Commit | Line | Data |
---|---|---|
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 | ||
fa3536cc | 145 | static kmem_cache_t *filelock_cache __read_mostly; |
1da177e4 LT |
146 | |
147 | /* Allocate an empty lock structure. */ | |
148 | static struct file_lock *locks_alloc_lock(void) | |
149 | { | |
150 | return kmem_cache_alloc(filelock_cache, SLAB_KERNEL); | |
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 LT |
170 | { |
171 | if (fl == NULL) { | |
172 | BUG(); | |
173 | return; | |
174 | } | |
175 | if (waitqueue_active(&fl->fl_wait)) | |
176 | panic("Attempting to free lock with active wait queue"); | |
177 | ||
178 | if (!list_empty(&fl->fl_block)) | |
179 | panic("Attempting to free lock with active block list"); | |
180 | ||
181 | if (!list_empty(&fl->fl_link)) | |
182 | panic("Attempting to free lock on active lock list"); | |
183 | ||
47831f35 | 184 | locks_release_private(fl); |
1da177e4 LT |
185 | kmem_cache_free(filelock_cache, fl); |
186 | } | |
187 | ||
188 | void locks_init_lock(struct file_lock *fl) | |
189 | { | |
190 | INIT_LIST_HEAD(&fl->fl_link); | |
191 | INIT_LIST_HEAD(&fl->fl_block); | |
192 | init_waitqueue_head(&fl->fl_wait); | |
193 | fl->fl_next = NULL; | |
194 | fl->fl_fasync = NULL; | |
195 | fl->fl_owner = NULL; | |
196 | fl->fl_pid = 0; | |
197 | fl->fl_file = NULL; | |
198 | fl->fl_flags = 0; | |
199 | fl->fl_type = 0; | |
200 | fl->fl_start = fl->fl_end = 0; | |
201 | fl->fl_ops = NULL; | |
202 | fl->fl_lmops = NULL; | |
203 | } | |
204 | ||
205 | EXPORT_SYMBOL(locks_init_lock); | |
206 | ||
207 | /* | |
208 | * Initialises the fields of the file lock which are invariant for | |
209 | * free file_locks. | |
210 | */ | |
211 | static void init_once(void *foo, kmem_cache_t *cache, unsigned long flags) | |
212 | { | |
213 | struct file_lock *lock = (struct file_lock *) foo; | |
214 | ||
215 | if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) != | |
216 | SLAB_CTOR_CONSTRUCTOR) | |
217 | return; | |
218 | ||
219 | locks_init_lock(lock); | |
220 | } | |
221 | ||
47831f35 TM |
222 | static void locks_copy_private(struct file_lock *new, struct file_lock *fl) |
223 | { | |
224 | if (fl->fl_ops) { | |
225 | if (fl->fl_ops->fl_copy_lock) | |
226 | fl->fl_ops->fl_copy_lock(new, fl); | |
227 | new->fl_ops = fl->fl_ops; | |
228 | } | |
229 | if (fl->fl_lmops) { | |
230 | if (fl->fl_lmops->fl_copy_lock) | |
231 | fl->fl_lmops->fl_copy_lock(new, fl); | |
232 | new->fl_lmops = fl->fl_lmops; | |
233 | } | |
234 | } | |
235 | ||
1da177e4 LT |
236 | /* |
237 | * Initialize a new lock from an existing file_lock structure. | |
238 | */ | |
0996905f | 239 | static void __locks_copy_lock(struct file_lock *new, const struct file_lock *fl) |
1da177e4 LT |
240 | { |
241 | new->fl_owner = fl->fl_owner; | |
242 | new->fl_pid = fl->fl_pid; | |
0996905f | 243 | new->fl_file = NULL; |
1da177e4 LT |
244 | new->fl_flags = fl->fl_flags; |
245 | new->fl_type = fl->fl_type; | |
246 | new->fl_start = fl->fl_start; | |
247 | new->fl_end = fl->fl_end; | |
0996905f TM |
248 | new->fl_ops = NULL; |
249 | new->fl_lmops = NULL; | |
250 | } | |
251 | ||
252 | void locks_copy_lock(struct file_lock *new, struct file_lock *fl) | |
253 | { | |
254 | locks_release_private(new); | |
255 | ||
256 | __locks_copy_lock(new, fl); | |
257 | new->fl_file = fl->fl_file; | |
1da177e4 LT |
258 | new->fl_ops = fl->fl_ops; |
259 | new->fl_lmops = fl->fl_lmops; | |
47831f35 TM |
260 | |
261 | locks_copy_private(new, fl); | |
1da177e4 LT |
262 | } |
263 | ||
264 | EXPORT_SYMBOL(locks_copy_lock); | |
265 | ||
266 | static inline int flock_translate_cmd(int cmd) { | |
267 | if (cmd & LOCK_MAND) | |
268 | return cmd & (LOCK_MAND | LOCK_RW); | |
269 | switch (cmd) { | |
270 | case LOCK_SH: | |
271 | return F_RDLCK; | |
272 | case LOCK_EX: | |
273 | return F_WRLCK; | |
274 | case LOCK_UN: | |
275 | return F_UNLCK; | |
276 | } | |
277 | return -EINVAL; | |
278 | } | |
279 | ||
280 | /* Fill in a file_lock structure with an appropriate FLOCK lock. */ | |
281 | static int flock_make_lock(struct file *filp, struct file_lock **lock, | |
282 | unsigned int cmd) | |
283 | { | |
284 | struct file_lock *fl; | |
285 | int type = flock_translate_cmd(cmd); | |
286 | if (type < 0) | |
287 | return type; | |
288 | ||
289 | fl = locks_alloc_lock(); | |
290 | if (fl == NULL) | |
291 | return -ENOMEM; | |
292 | ||
293 | fl->fl_file = filp; | |
294 | fl->fl_pid = current->tgid; | |
295 | fl->fl_flags = FL_FLOCK; | |
296 | fl->fl_type = type; | |
297 | fl->fl_end = OFFSET_MAX; | |
298 | ||
299 | *lock = fl; | |
300 | return 0; | |
301 | } | |
302 | ||
303 | static int assign_type(struct file_lock *fl, int type) | |
304 | { | |
305 | switch (type) { | |
306 | case F_RDLCK: | |
307 | case F_WRLCK: | |
308 | case F_UNLCK: | |
309 | fl->fl_type = type; | |
310 | break; | |
311 | default: | |
312 | return -EINVAL; | |
313 | } | |
314 | return 0; | |
315 | } | |
316 | ||
317 | /* Verify a "struct flock" and copy it to a "struct file_lock" as a POSIX | |
318 | * style lock. | |
319 | */ | |
320 | static int flock_to_posix_lock(struct file *filp, struct file_lock *fl, | |
321 | struct flock *l) | |
322 | { | |
323 | off_t start, end; | |
324 | ||
325 | switch (l->l_whence) { | |
326 | case 0: /*SEEK_SET*/ | |
327 | start = 0; | |
328 | break; | |
329 | case 1: /*SEEK_CUR*/ | |
330 | start = filp->f_pos; | |
331 | break; | |
332 | case 2: /*SEEK_END*/ | |
333 | start = i_size_read(filp->f_dentry->d_inode); | |
334 | break; | |
335 | default: | |
336 | return -EINVAL; | |
337 | } | |
338 | ||
339 | /* POSIX-1996 leaves the case l->l_len < 0 undefined; | |
340 | POSIX-2001 defines it. */ | |
341 | start += l->l_start; | |
4c780a46 TM |
342 | if (start < 0) |
343 | return -EINVAL; | |
344 | fl->fl_end = OFFSET_MAX; | |
345 | if (l->l_len > 0) { | |
346 | end = start + l->l_len - 1; | |
347 | fl->fl_end = end; | |
348 | } else if (l->l_len < 0) { | |
1da177e4 | 349 | end = start - 1; |
4c780a46 | 350 | fl->fl_end = end; |
1da177e4 | 351 | start += l->l_len; |
4c780a46 TM |
352 | if (start < 0) |
353 | return -EINVAL; | |
1da177e4 | 354 | } |
1da177e4 | 355 | fl->fl_start = start; /* we record the absolute position */ |
4c780a46 TM |
356 | if (fl->fl_end < fl->fl_start) |
357 | return -EOVERFLOW; | |
1da177e4 LT |
358 | |
359 | fl->fl_owner = current->files; | |
360 | fl->fl_pid = current->tgid; | |
361 | fl->fl_file = filp; | |
362 | fl->fl_flags = FL_POSIX; | |
363 | fl->fl_ops = NULL; | |
364 | fl->fl_lmops = NULL; | |
365 | ||
366 | return assign_type(fl, l->l_type); | |
367 | } | |
368 | ||
369 | #if BITS_PER_LONG == 32 | |
370 | static int flock64_to_posix_lock(struct file *filp, struct file_lock *fl, | |
371 | struct flock64 *l) | |
372 | { | |
373 | loff_t start; | |
374 | ||
375 | switch (l->l_whence) { | |
376 | case 0: /*SEEK_SET*/ | |
377 | start = 0; | |
378 | break; | |
379 | case 1: /*SEEK_CUR*/ | |
380 | start = filp->f_pos; | |
381 | break; | |
382 | case 2: /*SEEK_END*/ | |
383 | start = i_size_read(filp->f_dentry->d_inode); | |
384 | break; | |
385 | default: | |
386 | return -EINVAL; | |
387 | } | |
388 | ||
4c780a46 TM |
389 | start += l->l_start; |
390 | if (start < 0) | |
1da177e4 | 391 | return -EINVAL; |
4c780a46 TM |
392 | fl->fl_end = OFFSET_MAX; |
393 | if (l->l_len > 0) { | |
394 | fl->fl_end = start + l->l_len - 1; | |
395 | } else if (l->l_len < 0) { | |
396 | fl->fl_end = start - 1; | |
397 | start += l->l_len; | |
398 | if (start < 0) | |
399 | return -EINVAL; | |
400 | } | |
1da177e4 | 401 | fl->fl_start = start; /* we record the absolute position */ |
4c780a46 TM |
402 | if (fl->fl_end < fl->fl_start) |
403 | return -EOVERFLOW; | |
1da177e4 LT |
404 | |
405 | fl->fl_owner = current->files; | |
406 | fl->fl_pid = current->tgid; | |
407 | fl->fl_file = filp; | |
408 | fl->fl_flags = FL_POSIX; | |
409 | fl->fl_ops = NULL; | |
410 | fl->fl_lmops = NULL; | |
411 | ||
412 | switch (l->l_type) { | |
413 | case F_RDLCK: | |
414 | case F_WRLCK: | |
415 | case F_UNLCK: | |
416 | fl->fl_type = l->l_type; | |
417 | break; | |
418 | default: | |
419 | return -EINVAL; | |
420 | } | |
421 | ||
422 | return (0); | |
423 | } | |
424 | #endif | |
425 | ||
426 | /* default lease lock manager operations */ | |
427 | static void lease_break_callback(struct file_lock *fl) | |
428 | { | |
429 | kill_fasync(&fl->fl_fasync, SIGIO, POLL_MSG); | |
430 | } | |
431 | ||
432 | static void lease_release_private_callback(struct file_lock *fl) | |
433 | { | |
434 | if (!fl->fl_file) | |
435 | return; | |
436 | ||
437 | f_delown(fl->fl_file); | |
438 | fl->fl_file->f_owner.signum = 0; | |
439 | } | |
440 | ||
75c96f85 | 441 | static int lease_mylease_callback(struct file_lock *fl, struct file_lock *try) |
1da177e4 LT |
442 | { |
443 | return fl->fl_file == try->fl_file; | |
444 | } | |
445 | ||
75c96f85 | 446 | static struct lock_manager_operations lease_manager_ops = { |
1da177e4 LT |
447 | .fl_break = lease_break_callback, |
448 | .fl_release_private = lease_release_private_callback, | |
449 | .fl_mylease = lease_mylease_callback, | |
450 | .fl_change = lease_modify, | |
451 | }; | |
452 | ||
453 | /* | |
454 | * Initialize a lease, use the default lock manager operations | |
455 | */ | |
456 | static int lease_init(struct file *filp, int type, struct file_lock *fl) | |
457 | { | |
458 | fl->fl_owner = current->files; | |
459 | fl->fl_pid = current->tgid; | |
460 | ||
461 | fl->fl_file = filp; | |
462 | fl->fl_flags = FL_LEASE; | |
463 | if (assign_type(fl, type) != 0) { | |
464 | locks_free_lock(fl); | |
465 | return -EINVAL; | |
466 | } | |
467 | fl->fl_start = 0; | |
468 | fl->fl_end = OFFSET_MAX; | |
469 | fl->fl_ops = NULL; | |
470 | fl->fl_lmops = &lease_manager_ops; | |
471 | return 0; | |
472 | } | |
473 | ||
474 | /* Allocate a file_lock initialised to this type of lease */ | |
475 | static int lease_alloc(struct file *filp, int type, struct file_lock **flp) | |
476 | { | |
477 | struct file_lock *fl = locks_alloc_lock(); | |
478 | int error; | |
479 | ||
480 | if (fl == NULL) | |
481 | return -ENOMEM; | |
482 | ||
483 | error = lease_init(filp, type, fl); | |
484 | if (error) | |
485 | return error; | |
486 | *flp = fl; | |
487 | return 0; | |
488 | } | |
489 | ||
490 | /* Check if two locks overlap each other. | |
491 | */ | |
492 | static inline int locks_overlap(struct file_lock *fl1, struct file_lock *fl2) | |
493 | { | |
494 | return ((fl1->fl_end >= fl2->fl_start) && | |
495 | (fl2->fl_end >= fl1->fl_start)); | |
496 | } | |
497 | ||
498 | /* | |
499 | * Check whether two locks have the same owner. | |
500 | */ | |
33443c42 | 501 | static int posix_same_owner(struct file_lock *fl1, struct file_lock *fl2) |
1da177e4 LT |
502 | { |
503 | if (fl1->fl_lmops && fl1->fl_lmops->fl_compare_owner) | |
504 | return fl2->fl_lmops == fl1->fl_lmops && | |
505 | fl1->fl_lmops->fl_compare_owner(fl1, fl2); | |
506 | return fl1->fl_owner == fl2->fl_owner; | |
507 | } | |
508 | ||
509 | /* Remove waiter from blocker's block list. | |
510 | * When blocker ends up pointing to itself then the list is empty. | |
511 | */ | |
33443c42 | 512 | static void __locks_delete_block(struct file_lock *waiter) |
1da177e4 LT |
513 | { |
514 | list_del_init(&waiter->fl_block); | |
515 | list_del_init(&waiter->fl_link); | |
516 | waiter->fl_next = NULL; | |
517 | } | |
518 | ||
519 | /* | |
520 | */ | |
521 | static void locks_delete_block(struct file_lock *waiter) | |
522 | { | |
523 | lock_kernel(); | |
524 | __locks_delete_block(waiter); | |
525 | unlock_kernel(); | |
526 | } | |
527 | ||
528 | /* Insert waiter into blocker's block list. | |
529 | * We use a circular list so that processes can be easily woken up in | |
530 | * the order they blocked. The documentation doesn't require this but | |
531 | * it seems like the reasonable thing to do. | |
532 | */ | |
533 | static void locks_insert_block(struct file_lock *blocker, | |
534 | struct file_lock *waiter) | |
535 | { | |
6dc0fe8f | 536 | BUG_ON(!list_empty(&waiter->fl_block)); |
1da177e4 LT |
537 | list_add_tail(&waiter->fl_block, &blocker->fl_block); |
538 | waiter->fl_next = blocker; | |
539 | if (IS_POSIX(blocker)) | |
540 | list_add(&waiter->fl_link, &blocked_list); | |
541 | } | |
542 | ||
543 | /* Wake up processes blocked waiting for blocker. | |
544 | * If told to wait then schedule the processes until the block list | |
545 | * is empty, otherwise empty the block list ourselves. | |
546 | */ | |
547 | static void locks_wake_up_blocks(struct file_lock *blocker) | |
548 | { | |
549 | while (!list_empty(&blocker->fl_block)) { | |
550 | struct file_lock *waiter = list_entry(blocker->fl_block.next, | |
551 | struct file_lock, fl_block); | |
552 | __locks_delete_block(waiter); | |
553 | if (waiter->fl_lmops && waiter->fl_lmops->fl_notify) | |
554 | waiter->fl_lmops->fl_notify(waiter); | |
555 | else | |
556 | wake_up(&waiter->fl_wait); | |
557 | } | |
558 | } | |
559 | ||
560 | /* Insert file lock fl into an inode's lock list at the position indicated | |
561 | * by pos. At the same time add the lock to the global file lock list. | |
562 | */ | |
563 | static void locks_insert_lock(struct file_lock **pos, struct file_lock *fl) | |
564 | { | |
565 | list_add(&fl->fl_link, &file_lock_list); | |
566 | ||
567 | /* insert into file's list */ | |
568 | fl->fl_next = *pos; | |
569 | *pos = fl; | |
570 | ||
571 | if (fl->fl_ops && fl->fl_ops->fl_insert) | |
572 | fl->fl_ops->fl_insert(fl); | |
573 | } | |
574 | ||
575 | /* | |
576 | * Delete a lock and then free it. | |
577 | * Wake up processes that are blocked waiting for this lock, | |
578 | * notify the FS that the lock has been cleared and | |
579 | * finally free the lock. | |
580 | */ | |
581 | static void locks_delete_lock(struct file_lock **thisfl_p) | |
582 | { | |
583 | struct file_lock *fl = *thisfl_p; | |
584 | ||
585 | *thisfl_p = fl->fl_next; | |
586 | fl->fl_next = NULL; | |
587 | list_del_init(&fl->fl_link); | |
588 | ||
589 | fasync_helper(0, fl->fl_file, 0, &fl->fl_fasync); | |
590 | if (fl->fl_fasync != NULL) { | |
591 | printk(KERN_ERR "locks_delete_lock: fasync == %p\n", fl->fl_fasync); | |
592 | fl->fl_fasync = NULL; | |
593 | } | |
594 | ||
595 | if (fl->fl_ops && fl->fl_ops->fl_remove) | |
596 | fl->fl_ops->fl_remove(fl); | |
597 | ||
598 | locks_wake_up_blocks(fl); | |
599 | locks_free_lock(fl); | |
600 | } | |
601 | ||
602 | /* Determine if lock sys_fl blocks lock caller_fl. Common functionality | |
603 | * checks for shared/exclusive status of overlapping locks. | |
604 | */ | |
605 | static int locks_conflict(struct file_lock *caller_fl, struct file_lock *sys_fl) | |
606 | { | |
607 | if (sys_fl->fl_type == F_WRLCK) | |
608 | return 1; | |
609 | if (caller_fl->fl_type == F_WRLCK) | |
610 | return 1; | |
611 | return 0; | |
612 | } | |
613 | ||
614 | /* Determine if lock sys_fl blocks lock caller_fl. POSIX specific | |
615 | * checking before calling the locks_conflict(). | |
616 | */ | |
617 | static int posix_locks_conflict(struct file_lock *caller_fl, struct file_lock *sys_fl) | |
618 | { | |
619 | /* POSIX locks owned by the same process do not conflict with | |
620 | * each other. | |
621 | */ | |
622 | if (!IS_POSIX(sys_fl) || posix_same_owner(caller_fl, sys_fl)) | |
623 | return (0); | |
624 | ||
625 | /* Check whether they overlap */ | |
626 | if (!locks_overlap(caller_fl, sys_fl)) | |
627 | return 0; | |
628 | ||
629 | return (locks_conflict(caller_fl, sys_fl)); | |
630 | } | |
631 | ||
632 | /* Determine if lock sys_fl blocks lock caller_fl. FLOCK specific | |
633 | * checking before calling the locks_conflict(). | |
634 | */ | |
635 | static int flock_locks_conflict(struct file_lock *caller_fl, struct file_lock *sys_fl) | |
636 | { | |
637 | /* FLOCK locks referring to the same filp do not conflict with | |
638 | * each other. | |
639 | */ | |
640 | if (!IS_FLOCK(sys_fl) || (caller_fl->fl_file == sys_fl->fl_file)) | |
641 | return (0); | |
642 | if ((caller_fl->fl_type & LOCK_MAND) || (sys_fl->fl_type & LOCK_MAND)) | |
643 | return 0; | |
644 | ||
645 | return (locks_conflict(caller_fl, sys_fl)); | |
646 | } | |
647 | ||
648 | static int interruptible_sleep_on_locked(wait_queue_head_t *fl_wait, int timeout) | |
649 | { | |
650 | int result = 0; | |
651 | DECLARE_WAITQUEUE(wait, current); | |
652 | ||
653 | __set_current_state(TASK_INTERRUPTIBLE); | |
654 | add_wait_queue(fl_wait, &wait); | |
655 | if (timeout == 0) | |
656 | schedule(); | |
657 | else | |
658 | result = schedule_timeout(timeout); | |
659 | if (signal_pending(current)) | |
660 | result = -ERESTARTSYS; | |
661 | remove_wait_queue(fl_wait, &wait); | |
662 | __set_current_state(TASK_RUNNING); | |
663 | return result; | |
664 | } | |
665 | ||
666 | static int locks_block_on_timeout(struct file_lock *blocker, struct file_lock *waiter, int time) | |
667 | { | |
668 | int result; | |
669 | locks_insert_block(blocker, waiter); | |
670 | result = interruptible_sleep_on_locked(&waiter->fl_wait, time); | |
671 | __locks_delete_block(waiter); | |
672 | return result; | |
673 | } | |
674 | ||
8dc7c311 AA |
675 | int |
676 | posix_test_lock(struct file *filp, struct file_lock *fl, | |
677 | struct file_lock *conflock) | |
1da177e4 LT |
678 | { |
679 | struct file_lock *cfl; | |
680 | ||
681 | lock_kernel(); | |
682 | for (cfl = filp->f_dentry->d_inode->i_flock; cfl; cfl = cfl->fl_next) { | |
683 | if (!IS_POSIX(cfl)) | |
684 | continue; | |
685 | if (posix_locks_conflict(cfl, fl)) | |
686 | break; | |
687 | } | |
8dc7c311 | 688 | if (cfl) { |
0996905f | 689 | __locks_copy_lock(conflock, cfl); |
8dc7c311 AA |
690 | unlock_kernel(); |
691 | return 1; | |
692 | } | |
1da177e4 | 693 | unlock_kernel(); |
8dc7c311 | 694 | return 0; |
1da177e4 LT |
695 | } |
696 | ||
697 | EXPORT_SYMBOL(posix_test_lock); | |
698 | ||
699 | /* This function tests for deadlock condition before putting a process to | |
700 | * sleep. The detection scheme is no longer recursive. Recursive was neat, | |
701 | * but dangerous - we risked stack corruption if the lock data was bad, or | |
702 | * if the recursion was too deep for any other reason. | |
703 | * | |
704 | * We rely on the fact that a task can only be on one lock's wait queue | |
705 | * at a time. When we find blocked_task on a wait queue we can re-search | |
706 | * with blocked_task equal to that queue's owner, until either blocked_task | |
707 | * isn't found, or blocked_task is found on a queue owned by my_task. | |
708 | * | |
709 | * Note: the above assumption may not be true when handling lock requests | |
710 | * from a broken NFS client. But broken NFS clients have a lot more to | |
711 | * worry about than proper deadlock detection anyway... --okir | |
712 | */ | |
713 | int posix_locks_deadlock(struct file_lock *caller_fl, | |
714 | struct file_lock *block_fl) | |
715 | { | |
716 | struct list_head *tmp; | |
717 | ||
718 | next_task: | |
719 | if (posix_same_owner(caller_fl, block_fl)) | |
720 | return 1; | |
721 | list_for_each(tmp, &blocked_list) { | |
722 | struct file_lock *fl = list_entry(tmp, struct file_lock, fl_link); | |
723 | if (posix_same_owner(fl, block_fl)) { | |
724 | fl = fl->fl_next; | |
725 | block_fl = fl; | |
726 | goto next_task; | |
727 | } | |
728 | } | |
729 | return 0; | |
730 | } | |
731 | ||
732 | EXPORT_SYMBOL(posix_locks_deadlock); | |
733 | ||
734 | /* Try to create a FLOCK lock on filp. We always insert new FLOCK locks | |
735 | * at the head of the list, but that's secret knowledge known only to | |
736 | * flock_lock_file and posix_lock_file. | |
737 | */ | |
738 | static int flock_lock_file(struct file *filp, struct file_lock *new_fl) | |
739 | { | |
740 | struct file_lock **before; | |
741 | struct inode * inode = filp->f_dentry->d_inode; | |
742 | int error = 0; | |
743 | int found = 0; | |
744 | ||
745 | lock_kernel(); | |
746 | for_each_lock(inode, before) { | |
747 | struct file_lock *fl = *before; | |
748 | if (IS_POSIX(fl)) | |
749 | break; | |
750 | if (IS_LEASE(fl)) | |
751 | continue; | |
752 | if (filp != fl->fl_file) | |
753 | continue; | |
754 | if (new_fl->fl_type == fl->fl_type) | |
755 | goto out; | |
756 | found = 1; | |
757 | locks_delete_lock(before); | |
758 | break; | |
759 | } | |
760 | unlock_kernel(); | |
761 | ||
762 | if (new_fl->fl_type == F_UNLCK) | |
763 | return 0; | |
764 | ||
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 | ||
772 | lock_kernel(); | |
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; | |
779 | if (!flock_locks_conflict(new_fl, fl)) | |
780 | continue; | |
781 | error = -EAGAIN; | |
782 | if (new_fl->fl_flags & FL_SLEEP) { | |
783 | locks_insert_block(fl, new_fl); | |
784 | } | |
785 | goto out; | |
786 | } | |
787 | locks_insert_lock(&inode->i_flock, new_fl); | |
788 | error = 0; | |
789 | ||
790 | out: | |
791 | unlock_kernel(); | |
792 | return error; | |
793 | } | |
794 | ||
5842add2 | 795 | static int __posix_lock_file_conf(struct inode *inode, struct file_lock *request, struct file_lock *conflock) |
1da177e4 LT |
796 | { |
797 | struct file_lock *fl; | |
798 | struct file_lock *new_fl, *new_fl2; | |
799 | struct file_lock *left = NULL; | |
800 | struct file_lock *right = NULL; | |
801 | struct file_lock **before; | |
802 | int error, added = 0; | |
803 | ||
804 | /* | |
805 | * We may need two file_lock structures for this operation, | |
806 | * so we get them in advance to avoid races. | |
807 | */ | |
808 | new_fl = locks_alloc_lock(); | |
809 | new_fl2 = locks_alloc_lock(); | |
810 | ||
811 | lock_kernel(); | |
812 | if (request->fl_type != F_UNLCK) { | |
813 | for_each_lock(inode, before) { | |
814 | struct file_lock *fl = *before; | |
815 | if (!IS_POSIX(fl)) | |
816 | continue; | |
817 | if (!posix_locks_conflict(request, fl)) | |
818 | continue; | |
5842add2 AA |
819 | if (conflock) |
820 | locks_copy_lock(conflock, fl); | |
1da177e4 LT |
821 | error = -EAGAIN; |
822 | if (!(request->fl_flags & FL_SLEEP)) | |
823 | goto out; | |
824 | error = -EDEADLK; | |
825 | if (posix_locks_deadlock(request, fl)) | |
826 | goto out; | |
827 | error = -EAGAIN; | |
828 | locks_insert_block(fl, request); | |
829 | goto out; | |
830 | } | |
831 | } | |
832 | ||
833 | /* If we're just looking for a conflict, we're done. */ | |
834 | error = 0; | |
835 | if (request->fl_flags & FL_ACCESS) | |
836 | goto out; | |
837 | ||
838 | error = -ENOLCK; /* "no luck" */ | |
839 | if (!(new_fl && new_fl2)) | |
840 | goto out; | |
841 | ||
842 | /* | |
843 | * We've allocated the new locks in advance, so there are no | |
844 | * errors possible (and no blocking operations) from here on. | |
845 | * | |
846 | * Find the first old lock with the same owner as the new lock. | |
847 | */ | |
848 | ||
849 | before = &inode->i_flock; | |
850 | ||
851 | /* First skip locks owned by other processes. */ | |
852 | while ((fl = *before) && (!IS_POSIX(fl) || | |
853 | !posix_same_owner(request, fl))) { | |
854 | before = &fl->fl_next; | |
855 | } | |
856 | ||
857 | /* Process locks with this owner. */ | |
858 | while ((fl = *before) && posix_same_owner(request, fl)) { | |
859 | /* Detect adjacent or overlapping regions (if same lock type) | |
860 | */ | |
861 | if (request->fl_type == fl->fl_type) { | |
449231d6 OK |
862 | /* In all comparisons of start vs end, use |
863 | * "start - 1" rather than "end + 1". If end | |
864 | * is OFFSET_MAX, end + 1 will become negative. | |
865 | */ | |
1da177e4 LT |
866 | if (fl->fl_end < request->fl_start - 1) |
867 | goto next_lock; | |
868 | /* If the next lock in the list has entirely bigger | |
869 | * addresses than the new one, insert the lock here. | |
870 | */ | |
449231d6 | 871 | if (fl->fl_start - 1 > request->fl_end) |
1da177e4 LT |
872 | break; |
873 | ||
874 | /* If we come here, the new and old lock are of the | |
875 | * same type and adjacent or overlapping. Make one | |
876 | * lock yielding from the lower start address of both | |
877 | * locks to the higher end address. | |
878 | */ | |
879 | if (fl->fl_start > request->fl_start) | |
880 | fl->fl_start = request->fl_start; | |
881 | else | |
882 | request->fl_start = fl->fl_start; | |
883 | if (fl->fl_end < request->fl_end) | |
884 | fl->fl_end = request->fl_end; | |
885 | else | |
886 | request->fl_end = fl->fl_end; | |
887 | if (added) { | |
888 | locks_delete_lock(before); | |
889 | continue; | |
890 | } | |
891 | request = fl; | |
892 | added = 1; | |
893 | } | |
894 | else { | |
895 | /* Processing for different lock types is a bit | |
896 | * more complex. | |
897 | */ | |
898 | if (fl->fl_end < request->fl_start) | |
899 | goto next_lock; | |
900 | if (fl->fl_start > request->fl_end) | |
901 | break; | |
902 | if (request->fl_type == F_UNLCK) | |
903 | added = 1; | |
904 | if (fl->fl_start < request->fl_start) | |
905 | left = fl; | |
906 | /* If the next lock in the list has a higher end | |
907 | * address than the new one, insert the new one here. | |
908 | */ | |
909 | if (fl->fl_end > request->fl_end) { | |
910 | right = fl; | |
911 | break; | |
912 | } | |
913 | if (fl->fl_start >= request->fl_start) { | |
914 | /* The new lock completely replaces an old | |
915 | * one (This may happen several times). | |
916 | */ | |
917 | if (added) { | |
918 | locks_delete_lock(before); | |
919 | continue; | |
920 | } | |
921 | /* Replace the old lock with the new one. | |
922 | * Wake up anybody waiting for the old one, | |
923 | * as the change in lock type might satisfy | |
924 | * their needs. | |
925 | */ | |
926 | locks_wake_up_blocks(fl); | |
927 | fl->fl_start = request->fl_start; | |
928 | fl->fl_end = request->fl_end; | |
929 | fl->fl_type = request->fl_type; | |
47831f35 TM |
930 | locks_release_private(fl); |
931 | locks_copy_private(fl, request); | |
1da177e4 LT |
932 | request = fl; |
933 | added = 1; | |
934 | } | |
935 | } | |
936 | /* Go on to next lock. | |
937 | */ | |
938 | next_lock: | |
939 | before = &fl->fl_next; | |
940 | } | |
941 | ||
942 | error = 0; | |
943 | if (!added) { | |
944 | if (request->fl_type == F_UNLCK) | |
945 | goto out; | |
946 | locks_copy_lock(new_fl, request); | |
947 | locks_insert_lock(before, new_fl); | |
948 | new_fl = NULL; | |
949 | } | |
950 | if (right) { | |
951 | if (left == right) { | |
952 | /* The new lock breaks the old one in two pieces, | |
953 | * so we have to use the second new lock. | |
954 | */ | |
955 | left = new_fl2; | |
956 | new_fl2 = NULL; | |
957 | locks_copy_lock(left, right); | |
958 | locks_insert_lock(before, left); | |
959 | } | |
960 | right->fl_start = request->fl_end + 1; | |
961 | locks_wake_up_blocks(right); | |
962 | } | |
963 | if (left) { | |
964 | left->fl_end = request->fl_start - 1; | |
965 | locks_wake_up_blocks(left); | |
966 | } | |
967 | out: | |
968 | unlock_kernel(); | |
969 | /* | |
970 | * Free any unused locks. | |
971 | */ | |
972 | if (new_fl) | |
973 | locks_free_lock(new_fl); | |
974 | if (new_fl2) | |
975 | locks_free_lock(new_fl2); | |
976 | return error; | |
977 | } | |
978 | ||
979 | /** | |
980 | * posix_lock_file - Apply a POSIX-style lock to a file | |
981 | * @filp: The file to apply the lock to | |
982 | * @fl: The lock to be applied | |
983 | * | |
984 | * Add a POSIX style lock to a file. | |
985 | * We merge adjacent & overlapping locks whenever possible. | |
986 | * POSIX locks are sorted by owner task, then by starting address | |
987 | */ | |
988 | int posix_lock_file(struct file *filp, struct file_lock *fl) | |
989 | { | |
5842add2 AA |
990 | return __posix_lock_file_conf(filp->f_dentry->d_inode, fl, NULL); |
991 | } | |
992 | EXPORT_SYMBOL(posix_lock_file); | |
993 | ||
994 | /** | |
995 | * posix_lock_file_conf - Apply a POSIX-style lock to a file | |
996 | * @filp: The file to apply the lock to | |
997 | * @fl: The lock to be applied | |
998 | * @conflock: Place to return a copy of the conflicting lock, if found. | |
999 | * | |
1000 | * Except for the conflock parameter, acts just like posix_lock_file. | |
1001 | */ | |
1002 | int posix_lock_file_conf(struct file *filp, struct file_lock *fl, | |
1003 | struct file_lock *conflock) | |
1004 | { | |
1005 | return __posix_lock_file_conf(filp->f_dentry->d_inode, fl, conflock); | |
1da177e4 | 1006 | } |
5842add2 | 1007 | EXPORT_SYMBOL(posix_lock_file_conf); |
1da177e4 LT |
1008 | |
1009 | /** | |
1010 | * posix_lock_file_wait - Apply a POSIX-style lock to a file | |
1011 | * @filp: The file to apply the lock to | |
1012 | * @fl: The lock to be applied | |
1013 | * | |
1014 | * Add a POSIX style lock to a file. | |
1015 | * We merge adjacent & overlapping locks whenever possible. | |
1016 | * POSIX locks are sorted by owner task, then by starting address | |
1017 | */ | |
1018 | int posix_lock_file_wait(struct file *filp, struct file_lock *fl) | |
1019 | { | |
1020 | int error; | |
1021 | might_sleep (); | |
1022 | for (;;) { | |
5842add2 | 1023 | error = posix_lock_file(filp, fl); |
1da177e4 LT |
1024 | if ((error != -EAGAIN) || !(fl->fl_flags & FL_SLEEP)) |
1025 | break; | |
1026 | error = wait_event_interruptible(fl->fl_wait, !fl->fl_next); | |
1027 | if (!error) | |
1028 | continue; | |
1029 | ||
1030 | locks_delete_block(fl); | |
1031 | break; | |
1032 | } | |
1033 | return error; | |
1034 | } | |
1035 | EXPORT_SYMBOL(posix_lock_file_wait); | |
1036 | ||
1037 | /** | |
1038 | * locks_mandatory_locked - Check for an active lock | |
1039 | * @inode: the file to check | |
1040 | * | |
1041 | * Searches the inode's list of locks to find any POSIX locks which conflict. | |
1042 | * This function is called from locks_verify_locked() only. | |
1043 | */ | |
1044 | int locks_mandatory_locked(struct inode *inode) | |
1045 | { | |
1046 | fl_owner_t owner = current->files; | |
1047 | struct file_lock *fl; | |
1048 | ||
1049 | /* | |
1050 | * Search the lock list for this inode for any POSIX locks. | |
1051 | */ | |
1052 | lock_kernel(); | |
1053 | for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) { | |
1054 | if (!IS_POSIX(fl)) | |
1055 | continue; | |
1056 | if (fl->fl_owner != owner) | |
1057 | break; | |
1058 | } | |
1059 | unlock_kernel(); | |
1060 | return fl ? -EAGAIN : 0; | |
1061 | } | |
1062 | ||
1063 | /** | |
1064 | * locks_mandatory_area - Check for a conflicting lock | |
1065 | * @read_write: %FLOCK_VERIFY_WRITE for exclusive access, %FLOCK_VERIFY_READ | |
1066 | * for shared | |
1067 | * @inode: the file to check | |
1068 | * @filp: how the file was opened (if it was) | |
1069 | * @offset: start of area to check | |
1070 | * @count: length of area to check | |
1071 | * | |
1072 | * Searches the inode's list of locks to find any POSIX locks which conflict. | |
1073 | * This function is called from rw_verify_area() and | |
1074 | * locks_verify_truncate(). | |
1075 | */ | |
1076 | int locks_mandatory_area(int read_write, struct inode *inode, | |
1077 | struct file *filp, loff_t offset, | |
1078 | size_t count) | |
1079 | { | |
1080 | struct file_lock fl; | |
1081 | int error; | |
1082 | ||
1083 | locks_init_lock(&fl); | |
1084 | fl.fl_owner = current->files; | |
1085 | fl.fl_pid = current->tgid; | |
1086 | fl.fl_file = filp; | |
1087 | fl.fl_flags = FL_POSIX | FL_ACCESS; | |
1088 | if (filp && !(filp->f_flags & O_NONBLOCK)) | |
1089 | fl.fl_flags |= FL_SLEEP; | |
1090 | fl.fl_type = (read_write == FLOCK_VERIFY_WRITE) ? F_WRLCK : F_RDLCK; | |
1091 | fl.fl_start = offset; | |
1092 | fl.fl_end = offset + count - 1; | |
1093 | ||
1094 | for (;;) { | |
5842add2 | 1095 | error = __posix_lock_file_conf(inode, &fl, NULL); |
1da177e4 LT |
1096 | if (error != -EAGAIN) |
1097 | break; | |
1098 | if (!(fl.fl_flags & FL_SLEEP)) | |
1099 | break; | |
1100 | error = wait_event_interruptible(fl.fl_wait, !fl.fl_next); | |
1101 | if (!error) { | |
1102 | /* | |
1103 | * If we've been sleeping someone might have | |
1104 | * changed the permissions behind our back. | |
1105 | */ | |
1106 | if ((inode->i_mode & (S_ISGID | S_IXGRP)) == S_ISGID) | |
1107 | continue; | |
1108 | } | |
1109 | ||
1110 | locks_delete_block(&fl); | |
1111 | break; | |
1112 | } | |
1113 | ||
1114 | return error; | |
1115 | } | |
1116 | ||
1117 | EXPORT_SYMBOL(locks_mandatory_area); | |
1118 | ||
1119 | /* We already had a lease on this file; just change its type */ | |
1120 | int lease_modify(struct file_lock **before, int arg) | |
1121 | { | |
1122 | struct file_lock *fl = *before; | |
1123 | int error = assign_type(fl, arg); | |
1124 | ||
1125 | if (error) | |
1126 | return error; | |
1127 | locks_wake_up_blocks(fl); | |
1128 | if (arg == F_UNLCK) | |
1129 | locks_delete_lock(before); | |
1130 | return 0; | |
1131 | } | |
1132 | ||
1133 | EXPORT_SYMBOL(lease_modify); | |
1134 | ||
1135 | static void time_out_leases(struct inode *inode) | |
1136 | { | |
1137 | struct file_lock **before; | |
1138 | struct file_lock *fl; | |
1139 | ||
1140 | before = &inode->i_flock; | |
1141 | while ((fl = *before) && IS_LEASE(fl) && (fl->fl_type & F_INPROGRESS)) { | |
1142 | if ((fl->fl_break_time == 0) | |
1143 | || time_before(jiffies, fl->fl_break_time)) { | |
1144 | before = &fl->fl_next; | |
1145 | continue; | |
1146 | } | |
1da177e4 LT |
1147 | lease_modify(before, fl->fl_type & ~F_INPROGRESS); |
1148 | if (fl == *before) /* lease_modify may have freed fl */ | |
1149 | before = &fl->fl_next; | |
1150 | } | |
1151 | } | |
1152 | ||
1153 | /** | |
1154 | * __break_lease - revoke all outstanding leases on file | |
1155 | * @inode: the inode of the file to return | |
1156 | * @mode: the open mode (read or write) | |
1157 | * | |
1158 | * break_lease (inlined for speed) has checked there already | |
1159 | * is a lease on this file. Leases are broken on a call to open() | |
1160 | * or truncate(). This function can sleep unless you | |
1161 | * specified %O_NONBLOCK to your open(). | |
1162 | */ | |
1163 | int __break_lease(struct inode *inode, unsigned int mode) | |
1164 | { | |
1165 | int error = 0, future; | |
1166 | struct file_lock *new_fl, *flock; | |
1167 | struct file_lock *fl; | |
1168 | int alloc_err; | |
1169 | unsigned long break_time; | |
1170 | int i_have_this_lease = 0; | |
1171 | ||
1172 | alloc_err = lease_alloc(NULL, mode & FMODE_WRITE ? F_WRLCK : F_RDLCK, | |
1173 | &new_fl); | |
1174 | ||
1175 | lock_kernel(); | |
1176 | ||
1177 | time_out_leases(inode); | |
1178 | ||
1179 | flock = inode->i_flock; | |
1180 | if ((flock == NULL) || !IS_LEASE(flock)) | |
1181 | goto out; | |
1182 | ||
1183 | for (fl = flock; fl && IS_LEASE(fl); fl = fl->fl_next) | |
1184 | if (fl->fl_owner == current->files) | |
1185 | i_have_this_lease = 1; | |
1186 | ||
1187 | if (mode & FMODE_WRITE) { | |
1188 | /* If we want write access, we have to revoke any lease. */ | |
1189 | future = F_UNLCK | F_INPROGRESS; | |
1190 | } else if (flock->fl_type & F_INPROGRESS) { | |
1191 | /* If the lease is already being broken, we just leave it */ | |
1192 | future = flock->fl_type; | |
1193 | } else if (flock->fl_type & F_WRLCK) { | |
1194 | /* Downgrade the exclusive lease to a read-only lease. */ | |
1195 | future = F_RDLCK | F_INPROGRESS; | |
1196 | } else { | |
1197 | /* the existing lease was read-only, so we can read too. */ | |
1198 | goto out; | |
1199 | } | |
1200 | ||
1201 | if (alloc_err && !i_have_this_lease && ((mode & O_NONBLOCK) == 0)) { | |
1202 | error = alloc_err; | |
1203 | goto out; | |
1204 | } | |
1205 | ||
1206 | break_time = 0; | |
1207 | if (lease_break_time > 0) { | |
1208 | break_time = jiffies + lease_break_time * HZ; | |
1209 | if (break_time == 0) | |
1210 | break_time++; /* so that 0 means no break time */ | |
1211 | } | |
1212 | ||
1213 | for (fl = flock; fl && IS_LEASE(fl); fl = fl->fl_next) { | |
1214 | if (fl->fl_type != future) { | |
1215 | fl->fl_type = future; | |
1216 | fl->fl_break_time = break_time; | |
1217 | /* lease must have lmops break callback */ | |
1218 | fl->fl_lmops->fl_break(fl); | |
1219 | } | |
1220 | } | |
1221 | ||
1222 | if (i_have_this_lease || (mode & O_NONBLOCK)) { | |
1223 | error = -EWOULDBLOCK; | |
1224 | goto out; | |
1225 | } | |
1226 | ||
1227 | restart: | |
1228 | break_time = flock->fl_break_time; | |
1229 | if (break_time != 0) { | |
1230 | break_time -= jiffies; | |
1231 | if (break_time == 0) | |
1232 | break_time++; | |
1233 | } | |
1234 | error = locks_block_on_timeout(flock, new_fl, break_time); | |
1235 | if (error >= 0) { | |
1236 | if (error == 0) | |
1237 | time_out_leases(inode); | |
1238 | /* Wait for the next lease that has not been broken yet */ | |
1239 | for (flock = inode->i_flock; flock && IS_LEASE(flock); | |
1240 | flock = flock->fl_next) { | |
1241 | if (flock->fl_type & F_INPROGRESS) | |
1242 | goto restart; | |
1243 | } | |
1244 | error = 0; | |
1245 | } | |
1246 | ||
1247 | out: | |
1248 | unlock_kernel(); | |
1249 | if (!alloc_err) | |
1250 | locks_free_lock(new_fl); | |
1251 | return error; | |
1252 | } | |
1253 | ||
1254 | EXPORT_SYMBOL(__break_lease); | |
1255 | ||
1256 | /** | |
1257 | * lease_get_mtime | |
1258 | * @inode: the inode | |
1259 | * @time: pointer to a timespec which will contain the last modified time | |
1260 | * | |
1261 | * This is to force NFS clients to flush their caches for files with | |
1262 | * exclusive leases. The justification is that if someone has an | |
1263 | * exclusive lease, then they could be modifiying it. | |
1264 | */ | |
1265 | void lease_get_mtime(struct inode *inode, struct timespec *time) | |
1266 | { | |
1267 | struct file_lock *flock = inode->i_flock; | |
1268 | if (flock && IS_LEASE(flock) && (flock->fl_type & F_WRLCK)) | |
1269 | *time = current_fs_time(inode->i_sb); | |
1270 | else | |
1271 | *time = inode->i_mtime; | |
1272 | } | |
1273 | ||
1274 | EXPORT_SYMBOL(lease_get_mtime); | |
1275 | ||
1276 | /** | |
1277 | * fcntl_getlease - Enquire what lease is currently active | |
1278 | * @filp: the file | |
1279 | * | |
1280 | * The value returned by this function will be one of | |
1281 | * (if no lease break is pending): | |
1282 | * | |
1283 | * %F_RDLCK to indicate a shared lease is held. | |
1284 | * | |
1285 | * %F_WRLCK to indicate an exclusive lease is held. | |
1286 | * | |
1287 | * %F_UNLCK to indicate no lease is held. | |
1288 | * | |
1289 | * (if a lease break is pending): | |
1290 | * | |
1291 | * %F_RDLCK to indicate an exclusive lease needs to be | |
1292 | * changed to a shared lease (or removed). | |
1293 | * | |
1294 | * %F_UNLCK to indicate the lease needs to be removed. | |
1295 | * | |
1296 | * XXX: sfr & willy disagree over whether F_INPROGRESS | |
1297 | * should be returned to userspace. | |
1298 | */ | |
1299 | int fcntl_getlease(struct file *filp) | |
1300 | { | |
1301 | struct file_lock *fl; | |
1302 | int type = F_UNLCK; | |
1303 | ||
1304 | lock_kernel(); | |
1305 | time_out_leases(filp->f_dentry->d_inode); | |
1306 | for (fl = filp->f_dentry->d_inode->i_flock; fl && IS_LEASE(fl); | |
1307 | fl = fl->fl_next) { | |
1308 | if (fl->fl_file == filp) { | |
1309 | type = fl->fl_type & ~F_INPROGRESS; | |
1310 | break; | |
1311 | } | |
1312 | } | |
1313 | unlock_kernel(); | |
1314 | return type; | |
1315 | } | |
1316 | ||
1317 | /** | |
1318 | * __setlease - sets a lease on an open file | |
1319 | * @filp: file pointer | |
1320 | * @arg: type of lease to obtain | |
1321 | * @flp: input - file_lock to use, output - file_lock inserted | |
1322 | * | |
1323 | * The (input) flp->fl_lmops->fl_break function is required | |
1324 | * by break_lease(). | |
1325 | * | |
1326 | * Called with kernel lock held. | |
1327 | */ | |
75c96f85 | 1328 | static int __setlease(struct file *filp, long arg, struct file_lock **flp) |
1da177e4 | 1329 | { |
7eaae282 | 1330 | struct file_lock *fl, **before, **my_before = NULL, *lease; |
1da177e4 LT |
1331 | struct dentry *dentry = filp->f_dentry; |
1332 | struct inode *inode = dentry->d_inode; | |
1333 | int error, rdlease_count = 0, wrlease_count = 0; | |
1334 | ||
1335 | time_out_leases(inode); | |
1336 | ||
1337 | error = -EINVAL; | |
1338 | if (!flp || !(*flp) || !(*flp)->fl_lmops || !(*flp)->fl_lmops->fl_break) | |
1339 | goto out; | |
1340 | ||
7eaae282 KZ |
1341 | lease = *flp; |
1342 | ||
1da177e4 LT |
1343 | error = -EAGAIN; |
1344 | if ((arg == F_RDLCK) && (atomic_read(&inode->i_writecount) > 0)) | |
1345 | goto out; | |
1346 | if ((arg == F_WRLCK) | |
1347 | && ((atomic_read(&dentry->d_count) > 1) | |
1348 | || (atomic_read(&inode->i_count) > 1))) | |
1349 | goto out; | |
1350 | ||
1351 | /* | |
1352 | * At this point, we know that if there is an exclusive | |
1353 | * lease on this file, then we hold it on this filp | |
1354 | * (otherwise our open of this file would have blocked). | |
1355 | * And if we are trying to acquire an exclusive lease, | |
1356 | * then the file is not open by anyone (including us) | |
1357 | * except for this filp. | |
1358 | */ | |
1359 | for (before = &inode->i_flock; | |
1360 | ((fl = *before) != NULL) && IS_LEASE(fl); | |
1361 | before = &fl->fl_next) { | |
1362 | if (lease->fl_lmops->fl_mylease(fl, lease)) | |
1363 | my_before = before; | |
1364 | else if (fl->fl_type == (F_INPROGRESS | F_UNLCK)) | |
1365 | /* | |
1366 | * Someone is in the process of opening this | |
1367 | * file for writing so we may not take an | |
1368 | * exclusive lease on it. | |
1369 | */ | |
1370 | wrlease_count++; | |
1371 | else | |
1372 | rdlease_count++; | |
1373 | } | |
1374 | ||
1375 | if ((arg == F_RDLCK && (wrlease_count > 0)) || | |
1376 | (arg == F_WRLCK && ((rdlease_count + wrlease_count) > 0))) | |
1377 | goto out; | |
1378 | ||
1379 | if (my_before != NULL) { | |
1380 | error = lease->fl_lmops->fl_change(my_before, arg); | |
1381 | goto out; | |
1382 | } | |
1383 | ||
1384 | error = 0; | |
1385 | if (arg == F_UNLCK) | |
1386 | goto out; | |
1387 | ||
1388 | error = -EINVAL; | |
1389 | if (!leases_enable) | |
1390 | goto out; | |
1391 | ||
1392 | error = lease_alloc(filp, arg, &fl); | |
1393 | if (error) | |
1394 | goto out; | |
1395 | ||
1396 | locks_copy_lock(fl, lease); | |
1397 | ||
1398 | locks_insert_lock(before, fl); | |
1399 | ||
1400 | *flp = fl; | |
1401 | out: | |
1402 | return error; | |
1403 | } | |
1404 | ||
1405 | /** | |
1406 | * setlease - sets a lease on an open file | |
1407 | * @filp: file pointer | |
1408 | * @arg: type of lease to obtain | |
1409 | * @lease: file_lock to use | |
1410 | * | |
1411 | * Call this to establish a lease on the file. | |
1412 | * The fl_lmops fl_break function is required by break_lease | |
1413 | */ | |
1414 | ||
1415 | int setlease(struct file *filp, long arg, struct file_lock **lease) | |
1416 | { | |
1417 | struct dentry *dentry = filp->f_dentry; | |
1418 | struct inode *inode = dentry->d_inode; | |
1419 | int error; | |
1420 | ||
1421 | if ((current->fsuid != inode->i_uid) && !capable(CAP_LEASE)) | |
1422 | return -EACCES; | |
1423 | if (!S_ISREG(inode->i_mode)) | |
1424 | return -EINVAL; | |
1425 | error = security_file_lock(filp, arg); | |
1426 | if (error) | |
1427 | return error; | |
1428 | ||
1429 | lock_kernel(); | |
1430 | error = __setlease(filp, arg, lease); | |
1431 | unlock_kernel(); | |
1432 | ||
1433 | return error; | |
1434 | } | |
1435 | ||
1436 | EXPORT_SYMBOL(setlease); | |
1437 | ||
1438 | /** | |
1439 | * fcntl_setlease - sets a lease on an open file | |
1440 | * @fd: open file descriptor | |
1441 | * @filp: file pointer | |
1442 | * @arg: type of lease to obtain | |
1443 | * | |
1444 | * Call this fcntl to establish a lease on the file. | |
1445 | * Note that you also need to call %F_SETSIG to | |
1446 | * receive a signal when the lease is broken. | |
1447 | */ | |
1448 | int fcntl_setlease(unsigned int fd, struct file *filp, long arg) | |
1449 | { | |
1450 | struct file_lock fl, *flp = &fl; | |
1451 | struct dentry *dentry = filp->f_dentry; | |
1452 | struct inode *inode = dentry->d_inode; | |
1453 | int error; | |
1454 | ||
1455 | if ((current->fsuid != inode->i_uid) && !capable(CAP_LEASE)) | |
1456 | return -EACCES; | |
1457 | if (!S_ISREG(inode->i_mode)) | |
1458 | return -EINVAL; | |
1459 | error = security_file_lock(filp, arg); | |
1460 | if (error) | |
1461 | return error; | |
1462 | ||
1463 | locks_init_lock(&fl); | |
1464 | error = lease_init(filp, arg, &fl); | |
1465 | if (error) | |
1466 | return error; | |
1467 | ||
1468 | lock_kernel(); | |
1469 | ||
1470 | error = __setlease(filp, arg, &flp); | |
dc15ae14 | 1471 | if (error || arg == F_UNLCK) |
1da177e4 LT |
1472 | goto out_unlock; |
1473 | ||
1474 | error = fasync_helper(fd, filp, 1, &flp->fl_fasync); | |
1475 | if (error < 0) { | |
1476 | /* remove lease just inserted by __setlease */ | |
1477 | flp->fl_type = F_UNLCK | F_INPROGRESS; | |
1478 | flp->fl_break_time = jiffies- 10; | |
1479 | time_out_leases(inode); | |
1480 | goto out_unlock; | |
1481 | } | |
1482 | ||
1483 | error = f_setown(filp, current->pid, 0); | |
1484 | out_unlock: | |
1485 | unlock_kernel(); | |
1486 | return error; | |
1487 | } | |
1488 | ||
1489 | /** | |
1490 | * flock_lock_file_wait - Apply a FLOCK-style lock to a file | |
1491 | * @filp: The file to apply the lock to | |
1492 | * @fl: The lock to be applied | |
1493 | * | |
1494 | * Add a FLOCK style lock to a file. | |
1495 | */ | |
1496 | int flock_lock_file_wait(struct file *filp, struct file_lock *fl) | |
1497 | { | |
1498 | int error; | |
1499 | might_sleep(); | |
1500 | for (;;) { | |
1501 | error = flock_lock_file(filp, fl); | |
1502 | if ((error != -EAGAIN) || !(fl->fl_flags & FL_SLEEP)) | |
1503 | break; | |
1504 | error = wait_event_interruptible(fl->fl_wait, !fl->fl_next); | |
1505 | if (!error) | |
1506 | continue; | |
1507 | ||
1508 | locks_delete_block(fl); | |
1509 | break; | |
1510 | } | |
1511 | return error; | |
1512 | } | |
1513 | ||
1514 | EXPORT_SYMBOL(flock_lock_file_wait); | |
1515 | ||
1516 | /** | |
1517 | * sys_flock: - flock() system call. | |
1518 | * @fd: the file descriptor to lock. | |
1519 | * @cmd: the type of lock to apply. | |
1520 | * | |
1521 | * Apply a %FL_FLOCK style lock to an open file descriptor. | |
1522 | * The @cmd can be one of | |
1523 | * | |
1524 | * %LOCK_SH -- a shared lock. | |
1525 | * | |
1526 | * %LOCK_EX -- an exclusive lock. | |
1527 | * | |
1528 | * %LOCK_UN -- remove an existing lock. | |
1529 | * | |
1530 | * %LOCK_MAND -- a `mandatory' flock. This exists to emulate Windows Share Modes. | |
1531 | * | |
1532 | * %LOCK_MAND can be combined with %LOCK_READ or %LOCK_WRITE to allow other | |
1533 | * processes read and write access respectively. | |
1534 | */ | |
1535 | asmlinkage long sys_flock(unsigned int fd, unsigned int cmd) | |
1536 | { | |
1537 | struct file *filp; | |
1538 | struct file_lock *lock; | |
1539 | int can_sleep, unlock; | |
1540 | int error; | |
1541 | ||
1542 | error = -EBADF; | |
1543 | filp = fget(fd); | |
1544 | if (!filp) | |
1545 | goto out; | |
1546 | ||
1547 | can_sleep = !(cmd & LOCK_NB); | |
1548 | cmd &= ~LOCK_NB; | |
1549 | unlock = (cmd == LOCK_UN); | |
1550 | ||
1551 | if (!unlock && !(cmd & LOCK_MAND) && !(filp->f_mode & 3)) | |
1552 | goto out_putf; | |
1553 | ||
1554 | error = flock_make_lock(filp, &lock, cmd); | |
1555 | if (error) | |
1556 | goto out_putf; | |
1557 | if (can_sleep) | |
1558 | lock->fl_flags |= FL_SLEEP; | |
1559 | ||
1560 | error = security_file_lock(filp, cmd); | |
1561 | if (error) | |
1562 | goto out_free; | |
1563 | ||
1564 | if (filp->f_op && filp->f_op->flock) | |
1565 | error = filp->f_op->flock(filp, | |
1566 | (can_sleep) ? F_SETLKW : F_SETLK, | |
1567 | lock); | |
1568 | else | |
1569 | error = flock_lock_file_wait(filp, lock); | |
1570 | ||
1571 | out_free: | |
1572 | if (list_empty(&lock->fl_link)) { | |
1573 | locks_free_lock(lock); | |
1574 | } | |
1575 | ||
1576 | out_putf: | |
1577 | fput(filp); | |
1578 | out: | |
1579 | return error; | |
1580 | } | |
1581 | ||
1582 | /* Report the first existing lock that would conflict with l. | |
1583 | * This implements the F_GETLK command of fcntl(). | |
1584 | */ | |
1585 | int fcntl_getlk(struct file *filp, struct flock __user *l) | |
1586 | { | |
8dc7c311 | 1587 | struct file_lock *fl, cfl, file_lock; |
1da177e4 LT |
1588 | struct flock flock; |
1589 | int error; | |
1590 | ||
1591 | error = -EFAULT; | |
1592 | if (copy_from_user(&flock, l, sizeof(flock))) | |
1593 | goto out; | |
1594 | error = -EINVAL; | |
1595 | if ((flock.l_type != F_RDLCK) && (flock.l_type != F_WRLCK)) | |
1596 | goto out; | |
1597 | ||
1598 | error = flock_to_posix_lock(filp, &file_lock, &flock); | |
1599 | if (error) | |
1600 | goto out; | |
1601 | ||
1602 | if (filp->f_op && filp->f_op->lock) { | |
1603 | error = filp->f_op->lock(filp, F_GETLK, &file_lock); | |
80fec4c6 TM |
1604 | if (file_lock.fl_ops && file_lock.fl_ops->fl_release_private) |
1605 | file_lock.fl_ops->fl_release_private(&file_lock); | |
1da177e4 LT |
1606 | if (error < 0) |
1607 | goto out; | |
1608 | else | |
1609 | fl = (file_lock.fl_type == F_UNLCK ? NULL : &file_lock); | |
1610 | } else { | |
8dc7c311 | 1611 | fl = (posix_test_lock(filp, &file_lock, &cfl) ? &cfl : NULL); |
1da177e4 LT |
1612 | } |
1613 | ||
1614 | flock.l_type = F_UNLCK; | |
1615 | if (fl != NULL) { | |
1616 | flock.l_pid = fl->fl_pid; | |
1617 | #if BITS_PER_LONG == 32 | |
1618 | /* | |
1619 | * Make sure we can represent the posix lock via | |
1620 | * legacy 32bit flock. | |
1621 | */ | |
1622 | error = -EOVERFLOW; | |
1623 | if (fl->fl_start > OFFT_OFFSET_MAX) | |
1624 | goto out; | |
1625 | if ((fl->fl_end != OFFSET_MAX) | |
1626 | && (fl->fl_end > OFFT_OFFSET_MAX)) | |
1627 | goto out; | |
1628 | #endif | |
1629 | flock.l_start = fl->fl_start; | |
1630 | flock.l_len = fl->fl_end == OFFSET_MAX ? 0 : | |
1631 | fl->fl_end - fl->fl_start + 1; | |
1632 | flock.l_whence = 0; | |
1633 | flock.l_type = fl->fl_type; | |
1634 | } | |
1635 | error = -EFAULT; | |
1636 | if (!copy_to_user(l, &flock, sizeof(flock))) | |
1637 | error = 0; | |
1638 | out: | |
1639 | return error; | |
1640 | } | |
1641 | ||
1642 | /* Apply the lock described by l to an open file descriptor. | |
1643 | * This implements both the F_SETLK and F_SETLKW commands of fcntl(). | |
1644 | */ | |
c293621b PS |
1645 | int fcntl_setlk(unsigned int fd, struct file *filp, unsigned int cmd, |
1646 | struct flock __user *l) | |
1da177e4 LT |
1647 | { |
1648 | struct file_lock *file_lock = locks_alloc_lock(); | |
1649 | struct flock flock; | |
1650 | struct inode *inode; | |
1651 | int error; | |
1652 | ||
1653 | if (file_lock == NULL) | |
1654 | return -ENOLCK; | |
1655 | ||
1656 | /* | |
1657 | * This might block, so we do it before checking the inode. | |
1658 | */ | |
1659 | error = -EFAULT; | |
1660 | if (copy_from_user(&flock, l, sizeof(flock))) | |
1661 | goto out; | |
1662 | ||
1663 | inode = filp->f_dentry->d_inode; | |
1664 | ||
1665 | /* Don't allow mandatory locks on files that may be memory mapped | |
1666 | * and shared. | |
1667 | */ | |
1668 | if (IS_MANDLOCK(inode) && | |
1669 | (inode->i_mode & (S_ISGID | S_IXGRP)) == S_ISGID && | |
1670 | mapping_writably_mapped(filp->f_mapping)) { | |
1671 | error = -EAGAIN; | |
1672 | goto out; | |
1673 | } | |
1674 | ||
c293621b | 1675 | again: |
1da177e4 LT |
1676 | error = flock_to_posix_lock(filp, file_lock, &flock); |
1677 | if (error) | |
1678 | goto out; | |
1679 | if (cmd == F_SETLKW) { | |
1680 | file_lock->fl_flags |= FL_SLEEP; | |
1681 | } | |
1682 | ||
1683 | error = -EBADF; | |
1684 | switch (flock.l_type) { | |
1685 | case F_RDLCK: | |
1686 | if (!(filp->f_mode & FMODE_READ)) | |
1687 | goto out; | |
1688 | break; | |
1689 | case F_WRLCK: | |
1690 | if (!(filp->f_mode & FMODE_WRITE)) | |
1691 | goto out; | |
1692 | break; | |
1693 | case F_UNLCK: | |
1694 | break; | |
1695 | default: | |
1696 | error = -EINVAL; | |
1697 | goto out; | |
1698 | } | |
1699 | ||
1700 | error = security_file_lock(filp, file_lock->fl_type); | |
1701 | if (error) | |
1702 | goto out; | |
1703 | ||
c293621b | 1704 | if (filp->f_op && filp->f_op->lock != NULL) |
1da177e4 | 1705 | error = filp->f_op->lock(filp, cmd, file_lock); |
c293621b PS |
1706 | else { |
1707 | for (;;) { | |
5842add2 | 1708 | error = posix_lock_file(filp, file_lock); |
c293621b PS |
1709 | if ((error != -EAGAIN) || (cmd == F_SETLK)) |
1710 | break; | |
1711 | error = wait_event_interruptible(file_lock->fl_wait, | |
1712 | !file_lock->fl_next); | |
1713 | if (!error) | |
1714 | continue; | |
1da177e4 | 1715 | |
c293621b | 1716 | locks_delete_block(file_lock); |
1da177e4 | 1717 | break; |
c293621b PS |
1718 | } |
1719 | } | |
1da177e4 | 1720 | |
c293621b PS |
1721 | /* |
1722 | * Attempt to detect a close/fcntl race and recover by | |
1723 | * releasing the lock that was just acquired. | |
1724 | */ | |
1725 | if (!error && fcheck(fd) != filp && flock.l_type != F_UNLCK) { | |
1726 | flock.l_type = F_UNLCK; | |
1727 | goto again; | |
1da177e4 LT |
1728 | } |
1729 | ||
c293621b | 1730 | out: |
1da177e4 LT |
1731 | locks_free_lock(file_lock); |
1732 | return error; | |
1733 | } | |
1734 | ||
1735 | #if BITS_PER_LONG == 32 | |
1736 | /* Report the first existing lock that would conflict with l. | |
1737 | * This implements the F_GETLK command of fcntl(). | |
1738 | */ | |
1739 | int fcntl_getlk64(struct file *filp, struct flock64 __user *l) | |
1740 | { | |
8dc7c311 | 1741 | struct file_lock *fl, cfl, file_lock; |
1da177e4 LT |
1742 | struct flock64 flock; |
1743 | int error; | |
1744 | ||
1745 | error = -EFAULT; | |
1746 | if (copy_from_user(&flock, l, sizeof(flock))) | |
1747 | goto out; | |
1748 | error = -EINVAL; | |
1749 | if ((flock.l_type != F_RDLCK) && (flock.l_type != F_WRLCK)) | |
1750 | goto out; | |
1751 | ||
1752 | error = flock64_to_posix_lock(filp, &file_lock, &flock); | |
1753 | if (error) | |
1754 | goto out; | |
1755 | ||
1756 | if (filp->f_op && filp->f_op->lock) { | |
1757 | error = filp->f_op->lock(filp, F_GETLK, &file_lock); | |
80fec4c6 TM |
1758 | if (file_lock.fl_ops && file_lock.fl_ops->fl_release_private) |
1759 | file_lock.fl_ops->fl_release_private(&file_lock); | |
1da177e4 LT |
1760 | if (error < 0) |
1761 | goto out; | |
1762 | else | |
1763 | fl = (file_lock.fl_type == F_UNLCK ? NULL : &file_lock); | |
1764 | } else { | |
8dc7c311 | 1765 | fl = (posix_test_lock(filp, &file_lock, &cfl) ? &cfl : NULL); |
1da177e4 LT |
1766 | } |
1767 | ||
1768 | flock.l_type = F_UNLCK; | |
1769 | if (fl != NULL) { | |
1770 | flock.l_pid = fl->fl_pid; | |
1771 | flock.l_start = fl->fl_start; | |
1772 | flock.l_len = fl->fl_end == OFFSET_MAX ? 0 : | |
1773 | fl->fl_end - fl->fl_start + 1; | |
1774 | flock.l_whence = 0; | |
1775 | flock.l_type = fl->fl_type; | |
1776 | } | |
1777 | error = -EFAULT; | |
1778 | if (!copy_to_user(l, &flock, sizeof(flock))) | |
1779 | error = 0; | |
1780 | ||
1781 | out: | |
1782 | return error; | |
1783 | } | |
1784 | ||
1785 | /* Apply the lock described by l to an open file descriptor. | |
1786 | * This implements both the F_SETLK and F_SETLKW commands of fcntl(). | |
1787 | */ | |
c293621b PS |
1788 | int fcntl_setlk64(unsigned int fd, struct file *filp, unsigned int cmd, |
1789 | struct flock64 __user *l) | |
1da177e4 LT |
1790 | { |
1791 | struct file_lock *file_lock = locks_alloc_lock(); | |
1792 | struct flock64 flock; | |
1793 | struct inode *inode; | |
1794 | int error; | |
1795 | ||
1796 | if (file_lock == NULL) | |
1797 | return -ENOLCK; | |
1798 | ||
1799 | /* | |
1800 | * This might block, so we do it before checking the inode. | |
1801 | */ | |
1802 | error = -EFAULT; | |
1803 | if (copy_from_user(&flock, l, sizeof(flock))) | |
1804 | goto out; | |
1805 | ||
1806 | inode = filp->f_dentry->d_inode; | |
1807 | ||
1808 | /* Don't allow mandatory locks on files that may be memory mapped | |
1809 | * and shared. | |
1810 | */ | |
1811 | if (IS_MANDLOCK(inode) && | |
1812 | (inode->i_mode & (S_ISGID | S_IXGRP)) == S_ISGID && | |
1813 | mapping_writably_mapped(filp->f_mapping)) { | |
1814 | error = -EAGAIN; | |
1815 | goto out; | |
1816 | } | |
1817 | ||
c293621b | 1818 | again: |
1da177e4 LT |
1819 | error = flock64_to_posix_lock(filp, file_lock, &flock); |
1820 | if (error) | |
1821 | goto out; | |
1822 | if (cmd == F_SETLKW64) { | |
1823 | file_lock->fl_flags |= FL_SLEEP; | |
1824 | } | |
1825 | ||
1826 | error = -EBADF; | |
1827 | switch (flock.l_type) { | |
1828 | case F_RDLCK: | |
1829 | if (!(filp->f_mode & FMODE_READ)) | |
1830 | goto out; | |
1831 | break; | |
1832 | case F_WRLCK: | |
1833 | if (!(filp->f_mode & FMODE_WRITE)) | |
1834 | goto out; | |
1835 | break; | |
1836 | case F_UNLCK: | |
1837 | break; | |
1838 | default: | |
1839 | error = -EINVAL; | |
1840 | goto out; | |
1841 | } | |
1842 | ||
1843 | error = security_file_lock(filp, file_lock->fl_type); | |
1844 | if (error) | |
1845 | goto out; | |
1846 | ||
c293621b | 1847 | if (filp->f_op && filp->f_op->lock != NULL) |
1da177e4 | 1848 | error = filp->f_op->lock(filp, cmd, file_lock); |
c293621b PS |
1849 | else { |
1850 | for (;;) { | |
5842add2 | 1851 | error = posix_lock_file(filp, file_lock); |
c293621b PS |
1852 | if ((error != -EAGAIN) || (cmd == F_SETLK64)) |
1853 | break; | |
1854 | error = wait_event_interruptible(file_lock->fl_wait, | |
1855 | !file_lock->fl_next); | |
1856 | if (!error) | |
1857 | continue; | |
1da177e4 | 1858 | |
c293621b | 1859 | locks_delete_block(file_lock); |
1da177e4 | 1860 | break; |
c293621b PS |
1861 | } |
1862 | } | |
1da177e4 | 1863 | |
c293621b PS |
1864 | /* |
1865 | * Attempt to detect a close/fcntl race and recover by | |
1866 | * releasing the lock that was just acquired. | |
1867 | */ | |
1868 | if (!error && fcheck(fd) != filp && flock.l_type != F_UNLCK) { | |
1869 | flock.l_type = F_UNLCK; | |
1870 | goto again; | |
1da177e4 LT |
1871 | } |
1872 | ||
1873 | out: | |
1874 | locks_free_lock(file_lock); | |
1875 | return error; | |
1876 | } | |
1877 | #endif /* BITS_PER_LONG == 32 */ | |
1878 | ||
1879 | /* | |
1880 | * This function is called when the file is being removed | |
1881 | * from the task's fd array. POSIX locks belonging to this task | |
1882 | * are deleted at this time. | |
1883 | */ | |
1884 | void locks_remove_posix(struct file *filp, fl_owner_t owner) | |
1885 | { | |
1886 | struct file_lock lock, **before; | |
1887 | ||
1888 | /* | |
1889 | * If there are no locks held on this file, we don't need to call | |
1890 | * posix_lock_file(). Another process could be setting a lock on this | |
1891 | * file at the same time, but we wouldn't remove that lock anyway. | |
1892 | */ | |
1893 | before = &filp->f_dentry->d_inode->i_flock; | |
1894 | if (*before == NULL) | |
1895 | return; | |
1896 | ||
1897 | lock.fl_type = F_UNLCK; | |
1898 | lock.fl_flags = FL_POSIX; | |
1899 | lock.fl_start = 0; | |
1900 | lock.fl_end = OFFSET_MAX; | |
1901 | lock.fl_owner = owner; | |
1902 | lock.fl_pid = current->tgid; | |
1903 | lock.fl_file = filp; | |
1904 | lock.fl_ops = NULL; | |
1905 | lock.fl_lmops = NULL; | |
1906 | ||
1907 | if (filp->f_op && filp->f_op->lock != NULL) { | |
1908 | filp->f_op->lock(filp, F_SETLK, &lock); | |
1909 | goto out; | |
1910 | } | |
1911 | ||
1912 | /* Can't use posix_lock_file here; we need to remove it no matter | |
1913 | * which pid we have. | |
1914 | */ | |
1915 | lock_kernel(); | |
1916 | while (*before != NULL) { | |
1917 | struct file_lock *fl = *before; | |
1918 | if (IS_POSIX(fl) && posix_same_owner(fl, &lock)) { | |
1919 | locks_delete_lock(before); | |
1920 | continue; | |
1921 | } | |
1922 | before = &fl->fl_next; | |
1923 | } | |
1924 | unlock_kernel(); | |
1925 | out: | |
1926 | if (lock.fl_ops && lock.fl_ops->fl_release_private) | |
1927 | lock.fl_ops->fl_release_private(&lock); | |
1928 | } | |
1929 | ||
1930 | EXPORT_SYMBOL(locks_remove_posix); | |
1931 | ||
1932 | /* | |
1933 | * This function is called on the last close of an open file. | |
1934 | */ | |
1935 | void locks_remove_flock(struct file *filp) | |
1936 | { | |
1937 | struct inode * inode = filp->f_dentry->d_inode; | |
1938 | struct file_lock *fl; | |
1939 | struct file_lock **before; | |
1940 | ||
1941 | if (!inode->i_flock) | |
1942 | return; | |
1943 | ||
1944 | if (filp->f_op && filp->f_op->flock) { | |
1945 | struct file_lock fl = { | |
1946 | .fl_pid = current->tgid, | |
1947 | .fl_file = filp, | |
1948 | .fl_flags = FL_FLOCK, | |
1949 | .fl_type = F_UNLCK, | |
1950 | .fl_end = OFFSET_MAX, | |
1951 | }; | |
1952 | filp->f_op->flock(filp, F_SETLKW, &fl); | |
80fec4c6 TM |
1953 | if (fl.fl_ops && fl.fl_ops->fl_release_private) |
1954 | fl.fl_ops->fl_release_private(&fl); | |
1da177e4 LT |
1955 | } |
1956 | ||
1957 | lock_kernel(); | |
1958 | before = &inode->i_flock; | |
1959 | ||
1960 | while ((fl = *before) != NULL) { | |
1961 | if (fl->fl_file == filp) { | |
c293621b | 1962 | if (IS_FLOCK(fl)) { |
1da177e4 LT |
1963 | locks_delete_lock(before); |
1964 | continue; | |
1965 | } | |
1966 | if (IS_LEASE(fl)) { | |
1967 | lease_modify(before, F_UNLCK); | |
1968 | continue; | |
1969 | } | |
1970 | /* What? */ | |
1971 | BUG(); | |
1972 | } | |
1973 | before = &fl->fl_next; | |
1974 | } | |
1975 | unlock_kernel(); | |
1976 | } | |
1977 | ||
1da177e4 LT |
1978 | /** |
1979 | * posix_unblock_lock - stop waiting for a file lock | |
1980 | * @filp: how the file was opened | |
1981 | * @waiter: the lock which was waiting | |
1982 | * | |
1983 | * lockd needs to block waiting for locks. | |
1984 | */ | |
64a318ee | 1985 | int |
1da177e4 LT |
1986 | posix_unblock_lock(struct file *filp, struct file_lock *waiter) |
1987 | { | |
64a318ee BF |
1988 | int status = 0; |
1989 | ||
1da177e4 | 1990 | lock_kernel(); |
5996a298 | 1991 | if (waiter->fl_next) |
1da177e4 | 1992 | __locks_delete_block(waiter); |
64a318ee BF |
1993 | else |
1994 | status = -ENOENT; | |
5996a298 | 1995 | unlock_kernel(); |
64a318ee | 1996 | return status; |
1da177e4 LT |
1997 | } |
1998 | ||
1999 | EXPORT_SYMBOL(posix_unblock_lock); | |
2000 | ||
2001 | static void lock_get_status(char* out, struct file_lock *fl, int id, char *pfx) | |
2002 | { | |
2003 | struct inode *inode = NULL; | |
2004 | ||
2005 | if (fl->fl_file != NULL) | |
2006 | inode = fl->fl_file->f_dentry->d_inode; | |
2007 | ||
2008 | out += sprintf(out, "%d:%s ", id, pfx); | |
2009 | if (IS_POSIX(fl)) { | |
2010 | out += sprintf(out, "%6s %s ", | |
2011 | (fl->fl_flags & FL_ACCESS) ? "ACCESS" : "POSIX ", | |
2012 | (inode == NULL) ? "*NOINODE*" : | |
2013 | (IS_MANDLOCK(inode) && | |
2014 | (inode->i_mode & (S_IXGRP | S_ISGID)) == S_ISGID) ? | |
2015 | "MANDATORY" : "ADVISORY "); | |
2016 | } else if (IS_FLOCK(fl)) { | |
2017 | if (fl->fl_type & LOCK_MAND) { | |
2018 | out += sprintf(out, "FLOCK MSNFS "); | |
2019 | } else { | |
2020 | out += sprintf(out, "FLOCK ADVISORY "); | |
2021 | } | |
2022 | } else if (IS_LEASE(fl)) { | |
2023 | out += sprintf(out, "LEASE "); | |
2024 | if (fl->fl_type & F_INPROGRESS) | |
2025 | out += sprintf(out, "BREAKING "); | |
2026 | else if (fl->fl_file) | |
2027 | out += sprintf(out, "ACTIVE "); | |
2028 | else | |
2029 | out += sprintf(out, "BREAKER "); | |
2030 | } else { | |
2031 | out += sprintf(out, "UNKNOWN UNKNOWN "); | |
2032 | } | |
2033 | if (fl->fl_type & LOCK_MAND) { | |
2034 | out += sprintf(out, "%s ", | |
2035 | (fl->fl_type & LOCK_READ) | |
2036 | ? (fl->fl_type & LOCK_WRITE) ? "RW " : "READ " | |
2037 | : (fl->fl_type & LOCK_WRITE) ? "WRITE" : "NONE "); | |
2038 | } else { | |
2039 | out += sprintf(out, "%s ", | |
2040 | (fl->fl_type & F_INPROGRESS) | |
2041 | ? (fl->fl_type & F_UNLCK) ? "UNLCK" : "READ " | |
2042 | : (fl->fl_type & F_WRLCK) ? "WRITE" : "READ "); | |
2043 | } | |
2044 | if (inode) { | |
2045 | #ifdef WE_CAN_BREAK_LSLK_NOW | |
2046 | out += sprintf(out, "%d %s:%ld ", fl->fl_pid, | |
2047 | inode->i_sb->s_id, inode->i_ino); | |
2048 | #else | |
2049 | /* userspace relies on this representation of dev_t ;-( */ | |
2050 | out += sprintf(out, "%d %02x:%02x:%ld ", fl->fl_pid, | |
2051 | MAJOR(inode->i_sb->s_dev), | |
2052 | MINOR(inode->i_sb->s_dev), inode->i_ino); | |
2053 | #endif | |
2054 | } else { | |
2055 | out += sprintf(out, "%d <none>:0 ", fl->fl_pid); | |
2056 | } | |
2057 | if (IS_POSIX(fl)) { | |
2058 | if (fl->fl_end == OFFSET_MAX) | |
2059 | out += sprintf(out, "%Ld EOF\n", fl->fl_start); | |
2060 | else | |
2061 | out += sprintf(out, "%Ld %Ld\n", fl->fl_start, | |
2062 | fl->fl_end); | |
2063 | } else { | |
2064 | out += sprintf(out, "0 EOF\n"); | |
2065 | } | |
2066 | } | |
2067 | ||
2068 | static void move_lock_status(char **p, off_t* pos, off_t offset) | |
2069 | { | |
2070 | int len; | |
2071 | len = strlen(*p); | |
2072 | if(*pos >= offset) { | |
2073 | /* the complete line is valid */ | |
2074 | *p += len; | |
2075 | *pos += len; | |
2076 | return; | |
2077 | } | |
2078 | if(*pos+len > offset) { | |
2079 | /* use the second part of the line */ | |
2080 | int i = offset-*pos; | |
2081 | memmove(*p,*p+i,len-i); | |
2082 | *p += len-i; | |
2083 | *pos += len; | |
2084 | return; | |
2085 | } | |
2086 | /* discard the complete line */ | |
2087 | *pos += len; | |
2088 | } | |
2089 | ||
2090 | /** | |
2091 | * get_locks_status - reports lock usage in /proc/locks | |
2092 | * @buffer: address in userspace to write into | |
2093 | * @start: ? | |
2094 | * @offset: how far we are through the buffer | |
2095 | * @length: how much to read | |
2096 | */ | |
2097 | ||
2098 | int get_locks_status(char *buffer, char **start, off_t offset, int length) | |
2099 | { | |
2100 | struct list_head *tmp; | |
2101 | char *q = buffer; | |
2102 | off_t pos = 0; | |
2103 | int i = 0; | |
2104 | ||
2105 | lock_kernel(); | |
2106 | list_for_each(tmp, &file_lock_list) { | |
2107 | struct list_head *btmp; | |
2108 | struct file_lock *fl = list_entry(tmp, struct file_lock, fl_link); | |
2109 | lock_get_status(q, fl, ++i, ""); | |
2110 | move_lock_status(&q, &pos, offset); | |
2111 | ||
2112 | if(pos >= offset+length) | |
2113 | goto done; | |
2114 | ||
2115 | list_for_each(btmp, &fl->fl_block) { | |
2116 | struct file_lock *bfl = list_entry(btmp, | |
2117 | struct file_lock, fl_block); | |
2118 | lock_get_status(q, bfl, i, " ->"); | |
2119 | move_lock_status(&q, &pos, offset); | |
2120 | ||
2121 | if(pos >= offset+length) | |
2122 | goto done; | |
2123 | } | |
2124 | } | |
2125 | done: | |
2126 | unlock_kernel(); | |
2127 | *start = buffer; | |
2128 | if(q-buffer < length) | |
2129 | return (q-buffer); | |
2130 | return length; | |
2131 | } | |
2132 | ||
2133 | /** | |
2134 | * lock_may_read - checks that the region is free of locks | |
2135 | * @inode: the inode that is being read | |
2136 | * @start: the first byte to read | |
2137 | * @len: the number of bytes to read | |
2138 | * | |
2139 | * Emulates Windows locking requirements. Whole-file | |
2140 | * mandatory locks (share modes) can prohibit a read and | |
2141 | * byte-range POSIX locks can prohibit a read if they overlap. | |
2142 | * | |
2143 | * N.B. this function is only ever called | |
2144 | * from knfsd and ownership of locks is never checked. | |
2145 | */ | |
2146 | int lock_may_read(struct inode *inode, loff_t start, unsigned long len) | |
2147 | { | |
2148 | struct file_lock *fl; | |
2149 | int result = 1; | |
2150 | lock_kernel(); | |
2151 | for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) { | |
2152 | if (IS_POSIX(fl)) { | |
2153 | if (fl->fl_type == F_RDLCK) | |
2154 | continue; | |
2155 | if ((fl->fl_end < start) || (fl->fl_start > (start + len))) | |
2156 | continue; | |
2157 | } else if (IS_FLOCK(fl)) { | |
2158 | if (!(fl->fl_type & LOCK_MAND)) | |
2159 | continue; | |
2160 | if (fl->fl_type & LOCK_READ) | |
2161 | continue; | |
2162 | } else | |
2163 | continue; | |
2164 | result = 0; | |
2165 | break; | |
2166 | } | |
2167 | unlock_kernel(); | |
2168 | return result; | |
2169 | } | |
2170 | ||
2171 | EXPORT_SYMBOL(lock_may_read); | |
2172 | ||
2173 | /** | |
2174 | * lock_may_write - checks that the region is free of locks | |
2175 | * @inode: the inode that is being written | |
2176 | * @start: the first byte to write | |
2177 | * @len: the number of bytes to write | |
2178 | * | |
2179 | * Emulates Windows locking requirements. Whole-file | |
2180 | * mandatory locks (share modes) can prohibit a write and | |
2181 | * byte-range POSIX locks can prohibit a write if they overlap. | |
2182 | * | |
2183 | * N.B. this function is only ever called | |
2184 | * from knfsd and ownership of locks is never checked. | |
2185 | */ | |
2186 | int lock_may_write(struct inode *inode, loff_t start, unsigned long len) | |
2187 | { | |
2188 | struct file_lock *fl; | |
2189 | int result = 1; | |
2190 | lock_kernel(); | |
2191 | for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) { | |
2192 | if (IS_POSIX(fl)) { | |
2193 | if ((fl->fl_end < start) || (fl->fl_start > (start + len))) | |
2194 | continue; | |
2195 | } else if (IS_FLOCK(fl)) { | |
2196 | if (!(fl->fl_type & LOCK_MAND)) | |
2197 | continue; | |
2198 | if (fl->fl_type & LOCK_WRITE) | |
2199 | continue; | |
2200 | } else | |
2201 | continue; | |
2202 | result = 0; | |
2203 | break; | |
2204 | } | |
2205 | unlock_kernel(); | |
2206 | return result; | |
2207 | } | |
2208 | ||
2209 | EXPORT_SYMBOL(lock_may_write); | |
2210 | ||
2211 | static inline void __steal_locks(struct file *file, fl_owner_t from) | |
2212 | { | |
2213 | struct inode *inode = file->f_dentry->d_inode; | |
2214 | struct file_lock *fl = inode->i_flock; | |
2215 | ||
2216 | while (fl) { | |
2217 | if (fl->fl_file == file && fl->fl_owner == from) | |
2218 | fl->fl_owner = current->files; | |
2219 | fl = fl->fl_next; | |
2220 | } | |
2221 | } | |
2222 | ||
2223 | /* When getting ready for executing a binary, we make sure that current | |
2224 | * has a files_struct on its own. Before dropping the old files_struct, | |
2225 | * we take over ownership of all locks for all file descriptors we own. | |
2226 | * Note that we may accidentally steal a lock for a file that a sibling | |
2227 | * has created since the unshare_files() call. | |
2228 | */ | |
2229 | void steal_locks(fl_owner_t from) | |
2230 | { | |
2231 | struct files_struct *files = current->files; | |
2232 | int i, j; | |
badf1662 | 2233 | struct fdtable *fdt; |
1da177e4 LT |
2234 | |
2235 | if (from == files) | |
2236 | return; | |
2237 | ||
2238 | lock_kernel(); | |
2239 | j = 0; | |
4fb3a538 | 2240 | rcu_read_lock(); |
badf1662 | 2241 | fdt = files_fdtable(files); |
1da177e4 LT |
2242 | for (;;) { |
2243 | unsigned long set; | |
2244 | i = j * __NFDBITS; | |
badf1662 | 2245 | if (i >= fdt->max_fdset || i >= fdt->max_fds) |
1da177e4 | 2246 | break; |
badf1662 | 2247 | set = fdt->open_fds->fds_bits[j++]; |
1da177e4 LT |
2248 | while (set) { |
2249 | if (set & 1) { | |
badf1662 | 2250 | struct file *file = fdt->fd[i]; |
1da177e4 LT |
2251 | if (file) |
2252 | __steal_locks(file, from); | |
2253 | } | |
2254 | i++; | |
2255 | set >>= 1; | |
2256 | } | |
2257 | } | |
4fb3a538 | 2258 | rcu_read_unlock(); |
1da177e4 LT |
2259 | unlock_kernel(); |
2260 | } | |
2261 | EXPORT_SYMBOL(steal_locks); | |
2262 | ||
2263 | static int __init filelock_init(void) | |
2264 | { | |
2265 | filelock_cache = kmem_cache_create("file_lock_cache", | |
2266 | sizeof(struct file_lock), 0, SLAB_PANIC, | |
2267 | init_once, NULL); | |
2268 | return 0; | |
2269 | } | |
2270 | ||
2271 | core_initcall(filelock_init); |