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1 | // SPDX-License-Identifier: GPL-2.0-only | |
2 | /* | |
3 | * linux/fs/locks.c | |
4 | * | |
5 | * We implement four types of file locks: BSD locks, posix locks, open | |
6 | * file description locks, and leases. For details about BSD locks, | |
7 | * see the flock(2) man page; for details about the other three, see | |
8 | * fcntl(2). | |
9 | * | |
10 | * | |
11 | * Locking conflicts and dependencies: | |
12 | * If multiple threads attempt to lock the same byte (or flock the same file) | |
13 | * only one can be granted the lock, and other must wait their turn. | |
14 | * The first lock has been "applied" or "granted", the others are "waiting" | |
15 | * and are "blocked" by the "applied" lock.. | |
16 | * | |
17 | * Waiting and applied locks are all kept in trees whose properties are: | |
18 | * | |
19 | * - the root of a tree may be an applied or waiting lock. | |
20 | * - every other node in the tree is a waiting lock that | |
21 | * conflicts with every ancestor of that node. | |
22 | * | |
23 | * Every such tree begins life as a waiting singleton which obviously | |
24 | * satisfies the above properties. | |
25 | * | |
26 | * The only ways we modify trees preserve these properties: | |
27 | * | |
28 | * 1. We may add a new leaf node, but only after first verifying that it | |
29 | * conflicts with all of its ancestors. | |
30 | * 2. We may remove the root of a tree, creating a new singleton | |
31 | * tree from the root and N new trees rooted in the immediate | |
32 | * children. | |
33 | * 3. If the root of a tree is not currently an applied lock, we may | |
34 | * apply it (if possible). | |
35 | * 4. We may upgrade the root of the tree (either extend its range, | |
36 | * or upgrade its entire range from read to write). | |
37 | * | |
38 | * When an applied lock is modified in a way that reduces or downgrades any | |
39 | * part of its range, we remove all its children (2 above). This particularly | |
40 | * happens when a lock is unlocked. | |
41 | * | |
42 | * For each of those child trees we "wake up" the thread which is | |
43 | * waiting for the lock so it can continue handling as follows: if the | |
44 | * root of the tree applies, we do so (3). If it doesn't, it must | |
45 | * conflict with some applied lock. We remove (wake up) all of its children | |
46 | * (2), and add it is a new leaf to the tree rooted in the applied | |
47 | * lock (1). We then repeat the process recursively with those | |
48 | * children. | |
49 | * | |
50 | */ | |
51 | #include <linux/capability.h> | |
52 | #include <linux/file.h> | |
53 | #include <linux/fdtable.h> | |
54 | #include <linux/filelock.h> | |
55 | #include <linux/fs.h> | |
56 | #include <linux/init.h> | |
57 | #include <linux/security.h> | |
58 | #include <linux/slab.h> | |
59 | #include <linux/syscalls.h> | |
60 | #include <linux/time.h> | |
61 | #include <linux/rcupdate.h> | |
62 | #include <linux/pid_namespace.h> | |
63 | #include <linux/hashtable.h> | |
64 | #include <linux/percpu.h> | |
65 | #include <linux/sysctl.h> | |
66 | ||
67 | #define CREATE_TRACE_POINTS | |
68 | #include <trace/events/filelock.h> | |
69 | ||
70 | #include <linux/uaccess.h> | |
71 | ||
72 | static struct file_lock *file_lock(struct file_lock_core *flc) | |
73 | { | |
74 | return container_of(flc, struct file_lock, c); | |
75 | } | |
76 | ||
77 | static struct file_lease *file_lease(struct file_lock_core *flc) | |
78 | { | |
79 | return container_of(flc, struct file_lease, c); | |
80 | } | |
81 | ||
82 | static bool lease_breaking(struct file_lease *fl) | |
83 | { | |
84 | return fl->c.flc_flags & (FL_UNLOCK_PENDING | FL_DOWNGRADE_PENDING); | |
85 | } | |
86 | ||
87 | static int target_leasetype(struct file_lease *fl) | |
88 | { | |
89 | if (fl->c.flc_flags & FL_UNLOCK_PENDING) | |
90 | return F_UNLCK; | |
91 | if (fl->c.flc_flags & FL_DOWNGRADE_PENDING) | |
92 | return F_RDLCK; | |
93 | return fl->c.flc_type; | |
94 | } | |
95 | ||
96 | static int leases_enable = 1; | |
97 | static int lease_break_time = 45; | |
98 | ||
99 | #ifdef CONFIG_SYSCTL | |
100 | static struct ctl_table locks_sysctls[] = { | |
101 | { | |
102 | .procname = "leases-enable", | |
103 | .data = &leases_enable, | |
104 | .maxlen = sizeof(int), | |
105 | .mode = 0644, | |
106 | .proc_handler = proc_dointvec, | |
107 | }, | |
108 | #ifdef CONFIG_MMU | |
109 | { | |
110 | .procname = "lease-break-time", | |
111 | .data = &lease_break_time, | |
112 | .maxlen = sizeof(int), | |
113 | .mode = 0644, | |
114 | .proc_handler = proc_dointvec, | |
115 | }, | |
116 | #endif /* CONFIG_MMU */ | |
117 | }; | |
118 | ||
119 | static int __init init_fs_locks_sysctls(void) | |
120 | { | |
121 | register_sysctl_init("fs", locks_sysctls); | |
122 | return 0; | |
123 | } | |
124 | early_initcall(init_fs_locks_sysctls); | |
125 | #endif /* CONFIG_SYSCTL */ | |
126 | ||
127 | /* | |
128 | * The global file_lock_list is only used for displaying /proc/locks, so we | |
129 | * keep a list on each CPU, with each list protected by its own spinlock. | |
130 | * Global serialization is done using file_rwsem. | |
131 | * | |
132 | * Note that alterations to the list also require that the relevant flc_lock is | |
133 | * held. | |
134 | */ | |
135 | struct file_lock_list_struct { | |
136 | spinlock_t lock; | |
137 | struct hlist_head hlist; | |
138 | }; | |
139 | static DEFINE_PER_CPU(struct file_lock_list_struct, file_lock_list); | |
140 | DEFINE_STATIC_PERCPU_RWSEM(file_rwsem); | |
141 | ||
142 | ||
143 | /* | |
144 | * The blocked_hash is used to find POSIX lock loops for deadlock detection. | |
145 | * It is protected by blocked_lock_lock. | |
146 | * | |
147 | * We hash locks by lockowner in order to optimize searching for the lock a | |
148 | * particular lockowner is waiting on. | |
149 | * | |
150 | * FIXME: make this value scale via some heuristic? We generally will want more | |
151 | * buckets when we have more lockowners holding locks, but that's a little | |
152 | * difficult to determine without knowing what the workload will look like. | |
153 | */ | |
154 | #define BLOCKED_HASH_BITS 7 | |
155 | static DEFINE_HASHTABLE(blocked_hash, BLOCKED_HASH_BITS); | |
156 | ||
157 | /* | |
158 | * This lock protects the blocked_hash. Generally, if you're accessing it, you | |
159 | * want to be holding this lock. | |
160 | * | |
161 | * In addition, it also protects the fl->fl_blocked_requests list, and the | |
162 | * fl->fl_blocker pointer for file_lock structures that are acting as lock | |
163 | * requests (in contrast to those that are acting as records of acquired locks). | |
164 | * | |
165 | * Note that when we acquire this lock in order to change the above fields, | |
166 | * we often hold the flc_lock as well. In certain cases, when reading the fields | |
167 | * protected by this lock, we can skip acquiring it iff we already hold the | |
168 | * flc_lock. | |
169 | */ | |
170 | static DEFINE_SPINLOCK(blocked_lock_lock); | |
171 | ||
172 | static struct kmem_cache *flctx_cache __ro_after_init; | |
173 | static struct kmem_cache *filelock_cache __ro_after_init; | |
174 | static struct kmem_cache *filelease_cache __ro_after_init; | |
175 | ||
176 | static struct file_lock_context * | |
177 | locks_get_lock_context(struct inode *inode, int type) | |
178 | { | |
179 | struct file_lock_context *ctx; | |
180 | ||
181 | /* paired with cmpxchg() below */ | |
182 | ctx = locks_inode_context(inode); | |
183 | if (likely(ctx) || type == F_UNLCK) | |
184 | goto out; | |
185 | ||
186 | ctx = kmem_cache_alloc(flctx_cache, GFP_KERNEL); | |
187 | if (!ctx) | |
188 | goto out; | |
189 | ||
190 | spin_lock_init(&ctx->flc_lock); | |
191 | INIT_LIST_HEAD(&ctx->flc_flock); | |
192 | INIT_LIST_HEAD(&ctx->flc_posix); | |
193 | INIT_LIST_HEAD(&ctx->flc_lease); | |
194 | ||
195 | /* | |
196 | * Assign the pointer if it's not already assigned. If it is, then | |
197 | * free the context we just allocated. | |
198 | */ | |
199 | if (cmpxchg(&inode->i_flctx, NULL, ctx)) { | |
200 | kmem_cache_free(flctx_cache, ctx); | |
201 | ctx = locks_inode_context(inode); | |
202 | } | |
203 | out: | |
204 | trace_locks_get_lock_context(inode, type, ctx); | |
205 | return ctx; | |
206 | } | |
207 | ||
208 | static void | |
209 | locks_dump_ctx_list(struct list_head *list, char *list_type) | |
210 | { | |
211 | struct file_lock_core *flc; | |
212 | ||
213 | list_for_each_entry(flc, list, flc_list) | |
214 | pr_warn("%s: fl_owner=%p fl_flags=0x%x fl_type=0x%x fl_pid=%u\n", | |
215 | list_type, flc->flc_owner, flc->flc_flags, | |
216 | flc->flc_type, flc->flc_pid); | |
217 | } | |
218 | ||
219 | static void | |
220 | locks_check_ctx_lists(struct inode *inode) | |
221 | { | |
222 | struct file_lock_context *ctx = inode->i_flctx; | |
223 | ||
224 | if (unlikely(!list_empty(&ctx->flc_flock) || | |
225 | !list_empty(&ctx->flc_posix) || | |
226 | !list_empty(&ctx->flc_lease))) { | |
227 | pr_warn("Leaked locks on dev=0x%x:0x%x ino=0x%lx:\n", | |
228 | MAJOR(inode->i_sb->s_dev), MINOR(inode->i_sb->s_dev), | |
229 | inode->i_ino); | |
230 | locks_dump_ctx_list(&ctx->flc_flock, "FLOCK"); | |
231 | locks_dump_ctx_list(&ctx->flc_posix, "POSIX"); | |
232 | locks_dump_ctx_list(&ctx->flc_lease, "LEASE"); | |
233 | } | |
234 | } | |
235 | ||
236 | static void | |
237 | locks_check_ctx_file_list(struct file *filp, struct list_head *list, char *list_type) | |
238 | { | |
239 | struct file_lock_core *flc; | |
240 | struct inode *inode = file_inode(filp); | |
241 | ||
242 | list_for_each_entry(flc, list, flc_list) | |
243 | if (flc->flc_file == filp) | |
244 | pr_warn("Leaked %s lock on dev=0x%x:0x%x ino=0x%lx " | |
245 | " fl_owner=%p fl_flags=0x%x fl_type=0x%x fl_pid=%u\n", | |
246 | list_type, MAJOR(inode->i_sb->s_dev), | |
247 | MINOR(inode->i_sb->s_dev), inode->i_ino, | |
248 | flc->flc_owner, flc->flc_flags, | |
249 | flc->flc_type, flc->flc_pid); | |
250 | } | |
251 | ||
252 | void | |
253 | locks_free_lock_context(struct inode *inode) | |
254 | { | |
255 | struct file_lock_context *ctx = locks_inode_context(inode); | |
256 | ||
257 | if (unlikely(ctx)) { | |
258 | locks_check_ctx_lists(inode); | |
259 | kmem_cache_free(flctx_cache, ctx); | |
260 | } | |
261 | } | |
262 | ||
263 | static void locks_init_lock_heads(struct file_lock_core *flc) | |
264 | { | |
265 | INIT_HLIST_NODE(&flc->flc_link); | |
266 | INIT_LIST_HEAD(&flc->flc_list); | |
267 | INIT_LIST_HEAD(&flc->flc_blocked_requests); | |
268 | INIT_LIST_HEAD(&flc->flc_blocked_member); | |
269 | init_waitqueue_head(&flc->flc_wait); | |
270 | } | |
271 | ||
272 | /* Allocate an empty lock structure. */ | |
273 | struct file_lock *locks_alloc_lock(void) | |
274 | { | |
275 | struct file_lock *fl = kmem_cache_zalloc(filelock_cache, GFP_KERNEL); | |
276 | ||
277 | if (fl) | |
278 | locks_init_lock_heads(&fl->c); | |
279 | ||
280 | return fl; | |
281 | } | |
282 | EXPORT_SYMBOL_GPL(locks_alloc_lock); | |
283 | ||
284 | /* Allocate an empty lock structure. */ | |
285 | struct file_lease *locks_alloc_lease(void) | |
286 | { | |
287 | struct file_lease *fl = kmem_cache_zalloc(filelease_cache, GFP_KERNEL); | |
288 | ||
289 | if (fl) | |
290 | locks_init_lock_heads(&fl->c); | |
291 | ||
292 | return fl; | |
293 | } | |
294 | EXPORT_SYMBOL_GPL(locks_alloc_lease); | |
295 | ||
296 | void locks_release_private(struct file_lock *fl) | |
297 | { | |
298 | struct file_lock_core *flc = &fl->c; | |
299 | ||
300 | BUG_ON(waitqueue_active(&flc->flc_wait)); | |
301 | BUG_ON(!list_empty(&flc->flc_list)); | |
302 | BUG_ON(!list_empty(&flc->flc_blocked_requests)); | |
303 | BUG_ON(!list_empty(&flc->flc_blocked_member)); | |
304 | BUG_ON(!hlist_unhashed(&flc->flc_link)); | |
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(flc->flc_owner); | |
315 | flc->flc_owner = NULL; | |
316 | } | |
317 | fl->fl_lmops = NULL; | |
318 | } | |
319 | } | |
320 | EXPORT_SYMBOL_GPL(locks_release_private); | |
321 | ||
322 | /** | |
323 | * locks_owner_has_blockers - Check for blocking lock requests | |
324 | * @flctx: file lock context | |
325 | * @owner: lock owner | |
326 | * | |
327 | * Return values: | |
328 | * %true: @owner has at least one blocker | |
329 | * %false: @owner has no blockers | |
330 | */ | |
331 | bool locks_owner_has_blockers(struct file_lock_context *flctx, fl_owner_t owner) | |
332 | { | |
333 | struct file_lock_core *flc; | |
334 | ||
335 | spin_lock(&flctx->flc_lock); | |
336 | list_for_each_entry(flc, &flctx->flc_posix, flc_list) { | |
337 | if (flc->flc_owner != owner) | |
338 | continue; | |
339 | if (!list_empty(&flc->flc_blocked_requests)) { | |
340 | spin_unlock(&flctx->flc_lock); | |
341 | return true; | |
342 | } | |
343 | } | |
344 | spin_unlock(&flctx->flc_lock); | |
345 | return false; | |
346 | } | |
347 | EXPORT_SYMBOL_GPL(locks_owner_has_blockers); | |
348 | ||
349 | /* Free a lock which is not in use. */ | |
350 | void locks_free_lock(struct file_lock *fl) | |
351 | { | |
352 | locks_release_private(fl); | |
353 | kmem_cache_free(filelock_cache, fl); | |
354 | } | |
355 | EXPORT_SYMBOL(locks_free_lock); | |
356 | ||
357 | /* Free a lease which is not in use. */ | |
358 | void locks_free_lease(struct file_lease *fl) | |
359 | { | |
360 | kmem_cache_free(filelease_cache, fl); | |
361 | } | |
362 | EXPORT_SYMBOL(locks_free_lease); | |
363 | ||
364 | static void | |
365 | locks_dispose_list(struct list_head *dispose) | |
366 | { | |
367 | struct file_lock_core *flc; | |
368 | ||
369 | while (!list_empty(dispose)) { | |
370 | flc = list_first_entry(dispose, struct file_lock_core, flc_list); | |
371 | list_del_init(&flc->flc_list); | |
372 | if (flc->flc_flags & (FL_LEASE|FL_DELEG|FL_LAYOUT)) | |
373 | locks_free_lease(file_lease(flc)); | |
374 | else | |
375 | locks_free_lock(file_lock(flc)); | |
376 | } | |
377 | } | |
378 | ||
379 | void locks_init_lock(struct file_lock *fl) | |
380 | { | |
381 | memset(fl, 0, sizeof(struct file_lock)); | |
382 | locks_init_lock_heads(&fl->c); | |
383 | } | |
384 | EXPORT_SYMBOL(locks_init_lock); | |
385 | ||
386 | void locks_init_lease(struct file_lease *fl) | |
387 | { | |
388 | memset(fl, 0, sizeof(*fl)); | |
389 | locks_init_lock_heads(&fl->c); | |
390 | } | |
391 | EXPORT_SYMBOL(locks_init_lease); | |
392 | ||
393 | /* | |
394 | * Initialize a new lock from an existing file_lock structure. | |
395 | */ | |
396 | void locks_copy_conflock(struct file_lock *new, struct file_lock *fl) | |
397 | { | |
398 | new->c.flc_owner = fl->c.flc_owner; | |
399 | new->c.flc_pid = fl->c.flc_pid; | |
400 | new->c.flc_file = NULL; | |
401 | new->c.flc_flags = fl->c.flc_flags; | |
402 | new->c.flc_type = fl->c.flc_type; | |
403 | new->fl_start = fl->fl_start; | |
404 | new->fl_end = fl->fl_end; | |
405 | new->fl_lmops = fl->fl_lmops; | |
406 | new->fl_ops = NULL; | |
407 | ||
408 | if (fl->fl_lmops) { | |
409 | if (fl->fl_lmops->lm_get_owner) | |
410 | fl->fl_lmops->lm_get_owner(fl->c.flc_owner); | |
411 | } | |
412 | } | |
413 | EXPORT_SYMBOL(locks_copy_conflock); | |
414 | ||
415 | void locks_copy_lock(struct file_lock *new, struct file_lock *fl) | |
416 | { | |
417 | /* "new" must be a freshly-initialized lock */ | |
418 | WARN_ON_ONCE(new->fl_ops); | |
419 | ||
420 | locks_copy_conflock(new, fl); | |
421 | ||
422 | new->c.flc_file = fl->c.flc_file; | |
423 | new->fl_ops = fl->fl_ops; | |
424 | ||
425 | if (fl->fl_ops) { | |
426 | if (fl->fl_ops->fl_copy_lock) | |
427 | fl->fl_ops->fl_copy_lock(new, fl); | |
428 | } | |
429 | } | |
430 | EXPORT_SYMBOL(locks_copy_lock); | |
431 | ||
432 | static void locks_move_blocks(struct file_lock *new, struct file_lock *fl) | |
433 | { | |
434 | struct file_lock *f; | |
435 | ||
436 | /* | |
437 | * As ctx->flc_lock is held, new requests cannot be added to | |
438 | * ->flc_blocked_requests, so we don't need a lock to check if it | |
439 | * is empty. | |
440 | */ | |
441 | if (list_empty(&fl->c.flc_blocked_requests)) | |
442 | return; | |
443 | spin_lock(&blocked_lock_lock); | |
444 | list_splice_init(&fl->c.flc_blocked_requests, | |
445 | &new->c.flc_blocked_requests); | |
446 | list_for_each_entry(f, &new->c.flc_blocked_requests, | |
447 | c.flc_blocked_member) | |
448 | f->c.flc_blocker = &new->c; | |
449 | spin_unlock(&blocked_lock_lock); | |
450 | } | |
451 | ||
452 | static inline int flock_translate_cmd(int cmd) { | |
453 | switch (cmd) { | |
454 | case LOCK_SH: | |
455 | return F_RDLCK; | |
456 | case LOCK_EX: | |
457 | return F_WRLCK; | |
458 | case LOCK_UN: | |
459 | return F_UNLCK; | |
460 | } | |
461 | return -EINVAL; | |
462 | } | |
463 | ||
464 | /* Fill in a file_lock structure with an appropriate FLOCK lock. */ | |
465 | static void flock_make_lock(struct file *filp, struct file_lock *fl, int type) | |
466 | { | |
467 | locks_init_lock(fl); | |
468 | ||
469 | fl->c.flc_file = filp; | |
470 | fl->c.flc_owner = filp; | |
471 | fl->c.flc_pid = current->tgid; | |
472 | fl->c.flc_flags = FL_FLOCK; | |
473 | fl->c.flc_type = type; | |
474 | fl->fl_end = OFFSET_MAX; | |
475 | } | |
476 | ||
477 | static int assign_type(struct file_lock_core *flc, int type) | |
478 | { | |
479 | switch (type) { | |
480 | case F_RDLCK: | |
481 | case F_WRLCK: | |
482 | case F_UNLCK: | |
483 | flc->flc_type = type; | |
484 | break; | |
485 | default: | |
486 | return -EINVAL; | |
487 | } | |
488 | return 0; | |
489 | } | |
490 | ||
491 | static int flock64_to_posix_lock(struct file *filp, struct file_lock *fl, | |
492 | struct flock64 *l) | |
493 | { | |
494 | switch (l->l_whence) { | |
495 | case SEEK_SET: | |
496 | fl->fl_start = 0; | |
497 | break; | |
498 | case SEEK_CUR: | |
499 | fl->fl_start = filp->f_pos; | |
500 | break; | |
501 | case SEEK_END: | |
502 | fl->fl_start = i_size_read(file_inode(filp)); | |
503 | break; | |
504 | default: | |
505 | return -EINVAL; | |
506 | } | |
507 | if (l->l_start > OFFSET_MAX - fl->fl_start) | |
508 | return -EOVERFLOW; | |
509 | fl->fl_start += l->l_start; | |
510 | if (fl->fl_start < 0) | |
511 | return -EINVAL; | |
512 | ||
513 | /* POSIX-1996 leaves the case l->l_len < 0 undefined; | |
514 | POSIX-2001 defines it. */ | |
515 | if (l->l_len > 0) { | |
516 | if (l->l_len - 1 > OFFSET_MAX - fl->fl_start) | |
517 | return -EOVERFLOW; | |
518 | fl->fl_end = fl->fl_start + (l->l_len - 1); | |
519 | ||
520 | } else if (l->l_len < 0) { | |
521 | if (fl->fl_start + l->l_len < 0) | |
522 | return -EINVAL; | |
523 | fl->fl_end = fl->fl_start - 1; | |
524 | fl->fl_start += l->l_len; | |
525 | } else | |
526 | fl->fl_end = OFFSET_MAX; | |
527 | ||
528 | fl->c.flc_owner = current->files; | |
529 | fl->c.flc_pid = current->tgid; | |
530 | fl->c.flc_file = filp; | |
531 | fl->c.flc_flags = FL_POSIX; | |
532 | fl->fl_ops = NULL; | |
533 | fl->fl_lmops = NULL; | |
534 | ||
535 | return assign_type(&fl->c, l->l_type); | |
536 | } | |
537 | ||
538 | /* Verify a "struct flock" and copy it to a "struct file_lock" as a POSIX | |
539 | * style lock. | |
540 | */ | |
541 | static int flock_to_posix_lock(struct file *filp, struct file_lock *fl, | |
542 | struct flock *l) | |
543 | { | |
544 | struct flock64 ll = { | |
545 | .l_type = l->l_type, | |
546 | .l_whence = l->l_whence, | |
547 | .l_start = l->l_start, | |
548 | .l_len = l->l_len, | |
549 | }; | |
550 | ||
551 | return flock64_to_posix_lock(filp, fl, &ll); | |
552 | } | |
553 | ||
554 | /* default lease lock manager operations */ | |
555 | static bool | |
556 | lease_break_callback(struct file_lease *fl) | |
557 | { | |
558 | kill_fasync(&fl->fl_fasync, SIGIO, POLL_MSG); | |
559 | return false; | |
560 | } | |
561 | ||
562 | static void | |
563 | lease_setup(struct file_lease *fl, void **priv) | |
564 | { | |
565 | struct file *filp = fl->c.flc_file; | |
566 | struct fasync_struct *fa = *priv; | |
567 | ||
568 | /* | |
569 | * fasync_insert_entry() returns the old entry if any. If there was no | |
570 | * old entry, then it used "priv" and inserted it into the fasync list. | |
571 | * Clear the pointer to indicate that it shouldn't be freed. | |
572 | */ | |
573 | if (!fasync_insert_entry(fa->fa_fd, filp, &fl->fl_fasync, fa)) | |
574 | *priv = NULL; | |
575 | ||
576 | __f_setown(filp, task_pid(current), PIDTYPE_TGID, 0); | |
577 | } | |
578 | ||
579 | static const struct lease_manager_operations lease_manager_ops = { | |
580 | .lm_break = lease_break_callback, | |
581 | .lm_change = lease_modify, | |
582 | .lm_setup = lease_setup, | |
583 | }; | |
584 | ||
585 | /* | |
586 | * Initialize a lease, use the default lock manager operations | |
587 | */ | |
588 | static int lease_init(struct file *filp, int type, struct file_lease *fl) | |
589 | { | |
590 | if (assign_type(&fl->c, type) != 0) | |
591 | return -EINVAL; | |
592 | ||
593 | fl->c.flc_owner = filp; | |
594 | fl->c.flc_pid = current->tgid; | |
595 | ||
596 | fl->c.flc_file = filp; | |
597 | fl->c.flc_flags = FL_LEASE; | |
598 | fl->fl_lmops = &lease_manager_ops; | |
599 | return 0; | |
600 | } | |
601 | ||
602 | /* Allocate a file_lock initialised to this type of lease */ | |
603 | static struct file_lease *lease_alloc(struct file *filp, int type) | |
604 | { | |
605 | struct file_lease *fl = locks_alloc_lease(); | |
606 | int error = -ENOMEM; | |
607 | ||
608 | if (fl == NULL) | |
609 | return ERR_PTR(error); | |
610 | ||
611 | error = lease_init(filp, type, fl); | |
612 | if (error) { | |
613 | locks_free_lease(fl); | |
614 | return ERR_PTR(error); | |
615 | } | |
616 | return fl; | |
617 | } | |
618 | ||
619 | /* Check if two locks overlap each other. | |
620 | */ | |
621 | static inline int locks_overlap(struct file_lock *fl1, struct file_lock *fl2) | |
622 | { | |
623 | return ((fl1->fl_end >= fl2->fl_start) && | |
624 | (fl2->fl_end >= fl1->fl_start)); | |
625 | } | |
626 | ||
627 | /* | |
628 | * Check whether two locks have the same owner. | |
629 | */ | |
630 | static int posix_same_owner(struct file_lock_core *fl1, struct file_lock_core *fl2) | |
631 | { | |
632 | return fl1->flc_owner == fl2->flc_owner; | |
633 | } | |
634 | ||
635 | /* Must be called with the flc_lock held! */ | |
636 | static void locks_insert_global_locks(struct file_lock_core *flc) | |
637 | { | |
638 | struct file_lock_list_struct *fll = this_cpu_ptr(&file_lock_list); | |
639 | ||
640 | percpu_rwsem_assert_held(&file_rwsem); | |
641 | ||
642 | spin_lock(&fll->lock); | |
643 | flc->flc_link_cpu = smp_processor_id(); | |
644 | hlist_add_head(&flc->flc_link, &fll->hlist); | |
645 | spin_unlock(&fll->lock); | |
646 | } | |
647 | ||
648 | /* Must be called with the flc_lock held! */ | |
649 | static void locks_delete_global_locks(struct file_lock_core *flc) | |
650 | { | |
651 | struct file_lock_list_struct *fll; | |
652 | ||
653 | percpu_rwsem_assert_held(&file_rwsem); | |
654 | ||
655 | /* | |
656 | * Avoid taking lock if already unhashed. This is safe since this check | |
657 | * is done while holding the flc_lock, and new insertions into the list | |
658 | * also require that it be held. | |
659 | */ | |
660 | if (hlist_unhashed(&flc->flc_link)) | |
661 | return; | |
662 | ||
663 | fll = per_cpu_ptr(&file_lock_list, flc->flc_link_cpu); | |
664 | spin_lock(&fll->lock); | |
665 | hlist_del_init(&flc->flc_link); | |
666 | spin_unlock(&fll->lock); | |
667 | } | |
668 | ||
669 | static unsigned long | |
670 | posix_owner_key(struct file_lock_core *flc) | |
671 | { | |
672 | return (unsigned long) flc->flc_owner; | |
673 | } | |
674 | ||
675 | static void locks_insert_global_blocked(struct file_lock_core *waiter) | |
676 | { | |
677 | lockdep_assert_held(&blocked_lock_lock); | |
678 | ||
679 | hash_add(blocked_hash, &waiter->flc_link, posix_owner_key(waiter)); | |
680 | } | |
681 | ||
682 | static void locks_delete_global_blocked(struct file_lock_core *waiter) | |
683 | { | |
684 | lockdep_assert_held(&blocked_lock_lock); | |
685 | ||
686 | hash_del(&waiter->flc_link); | |
687 | } | |
688 | ||
689 | /* Remove waiter from blocker's block list. | |
690 | * When blocker ends up pointing to itself then the list is empty. | |
691 | * | |
692 | * Must be called with blocked_lock_lock held. | |
693 | */ | |
694 | static void __locks_unlink_block(struct file_lock_core *waiter) | |
695 | { | |
696 | locks_delete_global_blocked(waiter); | |
697 | list_del_init(&waiter->flc_blocked_member); | |
698 | } | |
699 | ||
700 | static void __locks_wake_up_blocks(struct file_lock_core *blocker) | |
701 | { | |
702 | while (!list_empty(&blocker->flc_blocked_requests)) { | |
703 | struct file_lock_core *waiter; | |
704 | struct file_lock *fl; | |
705 | ||
706 | waiter = list_first_entry(&blocker->flc_blocked_requests, | |
707 | struct file_lock_core, flc_blocked_member); | |
708 | ||
709 | fl = file_lock(waiter); | |
710 | __locks_unlink_block(waiter); | |
711 | if ((waiter->flc_flags & (FL_POSIX | FL_FLOCK)) && | |
712 | fl->fl_lmops && fl->fl_lmops->lm_notify) | |
713 | fl->fl_lmops->lm_notify(fl); | |
714 | else | |
715 | locks_wake_up(fl); | |
716 | ||
717 | /* | |
718 | * The setting of flc_blocker to NULL marks the "done" | |
719 | * point in deleting a block. Paired with acquire at the top | |
720 | * of locks_delete_block(). | |
721 | */ | |
722 | smp_store_release(&waiter->flc_blocker, NULL); | |
723 | } | |
724 | } | |
725 | ||
726 | static int __locks_delete_block(struct file_lock_core *waiter) | |
727 | { | |
728 | int status = -ENOENT; | |
729 | ||
730 | /* | |
731 | * If fl_blocker is NULL, it won't be set again as this thread "owns" | |
732 | * the lock and is the only one that might try to claim the lock. | |
733 | * | |
734 | * We use acquire/release to manage fl_blocker so that we can | |
735 | * optimize away taking the blocked_lock_lock in many cases. | |
736 | * | |
737 | * The smp_load_acquire guarantees two things: | |
738 | * | |
739 | * 1/ that fl_blocked_requests can be tested locklessly. If something | |
740 | * was recently added to that list it must have been in a locked region | |
741 | * *before* the locked region when fl_blocker was set to NULL. | |
742 | * | |
743 | * 2/ that no other thread is accessing 'waiter', so it is safe to free | |
744 | * it. __locks_wake_up_blocks is careful not to touch waiter after | |
745 | * fl_blocker is released. | |
746 | * | |
747 | * If a lockless check of fl_blocker shows it to be NULL, we know that | |
748 | * no new locks can be inserted into its fl_blocked_requests list, and | |
749 | * can avoid doing anything further if the list is empty. | |
750 | */ | |
751 | if (!smp_load_acquire(&waiter->flc_blocker) && | |
752 | list_empty(&waiter->flc_blocked_requests)) | |
753 | return status; | |
754 | ||
755 | spin_lock(&blocked_lock_lock); | |
756 | if (waiter->flc_blocker) | |
757 | status = 0; | |
758 | __locks_wake_up_blocks(waiter); | |
759 | __locks_unlink_block(waiter); | |
760 | ||
761 | /* | |
762 | * The setting of fl_blocker to NULL marks the "done" point in deleting | |
763 | * a block. Paired with acquire at the top of this function. | |
764 | */ | |
765 | smp_store_release(&waiter->flc_blocker, NULL); | |
766 | spin_unlock(&blocked_lock_lock); | |
767 | return status; | |
768 | } | |
769 | ||
770 | /** | |
771 | * locks_delete_block - stop waiting for a file lock | |
772 | * @waiter: the lock which was waiting | |
773 | * | |
774 | * lockd/nfsd need to disconnect the lock while working on it. | |
775 | */ | |
776 | int locks_delete_block(struct file_lock *waiter) | |
777 | { | |
778 | return __locks_delete_block(&waiter->c); | |
779 | } | |
780 | EXPORT_SYMBOL(locks_delete_block); | |
781 | ||
782 | /* Insert waiter into blocker's block list. | |
783 | * We use a circular list so that processes can be easily woken up in | |
784 | * the order they blocked. The documentation doesn't require this but | |
785 | * it seems like the reasonable thing to do. | |
786 | * | |
787 | * Must be called with both the flc_lock and blocked_lock_lock held. The | |
788 | * fl_blocked_requests list itself is protected by the blocked_lock_lock, | |
789 | * but by ensuring that the flc_lock is also held on insertions we can avoid | |
790 | * taking the blocked_lock_lock in some cases when we see that the | |
791 | * fl_blocked_requests list is empty. | |
792 | * | |
793 | * Rather than just adding to the list, we check for conflicts with any existing | |
794 | * waiters, and add beneath any waiter that blocks the new waiter. | |
795 | * Thus wakeups don't happen until needed. | |
796 | */ | |
797 | static void __locks_insert_block(struct file_lock_core *blocker, | |
798 | struct file_lock_core *waiter, | |
799 | bool conflict(struct file_lock_core *, | |
800 | struct file_lock_core *)) | |
801 | { | |
802 | struct file_lock_core *flc; | |
803 | ||
804 | BUG_ON(!list_empty(&waiter->flc_blocked_member)); | |
805 | new_blocker: | |
806 | list_for_each_entry(flc, &blocker->flc_blocked_requests, flc_blocked_member) | |
807 | if (conflict(flc, waiter)) { | |
808 | blocker = flc; | |
809 | goto new_blocker; | |
810 | } | |
811 | waiter->flc_blocker = blocker; | |
812 | list_add_tail(&waiter->flc_blocked_member, | |
813 | &blocker->flc_blocked_requests); | |
814 | ||
815 | if ((blocker->flc_flags & (FL_POSIX|FL_OFDLCK)) == FL_POSIX) | |
816 | locks_insert_global_blocked(waiter); | |
817 | ||
818 | /* The requests in waiter->flc_blocked are known to conflict with | |
819 | * waiter, but might not conflict with blocker, or the requests | |
820 | * and lock which block it. So they all need to be woken. | |
821 | */ | |
822 | __locks_wake_up_blocks(waiter); | |
823 | } | |
824 | ||
825 | /* Must be called with flc_lock held. */ | |
826 | static void locks_insert_block(struct file_lock_core *blocker, | |
827 | struct file_lock_core *waiter, | |
828 | bool conflict(struct file_lock_core *, | |
829 | struct file_lock_core *)) | |
830 | { | |
831 | spin_lock(&blocked_lock_lock); | |
832 | __locks_insert_block(blocker, waiter, conflict); | |
833 | spin_unlock(&blocked_lock_lock); | |
834 | } | |
835 | ||
836 | /* | |
837 | * Wake up processes blocked waiting for blocker. | |
838 | * | |
839 | * Must be called with the inode->flc_lock held! | |
840 | */ | |
841 | static void locks_wake_up_blocks(struct file_lock_core *blocker) | |
842 | { | |
843 | /* | |
844 | * Avoid taking global lock if list is empty. This is safe since new | |
845 | * blocked requests are only added to the list under the flc_lock, and | |
846 | * the flc_lock is always held here. Note that removal from the | |
847 | * fl_blocked_requests list does not require the flc_lock, so we must | |
848 | * recheck list_empty() after acquiring the blocked_lock_lock. | |
849 | */ | |
850 | if (list_empty(&blocker->flc_blocked_requests)) | |
851 | return; | |
852 | ||
853 | spin_lock(&blocked_lock_lock); | |
854 | __locks_wake_up_blocks(blocker); | |
855 | spin_unlock(&blocked_lock_lock); | |
856 | } | |
857 | ||
858 | static void | |
859 | locks_insert_lock_ctx(struct file_lock_core *fl, struct list_head *before) | |
860 | { | |
861 | list_add_tail(&fl->flc_list, before); | |
862 | locks_insert_global_locks(fl); | |
863 | } | |
864 | ||
865 | static void | |
866 | locks_unlink_lock_ctx(struct file_lock_core *fl) | |
867 | { | |
868 | locks_delete_global_locks(fl); | |
869 | list_del_init(&fl->flc_list); | |
870 | locks_wake_up_blocks(fl); | |
871 | } | |
872 | ||
873 | static void | |
874 | locks_delete_lock_ctx(struct file_lock_core *fl, struct list_head *dispose) | |
875 | { | |
876 | locks_unlink_lock_ctx(fl); | |
877 | if (dispose) | |
878 | list_add(&fl->flc_list, dispose); | |
879 | else | |
880 | locks_free_lock(file_lock(fl)); | |
881 | } | |
882 | ||
883 | /* Determine if lock sys_fl blocks lock caller_fl. Common functionality | |
884 | * checks for shared/exclusive status of overlapping locks. | |
885 | */ | |
886 | static bool locks_conflict(struct file_lock_core *caller_flc, | |
887 | struct file_lock_core *sys_flc) | |
888 | { | |
889 | if (sys_flc->flc_type == F_WRLCK) | |
890 | return true; | |
891 | if (caller_flc->flc_type == F_WRLCK) | |
892 | return true; | |
893 | return false; | |
894 | } | |
895 | ||
896 | /* Determine if lock sys_fl blocks lock caller_fl. POSIX specific | |
897 | * checking before calling the locks_conflict(). | |
898 | */ | |
899 | static bool posix_locks_conflict(struct file_lock_core *caller_flc, | |
900 | struct file_lock_core *sys_flc) | |
901 | { | |
902 | struct file_lock *caller_fl = file_lock(caller_flc); | |
903 | struct file_lock *sys_fl = file_lock(sys_flc); | |
904 | ||
905 | /* POSIX locks owned by the same process do not conflict with | |
906 | * each other. | |
907 | */ | |
908 | if (posix_same_owner(caller_flc, sys_flc)) | |
909 | return false; | |
910 | ||
911 | /* Check whether they overlap */ | |
912 | if (!locks_overlap(caller_fl, sys_fl)) | |
913 | return false; | |
914 | ||
915 | return locks_conflict(caller_flc, sys_flc); | |
916 | } | |
917 | ||
918 | /* Determine if lock sys_fl blocks lock caller_fl. Used on xx_GETLK | |
919 | * path so checks for additional GETLK-specific things like F_UNLCK. | |
920 | */ | |
921 | static bool posix_test_locks_conflict(struct file_lock *caller_fl, | |
922 | struct file_lock *sys_fl) | |
923 | { | |
924 | struct file_lock_core *caller = &caller_fl->c; | |
925 | struct file_lock_core *sys = &sys_fl->c; | |
926 | ||
927 | /* F_UNLCK checks any locks on the same fd. */ | |
928 | if (lock_is_unlock(caller_fl)) { | |
929 | if (!posix_same_owner(caller, sys)) | |
930 | return false; | |
931 | return locks_overlap(caller_fl, sys_fl); | |
932 | } | |
933 | return posix_locks_conflict(caller, sys); | |
934 | } | |
935 | ||
936 | /* Determine if lock sys_fl blocks lock caller_fl. FLOCK specific | |
937 | * checking before calling the locks_conflict(). | |
938 | */ | |
939 | static bool flock_locks_conflict(struct file_lock_core *caller_flc, | |
940 | struct file_lock_core *sys_flc) | |
941 | { | |
942 | /* FLOCK locks referring to the same filp do not conflict with | |
943 | * each other. | |
944 | */ | |
945 | if (caller_flc->flc_file == sys_flc->flc_file) | |
946 | return false; | |
947 | ||
948 | return locks_conflict(caller_flc, sys_flc); | |
949 | } | |
950 | ||
951 | void | |
952 | posix_test_lock(struct file *filp, struct file_lock *fl) | |
953 | { | |
954 | struct file_lock *cfl; | |
955 | struct file_lock_context *ctx; | |
956 | struct inode *inode = file_inode(filp); | |
957 | void *owner; | |
958 | void (*func)(void); | |
959 | ||
960 | ctx = locks_inode_context(inode); | |
961 | if (!ctx || list_empty_careful(&ctx->flc_posix)) { | |
962 | fl->c.flc_type = F_UNLCK; | |
963 | return; | |
964 | } | |
965 | ||
966 | retry: | |
967 | spin_lock(&ctx->flc_lock); | |
968 | list_for_each_entry(cfl, &ctx->flc_posix, c.flc_list) { | |
969 | if (!posix_test_locks_conflict(fl, cfl)) | |
970 | continue; | |
971 | if (cfl->fl_lmops && cfl->fl_lmops->lm_lock_expirable | |
972 | && (*cfl->fl_lmops->lm_lock_expirable)(cfl)) { | |
973 | owner = cfl->fl_lmops->lm_mod_owner; | |
974 | func = cfl->fl_lmops->lm_expire_lock; | |
975 | __module_get(owner); | |
976 | spin_unlock(&ctx->flc_lock); | |
977 | (*func)(); | |
978 | module_put(owner); | |
979 | goto retry; | |
980 | } | |
981 | locks_copy_conflock(fl, cfl); | |
982 | goto out; | |
983 | } | |
984 | fl->c.flc_type = F_UNLCK; | |
985 | out: | |
986 | spin_unlock(&ctx->flc_lock); | |
987 | return; | |
988 | } | |
989 | EXPORT_SYMBOL(posix_test_lock); | |
990 | ||
991 | /* | |
992 | * Deadlock detection: | |
993 | * | |
994 | * We attempt to detect deadlocks that are due purely to posix file | |
995 | * locks. | |
996 | * | |
997 | * We assume that a task can be waiting for at most one lock at a time. | |
998 | * So for any acquired lock, the process holding that lock may be | |
999 | * waiting on at most one other lock. That lock in turns may be held by | |
1000 | * someone waiting for at most one other lock. Given a requested lock | |
1001 | * caller_fl which is about to wait for a conflicting lock block_fl, we | |
1002 | * follow this chain of waiters to ensure we are not about to create a | |
1003 | * cycle. | |
1004 | * | |
1005 | * Since we do this before we ever put a process to sleep on a lock, we | |
1006 | * are ensured that there is never a cycle; that is what guarantees that | |
1007 | * the while() loop in posix_locks_deadlock() eventually completes. | |
1008 | * | |
1009 | * Note: the above assumption may not be true when handling lock | |
1010 | * requests from a broken NFS client. It may also fail in the presence | |
1011 | * of tasks (such as posix threads) sharing the same open file table. | |
1012 | * To handle those cases, we just bail out after a few iterations. | |
1013 | * | |
1014 | * For FL_OFDLCK locks, the owner is the filp, not the files_struct. | |
1015 | * Because the owner is not even nominally tied to a thread of | |
1016 | * execution, the deadlock detection below can't reasonably work well. Just | |
1017 | * skip it for those. | |
1018 | * | |
1019 | * In principle, we could do a more limited deadlock detection on FL_OFDLCK | |
1020 | * locks that just checks for the case where two tasks are attempting to | |
1021 | * upgrade from read to write locks on the same inode. | |
1022 | */ | |
1023 | ||
1024 | #define MAX_DEADLK_ITERATIONS 10 | |
1025 | ||
1026 | /* Find a lock that the owner of the given @blocker is blocking on. */ | |
1027 | static struct file_lock_core *what_owner_is_waiting_for(struct file_lock_core *blocker) | |
1028 | { | |
1029 | struct file_lock_core *flc; | |
1030 | ||
1031 | hash_for_each_possible(blocked_hash, flc, flc_link, posix_owner_key(blocker)) { | |
1032 | if (posix_same_owner(flc, blocker)) { | |
1033 | while (flc->flc_blocker) | |
1034 | flc = flc->flc_blocker; | |
1035 | return flc; | |
1036 | } | |
1037 | } | |
1038 | return NULL; | |
1039 | } | |
1040 | ||
1041 | /* Must be called with the blocked_lock_lock held! */ | |
1042 | static bool posix_locks_deadlock(struct file_lock *caller_fl, | |
1043 | struct file_lock *block_fl) | |
1044 | { | |
1045 | struct file_lock_core *caller = &caller_fl->c; | |
1046 | struct file_lock_core *blocker = &block_fl->c; | |
1047 | int i = 0; | |
1048 | ||
1049 | lockdep_assert_held(&blocked_lock_lock); | |
1050 | ||
1051 | /* | |
1052 | * This deadlock detector can't reasonably detect deadlocks with | |
1053 | * FL_OFDLCK locks, since they aren't owned by a process, per-se. | |
1054 | */ | |
1055 | if (caller->flc_flags & FL_OFDLCK) | |
1056 | return false; | |
1057 | ||
1058 | while ((blocker = what_owner_is_waiting_for(blocker))) { | |
1059 | if (i++ > MAX_DEADLK_ITERATIONS) | |
1060 | return false; | |
1061 | if (posix_same_owner(caller, blocker)) | |
1062 | return true; | |
1063 | } | |
1064 | return false; | |
1065 | } | |
1066 | ||
1067 | /* Try to create a FLOCK lock on filp. We always insert new FLOCK locks | |
1068 | * after any leases, but before any posix locks. | |
1069 | * | |
1070 | * Note that if called with an FL_EXISTS argument, the caller may determine | |
1071 | * whether or not a lock was successfully freed by testing the return | |
1072 | * value for -ENOENT. | |
1073 | */ | |
1074 | static int flock_lock_inode(struct inode *inode, struct file_lock *request) | |
1075 | { | |
1076 | struct file_lock *new_fl = NULL; | |
1077 | struct file_lock *fl; | |
1078 | struct file_lock_context *ctx; | |
1079 | int error = 0; | |
1080 | bool found = false; | |
1081 | LIST_HEAD(dispose); | |
1082 | ||
1083 | ctx = locks_get_lock_context(inode, request->c.flc_type); | |
1084 | if (!ctx) { | |
1085 | if (request->c.flc_type != F_UNLCK) | |
1086 | return -ENOMEM; | |
1087 | return (request->c.flc_flags & FL_EXISTS) ? -ENOENT : 0; | |
1088 | } | |
1089 | ||
1090 | if (!(request->c.flc_flags & FL_ACCESS) && (request->c.flc_type != F_UNLCK)) { | |
1091 | new_fl = locks_alloc_lock(); | |
1092 | if (!new_fl) | |
1093 | return -ENOMEM; | |
1094 | } | |
1095 | ||
1096 | percpu_down_read(&file_rwsem); | |
1097 | spin_lock(&ctx->flc_lock); | |
1098 | if (request->c.flc_flags & FL_ACCESS) | |
1099 | goto find_conflict; | |
1100 | ||
1101 | list_for_each_entry(fl, &ctx->flc_flock, c.flc_list) { | |
1102 | if (request->c.flc_file != fl->c.flc_file) | |
1103 | continue; | |
1104 | if (request->c.flc_type == fl->c.flc_type) | |
1105 | goto out; | |
1106 | found = true; | |
1107 | locks_delete_lock_ctx(&fl->c, &dispose); | |
1108 | break; | |
1109 | } | |
1110 | ||
1111 | if (lock_is_unlock(request)) { | |
1112 | if ((request->c.flc_flags & FL_EXISTS) && !found) | |
1113 | error = -ENOENT; | |
1114 | goto out; | |
1115 | } | |
1116 | ||
1117 | find_conflict: | |
1118 | list_for_each_entry(fl, &ctx->flc_flock, c.flc_list) { | |
1119 | if (!flock_locks_conflict(&request->c, &fl->c)) | |
1120 | continue; | |
1121 | error = -EAGAIN; | |
1122 | if (!(request->c.flc_flags & FL_SLEEP)) | |
1123 | goto out; | |
1124 | error = FILE_LOCK_DEFERRED; | |
1125 | locks_insert_block(&fl->c, &request->c, flock_locks_conflict); | |
1126 | goto out; | |
1127 | } | |
1128 | if (request->c.flc_flags & FL_ACCESS) | |
1129 | goto out; | |
1130 | locks_copy_lock(new_fl, request); | |
1131 | locks_move_blocks(new_fl, request); | |
1132 | locks_insert_lock_ctx(&new_fl->c, &ctx->flc_flock); | |
1133 | new_fl = NULL; | |
1134 | error = 0; | |
1135 | ||
1136 | out: | |
1137 | spin_unlock(&ctx->flc_lock); | |
1138 | percpu_up_read(&file_rwsem); | |
1139 | if (new_fl) | |
1140 | locks_free_lock(new_fl); | |
1141 | locks_dispose_list(&dispose); | |
1142 | trace_flock_lock_inode(inode, request, error); | |
1143 | return error; | |
1144 | } | |
1145 | ||
1146 | static int posix_lock_inode(struct inode *inode, struct file_lock *request, | |
1147 | struct file_lock *conflock) | |
1148 | { | |
1149 | struct file_lock *fl, *tmp; | |
1150 | struct file_lock *new_fl = NULL; | |
1151 | struct file_lock *new_fl2 = NULL; | |
1152 | struct file_lock *left = NULL; | |
1153 | struct file_lock *right = NULL; | |
1154 | struct file_lock_context *ctx; | |
1155 | int error; | |
1156 | bool added = false; | |
1157 | LIST_HEAD(dispose); | |
1158 | void *owner; | |
1159 | void (*func)(void); | |
1160 | ||
1161 | ctx = locks_get_lock_context(inode, request->c.flc_type); | |
1162 | if (!ctx) | |
1163 | return lock_is_unlock(request) ? 0 : -ENOMEM; | |
1164 | ||
1165 | /* | |
1166 | * We may need two file_lock structures for this operation, | |
1167 | * so we get them in advance to avoid races. | |
1168 | * | |
1169 | * In some cases we can be sure, that no new locks will be needed | |
1170 | */ | |
1171 | if (!(request->c.flc_flags & FL_ACCESS) && | |
1172 | (request->c.flc_type != F_UNLCK || | |
1173 | request->fl_start != 0 || request->fl_end != OFFSET_MAX)) { | |
1174 | new_fl = locks_alloc_lock(); | |
1175 | new_fl2 = locks_alloc_lock(); | |
1176 | } | |
1177 | ||
1178 | retry: | |
1179 | percpu_down_read(&file_rwsem); | |
1180 | spin_lock(&ctx->flc_lock); | |
1181 | /* | |
1182 | * New lock request. Walk all POSIX locks and look for conflicts. If | |
1183 | * there are any, either return error or put the request on the | |
1184 | * blocker's list of waiters and the global blocked_hash. | |
1185 | */ | |
1186 | if (request->c.flc_type != F_UNLCK) { | |
1187 | list_for_each_entry(fl, &ctx->flc_posix, c.flc_list) { | |
1188 | if (!posix_locks_conflict(&request->c, &fl->c)) | |
1189 | continue; | |
1190 | if (fl->fl_lmops && fl->fl_lmops->lm_lock_expirable | |
1191 | && (*fl->fl_lmops->lm_lock_expirable)(fl)) { | |
1192 | owner = fl->fl_lmops->lm_mod_owner; | |
1193 | func = fl->fl_lmops->lm_expire_lock; | |
1194 | __module_get(owner); | |
1195 | spin_unlock(&ctx->flc_lock); | |
1196 | percpu_up_read(&file_rwsem); | |
1197 | (*func)(); | |
1198 | module_put(owner); | |
1199 | goto retry; | |
1200 | } | |
1201 | if (conflock) | |
1202 | locks_copy_conflock(conflock, fl); | |
1203 | error = -EAGAIN; | |
1204 | if (!(request->c.flc_flags & FL_SLEEP)) | |
1205 | goto out; | |
1206 | /* | |
1207 | * Deadlock detection and insertion into the blocked | |
1208 | * locks list must be done while holding the same lock! | |
1209 | */ | |
1210 | error = -EDEADLK; | |
1211 | spin_lock(&blocked_lock_lock); | |
1212 | /* | |
1213 | * Ensure that we don't find any locks blocked on this | |
1214 | * request during deadlock detection. | |
1215 | */ | |
1216 | __locks_wake_up_blocks(&request->c); | |
1217 | if (likely(!posix_locks_deadlock(request, fl))) { | |
1218 | error = FILE_LOCK_DEFERRED; | |
1219 | __locks_insert_block(&fl->c, &request->c, | |
1220 | posix_locks_conflict); | |
1221 | } | |
1222 | spin_unlock(&blocked_lock_lock); | |
1223 | goto out; | |
1224 | } | |
1225 | } | |
1226 | ||
1227 | /* If we're just looking for a conflict, we're done. */ | |
1228 | error = 0; | |
1229 | if (request->c.flc_flags & FL_ACCESS) | |
1230 | goto out; | |
1231 | ||
1232 | /* Find the first old lock with the same owner as the new lock */ | |
1233 | list_for_each_entry(fl, &ctx->flc_posix, c.flc_list) { | |
1234 | if (posix_same_owner(&request->c, &fl->c)) | |
1235 | break; | |
1236 | } | |
1237 | ||
1238 | /* Process locks with this owner. */ | |
1239 | list_for_each_entry_safe_from(fl, tmp, &ctx->flc_posix, c.flc_list) { | |
1240 | if (!posix_same_owner(&request->c, &fl->c)) | |
1241 | break; | |
1242 | ||
1243 | /* Detect adjacent or overlapping regions (if same lock type) */ | |
1244 | if (request->c.flc_type == fl->c.flc_type) { | |
1245 | /* In all comparisons of start vs end, use | |
1246 | * "start - 1" rather than "end + 1". If end | |
1247 | * is OFFSET_MAX, end + 1 will become negative. | |
1248 | */ | |
1249 | if (fl->fl_end < request->fl_start - 1) | |
1250 | continue; | |
1251 | /* If the next lock in the list has entirely bigger | |
1252 | * addresses than the new one, insert the lock here. | |
1253 | */ | |
1254 | if (fl->fl_start - 1 > request->fl_end) | |
1255 | break; | |
1256 | ||
1257 | /* If we come here, the new and old lock are of the | |
1258 | * same type and adjacent or overlapping. Make one | |
1259 | * lock yielding from the lower start address of both | |
1260 | * locks to the higher end address. | |
1261 | */ | |
1262 | if (fl->fl_start > request->fl_start) | |
1263 | fl->fl_start = request->fl_start; | |
1264 | else | |
1265 | request->fl_start = fl->fl_start; | |
1266 | if (fl->fl_end < request->fl_end) | |
1267 | fl->fl_end = request->fl_end; | |
1268 | else | |
1269 | request->fl_end = fl->fl_end; | |
1270 | if (added) { | |
1271 | locks_delete_lock_ctx(&fl->c, &dispose); | |
1272 | continue; | |
1273 | } | |
1274 | request = fl; | |
1275 | added = true; | |
1276 | } else { | |
1277 | /* Processing for different lock types is a bit | |
1278 | * more complex. | |
1279 | */ | |
1280 | if (fl->fl_end < request->fl_start) | |
1281 | continue; | |
1282 | if (fl->fl_start > request->fl_end) | |
1283 | break; | |
1284 | if (lock_is_unlock(request)) | |
1285 | added = true; | |
1286 | if (fl->fl_start < request->fl_start) | |
1287 | left = fl; | |
1288 | /* If the next lock in the list has a higher end | |
1289 | * address than the new one, insert the new one here. | |
1290 | */ | |
1291 | if (fl->fl_end > request->fl_end) { | |
1292 | right = fl; | |
1293 | break; | |
1294 | } | |
1295 | if (fl->fl_start >= request->fl_start) { | |
1296 | /* The new lock completely replaces an old | |
1297 | * one (This may happen several times). | |
1298 | */ | |
1299 | if (added) { | |
1300 | locks_delete_lock_ctx(&fl->c, &dispose); | |
1301 | continue; | |
1302 | } | |
1303 | /* | |
1304 | * Replace the old lock with new_fl, and | |
1305 | * remove the old one. It's safe to do the | |
1306 | * insert here since we know that we won't be | |
1307 | * using new_fl later, and that the lock is | |
1308 | * just replacing an existing lock. | |
1309 | */ | |
1310 | error = -ENOLCK; | |
1311 | if (!new_fl) | |
1312 | goto out; | |
1313 | locks_copy_lock(new_fl, request); | |
1314 | locks_move_blocks(new_fl, request); | |
1315 | request = new_fl; | |
1316 | new_fl = NULL; | |
1317 | locks_insert_lock_ctx(&request->c, | |
1318 | &fl->c.flc_list); | |
1319 | locks_delete_lock_ctx(&fl->c, &dispose); | |
1320 | added = true; | |
1321 | } | |
1322 | } | |
1323 | } | |
1324 | ||
1325 | /* | |
1326 | * The above code only modifies existing locks in case of merging or | |
1327 | * replacing. If new lock(s) need to be inserted all modifications are | |
1328 | * done below this, so it's safe yet to bail out. | |
1329 | */ | |
1330 | error = -ENOLCK; /* "no luck" */ | |
1331 | if (right && left == right && !new_fl2) | |
1332 | goto out; | |
1333 | ||
1334 | error = 0; | |
1335 | if (!added) { | |
1336 | if (lock_is_unlock(request)) { | |
1337 | if (request->c.flc_flags & FL_EXISTS) | |
1338 | error = -ENOENT; | |
1339 | goto out; | |
1340 | } | |
1341 | ||
1342 | if (!new_fl) { | |
1343 | error = -ENOLCK; | |
1344 | goto out; | |
1345 | } | |
1346 | locks_copy_lock(new_fl, request); | |
1347 | locks_move_blocks(new_fl, request); | |
1348 | locks_insert_lock_ctx(&new_fl->c, &fl->c.flc_list); | |
1349 | fl = new_fl; | |
1350 | new_fl = NULL; | |
1351 | } | |
1352 | if (right) { | |
1353 | if (left == right) { | |
1354 | /* The new lock breaks the old one in two pieces, | |
1355 | * so we have to use the second new lock. | |
1356 | */ | |
1357 | left = new_fl2; | |
1358 | new_fl2 = NULL; | |
1359 | locks_copy_lock(left, right); | |
1360 | locks_insert_lock_ctx(&left->c, &fl->c.flc_list); | |
1361 | } | |
1362 | right->fl_start = request->fl_end + 1; | |
1363 | locks_wake_up_blocks(&right->c); | |
1364 | } | |
1365 | if (left) { | |
1366 | left->fl_end = request->fl_start - 1; | |
1367 | locks_wake_up_blocks(&left->c); | |
1368 | } | |
1369 | out: | |
1370 | trace_posix_lock_inode(inode, request, error); | |
1371 | spin_unlock(&ctx->flc_lock); | |
1372 | percpu_up_read(&file_rwsem); | |
1373 | /* | |
1374 | * Free any unused locks. | |
1375 | */ | |
1376 | if (new_fl) | |
1377 | locks_free_lock(new_fl); | |
1378 | if (new_fl2) | |
1379 | locks_free_lock(new_fl2); | |
1380 | locks_dispose_list(&dispose); | |
1381 | ||
1382 | return error; | |
1383 | } | |
1384 | ||
1385 | /** | |
1386 | * posix_lock_file - Apply a POSIX-style lock to a file | |
1387 | * @filp: The file to apply the lock to | |
1388 | * @fl: The lock to be applied | |
1389 | * @conflock: Place to return a copy of the conflicting lock, if found. | |
1390 | * | |
1391 | * Add a POSIX style lock to a file. | |
1392 | * We merge adjacent & overlapping locks whenever possible. | |
1393 | * POSIX locks are sorted by owner task, then by starting address | |
1394 | * | |
1395 | * Note that if called with an FL_EXISTS argument, the caller may determine | |
1396 | * whether or not a lock was successfully freed by testing the return | |
1397 | * value for -ENOENT. | |
1398 | */ | |
1399 | int posix_lock_file(struct file *filp, struct file_lock *fl, | |
1400 | struct file_lock *conflock) | |
1401 | { | |
1402 | return posix_lock_inode(file_inode(filp), fl, conflock); | |
1403 | } | |
1404 | EXPORT_SYMBOL(posix_lock_file); | |
1405 | ||
1406 | /** | |
1407 | * posix_lock_inode_wait - Apply a POSIX-style lock to a file | |
1408 | * @inode: inode of file to which lock request should be applied | |
1409 | * @fl: The lock to be applied | |
1410 | * | |
1411 | * Apply a POSIX style lock request to an inode. | |
1412 | */ | |
1413 | static int posix_lock_inode_wait(struct inode *inode, struct file_lock *fl) | |
1414 | { | |
1415 | int error; | |
1416 | might_sleep (); | |
1417 | for (;;) { | |
1418 | error = posix_lock_inode(inode, fl, NULL); | |
1419 | if (error != FILE_LOCK_DEFERRED) | |
1420 | break; | |
1421 | error = wait_event_interruptible(fl->c.flc_wait, | |
1422 | list_empty(&fl->c.flc_blocked_member)); | |
1423 | if (error) | |
1424 | break; | |
1425 | } | |
1426 | locks_delete_block(fl); | |
1427 | return error; | |
1428 | } | |
1429 | ||
1430 | static void lease_clear_pending(struct file_lease *fl, int arg) | |
1431 | { | |
1432 | switch (arg) { | |
1433 | case F_UNLCK: | |
1434 | fl->c.flc_flags &= ~FL_UNLOCK_PENDING; | |
1435 | fallthrough; | |
1436 | case F_RDLCK: | |
1437 | fl->c.flc_flags &= ~FL_DOWNGRADE_PENDING; | |
1438 | } | |
1439 | } | |
1440 | ||
1441 | /* We already had a lease on this file; just change its type */ | |
1442 | int lease_modify(struct file_lease *fl, int arg, struct list_head *dispose) | |
1443 | { | |
1444 | int error = assign_type(&fl->c, arg); | |
1445 | ||
1446 | if (error) | |
1447 | return error; | |
1448 | lease_clear_pending(fl, arg); | |
1449 | locks_wake_up_blocks(&fl->c); | |
1450 | if (arg == F_UNLCK) { | |
1451 | struct file *filp = fl->c.flc_file; | |
1452 | ||
1453 | f_delown(filp); | |
1454 | file_f_owner(filp)->signum = 0; | |
1455 | fasync_helper(0, fl->c.flc_file, 0, &fl->fl_fasync); | |
1456 | if (fl->fl_fasync != NULL) { | |
1457 | printk(KERN_ERR "locks_delete_lock: fasync == %p\n", fl->fl_fasync); | |
1458 | fl->fl_fasync = NULL; | |
1459 | } | |
1460 | locks_delete_lock_ctx(&fl->c, dispose); | |
1461 | } | |
1462 | return 0; | |
1463 | } | |
1464 | EXPORT_SYMBOL(lease_modify); | |
1465 | ||
1466 | static bool past_time(unsigned long then) | |
1467 | { | |
1468 | if (!then) | |
1469 | /* 0 is a special value meaning "this never expires": */ | |
1470 | return false; | |
1471 | return time_after(jiffies, then); | |
1472 | } | |
1473 | ||
1474 | static void time_out_leases(struct inode *inode, struct list_head *dispose) | |
1475 | { | |
1476 | struct file_lock_context *ctx = inode->i_flctx; | |
1477 | struct file_lease *fl, *tmp; | |
1478 | ||
1479 | lockdep_assert_held(&ctx->flc_lock); | |
1480 | ||
1481 | list_for_each_entry_safe(fl, tmp, &ctx->flc_lease, c.flc_list) { | |
1482 | trace_time_out_leases(inode, fl); | |
1483 | if (past_time(fl->fl_downgrade_time)) | |
1484 | lease_modify(fl, F_RDLCK, dispose); | |
1485 | if (past_time(fl->fl_break_time)) | |
1486 | lease_modify(fl, F_UNLCK, dispose); | |
1487 | } | |
1488 | } | |
1489 | ||
1490 | static bool leases_conflict(struct file_lock_core *lc, struct file_lock_core *bc) | |
1491 | { | |
1492 | bool rc; | |
1493 | struct file_lease *lease = file_lease(lc); | |
1494 | struct file_lease *breaker = file_lease(bc); | |
1495 | ||
1496 | if (lease->fl_lmops->lm_breaker_owns_lease | |
1497 | && lease->fl_lmops->lm_breaker_owns_lease(lease)) | |
1498 | return false; | |
1499 | if ((bc->flc_flags & FL_LAYOUT) != (lc->flc_flags & FL_LAYOUT)) { | |
1500 | rc = false; | |
1501 | goto trace; | |
1502 | } | |
1503 | if ((bc->flc_flags & FL_DELEG) && (lc->flc_flags & FL_LEASE)) { | |
1504 | rc = false; | |
1505 | goto trace; | |
1506 | } | |
1507 | ||
1508 | rc = locks_conflict(bc, lc); | |
1509 | trace: | |
1510 | trace_leases_conflict(rc, lease, breaker); | |
1511 | return rc; | |
1512 | } | |
1513 | ||
1514 | static bool | |
1515 | any_leases_conflict(struct inode *inode, struct file_lease *breaker) | |
1516 | { | |
1517 | struct file_lock_context *ctx = inode->i_flctx; | |
1518 | struct file_lock_core *flc; | |
1519 | ||
1520 | lockdep_assert_held(&ctx->flc_lock); | |
1521 | ||
1522 | list_for_each_entry(flc, &ctx->flc_lease, flc_list) { | |
1523 | if (leases_conflict(flc, &breaker->c)) | |
1524 | return true; | |
1525 | } | |
1526 | return false; | |
1527 | } | |
1528 | ||
1529 | /** | |
1530 | * __break_lease - revoke all outstanding leases on file | |
1531 | * @inode: the inode of the file to return | |
1532 | * @mode: O_RDONLY: break only write leases; O_WRONLY or O_RDWR: | |
1533 | * break all leases | |
1534 | * @type: FL_LEASE: break leases and delegations; FL_DELEG: break | |
1535 | * only delegations | |
1536 | * | |
1537 | * break_lease (inlined for speed) has checked there already is at least | |
1538 | * some kind of lock (maybe a lease) on this file. Leases are broken on | |
1539 | * a call to open() or truncate(). This function can sleep unless you | |
1540 | * specified %O_NONBLOCK to your open(). | |
1541 | */ | |
1542 | int __break_lease(struct inode *inode, unsigned int mode, unsigned int type) | |
1543 | { | |
1544 | int error = 0; | |
1545 | struct file_lock_context *ctx; | |
1546 | struct file_lease *new_fl, *fl, *tmp; | |
1547 | unsigned long break_time; | |
1548 | int want_write = (mode & O_ACCMODE) != O_RDONLY; | |
1549 | LIST_HEAD(dispose); | |
1550 | ||
1551 | new_fl = lease_alloc(NULL, want_write ? F_WRLCK : F_RDLCK); | |
1552 | if (IS_ERR(new_fl)) | |
1553 | return PTR_ERR(new_fl); | |
1554 | new_fl->c.flc_flags = type; | |
1555 | ||
1556 | /* typically we will check that ctx is non-NULL before calling */ | |
1557 | ctx = locks_inode_context(inode); | |
1558 | if (!ctx) { | |
1559 | WARN_ON_ONCE(1); | |
1560 | goto free_lock; | |
1561 | } | |
1562 | ||
1563 | percpu_down_read(&file_rwsem); | |
1564 | spin_lock(&ctx->flc_lock); | |
1565 | ||
1566 | time_out_leases(inode, &dispose); | |
1567 | ||
1568 | if (!any_leases_conflict(inode, new_fl)) | |
1569 | goto out; | |
1570 | ||
1571 | break_time = 0; | |
1572 | if (lease_break_time > 0) { | |
1573 | break_time = jiffies + lease_break_time * HZ; | |
1574 | if (break_time == 0) | |
1575 | break_time++; /* so that 0 means no break time */ | |
1576 | } | |
1577 | ||
1578 | list_for_each_entry_safe(fl, tmp, &ctx->flc_lease, c.flc_list) { | |
1579 | if (!leases_conflict(&fl->c, &new_fl->c)) | |
1580 | continue; | |
1581 | if (want_write) { | |
1582 | if (fl->c.flc_flags & FL_UNLOCK_PENDING) | |
1583 | continue; | |
1584 | fl->c.flc_flags |= FL_UNLOCK_PENDING; | |
1585 | fl->fl_break_time = break_time; | |
1586 | } else { | |
1587 | if (lease_breaking(fl)) | |
1588 | continue; | |
1589 | fl->c.flc_flags |= FL_DOWNGRADE_PENDING; | |
1590 | fl->fl_downgrade_time = break_time; | |
1591 | } | |
1592 | if (fl->fl_lmops->lm_break(fl)) | |
1593 | locks_delete_lock_ctx(&fl->c, &dispose); | |
1594 | } | |
1595 | ||
1596 | if (list_empty(&ctx->flc_lease)) | |
1597 | goto out; | |
1598 | ||
1599 | if (mode & O_NONBLOCK) { | |
1600 | trace_break_lease_noblock(inode, new_fl); | |
1601 | error = -EWOULDBLOCK; | |
1602 | goto out; | |
1603 | } | |
1604 | ||
1605 | restart: | |
1606 | fl = list_first_entry(&ctx->flc_lease, struct file_lease, c.flc_list); | |
1607 | break_time = fl->fl_break_time; | |
1608 | if (break_time != 0) | |
1609 | break_time -= jiffies; | |
1610 | if (break_time == 0) | |
1611 | break_time++; | |
1612 | locks_insert_block(&fl->c, &new_fl->c, leases_conflict); | |
1613 | trace_break_lease_block(inode, new_fl); | |
1614 | spin_unlock(&ctx->flc_lock); | |
1615 | percpu_up_read(&file_rwsem); | |
1616 | ||
1617 | locks_dispose_list(&dispose); | |
1618 | error = wait_event_interruptible_timeout(new_fl->c.flc_wait, | |
1619 | list_empty(&new_fl->c.flc_blocked_member), | |
1620 | break_time); | |
1621 | ||
1622 | percpu_down_read(&file_rwsem); | |
1623 | spin_lock(&ctx->flc_lock); | |
1624 | trace_break_lease_unblock(inode, new_fl); | |
1625 | __locks_delete_block(&new_fl->c); | |
1626 | if (error >= 0) { | |
1627 | /* | |
1628 | * Wait for the next conflicting lease that has not been | |
1629 | * broken yet | |
1630 | */ | |
1631 | if (error == 0) | |
1632 | time_out_leases(inode, &dispose); | |
1633 | if (any_leases_conflict(inode, new_fl)) | |
1634 | goto restart; | |
1635 | error = 0; | |
1636 | } | |
1637 | out: | |
1638 | spin_unlock(&ctx->flc_lock); | |
1639 | percpu_up_read(&file_rwsem); | |
1640 | locks_dispose_list(&dispose); | |
1641 | free_lock: | |
1642 | locks_free_lease(new_fl); | |
1643 | return error; | |
1644 | } | |
1645 | EXPORT_SYMBOL(__break_lease); | |
1646 | ||
1647 | /** | |
1648 | * lease_get_mtime - update modified time of an inode with exclusive lease | |
1649 | * @inode: the inode | |
1650 | * @time: pointer to a timespec which contains the last modified time | |
1651 | * | |
1652 | * This is to force NFS clients to flush their caches for files with | |
1653 | * exclusive leases. The justification is that if someone has an | |
1654 | * exclusive lease, then they could be modifying it. | |
1655 | */ | |
1656 | void lease_get_mtime(struct inode *inode, struct timespec64 *time) | |
1657 | { | |
1658 | bool has_lease = false; | |
1659 | struct file_lock_context *ctx; | |
1660 | struct file_lock_core *flc; | |
1661 | ||
1662 | ctx = locks_inode_context(inode); | |
1663 | if (ctx && !list_empty_careful(&ctx->flc_lease)) { | |
1664 | spin_lock(&ctx->flc_lock); | |
1665 | flc = list_first_entry_or_null(&ctx->flc_lease, | |
1666 | struct file_lock_core, flc_list); | |
1667 | if (flc && flc->flc_type == F_WRLCK) | |
1668 | has_lease = true; | |
1669 | spin_unlock(&ctx->flc_lock); | |
1670 | } | |
1671 | ||
1672 | if (has_lease) | |
1673 | *time = current_time(inode); | |
1674 | } | |
1675 | EXPORT_SYMBOL(lease_get_mtime); | |
1676 | ||
1677 | /** | |
1678 | * fcntl_getlease - Enquire what lease is currently active | |
1679 | * @filp: the file | |
1680 | * | |
1681 | * The value returned by this function will be one of | |
1682 | * (if no lease break is pending): | |
1683 | * | |
1684 | * %F_RDLCK to indicate a shared lease is held. | |
1685 | * | |
1686 | * %F_WRLCK to indicate an exclusive lease is held. | |
1687 | * | |
1688 | * %F_UNLCK to indicate no lease is held. | |
1689 | * | |
1690 | * (if a lease break is pending): | |
1691 | * | |
1692 | * %F_RDLCK to indicate an exclusive lease needs to be | |
1693 | * changed to a shared lease (or removed). | |
1694 | * | |
1695 | * %F_UNLCK to indicate the lease needs to be removed. | |
1696 | * | |
1697 | * XXX: sfr & willy disagree over whether F_INPROGRESS | |
1698 | * should be returned to userspace. | |
1699 | */ | |
1700 | int fcntl_getlease(struct file *filp) | |
1701 | { | |
1702 | struct file_lease *fl; | |
1703 | struct inode *inode = file_inode(filp); | |
1704 | struct file_lock_context *ctx; | |
1705 | int type = F_UNLCK; | |
1706 | LIST_HEAD(dispose); | |
1707 | ||
1708 | ctx = locks_inode_context(inode); | |
1709 | if (ctx && !list_empty_careful(&ctx->flc_lease)) { | |
1710 | percpu_down_read(&file_rwsem); | |
1711 | spin_lock(&ctx->flc_lock); | |
1712 | time_out_leases(inode, &dispose); | |
1713 | list_for_each_entry(fl, &ctx->flc_lease, c.flc_list) { | |
1714 | if (fl->c.flc_file != filp) | |
1715 | continue; | |
1716 | type = target_leasetype(fl); | |
1717 | break; | |
1718 | } | |
1719 | spin_unlock(&ctx->flc_lock); | |
1720 | percpu_up_read(&file_rwsem); | |
1721 | ||
1722 | locks_dispose_list(&dispose); | |
1723 | } | |
1724 | return type; | |
1725 | } | |
1726 | ||
1727 | /** | |
1728 | * check_conflicting_open - see if the given file points to an inode that has | |
1729 | * an existing open that would conflict with the | |
1730 | * desired lease. | |
1731 | * @filp: file to check | |
1732 | * @arg: type of lease that we're trying to acquire | |
1733 | * @flags: current lock flags | |
1734 | * | |
1735 | * Check to see if there's an existing open fd on this file that would | |
1736 | * conflict with the lease we're trying to set. | |
1737 | */ | |
1738 | static int | |
1739 | check_conflicting_open(struct file *filp, const int arg, int flags) | |
1740 | { | |
1741 | struct inode *inode = file_inode(filp); | |
1742 | int self_wcount = 0, self_rcount = 0; | |
1743 | ||
1744 | if (flags & FL_LAYOUT) | |
1745 | return 0; | |
1746 | if (flags & FL_DELEG) | |
1747 | /* We leave these checks to the caller */ | |
1748 | return 0; | |
1749 | ||
1750 | if (arg == F_RDLCK) | |
1751 | return inode_is_open_for_write(inode) ? -EAGAIN : 0; | |
1752 | else if (arg != F_WRLCK) | |
1753 | return 0; | |
1754 | ||
1755 | /* | |
1756 | * Make sure that only read/write count is from lease requestor. | |
1757 | * Note that this will result in denying write leases when i_writecount | |
1758 | * is negative, which is what we want. (We shouldn't grant write leases | |
1759 | * on files open for execution.) | |
1760 | */ | |
1761 | if (filp->f_mode & FMODE_WRITE) | |
1762 | self_wcount = 1; | |
1763 | else if (filp->f_mode & FMODE_READ) | |
1764 | self_rcount = 1; | |
1765 | ||
1766 | if (atomic_read(&inode->i_writecount) != self_wcount || | |
1767 | atomic_read(&inode->i_readcount) != self_rcount) | |
1768 | return -EAGAIN; | |
1769 | ||
1770 | return 0; | |
1771 | } | |
1772 | ||
1773 | static int | |
1774 | generic_add_lease(struct file *filp, int arg, struct file_lease **flp, void **priv) | |
1775 | { | |
1776 | struct file_lease *fl, *my_fl = NULL, *lease; | |
1777 | struct inode *inode = file_inode(filp); | |
1778 | struct file_lock_context *ctx; | |
1779 | bool is_deleg = (*flp)->c.flc_flags & FL_DELEG; | |
1780 | int error; | |
1781 | LIST_HEAD(dispose); | |
1782 | ||
1783 | lease = *flp; | |
1784 | trace_generic_add_lease(inode, lease); | |
1785 | ||
1786 | error = file_f_owner_allocate(filp); | |
1787 | if (error) | |
1788 | return error; | |
1789 | ||
1790 | /* Note that arg is never F_UNLCK here */ | |
1791 | ctx = locks_get_lock_context(inode, arg); | |
1792 | if (!ctx) | |
1793 | return -ENOMEM; | |
1794 | ||
1795 | /* | |
1796 | * In the delegation case we need mutual exclusion with | |
1797 | * a number of operations that take the i_mutex. We trylock | |
1798 | * because delegations are an optional optimization, and if | |
1799 | * there's some chance of a conflict--we'd rather not | |
1800 | * bother, maybe that's a sign this just isn't a good file to | |
1801 | * hand out a delegation on. | |
1802 | */ | |
1803 | if (is_deleg && !inode_trylock(inode)) | |
1804 | return -EAGAIN; | |
1805 | ||
1806 | percpu_down_read(&file_rwsem); | |
1807 | spin_lock(&ctx->flc_lock); | |
1808 | time_out_leases(inode, &dispose); | |
1809 | error = check_conflicting_open(filp, arg, lease->c.flc_flags); | |
1810 | if (error) | |
1811 | goto out; | |
1812 | ||
1813 | /* | |
1814 | * At this point, we know that if there is an exclusive | |
1815 | * lease on this file, then we hold it on this filp | |
1816 | * (otherwise our open of this file would have blocked). | |
1817 | * And if we are trying to acquire an exclusive lease, | |
1818 | * then the file is not open by anyone (including us) | |
1819 | * except for this filp. | |
1820 | */ | |
1821 | error = -EAGAIN; | |
1822 | list_for_each_entry(fl, &ctx->flc_lease, c.flc_list) { | |
1823 | if (fl->c.flc_file == filp && | |
1824 | fl->c.flc_owner == lease->c.flc_owner) { | |
1825 | my_fl = fl; | |
1826 | continue; | |
1827 | } | |
1828 | ||
1829 | /* | |
1830 | * No exclusive leases if someone else has a lease on | |
1831 | * this file: | |
1832 | */ | |
1833 | if (arg == F_WRLCK) | |
1834 | goto out; | |
1835 | /* | |
1836 | * Modifying our existing lease is OK, but no getting a | |
1837 | * new lease if someone else is opening for write: | |
1838 | */ | |
1839 | if (fl->c.flc_flags & FL_UNLOCK_PENDING) | |
1840 | goto out; | |
1841 | } | |
1842 | ||
1843 | if (my_fl != NULL) { | |
1844 | lease = my_fl; | |
1845 | error = lease->fl_lmops->lm_change(lease, arg, &dispose); | |
1846 | if (error) | |
1847 | goto out; | |
1848 | goto out_setup; | |
1849 | } | |
1850 | ||
1851 | error = -EINVAL; | |
1852 | if (!leases_enable) | |
1853 | goto out; | |
1854 | ||
1855 | locks_insert_lock_ctx(&lease->c, &ctx->flc_lease); | |
1856 | /* | |
1857 | * The check in break_lease() is lockless. It's possible for another | |
1858 | * open to race in after we did the earlier check for a conflicting | |
1859 | * open but before the lease was inserted. Check again for a | |
1860 | * conflicting open and cancel the lease if there is one. | |
1861 | * | |
1862 | * We also add a barrier here to ensure that the insertion of the lock | |
1863 | * precedes these checks. | |
1864 | */ | |
1865 | smp_mb(); | |
1866 | error = check_conflicting_open(filp, arg, lease->c.flc_flags); | |
1867 | if (error) { | |
1868 | locks_unlink_lock_ctx(&lease->c); | |
1869 | goto out; | |
1870 | } | |
1871 | ||
1872 | out_setup: | |
1873 | if (lease->fl_lmops->lm_setup) | |
1874 | lease->fl_lmops->lm_setup(lease, priv); | |
1875 | out: | |
1876 | spin_unlock(&ctx->flc_lock); | |
1877 | percpu_up_read(&file_rwsem); | |
1878 | locks_dispose_list(&dispose); | |
1879 | if (is_deleg) | |
1880 | inode_unlock(inode); | |
1881 | if (!error && !my_fl) | |
1882 | *flp = NULL; | |
1883 | return error; | |
1884 | } | |
1885 | ||
1886 | static int generic_delete_lease(struct file *filp, void *owner) | |
1887 | { | |
1888 | int error = -EAGAIN; | |
1889 | struct file_lease *fl, *victim = NULL; | |
1890 | struct inode *inode = file_inode(filp); | |
1891 | struct file_lock_context *ctx; | |
1892 | LIST_HEAD(dispose); | |
1893 | ||
1894 | ctx = locks_inode_context(inode); | |
1895 | if (!ctx) { | |
1896 | trace_generic_delete_lease(inode, NULL); | |
1897 | return error; | |
1898 | } | |
1899 | ||
1900 | percpu_down_read(&file_rwsem); | |
1901 | spin_lock(&ctx->flc_lock); | |
1902 | list_for_each_entry(fl, &ctx->flc_lease, c.flc_list) { | |
1903 | if (fl->c.flc_file == filp && | |
1904 | fl->c.flc_owner == owner) { | |
1905 | victim = fl; | |
1906 | break; | |
1907 | } | |
1908 | } | |
1909 | trace_generic_delete_lease(inode, victim); | |
1910 | if (victim) | |
1911 | error = fl->fl_lmops->lm_change(victim, F_UNLCK, &dispose); | |
1912 | spin_unlock(&ctx->flc_lock); | |
1913 | percpu_up_read(&file_rwsem); | |
1914 | locks_dispose_list(&dispose); | |
1915 | return error; | |
1916 | } | |
1917 | ||
1918 | /** | |
1919 | * generic_setlease - sets a lease on an open file | |
1920 | * @filp: file pointer | |
1921 | * @arg: type of lease to obtain | |
1922 | * @flp: input - file_lock to use, output - file_lock inserted | |
1923 | * @priv: private data for lm_setup (may be NULL if lm_setup | |
1924 | * doesn't require it) | |
1925 | * | |
1926 | * The (input) flp->fl_lmops->lm_break function is required | |
1927 | * by break_lease(). | |
1928 | */ | |
1929 | int generic_setlease(struct file *filp, int arg, struct file_lease **flp, | |
1930 | void **priv) | |
1931 | { | |
1932 | switch (arg) { | |
1933 | case F_UNLCK: | |
1934 | return generic_delete_lease(filp, *priv); | |
1935 | case F_RDLCK: | |
1936 | case F_WRLCK: | |
1937 | if (!(*flp)->fl_lmops->lm_break) { | |
1938 | WARN_ON_ONCE(1); | |
1939 | return -ENOLCK; | |
1940 | } | |
1941 | ||
1942 | return generic_add_lease(filp, arg, flp, priv); | |
1943 | default: | |
1944 | return -EINVAL; | |
1945 | } | |
1946 | } | |
1947 | EXPORT_SYMBOL(generic_setlease); | |
1948 | ||
1949 | /* | |
1950 | * Kernel subsystems can register to be notified on any attempt to set | |
1951 | * a new lease with the lease_notifier_chain. This is used by (e.g.) nfsd | |
1952 | * to close files that it may have cached when there is an attempt to set a | |
1953 | * conflicting lease. | |
1954 | */ | |
1955 | static struct srcu_notifier_head lease_notifier_chain; | |
1956 | ||
1957 | static inline void | |
1958 | lease_notifier_chain_init(void) | |
1959 | { | |
1960 | srcu_init_notifier_head(&lease_notifier_chain); | |
1961 | } | |
1962 | ||
1963 | static inline void | |
1964 | setlease_notifier(int arg, struct file_lease *lease) | |
1965 | { | |
1966 | if (arg != F_UNLCK) | |
1967 | srcu_notifier_call_chain(&lease_notifier_chain, arg, lease); | |
1968 | } | |
1969 | ||
1970 | int lease_register_notifier(struct notifier_block *nb) | |
1971 | { | |
1972 | return srcu_notifier_chain_register(&lease_notifier_chain, nb); | |
1973 | } | |
1974 | EXPORT_SYMBOL_GPL(lease_register_notifier); | |
1975 | ||
1976 | void lease_unregister_notifier(struct notifier_block *nb) | |
1977 | { | |
1978 | srcu_notifier_chain_unregister(&lease_notifier_chain, nb); | |
1979 | } | |
1980 | EXPORT_SYMBOL_GPL(lease_unregister_notifier); | |
1981 | ||
1982 | ||
1983 | int | |
1984 | kernel_setlease(struct file *filp, int arg, struct file_lease **lease, void **priv) | |
1985 | { | |
1986 | if (lease) | |
1987 | setlease_notifier(arg, *lease); | |
1988 | if (filp->f_op->setlease) | |
1989 | return filp->f_op->setlease(filp, arg, lease, priv); | |
1990 | else | |
1991 | return generic_setlease(filp, arg, lease, priv); | |
1992 | } | |
1993 | EXPORT_SYMBOL_GPL(kernel_setlease); | |
1994 | ||
1995 | /** | |
1996 | * vfs_setlease - sets a lease on an open file | |
1997 | * @filp: file pointer | |
1998 | * @arg: type of lease to obtain | |
1999 | * @lease: file_lock to use when adding a lease | |
2000 | * @priv: private info for lm_setup when adding a lease (may be | |
2001 | * NULL if lm_setup doesn't require it) | |
2002 | * | |
2003 | * Call this to establish a lease on the file. The "lease" argument is not | |
2004 | * used for F_UNLCK requests and may be NULL. For commands that set or alter | |
2005 | * an existing lease, the ``(*lease)->fl_lmops->lm_break`` operation must be | |
2006 | * set; if not, this function will return -ENOLCK (and generate a scary-looking | |
2007 | * stack trace). | |
2008 | * | |
2009 | * The "priv" pointer is passed directly to the lm_setup function as-is. It | |
2010 | * may be NULL if the lm_setup operation doesn't require it. | |
2011 | */ | |
2012 | int | |
2013 | vfs_setlease(struct file *filp, int arg, struct file_lease **lease, void **priv) | |
2014 | { | |
2015 | struct inode *inode = file_inode(filp); | |
2016 | vfsuid_t vfsuid = i_uid_into_vfsuid(file_mnt_idmap(filp), inode); | |
2017 | int error; | |
2018 | ||
2019 | if ((!vfsuid_eq_kuid(vfsuid, current_fsuid())) && !capable(CAP_LEASE)) | |
2020 | return -EACCES; | |
2021 | if (!S_ISREG(inode->i_mode)) | |
2022 | return -EINVAL; | |
2023 | error = security_file_lock(filp, arg); | |
2024 | if (error) | |
2025 | return error; | |
2026 | return kernel_setlease(filp, arg, lease, priv); | |
2027 | } | |
2028 | EXPORT_SYMBOL_GPL(vfs_setlease); | |
2029 | ||
2030 | static int do_fcntl_add_lease(unsigned int fd, struct file *filp, int arg) | |
2031 | { | |
2032 | struct file_lease *fl; | |
2033 | struct fasync_struct *new; | |
2034 | int error; | |
2035 | ||
2036 | fl = lease_alloc(filp, arg); | |
2037 | if (IS_ERR(fl)) | |
2038 | return PTR_ERR(fl); | |
2039 | ||
2040 | new = fasync_alloc(); | |
2041 | if (!new) { | |
2042 | locks_free_lease(fl); | |
2043 | return -ENOMEM; | |
2044 | } | |
2045 | new->fa_fd = fd; | |
2046 | ||
2047 | error = vfs_setlease(filp, arg, &fl, (void **)&new); | |
2048 | if (fl) | |
2049 | locks_free_lease(fl); | |
2050 | if (new) | |
2051 | fasync_free(new); | |
2052 | return error; | |
2053 | } | |
2054 | ||
2055 | /** | |
2056 | * fcntl_setlease - sets a lease on an open file | |
2057 | * @fd: open file descriptor | |
2058 | * @filp: file pointer | |
2059 | * @arg: type of lease to obtain | |
2060 | * | |
2061 | * Call this fcntl to establish a lease on the file. | |
2062 | * Note that you also need to call %F_SETSIG to | |
2063 | * receive a signal when the lease is broken. | |
2064 | */ | |
2065 | int fcntl_setlease(unsigned int fd, struct file *filp, int arg) | |
2066 | { | |
2067 | if (arg == F_UNLCK) | |
2068 | return vfs_setlease(filp, F_UNLCK, NULL, (void **)&filp); | |
2069 | return do_fcntl_add_lease(fd, filp, arg); | |
2070 | } | |
2071 | ||
2072 | /** | |
2073 | * flock_lock_inode_wait - Apply a FLOCK-style lock to a file | |
2074 | * @inode: inode of the file to apply to | |
2075 | * @fl: The lock to be applied | |
2076 | * | |
2077 | * Apply a FLOCK style lock request to an inode. | |
2078 | */ | |
2079 | static int flock_lock_inode_wait(struct inode *inode, struct file_lock *fl) | |
2080 | { | |
2081 | int error; | |
2082 | might_sleep(); | |
2083 | for (;;) { | |
2084 | error = flock_lock_inode(inode, fl); | |
2085 | if (error != FILE_LOCK_DEFERRED) | |
2086 | break; | |
2087 | error = wait_event_interruptible(fl->c.flc_wait, | |
2088 | list_empty(&fl->c.flc_blocked_member)); | |
2089 | if (error) | |
2090 | break; | |
2091 | } | |
2092 | locks_delete_block(fl); | |
2093 | return error; | |
2094 | } | |
2095 | ||
2096 | /** | |
2097 | * locks_lock_inode_wait - Apply a lock to an inode | |
2098 | * @inode: inode of the file to apply to | |
2099 | * @fl: The lock to be applied | |
2100 | * | |
2101 | * Apply a POSIX or FLOCK style lock request to an inode. | |
2102 | */ | |
2103 | int locks_lock_inode_wait(struct inode *inode, struct file_lock *fl) | |
2104 | { | |
2105 | int res = 0; | |
2106 | switch (fl->c.flc_flags & (FL_POSIX|FL_FLOCK)) { | |
2107 | case FL_POSIX: | |
2108 | res = posix_lock_inode_wait(inode, fl); | |
2109 | break; | |
2110 | case FL_FLOCK: | |
2111 | res = flock_lock_inode_wait(inode, fl); | |
2112 | break; | |
2113 | default: | |
2114 | BUG(); | |
2115 | } | |
2116 | return res; | |
2117 | } | |
2118 | EXPORT_SYMBOL(locks_lock_inode_wait); | |
2119 | ||
2120 | /** | |
2121 | * sys_flock: - flock() system call. | |
2122 | * @fd: the file descriptor to lock. | |
2123 | * @cmd: the type of lock to apply. | |
2124 | * | |
2125 | * Apply a %FL_FLOCK style lock to an open file descriptor. | |
2126 | * The @cmd can be one of: | |
2127 | * | |
2128 | * - %LOCK_SH -- a shared lock. | |
2129 | * - %LOCK_EX -- an exclusive lock. | |
2130 | * - %LOCK_UN -- remove an existing lock. | |
2131 | * - %LOCK_MAND -- a 'mandatory' flock. (DEPRECATED) | |
2132 | * | |
2133 | * %LOCK_MAND support has been removed from the kernel. | |
2134 | */ | |
2135 | SYSCALL_DEFINE2(flock, unsigned int, fd, unsigned int, cmd) | |
2136 | { | |
2137 | int can_sleep, error, type; | |
2138 | struct file_lock fl; | |
2139 | struct fd f; | |
2140 | ||
2141 | /* | |
2142 | * LOCK_MAND locks were broken for a long time in that they never | |
2143 | * conflicted with one another and didn't prevent any sort of open, | |
2144 | * read or write activity. | |
2145 | * | |
2146 | * Just ignore these requests now, to preserve legacy behavior, but | |
2147 | * throw a warning to let people know that they don't actually work. | |
2148 | */ | |
2149 | if (cmd & LOCK_MAND) { | |
2150 | pr_warn_once("%s(%d): Attempt to set a LOCK_MAND lock via flock(2). This support has been removed and the request ignored.\n", current->comm, current->pid); | |
2151 | return 0; | |
2152 | } | |
2153 | ||
2154 | type = flock_translate_cmd(cmd & ~LOCK_NB); | |
2155 | if (type < 0) | |
2156 | return type; | |
2157 | ||
2158 | error = -EBADF; | |
2159 | f = fdget(fd); | |
2160 | if (!fd_file(f)) | |
2161 | return error; | |
2162 | ||
2163 | if (type != F_UNLCK && !(fd_file(f)->f_mode & (FMODE_READ | FMODE_WRITE))) | |
2164 | goto out_putf; | |
2165 | ||
2166 | flock_make_lock(fd_file(f), &fl, type); | |
2167 | ||
2168 | error = security_file_lock(fd_file(f), fl.c.flc_type); | |
2169 | if (error) | |
2170 | goto out_putf; | |
2171 | ||
2172 | can_sleep = !(cmd & LOCK_NB); | |
2173 | if (can_sleep) | |
2174 | fl.c.flc_flags |= FL_SLEEP; | |
2175 | ||
2176 | if (fd_file(f)->f_op->flock) | |
2177 | error = fd_file(f)->f_op->flock(fd_file(f), | |
2178 | (can_sleep) ? F_SETLKW : F_SETLK, | |
2179 | &fl); | |
2180 | else | |
2181 | error = locks_lock_file_wait(fd_file(f), &fl); | |
2182 | ||
2183 | locks_release_private(&fl); | |
2184 | out_putf: | |
2185 | fdput(f); | |
2186 | ||
2187 | return error; | |
2188 | } | |
2189 | ||
2190 | /** | |
2191 | * vfs_test_lock - test file byte range lock | |
2192 | * @filp: The file to test lock for | |
2193 | * @fl: The lock to test; also used to hold result | |
2194 | * | |
2195 | * Returns -ERRNO on failure. Indicates presence of conflicting lock by | |
2196 | * setting conf->fl_type to something other than F_UNLCK. | |
2197 | */ | |
2198 | int vfs_test_lock(struct file *filp, struct file_lock *fl) | |
2199 | { | |
2200 | WARN_ON_ONCE(filp != fl->c.flc_file); | |
2201 | if (filp->f_op->lock) | |
2202 | return filp->f_op->lock(filp, F_GETLK, fl); | |
2203 | posix_test_lock(filp, fl); | |
2204 | return 0; | |
2205 | } | |
2206 | EXPORT_SYMBOL_GPL(vfs_test_lock); | |
2207 | ||
2208 | /** | |
2209 | * locks_translate_pid - translate a file_lock's fl_pid number into a namespace | |
2210 | * @fl: The file_lock who's fl_pid should be translated | |
2211 | * @ns: The namespace into which the pid should be translated | |
2212 | * | |
2213 | * Used to translate a fl_pid into a namespace virtual pid number | |
2214 | */ | |
2215 | static pid_t locks_translate_pid(struct file_lock_core *fl, struct pid_namespace *ns) | |
2216 | { | |
2217 | pid_t vnr; | |
2218 | struct pid *pid; | |
2219 | ||
2220 | if (fl->flc_flags & FL_OFDLCK) | |
2221 | return -1; | |
2222 | ||
2223 | /* Remote locks report a negative pid value */ | |
2224 | if (fl->flc_pid <= 0) | |
2225 | return fl->flc_pid; | |
2226 | ||
2227 | /* | |
2228 | * If the flock owner process is dead and its pid has been already | |
2229 | * freed, the translation below won't work, but we still want to show | |
2230 | * flock owner pid number in init pidns. | |
2231 | */ | |
2232 | if (ns == &init_pid_ns) | |
2233 | return (pid_t) fl->flc_pid; | |
2234 | ||
2235 | rcu_read_lock(); | |
2236 | pid = find_pid_ns(fl->flc_pid, &init_pid_ns); | |
2237 | vnr = pid_nr_ns(pid, ns); | |
2238 | rcu_read_unlock(); | |
2239 | return vnr; | |
2240 | } | |
2241 | ||
2242 | static int posix_lock_to_flock(struct flock *flock, struct file_lock *fl) | |
2243 | { | |
2244 | flock->l_pid = locks_translate_pid(&fl->c, task_active_pid_ns(current)); | |
2245 | #if BITS_PER_LONG == 32 | |
2246 | /* | |
2247 | * Make sure we can represent the posix lock via | |
2248 | * legacy 32bit flock. | |
2249 | */ | |
2250 | if (fl->fl_start > OFFT_OFFSET_MAX) | |
2251 | return -EOVERFLOW; | |
2252 | if (fl->fl_end != OFFSET_MAX && fl->fl_end > OFFT_OFFSET_MAX) | |
2253 | return -EOVERFLOW; | |
2254 | #endif | |
2255 | flock->l_start = fl->fl_start; | |
2256 | flock->l_len = fl->fl_end == OFFSET_MAX ? 0 : | |
2257 | fl->fl_end - fl->fl_start + 1; | |
2258 | flock->l_whence = 0; | |
2259 | flock->l_type = fl->c.flc_type; | |
2260 | return 0; | |
2261 | } | |
2262 | ||
2263 | #if BITS_PER_LONG == 32 | |
2264 | static void posix_lock_to_flock64(struct flock64 *flock, struct file_lock *fl) | |
2265 | { | |
2266 | flock->l_pid = locks_translate_pid(&fl->c, task_active_pid_ns(current)); | |
2267 | flock->l_start = fl->fl_start; | |
2268 | flock->l_len = fl->fl_end == OFFSET_MAX ? 0 : | |
2269 | fl->fl_end - fl->fl_start + 1; | |
2270 | flock->l_whence = 0; | |
2271 | flock->l_type = fl->c.flc_type; | |
2272 | } | |
2273 | #endif | |
2274 | ||
2275 | /* Report the first existing lock that would conflict with l. | |
2276 | * This implements the F_GETLK command of fcntl(). | |
2277 | */ | |
2278 | int fcntl_getlk(struct file *filp, unsigned int cmd, struct flock *flock) | |
2279 | { | |
2280 | struct file_lock *fl; | |
2281 | int error; | |
2282 | ||
2283 | fl = locks_alloc_lock(); | |
2284 | if (fl == NULL) | |
2285 | return -ENOMEM; | |
2286 | error = -EINVAL; | |
2287 | if (cmd != F_OFD_GETLK && flock->l_type != F_RDLCK | |
2288 | && flock->l_type != F_WRLCK) | |
2289 | goto out; | |
2290 | ||
2291 | error = flock_to_posix_lock(filp, fl, flock); | |
2292 | if (error) | |
2293 | goto out; | |
2294 | ||
2295 | if (cmd == F_OFD_GETLK) { | |
2296 | error = -EINVAL; | |
2297 | if (flock->l_pid != 0) | |
2298 | goto out; | |
2299 | ||
2300 | fl->c.flc_flags |= FL_OFDLCK; | |
2301 | fl->c.flc_owner = filp; | |
2302 | } | |
2303 | ||
2304 | error = vfs_test_lock(filp, fl); | |
2305 | if (error) | |
2306 | goto out; | |
2307 | ||
2308 | flock->l_type = fl->c.flc_type; | |
2309 | if (fl->c.flc_type != F_UNLCK) { | |
2310 | error = posix_lock_to_flock(flock, fl); | |
2311 | if (error) | |
2312 | goto out; | |
2313 | } | |
2314 | out: | |
2315 | locks_free_lock(fl); | |
2316 | return error; | |
2317 | } | |
2318 | ||
2319 | /** | |
2320 | * vfs_lock_file - file byte range lock | |
2321 | * @filp: The file to apply the lock to | |
2322 | * @cmd: type of locking operation (F_SETLK, F_GETLK, etc.) | |
2323 | * @fl: The lock to be applied | |
2324 | * @conf: Place to return a copy of the conflicting lock, if found. | |
2325 | * | |
2326 | * A caller that doesn't care about the conflicting lock may pass NULL | |
2327 | * as the final argument. | |
2328 | * | |
2329 | * If the filesystem defines a private ->lock() method, then @conf will | |
2330 | * be left unchanged; so a caller that cares should initialize it to | |
2331 | * some acceptable default. | |
2332 | * | |
2333 | * To avoid blocking kernel daemons, such as lockd, that need to acquire POSIX | |
2334 | * locks, the ->lock() interface may return asynchronously, before the lock has | |
2335 | * been granted or denied by the underlying filesystem, if (and only if) | |
2336 | * lm_grant is set. Additionally EXPORT_OP_ASYNC_LOCK in export_operations | |
2337 | * flags need to be set. | |
2338 | * | |
2339 | * Callers expecting ->lock() to return asynchronously will only use F_SETLK, | |
2340 | * not F_SETLKW; they will set FL_SLEEP if (and only if) the request is for a | |
2341 | * blocking lock. When ->lock() does return asynchronously, it must return | |
2342 | * FILE_LOCK_DEFERRED, and call ->lm_grant() when the lock request completes. | |
2343 | * If the request is for non-blocking lock the file system should return | |
2344 | * FILE_LOCK_DEFERRED then try to get the lock and call the callback routine | |
2345 | * with the result. If the request timed out the callback routine will return a | |
2346 | * nonzero return code and the file system should release the lock. The file | |
2347 | * system is also responsible to keep a corresponding posix lock when it | |
2348 | * grants a lock so the VFS can find out which locks are locally held and do | |
2349 | * the correct lock cleanup when required. | |
2350 | * The underlying filesystem must not drop the kernel lock or call | |
2351 | * ->lm_grant() before returning to the caller with a FILE_LOCK_DEFERRED | |
2352 | * return code. | |
2353 | */ | |
2354 | int vfs_lock_file(struct file *filp, unsigned int cmd, struct file_lock *fl, struct file_lock *conf) | |
2355 | { | |
2356 | WARN_ON_ONCE(filp != fl->c.flc_file); | |
2357 | if (filp->f_op->lock) | |
2358 | return filp->f_op->lock(filp, cmd, fl); | |
2359 | else | |
2360 | return posix_lock_file(filp, fl, conf); | |
2361 | } | |
2362 | EXPORT_SYMBOL_GPL(vfs_lock_file); | |
2363 | ||
2364 | static int do_lock_file_wait(struct file *filp, unsigned int cmd, | |
2365 | struct file_lock *fl) | |
2366 | { | |
2367 | int error; | |
2368 | ||
2369 | error = security_file_lock(filp, fl->c.flc_type); | |
2370 | if (error) | |
2371 | return error; | |
2372 | ||
2373 | for (;;) { | |
2374 | error = vfs_lock_file(filp, cmd, fl, NULL); | |
2375 | if (error != FILE_LOCK_DEFERRED) | |
2376 | break; | |
2377 | error = wait_event_interruptible(fl->c.flc_wait, | |
2378 | list_empty(&fl->c.flc_blocked_member)); | |
2379 | if (error) | |
2380 | break; | |
2381 | } | |
2382 | locks_delete_block(fl); | |
2383 | ||
2384 | return error; | |
2385 | } | |
2386 | ||
2387 | /* Ensure that fl->fl_file has compatible f_mode for F_SETLK calls */ | |
2388 | static int | |
2389 | check_fmode_for_setlk(struct file_lock *fl) | |
2390 | { | |
2391 | switch (fl->c.flc_type) { | |
2392 | case F_RDLCK: | |
2393 | if (!(fl->c.flc_file->f_mode & FMODE_READ)) | |
2394 | return -EBADF; | |
2395 | break; | |
2396 | case F_WRLCK: | |
2397 | if (!(fl->c.flc_file->f_mode & FMODE_WRITE)) | |
2398 | return -EBADF; | |
2399 | } | |
2400 | return 0; | |
2401 | } | |
2402 | ||
2403 | /* Apply the lock described by l to an open file descriptor. | |
2404 | * This implements both the F_SETLK and F_SETLKW commands of fcntl(). | |
2405 | */ | |
2406 | int fcntl_setlk(unsigned int fd, struct file *filp, unsigned int cmd, | |
2407 | struct flock *flock) | |
2408 | { | |
2409 | struct file_lock *file_lock = locks_alloc_lock(); | |
2410 | struct inode *inode = file_inode(filp); | |
2411 | struct file *f; | |
2412 | int error; | |
2413 | ||
2414 | if (file_lock == NULL) | |
2415 | return -ENOLCK; | |
2416 | ||
2417 | error = flock_to_posix_lock(filp, file_lock, flock); | |
2418 | if (error) | |
2419 | goto out; | |
2420 | ||
2421 | error = check_fmode_for_setlk(file_lock); | |
2422 | if (error) | |
2423 | goto out; | |
2424 | ||
2425 | /* | |
2426 | * If the cmd is requesting file-private locks, then set the | |
2427 | * FL_OFDLCK flag and override the owner. | |
2428 | */ | |
2429 | switch (cmd) { | |
2430 | case F_OFD_SETLK: | |
2431 | error = -EINVAL; | |
2432 | if (flock->l_pid != 0) | |
2433 | goto out; | |
2434 | ||
2435 | cmd = F_SETLK; | |
2436 | file_lock->c.flc_flags |= FL_OFDLCK; | |
2437 | file_lock->c.flc_owner = filp; | |
2438 | break; | |
2439 | case F_OFD_SETLKW: | |
2440 | error = -EINVAL; | |
2441 | if (flock->l_pid != 0) | |
2442 | goto out; | |
2443 | ||
2444 | cmd = F_SETLKW; | |
2445 | file_lock->c.flc_flags |= FL_OFDLCK; | |
2446 | file_lock->c.flc_owner = filp; | |
2447 | fallthrough; | |
2448 | case F_SETLKW: | |
2449 | file_lock->c.flc_flags |= FL_SLEEP; | |
2450 | } | |
2451 | ||
2452 | error = do_lock_file_wait(filp, cmd, file_lock); | |
2453 | ||
2454 | /* | |
2455 | * Detect close/fcntl races and recover by zapping all POSIX locks | |
2456 | * associated with this file and our files_struct, just like on | |
2457 | * filp_flush(). There is no need to do that when we're | |
2458 | * unlocking though, or for OFD locks. | |
2459 | */ | |
2460 | if (!error && file_lock->c.flc_type != F_UNLCK && | |
2461 | !(file_lock->c.flc_flags & FL_OFDLCK)) { | |
2462 | struct files_struct *files = current->files; | |
2463 | /* | |
2464 | * We need that spin_lock here - it prevents reordering between | |
2465 | * update of i_flctx->flc_posix and check for it done in | |
2466 | * close(). rcu_read_lock() wouldn't do. | |
2467 | */ | |
2468 | spin_lock(&files->file_lock); | |
2469 | f = files_lookup_fd_locked(files, fd); | |
2470 | spin_unlock(&files->file_lock); | |
2471 | if (f != filp) { | |
2472 | locks_remove_posix(filp, files); | |
2473 | error = -EBADF; | |
2474 | } | |
2475 | } | |
2476 | out: | |
2477 | trace_fcntl_setlk(inode, file_lock, error); | |
2478 | locks_free_lock(file_lock); | |
2479 | return error; | |
2480 | } | |
2481 | ||
2482 | #if BITS_PER_LONG == 32 | |
2483 | /* Report the first existing lock that would conflict with l. | |
2484 | * This implements the F_GETLK command of fcntl(). | |
2485 | */ | |
2486 | int fcntl_getlk64(struct file *filp, unsigned int cmd, struct flock64 *flock) | |
2487 | { | |
2488 | struct file_lock *fl; | |
2489 | int error; | |
2490 | ||
2491 | fl = locks_alloc_lock(); | |
2492 | if (fl == NULL) | |
2493 | return -ENOMEM; | |
2494 | ||
2495 | error = -EINVAL; | |
2496 | if (cmd != F_OFD_GETLK && flock->l_type != F_RDLCK | |
2497 | && flock->l_type != F_WRLCK) | |
2498 | goto out; | |
2499 | ||
2500 | error = flock64_to_posix_lock(filp, fl, flock); | |
2501 | if (error) | |
2502 | goto out; | |
2503 | ||
2504 | if (cmd == F_OFD_GETLK) { | |
2505 | error = -EINVAL; | |
2506 | if (flock->l_pid != 0) | |
2507 | goto out; | |
2508 | ||
2509 | fl->c.flc_flags |= FL_OFDLCK; | |
2510 | fl->c.flc_owner = filp; | |
2511 | } | |
2512 | ||
2513 | error = vfs_test_lock(filp, fl); | |
2514 | if (error) | |
2515 | goto out; | |
2516 | ||
2517 | flock->l_type = fl->c.flc_type; | |
2518 | if (fl->c.flc_type != F_UNLCK) | |
2519 | posix_lock_to_flock64(flock, fl); | |
2520 | ||
2521 | out: | |
2522 | locks_free_lock(fl); | |
2523 | return error; | |
2524 | } | |
2525 | ||
2526 | /* Apply the lock described by l to an open file descriptor. | |
2527 | * This implements both the F_SETLK and F_SETLKW commands of fcntl(). | |
2528 | */ | |
2529 | int fcntl_setlk64(unsigned int fd, struct file *filp, unsigned int cmd, | |
2530 | struct flock64 *flock) | |
2531 | { | |
2532 | struct file_lock *file_lock = locks_alloc_lock(); | |
2533 | struct file *f; | |
2534 | int error; | |
2535 | ||
2536 | if (file_lock == NULL) | |
2537 | return -ENOLCK; | |
2538 | ||
2539 | error = flock64_to_posix_lock(filp, file_lock, flock); | |
2540 | if (error) | |
2541 | goto out; | |
2542 | ||
2543 | error = check_fmode_for_setlk(file_lock); | |
2544 | if (error) | |
2545 | goto out; | |
2546 | ||
2547 | /* | |
2548 | * If the cmd is requesting file-private locks, then set the | |
2549 | * FL_OFDLCK flag and override the owner. | |
2550 | */ | |
2551 | switch (cmd) { | |
2552 | case F_OFD_SETLK: | |
2553 | error = -EINVAL; | |
2554 | if (flock->l_pid != 0) | |
2555 | goto out; | |
2556 | ||
2557 | cmd = F_SETLK64; | |
2558 | file_lock->c.flc_flags |= FL_OFDLCK; | |
2559 | file_lock->c.flc_owner = filp; | |
2560 | break; | |
2561 | case F_OFD_SETLKW: | |
2562 | error = -EINVAL; | |
2563 | if (flock->l_pid != 0) | |
2564 | goto out; | |
2565 | ||
2566 | cmd = F_SETLKW64; | |
2567 | file_lock->c.flc_flags |= FL_OFDLCK; | |
2568 | file_lock->c.flc_owner = filp; | |
2569 | fallthrough; | |
2570 | case F_SETLKW64: | |
2571 | file_lock->c.flc_flags |= FL_SLEEP; | |
2572 | } | |
2573 | ||
2574 | error = do_lock_file_wait(filp, cmd, file_lock); | |
2575 | ||
2576 | /* | |
2577 | * Detect close/fcntl races and recover by zapping all POSIX locks | |
2578 | * associated with this file and our files_struct, just like on | |
2579 | * filp_flush(). There is no need to do that when we're | |
2580 | * unlocking though, or for OFD locks. | |
2581 | */ | |
2582 | if (!error && file_lock->c.flc_type != F_UNLCK && | |
2583 | !(file_lock->c.flc_flags & FL_OFDLCK)) { | |
2584 | struct files_struct *files = current->files; | |
2585 | /* | |
2586 | * We need that spin_lock here - it prevents reordering between | |
2587 | * update of i_flctx->flc_posix and check for it done in | |
2588 | * close(). rcu_read_lock() wouldn't do. | |
2589 | */ | |
2590 | spin_lock(&files->file_lock); | |
2591 | f = files_lookup_fd_locked(files, fd); | |
2592 | spin_unlock(&files->file_lock); | |
2593 | if (f != filp) { | |
2594 | locks_remove_posix(filp, files); | |
2595 | error = -EBADF; | |
2596 | } | |
2597 | } | |
2598 | out: | |
2599 | locks_free_lock(file_lock); | |
2600 | return error; | |
2601 | } | |
2602 | #endif /* BITS_PER_LONG == 32 */ | |
2603 | ||
2604 | /* | |
2605 | * This function is called when the file is being removed | |
2606 | * from the task's fd array. POSIX locks belonging to this task | |
2607 | * are deleted at this time. | |
2608 | */ | |
2609 | void locks_remove_posix(struct file *filp, fl_owner_t owner) | |
2610 | { | |
2611 | int error; | |
2612 | struct inode *inode = file_inode(filp); | |
2613 | struct file_lock lock; | |
2614 | struct file_lock_context *ctx; | |
2615 | ||
2616 | /* | |
2617 | * If there are no locks held on this file, we don't need to call | |
2618 | * posix_lock_file(). Another process could be setting a lock on this | |
2619 | * file at the same time, but we wouldn't remove that lock anyway. | |
2620 | */ | |
2621 | ctx = locks_inode_context(inode); | |
2622 | if (!ctx || list_empty(&ctx->flc_posix)) | |
2623 | return; | |
2624 | ||
2625 | locks_init_lock(&lock); | |
2626 | lock.c.flc_type = F_UNLCK; | |
2627 | lock.c.flc_flags = FL_POSIX | FL_CLOSE; | |
2628 | lock.fl_start = 0; | |
2629 | lock.fl_end = OFFSET_MAX; | |
2630 | lock.c.flc_owner = owner; | |
2631 | lock.c.flc_pid = current->tgid; | |
2632 | lock.c.flc_file = filp; | |
2633 | lock.fl_ops = NULL; | |
2634 | lock.fl_lmops = NULL; | |
2635 | ||
2636 | error = vfs_lock_file(filp, F_SETLK, &lock, NULL); | |
2637 | ||
2638 | if (lock.fl_ops && lock.fl_ops->fl_release_private) | |
2639 | lock.fl_ops->fl_release_private(&lock); | |
2640 | trace_locks_remove_posix(inode, &lock, error); | |
2641 | } | |
2642 | EXPORT_SYMBOL(locks_remove_posix); | |
2643 | ||
2644 | /* The i_flctx must be valid when calling into here */ | |
2645 | static void | |
2646 | locks_remove_flock(struct file *filp, struct file_lock_context *flctx) | |
2647 | { | |
2648 | struct file_lock fl; | |
2649 | struct inode *inode = file_inode(filp); | |
2650 | ||
2651 | if (list_empty(&flctx->flc_flock)) | |
2652 | return; | |
2653 | ||
2654 | flock_make_lock(filp, &fl, F_UNLCK); | |
2655 | fl.c.flc_flags |= FL_CLOSE; | |
2656 | ||
2657 | if (filp->f_op->flock) | |
2658 | filp->f_op->flock(filp, F_SETLKW, &fl); | |
2659 | else | |
2660 | flock_lock_inode(inode, &fl); | |
2661 | ||
2662 | if (fl.fl_ops && fl.fl_ops->fl_release_private) | |
2663 | fl.fl_ops->fl_release_private(&fl); | |
2664 | } | |
2665 | ||
2666 | /* The i_flctx must be valid when calling into here */ | |
2667 | static void | |
2668 | locks_remove_lease(struct file *filp, struct file_lock_context *ctx) | |
2669 | { | |
2670 | struct file_lease *fl, *tmp; | |
2671 | LIST_HEAD(dispose); | |
2672 | ||
2673 | if (list_empty(&ctx->flc_lease)) | |
2674 | return; | |
2675 | ||
2676 | percpu_down_read(&file_rwsem); | |
2677 | spin_lock(&ctx->flc_lock); | |
2678 | list_for_each_entry_safe(fl, tmp, &ctx->flc_lease, c.flc_list) | |
2679 | if (filp == fl->c.flc_file) | |
2680 | lease_modify(fl, F_UNLCK, &dispose); | |
2681 | spin_unlock(&ctx->flc_lock); | |
2682 | percpu_up_read(&file_rwsem); | |
2683 | ||
2684 | locks_dispose_list(&dispose); | |
2685 | } | |
2686 | ||
2687 | /* | |
2688 | * This function is called on the last close of an open file. | |
2689 | */ | |
2690 | void locks_remove_file(struct file *filp) | |
2691 | { | |
2692 | struct file_lock_context *ctx; | |
2693 | ||
2694 | ctx = locks_inode_context(file_inode(filp)); | |
2695 | if (!ctx) | |
2696 | return; | |
2697 | ||
2698 | /* remove any OFD locks */ | |
2699 | locks_remove_posix(filp, filp); | |
2700 | ||
2701 | /* remove flock locks */ | |
2702 | locks_remove_flock(filp, ctx); | |
2703 | ||
2704 | /* remove any leases */ | |
2705 | locks_remove_lease(filp, ctx); | |
2706 | ||
2707 | spin_lock(&ctx->flc_lock); | |
2708 | locks_check_ctx_file_list(filp, &ctx->flc_posix, "POSIX"); | |
2709 | locks_check_ctx_file_list(filp, &ctx->flc_flock, "FLOCK"); | |
2710 | locks_check_ctx_file_list(filp, &ctx->flc_lease, "LEASE"); | |
2711 | spin_unlock(&ctx->flc_lock); | |
2712 | } | |
2713 | ||
2714 | /** | |
2715 | * vfs_cancel_lock - file byte range unblock lock | |
2716 | * @filp: The file to apply the unblock to | |
2717 | * @fl: The lock to be unblocked | |
2718 | * | |
2719 | * Used by lock managers to cancel blocked requests | |
2720 | */ | |
2721 | int vfs_cancel_lock(struct file *filp, struct file_lock *fl) | |
2722 | { | |
2723 | WARN_ON_ONCE(filp != fl->c.flc_file); | |
2724 | if (filp->f_op->lock) | |
2725 | return filp->f_op->lock(filp, F_CANCELLK, fl); | |
2726 | return 0; | |
2727 | } | |
2728 | EXPORT_SYMBOL_GPL(vfs_cancel_lock); | |
2729 | ||
2730 | /** | |
2731 | * vfs_inode_has_locks - are any file locks held on @inode? | |
2732 | * @inode: inode to check for locks | |
2733 | * | |
2734 | * Return true if there are any FL_POSIX or FL_FLOCK locks currently | |
2735 | * set on @inode. | |
2736 | */ | |
2737 | bool vfs_inode_has_locks(struct inode *inode) | |
2738 | { | |
2739 | struct file_lock_context *ctx; | |
2740 | bool ret; | |
2741 | ||
2742 | ctx = locks_inode_context(inode); | |
2743 | if (!ctx) | |
2744 | return false; | |
2745 | ||
2746 | spin_lock(&ctx->flc_lock); | |
2747 | ret = !list_empty(&ctx->flc_posix) || !list_empty(&ctx->flc_flock); | |
2748 | spin_unlock(&ctx->flc_lock); | |
2749 | return ret; | |
2750 | } | |
2751 | EXPORT_SYMBOL_GPL(vfs_inode_has_locks); | |
2752 | ||
2753 | #ifdef CONFIG_PROC_FS | |
2754 | #include <linux/proc_fs.h> | |
2755 | #include <linux/seq_file.h> | |
2756 | ||
2757 | struct locks_iterator { | |
2758 | int li_cpu; | |
2759 | loff_t li_pos; | |
2760 | }; | |
2761 | ||
2762 | static void lock_get_status(struct seq_file *f, struct file_lock_core *flc, | |
2763 | loff_t id, char *pfx, int repeat) | |
2764 | { | |
2765 | struct inode *inode = NULL; | |
2766 | unsigned int pid; | |
2767 | struct pid_namespace *proc_pidns = proc_pid_ns(file_inode(f->file)->i_sb); | |
2768 | int type = flc->flc_type; | |
2769 | struct file_lock *fl = file_lock(flc); | |
2770 | ||
2771 | pid = locks_translate_pid(flc, proc_pidns); | |
2772 | ||
2773 | /* | |
2774 | * If lock owner is dead (and pid is freed) or not visible in current | |
2775 | * pidns, zero is shown as a pid value. Check lock info from | |
2776 | * init_pid_ns to get saved lock pid value. | |
2777 | */ | |
2778 | if (flc->flc_file != NULL) | |
2779 | inode = file_inode(flc->flc_file); | |
2780 | ||
2781 | seq_printf(f, "%lld: ", id); | |
2782 | ||
2783 | if (repeat) | |
2784 | seq_printf(f, "%*s", repeat - 1 + (int)strlen(pfx), pfx); | |
2785 | ||
2786 | if (flc->flc_flags & FL_POSIX) { | |
2787 | if (flc->flc_flags & FL_ACCESS) | |
2788 | seq_puts(f, "ACCESS"); | |
2789 | else if (flc->flc_flags & FL_OFDLCK) | |
2790 | seq_puts(f, "OFDLCK"); | |
2791 | else | |
2792 | seq_puts(f, "POSIX "); | |
2793 | ||
2794 | seq_printf(f, " %s ", | |
2795 | (inode == NULL) ? "*NOINODE*" : "ADVISORY "); | |
2796 | } else if (flc->flc_flags & FL_FLOCK) { | |
2797 | seq_puts(f, "FLOCK ADVISORY "); | |
2798 | } else if (flc->flc_flags & (FL_LEASE|FL_DELEG|FL_LAYOUT)) { | |
2799 | struct file_lease *lease = file_lease(flc); | |
2800 | ||
2801 | type = target_leasetype(lease); | |
2802 | ||
2803 | if (flc->flc_flags & FL_DELEG) | |
2804 | seq_puts(f, "DELEG "); | |
2805 | else | |
2806 | seq_puts(f, "LEASE "); | |
2807 | ||
2808 | if (lease_breaking(lease)) | |
2809 | seq_puts(f, "BREAKING "); | |
2810 | else if (flc->flc_file) | |
2811 | seq_puts(f, "ACTIVE "); | |
2812 | else | |
2813 | seq_puts(f, "BREAKER "); | |
2814 | } else { | |
2815 | seq_puts(f, "UNKNOWN UNKNOWN "); | |
2816 | } | |
2817 | ||
2818 | seq_printf(f, "%s ", (type == F_WRLCK) ? "WRITE" : | |
2819 | (type == F_RDLCK) ? "READ" : "UNLCK"); | |
2820 | if (inode) { | |
2821 | /* userspace relies on this representation of dev_t */ | |
2822 | seq_printf(f, "%d %02x:%02x:%lu ", pid, | |
2823 | MAJOR(inode->i_sb->s_dev), | |
2824 | MINOR(inode->i_sb->s_dev), inode->i_ino); | |
2825 | } else { | |
2826 | seq_printf(f, "%d <none>:0 ", pid); | |
2827 | } | |
2828 | if (flc->flc_flags & FL_POSIX) { | |
2829 | if (fl->fl_end == OFFSET_MAX) | |
2830 | seq_printf(f, "%Ld EOF\n", fl->fl_start); | |
2831 | else | |
2832 | seq_printf(f, "%Ld %Ld\n", fl->fl_start, fl->fl_end); | |
2833 | } else { | |
2834 | seq_puts(f, "0 EOF\n"); | |
2835 | } | |
2836 | } | |
2837 | ||
2838 | static struct file_lock_core *get_next_blocked_member(struct file_lock_core *node) | |
2839 | { | |
2840 | struct file_lock_core *tmp; | |
2841 | ||
2842 | /* NULL node or root node */ | |
2843 | if (node == NULL || node->flc_blocker == NULL) | |
2844 | return NULL; | |
2845 | ||
2846 | /* Next member in the linked list could be itself */ | |
2847 | tmp = list_next_entry(node, flc_blocked_member); | |
2848 | if (list_entry_is_head(tmp, &node->flc_blocker->flc_blocked_requests, | |
2849 | flc_blocked_member) | |
2850 | || tmp == node) { | |
2851 | return NULL; | |
2852 | } | |
2853 | ||
2854 | return tmp; | |
2855 | } | |
2856 | ||
2857 | static int locks_show(struct seq_file *f, void *v) | |
2858 | { | |
2859 | struct locks_iterator *iter = f->private; | |
2860 | struct file_lock_core *cur, *tmp; | |
2861 | struct pid_namespace *proc_pidns = proc_pid_ns(file_inode(f->file)->i_sb); | |
2862 | int level = 0; | |
2863 | ||
2864 | cur = hlist_entry(v, struct file_lock_core, flc_link); | |
2865 | ||
2866 | if (locks_translate_pid(cur, proc_pidns) == 0) | |
2867 | return 0; | |
2868 | ||
2869 | /* View this crossed linked list as a binary tree, the first member of flc_blocked_requests | |
2870 | * is the left child of current node, the next silibing in flc_blocked_member is the | |
2871 | * right child, we can alse get the parent of current node from flc_blocker, so this | |
2872 | * question becomes traversal of a binary tree | |
2873 | */ | |
2874 | while (cur != NULL) { | |
2875 | if (level) | |
2876 | lock_get_status(f, cur, iter->li_pos, "-> ", level); | |
2877 | else | |
2878 | lock_get_status(f, cur, iter->li_pos, "", level); | |
2879 | ||
2880 | if (!list_empty(&cur->flc_blocked_requests)) { | |
2881 | /* Turn left */ | |
2882 | cur = list_first_entry_or_null(&cur->flc_blocked_requests, | |
2883 | struct file_lock_core, | |
2884 | flc_blocked_member); | |
2885 | level++; | |
2886 | } else { | |
2887 | /* Turn right */ | |
2888 | tmp = get_next_blocked_member(cur); | |
2889 | /* Fall back to parent node */ | |
2890 | while (tmp == NULL && cur->flc_blocker != NULL) { | |
2891 | cur = cur->flc_blocker; | |
2892 | level--; | |
2893 | tmp = get_next_blocked_member(cur); | |
2894 | } | |
2895 | cur = tmp; | |
2896 | } | |
2897 | } | |
2898 | ||
2899 | return 0; | |
2900 | } | |
2901 | ||
2902 | static void __show_fd_locks(struct seq_file *f, | |
2903 | struct list_head *head, int *id, | |
2904 | struct file *filp, struct files_struct *files) | |
2905 | { | |
2906 | struct file_lock_core *fl; | |
2907 | ||
2908 | list_for_each_entry(fl, head, flc_list) { | |
2909 | ||
2910 | if (filp != fl->flc_file) | |
2911 | continue; | |
2912 | if (fl->flc_owner != files && fl->flc_owner != filp) | |
2913 | continue; | |
2914 | ||
2915 | (*id)++; | |
2916 | seq_puts(f, "lock:\t"); | |
2917 | lock_get_status(f, fl, *id, "", 0); | |
2918 | } | |
2919 | } | |
2920 | ||
2921 | void show_fd_locks(struct seq_file *f, | |
2922 | struct file *filp, struct files_struct *files) | |
2923 | { | |
2924 | struct inode *inode = file_inode(filp); | |
2925 | struct file_lock_context *ctx; | |
2926 | int id = 0; | |
2927 | ||
2928 | ctx = locks_inode_context(inode); | |
2929 | if (!ctx) | |
2930 | return; | |
2931 | ||
2932 | spin_lock(&ctx->flc_lock); | |
2933 | __show_fd_locks(f, &ctx->flc_flock, &id, filp, files); | |
2934 | __show_fd_locks(f, &ctx->flc_posix, &id, filp, files); | |
2935 | __show_fd_locks(f, &ctx->flc_lease, &id, filp, files); | |
2936 | spin_unlock(&ctx->flc_lock); | |
2937 | } | |
2938 | ||
2939 | static void *locks_start(struct seq_file *f, loff_t *pos) | |
2940 | __acquires(&blocked_lock_lock) | |
2941 | { | |
2942 | struct locks_iterator *iter = f->private; | |
2943 | ||
2944 | iter->li_pos = *pos + 1; | |
2945 | percpu_down_write(&file_rwsem); | |
2946 | spin_lock(&blocked_lock_lock); | |
2947 | return seq_hlist_start_percpu(&file_lock_list.hlist, &iter->li_cpu, *pos); | |
2948 | } | |
2949 | ||
2950 | static void *locks_next(struct seq_file *f, void *v, loff_t *pos) | |
2951 | { | |
2952 | struct locks_iterator *iter = f->private; | |
2953 | ||
2954 | ++iter->li_pos; | |
2955 | return seq_hlist_next_percpu(v, &file_lock_list.hlist, &iter->li_cpu, pos); | |
2956 | } | |
2957 | ||
2958 | static void locks_stop(struct seq_file *f, void *v) | |
2959 | __releases(&blocked_lock_lock) | |
2960 | { | |
2961 | spin_unlock(&blocked_lock_lock); | |
2962 | percpu_up_write(&file_rwsem); | |
2963 | } | |
2964 | ||
2965 | static const struct seq_operations locks_seq_operations = { | |
2966 | .start = locks_start, | |
2967 | .next = locks_next, | |
2968 | .stop = locks_stop, | |
2969 | .show = locks_show, | |
2970 | }; | |
2971 | ||
2972 | static int __init proc_locks_init(void) | |
2973 | { | |
2974 | proc_create_seq_private("locks", 0, NULL, &locks_seq_operations, | |
2975 | sizeof(struct locks_iterator), NULL); | |
2976 | return 0; | |
2977 | } | |
2978 | fs_initcall(proc_locks_init); | |
2979 | #endif | |
2980 | ||
2981 | static int __init filelock_init(void) | |
2982 | { | |
2983 | int i; | |
2984 | ||
2985 | flctx_cache = kmem_cache_create("file_lock_ctx", | |
2986 | sizeof(struct file_lock_context), 0, SLAB_PANIC, NULL); | |
2987 | ||
2988 | filelock_cache = kmem_cache_create("file_lock_cache", | |
2989 | sizeof(struct file_lock), 0, SLAB_PANIC, NULL); | |
2990 | ||
2991 | filelease_cache = kmem_cache_create("file_lease_cache", | |
2992 | sizeof(struct file_lease), 0, SLAB_PANIC, NULL); | |
2993 | ||
2994 | for_each_possible_cpu(i) { | |
2995 | struct file_lock_list_struct *fll = per_cpu_ptr(&file_lock_list, i); | |
2996 | ||
2997 | spin_lock_init(&fll->lock); | |
2998 | INIT_HLIST_HEAD(&fll->hlist); | |
2999 | } | |
3000 | ||
3001 | lease_notifier_chain_init(); | |
3002 | return 0; | |
3003 | } | |
3004 | core_initcall(filelock_init); |