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1/*
2 * linux/fs/locks.c
3 *
4 * Provide support for fcntl()'s F_GETLK, F_SETLK, and F_SETLKW calls.
5 * Doug Evans (dje@spiff.uucp), August 07, 1992
6 *
7 * Deadlock detection added.
8 * FIXME: one thing isn't handled yet:
9 * - mandatory locks (requires lots of changes elsewhere)
10 * Kelly Carmichael (kelly@[142.24.8.65]), September 17, 1994.
11 *
12 * Miscellaneous edits, and a total rewrite of posix_lock_file() code.
13 * Kai Petzke (wpp@marie.physik.tu-berlin.de), 1994
14 *
15 * Converted file_lock_table to a linked list from an array, which eliminates
16 * the limits on how many active file locks are open.
17 * Chad Page (pageone@netcom.com), November 27, 1994
18 *
19 * Removed dependency on file descriptors. dup()'ed file descriptors now
20 * get the same locks as the original file descriptors, and a close() on
21 * any file descriptor removes ALL the locks on the file for the current
22 * process. Since locks still depend on the process id, locks are inherited
23 * after an exec() but not after a fork(). This agrees with POSIX, and both
24 * BSD and SVR4 practice.
25 * Andy Walker (andy@lysaker.kvaerner.no), February 14, 1995
26 *
27 * Scrapped free list which is redundant now that we allocate locks
28 * dynamically with kmalloc()/kfree().
29 * Andy Walker (andy@lysaker.kvaerner.no), February 21, 1995
30 *
31 * Implemented two lock personalities - FL_FLOCK and FL_POSIX.
32 *
33 * FL_POSIX locks are created with calls to fcntl() and lockf() through the
34 * fcntl() system call. They have the semantics described above.
35 *
36 * FL_FLOCK locks are created with calls to flock(), through the flock()
37 * system call, which is new. Old C libraries implement flock() via fcntl()
38 * and will continue to use the old, broken implementation.
39 *
40 * FL_FLOCK locks follow the 4.4 BSD flock() semantics. They are associated
41 * with a file pointer (filp). As a result they can be shared by a parent
42 * process and its children after a fork(). They are removed when the last
43 * file descriptor referring to the file pointer is closed (unless explicitly
44 * unlocked).
45 *
46 * FL_FLOCK locks never deadlock, an existing lock is always removed before
47 * upgrading from shared to exclusive (or vice versa). When this happens
48 * any processes blocked by the current lock are woken up and allowed to
49 * run before the new lock is applied.
50 * Andy Walker (andy@lysaker.kvaerner.no), June 09, 1995
51 *
52 * Removed some race conditions in flock_lock_file(), marked other possible
53 * races. Just grep for FIXME to see them.
54 * Dmitry Gorodchanin (pgmdsg@ibi.com), February 09, 1996.
55 *
56 * Addressed Dmitry's concerns. Deadlock checking no longer recursive.
57 * Lock allocation changed to GFP_ATOMIC as we can't afford to sleep
58 * once we've checked for blocking and deadlocking.
59 * Andy Walker (andy@lysaker.kvaerner.no), April 03, 1996.
60 *
61 * Initial implementation of mandatory locks. SunOS turned out to be
62 * a rotten model, so I implemented the "obvious" semantics.
63 * See 'Documentation/filesystems/mandatory-locking.txt' for details.
64 * Andy Walker (andy@lysaker.kvaerner.no), April 06, 1996.
65 *
66 * Don't allow mandatory locks on mmap()'ed files. Added simple functions to
67 * check if a file has mandatory locks, used by mmap(), open() and creat() to
68 * see if system call should be rejected. Ref. HP-UX/SunOS/Solaris Reference
69 * Manual, Section 2.
70 * Andy Walker (andy@lysaker.kvaerner.no), April 09, 1996.
71 *
72 * Tidied up block list handling. Added '/proc/locks' interface.
73 * Andy Walker (andy@lysaker.kvaerner.no), April 24, 1996.
74 *
75 * Fixed deadlock condition for pathological code that mixes calls to
76 * flock() and fcntl().
77 * Andy Walker (andy@lysaker.kvaerner.no), April 29, 1996.
78 *
79 * Allow only one type of locking scheme (FL_POSIX or FL_FLOCK) to be in use
80 * for a given file at a time. Changed the CONFIG_LOCK_MANDATORY scheme to
81 * guarantee sensible behaviour in the case where file system modules might
82 * be compiled with different options than the kernel itself.
83 * Andy Walker (andy@lysaker.kvaerner.no), May 15, 1996.
84 *
85 * Added a couple of missing wake_up() calls. Thanks to Thomas Meckel
86 * (Thomas.Meckel@mni.fh-giessen.de) for spotting this.
87 * Andy Walker (andy@lysaker.kvaerner.no), May 15, 1996.
88 *
89 * Changed FL_POSIX locks to use the block list in the same way as FL_FLOCK
90 * locks. Changed process synchronisation to avoid dereferencing locks that
91 * have already been freed.
92 * Andy Walker (andy@lysaker.kvaerner.no), Sep 21, 1996.
93 *
94 * Made the block list a circular list to minimise searching in the list.
95 * Andy Walker (andy@lysaker.kvaerner.no), Sep 25, 1996.
96 *
97 * Made mandatory locking a mount option. Default is not to allow mandatory
98 * locking.
99 * Andy Walker (andy@lysaker.kvaerner.no), Oct 04, 1996.
100 *
101 * Some adaptations for NFS support.
102 * Olaf Kirch (okir@monad.swb.de), Dec 1996,
103 *
104 * Fixed /proc/locks interface so that we can't overrun the buffer we are handed.
105 * Andy Walker (andy@lysaker.kvaerner.no), May 12, 1997.
106 *
107 * Use slab allocator instead of kmalloc/kfree.
108 * Use generic list implementation from <linux/list.h>.
109 * Sped up posix_locks_deadlock by only considering blocked locks.
110 * Matthew Wilcox <willy@debian.org>, March, 2000.
111 *
112 * Leases and LOCK_MAND
113 * Matthew Wilcox <willy@debian.org>, June, 2000.
114 * Stephen Rothwell <sfr@canb.auug.org.au>, June, 2000.
115 */
116
117#include <linux/capability.h>
118#include <linux/file.h>
119#include <linux/fdtable.h>
120#include <linux/fs.h>
121#include <linux/init.h>
122#include <linux/security.h>
123#include <linux/slab.h>
124#include <linux/syscalls.h>
125#include <linux/time.h>
126#include <linux/rcupdate.h>
127#include <linux/pid_namespace.h>
128#include <linux/hashtable.h>
129#include <linux/percpu.h>
130#include <linux/lglock.h>
131
132#define CREATE_TRACE_POINTS
133#include <trace/events/filelock.h>
134
135#include <asm/uaccess.h>
136
137#define IS_POSIX(fl) (fl->fl_flags & FL_POSIX)
138#define IS_FLOCK(fl) (fl->fl_flags & FL_FLOCK)
139#define IS_LEASE(fl) (fl->fl_flags & (FL_LEASE|FL_DELEG|FL_LAYOUT))
140#define IS_OFDLCK(fl) (fl->fl_flags & FL_OFDLCK)
141
142static bool lease_breaking(struct file_lock *fl)
143{
144 return fl->fl_flags & (FL_UNLOCK_PENDING | FL_DOWNGRADE_PENDING);
145}
146
147static int target_leasetype(struct file_lock *fl)
148{
149 if (fl->fl_flags & FL_UNLOCK_PENDING)
150 return F_UNLCK;
151 if (fl->fl_flags & FL_DOWNGRADE_PENDING)
152 return F_RDLCK;
153 return fl->fl_type;
154}
155
156int leases_enable = 1;
157int lease_break_time = 45;
158
159/*
160 * The global file_lock_list is only used for displaying /proc/locks, so we
161 * keep a list on each CPU, with each list protected by its own spinlock via
162 * the file_lock_lglock. Note that alterations to the list also require that
163 * the relevant flc_lock is held.
164 */
165DEFINE_STATIC_LGLOCK(file_lock_lglock);
166static DEFINE_PER_CPU(struct hlist_head, file_lock_list);
167
168/*
169 * The blocked_hash is used to find POSIX lock loops for deadlock detection.
170 * It is protected by blocked_lock_lock.
171 *
172 * We hash locks by lockowner in order to optimize searching for the lock a
173 * particular lockowner is waiting on.
174 *
175 * FIXME: make this value scale via some heuristic? We generally will want more
176 * buckets when we have more lockowners holding locks, but that's a little
177 * difficult to determine without knowing what the workload will look like.
178 */
179#define BLOCKED_HASH_BITS 7
180static DEFINE_HASHTABLE(blocked_hash, BLOCKED_HASH_BITS);
181
182/*
183 * This lock protects the blocked_hash. Generally, if you're accessing it, you
184 * want to be holding this lock.
185 *
186 * In addition, it also protects the fl->fl_block list, and the fl->fl_next
187 * pointer for file_lock structures that are acting as lock requests (in
188 * contrast to those that are acting as records of acquired locks).
189 *
190 * Note that when we acquire this lock in order to change the above fields,
191 * we often hold the flc_lock as well. In certain cases, when reading the fields
192 * protected by this lock, we can skip acquiring it iff we already hold the
193 * flc_lock.
194 *
195 * In particular, adding an entry to the fl_block list requires that you hold
196 * both the flc_lock and the blocked_lock_lock (acquired in that order).
197 * Deleting an entry from the list however only requires the file_lock_lock.
198 */
199static DEFINE_SPINLOCK(blocked_lock_lock);
200
201static struct kmem_cache *flctx_cache __read_mostly;
202static struct kmem_cache *filelock_cache __read_mostly;
203
204static struct file_lock_context *
205locks_get_lock_context(struct inode *inode, int type)
206{
207 struct file_lock_context *ctx;
208
209 /* paired with cmpxchg() below */
210 ctx = smp_load_acquire(&inode->i_flctx);
211 if (likely(ctx) || type == F_UNLCK)
212 goto out;
213
214 ctx = kmem_cache_alloc(flctx_cache, GFP_KERNEL);
215 if (!ctx)
216 goto out;
217
218 spin_lock_init(&ctx->flc_lock);
219 INIT_LIST_HEAD(&ctx->flc_flock);
220 INIT_LIST_HEAD(&ctx->flc_posix);
221 INIT_LIST_HEAD(&ctx->flc_lease);
222
223 /*
224 * Assign the pointer if it's not already assigned. If it is, then
225 * free the context we just allocated.
226 */
227 if (cmpxchg(&inode->i_flctx, NULL, ctx)) {
228 kmem_cache_free(flctx_cache, ctx);
229 ctx = smp_load_acquire(&inode->i_flctx);
230 }
231out:
232 trace_locks_get_lock_context(inode, type, ctx);
233 return ctx;
234}
235
236static void
237locks_dump_ctx_list(struct list_head *list, char *list_type)
238{
239 struct file_lock *fl;
240
241 list_for_each_entry(fl, list, fl_list) {
242 pr_warn("%s: fl_owner=%p fl_flags=0x%x fl_type=0x%x fl_pid=%u\n", list_type, fl->fl_owner, fl->fl_flags, fl->fl_type, fl->fl_pid);
243 }
244}
245
246static void
247locks_check_ctx_lists(struct inode *inode)
248{
249 struct file_lock_context *ctx = inode->i_flctx;
250
251 if (unlikely(!list_empty(&ctx->flc_flock) ||
252 !list_empty(&ctx->flc_posix) ||
253 !list_empty(&ctx->flc_lease))) {
254 pr_warn("Leaked locks on dev=0x%x:0x%x ino=0x%lx:\n",
255 MAJOR(inode->i_sb->s_dev), MINOR(inode->i_sb->s_dev),
256 inode->i_ino);
257 locks_dump_ctx_list(&ctx->flc_flock, "FLOCK");
258 locks_dump_ctx_list(&ctx->flc_posix, "POSIX");
259 locks_dump_ctx_list(&ctx->flc_lease, "LEASE");
260 }
261}
262
263void
264locks_free_lock_context(struct inode *inode)
265{
266 struct file_lock_context *ctx = inode->i_flctx;
267
268 if (unlikely(ctx)) {
269 locks_check_ctx_lists(inode);
270 kmem_cache_free(flctx_cache, ctx);
271 }
272}
273
274static void locks_init_lock_heads(struct file_lock *fl)
275{
276 INIT_HLIST_NODE(&fl->fl_link);
277 INIT_LIST_HEAD(&fl->fl_list);
278 INIT_LIST_HEAD(&fl->fl_block);
279 init_waitqueue_head(&fl->fl_wait);
280}
281
282/* Allocate an empty lock structure. */
283struct file_lock *locks_alloc_lock(void)
284{
285 struct file_lock *fl = kmem_cache_zalloc(filelock_cache, GFP_KERNEL);
286
287 if (fl)
288 locks_init_lock_heads(fl);
289
290 return fl;
291}
292EXPORT_SYMBOL_GPL(locks_alloc_lock);
293
294void locks_release_private(struct file_lock *fl)
295{
296 if (fl->fl_ops) {
297 if (fl->fl_ops->fl_release_private)
298 fl->fl_ops->fl_release_private(fl);
299 fl->fl_ops = NULL;
300 }
301
302 if (fl->fl_lmops) {
303 if (fl->fl_lmops->lm_put_owner) {
304 fl->fl_lmops->lm_put_owner(fl->fl_owner);
305 fl->fl_owner = NULL;
306 }
307 fl->fl_lmops = NULL;
308 }
309}
310EXPORT_SYMBOL_GPL(locks_release_private);
311
312/* Free a lock which is not in use. */
313void locks_free_lock(struct file_lock *fl)
314{
315 BUG_ON(waitqueue_active(&fl->fl_wait));
316 BUG_ON(!list_empty(&fl->fl_list));
317 BUG_ON(!list_empty(&fl->fl_block));
318 BUG_ON(!hlist_unhashed(&fl->fl_link));
319
320 locks_release_private(fl);
321 kmem_cache_free(filelock_cache, fl);
322}
323EXPORT_SYMBOL(locks_free_lock);
324
325static void
326locks_dispose_list(struct list_head *dispose)
327{
328 struct file_lock *fl;
329
330 while (!list_empty(dispose)) {
331 fl = list_first_entry(dispose, struct file_lock, fl_list);
332 list_del_init(&fl->fl_list);
333 locks_free_lock(fl);
334 }
335}
336
337void locks_init_lock(struct file_lock *fl)
338{
339 memset(fl, 0, sizeof(struct file_lock));
340 locks_init_lock_heads(fl);
341}
342
343EXPORT_SYMBOL(locks_init_lock);
344
345/*
346 * Initialize a new lock from an existing file_lock structure.
347 */
348void locks_copy_conflock(struct file_lock *new, struct file_lock *fl)
349{
350 new->fl_owner = fl->fl_owner;
351 new->fl_pid = fl->fl_pid;
352 new->fl_file = NULL;
353 new->fl_flags = fl->fl_flags;
354 new->fl_type = fl->fl_type;
355 new->fl_start = fl->fl_start;
356 new->fl_end = fl->fl_end;
357 new->fl_lmops = fl->fl_lmops;
358 new->fl_ops = NULL;
359
360 if (fl->fl_lmops) {
361 if (fl->fl_lmops->lm_get_owner)
362 fl->fl_lmops->lm_get_owner(fl->fl_owner);
363 }
364}
365EXPORT_SYMBOL(locks_copy_conflock);
366
367void locks_copy_lock(struct file_lock *new, struct file_lock *fl)
368{
369 /* "new" must be a freshly-initialized lock */
370 WARN_ON_ONCE(new->fl_ops);
371
372 locks_copy_conflock(new, fl);
373
374 new->fl_file = fl->fl_file;
375 new->fl_ops = fl->fl_ops;
376
377 if (fl->fl_ops) {
378 if (fl->fl_ops->fl_copy_lock)
379 fl->fl_ops->fl_copy_lock(new, fl);
380 }
381}
382
383EXPORT_SYMBOL(locks_copy_lock);
384
385static inline int flock_translate_cmd(int cmd) {
386 if (cmd & LOCK_MAND)
387 return cmd & (LOCK_MAND | LOCK_RW);
388 switch (cmd) {
389 case LOCK_SH:
390 return F_RDLCK;
391 case LOCK_EX:
392 return F_WRLCK;
393 case LOCK_UN:
394 return F_UNLCK;
395 }
396 return -EINVAL;
397}
398
399/* Fill in a file_lock structure with an appropriate FLOCK lock. */
400static struct file_lock *
401flock_make_lock(struct file *filp, unsigned int cmd)
402{
403 struct file_lock *fl;
404 int type = flock_translate_cmd(cmd);
405
406 if (type < 0)
407 return ERR_PTR(type);
408
409 fl = locks_alloc_lock();
410 if (fl == NULL)
411 return ERR_PTR(-ENOMEM);
412
413 fl->fl_file = filp;
414 fl->fl_owner = filp;
415 fl->fl_pid = current->tgid;
416 fl->fl_flags = FL_FLOCK;
417 fl->fl_type = type;
418 fl->fl_end = OFFSET_MAX;
419
420 return fl;
421}
422
423static int assign_type(struct file_lock *fl, long type)
424{
425 switch (type) {
426 case F_RDLCK:
427 case F_WRLCK:
428 case F_UNLCK:
429 fl->fl_type = type;
430 break;
431 default:
432 return -EINVAL;
433 }
434 return 0;
435}
436
437static int flock64_to_posix_lock(struct file *filp, struct file_lock *fl,
438 struct flock64 *l)
439{
440 switch (l->l_whence) {
441 case SEEK_SET:
442 fl->fl_start = 0;
443 break;
444 case SEEK_CUR:
445 fl->fl_start = filp->f_pos;
446 break;
447 case SEEK_END:
448 fl->fl_start = i_size_read(file_inode(filp));
449 break;
450 default:
451 return -EINVAL;
452 }
453 if (l->l_start > OFFSET_MAX - fl->fl_start)
454 return -EOVERFLOW;
455 fl->fl_start += l->l_start;
456 if (fl->fl_start < 0)
457 return -EINVAL;
458
459 /* POSIX-1996 leaves the case l->l_len < 0 undefined;
460 POSIX-2001 defines it. */
461 if (l->l_len > 0) {
462 if (l->l_len - 1 > OFFSET_MAX - fl->fl_start)
463 return -EOVERFLOW;
464 fl->fl_end = fl->fl_start + l->l_len - 1;
465
466 } else if (l->l_len < 0) {
467 if (fl->fl_start + l->l_len < 0)
468 return -EINVAL;
469 fl->fl_end = fl->fl_start - 1;
470 fl->fl_start += l->l_len;
471 } else
472 fl->fl_end = OFFSET_MAX;
473
474 fl->fl_owner = current->files;
475 fl->fl_pid = current->tgid;
476 fl->fl_file = filp;
477 fl->fl_flags = FL_POSIX;
478 fl->fl_ops = NULL;
479 fl->fl_lmops = NULL;
480
481 return assign_type(fl, l->l_type);
482}
483
484/* Verify a "struct flock" and copy it to a "struct file_lock" as a POSIX
485 * style lock.
486 */
487static int flock_to_posix_lock(struct file *filp, struct file_lock *fl,
488 struct flock *l)
489{
490 struct flock64 ll = {
491 .l_type = l->l_type,
492 .l_whence = l->l_whence,
493 .l_start = l->l_start,
494 .l_len = l->l_len,
495 };
496
497 return flock64_to_posix_lock(filp, fl, &ll);
498}
499
500/* default lease lock manager operations */
501static bool
502lease_break_callback(struct file_lock *fl)
503{
504 kill_fasync(&fl->fl_fasync, SIGIO, POLL_MSG);
505 return false;
506}
507
508static void
509lease_setup(struct file_lock *fl, void **priv)
510{
511 struct file *filp = fl->fl_file;
512 struct fasync_struct *fa = *priv;
513
514 /*
515 * fasync_insert_entry() returns the old entry if any. If there was no
516 * old entry, then it used "priv" and inserted it into the fasync list.
517 * Clear the pointer to indicate that it shouldn't be freed.
518 */
519 if (!fasync_insert_entry(fa->fa_fd, filp, &fl->fl_fasync, fa))
520 *priv = NULL;
521
522 __f_setown(filp, task_pid(current), PIDTYPE_PID, 0);
523}
524
525static const struct lock_manager_operations lease_manager_ops = {
526 .lm_break = lease_break_callback,
527 .lm_change = lease_modify,
528 .lm_setup = lease_setup,
529};
530
531/*
532 * Initialize a lease, use the default lock manager operations
533 */
534static int lease_init(struct file *filp, long type, struct file_lock *fl)
535 {
536 if (assign_type(fl, type) != 0)
537 return -EINVAL;
538
539 fl->fl_owner = filp;
540 fl->fl_pid = current->tgid;
541
542 fl->fl_file = filp;
543 fl->fl_flags = FL_LEASE;
544 fl->fl_start = 0;
545 fl->fl_end = OFFSET_MAX;
546 fl->fl_ops = NULL;
547 fl->fl_lmops = &lease_manager_ops;
548 return 0;
549}
550
551/* Allocate a file_lock initialised to this type of lease */
552static struct file_lock *lease_alloc(struct file *filp, long type)
553{
554 struct file_lock *fl = locks_alloc_lock();
555 int error = -ENOMEM;
556
557 if (fl == NULL)
558 return ERR_PTR(error);
559
560 error = lease_init(filp, type, fl);
561 if (error) {
562 locks_free_lock(fl);
563 return ERR_PTR(error);
564 }
565 return fl;
566}
567
568/* Check if two locks overlap each other.
569 */
570static inline int locks_overlap(struct file_lock *fl1, struct file_lock *fl2)
571{
572 return ((fl1->fl_end >= fl2->fl_start) &&
573 (fl2->fl_end >= fl1->fl_start));
574}
575
576/*
577 * Check whether two locks have the same owner.
578 */
579static int posix_same_owner(struct file_lock *fl1, struct file_lock *fl2)
580{
581 if (fl1->fl_lmops && fl1->fl_lmops->lm_compare_owner)
582 return fl2->fl_lmops == fl1->fl_lmops &&
583 fl1->fl_lmops->lm_compare_owner(fl1, fl2);
584 return fl1->fl_owner == fl2->fl_owner;
585}
586
587/* Must be called with the flc_lock held! */
588static void locks_insert_global_locks(struct file_lock *fl)
589{
590 lg_local_lock(&file_lock_lglock);
591 fl->fl_link_cpu = smp_processor_id();
592 hlist_add_head(&fl->fl_link, this_cpu_ptr(&file_lock_list));
593 lg_local_unlock(&file_lock_lglock);
594}
595
596/* Must be called with the flc_lock held! */
597static void locks_delete_global_locks(struct file_lock *fl)
598{
599 /*
600 * Avoid taking lock if already unhashed. This is safe since this check
601 * is done while holding the flc_lock, and new insertions into the list
602 * also require that it be held.
603 */
604 if (hlist_unhashed(&fl->fl_link))
605 return;
606 lg_local_lock_cpu(&file_lock_lglock, fl->fl_link_cpu);
607 hlist_del_init(&fl->fl_link);
608 lg_local_unlock_cpu(&file_lock_lglock, fl->fl_link_cpu);
609}
610
611static unsigned long
612posix_owner_key(struct file_lock *fl)
613{
614 if (fl->fl_lmops && fl->fl_lmops->lm_owner_key)
615 return fl->fl_lmops->lm_owner_key(fl);
616 return (unsigned long)fl->fl_owner;
617}
618
619static void locks_insert_global_blocked(struct file_lock *waiter)
620{
621 lockdep_assert_held(&blocked_lock_lock);
622
623 hash_add(blocked_hash, &waiter->fl_link, posix_owner_key(waiter));
624}
625
626static void locks_delete_global_blocked(struct file_lock *waiter)
627{
628 lockdep_assert_held(&blocked_lock_lock);
629
630 hash_del(&waiter->fl_link);
631}
632
633/* Remove waiter from blocker's block list.
634 * When blocker ends up pointing to itself then the list is empty.
635 *
636 * Must be called with blocked_lock_lock held.
637 */
638static void __locks_delete_block(struct file_lock *waiter)
639{
640 locks_delete_global_blocked(waiter);
641 list_del_init(&waiter->fl_block);
642 waiter->fl_next = NULL;
643}
644
645static void locks_delete_block(struct file_lock *waiter)
646{
647 spin_lock(&blocked_lock_lock);
648 __locks_delete_block(waiter);
649 spin_unlock(&blocked_lock_lock);
650}
651
652/* Insert waiter into blocker's block list.
653 * We use a circular list so that processes can be easily woken up in
654 * the order they blocked. The documentation doesn't require this but
655 * it seems like the reasonable thing to do.
656 *
657 * Must be called with both the flc_lock and blocked_lock_lock held. The
658 * fl_block list itself is protected by the blocked_lock_lock, but by ensuring
659 * that the flc_lock is also held on insertions we can avoid taking the
660 * blocked_lock_lock in some cases when we see that the fl_block list is empty.
661 */
662static void __locks_insert_block(struct file_lock *blocker,
663 struct file_lock *waiter)
664{
665 BUG_ON(!list_empty(&waiter->fl_block));
666 waiter->fl_next = blocker;
667 list_add_tail(&waiter->fl_block, &blocker->fl_block);
668 if (IS_POSIX(blocker) && !IS_OFDLCK(blocker))
669 locks_insert_global_blocked(waiter);
670}
671
672/* Must be called with flc_lock held. */
673static void locks_insert_block(struct file_lock *blocker,
674 struct file_lock *waiter)
675{
676 spin_lock(&blocked_lock_lock);
677 __locks_insert_block(blocker, waiter);
678 spin_unlock(&blocked_lock_lock);
679}
680
681/*
682 * Wake up processes blocked waiting for blocker.
683 *
684 * Must be called with the inode->flc_lock held!
685 */
686static void locks_wake_up_blocks(struct file_lock *blocker)
687{
688 /*
689 * Avoid taking global lock if list is empty. This is safe since new
690 * blocked requests are only added to the list under the flc_lock, and
691 * the flc_lock is always held here. Note that removal from the fl_block
692 * list does not require the flc_lock, so we must recheck list_empty()
693 * after acquiring the blocked_lock_lock.
694 */
695 if (list_empty(&blocker->fl_block))
696 return;
697
698 spin_lock(&blocked_lock_lock);
699 while (!list_empty(&blocker->fl_block)) {
700 struct file_lock *waiter;
701
702 waiter = list_first_entry(&blocker->fl_block,
703 struct file_lock, fl_block);
704 __locks_delete_block(waiter);
705 if (waiter->fl_lmops && waiter->fl_lmops->lm_notify)
706 waiter->fl_lmops->lm_notify(waiter);
707 else
708 wake_up(&waiter->fl_wait);
709 }
710 spin_unlock(&blocked_lock_lock);
711}
712
713static void
714locks_insert_lock_ctx(struct file_lock *fl, struct list_head *before)
715{
716 fl->fl_nspid = get_pid(task_tgid(current));
717 list_add_tail(&fl->fl_list, before);
718 locks_insert_global_locks(fl);
719}
720
721static void
722locks_unlink_lock_ctx(struct file_lock *fl)
723{
724 locks_delete_global_locks(fl);
725 list_del_init(&fl->fl_list);
726 if (fl->fl_nspid) {
727 put_pid(fl->fl_nspid);
728 fl->fl_nspid = NULL;
729 }
730 locks_wake_up_blocks(fl);
731}
732
733static void
734locks_delete_lock_ctx(struct file_lock *fl, struct list_head *dispose)
735{
736 locks_unlink_lock_ctx(fl);
737 if (dispose)
738 list_add(&fl->fl_list, dispose);
739 else
740 locks_free_lock(fl);
741}
742
743/* Determine if lock sys_fl blocks lock caller_fl. Common functionality
744 * checks for shared/exclusive status of overlapping locks.
745 */
746static int locks_conflict(struct file_lock *caller_fl, struct file_lock *sys_fl)
747{
748 if (sys_fl->fl_type == F_WRLCK)
749 return 1;
750 if (caller_fl->fl_type == F_WRLCK)
751 return 1;
752 return 0;
753}
754
755/* Determine if lock sys_fl blocks lock caller_fl. POSIX specific
756 * checking before calling the locks_conflict().
757 */
758static int posix_locks_conflict(struct file_lock *caller_fl, struct file_lock *sys_fl)
759{
760 /* POSIX locks owned by the same process do not conflict with
761 * each other.
762 */
763 if (posix_same_owner(caller_fl, sys_fl))
764 return (0);
765
766 /* Check whether they overlap */
767 if (!locks_overlap(caller_fl, sys_fl))
768 return 0;
769
770 return (locks_conflict(caller_fl, sys_fl));
771}
772
773/* Determine if lock sys_fl blocks lock caller_fl. FLOCK specific
774 * checking before calling the locks_conflict().
775 */
776static int flock_locks_conflict(struct file_lock *caller_fl, struct file_lock *sys_fl)
777{
778 /* FLOCK locks referring to the same filp do not conflict with
779 * each other.
780 */
781 if (caller_fl->fl_file == sys_fl->fl_file)
782 return (0);
783 if ((caller_fl->fl_type & LOCK_MAND) || (sys_fl->fl_type & LOCK_MAND))
784 return 0;
785
786 return (locks_conflict(caller_fl, sys_fl));
787}
788
789void
790posix_test_lock(struct file *filp, struct file_lock *fl)
791{
792 struct file_lock *cfl;
793 struct file_lock_context *ctx;
794 struct inode *inode = file_inode(filp);
795
796 ctx = smp_load_acquire(&inode->i_flctx);
797 if (!ctx || list_empty_careful(&ctx->flc_posix)) {
798 fl->fl_type = F_UNLCK;
799 return;
800 }
801
802 spin_lock(&ctx->flc_lock);
803 list_for_each_entry(cfl, &ctx->flc_posix, fl_list) {
804 if (posix_locks_conflict(fl, cfl)) {
805 locks_copy_conflock(fl, cfl);
806 if (cfl->fl_nspid)
807 fl->fl_pid = pid_vnr(cfl->fl_nspid);
808 goto out;
809 }
810 }
811 fl->fl_type = F_UNLCK;
812out:
813 spin_unlock(&ctx->flc_lock);
814 return;
815}
816EXPORT_SYMBOL(posix_test_lock);
817
818/*
819 * Deadlock detection:
820 *
821 * We attempt to detect deadlocks that are due purely to posix file
822 * locks.
823 *
824 * We assume that a task can be waiting for at most one lock at a time.
825 * So for any acquired lock, the process holding that lock may be
826 * waiting on at most one other lock. That lock in turns may be held by
827 * someone waiting for at most one other lock. Given a requested lock
828 * caller_fl which is about to wait for a conflicting lock block_fl, we
829 * follow this chain of waiters to ensure we are not about to create a
830 * cycle.
831 *
832 * Since we do this before we ever put a process to sleep on a lock, we
833 * are ensured that there is never a cycle; that is what guarantees that
834 * the while() loop in posix_locks_deadlock() eventually completes.
835 *
836 * Note: the above assumption may not be true when handling lock
837 * requests from a broken NFS client. It may also fail in the presence
838 * of tasks (such as posix threads) sharing the same open file table.
839 * To handle those cases, we just bail out after a few iterations.
840 *
841 * For FL_OFDLCK locks, the owner is the filp, not the files_struct.
842 * Because the owner is not even nominally tied to a thread of
843 * execution, the deadlock detection below can't reasonably work well. Just
844 * skip it for those.
845 *
846 * In principle, we could do a more limited deadlock detection on FL_OFDLCK
847 * locks that just checks for the case where two tasks are attempting to
848 * upgrade from read to write locks on the same inode.
849 */
850
851#define MAX_DEADLK_ITERATIONS 10
852
853/* Find a lock that the owner of the given block_fl is blocking on. */
854static struct file_lock *what_owner_is_waiting_for(struct file_lock *block_fl)
855{
856 struct file_lock *fl;
857
858 hash_for_each_possible(blocked_hash, fl, fl_link, posix_owner_key(block_fl)) {
859 if (posix_same_owner(fl, block_fl))
860 return fl->fl_next;
861 }
862 return NULL;
863}
864
865/* Must be called with the blocked_lock_lock held! */
866static int posix_locks_deadlock(struct file_lock *caller_fl,
867 struct file_lock *block_fl)
868{
869 int i = 0;
870
871 lockdep_assert_held(&blocked_lock_lock);
872
873 /*
874 * This deadlock detector can't reasonably detect deadlocks with
875 * FL_OFDLCK locks, since they aren't owned by a process, per-se.
876 */
877 if (IS_OFDLCK(caller_fl))
878 return 0;
879
880 while ((block_fl = what_owner_is_waiting_for(block_fl))) {
881 if (i++ > MAX_DEADLK_ITERATIONS)
882 return 0;
883 if (posix_same_owner(caller_fl, block_fl))
884 return 1;
885 }
886 return 0;
887}
888
889/* Try to create a FLOCK lock on filp. We always insert new FLOCK locks
890 * after any leases, but before any posix locks.
891 *
892 * Note that if called with an FL_EXISTS argument, the caller may determine
893 * whether or not a lock was successfully freed by testing the return
894 * value for -ENOENT.
895 */
896static int flock_lock_inode(struct inode *inode, struct file_lock *request)
897{
898 struct file_lock *new_fl = NULL;
899 struct file_lock *fl;
900 struct file_lock_context *ctx;
901 int error = 0;
902 bool found = false;
903 LIST_HEAD(dispose);
904
905 ctx = locks_get_lock_context(inode, request->fl_type);
906 if (!ctx) {
907 if (request->fl_type != F_UNLCK)
908 return -ENOMEM;
909 return (request->fl_flags & FL_EXISTS) ? -ENOENT : 0;
910 }
911
912 if (!(request->fl_flags & FL_ACCESS) && (request->fl_type != F_UNLCK)) {
913 new_fl = locks_alloc_lock();
914 if (!new_fl)
915 return -ENOMEM;
916 }
917
918 spin_lock(&ctx->flc_lock);
919 if (request->fl_flags & FL_ACCESS)
920 goto find_conflict;
921
922 list_for_each_entry(fl, &ctx->flc_flock, fl_list) {
923 if (request->fl_file != fl->fl_file)
924 continue;
925 if (request->fl_type == fl->fl_type)
926 goto out;
927 found = true;
928 locks_delete_lock_ctx(fl, &dispose);
929 break;
930 }
931
932 if (request->fl_type == F_UNLCK) {
933 if ((request->fl_flags & FL_EXISTS) && !found)
934 error = -ENOENT;
935 goto out;
936 }
937
938find_conflict:
939 list_for_each_entry(fl, &ctx->flc_flock, fl_list) {
940 if (!flock_locks_conflict(request, fl))
941 continue;
942 error = -EAGAIN;
943 if (!(request->fl_flags & FL_SLEEP))
944 goto out;
945 error = FILE_LOCK_DEFERRED;
946 locks_insert_block(fl, request);
947 goto out;
948 }
949 if (request->fl_flags & FL_ACCESS)
950 goto out;
951 locks_copy_lock(new_fl, request);
952 locks_insert_lock_ctx(new_fl, &ctx->flc_flock);
953 new_fl = NULL;
954 error = 0;
955
956out:
957 spin_unlock(&ctx->flc_lock);
958 if (new_fl)
959 locks_free_lock(new_fl);
960 locks_dispose_list(&dispose);
961 return error;
962}
963
964static int posix_lock_inode(struct inode *inode, struct file_lock *request,
965 struct file_lock *conflock)
966{
967 struct file_lock *fl, *tmp;
968 struct file_lock *new_fl = NULL;
969 struct file_lock *new_fl2 = NULL;
970 struct file_lock *left = NULL;
971 struct file_lock *right = NULL;
972 struct file_lock_context *ctx;
973 int error;
974 bool added = false;
975 LIST_HEAD(dispose);
976
977 ctx = locks_get_lock_context(inode, request->fl_type);
978 if (!ctx)
979 return (request->fl_type == F_UNLCK) ? 0 : -ENOMEM;
980
981 /*
982 * We may need two file_lock structures for this operation,
983 * so we get them in advance to avoid races.
984 *
985 * In some cases we can be sure, that no new locks will be needed
986 */
987 if (!(request->fl_flags & FL_ACCESS) &&
988 (request->fl_type != F_UNLCK ||
989 request->fl_start != 0 || request->fl_end != OFFSET_MAX)) {
990 new_fl = locks_alloc_lock();
991 new_fl2 = locks_alloc_lock();
992 }
993
994 spin_lock(&ctx->flc_lock);
995 /*
996 * New lock request. Walk all POSIX locks and look for conflicts. If
997 * there are any, either return error or put the request on the
998 * blocker's list of waiters and the global blocked_hash.
999 */
1000 if (request->fl_type != F_UNLCK) {
1001 list_for_each_entry(fl, &ctx->flc_posix, fl_list) {
1002 if (!posix_locks_conflict(request, fl))
1003 continue;
1004 if (conflock)
1005 locks_copy_conflock(conflock, fl);
1006 error = -EAGAIN;
1007 if (!(request->fl_flags & FL_SLEEP))
1008 goto out;
1009 /*
1010 * Deadlock detection and insertion into the blocked
1011 * locks list must be done while holding the same lock!
1012 */
1013 error = -EDEADLK;
1014 spin_lock(&blocked_lock_lock);
1015 if (likely(!posix_locks_deadlock(request, fl))) {
1016 error = FILE_LOCK_DEFERRED;
1017 __locks_insert_block(fl, request);
1018 }
1019 spin_unlock(&blocked_lock_lock);
1020 goto out;
1021 }
1022 }
1023
1024 /* If we're just looking for a conflict, we're done. */
1025 error = 0;
1026 if (request->fl_flags & FL_ACCESS)
1027 goto out;
1028
1029 /* Find the first old lock with the same owner as the new lock */
1030 list_for_each_entry(fl, &ctx->flc_posix, fl_list) {
1031 if (posix_same_owner(request, fl))
1032 break;
1033 }
1034
1035 /* Process locks with this owner. */
1036 list_for_each_entry_safe_from(fl, tmp, &ctx->flc_posix, fl_list) {
1037 if (!posix_same_owner(request, fl))
1038 break;
1039
1040 /* Detect adjacent or overlapping regions (if same lock type) */
1041 if (request->fl_type == fl->fl_type) {
1042 /* In all comparisons of start vs end, use
1043 * "start - 1" rather than "end + 1". If end
1044 * is OFFSET_MAX, end + 1 will become negative.
1045 */
1046 if (fl->fl_end < request->fl_start - 1)
1047 continue;
1048 /* If the next lock in the list has entirely bigger
1049 * addresses than the new one, insert the lock here.
1050 */
1051 if (fl->fl_start - 1 > request->fl_end)
1052 break;
1053
1054 /* If we come here, the new and old lock are of the
1055 * same type and adjacent or overlapping. Make one
1056 * lock yielding from the lower start address of both
1057 * locks to the higher end address.
1058 */
1059 if (fl->fl_start > request->fl_start)
1060 fl->fl_start = request->fl_start;
1061 else
1062 request->fl_start = fl->fl_start;
1063 if (fl->fl_end < request->fl_end)
1064 fl->fl_end = request->fl_end;
1065 else
1066 request->fl_end = fl->fl_end;
1067 if (added) {
1068 locks_delete_lock_ctx(fl, &dispose);
1069 continue;
1070 }
1071 request = fl;
1072 added = true;
1073 } else {
1074 /* Processing for different lock types is a bit
1075 * more complex.
1076 */
1077 if (fl->fl_end < request->fl_start)
1078 continue;
1079 if (fl->fl_start > request->fl_end)
1080 break;
1081 if (request->fl_type == F_UNLCK)
1082 added = true;
1083 if (fl->fl_start < request->fl_start)
1084 left = fl;
1085 /* If the next lock in the list has a higher end
1086 * address than the new one, insert the new one here.
1087 */
1088 if (fl->fl_end > request->fl_end) {
1089 right = fl;
1090 break;
1091 }
1092 if (fl->fl_start >= request->fl_start) {
1093 /* The new lock completely replaces an old
1094 * one (This may happen several times).
1095 */
1096 if (added) {
1097 locks_delete_lock_ctx(fl, &dispose);
1098 continue;
1099 }
1100 /*
1101 * Replace the old lock with new_fl, and
1102 * remove the old one. It's safe to do the
1103 * insert here since we know that we won't be
1104 * using new_fl later, and that the lock is
1105 * just replacing an existing lock.
1106 */
1107 error = -ENOLCK;
1108 if (!new_fl)
1109 goto out;
1110 locks_copy_lock(new_fl, request);
1111 request = new_fl;
1112 new_fl = NULL;
1113 locks_insert_lock_ctx(request, &fl->fl_list);
1114 locks_delete_lock_ctx(fl, &dispose);
1115 added = true;
1116 }
1117 }
1118 }
1119
1120 /*
1121 * The above code only modifies existing locks in case of merging or
1122 * replacing. If new lock(s) need to be inserted all modifications are
1123 * done below this, so it's safe yet to bail out.
1124 */
1125 error = -ENOLCK; /* "no luck" */
1126 if (right && left == right && !new_fl2)
1127 goto out;
1128
1129 error = 0;
1130 if (!added) {
1131 if (request->fl_type == F_UNLCK) {
1132 if (request->fl_flags & FL_EXISTS)
1133 error = -ENOENT;
1134 goto out;
1135 }
1136
1137 if (!new_fl) {
1138 error = -ENOLCK;
1139 goto out;
1140 }
1141 locks_copy_lock(new_fl, request);
1142 locks_insert_lock_ctx(new_fl, &fl->fl_list);
1143 fl = new_fl;
1144 new_fl = NULL;
1145 }
1146 if (right) {
1147 if (left == right) {
1148 /* The new lock breaks the old one in two pieces,
1149 * so we have to use the second new lock.
1150 */
1151 left = new_fl2;
1152 new_fl2 = NULL;
1153 locks_copy_lock(left, right);
1154 locks_insert_lock_ctx(left, &fl->fl_list);
1155 }
1156 right->fl_start = request->fl_end + 1;
1157 locks_wake_up_blocks(right);
1158 }
1159 if (left) {
1160 left->fl_end = request->fl_start - 1;
1161 locks_wake_up_blocks(left);
1162 }
1163 out:
1164 spin_unlock(&ctx->flc_lock);
1165 /*
1166 * Free any unused locks.
1167 */
1168 if (new_fl)
1169 locks_free_lock(new_fl);
1170 if (new_fl2)
1171 locks_free_lock(new_fl2);
1172 locks_dispose_list(&dispose);
1173 trace_posix_lock_inode(inode, request, error);
1174
1175 return error;
1176}
1177
1178/**
1179 * posix_lock_file - Apply a POSIX-style lock to a file
1180 * @filp: The file to apply the lock to
1181 * @fl: The lock to be applied
1182 * @conflock: Place to return a copy of the conflicting lock, if found.
1183 *
1184 * Add a POSIX style lock to a file.
1185 * We merge adjacent & overlapping locks whenever possible.
1186 * POSIX locks are sorted by owner task, then by starting address
1187 *
1188 * Note that if called with an FL_EXISTS argument, the caller may determine
1189 * whether or not a lock was successfully freed by testing the return
1190 * value for -ENOENT.
1191 */
1192int posix_lock_file(struct file *filp, struct file_lock *fl,
1193 struct file_lock *conflock)
1194{
1195 return posix_lock_inode(file_inode(filp), fl, conflock);
1196}
1197EXPORT_SYMBOL(posix_lock_file);
1198
1199/**
1200 * posix_lock_inode_wait - Apply a POSIX-style lock to a file
1201 * @inode: inode of file to which lock request should be applied
1202 * @fl: The lock to be applied
1203 *
1204 * Apply a POSIX style lock request to an inode.
1205 */
1206static int posix_lock_inode_wait(struct inode *inode, struct file_lock *fl)
1207{
1208 int error;
1209 might_sleep ();
1210 for (;;) {
1211 error = posix_lock_inode(inode, fl, NULL);
1212 if (error != FILE_LOCK_DEFERRED)
1213 break;
1214 error = wait_event_interruptible(fl->fl_wait, !fl->fl_next);
1215 if (!error)
1216 continue;
1217
1218 locks_delete_block(fl);
1219 break;
1220 }
1221 return error;
1222}
1223
1224#ifdef CONFIG_MANDATORY_FILE_LOCKING
1225/**
1226 * locks_mandatory_locked - Check for an active lock
1227 * @file: the file to check
1228 *
1229 * Searches the inode's list of locks to find any POSIX locks which conflict.
1230 * This function is called from locks_verify_locked() only.
1231 */
1232int locks_mandatory_locked(struct file *file)
1233{
1234 int ret;
1235 struct inode *inode = file_inode(file);
1236 struct file_lock_context *ctx;
1237 struct file_lock *fl;
1238
1239 ctx = smp_load_acquire(&inode->i_flctx);
1240 if (!ctx || list_empty_careful(&ctx->flc_posix))
1241 return 0;
1242
1243 /*
1244 * Search the lock list for this inode for any POSIX locks.
1245 */
1246 spin_lock(&ctx->flc_lock);
1247 ret = 0;
1248 list_for_each_entry(fl, &ctx->flc_posix, fl_list) {
1249 if (fl->fl_owner != current->files &&
1250 fl->fl_owner != file) {
1251 ret = -EAGAIN;
1252 break;
1253 }
1254 }
1255 spin_unlock(&ctx->flc_lock);
1256 return ret;
1257}
1258
1259/**
1260 * locks_mandatory_area - Check for a conflicting lock
1261 * @inode: the file to check
1262 * @filp: how the file was opened (if it was)
1263 * @start: first byte in the file to check
1264 * @end: lastbyte in the file to check
1265 * @type: %F_WRLCK for a write lock, else %F_RDLCK
1266 *
1267 * Searches the inode's list of locks to find any POSIX locks which conflict.
1268 */
1269int locks_mandatory_area(struct inode *inode, struct file *filp, loff_t start,
1270 loff_t end, unsigned char type)
1271{
1272 struct file_lock fl;
1273 int error;
1274 bool sleep = false;
1275
1276 locks_init_lock(&fl);
1277 fl.fl_pid = current->tgid;
1278 fl.fl_file = filp;
1279 fl.fl_flags = FL_POSIX | FL_ACCESS;
1280 if (filp && !(filp->f_flags & O_NONBLOCK))
1281 sleep = true;
1282 fl.fl_type = type;
1283 fl.fl_start = start;
1284 fl.fl_end = end;
1285
1286 for (;;) {
1287 if (filp) {
1288 fl.fl_owner = filp;
1289 fl.fl_flags &= ~FL_SLEEP;
1290 error = posix_lock_inode(inode, &fl, NULL);
1291 if (!error)
1292 break;
1293 }
1294
1295 if (sleep)
1296 fl.fl_flags |= FL_SLEEP;
1297 fl.fl_owner = current->files;
1298 error = posix_lock_inode(inode, &fl, NULL);
1299 if (error != FILE_LOCK_DEFERRED)
1300 break;
1301 error = wait_event_interruptible(fl.fl_wait, !fl.fl_next);
1302 if (!error) {
1303 /*
1304 * If we've been sleeping someone might have
1305 * changed the permissions behind our back.
1306 */
1307 if (__mandatory_lock(inode))
1308 continue;
1309 }
1310
1311 locks_delete_block(&fl);
1312 break;
1313 }
1314
1315 return error;
1316}
1317
1318EXPORT_SYMBOL(locks_mandatory_area);
1319#endif /* CONFIG_MANDATORY_FILE_LOCKING */
1320
1321static void lease_clear_pending(struct file_lock *fl, int arg)
1322{
1323 switch (arg) {
1324 case F_UNLCK:
1325 fl->fl_flags &= ~FL_UNLOCK_PENDING;
1326 /* fall through: */
1327 case F_RDLCK:
1328 fl->fl_flags &= ~FL_DOWNGRADE_PENDING;
1329 }
1330}
1331
1332/* We already had a lease on this file; just change its type */
1333int lease_modify(struct file_lock *fl, int arg, struct list_head *dispose)
1334{
1335 int error = assign_type(fl, arg);
1336
1337 if (error)
1338 return error;
1339 lease_clear_pending(fl, arg);
1340 locks_wake_up_blocks(fl);
1341 if (arg == F_UNLCK) {
1342 struct file *filp = fl->fl_file;
1343
1344 f_delown(filp);
1345 filp->f_owner.signum = 0;
1346 fasync_helper(0, fl->fl_file, 0, &fl->fl_fasync);
1347 if (fl->fl_fasync != NULL) {
1348 printk(KERN_ERR "locks_delete_lock: fasync == %p\n", fl->fl_fasync);
1349 fl->fl_fasync = NULL;
1350 }
1351 locks_delete_lock_ctx(fl, dispose);
1352 }
1353 return 0;
1354}
1355EXPORT_SYMBOL(lease_modify);
1356
1357static bool past_time(unsigned long then)
1358{
1359 if (!then)
1360 /* 0 is a special value meaning "this never expires": */
1361 return false;
1362 return time_after(jiffies, then);
1363}
1364
1365static void time_out_leases(struct inode *inode, struct list_head *dispose)
1366{
1367 struct file_lock_context *ctx = inode->i_flctx;
1368 struct file_lock *fl, *tmp;
1369
1370 lockdep_assert_held(&ctx->flc_lock);
1371
1372 list_for_each_entry_safe(fl, tmp, &ctx->flc_lease, fl_list) {
1373 trace_time_out_leases(inode, fl);
1374 if (past_time(fl->fl_downgrade_time))
1375 lease_modify(fl, F_RDLCK, dispose);
1376 if (past_time(fl->fl_break_time))
1377 lease_modify(fl, F_UNLCK, dispose);
1378 }
1379}
1380
1381static bool leases_conflict(struct file_lock *lease, struct file_lock *breaker)
1382{
1383 if ((breaker->fl_flags & FL_LAYOUT) != (lease->fl_flags & FL_LAYOUT))
1384 return false;
1385 if ((breaker->fl_flags & FL_DELEG) && (lease->fl_flags & FL_LEASE))
1386 return false;
1387 return locks_conflict(breaker, lease);
1388}
1389
1390static bool
1391any_leases_conflict(struct inode *inode, struct file_lock *breaker)
1392{
1393 struct file_lock_context *ctx = inode->i_flctx;
1394 struct file_lock *fl;
1395
1396 lockdep_assert_held(&ctx->flc_lock);
1397
1398 list_for_each_entry(fl, &ctx->flc_lease, fl_list) {
1399 if (leases_conflict(fl, breaker))
1400 return true;
1401 }
1402 return false;
1403}
1404
1405/**
1406 * __break_lease - revoke all outstanding leases on file
1407 * @inode: the inode of the file to return
1408 * @mode: O_RDONLY: break only write leases; O_WRONLY or O_RDWR:
1409 * break all leases
1410 * @type: FL_LEASE: break leases and delegations; FL_DELEG: break
1411 * only delegations
1412 *
1413 * break_lease (inlined for speed) has checked there already is at least
1414 * some kind of lock (maybe a lease) on this file. Leases are broken on
1415 * a call to open() or truncate(). This function can sleep unless you
1416 * specified %O_NONBLOCK to your open().
1417 */
1418int __break_lease(struct inode *inode, unsigned int mode, unsigned int type)
1419{
1420 int error = 0;
1421 struct file_lock_context *ctx;
1422 struct file_lock *new_fl, *fl, *tmp;
1423 unsigned long break_time;
1424 int want_write = (mode & O_ACCMODE) != O_RDONLY;
1425 LIST_HEAD(dispose);
1426
1427 new_fl = lease_alloc(NULL, want_write ? F_WRLCK : F_RDLCK);
1428 if (IS_ERR(new_fl))
1429 return PTR_ERR(new_fl);
1430 new_fl->fl_flags = type;
1431
1432 /* typically we will check that ctx is non-NULL before calling */
1433 ctx = smp_load_acquire(&inode->i_flctx);
1434 if (!ctx) {
1435 WARN_ON_ONCE(1);
1436 return error;
1437 }
1438
1439 spin_lock(&ctx->flc_lock);
1440
1441 time_out_leases(inode, &dispose);
1442
1443 if (!any_leases_conflict(inode, new_fl))
1444 goto out;
1445
1446 break_time = 0;
1447 if (lease_break_time > 0) {
1448 break_time = jiffies + lease_break_time * HZ;
1449 if (break_time == 0)
1450 break_time++; /* so that 0 means no break time */
1451 }
1452
1453 list_for_each_entry_safe(fl, tmp, &ctx->flc_lease, fl_list) {
1454 if (!leases_conflict(fl, new_fl))
1455 continue;
1456 if (want_write) {
1457 if (fl->fl_flags & FL_UNLOCK_PENDING)
1458 continue;
1459 fl->fl_flags |= FL_UNLOCK_PENDING;
1460 fl->fl_break_time = break_time;
1461 } else {
1462 if (lease_breaking(fl))
1463 continue;
1464 fl->fl_flags |= FL_DOWNGRADE_PENDING;
1465 fl->fl_downgrade_time = break_time;
1466 }
1467 if (fl->fl_lmops->lm_break(fl))
1468 locks_delete_lock_ctx(fl, &dispose);
1469 }
1470
1471 if (list_empty(&ctx->flc_lease))
1472 goto out;
1473
1474 if (mode & O_NONBLOCK) {
1475 trace_break_lease_noblock(inode, new_fl);
1476 error = -EWOULDBLOCK;
1477 goto out;
1478 }
1479
1480restart:
1481 fl = list_first_entry(&ctx->flc_lease, struct file_lock, fl_list);
1482 break_time = fl->fl_break_time;
1483 if (break_time != 0)
1484 break_time -= jiffies;
1485 if (break_time == 0)
1486 break_time++;
1487 locks_insert_block(fl, new_fl);
1488 trace_break_lease_block(inode, new_fl);
1489 spin_unlock(&ctx->flc_lock);
1490 locks_dispose_list(&dispose);
1491 error = wait_event_interruptible_timeout(new_fl->fl_wait,
1492 !new_fl->fl_next, break_time);
1493 spin_lock(&ctx->flc_lock);
1494 trace_break_lease_unblock(inode, new_fl);
1495 locks_delete_block(new_fl);
1496 if (error >= 0) {
1497 /*
1498 * Wait for the next conflicting lease that has not been
1499 * broken yet
1500 */
1501 if (error == 0)
1502 time_out_leases(inode, &dispose);
1503 if (any_leases_conflict(inode, new_fl))
1504 goto restart;
1505 error = 0;
1506 }
1507out:
1508 spin_unlock(&ctx->flc_lock);
1509 locks_dispose_list(&dispose);
1510 locks_free_lock(new_fl);
1511 return error;
1512}
1513
1514EXPORT_SYMBOL(__break_lease);
1515
1516/**
1517 * lease_get_mtime - get the last modified time of an inode
1518 * @inode: the inode
1519 * @time: pointer to a timespec which will contain the last modified time
1520 *
1521 * This is to force NFS clients to flush their caches for files with
1522 * exclusive leases. The justification is that if someone has an
1523 * exclusive lease, then they could be modifying it.
1524 */
1525void lease_get_mtime(struct inode *inode, struct timespec *time)
1526{
1527 bool has_lease = false;
1528 struct file_lock_context *ctx;
1529 struct file_lock *fl;
1530
1531 ctx = smp_load_acquire(&inode->i_flctx);
1532 if (ctx && !list_empty_careful(&ctx->flc_lease)) {
1533 spin_lock(&ctx->flc_lock);
1534 fl = list_first_entry_or_null(&ctx->flc_lease,
1535 struct file_lock, fl_list);
1536 if (fl && (fl->fl_type == F_WRLCK))
1537 has_lease = true;
1538 spin_unlock(&ctx->flc_lock);
1539 }
1540
1541 if (has_lease)
1542 *time = current_fs_time(inode->i_sb);
1543 else
1544 *time = inode->i_mtime;
1545}
1546
1547EXPORT_SYMBOL(lease_get_mtime);
1548
1549/**
1550 * fcntl_getlease - Enquire what lease is currently active
1551 * @filp: the file
1552 *
1553 * The value returned by this function will be one of
1554 * (if no lease break is pending):
1555 *
1556 * %F_RDLCK to indicate a shared lease is held.
1557 *
1558 * %F_WRLCK to indicate an exclusive lease is held.
1559 *
1560 * %F_UNLCK to indicate no lease is held.
1561 *
1562 * (if a lease break is pending):
1563 *
1564 * %F_RDLCK to indicate an exclusive lease needs to be
1565 * changed to a shared lease (or removed).
1566 *
1567 * %F_UNLCK to indicate the lease needs to be removed.
1568 *
1569 * XXX: sfr & willy disagree over whether F_INPROGRESS
1570 * should be returned to userspace.
1571 */
1572int fcntl_getlease(struct file *filp)
1573{
1574 struct file_lock *fl;
1575 struct inode *inode = file_inode(filp);
1576 struct file_lock_context *ctx;
1577 int type = F_UNLCK;
1578 LIST_HEAD(dispose);
1579
1580 ctx = smp_load_acquire(&inode->i_flctx);
1581 if (ctx && !list_empty_careful(&ctx->flc_lease)) {
1582 spin_lock(&ctx->flc_lock);
1583 time_out_leases(file_inode(filp), &dispose);
1584 list_for_each_entry(fl, &ctx->flc_lease, fl_list) {
1585 if (fl->fl_file != filp)
1586 continue;
1587 type = target_leasetype(fl);
1588 break;
1589 }
1590 spin_unlock(&ctx->flc_lock);
1591 locks_dispose_list(&dispose);
1592 }
1593 return type;
1594}
1595
1596/**
1597 * check_conflicting_open - see if the given dentry points to a file that has
1598 * an existing open that would conflict with the
1599 * desired lease.
1600 * @dentry: dentry to check
1601 * @arg: type of lease that we're trying to acquire
1602 * @flags: current lock flags
1603 *
1604 * Check to see if there's an existing open fd on this file that would
1605 * conflict with the lease we're trying to set.
1606 */
1607static int
1608check_conflicting_open(const struct dentry *dentry, const long arg, int flags)
1609{
1610 int ret = 0;
1611 struct inode *inode = dentry->d_inode;
1612
1613 if (flags & FL_LAYOUT)
1614 return 0;
1615
1616 if ((arg == F_RDLCK) && (atomic_read(&inode->i_writecount) > 0))
1617 return -EAGAIN;
1618
1619 if ((arg == F_WRLCK) && ((d_count(dentry) > 1) ||
1620 (atomic_read(&inode->i_count) > 1)))
1621 ret = -EAGAIN;
1622
1623 return ret;
1624}
1625
1626static int
1627generic_add_lease(struct file *filp, long arg, struct file_lock **flp, void **priv)
1628{
1629 struct file_lock *fl, *my_fl = NULL, *lease;
1630 struct dentry *dentry = filp->f_path.dentry;
1631 struct inode *inode = dentry->d_inode;
1632 struct file_lock_context *ctx;
1633 bool is_deleg = (*flp)->fl_flags & FL_DELEG;
1634 int error;
1635 LIST_HEAD(dispose);
1636
1637 lease = *flp;
1638 trace_generic_add_lease(inode, lease);
1639
1640 /* Note that arg is never F_UNLCK here */
1641 ctx = locks_get_lock_context(inode, arg);
1642 if (!ctx)
1643 return -ENOMEM;
1644
1645 /*
1646 * In the delegation case we need mutual exclusion with
1647 * a number of operations that take the i_mutex. We trylock
1648 * because delegations are an optional optimization, and if
1649 * there's some chance of a conflict--we'd rather not
1650 * bother, maybe that's a sign this just isn't a good file to
1651 * hand out a delegation on.
1652 */
1653 if (is_deleg && !inode_trylock(inode))
1654 return -EAGAIN;
1655
1656 if (is_deleg && arg == F_WRLCK) {
1657 /* Write delegations are not currently supported: */
1658 inode_unlock(inode);
1659 WARN_ON_ONCE(1);
1660 return -EINVAL;
1661 }
1662
1663 spin_lock(&ctx->flc_lock);
1664 time_out_leases(inode, &dispose);
1665 error = check_conflicting_open(dentry, arg, lease->fl_flags);
1666 if (error)
1667 goto out;
1668
1669 /*
1670 * At this point, we know that if there is an exclusive
1671 * lease on this file, then we hold it on this filp
1672 * (otherwise our open of this file would have blocked).
1673 * And if we are trying to acquire an exclusive lease,
1674 * then the file is not open by anyone (including us)
1675 * except for this filp.
1676 */
1677 error = -EAGAIN;
1678 list_for_each_entry(fl, &ctx->flc_lease, fl_list) {
1679 if (fl->fl_file == filp &&
1680 fl->fl_owner == lease->fl_owner) {
1681 my_fl = fl;
1682 continue;
1683 }
1684
1685 /*
1686 * No exclusive leases if someone else has a lease on
1687 * this file:
1688 */
1689 if (arg == F_WRLCK)
1690 goto out;
1691 /*
1692 * Modifying our existing lease is OK, but no getting a
1693 * new lease if someone else is opening for write:
1694 */
1695 if (fl->fl_flags & FL_UNLOCK_PENDING)
1696 goto out;
1697 }
1698
1699 if (my_fl != NULL) {
1700 lease = my_fl;
1701 error = lease->fl_lmops->lm_change(lease, arg, &dispose);
1702 if (error)
1703 goto out;
1704 goto out_setup;
1705 }
1706
1707 error = -EINVAL;
1708 if (!leases_enable)
1709 goto out;
1710
1711 locks_insert_lock_ctx(lease, &ctx->flc_lease);
1712 /*
1713 * The check in break_lease() is lockless. It's possible for another
1714 * open to race in after we did the earlier check for a conflicting
1715 * open but before the lease was inserted. Check again for a
1716 * conflicting open and cancel the lease if there is one.
1717 *
1718 * We also add a barrier here to ensure that the insertion of the lock
1719 * precedes these checks.
1720 */
1721 smp_mb();
1722 error = check_conflicting_open(dentry, arg, lease->fl_flags);
1723 if (error) {
1724 locks_unlink_lock_ctx(lease);
1725 goto out;
1726 }
1727
1728out_setup:
1729 if (lease->fl_lmops->lm_setup)
1730 lease->fl_lmops->lm_setup(lease, priv);
1731out:
1732 spin_unlock(&ctx->flc_lock);
1733 locks_dispose_list(&dispose);
1734 if (is_deleg)
1735 inode_unlock(inode);
1736 if (!error && !my_fl)
1737 *flp = NULL;
1738 return error;
1739}
1740
1741static int generic_delete_lease(struct file *filp, void *owner)
1742{
1743 int error = -EAGAIN;
1744 struct file_lock *fl, *victim = NULL;
1745 struct inode *inode = file_inode(filp);
1746 struct file_lock_context *ctx;
1747 LIST_HEAD(dispose);
1748
1749 ctx = smp_load_acquire(&inode->i_flctx);
1750 if (!ctx) {
1751 trace_generic_delete_lease(inode, NULL);
1752 return error;
1753 }
1754
1755 spin_lock(&ctx->flc_lock);
1756 list_for_each_entry(fl, &ctx->flc_lease, fl_list) {
1757 if (fl->fl_file == filp &&
1758 fl->fl_owner == owner) {
1759 victim = fl;
1760 break;
1761 }
1762 }
1763 trace_generic_delete_lease(inode, victim);
1764 if (victim)
1765 error = fl->fl_lmops->lm_change(victim, F_UNLCK, &dispose);
1766 spin_unlock(&ctx->flc_lock);
1767 locks_dispose_list(&dispose);
1768 return error;
1769}
1770
1771/**
1772 * generic_setlease - sets a lease on an open file
1773 * @filp: file pointer
1774 * @arg: type of lease to obtain
1775 * @flp: input - file_lock to use, output - file_lock inserted
1776 * @priv: private data for lm_setup (may be NULL if lm_setup
1777 * doesn't require it)
1778 *
1779 * The (input) flp->fl_lmops->lm_break function is required
1780 * by break_lease().
1781 */
1782int generic_setlease(struct file *filp, long arg, struct file_lock **flp,
1783 void **priv)
1784{
1785 struct inode *inode = file_inode(filp);
1786 int error;
1787
1788 if ((!uid_eq(current_fsuid(), inode->i_uid)) && !capable(CAP_LEASE))
1789 return -EACCES;
1790 if (!S_ISREG(inode->i_mode))
1791 return -EINVAL;
1792 error = security_file_lock(filp, arg);
1793 if (error)
1794 return error;
1795
1796 switch (arg) {
1797 case F_UNLCK:
1798 return generic_delete_lease(filp, *priv);
1799 case F_RDLCK:
1800 case F_WRLCK:
1801 if (!(*flp)->fl_lmops->lm_break) {
1802 WARN_ON_ONCE(1);
1803 return -ENOLCK;
1804 }
1805
1806 return generic_add_lease(filp, arg, flp, priv);
1807 default:
1808 return -EINVAL;
1809 }
1810}
1811EXPORT_SYMBOL(generic_setlease);
1812
1813/**
1814 * vfs_setlease - sets a lease on an open file
1815 * @filp: file pointer
1816 * @arg: type of lease to obtain
1817 * @lease: file_lock to use when adding a lease
1818 * @priv: private info for lm_setup when adding a lease (may be
1819 * NULL if lm_setup doesn't require it)
1820 *
1821 * Call this to establish a lease on the file. The "lease" argument is not
1822 * used for F_UNLCK requests and may be NULL. For commands that set or alter
1823 * an existing lease, the (*lease)->fl_lmops->lm_break operation must be set;
1824 * if not, this function will return -ENOLCK (and generate a scary-looking
1825 * stack trace).
1826 *
1827 * The "priv" pointer is passed directly to the lm_setup function as-is. It
1828 * may be NULL if the lm_setup operation doesn't require it.
1829 */
1830int
1831vfs_setlease(struct file *filp, long arg, struct file_lock **lease, void **priv)
1832{
1833 if (filp->f_op->setlease)
1834 return filp->f_op->setlease(filp, arg, lease, priv);
1835 else
1836 return generic_setlease(filp, arg, lease, priv);
1837}
1838EXPORT_SYMBOL_GPL(vfs_setlease);
1839
1840static int do_fcntl_add_lease(unsigned int fd, struct file *filp, long arg)
1841{
1842 struct file_lock *fl;
1843 struct fasync_struct *new;
1844 int error;
1845
1846 fl = lease_alloc(filp, arg);
1847 if (IS_ERR(fl))
1848 return PTR_ERR(fl);
1849
1850 new = fasync_alloc();
1851 if (!new) {
1852 locks_free_lock(fl);
1853 return -ENOMEM;
1854 }
1855 new->fa_fd = fd;
1856
1857 error = vfs_setlease(filp, arg, &fl, (void **)&new);
1858 if (fl)
1859 locks_free_lock(fl);
1860 if (new)
1861 fasync_free(new);
1862 return error;
1863}
1864
1865/**
1866 * fcntl_setlease - sets a lease on an open file
1867 * @fd: open file descriptor
1868 * @filp: file pointer
1869 * @arg: type of lease to obtain
1870 *
1871 * Call this fcntl to establish a lease on the file.
1872 * Note that you also need to call %F_SETSIG to
1873 * receive a signal when the lease is broken.
1874 */
1875int fcntl_setlease(unsigned int fd, struct file *filp, long arg)
1876{
1877 if (arg == F_UNLCK)
1878 return vfs_setlease(filp, F_UNLCK, NULL, (void **)&filp);
1879 return do_fcntl_add_lease(fd, filp, arg);
1880}
1881
1882/**
1883 * flock_lock_inode_wait - Apply a FLOCK-style lock to a file
1884 * @inode: inode of the file to apply to
1885 * @fl: The lock to be applied
1886 *
1887 * Apply a FLOCK style lock request to an inode.
1888 */
1889static int flock_lock_inode_wait(struct inode *inode, struct file_lock *fl)
1890{
1891 int error;
1892 might_sleep();
1893 for (;;) {
1894 error = flock_lock_inode(inode, fl);
1895 if (error != FILE_LOCK_DEFERRED)
1896 break;
1897 error = wait_event_interruptible(fl->fl_wait, !fl->fl_next);
1898 if (!error)
1899 continue;
1900
1901 locks_delete_block(fl);
1902 break;
1903 }
1904 return error;
1905}
1906
1907/**
1908 * locks_lock_inode_wait - Apply a lock to an inode
1909 * @inode: inode of the file to apply to
1910 * @fl: The lock to be applied
1911 *
1912 * Apply a POSIX or FLOCK style lock request to an inode.
1913 */
1914int locks_lock_inode_wait(struct inode *inode, struct file_lock *fl)
1915{
1916 int res = 0;
1917 switch (fl->fl_flags & (FL_POSIX|FL_FLOCK)) {
1918 case FL_POSIX:
1919 res = posix_lock_inode_wait(inode, fl);
1920 break;
1921 case FL_FLOCK:
1922 res = flock_lock_inode_wait(inode, fl);
1923 break;
1924 default:
1925 BUG();
1926 }
1927 return res;
1928}
1929EXPORT_SYMBOL(locks_lock_inode_wait);
1930
1931/**
1932 * sys_flock: - flock() system call.
1933 * @fd: the file descriptor to lock.
1934 * @cmd: the type of lock to apply.
1935 *
1936 * Apply a %FL_FLOCK style lock to an open file descriptor.
1937 * The @cmd can be one of
1938 *
1939 * %LOCK_SH -- a shared lock.
1940 *
1941 * %LOCK_EX -- an exclusive lock.
1942 *
1943 * %LOCK_UN -- remove an existing lock.
1944 *
1945 * %LOCK_MAND -- a `mandatory' flock. This exists to emulate Windows Share Modes.
1946 *
1947 * %LOCK_MAND can be combined with %LOCK_READ or %LOCK_WRITE to allow other
1948 * processes read and write access respectively.
1949 */
1950SYSCALL_DEFINE2(flock, unsigned int, fd, unsigned int, cmd)
1951{
1952 struct fd f = fdget(fd);
1953 struct file_lock *lock;
1954 int can_sleep, unlock;
1955 int error;
1956
1957 error = -EBADF;
1958 if (!f.file)
1959 goto out;
1960
1961 can_sleep = !(cmd & LOCK_NB);
1962 cmd &= ~LOCK_NB;
1963 unlock = (cmd == LOCK_UN);
1964
1965 if (!unlock && !(cmd & LOCK_MAND) &&
1966 !(f.file->f_mode & (FMODE_READ|FMODE_WRITE)))
1967 goto out_putf;
1968
1969 lock = flock_make_lock(f.file, cmd);
1970 if (IS_ERR(lock)) {
1971 error = PTR_ERR(lock);
1972 goto out_putf;
1973 }
1974
1975 if (can_sleep)
1976 lock->fl_flags |= FL_SLEEP;
1977
1978 error = security_file_lock(f.file, lock->fl_type);
1979 if (error)
1980 goto out_free;
1981
1982 if (f.file->f_op->flock)
1983 error = f.file->f_op->flock(f.file,
1984 (can_sleep) ? F_SETLKW : F_SETLK,
1985 lock);
1986 else
1987 error = locks_lock_file_wait(f.file, lock);
1988
1989 out_free:
1990 locks_free_lock(lock);
1991
1992 out_putf:
1993 fdput(f);
1994 out:
1995 return error;
1996}
1997
1998/**
1999 * vfs_test_lock - test file byte range lock
2000 * @filp: The file to test lock for
2001 * @fl: The lock to test; also used to hold result
2002 *
2003 * Returns -ERRNO on failure. Indicates presence of conflicting lock by
2004 * setting conf->fl_type to something other than F_UNLCK.
2005 */
2006int vfs_test_lock(struct file *filp, struct file_lock *fl)
2007{
2008 if (filp->f_op->lock)
2009 return filp->f_op->lock(filp, F_GETLK, fl);
2010 posix_test_lock(filp, fl);
2011 return 0;
2012}
2013EXPORT_SYMBOL_GPL(vfs_test_lock);
2014
2015static int posix_lock_to_flock(struct flock *flock, struct file_lock *fl)
2016{
2017 flock->l_pid = IS_OFDLCK(fl) ? -1 : fl->fl_pid;
2018#if BITS_PER_LONG == 32
2019 /*
2020 * Make sure we can represent the posix lock via
2021 * legacy 32bit flock.
2022 */
2023 if (fl->fl_start > OFFT_OFFSET_MAX)
2024 return -EOVERFLOW;
2025 if (fl->fl_end != OFFSET_MAX && fl->fl_end > OFFT_OFFSET_MAX)
2026 return -EOVERFLOW;
2027#endif
2028 flock->l_start = fl->fl_start;
2029 flock->l_len = fl->fl_end == OFFSET_MAX ? 0 :
2030 fl->fl_end - fl->fl_start + 1;
2031 flock->l_whence = 0;
2032 flock->l_type = fl->fl_type;
2033 return 0;
2034}
2035
2036#if BITS_PER_LONG == 32
2037static void posix_lock_to_flock64(struct flock64 *flock, struct file_lock *fl)
2038{
2039 flock->l_pid = IS_OFDLCK(fl) ? -1 : fl->fl_pid;
2040 flock->l_start = fl->fl_start;
2041 flock->l_len = fl->fl_end == OFFSET_MAX ? 0 :
2042 fl->fl_end - fl->fl_start + 1;
2043 flock->l_whence = 0;
2044 flock->l_type = fl->fl_type;
2045}
2046#endif
2047
2048/* Report the first existing lock that would conflict with l.
2049 * This implements the F_GETLK command of fcntl().
2050 */
2051int fcntl_getlk(struct file *filp, unsigned int cmd, struct flock __user *l)
2052{
2053 struct file_lock file_lock;
2054 struct flock flock;
2055 int error;
2056
2057 error = -EFAULT;
2058 if (copy_from_user(&flock, l, sizeof(flock)))
2059 goto out;
2060 error = -EINVAL;
2061 if ((flock.l_type != F_RDLCK) && (flock.l_type != F_WRLCK))
2062 goto out;
2063
2064 error = flock_to_posix_lock(filp, &file_lock, &flock);
2065 if (error)
2066 goto out;
2067
2068 if (cmd == F_OFD_GETLK) {
2069 error = -EINVAL;
2070 if (flock.l_pid != 0)
2071 goto out;
2072
2073 cmd = F_GETLK;
2074 file_lock.fl_flags |= FL_OFDLCK;
2075 file_lock.fl_owner = filp;
2076 }
2077
2078 error = vfs_test_lock(filp, &file_lock);
2079 if (error)
2080 goto out;
2081
2082 flock.l_type = file_lock.fl_type;
2083 if (file_lock.fl_type != F_UNLCK) {
2084 error = posix_lock_to_flock(&flock, &file_lock);
2085 if (error)
2086 goto rel_priv;
2087 }
2088 error = -EFAULT;
2089 if (!copy_to_user(l, &flock, sizeof(flock)))
2090 error = 0;
2091rel_priv:
2092 locks_release_private(&file_lock);
2093out:
2094 return error;
2095}
2096
2097/**
2098 * vfs_lock_file - file byte range lock
2099 * @filp: The file to apply the lock to
2100 * @cmd: type of locking operation (F_SETLK, F_GETLK, etc.)
2101 * @fl: The lock to be applied
2102 * @conf: Place to return a copy of the conflicting lock, if found.
2103 *
2104 * A caller that doesn't care about the conflicting lock may pass NULL
2105 * as the final argument.
2106 *
2107 * If the filesystem defines a private ->lock() method, then @conf will
2108 * be left unchanged; so a caller that cares should initialize it to
2109 * some acceptable default.
2110 *
2111 * To avoid blocking kernel daemons, such as lockd, that need to acquire POSIX
2112 * locks, the ->lock() interface may return asynchronously, before the lock has
2113 * been granted or denied by the underlying filesystem, if (and only if)
2114 * lm_grant is set. Callers expecting ->lock() to return asynchronously
2115 * will only use F_SETLK, not F_SETLKW; they will set FL_SLEEP if (and only if)
2116 * the request is for a blocking lock. When ->lock() does return asynchronously,
2117 * it must return FILE_LOCK_DEFERRED, and call ->lm_grant() when the lock
2118 * request completes.
2119 * If the request is for non-blocking lock the file system should return
2120 * FILE_LOCK_DEFERRED then try to get the lock and call the callback routine
2121 * with the result. If the request timed out the callback routine will return a
2122 * nonzero return code and the file system should release the lock. The file
2123 * system is also responsible to keep a corresponding posix lock when it
2124 * grants a lock so the VFS can find out which locks are locally held and do
2125 * the correct lock cleanup when required.
2126 * The underlying filesystem must not drop the kernel lock or call
2127 * ->lm_grant() before returning to the caller with a FILE_LOCK_DEFERRED
2128 * return code.
2129 */
2130int vfs_lock_file(struct file *filp, unsigned int cmd, struct file_lock *fl, struct file_lock *conf)
2131{
2132 if (filp->f_op->lock)
2133 return filp->f_op->lock(filp, cmd, fl);
2134 else
2135 return posix_lock_file(filp, fl, conf);
2136}
2137EXPORT_SYMBOL_GPL(vfs_lock_file);
2138
2139static int do_lock_file_wait(struct file *filp, unsigned int cmd,
2140 struct file_lock *fl)
2141{
2142 int error;
2143
2144 error = security_file_lock(filp, fl->fl_type);
2145 if (error)
2146 return error;
2147
2148 for (;;) {
2149 error = vfs_lock_file(filp, cmd, fl, NULL);
2150 if (error != FILE_LOCK_DEFERRED)
2151 break;
2152 error = wait_event_interruptible(fl->fl_wait, !fl->fl_next);
2153 if (!error)
2154 continue;
2155
2156 locks_delete_block(fl);
2157 break;
2158 }
2159
2160 return error;
2161}
2162
2163/* Ensure that fl->fl_file has compatible f_mode for F_SETLK calls */
2164static int
2165check_fmode_for_setlk(struct file_lock *fl)
2166{
2167 switch (fl->fl_type) {
2168 case F_RDLCK:
2169 if (!(fl->fl_file->f_mode & FMODE_READ))
2170 return -EBADF;
2171 break;
2172 case F_WRLCK:
2173 if (!(fl->fl_file->f_mode & FMODE_WRITE))
2174 return -EBADF;
2175 }
2176 return 0;
2177}
2178
2179/* Apply the lock described by l to an open file descriptor.
2180 * This implements both the F_SETLK and F_SETLKW commands of fcntl().
2181 */
2182int fcntl_setlk(unsigned int fd, struct file *filp, unsigned int cmd,
2183 struct flock __user *l)
2184{
2185 struct file_lock *file_lock = locks_alloc_lock();
2186 struct flock flock;
2187 struct inode *inode;
2188 struct file *f;
2189 int error;
2190
2191 if (file_lock == NULL)
2192 return -ENOLCK;
2193
2194 inode = file_inode(filp);
2195
2196 /*
2197 * This might block, so we do it before checking the inode.
2198 */
2199 error = -EFAULT;
2200 if (copy_from_user(&flock, l, sizeof(flock)))
2201 goto out;
2202
2203 /* Don't allow mandatory locks on files that may be memory mapped
2204 * and shared.
2205 */
2206 if (mandatory_lock(inode) && mapping_writably_mapped(filp->f_mapping)) {
2207 error = -EAGAIN;
2208 goto out;
2209 }
2210
2211 error = flock_to_posix_lock(filp, file_lock, &flock);
2212 if (error)
2213 goto out;
2214
2215 error = check_fmode_for_setlk(file_lock);
2216 if (error)
2217 goto out;
2218
2219 /*
2220 * If the cmd is requesting file-private locks, then set the
2221 * FL_OFDLCK flag and override the owner.
2222 */
2223 switch (cmd) {
2224 case F_OFD_SETLK:
2225 error = -EINVAL;
2226 if (flock.l_pid != 0)
2227 goto out;
2228
2229 cmd = F_SETLK;
2230 file_lock->fl_flags |= FL_OFDLCK;
2231 file_lock->fl_owner = filp;
2232 break;
2233 case F_OFD_SETLKW:
2234 error = -EINVAL;
2235 if (flock.l_pid != 0)
2236 goto out;
2237
2238 cmd = F_SETLKW;
2239 file_lock->fl_flags |= FL_OFDLCK;
2240 file_lock->fl_owner = filp;
2241 /* Fallthrough */
2242 case F_SETLKW:
2243 file_lock->fl_flags |= FL_SLEEP;
2244 }
2245
2246 error = do_lock_file_wait(filp, cmd, file_lock);
2247
2248 /*
2249 * Attempt to detect a close/fcntl race and recover by releasing the
2250 * lock that was just acquired. There is no need to do that when we're
2251 * unlocking though, or for OFD locks.
2252 */
2253 if (!error && file_lock->fl_type != F_UNLCK &&
2254 !(file_lock->fl_flags & FL_OFDLCK)) {
2255 /*
2256 * We need that spin_lock here - it prevents reordering between
2257 * update of i_flctx->flc_posix and check for it done in
2258 * close(). rcu_read_lock() wouldn't do.
2259 */
2260 spin_lock(¤t->files->file_lock);
2261 f = fcheck(fd);
2262 spin_unlock(¤t->files->file_lock);
2263 if (f != filp) {
2264 file_lock->fl_type = F_UNLCK;
2265 error = do_lock_file_wait(filp, cmd, file_lock);
2266 WARN_ON_ONCE(error);
2267 error = -EBADF;
2268 }
2269 }
2270out:
2271 trace_fcntl_setlk(inode, file_lock, error);
2272 locks_free_lock(file_lock);
2273 return error;
2274}
2275
2276#if BITS_PER_LONG == 32
2277/* Report the first existing lock that would conflict with l.
2278 * This implements the F_GETLK command of fcntl().
2279 */
2280int fcntl_getlk64(struct file *filp, unsigned int cmd, struct flock64 __user *l)
2281{
2282 struct file_lock file_lock;
2283 struct flock64 flock;
2284 int error;
2285
2286 error = -EFAULT;
2287 if (copy_from_user(&flock, l, sizeof(flock)))
2288 goto out;
2289 error = -EINVAL;
2290 if ((flock.l_type != F_RDLCK) && (flock.l_type != F_WRLCK))
2291 goto out;
2292
2293 error = flock64_to_posix_lock(filp, &file_lock, &flock);
2294 if (error)
2295 goto out;
2296
2297 if (cmd == F_OFD_GETLK) {
2298 error = -EINVAL;
2299 if (flock.l_pid != 0)
2300 goto out;
2301
2302 cmd = F_GETLK64;
2303 file_lock.fl_flags |= FL_OFDLCK;
2304 file_lock.fl_owner = filp;
2305 }
2306
2307 error = vfs_test_lock(filp, &file_lock);
2308 if (error)
2309 goto out;
2310
2311 flock.l_type = file_lock.fl_type;
2312 if (file_lock.fl_type != F_UNLCK)
2313 posix_lock_to_flock64(&flock, &file_lock);
2314
2315 error = -EFAULT;
2316 if (!copy_to_user(l, &flock, sizeof(flock)))
2317 error = 0;
2318
2319 locks_release_private(&file_lock);
2320out:
2321 return error;
2322}
2323
2324/* Apply the lock described by l to an open file descriptor.
2325 * This implements both the F_SETLK and F_SETLKW commands of fcntl().
2326 */
2327int fcntl_setlk64(unsigned int fd, struct file *filp, unsigned int cmd,
2328 struct flock64 __user *l)
2329{
2330 struct file_lock *file_lock = locks_alloc_lock();
2331 struct flock64 flock;
2332 struct inode *inode;
2333 struct file *f;
2334 int error;
2335
2336 if (file_lock == NULL)
2337 return -ENOLCK;
2338
2339 /*
2340 * This might block, so we do it before checking the inode.
2341 */
2342 error = -EFAULT;
2343 if (copy_from_user(&flock, l, sizeof(flock)))
2344 goto out;
2345
2346 inode = file_inode(filp);
2347
2348 /* Don't allow mandatory locks on files that may be memory mapped
2349 * and shared.
2350 */
2351 if (mandatory_lock(inode) && mapping_writably_mapped(filp->f_mapping)) {
2352 error = -EAGAIN;
2353 goto out;
2354 }
2355
2356 error = flock64_to_posix_lock(filp, file_lock, &flock);
2357 if (error)
2358 goto out;
2359
2360 error = check_fmode_for_setlk(file_lock);
2361 if (error)
2362 goto out;
2363
2364 /*
2365 * If the cmd is requesting file-private locks, then set the
2366 * FL_OFDLCK flag and override the owner.
2367 */
2368 switch (cmd) {
2369 case F_OFD_SETLK:
2370 error = -EINVAL;
2371 if (flock.l_pid != 0)
2372 goto out;
2373
2374 cmd = F_SETLK64;
2375 file_lock->fl_flags |= FL_OFDLCK;
2376 file_lock->fl_owner = filp;
2377 break;
2378 case F_OFD_SETLKW:
2379 error = -EINVAL;
2380 if (flock.l_pid != 0)
2381 goto out;
2382
2383 cmd = F_SETLKW64;
2384 file_lock->fl_flags |= FL_OFDLCK;
2385 file_lock->fl_owner = filp;
2386 /* Fallthrough */
2387 case F_SETLKW64:
2388 file_lock->fl_flags |= FL_SLEEP;
2389 }
2390
2391 error = do_lock_file_wait(filp, cmd, file_lock);
2392
2393 /*
2394 * Attempt to detect a close/fcntl race and recover by releasing the
2395 * lock that was just acquired. There is no need to do that when we're
2396 * unlocking though, or for OFD locks.
2397 */
2398 if (!error && file_lock->fl_type != F_UNLCK &&
2399 !(file_lock->fl_flags & FL_OFDLCK)) {
2400 /*
2401 * We need that spin_lock here - it prevents reordering between
2402 * update of i_flctx->flc_posix and check for it done in
2403 * close(). rcu_read_lock() wouldn't do.
2404 */
2405 spin_lock(¤t->files->file_lock);
2406 f = fcheck(fd);
2407 spin_unlock(¤t->files->file_lock);
2408 if (f != filp) {
2409 file_lock->fl_type = F_UNLCK;
2410 error = do_lock_file_wait(filp, cmd, file_lock);
2411 WARN_ON_ONCE(error);
2412 error = -EBADF;
2413 }
2414 }
2415out:
2416 locks_free_lock(file_lock);
2417 return error;
2418}
2419#endif /* BITS_PER_LONG == 32 */
2420
2421/*
2422 * This function is called when the file is being removed
2423 * from the task's fd array. POSIX locks belonging to this task
2424 * are deleted at this time.
2425 */
2426void locks_remove_posix(struct file *filp, fl_owner_t owner)
2427{
2428 int error;
2429 struct file_lock lock;
2430 struct file_lock_context *ctx;
2431
2432 /*
2433 * If there are no locks held on this file, we don't need to call
2434 * posix_lock_file(). Another process could be setting a lock on this
2435 * file at the same time, but we wouldn't remove that lock anyway.
2436 */
2437 ctx = smp_load_acquire(&file_inode(filp)->i_flctx);
2438 if (!ctx || list_empty(&ctx->flc_posix))
2439 return;
2440
2441 lock.fl_type = F_UNLCK;
2442 lock.fl_flags = FL_POSIX | FL_CLOSE;
2443 lock.fl_start = 0;
2444 lock.fl_end = OFFSET_MAX;
2445 lock.fl_owner = owner;
2446 lock.fl_pid = current->tgid;
2447 lock.fl_file = filp;
2448 lock.fl_ops = NULL;
2449 lock.fl_lmops = NULL;
2450
2451 error = vfs_lock_file(filp, F_SETLK, &lock, NULL);
2452
2453 if (lock.fl_ops && lock.fl_ops->fl_release_private)
2454 lock.fl_ops->fl_release_private(&lock);
2455 trace_locks_remove_posix(file_inode(filp), &lock, error);
2456}
2457
2458EXPORT_SYMBOL(locks_remove_posix);
2459
2460/* The i_flctx must be valid when calling into here */
2461static void
2462locks_remove_flock(struct file *filp, struct file_lock_context *flctx)
2463{
2464 struct file_lock fl = {
2465 .fl_owner = filp,
2466 .fl_pid = current->tgid,
2467 .fl_file = filp,
2468 .fl_flags = FL_FLOCK,
2469 .fl_type = F_UNLCK,
2470 .fl_end = OFFSET_MAX,
2471 };
2472 struct inode *inode = file_inode(filp);
2473
2474 if (list_empty(&flctx->flc_flock))
2475 return;
2476
2477 if (filp->f_op->flock)
2478 filp->f_op->flock(filp, F_SETLKW, &fl);
2479 else
2480 flock_lock_inode(inode, &fl);
2481
2482 if (fl.fl_ops && fl.fl_ops->fl_release_private)
2483 fl.fl_ops->fl_release_private(&fl);
2484}
2485
2486/* The i_flctx must be valid when calling into here */
2487static void
2488locks_remove_lease(struct file *filp, struct file_lock_context *ctx)
2489{
2490 struct file_lock *fl, *tmp;
2491 LIST_HEAD(dispose);
2492
2493 if (list_empty(&ctx->flc_lease))
2494 return;
2495
2496 spin_lock(&ctx->flc_lock);
2497 list_for_each_entry_safe(fl, tmp, &ctx->flc_lease, fl_list)
2498 if (filp == fl->fl_file)
2499 lease_modify(fl, F_UNLCK, &dispose);
2500 spin_unlock(&ctx->flc_lock);
2501 locks_dispose_list(&dispose);
2502}
2503
2504/*
2505 * This function is called on the last close of an open file.
2506 */
2507void locks_remove_file(struct file *filp)
2508{
2509 struct file_lock_context *ctx;
2510
2511 ctx = smp_load_acquire(&file_inode(filp)->i_flctx);
2512 if (!ctx)
2513 return;
2514
2515 /* remove any OFD locks */
2516 locks_remove_posix(filp, filp);
2517
2518 /* remove flock locks */
2519 locks_remove_flock(filp, ctx);
2520
2521 /* remove any leases */
2522 locks_remove_lease(filp, ctx);
2523}
2524
2525/**
2526 * posix_unblock_lock - stop waiting for a file lock
2527 * @waiter: the lock which was waiting
2528 *
2529 * lockd needs to block waiting for locks.
2530 */
2531int
2532posix_unblock_lock(struct file_lock *waiter)
2533{
2534 int status = 0;
2535
2536 spin_lock(&blocked_lock_lock);
2537 if (waiter->fl_next)
2538 __locks_delete_block(waiter);
2539 else
2540 status = -ENOENT;
2541 spin_unlock(&blocked_lock_lock);
2542 return status;
2543}
2544EXPORT_SYMBOL(posix_unblock_lock);
2545
2546/**
2547 * vfs_cancel_lock - file byte range unblock lock
2548 * @filp: The file to apply the unblock to
2549 * @fl: The lock to be unblocked
2550 *
2551 * Used by lock managers to cancel blocked requests
2552 */
2553int vfs_cancel_lock(struct file *filp, struct file_lock *fl)
2554{
2555 if (filp->f_op->lock)
2556 return filp->f_op->lock(filp, F_CANCELLK, fl);
2557 return 0;
2558}
2559
2560EXPORT_SYMBOL_GPL(vfs_cancel_lock);
2561
2562#ifdef CONFIG_PROC_FS
2563#include <linux/proc_fs.h>
2564#include <linux/seq_file.h>
2565
2566struct locks_iterator {
2567 int li_cpu;
2568 loff_t li_pos;
2569};
2570
2571static void lock_get_status(struct seq_file *f, struct file_lock *fl,
2572 loff_t id, char *pfx)
2573{
2574 struct inode *inode = NULL;
2575 unsigned int fl_pid;
2576
2577 if (fl->fl_nspid)
2578 fl_pid = pid_vnr(fl->fl_nspid);
2579 else
2580 fl_pid = fl->fl_pid;
2581
2582 if (fl->fl_file != NULL)
2583 inode = file_inode(fl->fl_file);
2584
2585 seq_printf(f, "%lld:%s ", id, pfx);
2586 if (IS_POSIX(fl)) {
2587 if (fl->fl_flags & FL_ACCESS)
2588 seq_puts(f, "ACCESS");
2589 else if (IS_OFDLCK(fl))
2590 seq_puts(f, "OFDLCK");
2591 else
2592 seq_puts(f, "POSIX ");
2593
2594 seq_printf(f, " %s ",
2595 (inode == NULL) ? "*NOINODE*" :
2596 mandatory_lock(inode) ? "MANDATORY" : "ADVISORY ");
2597 } else if (IS_FLOCK(fl)) {
2598 if (fl->fl_type & LOCK_MAND) {
2599 seq_puts(f, "FLOCK MSNFS ");
2600 } else {
2601 seq_puts(f, "FLOCK ADVISORY ");
2602 }
2603 } else if (IS_LEASE(fl)) {
2604 if (fl->fl_flags & FL_DELEG)
2605 seq_puts(f, "DELEG ");
2606 else
2607 seq_puts(f, "LEASE ");
2608
2609 if (lease_breaking(fl))
2610 seq_puts(f, "BREAKING ");
2611 else if (fl->fl_file)
2612 seq_puts(f, "ACTIVE ");
2613 else
2614 seq_puts(f, "BREAKER ");
2615 } else {
2616 seq_puts(f, "UNKNOWN UNKNOWN ");
2617 }
2618 if (fl->fl_type & LOCK_MAND) {
2619 seq_printf(f, "%s ",
2620 (fl->fl_type & LOCK_READ)
2621 ? (fl->fl_type & LOCK_WRITE) ? "RW " : "READ "
2622 : (fl->fl_type & LOCK_WRITE) ? "WRITE" : "NONE ");
2623 } else {
2624 seq_printf(f, "%s ",
2625 (lease_breaking(fl))
2626 ? (fl->fl_type == F_UNLCK) ? "UNLCK" : "READ "
2627 : (fl->fl_type == F_WRLCK) ? "WRITE" : "READ ");
2628 }
2629 if (inode) {
2630 /* userspace relies on this representation of dev_t */
2631 seq_printf(f, "%d %02x:%02x:%ld ", fl_pid,
2632 MAJOR(inode->i_sb->s_dev),
2633 MINOR(inode->i_sb->s_dev), inode->i_ino);
2634 } else {
2635 seq_printf(f, "%d <none>:0 ", fl_pid);
2636 }
2637 if (IS_POSIX(fl)) {
2638 if (fl->fl_end == OFFSET_MAX)
2639 seq_printf(f, "%Ld EOF\n", fl->fl_start);
2640 else
2641 seq_printf(f, "%Ld %Ld\n", fl->fl_start, fl->fl_end);
2642 } else {
2643 seq_puts(f, "0 EOF\n");
2644 }
2645}
2646
2647static int locks_show(struct seq_file *f, void *v)
2648{
2649 struct locks_iterator *iter = f->private;
2650 struct file_lock *fl, *bfl;
2651
2652 fl = hlist_entry(v, struct file_lock, fl_link);
2653
2654 lock_get_status(f, fl, iter->li_pos, "");
2655
2656 list_for_each_entry(bfl, &fl->fl_block, fl_block)
2657 lock_get_status(f, bfl, iter->li_pos, " ->");
2658
2659 return 0;
2660}
2661
2662static void __show_fd_locks(struct seq_file *f,
2663 struct list_head *head, int *id,
2664 struct file *filp, struct files_struct *files)
2665{
2666 struct file_lock *fl;
2667
2668 list_for_each_entry(fl, head, fl_list) {
2669
2670 if (filp != fl->fl_file)
2671 continue;
2672 if (fl->fl_owner != files &&
2673 fl->fl_owner != filp)
2674 continue;
2675
2676 (*id)++;
2677 seq_puts(f, "lock:\t");
2678 lock_get_status(f, fl, *id, "");
2679 }
2680}
2681
2682void show_fd_locks(struct seq_file *f,
2683 struct file *filp, struct files_struct *files)
2684{
2685 struct inode *inode = file_inode(filp);
2686 struct file_lock_context *ctx;
2687 int id = 0;
2688
2689 ctx = smp_load_acquire(&inode->i_flctx);
2690 if (!ctx)
2691 return;
2692
2693 spin_lock(&ctx->flc_lock);
2694 __show_fd_locks(f, &ctx->flc_flock, &id, filp, files);
2695 __show_fd_locks(f, &ctx->flc_posix, &id, filp, files);
2696 __show_fd_locks(f, &ctx->flc_lease, &id, filp, files);
2697 spin_unlock(&ctx->flc_lock);
2698}
2699
2700static void *locks_start(struct seq_file *f, loff_t *pos)
2701 __acquires(&blocked_lock_lock)
2702{
2703 struct locks_iterator *iter = f->private;
2704
2705 iter->li_pos = *pos + 1;
2706 lg_global_lock(&file_lock_lglock);
2707 spin_lock(&blocked_lock_lock);
2708 return seq_hlist_start_percpu(&file_lock_list, &iter->li_cpu, *pos);
2709}
2710
2711static void *locks_next(struct seq_file *f, void *v, loff_t *pos)
2712{
2713 struct locks_iterator *iter = f->private;
2714
2715 ++iter->li_pos;
2716 return seq_hlist_next_percpu(v, &file_lock_list, &iter->li_cpu, pos);
2717}
2718
2719static void locks_stop(struct seq_file *f, void *v)
2720 __releases(&blocked_lock_lock)
2721{
2722 spin_unlock(&blocked_lock_lock);
2723 lg_global_unlock(&file_lock_lglock);
2724}
2725
2726static const struct seq_operations locks_seq_operations = {
2727 .start = locks_start,
2728 .next = locks_next,
2729 .stop = locks_stop,
2730 .show = locks_show,
2731};
2732
2733static int locks_open(struct inode *inode, struct file *filp)
2734{
2735 return seq_open_private(filp, &locks_seq_operations,
2736 sizeof(struct locks_iterator));
2737}
2738
2739static const struct file_operations proc_locks_operations = {
2740 .open = locks_open,
2741 .read = seq_read,
2742 .llseek = seq_lseek,
2743 .release = seq_release_private,
2744};
2745
2746static int __init proc_locks_init(void)
2747{
2748 proc_create("locks", 0, NULL, &proc_locks_operations);
2749 return 0;
2750}
2751fs_initcall(proc_locks_init);
2752#endif
2753
2754static int __init filelock_init(void)
2755{
2756 int i;
2757
2758 flctx_cache = kmem_cache_create("file_lock_ctx",
2759 sizeof(struct file_lock_context), 0, SLAB_PANIC, NULL);
2760
2761 filelock_cache = kmem_cache_create("file_lock_cache",
2762 sizeof(struct file_lock), 0, SLAB_PANIC, NULL);
2763
2764 lg_lock_init(&file_lock_lglock, "file_lock_lglock");
2765
2766 for_each_possible_cpu(i)
2767 INIT_HLIST_HEAD(per_cpu_ptr(&file_lock_list, i));
2768
2769 return 0;
2770}
2771
2772core_initcall(filelock_init);
1/*
2 * linux/fs/locks.c
3 *
4 * Provide support for fcntl()'s F_GETLK, F_SETLK, and F_SETLKW calls.
5 * Doug Evans (dje@spiff.uucp), August 07, 1992
6 *
7 * Deadlock detection added.
8 * FIXME: one thing isn't handled yet:
9 * - mandatory locks (requires lots of changes elsewhere)
10 * Kelly Carmichael (kelly@[142.24.8.65]), September 17, 1994.
11 *
12 * Miscellaneous edits, and a total rewrite of posix_lock_file() code.
13 * Kai Petzke (wpp@marie.physik.tu-berlin.de), 1994
14 *
15 * Converted file_lock_table to a linked list from an array, which eliminates
16 * the limits on how many active file locks are open.
17 * Chad Page (pageone@netcom.com), November 27, 1994
18 *
19 * Removed dependency on file descriptors. dup()'ed file descriptors now
20 * get the same locks as the original file descriptors, and a close() on
21 * any file descriptor removes ALL the locks on the file for the current
22 * process. Since locks still depend on the process id, locks are inherited
23 * after an exec() but not after a fork(). This agrees with POSIX, and both
24 * BSD and SVR4 practice.
25 * Andy Walker (andy@lysaker.kvaerner.no), February 14, 1995
26 *
27 * Scrapped free list which is redundant now that we allocate locks
28 * dynamically with kmalloc()/kfree().
29 * Andy Walker (andy@lysaker.kvaerner.no), February 21, 1995
30 *
31 * Implemented two lock personalities - FL_FLOCK and FL_POSIX.
32 *
33 * FL_POSIX locks are created with calls to fcntl() and lockf() through the
34 * fcntl() system call. They have the semantics described above.
35 *
36 * FL_FLOCK locks are created with calls to flock(), through the flock()
37 * system call, which is new. Old C libraries implement flock() via fcntl()
38 * and will continue to use the old, broken implementation.
39 *
40 * FL_FLOCK locks follow the 4.4 BSD flock() semantics. They are associated
41 * with a file pointer (filp). As a result they can be shared by a parent
42 * process and its children after a fork(). They are removed when the last
43 * file descriptor referring to the file pointer is closed (unless explicitly
44 * unlocked).
45 *
46 * FL_FLOCK locks never deadlock, an existing lock is always removed before
47 * upgrading from shared to exclusive (or vice versa). When this happens
48 * any processes blocked by the current lock are woken up and allowed to
49 * run before the new lock is applied.
50 * Andy Walker (andy@lysaker.kvaerner.no), June 09, 1995
51 *
52 * Removed some race conditions in flock_lock_file(), marked other possible
53 * races. Just grep for FIXME to see them.
54 * Dmitry Gorodchanin (pgmdsg@ibi.com), February 09, 1996.
55 *
56 * Addressed Dmitry's concerns. Deadlock checking no longer recursive.
57 * Lock allocation changed to GFP_ATOMIC as we can't afford to sleep
58 * once we've checked for blocking and deadlocking.
59 * Andy Walker (andy@lysaker.kvaerner.no), April 03, 1996.
60 *
61 * Initial implementation of mandatory locks. SunOS turned out to be
62 * a rotten model, so I implemented the "obvious" semantics.
63 * See 'Documentation/mandatory.txt' for details.
64 * Andy Walker (andy@lysaker.kvaerner.no), April 06, 1996.
65 *
66 * Don't allow mandatory locks on mmap()'ed files. Added simple functions to
67 * check if a file has mandatory locks, used by mmap(), open() and creat() to
68 * see if system call should be rejected. Ref. HP-UX/SunOS/Solaris Reference
69 * Manual, Section 2.
70 * Andy Walker (andy@lysaker.kvaerner.no), April 09, 1996.
71 *
72 * Tidied up block list handling. Added '/proc/locks' interface.
73 * Andy Walker (andy@lysaker.kvaerner.no), April 24, 1996.
74 *
75 * Fixed deadlock condition for pathological code that mixes calls to
76 * flock() and fcntl().
77 * Andy Walker (andy@lysaker.kvaerner.no), April 29, 1996.
78 *
79 * Allow only one type of locking scheme (FL_POSIX or FL_FLOCK) to be in use
80 * for a given file at a time. Changed the CONFIG_LOCK_MANDATORY scheme to
81 * guarantee sensible behaviour in the case where file system modules might
82 * be compiled with different options than the kernel itself.
83 * Andy Walker (andy@lysaker.kvaerner.no), May 15, 1996.
84 *
85 * Added a couple of missing wake_up() calls. Thanks to Thomas Meckel
86 * (Thomas.Meckel@mni.fh-giessen.de) for spotting this.
87 * Andy Walker (andy@lysaker.kvaerner.no), May 15, 1996.
88 *
89 * Changed FL_POSIX locks to use the block list in the same way as FL_FLOCK
90 * locks. Changed process synchronisation to avoid dereferencing locks that
91 * have already been freed.
92 * Andy Walker (andy@lysaker.kvaerner.no), Sep 21, 1996.
93 *
94 * Made the block list a circular list to minimise searching in the list.
95 * Andy Walker (andy@lysaker.kvaerner.no), Sep 25, 1996.
96 *
97 * Made mandatory locking a mount option. Default is not to allow mandatory
98 * locking.
99 * Andy Walker (andy@lysaker.kvaerner.no), Oct 04, 1996.
100 *
101 * Some adaptations for NFS support.
102 * Olaf Kirch (okir@monad.swb.de), Dec 1996,
103 *
104 * Fixed /proc/locks interface so that we can't overrun the buffer we are handed.
105 * Andy Walker (andy@lysaker.kvaerner.no), May 12, 1997.
106 *
107 * Use slab allocator instead of kmalloc/kfree.
108 * Use generic list implementation from <linux/list.h>.
109 * Sped up posix_locks_deadlock by only considering blocked locks.
110 * Matthew Wilcox <willy@debian.org>, March, 2000.
111 *
112 * Leases and LOCK_MAND
113 * Matthew Wilcox <willy@debian.org>, June, 2000.
114 * Stephen Rothwell <sfr@canb.auug.org.au>, June, 2000.
115 */
116
117#include <linux/capability.h>
118#include <linux/file.h>
119#include <linux/fdtable.h>
120#include <linux/fs.h>
121#include <linux/init.h>
122#include <linux/module.h>
123#include <linux/security.h>
124#include <linux/slab.h>
125#include <linux/syscalls.h>
126#include <linux/time.h>
127#include <linux/rcupdate.h>
128#include <linux/pid_namespace.h>
129
130#include <asm/uaccess.h>
131
132#define IS_POSIX(fl) (fl->fl_flags & FL_POSIX)
133#define IS_FLOCK(fl) (fl->fl_flags & FL_FLOCK)
134#define IS_LEASE(fl) (fl->fl_flags & FL_LEASE)
135
136int leases_enable = 1;
137int lease_break_time = 45;
138
139#define for_each_lock(inode, lockp) \
140 for (lockp = &inode->i_flock; *lockp != NULL; lockp = &(*lockp)->fl_next)
141
142static LIST_HEAD(file_lock_list);
143static LIST_HEAD(blocked_list);
144static DEFINE_SPINLOCK(file_lock_lock);
145
146/*
147 * Protects the two list heads above, plus the inode->i_flock list
148 */
149void lock_flocks(void)
150{
151 spin_lock(&file_lock_lock);
152}
153EXPORT_SYMBOL_GPL(lock_flocks);
154
155void unlock_flocks(void)
156{
157 spin_unlock(&file_lock_lock);
158}
159EXPORT_SYMBOL_GPL(unlock_flocks);
160
161static struct kmem_cache *filelock_cache __read_mostly;
162
163static void locks_init_lock_heads(struct file_lock *fl)
164{
165 INIT_LIST_HEAD(&fl->fl_link);
166 INIT_LIST_HEAD(&fl->fl_block);
167 init_waitqueue_head(&fl->fl_wait);
168}
169
170/* Allocate an empty lock structure. */
171struct file_lock *locks_alloc_lock(void)
172{
173 struct file_lock *fl = kmem_cache_zalloc(filelock_cache, GFP_KERNEL);
174
175 if (fl)
176 locks_init_lock_heads(fl);
177
178 return fl;
179}
180EXPORT_SYMBOL_GPL(locks_alloc_lock);
181
182void locks_release_private(struct file_lock *fl)
183{
184 if (fl->fl_ops) {
185 if (fl->fl_ops->fl_release_private)
186 fl->fl_ops->fl_release_private(fl);
187 fl->fl_ops = NULL;
188 }
189 if (fl->fl_lmops) {
190 if (fl->fl_lmops->lm_release_private)
191 fl->fl_lmops->lm_release_private(fl);
192 fl->fl_lmops = NULL;
193 }
194
195}
196EXPORT_SYMBOL_GPL(locks_release_private);
197
198/* Free a lock which is not in use. */
199void locks_free_lock(struct file_lock *fl)
200{
201 BUG_ON(waitqueue_active(&fl->fl_wait));
202 BUG_ON(!list_empty(&fl->fl_block));
203 BUG_ON(!list_empty(&fl->fl_link));
204
205 locks_release_private(fl);
206 kmem_cache_free(filelock_cache, fl);
207}
208EXPORT_SYMBOL(locks_free_lock);
209
210void locks_init_lock(struct file_lock *fl)
211{
212 memset(fl, 0, sizeof(struct file_lock));
213 locks_init_lock_heads(fl);
214}
215
216EXPORT_SYMBOL(locks_init_lock);
217
218static void locks_copy_private(struct file_lock *new, struct file_lock *fl)
219{
220 if (fl->fl_ops) {
221 if (fl->fl_ops->fl_copy_lock)
222 fl->fl_ops->fl_copy_lock(new, fl);
223 new->fl_ops = fl->fl_ops;
224 }
225 if (fl->fl_lmops)
226 new->fl_lmops = fl->fl_lmops;
227}
228
229/*
230 * Initialize a new lock from an existing file_lock structure.
231 */
232void __locks_copy_lock(struct file_lock *new, const struct file_lock *fl)
233{
234 new->fl_owner = fl->fl_owner;
235 new->fl_pid = fl->fl_pid;
236 new->fl_file = NULL;
237 new->fl_flags = fl->fl_flags;
238 new->fl_type = fl->fl_type;
239 new->fl_start = fl->fl_start;
240 new->fl_end = fl->fl_end;
241 new->fl_ops = NULL;
242 new->fl_lmops = NULL;
243}
244EXPORT_SYMBOL(__locks_copy_lock);
245
246void locks_copy_lock(struct file_lock *new, struct file_lock *fl)
247{
248 locks_release_private(new);
249
250 __locks_copy_lock(new, fl);
251 new->fl_file = fl->fl_file;
252 new->fl_ops = fl->fl_ops;
253 new->fl_lmops = fl->fl_lmops;
254
255 locks_copy_private(new, fl);
256}
257
258EXPORT_SYMBOL(locks_copy_lock);
259
260static inline int flock_translate_cmd(int cmd) {
261 if (cmd & LOCK_MAND)
262 return cmd & (LOCK_MAND | LOCK_RW);
263 switch (cmd) {
264 case LOCK_SH:
265 return F_RDLCK;
266 case LOCK_EX:
267 return F_WRLCK;
268 case LOCK_UN:
269 return F_UNLCK;
270 }
271 return -EINVAL;
272}
273
274/* Fill in a file_lock structure with an appropriate FLOCK lock. */
275static int flock_make_lock(struct file *filp, struct file_lock **lock,
276 unsigned int cmd)
277{
278 struct file_lock *fl;
279 int type = flock_translate_cmd(cmd);
280 if (type < 0)
281 return type;
282
283 fl = locks_alloc_lock();
284 if (fl == NULL)
285 return -ENOMEM;
286
287 fl->fl_file = filp;
288 fl->fl_pid = current->tgid;
289 fl->fl_flags = FL_FLOCK;
290 fl->fl_type = type;
291 fl->fl_end = OFFSET_MAX;
292
293 *lock = fl;
294 return 0;
295}
296
297static int assign_type(struct file_lock *fl, int type)
298{
299 switch (type) {
300 case F_RDLCK:
301 case F_WRLCK:
302 case F_UNLCK:
303 fl->fl_type = type;
304 break;
305 default:
306 return -EINVAL;
307 }
308 return 0;
309}
310
311/* Verify a "struct flock" and copy it to a "struct file_lock" as a POSIX
312 * style lock.
313 */
314static int flock_to_posix_lock(struct file *filp, struct file_lock *fl,
315 struct flock *l)
316{
317 off_t start, end;
318
319 switch (l->l_whence) {
320 case SEEK_SET:
321 start = 0;
322 break;
323 case SEEK_CUR:
324 start = filp->f_pos;
325 break;
326 case SEEK_END:
327 start = i_size_read(filp->f_path.dentry->d_inode);
328 break;
329 default:
330 return -EINVAL;
331 }
332
333 /* POSIX-1996 leaves the case l->l_len < 0 undefined;
334 POSIX-2001 defines it. */
335 start += l->l_start;
336 if (start < 0)
337 return -EINVAL;
338 fl->fl_end = OFFSET_MAX;
339 if (l->l_len > 0) {
340 end = start + l->l_len - 1;
341 fl->fl_end = end;
342 } else if (l->l_len < 0) {
343 end = start - 1;
344 fl->fl_end = end;
345 start += l->l_len;
346 if (start < 0)
347 return -EINVAL;
348 }
349 fl->fl_start = start; /* we record the absolute position */
350 if (fl->fl_end < fl->fl_start)
351 return -EOVERFLOW;
352
353 fl->fl_owner = current->files;
354 fl->fl_pid = current->tgid;
355 fl->fl_file = filp;
356 fl->fl_flags = FL_POSIX;
357 fl->fl_ops = NULL;
358 fl->fl_lmops = NULL;
359
360 return assign_type(fl, l->l_type);
361}
362
363#if BITS_PER_LONG == 32
364static int flock64_to_posix_lock(struct file *filp, struct file_lock *fl,
365 struct flock64 *l)
366{
367 loff_t start;
368
369 switch (l->l_whence) {
370 case SEEK_SET:
371 start = 0;
372 break;
373 case SEEK_CUR:
374 start = filp->f_pos;
375 break;
376 case SEEK_END:
377 start = i_size_read(filp->f_path.dentry->d_inode);
378 break;
379 default:
380 return -EINVAL;
381 }
382
383 start += l->l_start;
384 if (start < 0)
385 return -EINVAL;
386 fl->fl_end = OFFSET_MAX;
387 if (l->l_len > 0) {
388 fl->fl_end = start + l->l_len - 1;
389 } else if (l->l_len < 0) {
390 fl->fl_end = start - 1;
391 start += l->l_len;
392 if (start < 0)
393 return -EINVAL;
394 }
395 fl->fl_start = start; /* we record the absolute position */
396 if (fl->fl_end < fl->fl_start)
397 return -EOVERFLOW;
398
399 fl->fl_owner = current->files;
400 fl->fl_pid = current->tgid;
401 fl->fl_file = filp;
402 fl->fl_flags = FL_POSIX;
403 fl->fl_ops = NULL;
404 fl->fl_lmops = NULL;
405
406 return assign_type(fl, l->l_type);
407}
408#endif
409
410/* default lease lock manager operations */
411static void lease_break_callback(struct file_lock *fl)
412{
413 kill_fasync(&fl->fl_fasync, SIGIO, POLL_MSG);
414}
415
416static void lease_release_private_callback(struct file_lock *fl)
417{
418 if (!fl->fl_file)
419 return;
420
421 f_delown(fl->fl_file);
422 fl->fl_file->f_owner.signum = 0;
423}
424
425static const struct lock_manager_operations lease_manager_ops = {
426 .lm_break = lease_break_callback,
427 .lm_release_private = lease_release_private_callback,
428 .lm_change = lease_modify,
429};
430
431/*
432 * Initialize a lease, use the default lock manager operations
433 */
434static int lease_init(struct file *filp, int type, struct file_lock *fl)
435 {
436 if (assign_type(fl, type) != 0)
437 return -EINVAL;
438
439 fl->fl_owner = current->files;
440 fl->fl_pid = current->tgid;
441
442 fl->fl_file = filp;
443 fl->fl_flags = FL_LEASE;
444 fl->fl_start = 0;
445 fl->fl_end = OFFSET_MAX;
446 fl->fl_ops = NULL;
447 fl->fl_lmops = &lease_manager_ops;
448 return 0;
449}
450
451/* Allocate a file_lock initialised to this type of lease */
452static struct file_lock *lease_alloc(struct file *filp, int type)
453{
454 struct file_lock *fl = locks_alloc_lock();
455 int error = -ENOMEM;
456
457 if (fl == NULL)
458 return ERR_PTR(error);
459
460 error = lease_init(filp, type, fl);
461 if (error) {
462 locks_free_lock(fl);
463 return ERR_PTR(error);
464 }
465 return fl;
466}
467
468/* Check if two locks overlap each other.
469 */
470static inline int locks_overlap(struct file_lock *fl1, struct file_lock *fl2)
471{
472 return ((fl1->fl_end >= fl2->fl_start) &&
473 (fl2->fl_end >= fl1->fl_start));
474}
475
476/*
477 * Check whether two locks have the same owner.
478 */
479static int posix_same_owner(struct file_lock *fl1, struct file_lock *fl2)
480{
481 if (fl1->fl_lmops && fl1->fl_lmops->lm_compare_owner)
482 return fl2->fl_lmops == fl1->fl_lmops &&
483 fl1->fl_lmops->lm_compare_owner(fl1, fl2);
484 return fl1->fl_owner == fl2->fl_owner;
485}
486
487/* Remove waiter from blocker's block list.
488 * When blocker ends up pointing to itself then the list is empty.
489 */
490static void __locks_delete_block(struct file_lock *waiter)
491{
492 list_del_init(&waiter->fl_block);
493 list_del_init(&waiter->fl_link);
494 waiter->fl_next = NULL;
495}
496
497/*
498 */
499static void locks_delete_block(struct file_lock *waiter)
500{
501 lock_flocks();
502 __locks_delete_block(waiter);
503 unlock_flocks();
504}
505
506/* Insert waiter into blocker's block list.
507 * We use a circular list so that processes can be easily woken up in
508 * the order they blocked. The documentation doesn't require this but
509 * it seems like the reasonable thing to do.
510 */
511static void locks_insert_block(struct file_lock *blocker,
512 struct file_lock *waiter)
513{
514 BUG_ON(!list_empty(&waiter->fl_block));
515 list_add_tail(&waiter->fl_block, &blocker->fl_block);
516 waiter->fl_next = blocker;
517 if (IS_POSIX(blocker))
518 list_add(&waiter->fl_link, &blocked_list);
519}
520
521/* Wake up processes blocked waiting for blocker.
522 * If told to wait then schedule the processes until the block list
523 * is empty, otherwise empty the block list ourselves.
524 */
525static void locks_wake_up_blocks(struct file_lock *blocker)
526{
527 while (!list_empty(&blocker->fl_block)) {
528 struct file_lock *waiter;
529
530 waiter = list_first_entry(&blocker->fl_block,
531 struct file_lock, fl_block);
532 __locks_delete_block(waiter);
533 if (waiter->fl_lmops && waiter->fl_lmops->lm_notify)
534 waiter->fl_lmops->lm_notify(waiter);
535 else
536 wake_up(&waiter->fl_wait);
537 }
538}
539
540/* Insert file lock fl into an inode's lock list at the position indicated
541 * by pos. At the same time add the lock to the global file lock list.
542 */
543static void locks_insert_lock(struct file_lock **pos, struct file_lock *fl)
544{
545 list_add(&fl->fl_link, &file_lock_list);
546
547 fl->fl_nspid = get_pid(task_tgid(current));
548
549 /* insert into file's list */
550 fl->fl_next = *pos;
551 *pos = fl;
552}
553
554/*
555 * Delete a lock and then free it.
556 * Wake up processes that are blocked waiting for this lock,
557 * notify the FS that the lock has been cleared and
558 * finally free the lock.
559 */
560static void locks_delete_lock(struct file_lock **thisfl_p)
561{
562 struct file_lock *fl = *thisfl_p;
563
564 *thisfl_p = fl->fl_next;
565 fl->fl_next = NULL;
566 list_del_init(&fl->fl_link);
567
568 fasync_helper(0, fl->fl_file, 0, &fl->fl_fasync);
569 if (fl->fl_fasync != NULL) {
570 printk(KERN_ERR "locks_delete_lock: fasync == %p\n", fl->fl_fasync);
571 fl->fl_fasync = NULL;
572 }
573
574 if (fl->fl_nspid) {
575 put_pid(fl->fl_nspid);
576 fl->fl_nspid = NULL;
577 }
578
579 locks_wake_up_blocks(fl);
580 locks_free_lock(fl);
581}
582
583/* Determine if lock sys_fl blocks lock caller_fl. Common functionality
584 * checks for shared/exclusive status of overlapping locks.
585 */
586static int locks_conflict(struct file_lock *caller_fl, struct file_lock *sys_fl)
587{
588 if (sys_fl->fl_type == F_WRLCK)
589 return 1;
590 if (caller_fl->fl_type == F_WRLCK)
591 return 1;
592 return 0;
593}
594
595/* Determine if lock sys_fl blocks lock caller_fl. POSIX specific
596 * checking before calling the locks_conflict().
597 */
598static int posix_locks_conflict(struct file_lock *caller_fl, struct file_lock *sys_fl)
599{
600 /* POSIX locks owned by the same process do not conflict with
601 * each other.
602 */
603 if (!IS_POSIX(sys_fl) || posix_same_owner(caller_fl, sys_fl))
604 return (0);
605
606 /* Check whether they overlap */
607 if (!locks_overlap(caller_fl, sys_fl))
608 return 0;
609
610 return (locks_conflict(caller_fl, sys_fl));
611}
612
613/* Determine if lock sys_fl blocks lock caller_fl. FLOCK specific
614 * checking before calling the locks_conflict().
615 */
616static int flock_locks_conflict(struct file_lock *caller_fl, struct file_lock *sys_fl)
617{
618 /* FLOCK locks referring to the same filp do not conflict with
619 * each other.
620 */
621 if (!IS_FLOCK(sys_fl) || (caller_fl->fl_file == sys_fl->fl_file))
622 return (0);
623 if ((caller_fl->fl_type & LOCK_MAND) || (sys_fl->fl_type & LOCK_MAND))
624 return 0;
625
626 return (locks_conflict(caller_fl, sys_fl));
627}
628
629void
630posix_test_lock(struct file *filp, struct file_lock *fl)
631{
632 struct file_lock *cfl;
633
634 lock_flocks();
635 for (cfl = filp->f_path.dentry->d_inode->i_flock; cfl; cfl = cfl->fl_next) {
636 if (!IS_POSIX(cfl))
637 continue;
638 if (posix_locks_conflict(fl, cfl))
639 break;
640 }
641 if (cfl) {
642 __locks_copy_lock(fl, cfl);
643 if (cfl->fl_nspid)
644 fl->fl_pid = pid_vnr(cfl->fl_nspid);
645 } else
646 fl->fl_type = F_UNLCK;
647 unlock_flocks();
648 return;
649}
650EXPORT_SYMBOL(posix_test_lock);
651
652/*
653 * Deadlock detection:
654 *
655 * We attempt to detect deadlocks that are due purely to posix file
656 * locks.
657 *
658 * We assume that a task can be waiting for at most one lock at a time.
659 * So for any acquired lock, the process holding that lock may be
660 * waiting on at most one other lock. That lock in turns may be held by
661 * someone waiting for at most one other lock. Given a requested lock
662 * caller_fl which is about to wait for a conflicting lock block_fl, we
663 * follow this chain of waiters to ensure we are not about to create a
664 * cycle.
665 *
666 * Since we do this before we ever put a process to sleep on a lock, we
667 * are ensured that there is never a cycle; that is what guarantees that
668 * the while() loop in posix_locks_deadlock() eventually completes.
669 *
670 * Note: the above assumption may not be true when handling lock
671 * requests from a broken NFS client. It may also fail in the presence
672 * of tasks (such as posix threads) sharing the same open file table.
673 *
674 * To handle those cases, we just bail out after a few iterations.
675 */
676
677#define MAX_DEADLK_ITERATIONS 10
678
679/* Find a lock that the owner of the given block_fl is blocking on. */
680static struct file_lock *what_owner_is_waiting_for(struct file_lock *block_fl)
681{
682 struct file_lock *fl;
683
684 list_for_each_entry(fl, &blocked_list, fl_link) {
685 if (posix_same_owner(fl, block_fl))
686 return fl->fl_next;
687 }
688 return NULL;
689}
690
691static int posix_locks_deadlock(struct file_lock *caller_fl,
692 struct file_lock *block_fl)
693{
694 int i = 0;
695
696 while ((block_fl = what_owner_is_waiting_for(block_fl))) {
697 if (i++ > MAX_DEADLK_ITERATIONS)
698 return 0;
699 if (posix_same_owner(caller_fl, block_fl))
700 return 1;
701 }
702 return 0;
703}
704
705/* Try to create a FLOCK lock on filp. We always insert new FLOCK locks
706 * after any leases, but before any posix locks.
707 *
708 * Note that if called with an FL_EXISTS argument, the caller may determine
709 * whether or not a lock was successfully freed by testing the return
710 * value for -ENOENT.
711 */
712static int flock_lock_file(struct file *filp, struct file_lock *request)
713{
714 struct file_lock *new_fl = NULL;
715 struct file_lock **before;
716 struct inode * inode = filp->f_path.dentry->d_inode;
717 int error = 0;
718 int found = 0;
719
720 if (!(request->fl_flags & FL_ACCESS) && (request->fl_type != F_UNLCK)) {
721 new_fl = locks_alloc_lock();
722 if (!new_fl)
723 return -ENOMEM;
724 }
725
726 lock_flocks();
727 if (request->fl_flags & FL_ACCESS)
728 goto find_conflict;
729
730 for_each_lock(inode, before) {
731 struct file_lock *fl = *before;
732 if (IS_POSIX(fl))
733 break;
734 if (IS_LEASE(fl))
735 continue;
736 if (filp != fl->fl_file)
737 continue;
738 if (request->fl_type == fl->fl_type)
739 goto out;
740 found = 1;
741 locks_delete_lock(before);
742 break;
743 }
744
745 if (request->fl_type == F_UNLCK) {
746 if ((request->fl_flags & FL_EXISTS) && !found)
747 error = -ENOENT;
748 goto out;
749 }
750
751 /*
752 * If a higher-priority process was blocked on the old file lock,
753 * give it the opportunity to lock the file.
754 */
755 if (found) {
756 unlock_flocks();
757 cond_resched();
758 lock_flocks();
759 }
760
761find_conflict:
762 for_each_lock(inode, before) {
763 struct file_lock *fl = *before;
764 if (IS_POSIX(fl))
765 break;
766 if (IS_LEASE(fl))
767 continue;
768 if (!flock_locks_conflict(request, fl))
769 continue;
770 error = -EAGAIN;
771 if (!(request->fl_flags & FL_SLEEP))
772 goto out;
773 error = FILE_LOCK_DEFERRED;
774 locks_insert_block(fl, request);
775 goto out;
776 }
777 if (request->fl_flags & FL_ACCESS)
778 goto out;
779 locks_copy_lock(new_fl, request);
780 locks_insert_lock(before, new_fl);
781 new_fl = NULL;
782 error = 0;
783
784out:
785 unlock_flocks();
786 if (new_fl)
787 locks_free_lock(new_fl);
788 return error;
789}
790
791static int __posix_lock_file(struct inode *inode, struct file_lock *request, struct file_lock *conflock)
792{
793 struct file_lock *fl;
794 struct file_lock *new_fl = NULL;
795 struct file_lock *new_fl2 = NULL;
796 struct file_lock *left = NULL;
797 struct file_lock *right = NULL;
798 struct file_lock **before;
799 int error, added = 0;
800
801 /*
802 * We may need two file_lock structures for this operation,
803 * so we get them in advance to avoid races.
804 *
805 * In some cases we can be sure, that no new locks will be needed
806 */
807 if (!(request->fl_flags & FL_ACCESS) &&
808 (request->fl_type != F_UNLCK ||
809 request->fl_start != 0 || request->fl_end != OFFSET_MAX)) {
810 new_fl = locks_alloc_lock();
811 new_fl2 = locks_alloc_lock();
812 }
813
814 lock_flocks();
815 if (request->fl_type != F_UNLCK) {
816 for_each_lock(inode, before) {
817 fl = *before;
818 if (!IS_POSIX(fl))
819 continue;
820 if (!posix_locks_conflict(request, fl))
821 continue;
822 if (conflock)
823 __locks_copy_lock(conflock, fl);
824 error = -EAGAIN;
825 if (!(request->fl_flags & FL_SLEEP))
826 goto out;
827 error = -EDEADLK;
828 if (posix_locks_deadlock(request, fl))
829 goto out;
830 error = FILE_LOCK_DEFERRED;
831 locks_insert_block(fl, request);
832 goto out;
833 }
834 }
835
836 /* If we're just looking for a conflict, we're done. */
837 error = 0;
838 if (request->fl_flags & FL_ACCESS)
839 goto out;
840
841 /*
842 * Find the first old lock with the same owner as the new lock.
843 */
844
845 before = &inode->i_flock;
846
847 /* First skip locks owned by other processes. */
848 while ((fl = *before) && (!IS_POSIX(fl) ||
849 !posix_same_owner(request, fl))) {
850 before = &fl->fl_next;
851 }
852
853 /* Process locks with this owner. */
854 while ((fl = *before) && posix_same_owner(request, fl)) {
855 /* Detect adjacent or overlapping regions (if same lock type)
856 */
857 if (request->fl_type == fl->fl_type) {
858 /* In all comparisons of start vs end, use
859 * "start - 1" rather than "end + 1". If end
860 * is OFFSET_MAX, end + 1 will become negative.
861 */
862 if (fl->fl_end < request->fl_start - 1)
863 goto next_lock;
864 /* If the next lock in the list has entirely bigger
865 * addresses than the new one, insert the lock here.
866 */
867 if (fl->fl_start - 1 > request->fl_end)
868 break;
869
870 /* If we come here, the new and old lock are of the
871 * same type and adjacent or overlapping. Make one
872 * lock yielding from the lower start address of both
873 * locks to the higher end address.
874 */
875 if (fl->fl_start > request->fl_start)
876 fl->fl_start = request->fl_start;
877 else
878 request->fl_start = fl->fl_start;
879 if (fl->fl_end < request->fl_end)
880 fl->fl_end = request->fl_end;
881 else
882 request->fl_end = fl->fl_end;
883 if (added) {
884 locks_delete_lock(before);
885 continue;
886 }
887 request = fl;
888 added = 1;
889 }
890 else {
891 /* Processing for different lock types is a bit
892 * more complex.
893 */
894 if (fl->fl_end < request->fl_start)
895 goto next_lock;
896 if (fl->fl_start > request->fl_end)
897 break;
898 if (request->fl_type == F_UNLCK)
899 added = 1;
900 if (fl->fl_start < request->fl_start)
901 left = fl;
902 /* If the next lock in the list has a higher end
903 * address than the new one, insert the new one here.
904 */
905 if (fl->fl_end > request->fl_end) {
906 right = fl;
907 break;
908 }
909 if (fl->fl_start >= request->fl_start) {
910 /* The new lock completely replaces an old
911 * one (This may happen several times).
912 */
913 if (added) {
914 locks_delete_lock(before);
915 continue;
916 }
917 /* Replace the old lock with the new one.
918 * Wake up anybody waiting for the old one,
919 * as the change in lock type might satisfy
920 * their needs.
921 */
922 locks_wake_up_blocks(fl);
923 fl->fl_start = request->fl_start;
924 fl->fl_end = request->fl_end;
925 fl->fl_type = request->fl_type;
926 locks_release_private(fl);
927 locks_copy_private(fl, request);
928 request = fl;
929 added = 1;
930 }
931 }
932 /* Go on to next lock.
933 */
934 next_lock:
935 before = &fl->fl_next;
936 }
937
938 /*
939 * The above code only modifies existing locks in case of
940 * merging or replacing. If new lock(s) need to be inserted
941 * all modifications are done bellow this, so it's safe yet to
942 * bail out.
943 */
944 error = -ENOLCK; /* "no luck" */
945 if (right && left == right && !new_fl2)
946 goto out;
947
948 error = 0;
949 if (!added) {
950 if (request->fl_type == F_UNLCK) {
951 if (request->fl_flags & FL_EXISTS)
952 error = -ENOENT;
953 goto out;
954 }
955
956 if (!new_fl) {
957 error = -ENOLCK;
958 goto out;
959 }
960 locks_copy_lock(new_fl, request);
961 locks_insert_lock(before, new_fl);
962 new_fl = NULL;
963 }
964 if (right) {
965 if (left == right) {
966 /* The new lock breaks the old one in two pieces,
967 * so we have to use the second new lock.
968 */
969 left = new_fl2;
970 new_fl2 = NULL;
971 locks_copy_lock(left, right);
972 locks_insert_lock(before, left);
973 }
974 right->fl_start = request->fl_end + 1;
975 locks_wake_up_blocks(right);
976 }
977 if (left) {
978 left->fl_end = request->fl_start - 1;
979 locks_wake_up_blocks(left);
980 }
981 out:
982 unlock_flocks();
983 /*
984 * Free any unused locks.
985 */
986 if (new_fl)
987 locks_free_lock(new_fl);
988 if (new_fl2)
989 locks_free_lock(new_fl2);
990 return error;
991}
992
993/**
994 * posix_lock_file - Apply a POSIX-style lock to a file
995 * @filp: The file to apply the lock to
996 * @fl: The lock to be applied
997 * @conflock: Place to return a copy of the conflicting lock, if found.
998 *
999 * Add a POSIX style lock to a file.
1000 * We merge adjacent & overlapping locks whenever possible.
1001 * POSIX locks are sorted by owner task, then by starting address
1002 *
1003 * Note that if called with an FL_EXISTS argument, the caller may determine
1004 * whether or not a lock was successfully freed by testing the return
1005 * value for -ENOENT.
1006 */
1007int posix_lock_file(struct file *filp, struct file_lock *fl,
1008 struct file_lock *conflock)
1009{
1010 return __posix_lock_file(filp->f_path.dentry->d_inode, fl, conflock);
1011}
1012EXPORT_SYMBOL(posix_lock_file);
1013
1014/**
1015 * posix_lock_file_wait - Apply a POSIX-style lock to a file
1016 * @filp: The file to apply the lock to
1017 * @fl: The lock to be applied
1018 *
1019 * Add a POSIX style lock to a file.
1020 * We merge adjacent & overlapping locks whenever possible.
1021 * POSIX locks are sorted by owner task, then by starting address
1022 */
1023int posix_lock_file_wait(struct file *filp, struct file_lock *fl)
1024{
1025 int error;
1026 might_sleep ();
1027 for (;;) {
1028 error = posix_lock_file(filp, fl, NULL);
1029 if (error != FILE_LOCK_DEFERRED)
1030 break;
1031 error = wait_event_interruptible(fl->fl_wait, !fl->fl_next);
1032 if (!error)
1033 continue;
1034
1035 locks_delete_block(fl);
1036 break;
1037 }
1038 return error;
1039}
1040EXPORT_SYMBOL(posix_lock_file_wait);
1041
1042/**
1043 * locks_mandatory_locked - Check for an active lock
1044 * @inode: the file to check
1045 *
1046 * Searches the inode's list of locks to find any POSIX locks which conflict.
1047 * This function is called from locks_verify_locked() only.
1048 */
1049int locks_mandatory_locked(struct inode *inode)
1050{
1051 fl_owner_t owner = current->files;
1052 struct file_lock *fl;
1053
1054 /*
1055 * Search the lock list for this inode for any POSIX locks.
1056 */
1057 lock_flocks();
1058 for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) {
1059 if (!IS_POSIX(fl))
1060 continue;
1061 if (fl->fl_owner != owner)
1062 break;
1063 }
1064 unlock_flocks();
1065 return fl ? -EAGAIN : 0;
1066}
1067
1068/**
1069 * locks_mandatory_area - Check for a conflicting lock
1070 * @read_write: %FLOCK_VERIFY_WRITE for exclusive access, %FLOCK_VERIFY_READ
1071 * for shared
1072 * @inode: the file to check
1073 * @filp: how the file was opened (if it was)
1074 * @offset: start of area to check
1075 * @count: length of area to check
1076 *
1077 * Searches the inode's list of locks to find any POSIX locks which conflict.
1078 * This function is called from rw_verify_area() and
1079 * locks_verify_truncate().
1080 */
1081int locks_mandatory_area(int read_write, struct inode *inode,
1082 struct file *filp, loff_t offset,
1083 size_t count)
1084{
1085 struct file_lock fl;
1086 int error;
1087
1088 locks_init_lock(&fl);
1089 fl.fl_owner = current->files;
1090 fl.fl_pid = current->tgid;
1091 fl.fl_file = filp;
1092 fl.fl_flags = FL_POSIX | FL_ACCESS;
1093 if (filp && !(filp->f_flags & O_NONBLOCK))
1094 fl.fl_flags |= FL_SLEEP;
1095 fl.fl_type = (read_write == FLOCK_VERIFY_WRITE) ? F_WRLCK : F_RDLCK;
1096 fl.fl_start = offset;
1097 fl.fl_end = offset + count - 1;
1098
1099 for (;;) {
1100 error = __posix_lock_file(inode, &fl, NULL);
1101 if (error != FILE_LOCK_DEFERRED)
1102 break;
1103 error = wait_event_interruptible(fl.fl_wait, !fl.fl_next);
1104 if (!error) {
1105 /*
1106 * If we've been sleeping someone might have
1107 * changed the permissions behind our back.
1108 */
1109 if (__mandatory_lock(inode))
1110 continue;
1111 }
1112
1113 locks_delete_block(&fl);
1114 break;
1115 }
1116
1117 return error;
1118}
1119
1120EXPORT_SYMBOL(locks_mandatory_area);
1121
1122/* We already had a lease on this file; just change its type */
1123int lease_modify(struct file_lock **before, int arg)
1124{
1125 struct file_lock *fl = *before;
1126 int error = assign_type(fl, arg);
1127
1128 if (error)
1129 return error;
1130 locks_wake_up_blocks(fl);
1131 if (arg == F_UNLCK)
1132 locks_delete_lock(before);
1133 return 0;
1134}
1135
1136EXPORT_SYMBOL(lease_modify);
1137
1138static void time_out_leases(struct inode *inode)
1139{
1140 struct file_lock **before;
1141 struct file_lock *fl;
1142
1143 before = &inode->i_flock;
1144 while ((fl = *before) && IS_LEASE(fl) && (fl->fl_type & F_INPROGRESS)) {
1145 if ((fl->fl_break_time == 0)
1146 || time_before(jiffies, fl->fl_break_time)) {
1147 before = &fl->fl_next;
1148 continue;
1149 }
1150 lease_modify(before, fl->fl_type & ~F_INPROGRESS);
1151 if (fl == *before) /* lease_modify may have freed fl */
1152 before = &fl->fl_next;
1153 }
1154}
1155
1156/**
1157 * __break_lease - revoke all outstanding leases on file
1158 * @inode: the inode of the file to return
1159 * @mode: the open mode (read or write)
1160 *
1161 * break_lease (inlined for speed) has checked there already is at least
1162 * some kind of lock (maybe a lease) on this file. Leases are broken on
1163 * a call to open() or truncate(). This function can sleep unless you
1164 * specified %O_NONBLOCK to your open().
1165 */
1166int __break_lease(struct inode *inode, unsigned int mode)
1167{
1168 int error = 0, future;
1169 struct file_lock *new_fl, *flock;
1170 struct file_lock *fl;
1171 unsigned long break_time;
1172 int i_have_this_lease = 0;
1173 int want_write = (mode & O_ACCMODE) != O_RDONLY;
1174
1175 new_fl = lease_alloc(NULL, want_write ? F_WRLCK : F_RDLCK);
1176
1177 lock_flocks();
1178
1179 time_out_leases(inode);
1180
1181 flock = inode->i_flock;
1182 if ((flock == NULL) || !IS_LEASE(flock))
1183 goto out;
1184
1185 for (fl = flock; fl && IS_LEASE(fl); fl = fl->fl_next)
1186 if (fl->fl_owner == current->files)
1187 i_have_this_lease = 1;
1188
1189 if (want_write) {
1190 /* If we want write access, we have to revoke any lease. */
1191 future = F_UNLCK | F_INPROGRESS;
1192 } else if (flock->fl_type & F_INPROGRESS) {
1193 /* If the lease is already being broken, we just leave it */
1194 future = flock->fl_type;
1195 } else if (flock->fl_type & F_WRLCK) {
1196 /* Downgrade the exclusive lease to a read-only lease. */
1197 future = F_RDLCK | F_INPROGRESS;
1198 } else {
1199 /* the existing lease was read-only, so we can read too. */
1200 goto out;
1201 }
1202
1203 if (IS_ERR(new_fl) && !i_have_this_lease
1204 && ((mode & O_NONBLOCK) == 0)) {
1205 error = PTR_ERR(new_fl);
1206 goto out;
1207 }
1208
1209 break_time = 0;
1210 if (lease_break_time > 0) {
1211 break_time = jiffies + lease_break_time * HZ;
1212 if (break_time == 0)
1213 break_time++; /* so that 0 means no break time */
1214 }
1215
1216 for (fl = flock; fl && IS_LEASE(fl); fl = fl->fl_next) {
1217 if (fl->fl_type != future) {
1218 fl->fl_type = future;
1219 fl->fl_break_time = break_time;
1220 /* lease must have lmops break callback */
1221 fl->fl_lmops->lm_break(fl);
1222 }
1223 }
1224
1225 if (i_have_this_lease || (mode & O_NONBLOCK)) {
1226 error = -EWOULDBLOCK;
1227 goto out;
1228 }
1229
1230restart:
1231 break_time = flock->fl_break_time;
1232 if (break_time != 0) {
1233 break_time -= jiffies;
1234 if (break_time == 0)
1235 break_time++;
1236 }
1237 locks_insert_block(flock, new_fl);
1238 unlock_flocks();
1239 error = wait_event_interruptible_timeout(new_fl->fl_wait,
1240 !new_fl->fl_next, break_time);
1241 lock_flocks();
1242 __locks_delete_block(new_fl);
1243 if (error >= 0) {
1244 if (error == 0)
1245 time_out_leases(inode);
1246 /* Wait for the next lease that has not been broken yet */
1247 for (flock = inode->i_flock; flock && IS_LEASE(flock);
1248 flock = flock->fl_next) {
1249 if (flock->fl_type & F_INPROGRESS)
1250 goto restart;
1251 }
1252 error = 0;
1253 }
1254
1255out:
1256 unlock_flocks();
1257 if (!IS_ERR(new_fl))
1258 locks_free_lock(new_fl);
1259 return error;
1260}
1261
1262EXPORT_SYMBOL(__break_lease);
1263
1264/**
1265 * lease_get_mtime - get the last modified time of an inode
1266 * @inode: the inode
1267 * @time: pointer to a timespec which will contain the last modified time
1268 *
1269 * This is to force NFS clients to flush their caches for files with
1270 * exclusive leases. The justification is that if someone has an
1271 * exclusive lease, then they could be modifying it.
1272 */
1273void lease_get_mtime(struct inode *inode, struct timespec *time)
1274{
1275 struct file_lock *flock = inode->i_flock;
1276 if (flock && IS_LEASE(flock) && (flock->fl_type & F_WRLCK))
1277 *time = current_fs_time(inode->i_sb);
1278 else
1279 *time = inode->i_mtime;
1280}
1281
1282EXPORT_SYMBOL(lease_get_mtime);
1283
1284/**
1285 * fcntl_getlease - Enquire what lease is currently active
1286 * @filp: the file
1287 *
1288 * The value returned by this function will be one of
1289 * (if no lease break is pending):
1290 *
1291 * %F_RDLCK to indicate a shared lease is held.
1292 *
1293 * %F_WRLCK to indicate an exclusive lease is held.
1294 *
1295 * %F_UNLCK to indicate no lease is held.
1296 *
1297 * (if a lease break is pending):
1298 *
1299 * %F_RDLCK to indicate an exclusive lease needs to be
1300 * changed to a shared lease (or removed).
1301 *
1302 * %F_UNLCK to indicate the lease needs to be removed.
1303 *
1304 * XXX: sfr & willy disagree over whether F_INPROGRESS
1305 * should be returned to userspace.
1306 */
1307int fcntl_getlease(struct file *filp)
1308{
1309 struct file_lock *fl;
1310 int type = F_UNLCK;
1311
1312 lock_flocks();
1313 time_out_leases(filp->f_path.dentry->d_inode);
1314 for (fl = filp->f_path.dentry->d_inode->i_flock; fl && IS_LEASE(fl);
1315 fl = fl->fl_next) {
1316 if (fl->fl_file == filp) {
1317 type = fl->fl_type & ~F_INPROGRESS;
1318 break;
1319 }
1320 }
1321 unlock_flocks();
1322 return type;
1323}
1324
1325/**
1326 * generic_setlease - sets a lease on an open file
1327 * @filp: file pointer
1328 * @arg: type of lease to obtain
1329 * @flp: input - file_lock to use, output - file_lock inserted
1330 *
1331 * The (input) flp->fl_lmops->lm_break function is required
1332 * by break_lease().
1333 *
1334 * Called with file_lock_lock held.
1335 */
1336int generic_setlease(struct file *filp, long arg, struct file_lock **flp)
1337{
1338 struct file_lock *fl, **before, **my_before = NULL, *lease;
1339 struct dentry *dentry = filp->f_path.dentry;
1340 struct inode *inode = dentry->d_inode;
1341 int error, rdlease_count = 0, wrlease_count = 0;
1342
1343 lease = *flp;
1344
1345 error = -EACCES;
1346 if ((current_fsuid() != inode->i_uid) && !capable(CAP_LEASE))
1347 goto out;
1348 error = -EINVAL;
1349 if (!S_ISREG(inode->i_mode))
1350 goto out;
1351 error = security_file_lock(filp, arg);
1352 if (error)
1353 goto out;
1354
1355 time_out_leases(inode);
1356
1357 BUG_ON(!(*flp)->fl_lmops->lm_break);
1358
1359 if (arg != F_UNLCK) {
1360 error = -EAGAIN;
1361 if ((arg == F_RDLCK) && (atomic_read(&inode->i_writecount) > 0))
1362 goto out;
1363 if ((arg == F_WRLCK)
1364 && ((dentry->d_count > 1)
1365 || (atomic_read(&inode->i_count) > 1)))
1366 goto out;
1367 }
1368
1369 /*
1370 * At this point, we know that if there is an exclusive
1371 * lease on this file, then we hold it on this filp
1372 * (otherwise our open of this file would have blocked).
1373 * And if we are trying to acquire an exclusive lease,
1374 * then the file is not open by anyone (including us)
1375 * except for this filp.
1376 */
1377 for (before = &inode->i_flock;
1378 ((fl = *before) != NULL) && IS_LEASE(fl);
1379 before = &fl->fl_next) {
1380 if (fl->fl_file == filp)
1381 my_before = before;
1382 else if (fl->fl_type == (F_INPROGRESS | F_UNLCK))
1383 /*
1384 * Someone is in the process of opening this
1385 * file for writing so we may not take an
1386 * exclusive lease on it.
1387 */
1388 wrlease_count++;
1389 else
1390 rdlease_count++;
1391 }
1392
1393 error = -EAGAIN;
1394 if ((arg == F_RDLCK && (wrlease_count > 0)) ||
1395 (arg == F_WRLCK && ((rdlease_count + wrlease_count) > 0)))
1396 goto out;
1397
1398 if (my_before != NULL) {
1399 error = lease->fl_lmops->lm_change(my_before, arg);
1400 if (!error)
1401 *flp = *my_before;
1402 goto out;
1403 }
1404
1405 if (arg == F_UNLCK)
1406 goto out;
1407
1408 error = -EINVAL;
1409 if (!leases_enable)
1410 goto out;
1411
1412 locks_insert_lock(before, lease);
1413 return 0;
1414
1415out:
1416 return error;
1417}
1418EXPORT_SYMBOL(generic_setlease);
1419
1420static int __vfs_setlease(struct file *filp, long arg, struct file_lock **lease)
1421{
1422 if (filp->f_op && filp->f_op->setlease)
1423 return filp->f_op->setlease(filp, arg, lease);
1424 else
1425 return generic_setlease(filp, arg, lease);
1426}
1427
1428/**
1429 * vfs_setlease - sets a lease on an open file
1430 * @filp: file pointer
1431 * @arg: type of lease to obtain
1432 * @lease: file_lock to use
1433 *
1434 * Call this to establish a lease on the file.
1435 * The (*lease)->fl_lmops->lm_break operation must be set; if not,
1436 * break_lease will oops!
1437 *
1438 * This will call the filesystem's setlease file method, if
1439 * defined. Note that there is no getlease method; instead, the
1440 * filesystem setlease method should call back to setlease() to
1441 * add a lease to the inode's lease list, where fcntl_getlease() can
1442 * find it. Since fcntl_getlease() only reports whether the current
1443 * task holds a lease, a cluster filesystem need only do this for
1444 * leases held by processes on this node.
1445 *
1446 * There is also no break_lease method; filesystems that
1447 * handle their own leases should break leases themselves from the
1448 * filesystem's open, create, and (on truncate) setattr methods.
1449 *
1450 * Warning: the only current setlease methods exist only to disable
1451 * leases in certain cases. More vfs changes may be required to
1452 * allow a full filesystem lease implementation.
1453 */
1454
1455int vfs_setlease(struct file *filp, long arg, struct file_lock **lease)
1456{
1457 int error;
1458
1459 lock_flocks();
1460 error = __vfs_setlease(filp, arg, lease);
1461 unlock_flocks();
1462
1463 return error;
1464}
1465EXPORT_SYMBOL_GPL(vfs_setlease);
1466
1467static int do_fcntl_delete_lease(struct file *filp)
1468{
1469 struct file_lock fl, *flp = &fl;
1470
1471 lease_init(filp, F_UNLCK, flp);
1472
1473 return vfs_setlease(filp, F_UNLCK, &flp);
1474}
1475
1476static int do_fcntl_add_lease(unsigned int fd, struct file *filp, long arg)
1477{
1478 struct file_lock *fl, *ret;
1479 struct fasync_struct *new;
1480 int error;
1481
1482 fl = lease_alloc(filp, arg);
1483 if (IS_ERR(fl))
1484 return PTR_ERR(fl);
1485
1486 new = fasync_alloc();
1487 if (!new) {
1488 locks_free_lock(fl);
1489 return -ENOMEM;
1490 }
1491 ret = fl;
1492 lock_flocks();
1493 error = __vfs_setlease(filp, arg, &ret);
1494 if (error) {
1495 unlock_flocks();
1496 locks_free_lock(fl);
1497 goto out_free_fasync;
1498 }
1499 if (ret != fl)
1500 locks_free_lock(fl);
1501
1502 /*
1503 * fasync_insert_entry() returns the old entry if any.
1504 * If there was no old entry, then it used 'new' and
1505 * inserted it into the fasync list. Clear new so that
1506 * we don't release it here.
1507 */
1508 if (!fasync_insert_entry(fd, filp, &ret->fl_fasync, new))
1509 new = NULL;
1510
1511 error = __f_setown(filp, task_pid(current), PIDTYPE_PID, 0);
1512 unlock_flocks();
1513
1514out_free_fasync:
1515 if (new)
1516 fasync_free(new);
1517 return error;
1518}
1519
1520/**
1521 * fcntl_setlease - sets a lease on an open file
1522 * @fd: open file descriptor
1523 * @filp: file pointer
1524 * @arg: type of lease to obtain
1525 *
1526 * Call this fcntl to establish a lease on the file.
1527 * Note that you also need to call %F_SETSIG to
1528 * receive a signal when the lease is broken.
1529 */
1530int fcntl_setlease(unsigned int fd, struct file *filp, long arg)
1531{
1532 if (arg == F_UNLCK)
1533 return do_fcntl_delete_lease(filp);
1534 return do_fcntl_add_lease(fd, filp, arg);
1535}
1536
1537/**
1538 * flock_lock_file_wait - Apply a FLOCK-style lock to a file
1539 * @filp: The file to apply the lock to
1540 * @fl: The lock to be applied
1541 *
1542 * Add a FLOCK style lock to a file.
1543 */
1544int flock_lock_file_wait(struct file *filp, struct file_lock *fl)
1545{
1546 int error;
1547 might_sleep();
1548 for (;;) {
1549 error = flock_lock_file(filp, fl);
1550 if (error != FILE_LOCK_DEFERRED)
1551 break;
1552 error = wait_event_interruptible(fl->fl_wait, !fl->fl_next);
1553 if (!error)
1554 continue;
1555
1556 locks_delete_block(fl);
1557 break;
1558 }
1559 return error;
1560}
1561
1562EXPORT_SYMBOL(flock_lock_file_wait);
1563
1564/**
1565 * sys_flock: - flock() system call.
1566 * @fd: the file descriptor to lock.
1567 * @cmd: the type of lock to apply.
1568 *
1569 * Apply a %FL_FLOCK style lock to an open file descriptor.
1570 * The @cmd can be one of
1571 *
1572 * %LOCK_SH -- a shared lock.
1573 *
1574 * %LOCK_EX -- an exclusive lock.
1575 *
1576 * %LOCK_UN -- remove an existing lock.
1577 *
1578 * %LOCK_MAND -- a `mandatory' flock. This exists to emulate Windows Share Modes.
1579 *
1580 * %LOCK_MAND can be combined with %LOCK_READ or %LOCK_WRITE to allow other
1581 * processes read and write access respectively.
1582 */
1583SYSCALL_DEFINE2(flock, unsigned int, fd, unsigned int, cmd)
1584{
1585 struct file *filp;
1586 struct file_lock *lock;
1587 int can_sleep, unlock;
1588 int error;
1589
1590 error = -EBADF;
1591 filp = fget(fd);
1592 if (!filp)
1593 goto out;
1594
1595 can_sleep = !(cmd & LOCK_NB);
1596 cmd &= ~LOCK_NB;
1597 unlock = (cmd == LOCK_UN);
1598
1599 if (!unlock && !(cmd & LOCK_MAND) &&
1600 !(filp->f_mode & (FMODE_READ|FMODE_WRITE)))
1601 goto out_putf;
1602
1603 error = flock_make_lock(filp, &lock, cmd);
1604 if (error)
1605 goto out_putf;
1606 if (can_sleep)
1607 lock->fl_flags |= FL_SLEEP;
1608
1609 error = security_file_lock(filp, lock->fl_type);
1610 if (error)
1611 goto out_free;
1612
1613 if (filp->f_op && filp->f_op->flock)
1614 error = filp->f_op->flock(filp,
1615 (can_sleep) ? F_SETLKW : F_SETLK,
1616 lock);
1617 else
1618 error = flock_lock_file_wait(filp, lock);
1619
1620 out_free:
1621 locks_free_lock(lock);
1622
1623 out_putf:
1624 fput(filp);
1625 out:
1626 return error;
1627}
1628
1629/**
1630 * vfs_test_lock - test file byte range lock
1631 * @filp: The file to test lock for
1632 * @fl: The lock to test; also used to hold result
1633 *
1634 * Returns -ERRNO on failure. Indicates presence of conflicting lock by
1635 * setting conf->fl_type to something other than F_UNLCK.
1636 */
1637int vfs_test_lock(struct file *filp, struct file_lock *fl)
1638{
1639 if (filp->f_op && filp->f_op->lock)
1640 return filp->f_op->lock(filp, F_GETLK, fl);
1641 posix_test_lock(filp, fl);
1642 return 0;
1643}
1644EXPORT_SYMBOL_GPL(vfs_test_lock);
1645
1646static int posix_lock_to_flock(struct flock *flock, struct file_lock *fl)
1647{
1648 flock->l_pid = fl->fl_pid;
1649#if BITS_PER_LONG == 32
1650 /*
1651 * Make sure we can represent the posix lock via
1652 * legacy 32bit flock.
1653 */
1654 if (fl->fl_start > OFFT_OFFSET_MAX)
1655 return -EOVERFLOW;
1656 if (fl->fl_end != OFFSET_MAX && fl->fl_end > OFFT_OFFSET_MAX)
1657 return -EOVERFLOW;
1658#endif
1659 flock->l_start = fl->fl_start;
1660 flock->l_len = fl->fl_end == OFFSET_MAX ? 0 :
1661 fl->fl_end - fl->fl_start + 1;
1662 flock->l_whence = 0;
1663 flock->l_type = fl->fl_type;
1664 return 0;
1665}
1666
1667#if BITS_PER_LONG == 32
1668static void posix_lock_to_flock64(struct flock64 *flock, struct file_lock *fl)
1669{
1670 flock->l_pid = fl->fl_pid;
1671 flock->l_start = fl->fl_start;
1672 flock->l_len = fl->fl_end == OFFSET_MAX ? 0 :
1673 fl->fl_end - fl->fl_start + 1;
1674 flock->l_whence = 0;
1675 flock->l_type = fl->fl_type;
1676}
1677#endif
1678
1679/* Report the first existing lock that would conflict with l.
1680 * This implements the F_GETLK command of fcntl().
1681 */
1682int fcntl_getlk(struct file *filp, struct flock __user *l)
1683{
1684 struct file_lock file_lock;
1685 struct flock flock;
1686 int error;
1687
1688 error = -EFAULT;
1689 if (copy_from_user(&flock, l, sizeof(flock)))
1690 goto out;
1691 error = -EINVAL;
1692 if ((flock.l_type != F_RDLCK) && (flock.l_type != F_WRLCK))
1693 goto out;
1694
1695 error = flock_to_posix_lock(filp, &file_lock, &flock);
1696 if (error)
1697 goto out;
1698
1699 error = vfs_test_lock(filp, &file_lock);
1700 if (error)
1701 goto out;
1702
1703 flock.l_type = file_lock.fl_type;
1704 if (file_lock.fl_type != F_UNLCK) {
1705 error = posix_lock_to_flock(&flock, &file_lock);
1706 if (error)
1707 goto out;
1708 }
1709 error = -EFAULT;
1710 if (!copy_to_user(l, &flock, sizeof(flock)))
1711 error = 0;
1712out:
1713 return error;
1714}
1715
1716/**
1717 * vfs_lock_file - file byte range lock
1718 * @filp: The file to apply the lock to
1719 * @cmd: type of locking operation (F_SETLK, F_GETLK, etc.)
1720 * @fl: The lock to be applied
1721 * @conf: Place to return a copy of the conflicting lock, if found.
1722 *
1723 * A caller that doesn't care about the conflicting lock may pass NULL
1724 * as the final argument.
1725 *
1726 * If the filesystem defines a private ->lock() method, then @conf will
1727 * be left unchanged; so a caller that cares should initialize it to
1728 * some acceptable default.
1729 *
1730 * To avoid blocking kernel daemons, such as lockd, that need to acquire POSIX
1731 * locks, the ->lock() interface may return asynchronously, before the lock has
1732 * been granted or denied by the underlying filesystem, if (and only if)
1733 * lm_grant is set. Callers expecting ->lock() to return asynchronously
1734 * will only use F_SETLK, not F_SETLKW; they will set FL_SLEEP if (and only if)
1735 * the request is for a blocking lock. When ->lock() does return asynchronously,
1736 * it must return FILE_LOCK_DEFERRED, and call ->lm_grant() when the lock
1737 * request completes.
1738 * If the request is for non-blocking lock the file system should return
1739 * FILE_LOCK_DEFERRED then try to get the lock and call the callback routine
1740 * with the result. If the request timed out the callback routine will return a
1741 * nonzero return code and the file system should release the lock. The file
1742 * system is also responsible to keep a corresponding posix lock when it
1743 * grants a lock so the VFS can find out which locks are locally held and do
1744 * the correct lock cleanup when required.
1745 * The underlying filesystem must not drop the kernel lock or call
1746 * ->lm_grant() before returning to the caller with a FILE_LOCK_DEFERRED
1747 * return code.
1748 */
1749int vfs_lock_file(struct file *filp, unsigned int cmd, struct file_lock *fl, struct file_lock *conf)
1750{
1751 if (filp->f_op && filp->f_op->lock)
1752 return filp->f_op->lock(filp, cmd, fl);
1753 else
1754 return posix_lock_file(filp, fl, conf);
1755}
1756EXPORT_SYMBOL_GPL(vfs_lock_file);
1757
1758static int do_lock_file_wait(struct file *filp, unsigned int cmd,
1759 struct file_lock *fl)
1760{
1761 int error;
1762
1763 error = security_file_lock(filp, fl->fl_type);
1764 if (error)
1765 return error;
1766
1767 for (;;) {
1768 error = vfs_lock_file(filp, cmd, fl, NULL);
1769 if (error != FILE_LOCK_DEFERRED)
1770 break;
1771 error = wait_event_interruptible(fl->fl_wait, !fl->fl_next);
1772 if (!error)
1773 continue;
1774
1775 locks_delete_block(fl);
1776 break;
1777 }
1778
1779 return error;
1780}
1781
1782/* Apply the lock described by l to an open file descriptor.
1783 * This implements both the F_SETLK and F_SETLKW commands of fcntl().
1784 */
1785int fcntl_setlk(unsigned int fd, struct file *filp, unsigned int cmd,
1786 struct flock __user *l)
1787{
1788 struct file_lock *file_lock = locks_alloc_lock();
1789 struct flock flock;
1790 struct inode *inode;
1791 struct file *f;
1792 int error;
1793
1794 if (file_lock == NULL)
1795 return -ENOLCK;
1796
1797 /*
1798 * This might block, so we do it before checking the inode.
1799 */
1800 error = -EFAULT;
1801 if (copy_from_user(&flock, l, sizeof(flock)))
1802 goto out;
1803
1804 inode = filp->f_path.dentry->d_inode;
1805
1806 /* Don't allow mandatory locks on files that may be memory mapped
1807 * and shared.
1808 */
1809 if (mandatory_lock(inode) && mapping_writably_mapped(filp->f_mapping)) {
1810 error = -EAGAIN;
1811 goto out;
1812 }
1813
1814again:
1815 error = flock_to_posix_lock(filp, file_lock, &flock);
1816 if (error)
1817 goto out;
1818 if (cmd == F_SETLKW) {
1819 file_lock->fl_flags |= FL_SLEEP;
1820 }
1821
1822 error = -EBADF;
1823 switch (flock.l_type) {
1824 case F_RDLCK:
1825 if (!(filp->f_mode & FMODE_READ))
1826 goto out;
1827 break;
1828 case F_WRLCK:
1829 if (!(filp->f_mode & FMODE_WRITE))
1830 goto out;
1831 break;
1832 case F_UNLCK:
1833 break;
1834 default:
1835 error = -EINVAL;
1836 goto out;
1837 }
1838
1839 error = do_lock_file_wait(filp, cmd, file_lock);
1840
1841 /*
1842 * Attempt to detect a close/fcntl race and recover by
1843 * releasing the lock that was just acquired.
1844 */
1845 /*
1846 * we need that spin_lock here - it prevents reordering between
1847 * update of inode->i_flock and check for it done in close().
1848 * rcu_read_lock() wouldn't do.
1849 */
1850 spin_lock(¤t->files->file_lock);
1851 f = fcheck(fd);
1852 spin_unlock(¤t->files->file_lock);
1853 if (!error && f != filp && flock.l_type != F_UNLCK) {
1854 flock.l_type = F_UNLCK;
1855 goto again;
1856 }
1857
1858out:
1859 locks_free_lock(file_lock);
1860 return error;
1861}
1862
1863#if BITS_PER_LONG == 32
1864/* Report the first existing lock that would conflict with l.
1865 * This implements the F_GETLK command of fcntl().
1866 */
1867int fcntl_getlk64(struct file *filp, struct flock64 __user *l)
1868{
1869 struct file_lock file_lock;
1870 struct flock64 flock;
1871 int error;
1872
1873 error = -EFAULT;
1874 if (copy_from_user(&flock, l, sizeof(flock)))
1875 goto out;
1876 error = -EINVAL;
1877 if ((flock.l_type != F_RDLCK) && (flock.l_type != F_WRLCK))
1878 goto out;
1879
1880 error = flock64_to_posix_lock(filp, &file_lock, &flock);
1881 if (error)
1882 goto out;
1883
1884 error = vfs_test_lock(filp, &file_lock);
1885 if (error)
1886 goto out;
1887
1888 flock.l_type = file_lock.fl_type;
1889 if (file_lock.fl_type != F_UNLCK)
1890 posix_lock_to_flock64(&flock, &file_lock);
1891
1892 error = -EFAULT;
1893 if (!copy_to_user(l, &flock, sizeof(flock)))
1894 error = 0;
1895
1896out:
1897 return error;
1898}
1899
1900/* Apply the lock described by l to an open file descriptor.
1901 * This implements both the F_SETLK and F_SETLKW commands of fcntl().
1902 */
1903int fcntl_setlk64(unsigned int fd, struct file *filp, unsigned int cmd,
1904 struct flock64 __user *l)
1905{
1906 struct file_lock *file_lock = locks_alloc_lock();
1907 struct flock64 flock;
1908 struct inode *inode;
1909 struct file *f;
1910 int error;
1911
1912 if (file_lock == NULL)
1913 return -ENOLCK;
1914
1915 /*
1916 * This might block, so we do it before checking the inode.
1917 */
1918 error = -EFAULT;
1919 if (copy_from_user(&flock, l, sizeof(flock)))
1920 goto out;
1921
1922 inode = filp->f_path.dentry->d_inode;
1923
1924 /* Don't allow mandatory locks on files that may be memory mapped
1925 * and shared.
1926 */
1927 if (mandatory_lock(inode) && mapping_writably_mapped(filp->f_mapping)) {
1928 error = -EAGAIN;
1929 goto out;
1930 }
1931
1932again:
1933 error = flock64_to_posix_lock(filp, file_lock, &flock);
1934 if (error)
1935 goto out;
1936 if (cmd == F_SETLKW64) {
1937 file_lock->fl_flags |= FL_SLEEP;
1938 }
1939
1940 error = -EBADF;
1941 switch (flock.l_type) {
1942 case F_RDLCK:
1943 if (!(filp->f_mode & FMODE_READ))
1944 goto out;
1945 break;
1946 case F_WRLCK:
1947 if (!(filp->f_mode & FMODE_WRITE))
1948 goto out;
1949 break;
1950 case F_UNLCK:
1951 break;
1952 default:
1953 error = -EINVAL;
1954 goto out;
1955 }
1956
1957 error = do_lock_file_wait(filp, cmd, file_lock);
1958
1959 /*
1960 * Attempt to detect a close/fcntl race and recover by
1961 * releasing the lock that was just acquired.
1962 */
1963 spin_lock(¤t->files->file_lock);
1964 f = fcheck(fd);
1965 spin_unlock(¤t->files->file_lock);
1966 if (!error && f != filp && flock.l_type != F_UNLCK) {
1967 flock.l_type = F_UNLCK;
1968 goto again;
1969 }
1970
1971out:
1972 locks_free_lock(file_lock);
1973 return error;
1974}
1975#endif /* BITS_PER_LONG == 32 */
1976
1977/*
1978 * This function is called when the file is being removed
1979 * from the task's fd array. POSIX locks belonging to this task
1980 * are deleted at this time.
1981 */
1982void locks_remove_posix(struct file *filp, fl_owner_t owner)
1983{
1984 struct file_lock lock;
1985
1986 /*
1987 * If there are no locks held on this file, we don't need to call
1988 * posix_lock_file(). Another process could be setting a lock on this
1989 * file at the same time, but we wouldn't remove that lock anyway.
1990 */
1991 if (!filp->f_path.dentry->d_inode->i_flock)
1992 return;
1993
1994 lock.fl_type = F_UNLCK;
1995 lock.fl_flags = FL_POSIX | FL_CLOSE;
1996 lock.fl_start = 0;
1997 lock.fl_end = OFFSET_MAX;
1998 lock.fl_owner = owner;
1999 lock.fl_pid = current->tgid;
2000 lock.fl_file = filp;
2001 lock.fl_ops = NULL;
2002 lock.fl_lmops = NULL;
2003
2004 vfs_lock_file(filp, F_SETLK, &lock, NULL);
2005
2006 if (lock.fl_ops && lock.fl_ops->fl_release_private)
2007 lock.fl_ops->fl_release_private(&lock);
2008}
2009
2010EXPORT_SYMBOL(locks_remove_posix);
2011
2012/*
2013 * This function is called on the last close of an open file.
2014 */
2015void locks_remove_flock(struct file *filp)
2016{
2017 struct inode * inode = filp->f_path.dentry->d_inode;
2018 struct file_lock *fl;
2019 struct file_lock **before;
2020
2021 if (!inode->i_flock)
2022 return;
2023
2024 if (filp->f_op && filp->f_op->flock) {
2025 struct file_lock fl = {
2026 .fl_pid = current->tgid,
2027 .fl_file = filp,
2028 .fl_flags = FL_FLOCK,
2029 .fl_type = F_UNLCK,
2030 .fl_end = OFFSET_MAX,
2031 };
2032 filp->f_op->flock(filp, F_SETLKW, &fl);
2033 if (fl.fl_ops && fl.fl_ops->fl_release_private)
2034 fl.fl_ops->fl_release_private(&fl);
2035 }
2036
2037 lock_flocks();
2038 before = &inode->i_flock;
2039
2040 while ((fl = *before) != NULL) {
2041 if (fl->fl_file == filp) {
2042 if (IS_FLOCK(fl)) {
2043 locks_delete_lock(before);
2044 continue;
2045 }
2046 if (IS_LEASE(fl)) {
2047 lease_modify(before, F_UNLCK);
2048 continue;
2049 }
2050 /* What? */
2051 BUG();
2052 }
2053 before = &fl->fl_next;
2054 }
2055 unlock_flocks();
2056}
2057
2058/**
2059 * posix_unblock_lock - stop waiting for a file lock
2060 * @filp: how the file was opened
2061 * @waiter: the lock which was waiting
2062 *
2063 * lockd needs to block waiting for locks.
2064 */
2065int
2066posix_unblock_lock(struct file *filp, struct file_lock *waiter)
2067{
2068 int status = 0;
2069
2070 lock_flocks();
2071 if (waiter->fl_next)
2072 __locks_delete_block(waiter);
2073 else
2074 status = -ENOENT;
2075 unlock_flocks();
2076 return status;
2077}
2078
2079EXPORT_SYMBOL(posix_unblock_lock);
2080
2081/**
2082 * vfs_cancel_lock - file byte range unblock lock
2083 * @filp: The file to apply the unblock to
2084 * @fl: The lock to be unblocked
2085 *
2086 * Used by lock managers to cancel blocked requests
2087 */
2088int vfs_cancel_lock(struct file *filp, struct file_lock *fl)
2089{
2090 if (filp->f_op && filp->f_op->lock)
2091 return filp->f_op->lock(filp, F_CANCELLK, fl);
2092 return 0;
2093}
2094
2095EXPORT_SYMBOL_GPL(vfs_cancel_lock);
2096
2097#ifdef CONFIG_PROC_FS
2098#include <linux/proc_fs.h>
2099#include <linux/seq_file.h>
2100
2101static void lock_get_status(struct seq_file *f, struct file_lock *fl,
2102 loff_t id, char *pfx)
2103{
2104 struct inode *inode = NULL;
2105 unsigned int fl_pid;
2106
2107 if (fl->fl_nspid)
2108 fl_pid = pid_vnr(fl->fl_nspid);
2109 else
2110 fl_pid = fl->fl_pid;
2111
2112 if (fl->fl_file != NULL)
2113 inode = fl->fl_file->f_path.dentry->d_inode;
2114
2115 seq_printf(f, "%lld:%s ", id, pfx);
2116 if (IS_POSIX(fl)) {
2117 seq_printf(f, "%6s %s ",
2118 (fl->fl_flags & FL_ACCESS) ? "ACCESS" : "POSIX ",
2119 (inode == NULL) ? "*NOINODE*" :
2120 mandatory_lock(inode) ? "MANDATORY" : "ADVISORY ");
2121 } else if (IS_FLOCK(fl)) {
2122 if (fl->fl_type & LOCK_MAND) {
2123 seq_printf(f, "FLOCK MSNFS ");
2124 } else {
2125 seq_printf(f, "FLOCK ADVISORY ");
2126 }
2127 } else if (IS_LEASE(fl)) {
2128 seq_printf(f, "LEASE ");
2129 if (fl->fl_type & F_INPROGRESS)
2130 seq_printf(f, "BREAKING ");
2131 else if (fl->fl_file)
2132 seq_printf(f, "ACTIVE ");
2133 else
2134 seq_printf(f, "BREAKER ");
2135 } else {
2136 seq_printf(f, "UNKNOWN UNKNOWN ");
2137 }
2138 if (fl->fl_type & LOCK_MAND) {
2139 seq_printf(f, "%s ",
2140 (fl->fl_type & LOCK_READ)
2141 ? (fl->fl_type & LOCK_WRITE) ? "RW " : "READ "
2142 : (fl->fl_type & LOCK_WRITE) ? "WRITE" : "NONE ");
2143 } else {
2144 seq_printf(f, "%s ",
2145 (fl->fl_type & F_INPROGRESS)
2146 ? (fl->fl_type & F_UNLCK) ? "UNLCK" : "READ "
2147 : (fl->fl_type & F_WRLCK) ? "WRITE" : "READ ");
2148 }
2149 if (inode) {
2150#ifdef WE_CAN_BREAK_LSLK_NOW
2151 seq_printf(f, "%d %s:%ld ", fl_pid,
2152 inode->i_sb->s_id, inode->i_ino);
2153#else
2154 /* userspace relies on this representation of dev_t ;-( */
2155 seq_printf(f, "%d %02x:%02x:%ld ", fl_pid,
2156 MAJOR(inode->i_sb->s_dev),
2157 MINOR(inode->i_sb->s_dev), inode->i_ino);
2158#endif
2159 } else {
2160 seq_printf(f, "%d <none>:0 ", fl_pid);
2161 }
2162 if (IS_POSIX(fl)) {
2163 if (fl->fl_end == OFFSET_MAX)
2164 seq_printf(f, "%Ld EOF\n", fl->fl_start);
2165 else
2166 seq_printf(f, "%Ld %Ld\n", fl->fl_start, fl->fl_end);
2167 } else {
2168 seq_printf(f, "0 EOF\n");
2169 }
2170}
2171
2172static int locks_show(struct seq_file *f, void *v)
2173{
2174 struct file_lock *fl, *bfl;
2175
2176 fl = list_entry(v, struct file_lock, fl_link);
2177
2178 lock_get_status(f, fl, *((loff_t *)f->private), "");
2179
2180 list_for_each_entry(bfl, &fl->fl_block, fl_block)
2181 lock_get_status(f, bfl, *((loff_t *)f->private), " ->");
2182
2183 return 0;
2184}
2185
2186static void *locks_start(struct seq_file *f, loff_t *pos)
2187{
2188 loff_t *p = f->private;
2189
2190 lock_flocks();
2191 *p = (*pos + 1);
2192 return seq_list_start(&file_lock_list, *pos);
2193}
2194
2195static void *locks_next(struct seq_file *f, void *v, loff_t *pos)
2196{
2197 loff_t *p = f->private;
2198 ++*p;
2199 return seq_list_next(v, &file_lock_list, pos);
2200}
2201
2202static void locks_stop(struct seq_file *f, void *v)
2203{
2204 unlock_flocks();
2205}
2206
2207static const struct seq_operations locks_seq_operations = {
2208 .start = locks_start,
2209 .next = locks_next,
2210 .stop = locks_stop,
2211 .show = locks_show,
2212};
2213
2214static int locks_open(struct inode *inode, struct file *filp)
2215{
2216 return seq_open_private(filp, &locks_seq_operations, sizeof(loff_t));
2217}
2218
2219static const struct file_operations proc_locks_operations = {
2220 .open = locks_open,
2221 .read = seq_read,
2222 .llseek = seq_lseek,
2223 .release = seq_release_private,
2224};
2225
2226static int __init proc_locks_init(void)
2227{
2228 proc_create("locks", 0, NULL, &proc_locks_operations);
2229 return 0;
2230}
2231module_init(proc_locks_init);
2232#endif
2233
2234/**
2235 * lock_may_read - checks that the region is free of locks
2236 * @inode: the inode that is being read
2237 * @start: the first byte to read
2238 * @len: the number of bytes to read
2239 *
2240 * Emulates Windows locking requirements. Whole-file
2241 * mandatory locks (share modes) can prohibit a read and
2242 * byte-range POSIX locks can prohibit a read if they overlap.
2243 *
2244 * N.B. this function is only ever called
2245 * from knfsd and ownership of locks is never checked.
2246 */
2247int lock_may_read(struct inode *inode, loff_t start, unsigned long len)
2248{
2249 struct file_lock *fl;
2250 int result = 1;
2251 lock_flocks();
2252 for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) {
2253 if (IS_POSIX(fl)) {
2254 if (fl->fl_type == F_RDLCK)
2255 continue;
2256 if ((fl->fl_end < start) || (fl->fl_start > (start + len)))
2257 continue;
2258 } else if (IS_FLOCK(fl)) {
2259 if (!(fl->fl_type & LOCK_MAND))
2260 continue;
2261 if (fl->fl_type & LOCK_READ)
2262 continue;
2263 } else
2264 continue;
2265 result = 0;
2266 break;
2267 }
2268 unlock_flocks();
2269 return result;
2270}
2271
2272EXPORT_SYMBOL(lock_may_read);
2273
2274/**
2275 * lock_may_write - checks that the region is free of locks
2276 * @inode: the inode that is being written
2277 * @start: the first byte to write
2278 * @len: the number of bytes to write
2279 *
2280 * Emulates Windows locking requirements. Whole-file
2281 * mandatory locks (share modes) can prohibit a write and
2282 * byte-range POSIX locks can prohibit a write if they overlap.
2283 *
2284 * N.B. this function is only ever called
2285 * from knfsd and ownership of locks is never checked.
2286 */
2287int lock_may_write(struct inode *inode, loff_t start, unsigned long len)
2288{
2289 struct file_lock *fl;
2290 int result = 1;
2291 lock_flocks();
2292 for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) {
2293 if (IS_POSIX(fl)) {
2294 if ((fl->fl_end < start) || (fl->fl_start > (start + len)))
2295 continue;
2296 } else if (IS_FLOCK(fl)) {
2297 if (!(fl->fl_type & LOCK_MAND))
2298 continue;
2299 if (fl->fl_type & LOCK_WRITE)
2300 continue;
2301 } else
2302 continue;
2303 result = 0;
2304 break;
2305 }
2306 unlock_flocks();
2307 return result;
2308}
2309
2310EXPORT_SYMBOL(lock_may_write);
2311
2312static int __init filelock_init(void)
2313{
2314 filelock_cache = kmem_cache_create("file_lock_cache",
2315 sizeof(struct file_lock), 0, SLAB_PANIC, NULL);
2316
2317 return 0;
2318}
2319
2320core_initcall(filelock_init);