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Commit | Line | Data |
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1da177e4 LT |
1 | /* |
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> | |
4fb3a538 | 127 | #include <linux/rcupdate.h> |
1da177e4 LT |
128 | |
129 | #include <asm/semaphore.h> | |
130 | #include <asm/uaccess.h> | |
131 | ||
132 | #define IS_POSIX(fl) (fl->fl_flags & FL_POSIX) | |
133 | #define IS_FLOCK(fl) (fl->fl_flags & FL_FLOCK) | |
134 | #define IS_LEASE(fl) (fl->fl_flags & FL_LEASE) | |
135 | ||
136 | int leases_enable = 1; | |
137 | int 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 | ||
26bcbf96 | 142 | static LIST_HEAD(file_lock_list); |
1da177e4 LT |
143 | static LIST_HEAD(blocked_list); |
144 | ||
e18b890b | 145 | static struct kmem_cache *filelock_cache __read_mostly; |
1da177e4 LT |
146 | |
147 | /* Allocate an empty lock structure. */ | |
148 | static struct file_lock *locks_alloc_lock(void) | |
149 | { | |
e94b1766 | 150 | return kmem_cache_alloc(filelock_cache, GFP_KERNEL); |
1da177e4 LT |
151 | } |
152 | ||
47831f35 TM |
153 | static 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 | ||
1da177e4 | 168 | /* Free a lock which is not in use. */ |
33443c42 | 169 | static void locks_free_lock(struct file_lock *fl) |
1da177e4 | 170 | { |
5ce29646 MS |
171 | BUG_ON(waitqueue_active(&fl->fl_wait)); |
172 | BUG_ON(!list_empty(&fl->fl_block)); | |
173 | BUG_ON(!list_empty(&fl->fl_link)); | |
1da177e4 | 174 | |
47831f35 | 175 | locks_release_private(fl); |
1da177e4 LT |
176 | kmem_cache_free(filelock_cache, fl); |
177 | } | |
178 | ||
179 | void locks_init_lock(struct file_lock *fl) | |
180 | { | |
181 | INIT_LIST_HEAD(&fl->fl_link); | |
182 | INIT_LIST_HEAD(&fl->fl_block); | |
183 | init_waitqueue_head(&fl->fl_wait); | |
184 | fl->fl_next = NULL; | |
185 | fl->fl_fasync = NULL; | |
186 | fl->fl_owner = NULL; | |
187 | fl->fl_pid = 0; | |
188 | fl->fl_file = NULL; | |
189 | fl->fl_flags = 0; | |
190 | fl->fl_type = 0; | |
191 | fl->fl_start = fl->fl_end = 0; | |
192 | fl->fl_ops = NULL; | |
193 | fl->fl_lmops = NULL; | |
194 | } | |
195 | ||
196 | EXPORT_SYMBOL(locks_init_lock); | |
197 | ||
198 | /* | |
199 | * Initialises the fields of the file lock which are invariant for | |
200 | * free file_locks. | |
201 | */ | |
e18b890b | 202 | static void init_once(void *foo, struct kmem_cache *cache, unsigned long flags) |
1da177e4 LT |
203 | { |
204 | struct file_lock *lock = (struct file_lock *) foo; | |
205 | ||
1da177e4 LT |
206 | locks_init_lock(lock); |
207 | } | |
208 | ||
47831f35 TM |
209 | static void locks_copy_private(struct file_lock *new, struct file_lock *fl) |
210 | { | |
211 | if (fl->fl_ops) { | |
212 | if (fl->fl_ops->fl_copy_lock) | |
213 | fl->fl_ops->fl_copy_lock(new, fl); | |
214 | new->fl_ops = fl->fl_ops; | |
215 | } | |
216 | if (fl->fl_lmops) { | |
217 | if (fl->fl_lmops->fl_copy_lock) | |
218 | fl->fl_lmops->fl_copy_lock(new, fl); | |
219 | new->fl_lmops = fl->fl_lmops; | |
220 | } | |
221 | } | |
222 | ||
1da177e4 LT |
223 | /* |
224 | * Initialize a new lock from an existing file_lock structure. | |
225 | */ | |
0996905f | 226 | static void __locks_copy_lock(struct file_lock *new, const struct file_lock *fl) |
1da177e4 LT |
227 | { |
228 | new->fl_owner = fl->fl_owner; | |
229 | new->fl_pid = fl->fl_pid; | |
0996905f | 230 | new->fl_file = NULL; |
1da177e4 LT |
231 | new->fl_flags = fl->fl_flags; |
232 | new->fl_type = fl->fl_type; | |
233 | new->fl_start = fl->fl_start; | |
234 | new->fl_end = fl->fl_end; | |
0996905f TM |
235 | new->fl_ops = NULL; |
236 | new->fl_lmops = NULL; | |
237 | } | |
238 | ||
239 | void locks_copy_lock(struct file_lock *new, struct file_lock *fl) | |
240 | { | |
241 | locks_release_private(new); | |
242 | ||
243 | __locks_copy_lock(new, fl); | |
244 | new->fl_file = fl->fl_file; | |
1da177e4 LT |
245 | new->fl_ops = fl->fl_ops; |
246 | new->fl_lmops = fl->fl_lmops; | |
47831f35 TM |
247 | |
248 | locks_copy_private(new, fl); | |
1da177e4 LT |
249 | } |
250 | ||
251 | EXPORT_SYMBOL(locks_copy_lock); | |
252 | ||
253 | static inline int flock_translate_cmd(int cmd) { | |
254 | if (cmd & LOCK_MAND) | |
255 | return cmd & (LOCK_MAND | LOCK_RW); | |
256 | switch (cmd) { | |
257 | case LOCK_SH: | |
258 | return F_RDLCK; | |
259 | case LOCK_EX: | |
260 | return F_WRLCK; | |
261 | case LOCK_UN: | |
262 | return F_UNLCK; | |
263 | } | |
264 | return -EINVAL; | |
265 | } | |
266 | ||
267 | /* Fill in a file_lock structure with an appropriate FLOCK lock. */ | |
268 | static int flock_make_lock(struct file *filp, struct file_lock **lock, | |
269 | unsigned int cmd) | |
270 | { | |
271 | struct file_lock *fl; | |
272 | int type = flock_translate_cmd(cmd); | |
273 | if (type < 0) | |
274 | return type; | |
275 | ||
276 | fl = locks_alloc_lock(); | |
277 | if (fl == NULL) | |
278 | return -ENOMEM; | |
279 | ||
280 | fl->fl_file = filp; | |
281 | fl->fl_pid = current->tgid; | |
282 | fl->fl_flags = FL_FLOCK; | |
283 | fl->fl_type = type; | |
284 | fl->fl_end = OFFSET_MAX; | |
285 | ||
286 | *lock = fl; | |
287 | return 0; | |
288 | } | |
289 | ||
290 | static int assign_type(struct file_lock *fl, int type) | |
291 | { | |
292 | switch (type) { | |
293 | case F_RDLCK: | |
294 | case F_WRLCK: | |
295 | case F_UNLCK: | |
296 | fl->fl_type = type; | |
297 | break; | |
298 | default: | |
299 | return -EINVAL; | |
300 | } | |
301 | return 0; | |
302 | } | |
303 | ||
304 | /* Verify a "struct flock" and copy it to a "struct file_lock" as a POSIX | |
305 | * style lock. | |
306 | */ | |
307 | static int flock_to_posix_lock(struct file *filp, struct file_lock *fl, | |
308 | struct flock *l) | |
309 | { | |
310 | off_t start, end; | |
311 | ||
312 | switch (l->l_whence) { | |
f5579f8c | 313 | case SEEK_SET: |
1da177e4 LT |
314 | start = 0; |
315 | break; | |
f5579f8c | 316 | case SEEK_CUR: |
1da177e4 LT |
317 | start = filp->f_pos; |
318 | break; | |
f5579f8c | 319 | case SEEK_END: |
0f7fc9e4 | 320 | start = i_size_read(filp->f_path.dentry->d_inode); |
1da177e4 LT |
321 | break; |
322 | default: | |
323 | return -EINVAL; | |
324 | } | |
325 | ||
326 | /* POSIX-1996 leaves the case l->l_len < 0 undefined; | |
327 | POSIX-2001 defines it. */ | |
328 | start += l->l_start; | |
4c780a46 TM |
329 | if (start < 0) |
330 | return -EINVAL; | |
331 | fl->fl_end = OFFSET_MAX; | |
332 | if (l->l_len > 0) { | |
333 | end = start + l->l_len - 1; | |
334 | fl->fl_end = end; | |
335 | } else if (l->l_len < 0) { | |
1da177e4 | 336 | end = start - 1; |
4c780a46 | 337 | fl->fl_end = end; |
1da177e4 | 338 | start += l->l_len; |
4c780a46 TM |
339 | if (start < 0) |
340 | return -EINVAL; | |
1da177e4 | 341 | } |
1da177e4 | 342 | fl->fl_start = start; /* we record the absolute position */ |
4c780a46 TM |
343 | if (fl->fl_end < fl->fl_start) |
344 | return -EOVERFLOW; | |
1da177e4 LT |
345 | |
346 | fl->fl_owner = current->files; | |
347 | fl->fl_pid = current->tgid; | |
348 | fl->fl_file = filp; | |
349 | fl->fl_flags = FL_POSIX; | |
350 | fl->fl_ops = NULL; | |
351 | fl->fl_lmops = NULL; | |
352 | ||
353 | return assign_type(fl, l->l_type); | |
354 | } | |
355 | ||
356 | #if BITS_PER_LONG == 32 | |
357 | static int flock64_to_posix_lock(struct file *filp, struct file_lock *fl, | |
358 | struct flock64 *l) | |
359 | { | |
360 | loff_t start; | |
361 | ||
362 | switch (l->l_whence) { | |
f5579f8c | 363 | case SEEK_SET: |
1da177e4 LT |
364 | start = 0; |
365 | break; | |
f5579f8c | 366 | case SEEK_CUR: |
1da177e4 LT |
367 | start = filp->f_pos; |
368 | break; | |
f5579f8c | 369 | case SEEK_END: |
0f7fc9e4 | 370 | start = i_size_read(filp->f_path.dentry->d_inode); |
1da177e4 LT |
371 | break; |
372 | default: | |
373 | return -EINVAL; | |
374 | } | |
375 | ||
4c780a46 TM |
376 | start += l->l_start; |
377 | if (start < 0) | |
1da177e4 | 378 | return -EINVAL; |
4c780a46 TM |
379 | fl->fl_end = OFFSET_MAX; |
380 | if (l->l_len > 0) { | |
381 | fl->fl_end = start + l->l_len - 1; | |
382 | } else if (l->l_len < 0) { | |
383 | fl->fl_end = start - 1; | |
384 | start += l->l_len; | |
385 | if (start < 0) | |
386 | return -EINVAL; | |
387 | } | |
1da177e4 | 388 | fl->fl_start = start; /* we record the absolute position */ |
4c780a46 TM |
389 | if (fl->fl_end < fl->fl_start) |
390 | return -EOVERFLOW; | |
1da177e4 LT |
391 | |
392 | fl->fl_owner = current->files; | |
393 | fl->fl_pid = current->tgid; | |
394 | fl->fl_file = filp; | |
395 | fl->fl_flags = FL_POSIX; | |
396 | fl->fl_ops = NULL; | |
397 | fl->fl_lmops = NULL; | |
398 | ||
399 | switch (l->l_type) { | |
400 | case F_RDLCK: | |
401 | case F_WRLCK: | |
402 | case F_UNLCK: | |
403 | fl->fl_type = l->l_type; | |
404 | break; | |
405 | default: | |
406 | return -EINVAL; | |
407 | } | |
408 | ||
409 | return (0); | |
410 | } | |
411 | #endif | |
412 | ||
413 | /* default lease lock manager operations */ | |
414 | static void lease_break_callback(struct file_lock *fl) | |
415 | { | |
416 | kill_fasync(&fl->fl_fasync, SIGIO, POLL_MSG); | |
417 | } | |
418 | ||
419 | static void lease_release_private_callback(struct file_lock *fl) | |
420 | { | |
421 | if (!fl->fl_file) | |
422 | return; | |
423 | ||
424 | f_delown(fl->fl_file); | |
425 | fl->fl_file->f_owner.signum = 0; | |
426 | } | |
427 | ||
75c96f85 | 428 | static int lease_mylease_callback(struct file_lock *fl, struct file_lock *try) |
1da177e4 LT |
429 | { |
430 | return fl->fl_file == try->fl_file; | |
431 | } | |
432 | ||
75c96f85 | 433 | static struct lock_manager_operations lease_manager_ops = { |
1da177e4 LT |
434 | .fl_break = lease_break_callback, |
435 | .fl_release_private = lease_release_private_callback, | |
436 | .fl_mylease = lease_mylease_callback, | |
437 | .fl_change = lease_modify, | |
438 | }; | |
439 | ||
440 | /* | |
441 | * Initialize a lease, use the default lock manager operations | |
442 | */ | |
443 | static int lease_init(struct file *filp, int type, struct file_lock *fl) | |
444 | { | |
75dff55a TM |
445 | if (assign_type(fl, type) != 0) |
446 | return -EINVAL; | |
447 | ||
1da177e4 LT |
448 | fl->fl_owner = current->files; |
449 | fl->fl_pid = current->tgid; | |
450 | ||
451 | fl->fl_file = filp; | |
452 | fl->fl_flags = FL_LEASE; | |
1da177e4 LT |
453 | fl->fl_start = 0; |
454 | fl->fl_end = OFFSET_MAX; | |
455 | fl->fl_ops = NULL; | |
456 | fl->fl_lmops = &lease_manager_ops; | |
457 | return 0; | |
458 | } | |
459 | ||
460 | /* Allocate a file_lock initialised to this type of lease */ | |
461 | static int lease_alloc(struct file *filp, int type, struct file_lock **flp) | |
462 | { | |
463 | struct file_lock *fl = locks_alloc_lock(); | |
75dff55a | 464 | int error = -ENOMEM; |
1da177e4 LT |
465 | |
466 | if (fl == NULL) | |
75dff55a | 467 | goto out; |
1da177e4 LT |
468 | |
469 | error = lease_init(filp, type, fl); | |
75dff55a TM |
470 | if (error) { |
471 | locks_free_lock(fl); | |
472 | fl = NULL; | |
473 | } | |
474 | out: | |
1da177e4 | 475 | *flp = fl; |
75dff55a | 476 | return error; |
1da177e4 LT |
477 | } |
478 | ||
479 | /* Check if two locks overlap each other. | |
480 | */ | |
481 | static 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 | */ | |
33443c42 | 490 | static int posix_same_owner(struct file_lock *fl1, struct file_lock *fl2) |
1da177e4 LT |
491 | { |
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 | */ | |
33443c42 | 501 | static void __locks_delete_block(struct file_lock *waiter) |
1da177e4 LT |
502 | { |
503 | list_del_init(&waiter->fl_block); | |
504 | list_del_init(&waiter->fl_link); | |
505 | waiter->fl_next = NULL; | |
506 | } | |
507 | ||
508 | /* | |
509 | */ | |
510 | static 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 | */ | |
522 | static void locks_insert_block(struct file_lock *blocker, | |
523 | struct file_lock *waiter) | |
524 | { | |
6dc0fe8f | 525 | BUG_ON(!list_empty(&waiter->fl_block)); |
1da177e4 LT |
526 | 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 | */ | |
536 | static void locks_wake_up_blocks(struct file_lock *blocker) | |
537 | { | |
538 | while (!list_empty(&blocker->fl_block)) { | |
539 | struct file_lock *waiter = list_entry(blocker->fl_block.next, | |
540 | struct file_lock, fl_block); | |
541 | __locks_delete_block(waiter); | |
542 | if (waiter->fl_lmops && waiter->fl_lmops->fl_notify) | |
543 | waiter->fl_lmops->fl_notify(waiter); | |
544 | else | |
545 | wake_up(&waiter->fl_wait); | |
546 | } | |
547 | } | |
548 | ||
549 | /* Insert file lock fl into an inode's lock list at the position indicated | |
550 | * by pos. At the same time add the lock to the global file lock list. | |
551 | */ | |
552 | static void locks_insert_lock(struct file_lock **pos, struct file_lock *fl) | |
553 | { | |
554 | list_add(&fl->fl_link, &file_lock_list); | |
555 | ||
556 | /* insert into file's list */ | |
557 | fl->fl_next = *pos; | |
558 | *pos = fl; | |
559 | ||
560 | if (fl->fl_ops && fl->fl_ops->fl_insert) | |
561 | fl->fl_ops->fl_insert(fl); | |
562 | } | |
563 | ||
564 | /* | |
565 | * Delete a lock and then free it. | |
566 | * Wake up processes that are blocked waiting for this lock, | |
567 | * notify the FS that the lock has been cleared and | |
568 | * finally free the lock. | |
569 | */ | |
570 | static void locks_delete_lock(struct file_lock **thisfl_p) | |
571 | { | |
572 | struct file_lock *fl = *thisfl_p; | |
573 | ||
574 | *thisfl_p = fl->fl_next; | |
575 | fl->fl_next = NULL; | |
576 | list_del_init(&fl->fl_link); | |
577 | ||
578 | fasync_helper(0, fl->fl_file, 0, &fl->fl_fasync); | |
579 | if (fl->fl_fasync != NULL) { | |
580 | printk(KERN_ERR "locks_delete_lock: fasync == %p\n", fl->fl_fasync); | |
581 | fl->fl_fasync = NULL; | |
582 | } | |
583 | ||
584 | if (fl->fl_ops && fl->fl_ops->fl_remove) | |
585 | fl->fl_ops->fl_remove(fl); | |
586 | ||
587 | locks_wake_up_blocks(fl); | |
588 | locks_free_lock(fl); | |
589 | } | |
590 | ||
591 | /* Determine if lock sys_fl blocks lock caller_fl. Common functionality | |
592 | * checks for shared/exclusive status of overlapping locks. | |
593 | */ | |
594 | static int locks_conflict(struct file_lock *caller_fl, struct file_lock *sys_fl) | |
595 | { | |
596 | if (sys_fl->fl_type == F_WRLCK) | |
597 | return 1; | |
598 | if (caller_fl->fl_type == F_WRLCK) | |
599 | return 1; | |
600 | return 0; | |
601 | } | |
602 | ||
603 | /* Determine if lock sys_fl blocks lock caller_fl. POSIX specific | |
604 | * checking before calling the locks_conflict(). | |
605 | */ | |
606 | static int posix_locks_conflict(struct file_lock *caller_fl, struct file_lock *sys_fl) | |
607 | { | |
608 | /* POSIX locks owned by the same process do not conflict with | |
609 | * each other. | |
610 | */ | |
611 | if (!IS_POSIX(sys_fl) || posix_same_owner(caller_fl, sys_fl)) | |
612 | return (0); | |
613 | ||
614 | /* Check whether they overlap */ | |
615 | if (!locks_overlap(caller_fl, sys_fl)) | |
616 | return 0; | |
617 | ||
618 | return (locks_conflict(caller_fl, sys_fl)); | |
619 | } | |
620 | ||
621 | /* Determine if lock sys_fl blocks lock caller_fl. FLOCK specific | |
622 | * checking before calling the locks_conflict(). | |
623 | */ | |
624 | static int flock_locks_conflict(struct file_lock *caller_fl, struct file_lock *sys_fl) | |
625 | { | |
626 | /* FLOCK locks referring to the same filp do not conflict with | |
627 | * each other. | |
628 | */ | |
629 | if (!IS_FLOCK(sys_fl) || (caller_fl->fl_file == sys_fl->fl_file)) | |
630 | return (0); | |
631 | if ((caller_fl->fl_type & LOCK_MAND) || (sys_fl->fl_type & LOCK_MAND)) | |
632 | return 0; | |
633 | ||
634 | return (locks_conflict(caller_fl, sys_fl)); | |
635 | } | |
636 | ||
637 | static int interruptible_sleep_on_locked(wait_queue_head_t *fl_wait, int timeout) | |
638 | { | |
639 | int result = 0; | |
640 | DECLARE_WAITQUEUE(wait, current); | |
641 | ||
642 | __set_current_state(TASK_INTERRUPTIBLE); | |
643 | add_wait_queue(fl_wait, &wait); | |
644 | if (timeout == 0) | |
645 | schedule(); | |
646 | else | |
647 | result = schedule_timeout(timeout); | |
648 | if (signal_pending(current)) | |
649 | result = -ERESTARTSYS; | |
650 | remove_wait_queue(fl_wait, &wait); | |
651 | __set_current_state(TASK_RUNNING); | |
652 | return result; | |
653 | } | |
654 | ||
655 | static int locks_block_on_timeout(struct file_lock *blocker, struct file_lock *waiter, int time) | |
656 | { | |
657 | int result; | |
658 | locks_insert_block(blocker, waiter); | |
659 | result = interruptible_sleep_on_locked(&waiter->fl_wait, time); | |
660 | __locks_delete_block(waiter); | |
661 | return result; | |
662 | } | |
663 | ||
8dc7c311 | 664 | int |
9d6a8c5c | 665 | posix_test_lock(struct file *filp, struct file_lock *fl) |
1da177e4 LT |
666 | { |
667 | struct file_lock *cfl; | |
668 | ||
669 | lock_kernel(); | |
0f7fc9e4 | 670 | for (cfl = filp->f_path.dentry->d_inode->i_flock; cfl; cfl = cfl->fl_next) { |
1da177e4 LT |
671 | if (!IS_POSIX(cfl)) |
672 | continue; | |
673 | if (posix_locks_conflict(cfl, fl)) | |
674 | break; | |
675 | } | |
8dc7c311 | 676 | if (cfl) { |
9d6a8c5c | 677 | __locks_copy_lock(fl, cfl); |
8dc7c311 AA |
678 | unlock_kernel(); |
679 | return 1; | |
129a84de BF |
680 | } else |
681 | fl->fl_type = F_UNLCK; | |
1da177e4 | 682 | unlock_kernel(); |
8dc7c311 | 683 | return 0; |
1da177e4 LT |
684 | } |
685 | ||
686 | EXPORT_SYMBOL(posix_test_lock); | |
687 | ||
688 | /* This function tests for deadlock condition before putting a process to | |
689 | * sleep. The detection scheme is no longer recursive. Recursive was neat, | |
690 | * but dangerous - we risked stack corruption if the lock data was bad, or | |
691 | * if the recursion was too deep for any other reason. | |
692 | * | |
693 | * We rely on the fact that a task can only be on one lock's wait queue | |
694 | * at a time. When we find blocked_task on a wait queue we can re-search | |
695 | * with blocked_task equal to that queue's owner, until either blocked_task | |
696 | * isn't found, or blocked_task is found on a queue owned by my_task. | |
697 | * | |
698 | * Note: the above assumption may not be true when handling lock requests | |
699 | * from a broken NFS client. But broken NFS clients have a lot more to | |
700 | * worry about than proper deadlock detection anyway... --okir | |
701 | */ | |
b0904e14 | 702 | static int posix_locks_deadlock(struct file_lock *caller_fl, |
1da177e4 LT |
703 | struct file_lock *block_fl) |
704 | { | |
705 | struct list_head *tmp; | |
706 | ||
707 | next_task: | |
708 | if (posix_same_owner(caller_fl, block_fl)) | |
709 | return 1; | |
710 | list_for_each(tmp, &blocked_list) { | |
711 | struct file_lock *fl = list_entry(tmp, struct file_lock, fl_link); | |
712 | if (posix_same_owner(fl, block_fl)) { | |
713 | fl = fl->fl_next; | |
714 | block_fl = fl; | |
715 | goto next_task; | |
716 | } | |
717 | } | |
718 | return 0; | |
719 | } | |
720 | ||
1da177e4 LT |
721 | /* Try to create a FLOCK lock on filp. We always insert new FLOCK locks |
722 | * at the head of the list, but that's secret knowledge known only to | |
723 | * flock_lock_file and posix_lock_file. | |
f475ae95 TM |
724 | * |
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. | |
1da177e4 | 728 | */ |
993dfa87 | 729 | static int flock_lock_file(struct file *filp, struct file_lock *request) |
1da177e4 | 730 | { |
993dfa87 | 731 | struct file_lock *new_fl = NULL; |
1da177e4 | 732 | struct file_lock **before; |
0f7fc9e4 | 733 | struct inode * inode = filp->f_path.dentry->d_inode; |
1da177e4 LT |
734 | int error = 0; |
735 | int found = 0; | |
736 | ||
737 | lock_kernel(); | |
f07f18dd TM |
738 | if (request->fl_flags & FL_ACCESS) |
739 | goto find_conflict; | |
1da177e4 LT |
740 | for_each_lock(inode, before) { |
741 | struct file_lock *fl = *before; | |
742 | if (IS_POSIX(fl)) | |
743 | break; | |
744 | if (IS_LEASE(fl)) | |
745 | continue; | |
746 | if (filp != fl->fl_file) | |
747 | continue; | |
993dfa87 | 748 | if (request->fl_type == fl->fl_type) |
1da177e4 LT |
749 | goto out; |
750 | found = 1; | |
751 | locks_delete_lock(before); | |
752 | break; | |
753 | } | |
1da177e4 | 754 | |
f475ae95 TM |
755 | if (request->fl_type == F_UNLCK) { |
756 | if ((request->fl_flags & FL_EXISTS) && !found) | |
757 | error = -ENOENT; | |
993dfa87 | 758 | goto out; |
f475ae95 | 759 | } |
1da177e4 | 760 | |
9cedc194 | 761 | error = -ENOMEM; |
993dfa87 TM |
762 | new_fl = locks_alloc_lock(); |
763 | if (new_fl == NULL) | |
764 | goto out; | |
1da177e4 LT |
765 | /* |
766 | * If a higher-priority process was blocked on the old file lock, | |
767 | * give it the opportunity to lock the file. | |
768 | */ | |
769 | if (found) | |
770 | cond_resched(); | |
771 | ||
f07f18dd | 772 | find_conflict: |
1da177e4 LT |
773 | for_each_lock(inode, before) { |
774 | struct file_lock *fl = *before; | |
775 | if (IS_POSIX(fl)) | |
776 | break; | |
777 | if (IS_LEASE(fl)) | |
778 | continue; | |
993dfa87 | 779 | if (!flock_locks_conflict(request, fl)) |
1da177e4 LT |
780 | continue; |
781 | error = -EAGAIN; | |
993dfa87 TM |
782 | if (request->fl_flags & FL_SLEEP) |
783 | locks_insert_block(fl, request); | |
1da177e4 LT |
784 | goto out; |
785 | } | |
f07f18dd TM |
786 | if (request->fl_flags & FL_ACCESS) |
787 | goto out; | |
993dfa87 | 788 | locks_copy_lock(new_fl, request); |
1da177e4 | 789 | locks_insert_lock(&inode->i_flock, new_fl); |
993dfa87 | 790 | new_fl = NULL; |
9cedc194 | 791 | error = 0; |
1da177e4 LT |
792 | |
793 | out: | |
794 | unlock_kernel(); | |
993dfa87 TM |
795 | if (new_fl) |
796 | locks_free_lock(new_fl); | |
1da177e4 LT |
797 | return error; |
798 | } | |
799 | ||
150b3934 | 800 | static int __posix_lock_file(struct inode *inode, struct file_lock *request, struct file_lock *conflock) |
1da177e4 LT |
801 | { |
802 | struct file_lock *fl; | |
39005d02 MS |
803 | struct file_lock *new_fl = NULL; |
804 | struct file_lock *new_fl2 = NULL; | |
1da177e4 LT |
805 | struct file_lock *left = NULL; |
806 | struct file_lock *right = NULL; | |
807 | struct file_lock **before; | |
808 | int error, added = 0; | |
809 | ||
810 | /* | |
811 | * We may need two file_lock structures for this operation, | |
812 | * so we get them in advance to avoid races. | |
39005d02 MS |
813 | * |
814 | * In some cases we can be sure, that no new locks will be needed | |
1da177e4 | 815 | */ |
39005d02 MS |
816 | if (!(request->fl_flags & FL_ACCESS) && |
817 | (request->fl_type != F_UNLCK || | |
818 | request->fl_start != 0 || request->fl_end != OFFSET_MAX)) { | |
819 | new_fl = locks_alloc_lock(); | |
820 | new_fl2 = locks_alloc_lock(); | |
821 | } | |
1da177e4 LT |
822 | |
823 | lock_kernel(); | |
824 | if (request->fl_type != F_UNLCK) { | |
825 | for_each_lock(inode, before) { | |
826 | struct file_lock *fl = *before; | |
827 | if (!IS_POSIX(fl)) | |
828 | continue; | |
829 | if (!posix_locks_conflict(request, fl)) | |
830 | continue; | |
5842add2 AA |
831 | if (conflock) |
832 | locks_copy_lock(conflock, fl); | |
1da177e4 LT |
833 | error = -EAGAIN; |
834 | if (!(request->fl_flags & FL_SLEEP)) | |
835 | goto out; | |
836 | error = -EDEADLK; | |
837 | if (posix_locks_deadlock(request, fl)) | |
838 | goto out; | |
839 | error = -EAGAIN; | |
840 | locks_insert_block(fl, request); | |
841 | goto out; | |
842 | } | |
843 | } | |
844 | ||
845 | /* If we're just looking for a conflict, we're done. */ | |
846 | error = 0; | |
847 | if (request->fl_flags & FL_ACCESS) | |
848 | goto out; | |
849 | ||
1da177e4 | 850 | /* |
1da177e4 LT |
851 | * Find the first old lock with the same owner as the new lock. |
852 | */ | |
853 | ||
854 | before = &inode->i_flock; | |
855 | ||
856 | /* First skip locks owned by other processes. */ | |
857 | while ((fl = *before) && (!IS_POSIX(fl) || | |
858 | !posix_same_owner(request, fl))) { | |
859 | before = &fl->fl_next; | |
860 | } | |
861 | ||
862 | /* Process locks with this owner. */ | |
863 | while ((fl = *before) && posix_same_owner(request, fl)) { | |
864 | /* Detect adjacent or overlapping regions (if same lock type) | |
865 | */ | |
866 | if (request->fl_type == fl->fl_type) { | |
449231d6 OK |
867 | /* In all comparisons of start vs end, use |
868 | * "start - 1" rather than "end + 1". If end | |
869 | * is OFFSET_MAX, end + 1 will become negative. | |
870 | */ | |
1da177e4 LT |
871 | if (fl->fl_end < request->fl_start - 1) |
872 | goto next_lock; | |
873 | /* If the next lock in the list has entirely bigger | |
874 | * addresses than the new one, insert the lock here. | |
875 | */ | |
449231d6 | 876 | if (fl->fl_start - 1 > request->fl_end) |
1da177e4 LT |
877 | break; |
878 | ||
879 | /* If we come here, the new and old lock are of the | |
880 | * same type and adjacent or overlapping. Make one | |
881 | * lock yielding from the lower start address of both | |
882 | * locks to the higher end address. | |
883 | */ | |
884 | if (fl->fl_start > request->fl_start) | |
885 | fl->fl_start = request->fl_start; | |
886 | else | |
887 | request->fl_start = fl->fl_start; | |
888 | if (fl->fl_end < request->fl_end) | |
889 | fl->fl_end = request->fl_end; | |
890 | else | |
891 | request->fl_end = fl->fl_end; | |
892 | if (added) { | |
893 | locks_delete_lock(before); | |
894 | continue; | |
895 | } | |
896 | request = fl; | |
897 | added = 1; | |
898 | } | |
899 | else { | |
900 | /* Processing for different lock types is a bit | |
901 | * more complex. | |
902 | */ | |
903 | if (fl->fl_end < request->fl_start) | |
904 | goto next_lock; | |
905 | if (fl->fl_start > request->fl_end) | |
906 | break; | |
907 | if (request->fl_type == F_UNLCK) | |
908 | added = 1; | |
909 | if (fl->fl_start < request->fl_start) | |
910 | left = fl; | |
911 | /* If the next lock in the list has a higher end | |
912 | * address than the new one, insert the new one here. | |
913 | */ | |
914 | if (fl->fl_end > request->fl_end) { | |
915 | right = fl; | |
916 | break; | |
917 | } | |
918 | if (fl->fl_start >= request->fl_start) { | |
919 | /* The new lock completely replaces an old | |
920 | * one (This may happen several times). | |
921 | */ | |
922 | if (added) { | |
923 | locks_delete_lock(before); | |
924 | continue; | |
925 | } | |
926 | /* Replace the old lock with the new one. | |
927 | * Wake up anybody waiting for the old one, | |
928 | * as the change in lock type might satisfy | |
929 | * their needs. | |
930 | */ | |
931 | locks_wake_up_blocks(fl); | |
932 | fl->fl_start = request->fl_start; | |
933 | fl->fl_end = request->fl_end; | |
934 | fl->fl_type = request->fl_type; | |
47831f35 TM |
935 | locks_release_private(fl); |
936 | locks_copy_private(fl, request); | |
1da177e4 LT |
937 | request = fl; |
938 | added = 1; | |
939 | } | |
940 | } | |
941 | /* Go on to next lock. | |
942 | */ | |
943 | next_lock: | |
944 | before = &fl->fl_next; | |
945 | } | |
946 | ||
0d9a490a MS |
947 | /* |
948 | * The above code only modifies existing locks in case of | |
949 | * merging or replacing. If new lock(s) need to be inserted | |
950 | * all modifications are done bellow this, so it's safe yet to | |
951 | * bail out. | |
952 | */ | |
953 | error = -ENOLCK; /* "no luck" */ | |
954 | if (right && left == right && !new_fl2) | |
955 | goto out; | |
956 | ||
1da177e4 LT |
957 | error = 0; |
958 | if (!added) { | |
f475ae95 TM |
959 | if (request->fl_type == F_UNLCK) { |
960 | if (request->fl_flags & FL_EXISTS) | |
961 | error = -ENOENT; | |
1da177e4 | 962 | goto out; |
f475ae95 | 963 | } |
0d9a490a MS |
964 | |
965 | if (!new_fl) { | |
966 | error = -ENOLCK; | |
967 | goto out; | |
968 | } | |
1da177e4 LT |
969 | locks_copy_lock(new_fl, request); |
970 | locks_insert_lock(before, new_fl); | |
971 | new_fl = NULL; | |
972 | } | |
973 | if (right) { | |
974 | if (left == right) { | |
975 | /* The new lock breaks the old one in two pieces, | |
976 | * so we have to use the second new lock. | |
977 | */ | |
978 | left = new_fl2; | |
979 | new_fl2 = NULL; | |
980 | locks_copy_lock(left, right); | |
981 | locks_insert_lock(before, left); | |
982 | } | |
983 | right->fl_start = request->fl_end + 1; | |
984 | locks_wake_up_blocks(right); | |
985 | } | |
986 | if (left) { | |
987 | left->fl_end = request->fl_start - 1; | |
988 | locks_wake_up_blocks(left); | |
989 | } | |
990 | out: | |
991 | unlock_kernel(); | |
992 | /* | |
993 | * Free any unused locks. | |
994 | */ | |
995 | if (new_fl) | |
996 | locks_free_lock(new_fl); | |
997 | if (new_fl2) | |
998 | locks_free_lock(new_fl2); | |
999 | return error; | |
1000 | } | |
1001 | ||
1002 | /** | |
1003 | * posix_lock_file - Apply a POSIX-style lock to a file | |
1004 | * @filp: The file to apply the lock to | |
1005 | * @fl: The lock to be applied | |
150b3934 | 1006 | * @conflock: Place to return a copy of the conflicting lock, if found. |
1da177e4 LT |
1007 | * |
1008 | * Add a POSIX style lock to a file. | |
1009 | * We merge adjacent & overlapping locks whenever possible. | |
1010 | * POSIX locks are sorted by owner task, then by starting address | |
f475ae95 TM |
1011 | * |
1012 | * Note that if called with an FL_EXISTS argument, the caller may determine | |
1013 | * whether or not a lock was successfully freed by testing the return | |
1014 | * value for -ENOENT. | |
1da177e4 | 1015 | */ |
150b3934 | 1016 | int posix_lock_file(struct file *filp, struct file_lock *fl, |
5842add2 AA |
1017 | struct file_lock *conflock) |
1018 | { | |
150b3934 | 1019 | return __posix_lock_file(filp->f_path.dentry->d_inode, fl, conflock); |
1da177e4 | 1020 | } |
150b3934 | 1021 | EXPORT_SYMBOL(posix_lock_file); |
1da177e4 LT |
1022 | |
1023 | /** | |
1024 | * posix_lock_file_wait - Apply a POSIX-style lock to a file | |
1025 | * @filp: The file to apply the lock to | |
1026 | * @fl: The lock to be applied | |
1027 | * | |
1028 | * Add a POSIX style lock to a file. | |
1029 | * We merge adjacent & overlapping locks whenever possible. | |
1030 | * POSIX locks are sorted by owner task, then by starting address | |
1031 | */ | |
1032 | int posix_lock_file_wait(struct file *filp, struct file_lock *fl) | |
1033 | { | |
1034 | int error; | |
1035 | might_sleep (); | |
1036 | for (;;) { | |
150b3934 | 1037 | error = posix_lock_file(filp, fl, NULL); |
1da177e4 LT |
1038 | if ((error != -EAGAIN) || !(fl->fl_flags & FL_SLEEP)) |
1039 | break; | |
1040 | error = wait_event_interruptible(fl->fl_wait, !fl->fl_next); | |
1041 | if (!error) | |
1042 | continue; | |
1043 | ||
1044 | locks_delete_block(fl); | |
1045 | break; | |
1046 | } | |
1047 | return error; | |
1048 | } | |
1049 | EXPORT_SYMBOL(posix_lock_file_wait); | |
1050 | ||
1051 | /** | |
1052 | * locks_mandatory_locked - Check for an active lock | |
1053 | * @inode: the file to check | |
1054 | * | |
1055 | * Searches the inode's list of locks to find any POSIX locks which conflict. | |
1056 | * This function is called from locks_verify_locked() only. | |
1057 | */ | |
1058 | int locks_mandatory_locked(struct inode *inode) | |
1059 | { | |
1060 | fl_owner_t owner = current->files; | |
1061 | struct file_lock *fl; | |
1062 | ||
1063 | /* | |
1064 | * Search the lock list for this inode for any POSIX locks. | |
1065 | */ | |
1066 | lock_kernel(); | |
1067 | for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) { | |
1068 | if (!IS_POSIX(fl)) | |
1069 | continue; | |
1070 | if (fl->fl_owner != owner) | |
1071 | break; | |
1072 | } | |
1073 | unlock_kernel(); | |
1074 | return fl ? -EAGAIN : 0; | |
1075 | } | |
1076 | ||
1077 | /** | |
1078 | * locks_mandatory_area - Check for a conflicting lock | |
1079 | * @read_write: %FLOCK_VERIFY_WRITE for exclusive access, %FLOCK_VERIFY_READ | |
1080 | * for shared | |
1081 | * @inode: the file to check | |
1082 | * @filp: how the file was opened (if it was) | |
1083 | * @offset: start of area to check | |
1084 | * @count: length of area to check | |
1085 | * | |
1086 | * Searches the inode's list of locks to find any POSIX locks which conflict. | |
1087 | * This function is called from rw_verify_area() and | |
1088 | * locks_verify_truncate(). | |
1089 | */ | |
1090 | int locks_mandatory_area(int read_write, struct inode *inode, | |
1091 | struct file *filp, loff_t offset, | |
1092 | size_t count) | |
1093 | { | |
1094 | struct file_lock fl; | |
1095 | int error; | |
1096 | ||
1097 | locks_init_lock(&fl); | |
1098 | fl.fl_owner = current->files; | |
1099 | fl.fl_pid = current->tgid; | |
1100 | fl.fl_file = filp; | |
1101 | fl.fl_flags = FL_POSIX | FL_ACCESS; | |
1102 | if (filp && !(filp->f_flags & O_NONBLOCK)) | |
1103 | fl.fl_flags |= FL_SLEEP; | |
1104 | fl.fl_type = (read_write == FLOCK_VERIFY_WRITE) ? F_WRLCK : F_RDLCK; | |
1105 | fl.fl_start = offset; | |
1106 | fl.fl_end = offset + count - 1; | |
1107 | ||
1108 | for (;;) { | |
150b3934 | 1109 | error = __posix_lock_file(inode, &fl, NULL); |
1da177e4 LT |
1110 | if (error != -EAGAIN) |
1111 | break; | |
1112 | if (!(fl.fl_flags & FL_SLEEP)) | |
1113 | break; | |
1114 | error = wait_event_interruptible(fl.fl_wait, !fl.fl_next); | |
1115 | if (!error) { | |
1116 | /* | |
1117 | * If we've been sleeping someone might have | |
1118 | * changed the permissions behind our back. | |
1119 | */ | |
1120 | if ((inode->i_mode & (S_ISGID | S_IXGRP)) == S_ISGID) | |
1121 | continue; | |
1122 | } | |
1123 | ||
1124 | locks_delete_block(&fl); | |
1125 | break; | |
1126 | } | |
1127 | ||
1128 | return error; | |
1129 | } | |
1130 | ||
1131 | EXPORT_SYMBOL(locks_mandatory_area); | |
1132 | ||
1133 | /* We already had a lease on this file; just change its type */ | |
1134 | int lease_modify(struct file_lock **before, int arg) | |
1135 | { | |
1136 | struct file_lock *fl = *before; | |
1137 | int error = assign_type(fl, arg); | |
1138 | ||
1139 | if (error) | |
1140 | return error; | |
1141 | locks_wake_up_blocks(fl); | |
1142 | if (arg == F_UNLCK) | |
1143 | locks_delete_lock(before); | |
1144 | return 0; | |
1145 | } | |
1146 | ||
1147 | EXPORT_SYMBOL(lease_modify); | |
1148 | ||
1149 | static void time_out_leases(struct inode *inode) | |
1150 | { | |
1151 | struct file_lock **before; | |
1152 | struct file_lock *fl; | |
1153 | ||
1154 | before = &inode->i_flock; | |
1155 | while ((fl = *before) && IS_LEASE(fl) && (fl->fl_type & F_INPROGRESS)) { | |
1156 | if ((fl->fl_break_time == 0) | |
1157 | || time_before(jiffies, fl->fl_break_time)) { | |
1158 | before = &fl->fl_next; | |
1159 | continue; | |
1160 | } | |
1da177e4 LT |
1161 | lease_modify(before, fl->fl_type & ~F_INPROGRESS); |
1162 | if (fl == *before) /* lease_modify may have freed fl */ | |
1163 | before = &fl->fl_next; | |
1164 | } | |
1165 | } | |
1166 | ||
1167 | /** | |
1168 | * __break_lease - revoke all outstanding leases on file | |
1169 | * @inode: the inode of the file to return | |
1170 | * @mode: the open mode (read or write) | |
1171 | * | |
1172 | * break_lease (inlined for speed) has checked there already | |
1173 | * is a lease on this file. Leases are broken on a call to open() | |
1174 | * or truncate(). This function can sleep unless you | |
1175 | * specified %O_NONBLOCK to your open(). | |
1176 | */ | |
1177 | int __break_lease(struct inode *inode, unsigned int mode) | |
1178 | { | |
1179 | int error = 0, future; | |
1180 | struct file_lock *new_fl, *flock; | |
1181 | struct file_lock *fl; | |
1182 | int alloc_err; | |
1183 | unsigned long break_time; | |
1184 | int i_have_this_lease = 0; | |
1185 | ||
1186 | alloc_err = lease_alloc(NULL, mode & FMODE_WRITE ? F_WRLCK : F_RDLCK, | |
1187 | &new_fl); | |
1188 | ||
1189 | lock_kernel(); | |
1190 | ||
1191 | time_out_leases(inode); | |
1192 | ||
1193 | flock = inode->i_flock; | |
1194 | if ((flock == NULL) || !IS_LEASE(flock)) | |
1195 | goto out; | |
1196 | ||
1197 | for (fl = flock; fl && IS_LEASE(fl); fl = fl->fl_next) | |
1198 | if (fl->fl_owner == current->files) | |
1199 | i_have_this_lease = 1; | |
1200 | ||
1201 | if (mode & FMODE_WRITE) { | |
1202 | /* If we want write access, we have to revoke any lease. */ | |
1203 | future = F_UNLCK | F_INPROGRESS; | |
1204 | } else if (flock->fl_type & F_INPROGRESS) { | |
1205 | /* If the lease is already being broken, we just leave it */ | |
1206 | future = flock->fl_type; | |
1207 | } else if (flock->fl_type & F_WRLCK) { | |
1208 | /* Downgrade the exclusive lease to a read-only lease. */ | |
1209 | future = F_RDLCK | F_INPROGRESS; | |
1210 | } else { | |
1211 | /* the existing lease was read-only, so we can read too. */ | |
1212 | goto out; | |
1213 | } | |
1214 | ||
1215 | if (alloc_err && !i_have_this_lease && ((mode & O_NONBLOCK) == 0)) { | |
1216 | error = alloc_err; | |
1217 | goto out; | |
1218 | } | |
1219 | ||
1220 | break_time = 0; | |
1221 | if (lease_break_time > 0) { | |
1222 | break_time = jiffies + lease_break_time * HZ; | |
1223 | if (break_time == 0) | |
1224 | break_time++; /* so that 0 means no break time */ | |
1225 | } | |
1226 | ||
1227 | for (fl = flock; fl && IS_LEASE(fl); fl = fl->fl_next) { | |
1228 | if (fl->fl_type != future) { | |
1229 | fl->fl_type = future; | |
1230 | fl->fl_break_time = break_time; | |
1231 | /* lease must have lmops break callback */ | |
1232 | fl->fl_lmops->fl_break(fl); | |
1233 | } | |
1234 | } | |
1235 | ||
1236 | if (i_have_this_lease || (mode & O_NONBLOCK)) { | |
1237 | error = -EWOULDBLOCK; | |
1238 | goto out; | |
1239 | } | |
1240 | ||
1241 | restart: | |
1242 | break_time = flock->fl_break_time; | |
1243 | if (break_time != 0) { | |
1244 | break_time -= jiffies; | |
1245 | if (break_time == 0) | |
1246 | break_time++; | |
1247 | } | |
1248 | error = locks_block_on_timeout(flock, new_fl, break_time); | |
1249 | if (error >= 0) { | |
1250 | if (error == 0) | |
1251 | time_out_leases(inode); | |
1252 | /* Wait for the next lease that has not been broken yet */ | |
1253 | for (flock = inode->i_flock; flock && IS_LEASE(flock); | |
1254 | flock = flock->fl_next) { | |
1255 | if (flock->fl_type & F_INPROGRESS) | |
1256 | goto restart; | |
1257 | } | |
1258 | error = 0; | |
1259 | } | |
1260 | ||
1261 | out: | |
1262 | unlock_kernel(); | |
1263 | if (!alloc_err) | |
1264 | locks_free_lock(new_fl); | |
1265 | return error; | |
1266 | } | |
1267 | ||
1268 | EXPORT_SYMBOL(__break_lease); | |
1269 | ||
1270 | /** | |
1271 | * lease_get_mtime | |
1272 | * @inode: the inode | |
1273 | * @time: pointer to a timespec which will contain the last modified time | |
1274 | * | |
1275 | * This is to force NFS clients to flush their caches for files with | |
1276 | * exclusive leases. The justification is that if someone has an | |
1277 | * exclusive lease, then they could be modifiying it. | |
1278 | */ | |
1279 | void lease_get_mtime(struct inode *inode, struct timespec *time) | |
1280 | { | |
1281 | struct file_lock *flock = inode->i_flock; | |
1282 | if (flock && IS_LEASE(flock) && (flock->fl_type & F_WRLCK)) | |
1283 | *time = current_fs_time(inode->i_sb); | |
1284 | else | |
1285 | *time = inode->i_mtime; | |
1286 | } | |
1287 | ||
1288 | EXPORT_SYMBOL(lease_get_mtime); | |
1289 | ||
1290 | /** | |
1291 | * fcntl_getlease - Enquire what lease is currently active | |
1292 | * @filp: the file | |
1293 | * | |
1294 | * The value returned by this function will be one of | |
1295 | * (if no lease break is pending): | |
1296 | * | |
1297 | * %F_RDLCK to indicate a shared lease is held. | |
1298 | * | |
1299 | * %F_WRLCK to indicate an exclusive lease is held. | |
1300 | * | |
1301 | * %F_UNLCK to indicate no lease is held. | |
1302 | * | |
1303 | * (if a lease break is pending): | |
1304 | * | |
1305 | * %F_RDLCK to indicate an exclusive lease needs to be | |
1306 | * changed to a shared lease (or removed). | |
1307 | * | |
1308 | * %F_UNLCK to indicate the lease needs to be removed. | |
1309 | * | |
1310 | * XXX: sfr & willy disagree over whether F_INPROGRESS | |
1311 | * should be returned to userspace. | |
1312 | */ | |
1313 | int fcntl_getlease(struct file *filp) | |
1314 | { | |
1315 | struct file_lock *fl; | |
1316 | int type = F_UNLCK; | |
1317 | ||
1318 | lock_kernel(); | |
0f7fc9e4 JJS |
1319 | time_out_leases(filp->f_path.dentry->d_inode); |
1320 | for (fl = filp->f_path.dentry->d_inode->i_flock; fl && IS_LEASE(fl); | |
1da177e4 LT |
1321 | fl = fl->fl_next) { |
1322 | if (fl->fl_file == filp) { | |
1323 | type = fl->fl_type & ~F_INPROGRESS; | |
1324 | break; | |
1325 | } | |
1326 | } | |
1327 | unlock_kernel(); | |
1328 | return type; | |
1329 | } | |
1330 | ||
1331 | /** | |
1332 | * __setlease - sets a lease on an open file | |
1333 | * @filp: file pointer | |
1334 | * @arg: type of lease to obtain | |
1335 | * @flp: input - file_lock to use, output - file_lock inserted | |
1336 | * | |
1337 | * The (input) flp->fl_lmops->fl_break function is required | |
1338 | * by break_lease(). | |
1339 | * | |
1340 | * Called with kernel lock held. | |
1341 | */ | |
75c96f85 | 1342 | static int __setlease(struct file *filp, long arg, struct file_lock **flp) |
1da177e4 | 1343 | { |
7eaae282 | 1344 | struct file_lock *fl, **before, **my_before = NULL, *lease; |
0f7fc9e4 | 1345 | struct dentry *dentry = filp->f_path.dentry; |
1da177e4 LT |
1346 | struct inode *inode = dentry->d_inode; |
1347 | int error, rdlease_count = 0, wrlease_count = 0; | |
1348 | ||
1349 | time_out_leases(inode); | |
1350 | ||
1351 | error = -EINVAL; | |
1352 | if (!flp || !(*flp) || !(*flp)->fl_lmops || !(*flp)->fl_lmops->fl_break) | |
1353 | goto out; | |
1354 | ||
7eaae282 KZ |
1355 | lease = *flp; |
1356 | ||
1da177e4 LT |
1357 | error = -EAGAIN; |
1358 | if ((arg == F_RDLCK) && (atomic_read(&inode->i_writecount) > 0)) | |
1359 | goto out; | |
1360 | if ((arg == F_WRLCK) | |
1361 | && ((atomic_read(&dentry->d_count) > 1) | |
1362 | || (atomic_read(&inode->i_count) > 1))) | |
1363 | goto out; | |
1364 | ||
1365 | /* | |
1366 | * At this point, we know that if there is an exclusive | |
1367 | * lease on this file, then we hold it on this filp | |
1368 | * (otherwise our open of this file would have blocked). | |
1369 | * And if we are trying to acquire an exclusive lease, | |
1370 | * then the file is not open by anyone (including us) | |
1371 | * except for this filp. | |
1372 | */ | |
1373 | for (before = &inode->i_flock; | |
1374 | ((fl = *before) != NULL) && IS_LEASE(fl); | |
1375 | before = &fl->fl_next) { | |
1376 | if (lease->fl_lmops->fl_mylease(fl, lease)) | |
1377 | my_before = before; | |
1378 | else if (fl->fl_type == (F_INPROGRESS | F_UNLCK)) | |
1379 | /* | |
1380 | * Someone is in the process of opening this | |
1381 | * file for writing so we may not take an | |
1382 | * exclusive lease on it. | |
1383 | */ | |
1384 | wrlease_count++; | |
1385 | else | |
1386 | rdlease_count++; | |
1387 | } | |
1388 | ||
1389 | if ((arg == F_RDLCK && (wrlease_count > 0)) || | |
1390 | (arg == F_WRLCK && ((rdlease_count + wrlease_count) > 0))) | |
1391 | goto out; | |
1392 | ||
1393 | if (my_before != NULL) { | |
75dff55a | 1394 | *flp = *my_before; |
1da177e4 LT |
1395 | error = lease->fl_lmops->fl_change(my_before, arg); |
1396 | goto out; | |
1397 | } | |
1398 | ||
1399 | error = 0; | |
1400 | if (arg == F_UNLCK) | |
1401 | goto out; | |
1402 | ||
1403 | error = -EINVAL; | |
1404 | if (!leases_enable) | |
1405 | goto out; | |
1406 | ||
74361cb6 TM |
1407 | error = -ENOMEM; |
1408 | fl = locks_alloc_lock(); | |
1409 | if (fl == NULL) | |
1da177e4 LT |
1410 | goto out; |
1411 | ||
1412 | locks_copy_lock(fl, lease); | |
1413 | ||
1414 | locks_insert_lock(before, fl); | |
1415 | ||
1416 | *flp = fl; | |
74361cb6 | 1417 | error = 0; |
1da177e4 LT |
1418 | out: |
1419 | return error; | |
1420 | } | |
1421 | ||
1422 | /** | |
1423 | * setlease - sets a lease on an open file | |
1424 | * @filp: file pointer | |
1425 | * @arg: type of lease to obtain | |
1426 | * @lease: file_lock to use | |
1427 | * | |
1428 | * Call this to establish a lease on the file. | |
1429 | * The fl_lmops fl_break function is required by break_lease | |
1430 | */ | |
1431 | ||
1432 | int setlease(struct file *filp, long arg, struct file_lock **lease) | |
1433 | { | |
0f7fc9e4 | 1434 | struct dentry *dentry = filp->f_path.dentry; |
1da177e4 LT |
1435 | struct inode *inode = dentry->d_inode; |
1436 | int error; | |
1437 | ||
1438 | if ((current->fsuid != inode->i_uid) && !capable(CAP_LEASE)) | |
1439 | return -EACCES; | |
1440 | if (!S_ISREG(inode->i_mode)) | |
1441 | return -EINVAL; | |
1442 | error = security_file_lock(filp, arg); | |
1443 | if (error) | |
1444 | return error; | |
1445 | ||
1446 | lock_kernel(); | |
1447 | error = __setlease(filp, arg, lease); | |
1448 | unlock_kernel(); | |
1449 | ||
1450 | return error; | |
1451 | } | |
1452 | ||
1453 | EXPORT_SYMBOL(setlease); | |
1454 | ||
1455 | /** | |
1456 | * fcntl_setlease - sets a lease on an open file | |
1457 | * @fd: open file descriptor | |
1458 | * @filp: file pointer | |
1459 | * @arg: type of lease to obtain | |
1460 | * | |
1461 | * Call this fcntl to establish a lease on the file. | |
1462 | * Note that you also need to call %F_SETSIG to | |
1463 | * receive a signal when the lease is broken. | |
1464 | */ | |
1465 | int fcntl_setlease(unsigned int fd, struct file *filp, long arg) | |
1466 | { | |
1467 | struct file_lock fl, *flp = &fl; | |
0f7fc9e4 | 1468 | struct dentry *dentry = filp->f_path.dentry; |
1da177e4 LT |
1469 | struct inode *inode = dentry->d_inode; |
1470 | int error; | |
1471 | ||
1472 | if ((current->fsuid != inode->i_uid) && !capable(CAP_LEASE)) | |
1473 | return -EACCES; | |
1474 | if (!S_ISREG(inode->i_mode)) | |
1475 | return -EINVAL; | |
1476 | error = security_file_lock(filp, arg); | |
1477 | if (error) | |
1478 | return error; | |
1479 | ||
1480 | locks_init_lock(&fl); | |
1481 | error = lease_init(filp, arg, &fl); | |
1482 | if (error) | |
1483 | return error; | |
1484 | ||
1485 | lock_kernel(); | |
1486 | ||
1487 | error = __setlease(filp, arg, &flp); | |
dc15ae14 | 1488 | if (error || arg == F_UNLCK) |
1da177e4 LT |
1489 | goto out_unlock; |
1490 | ||
1491 | error = fasync_helper(fd, filp, 1, &flp->fl_fasync); | |
1492 | if (error < 0) { | |
1493 | /* remove lease just inserted by __setlease */ | |
1494 | flp->fl_type = F_UNLCK | F_INPROGRESS; | |
1495 | flp->fl_break_time = jiffies- 10; | |
1496 | time_out_leases(inode); | |
1497 | goto out_unlock; | |
1498 | } | |
1499 | ||
609d7fa9 | 1500 | error = __f_setown(filp, task_pid(current), PIDTYPE_PID, 0); |
1da177e4 LT |
1501 | out_unlock: |
1502 | unlock_kernel(); | |
1503 | return error; | |
1504 | } | |
1505 | ||
1506 | /** | |
1507 | * flock_lock_file_wait - Apply a FLOCK-style lock to a file | |
1508 | * @filp: The file to apply the lock to | |
1509 | * @fl: The lock to be applied | |
1510 | * | |
1511 | * Add a FLOCK style lock to a file. | |
1512 | */ | |
1513 | int flock_lock_file_wait(struct file *filp, struct file_lock *fl) | |
1514 | { | |
1515 | int error; | |
1516 | might_sleep(); | |
1517 | for (;;) { | |
1518 | error = flock_lock_file(filp, fl); | |
1519 | if ((error != -EAGAIN) || !(fl->fl_flags & FL_SLEEP)) | |
1520 | break; | |
1521 | error = wait_event_interruptible(fl->fl_wait, !fl->fl_next); | |
1522 | if (!error) | |
1523 | continue; | |
1524 | ||
1525 | locks_delete_block(fl); | |
1526 | break; | |
1527 | } | |
1528 | return error; | |
1529 | } | |
1530 | ||
1531 | EXPORT_SYMBOL(flock_lock_file_wait); | |
1532 | ||
1533 | /** | |
1534 | * sys_flock: - flock() system call. | |
1535 | * @fd: the file descriptor to lock. | |
1536 | * @cmd: the type of lock to apply. | |
1537 | * | |
1538 | * Apply a %FL_FLOCK style lock to an open file descriptor. | |
1539 | * The @cmd can be one of | |
1540 | * | |
1541 | * %LOCK_SH -- a shared lock. | |
1542 | * | |
1543 | * %LOCK_EX -- an exclusive lock. | |
1544 | * | |
1545 | * %LOCK_UN -- remove an existing lock. | |
1546 | * | |
1547 | * %LOCK_MAND -- a `mandatory' flock. This exists to emulate Windows Share Modes. | |
1548 | * | |
1549 | * %LOCK_MAND can be combined with %LOCK_READ or %LOCK_WRITE to allow other | |
1550 | * processes read and write access respectively. | |
1551 | */ | |
1552 | asmlinkage long sys_flock(unsigned int fd, unsigned int cmd) | |
1553 | { | |
1554 | struct file *filp; | |
1555 | struct file_lock *lock; | |
1556 | int can_sleep, unlock; | |
1557 | int error; | |
1558 | ||
1559 | error = -EBADF; | |
1560 | filp = fget(fd); | |
1561 | if (!filp) | |
1562 | goto out; | |
1563 | ||
1564 | can_sleep = !(cmd & LOCK_NB); | |
1565 | cmd &= ~LOCK_NB; | |
1566 | unlock = (cmd == LOCK_UN); | |
1567 | ||
1568 | if (!unlock && !(cmd & LOCK_MAND) && !(filp->f_mode & 3)) | |
1569 | goto out_putf; | |
1570 | ||
1571 | error = flock_make_lock(filp, &lock, cmd); | |
1572 | if (error) | |
1573 | goto out_putf; | |
1574 | if (can_sleep) | |
1575 | lock->fl_flags |= FL_SLEEP; | |
1576 | ||
1577 | error = security_file_lock(filp, cmd); | |
1578 | if (error) | |
1579 | goto out_free; | |
1580 | ||
1581 | if (filp->f_op && filp->f_op->flock) | |
1582 | error = filp->f_op->flock(filp, | |
1583 | (can_sleep) ? F_SETLKW : F_SETLK, | |
1584 | lock); | |
1585 | else | |
1586 | error = flock_lock_file_wait(filp, lock); | |
1587 | ||
1588 | out_free: | |
993dfa87 | 1589 | locks_free_lock(lock); |
1da177e4 LT |
1590 | |
1591 | out_putf: | |
1592 | fput(filp); | |
1593 | out: | |
1594 | return error; | |
1595 | } | |
1596 | ||
3ee17abd BF |
1597 | /** |
1598 | * vfs_test_lock - test file byte range lock | |
1599 | * @filp: The file to test lock for | |
1600 | * @fl: The lock to test | |
1601 | * @conf: Place to return a copy of the conflicting lock, if found | |
1602 | * | |
1603 | * Returns -ERRNO on failure. Indicates presence of conflicting lock by | |
1604 | * setting conf->fl_type to something other than F_UNLCK. | |
1605 | */ | |
1606 | int vfs_test_lock(struct file *filp, struct file_lock *fl) | |
1607 | { | |
1608 | if (filp->f_op && filp->f_op->lock) | |
1609 | return filp->f_op->lock(filp, F_GETLK, fl); | |
1610 | posix_test_lock(filp, fl); | |
1611 | return 0; | |
1612 | } | |
1613 | EXPORT_SYMBOL_GPL(vfs_test_lock); | |
1614 | ||
c2fa1b8a BF |
1615 | static int posix_lock_to_flock(struct flock *flock, struct file_lock *fl) |
1616 | { | |
1617 | flock->l_pid = fl->fl_pid; | |
1618 | #if BITS_PER_LONG == 32 | |
1619 | /* | |
1620 | * Make sure we can represent the posix lock via | |
1621 | * legacy 32bit flock. | |
1622 | */ | |
1623 | if (fl->fl_start > OFFT_OFFSET_MAX) | |
1624 | return -EOVERFLOW; | |
1625 | if (fl->fl_end != OFFSET_MAX && fl->fl_end > OFFT_OFFSET_MAX) | |
1626 | return -EOVERFLOW; | |
1627 | #endif | |
1628 | flock->l_start = fl->fl_start; | |
1629 | flock->l_len = fl->fl_end == OFFSET_MAX ? 0 : | |
1630 | fl->fl_end - fl->fl_start + 1; | |
1631 | flock->l_whence = 0; | |
129a84de | 1632 | flock->l_type = fl->fl_type; |
c2fa1b8a BF |
1633 | return 0; |
1634 | } | |
1635 | ||
1636 | #if BITS_PER_LONG == 32 | |
1637 | static void posix_lock_to_flock64(struct flock64 *flock, struct file_lock *fl) | |
1638 | { | |
1639 | flock->l_pid = fl->fl_pid; | |
1640 | flock->l_start = fl->fl_start; | |
1641 | flock->l_len = fl->fl_end == OFFSET_MAX ? 0 : | |
1642 | fl->fl_end - fl->fl_start + 1; | |
1643 | flock->l_whence = 0; | |
1644 | flock->l_type = fl->fl_type; | |
1645 | } | |
1646 | #endif | |
1647 | ||
1da177e4 LT |
1648 | /* Report the first existing lock that would conflict with l. |
1649 | * This implements the F_GETLK command of fcntl(). | |
1650 | */ | |
1651 | int fcntl_getlk(struct file *filp, struct flock __user *l) | |
1652 | { | |
9d6a8c5c | 1653 | struct file_lock file_lock; |
1da177e4 LT |
1654 | struct flock flock; |
1655 | int error; | |
1656 | ||
1657 | error = -EFAULT; | |
1658 | if (copy_from_user(&flock, l, sizeof(flock))) | |
1659 | goto out; | |
1660 | error = -EINVAL; | |
1661 | if ((flock.l_type != F_RDLCK) && (flock.l_type != F_WRLCK)) | |
1662 | goto out; | |
1663 | ||
1664 | error = flock_to_posix_lock(filp, &file_lock, &flock); | |
1665 | if (error) | |
1666 | goto out; | |
1667 | ||
3ee17abd BF |
1668 | error = vfs_test_lock(filp, &file_lock); |
1669 | if (error) | |
1670 | goto out; | |
1da177e4 | 1671 | |
9d6a8c5c ME |
1672 | flock.l_type = file_lock.fl_type; |
1673 | if (file_lock.fl_type != F_UNLCK) { | |
1674 | error = posix_lock_to_flock(&flock, &file_lock); | |
c2fa1b8a | 1675 | if (error) |
1da177e4 | 1676 | goto out; |
1da177e4 LT |
1677 | } |
1678 | error = -EFAULT; | |
1679 | if (!copy_to_user(l, &flock, sizeof(flock))) | |
1680 | error = 0; | |
1681 | out: | |
1682 | return error; | |
1683 | } | |
1684 | ||
7723ec97 ME |
1685 | /** |
1686 | * vfs_lock_file - file byte range lock | |
1687 | * @filp: The file to apply the lock to | |
1688 | * @cmd: type of locking operation (F_SETLK, F_GETLK, etc.) | |
1689 | * @fl: The lock to be applied | |
150b3934 ME |
1690 | * @conf: Place to return a copy of the conflicting lock, if found. |
1691 | * | |
1692 | * A caller that doesn't care about the conflicting lock may pass NULL | |
1693 | * as the final argument. | |
1694 | * | |
1695 | * If the filesystem defines a private ->lock() method, then @conf will | |
1696 | * be left unchanged; so a caller that cares should initialize it to | |
1697 | * some acceptable default. | |
2beb6614 ME |
1698 | * |
1699 | * To avoid blocking kernel daemons, such as lockd, that need to acquire POSIX | |
1700 | * locks, the ->lock() interface may return asynchronously, before the lock has | |
1701 | * been granted or denied by the underlying filesystem, if (and only if) | |
1702 | * fl_grant is set. Callers expecting ->lock() to return asynchronously | |
1703 | * will only use F_SETLK, not F_SETLKW; they will set FL_SLEEP if (and only if) | |
1704 | * the request is for a blocking lock. When ->lock() does return asynchronously, | |
1705 | * it must return -EINPROGRESS, and call ->fl_grant() when the lock | |
1706 | * request completes. | |
1707 | * If the request is for non-blocking lock the file system should return | |
1708 | * -EINPROGRESS then try to get the lock and call the callback routine with | |
1709 | * the result. If the request timed out the callback routine will return a | |
1710 | * nonzero return code and the file system should release the lock. The file | |
1711 | * system is also responsible to keep a corresponding posix lock when it | |
1712 | * grants a lock so the VFS can find out which locks are locally held and do | |
1713 | * the correct lock cleanup when required. | |
1714 | * The underlying filesystem must not drop the kernel lock or call | |
1715 | * ->fl_grant() before returning to the caller with a -EINPROGRESS | |
1716 | * return code. | |
7723ec97 | 1717 | */ |
150b3934 | 1718 | int vfs_lock_file(struct file *filp, unsigned int cmd, struct file_lock *fl, struct file_lock *conf) |
7723ec97 ME |
1719 | { |
1720 | if (filp->f_op && filp->f_op->lock) | |
1721 | return filp->f_op->lock(filp, cmd, fl); | |
1722 | else | |
150b3934 | 1723 | return posix_lock_file(filp, fl, conf); |
7723ec97 ME |
1724 | } |
1725 | EXPORT_SYMBOL_GPL(vfs_lock_file); | |
1726 | ||
1da177e4 LT |
1727 | /* Apply the lock described by l to an open file descriptor. |
1728 | * This implements both the F_SETLK and F_SETLKW commands of fcntl(). | |
1729 | */ | |
c293621b PS |
1730 | int fcntl_setlk(unsigned int fd, struct file *filp, unsigned int cmd, |
1731 | struct flock __user *l) | |
1da177e4 LT |
1732 | { |
1733 | struct file_lock *file_lock = locks_alloc_lock(); | |
1734 | struct flock flock; | |
1735 | struct inode *inode; | |
1736 | int error; | |
1737 | ||
1738 | if (file_lock == NULL) | |
1739 | return -ENOLCK; | |
1740 | ||
1741 | /* | |
1742 | * This might block, so we do it before checking the inode. | |
1743 | */ | |
1744 | error = -EFAULT; | |
1745 | if (copy_from_user(&flock, l, sizeof(flock))) | |
1746 | goto out; | |
1747 | ||
0f7fc9e4 | 1748 | inode = filp->f_path.dentry->d_inode; |
1da177e4 LT |
1749 | |
1750 | /* Don't allow mandatory locks on files that may be memory mapped | |
1751 | * and shared. | |
1752 | */ | |
1753 | if (IS_MANDLOCK(inode) && | |
1754 | (inode->i_mode & (S_ISGID | S_IXGRP)) == S_ISGID && | |
1755 | mapping_writably_mapped(filp->f_mapping)) { | |
1756 | error = -EAGAIN; | |
1757 | goto out; | |
1758 | } | |
1759 | ||
c293621b | 1760 | again: |
1da177e4 LT |
1761 | error = flock_to_posix_lock(filp, file_lock, &flock); |
1762 | if (error) | |
1763 | goto out; | |
1764 | if (cmd == F_SETLKW) { | |
1765 | file_lock->fl_flags |= FL_SLEEP; | |
1766 | } | |
1767 | ||
1768 | error = -EBADF; | |
1769 | switch (flock.l_type) { | |
1770 | case F_RDLCK: | |
1771 | if (!(filp->f_mode & FMODE_READ)) | |
1772 | goto out; | |
1773 | break; | |
1774 | case F_WRLCK: | |
1775 | if (!(filp->f_mode & FMODE_WRITE)) | |
1776 | goto out; | |
1777 | break; | |
1778 | case F_UNLCK: | |
1779 | break; | |
1780 | default: | |
1781 | error = -EINVAL; | |
1782 | goto out; | |
1783 | } | |
1784 | ||
1785 | error = security_file_lock(filp, file_lock->fl_type); | |
1786 | if (error) | |
1787 | goto out; | |
1788 | ||
7723ec97 | 1789 | for (;;) { |
150b3934 | 1790 | error = vfs_lock_file(filp, cmd, file_lock, NULL); |
7723ec97 | 1791 | if (error != -EAGAIN || cmd == F_SETLK) |
1da177e4 | 1792 | break; |
7723ec97 ME |
1793 | error = wait_event_interruptible(file_lock->fl_wait, |
1794 | !file_lock->fl_next); | |
1795 | if (!error) | |
1796 | continue; | |
1797 | ||
1798 | locks_delete_block(file_lock); | |
1799 | break; | |
c293621b | 1800 | } |
1da177e4 | 1801 | |
c293621b PS |
1802 | /* |
1803 | * Attempt to detect a close/fcntl race and recover by | |
1804 | * releasing the lock that was just acquired. | |
1805 | */ | |
1806 | if (!error && fcheck(fd) != filp && flock.l_type != F_UNLCK) { | |
1807 | flock.l_type = F_UNLCK; | |
1808 | goto again; | |
1da177e4 LT |
1809 | } |
1810 | ||
c293621b | 1811 | out: |
1da177e4 LT |
1812 | locks_free_lock(file_lock); |
1813 | return error; | |
1814 | } | |
1815 | ||
1816 | #if BITS_PER_LONG == 32 | |
1817 | /* Report the first existing lock that would conflict with l. | |
1818 | * This implements the F_GETLK command of fcntl(). | |
1819 | */ | |
1820 | int fcntl_getlk64(struct file *filp, struct flock64 __user *l) | |
1821 | { | |
9d6a8c5c | 1822 | struct file_lock file_lock; |
1da177e4 LT |
1823 | struct flock64 flock; |
1824 | int error; | |
1825 | ||
1826 | error = -EFAULT; | |
1827 | if (copy_from_user(&flock, l, sizeof(flock))) | |
1828 | goto out; | |
1829 | error = -EINVAL; | |
1830 | if ((flock.l_type != F_RDLCK) && (flock.l_type != F_WRLCK)) | |
1831 | goto out; | |
1832 | ||
1833 | error = flock64_to_posix_lock(filp, &file_lock, &flock); | |
1834 | if (error) | |
1835 | goto out; | |
1836 | ||
3ee17abd BF |
1837 | error = vfs_test_lock(filp, &file_lock); |
1838 | if (error) | |
1839 | goto out; | |
1840 | ||
9d6a8c5c ME |
1841 | flock.l_type = file_lock.fl_type; |
1842 | if (file_lock.fl_type != F_UNLCK) | |
1843 | posix_lock_to_flock64(&flock, &file_lock); | |
1844 | ||
1da177e4 LT |
1845 | error = -EFAULT; |
1846 | if (!copy_to_user(l, &flock, sizeof(flock))) | |
1847 | error = 0; | |
1848 | ||
1849 | out: | |
1850 | return error; | |
1851 | } | |
1852 | ||
1853 | /* Apply the lock described by l to an open file descriptor. | |
1854 | * This implements both the F_SETLK and F_SETLKW commands of fcntl(). | |
1855 | */ | |
c293621b PS |
1856 | int fcntl_setlk64(unsigned int fd, struct file *filp, unsigned int cmd, |
1857 | struct flock64 __user *l) | |
1da177e4 LT |
1858 | { |
1859 | struct file_lock *file_lock = locks_alloc_lock(); | |
1860 | struct flock64 flock; | |
1861 | struct inode *inode; | |
1862 | int error; | |
1863 | ||
1864 | if (file_lock == NULL) | |
1865 | return -ENOLCK; | |
1866 | ||
1867 | /* | |
1868 | * This might block, so we do it before checking the inode. | |
1869 | */ | |
1870 | error = -EFAULT; | |
1871 | if (copy_from_user(&flock, l, sizeof(flock))) | |
1872 | goto out; | |
1873 | ||
0f7fc9e4 | 1874 | inode = filp->f_path.dentry->d_inode; |
1da177e4 LT |
1875 | |
1876 | /* Don't allow mandatory locks on files that may be memory mapped | |
1877 | * and shared. | |
1878 | */ | |
1879 | if (IS_MANDLOCK(inode) && | |
1880 | (inode->i_mode & (S_ISGID | S_IXGRP)) == S_ISGID && | |
1881 | mapping_writably_mapped(filp->f_mapping)) { | |
1882 | error = -EAGAIN; | |
1883 | goto out; | |
1884 | } | |
1885 | ||
c293621b | 1886 | again: |
1da177e4 LT |
1887 | error = flock64_to_posix_lock(filp, file_lock, &flock); |
1888 | if (error) | |
1889 | goto out; | |
1890 | if (cmd == F_SETLKW64) { | |
1891 | file_lock->fl_flags |= FL_SLEEP; | |
1892 | } | |
1893 | ||
1894 | error = -EBADF; | |
1895 | switch (flock.l_type) { | |
1896 | case F_RDLCK: | |
1897 | if (!(filp->f_mode & FMODE_READ)) | |
1898 | goto out; | |
1899 | break; | |
1900 | case F_WRLCK: | |
1901 | if (!(filp->f_mode & FMODE_WRITE)) | |
1902 | goto out; | |
1903 | break; | |
1904 | case F_UNLCK: | |
1905 | break; | |
1906 | default: | |
1907 | error = -EINVAL; | |
1908 | goto out; | |
1909 | } | |
1910 | ||
1911 | error = security_file_lock(filp, file_lock->fl_type); | |
1912 | if (error) | |
1913 | goto out; | |
1914 | ||
7723ec97 | 1915 | for (;;) { |
150b3934 | 1916 | error = vfs_lock_file(filp, cmd, file_lock, NULL); |
7723ec97 | 1917 | if (error != -EAGAIN || cmd == F_SETLK64) |
1da177e4 | 1918 | break; |
7723ec97 ME |
1919 | error = wait_event_interruptible(file_lock->fl_wait, |
1920 | !file_lock->fl_next); | |
1921 | if (!error) | |
1922 | continue; | |
1923 | ||
1924 | locks_delete_block(file_lock); | |
1925 | break; | |
c293621b | 1926 | } |
1da177e4 | 1927 | |
c293621b PS |
1928 | /* |
1929 | * Attempt to detect a close/fcntl race and recover by | |
1930 | * releasing the lock that was just acquired. | |
1931 | */ | |
1932 | if (!error && fcheck(fd) != filp && flock.l_type != F_UNLCK) { | |
1933 | flock.l_type = F_UNLCK; | |
1934 | goto again; | |
1da177e4 LT |
1935 | } |
1936 | ||
1937 | out: | |
1938 | locks_free_lock(file_lock); | |
1939 | return error; | |
1940 | } | |
1941 | #endif /* BITS_PER_LONG == 32 */ | |
1942 | ||
1943 | /* | |
1944 | * This function is called when the file is being removed | |
1945 | * from the task's fd array. POSIX locks belonging to this task | |
1946 | * are deleted at this time. | |
1947 | */ | |
1948 | void locks_remove_posix(struct file *filp, fl_owner_t owner) | |
1949 | { | |
ff7b86b8 | 1950 | struct file_lock lock; |
1da177e4 LT |
1951 | |
1952 | /* | |
1953 | * If there are no locks held on this file, we don't need to call | |
1954 | * posix_lock_file(). Another process could be setting a lock on this | |
1955 | * file at the same time, but we wouldn't remove that lock anyway. | |
1956 | */ | |
0f7fc9e4 | 1957 | if (!filp->f_path.dentry->d_inode->i_flock) |
1da177e4 LT |
1958 | return; |
1959 | ||
1960 | lock.fl_type = F_UNLCK; | |
75e1fcc0 | 1961 | lock.fl_flags = FL_POSIX | FL_CLOSE; |
1da177e4 LT |
1962 | lock.fl_start = 0; |
1963 | lock.fl_end = OFFSET_MAX; | |
1964 | lock.fl_owner = owner; | |
1965 | lock.fl_pid = current->tgid; | |
1966 | lock.fl_file = filp; | |
1967 | lock.fl_ops = NULL; | |
1968 | lock.fl_lmops = NULL; | |
1969 | ||
150b3934 | 1970 | vfs_lock_file(filp, F_SETLK, &lock, NULL); |
1da177e4 | 1971 | |
1da177e4 LT |
1972 | if (lock.fl_ops && lock.fl_ops->fl_release_private) |
1973 | lock.fl_ops->fl_release_private(&lock); | |
1974 | } | |
1975 | ||
1976 | EXPORT_SYMBOL(locks_remove_posix); | |
1977 | ||
1978 | /* | |
1979 | * This function is called on the last close of an open file. | |
1980 | */ | |
1981 | void locks_remove_flock(struct file *filp) | |
1982 | { | |
0f7fc9e4 | 1983 | struct inode * inode = filp->f_path.dentry->d_inode; |
1da177e4 LT |
1984 | struct file_lock *fl; |
1985 | struct file_lock **before; | |
1986 | ||
1987 | if (!inode->i_flock) | |
1988 | return; | |
1989 | ||
1990 | if (filp->f_op && filp->f_op->flock) { | |
1991 | struct file_lock fl = { | |
1992 | .fl_pid = current->tgid, | |
1993 | .fl_file = filp, | |
1994 | .fl_flags = FL_FLOCK, | |
1995 | .fl_type = F_UNLCK, | |
1996 | .fl_end = OFFSET_MAX, | |
1997 | }; | |
1998 | filp->f_op->flock(filp, F_SETLKW, &fl); | |
80fec4c6 TM |
1999 | if (fl.fl_ops && fl.fl_ops->fl_release_private) |
2000 | fl.fl_ops->fl_release_private(&fl); | |
1da177e4 LT |
2001 | } |
2002 | ||
2003 | lock_kernel(); | |
2004 | before = &inode->i_flock; | |
2005 | ||
2006 | while ((fl = *before) != NULL) { | |
2007 | if (fl->fl_file == filp) { | |
c293621b | 2008 | if (IS_FLOCK(fl)) { |
1da177e4 LT |
2009 | locks_delete_lock(before); |
2010 | continue; | |
2011 | } | |
2012 | if (IS_LEASE(fl)) { | |
2013 | lease_modify(before, F_UNLCK); | |
2014 | continue; | |
2015 | } | |
2016 | /* What? */ | |
2017 | BUG(); | |
2018 | } | |
2019 | before = &fl->fl_next; | |
2020 | } | |
2021 | unlock_kernel(); | |
2022 | } | |
2023 | ||
1da177e4 LT |
2024 | /** |
2025 | * posix_unblock_lock - stop waiting for a file lock | |
2026 | * @filp: how the file was opened | |
2027 | * @waiter: the lock which was waiting | |
2028 | * | |
2029 | * lockd needs to block waiting for locks. | |
2030 | */ | |
64a318ee | 2031 | int |
1da177e4 LT |
2032 | posix_unblock_lock(struct file *filp, struct file_lock *waiter) |
2033 | { | |
64a318ee BF |
2034 | int status = 0; |
2035 | ||
1da177e4 | 2036 | lock_kernel(); |
5996a298 | 2037 | if (waiter->fl_next) |
1da177e4 | 2038 | __locks_delete_block(waiter); |
64a318ee BF |
2039 | else |
2040 | status = -ENOENT; | |
5996a298 | 2041 | unlock_kernel(); |
64a318ee | 2042 | return status; |
1da177e4 LT |
2043 | } |
2044 | ||
2045 | EXPORT_SYMBOL(posix_unblock_lock); | |
2046 | ||
9b9d2ab4 ME |
2047 | /** |
2048 | * vfs_cancel_lock - file byte range unblock lock | |
2049 | * @filp: The file to apply the unblock to | |
2050 | * @fl: The lock to be unblocked | |
2051 | * | |
2052 | * Used by lock managers to cancel blocked requests | |
2053 | */ | |
2054 | int vfs_cancel_lock(struct file *filp, struct file_lock *fl) | |
2055 | { | |
2056 | if (filp->f_op && filp->f_op->lock) | |
2057 | return filp->f_op->lock(filp, F_CANCELLK, fl); | |
2058 | return 0; | |
2059 | } | |
2060 | ||
2061 | EXPORT_SYMBOL_GPL(vfs_cancel_lock); | |
2062 | ||
1da177e4 LT |
2063 | static void lock_get_status(char* out, struct file_lock *fl, int id, char *pfx) |
2064 | { | |
2065 | struct inode *inode = NULL; | |
2066 | ||
2067 | if (fl->fl_file != NULL) | |
0f7fc9e4 | 2068 | inode = fl->fl_file->f_path.dentry->d_inode; |
1da177e4 LT |
2069 | |
2070 | out += sprintf(out, "%d:%s ", id, pfx); | |
2071 | if (IS_POSIX(fl)) { | |
2072 | out += sprintf(out, "%6s %s ", | |
2073 | (fl->fl_flags & FL_ACCESS) ? "ACCESS" : "POSIX ", | |
2074 | (inode == NULL) ? "*NOINODE*" : | |
2075 | (IS_MANDLOCK(inode) && | |
2076 | (inode->i_mode & (S_IXGRP | S_ISGID)) == S_ISGID) ? | |
2077 | "MANDATORY" : "ADVISORY "); | |
2078 | } else if (IS_FLOCK(fl)) { | |
2079 | if (fl->fl_type & LOCK_MAND) { | |
2080 | out += sprintf(out, "FLOCK MSNFS "); | |
2081 | } else { | |
2082 | out += sprintf(out, "FLOCK ADVISORY "); | |
2083 | } | |
2084 | } else if (IS_LEASE(fl)) { | |
2085 | out += sprintf(out, "LEASE "); | |
2086 | if (fl->fl_type & F_INPROGRESS) | |
2087 | out += sprintf(out, "BREAKING "); | |
2088 | else if (fl->fl_file) | |
2089 | out += sprintf(out, "ACTIVE "); | |
2090 | else | |
2091 | out += sprintf(out, "BREAKER "); | |
2092 | } else { | |
2093 | out += sprintf(out, "UNKNOWN UNKNOWN "); | |
2094 | } | |
2095 | if (fl->fl_type & LOCK_MAND) { | |
2096 | out += sprintf(out, "%s ", | |
2097 | (fl->fl_type & LOCK_READ) | |
2098 | ? (fl->fl_type & LOCK_WRITE) ? "RW " : "READ " | |
2099 | : (fl->fl_type & LOCK_WRITE) ? "WRITE" : "NONE "); | |
2100 | } else { | |
2101 | out += sprintf(out, "%s ", | |
2102 | (fl->fl_type & F_INPROGRESS) | |
2103 | ? (fl->fl_type & F_UNLCK) ? "UNLCK" : "READ " | |
2104 | : (fl->fl_type & F_WRLCK) ? "WRITE" : "READ "); | |
2105 | } | |
2106 | if (inode) { | |
2107 | #ifdef WE_CAN_BREAK_LSLK_NOW | |
2108 | out += sprintf(out, "%d %s:%ld ", fl->fl_pid, | |
2109 | inode->i_sb->s_id, inode->i_ino); | |
2110 | #else | |
2111 | /* userspace relies on this representation of dev_t ;-( */ | |
2112 | out += sprintf(out, "%d %02x:%02x:%ld ", fl->fl_pid, | |
2113 | MAJOR(inode->i_sb->s_dev), | |
2114 | MINOR(inode->i_sb->s_dev), inode->i_ino); | |
2115 | #endif | |
2116 | } else { | |
2117 | out += sprintf(out, "%d <none>:0 ", fl->fl_pid); | |
2118 | } | |
2119 | if (IS_POSIX(fl)) { | |
2120 | if (fl->fl_end == OFFSET_MAX) | |
2121 | out += sprintf(out, "%Ld EOF\n", fl->fl_start); | |
2122 | else | |
2123 | out += sprintf(out, "%Ld %Ld\n", fl->fl_start, | |
2124 | fl->fl_end); | |
2125 | } else { | |
2126 | out += sprintf(out, "0 EOF\n"); | |
2127 | } | |
2128 | } | |
2129 | ||
2130 | static void move_lock_status(char **p, off_t* pos, off_t offset) | |
2131 | { | |
2132 | int len; | |
2133 | len = strlen(*p); | |
2134 | if(*pos >= offset) { | |
2135 | /* the complete line is valid */ | |
2136 | *p += len; | |
2137 | *pos += len; | |
2138 | return; | |
2139 | } | |
2140 | if(*pos+len > offset) { | |
2141 | /* use the second part of the line */ | |
2142 | int i = offset-*pos; | |
2143 | memmove(*p,*p+i,len-i); | |
2144 | *p += len-i; | |
2145 | *pos += len; | |
2146 | return; | |
2147 | } | |
2148 | /* discard the complete line */ | |
2149 | *pos += len; | |
2150 | } | |
2151 | ||
2152 | /** | |
2153 | * get_locks_status - reports lock usage in /proc/locks | |
2154 | * @buffer: address in userspace to write into | |
2155 | * @start: ? | |
2156 | * @offset: how far we are through the buffer | |
2157 | * @length: how much to read | |
2158 | */ | |
2159 | ||
2160 | int get_locks_status(char *buffer, char **start, off_t offset, int length) | |
2161 | { | |
2162 | struct list_head *tmp; | |
2163 | char *q = buffer; | |
2164 | off_t pos = 0; | |
2165 | int i = 0; | |
2166 | ||
2167 | lock_kernel(); | |
2168 | list_for_each(tmp, &file_lock_list) { | |
2169 | struct list_head *btmp; | |
2170 | struct file_lock *fl = list_entry(tmp, struct file_lock, fl_link); | |
2171 | lock_get_status(q, fl, ++i, ""); | |
2172 | move_lock_status(&q, &pos, offset); | |
2173 | ||
2174 | if(pos >= offset+length) | |
2175 | goto done; | |
2176 | ||
2177 | list_for_each(btmp, &fl->fl_block) { | |
2178 | struct file_lock *bfl = list_entry(btmp, | |
2179 | struct file_lock, fl_block); | |
2180 | lock_get_status(q, bfl, i, " ->"); | |
2181 | move_lock_status(&q, &pos, offset); | |
2182 | ||
2183 | if(pos >= offset+length) | |
2184 | goto done; | |
2185 | } | |
2186 | } | |
2187 | done: | |
2188 | unlock_kernel(); | |
2189 | *start = buffer; | |
2190 | if(q-buffer < length) | |
2191 | return (q-buffer); | |
2192 | return length; | |
2193 | } | |
2194 | ||
2195 | /** | |
2196 | * lock_may_read - checks that the region is free of locks | |
2197 | * @inode: the inode that is being read | |
2198 | * @start: the first byte to read | |
2199 | * @len: the number of bytes to read | |
2200 | * | |
2201 | * Emulates Windows locking requirements. Whole-file | |
2202 | * mandatory locks (share modes) can prohibit a read and | |
2203 | * byte-range POSIX locks can prohibit a read if they overlap. | |
2204 | * | |
2205 | * N.B. this function is only ever called | |
2206 | * from knfsd and ownership of locks is never checked. | |
2207 | */ | |
2208 | int lock_may_read(struct inode *inode, loff_t start, unsigned long len) | |
2209 | { | |
2210 | struct file_lock *fl; | |
2211 | int result = 1; | |
2212 | lock_kernel(); | |
2213 | for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) { | |
2214 | if (IS_POSIX(fl)) { | |
2215 | if (fl->fl_type == F_RDLCK) | |
2216 | continue; | |
2217 | if ((fl->fl_end < start) || (fl->fl_start > (start + len))) | |
2218 | continue; | |
2219 | } else if (IS_FLOCK(fl)) { | |
2220 | if (!(fl->fl_type & LOCK_MAND)) | |
2221 | continue; | |
2222 | if (fl->fl_type & LOCK_READ) | |
2223 | continue; | |
2224 | } else | |
2225 | continue; | |
2226 | result = 0; | |
2227 | break; | |
2228 | } | |
2229 | unlock_kernel(); | |
2230 | return result; | |
2231 | } | |
2232 | ||
2233 | EXPORT_SYMBOL(lock_may_read); | |
2234 | ||
2235 | /** | |
2236 | * lock_may_write - checks that the region is free of locks | |
2237 | * @inode: the inode that is being written | |
2238 | * @start: the first byte to write | |
2239 | * @len: the number of bytes to write | |
2240 | * | |
2241 | * Emulates Windows locking requirements. Whole-file | |
2242 | * mandatory locks (share modes) can prohibit a write and | |
2243 | * byte-range POSIX locks can prohibit a write if they overlap. | |
2244 | * | |
2245 | * N.B. this function is only ever called | |
2246 | * from knfsd and ownership of locks is never checked. | |
2247 | */ | |
2248 | int lock_may_write(struct inode *inode, loff_t start, unsigned long len) | |
2249 | { | |
2250 | struct file_lock *fl; | |
2251 | int result = 1; | |
2252 | lock_kernel(); | |
2253 | for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) { | |
2254 | if (IS_POSIX(fl)) { | |
2255 | if ((fl->fl_end < start) || (fl->fl_start > (start + len))) | |
2256 | continue; | |
2257 | } else if (IS_FLOCK(fl)) { | |
2258 | if (!(fl->fl_type & LOCK_MAND)) | |
2259 | continue; | |
2260 | if (fl->fl_type & LOCK_WRITE) | |
2261 | continue; | |
2262 | } else | |
2263 | continue; | |
2264 | result = 0; | |
2265 | break; | |
2266 | } | |
2267 | unlock_kernel(); | |
2268 | return result; | |
2269 | } | |
2270 | ||
2271 | EXPORT_SYMBOL(lock_may_write); | |
2272 | ||
1da177e4 LT |
2273 | static int __init filelock_init(void) |
2274 | { | |
2275 | filelock_cache = kmem_cache_create("file_lock_cache", | |
2276 | sizeof(struct file_lock), 0, SLAB_PANIC, | |
2277 | init_once, NULL); | |
2278 | return 0; | |
2279 | } | |
2280 | ||
2281 | core_initcall(filelock_init); |