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