blob: 74c3df99c0e144702d259991ed42c84d93593adf [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>
Al Viro9f3acc32008-04-24 07:44:08 -0400119#include <linux/fdtable.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -0700120#include <linux/fs.h>
121#include <linux/init.h>
122#include <linux/module.h>
123#include <linux/security.h>
124#include <linux/slab.h>
125#include <linux/smp_lock.h>
126#include <linux/syscalls.h>
127#include <linux/time.h>
Dipankar Sarma4fb3a532005-09-16 19:28:13 -0700128#include <linux/rcupdate.h>
Vitaliy Gusevab1f1612008-01-17 00:07:08 +0000129#include <linux/pid_namespace.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -0700130
Linus Torvalds1da177e2005-04-16 15:20:36 -0700131#include <asm/uaccess.h>
132
133#define IS_POSIX(fl) (fl->fl_flags & FL_POSIX)
134#define IS_FLOCK(fl) (fl->fl_flags & FL_FLOCK)
135#define IS_LEASE(fl) (fl->fl_flags & FL_LEASE)
136
137int leases_enable = 1;
138int lease_break_time = 45;
139
140#define for_each_lock(inode, lockp) \
141 for (lockp = &inode->i_flock; *lockp != NULL; lockp = &(*lockp)->fl_next)
142
Christoph Hellwig26bcbf92006-03-20 13:44:40 -0500143static LIST_HEAD(file_lock_list);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700144static LIST_HEAD(blocked_list);
Arnd Bergmann72f98e72010-10-27 21:39:58 +0200145static DEFINE_SPINLOCK(file_lock_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700146
Arnd Bergmannb89f4322010-09-18 15:09:31 +0200147/*
148 * Protects the two list heads above, plus the inode->i_flock list
149 * FIXME: should use a spinlock, once lockd and ceph are ready.
150 */
151void lock_flocks(void)
152{
Arnd Bergmann72f98e72010-10-27 21:39:58 +0200153 spin_lock(&file_lock_lock);
Arnd Bergmannb89f4322010-09-18 15:09:31 +0200154}
155EXPORT_SYMBOL_GPL(lock_flocks);
156
157void unlock_flocks(void)
158{
Arnd Bergmann72f98e72010-10-27 21:39:58 +0200159 spin_unlock(&file_lock_lock);
Arnd Bergmannb89f4322010-09-18 15:09:31 +0200160}
161EXPORT_SYMBOL_GPL(unlock_flocks);
162
Christoph Lametere18b8902006-12-06 20:33:20 -0800163static struct kmem_cache *filelock_cache __read_mostly;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700164
165/* Allocate an empty lock structure. */
Arnd Bergmannc5b1f0d2010-10-27 15:46:08 +0200166struct file_lock *locks_alloc_lock(void)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700167{
Christoph Lametere94b1762006-12-06 20:33:17 -0800168 return kmem_cache_alloc(filelock_cache, GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700169}
Arnd Bergmannc5b1f0d2010-10-27 15:46:08 +0200170EXPORT_SYMBOL_GPL(locks_alloc_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700171
Felix Blyakhera9e61e22009-03-31 15:12:56 -0500172void locks_release_private(struct file_lock *fl)
Trond Myklebust47831f32006-03-20 13:44:05 -0500173{
174 if (fl->fl_ops) {
175 if (fl->fl_ops->fl_release_private)
176 fl->fl_ops->fl_release_private(fl);
177 fl->fl_ops = NULL;
178 }
179 if (fl->fl_lmops) {
180 if (fl->fl_lmops->fl_release_private)
181 fl->fl_lmops->fl_release_private(fl);
182 fl->fl_lmops = NULL;
183 }
184
185}
Felix Blyakhera9e61e22009-03-31 15:12:56 -0500186EXPORT_SYMBOL_GPL(locks_release_private);
Trond Myklebust47831f32006-03-20 13:44:05 -0500187
Linus Torvalds1da177e2005-04-16 15:20:36 -0700188/* Free a lock which is not in use. */
Matt Mackall33443c42006-01-08 01:05:22 -0800189static void locks_free_lock(struct file_lock *fl)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700190{
Miklos Szeredi5ce29642006-03-31 02:30:29 -0800191 BUG_ON(waitqueue_active(&fl->fl_wait));
192 BUG_ON(!list_empty(&fl->fl_block));
193 BUG_ON(!list_empty(&fl->fl_link));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700194
Trond Myklebust47831f32006-03-20 13:44:05 -0500195 locks_release_private(fl);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700196 kmem_cache_free(filelock_cache, fl);
197}
198
199void locks_init_lock(struct file_lock *fl)
200{
201 INIT_LIST_HEAD(&fl->fl_link);
202 INIT_LIST_HEAD(&fl->fl_block);
203 init_waitqueue_head(&fl->fl_wait);
204 fl->fl_next = NULL;
205 fl->fl_fasync = NULL;
206 fl->fl_owner = NULL;
207 fl->fl_pid = 0;
Vitaliy Gusevab1f1612008-01-17 00:07:08 +0000208 fl->fl_nspid = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700209 fl->fl_file = NULL;
210 fl->fl_flags = 0;
211 fl->fl_type = 0;
212 fl->fl_start = fl->fl_end = 0;
213 fl->fl_ops = NULL;
214 fl->fl_lmops = NULL;
215}
216
217EXPORT_SYMBOL(locks_init_lock);
218
219/*
220 * Initialises the fields of the file lock which are invariant for
221 * free file_locks.
222 */
Alexey Dobriyan51cc5062008-07-25 19:45:34 -0700223static void init_once(void *foo)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700224{
225 struct file_lock *lock = (struct file_lock *) foo;
226
Linus Torvalds1da177e2005-04-16 15:20:36 -0700227 locks_init_lock(lock);
228}
229
Trond Myklebust47831f32006-03-20 13:44:05 -0500230static void locks_copy_private(struct file_lock *new, struct file_lock *fl)
231{
232 if (fl->fl_ops) {
233 if (fl->fl_ops->fl_copy_lock)
234 fl->fl_ops->fl_copy_lock(new, fl);
235 new->fl_ops = fl->fl_ops;
236 }
237 if (fl->fl_lmops) {
238 if (fl->fl_lmops->fl_copy_lock)
239 fl->fl_lmops->fl_copy_lock(new, fl);
240 new->fl_lmops = fl->fl_lmops;
241 }
242}
243
Linus Torvalds1da177e2005-04-16 15:20:36 -0700244/*
245 * Initialize a new lock from an existing file_lock structure.
246 */
J. Bruce Fields1a747ee2008-04-24 10:08:22 -0400247void __locks_copy_lock(struct file_lock *new, const struct file_lock *fl)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700248{
249 new->fl_owner = fl->fl_owner;
250 new->fl_pid = fl->fl_pid;
Trond Myklebust09969052006-03-20 13:44:38 -0500251 new->fl_file = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700252 new->fl_flags = fl->fl_flags;
253 new->fl_type = fl->fl_type;
254 new->fl_start = fl->fl_start;
255 new->fl_end = fl->fl_end;
Trond Myklebust09969052006-03-20 13:44:38 -0500256 new->fl_ops = NULL;
257 new->fl_lmops = NULL;
258}
Roland Dreier3dd7b712008-04-25 15:32:51 -0700259EXPORT_SYMBOL(__locks_copy_lock);
Trond Myklebust09969052006-03-20 13:44:38 -0500260
261void locks_copy_lock(struct file_lock *new, struct file_lock *fl)
262{
263 locks_release_private(new);
264
265 __locks_copy_lock(new, fl);
266 new->fl_file = fl->fl_file;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700267 new->fl_ops = fl->fl_ops;
268 new->fl_lmops = fl->fl_lmops;
Trond Myklebust47831f32006-03-20 13:44:05 -0500269
270 locks_copy_private(new, fl);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700271}
272
273EXPORT_SYMBOL(locks_copy_lock);
274
275static inline int flock_translate_cmd(int cmd) {
276 if (cmd & LOCK_MAND)
277 return cmd & (LOCK_MAND | LOCK_RW);
278 switch (cmd) {
279 case LOCK_SH:
280 return F_RDLCK;
281 case LOCK_EX:
282 return F_WRLCK;
283 case LOCK_UN:
284 return F_UNLCK;
285 }
286 return -EINVAL;
287}
288
289/* Fill in a file_lock structure with an appropriate FLOCK lock. */
290static int flock_make_lock(struct file *filp, struct file_lock **lock,
291 unsigned int cmd)
292{
293 struct file_lock *fl;
294 int type = flock_translate_cmd(cmd);
295 if (type < 0)
296 return type;
297
298 fl = locks_alloc_lock();
299 if (fl == NULL)
300 return -ENOMEM;
301
302 fl->fl_file = filp;
303 fl->fl_pid = current->tgid;
304 fl->fl_flags = FL_FLOCK;
305 fl->fl_type = type;
306 fl->fl_end = OFFSET_MAX;
307
308 *lock = fl;
309 return 0;
310}
311
312static int assign_type(struct file_lock *fl, int type)
313{
314 switch (type) {
315 case F_RDLCK:
316 case F_WRLCK:
317 case F_UNLCK:
318 fl->fl_type = type;
319 break;
320 default:
321 return -EINVAL;
322 }
323 return 0;
324}
325
326/* Verify a "struct flock" and copy it to a "struct file_lock" as a POSIX
327 * style lock.
328 */
329static int flock_to_posix_lock(struct file *filp, struct file_lock *fl,
330 struct flock *l)
331{
332 off_t start, end;
333
334 switch (l->l_whence) {
Josef 'Jeff' Sipekf5579f82006-09-30 23:27:35 -0700335 case SEEK_SET:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700336 start = 0;
337 break;
Josef 'Jeff' Sipekf5579f82006-09-30 23:27:35 -0700338 case SEEK_CUR:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700339 start = filp->f_pos;
340 break;
Josef 'Jeff' Sipekf5579f82006-09-30 23:27:35 -0700341 case SEEK_END:
Josef "Jeff" Sipek0f7fc9e2006-12-08 02:36:35 -0800342 start = i_size_read(filp->f_path.dentry->d_inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700343 break;
344 default:
345 return -EINVAL;
346 }
347
348 /* POSIX-1996 leaves the case l->l_len < 0 undefined;
349 POSIX-2001 defines it. */
350 start += l->l_start;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700351 if (start < 0)
352 return -EINVAL;
Trond Myklebust4c780a42005-10-18 14:20:21 -0700353 fl->fl_end = OFFSET_MAX;
354 if (l->l_len > 0) {
355 end = start + l->l_len - 1;
356 fl->fl_end = end;
357 } else if (l->l_len < 0) {
358 end = start - 1;
359 fl->fl_end = end;
360 start += l->l_len;
361 if (start < 0)
362 return -EINVAL;
363 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700364 fl->fl_start = start; /* we record the absolute position */
Trond Myklebust4c780a42005-10-18 14:20:21 -0700365 if (fl->fl_end < fl->fl_start)
366 return -EOVERFLOW;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700367
368 fl->fl_owner = current->files;
369 fl->fl_pid = current->tgid;
370 fl->fl_file = filp;
371 fl->fl_flags = FL_POSIX;
372 fl->fl_ops = NULL;
373 fl->fl_lmops = NULL;
374
375 return assign_type(fl, l->l_type);
376}
377
378#if BITS_PER_LONG == 32
379static int flock64_to_posix_lock(struct file *filp, struct file_lock *fl,
380 struct flock64 *l)
381{
382 loff_t start;
383
384 switch (l->l_whence) {
Josef 'Jeff' Sipekf5579f82006-09-30 23:27:35 -0700385 case SEEK_SET:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700386 start = 0;
387 break;
Josef 'Jeff' Sipekf5579f82006-09-30 23:27:35 -0700388 case SEEK_CUR:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700389 start = filp->f_pos;
390 break;
Josef 'Jeff' Sipekf5579f82006-09-30 23:27:35 -0700391 case SEEK_END:
Josef "Jeff" Sipek0f7fc9e2006-12-08 02:36:35 -0800392 start = i_size_read(filp->f_path.dentry->d_inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700393 break;
394 default:
395 return -EINVAL;
396 }
397
Trond Myklebust4c780a42005-10-18 14:20:21 -0700398 start += l->l_start;
399 if (start < 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700400 return -EINVAL;
Trond Myklebust4c780a42005-10-18 14:20:21 -0700401 fl->fl_end = OFFSET_MAX;
402 if (l->l_len > 0) {
403 fl->fl_end = start + l->l_len - 1;
404 } else if (l->l_len < 0) {
405 fl->fl_end = start - 1;
406 start += l->l_len;
407 if (start < 0)
408 return -EINVAL;
409 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700410 fl->fl_start = start; /* we record the absolute position */
Trond Myklebust4c780a42005-10-18 14:20:21 -0700411 if (fl->fl_end < fl->fl_start)
412 return -EOVERFLOW;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700413
414 fl->fl_owner = current->files;
415 fl->fl_pid = current->tgid;
416 fl->fl_file = filp;
417 fl->fl_flags = FL_POSIX;
418 fl->fl_ops = NULL;
419 fl->fl_lmops = NULL;
420
421 switch (l->l_type) {
422 case F_RDLCK:
423 case F_WRLCK:
424 case F_UNLCK:
425 fl->fl_type = l->l_type;
426 break;
427 default:
428 return -EINVAL;
429 }
430
431 return (0);
432}
433#endif
434
435/* default lease lock manager operations */
436static void lease_break_callback(struct file_lock *fl)
437{
438 kill_fasync(&fl->fl_fasync, SIGIO, POLL_MSG);
439}
440
441static void lease_release_private_callback(struct file_lock *fl)
442{
443 if (!fl->fl_file)
444 return;
445
446 f_delown(fl->fl_file);
447 fl->fl_file->f_owner.signum = 0;
448}
449
Adrian Bunk75c96f82005-05-05 16:16:09 -0700450static int lease_mylease_callback(struct file_lock *fl, struct file_lock *try)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700451{
452 return fl->fl_file == try->fl_file;
453}
454
Alexey Dobriyan7b021962009-09-21 17:01:12 -0700455static const struct lock_manager_operations lease_manager_ops = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700456 .fl_break = lease_break_callback,
457 .fl_release_private = lease_release_private_callback,
458 .fl_mylease = lease_mylease_callback,
459 .fl_change = lease_modify,
460};
461
462/*
463 * Initialize a lease, use the default lock manager operations
464 */
465static int lease_init(struct file *filp, int type, struct file_lock *fl)
466 {
Trond Myklebust75dff552006-05-07 23:02:42 -0400467 if (assign_type(fl, type) != 0)
468 return -EINVAL;
469
Linus Torvalds1da177e2005-04-16 15:20:36 -0700470 fl->fl_owner = current->files;
471 fl->fl_pid = current->tgid;
472
473 fl->fl_file = filp;
474 fl->fl_flags = FL_LEASE;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700475 fl->fl_start = 0;
476 fl->fl_end = OFFSET_MAX;
477 fl->fl_ops = NULL;
478 fl->fl_lmops = &lease_manager_ops;
479 return 0;
480}
481
482/* Allocate a file_lock initialised to this type of lease */
J. Bruce Fieldse32b8ee2007-03-01 14:34:35 -0500483static struct file_lock *lease_alloc(struct file *filp, int type)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700484{
485 struct file_lock *fl = locks_alloc_lock();
Trond Myklebust75dff552006-05-07 23:02:42 -0400486 int error = -ENOMEM;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700487
488 if (fl == NULL)
J. Bruce Fieldse32b8ee2007-03-01 14:34:35 -0500489 return ERR_PTR(error);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700490
491 error = lease_init(filp, type, fl);
Trond Myklebust75dff552006-05-07 23:02:42 -0400492 if (error) {
493 locks_free_lock(fl);
J. Bruce Fieldse32b8ee2007-03-01 14:34:35 -0500494 return ERR_PTR(error);
Trond Myklebust75dff552006-05-07 23:02:42 -0400495 }
J. Bruce Fieldse32b8ee2007-03-01 14:34:35 -0500496 return fl;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700497}
498
499/* Check if two locks overlap each other.
500 */
501static inline int locks_overlap(struct file_lock *fl1, struct file_lock *fl2)
502{
503 return ((fl1->fl_end >= fl2->fl_start) &&
504 (fl2->fl_end >= fl1->fl_start));
505}
506
507/*
508 * Check whether two locks have the same owner.
509 */
Matt Mackall33443c42006-01-08 01:05:22 -0800510static int posix_same_owner(struct file_lock *fl1, struct file_lock *fl2)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700511{
512 if (fl1->fl_lmops && fl1->fl_lmops->fl_compare_owner)
513 return fl2->fl_lmops == fl1->fl_lmops &&
514 fl1->fl_lmops->fl_compare_owner(fl1, fl2);
515 return fl1->fl_owner == fl2->fl_owner;
516}
517
518/* Remove waiter from blocker's block list.
519 * When blocker ends up pointing to itself then the list is empty.
520 */
Matt Mackall33443c42006-01-08 01:05:22 -0800521static void __locks_delete_block(struct file_lock *waiter)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700522{
523 list_del_init(&waiter->fl_block);
524 list_del_init(&waiter->fl_link);
525 waiter->fl_next = NULL;
526}
527
528/*
529 */
530static void locks_delete_block(struct file_lock *waiter)
531{
Arnd Bergmannb89f4322010-09-18 15:09:31 +0200532 lock_flocks();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700533 __locks_delete_block(waiter);
Arnd Bergmannb89f4322010-09-18 15:09:31 +0200534 unlock_flocks();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700535}
536
537/* Insert waiter into blocker's block list.
538 * We use a circular list so that processes can be easily woken up in
539 * the order they blocked. The documentation doesn't require this but
540 * it seems like the reasonable thing to do.
541 */
542static void locks_insert_block(struct file_lock *blocker,
543 struct file_lock *waiter)
544{
J. Bruce Fields6dc0fe82006-03-26 01:37:24 -0800545 BUG_ON(!list_empty(&waiter->fl_block));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700546 list_add_tail(&waiter->fl_block, &blocker->fl_block);
547 waiter->fl_next = blocker;
548 if (IS_POSIX(blocker))
549 list_add(&waiter->fl_link, &blocked_list);
550}
551
552/* Wake up processes blocked waiting for blocker.
553 * If told to wait then schedule the processes until the block list
554 * is empty, otherwise empty the block list ourselves.
555 */
556static void locks_wake_up_blocks(struct file_lock *blocker)
557{
558 while (!list_empty(&blocker->fl_block)) {
Pavel Emelyanovf0c1cd02007-09-19 16:44:07 +0400559 struct file_lock *waiter;
560
561 waiter = list_first_entry(&blocker->fl_block,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700562 struct file_lock, fl_block);
563 __locks_delete_block(waiter);
564 if (waiter->fl_lmops && waiter->fl_lmops->fl_notify)
565 waiter->fl_lmops->fl_notify(waiter);
566 else
567 wake_up(&waiter->fl_wait);
568 }
569}
570
571/* Insert file lock fl into an inode's lock list at the position indicated
572 * by pos. At the same time add the lock to the global file lock list.
573 */
574static void locks_insert_lock(struct file_lock **pos, struct file_lock *fl)
575{
576 list_add(&fl->fl_link, &file_lock_list);
577
Vitaliy Gusevab1f1612008-01-17 00:07:08 +0000578 fl->fl_nspid = get_pid(task_tgid(current));
579
Linus Torvalds1da177e2005-04-16 15:20:36 -0700580 /* insert into file's list */
581 fl->fl_next = *pos;
582 *pos = fl;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700583}
584
585/*
586 * Delete a lock and then free it.
587 * Wake up processes that are blocked waiting for this lock,
588 * notify the FS that the lock has been cleared and
589 * finally free the lock.
590 */
591static void locks_delete_lock(struct file_lock **thisfl_p)
592{
593 struct file_lock *fl = *thisfl_p;
594
595 *thisfl_p = fl->fl_next;
596 fl->fl_next = NULL;
597 list_del_init(&fl->fl_link);
598
599 fasync_helper(0, fl->fl_file, 0, &fl->fl_fasync);
600 if (fl->fl_fasync != NULL) {
601 printk(KERN_ERR "locks_delete_lock: fasync == %p\n", fl->fl_fasync);
602 fl->fl_fasync = NULL;
603 }
604
Vitaliy Gusevab1f1612008-01-17 00:07:08 +0000605 if (fl->fl_nspid) {
606 put_pid(fl->fl_nspid);
607 fl->fl_nspid = NULL;
608 }
609
Linus Torvalds1da177e2005-04-16 15:20:36 -0700610 locks_wake_up_blocks(fl);
611 locks_free_lock(fl);
612}
613
614/* Determine if lock sys_fl blocks lock caller_fl. Common functionality
615 * checks for shared/exclusive status of overlapping locks.
616 */
617static int locks_conflict(struct file_lock *caller_fl, struct file_lock *sys_fl)
618{
619 if (sys_fl->fl_type == F_WRLCK)
620 return 1;
621 if (caller_fl->fl_type == F_WRLCK)
622 return 1;
623 return 0;
624}
625
626/* Determine if lock sys_fl blocks lock caller_fl. POSIX specific
627 * checking before calling the locks_conflict().
628 */
629static int posix_locks_conflict(struct file_lock *caller_fl, struct file_lock *sys_fl)
630{
631 /* POSIX locks owned by the same process do not conflict with
632 * each other.
633 */
634 if (!IS_POSIX(sys_fl) || posix_same_owner(caller_fl, sys_fl))
635 return (0);
636
637 /* Check whether they overlap */
638 if (!locks_overlap(caller_fl, sys_fl))
639 return 0;
640
641 return (locks_conflict(caller_fl, sys_fl));
642}
643
644/* Determine if lock sys_fl blocks lock caller_fl. FLOCK specific
645 * checking before calling the locks_conflict().
646 */
647static int flock_locks_conflict(struct file_lock *caller_fl, struct file_lock *sys_fl)
648{
649 /* FLOCK locks referring to the same filp do not conflict with
650 * each other.
651 */
652 if (!IS_FLOCK(sys_fl) || (caller_fl->fl_file == sys_fl->fl_file))
653 return (0);
654 if ((caller_fl->fl_type & LOCK_MAND) || (sys_fl->fl_type & LOCK_MAND))
655 return 0;
656
657 return (locks_conflict(caller_fl, sys_fl));
658}
659
J. Bruce Fields6d34ac12007-05-11 16:09:32 -0400660void
Marc Eshel9d6a8c52007-02-21 00:55:18 -0500661posix_test_lock(struct file *filp, struct file_lock *fl)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700662{
663 struct file_lock *cfl;
664
Arnd Bergmannb89f4322010-09-18 15:09:31 +0200665 lock_flocks();
Josef "Jeff" Sipek0f7fc9e2006-12-08 02:36:35 -0800666 for (cfl = filp->f_path.dentry->d_inode->i_flock; cfl; cfl = cfl->fl_next) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700667 if (!IS_POSIX(cfl))
668 continue;
J. Bruce Fieldsb842e242007-05-10 19:02:07 -0400669 if (posix_locks_conflict(fl, cfl))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700670 break;
671 }
Vitaliy Gusevab1f1612008-01-17 00:07:08 +0000672 if (cfl) {
Marc Eshel9d6a8c52007-02-21 00:55:18 -0500673 __locks_copy_lock(fl, cfl);
Vitaliy Gusevab1f1612008-01-17 00:07:08 +0000674 if (cfl->fl_nspid)
Pavel Emelyanov6c5f3e72008-02-08 04:19:20 -0800675 fl->fl_pid = pid_vnr(cfl->fl_nspid);
Vitaliy Gusevab1f1612008-01-17 00:07:08 +0000676 } else
J. Bruce Fields129a84d2007-05-10 18:38:43 -0400677 fl->fl_type = F_UNLCK;
Arnd Bergmannb89f4322010-09-18 15:09:31 +0200678 unlock_flocks();
J. Bruce Fields6d34ac12007-05-11 16:09:32 -0400679 return;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700680}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700681EXPORT_SYMBOL(posix_test_lock);
682
J. Bruce Fieldsb5331842007-10-26 18:05:40 -0400683/*
684 * Deadlock detection:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700685 *
J. Bruce Fieldsb5331842007-10-26 18:05:40 -0400686 * We attempt to detect deadlocks that are due purely to posix file
687 * locks.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700688 *
J. Bruce Fieldsb5331842007-10-26 18:05:40 -0400689 * We assume that a task can be waiting for at most one lock at a time.
690 * So for any acquired lock, the process holding that lock may be
691 * waiting on at most one other lock. That lock in turns may be held by
692 * someone waiting for at most one other lock. Given a requested lock
693 * caller_fl which is about to wait for a conflicting lock block_fl, we
694 * follow this chain of waiters to ensure we are not about to create a
695 * cycle.
J. Bruce Fields97855b42007-10-30 11:20:02 -0400696 *
J. Bruce Fieldsb5331842007-10-26 18:05:40 -0400697 * Since we do this before we ever put a process to sleep on a lock, we
698 * are ensured that there is never a cycle; that is what guarantees that
699 * the while() loop in posix_locks_deadlock() eventually completes.
700 *
701 * Note: the above assumption may not be true when handling lock
702 * requests from a broken NFS client. It may also fail in the presence
703 * of tasks (such as posix threads) sharing the same open file table.
704 *
705 * To handle those cases, we just bail out after a few iterations.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700706 */
J. Bruce Fields97855b42007-10-30 11:20:02 -0400707
708#define MAX_DEADLK_ITERATIONS 10
709
J. Bruce Fieldsb5331842007-10-26 18:05:40 -0400710/* Find a lock that the owner of the given block_fl is blocking on. */
711static struct file_lock *what_owner_is_waiting_for(struct file_lock *block_fl)
712{
713 struct file_lock *fl;
714
715 list_for_each_entry(fl, &blocked_list, fl_link) {
716 if (posix_same_owner(fl, block_fl))
717 return fl->fl_next;
718 }
719 return NULL;
720}
721
Adrian Bunkb0904e12006-06-23 02:05:13 -0700722static int posix_locks_deadlock(struct file_lock *caller_fl,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700723 struct file_lock *block_fl)
724{
J. Bruce Fields97855b42007-10-30 11:20:02 -0400725 int i = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700726
J. Bruce Fieldsb5331842007-10-26 18:05:40 -0400727 while ((block_fl = what_owner_is_waiting_for(block_fl))) {
728 if (i++ > MAX_DEADLK_ITERATIONS)
729 return 0;
730 if (posix_same_owner(caller_fl, block_fl))
731 return 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700732 }
733 return 0;
734}
735
Linus Torvalds1da177e2005-04-16 15:20:36 -0700736/* Try to create a FLOCK lock on filp. We always insert new FLOCK locks
J. Bruce Fields02888f42007-09-12 15:45:07 -0400737 * after any leases, but before any posix locks.
Trond Myklebustf475ae92006-06-29 16:38:32 -0400738 *
739 * Note that if called with an FL_EXISTS argument, the caller may determine
740 * whether or not a lock was successfully freed by testing the return
741 * value for -ENOENT.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700742 */
Trond Myklebust993dfa82006-03-31 02:30:55 -0800743static int flock_lock_file(struct file *filp, struct file_lock *request)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700744{
Trond Myklebust993dfa82006-03-31 02:30:55 -0800745 struct file_lock *new_fl = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700746 struct file_lock **before;
Josef "Jeff" Sipek0f7fc9e2006-12-08 02:36:35 -0800747 struct inode * inode = filp->f_path.dentry->d_inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700748 int error = 0;
749 int found = 0;
750
Arnd Bergmannb89f4322010-09-18 15:09:31 +0200751 if (!(request->fl_flags & FL_ACCESS) && (request->fl_type != F_UNLCK)) {
752 new_fl = locks_alloc_lock();
753 if (!new_fl)
754 return -ENOMEM;
755 }
756
757 lock_flocks();
Trond Myklebustf07f18d2006-06-29 16:38:37 -0400758 if (request->fl_flags & FL_ACCESS)
759 goto find_conflict;
Pavel Emelyanov84d535a2007-09-11 16:38:13 +0400760
Linus Torvalds1da177e2005-04-16 15:20:36 -0700761 for_each_lock(inode, before) {
762 struct file_lock *fl = *before;
763 if (IS_POSIX(fl))
764 break;
765 if (IS_LEASE(fl))
766 continue;
767 if (filp != fl->fl_file)
768 continue;
Trond Myklebust993dfa82006-03-31 02:30:55 -0800769 if (request->fl_type == fl->fl_type)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700770 goto out;
771 found = 1;
772 locks_delete_lock(before);
773 break;
774 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700775
Trond Myklebustf475ae92006-06-29 16:38:32 -0400776 if (request->fl_type == F_UNLCK) {
777 if ((request->fl_flags & FL_EXISTS) && !found)
778 error = -ENOENT;
Trond Myklebust993dfa82006-03-31 02:30:55 -0800779 goto out;
Trond Myklebustf475ae92006-06-29 16:38:32 -0400780 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700781
782 /*
783 * If a higher-priority process was blocked on the old file lock,
784 * give it the opportunity to lock the file.
785 */
Arnd Bergmannb89f4322010-09-18 15:09:31 +0200786 if (found) {
787 unlock_flocks();
Frederic Weisbeckerdef01bc2009-07-16 15:44:29 +0200788 cond_resched();
Arnd Bergmannb89f4322010-09-18 15:09:31 +0200789 lock_flocks();
790 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700791
Trond Myklebustf07f18d2006-06-29 16:38:37 -0400792find_conflict:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700793 for_each_lock(inode, before) {
794 struct file_lock *fl = *before;
795 if (IS_POSIX(fl))
796 break;
797 if (IS_LEASE(fl))
798 continue;
Trond Myklebust993dfa82006-03-31 02:30:55 -0800799 if (!flock_locks_conflict(request, fl))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700800 continue;
801 error = -EAGAIN;
Miklos Szeredibde74e42008-07-25 01:48:57 -0700802 if (!(request->fl_flags & FL_SLEEP))
803 goto out;
804 error = FILE_LOCK_DEFERRED;
805 locks_insert_block(fl, request);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700806 goto out;
807 }
Trond Myklebustf07f18d2006-06-29 16:38:37 -0400808 if (request->fl_flags & FL_ACCESS)
809 goto out;
Trond Myklebust993dfa82006-03-31 02:30:55 -0800810 locks_copy_lock(new_fl, request);
Pavel Emelyanov0e2f6db2007-09-11 15:24:01 -0700811 locks_insert_lock(before, new_fl);
Trond Myklebust993dfa82006-03-31 02:30:55 -0800812 new_fl = NULL;
Kirill Korotaev9cedc192006-06-14 17:59:35 +0400813 error = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700814
815out:
Arnd Bergmannb89f4322010-09-18 15:09:31 +0200816 unlock_flocks();
Trond Myklebust993dfa82006-03-31 02:30:55 -0800817 if (new_fl)
818 locks_free_lock(new_fl);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700819 return error;
820}
821
Marc Eshel150b3932007-01-18 16:15:35 -0500822static int __posix_lock_file(struct inode *inode, struct file_lock *request, struct file_lock *conflock)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700823{
824 struct file_lock *fl;
Miklos Szeredi39005d02006-06-23 02:05:10 -0700825 struct file_lock *new_fl = NULL;
826 struct file_lock *new_fl2 = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700827 struct file_lock *left = NULL;
828 struct file_lock *right = NULL;
829 struct file_lock **before;
830 int error, added = 0;
831
832 /*
833 * We may need two file_lock structures for this operation,
834 * so we get them in advance to avoid races.
Miklos Szeredi39005d02006-06-23 02:05:10 -0700835 *
836 * In some cases we can be sure, that no new locks will be needed
Linus Torvalds1da177e2005-04-16 15:20:36 -0700837 */
Miklos Szeredi39005d02006-06-23 02:05:10 -0700838 if (!(request->fl_flags & FL_ACCESS) &&
839 (request->fl_type != F_UNLCK ||
840 request->fl_start != 0 || request->fl_end != OFFSET_MAX)) {
841 new_fl = locks_alloc_lock();
842 new_fl2 = locks_alloc_lock();
843 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700844
Arnd Bergmannb89f4322010-09-18 15:09:31 +0200845 lock_flocks();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700846 if (request->fl_type != F_UNLCK) {
847 for_each_lock(inode, before) {
J. Bruce Fields526985b2006-11-14 16:54:36 -0500848 fl = *before;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700849 if (!IS_POSIX(fl))
850 continue;
851 if (!posix_locks_conflict(request, fl))
852 continue;
Andy Adamson5842add2006-03-26 01:37:26 -0800853 if (conflock)
J. Bruce Fields1a747ee2008-04-24 10:08:22 -0400854 __locks_copy_lock(conflock, fl);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700855 error = -EAGAIN;
856 if (!(request->fl_flags & FL_SLEEP))
857 goto out;
858 error = -EDEADLK;
859 if (posix_locks_deadlock(request, fl))
860 goto out;
Miklos Szeredibde74e42008-07-25 01:48:57 -0700861 error = FILE_LOCK_DEFERRED;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700862 locks_insert_block(fl, request);
863 goto out;
864 }
865 }
866
867 /* If we're just looking for a conflict, we're done. */
868 error = 0;
869 if (request->fl_flags & FL_ACCESS)
870 goto out;
871
Linus Torvalds1da177e2005-04-16 15:20:36 -0700872 /*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700873 * Find the first old lock with the same owner as the new lock.
874 */
875
876 before = &inode->i_flock;
877
878 /* First skip locks owned by other processes. */
879 while ((fl = *before) && (!IS_POSIX(fl) ||
880 !posix_same_owner(request, fl))) {
881 before = &fl->fl_next;
882 }
883
884 /* Process locks with this owner. */
885 while ((fl = *before) && posix_same_owner(request, fl)) {
886 /* Detect adjacent or overlapping regions (if same lock type)
887 */
888 if (request->fl_type == fl->fl_type) {
Olaf Kirch449231d2005-08-25 16:25:35 -0700889 /* In all comparisons of start vs end, use
890 * "start - 1" rather than "end + 1". If end
891 * is OFFSET_MAX, end + 1 will become negative.
892 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700893 if (fl->fl_end < request->fl_start - 1)
894 goto next_lock;
895 /* If the next lock in the list has entirely bigger
896 * addresses than the new one, insert the lock here.
897 */
Olaf Kirch449231d2005-08-25 16:25:35 -0700898 if (fl->fl_start - 1 > request->fl_end)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700899 break;
900
901 /* If we come here, the new and old lock are of the
902 * same type and adjacent or overlapping. Make one
903 * lock yielding from the lower start address of both
904 * locks to the higher end address.
905 */
906 if (fl->fl_start > request->fl_start)
907 fl->fl_start = request->fl_start;
908 else
909 request->fl_start = fl->fl_start;
910 if (fl->fl_end < request->fl_end)
911 fl->fl_end = request->fl_end;
912 else
913 request->fl_end = fl->fl_end;
914 if (added) {
915 locks_delete_lock(before);
916 continue;
917 }
918 request = fl;
919 added = 1;
920 }
921 else {
922 /* Processing for different lock types is a bit
923 * more complex.
924 */
925 if (fl->fl_end < request->fl_start)
926 goto next_lock;
927 if (fl->fl_start > request->fl_end)
928 break;
929 if (request->fl_type == F_UNLCK)
930 added = 1;
931 if (fl->fl_start < request->fl_start)
932 left = fl;
933 /* If the next lock in the list has a higher end
934 * address than the new one, insert the new one here.
935 */
936 if (fl->fl_end > request->fl_end) {
937 right = fl;
938 break;
939 }
940 if (fl->fl_start >= request->fl_start) {
941 /* The new lock completely replaces an old
942 * one (This may happen several times).
943 */
944 if (added) {
945 locks_delete_lock(before);
946 continue;
947 }
948 /* Replace the old lock with the new one.
949 * Wake up anybody waiting for the old one,
950 * as the change in lock type might satisfy
951 * their needs.
952 */
953 locks_wake_up_blocks(fl);
954 fl->fl_start = request->fl_start;
955 fl->fl_end = request->fl_end;
956 fl->fl_type = request->fl_type;
Trond Myklebust47831f32006-03-20 13:44:05 -0500957 locks_release_private(fl);
958 locks_copy_private(fl, request);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700959 request = fl;
960 added = 1;
961 }
962 }
963 /* Go on to next lock.
964 */
965 next_lock:
966 before = &fl->fl_next;
967 }
968
Miklos Szeredi0d9a4902006-06-23 02:05:09 -0700969 /*
970 * The above code only modifies existing locks in case of
971 * merging or replacing. If new lock(s) need to be inserted
972 * all modifications are done bellow this, so it's safe yet to
973 * bail out.
974 */
975 error = -ENOLCK; /* "no luck" */
976 if (right && left == right && !new_fl2)
977 goto out;
978
Linus Torvalds1da177e2005-04-16 15:20:36 -0700979 error = 0;
980 if (!added) {
Trond Myklebustf475ae92006-06-29 16:38:32 -0400981 if (request->fl_type == F_UNLCK) {
982 if (request->fl_flags & FL_EXISTS)
983 error = -ENOENT;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700984 goto out;
Trond Myklebustf475ae92006-06-29 16:38:32 -0400985 }
Miklos Szeredi0d9a4902006-06-23 02:05:09 -0700986
987 if (!new_fl) {
988 error = -ENOLCK;
989 goto out;
990 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700991 locks_copy_lock(new_fl, request);
992 locks_insert_lock(before, new_fl);
993 new_fl = NULL;
994 }
995 if (right) {
996 if (left == right) {
997 /* The new lock breaks the old one in two pieces,
998 * so we have to use the second new lock.
999 */
1000 left = new_fl2;
1001 new_fl2 = NULL;
1002 locks_copy_lock(left, right);
1003 locks_insert_lock(before, left);
1004 }
1005 right->fl_start = request->fl_end + 1;
1006 locks_wake_up_blocks(right);
1007 }
1008 if (left) {
1009 left->fl_end = request->fl_start - 1;
1010 locks_wake_up_blocks(left);
1011 }
1012 out:
Arnd Bergmannb89f4322010-09-18 15:09:31 +02001013 unlock_flocks();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001014 /*
1015 * Free any unused locks.
1016 */
1017 if (new_fl)
1018 locks_free_lock(new_fl);
1019 if (new_fl2)
1020 locks_free_lock(new_fl2);
1021 return error;
1022}
1023
1024/**
1025 * posix_lock_file - Apply a POSIX-style lock to a file
1026 * @filp: The file to apply the lock to
1027 * @fl: The lock to be applied
Marc Eshel150b3932007-01-18 16:15:35 -05001028 * @conflock: Place to return a copy of the conflicting lock, if found.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001029 *
1030 * Add a POSIX style lock to a file.
1031 * We merge adjacent & overlapping locks whenever possible.
1032 * POSIX locks are sorted by owner task, then by starting address
Trond Myklebustf475ae92006-06-29 16:38:32 -04001033 *
1034 * Note that if called with an FL_EXISTS argument, the caller may determine
1035 * whether or not a lock was successfully freed by testing the return
1036 * value for -ENOENT.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001037 */
Marc Eshel150b3932007-01-18 16:15:35 -05001038int posix_lock_file(struct file *filp, struct file_lock *fl,
Andy Adamson5842add2006-03-26 01:37:26 -08001039 struct file_lock *conflock)
1040{
Marc Eshel150b3932007-01-18 16:15:35 -05001041 return __posix_lock_file(filp->f_path.dentry->d_inode, fl, conflock);
Andy Adamson5842add2006-03-26 01:37:26 -08001042}
Marc Eshel150b3932007-01-18 16:15:35 -05001043EXPORT_SYMBOL(posix_lock_file);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001044
1045/**
1046 * posix_lock_file_wait - Apply a POSIX-style lock to a file
1047 * @filp: The file to apply the lock to
1048 * @fl: The lock to be applied
1049 *
1050 * Add a POSIX style lock to a file.
1051 * We merge adjacent & overlapping locks whenever possible.
1052 * POSIX locks are sorted by owner task, then by starting address
1053 */
1054int posix_lock_file_wait(struct file *filp, struct file_lock *fl)
1055{
1056 int error;
1057 might_sleep ();
1058 for (;;) {
Marc Eshel150b3932007-01-18 16:15:35 -05001059 error = posix_lock_file(filp, fl, NULL);
Miklos Szeredibde74e42008-07-25 01:48:57 -07001060 if (error != FILE_LOCK_DEFERRED)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001061 break;
1062 error = wait_event_interruptible(fl->fl_wait, !fl->fl_next);
1063 if (!error)
1064 continue;
1065
1066 locks_delete_block(fl);
1067 break;
1068 }
1069 return error;
1070}
1071EXPORT_SYMBOL(posix_lock_file_wait);
1072
1073/**
1074 * locks_mandatory_locked - Check for an active lock
1075 * @inode: the file to check
1076 *
1077 * Searches the inode's list of locks to find any POSIX locks which conflict.
1078 * This function is called from locks_verify_locked() only.
1079 */
1080int locks_mandatory_locked(struct inode *inode)
1081{
1082 fl_owner_t owner = current->files;
1083 struct file_lock *fl;
1084
1085 /*
1086 * Search the lock list for this inode for any POSIX locks.
1087 */
Arnd Bergmannb89f4322010-09-18 15:09:31 +02001088 lock_flocks();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001089 for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) {
1090 if (!IS_POSIX(fl))
1091 continue;
1092 if (fl->fl_owner != owner)
1093 break;
1094 }
Arnd Bergmannb89f4322010-09-18 15:09:31 +02001095 unlock_flocks();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001096 return fl ? -EAGAIN : 0;
1097}
1098
1099/**
1100 * locks_mandatory_area - Check for a conflicting lock
1101 * @read_write: %FLOCK_VERIFY_WRITE for exclusive access, %FLOCK_VERIFY_READ
1102 * for shared
1103 * @inode: the file to check
1104 * @filp: how the file was opened (if it was)
1105 * @offset: start of area to check
1106 * @count: length of area to check
1107 *
1108 * Searches the inode's list of locks to find any POSIX locks which conflict.
1109 * This function is called from rw_verify_area() and
1110 * locks_verify_truncate().
1111 */
1112int locks_mandatory_area(int read_write, struct inode *inode,
1113 struct file *filp, loff_t offset,
1114 size_t count)
1115{
1116 struct file_lock fl;
1117 int error;
1118
1119 locks_init_lock(&fl);
1120 fl.fl_owner = current->files;
1121 fl.fl_pid = current->tgid;
1122 fl.fl_file = filp;
1123 fl.fl_flags = FL_POSIX | FL_ACCESS;
1124 if (filp && !(filp->f_flags & O_NONBLOCK))
1125 fl.fl_flags |= FL_SLEEP;
1126 fl.fl_type = (read_write == FLOCK_VERIFY_WRITE) ? F_WRLCK : F_RDLCK;
1127 fl.fl_start = offset;
1128 fl.fl_end = offset + count - 1;
1129
1130 for (;;) {
Marc Eshel150b3932007-01-18 16:15:35 -05001131 error = __posix_lock_file(inode, &fl, NULL);
Miklos Szeredibde74e42008-07-25 01:48:57 -07001132 if (error != FILE_LOCK_DEFERRED)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001133 break;
1134 error = wait_event_interruptible(fl.fl_wait, !fl.fl_next);
1135 if (!error) {
1136 /*
1137 * If we've been sleeping someone might have
1138 * changed the permissions behind our back.
1139 */
Pavel Emelyanova16877c2007-10-01 14:41:11 -07001140 if (__mandatory_lock(inode))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001141 continue;
1142 }
1143
1144 locks_delete_block(&fl);
1145 break;
1146 }
1147
1148 return error;
1149}
1150
1151EXPORT_SYMBOL(locks_mandatory_area);
1152
1153/* We already had a lease on this file; just change its type */
1154int lease_modify(struct file_lock **before, int arg)
1155{
1156 struct file_lock *fl = *before;
1157 int error = assign_type(fl, arg);
1158
1159 if (error)
1160 return error;
1161 locks_wake_up_blocks(fl);
1162 if (arg == F_UNLCK)
1163 locks_delete_lock(before);
1164 return 0;
1165}
1166
1167EXPORT_SYMBOL(lease_modify);
1168
1169static void time_out_leases(struct inode *inode)
1170{
1171 struct file_lock **before;
1172 struct file_lock *fl;
1173
1174 before = &inode->i_flock;
1175 while ((fl = *before) && IS_LEASE(fl) && (fl->fl_type & F_INPROGRESS)) {
1176 if ((fl->fl_break_time == 0)
1177 || time_before(jiffies, fl->fl_break_time)) {
1178 before = &fl->fl_next;
1179 continue;
1180 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001181 lease_modify(before, fl->fl_type & ~F_INPROGRESS);
1182 if (fl == *before) /* lease_modify may have freed fl */
1183 before = &fl->fl_next;
1184 }
1185}
1186
1187/**
1188 * __break_lease - revoke all outstanding leases on file
1189 * @inode: the inode of the file to return
1190 * @mode: the open mode (read or write)
1191 *
david m. richter87250dd2007-05-09 16:10:27 -04001192 * break_lease (inlined for speed) has checked there already is at least
1193 * some kind of lock (maybe a lease) on this file. Leases are broken on
1194 * a call to open() or truncate(). This function can sleep unless you
Linus Torvalds1da177e2005-04-16 15:20:36 -07001195 * specified %O_NONBLOCK to your open().
1196 */
1197int __break_lease(struct inode *inode, unsigned int mode)
1198{
1199 int error = 0, future;
1200 struct file_lock *new_fl, *flock;
1201 struct file_lock *fl;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001202 unsigned long break_time;
1203 int i_have_this_lease = 0;
Al Viro8737c932009-12-24 06:47:55 -05001204 int want_write = (mode & O_ACCMODE) != O_RDONLY;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001205
Al Viro8737c932009-12-24 06:47:55 -05001206 new_fl = lease_alloc(NULL, want_write ? F_WRLCK : F_RDLCK);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001207
Arnd Bergmannb89f4322010-09-18 15:09:31 +02001208 lock_flocks();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001209
1210 time_out_leases(inode);
1211
1212 flock = inode->i_flock;
1213 if ((flock == NULL) || !IS_LEASE(flock))
1214 goto out;
1215
1216 for (fl = flock; fl && IS_LEASE(fl); fl = fl->fl_next)
1217 if (fl->fl_owner == current->files)
1218 i_have_this_lease = 1;
1219
Al Viro8737c932009-12-24 06:47:55 -05001220 if (want_write) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001221 /* If we want write access, we have to revoke any lease. */
1222 future = F_UNLCK | F_INPROGRESS;
1223 } else if (flock->fl_type & F_INPROGRESS) {
1224 /* If the lease is already being broken, we just leave it */
1225 future = flock->fl_type;
1226 } else if (flock->fl_type & F_WRLCK) {
1227 /* Downgrade the exclusive lease to a read-only lease. */
1228 future = F_RDLCK | F_INPROGRESS;
1229 } else {
1230 /* the existing lease was read-only, so we can read too. */
1231 goto out;
1232 }
1233
J. Bruce Fieldse32b8ee2007-03-01 14:34:35 -05001234 if (IS_ERR(new_fl) && !i_have_this_lease
1235 && ((mode & O_NONBLOCK) == 0)) {
1236 error = PTR_ERR(new_fl);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001237 goto out;
1238 }
1239
1240 break_time = 0;
1241 if (lease_break_time > 0) {
1242 break_time = jiffies + lease_break_time * HZ;
1243 if (break_time == 0)
1244 break_time++; /* so that 0 means no break time */
1245 }
1246
1247 for (fl = flock; fl && IS_LEASE(fl); fl = fl->fl_next) {
1248 if (fl->fl_type != future) {
1249 fl->fl_type = future;
1250 fl->fl_break_time = break_time;
1251 /* lease must have lmops break callback */
1252 fl->fl_lmops->fl_break(fl);
1253 }
1254 }
1255
1256 if (i_have_this_lease || (mode & O_NONBLOCK)) {
1257 error = -EWOULDBLOCK;
1258 goto out;
1259 }
1260
1261restart:
1262 break_time = flock->fl_break_time;
1263 if (break_time != 0) {
1264 break_time -= jiffies;
1265 if (break_time == 0)
1266 break_time++;
1267 }
Matthew Wilcox4321e012008-01-14 21:28:30 -07001268 locks_insert_block(flock, new_fl);
Arnd Bergmannb89f4322010-09-18 15:09:31 +02001269 unlock_flocks();
Matthew Wilcox4321e012008-01-14 21:28:30 -07001270 error = wait_event_interruptible_timeout(new_fl->fl_wait,
1271 !new_fl->fl_next, break_time);
Arnd Bergmannb89f4322010-09-18 15:09:31 +02001272 lock_flocks();
Matthew Wilcox4321e012008-01-14 21:28:30 -07001273 __locks_delete_block(new_fl);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001274 if (error >= 0) {
1275 if (error == 0)
1276 time_out_leases(inode);
1277 /* Wait for the next lease that has not been broken yet */
1278 for (flock = inode->i_flock; flock && IS_LEASE(flock);
1279 flock = flock->fl_next) {
1280 if (flock->fl_type & F_INPROGRESS)
1281 goto restart;
1282 }
1283 error = 0;
1284 }
1285
1286out:
Arnd Bergmannb89f4322010-09-18 15:09:31 +02001287 unlock_flocks();
J. Bruce Fieldse32b8ee2007-03-01 14:34:35 -05001288 if (!IS_ERR(new_fl))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001289 locks_free_lock(new_fl);
1290 return error;
1291}
1292
1293EXPORT_SYMBOL(__break_lease);
1294
1295/**
Randy Dunlapa6b91912008-03-19 17:01:00 -07001296 * lease_get_mtime - get the last modified time of an inode
Linus Torvalds1da177e2005-04-16 15:20:36 -07001297 * @inode: the inode
1298 * @time: pointer to a timespec which will contain the last modified time
1299 *
1300 * This is to force NFS clients to flush their caches for files with
1301 * exclusive leases. The justification is that if someone has an
Randy Dunlapa6b91912008-03-19 17:01:00 -07001302 * exclusive lease, then they could be modifying it.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001303 */
1304void lease_get_mtime(struct inode *inode, struct timespec *time)
1305{
1306 struct file_lock *flock = inode->i_flock;
1307 if (flock && IS_LEASE(flock) && (flock->fl_type & F_WRLCK))
1308 *time = current_fs_time(inode->i_sb);
1309 else
1310 *time = inode->i_mtime;
1311}
1312
1313EXPORT_SYMBOL(lease_get_mtime);
1314
1315/**
1316 * fcntl_getlease - Enquire what lease is currently active
1317 * @filp: the file
1318 *
1319 * The value returned by this function will be one of
1320 * (if no lease break is pending):
1321 *
1322 * %F_RDLCK to indicate a shared lease is held.
1323 *
1324 * %F_WRLCK to indicate an exclusive lease is held.
1325 *
1326 * %F_UNLCK to indicate no lease is held.
1327 *
1328 * (if a lease break is pending):
1329 *
1330 * %F_RDLCK to indicate an exclusive lease needs to be
1331 * changed to a shared lease (or removed).
1332 *
1333 * %F_UNLCK to indicate the lease needs to be removed.
1334 *
1335 * XXX: sfr & willy disagree over whether F_INPROGRESS
1336 * should be returned to userspace.
1337 */
1338int fcntl_getlease(struct file *filp)
1339{
1340 struct file_lock *fl;
1341 int type = F_UNLCK;
1342
Arnd Bergmannb89f4322010-09-18 15:09:31 +02001343 lock_flocks();
Josef "Jeff" Sipek0f7fc9e2006-12-08 02:36:35 -08001344 time_out_leases(filp->f_path.dentry->d_inode);
1345 for (fl = filp->f_path.dentry->d_inode->i_flock; fl && IS_LEASE(fl);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001346 fl = fl->fl_next) {
1347 if (fl->fl_file == filp) {
1348 type = fl->fl_type & ~F_INPROGRESS;
1349 break;
1350 }
1351 }
Arnd Bergmannb89f4322010-09-18 15:09:31 +02001352 unlock_flocks();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001353 return type;
1354}
1355
1356/**
Christoph Hellwig0af1a452007-07-31 00:39:22 -07001357 * generic_setlease - sets a lease on an open file
Linus Torvalds1da177e2005-04-16 15:20:36 -07001358 * @filp: file pointer
1359 * @arg: type of lease to obtain
1360 * @flp: input - file_lock to use, output - file_lock inserted
1361 *
1362 * The (input) flp->fl_lmops->fl_break function is required
1363 * by break_lease().
1364 *
Arnd Bergmannb89f4322010-09-18 15:09:31 +02001365 * Called with file_lock_lock held.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001366 */
Christoph Hellwig0af1a452007-07-31 00:39:22 -07001367int generic_setlease(struct file *filp, long arg, struct file_lock **flp)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001368{
KAMBAROV, ZAUR7eaae282005-07-07 17:57:06 -07001369 struct file_lock *fl, **before, **my_before = NULL, *lease;
Josef "Jeff" Sipek0f7fc9e2006-12-08 02:36:35 -08001370 struct dentry *dentry = filp->f_path.dentry;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001371 struct inode *inode = dentry->d_inode;
1372 int error, rdlease_count = 0, wrlease_count = 0;
1373
David Howellsda9592e2008-11-14 10:39:05 +11001374 if ((current_fsuid() != inode->i_uid) && !capable(CAP_LEASE))
J. Bruce Fields6d5e8b02007-05-31 17:03:46 -04001375 return -EACCES;
1376 if (!S_ISREG(inode->i_mode))
1377 return -EINVAL;
1378 error = security_file_lock(filp, arg);
1379 if (error)
1380 return error;
1381
Linus Torvalds1da177e2005-04-16 15:20:36 -07001382 time_out_leases(inode);
1383
J. Bruce Fieldsd2ab0b0c2007-06-30 12:40:32 -04001384 BUG_ON(!(*flp)->fl_lmops->fl_break);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001385
KAMBAROV, ZAUR7eaae282005-07-07 17:57:06 -07001386 lease = *flp;
1387
David M. Richter288b2fd2008-04-23 16:29:00 -04001388 if (arg != F_UNLCK) {
1389 error = -EAGAIN;
1390 if ((arg == F_RDLCK) && (atomic_read(&inode->i_writecount) > 0))
1391 goto out;
1392 if ((arg == F_WRLCK)
1393 && ((atomic_read(&dentry->d_count) > 1)
1394 || (atomic_read(&inode->i_count) > 1)))
1395 goto out;
David M. Richter288b2fd2008-04-23 16:29:00 -04001396 }
Pavel Emelyanov85c59582007-09-20 12:45:02 +04001397
Linus Torvalds1da177e2005-04-16 15:20:36 -07001398 /*
1399 * At this point, we know that if there is an exclusive
1400 * lease on this file, then we hold it on this filp
1401 * (otherwise our open of this file would have blocked).
1402 * And if we are trying to acquire an exclusive lease,
1403 * then the file is not open by anyone (including us)
1404 * except for this filp.
1405 */
1406 for (before = &inode->i_flock;
1407 ((fl = *before) != NULL) && IS_LEASE(fl);
1408 before = &fl->fl_next) {
1409 if (lease->fl_lmops->fl_mylease(fl, lease))
1410 my_before = before;
1411 else if (fl->fl_type == (F_INPROGRESS | F_UNLCK))
1412 /*
1413 * Someone is in the process of opening this
1414 * file for writing so we may not take an
1415 * exclusive lease on it.
1416 */
1417 wrlease_count++;
1418 else
1419 rdlease_count++;
1420 }
1421
David M. Richter5fcc60c2008-04-23 16:28:59 -04001422 error = -EAGAIN;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001423 if ((arg == F_RDLCK && (wrlease_count > 0)) ||
1424 (arg == F_WRLCK && ((rdlease_count + wrlease_count) > 0)))
1425 goto out;
1426
1427 if (my_before != NULL) {
Trond Myklebust75dff552006-05-07 23:02:42 -04001428 *flp = *my_before;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001429 error = lease->fl_lmops->fl_change(my_before, arg);
1430 goto out;
1431 }
1432
Linus Torvalds1da177e2005-04-16 15:20:36 -07001433 if (arg == F_UNLCK)
1434 goto out;
1435
1436 error = -EINVAL;
1437 if (!leases_enable)
1438 goto out;
1439
Arnd Bergmannc5b1f0d2010-10-27 15:46:08 +02001440 locks_insert_lock(before, lease);
Pavel Emelyanov85c59582007-09-20 12:45:02 +04001441 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001442
Linus Torvalds1da177e2005-04-16 15:20:36 -07001443out:
Arnd Bergmannc5b1f0d2010-10-27 15:46:08 +02001444 locks_free_lock(lease);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001445 return error;
1446}
Christoph Hellwig0af1a452007-07-31 00:39:22 -07001447EXPORT_SYMBOL(generic_setlease);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001448
Arnd Bergmannb89f4322010-09-18 15:09:31 +02001449static int __vfs_setlease(struct file *filp, long arg, struct file_lock **lease)
1450{
1451 if (filp->f_op && filp->f_op->setlease)
1452 return filp->f_op->setlease(filp, arg, lease);
1453 else
1454 return generic_setlease(filp, arg, lease);
1455}
1456
1457/**
J. Bruce Fieldsa9933ce2007-06-07 17:09:49 -04001458 * vfs_setlease - sets a lease on an open file
Linus Torvalds1da177e2005-04-16 15:20:36 -07001459 * @filp: file pointer
1460 * @arg: type of lease to obtain
1461 * @lease: file_lock to use
1462 *
1463 * Call this to establish a lease on the file.
J. Bruce Fieldsf9ffed22006-11-14 15:51:40 -05001464 * The (*lease)->fl_lmops->fl_break operation must be set; if not,
1465 * break_lease will oops!
1466 *
1467 * This will call the filesystem's setlease file method, if
1468 * defined. Note that there is no getlease method; instead, the
1469 * filesystem setlease method should call back to setlease() to
1470 * add a lease to the inode's lease list, where fcntl_getlease() can
1471 * find it. Since fcntl_getlease() only reports whether the current
1472 * task holds a lease, a cluster filesystem need only do this for
1473 * leases held by processes on this node.
1474 *
1475 * There is also no break_lease method; filesystems that
Adam Buchbinderc9404c92009-12-18 15:40:42 -05001476 * handle their own leases should break leases themselves from the
J. Bruce Fieldsf9ffed22006-11-14 15:51:40 -05001477 * filesystem's open, create, and (on truncate) setattr methods.
1478 *
1479 * Warning: the only current setlease methods exist only to disable
1480 * leases in certain cases. More vfs changes may be required to
1481 * allow a full filesystem lease implementation.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001482 */
1483
J. Bruce Fieldsa9933ce2007-06-07 17:09:49 -04001484int vfs_setlease(struct file *filp, long arg, struct file_lock **lease)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001485{
Linus Torvalds1da177e2005-04-16 15:20:36 -07001486 int error;
1487
Arnd Bergmannb89f4322010-09-18 15:09:31 +02001488 lock_flocks();
1489 error = __vfs_setlease(filp, arg, lease);
1490 unlock_flocks();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001491
1492 return error;
1493}
J. Bruce Fieldsa9933ce2007-06-07 17:09:49 -04001494EXPORT_SYMBOL_GPL(vfs_setlease);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001495
1496/**
1497 * fcntl_setlease - sets a lease on an open file
1498 * @fd: open file descriptor
1499 * @filp: file pointer
1500 * @arg: type of lease to obtain
1501 *
1502 * Call this fcntl to establish a lease on the file.
1503 * Note that you also need to call %F_SETSIG to
1504 * receive a signal when the lease is broken.
1505 */
1506int fcntl_setlease(unsigned int fd, struct file *filp, long arg)
1507{
Arnd Bergmannc5b1f0d2010-10-27 15:46:08 +02001508 struct file_lock *fl;
Linus Torvaldsf7347ce2010-10-27 12:38:12 -04001509 struct fasync_struct *new;
David M. Richter9d91cdc2008-04-23 16:29:02 -04001510 struct inode *inode = filp->f_path.dentry->d_inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001511 int error;
1512
Arnd Bergmannc5b1f0d2010-10-27 15:46:08 +02001513 fl = lease_alloc(filp, arg);
1514 if (IS_ERR(fl))
1515 return PTR_ERR(fl);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001516
Linus Torvaldsf7347ce2010-10-27 12:38:12 -04001517 new = fasync_alloc();
1518 if (!new) {
1519 locks_free_lock(fl);
1520 return -ENOMEM;
1521 }
Arnd Bergmannb89f4322010-09-18 15:09:31 +02001522 lock_flocks();
Arnd Bergmannc5b1f0d2010-10-27 15:46:08 +02001523 error = __vfs_setlease(filp, arg, &fl);
J. Bruce Fieldsdc15ae12005-11-10 19:08:00 -05001524 if (error || arg == F_UNLCK)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001525 goto out_unlock;
1526
Linus Torvaldsf7347ce2010-10-27 12:38:12 -04001527 /*
1528 * fasync_insert_entry() returns the old entry if any.
1529 * If there was no old entry, then it used 'new' and
1530 * inserted it into the fasync list. Clear new so that
1531 * we don't release it here.
1532 */
1533 if (!fasync_insert_entry(fd, filp, &fl->fl_fasync, new))
1534 new = NULL;
1535
Linus Torvalds1da177e2005-04-16 15:20:36 -07001536 if (error < 0) {
J. Bruce Fields6d5e8b02007-05-31 17:03:46 -04001537 /* remove lease just inserted by setlease */
Arnd Bergmannc5b1f0d2010-10-27 15:46:08 +02001538 fl->fl_type = F_UNLCK | F_INPROGRESS;
1539 fl->fl_break_time = jiffies - 10;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001540 time_out_leases(inode);
1541 goto out_unlock;
1542 }
1543
Eric W. Biederman609d7fa2006-10-02 02:17:15 -07001544 error = __f_setown(filp, task_pid(current), PIDTYPE_PID, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001545out_unlock:
Arnd Bergmannb89f4322010-09-18 15:09:31 +02001546 unlock_flocks();
Linus Torvaldsf7347ce2010-10-27 12:38:12 -04001547 if (new)
1548 fasync_free(new);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001549 return error;
1550}
1551
1552/**
1553 * flock_lock_file_wait - Apply a FLOCK-style lock to a file
1554 * @filp: The file to apply the lock to
1555 * @fl: The lock to be applied
1556 *
1557 * Add a FLOCK style lock to a file.
1558 */
1559int flock_lock_file_wait(struct file *filp, struct file_lock *fl)
1560{
1561 int error;
1562 might_sleep();
1563 for (;;) {
1564 error = flock_lock_file(filp, fl);
Miklos Szeredibde74e42008-07-25 01:48:57 -07001565 if (error != FILE_LOCK_DEFERRED)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001566 break;
1567 error = wait_event_interruptible(fl->fl_wait, !fl->fl_next);
1568 if (!error)
1569 continue;
1570
1571 locks_delete_block(fl);
1572 break;
1573 }
1574 return error;
1575}
1576
1577EXPORT_SYMBOL(flock_lock_file_wait);
1578
1579/**
1580 * sys_flock: - flock() system call.
1581 * @fd: the file descriptor to lock.
1582 * @cmd: the type of lock to apply.
1583 *
1584 * Apply a %FL_FLOCK style lock to an open file descriptor.
1585 * The @cmd can be one of
1586 *
1587 * %LOCK_SH -- a shared lock.
1588 *
1589 * %LOCK_EX -- an exclusive lock.
1590 *
1591 * %LOCK_UN -- remove an existing lock.
1592 *
1593 * %LOCK_MAND -- a `mandatory' flock. This exists to emulate Windows Share Modes.
1594 *
1595 * %LOCK_MAND can be combined with %LOCK_READ or %LOCK_WRITE to allow other
1596 * processes read and write access respectively.
1597 */
Heiko Carstens002c8972009-01-14 14:14:18 +01001598SYSCALL_DEFINE2(flock, unsigned int, fd, unsigned int, cmd)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001599{
1600 struct file *filp;
1601 struct file_lock *lock;
1602 int can_sleep, unlock;
1603 int error;
1604
1605 error = -EBADF;
1606 filp = fget(fd);
1607 if (!filp)
1608 goto out;
1609
1610 can_sleep = !(cmd & LOCK_NB);
1611 cmd &= ~LOCK_NB;
1612 unlock = (cmd == LOCK_UN);
1613
Al Viroaeb5d722008-09-02 15:28:45 -04001614 if (!unlock && !(cmd & LOCK_MAND) &&
1615 !(filp->f_mode & (FMODE_READ|FMODE_WRITE)))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001616 goto out_putf;
1617
1618 error = flock_make_lock(filp, &lock, cmd);
1619 if (error)
1620 goto out_putf;
1621 if (can_sleep)
1622 lock->fl_flags |= FL_SLEEP;
1623
Sten Spans713c0ec2009-07-16 09:41:39 +02001624 error = security_file_lock(filp, lock->fl_type);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001625 if (error)
1626 goto out_free;
1627
1628 if (filp->f_op && filp->f_op->flock)
1629 error = filp->f_op->flock(filp,
1630 (can_sleep) ? F_SETLKW : F_SETLK,
1631 lock);
1632 else
1633 error = flock_lock_file_wait(filp, lock);
1634
1635 out_free:
Trond Myklebust993dfa82006-03-31 02:30:55 -08001636 locks_free_lock(lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001637
1638 out_putf:
1639 fput(filp);
1640 out:
1641 return error;
1642}
1643
J. Bruce Fields3ee17ab2007-02-21 00:58:50 -05001644/**
1645 * vfs_test_lock - test file byte range lock
1646 * @filp: The file to test lock for
J. Bruce Fields6924c552007-05-11 16:22:50 -04001647 * @fl: The lock to test; also used to hold result
J. Bruce Fields3ee17ab2007-02-21 00:58:50 -05001648 *
1649 * Returns -ERRNO on failure. Indicates presence of conflicting lock by
1650 * setting conf->fl_type to something other than F_UNLCK.
1651 */
1652int vfs_test_lock(struct file *filp, struct file_lock *fl)
1653{
1654 if (filp->f_op && filp->f_op->lock)
1655 return filp->f_op->lock(filp, F_GETLK, fl);
1656 posix_test_lock(filp, fl);
1657 return 0;
1658}
1659EXPORT_SYMBOL_GPL(vfs_test_lock);
1660
J. Bruce Fieldsc2fa1b82007-02-20 16:10:11 -05001661static int posix_lock_to_flock(struct flock *flock, struct file_lock *fl)
1662{
1663 flock->l_pid = fl->fl_pid;
1664#if BITS_PER_LONG == 32
1665 /*
1666 * Make sure we can represent the posix lock via
1667 * legacy 32bit flock.
1668 */
1669 if (fl->fl_start > OFFT_OFFSET_MAX)
1670 return -EOVERFLOW;
1671 if (fl->fl_end != OFFSET_MAX && fl->fl_end > OFFT_OFFSET_MAX)
1672 return -EOVERFLOW;
1673#endif
1674 flock->l_start = fl->fl_start;
1675 flock->l_len = fl->fl_end == OFFSET_MAX ? 0 :
1676 fl->fl_end - fl->fl_start + 1;
1677 flock->l_whence = 0;
J. Bruce Fields129a84d2007-05-10 18:38:43 -04001678 flock->l_type = fl->fl_type;
J. Bruce Fieldsc2fa1b82007-02-20 16:10:11 -05001679 return 0;
1680}
1681
1682#if BITS_PER_LONG == 32
1683static void posix_lock_to_flock64(struct flock64 *flock, struct file_lock *fl)
1684{
1685 flock->l_pid = fl->fl_pid;
1686 flock->l_start = fl->fl_start;
1687 flock->l_len = fl->fl_end == OFFSET_MAX ? 0 :
1688 fl->fl_end - fl->fl_start + 1;
1689 flock->l_whence = 0;
1690 flock->l_type = fl->fl_type;
1691}
1692#endif
1693
Linus Torvalds1da177e2005-04-16 15:20:36 -07001694/* Report the first existing lock that would conflict with l.
1695 * This implements the F_GETLK command of fcntl().
1696 */
1697int fcntl_getlk(struct file *filp, struct flock __user *l)
1698{
Marc Eshel9d6a8c52007-02-21 00:55:18 -05001699 struct file_lock file_lock;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001700 struct flock flock;
1701 int error;
1702
1703 error = -EFAULT;
1704 if (copy_from_user(&flock, l, sizeof(flock)))
1705 goto out;
1706 error = -EINVAL;
1707 if ((flock.l_type != F_RDLCK) && (flock.l_type != F_WRLCK))
1708 goto out;
1709
1710 error = flock_to_posix_lock(filp, &file_lock, &flock);
1711 if (error)
1712 goto out;
1713
J. Bruce Fields3ee17ab2007-02-21 00:58:50 -05001714 error = vfs_test_lock(filp, &file_lock);
1715 if (error)
1716 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001717
Marc Eshel9d6a8c52007-02-21 00:55:18 -05001718 flock.l_type = file_lock.fl_type;
1719 if (file_lock.fl_type != F_UNLCK) {
1720 error = posix_lock_to_flock(&flock, &file_lock);
J. Bruce Fieldsc2fa1b82007-02-20 16:10:11 -05001721 if (error)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001722 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001723 }
1724 error = -EFAULT;
1725 if (!copy_to_user(l, &flock, sizeof(flock)))
1726 error = 0;
1727out:
1728 return error;
1729}
1730
Marc Eshel7723ec92007-01-18 15:08:55 -05001731/**
1732 * vfs_lock_file - file byte range lock
1733 * @filp: The file to apply the lock to
1734 * @cmd: type of locking operation (F_SETLK, F_GETLK, etc.)
1735 * @fl: The lock to be applied
Marc Eshel150b3932007-01-18 16:15:35 -05001736 * @conf: Place to return a copy of the conflicting lock, if found.
1737 *
1738 * A caller that doesn't care about the conflicting lock may pass NULL
1739 * as the final argument.
1740 *
1741 * If the filesystem defines a private ->lock() method, then @conf will
1742 * be left unchanged; so a caller that cares should initialize it to
1743 * some acceptable default.
Marc Eshel2beb6612006-12-05 23:31:28 -05001744 *
1745 * To avoid blocking kernel daemons, such as lockd, that need to acquire POSIX
1746 * locks, the ->lock() interface may return asynchronously, before the lock has
1747 * been granted or denied by the underlying filesystem, if (and only if)
1748 * fl_grant is set. Callers expecting ->lock() to return asynchronously
1749 * will only use F_SETLK, not F_SETLKW; they will set FL_SLEEP if (and only if)
1750 * the request is for a blocking lock. When ->lock() does return asynchronously,
Miklos Szeredibde74e42008-07-25 01:48:57 -07001751 * it must return FILE_LOCK_DEFERRED, and call ->fl_grant() when the lock
Marc Eshel2beb6612006-12-05 23:31:28 -05001752 * request completes.
1753 * If the request is for non-blocking lock the file system should return
Miklos Szeredibde74e42008-07-25 01:48:57 -07001754 * FILE_LOCK_DEFERRED then try to get the lock and call the callback routine
1755 * with the result. If the request timed out the callback routine will return a
Marc Eshel2beb6612006-12-05 23:31:28 -05001756 * nonzero return code and the file system should release the lock. The file
1757 * system is also responsible to keep a corresponding posix lock when it
1758 * grants a lock so the VFS can find out which locks are locally held and do
1759 * the correct lock cleanup when required.
1760 * The underlying filesystem must not drop the kernel lock or call
Miklos Szeredibde74e42008-07-25 01:48:57 -07001761 * ->fl_grant() before returning to the caller with a FILE_LOCK_DEFERRED
Marc Eshel2beb6612006-12-05 23:31:28 -05001762 * return code.
Marc Eshel7723ec92007-01-18 15:08:55 -05001763 */
Marc Eshel150b3932007-01-18 16:15:35 -05001764int vfs_lock_file(struct file *filp, unsigned int cmd, struct file_lock *fl, struct file_lock *conf)
Marc Eshel7723ec92007-01-18 15:08:55 -05001765{
1766 if (filp->f_op && filp->f_op->lock)
1767 return filp->f_op->lock(filp, cmd, fl);
1768 else
Marc Eshel150b3932007-01-18 16:15:35 -05001769 return posix_lock_file(filp, fl, conf);
Marc Eshel7723ec92007-01-18 15:08:55 -05001770}
1771EXPORT_SYMBOL_GPL(vfs_lock_file);
1772
Miklos Szeredib648a6d2008-07-25 01:48:57 -07001773static int do_lock_file_wait(struct file *filp, unsigned int cmd,
1774 struct file_lock *fl)
1775{
1776 int error;
1777
1778 error = security_file_lock(filp, fl->fl_type);
1779 if (error)
1780 return error;
1781
Miklos Szeredi764c76b2008-07-25 01:48:58 -07001782 for (;;) {
1783 error = vfs_lock_file(filp, cmd, fl, NULL);
1784 if (error != FILE_LOCK_DEFERRED)
Miklos Szeredib648a6d2008-07-25 01:48:57 -07001785 break;
Miklos Szeredi764c76b2008-07-25 01:48:58 -07001786 error = wait_event_interruptible(fl->fl_wait, !fl->fl_next);
1787 if (!error)
1788 continue;
1789
1790 locks_delete_block(fl);
1791 break;
Miklos Szeredib648a6d2008-07-25 01:48:57 -07001792 }
1793
1794 return error;
1795}
1796
Linus Torvalds1da177e2005-04-16 15:20:36 -07001797/* Apply the lock described by l to an open file descriptor.
1798 * This implements both the F_SETLK and F_SETLKW commands of fcntl().
1799 */
Peter Staubachc2936212005-07-27 11:45:09 -07001800int fcntl_setlk(unsigned int fd, struct file *filp, unsigned int cmd,
1801 struct flock __user *l)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001802{
1803 struct file_lock *file_lock = locks_alloc_lock();
1804 struct flock flock;
1805 struct inode *inode;
Al Viro0b2bac22008-05-06 13:58:34 -04001806 struct file *f;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001807 int error;
1808
1809 if (file_lock == NULL)
1810 return -ENOLCK;
1811
1812 /*
1813 * This might block, so we do it before checking the inode.
1814 */
1815 error = -EFAULT;
1816 if (copy_from_user(&flock, l, sizeof(flock)))
1817 goto out;
1818
Josef "Jeff" Sipek0f7fc9e2006-12-08 02:36:35 -08001819 inode = filp->f_path.dentry->d_inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001820
1821 /* Don't allow mandatory locks on files that may be memory mapped
1822 * and shared.
1823 */
Pavel Emelyanova16877c2007-10-01 14:41:11 -07001824 if (mandatory_lock(inode) && mapping_writably_mapped(filp->f_mapping)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001825 error = -EAGAIN;
1826 goto out;
1827 }
1828
Peter Staubachc2936212005-07-27 11:45:09 -07001829again:
Linus Torvalds1da177e2005-04-16 15:20:36 -07001830 error = flock_to_posix_lock(filp, file_lock, &flock);
1831 if (error)
1832 goto out;
1833 if (cmd == F_SETLKW) {
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
Miklos Szeredib648a6d2008-07-25 01:48:57 -07001854 error = do_lock_file_wait(filp, cmd, file_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001855
Peter Staubachc2936212005-07-27 11:45:09 -07001856 /*
1857 * Attempt to detect a close/fcntl race and recover by
1858 * releasing the lock that was just acquired.
1859 */
Al Viro0b2bac22008-05-06 13:58:34 -04001860 /*
1861 * we need that spin_lock here - it prevents reordering between
1862 * update of inode->i_flock and check for it done in close().
1863 * rcu_read_lock() wouldn't do.
1864 */
1865 spin_lock(&current->files->file_lock);
1866 f = fcheck(fd);
1867 spin_unlock(&current->files->file_lock);
1868 if (!error && f != filp && flock.l_type != F_UNLCK) {
Peter Staubachc2936212005-07-27 11:45:09 -07001869 flock.l_type = F_UNLCK;
1870 goto again;
1871 }
1872
1873out:
Linus Torvalds1da177e2005-04-16 15:20:36 -07001874 locks_free_lock(file_lock);
1875 return error;
1876}
1877
1878#if BITS_PER_LONG == 32
1879/* Report the first existing lock that would conflict with l.
1880 * This implements the F_GETLK command of fcntl().
1881 */
1882int fcntl_getlk64(struct file *filp, struct flock64 __user *l)
1883{
Marc Eshel9d6a8c52007-02-21 00:55:18 -05001884 struct file_lock file_lock;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001885 struct flock64 flock;
1886 int error;
1887
1888 error = -EFAULT;
1889 if (copy_from_user(&flock, l, sizeof(flock)))
1890 goto out;
1891 error = -EINVAL;
1892 if ((flock.l_type != F_RDLCK) && (flock.l_type != F_WRLCK))
1893 goto out;
1894
1895 error = flock64_to_posix_lock(filp, &file_lock, &flock);
1896 if (error)
1897 goto out;
1898
J. Bruce Fields3ee17ab2007-02-21 00:58:50 -05001899 error = vfs_test_lock(filp, &file_lock);
1900 if (error)
1901 goto out;
1902
Marc Eshel9d6a8c52007-02-21 00:55:18 -05001903 flock.l_type = file_lock.fl_type;
1904 if (file_lock.fl_type != F_UNLCK)
1905 posix_lock_to_flock64(&flock, &file_lock);
1906
Linus Torvalds1da177e2005-04-16 15:20:36 -07001907 error = -EFAULT;
1908 if (!copy_to_user(l, &flock, sizeof(flock)))
1909 error = 0;
1910
1911out:
1912 return error;
1913}
1914
1915/* Apply the lock described by l to an open file descriptor.
1916 * This implements both the F_SETLK and F_SETLKW commands of fcntl().
1917 */
Peter Staubachc2936212005-07-27 11:45:09 -07001918int fcntl_setlk64(unsigned int fd, struct file *filp, unsigned int cmd,
1919 struct flock64 __user *l)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001920{
1921 struct file_lock *file_lock = locks_alloc_lock();
1922 struct flock64 flock;
1923 struct inode *inode;
Al Viro0b2bac22008-05-06 13:58:34 -04001924 struct file *f;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001925 int error;
1926
1927 if (file_lock == NULL)
1928 return -ENOLCK;
1929
1930 /*
1931 * This might block, so we do it before checking the inode.
1932 */
1933 error = -EFAULT;
1934 if (copy_from_user(&flock, l, sizeof(flock)))
1935 goto out;
1936
Josef "Jeff" Sipek0f7fc9e2006-12-08 02:36:35 -08001937 inode = filp->f_path.dentry->d_inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001938
1939 /* Don't allow mandatory locks on files that may be memory mapped
1940 * and shared.
1941 */
Pavel Emelyanova16877c2007-10-01 14:41:11 -07001942 if (mandatory_lock(inode) && mapping_writably_mapped(filp->f_mapping)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001943 error = -EAGAIN;
1944 goto out;
1945 }
1946
Peter Staubachc2936212005-07-27 11:45:09 -07001947again:
Linus Torvalds1da177e2005-04-16 15:20:36 -07001948 error = flock64_to_posix_lock(filp, file_lock, &flock);
1949 if (error)
1950 goto out;
1951 if (cmd == F_SETLKW64) {
1952 file_lock->fl_flags |= FL_SLEEP;
1953 }
1954
1955 error = -EBADF;
1956 switch (flock.l_type) {
1957 case F_RDLCK:
1958 if (!(filp->f_mode & FMODE_READ))
1959 goto out;
1960 break;
1961 case F_WRLCK:
1962 if (!(filp->f_mode & FMODE_WRITE))
1963 goto out;
1964 break;
1965 case F_UNLCK:
1966 break;
1967 default:
1968 error = -EINVAL;
1969 goto out;
1970 }
1971
Miklos Szeredib648a6d2008-07-25 01:48:57 -07001972 error = do_lock_file_wait(filp, cmd, file_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001973
Peter Staubachc2936212005-07-27 11:45:09 -07001974 /*
1975 * Attempt to detect a close/fcntl race and recover by
1976 * releasing the lock that was just acquired.
1977 */
Al Viro0b2bac22008-05-06 13:58:34 -04001978 spin_lock(&current->files->file_lock);
1979 f = fcheck(fd);
1980 spin_unlock(&current->files->file_lock);
1981 if (!error && f != filp && flock.l_type != F_UNLCK) {
Peter Staubachc2936212005-07-27 11:45:09 -07001982 flock.l_type = F_UNLCK;
1983 goto again;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001984 }
1985
1986out:
1987 locks_free_lock(file_lock);
1988 return error;
1989}
1990#endif /* BITS_PER_LONG == 32 */
1991
1992/*
1993 * This function is called when the file is being removed
1994 * from the task's fd array. POSIX locks belonging to this task
1995 * are deleted at this time.
1996 */
1997void locks_remove_posix(struct file *filp, fl_owner_t owner)
1998{
Miklos Szerediff7b86b2006-06-23 02:05:11 -07001999 struct file_lock lock;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002000
2001 /*
2002 * If there are no locks held on this file, we don't need to call
2003 * posix_lock_file(). Another process could be setting a lock on this
2004 * file at the same time, but we wouldn't remove that lock anyway.
2005 */
Josef "Jeff" Sipek0f7fc9e2006-12-08 02:36:35 -08002006 if (!filp->f_path.dentry->d_inode->i_flock)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002007 return;
2008
2009 lock.fl_type = F_UNLCK;
Miklos Szeredi75e1fcc2006-06-23 02:05:12 -07002010 lock.fl_flags = FL_POSIX | FL_CLOSE;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002011 lock.fl_start = 0;
2012 lock.fl_end = OFFSET_MAX;
2013 lock.fl_owner = owner;
2014 lock.fl_pid = current->tgid;
2015 lock.fl_file = filp;
2016 lock.fl_ops = NULL;
2017 lock.fl_lmops = NULL;
2018
Marc Eshel150b3932007-01-18 16:15:35 -05002019 vfs_lock_file(filp, F_SETLK, &lock, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002020
Linus Torvalds1da177e2005-04-16 15:20:36 -07002021 if (lock.fl_ops && lock.fl_ops->fl_release_private)
2022 lock.fl_ops->fl_release_private(&lock);
2023}
2024
2025EXPORT_SYMBOL(locks_remove_posix);
2026
2027/*
2028 * This function is called on the last close of an open file.
2029 */
2030void locks_remove_flock(struct file *filp)
2031{
Josef "Jeff" Sipek0f7fc9e2006-12-08 02:36:35 -08002032 struct inode * inode = filp->f_path.dentry->d_inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002033 struct file_lock *fl;
2034 struct file_lock **before;
2035
2036 if (!inode->i_flock)
2037 return;
2038
2039 if (filp->f_op && filp->f_op->flock) {
2040 struct file_lock fl = {
2041 .fl_pid = current->tgid,
2042 .fl_file = filp,
2043 .fl_flags = FL_FLOCK,
2044 .fl_type = F_UNLCK,
2045 .fl_end = OFFSET_MAX,
2046 };
2047 filp->f_op->flock(filp, F_SETLKW, &fl);
Trond Myklebust80fec4c2005-06-22 17:16:31 +00002048 if (fl.fl_ops && fl.fl_ops->fl_release_private)
2049 fl.fl_ops->fl_release_private(&fl);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002050 }
2051
Arnd Bergmannb89f4322010-09-18 15:09:31 +02002052 lock_flocks();
Linus Torvalds1da177e2005-04-16 15:20:36 -07002053 before = &inode->i_flock;
2054
2055 while ((fl = *before) != NULL) {
2056 if (fl->fl_file == filp) {
Peter Staubachc2936212005-07-27 11:45:09 -07002057 if (IS_FLOCK(fl)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002058 locks_delete_lock(before);
2059 continue;
2060 }
2061 if (IS_LEASE(fl)) {
2062 lease_modify(before, F_UNLCK);
2063 continue;
2064 }
2065 /* What? */
2066 BUG();
2067 }
2068 before = &fl->fl_next;
2069 }
Arnd Bergmannb89f4322010-09-18 15:09:31 +02002070 unlock_flocks();
Linus Torvalds1da177e2005-04-16 15:20:36 -07002071}
2072
2073/**
Linus Torvalds1da177e2005-04-16 15:20:36 -07002074 * posix_unblock_lock - stop waiting for a file lock
2075 * @filp: how the file was opened
2076 * @waiter: the lock which was waiting
2077 *
2078 * lockd needs to block waiting for locks.
2079 */
J. Bruce Fields64a318e2006-01-03 09:55:46 +01002080int
Linus Torvalds1da177e2005-04-16 15:20:36 -07002081posix_unblock_lock(struct file *filp, struct file_lock *waiter)
2082{
J. Bruce Fields64a318e2006-01-03 09:55:46 +01002083 int status = 0;
2084
Arnd Bergmannb89f4322010-09-18 15:09:31 +02002085 lock_flocks();
J. Bruce Fields5996a292006-01-03 09:55:44 +01002086 if (waiter->fl_next)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002087 __locks_delete_block(waiter);
J. Bruce Fields64a318e2006-01-03 09:55:46 +01002088 else
2089 status = -ENOENT;
Arnd Bergmannb89f4322010-09-18 15:09:31 +02002090 unlock_flocks();
J. Bruce Fields64a318e2006-01-03 09:55:46 +01002091 return status;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002092}
2093
2094EXPORT_SYMBOL(posix_unblock_lock);
2095
Marc Eshel9b9d2ab2007-01-18 17:52:58 -05002096/**
2097 * vfs_cancel_lock - file byte range unblock lock
2098 * @filp: The file to apply the unblock to
2099 * @fl: The lock to be unblocked
2100 *
2101 * Used by lock managers to cancel blocked requests
2102 */
2103int vfs_cancel_lock(struct file *filp, struct file_lock *fl)
2104{
2105 if (filp->f_op && filp->f_op->lock)
2106 return filp->f_op->lock(filp, F_CANCELLK, fl);
2107 return 0;
2108}
2109
2110EXPORT_SYMBOL_GPL(vfs_cancel_lock);
2111
Pavel Emelyanov7f8ada92007-10-01 14:41:15 -07002112#ifdef CONFIG_PROC_FS
Alexey Dobriyand8ba7a32008-10-04 22:34:18 +04002113#include <linux/proc_fs.h>
Pavel Emelyanov7f8ada92007-10-01 14:41:15 -07002114#include <linux/seq_file.h>
2115
2116static void lock_get_status(struct seq_file *f, struct file_lock *fl,
2117 int id, char *pfx)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002118{
2119 struct inode *inode = NULL;
Vitaliy Gusevab1f1612008-01-17 00:07:08 +00002120 unsigned int fl_pid;
2121
2122 if (fl->fl_nspid)
Pavel Emelyanov6c5f3e72008-02-08 04:19:20 -08002123 fl_pid = pid_vnr(fl->fl_nspid);
Vitaliy Gusevab1f1612008-01-17 00:07:08 +00002124 else
2125 fl_pid = fl->fl_pid;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002126
2127 if (fl->fl_file != NULL)
Josef "Jeff" Sipek0f7fc9e2006-12-08 02:36:35 -08002128 inode = fl->fl_file->f_path.dentry->d_inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002129
Pavel Emelyanov7f8ada92007-10-01 14:41:15 -07002130 seq_printf(f, "%d:%s ", id, pfx);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002131 if (IS_POSIX(fl)) {
Pavel Emelyanov7f8ada92007-10-01 14:41:15 -07002132 seq_printf(f, "%6s %s ",
Linus Torvalds1da177e2005-04-16 15:20:36 -07002133 (fl->fl_flags & FL_ACCESS) ? "ACCESS" : "POSIX ",
2134 (inode == NULL) ? "*NOINODE*" :
Pavel Emelyanova16877c2007-10-01 14:41:11 -07002135 mandatory_lock(inode) ? "MANDATORY" : "ADVISORY ");
Linus Torvalds1da177e2005-04-16 15:20:36 -07002136 } else if (IS_FLOCK(fl)) {
2137 if (fl->fl_type & LOCK_MAND) {
Pavel Emelyanov7f8ada92007-10-01 14:41:15 -07002138 seq_printf(f, "FLOCK MSNFS ");
Linus Torvalds1da177e2005-04-16 15:20:36 -07002139 } else {
Pavel Emelyanov7f8ada92007-10-01 14:41:15 -07002140 seq_printf(f, "FLOCK ADVISORY ");
Linus Torvalds1da177e2005-04-16 15:20:36 -07002141 }
2142 } else if (IS_LEASE(fl)) {
Pavel Emelyanov7f8ada92007-10-01 14:41:15 -07002143 seq_printf(f, "LEASE ");
Linus Torvalds1da177e2005-04-16 15:20:36 -07002144 if (fl->fl_type & F_INPROGRESS)
Pavel Emelyanov7f8ada92007-10-01 14:41:15 -07002145 seq_printf(f, "BREAKING ");
Linus Torvalds1da177e2005-04-16 15:20:36 -07002146 else if (fl->fl_file)
Pavel Emelyanov7f8ada92007-10-01 14:41:15 -07002147 seq_printf(f, "ACTIVE ");
Linus Torvalds1da177e2005-04-16 15:20:36 -07002148 else
Pavel Emelyanov7f8ada92007-10-01 14:41:15 -07002149 seq_printf(f, "BREAKER ");
Linus Torvalds1da177e2005-04-16 15:20:36 -07002150 } else {
Pavel Emelyanov7f8ada92007-10-01 14:41:15 -07002151 seq_printf(f, "UNKNOWN UNKNOWN ");
Linus Torvalds1da177e2005-04-16 15:20:36 -07002152 }
2153 if (fl->fl_type & LOCK_MAND) {
Pavel Emelyanov7f8ada92007-10-01 14:41:15 -07002154 seq_printf(f, "%s ",
Linus Torvalds1da177e2005-04-16 15:20:36 -07002155 (fl->fl_type & LOCK_READ)
2156 ? (fl->fl_type & LOCK_WRITE) ? "RW " : "READ "
2157 : (fl->fl_type & LOCK_WRITE) ? "WRITE" : "NONE ");
2158 } else {
Pavel Emelyanov7f8ada92007-10-01 14:41:15 -07002159 seq_printf(f, "%s ",
Linus Torvalds1da177e2005-04-16 15:20:36 -07002160 (fl->fl_type & F_INPROGRESS)
2161 ? (fl->fl_type & F_UNLCK) ? "UNLCK" : "READ "
2162 : (fl->fl_type & F_WRLCK) ? "WRITE" : "READ ");
2163 }
2164 if (inode) {
2165#ifdef WE_CAN_BREAK_LSLK_NOW
Vitaliy Gusevab1f1612008-01-17 00:07:08 +00002166 seq_printf(f, "%d %s:%ld ", fl_pid,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002167 inode->i_sb->s_id, inode->i_ino);
2168#else
2169 /* userspace relies on this representation of dev_t ;-( */
Vitaliy Gusevab1f1612008-01-17 00:07:08 +00002170 seq_printf(f, "%d %02x:%02x:%ld ", fl_pid,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002171 MAJOR(inode->i_sb->s_dev),
2172 MINOR(inode->i_sb->s_dev), inode->i_ino);
2173#endif
2174 } else {
Vitaliy Gusevab1f1612008-01-17 00:07:08 +00002175 seq_printf(f, "%d <none>:0 ", fl_pid);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002176 }
2177 if (IS_POSIX(fl)) {
2178 if (fl->fl_end == OFFSET_MAX)
Pavel Emelyanov7f8ada92007-10-01 14:41:15 -07002179 seq_printf(f, "%Ld EOF\n", fl->fl_start);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002180 else
Pavel Emelyanov7f8ada92007-10-01 14:41:15 -07002181 seq_printf(f, "%Ld %Ld\n", fl->fl_start, fl->fl_end);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002182 } else {
Pavel Emelyanov7f8ada92007-10-01 14:41:15 -07002183 seq_printf(f, "0 EOF\n");
Linus Torvalds1da177e2005-04-16 15:20:36 -07002184 }
2185}
2186
Pavel Emelyanov7f8ada92007-10-01 14:41:15 -07002187static int locks_show(struct seq_file *f, void *v)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002188{
Pavel Emelyanov7f8ada92007-10-01 14:41:15 -07002189 struct file_lock *fl, *bfl;
2190
2191 fl = list_entry(v, struct file_lock, fl_link);
2192
2193 lock_get_status(f, fl, (long)f->private, "");
2194
2195 list_for_each_entry(bfl, &fl->fl_block, fl_block)
2196 lock_get_status(f, bfl, (long)f->private, " ->");
2197
2198 f->private++;
2199 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002200}
2201
Pavel Emelyanov7f8ada92007-10-01 14:41:15 -07002202static void *locks_start(struct seq_file *f, loff_t *pos)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002203{
Arnd Bergmannb89f4322010-09-18 15:09:31 +02002204 lock_flocks();
Pavel Emelyanov7f8ada92007-10-01 14:41:15 -07002205 f->private = (void *)1;
2206 return seq_list_start(&file_lock_list, *pos);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002207}
2208
Pavel Emelyanov7f8ada92007-10-01 14:41:15 -07002209static void *locks_next(struct seq_file *f, void *v, loff_t *pos)
2210{
2211 return seq_list_next(v, &file_lock_list, pos);
2212}
2213
2214static void locks_stop(struct seq_file *f, void *v)
2215{
Arnd Bergmannb89f4322010-09-18 15:09:31 +02002216 unlock_flocks();
Pavel Emelyanov7f8ada92007-10-01 14:41:15 -07002217}
2218
Alexey Dobriyand8ba7a32008-10-04 22:34:18 +04002219static const struct seq_operations locks_seq_operations = {
Pavel Emelyanov7f8ada92007-10-01 14:41:15 -07002220 .start = locks_start,
2221 .next = locks_next,
2222 .stop = locks_stop,
2223 .show = locks_show,
2224};
Alexey Dobriyand8ba7a32008-10-04 22:34:18 +04002225
2226static int locks_open(struct inode *inode, struct file *filp)
2227{
2228 return seq_open(filp, &locks_seq_operations);
2229}
2230
2231static const struct file_operations proc_locks_operations = {
2232 .open = locks_open,
2233 .read = seq_read,
2234 .llseek = seq_lseek,
2235 .release = seq_release,
2236};
2237
2238static int __init proc_locks_init(void)
2239{
2240 proc_create("locks", 0, NULL, &proc_locks_operations);
2241 return 0;
2242}
2243module_init(proc_locks_init);
Pavel Emelyanov7f8ada92007-10-01 14:41:15 -07002244#endif
2245
Linus Torvalds1da177e2005-04-16 15:20:36 -07002246/**
2247 * lock_may_read - checks that the region is free of locks
2248 * @inode: the inode that is being read
2249 * @start: the first byte to read
2250 * @len: the number of bytes to read
2251 *
2252 * Emulates Windows locking requirements. Whole-file
2253 * mandatory locks (share modes) can prohibit a read and
2254 * byte-range POSIX locks can prohibit a read if they overlap.
2255 *
2256 * N.B. this function is only ever called
2257 * from knfsd and ownership of locks is never checked.
2258 */
2259int lock_may_read(struct inode *inode, loff_t start, unsigned long len)
2260{
2261 struct file_lock *fl;
2262 int result = 1;
Arnd Bergmannb89f4322010-09-18 15:09:31 +02002263 lock_flocks();
Linus Torvalds1da177e2005-04-16 15:20:36 -07002264 for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) {
2265 if (IS_POSIX(fl)) {
2266 if (fl->fl_type == F_RDLCK)
2267 continue;
2268 if ((fl->fl_end < start) || (fl->fl_start > (start + len)))
2269 continue;
2270 } else if (IS_FLOCK(fl)) {
2271 if (!(fl->fl_type & LOCK_MAND))
2272 continue;
2273 if (fl->fl_type & LOCK_READ)
2274 continue;
2275 } else
2276 continue;
2277 result = 0;
2278 break;
2279 }
Arnd Bergmannb89f4322010-09-18 15:09:31 +02002280 unlock_flocks();
Linus Torvalds1da177e2005-04-16 15:20:36 -07002281 return result;
2282}
2283
2284EXPORT_SYMBOL(lock_may_read);
2285
2286/**
2287 * lock_may_write - checks that the region is free of locks
2288 * @inode: the inode that is being written
2289 * @start: the first byte to write
2290 * @len: the number of bytes to write
2291 *
2292 * Emulates Windows locking requirements. Whole-file
2293 * mandatory locks (share modes) can prohibit a write and
2294 * byte-range POSIX locks can prohibit a write if they overlap.
2295 *
2296 * N.B. this function is only ever called
2297 * from knfsd and ownership of locks is never checked.
2298 */
2299int lock_may_write(struct inode *inode, loff_t start, unsigned long len)
2300{
2301 struct file_lock *fl;
2302 int result = 1;
Arnd Bergmannb89f4322010-09-18 15:09:31 +02002303 lock_flocks();
Linus Torvalds1da177e2005-04-16 15:20:36 -07002304 for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) {
2305 if (IS_POSIX(fl)) {
2306 if ((fl->fl_end < start) || (fl->fl_start > (start + len)))
2307 continue;
2308 } else if (IS_FLOCK(fl)) {
2309 if (!(fl->fl_type & LOCK_MAND))
2310 continue;
2311 if (fl->fl_type & LOCK_WRITE)
2312 continue;
2313 } else
2314 continue;
2315 result = 0;
2316 break;
2317 }
Arnd Bergmannb89f4322010-09-18 15:09:31 +02002318 unlock_flocks();
Linus Torvalds1da177e2005-04-16 15:20:36 -07002319 return result;
2320}
2321
2322EXPORT_SYMBOL(lock_may_write);
2323
Linus Torvalds1da177e2005-04-16 15:20:36 -07002324static int __init filelock_init(void)
2325{
2326 filelock_cache = kmem_cache_create("file_lock_cache",
2327 sizeof(struct file_lock), 0, SLAB_PANIC,
Paul Mundt20c2df82007-07-20 10:11:58 +09002328 init_once);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002329 return 0;
2330}
2331
2332core_initcall(filelock_init);