blob: 22c5b4aa49611ac46cb50dbf4fc8ef25ec500b34
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/filesystems/mandatory-locking.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/fdtable.h> |
120 | #include <linux/fs.h> |
121 | #include <linux/init.h> |
122 | #include <linux/security.h> |
123 | #include <linux/slab.h> |
124 | #include <linux/syscalls.h> |
125 | #include <linux/time.h> |
126 | #include <linux/rcupdate.h> |
127 | #include <linux/pid_namespace.h> |
128 | #include <linux/hashtable.h> |
129 | #include <linux/percpu.h> |
130 | |
131 | #define CREATE_TRACE_POINTS |
132 | #include <trace/events/filelock.h> |
133 | |
134 | #include <asm/uaccess.h> |
135 | |
136 | #define IS_POSIX(fl) (fl->fl_flags & FL_POSIX) |
137 | #define IS_FLOCK(fl) (fl->fl_flags & FL_FLOCK) |
138 | #define IS_LEASE(fl) (fl->fl_flags & (FL_LEASE|FL_DELEG|FL_LAYOUT)) |
139 | #define IS_OFDLCK(fl) (fl->fl_flags & FL_OFDLCK) |
140 | |
141 | static inline bool is_remote_lock(struct file *filp) |
142 | { |
143 | return likely(!(filp->f_path.dentry->d_sb->s_flags & MS_NOREMOTELOCK)); |
144 | } |
145 | |
146 | static bool lease_breaking(struct file_lock *fl) |
147 | { |
148 | return fl->fl_flags & (FL_UNLOCK_PENDING | FL_DOWNGRADE_PENDING); |
149 | } |
150 | |
151 | static int target_leasetype(struct file_lock *fl) |
152 | { |
153 | if (fl->fl_flags & FL_UNLOCK_PENDING) |
154 | return F_UNLCK; |
155 | if (fl->fl_flags & FL_DOWNGRADE_PENDING) |
156 | return F_RDLCK; |
157 | return fl->fl_type; |
158 | } |
159 | |
160 | int leases_enable = 1; |
161 | int lease_break_time = 45; |
162 | |
163 | /* |
164 | * The global file_lock_list is only used for displaying /proc/locks, so we |
165 | * keep a list on each CPU, with each list protected by its own spinlock. |
166 | * Global serialization is done using file_rwsem. |
167 | * |
168 | * Note that alterations to the list also require that the relevant flc_lock is |
169 | * held. |
170 | */ |
171 | struct file_lock_list_struct { |
172 | spinlock_t lock; |
173 | struct hlist_head hlist; |
174 | }; |
175 | static DEFINE_PER_CPU(struct file_lock_list_struct, file_lock_list); |
176 | DEFINE_STATIC_PERCPU_RWSEM(file_rwsem); |
177 | |
178 | /* |
179 | * The blocked_hash is used to find POSIX lock loops for deadlock detection. |
180 | * It is protected by blocked_lock_lock. |
181 | * |
182 | * We hash locks by lockowner in order to optimize searching for the lock a |
183 | * particular lockowner is waiting on. |
184 | * |
185 | * FIXME: make this value scale via some heuristic? We generally will want more |
186 | * buckets when we have more lockowners holding locks, but that's a little |
187 | * difficult to determine without knowing what the workload will look like. |
188 | */ |
189 | #define BLOCKED_HASH_BITS 7 |
190 | static DEFINE_HASHTABLE(blocked_hash, BLOCKED_HASH_BITS); |
191 | |
192 | /* |
193 | * This lock protects the blocked_hash. Generally, if you're accessing it, you |
194 | * want to be holding this lock. |
195 | * |
196 | * In addition, it also protects the fl->fl_block list, and the fl->fl_next |
197 | * pointer for file_lock structures that are acting as lock requests (in |
198 | * contrast to those that are acting as records of acquired locks). |
199 | * |
200 | * Note that when we acquire this lock in order to change the above fields, |
201 | * we often hold the flc_lock as well. In certain cases, when reading the fields |
202 | * protected by this lock, we can skip acquiring it iff we already hold the |
203 | * flc_lock. |
204 | * |
205 | * In particular, adding an entry to the fl_block list requires that you hold |
206 | * both the flc_lock and the blocked_lock_lock (acquired in that order). |
207 | * Deleting an entry from the list however only requires the file_lock_lock. |
208 | */ |
209 | static DEFINE_SPINLOCK(blocked_lock_lock); |
210 | |
211 | static struct kmem_cache *flctx_cache __read_mostly; |
212 | static struct kmem_cache *filelock_cache __read_mostly; |
213 | |
214 | static struct file_lock_context * |
215 | locks_get_lock_context(struct inode *inode, int type) |
216 | { |
217 | struct file_lock_context *ctx; |
218 | |
219 | /* paired with cmpxchg() below */ |
220 | ctx = smp_load_acquire(&inode->i_flctx); |
221 | if (likely(ctx) || type == F_UNLCK) |
222 | goto out; |
223 | |
224 | ctx = kmem_cache_alloc(flctx_cache, GFP_KERNEL); |
225 | if (!ctx) |
226 | goto out; |
227 | |
228 | spin_lock_init(&ctx->flc_lock); |
229 | INIT_LIST_HEAD(&ctx->flc_flock); |
230 | INIT_LIST_HEAD(&ctx->flc_posix); |
231 | INIT_LIST_HEAD(&ctx->flc_lease); |
232 | |
233 | /* |
234 | * Assign the pointer if it's not already assigned. If it is, then |
235 | * free the context we just allocated. |
236 | */ |
237 | if (cmpxchg(&inode->i_flctx, NULL, ctx)) { |
238 | kmem_cache_free(flctx_cache, ctx); |
239 | ctx = smp_load_acquire(&inode->i_flctx); |
240 | } |
241 | out: |
242 | trace_locks_get_lock_context(inode, type, ctx); |
243 | return ctx; |
244 | } |
245 | |
246 | static void |
247 | locks_dump_ctx_list(struct list_head *list, char *list_type) |
248 | { |
249 | struct file_lock *fl; |
250 | |
251 | list_for_each_entry(fl, list, fl_list) { |
252 | pr_warn("%s: fl_owner=%p fl_flags=0x%x fl_type=0x%x fl_pid=%u\n", list_type, fl->fl_owner, fl->fl_flags, fl->fl_type, fl->fl_pid); |
253 | } |
254 | } |
255 | |
256 | static void |
257 | locks_check_ctx_lists(struct inode *inode) |
258 | { |
259 | struct file_lock_context *ctx = inode->i_flctx; |
260 | |
261 | if (unlikely(!list_empty(&ctx->flc_flock) || |
262 | !list_empty(&ctx->flc_posix) || |
263 | !list_empty(&ctx->flc_lease))) { |
264 | pr_warn("Leaked locks on dev=0x%x:0x%x ino=0x%lx:\n", |
265 | MAJOR(inode->i_sb->s_dev), MINOR(inode->i_sb->s_dev), |
266 | inode->i_ino); |
267 | locks_dump_ctx_list(&ctx->flc_flock, "FLOCK"); |
268 | locks_dump_ctx_list(&ctx->flc_posix, "POSIX"); |
269 | locks_dump_ctx_list(&ctx->flc_lease, "LEASE"); |
270 | } |
271 | } |
272 | |
273 | void |
274 | locks_free_lock_context(struct inode *inode) |
275 | { |
276 | struct file_lock_context *ctx = inode->i_flctx; |
277 | |
278 | if (unlikely(ctx)) { |
279 | locks_check_ctx_lists(inode); |
280 | kmem_cache_free(flctx_cache, ctx); |
281 | } |
282 | } |
283 | |
284 | static void locks_init_lock_heads(struct file_lock *fl) |
285 | { |
286 | INIT_HLIST_NODE(&fl->fl_link); |
287 | INIT_LIST_HEAD(&fl->fl_list); |
288 | INIT_LIST_HEAD(&fl->fl_block); |
289 | init_waitqueue_head(&fl->fl_wait); |
290 | } |
291 | |
292 | /* Allocate an empty lock structure. */ |
293 | struct file_lock *locks_alloc_lock(void) |
294 | { |
295 | struct file_lock *fl = kmem_cache_zalloc(filelock_cache, GFP_KERNEL); |
296 | |
297 | if (fl) |
298 | locks_init_lock_heads(fl); |
299 | |
300 | return fl; |
301 | } |
302 | EXPORT_SYMBOL_GPL(locks_alloc_lock); |
303 | |
304 | void locks_release_private(struct file_lock *fl) |
305 | { |
306 | if (fl->fl_ops) { |
307 | if (fl->fl_ops->fl_release_private) |
308 | fl->fl_ops->fl_release_private(fl); |
309 | fl->fl_ops = NULL; |
310 | } |
311 | |
312 | if (fl->fl_lmops) { |
313 | if (fl->fl_lmops->lm_put_owner) { |
314 | fl->fl_lmops->lm_put_owner(fl->fl_owner); |
315 | fl->fl_owner = NULL; |
316 | } |
317 | fl->fl_lmops = NULL; |
318 | } |
319 | } |
320 | EXPORT_SYMBOL_GPL(locks_release_private); |
321 | |
322 | /* Free a lock which is not in use. */ |
323 | void locks_free_lock(struct file_lock *fl) |
324 | { |
325 | BUG_ON(waitqueue_active(&fl->fl_wait)); |
326 | BUG_ON(!list_empty(&fl->fl_list)); |
327 | BUG_ON(!list_empty(&fl->fl_block)); |
328 | BUG_ON(!hlist_unhashed(&fl->fl_link)); |
329 | |
330 | locks_release_private(fl); |
331 | kmem_cache_free(filelock_cache, fl); |
332 | } |
333 | EXPORT_SYMBOL(locks_free_lock); |
334 | |
335 | static void |
336 | locks_dispose_list(struct list_head *dispose) |
337 | { |
338 | struct file_lock *fl; |
339 | |
340 | while (!list_empty(dispose)) { |
341 | fl = list_first_entry(dispose, struct file_lock, fl_list); |
342 | list_del_init(&fl->fl_list); |
343 | locks_free_lock(fl); |
344 | } |
345 | } |
346 | |
347 | void locks_init_lock(struct file_lock *fl) |
348 | { |
349 | memset(fl, 0, sizeof(struct file_lock)); |
350 | locks_init_lock_heads(fl); |
351 | } |
352 | |
353 | EXPORT_SYMBOL(locks_init_lock); |
354 | |
355 | /* |
356 | * Initialize a new lock from an existing file_lock structure. |
357 | */ |
358 | void locks_copy_conflock(struct file_lock *new, struct file_lock *fl) |
359 | { |
360 | new->fl_owner = fl->fl_owner; |
361 | new->fl_pid = fl->fl_pid; |
362 | new->fl_file = NULL; |
363 | new->fl_flags = fl->fl_flags; |
364 | new->fl_type = fl->fl_type; |
365 | new->fl_start = fl->fl_start; |
366 | new->fl_end = fl->fl_end; |
367 | new->fl_lmops = fl->fl_lmops; |
368 | new->fl_ops = NULL; |
369 | |
370 | if (fl->fl_lmops) { |
371 | if (fl->fl_lmops->lm_get_owner) |
372 | fl->fl_lmops->lm_get_owner(fl->fl_owner); |
373 | } |
374 | } |
375 | EXPORT_SYMBOL(locks_copy_conflock); |
376 | |
377 | void locks_copy_lock(struct file_lock *new, struct file_lock *fl) |
378 | { |
379 | /* "new" must be a freshly-initialized lock */ |
380 | WARN_ON_ONCE(new->fl_ops); |
381 | |
382 | locks_copy_conflock(new, fl); |
383 | |
384 | new->fl_file = fl->fl_file; |
385 | new->fl_ops = fl->fl_ops; |
386 | |
387 | if (fl->fl_ops) { |
388 | if (fl->fl_ops->fl_copy_lock) |
389 | fl->fl_ops->fl_copy_lock(new, fl); |
390 | } |
391 | } |
392 | |
393 | EXPORT_SYMBOL(locks_copy_lock); |
394 | |
395 | static inline int flock_translate_cmd(int cmd) { |
396 | if (cmd & LOCK_MAND) |
397 | return cmd & (LOCK_MAND | LOCK_RW); |
398 | switch (cmd) { |
399 | case LOCK_SH: |
400 | return F_RDLCK; |
401 | case LOCK_EX: |
402 | return F_WRLCK; |
403 | case LOCK_UN: |
404 | return F_UNLCK; |
405 | } |
406 | return -EINVAL; |
407 | } |
408 | |
409 | /* Fill in a file_lock structure with an appropriate FLOCK lock. */ |
410 | static struct file_lock * |
411 | flock_make_lock(struct file *filp, unsigned int cmd) |
412 | { |
413 | struct file_lock *fl; |
414 | int type = flock_translate_cmd(cmd); |
415 | |
416 | if (type < 0) |
417 | return ERR_PTR(type); |
418 | |
419 | fl = locks_alloc_lock(); |
420 | if (fl == NULL) |
421 | return ERR_PTR(-ENOMEM); |
422 | |
423 | fl->fl_file = filp; |
424 | fl->fl_owner = filp; |
425 | fl->fl_pid = current->tgid; |
426 | fl->fl_flags = FL_FLOCK; |
427 | fl->fl_type = type; |
428 | fl->fl_end = OFFSET_MAX; |
429 | |
430 | return fl; |
431 | } |
432 | |
433 | static int assign_type(struct file_lock *fl, long type) |
434 | { |
435 | switch (type) { |
436 | case F_RDLCK: |
437 | case F_WRLCK: |
438 | case F_UNLCK: |
439 | fl->fl_type = type; |
440 | break; |
441 | default: |
442 | return -EINVAL; |
443 | } |
444 | return 0; |
445 | } |
446 | |
447 | static int flock64_to_posix_lock(struct file *filp, struct file_lock *fl, |
448 | struct flock64 *l) |
449 | { |
450 | switch (l->l_whence) { |
451 | case SEEK_SET: |
452 | fl->fl_start = 0; |
453 | break; |
454 | case SEEK_CUR: |
455 | fl->fl_start = filp->f_pos; |
456 | break; |
457 | case SEEK_END: |
458 | fl->fl_start = i_size_read(file_inode(filp)); |
459 | break; |
460 | default: |
461 | return -EINVAL; |
462 | } |
463 | if (l->l_start > OFFSET_MAX - fl->fl_start) |
464 | return -EOVERFLOW; |
465 | fl->fl_start += l->l_start; |
466 | if (fl->fl_start < 0) |
467 | return -EINVAL; |
468 | |
469 | /* POSIX-1996 leaves the case l->l_len < 0 undefined; |
470 | POSIX-2001 defines it. */ |
471 | if (l->l_len > 0) { |
472 | if (l->l_len - 1 > OFFSET_MAX - fl->fl_start) |
473 | return -EOVERFLOW; |
474 | fl->fl_end = fl->fl_start + l->l_len - 1; |
475 | |
476 | } else if (l->l_len < 0) { |
477 | if (fl->fl_start + l->l_len < 0) |
478 | return -EINVAL; |
479 | fl->fl_end = fl->fl_start - 1; |
480 | fl->fl_start += l->l_len; |
481 | } else |
482 | fl->fl_end = OFFSET_MAX; |
483 | |
484 | fl->fl_owner = current->files; |
485 | fl->fl_pid = current->tgid; |
486 | fl->fl_file = filp; |
487 | fl->fl_flags = FL_POSIX; |
488 | fl->fl_ops = NULL; |
489 | fl->fl_lmops = NULL; |
490 | |
491 | return assign_type(fl, l->l_type); |
492 | } |
493 | |
494 | /* Verify a "struct flock" and copy it to a "struct file_lock" as a POSIX |
495 | * style lock. |
496 | */ |
497 | static int flock_to_posix_lock(struct file *filp, struct file_lock *fl, |
498 | struct flock *l) |
499 | { |
500 | struct flock64 ll = { |
501 | .l_type = l->l_type, |
502 | .l_whence = l->l_whence, |
503 | .l_start = l->l_start, |
504 | .l_len = l->l_len, |
505 | }; |
506 | |
507 | return flock64_to_posix_lock(filp, fl, &ll); |
508 | } |
509 | |
510 | /* default lease lock manager operations */ |
511 | static bool |
512 | lease_break_callback(struct file_lock *fl) |
513 | { |
514 | kill_fasync(&fl->fl_fasync, SIGIO, POLL_MSG); |
515 | return false; |
516 | } |
517 | |
518 | static void |
519 | lease_setup(struct file_lock *fl, void **priv) |
520 | { |
521 | struct file *filp = fl->fl_file; |
522 | struct fasync_struct *fa = *priv; |
523 | |
524 | /* |
525 | * fasync_insert_entry() returns the old entry if any. If there was no |
526 | * old entry, then it used "priv" and inserted it into the fasync list. |
527 | * Clear the pointer to indicate that it shouldn't be freed. |
528 | */ |
529 | if (!fasync_insert_entry(fa->fa_fd, filp, &fl->fl_fasync, fa)) |
530 | *priv = NULL; |
531 | |
532 | __f_setown(filp, task_pid(current), PIDTYPE_PID, 0); |
533 | } |
534 | |
535 | static const struct lock_manager_operations lease_manager_ops = { |
536 | .lm_break = lease_break_callback, |
537 | .lm_change = lease_modify, |
538 | .lm_setup = lease_setup, |
539 | }; |
540 | |
541 | /* |
542 | * Initialize a lease, use the default lock manager operations |
543 | */ |
544 | static int lease_init(struct file *filp, long type, struct file_lock *fl) |
545 | { |
546 | if (assign_type(fl, type) != 0) |
547 | return -EINVAL; |
548 | |
549 | fl->fl_owner = filp; |
550 | fl->fl_pid = current->tgid; |
551 | |
552 | fl->fl_file = filp; |
553 | fl->fl_flags = FL_LEASE; |
554 | fl->fl_start = 0; |
555 | fl->fl_end = OFFSET_MAX; |
556 | fl->fl_ops = NULL; |
557 | fl->fl_lmops = &lease_manager_ops; |
558 | return 0; |
559 | } |
560 | |
561 | /* Allocate a file_lock initialised to this type of lease */ |
562 | static struct file_lock *lease_alloc(struct file *filp, long type) |
563 | { |
564 | struct file_lock *fl = locks_alloc_lock(); |
565 | int error = -ENOMEM; |
566 | |
567 | if (fl == NULL) |
568 | return ERR_PTR(error); |
569 | |
570 | error = lease_init(filp, type, fl); |
571 | if (error) { |
572 | locks_free_lock(fl); |
573 | return ERR_PTR(error); |
574 | } |
575 | return fl; |
576 | } |
577 | |
578 | /* Check if two locks overlap each other. |
579 | */ |
580 | static inline int locks_overlap(struct file_lock *fl1, struct file_lock *fl2) |
581 | { |
582 | return ((fl1->fl_end >= fl2->fl_start) && |
583 | (fl2->fl_end >= fl1->fl_start)); |
584 | } |
585 | |
586 | /* |
587 | * Check whether two locks have the same owner. |
588 | */ |
589 | static int posix_same_owner(struct file_lock *fl1, struct file_lock *fl2) |
590 | { |
591 | if (fl1->fl_lmops && fl1->fl_lmops->lm_compare_owner) |
592 | return fl2->fl_lmops == fl1->fl_lmops && |
593 | fl1->fl_lmops->lm_compare_owner(fl1, fl2); |
594 | return fl1->fl_owner == fl2->fl_owner; |
595 | } |
596 | |
597 | /* Must be called with the flc_lock held! */ |
598 | static void locks_insert_global_locks(struct file_lock *fl) |
599 | { |
600 | struct file_lock_list_struct *fll = this_cpu_ptr(&file_lock_list); |
601 | |
602 | percpu_rwsem_assert_held(&file_rwsem); |
603 | |
604 | spin_lock(&fll->lock); |
605 | fl->fl_link_cpu = smp_processor_id(); |
606 | hlist_add_head(&fl->fl_link, &fll->hlist); |
607 | spin_unlock(&fll->lock); |
608 | } |
609 | |
610 | /* Must be called with the flc_lock held! */ |
611 | static void locks_delete_global_locks(struct file_lock *fl) |
612 | { |
613 | struct file_lock_list_struct *fll; |
614 | |
615 | percpu_rwsem_assert_held(&file_rwsem); |
616 | |
617 | /* |
618 | * Avoid taking lock if already unhashed. This is safe since this check |
619 | * is done while holding the flc_lock, and new insertions into the list |
620 | * also require that it be held. |
621 | */ |
622 | if (hlist_unhashed(&fl->fl_link)) |
623 | return; |
624 | |
625 | fll = per_cpu_ptr(&file_lock_list, fl->fl_link_cpu); |
626 | spin_lock(&fll->lock); |
627 | hlist_del_init(&fl->fl_link); |
628 | spin_unlock(&fll->lock); |
629 | } |
630 | |
631 | static unsigned long |
632 | posix_owner_key(struct file_lock *fl) |
633 | { |
634 | if (fl->fl_lmops && fl->fl_lmops->lm_owner_key) |
635 | return fl->fl_lmops->lm_owner_key(fl); |
636 | return (unsigned long)fl->fl_owner; |
637 | } |
638 | |
639 | static void locks_insert_global_blocked(struct file_lock *waiter) |
640 | { |
641 | lockdep_assert_held(&blocked_lock_lock); |
642 | |
643 | hash_add(blocked_hash, &waiter->fl_link, posix_owner_key(waiter)); |
644 | } |
645 | |
646 | static void locks_delete_global_blocked(struct file_lock *waiter) |
647 | { |
648 | lockdep_assert_held(&blocked_lock_lock); |
649 | |
650 | hash_del(&waiter->fl_link); |
651 | } |
652 | |
653 | /* Remove waiter from blocker's block list. |
654 | * When blocker ends up pointing to itself then the list is empty. |
655 | * |
656 | * Must be called with blocked_lock_lock held. |
657 | */ |
658 | static void __locks_delete_block(struct file_lock *waiter) |
659 | { |
660 | locks_delete_global_blocked(waiter); |
661 | list_del_init(&waiter->fl_block); |
662 | waiter->fl_next = NULL; |
663 | } |
664 | |
665 | static void locks_delete_block(struct file_lock *waiter) |
666 | { |
667 | spin_lock(&blocked_lock_lock); |
668 | __locks_delete_block(waiter); |
669 | spin_unlock(&blocked_lock_lock); |
670 | } |
671 | |
672 | /* Insert waiter into blocker's block list. |
673 | * We use a circular list so that processes can be easily woken up in |
674 | * the order they blocked. The documentation doesn't require this but |
675 | * it seems like the reasonable thing to do. |
676 | * |
677 | * Must be called with both the flc_lock and blocked_lock_lock held. The |
678 | * fl_block list itself is protected by the blocked_lock_lock, but by ensuring |
679 | * that the flc_lock is also held on insertions we can avoid taking the |
680 | * blocked_lock_lock in some cases when we see that the fl_block list is empty. |
681 | */ |
682 | static void __locks_insert_block(struct file_lock *blocker, |
683 | struct file_lock *waiter) |
684 | { |
685 | BUG_ON(!list_empty(&waiter->fl_block)); |
686 | waiter->fl_next = blocker; |
687 | list_add_tail(&waiter->fl_block, &blocker->fl_block); |
688 | if (IS_POSIX(blocker) && !IS_OFDLCK(blocker)) |
689 | locks_insert_global_blocked(waiter); |
690 | } |
691 | |
692 | /* Must be called with flc_lock held. */ |
693 | static void locks_insert_block(struct file_lock *blocker, |
694 | struct file_lock *waiter) |
695 | { |
696 | spin_lock(&blocked_lock_lock); |
697 | __locks_insert_block(blocker, waiter); |
698 | spin_unlock(&blocked_lock_lock); |
699 | } |
700 | |
701 | /* |
702 | * Wake up processes blocked waiting for blocker. |
703 | * |
704 | * Must be called with the inode->flc_lock held! |
705 | */ |
706 | static void locks_wake_up_blocks(struct file_lock *blocker) |
707 | { |
708 | /* |
709 | * Avoid taking global lock if list is empty. This is safe since new |
710 | * blocked requests are only added to the list under the flc_lock, and |
711 | * the flc_lock is always held here. Note that removal from the fl_block |
712 | * list does not require the flc_lock, so we must recheck list_empty() |
713 | * after acquiring the blocked_lock_lock. |
714 | */ |
715 | if (list_empty(&blocker->fl_block)) |
716 | return; |
717 | |
718 | spin_lock(&blocked_lock_lock); |
719 | while (!list_empty(&blocker->fl_block)) { |
720 | struct file_lock *waiter; |
721 | |
722 | waiter = list_first_entry(&blocker->fl_block, |
723 | struct file_lock, fl_block); |
724 | __locks_delete_block(waiter); |
725 | if (waiter->fl_lmops && waiter->fl_lmops->lm_notify) |
726 | waiter->fl_lmops->lm_notify(waiter); |
727 | else |
728 | wake_up(&waiter->fl_wait); |
729 | } |
730 | spin_unlock(&blocked_lock_lock); |
731 | } |
732 | |
733 | static void |
734 | locks_insert_lock_ctx(struct file_lock *fl, struct list_head *before) |
735 | { |
736 | fl->fl_nspid = get_pid(task_tgid(current)); |
737 | list_add_tail(&fl->fl_list, before); |
738 | locks_insert_global_locks(fl); |
739 | } |
740 | |
741 | static void |
742 | locks_unlink_lock_ctx(struct file_lock *fl) |
743 | { |
744 | locks_delete_global_locks(fl); |
745 | list_del_init(&fl->fl_list); |
746 | if (fl->fl_nspid) { |
747 | put_pid(fl->fl_nspid); |
748 | fl->fl_nspid = NULL; |
749 | } |
750 | locks_wake_up_blocks(fl); |
751 | } |
752 | |
753 | static void |
754 | locks_delete_lock_ctx(struct file_lock *fl, struct list_head *dispose) |
755 | { |
756 | locks_unlink_lock_ctx(fl); |
757 | if (dispose) |
758 | list_add(&fl->fl_list, dispose); |
759 | else |
760 | locks_free_lock(fl); |
761 | } |
762 | |
763 | /* Determine if lock sys_fl blocks lock caller_fl. Common functionality |
764 | * checks for shared/exclusive status of overlapping locks. |
765 | */ |
766 | static int locks_conflict(struct file_lock *caller_fl, struct file_lock *sys_fl) |
767 | { |
768 | if (sys_fl->fl_type == F_WRLCK) |
769 | return 1; |
770 | if (caller_fl->fl_type == F_WRLCK) |
771 | return 1; |
772 | return 0; |
773 | } |
774 | |
775 | /* Determine if lock sys_fl blocks lock caller_fl. POSIX specific |
776 | * checking before calling the locks_conflict(). |
777 | */ |
778 | static int posix_locks_conflict(struct file_lock *caller_fl, struct file_lock *sys_fl) |
779 | { |
780 | /* POSIX locks owned by the same process do not conflict with |
781 | * each other. |
782 | */ |
783 | if (posix_same_owner(caller_fl, sys_fl)) |
784 | return (0); |
785 | |
786 | /* Check whether they overlap */ |
787 | if (!locks_overlap(caller_fl, sys_fl)) |
788 | return 0; |
789 | |
790 | return (locks_conflict(caller_fl, sys_fl)); |
791 | } |
792 | |
793 | /* Determine if lock sys_fl blocks lock caller_fl. FLOCK specific |
794 | * checking before calling the locks_conflict(). |
795 | */ |
796 | static int flock_locks_conflict(struct file_lock *caller_fl, struct file_lock *sys_fl) |
797 | { |
798 | /* FLOCK locks referring to the same filp do not conflict with |
799 | * each other. |
800 | */ |
801 | if (caller_fl->fl_file == sys_fl->fl_file) |
802 | return (0); |
803 | if ((caller_fl->fl_type & LOCK_MAND) || (sys_fl->fl_type & LOCK_MAND)) |
804 | return 0; |
805 | |
806 | return (locks_conflict(caller_fl, sys_fl)); |
807 | } |
808 | |
809 | void |
810 | posix_test_lock(struct file *filp, struct file_lock *fl) |
811 | { |
812 | struct file_lock *cfl; |
813 | struct file_lock_context *ctx; |
814 | struct inode *inode = locks_inode(filp); |
815 | |
816 | ctx = smp_load_acquire(&inode->i_flctx); |
817 | if (!ctx || list_empty_careful(&ctx->flc_posix)) { |
818 | fl->fl_type = F_UNLCK; |
819 | return; |
820 | } |
821 | |
822 | spin_lock(&ctx->flc_lock); |
823 | list_for_each_entry(cfl, &ctx->flc_posix, fl_list) { |
824 | if (posix_locks_conflict(fl, cfl)) { |
825 | locks_copy_conflock(fl, cfl); |
826 | if (cfl->fl_nspid) |
827 | fl->fl_pid = pid_vnr(cfl->fl_nspid); |
828 | goto out; |
829 | } |
830 | } |
831 | fl->fl_type = F_UNLCK; |
832 | out: |
833 | spin_unlock(&ctx->flc_lock); |
834 | return; |
835 | } |
836 | EXPORT_SYMBOL(posix_test_lock); |
837 | |
838 | /* |
839 | * Deadlock detection: |
840 | * |
841 | * We attempt to detect deadlocks that are due purely to posix file |
842 | * locks. |
843 | * |
844 | * We assume that a task can be waiting for at most one lock at a time. |
845 | * So for any acquired lock, the process holding that lock may be |
846 | * waiting on at most one other lock. That lock in turns may be held by |
847 | * someone waiting for at most one other lock. Given a requested lock |
848 | * caller_fl which is about to wait for a conflicting lock block_fl, we |
849 | * follow this chain of waiters to ensure we are not about to create a |
850 | * cycle. |
851 | * |
852 | * Since we do this before we ever put a process to sleep on a lock, we |
853 | * are ensured that there is never a cycle; that is what guarantees that |
854 | * the while() loop in posix_locks_deadlock() eventually completes. |
855 | * |
856 | * Note: the above assumption may not be true when handling lock |
857 | * requests from a broken NFS client. It may also fail in the presence |
858 | * of tasks (such as posix threads) sharing the same open file table. |
859 | * To handle those cases, we just bail out after a few iterations. |
860 | * |
861 | * For FL_OFDLCK locks, the owner is the filp, not the files_struct. |
862 | * Because the owner is not even nominally tied to a thread of |
863 | * execution, the deadlock detection below can't reasonably work well. Just |
864 | * skip it for those. |
865 | * |
866 | * In principle, we could do a more limited deadlock detection on FL_OFDLCK |
867 | * locks that just checks for the case where two tasks are attempting to |
868 | * upgrade from read to write locks on the same inode. |
869 | */ |
870 | |
871 | #define MAX_DEADLK_ITERATIONS 10 |
872 | |
873 | /* Find a lock that the owner of the given block_fl is blocking on. */ |
874 | static struct file_lock *what_owner_is_waiting_for(struct file_lock *block_fl) |
875 | { |
876 | struct file_lock *fl; |
877 | |
878 | hash_for_each_possible(blocked_hash, fl, fl_link, posix_owner_key(block_fl)) { |
879 | if (posix_same_owner(fl, block_fl)) |
880 | return fl->fl_next; |
881 | } |
882 | return NULL; |
883 | } |
884 | |
885 | /* Must be called with the blocked_lock_lock held! */ |
886 | static int posix_locks_deadlock(struct file_lock *caller_fl, |
887 | struct file_lock *block_fl) |
888 | { |
889 | int i = 0; |
890 | |
891 | lockdep_assert_held(&blocked_lock_lock); |
892 | |
893 | /* |
894 | * This deadlock detector can't reasonably detect deadlocks with |
895 | * FL_OFDLCK locks, since they aren't owned by a process, per-se. |
896 | */ |
897 | if (IS_OFDLCK(caller_fl)) |
898 | return 0; |
899 | |
900 | while ((block_fl = what_owner_is_waiting_for(block_fl))) { |
901 | if (i++ > MAX_DEADLK_ITERATIONS) |
902 | return 0; |
903 | if (posix_same_owner(caller_fl, block_fl)) |
904 | return 1; |
905 | } |
906 | return 0; |
907 | } |
908 | |
909 | /* Try to create a FLOCK lock on filp. We always insert new FLOCK locks |
910 | * after any leases, but before any posix locks. |
911 | * |
912 | * Note that if called with an FL_EXISTS argument, the caller may determine |
913 | * whether or not a lock was successfully freed by testing the return |
914 | * value for -ENOENT. |
915 | */ |
916 | static int flock_lock_inode(struct inode *inode, struct file_lock *request) |
917 | { |
918 | struct file_lock *new_fl = NULL; |
919 | struct file_lock *fl; |
920 | struct file_lock_context *ctx; |
921 | int error = 0; |
922 | bool found = false; |
923 | LIST_HEAD(dispose); |
924 | |
925 | ctx = locks_get_lock_context(inode, request->fl_type); |
926 | if (!ctx) { |
927 | if (request->fl_type != F_UNLCK) |
928 | return -ENOMEM; |
929 | return (request->fl_flags & FL_EXISTS) ? -ENOENT : 0; |
930 | } |
931 | |
932 | if (!(request->fl_flags & FL_ACCESS) && (request->fl_type != F_UNLCK)) { |
933 | new_fl = locks_alloc_lock(); |
934 | if (!new_fl) |
935 | return -ENOMEM; |
936 | } |
937 | |
938 | percpu_down_read_preempt_disable(&file_rwsem); |
939 | spin_lock(&ctx->flc_lock); |
940 | if (request->fl_flags & FL_ACCESS) |
941 | goto find_conflict; |
942 | |
943 | list_for_each_entry(fl, &ctx->flc_flock, fl_list) { |
944 | if (request->fl_file != fl->fl_file) |
945 | continue; |
946 | if (request->fl_type == fl->fl_type) |
947 | goto out; |
948 | found = true; |
949 | locks_delete_lock_ctx(fl, &dispose); |
950 | break; |
951 | } |
952 | |
953 | if (request->fl_type == F_UNLCK) { |
954 | if ((request->fl_flags & FL_EXISTS) && !found) |
955 | error = -ENOENT; |
956 | goto out; |
957 | } |
958 | |
959 | find_conflict: |
960 | list_for_each_entry(fl, &ctx->flc_flock, fl_list) { |
961 | if (!flock_locks_conflict(request, fl)) |
962 | continue; |
963 | error = -EAGAIN; |
964 | if (!(request->fl_flags & FL_SLEEP)) |
965 | goto out; |
966 | error = FILE_LOCK_DEFERRED; |
967 | locks_insert_block(fl, request); |
968 | goto out; |
969 | } |
970 | if (request->fl_flags & FL_ACCESS) |
971 | goto out; |
972 | locks_copy_lock(new_fl, request); |
973 | locks_insert_lock_ctx(new_fl, &ctx->flc_flock); |
974 | new_fl = NULL; |
975 | error = 0; |
976 | |
977 | out: |
978 | spin_unlock(&ctx->flc_lock); |
979 | percpu_up_read_preempt_enable(&file_rwsem); |
980 | if (new_fl) |
981 | locks_free_lock(new_fl); |
982 | locks_dispose_list(&dispose); |
983 | return error; |
984 | } |
985 | |
986 | static int posix_lock_inode(struct inode *inode, struct file_lock *request, |
987 | struct file_lock *conflock) |
988 | { |
989 | struct file_lock *fl, *tmp; |
990 | struct file_lock *new_fl = NULL; |
991 | struct file_lock *new_fl2 = NULL; |
992 | struct file_lock *left = NULL; |
993 | struct file_lock *right = NULL; |
994 | struct file_lock_context *ctx; |
995 | int error; |
996 | bool added = false; |
997 | LIST_HEAD(dispose); |
998 | |
999 | ctx = locks_get_lock_context(inode, request->fl_type); |
1000 | if (!ctx) |
1001 | return (request->fl_type == F_UNLCK) ? 0 : -ENOMEM; |
1002 | |
1003 | /* |
1004 | * We may need two file_lock structures for this operation, |
1005 | * so we get them in advance to avoid races. |
1006 | * |
1007 | * In some cases we can be sure, that no new locks will be needed |
1008 | */ |
1009 | if (!(request->fl_flags & FL_ACCESS) && |
1010 | (request->fl_type != F_UNLCK || |
1011 | request->fl_start != 0 || request->fl_end != OFFSET_MAX)) { |
1012 | new_fl = locks_alloc_lock(); |
1013 | new_fl2 = locks_alloc_lock(); |
1014 | } |
1015 | |
1016 | percpu_down_read_preempt_disable(&file_rwsem); |
1017 | spin_lock(&ctx->flc_lock); |
1018 | /* |
1019 | * New lock request. Walk all POSIX locks and look for conflicts. If |
1020 | * there are any, either return error or put the request on the |
1021 | * blocker's list of waiters and the global blocked_hash. |
1022 | */ |
1023 | if (request->fl_type != F_UNLCK) { |
1024 | list_for_each_entry(fl, &ctx->flc_posix, fl_list) { |
1025 | if (!posix_locks_conflict(request, fl)) |
1026 | continue; |
1027 | if (conflock) |
1028 | locks_copy_conflock(conflock, fl); |
1029 | error = -EAGAIN; |
1030 | if (!(request->fl_flags & FL_SLEEP)) |
1031 | goto out; |
1032 | /* |
1033 | * Deadlock detection and insertion into the blocked |
1034 | * locks list must be done while holding the same lock! |
1035 | */ |
1036 | error = -EDEADLK; |
1037 | spin_lock(&blocked_lock_lock); |
1038 | if (likely(!posix_locks_deadlock(request, fl))) { |
1039 | error = FILE_LOCK_DEFERRED; |
1040 | __locks_insert_block(fl, request); |
1041 | } |
1042 | spin_unlock(&blocked_lock_lock); |
1043 | goto out; |
1044 | } |
1045 | } |
1046 | |
1047 | /* If we're just looking for a conflict, we're done. */ |
1048 | error = 0; |
1049 | if (request->fl_flags & FL_ACCESS) |
1050 | goto out; |
1051 | |
1052 | /* Find the first old lock with the same owner as the new lock */ |
1053 | list_for_each_entry(fl, &ctx->flc_posix, fl_list) { |
1054 | if (posix_same_owner(request, fl)) |
1055 | break; |
1056 | } |
1057 | |
1058 | /* Process locks with this owner. */ |
1059 | list_for_each_entry_safe_from(fl, tmp, &ctx->flc_posix, fl_list) { |
1060 | if (!posix_same_owner(request, fl)) |
1061 | break; |
1062 | |
1063 | /* Detect adjacent or overlapping regions (if same lock type) */ |
1064 | if (request->fl_type == fl->fl_type) { |
1065 | /* In all comparisons of start vs end, use |
1066 | * "start - 1" rather than "end + 1". If end |
1067 | * is OFFSET_MAX, end + 1 will become negative. |
1068 | */ |
1069 | if (fl->fl_end < request->fl_start - 1) |
1070 | continue; |
1071 | /* If the next lock in the list has entirely bigger |
1072 | * addresses than the new one, insert the lock here. |
1073 | */ |
1074 | if (fl->fl_start - 1 > request->fl_end) |
1075 | break; |
1076 | |
1077 | /* If we come here, the new and old lock are of the |
1078 | * same type and adjacent or overlapping. Make one |
1079 | * lock yielding from the lower start address of both |
1080 | * locks to the higher end address. |
1081 | */ |
1082 | if (fl->fl_start > request->fl_start) |
1083 | fl->fl_start = request->fl_start; |
1084 | else |
1085 | request->fl_start = fl->fl_start; |
1086 | if (fl->fl_end < request->fl_end) |
1087 | fl->fl_end = request->fl_end; |
1088 | else |
1089 | request->fl_end = fl->fl_end; |
1090 | if (added) { |
1091 | locks_delete_lock_ctx(fl, &dispose); |
1092 | continue; |
1093 | } |
1094 | request = fl; |
1095 | added = true; |
1096 | } else { |
1097 | /* Processing for different lock types is a bit |
1098 | * more complex. |
1099 | */ |
1100 | if (fl->fl_end < request->fl_start) |
1101 | continue; |
1102 | if (fl->fl_start > request->fl_end) |
1103 | break; |
1104 | if (request->fl_type == F_UNLCK) |
1105 | added = true; |
1106 | if (fl->fl_start < request->fl_start) |
1107 | left = fl; |
1108 | /* If the next lock in the list has a higher end |
1109 | * address than the new one, insert the new one here. |
1110 | */ |
1111 | if (fl->fl_end > request->fl_end) { |
1112 | right = fl; |
1113 | break; |
1114 | } |
1115 | if (fl->fl_start >= request->fl_start) { |
1116 | /* The new lock completely replaces an old |
1117 | * one (This may happen several times). |
1118 | */ |
1119 | if (added) { |
1120 | locks_delete_lock_ctx(fl, &dispose); |
1121 | continue; |
1122 | } |
1123 | /* |
1124 | * Replace the old lock with new_fl, and |
1125 | * remove the old one. It's safe to do the |
1126 | * insert here since we know that we won't be |
1127 | * using new_fl later, and that the lock is |
1128 | * just replacing an existing lock. |
1129 | */ |
1130 | error = -ENOLCK; |
1131 | if (!new_fl) |
1132 | goto out; |
1133 | locks_copy_lock(new_fl, request); |
1134 | request = new_fl; |
1135 | new_fl = NULL; |
1136 | locks_insert_lock_ctx(request, &fl->fl_list); |
1137 | locks_delete_lock_ctx(fl, &dispose); |
1138 | added = true; |
1139 | } |
1140 | } |
1141 | } |
1142 | |
1143 | /* |
1144 | * The above code only modifies existing locks in case of merging or |
1145 | * replacing. If new lock(s) need to be inserted all modifications are |
1146 | * done below this, so it's safe yet to bail out. |
1147 | */ |
1148 | error = -ENOLCK; /* "no luck" */ |
1149 | if (right && left == right && !new_fl2) |
1150 | goto out; |
1151 | |
1152 | error = 0; |
1153 | if (!added) { |
1154 | if (request->fl_type == F_UNLCK) { |
1155 | if (request->fl_flags & FL_EXISTS) |
1156 | error = -ENOENT; |
1157 | goto out; |
1158 | } |
1159 | |
1160 | if (!new_fl) { |
1161 | error = -ENOLCK; |
1162 | goto out; |
1163 | } |
1164 | locks_copy_lock(new_fl, request); |
1165 | locks_insert_lock_ctx(new_fl, &fl->fl_list); |
1166 | fl = new_fl; |
1167 | new_fl = NULL; |
1168 | } |
1169 | if (right) { |
1170 | if (left == right) { |
1171 | /* The new lock breaks the old one in two pieces, |
1172 | * so we have to use the second new lock. |
1173 | */ |
1174 | left = new_fl2; |
1175 | new_fl2 = NULL; |
1176 | locks_copy_lock(left, right); |
1177 | locks_insert_lock_ctx(left, &fl->fl_list); |
1178 | } |
1179 | right->fl_start = request->fl_end + 1; |
1180 | locks_wake_up_blocks(right); |
1181 | } |
1182 | if (left) { |
1183 | left->fl_end = request->fl_start - 1; |
1184 | locks_wake_up_blocks(left); |
1185 | } |
1186 | out: |
1187 | spin_unlock(&ctx->flc_lock); |
1188 | percpu_up_read_preempt_enable(&file_rwsem); |
1189 | /* |
1190 | * Free any unused locks. |
1191 | */ |
1192 | if (new_fl) |
1193 | locks_free_lock(new_fl); |
1194 | if (new_fl2) |
1195 | locks_free_lock(new_fl2); |
1196 | locks_dispose_list(&dispose); |
1197 | trace_posix_lock_inode(inode, request, error); |
1198 | |
1199 | return error; |
1200 | } |
1201 | |
1202 | /** |
1203 | * posix_lock_file - Apply a POSIX-style lock to a file |
1204 | * @filp: The file to apply the lock to |
1205 | * @fl: The lock to be applied |
1206 | * @conflock: Place to return a copy of the conflicting lock, if found. |
1207 | * |
1208 | * Add a POSIX style lock to a file. |
1209 | * We merge adjacent & overlapping locks whenever possible. |
1210 | * POSIX locks are sorted by owner task, then by starting address |
1211 | * |
1212 | * Note that if called with an FL_EXISTS argument, the caller may determine |
1213 | * whether or not a lock was successfully freed by testing the return |
1214 | * value for -ENOENT. |
1215 | */ |
1216 | int posix_lock_file(struct file *filp, struct file_lock *fl, |
1217 | struct file_lock *conflock) |
1218 | { |
1219 | return posix_lock_inode(locks_inode(filp), fl, conflock); |
1220 | } |
1221 | EXPORT_SYMBOL(posix_lock_file); |
1222 | |
1223 | /** |
1224 | * posix_lock_inode_wait - Apply a POSIX-style lock to a file |
1225 | * @inode: inode of file to which lock request should be applied |
1226 | * @fl: The lock to be applied |
1227 | * |
1228 | * Apply a POSIX style lock request to an inode. |
1229 | */ |
1230 | static int posix_lock_inode_wait(struct inode *inode, struct file_lock *fl) |
1231 | { |
1232 | int error; |
1233 | might_sleep (); |
1234 | for (;;) { |
1235 | error = posix_lock_inode(inode, fl, NULL); |
1236 | if (error != FILE_LOCK_DEFERRED) |
1237 | break; |
1238 | error = wait_event_interruptible(fl->fl_wait, !fl->fl_next); |
1239 | if (!error) |
1240 | continue; |
1241 | |
1242 | locks_delete_block(fl); |
1243 | break; |
1244 | } |
1245 | return error; |
1246 | } |
1247 | |
1248 | #ifdef CONFIG_MANDATORY_FILE_LOCKING |
1249 | /** |
1250 | * locks_mandatory_locked - Check for an active lock |
1251 | * @file: the file to check |
1252 | * |
1253 | * Searches the inode's list of locks to find any POSIX locks which conflict. |
1254 | * This function is called from locks_verify_locked() only. |
1255 | */ |
1256 | int locks_mandatory_locked(struct file *file) |
1257 | { |
1258 | int ret; |
1259 | struct inode *inode = locks_inode(file); |
1260 | struct file_lock_context *ctx; |
1261 | struct file_lock *fl; |
1262 | |
1263 | ctx = smp_load_acquire(&inode->i_flctx); |
1264 | if (!ctx || list_empty_careful(&ctx->flc_posix)) |
1265 | return 0; |
1266 | |
1267 | /* |
1268 | * Search the lock list for this inode for any POSIX locks. |
1269 | */ |
1270 | spin_lock(&ctx->flc_lock); |
1271 | ret = 0; |
1272 | list_for_each_entry(fl, &ctx->flc_posix, fl_list) { |
1273 | if (fl->fl_owner != current->files && |
1274 | fl->fl_owner != file) { |
1275 | ret = -EAGAIN; |
1276 | break; |
1277 | } |
1278 | } |
1279 | spin_unlock(&ctx->flc_lock); |
1280 | return ret; |
1281 | } |
1282 | |
1283 | /** |
1284 | * locks_mandatory_area - Check for a conflicting lock |
1285 | * @inode: the file to check |
1286 | * @filp: how the file was opened (if it was) |
1287 | * @start: first byte in the file to check |
1288 | * @end: lastbyte in the file to check |
1289 | * @type: %F_WRLCK for a write lock, else %F_RDLCK |
1290 | * |
1291 | * Searches the inode's list of locks to find any POSIX locks which conflict. |
1292 | */ |
1293 | int locks_mandatory_area(struct inode *inode, struct file *filp, loff_t start, |
1294 | loff_t end, unsigned char type) |
1295 | { |
1296 | struct file_lock fl; |
1297 | int error; |
1298 | bool sleep = false; |
1299 | |
1300 | locks_init_lock(&fl); |
1301 | fl.fl_pid = current->tgid; |
1302 | fl.fl_file = filp; |
1303 | fl.fl_flags = FL_POSIX | FL_ACCESS; |
1304 | if (filp && !(filp->f_flags & O_NONBLOCK)) |
1305 | sleep = true; |
1306 | fl.fl_type = type; |
1307 | fl.fl_start = start; |
1308 | fl.fl_end = end; |
1309 | |
1310 | for (;;) { |
1311 | if (filp) { |
1312 | fl.fl_owner = filp; |
1313 | fl.fl_flags &= ~FL_SLEEP; |
1314 | error = posix_lock_inode(inode, &fl, NULL); |
1315 | if (!error) |
1316 | break; |
1317 | } |
1318 | |
1319 | if (sleep) |
1320 | fl.fl_flags |= FL_SLEEP; |
1321 | fl.fl_owner = current->files; |
1322 | error = posix_lock_inode(inode, &fl, NULL); |
1323 | if (error != FILE_LOCK_DEFERRED) |
1324 | break; |
1325 | error = wait_event_interruptible(fl.fl_wait, !fl.fl_next); |
1326 | if (!error) { |
1327 | /* |
1328 | * If we've been sleeping someone might have |
1329 | * changed the permissions behind our back. |
1330 | */ |
1331 | if (__mandatory_lock(inode)) |
1332 | continue; |
1333 | } |
1334 | |
1335 | locks_delete_block(&fl); |
1336 | break; |
1337 | } |
1338 | |
1339 | return error; |
1340 | } |
1341 | |
1342 | EXPORT_SYMBOL(locks_mandatory_area); |
1343 | #endif /* CONFIG_MANDATORY_FILE_LOCKING */ |
1344 | |
1345 | static void lease_clear_pending(struct file_lock *fl, int arg) |
1346 | { |
1347 | switch (arg) { |
1348 | case F_UNLCK: |
1349 | fl->fl_flags &= ~FL_UNLOCK_PENDING; |
1350 | /* fall through: */ |
1351 | case F_RDLCK: |
1352 | fl->fl_flags &= ~FL_DOWNGRADE_PENDING; |
1353 | } |
1354 | } |
1355 | |
1356 | /* We already had a lease on this file; just change its type */ |
1357 | int lease_modify(struct file_lock *fl, int arg, struct list_head *dispose) |
1358 | { |
1359 | int error = assign_type(fl, arg); |
1360 | |
1361 | if (error) |
1362 | return error; |
1363 | lease_clear_pending(fl, arg); |
1364 | locks_wake_up_blocks(fl); |
1365 | if (arg == F_UNLCK) { |
1366 | struct file *filp = fl->fl_file; |
1367 | |
1368 | f_delown(filp); |
1369 | filp->f_owner.signum = 0; |
1370 | fasync_helper(0, fl->fl_file, 0, &fl->fl_fasync); |
1371 | if (fl->fl_fasync != NULL) { |
1372 | printk(KERN_ERR "locks_delete_lock: fasync == %p\n", fl->fl_fasync); |
1373 | fl->fl_fasync = NULL; |
1374 | } |
1375 | locks_delete_lock_ctx(fl, dispose); |
1376 | } |
1377 | return 0; |
1378 | } |
1379 | EXPORT_SYMBOL(lease_modify); |
1380 | |
1381 | static bool past_time(unsigned long then) |
1382 | { |
1383 | if (!then) |
1384 | /* 0 is a special value meaning "this never expires": */ |
1385 | return false; |
1386 | return time_after(jiffies, then); |
1387 | } |
1388 | |
1389 | static void time_out_leases(struct inode *inode, struct list_head *dispose) |
1390 | { |
1391 | struct file_lock_context *ctx = inode->i_flctx; |
1392 | struct file_lock *fl, *tmp; |
1393 | |
1394 | lockdep_assert_held(&ctx->flc_lock); |
1395 | |
1396 | list_for_each_entry_safe(fl, tmp, &ctx->flc_lease, fl_list) { |
1397 | trace_time_out_leases(inode, fl); |
1398 | if (past_time(fl->fl_downgrade_time)) |
1399 | lease_modify(fl, F_RDLCK, dispose); |
1400 | if (past_time(fl->fl_break_time)) |
1401 | lease_modify(fl, F_UNLCK, dispose); |
1402 | } |
1403 | } |
1404 | |
1405 | static bool leases_conflict(struct file_lock *lease, struct file_lock *breaker) |
1406 | { |
1407 | if ((breaker->fl_flags & FL_LAYOUT) != (lease->fl_flags & FL_LAYOUT)) |
1408 | return false; |
1409 | if ((breaker->fl_flags & FL_DELEG) && (lease->fl_flags & FL_LEASE)) |
1410 | return false; |
1411 | return locks_conflict(breaker, lease); |
1412 | } |
1413 | |
1414 | static bool |
1415 | any_leases_conflict(struct inode *inode, struct file_lock *breaker) |
1416 | { |
1417 | struct file_lock_context *ctx = inode->i_flctx; |
1418 | struct file_lock *fl; |
1419 | |
1420 | lockdep_assert_held(&ctx->flc_lock); |
1421 | |
1422 | list_for_each_entry(fl, &ctx->flc_lease, fl_list) { |
1423 | if (leases_conflict(fl, breaker)) |
1424 | return true; |
1425 | } |
1426 | return false; |
1427 | } |
1428 | |
1429 | /** |
1430 | * __break_lease - revoke all outstanding leases on file |
1431 | * @inode: the inode of the file to return |
1432 | * @mode: O_RDONLY: break only write leases; O_WRONLY or O_RDWR: |
1433 | * break all leases |
1434 | * @type: FL_LEASE: break leases and delegations; FL_DELEG: break |
1435 | * only delegations |
1436 | * |
1437 | * break_lease (inlined for speed) has checked there already is at least |
1438 | * some kind of lock (maybe a lease) on this file. Leases are broken on |
1439 | * a call to open() or truncate(). This function can sleep unless you |
1440 | * specified %O_NONBLOCK to your open(). |
1441 | */ |
1442 | int __break_lease(struct inode *inode, unsigned int mode, unsigned int type) |
1443 | { |
1444 | int error = 0; |
1445 | struct file_lock_context *ctx; |
1446 | struct file_lock *new_fl, *fl, *tmp; |
1447 | unsigned long break_time; |
1448 | int want_write = (mode & O_ACCMODE) != O_RDONLY; |
1449 | LIST_HEAD(dispose); |
1450 | |
1451 | new_fl = lease_alloc(NULL, want_write ? F_WRLCK : F_RDLCK); |
1452 | if (IS_ERR(new_fl)) |
1453 | return PTR_ERR(new_fl); |
1454 | new_fl->fl_flags = type; |
1455 | |
1456 | /* typically we will check that ctx is non-NULL before calling */ |
1457 | ctx = smp_load_acquire(&inode->i_flctx); |
1458 | if (!ctx) { |
1459 | WARN_ON_ONCE(1); |
1460 | return error; |
1461 | } |
1462 | |
1463 | percpu_down_read_preempt_disable(&file_rwsem); |
1464 | spin_lock(&ctx->flc_lock); |
1465 | |
1466 | time_out_leases(inode, &dispose); |
1467 | |
1468 | if (!any_leases_conflict(inode, new_fl)) |
1469 | goto out; |
1470 | |
1471 | break_time = 0; |
1472 | if (lease_break_time > 0) { |
1473 | break_time = jiffies + lease_break_time * HZ; |
1474 | if (break_time == 0) |
1475 | break_time++; /* so that 0 means no break time */ |
1476 | } |
1477 | |
1478 | list_for_each_entry_safe(fl, tmp, &ctx->flc_lease, fl_list) { |
1479 | if (!leases_conflict(fl, new_fl)) |
1480 | continue; |
1481 | if (want_write) { |
1482 | if (fl->fl_flags & FL_UNLOCK_PENDING) |
1483 | continue; |
1484 | fl->fl_flags |= FL_UNLOCK_PENDING; |
1485 | fl->fl_break_time = break_time; |
1486 | } else { |
1487 | if (lease_breaking(fl)) |
1488 | continue; |
1489 | fl->fl_flags |= FL_DOWNGRADE_PENDING; |
1490 | fl->fl_downgrade_time = break_time; |
1491 | } |
1492 | if (fl->fl_lmops->lm_break(fl)) |
1493 | locks_delete_lock_ctx(fl, &dispose); |
1494 | } |
1495 | |
1496 | if (list_empty(&ctx->flc_lease)) |
1497 | goto out; |
1498 | |
1499 | if (mode & O_NONBLOCK) { |
1500 | trace_break_lease_noblock(inode, new_fl); |
1501 | error = -EWOULDBLOCK; |
1502 | goto out; |
1503 | } |
1504 | |
1505 | restart: |
1506 | fl = list_first_entry(&ctx->flc_lease, struct file_lock, fl_list); |
1507 | break_time = fl->fl_break_time; |
1508 | if (break_time != 0) |
1509 | break_time -= jiffies; |
1510 | if (break_time == 0) |
1511 | break_time++; |
1512 | locks_insert_block(fl, new_fl); |
1513 | trace_break_lease_block(inode, new_fl); |
1514 | spin_unlock(&ctx->flc_lock); |
1515 | percpu_up_read_preempt_enable(&file_rwsem); |
1516 | |
1517 | locks_dispose_list(&dispose); |
1518 | error = wait_event_interruptible_timeout(new_fl->fl_wait, |
1519 | !new_fl->fl_next, break_time); |
1520 | |
1521 | percpu_down_read_preempt_disable(&file_rwsem); |
1522 | spin_lock(&ctx->flc_lock); |
1523 | trace_break_lease_unblock(inode, new_fl); |
1524 | locks_delete_block(new_fl); |
1525 | if (error >= 0) { |
1526 | /* |
1527 | * Wait for the next conflicting lease that has not been |
1528 | * broken yet |
1529 | */ |
1530 | if (error == 0) |
1531 | time_out_leases(inode, &dispose); |
1532 | if (any_leases_conflict(inode, new_fl)) |
1533 | goto restart; |
1534 | error = 0; |
1535 | } |
1536 | out: |
1537 | spin_unlock(&ctx->flc_lock); |
1538 | percpu_up_read_preempt_enable(&file_rwsem); |
1539 | locks_dispose_list(&dispose); |
1540 | locks_free_lock(new_fl); |
1541 | return error; |
1542 | } |
1543 | |
1544 | EXPORT_SYMBOL(__break_lease); |
1545 | |
1546 | /** |
1547 | * lease_get_mtime - get the last modified time of an inode |
1548 | * @inode: the inode |
1549 | * @time: pointer to a timespec which will contain the last modified time |
1550 | * |
1551 | * This is to force NFS clients to flush their caches for files with |
1552 | * exclusive leases. The justification is that if someone has an |
1553 | * exclusive lease, then they could be modifying it. |
1554 | */ |
1555 | void lease_get_mtime(struct inode *inode, struct timespec *time) |
1556 | { |
1557 | bool has_lease = false; |
1558 | struct file_lock_context *ctx; |
1559 | struct file_lock *fl; |
1560 | |
1561 | ctx = smp_load_acquire(&inode->i_flctx); |
1562 | if (ctx && !list_empty_careful(&ctx->flc_lease)) { |
1563 | spin_lock(&ctx->flc_lock); |
1564 | fl = list_first_entry_or_null(&ctx->flc_lease, |
1565 | struct file_lock, fl_list); |
1566 | if (fl && (fl->fl_type == F_WRLCK)) |
1567 | has_lease = true; |
1568 | spin_unlock(&ctx->flc_lock); |
1569 | } |
1570 | |
1571 | if (has_lease) |
1572 | *time = current_time(inode); |
1573 | else |
1574 | *time = inode->i_mtime; |
1575 | } |
1576 | |
1577 | EXPORT_SYMBOL(lease_get_mtime); |
1578 | |
1579 | /** |
1580 | * fcntl_getlease - Enquire what lease is currently active |
1581 | * @filp: the file |
1582 | * |
1583 | * The value returned by this function will be one of |
1584 | * (if no lease break is pending): |
1585 | * |
1586 | * %F_RDLCK to indicate a shared lease is held. |
1587 | * |
1588 | * %F_WRLCK to indicate an exclusive lease is held. |
1589 | * |
1590 | * %F_UNLCK to indicate no lease is held. |
1591 | * |
1592 | * (if a lease break is pending): |
1593 | * |
1594 | * %F_RDLCK to indicate an exclusive lease needs to be |
1595 | * changed to a shared lease (or removed). |
1596 | * |
1597 | * %F_UNLCK to indicate the lease needs to be removed. |
1598 | * |
1599 | * XXX: sfr & willy disagree over whether F_INPROGRESS |
1600 | * should be returned to userspace. |
1601 | */ |
1602 | int fcntl_getlease(struct file *filp) |
1603 | { |
1604 | struct file_lock *fl; |
1605 | struct inode *inode = locks_inode(filp); |
1606 | struct file_lock_context *ctx; |
1607 | int type = F_UNLCK; |
1608 | LIST_HEAD(dispose); |
1609 | |
1610 | ctx = smp_load_acquire(&inode->i_flctx); |
1611 | if (ctx && !list_empty_careful(&ctx->flc_lease)) { |
1612 | percpu_down_read_preempt_disable(&file_rwsem); |
1613 | spin_lock(&ctx->flc_lock); |
1614 | time_out_leases(inode, &dispose); |
1615 | list_for_each_entry(fl, &ctx->flc_lease, fl_list) { |
1616 | if (fl->fl_file != filp) |
1617 | continue; |
1618 | type = target_leasetype(fl); |
1619 | break; |
1620 | } |
1621 | spin_unlock(&ctx->flc_lock); |
1622 | percpu_up_read_preempt_enable(&file_rwsem); |
1623 | |
1624 | locks_dispose_list(&dispose); |
1625 | } |
1626 | return type; |
1627 | } |
1628 | |
1629 | /** |
1630 | * check_conflicting_open - see if the given dentry points to a file that has |
1631 | * an existing open that would conflict with the |
1632 | * desired lease. |
1633 | * @dentry: dentry to check |
1634 | * @arg: type of lease that we're trying to acquire |
1635 | * @flags: current lock flags |
1636 | * |
1637 | * Check to see if there's an existing open fd on this file that would |
1638 | * conflict with the lease we're trying to set. |
1639 | */ |
1640 | static int |
1641 | check_conflicting_open(const struct dentry *dentry, const long arg, int flags) |
1642 | { |
1643 | int ret = 0; |
1644 | struct inode *inode = dentry->d_inode; |
1645 | |
1646 | if (flags & FL_LAYOUT) |
1647 | return 0; |
1648 | |
1649 | if ((arg == F_RDLCK) && |
1650 | (atomic_read(&d_real_inode(dentry)->i_writecount) > 0)) |
1651 | return -EAGAIN; |
1652 | |
1653 | if ((arg == F_WRLCK) && ((d_count(dentry) > 1) || |
1654 | (atomic_read(&inode->i_count) > 1))) |
1655 | ret = -EAGAIN; |
1656 | |
1657 | return ret; |
1658 | } |
1659 | |
1660 | static int |
1661 | generic_add_lease(struct file *filp, long arg, struct file_lock **flp, void **priv) |
1662 | { |
1663 | struct file_lock *fl, *my_fl = NULL, *lease; |
1664 | struct dentry *dentry = filp->f_path.dentry; |
1665 | struct inode *inode = dentry->d_inode; |
1666 | struct file_lock_context *ctx; |
1667 | bool is_deleg = (*flp)->fl_flags & FL_DELEG; |
1668 | int error; |
1669 | LIST_HEAD(dispose); |
1670 | |
1671 | lease = *flp; |
1672 | trace_generic_add_lease(inode, lease); |
1673 | |
1674 | /* Note that arg is never F_UNLCK here */ |
1675 | ctx = locks_get_lock_context(inode, arg); |
1676 | if (!ctx) |
1677 | return -ENOMEM; |
1678 | |
1679 | /* |
1680 | * In the delegation case we need mutual exclusion with |
1681 | * a number of operations that take the i_mutex. We trylock |
1682 | * because delegations are an optional optimization, and if |
1683 | * there's some chance of a conflict--we'd rather not |
1684 | * bother, maybe that's a sign this just isn't a good file to |
1685 | * hand out a delegation on. |
1686 | */ |
1687 | if (is_deleg && !inode_trylock(inode)) |
1688 | return -EAGAIN; |
1689 | |
1690 | if (is_deleg && arg == F_WRLCK) { |
1691 | /* Write delegations are not currently supported: */ |
1692 | inode_unlock(inode); |
1693 | WARN_ON_ONCE(1); |
1694 | return -EINVAL; |
1695 | } |
1696 | |
1697 | percpu_down_read_preempt_disable(&file_rwsem); |
1698 | spin_lock(&ctx->flc_lock); |
1699 | time_out_leases(inode, &dispose); |
1700 | error = check_conflicting_open(dentry, arg, lease->fl_flags); |
1701 | if (error) |
1702 | goto out; |
1703 | |
1704 | /* |
1705 | * At this point, we know that if there is an exclusive |
1706 | * lease on this file, then we hold it on this filp |
1707 | * (otherwise our open of this file would have blocked). |
1708 | * And if we are trying to acquire an exclusive lease, |
1709 | * then the file is not open by anyone (including us) |
1710 | * except for this filp. |
1711 | */ |
1712 | error = -EAGAIN; |
1713 | list_for_each_entry(fl, &ctx->flc_lease, fl_list) { |
1714 | if (fl->fl_file == filp && |
1715 | fl->fl_owner == lease->fl_owner) { |
1716 | my_fl = fl; |
1717 | continue; |
1718 | } |
1719 | |
1720 | /* |
1721 | * No exclusive leases if someone else has a lease on |
1722 | * this file: |
1723 | */ |
1724 | if (arg == F_WRLCK) |
1725 | goto out; |
1726 | /* |
1727 | * Modifying our existing lease is OK, but no getting a |
1728 | * new lease if someone else is opening for write: |
1729 | */ |
1730 | if (fl->fl_flags & FL_UNLOCK_PENDING) |
1731 | goto out; |
1732 | } |
1733 | |
1734 | if (my_fl != NULL) { |
1735 | lease = my_fl; |
1736 | error = lease->fl_lmops->lm_change(lease, arg, &dispose); |
1737 | if (error) |
1738 | goto out; |
1739 | goto out_setup; |
1740 | } |
1741 | |
1742 | error = -EINVAL; |
1743 | if (!leases_enable) |
1744 | goto out; |
1745 | |
1746 | locks_insert_lock_ctx(lease, &ctx->flc_lease); |
1747 | /* |
1748 | * The check in break_lease() is lockless. It's possible for another |
1749 | * open to race in after we did the earlier check for a conflicting |
1750 | * open but before the lease was inserted. Check again for a |
1751 | * conflicting open and cancel the lease if there is one. |
1752 | * |
1753 | * We also add a barrier here to ensure that the insertion of the lock |
1754 | * precedes these checks. |
1755 | */ |
1756 | smp_mb(); |
1757 | error = check_conflicting_open(dentry, arg, lease->fl_flags); |
1758 | if (error) { |
1759 | locks_unlink_lock_ctx(lease); |
1760 | goto out; |
1761 | } |
1762 | |
1763 | out_setup: |
1764 | if (lease->fl_lmops->lm_setup) |
1765 | lease->fl_lmops->lm_setup(lease, priv); |
1766 | out: |
1767 | spin_unlock(&ctx->flc_lock); |
1768 | percpu_up_read_preempt_enable(&file_rwsem); |
1769 | locks_dispose_list(&dispose); |
1770 | if (is_deleg) |
1771 | inode_unlock(inode); |
1772 | if (!error && !my_fl) |
1773 | *flp = NULL; |
1774 | return error; |
1775 | } |
1776 | |
1777 | static int generic_delete_lease(struct file *filp, void *owner) |
1778 | { |
1779 | int error = -EAGAIN; |
1780 | struct file_lock *fl, *victim = NULL; |
1781 | struct inode *inode = locks_inode(filp); |
1782 | struct file_lock_context *ctx; |
1783 | LIST_HEAD(dispose); |
1784 | |
1785 | ctx = smp_load_acquire(&inode->i_flctx); |
1786 | if (!ctx) { |
1787 | trace_generic_delete_lease(inode, NULL); |
1788 | return error; |
1789 | } |
1790 | |
1791 | percpu_down_read_preempt_disable(&file_rwsem); |
1792 | spin_lock(&ctx->flc_lock); |
1793 | list_for_each_entry(fl, &ctx->flc_lease, fl_list) { |
1794 | if (fl->fl_file == filp && |
1795 | fl->fl_owner == owner) { |
1796 | victim = fl; |
1797 | break; |
1798 | } |
1799 | } |
1800 | trace_generic_delete_lease(inode, victim); |
1801 | if (victim) |
1802 | error = fl->fl_lmops->lm_change(victim, F_UNLCK, &dispose); |
1803 | spin_unlock(&ctx->flc_lock); |
1804 | percpu_up_read_preempt_enable(&file_rwsem); |
1805 | locks_dispose_list(&dispose); |
1806 | return error; |
1807 | } |
1808 | |
1809 | /** |
1810 | * generic_setlease - sets a lease on an open file |
1811 | * @filp: file pointer |
1812 | * @arg: type of lease to obtain |
1813 | * @flp: input - file_lock to use, output - file_lock inserted |
1814 | * @priv: private data for lm_setup (may be NULL if lm_setup |
1815 | * doesn't require it) |
1816 | * |
1817 | * The (input) flp->fl_lmops->lm_break function is required |
1818 | * by break_lease(). |
1819 | */ |
1820 | int generic_setlease(struct file *filp, long arg, struct file_lock **flp, |
1821 | void **priv) |
1822 | { |
1823 | struct inode *inode = locks_inode(filp); |
1824 | int error; |
1825 | |
1826 | if ((!uid_eq(current_fsuid(), inode->i_uid)) && !capable(CAP_LEASE)) |
1827 | return -EACCES; |
1828 | if (!S_ISREG(inode->i_mode)) |
1829 | return -EINVAL; |
1830 | error = security_file_lock(filp, arg); |
1831 | if (error) |
1832 | return error; |
1833 | |
1834 | switch (arg) { |
1835 | case F_UNLCK: |
1836 | return generic_delete_lease(filp, *priv); |
1837 | case F_RDLCK: |
1838 | case F_WRLCK: |
1839 | if (!(*flp)->fl_lmops->lm_break) { |
1840 | WARN_ON_ONCE(1); |
1841 | return -ENOLCK; |
1842 | } |
1843 | |
1844 | return generic_add_lease(filp, arg, flp, priv); |
1845 | default: |
1846 | return -EINVAL; |
1847 | } |
1848 | } |
1849 | EXPORT_SYMBOL(generic_setlease); |
1850 | |
1851 | /** |
1852 | * vfs_setlease - sets a lease on an open file |
1853 | * @filp: file pointer |
1854 | * @arg: type of lease to obtain |
1855 | * @lease: file_lock to use when adding a lease |
1856 | * @priv: private info for lm_setup when adding a lease (may be |
1857 | * NULL if lm_setup doesn't require it) |
1858 | * |
1859 | * Call this to establish a lease on the file. The "lease" argument is not |
1860 | * used for F_UNLCK requests and may be NULL. For commands that set or alter |
1861 | * an existing lease, the (*lease)->fl_lmops->lm_break operation must be set; |
1862 | * if not, this function will return -ENOLCK (and generate a scary-looking |
1863 | * stack trace). |
1864 | * |
1865 | * The "priv" pointer is passed directly to the lm_setup function as-is. It |
1866 | * may be NULL if the lm_setup operation doesn't require it. |
1867 | */ |
1868 | int |
1869 | vfs_setlease(struct file *filp, long arg, struct file_lock **lease, void **priv) |
1870 | { |
1871 | if (filp->f_op->setlease && is_remote_lock(filp)) |
1872 | return filp->f_op->setlease(filp, arg, lease, priv); |
1873 | else |
1874 | return generic_setlease(filp, arg, lease, priv); |
1875 | } |
1876 | EXPORT_SYMBOL_GPL(vfs_setlease); |
1877 | |
1878 | static int do_fcntl_add_lease(unsigned int fd, struct file *filp, long arg) |
1879 | { |
1880 | struct file_lock *fl; |
1881 | struct fasync_struct *new; |
1882 | int error; |
1883 | |
1884 | fl = lease_alloc(filp, arg); |
1885 | if (IS_ERR(fl)) |
1886 | return PTR_ERR(fl); |
1887 | |
1888 | new = fasync_alloc(); |
1889 | if (!new) { |
1890 | locks_free_lock(fl); |
1891 | return -ENOMEM; |
1892 | } |
1893 | new->fa_fd = fd; |
1894 | |
1895 | error = vfs_setlease(filp, arg, &fl, (void **)&new); |
1896 | if (fl) |
1897 | locks_free_lock(fl); |
1898 | if (new) |
1899 | fasync_free(new); |
1900 | return error; |
1901 | } |
1902 | |
1903 | /** |
1904 | * fcntl_setlease - sets a lease on an open file |
1905 | * @fd: open file descriptor |
1906 | * @filp: file pointer |
1907 | * @arg: type of lease to obtain |
1908 | * |
1909 | * Call this fcntl to establish a lease on the file. |
1910 | * Note that you also need to call %F_SETSIG to |
1911 | * receive a signal when the lease is broken. |
1912 | */ |
1913 | int fcntl_setlease(unsigned int fd, struct file *filp, long arg) |
1914 | { |
1915 | if (arg == F_UNLCK) |
1916 | return vfs_setlease(filp, F_UNLCK, NULL, (void **)&filp); |
1917 | return do_fcntl_add_lease(fd, filp, arg); |
1918 | } |
1919 | |
1920 | /** |
1921 | * flock_lock_inode_wait - Apply a FLOCK-style lock to a file |
1922 | * @inode: inode of the file to apply to |
1923 | * @fl: The lock to be applied |
1924 | * |
1925 | * Apply a FLOCK style lock request to an inode. |
1926 | */ |
1927 | static int flock_lock_inode_wait(struct inode *inode, struct file_lock *fl) |
1928 | { |
1929 | int error; |
1930 | might_sleep(); |
1931 | for (;;) { |
1932 | error = flock_lock_inode(inode, fl); |
1933 | if (error != FILE_LOCK_DEFERRED) |
1934 | break; |
1935 | error = wait_event_interruptible(fl->fl_wait, !fl->fl_next); |
1936 | if (!error) |
1937 | continue; |
1938 | |
1939 | locks_delete_block(fl); |
1940 | break; |
1941 | } |
1942 | return error; |
1943 | } |
1944 | |
1945 | /** |
1946 | * locks_lock_inode_wait - Apply a lock to an inode |
1947 | * @inode: inode of the file to apply to |
1948 | * @fl: The lock to be applied |
1949 | * |
1950 | * Apply a POSIX or FLOCK style lock request to an inode. |
1951 | */ |
1952 | int locks_lock_inode_wait(struct inode *inode, struct file_lock *fl) |
1953 | { |
1954 | int res = 0; |
1955 | switch (fl->fl_flags & (FL_POSIX|FL_FLOCK)) { |
1956 | case FL_POSIX: |
1957 | res = posix_lock_inode_wait(inode, fl); |
1958 | break; |
1959 | case FL_FLOCK: |
1960 | res = flock_lock_inode_wait(inode, fl); |
1961 | break; |
1962 | default: |
1963 | BUG(); |
1964 | } |
1965 | return res; |
1966 | } |
1967 | EXPORT_SYMBOL(locks_lock_inode_wait); |
1968 | |
1969 | /** |
1970 | * sys_flock: - flock() system call. |
1971 | * @fd: the file descriptor to lock. |
1972 | * @cmd: the type of lock to apply. |
1973 | * |
1974 | * Apply a %FL_FLOCK style lock to an open file descriptor. |
1975 | * The @cmd can be one of |
1976 | * |
1977 | * %LOCK_SH -- a shared lock. |
1978 | * |
1979 | * %LOCK_EX -- an exclusive lock. |
1980 | * |
1981 | * %LOCK_UN -- remove an existing lock. |
1982 | * |
1983 | * %LOCK_MAND -- a `mandatory' flock. This exists to emulate Windows Share Modes. |
1984 | * |
1985 | * %LOCK_MAND can be combined with %LOCK_READ or %LOCK_WRITE to allow other |
1986 | * processes read and write access respectively. |
1987 | */ |
1988 | SYSCALL_DEFINE2(flock, unsigned int, fd, unsigned int, cmd) |
1989 | { |
1990 | struct fd f = fdget(fd); |
1991 | struct file_lock *lock; |
1992 | int can_sleep, unlock; |
1993 | int error; |
1994 | |
1995 | error = -EBADF; |
1996 | if (!f.file) |
1997 | goto out; |
1998 | |
1999 | can_sleep = !(cmd & LOCK_NB); |
2000 | cmd &= ~LOCK_NB; |
2001 | unlock = (cmd == LOCK_UN); |
2002 | |
2003 | if (!unlock && !(cmd & LOCK_MAND) && |
2004 | !(f.file->f_mode & (FMODE_READ|FMODE_WRITE))) |
2005 | goto out_putf; |
2006 | |
2007 | lock = flock_make_lock(f.file, cmd); |
2008 | if (IS_ERR(lock)) { |
2009 | error = PTR_ERR(lock); |
2010 | goto out_putf; |
2011 | } |
2012 | |
2013 | if (can_sleep) |
2014 | lock->fl_flags |= FL_SLEEP; |
2015 | |
2016 | error = security_file_lock(f.file, lock->fl_type); |
2017 | if (error) |
2018 | goto out_free; |
2019 | |
2020 | if (f.file->f_op->flock && is_remote_lock(f.file)) |
2021 | error = f.file->f_op->flock(f.file, |
2022 | (can_sleep) ? F_SETLKW : F_SETLK, |
2023 | lock); |
2024 | else |
2025 | error = locks_lock_file_wait(f.file, lock); |
2026 | |
2027 | out_free: |
2028 | locks_free_lock(lock); |
2029 | |
2030 | out_putf: |
2031 | fdput(f); |
2032 | out: |
2033 | return error; |
2034 | } |
2035 | |
2036 | /** |
2037 | * vfs_test_lock - test file byte range lock |
2038 | * @filp: The file to test lock for |
2039 | * @fl: The lock to test; also used to hold result |
2040 | * |
2041 | * Returns -ERRNO on failure. Indicates presence of conflicting lock by |
2042 | * setting conf->fl_type to something other than F_UNLCK. |
2043 | */ |
2044 | int vfs_test_lock(struct file *filp, struct file_lock *fl) |
2045 | { |
2046 | if (filp->f_op->lock && is_remote_lock(filp)) |
2047 | return filp->f_op->lock(filp, F_GETLK, fl); |
2048 | posix_test_lock(filp, fl); |
2049 | return 0; |
2050 | } |
2051 | EXPORT_SYMBOL_GPL(vfs_test_lock); |
2052 | |
2053 | static int posix_lock_to_flock(struct flock *flock, struct file_lock *fl) |
2054 | { |
2055 | flock->l_pid = IS_OFDLCK(fl) ? -1 : fl->fl_pid; |
2056 | #if BITS_PER_LONG == 32 |
2057 | /* |
2058 | * Make sure we can represent the posix lock via |
2059 | * legacy 32bit flock. |
2060 | */ |
2061 | if (fl->fl_start > OFFT_OFFSET_MAX) |
2062 | return -EOVERFLOW; |
2063 | if (fl->fl_end != OFFSET_MAX && fl->fl_end > OFFT_OFFSET_MAX) |
2064 | return -EOVERFLOW; |
2065 | #endif |
2066 | flock->l_start = fl->fl_start; |
2067 | flock->l_len = fl->fl_end == OFFSET_MAX ? 0 : |
2068 | fl->fl_end - fl->fl_start + 1; |
2069 | flock->l_whence = 0; |
2070 | flock->l_type = fl->fl_type; |
2071 | return 0; |
2072 | } |
2073 | |
2074 | #if BITS_PER_LONG == 32 |
2075 | static void posix_lock_to_flock64(struct flock64 *flock, struct file_lock *fl) |
2076 | { |
2077 | flock->l_pid = IS_OFDLCK(fl) ? -1 : fl->fl_pid; |
2078 | flock->l_start = fl->fl_start; |
2079 | flock->l_len = fl->fl_end == OFFSET_MAX ? 0 : |
2080 | fl->fl_end - fl->fl_start + 1; |
2081 | flock->l_whence = 0; |
2082 | flock->l_type = fl->fl_type; |
2083 | } |
2084 | #endif |
2085 | |
2086 | /* Report the first existing lock that would conflict with l. |
2087 | * This implements the F_GETLK command of fcntl(). |
2088 | */ |
2089 | int fcntl_getlk(struct file *filp, unsigned int cmd, struct flock __user *l) |
2090 | { |
2091 | struct file_lock file_lock; |
2092 | struct flock flock; |
2093 | int error; |
2094 | |
2095 | error = -EFAULT; |
2096 | if (copy_from_user(&flock, l, sizeof(flock))) |
2097 | goto out; |
2098 | error = -EINVAL; |
2099 | if ((flock.l_type != F_RDLCK) && (flock.l_type != F_WRLCK)) |
2100 | goto out; |
2101 | |
2102 | error = flock_to_posix_lock(filp, &file_lock, &flock); |
2103 | if (error) |
2104 | goto out; |
2105 | |
2106 | if (cmd == F_OFD_GETLK) { |
2107 | error = -EINVAL; |
2108 | if (flock.l_pid != 0) |
2109 | goto out; |
2110 | |
2111 | cmd = F_GETLK; |
2112 | file_lock.fl_flags |= FL_OFDLCK; |
2113 | file_lock.fl_owner = filp; |
2114 | } |
2115 | |
2116 | error = vfs_test_lock(filp, &file_lock); |
2117 | if (error) |
2118 | goto out; |
2119 | |
2120 | flock.l_type = file_lock.fl_type; |
2121 | if (file_lock.fl_type != F_UNLCK) { |
2122 | error = posix_lock_to_flock(&flock, &file_lock); |
2123 | if (error) |
2124 | goto rel_priv; |
2125 | } |
2126 | error = -EFAULT; |
2127 | if (!copy_to_user(l, &flock, sizeof(flock))) |
2128 | error = 0; |
2129 | rel_priv: |
2130 | locks_release_private(&file_lock); |
2131 | out: |
2132 | return error; |
2133 | } |
2134 | |
2135 | /** |
2136 | * vfs_lock_file - file byte range lock |
2137 | * @filp: The file to apply the lock to |
2138 | * @cmd: type of locking operation (F_SETLK, F_GETLK, etc.) |
2139 | * @fl: The lock to be applied |
2140 | * @conf: Place to return a copy of the conflicting lock, if found. |
2141 | * |
2142 | * A caller that doesn't care about the conflicting lock may pass NULL |
2143 | * as the final argument. |
2144 | * |
2145 | * If the filesystem defines a private ->lock() method, then @conf will |
2146 | * be left unchanged; so a caller that cares should initialize it to |
2147 | * some acceptable default. |
2148 | * |
2149 | * To avoid blocking kernel daemons, such as lockd, that need to acquire POSIX |
2150 | * locks, the ->lock() interface may return asynchronously, before the lock has |
2151 | * been granted or denied by the underlying filesystem, if (and only if) |
2152 | * lm_grant is set. Callers expecting ->lock() to return asynchronously |
2153 | * will only use F_SETLK, not F_SETLKW; they will set FL_SLEEP if (and only if) |
2154 | * the request is for a blocking lock. When ->lock() does return asynchronously, |
2155 | * it must return FILE_LOCK_DEFERRED, and call ->lm_grant() when the lock |
2156 | * request completes. |
2157 | * If the request is for non-blocking lock the file system should return |
2158 | * FILE_LOCK_DEFERRED then try to get the lock and call the callback routine |
2159 | * with the result. If the request timed out the callback routine will return a |
2160 | * nonzero return code and the file system should release the lock. The file |
2161 | * system is also responsible to keep a corresponding posix lock when it |
2162 | * grants a lock so the VFS can find out which locks are locally held and do |
2163 | * the correct lock cleanup when required. |
2164 | * The underlying filesystem must not drop the kernel lock or call |
2165 | * ->lm_grant() before returning to the caller with a FILE_LOCK_DEFERRED |
2166 | * return code. |
2167 | */ |
2168 | int vfs_lock_file(struct file *filp, unsigned int cmd, struct file_lock *fl, struct file_lock *conf) |
2169 | { |
2170 | if (filp->f_op->lock && is_remote_lock(filp)) |
2171 | return filp->f_op->lock(filp, cmd, fl); |
2172 | else |
2173 | return posix_lock_file(filp, fl, conf); |
2174 | } |
2175 | EXPORT_SYMBOL_GPL(vfs_lock_file); |
2176 | |
2177 | static int do_lock_file_wait(struct file *filp, unsigned int cmd, |
2178 | struct file_lock *fl) |
2179 | { |
2180 | int error; |
2181 | |
2182 | error = security_file_lock(filp, fl->fl_type); |
2183 | if (error) |
2184 | return error; |
2185 | |
2186 | for (;;) { |
2187 | error = vfs_lock_file(filp, cmd, fl, NULL); |
2188 | if (error != FILE_LOCK_DEFERRED) |
2189 | break; |
2190 | error = wait_event_interruptible(fl->fl_wait, !fl->fl_next); |
2191 | if (!error) |
2192 | continue; |
2193 | |
2194 | locks_delete_block(fl); |
2195 | break; |
2196 | } |
2197 | |
2198 | return error; |
2199 | } |
2200 | |
2201 | /* Ensure that fl->fl_file has compatible f_mode for F_SETLK calls */ |
2202 | static int |
2203 | check_fmode_for_setlk(struct file_lock *fl) |
2204 | { |
2205 | switch (fl->fl_type) { |
2206 | case F_RDLCK: |
2207 | if (!(fl->fl_file->f_mode & FMODE_READ)) |
2208 | return -EBADF; |
2209 | break; |
2210 | case F_WRLCK: |
2211 | if (!(fl->fl_file->f_mode & FMODE_WRITE)) |
2212 | return -EBADF; |
2213 | } |
2214 | return 0; |
2215 | } |
2216 | |
2217 | /* Apply the lock described by l to an open file descriptor. |
2218 | * This implements both the F_SETLK and F_SETLKW commands of fcntl(). |
2219 | */ |
2220 | int fcntl_setlk(unsigned int fd, struct file *filp, unsigned int cmd, |
2221 | struct flock __user *l) |
2222 | { |
2223 | struct file_lock *file_lock = locks_alloc_lock(); |
2224 | struct flock flock; |
2225 | struct inode *inode; |
2226 | struct file *f; |
2227 | int error; |
2228 | |
2229 | if (file_lock == NULL) |
2230 | return -ENOLCK; |
2231 | |
2232 | inode = locks_inode(filp); |
2233 | |
2234 | /* |
2235 | * This might block, so we do it before checking the inode. |
2236 | */ |
2237 | error = -EFAULT; |
2238 | if (copy_from_user(&flock, l, sizeof(flock))) |
2239 | goto out; |
2240 | |
2241 | /* Don't allow mandatory locks on files that may be memory mapped |
2242 | * and shared. |
2243 | */ |
2244 | if (mandatory_lock(inode) && mapping_writably_mapped(filp->f_mapping)) { |
2245 | error = -EAGAIN; |
2246 | goto out; |
2247 | } |
2248 | |
2249 | error = flock_to_posix_lock(filp, file_lock, &flock); |
2250 | if (error) |
2251 | goto out; |
2252 | |
2253 | error = check_fmode_for_setlk(file_lock); |
2254 | if (error) |
2255 | goto out; |
2256 | |
2257 | /* |
2258 | * If the cmd is requesting file-private locks, then set the |
2259 | * FL_OFDLCK flag and override the owner. |
2260 | */ |
2261 | switch (cmd) { |
2262 | case F_OFD_SETLK: |
2263 | error = -EINVAL; |
2264 | if (flock.l_pid != 0) |
2265 | goto out; |
2266 | |
2267 | cmd = F_SETLK; |
2268 | file_lock->fl_flags |= FL_OFDLCK; |
2269 | file_lock->fl_owner = filp; |
2270 | break; |
2271 | case F_OFD_SETLKW: |
2272 | error = -EINVAL; |
2273 | if (flock.l_pid != 0) |
2274 | goto out; |
2275 | |
2276 | cmd = F_SETLKW; |
2277 | file_lock->fl_flags |= FL_OFDLCK; |
2278 | file_lock->fl_owner = filp; |
2279 | /* Fallthrough */ |
2280 | case F_SETLKW: |
2281 | file_lock->fl_flags |= FL_SLEEP; |
2282 | } |
2283 | |
2284 | error = do_lock_file_wait(filp, cmd, file_lock); |
2285 | |
2286 | /* |
2287 | * Attempt to detect a close/fcntl race and recover by releasing the |
2288 | * lock that was just acquired. There is no need to do that when we're |
2289 | * unlocking though, or for OFD locks. |
2290 | */ |
2291 | if (!error && file_lock->fl_type != F_UNLCK && |
2292 | !(file_lock->fl_flags & FL_OFDLCK)) { |
2293 | /* |
2294 | * We need that spin_lock here - it prevents reordering between |
2295 | * update of i_flctx->flc_posix and check for it done in |
2296 | * close(). rcu_read_lock() wouldn't do. |
2297 | */ |
2298 | spin_lock(¤t->files->file_lock); |
2299 | f = fcheck(fd); |
2300 | spin_unlock(¤t->files->file_lock); |
2301 | if (f != filp) { |
2302 | file_lock->fl_type = F_UNLCK; |
2303 | error = do_lock_file_wait(filp, cmd, file_lock); |
2304 | WARN_ON_ONCE(error); |
2305 | error = -EBADF; |
2306 | } |
2307 | } |
2308 | out: |
2309 | trace_fcntl_setlk(inode, file_lock, error); |
2310 | locks_free_lock(file_lock); |
2311 | return error; |
2312 | } |
2313 | |
2314 | #if BITS_PER_LONG == 32 |
2315 | /* Report the first existing lock that would conflict with l. |
2316 | * This implements the F_GETLK command of fcntl(). |
2317 | */ |
2318 | int fcntl_getlk64(struct file *filp, unsigned int cmd, struct flock64 __user *l) |
2319 | { |
2320 | struct file_lock file_lock; |
2321 | struct flock64 flock; |
2322 | int error; |
2323 | |
2324 | error = -EFAULT; |
2325 | if (copy_from_user(&flock, l, sizeof(flock))) |
2326 | goto out; |
2327 | error = -EINVAL; |
2328 | if ((flock.l_type != F_RDLCK) && (flock.l_type != F_WRLCK)) |
2329 | goto out; |
2330 | |
2331 | error = flock64_to_posix_lock(filp, &file_lock, &flock); |
2332 | if (error) |
2333 | goto out; |
2334 | |
2335 | if (cmd == F_OFD_GETLK) { |
2336 | error = -EINVAL; |
2337 | if (flock.l_pid != 0) |
2338 | goto out; |
2339 | |
2340 | cmd = F_GETLK64; |
2341 | file_lock.fl_flags |= FL_OFDLCK; |
2342 | file_lock.fl_owner = filp; |
2343 | } |
2344 | |
2345 | error = vfs_test_lock(filp, &file_lock); |
2346 | if (error) |
2347 | goto out; |
2348 | |
2349 | flock.l_type = file_lock.fl_type; |
2350 | if (file_lock.fl_type != F_UNLCK) |
2351 | posix_lock_to_flock64(&flock, &file_lock); |
2352 | |
2353 | error = -EFAULT; |
2354 | if (!copy_to_user(l, &flock, sizeof(flock))) |
2355 | error = 0; |
2356 | |
2357 | locks_release_private(&file_lock); |
2358 | out: |
2359 | return error; |
2360 | } |
2361 | |
2362 | /* Apply the lock described by l to an open file descriptor. |
2363 | * This implements both the F_SETLK and F_SETLKW commands of fcntl(). |
2364 | */ |
2365 | int fcntl_setlk64(unsigned int fd, struct file *filp, unsigned int cmd, |
2366 | struct flock64 __user *l) |
2367 | { |
2368 | struct file_lock *file_lock = locks_alloc_lock(); |
2369 | struct flock64 flock; |
2370 | struct inode *inode; |
2371 | struct file *f; |
2372 | int error; |
2373 | |
2374 | if (file_lock == NULL) |
2375 | return -ENOLCK; |
2376 | |
2377 | /* |
2378 | * This might block, so we do it before checking the inode. |
2379 | */ |
2380 | error = -EFAULT; |
2381 | if (copy_from_user(&flock, l, sizeof(flock))) |
2382 | goto out; |
2383 | |
2384 | inode = locks_inode(filp); |
2385 | |
2386 | /* Don't allow mandatory locks on files that may be memory mapped |
2387 | * and shared. |
2388 | */ |
2389 | if (mandatory_lock(inode) && mapping_writably_mapped(filp->f_mapping)) { |
2390 | error = -EAGAIN; |
2391 | goto out; |
2392 | } |
2393 | |
2394 | error = flock64_to_posix_lock(filp, file_lock, &flock); |
2395 | if (error) |
2396 | goto out; |
2397 | |
2398 | error = check_fmode_for_setlk(file_lock); |
2399 | if (error) |
2400 | goto out; |
2401 | |
2402 | /* |
2403 | * If the cmd is requesting file-private locks, then set the |
2404 | * FL_OFDLCK flag and override the owner. |
2405 | */ |
2406 | switch (cmd) { |
2407 | case F_OFD_SETLK: |
2408 | error = -EINVAL; |
2409 | if (flock.l_pid != 0) |
2410 | goto out; |
2411 | |
2412 | cmd = F_SETLK64; |
2413 | file_lock->fl_flags |= FL_OFDLCK; |
2414 | file_lock->fl_owner = filp; |
2415 | break; |
2416 | case F_OFD_SETLKW: |
2417 | error = -EINVAL; |
2418 | if (flock.l_pid != 0) |
2419 | goto out; |
2420 | |
2421 | cmd = F_SETLKW64; |
2422 | file_lock->fl_flags |= FL_OFDLCK; |
2423 | file_lock->fl_owner = filp; |
2424 | /* Fallthrough */ |
2425 | case F_SETLKW64: |
2426 | file_lock->fl_flags |= FL_SLEEP; |
2427 | } |
2428 | |
2429 | error = do_lock_file_wait(filp, cmd, file_lock); |
2430 | |
2431 | /* |
2432 | * Attempt to detect a close/fcntl race and recover by releasing the |
2433 | * lock that was just acquired. There is no need to do that when we're |
2434 | * unlocking though, or for OFD locks. |
2435 | */ |
2436 | if (!error && file_lock->fl_type != F_UNLCK && |
2437 | !(file_lock->fl_flags & FL_OFDLCK)) { |
2438 | /* |
2439 | * We need that spin_lock here - it prevents reordering between |
2440 | * update of i_flctx->flc_posix and check for it done in |
2441 | * close(). rcu_read_lock() wouldn't do. |
2442 | */ |
2443 | spin_lock(¤t->files->file_lock); |
2444 | f = fcheck(fd); |
2445 | spin_unlock(¤t->files->file_lock); |
2446 | if (f != filp) { |
2447 | file_lock->fl_type = F_UNLCK; |
2448 | error = do_lock_file_wait(filp, cmd, file_lock); |
2449 | WARN_ON_ONCE(error); |
2450 | error = -EBADF; |
2451 | } |
2452 | } |
2453 | out: |
2454 | locks_free_lock(file_lock); |
2455 | return error; |
2456 | } |
2457 | #endif /* BITS_PER_LONG == 32 */ |
2458 | |
2459 | /* |
2460 | * This function is called when the file is being removed |
2461 | * from the task's fd array. POSIX locks belonging to this task |
2462 | * are deleted at this time. |
2463 | */ |
2464 | void locks_remove_posix(struct file *filp, fl_owner_t owner) |
2465 | { |
2466 | int error; |
2467 | struct inode *inode = locks_inode(filp); |
2468 | struct file_lock lock; |
2469 | struct file_lock_context *ctx; |
2470 | |
2471 | /* |
2472 | * If there are no locks held on this file, we don't need to call |
2473 | * posix_lock_file(). Another process could be setting a lock on this |
2474 | * file at the same time, but we wouldn't remove that lock anyway. |
2475 | */ |
2476 | ctx = smp_load_acquire(&inode->i_flctx); |
2477 | if (!ctx || list_empty(&ctx->flc_posix)) |
2478 | return; |
2479 | |
2480 | lock.fl_type = F_UNLCK; |
2481 | lock.fl_flags = FL_POSIX | FL_CLOSE; |
2482 | lock.fl_start = 0; |
2483 | lock.fl_end = OFFSET_MAX; |
2484 | lock.fl_owner = owner; |
2485 | lock.fl_pid = current->tgid; |
2486 | lock.fl_file = filp; |
2487 | lock.fl_ops = NULL; |
2488 | lock.fl_lmops = NULL; |
2489 | |
2490 | error = vfs_lock_file(filp, F_SETLK, &lock, NULL); |
2491 | |
2492 | if (lock.fl_ops && lock.fl_ops->fl_release_private) |
2493 | lock.fl_ops->fl_release_private(&lock); |
2494 | trace_locks_remove_posix(inode, &lock, error); |
2495 | } |
2496 | |
2497 | EXPORT_SYMBOL(locks_remove_posix); |
2498 | |
2499 | /* The i_flctx must be valid when calling into here */ |
2500 | static void |
2501 | locks_remove_flock(struct file *filp, struct file_lock_context *flctx) |
2502 | { |
2503 | struct file_lock fl = { |
2504 | .fl_owner = filp, |
2505 | .fl_pid = current->tgid, |
2506 | .fl_file = filp, |
2507 | .fl_flags = FL_FLOCK, |
2508 | .fl_type = F_UNLCK, |
2509 | .fl_end = OFFSET_MAX, |
2510 | }; |
2511 | struct inode *inode = locks_inode(filp); |
2512 | |
2513 | if (list_empty(&flctx->flc_flock)) |
2514 | return; |
2515 | |
2516 | if (filp->f_op->flock && is_remote_lock(filp)) |
2517 | filp->f_op->flock(filp, F_SETLKW, &fl); |
2518 | else |
2519 | flock_lock_inode(inode, &fl); |
2520 | |
2521 | if (fl.fl_ops && fl.fl_ops->fl_release_private) |
2522 | fl.fl_ops->fl_release_private(&fl); |
2523 | } |
2524 | |
2525 | /* The i_flctx must be valid when calling into here */ |
2526 | static void |
2527 | locks_remove_lease(struct file *filp, struct file_lock_context *ctx) |
2528 | { |
2529 | struct file_lock *fl, *tmp; |
2530 | LIST_HEAD(dispose); |
2531 | |
2532 | if (list_empty(&ctx->flc_lease)) |
2533 | return; |
2534 | |
2535 | percpu_down_read_preempt_disable(&file_rwsem); |
2536 | spin_lock(&ctx->flc_lock); |
2537 | list_for_each_entry_safe(fl, tmp, &ctx->flc_lease, fl_list) |
2538 | if (filp == fl->fl_file) |
2539 | lease_modify(fl, F_UNLCK, &dispose); |
2540 | spin_unlock(&ctx->flc_lock); |
2541 | percpu_up_read_preempt_enable(&file_rwsem); |
2542 | |
2543 | locks_dispose_list(&dispose); |
2544 | } |
2545 | |
2546 | /* |
2547 | * This function is called on the last close of an open file. |
2548 | */ |
2549 | void locks_remove_file(struct file *filp) |
2550 | { |
2551 | struct file_lock_context *ctx; |
2552 | |
2553 | ctx = smp_load_acquire(&locks_inode(filp)->i_flctx); |
2554 | if (!ctx) |
2555 | return; |
2556 | |
2557 | /* remove any OFD locks */ |
2558 | locks_remove_posix(filp, filp); |
2559 | |
2560 | /* remove flock locks */ |
2561 | locks_remove_flock(filp, ctx); |
2562 | |
2563 | /* remove any leases */ |
2564 | locks_remove_lease(filp, ctx); |
2565 | } |
2566 | |
2567 | /** |
2568 | * posix_unblock_lock - stop waiting for a file lock |
2569 | * @waiter: the lock which was waiting |
2570 | * |
2571 | * lockd needs to block waiting for locks. |
2572 | */ |
2573 | int |
2574 | posix_unblock_lock(struct file_lock *waiter) |
2575 | { |
2576 | int status = 0; |
2577 | |
2578 | spin_lock(&blocked_lock_lock); |
2579 | if (waiter->fl_next) |
2580 | __locks_delete_block(waiter); |
2581 | else |
2582 | status = -ENOENT; |
2583 | spin_unlock(&blocked_lock_lock); |
2584 | return status; |
2585 | } |
2586 | EXPORT_SYMBOL(posix_unblock_lock); |
2587 | |
2588 | /** |
2589 | * vfs_cancel_lock - file byte range unblock lock |
2590 | * @filp: The file to apply the unblock to |
2591 | * @fl: The lock to be unblocked |
2592 | * |
2593 | * Used by lock managers to cancel blocked requests |
2594 | */ |
2595 | int vfs_cancel_lock(struct file *filp, struct file_lock *fl) |
2596 | { |
2597 | if (filp->f_op->lock && is_remote_lock(filp)) |
2598 | return filp->f_op->lock(filp, F_CANCELLK, fl); |
2599 | return 0; |
2600 | } |
2601 | |
2602 | EXPORT_SYMBOL_GPL(vfs_cancel_lock); |
2603 | |
2604 | #ifdef CONFIG_PROC_FS |
2605 | #include <linux/proc_fs.h> |
2606 | #include <linux/seq_file.h> |
2607 | |
2608 | struct locks_iterator { |
2609 | int li_cpu; |
2610 | loff_t li_pos; |
2611 | }; |
2612 | |
2613 | static void lock_get_status(struct seq_file *f, struct file_lock *fl, |
2614 | loff_t id, char *pfx) |
2615 | { |
2616 | struct inode *inode = NULL; |
2617 | unsigned int fl_pid; |
2618 | |
2619 | if (fl->fl_nspid) { |
2620 | struct pid_namespace *proc_pidns = file_inode(f->file)->i_sb->s_fs_info; |
2621 | |
2622 | /* Don't let fl_pid change based on who is reading the file */ |
2623 | fl_pid = pid_nr_ns(fl->fl_nspid, proc_pidns); |
2624 | |
2625 | /* |
2626 | * If there isn't a fl_pid don't display who is waiting on |
2627 | * the lock if we are called from locks_show, or if we are |
2628 | * called from __show_fd_info - skip lock entirely |
2629 | */ |
2630 | if (fl_pid == 0) |
2631 | return; |
2632 | } else |
2633 | fl_pid = fl->fl_pid; |
2634 | |
2635 | if (fl->fl_file != NULL) |
2636 | inode = locks_inode(fl->fl_file); |
2637 | |
2638 | seq_printf(f, "%lld:%s ", id, pfx); |
2639 | if (IS_POSIX(fl)) { |
2640 | if (fl->fl_flags & FL_ACCESS) |
2641 | seq_puts(f, "ACCESS"); |
2642 | else if (IS_OFDLCK(fl)) |
2643 | seq_puts(f, "OFDLCK"); |
2644 | else |
2645 | seq_puts(f, "POSIX "); |
2646 | |
2647 | seq_printf(f, " %s ", |
2648 | (inode == NULL) ? "*NOINODE*" : |
2649 | mandatory_lock(inode) ? "MANDATORY" : "ADVISORY "); |
2650 | } else if (IS_FLOCK(fl)) { |
2651 | if (fl->fl_type & LOCK_MAND) { |
2652 | seq_puts(f, "FLOCK MSNFS "); |
2653 | } else { |
2654 | seq_puts(f, "FLOCK ADVISORY "); |
2655 | } |
2656 | } else if (IS_LEASE(fl)) { |
2657 | if (fl->fl_flags & FL_DELEG) |
2658 | seq_puts(f, "DELEG "); |
2659 | else |
2660 | seq_puts(f, "LEASE "); |
2661 | |
2662 | if (lease_breaking(fl)) |
2663 | seq_puts(f, "BREAKING "); |
2664 | else if (fl->fl_file) |
2665 | seq_puts(f, "ACTIVE "); |
2666 | else |
2667 | seq_puts(f, "BREAKER "); |
2668 | } else { |
2669 | seq_puts(f, "UNKNOWN UNKNOWN "); |
2670 | } |
2671 | if (fl->fl_type & LOCK_MAND) { |
2672 | seq_printf(f, "%s ", |
2673 | (fl->fl_type & LOCK_READ) |
2674 | ? (fl->fl_type & LOCK_WRITE) ? "RW " : "READ " |
2675 | : (fl->fl_type & LOCK_WRITE) ? "WRITE" : "NONE "); |
2676 | } else { |
2677 | seq_printf(f, "%s ", |
2678 | (lease_breaking(fl)) |
2679 | ? (fl->fl_type == F_UNLCK) ? "UNLCK" : "READ " |
2680 | : (fl->fl_type == F_WRLCK) ? "WRITE" : "READ "); |
2681 | } |
2682 | if (inode) { |
2683 | /* userspace relies on this representation of dev_t */ |
2684 | seq_printf(f, "%d %02x:%02x:%ld ", fl_pid, |
2685 | MAJOR(inode->i_sb->s_dev), |
2686 | MINOR(inode->i_sb->s_dev), inode->i_ino); |
2687 | } else { |
2688 | seq_printf(f, "%d <none>:0 ", fl_pid); |
2689 | } |
2690 | if (IS_POSIX(fl)) { |
2691 | if (fl->fl_end == OFFSET_MAX) |
2692 | seq_printf(f, "%Ld EOF\n", fl->fl_start); |
2693 | else |
2694 | seq_printf(f, "%Ld %Ld\n", fl->fl_start, fl->fl_end); |
2695 | } else { |
2696 | seq_puts(f, "0 EOF\n"); |
2697 | } |
2698 | } |
2699 | |
2700 | static int locks_show(struct seq_file *f, void *v) |
2701 | { |
2702 | struct locks_iterator *iter = f->private; |
2703 | struct file_lock *fl, *bfl; |
2704 | struct pid_namespace *proc_pidns = file_inode(f->file)->i_sb->s_fs_info; |
2705 | |
2706 | fl = hlist_entry(v, struct file_lock, fl_link); |
2707 | |
2708 | if (fl->fl_nspid && !pid_nr_ns(fl->fl_nspid, proc_pidns)) |
2709 | return 0; |
2710 | |
2711 | lock_get_status(f, fl, iter->li_pos, ""); |
2712 | |
2713 | list_for_each_entry(bfl, &fl->fl_block, fl_block) |
2714 | lock_get_status(f, bfl, iter->li_pos, " ->"); |
2715 | |
2716 | return 0; |
2717 | } |
2718 | |
2719 | static void __show_fd_locks(struct seq_file *f, |
2720 | struct list_head *head, int *id, |
2721 | struct file *filp, struct files_struct *files) |
2722 | { |
2723 | struct file_lock *fl; |
2724 | |
2725 | list_for_each_entry(fl, head, fl_list) { |
2726 | |
2727 | if (filp != fl->fl_file) |
2728 | continue; |
2729 | if (fl->fl_owner != files && |
2730 | fl->fl_owner != filp) |
2731 | continue; |
2732 | |
2733 | (*id)++; |
2734 | seq_puts(f, "lock:\t"); |
2735 | lock_get_status(f, fl, *id, ""); |
2736 | } |
2737 | } |
2738 | |
2739 | void show_fd_locks(struct seq_file *f, |
2740 | struct file *filp, struct files_struct *files) |
2741 | { |
2742 | struct inode *inode = locks_inode(filp); |
2743 | struct file_lock_context *ctx; |
2744 | int id = 0; |
2745 | |
2746 | ctx = smp_load_acquire(&inode->i_flctx); |
2747 | if (!ctx) |
2748 | return; |
2749 | |
2750 | spin_lock(&ctx->flc_lock); |
2751 | __show_fd_locks(f, &ctx->flc_flock, &id, filp, files); |
2752 | __show_fd_locks(f, &ctx->flc_posix, &id, filp, files); |
2753 | __show_fd_locks(f, &ctx->flc_lease, &id, filp, files); |
2754 | spin_unlock(&ctx->flc_lock); |
2755 | } |
2756 | |
2757 | static void *locks_start(struct seq_file *f, loff_t *pos) |
2758 | __acquires(&blocked_lock_lock) |
2759 | { |
2760 | struct locks_iterator *iter = f->private; |
2761 | |
2762 | iter->li_pos = *pos + 1; |
2763 | percpu_down_write(&file_rwsem); |
2764 | spin_lock(&blocked_lock_lock); |
2765 | return seq_hlist_start_percpu(&file_lock_list.hlist, &iter->li_cpu, *pos); |
2766 | } |
2767 | |
2768 | static void *locks_next(struct seq_file *f, void *v, loff_t *pos) |
2769 | { |
2770 | struct locks_iterator *iter = f->private; |
2771 | |
2772 | ++iter->li_pos; |
2773 | return seq_hlist_next_percpu(v, &file_lock_list.hlist, &iter->li_cpu, pos); |
2774 | } |
2775 | |
2776 | static void locks_stop(struct seq_file *f, void *v) |
2777 | __releases(&blocked_lock_lock) |
2778 | { |
2779 | spin_unlock(&blocked_lock_lock); |
2780 | percpu_up_write(&file_rwsem); |
2781 | } |
2782 | |
2783 | static const struct seq_operations locks_seq_operations = { |
2784 | .start = locks_start, |
2785 | .next = locks_next, |
2786 | .stop = locks_stop, |
2787 | .show = locks_show, |
2788 | }; |
2789 | |
2790 | static int locks_open(struct inode *inode, struct file *filp) |
2791 | { |
2792 | return seq_open_private(filp, &locks_seq_operations, |
2793 | sizeof(struct locks_iterator)); |
2794 | } |
2795 | |
2796 | static const struct file_operations proc_locks_operations = { |
2797 | .open = locks_open, |
2798 | .read = seq_read, |
2799 | .llseek = seq_lseek, |
2800 | .release = seq_release_private, |
2801 | }; |
2802 | |
2803 | static int __init proc_locks_init(void) |
2804 | { |
2805 | proc_create("locks", 0, NULL, &proc_locks_operations); |
2806 | return 0; |
2807 | } |
2808 | fs_initcall(proc_locks_init); |
2809 | #endif |
2810 | |
2811 | static int __init filelock_init(void) |
2812 | { |
2813 | int i; |
2814 | |
2815 | flctx_cache = kmem_cache_create("file_lock_ctx", |
2816 | sizeof(struct file_lock_context), 0, SLAB_PANIC, NULL); |
2817 | |
2818 | filelock_cache = kmem_cache_create("file_lock_cache", |
2819 | sizeof(struct file_lock), 0, SLAB_PANIC, NULL); |
2820 | |
2821 | |
2822 | for_each_possible_cpu(i) { |
2823 | struct file_lock_list_struct *fll = per_cpu_ptr(&file_lock_list, i); |
2824 | |
2825 | spin_lock_init(&fll->lock); |
2826 | INIT_HLIST_HEAD(&fll->hlist); |
2827 | } |
2828 | |
2829 | return 0; |
2830 | } |
2831 | |
2832 | core_initcall(filelock_init); |
2833 |