sleep, unlock;
1553 int error;
1554
1555 error = -EBADF;
1556 filp = fget(fd);
1557 if (!filp)
1558 goto out;
1559
1560 can_sleep = !(cmd & LOCK_NB);
1561 cmd &= ~LOCK_NB;
1562 unlock = (cmd == LOCK_UN);
1563
1564 if (!unlock && !(cmd & LOCK_MAND) && !(filp->f_mode & 3))
1565 goto out_putf;
1566
1567 error = flock_make_lock(filp, &lock, cmd);
1568 if (error)
1569 goto out_putf;
1570 if (can_sleep)
1571 lock->fl_flags |= FL_SLEEP;
1572
1573 error = security_file_lock(filp, cmd);
1574 if (error)
1575 goto out_free;
1576
1577 if (filp->f_op && filp->f_op->flock)
1578 error = filp->f_op->flock(filp,
1579 (can_sleep) ? F_SETLKW : F_SETLK,
1580 lock);
1581 else
1582 error = flock_lock_file_wait(filp, lock);
1583
1584 out_free:
Trond Myklebust993dfa82006-03-31 02:30:55 -08001585 locks_free_lock(lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001586
1587 out_putf:
1588 fput(filp);
1589 out:
1590 return error;
1591}
1592
1593/* Report the first existing lock that would conflict with l.
1594 * This implements the F_GETLK command of fcntl().
1595 */
1596int fcntl_getlk(struct file *filp, struct flock __user *l)
1597{
Andy Adamson8dc7c312006-03-20 13:44:26 -05001598 struct file_lock *fl, cfl, file_lock;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001599 struct flock flock;
1600 int error;
1601
1602 error = -EFAULT;
1603 if (copy_from_user(&flock, l, sizeof(flock)))
1604 goto out;
1605 error = -EINVAL;
1606 if ((flock.l_type != F_RDLCK) && (flock.l_type != F_WRLCK))
1607 goto out;
1608
1609 error = flock_to_posix_lock(filp, &file_lock, &flock);
1610 if (error)
1611 goto out;
1612
1613 if (filp->f_op && filp->f_op->lock) {
1614 error = filp->f_op->lock(filp, F_GETLK, &file_lock);
Trond Myklebust80fec4c2005-06-22 17:16:31 +00001615 if (file_lock.fl_ops && file_lock.fl_ops->fl_release_private)
1616 file_lock.fl_ops->fl_release_private(&file_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001617 if (error < 0)
1618 goto out;
1619 else
1620 fl = (file_lock.fl_type == F_UNLCK ? NULL : &file_lock);
1621 } else {
Andy Adamson8dc7c312006-03-20 13:44:26 -05001622 fl = (posix_test_lock(filp, &file_lock, &cfl) ? &cfl : NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001623 }
1624
1625 flock.l_type = F_UNLCK;
1626 if (fl != NULL) {
1627 flock.l_pid = fl->fl_pid;
1628#if BITS_PER_LONG == 32
1629 /*
1630 * Make sure we can represent the posix lock via
1631 * legacy 32bit flock.
1632 */
1633 error = -EOVERFLOW;
1634 if (fl->fl_start > OFFT_OFFSET_MAX)
1635 goto out;
1636 if ((fl->fl_end != OFFSET_MAX)
1637 && (fl->fl_end > OFFT_OFFSET_MAX))
1638 goto out;
1639#endif
1640 flock.l_start = fl->fl_start;
1641 flock.l_len = fl->fl_end == OFFSET_MAX ? 0 :
1642 fl->fl_end - fl->fl_start + 1;
1643 flock.l_whence = 0;
1644 flock.l_type = fl->fl_type;
1645 }
1646 error = -EFAULT;
1647 if (!copy_to_user(l, &flock, sizeof(flock)))
1648 error = 0;
1649out:
1650 return error;
1651}
1652
1653/* Apply the lock described by l to an open file descriptor.
1654 * This implements both the F_SETLK and F_SETLKW commands of fcntl().
1655 */
Peter Staubachc2936212005-07-27 11:45:09 -07001656int fcntl_setlk(unsigned int fd, struct file *filp, unsigned int cmd,
1657 struct flock __user *l)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001658{
1659 struct file_lock *file_lock = locks_alloc_lock();
1660 struct flock flock;
1661 struct inode *inode;
1662 int error;
1663
1664 if (file_lock == NULL)
1665 return -ENOLCK;
1666
1667 /*
1668 * This might block, so we do it before checking the inode.
1669 */
1670 error = -EFAULT;
1671 if (copy_from_user(&flock, l, sizeof(flock)))
1672 goto out;
1673
1674 inode = filp->f_dentry->d_inode;
1675
1676 /* Don't allow mandatory locks on files that may be memory mapped
1677 * and shared.
1678 */
1679 if (IS_MANDLOCK(inode) &&
1680 (inode->i_mode & (S_ISGID | S_IXGRP)) == S_ISGID &&
1681 mapping_writably_mapped(filp->f_mapping)) {
1682 error = -EAGAIN;
1683 goto out;
1684 }
1685
Peter Staubachc2936212005-07-27 11:45:09 -07001686again:
Linus Torvalds1da177e2005-04-16 15:20:36 -07001687 error = flock_to_posix_lock(filp, file_lock, &flock);
1688 if (error)
1689 goto out;
1690 if (cmd == F_SETLKW) {
1691 file_lock->fl_flags |= FL_SLEEP;
1692 }
1693
1694 error = -EBADF;
1695 switch (flock.l_type) {
1696 case F_RDLCK:
1697 if (!(filp->f_mode & FMODE_READ))
1698 goto out;
1699 break;
1700 case F_WRLCK:
1701 if (!(filp->f_mode & FMODE_WRITE))
1702 goto out;
1703 break;
1704 case F_UNLCK:
1705 break;
1706 default:
1707 error = -EINVAL;
1708 goto out;
1709 }
1710
1711 error = security_file_lock(filp, file_lock->fl_type);
1712 if (error)
1713 goto out;
1714
Peter Staubachc2936212005-07-27 11:45:09 -07001715 if (filp->f_op && filp->f_op->lock != NULL)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001716 error = filp->f_op->lock(filp, cmd, file_lock);
Peter Staubachc2936212005-07-27 11:45:09 -07001717 else {
1718 for (;;) {
Andy Adamson5842add2006-03-26 01:37:26 -08001719 error = posix_lock_file(filp, file_lock);
Peter Staubachc2936212005-07-27 11:45:09 -07001720 if ((error != -EAGAIN) || (cmd == F_SETLK))
1721 break;
1722 error = wait_event_interruptible(file_lock->fl_wait,
1723 !file_lock->fl_next);
1724 if (!error)
1725 continue;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001726
Peter Staubachc2936212005-07-27 11:45:09 -07001727 locks_delete_block(file_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001728 break;
Peter Staubachc2936212005-07-27 11:45:09 -07001729 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001730 }
1731
Peter Staubachc2936212005-07-27 11:45:09 -07001732 /*
1733 * Attempt to detect a close/fcntl race and recover by
1734 * releasing the lock that was just acquired.
1735 */
1736 if (!error && fcheck(fd) != filp && flock.l_type != F_UNLCK) {
1737 flock.l_type = F_UNLCK;
1738 goto again;
1739 }
1740
1741out:
Linus Torvalds1da177e2005-04-16 15:20:36 -07001742 locks_free_lock(file_lock);
1743 return error;
1744}
1745
1746#if BITS_PER_LONG == 32
1747/* Report the first existing lock that would conflict with l.
1748 * This implements the F_GETLK command of fcntl().
1749 */
1750int fcntl_getlk64(struct file *filp, struct flock64 __user *l)
1751{
Andy Adamson8dc7c312006-03-20 13:44:26 -05001752 struct file_lock *fl, cfl, file_lock;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001753 struct flock64 flock;
1754 int error;
1755
1756 error = -EFAULT;
1757 if (copy_from_user(&flock, l, sizeof(flock)))
1758 goto out;
1759 error = -EINVAL;
1760 if ((flock.l_type != F_RDLCK) && (flock.l_type != F_WRLCK))
1761 goto out;
1762
1763 error = flock64_to_posix_lock(filp, &file_lock, &flock);
1764 if (error)
1765 goto out;
1766
1767 if (filp->f_op && filp->f_op->lock) {
1768 error = filp->f_op->lock(filp, F_GETLK, &file_lock);
Trond Myklebust80fec4c2005-06-22 17:16:31 +00001769 if (file_lock.fl_ops && file_lock.fl_ops->fl_release_private)
1770 file_lock.fl_ops->fl_release_private(&file_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001771 if (error < 0)
1772 goto out;
1773 else
1774 fl = (file_lock.fl_type == F_UNLCK ? NULL : &file_lock);
1775 } else {
Andy Adamson8dc7c312006-03-20 13:44:26 -05001776 fl = (posix_test_lock(filp, &file_lock, &cfl) ? &cfl : NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001777 }
1778
1779 flock.l_type = F_UNLCK;
1780 if (fl != NULL) {
1781 flock.l_pid = fl->fl_pid;
1782 flock.l_start = fl->fl_start;
1783 flock.l_len = fl->fl_end == OFFSET_MAX ? 0 :
1784 fl->fl_end - fl->fl_start + 1;
1785 flock.l_whence = 0;
1786 flock.l_type = fl->fl_type;
1787 }
1788 error = -EFAULT;
1789 if (!copy_to_user(l, &flock, sizeof(flock)))
1790 error = 0;
1791
1792out:
1793 return error;
1794}
1795
1796/* Apply the lock described by l to an open file descriptor.
1797 * This implements both the F_SETLK and F_SETLKW commands of fcntl().
1798 */
Peter Staubachc2936212005-07-27 11:45:09 -07001799int fcntl_setlk64(unsigned int fd, struct file *filp, unsigned int cmd,
1800 struct flock64 __user *l)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001801{
1802 struct file_lock *file_lock = locks_alloc_lock();
1803 struct flock64 flock;
1804 struct inode *inode;
1805 int error;
1806
1807 if (file_lock == NULL)
1808 return -ENOLCK;
1809
1810 /*
1811 * This might block, so we do it before checking the inode.
1812 */
1813 error = -EFAULT;
1814 if (copy_from_user(&flock, l, sizeof(flock)))
1815 goto out;
1816
1817 inode = filp->f_dentry->d_inode;
1818
1819 /* Don't allow mandatory locks on files that may be memory mapped
1820 * and shared.
1821 */
1822 if (IS_MANDLOCK(inode) &&
1823 (inode->i_mode & (S_ISGID | S_IXGRP)) == S_ISGID &&
1824 mapping_writably_mapped(filp->f_mapping)) {
1825 error = -EAGAIN;
1826 goto out;
1827 }
1828
Peter Staubachc2936212005-07-27 11:45:09 -07001829again:
Linus Torvalds1da177e2005-04-16 15:20:36 -07001830 error = flock64_to_posix_lock(filp, file_lock, &flock);
1831 if (error)
1832 goto out;
1833 if (cmd == F_SETLKW64) {
1834 file_lock->fl_flags |= FL_SLEEP;
1835 }
1836
1837 error = -EBADF;
1838 switch (flock.l_type) {
1839 case F_RDLCK:
1840 if (!(filp->f_mode & FMODE_READ))
1841 goto out;
1842 break;
1843 case F_WRLCK:
1844 if (!(filp->f_mode & FMODE_WRITE))
1845 goto out;
1846 break;
1847 case F_UNLCK:
1848 break;
1849 default:
1850 error = -EINVAL;
1851 goto out;
1852 }
1853
1854 error = security_file_lock(filp, file_lock->fl_type);
1855 if (error)
1856 goto out;
1857
Peter Staubachc2936212005-07-27 11:45:09 -07001858 if (filp->f_op && filp->f_op->lock != NULL)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001859 error = filp->f_op->lock(filp, cmd, file_lock);
Peter Staubachc2936212005-07-27 11:45:09 -07001860 else {
1861 for (;;) {
Andy Adamson5842add2006-03-26 01:37:26 -08001862 error = posix_lock_file(filp, file_lock);
Peter Staubachc2936212005-07-27 11:45:09 -07001863 if ((error != -EAGAIN) || (cmd == F_SETLK64))
1864 break;
1865 error = wait_event_interruptible(file_lock->fl_wait,
1866 !file_lock->fl_next);
1867 if (!error)
1868 continue;
1869
1870 locks_delete_block(file_lock);
1871 break;
1872 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001873 }
1874
Peter Staubachc2936212005-07-27 11:45:09 -07001875 /*
1876 * Attempt to detect a close/fcntl race and recover by
1877 * releasing the lock that was just acquired.
1878 */
1879 if (!error && fcheck(fd) != filp && flock.l_type != F_UNLCK) {
1880 flock.l_type = F_UNLCK;
1881 goto again;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001882 }
1883
1884out:
1885 locks_free_lock(file_lock);
1886 return error;
1887}
1888#endif /* BITS_PER_LONG == 32 */
1889
1890/*
1891 * This function is called when the file is being removed
1892 * from the task's fd array. POSIX locks belonging to this task
1893 * are deleted at this time.
1894 */
1895void locks_remove_posix(struct file *filp, fl_owner_t owner)
1896{
Miklos Szerediff7b86b2006-06-23 02:05:11 -07001897 struct file_lock lock;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001898
1899 /*
1900 * If there are no locks held on this file, we don't need to call
1901 * posix_lock_file(). Another process could be setting a lock on this
1902 * file at the same time, but we wouldn't remove that lock anyway.
1903 */
Miklos Szerediff7b86b2006-06-23 02:05:11 -07001904 if (!filp->f_dentry->d_inode->i_flock)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001905 return;
1906
1907 lock.fl_type = F_UNLCK;
Miklos Szeredi75e1fcc2006-06-23 02:05:12 -07001908 lock.fl_flags = FL_POSIX | FL_CLOSE;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001909 lock.fl_start = 0;
1910 lock.fl_end = OFFSET_MAX;
1911 lock.fl_owner = owner;
1912 lock.fl_pid = current->tgid;
1913 lock.fl_file = filp;
1914 lock.fl_ops = NULL;
1915 lock.fl_lmops = NULL;
1916
Miklos Szerediff7b86b2006-06-23 02:05:11 -07001917 if (filp->f_op && filp->f_op->lock != NULL)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001918 filp->f_op->lock(filp, F_SETLK, &lock);
Miklos Szerediff7b86b2006-06-23 02:05:11 -07001919 else
1920 posix_lock_file(filp, &lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001921
Linus Torvalds1da177e2005-04-16 15:20:36 -07001922 if (lock.fl_ops && lock.fl_ops->fl_release_private)
1923 lock.fl_ops->fl_release_private(&lock);
1924}
1925
1926EXPORT_SYMBOL(locks_remove_posix);
1927
1928/*
1929 * This function is called on the last close of an open file.
1930 */
1931void locks_remove_flock(struct file *filp)
1932{
1933 struct inode * inode = filp->f_dentry->d_inode;
1934 struct file_lock *fl;
1935 struct file_lock **before;
1936
1937 if (!inode->i_flock)
1938 return;
1939
1940 if (filp->f_op && filp->f_op->flock) {
1941 struct file_lock fl = {
1942 .fl_pid = current->tgid,
1943 .fl_file = filp,
1944 .fl_flags = FL_FLOCK,
1945 .fl_type = F_UNLCK,
1946 .fl_end = OFFSET_MAX,
1947 };
1948 filp->f_op->flock(filp, F_SETLKW, &fl);
Trond Myklebust80fec4c2005-06-22 17:16:31 +00001949 if (fl.fl_ops && fl.fl_ops->fl_release_private)
1950 fl.fl_ops->fl_release_private(&fl);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001951 }
1952
1953 lock_kernel();
1954 before = &inode->i_flock;
1955
1956 while ((fl = *before) != NULL) {
1957 if (fl->fl_file == filp) {
Peter Staubachc2936212005-07-27 11:45:09 -07001958 if (IS_FLOCK(fl)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001959 locks_delete_lock(before);
1960 continue;
1961 }
1962 if (IS_LEASE(fl)) {
1963 lease_modify(before, F_UNLCK);
1964 continue;
1965 }
1966 /* What? */
1967 BUG();
1968 }
1969 before = &fl->fl_next;
1970 }
1971 unlock_kernel();
1972}
1973
1974/**
Linus Torvalds1da177e2005-04-16 15:20:36 -07001975 * posix_unblock_lock - stop waiting for a file lock
1976 * @filp: how the file was opened
1977 * @waiter: the lock which was waiting
1978 *
1979 * lockd needs to block waiting for locks.
1980 */
J. Bruce Fields64a318e2006-01-03 09:55:46 +01001981int
Linus Torvalds1da177e2005-04-16 15:20:36 -07001982posix_unblock_lock(struct file *filp, struct file_lock *waiter)
1983{
J. Bruce Fields64a318e2006-01-03 09:55:46 +01001984 int status = 0;
1985
Linus Torvalds1da177e2005-04-16 15:20:36 -07001986 lock_kernel();
J. Bruce Fields5996a292006-01-03 09:55:44 +01001987 if (waiter->fl_next)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001988 __locks_delete_block(waiter);
J. Bruce Fields64a318e2006-01-03 09:55:46 +01001989 else
1990 status = -ENOENT;
J. Bruce Fields5996a292006-01-03 09:55:44 +01001991 unlock_kernel();
J. Bruce Fields64a318e2006-01-03 09:55:46 +01001992 return status;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001993}
1994
1995EXPORT_SYMBOL(posix_unblock_lock);
1996
1997static void lock_get_status(char* out, struct file_lock *fl, int id, char *pfx)
1998{
1999 struct inode *inode = NULL;
2000
2001 if (fl->fl_file != NULL)
2002 inode = fl->fl_file->f_dentry->d_inode;
2003
2004 out += sprintf(out, "%d:%s ", id, pfx);
2005 if (IS_POSIX(fl)) {
2006 out += sprintf(out, "%6s %s ",
2007 (fl->fl_flags & FL_ACCESS) ? "ACCESS" : "POSIX ",
2008 (inode == NULL) ? "*NOINODE*" :
2009 (IS_MANDLOCK(inode) &&
2010 (inode->i_mode & (S_IXGRP | S_ISGID)) == S_ISGID) ?
2011 "MANDATORY" : "ADVISORY ");
2012 } else if (IS_FLOCK(fl)) {
2013 if (fl->fl_type & LOCK_MAND) {
2014 out += sprintf(out, "FLOCK MSNFS ");
2015 } else {
2016 out += sprintf(out, "FLOCK ADVISORY ");
2017 }
2018 } else if (IS_LEASE(fl)) {
2019 out += sprintf(out, "LEASE ");
2020 if (fl->fl_type & F_INPROGRESS)
2021 out += sprintf(out, "BREAKING ");
2022 else if (fl->fl_file)
2023 out += sprintf(out, "ACTIVE ");
2024 else
2025 out += sprintf(out, "BREAKER ");
2026 } else {
2027 out += sprintf(out, "UNKNOWN UNKNOWN ");
2028 }
2029 if (fl->fl_type & LOCK_MAND) {
2030 out += sprintf(out, "%s ",
2031 (fl->fl_type & LOCK_READ)
2032 ? (fl->fl_type & LOCK_WRITE) ? "RW " : "READ "
2033 : (fl->fl_type & LOCK_WRITE) ? "WRITE" : "NONE ");
2034 } else {
2035 out += sprintf(out, "%s ",
2036 (fl->fl_type & F_INPROGRESS)
2037 ? (fl->fl_type & F_UNLCK) ? "UNLCK" : "READ "
2038 : (fl->fl_type & F_WRLCK) ? "WRITE" : "READ ");
2039 }
2040 if (inode) {
2041#ifdef WE_CAN_BREAK_LSLK_NOW
2042 out += sprintf(out, "%d %s:%ld ", fl->fl_pid,
2043 inode->i_sb->s_id, inode->i_ino);
2044#else
2045 /* userspace relies on this representation of dev_t ;-( */
2046 out += sprintf(out, "%d %02x:%02x:%ld ", fl->fl_pid,
2047 MAJOR(inode->i_sb->s_dev),
2048 MINOR(inode->i_sb->s_dev), inode->i_ino);
2049#endif
2050 } else {
2051 out += sprintf(out, "%d <none>:0 ", fl->fl_pid);
2052 }
2053 if (IS_POSIX(fl)) {
2054 if (fl->fl_end == OFFSET_MAX)
2055 out += sprintf(out, "%Ld EOF\n", fl->fl_start);
2056 else
2057 out += sprintf(out, "%Ld %Ld\n", fl->fl_start,
2058 fl->fl_end);
2059 } else {
2060 out += sprintf(out, "0 EOF\n");
2061 }
2062}
2063
2064static void move_lock_status(char **p, off_t* pos, off_t offset)
2065{
2066 int len;
2067 len = strlen(*p);
2068 if(*pos >= offset) {
2069 /* the complete line is valid */
2070 *p += len;
2071 *pos += len;
2072 return;
2073 }
2074 if(*pos+len > offset) {
2075 /* use the second part of the line */
2076 int i = offset-*pos;
2077 memmove(*p,*p+i,len-i);
2078 *p += len-i;
2079 *pos += len;
2080 return;
2081 }
2082 /* discard the complete line */
2083 *pos += len;
2084}
2085
2086/**
2087 * get_locks_status - reports lock usage in /proc/locks
2088 * @buffer: address in userspace to write into
2089 * @start: ?
2090 * @offset: how far we are through the buffer
2091 * @length: how much to read
2092 */
2093
2094int get_locks_status(char *buffer, char **start, off_t offset, int length)
2095{
2096 struct list_head *tmp;
2097 char *q = buffer;
2098 off_t pos = 0;
2099 int i = 0;
2100
2101 lock_kernel();
2102 list_for_each(tmp, &file_lock_list) {
2103 struct list_head *btmp;
2104 struct file_lock *fl = list_entry(tmp, struct file_lock, fl_link);
2105 lock_get_status(q, fl, ++i, "");
2106 move_lock_status(&q, &pos, offset);
2107
2108 if(pos >= offset+length)
2109 goto done;
2110
2111 list_for_each(btmp, &fl->fl_block) {
2112 struct file_lock *bfl = list_entry(btmp,
2113 struct file_lock, fl_block);
2114 lock_get_status(q, bfl, i, " ->");
2115 move_lock_status(&q, &pos, offset);
2116
2117 if(pos >= offset+length)
2118 goto done;
2119 }
2120 }
2121done:
2122 unlock_kernel();
2123 *start = buffer;
2124 if(q-buffer < length)
2125 return (q-buffer);
2126 return length;
2127}
2128
2129/**
2130 * lock_may_read - checks that the region is free of locks
2131 * @inode: the inode that is being read
2132 * @start: the first byte to read
2133 * @len: the number of bytes to read
2134 *
2135 * Emulates Windows locking requirements. Whole-file
2136 * mandatory locks (share modes) can prohibit a read and
2137 * byte-range POSIX locks can prohibit a read if they overlap.
2138 *
2139 * N.B. this function is only ever called
2140 * from knfsd and ownership of locks is never checked.
2141 */
2142int lock_may_read(struct inode *inode, loff_t start, unsigned long len)
2143{
2144 struct file_lock *fl;
2145 int result = 1;
2146 lock_kernel();
2147 for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) {
2148 if (IS_POSIX(fl)) {
2149 if (fl->fl_type == F_RDLCK)
2150 continue;
2151 if ((fl->fl_end < start) || (fl->fl_start > (start + len)))
2152 continue;
2153 } else if (IS_FLOCK(fl)) {
2154 if (!(fl->fl_type & LOCK_MAND))
2155 continue;
2156 if (fl->fl_type & LOCK_READ)
2157 continue;
2158 } else
2159 continue;
2160 result = 0;
2161 break;
2162 }
2163 unlock_kernel();
2164 return result;
2165}
2166
2167EXPORT_SYMBOL(lock_may_read);
2168
2169/**
2170 * lock_may_write - checks that the region is free of locks
2171 * @inode: the inode that is being written
2172 * @start: the first byte to write
2173 * @len: the number of bytes to write
2174 *
2175 * Emulates Windows locking requirements. Whole-file
2176 * mandatory locks (share modes) can prohibit a write and
2177 * byte-range POSIX locks can prohibit a write if they overlap.
2178 *
2179 * N.B. this function is only ever called
2180 * from knfsd and ownership of locks is never checked.
2181 */
2182int lock_may_write(struct inode *inode, loff_t start, unsigned long len)
2183{
2184 struct file_lock *fl;
2185 int result = 1;
2186 lock_kernel();
2187 for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) {
2188 if (IS_POSIX(fl)) {
2189 if ((fl->fl_end < start) || (fl->fl_start > (start + len)))
2190 continue;
2191 } else if (IS_FLOCK(fl)) {
2192 if (!(fl->fl_type & LOCK_MAND))
2193 continue;
2194 if (fl->fl_type & LOCK_WRITE)
2195 continue;
2196 } else
2197 continue;
2198 result = 0;
2199 break;
2200 }
2201 unlock_kernel();
2202 return result;
2203}
2204
2205EXPORT_SYMBOL(lock_may_write);
2206
Linus Torvalds1da177e2005-04-16 15:20:36 -07002207static int __init filelock_init(void)
2208{
2209 filelock_cache = kmem_cache_create("file_lock_cache",
2210 sizeof(struct file_lock), 0, SLAB_PANIC,
2211 init_once, NULL);
2212 return 0;
2213}
2214
2215core_initcall(filelock_init);