blob: 44d9a6a7ec50caad376e36d721a3a42bc5028948 [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>
Vitaliy Gusevab1f1612008-01-17 00:07:08 +0000128#include <linux/pid_namespace.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -0700129
Linus Torvalds1da177e2005-04-16 15:20:36 -0700130#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
Christoph Lametere18b8902006-12-06 20:33:20 -0800145static struct kmem_cache *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{
Christoph Lametere94b1762006-12-06 20:33:17 -0800150 return kmem_cache_alloc(filelock_cache, GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700151}
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;
Vitaliy Gusevab1f1612008-01-17 00:07:08 +0000188 fl->fl_nspid = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700189 fl->fl_file = NULL;
190 fl->fl_flags = 0;
191 fl->fl_type = 0;
192 fl->fl_start = fl->fl_end = 0;
193 fl->fl_ops = NULL;
194 fl->fl_lmops = NULL;
195}
196
197EXPORT_SYMBOL(locks_init_lock);
198
199/*
200 * Initialises the fields of the file lock which are invariant for
201 * free file_locks.
202 */
Christoph Lameter4ba9b9d2007-10-16 23:25:51 -0700203static void init_once(struct kmem_cache *cache, void *foo)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700204{
205 struct file_lock *lock = (struct file_lock *) foo;
206
Linus Torvalds1da177e2005-04-16 15:20:36 -0700207 locks_init_lock(lock);
208}
209
Trond Myklebust47831f32006-03-20 13:44:05 -0500210static void locks_copy_private(struct file_lock *new, struct file_lock *fl)
211{
212 if (fl->fl_ops) {
213 if (fl->fl_ops->fl_copy_lock)
214 fl->fl_ops->fl_copy_lock(new, fl);
215 new->fl_ops = fl->fl_ops;
216 }
217 if (fl->fl_lmops) {
218 if (fl->fl_lmops->fl_copy_lock)
219 fl->fl_lmops->fl_copy_lock(new, fl);
220 new->fl_lmops = fl->fl_lmops;
221 }
222}
223
Linus Torvalds1da177e2005-04-16 15:20:36 -0700224/*
225 * Initialize a new lock from an existing file_lock structure.
226 */
J. Bruce Fields1a747ee2008-04-24 10:08:22 -0400227void __locks_copy_lock(struct file_lock *new, const struct file_lock *fl)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700228{
229 new->fl_owner = fl->fl_owner;
230 new->fl_pid = fl->fl_pid;
Trond Myklebust09969052006-03-20 13:44:38 -0500231 new->fl_file = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700232 new->fl_flags = fl->fl_flags;
233 new->fl_type = fl->fl_type;
234 new->fl_start = fl->fl_start;
235 new->fl_end = fl->fl_end;
Trond Myklebust09969052006-03-20 13:44:38 -0500236 new->fl_ops = NULL;
237 new->fl_lmops = NULL;
238}
Roland Dreier3dd7b712008-04-25 15:32:51 -0700239EXPORT_SYMBOL(__locks_copy_lock);
Trond Myklebust09969052006-03-20 13:44:38 -0500240
241void locks_copy_lock(struct file_lock *new, struct file_lock *fl)
242{
243 locks_release_private(new);
244
245 __locks_copy_lock(new, fl);
246 new->fl_file = fl->fl_file;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700247 new->fl_ops = fl->fl_ops;
248 new->fl_lmops = fl->fl_lmops;
Trond Myklebust47831f32006-03-20 13:44:05 -0500249
250 locks_copy_private(new, fl);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700251}
252
253EXPORT_SYMBOL(locks_copy_lock);
254
255static inline int flock_translate_cmd(int cmd) {
256 if (cmd & LOCK_MAND)
257 return cmd & (LOCK_MAND | LOCK_RW);
258 switch (cmd) {
259 case LOCK_SH:
260 return F_RDLCK;
261 case LOCK_EX:
262 return F_WRLCK;
263 case LOCK_UN:
264 return F_UNLCK;
265 }
266 return -EINVAL;
267}
268
269/* Fill in a file_lock structure with an appropriate FLOCK lock. */
270static int flock_make_lock(struct file *filp, struct file_lock **lock,
271 unsigned int cmd)
272{
273 struct file_lock *fl;
274 int type = flock_translate_cmd(cmd);
275 if (type < 0)
276 return type;
277
278 fl = locks_alloc_lock();
279 if (fl == NULL)
280 return -ENOMEM;
281
282 fl->fl_file = filp;
283 fl->fl_pid = current->tgid;
284 fl->fl_flags = FL_FLOCK;
285 fl->fl_type = type;
286 fl->fl_end = OFFSET_MAX;
287
288 *lock = fl;
289 return 0;
290}
291
292static int assign_type(struct file_lock *fl, int type)
293{
294 switch (type) {
295 case F_RDLCK:
296 case F_WRLCK:
297 case F_UNLCK:
298 fl->fl_type = type;
299 break;
300 default:
301 return -EINVAL;
302 }
303 return 0;
304}
305
306/* Verify a "struct flock" and copy it to a "struct file_lock" as a POSIX
307 * style lock.
308 */
309static int flock_to_posix_lock(struct file *filp, struct file_lock *fl,
310 struct flock *l)
311{
312 off_t start, end;
313
314 switch (l->l_whence) {
Josef 'Jeff' Sipekf5579f82006-09-30 23:27:35 -0700315 case SEEK_SET:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700316 start = 0;
317 break;
Josef 'Jeff' Sipekf5579f82006-09-30 23:27:35 -0700318 case SEEK_CUR:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700319 start = filp->f_pos;
320 break;
Josef 'Jeff' Sipekf5579f82006-09-30 23:27:35 -0700321 case SEEK_END:
Josef "Jeff" Sipek0f7fc9e2006-12-08 02:36:35 -0800322 start = i_size_read(filp->f_path.dentry->d_inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700323 break;
324 default:
325 return -EINVAL;
326 }
327
328 /* POSIX-1996 leaves the case l->l_len < 0 undefined;
329 POSIX-2001 defines it. */
330 start += l->l_start;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700331 if (start < 0)
332 return -EINVAL;
Trond Myklebust4c780a42005-10-18 14:20:21 -0700333 fl->fl_end = OFFSET_MAX;
334 if (l->l_len > 0) {
335 end = start + l->l_len - 1;
336 fl->fl_end = end;
337 } else if (l->l_len < 0) {
338 end = start - 1;
339 fl->fl_end = end;
340 start += l->l_len;
341 if (start < 0)
342 return -EINVAL;
343 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700344 fl->fl_start = start; /* we record the absolute position */
Trond Myklebust4c780a42005-10-18 14:20:21 -0700345 if (fl->fl_end < fl->fl_start)
346 return -EOVERFLOW;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700347
348 fl->fl_owner = current->files;
349 fl->fl_pid = current->tgid;
350 fl->fl_file = filp;
351 fl->fl_flags = FL_POSIX;
352 fl->fl_ops = NULL;
353 fl->fl_lmops = NULL;
354
355 return assign_type(fl, l->l_type);
356}
357
358#if BITS_PER_LONG == 32
359static int flock64_to_posix_lock(struct file *filp, struct file_lock *fl,
360 struct flock64 *l)
361{
362 loff_t start;
363
364 switch (l->l_whence) {
Josef 'Jeff' Sipekf5579f82006-09-30 23:27:35 -0700365 case SEEK_SET:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700366 start = 0;
367 break;
Josef 'Jeff' Sipekf5579f82006-09-30 23:27:35 -0700368 case SEEK_CUR:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700369 start = filp->f_pos;
370 break;
Josef 'Jeff' Sipekf5579f82006-09-30 23:27:35 -0700371 case SEEK_END:
Josef "Jeff" Sipek0f7fc9e2006-12-08 02:36:35 -0800372 start = i_size_read(filp->f_path.dentry->d_inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700373 break;
374 default:
375 return -EINVAL;
376 }
377
Trond Myklebust4c780a42005-10-18 14:20:21 -0700378 start += l->l_start;
379 if (start < 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700380 return -EINVAL;
Trond Myklebust4c780a42005-10-18 14:20:21 -0700381 fl->fl_end = OFFSET_MAX;
382 if (l->l_len > 0) {
383 fl->fl_end = start + l->l_len - 1;
384 } else if (l->l_len < 0) {
385 fl->fl_end = start - 1;
386 start += l->l_len;
387 if (start < 0)
388 return -EINVAL;
389 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700390 fl->fl_start = start; /* we record the absolute position */
Trond Myklebust4c780a42005-10-18 14:20:21 -0700391 if (fl->fl_end < fl->fl_start)
392 return -EOVERFLOW;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700393
394 fl->fl_owner = current->files;
395 fl->fl_pid = current->tgid;
396 fl->fl_file = filp;
397 fl->fl_flags = FL_POSIX;
398 fl->fl_ops = NULL;
399 fl->fl_lmops = NULL;
400
401 switch (l->l_type) {
402 case F_RDLCK:
403 case F_WRLCK:
404 case F_UNLCK:
405 fl->fl_type = l->l_type;
406 break;
407 default:
408 return -EINVAL;
409 }
410
411 return (0);
412}
413#endif
414
415/* default lease lock manager operations */
416static void lease_break_callback(struct file_lock *fl)
417{
418 kill_fasync(&fl->fl_fasync, SIGIO, POLL_MSG);
419}
420
421static void lease_release_private_callback(struct file_lock *fl)
422{
423 if (!fl->fl_file)
424 return;
425
426 f_delown(fl->fl_file);
427 fl->fl_file->f_owner.signum = 0;
428}
429
Adrian Bunk75c96f82005-05-05 16:16:09 -0700430static int lease_mylease_callback(struct file_lock *fl, struct file_lock *try)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700431{
432 return fl->fl_file == try->fl_file;
433}
434
Adrian Bunk75c96f82005-05-05 16:16:09 -0700435static struct lock_manager_operations lease_manager_ops = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700436 .fl_break = lease_break_callback,
437 .fl_release_private = lease_release_private_callback,
438 .fl_mylease = lease_mylease_callback,
439 .fl_change = lease_modify,
440};
441
442/*
443 * Initialize a lease, use the default lock manager operations
444 */
445static int lease_init(struct file *filp, int type, struct file_lock *fl)
446 {
Trond Myklebust75dff552006-05-07 23:02:42 -0400447 if (assign_type(fl, type) != 0)
448 return -EINVAL;
449
Linus Torvalds1da177e2005-04-16 15:20:36 -0700450 fl->fl_owner = current->files;
451 fl->fl_pid = current->tgid;
452
453 fl->fl_file = filp;
454 fl->fl_flags = FL_LEASE;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700455 fl->fl_start = 0;
456 fl->fl_end = OFFSET_MAX;
457 fl->fl_ops = NULL;
458 fl->fl_lmops = &lease_manager_ops;
459 return 0;
460}
461
462/* Allocate a file_lock initialised to this type of lease */
J. Bruce Fieldse32b8ee2007-03-01 14:34:35 -0500463static struct file_lock *lease_alloc(struct file *filp, int type)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700464{
465 struct file_lock *fl = locks_alloc_lock();
Trond Myklebust75dff552006-05-07 23:02:42 -0400466 int error = -ENOMEM;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700467
468 if (fl == NULL)
J. Bruce Fieldse32b8ee2007-03-01 14:34:35 -0500469 return ERR_PTR(error);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700470
471 error = lease_init(filp, type, fl);
Trond Myklebust75dff552006-05-07 23:02:42 -0400472 if (error) {
473 locks_free_lock(fl);
J. Bruce Fieldse32b8ee2007-03-01 14:34:35 -0500474 return ERR_PTR(error);
Trond Myklebust75dff552006-05-07 23:02:42 -0400475 }
J. Bruce Fieldse32b8ee2007-03-01 14:34:35 -0500476 return fl;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700477}
478
479/* Check if two locks overlap each other.
480 */
481static inline int locks_overlap(struct file_lock *fl1, struct file_lock *fl2)
482{
483 return ((fl1->fl_end >= fl2->fl_start) &&
484 (fl2->fl_end >= fl1->fl_start));
485}
486
487/*
488 * Check whether two locks have the same owner.
489 */
Matt Mackall33443c42006-01-08 01:05:22 -0800490static int posix_same_owner(struct file_lock *fl1, struct file_lock *fl2)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700491{
492 if (fl1->fl_lmops && fl1->fl_lmops->fl_compare_owner)
493 return fl2->fl_lmops == fl1->fl_lmops &&
494 fl1->fl_lmops->fl_compare_owner(fl1, fl2);
495 return fl1->fl_owner == fl2->fl_owner;
496}
497
498/* Remove waiter from blocker's block list.
499 * When blocker ends up pointing to itself then the list is empty.
500 */
Matt Mackall33443c42006-01-08 01:05:22 -0800501static void __locks_delete_block(struct file_lock *waiter)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700502{
503 list_del_init(&waiter->fl_block);
504 list_del_init(&waiter->fl_link);
505 waiter->fl_next = NULL;
506}
507
508/*
509 */
510static void locks_delete_block(struct file_lock *waiter)
511{
512 lock_kernel();
513 __locks_delete_block(waiter);
514 unlock_kernel();
515}
516
517/* Insert waiter into blocker's block list.
518 * We use a circular list so that processes can be easily woken up in
519 * the order they blocked. The documentation doesn't require this but
520 * it seems like the reasonable thing to do.
521 */
522static void locks_insert_block(struct file_lock *blocker,
523 struct file_lock *waiter)
524{
J. Bruce Fields6dc0fe82006-03-26 01:37:24 -0800525 BUG_ON(!list_empty(&waiter->fl_block));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700526 list_add_tail(&waiter->fl_block, &blocker->fl_block);
527 waiter->fl_next = blocker;
528 if (IS_POSIX(blocker))
529 list_add(&waiter->fl_link, &blocked_list);
530}
531
532/* Wake up processes blocked waiting for blocker.
533 * If told to wait then schedule the processes until the block list
534 * is empty, otherwise empty the block list ourselves.
535 */
536static void locks_wake_up_blocks(struct file_lock *blocker)
537{
538 while (!list_empty(&blocker->fl_block)) {
Pavel Emelyanovf0c1cd02007-09-19 16:44:07 +0400539 struct file_lock *waiter;
540
541 waiter = list_first_entry(&blocker->fl_block,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700542 struct file_lock, fl_block);
543 __locks_delete_block(waiter);
544 if (waiter->fl_lmops && waiter->fl_lmops->fl_notify)
545 waiter->fl_lmops->fl_notify(waiter);
546 else
547 wake_up(&waiter->fl_wait);
548 }
549}
550
551/* Insert file lock fl into an inode's lock list at the position indicated
552 * by pos. At the same time add the lock to the global file lock list.
553 */
554static void locks_insert_lock(struct file_lock **pos, struct file_lock *fl)
555{
556 list_add(&fl->fl_link, &file_lock_list);
557
Vitaliy Gusevab1f1612008-01-17 00:07:08 +0000558 fl->fl_nspid = get_pid(task_tgid(current));
559
Linus Torvalds1da177e2005-04-16 15:20:36 -0700560 /* 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
Vitaliy Gusevab1f1612008-01-17 00:07:08 +0000591 if (fl->fl_nspid) {
592 put_pid(fl->fl_nspid);
593 fl->fl_nspid = NULL;
594 }
595
Linus Torvalds1da177e2005-04-16 15:20:36 -0700596 locks_wake_up_blocks(fl);
597 locks_free_lock(fl);
598}
599
600/* Determine if lock sys_fl blocks lock caller_fl. Common functionality
601 * checks for shared/exclusive status of overlapping locks.
602 */
603static int locks_conflict(struct file_lock *caller_fl, struct file_lock *sys_fl)
604{
605 if (sys_fl->fl_type == F_WRLCK)
606 return 1;
607 if (caller_fl->fl_type == F_WRLCK)
608 return 1;
609 return 0;
610}
611
612/* Determine if lock sys_fl blocks lock caller_fl. POSIX specific
613 * checking before calling the locks_conflict().
614 */
615static int posix_locks_conflict(struct file_lock *caller_fl, struct file_lock *sys_fl)
616{
617 /* POSIX locks owned by the same process do not conflict with
618 * each other.
619 */
620 if (!IS_POSIX(sys_fl) || posix_same_owner(caller_fl, sys_fl))
621 return (0);
622
623 /* Check whether they overlap */
624 if (!locks_overlap(caller_fl, sys_fl))
625 return 0;
626
627 return (locks_conflict(caller_fl, sys_fl));
628}
629
630/* Determine if lock sys_fl blocks lock caller_fl. FLOCK specific
631 * checking before calling the locks_conflict().
632 */
633static int flock_locks_conflict(struct file_lock *caller_fl, struct file_lock *sys_fl)
634{
635 /* FLOCK locks referring to the same filp do not conflict with
636 * each other.
637 */
638 if (!IS_FLOCK(sys_fl) || (caller_fl->fl_file == sys_fl->fl_file))
639 return (0);
640 if ((caller_fl->fl_type & LOCK_MAND) || (sys_fl->fl_type & LOCK_MAND))
641 return 0;
642
643 return (locks_conflict(caller_fl, sys_fl));
644}
645
J. Bruce Fields6d34ac12007-05-11 16:09:32 -0400646void
Marc Eshel9d6a8c52007-02-21 00:55:18 -0500647posix_test_lock(struct file *filp, struct file_lock *fl)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700648{
649 struct file_lock *cfl;
650
651 lock_kernel();
Josef "Jeff" Sipek0f7fc9e2006-12-08 02:36:35 -0800652 for (cfl = filp->f_path.dentry->d_inode->i_flock; cfl; cfl = cfl->fl_next) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700653 if (!IS_POSIX(cfl))
654 continue;
J. Bruce Fieldsb842e242007-05-10 19:02:07 -0400655 if (posix_locks_conflict(fl, cfl))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700656 break;
657 }
Vitaliy Gusevab1f1612008-01-17 00:07:08 +0000658 if (cfl) {
Marc Eshel9d6a8c52007-02-21 00:55:18 -0500659 __locks_copy_lock(fl, cfl);
Vitaliy Gusevab1f1612008-01-17 00:07:08 +0000660 if (cfl->fl_nspid)
Pavel Emelyanov6c5f3e72008-02-08 04:19:20 -0800661 fl->fl_pid = pid_vnr(cfl->fl_nspid);
Vitaliy Gusevab1f1612008-01-17 00:07:08 +0000662 } else
J. Bruce Fields129a84d2007-05-10 18:38:43 -0400663 fl->fl_type = F_UNLCK;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700664 unlock_kernel();
J. Bruce Fields6d34ac12007-05-11 16:09:32 -0400665 return;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700666}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700667EXPORT_SYMBOL(posix_test_lock);
668
J. Bruce Fieldsb5331842007-10-26 18:05:40 -0400669/*
670 * Deadlock detection:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700671 *
J. Bruce Fieldsb5331842007-10-26 18:05:40 -0400672 * We attempt to detect deadlocks that are due purely to posix file
673 * locks.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700674 *
J. Bruce Fieldsb5331842007-10-26 18:05:40 -0400675 * We assume that a task can be waiting for at most one lock at a time.
676 * So for any acquired lock, the process holding that lock may be
677 * waiting on at most one other lock. That lock in turns may be held by
678 * someone waiting for at most one other lock. Given a requested lock
679 * caller_fl which is about to wait for a conflicting lock block_fl, we
680 * follow this chain of waiters to ensure we are not about to create a
681 * cycle.
J. Bruce Fields97855b42007-10-30 11:20:02 -0400682 *
J. Bruce Fieldsb5331842007-10-26 18:05:40 -0400683 * Since we do this before we ever put a process to sleep on a lock, we
684 * are ensured that there is never a cycle; that is what guarantees that
685 * the while() loop in posix_locks_deadlock() eventually completes.
686 *
687 * Note: the above assumption may not be true when handling lock
688 * requests from a broken NFS client. It may also fail in the presence
689 * of tasks (such as posix threads) sharing the same open file table.
690 *
691 * To handle those cases, we just bail out after a few iterations.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700692 */
J. Bruce Fields97855b42007-10-30 11:20:02 -0400693
694#define MAX_DEADLK_ITERATIONS 10
695
J. Bruce Fieldsb5331842007-10-26 18:05:40 -0400696/* Find a lock that the owner of the given block_fl is blocking on. */
697static struct file_lock *what_owner_is_waiting_for(struct file_lock *block_fl)
698{
699 struct file_lock *fl;
700
701 list_for_each_entry(fl, &blocked_list, fl_link) {
702 if (posix_same_owner(fl, block_fl))
703 return fl->fl_next;
704 }
705 return NULL;
706}
707
Adrian Bunkb0904e12006-06-23 02:05:13 -0700708static int posix_locks_deadlock(struct file_lock *caller_fl,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700709 struct file_lock *block_fl)
710{
J. Bruce Fields97855b42007-10-30 11:20:02 -0400711 int i = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700712
J. Bruce Fieldsb5331842007-10-26 18:05:40 -0400713 while ((block_fl = what_owner_is_waiting_for(block_fl))) {
714 if (i++ > MAX_DEADLK_ITERATIONS)
715 return 0;
716 if (posix_same_owner(caller_fl, block_fl))
717 return 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700718 }
719 return 0;
720}
721
Linus Torvalds1da177e2005-04-16 15:20:36 -0700722/* Try to create a FLOCK lock on filp. We always insert new FLOCK locks
J. Bruce Fields02888f42007-09-12 15:45:07 -0400723 * after any leases, but before any posix locks.
Trond Myklebustf475ae92006-06-29 16:38:32 -0400724 *
725 * Note that if called with an FL_EXISTS argument, the caller may determine
726 * whether or not a lock was successfully freed by testing the return
727 * value for -ENOENT.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700728 */
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;
Josef "Jeff" Sipek0f7fc9e2006-12-08 02:36:35 -0800733 struct inode * inode = filp->f_path.dentry->d_inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700734 int error = 0;
735 int found = 0;
736
737 lock_kernel();
Trond Myklebustf07f18d2006-06-29 16:38:37 -0400738 if (request->fl_flags & FL_ACCESS)
739 goto find_conflict;
Pavel Emelyanov84d535a2007-09-11 16:38:13 +0400740
741 if (request->fl_type != F_UNLCK) {
742 error = -ENOMEM;
743 new_fl = locks_alloc_lock();
744 if (new_fl == NULL)
745 goto out;
746 error = 0;
747 }
748
Linus Torvalds1da177e2005-04-16 15:20:36 -0700749 for_each_lock(inode, before) {
750 struct file_lock *fl = *before;
751 if (IS_POSIX(fl))
752 break;
753 if (IS_LEASE(fl))
754 continue;
755 if (filp != fl->fl_file)
756 continue;
Trond Myklebust993dfa82006-03-31 02:30:55 -0800757 if (request->fl_type == fl->fl_type)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700758 goto out;
759 found = 1;
760 locks_delete_lock(before);
761 break;
762 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700763
Trond Myklebustf475ae92006-06-29 16:38:32 -0400764 if (request->fl_type == F_UNLCK) {
765 if ((request->fl_flags & FL_EXISTS) && !found)
766 error = -ENOENT;
Trond Myklebust993dfa82006-03-31 02:30:55 -0800767 goto out;
Trond Myklebustf475ae92006-06-29 16:38:32 -0400768 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700769
770 /*
771 * If a higher-priority process was blocked on the old file lock,
772 * give it the opportunity to lock the file.
773 */
774 if (found)
775 cond_resched();
776
Trond Myklebustf07f18d2006-06-29 16:38:37 -0400777find_conflict:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700778 for_each_lock(inode, before) {
779 struct file_lock *fl = *before;
780 if (IS_POSIX(fl))
781 break;
782 if (IS_LEASE(fl))
783 continue;
Trond Myklebust993dfa82006-03-31 02:30:55 -0800784 if (!flock_locks_conflict(request, fl))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700785 continue;
786 error = -EAGAIN;
Trond Myklebust993dfa82006-03-31 02:30:55 -0800787 if (request->fl_flags & FL_SLEEP)
788 locks_insert_block(fl, request);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700789 goto out;
790 }
Trond Myklebustf07f18d2006-06-29 16:38:37 -0400791 if (request->fl_flags & FL_ACCESS)
792 goto out;
Trond Myklebust993dfa82006-03-31 02:30:55 -0800793 locks_copy_lock(new_fl, request);
Pavel Emelyanov0e2f6db2007-09-11 15:24:01 -0700794 locks_insert_lock(before, new_fl);
Trond Myklebust993dfa82006-03-31 02:30:55 -0800795 new_fl = NULL;
Kirill Korotaev9cedc192006-06-14 17:59:35 +0400796 error = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700797
798out:
799 unlock_kernel();
Trond Myklebust993dfa82006-03-31 02:30:55 -0800800 if (new_fl)
801 locks_free_lock(new_fl);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700802 return error;
803}
804
Marc Eshel150b3932007-01-18 16:15:35 -0500805static int __posix_lock_file(struct inode *inode, struct file_lock *request, struct file_lock *conflock)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700806{
807 struct file_lock *fl;
Miklos Szeredi39005d02006-06-23 02:05:10 -0700808 struct file_lock *new_fl = NULL;
809 struct file_lock *new_fl2 = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700810 struct file_lock *left = NULL;
811 struct file_lock *right = NULL;
812 struct file_lock **before;
813 int error, added = 0;
814
815 /*
816 * We may need two file_lock structures for this operation,
817 * so we get them in advance to avoid races.
Miklos Szeredi39005d02006-06-23 02:05:10 -0700818 *
819 * In some cases we can be sure, that no new locks will be needed
Linus Torvalds1da177e2005-04-16 15:20:36 -0700820 */
Miklos Szeredi39005d02006-06-23 02:05:10 -0700821 if (!(request->fl_flags & FL_ACCESS) &&
822 (request->fl_type != F_UNLCK ||
823 request->fl_start != 0 || request->fl_end != OFFSET_MAX)) {
824 new_fl = locks_alloc_lock();
825 new_fl2 = locks_alloc_lock();
826 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700827
828 lock_kernel();
829 if (request->fl_type != F_UNLCK) {
830 for_each_lock(inode, before) {
J. Bruce Fields526985b2006-11-14 16:54:36 -0500831 fl = *before;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700832 if (!IS_POSIX(fl))
833 continue;
834 if (!posix_locks_conflict(request, fl))
835 continue;
Andy Adamson5842add2006-03-26 01:37:26 -0800836 if (conflock)
J. Bruce Fields1a747ee2008-04-24 10:08:22 -0400837 __locks_copy_lock(conflock, fl);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700838 error = -EAGAIN;
839 if (!(request->fl_flags & FL_SLEEP))
840 goto out;
841 error = -EDEADLK;
842 if (posix_locks_deadlock(request, fl))
843 goto out;
844 error = -EAGAIN;
845 locks_insert_block(fl, request);
846 goto out;
847 }
848 }
849
850 /* If we're just looking for a conflict, we're done. */
851 error = 0;
852 if (request->fl_flags & FL_ACCESS)
853 goto out;
854
Linus Torvalds1da177e2005-04-16 15:20:36 -0700855 /*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700856 * Find the first old lock with the same owner as the new lock.
857 */
858
859 before = &inode->i_flock;
860
861 /* First skip locks owned by other processes. */
862 while ((fl = *before) && (!IS_POSIX(fl) ||
863 !posix_same_owner(request, fl))) {
864 before = &fl->fl_next;
865 }
866
867 /* Process locks with this owner. */
868 while ((fl = *before) && posix_same_owner(request, fl)) {
869 /* Detect adjacent or overlapping regions (if same lock type)
870 */
871 if (request->fl_type == fl->fl_type) {
Olaf Kirch449231d2005-08-25 16:25:35 -0700872 /* In all comparisons of start vs end, use
873 * "start - 1" rather than "end + 1". If end
874 * is OFFSET_MAX, end + 1 will become negative.
875 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700876 if (fl->fl_end < request->fl_start - 1)
877 goto next_lock;
878 /* If the next lock in the list has entirely bigger
879 * addresses than the new one, insert the lock here.
880 */
Olaf Kirch449231d2005-08-25 16:25:35 -0700881 if (fl->fl_start - 1 > request->fl_end)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700882 break;
883
884 /* If we come here, the new and old lock are of the
885 * same type and adjacent or overlapping. Make one
886 * lock yielding from the lower start address of both
887 * locks to the higher end address.
888 */
889 if (fl->fl_start > request->fl_start)
890 fl->fl_start = request->fl_start;
891 else
892 request->fl_start = fl->fl_start;
893 if (fl->fl_end < request->fl_end)
894 fl->fl_end = request->fl_end;
895 else
896 request->fl_end = fl->fl_end;
897 if (added) {
898 locks_delete_lock(before);
899 continue;
900 }
901 request = fl;
902 added = 1;
903 }
904 else {
905 /* Processing for different lock types is a bit
906 * more complex.
907 */
908 if (fl->fl_end < request->fl_start)
909 goto next_lock;
910 if (fl->fl_start > request->fl_end)
911 break;
912 if (request->fl_type == F_UNLCK)
913 added = 1;
914 if (fl->fl_start < request->fl_start)
915 left = fl;
916 /* If the next lock in the list has a higher end
917 * address than the new one, insert the new one here.
918 */
919 if (fl->fl_end > request->fl_end) {
920 right = fl;
921 break;
922 }
923 if (fl->fl_start >= request->fl_start) {
924 /* The new lock completely replaces an old
925 * one (This may happen several times).
926 */
927 if (added) {
928 locks_delete_lock(before);
929 continue;
930 }
931 /* Replace the old lock with the new one.
932 * Wake up anybody waiting for the old one,
933 * as the change in lock type might satisfy
934 * their needs.
935 */
936 locks_wake_up_blocks(fl);
937 fl->fl_start = request->fl_start;
938 fl->fl_end = request->fl_end;
939 fl->fl_type = request->fl_type;
Trond Myklebust47831f32006-03-20 13:44:05 -0500940 locks_release_private(fl);
941 locks_copy_private(fl, request);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700942 request = fl;
943 added = 1;
944 }
945 }
946 /* Go on to next lock.
947 */
948 next_lock:
949 before = &fl->fl_next;
950 }
951
Miklos Szeredi0d9a4902006-06-23 02:05:09 -0700952 /*
953 * The above code only modifies existing locks in case of
954 * merging or replacing. If new lock(s) need to be inserted
955 * all modifications are done bellow this, so it's safe yet to
956 * bail out.
957 */
958 error = -ENOLCK; /* "no luck" */
959 if (right && left == right && !new_fl2)
960 goto out;
961
Linus Torvalds1da177e2005-04-16 15:20:36 -0700962 error = 0;
963 if (!added) {
Trond Myklebustf475ae92006-06-29 16:38:32 -0400964 if (request->fl_type == F_UNLCK) {
965 if (request->fl_flags & FL_EXISTS)
966 error = -ENOENT;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700967 goto out;
Trond Myklebustf475ae92006-06-29 16:38:32 -0400968 }
Miklos Szeredi0d9a4902006-06-23 02:05:09 -0700969
970 if (!new_fl) {
971 error = -ENOLCK;
972 goto out;
973 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700974 locks_copy_lock(new_fl, request);
975 locks_insert_lock(before, new_fl);
976 new_fl = NULL;
977 }
978 if (right) {
979 if (left == right) {
980 /* The new lock breaks the old one in two pieces,
981 * so we have to use the second new lock.
982 */
983 left = new_fl2;
984 new_fl2 = NULL;
985 locks_copy_lock(left, right);
986 locks_insert_lock(before, left);
987 }
988 right->fl_start = request->fl_end + 1;
989 locks_wake_up_blocks(right);
990 }
991 if (left) {
992 left->fl_end = request->fl_start - 1;
993 locks_wake_up_blocks(left);
994 }
995 out:
996 unlock_kernel();
997 /*
998 * Free any unused locks.
999 */
1000 if (new_fl)
1001 locks_free_lock(new_fl);
1002 if (new_fl2)
1003 locks_free_lock(new_fl2);
1004 return error;
1005}
1006
1007/**
1008 * posix_lock_file - Apply a POSIX-style lock to a file
1009 * @filp: The file to apply the lock to
1010 * @fl: The lock to be applied
Marc Eshel150b3932007-01-18 16:15:35 -05001011 * @conflock: Place to return a copy of the conflicting lock, if found.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001012 *
1013 * Add a POSIX style lock to a file.
1014 * We merge adjacent & overlapping locks whenever possible.
1015 * POSIX locks are sorted by owner task, then by starting address
Trond Myklebustf475ae92006-06-29 16:38:32 -04001016 *
1017 * Note that if called with an FL_EXISTS argument, the caller may determine
1018 * whether or not a lock was successfully freed by testing the return
1019 * value for -ENOENT.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001020 */
Marc Eshel150b3932007-01-18 16:15:35 -05001021int posix_lock_file(struct file *filp, struct file_lock *fl,
Andy Adamson5842add2006-03-26 01:37:26 -08001022 struct file_lock *conflock)
1023{
Marc Eshel150b3932007-01-18 16:15:35 -05001024 return __posix_lock_file(filp->f_path.dentry->d_inode, fl, conflock);
Andy Adamson5842add2006-03-26 01:37:26 -08001025}
Marc Eshel150b3932007-01-18 16:15:35 -05001026EXPORT_SYMBOL(posix_lock_file);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001027
1028/**
1029 * posix_lock_file_wait - Apply a POSIX-style lock to a file
1030 * @filp: The file to apply the lock to
1031 * @fl: The lock to be applied
1032 *
1033 * Add a POSIX style lock to a file.
1034 * We merge adjacent & overlapping locks whenever possible.
1035 * POSIX locks are sorted by owner task, then by starting address
1036 */
1037int posix_lock_file_wait(struct file *filp, struct file_lock *fl)
1038{
1039 int error;
1040 might_sleep ();
1041 for (;;) {
Marc Eshel150b3932007-01-18 16:15:35 -05001042 error = posix_lock_file(filp, fl, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001043 if ((error != -EAGAIN) || !(fl->fl_flags & FL_SLEEP))
1044 break;
1045 error = wait_event_interruptible(fl->fl_wait, !fl->fl_next);
1046 if (!error)
1047 continue;
1048
1049 locks_delete_block(fl);
1050 break;
1051 }
1052 return error;
1053}
1054EXPORT_SYMBOL(posix_lock_file_wait);
1055
1056/**
1057 * locks_mandatory_locked - Check for an active lock
1058 * @inode: the file to check
1059 *
1060 * Searches the inode's list of locks to find any POSIX locks which conflict.
1061 * This function is called from locks_verify_locked() only.
1062 */
1063int locks_mandatory_locked(struct inode *inode)
1064{
1065 fl_owner_t owner = current->files;
1066 struct file_lock *fl;
1067
1068 /*
1069 * Search the lock list for this inode for any POSIX locks.
1070 */
1071 lock_kernel();
1072 for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) {
1073 if (!IS_POSIX(fl))
1074 continue;
1075 if (fl->fl_owner != owner)
1076 break;
1077 }
1078 unlock_kernel();
1079 return fl ? -EAGAIN : 0;
1080}
1081
1082/**
1083 * locks_mandatory_area - Check for a conflicting lock
1084 * @read_write: %FLOCK_VERIFY_WRITE for exclusive access, %FLOCK_VERIFY_READ
1085 * for shared
1086 * @inode: the file to check
1087 * @filp: how the file was opened (if it was)
1088 * @offset: start of area to check
1089 * @count: length of area to check
1090 *
1091 * Searches the inode's list of locks to find any POSIX locks which conflict.
1092 * This function is called from rw_verify_area() and
1093 * locks_verify_truncate().
1094 */
1095int locks_mandatory_area(int read_write, struct inode *inode,
1096 struct file *filp, loff_t offset,
1097 size_t count)
1098{
1099 struct file_lock fl;
1100 int error;
1101
1102 locks_init_lock(&fl);
1103 fl.fl_owner = current->files;
1104 fl.fl_pid = current->tgid;
1105 fl.fl_file = filp;
1106 fl.fl_flags = FL_POSIX | FL_ACCESS;
1107 if (filp && !(filp->f_flags & O_NONBLOCK))
1108 fl.fl_flags |= FL_SLEEP;
1109 fl.fl_type = (read_write == FLOCK_VERIFY_WRITE) ? F_WRLCK : F_RDLCK;
1110 fl.fl_start = offset;
1111 fl.fl_end = offset + count - 1;
1112
1113 for (;;) {
Marc Eshel150b3932007-01-18 16:15:35 -05001114 error = __posix_lock_file(inode, &fl, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001115 if (error != -EAGAIN)
1116 break;
1117 if (!(fl.fl_flags & FL_SLEEP))
1118 break;
1119 error = wait_event_interruptible(fl.fl_wait, !fl.fl_next);
1120 if (!error) {
1121 /*
1122 * If we've been sleeping someone might have
1123 * changed the permissions behind our back.
1124 */
Pavel Emelyanova16877c2007-10-01 14:41:11 -07001125 if (__mandatory_lock(inode))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001126 continue;
1127 }
1128
1129 locks_delete_block(&fl);
1130 break;
1131 }
1132
1133 return error;
1134}
1135
1136EXPORT_SYMBOL(locks_mandatory_area);
1137
1138/* We already had a lease on this file; just change its type */
1139int lease_modify(struct file_lock **before, int arg)
1140{
1141 struct file_lock *fl = *before;
1142 int error = assign_type(fl, arg);
1143
1144 if (error)
1145 return error;
1146 locks_wake_up_blocks(fl);
1147 if (arg == F_UNLCK)
1148 locks_delete_lock(before);
1149 return 0;
1150}
1151
1152EXPORT_SYMBOL(lease_modify);
1153
1154static void time_out_leases(struct inode *inode)
1155{
1156 struct file_lock **before;
1157 struct file_lock *fl;
1158
1159 before = &inode->i_flock;
1160 while ((fl = *before) && IS_LEASE(fl) && (fl->fl_type & F_INPROGRESS)) {
1161 if ((fl->fl_break_time == 0)
1162 || time_before(jiffies, fl->fl_break_time)) {
1163 before = &fl->fl_next;
1164 continue;
1165 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001166 lease_modify(before, fl->fl_type & ~F_INPROGRESS);
1167 if (fl == *before) /* lease_modify may have freed fl */
1168 before = &fl->fl_next;
1169 }
1170}
1171
1172/**
1173 * __break_lease - revoke all outstanding leases on file
1174 * @inode: the inode of the file to return
1175 * @mode: the open mode (read or write)
1176 *
david m. richter87250dd2007-05-09 16:10:27 -04001177 * break_lease (inlined for speed) has checked there already is at least
1178 * some kind of lock (maybe a lease) on this file. Leases are broken on
1179 * a call to open() or truncate(). This function can sleep unless you
Linus Torvalds1da177e2005-04-16 15:20:36 -07001180 * specified %O_NONBLOCK to your open().
1181 */
1182int __break_lease(struct inode *inode, unsigned int mode)
1183{
1184 int error = 0, future;
1185 struct file_lock *new_fl, *flock;
1186 struct file_lock *fl;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001187 unsigned long break_time;
1188 int i_have_this_lease = 0;
1189
J. Bruce Fieldse32b8ee2007-03-01 14:34:35 -05001190 new_fl = lease_alloc(NULL, mode & FMODE_WRITE ? F_WRLCK : F_RDLCK);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001191
1192 lock_kernel();
1193
1194 time_out_leases(inode);
1195
1196 flock = inode->i_flock;
1197 if ((flock == NULL) || !IS_LEASE(flock))
1198 goto out;
1199
1200 for (fl = flock; fl && IS_LEASE(fl); fl = fl->fl_next)
1201 if (fl->fl_owner == current->files)
1202 i_have_this_lease = 1;
1203
1204 if (mode & FMODE_WRITE) {
1205 /* If we want write access, we have to revoke any lease. */
1206 future = F_UNLCK | F_INPROGRESS;
1207 } else if (flock->fl_type & F_INPROGRESS) {
1208 /* If the lease is already being broken, we just leave it */
1209 future = flock->fl_type;
1210 } else if (flock->fl_type & F_WRLCK) {
1211 /* Downgrade the exclusive lease to a read-only lease. */
1212 future = F_RDLCK | F_INPROGRESS;
1213 } else {
1214 /* the existing lease was read-only, so we can read too. */
1215 goto out;
1216 }
1217
J. Bruce Fieldse32b8ee2007-03-01 14:34:35 -05001218 if (IS_ERR(new_fl) && !i_have_this_lease
1219 && ((mode & O_NONBLOCK) == 0)) {
1220 error = PTR_ERR(new_fl);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001221 goto out;
1222 }
1223
1224 break_time = 0;
1225 if (lease_break_time > 0) {
1226 break_time = jiffies + lease_break_time * HZ;
1227 if (break_time == 0)
1228 break_time++; /* so that 0 means no break time */
1229 }
1230
1231 for (fl = flock; fl && IS_LEASE(fl); fl = fl->fl_next) {
1232 if (fl->fl_type != future) {
1233 fl->fl_type = future;
1234 fl->fl_break_time = break_time;
1235 /* lease must have lmops break callback */
1236 fl->fl_lmops->fl_break(fl);
1237 }
1238 }
1239
1240 if (i_have_this_lease || (mode & O_NONBLOCK)) {
1241 error = -EWOULDBLOCK;
1242 goto out;
1243 }
1244
1245restart:
1246 break_time = flock->fl_break_time;
1247 if (break_time != 0) {
1248 break_time -= jiffies;
1249 if (break_time == 0)
1250 break_time++;
1251 }
Matthew Wilcox4321e012008-01-14 21:28:30 -07001252 locks_insert_block(flock, new_fl);
1253 error = wait_event_interruptible_timeout(new_fl->fl_wait,
1254 !new_fl->fl_next, break_time);
1255 __locks_delete_block(new_fl);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001256 if (error >= 0) {
1257 if (error == 0)
1258 time_out_leases(inode);
1259 /* Wait for the next lease that has not been broken yet */
1260 for (flock = inode->i_flock; flock && IS_LEASE(flock);
1261 flock = flock->fl_next) {
1262 if (flock->fl_type & F_INPROGRESS)
1263 goto restart;
1264 }
1265 error = 0;
1266 }
1267
1268out:
1269 unlock_kernel();
J. Bruce Fieldse32b8ee2007-03-01 14:34:35 -05001270 if (!IS_ERR(new_fl))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001271 locks_free_lock(new_fl);
1272 return error;
1273}
1274
1275EXPORT_SYMBOL(__break_lease);
1276
1277/**
Randy Dunlapa6b91912008-03-19 17:01:00 -07001278 * lease_get_mtime - get the last modified time of an inode
Linus Torvalds1da177e2005-04-16 15:20:36 -07001279 * @inode: the inode
1280 * @time: pointer to a timespec which will contain the last modified time
1281 *
1282 * This is to force NFS clients to flush their caches for files with
1283 * exclusive leases. The justification is that if someone has an
Randy Dunlapa6b91912008-03-19 17:01:00 -07001284 * exclusive lease, then they could be modifying it.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001285 */
1286void lease_get_mtime(struct inode *inode, struct timespec *time)
1287{
1288 struct file_lock *flock = inode->i_flock;
1289 if (flock && IS_LEASE(flock) && (flock->fl_type & F_WRLCK))
1290 *time = current_fs_time(inode->i_sb);
1291 else
1292 *time = inode->i_mtime;
1293}
1294
1295EXPORT_SYMBOL(lease_get_mtime);
1296
1297/**
1298 * fcntl_getlease - Enquire what lease is currently active
1299 * @filp: the file
1300 *
1301 * The value returned by this function will be one of
1302 * (if no lease break is pending):
1303 *
1304 * %F_RDLCK to indicate a shared lease is held.
1305 *
1306 * %F_WRLCK to indicate an exclusive lease is held.
1307 *
1308 * %F_UNLCK to indicate no lease is held.
1309 *
1310 * (if a lease break is pending):
1311 *
1312 * %F_RDLCK to indicate an exclusive lease needs to be
1313 * changed to a shared lease (or removed).
1314 *
1315 * %F_UNLCK to indicate the lease needs to be removed.
1316 *
1317 * XXX: sfr & willy disagree over whether F_INPROGRESS
1318 * should be returned to userspace.
1319 */
1320int fcntl_getlease(struct file *filp)
1321{
1322 struct file_lock *fl;
1323 int type = F_UNLCK;
1324
1325 lock_kernel();
Josef "Jeff" Sipek0f7fc9e2006-12-08 02:36:35 -08001326 time_out_leases(filp->f_path.dentry->d_inode);
1327 for (fl = filp->f_path.dentry->d_inode->i_flock; fl && IS_LEASE(fl);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001328 fl = fl->fl_next) {
1329 if (fl->fl_file == filp) {
1330 type = fl->fl_type & ~F_INPROGRESS;
1331 break;
1332 }
1333 }
1334 unlock_kernel();
1335 return type;
1336}
1337
1338/**
Christoph Hellwig0af1a452007-07-31 00:39:22 -07001339 * generic_setlease - sets a lease on an open file
Linus Torvalds1da177e2005-04-16 15:20:36 -07001340 * @filp: file pointer
1341 * @arg: type of lease to obtain
1342 * @flp: input - file_lock to use, output - file_lock inserted
1343 *
1344 * The (input) flp->fl_lmops->fl_break function is required
1345 * by break_lease().
1346 *
1347 * Called with kernel lock held.
1348 */
Christoph Hellwig0af1a452007-07-31 00:39:22 -07001349int generic_setlease(struct file *filp, long arg, struct file_lock **flp)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001350{
KAMBAROV, ZAUR7eaae282005-07-07 17:57:06 -07001351 struct file_lock *fl, **before, **my_before = NULL, *lease;
Pavel Emelyanov85c59582007-09-20 12:45:02 +04001352 struct file_lock *new_fl = NULL;
Josef "Jeff" Sipek0f7fc9e2006-12-08 02:36:35 -08001353 struct dentry *dentry = filp->f_path.dentry;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001354 struct inode *inode = dentry->d_inode;
1355 int error, rdlease_count = 0, wrlease_count = 0;
1356
J. Bruce Fields6d5e8b02007-05-31 17:03:46 -04001357 if ((current->fsuid != inode->i_uid) && !capable(CAP_LEASE))
1358 return -EACCES;
1359 if (!S_ISREG(inode->i_mode))
1360 return -EINVAL;
1361 error = security_file_lock(filp, arg);
1362 if (error)
1363 return error;
1364
Linus Torvalds1da177e2005-04-16 15:20:36 -07001365 time_out_leases(inode);
1366
J. Bruce Fieldsd2ab0b0c2007-06-30 12:40:32 -04001367 BUG_ON(!(*flp)->fl_lmops->fl_break);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001368
KAMBAROV, ZAUR7eaae282005-07-07 17:57:06 -07001369 lease = *flp;
1370
David M. Richter288b2fd2008-04-23 16:29:00 -04001371 if (arg != F_UNLCK) {
David M. Richter19085552008-04-23 16:29:01 -04001372 error = -ENOMEM;
1373 new_fl = locks_alloc_lock();
1374 if (new_fl == NULL)
1375 goto out;
1376
David M. Richter288b2fd2008-04-23 16:29:00 -04001377 error = -EAGAIN;
1378 if ((arg == F_RDLCK) && (atomic_read(&inode->i_writecount) > 0))
1379 goto out;
1380 if ((arg == F_WRLCK)
1381 && ((atomic_read(&dentry->d_count) > 1)
1382 || (atomic_read(&inode->i_count) > 1)))
1383 goto out;
David M. Richter288b2fd2008-04-23 16:29:00 -04001384 }
Pavel Emelyanov85c59582007-09-20 12:45:02 +04001385
Linus Torvalds1da177e2005-04-16 15:20:36 -07001386 /*
1387 * At this point, we know that if there is an exclusive
1388 * lease on this file, then we hold it on this filp
1389 * (otherwise our open of this file would have blocked).
1390 * And if we are trying to acquire an exclusive lease,
1391 * then the file is not open by anyone (including us)
1392 * except for this filp.
1393 */
1394 for (before = &inode->i_flock;
1395 ((fl = *before) != NULL) && IS_LEASE(fl);
1396 before = &fl->fl_next) {
1397 if (lease->fl_lmops->fl_mylease(fl, lease))
1398 my_before = before;
1399 else if (fl->fl_type == (F_INPROGRESS | F_UNLCK))
1400 /*
1401 * Someone is in the process of opening this
1402 * file for writing so we may not take an
1403 * exclusive lease on it.
1404 */
1405 wrlease_count++;
1406 else
1407 rdlease_count++;
1408 }
1409
David M. Richter5fcc60c2008-04-23 16:28:59 -04001410 error = -EAGAIN;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001411 if ((arg == F_RDLCK && (wrlease_count > 0)) ||
1412 (arg == F_WRLCK && ((rdlease_count + wrlease_count) > 0)))
1413 goto out;
1414
1415 if (my_before != NULL) {
Trond Myklebust75dff552006-05-07 23:02:42 -04001416 *flp = *my_before;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001417 error = lease->fl_lmops->fl_change(my_before, arg);
1418 goto out;
1419 }
1420
1421 error = 0;
1422 if (arg == F_UNLCK)
1423 goto out;
1424
1425 error = -EINVAL;
1426 if (!leases_enable)
1427 goto out;
1428
Pavel Emelyanov85c59582007-09-20 12:45:02 +04001429 locks_copy_lock(new_fl, lease);
1430 locks_insert_lock(before, new_fl);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001431
Pavel Emelyanov85c59582007-09-20 12:45:02 +04001432 *flp = new_fl;
1433 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001434
Linus Torvalds1da177e2005-04-16 15:20:36 -07001435out:
Pavel Emelyanov85c59582007-09-20 12:45:02 +04001436 if (new_fl != NULL)
1437 locks_free_lock(new_fl);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001438 return error;
1439}
Christoph Hellwig0af1a452007-07-31 00:39:22 -07001440EXPORT_SYMBOL(generic_setlease);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001441
1442 /**
J. Bruce Fieldsa9933ce2007-06-07 17:09:49 -04001443 * vfs_setlease - sets a lease on an open file
Linus Torvalds1da177e2005-04-16 15:20:36 -07001444 * @filp: file pointer
1445 * @arg: type of lease to obtain
1446 * @lease: file_lock to use
1447 *
1448 * Call this to establish a lease on the file.
J. Bruce Fieldsf9ffed22006-11-14 15:51:40 -05001449 * The (*lease)->fl_lmops->fl_break operation must be set; if not,
1450 * break_lease will oops!
1451 *
1452 * This will call the filesystem's setlease file method, if
1453 * defined. Note that there is no getlease method; instead, the
1454 * filesystem setlease method should call back to setlease() to
1455 * add a lease to the inode's lease list, where fcntl_getlease() can
1456 * find it. Since fcntl_getlease() only reports whether the current
1457 * task holds a lease, a cluster filesystem need only do this for
1458 * leases held by processes on this node.
1459 *
1460 * There is also no break_lease method; filesystems that
1461 * handle their own leases shoud break leases themselves from the
1462 * filesystem's open, create, and (on truncate) setattr methods.
1463 *
1464 * Warning: the only current setlease methods exist only to disable
1465 * leases in certain cases. More vfs changes may be required to
1466 * allow a full filesystem lease implementation.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001467 */
1468
J. Bruce Fieldsa9933ce2007-06-07 17:09:49 -04001469int vfs_setlease(struct file *filp, long arg, struct file_lock **lease)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001470{
Linus Torvalds1da177e2005-04-16 15:20:36 -07001471 int error;
1472
Linus Torvalds1da177e2005-04-16 15:20:36 -07001473 lock_kernel();
J. Bruce Fieldsf9ffed22006-11-14 15:51:40 -05001474 if (filp->f_op && filp->f_op->setlease)
1475 error = filp->f_op->setlease(filp, arg, lease);
1476 else
Christoph Hellwig0af1a452007-07-31 00:39:22 -07001477 error = generic_setlease(filp, arg, lease);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001478 unlock_kernel();
1479
1480 return error;
1481}
J. Bruce Fieldsa9933ce2007-06-07 17:09:49 -04001482EXPORT_SYMBOL_GPL(vfs_setlease);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001483
1484/**
1485 * fcntl_setlease - sets a lease on an open file
1486 * @fd: open file descriptor
1487 * @filp: file pointer
1488 * @arg: type of lease to obtain
1489 *
1490 * Call this fcntl to establish a lease on the file.
1491 * Note that you also need to call %F_SETSIG to
1492 * receive a signal when the lease is broken.
1493 */
1494int fcntl_setlease(unsigned int fd, struct file *filp, long arg)
1495{
1496 struct file_lock fl, *flp = &fl;
David M. Richter9d91cdc2008-04-23 16:29:02 -04001497 struct inode *inode = filp->f_path.dentry->d_inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001498 int error;
1499
Linus Torvalds1da177e2005-04-16 15:20:36 -07001500 locks_init_lock(&fl);
1501 error = lease_init(filp, arg, &fl);
1502 if (error)
1503 return error;
1504
1505 lock_kernel();
1506
J. Bruce Fieldsa9933ce2007-06-07 17:09:49 -04001507 error = vfs_setlease(filp, arg, &flp);
J. Bruce Fieldsdc15ae12005-11-10 19:08:00 -05001508 if (error || arg == F_UNLCK)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001509 goto out_unlock;
1510
1511 error = fasync_helper(fd, filp, 1, &flp->fl_fasync);
1512 if (error < 0) {
J. Bruce Fields6d5e8b02007-05-31 17:03:46 -04001513 /* remove lease just inserted by setlease */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001514 flp->fl_type = F_UNLCK | F_INPROGRESS;
J. Bruce Fields6d5e8b02007-05-31 17:03:46 -04001515 flp->fl_break_time = jiffies - 10;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001516 time_out_leases(inode);
1517 goto out_unlock;
1518 }
1519
Eric W. Biederman609d7fa2006-10-02 02:17:15 -07001520 error = __f_setown(filp, task_pid(current), PIDTYPE_PID, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001521out_unlock:
1522 unlock_kernel();
1523 return error;
1524}
1525
1526/**
1527 * flock_lock_file_wait - Apply a FLOCK-style lock to a file
1528 * @filp: The file to apply the lock to
1529 * @fl: The lock to be applied
1530 *
1531 * Add a FLOCK style lock to a file.
1532 */
1533int flock_lock_file_wait(struct file *filp, struct file_lock *fl)
1534{
1535 int error;
1536 might_sleep();
1537 for (;;) {
1538 error = flock_lock_file(filp, fl);
1539 if ((error != -EAGAIN) || !(fl->fl_flags & FL_SLEEP))
1540 break;
1541 error = wait_event_interruptible(fl->fl_wait, !fl->fl_next);
1542 if (!error)
1543 continue;
1544
1545 locks_delete_block(fl);
1546 break;
1547 }
1548 return error;
1549}
1550
1551EXPORT_SYMBOL(flock_lock_file_wait);
1552
1553/**
1554 * sys_flock: - flock() system call.
1555 * @fd: the file descriptor to lock.
1556 * @cmd: the type of lock to apply.
1557 *
1558 * Apply a %FL_FLOCK style lock to an open file descriptor.
1559 * The @cmd can be one of
1560 *
1561 * %LOCK_SH -- a shared lock.
1562 *
1563 * %LOCK_EX -- an exclusive lock.
1564 *
1565 * %LOCK_UN -- remove an existing lock.
1566 *
1567 * %LOCK_MAND -- a `mandatory' flock. This exists to emulate Windows Share Modes.
1568 *
1569 * %LOCK_MAND can be combined with %LOCK_READ or %LOCK_WRITE to allow other
1570 * processes read and write access respectively.
1571 */
1572asmlinkage long sys_flock(unsigned int fd, unsigned int cmd)
1573{
1574 struct file *filp;
1575 struct file_lock *lock;
1576 int can_sleep, unlock;
1577 int error;
1578
1579 error = -EBADF;
1580 filp = fget(fd);
1581 if (!filp)
1582 goto out;
1583
1584 can_sleep = !(cmd & LOCK_NB);
1585 cmd &= ~LOCK_NB;
1586 unlock = (cmd == LOCK_UN);
1587
1588 if (!unlock && !(cmd & LOCK_MAND) && !(filp->f_mode & 3))
1589 goto out_putf;
1590
1591 error = flock_make_lock(filp, &lock, cmd);
1592 if (error)
1593 goto out_putf;
1594 if (can_sleep)
1595 lock->fl_flags |= FL_SLEEP;
1596
1597 error = security_file_lock(filp, cmd);
1598 if (error)
1599 goto out_free;
1600
1601 if (filp->f_op && filp->f_op->flock)
1602 error = filp->f_op->flock(filp,
1603 (can_sleep) ? F_SETLKW : F_SETLK,
1604 lock);
1605 else
1606 error = flock_lock_file_wait(filp, lock);
1607
1608 out_free:
Trond Myklebust993dfa82006-03-31 02:30:55 -08001609 locks_free_lock(lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001610
1611 out_putf:
1612 fput(filp);
1613 out:
1614 return error;
1615}
1616
J. Bruce Fields3ee17ab2007-02-21 00:58:50 -05001617/**
1618 * vfs_test_lock - test file byte range lock
1619 * @filp: The file to test lock for
J. Bruce Fields6924c552007-05-11 16:22:50 -04001620 * @fl: The lock to test; also used to hold result
J. Bruce Fields3ee17ab2007-02-21 00:58:50 -05001621 *
1622 * Returns -ERRNO on failure. Indicates presence of conflicting lock by
1623 * setting conf->fl_type to something other than F_UNLCK.
1624 */
1625int vfs_test_lock(struct file *filp, struct file_lock *fl)
1626{
1627 if (filp->f_op && filp->f_op->lock)
1628 return filp->f_op->lock(filp, F_GETLK, fl);
1629 posix_test_lock(filp, fl);
1630 return 0;
1631}
1632EXPORT_SYMBOL_GPL(vfs_test_lock);
1633
J. Bruce Fieldsc2fa1b82007-02-20 16:10:11 -05001634static int posix_lock_to_flock(struct flock *flock, struct file_lock *fl)
1635{
1636 flock->l_pid = fl->fl_pid;
1637#if BITS_PER_LONG == 32
1638 /*
1639 * Make sure we can represent the posix lock via
1640 * legacy 32bit flock.
1641 */
1642 if (fl->fl_start > OFFT_OFFSET_MAX)
1643 return -EOVERFLOW;
1644 if (fl->fl_end != OFFSET_MAX && fl->fl_end > OFFT_OFFSET_MAX)
1645 return -EOVERFLOW;
1646#endif
1647 flock->l_start = fl->fl_start;
1648 flock->l_len = fl->fl_end == OFFSET_MAX ? 0 :
1649 fl->fl_end - fl->fl_start + 1;
1650 flock->l_whence = 0;
J. Bruce Fields129a84d2007-05-10 18:38:43 -04001651 flock->l_type = fl->fl_type;
J. Bruce Fieldsc2fa1b82007-02-20 16:10:11 -05001652 return 0;
1653}
1654
1655#if BITS_PER_LONG == 32
1656static void posix_lock_to_flock64(struct flock64 *flock, struct file_lock *fl)
1657{
1658 flock->l_pid = fl->fl_pid;
1659 flock->l_start = fl->fl_start;
1660 flock->l_len = fl->fl_end == OFFSET_MAX ? 0 :
1661 fl->fl_end - fl->fl_start + 1;
1662 flock->l_whence = 0;
1663 flock->l_type = fl->fl_type;
1664}
1665#endif
1666
Linus Torvalds1da177e2005-04-16 15:20:36 -07001667/* Report the first existing lock that would conflict with l.
1668 * This implements the F_GETLK command of fcntl().
1669 */
1670int fcntl_getlk(struct file *filp, struct flock __user *l)
1671{
Marc Eshel9d6a8c52007-02-21 00:55:18 -05001672 struct file_lock file_lock;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001673 struct flock flock;
1674 int error;
1675
1676 error = -EFAULT;
1677 if (copy_from_user(&flock, l, sizeof(flock)))
1678 goto out;
1679 error = -EINVAL;
1680 if ((flock.l_type != F_RDLCK) && (flock.l_type != F_WRLCK))
1681 goto out;
1682
1683 error = flock_to_posix_lock(filp, &file_lock, &flock);
1684 if (error)
1685 goto out;
1686
J. Bruce Fields3ee17ab2007-02-21 00:58:50 -05001687 error = vfs_test_lock(filp, &file_lock);
1688 if (error)
1689 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001690
Marc Eshel9d6a8c52007-02-21 00:55:18 -05001691 flock.l_type = file_lock.fl_type;
1692 if (file_lock.fl_type != F_UNLCK) {
1693 error = posix_lock_to_flock(&flock, &file_lock);
J. Bruce Fieldsc2fa1b82007-02-20 16:10:11 -05001694 if (error)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001695 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001696 }
1697 error = -EFAULT;
1698 if (!copy_to_user(l, &flock, sizeof(flock)))
1699 error = 0;
1700out:
1701 return error;
1702}
1703
Marc Eshel7723ec92007-01-18 15:08:55 -05001704/**
1705 * vfs_lock_file - file byte range lock
1706 * @filp: The file to apply the lock to
1707 * @cmd: type of locking operation (F_SETLK, F_GETLK, etc.)
1708 * @fl: The lock to be applied
Marc Eshel150b3932007-01-18 16:15:35 -05001709 * @conf: Place to return a copy of the conflicting lock, if found.
1710 *
1711 * A caller that doesn't care about the conflicting lock may pass NULL
1712 * as the final argument.
1713 *
1714 * If the filesystem defines a private ->lock() method, then @conf will
1715 * be left unchanged; so a caller that cares should initialize it to
1716 * some acceptable default.
Marc Eshel2beb6612006-12-05 23:31:28 -05001717 *
1718 * To avoid blocking kernel daemons, such as lockd, that need to acquire POSIX
1719 * locks, the ->lock() interface may return asynchronously, before the lock has
1720 * been granted or denied by the underlying filesystem, if (and only if)
1721 * fl_grant is set. Callers expecting ->lock() to return asynchronously
1722 * will only use F_SETLK, not F_SETLKW; they will set FL_SLEEP if (and only if)
1723 * the request is for a blocking lock. When ->lock() does return asynchronously,
1724 * it must return -EINPROGRESS, and call ->fl_grant() when the lock
1725 * request completes.
1726 * If the request is for non-blocking lock the file system should return
1727 * -EINPROGRESS then try to get the lock and call the callback routine with
1728 * the result. If the request timed out the callback routine will return a
1729 * nonzero return code and the file system should release the lock. The file
1730 * system is also responsible to keep a corresponding posix lock when it
1731 * grants a lock so the VFS can find out which locks are locally held and do
1732 * the correct lock cleanup when required.
1733 * The underlying filesystem must not drop the kernel lock or call
1734 * ->fl_grant() before returning to the caller with a -EINPROGRESS
1735 * return code.
Marc Eshel7723ec92007-01-18 15:08:55 -05001736 */
Marc Eshel150b3932007-01-18 16:15:35 -05001737int vfs_lock_file(struct file *filp, unsigned int cmd, struct file_lock *fl, struct file_lock *conf)
Marc Eshel7723ec92007-01-18 15:08:55 -05001738{
1739 if (filp->f_op && filp->f_op->lock)
1740 return filp->f_op->lock(filp, cmd, fl);
1741 else
Marc Eshel150b3932007-01-18 16:15:35 -05001742 return posix_lock_file(filp, fl, conf);
Marc Eshel7723ec92007-01-18 15:08:55 -05001743}
1744EXPORT_SYMBOL_GPL(vfs_lock_file);
1745
Linus Torvalds1da177e2005-04-16 15:20:36 -07001746/* Apply the lock described by l to an open file descriptor.
1747 * This implements both the F_SETLK and F_SETLKW commands of fcntl().
1748 */
Peter Staubachc2936212005-07-27 11:45:09 -07001749int fcntl_setlk(unsigned int fd, struct file *filp, unsigned int cmd,
1750 struct flock __user *l)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001751{
1752 struct file_lock *file_lock = locks_alloc_lock();
1753 struct flock flock;
1754 struct inode *inode;
1755 int error;
1756
1757 if (file_lock == NULL)
1758 return -ENOLCK;
1759
1760 /*
1761 * This might block, so we do it before checking the inode.
1762 */
1763 error = -EFAULT;
1764 if (copy_from_user(&flock, l, sizeof(flock)))
1765 goto out;
1766
Josef "Jeff" Sipek0f7fc9e2006-12-08 02:36:35 -08001767 inode = filp->f_path.dentry->d_inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001768
1769 /* Don't allow mandatory locks on files that may be memory mapped
1770 * and shared.
1771 */
Pavel Emelyanova16877c2007-10-01 14:41:11 -07001772 if (mandatory_lock(inode) && mapping_writably_mapped(filp->f_mapping)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001773 error = -EAGAIN;
1774 goto out;
1775 }
1776
Peter Staubachc2936212005-07-27 11:45:09 -07001777again:
Linus Torvalds1da177e2005-04-16 15:20:36 -07001778 error = flock_to_posix_lock(filp, file_lock, &flock);
1779 if (error)
1780 goto out;
1781 if (cmd == F_SETLKW) {
1782 file_lock->fl_flags |= FL_SLEEP;
1783 }
1784
1785 error = -EBADF;
1786 switch (flock.l_type) {
1787 case F_RDLCK:
1788 if (!(filp->f_mode & FMODE_READ))
1789 goto out;
1790 break;
1791 case F_WRLCK:
1792 if (!(filp->f_mode & FMODE_WRITE))
1793 goto out;
1794 break;
1795 case F_UNLCK:
1796 break;
1797 default:
1798 error = -EINVAL;
1799 goto out;
1800 }
1801
1802 error = security_file_lock(filp, file_lock->fl_type);
1803 if (error)
1804 goto out;
1805
J. Bruce Fields19e729a2008-04-14 15:03:02 -04001806 if (filp->f_op && filp->f_op->lock != NULL)
1807 error = filp->f_op->lock(filp, cmd, file_lock);
1808 else {
1809 for (;;) {
1810 error = posix_lock_file(filp, file_lock, NULL);
1811 if (error != -EAGAIN || cmd == F_SETLK)
1812 break;
1813 error = wait_event_interruptible(file_lock->fl_wait,
1814 !file_lock->fl_next);
1815 if (!error)
1816 continue;
Marc Eshel7723ec92007-01-18 15:08:55 -05001817
J. Bruce Fields19e729a2008-04-14 15:03:02 -04001818 locks_delete_block(file_lock);
1819 break;
1820 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001821 }
1822
Peter Staubachc2936212005-07-27 11:45:09 -07001823 /*
1824 * Attempt to detect a close/fcntl race and recover by
1825 * releasing the lock that was just acquired.
1826 */
1827 if (!error && fcheck(fd) != filp && flock.l_type != F_UNLCK) {
1828 flock.l_type = F_UNLCK;
1829 goto again;
1830 }
1831
1832out:
Linus Torvalds1da177e2005-04-16 15:20:36 -07001833 locks_free_lock(file_lock);
1834 return error;
1835}
1836
1837#if BITS_PER_LONG == 32
1838/* Report the first existing lock that would conflict with l.
1839 * This implements the F_GETLK command of fcntl().
1840 */
1841int fcntl_getlk64(struct file *filp, struct flock64 __user *l)
1842{
Marc Eshel9d6a8c52007-02-21 00:55:18 -05001843 struct file_lock file_lock;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001844 struct flock64 flock;
1845 int error;
1846
1847 error = -EFAULT;
1848 if (copy_from_user(&flock, l, sizeof(flock)))
1849 goto out;
1850 error = -EINVAL;
1851 if ((flock.l_type != F_RDLCK) && (flock.l_type != F_WRLCK))
1852 goto out;
1853
1854 error = flock64_to_posix_lock(filp, &file_lock, &flock);
1855 if (error)
1856 goto out;
1857
J. Bruce Fields3ee17ab2007-02-21 00:58:50 -05001858 error = vfs_test_lock(filp, &file_lock);
1859 if (error)
1860 goto out;
1861
Marc Eshel9d6a8c52007-02-21 00:55:18 -05001862 flock.l_type = file_lock.fl_type;
1863 if (file_lock.fl_type != F_UNLCK)
1864 posix_lock_to_flock64(&flock, &file_lock);
1865
Linus Torvalds1da177e2005-04-16 15:20:36 -07001866 error = -EFAULT;
1867 if (!copy_to_user(l, &flock, sizeof(flock)))
1868 error = 0;
1869
1870out:
1871 return error;
1872}
1873
1874/* Apply the lock described by l to an open file descriptor.
1875 * This implements both the F_SETLK and F_SETLKW commands of fcntl().
1876 */
Peter Staubachc2936212005-07-27 11:45:09 -07001877int fcntl_setlk64(unsigned int fd, struct file *filp, unsigned int cmd,
1878 struct flock64 __user *l)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001879{
1880 struct file_lock *file_lock = locks_alloc_lock();
1881 struct flock64 flock;
1882 struct inode *inode;
1883 int error;
1884
1885 if (file_lock == NULL)
1886 return -ENOLCK;
1887
1888 /*
1889 * This might block, so we do it before checking the inode.
1890 */
1891 error = -EFAULT;
1892 if (copy_from_user(&flock, l, sizeof(flock)))
1893 goto out;
1894
Josef "Jeff" Sipek0f7fc9e2006-12-08 02:36:35 -08001895 inode = filp->f_path.dentry->d_inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001896
1897 /* Don't allow mandatory locks on files that may be memory mapped
1898 * and shared.
1899 */
Pavel Emelyanova16877c2007-10-01 14:41:11 -07001900 if (mandatory_lock(inode) && mapping_writably_mapped(filp->f_mapping)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001901 error = -EAGAIN;
1902 goto out;
1903 }
1904
Peter Staubachc2936212005-07-27 11:45:09 -07001905again:
Linus Torvalds1da177e2005-04-16 15:20:36 -07001906 error = flock64_to_posix_lock(filp, file_lock, &flock);
1907 if (error)
1908 goto out;
1909 if (cmd == F_SETLKW64) {
1910 file_lock->fl_flags |= FL_SLEEP;
1911 }
1912
1913 error = -EBADF;
1914 switch (flock.l_type) {
1915 case F_RDLCK:
1916 if (!(filp->f_mode & FMODE_READ))
1917 goto out;
1918 break;
1919 case F_WRLCK:
1920 if (!(filp->f_mode & FMODE_WRITE))
1921 goto out;
1922 break;
1923 case F_UNLCK:
1924 break;
1925 default:
1926 error = -EINVAL;
1927 goto out;
1928 }
1929
1930 error = security_file_lock(filp, file_lock->fl_type);
1931 if (error)
1932 goto out;
1933
J. Bruce Fields19e729a2008-04-14 15:03:02 -04001934 if (filp->f_op && filp->f_op->lock != NULL)
1935 error = filp->f_op->lock(filp, cmd, file_lock);
1936 else {
1937 for (;;) {
1938 error = posix_lock_file(filp, file_lock, NULL);
1939 if (error != -EAGAIN || cmd == F_SETLK64)
1940 break;
1941 error = wait_event_interruptible(file_lock->fl_wait,
1942 !file_lock->fl_next);
1943 if (!error)
1944 continue;
Marc Eshel7723ec92007-01-18 15:08:55 -05001945
J. Bruce Fields19e729a2008-04-14 15:03:02 -04001946 locks_delete_block(file_lock);
1947 break;
1948 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001949 }
1950
Peter Staubachc2936212005-07-27 11:45:09 -07001951 /*
1952 * Attempt to detect a close/fcntl race and recover by
1953 * releasing the lock that was just acquired.
1954 */
1955 if (!error && fcheck(fd) != filp && flock.l_type != F_UNLCK) {
1956 flock.l_type = F_UNLCK;
1957 goto again;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001958 }
1959
1960out:
1961 locks_free_lock(file_lock);
1962 return error;
1963}
1964#endif /* BITS_PER_LONG == 32 */
1965
1966/*
1967 * This function is called when the file is being removed
1968 * from the task's fd array. POSIX locks belonging to this task
1969 * are deleted at this time.
1970 */
1971void locks_remove_posix(struct file *filp, fl_owner_t owner)
1972{
Miklos Szerediff7b86b2006-06-23 02:05:11 -07001973 struct file_lock lock;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001974
1975 /*
1976 * If there are no locks held on this file, we don't need to call
1977 * posix_lock_file(). Another process could be setting a lock on this
1978 * file at the same time, but we wouldn't remove that lock anyway.
1979 */
Josef "Jeff" Sipek0f7fc9e2006-12-08 02:36:35 -08001980 if (!filp->f_path.dentry->d_inode->i_flock)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001981 return;
1982
1983 lock.fl_type = F_UNLCK;
Miklos Szeredi75e1fcc2006-06-23 02:05:12 -07001984 lock.fl_flags = FL_POSIX | FL_CLOSE;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001985 lock.fl_start = 0;
1986 lock.fl_end = OFFSET_MAX;
1987 lock.fl_owner = owner;
1988 lock.fl_pid = current->tgid;
1989 lock.fl_file = filp;
1990 lock.fl_ops = NULL;
1991 lock.fl_lmops = NULL;
1992
Marc Eshel150b3932007-01-18 16:15:35 -05001993 vfs_lock_file(filp, F_SETLK, &lock, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001994
Linus Torvalds1da177e2005-04-16 15:20:36 -07001995 if (lock.fl_ops && lock.fl_ops->fl_release_private)
1996 lock.fl_ops->fl_release_private(&lock);
1997}
1998
1999EXPORT_SYMBOL(locks_remove_posix);
2000
2001/*
2002 * This function is called on the last close of an open file.
2003 */
2004void locks_remove_flock(struct file *filp)
2005{
Josef "Jeff" Sipek0f7fc9e2006-12-08 02:36:35 -08002006 struct inode * inode = filp->f_path.dentry->d_inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002007 struct file_lock *fl;
2008 struct file_lock **before;
2009
2010 if (!inode->i_flock)
2011 return;
2012
2013 if (filp->f_op && filp->f_op->flock) {
2014 struct file_lock fl = {
2015 .fl_pid = current->tgid,
2016 .fl_file = filp,
2017 .fl_flags = FL_FLOCK,
2018 .fl_type = F_UNLCK,
2019 .fl_end = OFFSET_MAX,
2020 };
2021 filp->f_op->flock(filp, F_SETLKW, &fl);
Trond Myklebust80fec4c2005-06-22 17:16:31 +00002022 if (fl.fl_ops && fl.fl_ops->fl_release_private)
2023 fl.fl_ops->fl_release_private(&fl);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002024 }
2025
2026 lock_kernel();
2027 before = &inode->i_flock;
2028
2029 while ((fl = *before) != NULL) {
2030 if (fl->fl_file == filp) {
Peter Staubachc2936212005-07-27 11:45:09 -07002031 if (IS_FLOCK(fl)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002032 locks_delete_lock(before);
2033 continue;
2034 }
2035 if (IS_LEASE(fl)) {
2036 lease_modify(before, F_UNLCK);
2037 continue;
2038 }
2039 /* What? */
2040 BUG();
2041 }
2042 before = &fl->fl_next;
2043 }
2044 unlock_kernel();
2045}
2046
2047/**
Linus Torvalds1da177e2005-04-16 15:20:36 -07002048 * posix_unblock_lock - stop waiting for a file lock
2049 * @filp: how the file was opened
2050 * @waiter: the lock which was waiting
2051 *
2052 * lockd needs to block waiting for locks.
2053 */
J. Bruce Fields64a318e2006-01-03 09:55:46 +01002054int
Linus Torvalds1da177e2005-04-16 15:20:36 -07002055posix_unblock_lock(struct file *filp, struct file_lock *waiter)
2056{
J. Bruce Fields64a318e2006-01-03 09:55:46 +01002057 int status = 0;
2058
Linus Torvalds1da177e2005-04-16 15:20:36 -07002059 lock_kernel();
J. Bruce Fields5996a292006-01-03 09:55:44 +01002060 if (waiter->fl_next)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002061 __locks_delete_block(waiter);
J. Bruce Fields64a318e2006-01-03 09:55:46 +01002062 else
2063 status = -ENOENT;
J. Bruce Fields5996a292006-01-03 09:55:44 +01002064 unlock_kernel();
J. Bruce Fields64a318e2006-01-03 09:55:46 +01002065 return status;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002066}
2067
2068EXPORT_SYMBOL(posix_unblock_lock);
2069
Marc Eshel9b9d2ab2007-01-18 17:52:58 -05002070/**
2071 * vfs_cancel_lock - file byte range unblock lock
2072 * @filp: The file to apply the unblock to
2073 * @fl: The lock to be unblocked
2074 *
2075 * Used by lock managers to cancel blocked requests
2076 */
2077int vfs_cancel_lock(struct file *filp, struct file_lock *fl)
2078{
2079 if (filp->f_op && filp->f_op->lock)
2080 return filp->f_op->lock(filp, F_CANCELLK, fl);
2081 return 0;
2082}
2083
2084EXPORT_SYMBOL_GPL(vfs_cancel_lock);
2085
Pavel Emelyanov7f8ada92007-10-01 14:41:15 -07002086#ifdef CONFIG_PROC_FS
2087#include <linux/seq_file.h>
2088
2089static void lock_get_status(struct seq_file *f, struct file_lock *fl,
2090 int id, char *pfx)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002091{
2092 struct inode *inode = NULL;
Vitaliy Gusevab1f1612008-01-17 00:07:08 +00002093 unsigned int fl_pid;
2094
2095 if (fl->fl_nspid)
Pavel Emelyanov6c5f3e72008-02-08 04:19:20 -08002096 fl_pid = pid_vnr(fl->fl_nspid);
Vitaliy Gusevab1f1612008-01-17 00:07:08 +00002097 else
2098 fl_pid = fl->fl_pid;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002099
2100 if (fl->fl_file != NULL)
Josef "Jeff" Sipek0f7fc9e2006-12-08 02:36:35 -08002101 inode = fl->fl_file->f_path.dentry->d_inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002102
Pavel Emelyanov7f8ada92007-10-01 14:41:15 -07002103 seq_printf(f, "%d:%s ", id, pfx);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002104 if (IS_POSIX(fl)) {
Pavel Emelyanov7f8ada92007-10-01 14:41:15 -07002105 seq_printf(f, "%6s %s ",
Linus Torvalds1da177e2005-04-16 15:20:36 -07002106 (fl->fl_flags & FL_ACCESS) ? "ACCESS" : "POSIX ",
2107 (inode == NULL) ? "*NOINODE*" :
Pavel Emelyanova16877c2007-10-01 14:41:11 -07002108 mandatory_lock(inode) ? "MANDATORY" : "ADVISORY ");
Linus Torvalds1da177e2005-04-16 15:20:36 -07002109 } else if (IS_FLOCK(fl)) {
2110 if (fl->fl_type & LOCK_MAND) {
Pavel Emelyanov7f8ada92007-10-01 14:41:15 -07002111 seq_printf(f, "FLOCK MSNFS ");
Linus Torvalds1da177e2005-04-16 15:20:36 -07002112 } else {
Pavel Emelyanov7f8ada92007-10-01 14:41:15 -07002113 seq_printf(f, "FLOCK ADVISORY ");
Linus Torvalds1da177e2005-04-16 15:20:36 -07002114 }
2115 } else if (IS_LEASE(fl)) {
Pavel Emelyanov7f8ada92007-10-01 14:41:15 -07002116 seq_printf(f, "LEASE ");
Linus Torvalds1da177e2005-04-16 15:20:36 -07002117 if (fl->fl_type & F_INPROGRESS)
Pavel Emelyanov7f8ada92007-10-01 14:41:15 -07002118 seq_printf(f, "BREAKING ");
Linus Torvalds1da177e2005-04-16 15:20:36 -07002119 else if (fl->fl_file)
Pavel Emelyanov7f8ada92007-10-01 14:41:15 -07002120 seq_printf(f, "ACTIVE ");
Linus Torvalds1da177e2005-04-16 15:20:36 -07002121 else
Pavel Emelyanov7f8ada92007-10-01 14:41:15 -07002122 seq_printf(f, "BREAKER ");
Linus Torvalds1da177e2005-04-16 15:20:36 -07002123 } else {
Pavel Emelyanov7f8ada92007-10-01 14:41:15 -07002124 seq_printf(f, "UNKNOWN UNKNOWN ");
Linus Torvalds1da177e2005-04-16 15:20:36 -07002125 }
2126 if (fl->fl_type & LOCK_MAND) {
Pavel Emelyanov7f8ada92007-10-01 14:41:15 -07002127 seq_printf(f, "%s ",
Linus Torvalds1da177e2005-04-16 15:20:36 -07002128 (fl->fl_type & LOCK_READ)
2129 ? (fl->fl_type & LOCK_WRITE) ? "RW " : "READ "
2130 : (fl->fl_type & LOCK_WRITE) ? "WRITE" : "NONE ");
2131 } else {
Pavel Emelyanov7f8ada92007-10-01 14:41:15 -07002132 seq_printf(f, "%s ",
Linus Torvalds1da177e2005-04-16 15:20:36 -07002133 (fl->fl_type & F_INPROGRESS)
2134 ? (fl->fl_type & F_UNLCK) ? "UNLCK" : "READ "
2135 : (fl->fl_type & F_WRLCK) ? "WRITE" : "READ ");
2136 }
2137 if (inode) {
2138#ifdef WE_CAN_BREAK_LSLK_NOW
Vitaliy Gusevab1f1612008-01-17 00:07:08 +00002139 seq_printf(f, "%d %s:%ld ", fl_pid,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002140 inode->i_sb->s_id, inode->i_ino);
2141#else
2142 /* userspace relies on this representation of dev_t ;-( */
Vitaliy Gusevab1f1612008-01-17 00:07:08 +00002143 seq_printf(f, "%d %02x:%02x:%ld ", fl_pid,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002144 MAJOR(inode->i_sb->s_dev),
2145 MINOR(inode->i_sb->s_dev), inode->i_ino);
2146#endif
2147 } else {
Vitaliy Gusevab1f1612008-01-17 00:07:08 +00002148 seq_printf(f, "%d <none>:0 ", fl_pid);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002149 }
2150 if (IS_POSIX(fl)) {
2151 if (fl->fl_end == OFFSET_MAX)
Pavel Emelyanov7f8ada92007-10-01 14:41:15 -07002152 seq_printf(f, "%Ld EOF\n", fl->fl_start);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002153 else
Pavel Emelyanov7f8ada92007-10-01 14:41:15 -07002154 seq_printf(f, "%Ld %Ld\n", fl->fl_start, fl->fl_end);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002155 } else {
Pavel Emelyanov7f8ada92007-10-01 14:41:15 -07002156 seq_printf(f, "0 EOF\n");
Linus Torvalds1da177e2005-04-16 15:20:36 -07002157 }
2158}
2159
Pavel Emelyanov7f8ada92007-10-01 14:41:15 -07002160static int locks_show(struct seq_file *f, void *v)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002161{
Pavel Emelyanov7f8ada92007-10-01 14:41:15 -07002162 struct file_lock *fl, *bfl;
2163
2164 fl = list_entry(v, struct file_lock, fl_link);
2165
2166 lock_get_status(f, fl, (long)f->private, "");
2167
2168 list_for_each_entry(bfl, &fl->fl_block, fl_block)
2169 lock_get_status(f, bfl, (long)f->private, " ->");
2170
2171 f->private++;
2172 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002173}
2174
Pavel Emelyanov7f8ada92007-10-01 14:41:15 -07002175static void *locks_start(struct seq_file *f, loff_t *pos)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002176{
Linus Torvalds1da177e2005-04-16 15:20:36 -07002177 lock_kernel();
Pavel Emelyanov7f8ada92007-10-01 14:41:15 -07002178 f->private = (void *)1;
2179 return seq_list_start(&file_lock_list, *pos);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002180}
2181
Pavel Emelyanov7f8ada92007-10-01 14:41:15 -07002182static void *locks_next(struct seq_file *f, void *v, loff_t *pos)
2183{
2184 return seq_list_next(v, &file_lock_list, pos);
2185}
2186
2187static void locks_stop(struct seq_file *f, void *v)
2188{
2189 unlock_kernel();
2190}
2191
2192struct seq_operations locks_seq_operations = {
2193 .start = locks_start,
2194 .next = locks_next,
2195 .stop = locks_stop,
2196 .show = locks_show,
2197};
2198#endif
2199
Linus Torvalds1da177e2005-04-16 15:20:36 -07002200/**
2201 * lock_may_read - checks that the region is free of locks
2202 * @inode: the inode that is being read
2203 * @start: the first byte to read
2204 * @len: the number of bytes to read
2205 *
2206 * Emulates Windows locking requirements. Whole-file
2207 * mandatory locks (share modes) can prohibit a read and
2208 * byte-range POSIX locks can prohibit a read if they overlap.
2209 *
2210 * N.B. this function is only ever called
2211 * from knfsd and ownership of locks is never checked.
2212 */
2213int lock_may_read(struct inode *inode, loff_t start, unsigned long len)
2214{
2215 struct file_lock *fl;
2216 int result = 1;
2217 lock_kernel();
2218 for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) {
2219 if (IS_POSIX(fl)) {
2220 if (fl->fl_type == F_RDLCK)
2221 continue;
2222 if ((fl->fl_end < start) || (fl->fl_start > (start + len)))
2223 continue;
2224 } else if (IS_FLOCK(fl)) {
2225 if (!(fl->fl_type & LOCK_MAND))
2226 continue;
2227 if (fl->fl_type & LOCK_READ)
2228 continue;
2229 } else
2230 continue;
2231 result = 0;
2232 break;
2233 }
2234 unlock_kernel();
2235 return result;
2236}
2237
2238EXPORT_SYMBOL(lock_may_read);
2239
2240/**
2241 * lock_may_write - checks that the region is free of locks
2242 * @inode: the inode that is being written
2243 * @start: the first byte to write
2244 * @len: the number of bytes to write
2245 *
2246 * Emulates Windows locking requirements. Whole-file
2247 * mandatory locks (share modes) can prohibit a write and
2248 * byte-range POSIX locks can prohibit a write if they overlap.
2249 *
2250 * N.B. this function is only ever called
2251 * from knfsd and ownership of locks is never checked.
2252 */
2253int lock_may_write(struct inode *inode, loff_t start, unsigned long len)
2254{
2255 struct file_lock *fl;
2256 int result = 1;
2257 lock_kernel();
2258 for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) {
2259 if (IS_POSIX(fl)) {
2260 if ((fl->fl_end < start) || (fl->fl_start > (start + len)))
2261 continue;
2262 } else if (IS_FLOCK(fl)) {
2263 if (!(fl->fl_type & LOCK_MAND))
2264 continue;
2265 if (fl->fl_type & LOCK_WRITE)
2266 continue;
2267 } else
2268 continue;
2269 result = 0;
2270 break;
2271 }
2272 unlock_kernel();
2273 return result;
2274}
2275
2276EXPORT_SYMBOL(lock_may_write);
2277
Linus Torvalds1da177e2005-04-16 15:20:36 -07002278static int __init filelock_init(void)
2279{
2280 filelock_cache = kmem_cache_create("file_lock_cache",
2281 sizeof(struct file_lock), 0, SLAB_PANIC,
Paul Mundt20c2df82007-07-20 10:11:58 +09002282 init_once);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002283 return 0;
2284}
2285
2286core_initcall(filelock_init);