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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// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * linux/fs/locks.c
4 *
5 * Provide support for fcntl()'s F_GETLK, F_SETLK, and F_SETLKW calls.
6 * Doug Evans (dje@spiff.uucp), August 07, 1992
7 *
8 * Deadlock detection added.
9 * FIXME: one thing isn't handled yet:
10 * - mandatory locks (requires lots of changes elsewhere)
11 * Kelly Carmichael (kelly@[142.24.8.65]), September 17, 1994.
12 *
13 * Miscellaneous edits, and a total rewrite of posix_lock_file() code.
14 * Kai Petzke (wpp@marie.physik.tu-berlin.de), 1994
15 *
16 * Converted file_lock_table to a linked list from an array, which eliminates
17 * the limits on how many active file locks are open.
18 * Chad Page (pageone@netcom.com), November 27, 1994
19 *
20 * Removed dependency on file descriptors. dup()'ed file descriptors now
21 * get the same locks as the original file descriptors, and a close() on
22 * any file descriptor removes ALL the locks on the file for the current
23 * process. Since locks still depend on the process id, locks are inherited
24 * after an exec() but not after a fork(). This agrees with POSIX, and both
25 * BSD and SVR4 practice.
26 * Andy Walker (andy@lysaker.kvaerner.no), February 14, 1995
27 *
28 * Scrapped free list which is redundant now that we allocate locks
29 * dynamically with kmalloc()/kfree().
30 * Andy Walker (andy@lysaker.kvaerner.no), February 21, 1995
31 *
32 * Implemented two lock personalities - FL_FLOCK and FL_POSIX.
33 *
34 * FL_POSIX locks are created with calls to fcntl() and lockf() through the
35 * fcntl() system call. They have the semantics described above.
36 *
37 * FL_FLOCK locks are created with calls to flock(), through the flock()
38 * system call, which is new. Old C libraries implement flock() via fcntl()
39 * and will continue to use the old, broken implementation.
40 *
41 * FL_FLOCK locks follow the 4.4 BSD flock() semantics. They are associated
42 * with a file pointer (filp). As a result they can be shared by a parent
43 * process and its children after a fork(). They are removed when the last
44 * file descriptor referring to the file pointer is closed (unless explicitly
45 * unlocked).
46 *
47 * FL_FLOCK locks never deadlock, an existing lock is always removed before
48 * upgrading from shared to exclusive (or vice versa). When this happens
49 * any processes blocked by the current lock are woken up and allowed to
50 * run before the new lock is applied.
51 * Andy Walker (andy@lysaker.kvaerner.no), June 09, 1995
52 *
53 * Removed some race conditions in flock_lock_file(), marked other possible
54 * races. Just grep for FIXME to see them.
55 * Dmitry Gorodchanin (pgmdsg@ibi.com), February 09, 1996.
56 *
57 * Addressed Dmitry's concerns. Deadlock checking no longer recursive.
58 * Lock allocation changed to GFP_ATOMIC as we can't afford to sleep
59 * once we've checked for blocking and deadlocking.
60 * Andy Walker (andy@lysaker.kvaerner.no), April 03, 1996.
61 *
62 * Initial implementation of mandatory locks. SunOS turned out to be
63 * a rotten model, so I implemented the "obvious" semantics.
64 * See 'Documentation/filesystems/mandatory-locking.txt' for details.
65 * Andy Walker (andy@lysaker.kvaerner.no), April 06, 1996.
66 *
67 * Don't allow mandatory locks on mmap()'ed files. Added simple functions to
68 * check if a file has mandatory locks, used by mmap(), open() and creat() to
69 * see if system call should be rejected. Ref. HP-UX/SunOS/Solaris Reference
70 * Manual, Section 2.
71 * Andy Walker (andy@lysaker.kvaerner.no), April 09, 1996.
72 *
73 * Tidied up block list handling. Added '/proc/locks' interface.
74 * Andy Walker (andy@lysaker.kvaerner.no), April 24, 1996.
75 *
76 * Fixed deadlock condition for pathological code that mixes calls to
77 * flock() and fcntl().
78 * Andy Walker (andy@lysaker.kvaerner.no), April 29, 1996.
79 *
80 * Allow only one type of locking scheme (FL_POSIX or FL_FLOCK) to be in use
81 * for a given file at a time. Changed the CONFIG_LOCK_MANDATORY scheme to
82 * guarantee sensible behaviour in the case where file system modules might
83 * be compiled with different options than the kernel itself.
84 * Andy Walker (andy@lysaker.kvaerner.no), May 15, 1996.
85 *
86 * Added a couple of missing wake_up() calls. Thanks to Thomas Meckel
87 * (Thomas.Meckel@mni.fh-giessen.de) for spotting this.
88 * Andy Walker (andy@lysaker.kvaerner.no), May 15, 1996.
89 *
90 * Changed FL_POSIX locks to use the block list in the same way as FL_FLOCK
91 * locks. Changed process synchronisation to avoid dereferencing locks that
92 * have already been freed.
93 * Andy Walker (andy@lysaker.kvaerner.no), Sep 21, 1996.
94 *
95 * Made the block list a circular list to minimise searching in the list.
96 * Andy Walker (andy@lysaker.kvaerner.no), Sep 25, 1996.
97 *
98 * Made mandatory locking a mount option. Default is not to allow mandatory
99 * locking.
100 * Andy Walker (andy@lysaker.kvaerner.no), Oct 04, 1996.
101 *
102 * Some adaptations for NFS support.
103 * Olaf Kirch (okir@monad.swb.de), Dec 1996,
104 *
105 * Fixed /proc/locks interface so that we can't overrun the buffer we are handed.
106 * Andy Walker (andy@lysaker.kvaerner.no), May 12, 1997.
107 *
108 * Use slab allocator instead of kmalloc/kfree.
109 * Use generic list implementation from <linux/list.h>.
110 * Sped up posix_locks_deadlock by only considering blocked locks.
111 * Matthew Wilcox <willy@debian.org>, March, 2000.
112 *
113 * Leases and LOCK_MAND
114 * Matthew Wilcox <willy@debian.org>, June, 2000.
115 * Stephen Rothwell <sfr@canb.auug.org.au>, June, 2000.
116 *
117 * Locking conflicts and dependencies:
118 * If multiple threads attempt to lock the same byte (or flock the same file)
119 * only one can be granted the lock, and other must wait their turn.
120 * The first lock has been "applied" or "granted", the others are "waiting"
121 * and are "blocked" by the "applied" lock..
122 *
123 * Waiting and applied locks are all kept in trees whose properties are:
124 *
125 * - the root of a tree may be an applied or waiting lock.
126 * - every other node in the tree is a waiting lock that
127 * conflicts with every ancestor of that node.
128 *
129 * Every such tree begins life as a waiting singleton which obviously
130 * satisfies the above properties.
131 *
132 * The only ways we modify trees preserve these properties:
133 *
134 * 1. We may add a new leaf node, but only after first verifying that it
135 * conflicts with all of its ancestors.
136 * 2. We may remove the root of a tree, creating a new singleton
137 * tree from the root and N new trees rooted in the immediate
138 * children.
139 * 3. If the root of a tree is not currently an applied lock, we may
140 * apply it (if possible).
141 * 4. We may upgrade the root of the tree (either extend its range,
142 * or upgrade its entire range from read to write).
143 *
144 * When an applied lock is modified in a way that reduces or downgrades any
145 * part of its range, we remove all its children (2 above). This particularly
146 * happens when a lock is unlocked.
147 *
148 * For each of those child trees we "wake up" the thread which is
149 * waiting for the lock so it can continue handling as follows: if the
150 * root of the tree applies, we do so (3). If it doesn't, it must
151 * conflict with some applied lock. We remove (wake up) all of its children
152 * (2), and add it is a new leaf to the tree rooted in the applied
153 * lock (1). We then repeat the process recursively with those
154 * children.
155 *
156 */
157
158#include <linux/capability.h>
159#include <linux/file.h>
160#include <linux/fdtable.h>
161#include <linux/fs.h>
162#include <linux/init.h>
163#include <linux/security.h>
164#include <linux/slab.h>
165#include <linux/syscalls.h>
166#include <linux/time.h>
167#include <linux/rcupdate.h>
168#include <linux/pid_namespace.h>
169#include <linux/hashtable.h>
170#include <linux/percpu.h>
171
172#define CREATE_TRACE_POINTS
173#include <trace/events/filelock.h>
174
175#include <linux/uaccess.h>
176
177#define IS_POSIX(fl) (fl->fl_flags & FL_POSIX)
178#define IS_FLOCK(fl) (fl->fl_flags & FL_FLOCK)
179#define IS_LEASE(fl) (fl->fl_flags & (FL_LEASE|FL_DELEG|FL_LAYOUT))
180#define IS_OFDLCK(fl) (fl->fl_flags & FL_OFDLCK)
181#define IS_REMOTELCK(fl) (fl->fl_pid <= 0)
182
183static bool lease_breaking(struct file_lock *fl)
184{
185 return fl->fl_flags & (FL_UNLOCK_PENDING | FL_DOWNGRADE_PENDING);
186}
187
188static int target_leasetype(struct file_lock *fl)
189{
190 if (fl->fl_flags & FL_UNLOCK_PENDING)
191 return F_UNLCK;
192 if (fl->fl_flags & FL_DOWNGRADE_PENDING)
193 return F_RDLCK;
194 return fl->fl_type;
195}
196
197int leases_enable = 1;
198int lease_break_time = 45;
199
200/*
201 * The global file_lock_list is only used for displaying /proc/locks, so we
202 * keep a list on each CPU, with each list protected by its own spinlock.
203 * Global serialization is done using file_rwsem.
204 *
205 * Note that alterations to the list also require that the relevant flc_lock is
206 * held.
207 */
208struct file_lock_list_struct {
209 spinlock_t lock;
210 struct hlist_head hlist;
211};
212static DEFINE_PER_CPU(struct file_lock_list_struct, file_lock_list);
213DEFINE_STATIC_PERCPU_RWSEM(file_rwsem);
214
215
216/*
217 * The blocked_hash is used to find POSIX lock loops for deadlock detection.
218 * It is protected by blocked_lock_lock.
219 *
220 * We hash locks by lockowner in order to optimize searching for the lock a
221 * particular lockowner is waiting on.
222 *
223 * FIXME: make this value scale via some heuristic? We generally will want more
224 * buckets when we have more lockowners holding locks, but that's a little
225 * difficult to determine without knowing what the workload will look like.
226 */
227#define BLOCKED_HASH_BITS 7
228static DEFINE_HASHTABLE(blocked_hash, BLOCKED_HASH_BITS);
229
230/*
231 * This lock protects the blocked_hash. Generally, if you're accessing it, you
232 * want to be holding this lock.
233 *
234 * In addition, it also protects the fl->fl_blocked_requests list, and the
235 * fl->fl_blocker pointer for file_lock structures that are acting as lock
236 * requests (in contrast to those that are acting as records of acquired locks).
237 *
238 * Note that when we acquire this lock in order to change the above fields,
239 * we often hold the flc_lock as well. In certain cases, when reading the fields
240 * protected by this lock, we can skip acquiring it iff we already hold the
241 * flc_lock.
242 */
243static DEFINE_SPINLOCK(blocked_lock_lock);
244
245static struct kmem_cache *flctx_cache __read_mostly;
246static struct kmem_cache *filelock_cache __read_mostly;
247
248static struct file_lock_context *
249locks_get_lock_context(struct inode *inode, int type)
250{
251 struct file_lock_context *ctx;
252
253 /* paired with cmpxchg() below */
254 ctx = smp_load_acquire(&inode->i_flctx);
255 if (likely(ctx) || type == F_UNLCK)
256 goto out;
257
258 ctx = kmem_cache_alloc(flctx_cache, GFP_KERNEL);
259 if (!ctx)
260 goto out;
261
262 spin_lock_init(&ctx->flc_lock);
263 INIT_LIST_HEAD(&ctx->flc_flock);
264 INIT_LIST_HEAD(&ctx->flc_posix);
265 INIT_LIST_HEAD(&ctx->flc_lease);
266
267 /*
268 * Assign the pointer if it's not already assigned. If it is, then
269 * free the context we just allocated.
270 */
271 if (cmpxchg(&inode->i_flctx, NULL, ctx)) {
272 kmem_cache_free(flctx_cache, ctx);
273 ctx = smp_load_acquire(&inode->i_flctx);
274 }
275out:
276 trace_locks_get_lock_context(inode, type, ctx);
277 return ctx;
278}
279
280static void
281locks_dump_ctx_list(struct list_head *list, char *list_type)
282{
283 struct file_lock *fl;
284
285 list_for_each_entry(fl, list, fl_list) {
286 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);
287 }
288}
289
290static void
291locks_check_ctx_lists(struct inode *inode)
292{
293 struct file_lock_context *ctx = inode->i_flctx;
294
295 if (unlikely(!list_empty(&ctx->flc_flock) ||
296 !list_empty(&ctx->flc_posix) ||
297 !list_empty(&ctx->flc_lease))) {
298 pr_warn("Leaked locks on dev=0x%x:0x%x ino=0x%lx:\n",
299 MAJOR(inode->i_sb->s_dev), MINOR(inode->i_sb->s_dev),
300 inode->i_ino);
301 locks_dump_ctx_list(&ctx->flc_flock, "FLOCK");
302 locks_dump_ctx_list(&ctx->flc_posix, "POSIX");
303 locks_dump_ctx_list(&ctx->flc_lease, "LEASE");
304 }
305}
306
307static void
308locks_check_ctx_file_list(struct file *filp, struct list_head *list,
309 char *list_type)
310{
311 struct file_lock *fl;
312 struct inode *inode = locks_inode(filp);
313
314 list_for_each_entry(fl, list, fl_list)
315 if (fl->fl_file == filp)
316 pr_warn("Leaked %s lock on dev=0x%x:0x%x ino=0x%lx "
317 " fl_owner=%p fl_flags=0x%x fl_type=0x%x fl_pid=%u\n",
318 list_type, MAJOR(inode->i_sb->s_dev),
319 MINOR(inode->i_sb->s_dev), inode->i_ino,
320 fl->fl_owner, fl->fl_flags, fl->fl_type, fl->fl_pid);
321}
322
323void
324locks_free_lock_context(struct inode *inode)
325{
326 struct file_lock_context *ctx = inode->i_flctx;
327
328 if (unlikely(ctx)) {
329 locks_check_ctx_lists(inode);
330 kmem_cache_free(flctx_cache, ctx);
331 }
332}
333
334static void locks_init_lock_heads(struct file_lock *fl)
335{
336 INIT_HLIST_NODE(&fl->fl_link);
337 INIT_LIST_HEAD(&fl->fl_list);
338 INIT_LIST_HEAD(&fl->fl_blocked_requests);
339 INIT_LIST_HEAD(&fl->fl_blocked_member);
340 init_waitqueue_head(&fl->fl_wait);
341}
342
343/* Allocate an empty lock structure. */
344struct file_lock *locks_alloc_lock(void)
345{
346 struct file_lock *fl = kmem_cache_zalloc(filelock_cache, GFP_KERNEL);
347
348 if (fl)
349 locks_init_lock_heads(fl);
350
351 return fl;
352}
353EXPORT_SYMBOL_GPL(locks_alloc_lock);
354
355void locks_release_private(struct file_lock *fl)
356{
357 BUG_ON(waitqueue_active(&fl->fl_wait));
358 BUG_ON(!list_empty(&fl->fl_list));
359 BUG_ON(!list_empty(&fl->fl_blocked_requests));
360 BUG_ON(!list_empty(&fl->fl_blocked_member));
361 BUG_ON(!hlist_unhashed(&fl->fl_link));
362
363 if (fl->fl_ops) {
364 if (fl->fl_ops->fl_release_private)
365 fl->fl_ops->fl_release_private(fl);
366 fl->fl_ops = NULL;
367 }
368
369 if (fl->fl_lmops) {
370 if (fl->fl_lmops->lm_put_owner) {
371 fl->fl_lmops->lm_put_owner(fl->fl_owner);
372 fl->fl_owner = NULL;
373 }
374 fl->fl_lmops = NULL;
375 }
376}
377EXPORT_SYMBOL_GPL(locks_release_private);
378
379/* Free a lock which is not in use. */
380void locks_free_lock(struct file_lock *fl)
381{
382 locks_release_private(fl);
383 kmem_cache_free(filelock_cache, fl);
384}
385EXPORT_SYMBOL(locks_free_lock);
386
387static void
388locks_dispose_list(struct list_head *dispose)
389{
390 struct file_lock *fl;
391
392 while (!list_empty(dispose)) {
393 fl = list_first_entry(dispose, struct file_lock, fl_list);
394 list_del_init(&fl->fl_list);
395 locks_free_lock(fl);
396 }
397}
398
399void locks_init_lock(struct file_lock *fl)
400{
401 memset(fl, 0, sizeof(struct file_lock));
402 locks_init_lock_heads(fl);
403}
404EXPORT_SYMBOL(locks_init_lock);
405
406/*
407 * Initialize a new lock from an existing file_lock structure.
408 */
409void locks_copy_conflock(struct file_lock *new, struct file_lock *fl)
410{
411 new->fl_owner = fl->fl_owner;
412 new->fl_pid = fl->fl_pid;
413 new->fl_file = NULL;
414 new->fl_flags = fl->fl_flags;
415 new->fl_type = fl->fl_type;
416 new->fl_start = fl->fl_start;
417 new->fl_end = fl->fl_end;
418 new->fl_lmops = fl->fl_lmops;
419 new->fl_ops = NULL;
420
421 if (fl->fl_lmops) {
422 if (fl->fl_lmops->lm_get_owner)
423 fl->fl_lmops->lm_get_owner(fl->fl_owner);
424 }
425}
426EXPORT_SYMBOL(locks_copy_conflock);
427
428void locks_copy_lock(struct file_lock *new, struct file_lock *fl)
429{
430 /* "new" must be a freshly-initialized lock */
431 WARN_ON_ONCE(new->fl_ops);
432
433 locks_copy_conflock(new, fl);
434
435 new->fl_file = fl->fl_file;
436 new->fl_ops = fl->fl_ops;
437
438 if (fl->fl_ops) {
439 if (fl->fl_ops->fl_copy_lock)
440 fl->fl_ops->fl_copy_lock(new, fl);
441 }
442}
443EXPORT_SYMBOL(locks_copy_lock);
444
445static void locks_move_blocks(struct file_lock *new, struct file_lock *fl)
446{
447 struct file_lock *f;
448
449 /*
450 * As ctx->flc_lock is held, new requests cannot be added to
451 * ->fl_blocked_requests, so we don't need a lock to check if it
452 * is empty.
453 */
454 if (list_empty(&fl->fl_blocked_requests))
455 return;
456 spin_lock(&blocked_lock_lock);
457 list_splice_init(&fl->fl_blocked_requests, &new->fl_blocked_requests);
458 list_for_each_entry(f, &new->fl_blocked_requests, fl_blocked_member)
459 f->fl_blocker = new;
460 spin_unlock(&blocked_lock_lock);
461}
462
463static inline int flock_translate_cmd(int cmd) {
464 if (cmd & LOCK_MAND)
465 return cmd & (LOCK_MAND | LOCK_RW);
466 switch (cmd) {
467 case LOCK_SH:
468 return F_RDLCK;
469 case LOCK_EX:
470 return F_WRLCK;
471 case LOCK_UN:
472 return F_UNLCK;
473 }
474 return -EINVAL;
475}
476
477/* Fill in a file_lock structure with an appropriate FLOCK lock. */
478static struct file_lock *
479flock_make_lock(struct file *filp, unsigned int cmd, struct file_lock *fl)
480{
481 int type = flock_translate_cmd(cmd);
482
483 if (type < 0)
484 return ERR_PTR(type);
485
486 if (fl == NULL) {
487 fl = locks_alloc_lock();
488 if (fl == NULL)
489 return ERR_PTR(-ENOMEM);
490 } else {
491 locks_init_lock(fl);
492 }
493
494 fl->fl_file = filp;
495 fl->fl_owner = filp;
496 fl->fl_pid = current->tgid;
497 fl->fl_flags = FL_FLOCK;
498 fl->fl_type = type;
499 fl->fl_end = OFFSET_MAX;
500
501 return fl;
502}
503
504static int assign_type(struct file_lock *fl, long type)
505{
506 switch (type) {
507 case F_RDLCK:
508 case F_WRLCK:
509 case F_UNLCK:
510 fl->fl_type = type;
511 break;
512 default:
513 return -EINVAL;
514 }
515 return 0;
516}
517
518static int flock64_to_posix_lock(struct file *filp, struct file_lock *fl,
519 struct flock64 *l)
520{
521 switch (l->l_whence) {
522 case SEEK_SET:
523 fl->fl_start = 0;
524 break;
525 case SEEK_CUR:
526 fl->fl_start = filp->f_pos;
527 break;
528 case SEEK_END:
529 fl->fl_start = i_size_read(file_inode(filp));
530 break;
531 default:
532 return -EINVAL;
533 }
534 if (l->l_start > OFFSET_MAX - fl->fl_start)
535 return -EOVERFLOW;
536 fl->fl_start += l->l_start;
537 if (fl->fl_start < 0)
538 return -EINVAL;
539
540 /* POSIX-1996 leaves the case l->l_len < 0 undefined;
541 POSIX-2001 defines it. */
542 if (l->l_len > 0) {
543 if (l->l_len - 1 > OFFSET_MAX - fl->fl_start)
544 return -EOVERFLOW;
545 fl->fl_end = fl->fl_start + l->l_len - 1;
546
547 } else if (l->l_len < 0) {
548 if (fl->fl_start + l->l_len < 0)
549 return -EINVAL;
550 fl->fl_end = fl->fl_start - 1;
551 fl->fl_start += l->l_len;
552 } else
553 fl->fl_end = OFFSET_MAX;
554
555 fl->fl_owner = current->files;
556 fl->fl_pid = current->tgid;
557 fl->fl_file = filp;
558 fl->fl_flags = FL_POSIX;
559 fl->fl_ops = NULL;
560 fl->fl_lmops = NULL;
561
562 return assign_type(fl, l->l_type);
563}
564
565/* Verify a "struct flock" and copy it to a "struct file_lock" as a POSIX
566 * style lock.
567 */
568static int flock_to_posix_lock(struct file *filp, struct file_lock *fl,
569 struct flock *l)
570{
571 struct flock64 ll = {
572 .l_type = l->l_type,
573 .l_whence = l->l_whence,
574 .l_start = l->l_start,
575 .l_len = l->l_len,
576 };
577
578 return flock64_to_posix_lock(filp, fl, &ll);
579}
580
581/* default lease lock manager operations */
582static bool
583lease_break_callback(struct file_lock *fl)
584{
585 kill_fasync(&fl->fl_fasync, SIGIO, POLL_MSG);
586 return false;
587}
588
589static void
590lease_setup(struct file_lock *fl, void **priv)
591{
592 struct file *filp = fl->fl_file;
593 struct fasync_struct *fa = *priv;
594
595 /*
596 * fasync_insert_entry() returns the old entry if any. If there was no
597 * old entry, then it used "priv" and inserted it into the fasync list.
598 * Clear the pointer to indicate that it shouldn't be freed.
599 */
600 if (!fasync_insert_entry(fa->fa_fd, filp, &fl->fl_fasync, fa))
601 *priv = NULL;
602
603 __f_setown(filp, task_pid(current), PIDTYPE_TGID, 0);
604}
605
606static const struct lock_manager_operations lease_manager_ops = {
607 .lm_break = lease_break_callback,
608 .lm_change = lease_modify,
609 .lm_setup = lease_setup,
610};
611
612/*
613 * Initialize a lease, use the default lock manager operations
614 */
615static int lease_init(struct file *filp, long type, struct file_lock *fl)
616{
617 if (assign_type(fl, type) != 0)
618 return -EINVAL;
619
620 fl->fl_owner = filp;
621 fl->fl_pid = current->tgid;
622
623 fl->fl_file = filp;
624 fl->fl_flags = FL_LEASE;
625 fl->fl_start = 0;
626 fl->fl_end = OFFSET_MAX;
627 fl->fl_ops = NULL;
628 fl->fl_lmops = &lease_manager_ops;
629 return 0;
630}
631
632/* Allocate a file_lock initialised to this type of lease */
633static struct file_lock *lease_alloc(struct file *filp, long type)
634{
635 struct file_lock *fl = locks_alloc_lock();
636 int error = -ENOMEM;
637
638 if (fl == NULL)
639 return ERR_PTR(error);
640
641 error = lease_init(filp, type, fl);
642 if (error) {
643 locks_free_lock(fl);
644 return ERR_PTR(error);
645 }
646 return fl;
647}
648
649/* Check if two locks overlap each other.
650 */
651static inline int locks_overlap(struct file_lock *fl1, struct file_lock *fl2)
652{
653 return ((fl1->fl_end >= fl2->fl_start) &&
654 (fl2->fl_end >= fl1->fl_start));
655}
656
657/*
658 * Check whether two locks have the same owner.
659 */
660static int posix_same_owner(struct file_lock *fl1, struct file_lock *fl2)
661{
662 return fl1->fl_owner == fl2->fl_owner;
663}
664
665/* Must be called with the flc_lock held! */
666static void locks_insert_global_locks(struct file_lock *fl)
667{
668 struct file_lock_list_struct *fll = this_cpu_ptr(&file_lock_list);
669
670 percpu_rwsem_assert_held(&file_rwsem);
671
672 spin_lock(&fll->lock);
673 fl->fl_link_cpu = smp_processor_id();
674 hlist_add_head(&fl->fl_link, &fll->hlist);
675 spin_unlock(&fll->lock);
676}
677
678/* Must be called with the flc_lock held! */
679static void locks_delete_global_locks(struct file_lock *fl)
680{
681 struct file_lock_list_struct *fll;
682
683 percpu_rwsem_assert_held(&file_rwsem);
684
685 /*
686 * Avoid taking lock if already unhashed. This is safe since this check
687 * is done while holding the flc_lock, and new insertions into the list
688 * also require that it be held.
689 */
690 if (hlist_unhashed(&fl->fl_link))
691 return;
692
693 fll = per_cpu_ptr(&file_lock_list, fl->fl_link_cpu);
694 spin_lock(&fll->lock);
695 hlist_del_init(&fl->fl_link);
696 spin_unlock(&fll->lock);
697}
698
699static unsigned long
700posix_owner_key(struct file_lock *fl)
701{
702 return (unsigned long)fl->fl_owner;
703}
704
705static void locks_insert_global_blocked(struct file_lock *waiter)
706{
707 lockdep_assert_held(&blocked_lock_lock);
708
709 hash_add(blocked_hash, &waiter->fl_link, posix_owner_key(waiter));
710}
711
712static void locks_delete_global_blocked(struct file_lock *waiter)
713{
714 lockdep_assert_held(&blocked_lock_lock);
715
716 hash_del(&waiter->fl_link);
717}
718
719/* Remove waiter from blocker's block list.
720 * When blocker ends up pointing to itself then the list is empty.
721 *
722 * Must be called with blocked_lock_lock held.
723 */
724static void __locks_delete_block(struct file_lock *waiter)
725{
726 locks_delete_global_blocked(waiter);
727 list_del_init(&waiter->fl_blocked_member);
728 waiter->fl_blocker = NULL;
729}
730
731static void __locks_wake_up_blocks(struct file_lock *blocker)
732{
733 while (!list_empty(&blocker->fl_blocked_requests)) {
734 struct file_lock *waiter;
735
736 waiter = list_first_entry(&blocker->fl_blocked_requests,
737 struct file_lock, fl_blocked_member);
738 __locks_delete_block(waiter);
739 if (waiter->fl_lmops && waiter->fl_lmops->lm_notify)
740 waiter->fl_lmops->lm_notify(waiter);
741 else
742 wake_up(&waiter->fl_wait);
743 }
744}
745
746/**
747 * locks_delete_lock - stop waiting for a file lock
748 * @waiter: the lock which was waiting
749 *
750 * lockd/nfsd need to disconnect the lock while working on it.
751 */
752int locks_delete_block(struct file_lock *waiter)
753{
754 int status = -ENOENT;
755
756 /*
757 * If fl_blocker is NULL, it won't be set again as this thread
758 * "owns" the lock and is the only one that might try to claim
759 * the lock. So it is safe to test fl_blocker locklessly.
760 * Also if fl_blocker is NULL, this waiter is not listed on
761 * fl_blocked_requests for some lock, so no other request can
762 * be added to the list of fl_blocked_requests for this
763 * request. So if fl_blocker is NULL, it is safe to
764 * locklessly check if fl_blocked_requests is empty. If both
765 * of these checks succeed, there is no need to take the lock.
766 */
767 if (waiter->fl_blocker == NULL &&
768 list_empty(&waiter->fl_blocked_requests))
769 return status;
770 spin_lock(&blocked_lock_lock);
771 if (waiter->fl_blocker)
772 status = 0;
773 __locks_wake_up_blocks(waiter);
774 __locks_delete_block(waiter);
775 spin_unlock(&blocked_lock_lock);
776 return status;
777}
778EXPORT_SYMBOL(locks_delete_block);
779
780/* Insert waiter into blocker's block list.
781 * We use a circular list so that processes can be easily woken up in
782 * the order they blocked. The documentation doesn't require this but
783 * it seems like the reasonable thing to do.
784 *
785 * Must be called with both the flc_lock and blocked_lock_lock held. The
786 * fl_blocked_requests list itself is protected by the blocked_lock_lock,
787 * but by ensuring that the flc_lock is also held on insertions we can avoid
788 * taking the blocked_lock_lock in some cases when we see that the
789 * fl_blocked_requests list is empty.
790 *
791 * Rather than just adding to the list, we check for conflicts with any existing
792 * waiters, and add beneath any waiter that blocks the new waiter.
793 * Thus wakeups don't happen until needed.
794 */
795static void __locks_insert_block(struct file_lock *blocker,
796 struct file_lock *waiter,
797 bool conflict(struct file_lock *,
798 struct file_lock *))
799{
800 struct file_lock *fl;
801 BUG_ON(!list_empty(&waiter->fl_blocked_member));
802
803new_blocker:
804 list_for_each_entry(fl, &blocker->fl_blocked_requests, fl_blocked_member)
805 if (conflict(fl, waiter)) {
806 blocker = fl;
807 goto new_blocker;
808 }
809 waiter->fl_blocker = blocker;
810 list_add_tail(&waiter->fl_blocked_member, &blocker->fl_blocked_requests);
811 if (IS_POSIX(blocker) && !IS_OFDLCK(blocker))
812 locks_insert_global_blocked(waiter);
813
814 /* The requests in waiter->fl_blocked are known to conflict with
815 * waiter, but might not conflict with blocker, or the requests
816 * and lock which block it. So they all need to be woken.
817 */
818 __locks_wake_up_blocks(waiter);
819}
820
821/* Must be called with flc_lock held. */
822static void locks_insert_block(struct file_lock *blocker,
823 struct file_lock *waiter,
824 bool conflict(struct file_lock *,
825 struct file_lock *))
826{
827 spin_lock(&blocked_lock_lock);
828 __locks_insert_block(blocker, waiter, conflict);
829 spin_unlock(&blocked_lock_lock);
830}
831
832/*
833 * Wake up processes blocked waiting for blocker.
834 *
835 * Must be called with the inode->flc_lock held!
836 */
837static void locks_wake_up_blocks(struct file_lock *blocker)
838{
839 /*
840 * Avoid taking global lock if list is empty. This is safe since new
841 * blocked requests are only added to the list under the flc_lock, and
842 * the flc_lock is always held here. Note that removal from the
843 * fl_blocked_requests list does not require the flc_lock, so we must
844 * recheck list_empty() after acquiring the blocked_lock_lock.
845 */
846 if (list_empty(&blocker->fl_blocked_requests))
847 return;
848
849 spin_lock(&blocked_lock_lock);
850 __locks_wake_up_blocks(blocker);
851 spin_unlock(&blocked_lock_lock);
852}
853
854static void
855locks_insert_lock_ctx(struct file_lock *fl, struct list_head *before)
856{
857 list_add_tail(&fl->fl_list, before);
858 locks_insert_global_locks(fl);
859}
860
861static void
862locks_unlink_lock_ctx(struct file_lock *fl)
863{
864 locks_delete_global_locks(fl);
865 list_del_init(&fl->fl_list);
866 locks_wake_up_blocks(fl);
867}
868
869static void
870locks_delete_lock_ctx(struct file_lock *fl, struct list_head *dispose)
871{
872 locks_unlink_lock_ctx(fl);
873 if (dispose)
874 list_add(&fl->fl_list, dispose);
875 else
876 locks_free_lock(fl);
877}
878
879/* Determine if lock sys_fl blocks lock caller_fl. Common functionality
880 * checks for shared/exclusive status of overlapping locks.
881 */
882static bool locks_conflict(struct file_lock *caller_fl,
883 struct file_lock *sys_fl)
884{
885 if (sys_fl->fl_type == F_WRLCK)
886 return true;
887 if (caller_fl->fl_type == F_WRLCK)
888 return true;
889 return false;
890}
891
892/* Determine if lock sys_fl blocks lock caller_fl. POSIX specific
893 * checking before calling the locks_conflict().
894 */
895static bool posix_locks_conflict(struct file_lock *caller_fl,
896 struct file_lock *sys_fl)
897{
898 /* POSIX locks owned by the same process do not conflict with
899 * each other.
900 */
901 if (posix_same_owner(caller_fl, sys_fl))
902 return false;
903
904 /* Check whether they overlap */
905 if (!locks_overlap(caller_fl, sys_fl))
906 return false;
907
908 return locks_conflict(caller_fl, sys_fl);
909}
910
911/* Determine if lock sys_fl blocks lock caller_fl. FLOCK specific
912 * checking before calling the locks_conflict().
913 */
914static bool flock_locks_conflict(struct file_lock *caller_fl,
915 struct file_lock *sys_fl)
916{
917 /* FLOCK locks referring to the same filp do not conflict with
918 * each other.
919 */
920 if (caller_fl->fl_file == sys_fl->fl_file)
921 return false;
922 if ((caller_fl->fl_type & LOCK_MAND) || (sys_fl->fl_type & LOCK_MAND))
923 return false;
924
925 return locks_conflict(caller_fl, sys_fl);
926}
927
928void
929posix_test_lock(struct file *filp, struct file_lock *fl)
930{
931 struct file_lock *cfl;
932 struct file_lock_context *ctx;
933 struct inode *inode = locks_inode(filp);
934
935 ctx = smp_load_acquire(&inode->i_flctx);
936 if (!ctx || list_empty_careful(&ctx->flc_posix)) {
937 fl->fl_type = F_UNLCK;
938 return;
939 }
940
941 spin_lock(&ctx->flc_lock);
942 list_for_each_entry(cfl, &ctx->flc_posix, fl_list) {
943 if (posix_locks_conflict(fl, cfl)) {
944 locks_copy_conflock(fl, cfl);
945 goto out;
946 }
947 }
948 fl->fl_type = F_UNLCK;
949out:
950 spin_unlock(&ctx->flc_lock);
951 return;
952}
953EXPORT_SYMBOL(posix_test_lock);
954
955/*
956 * Deadlock detection:
957 *
958 * We attempt to detect deadlocks that are due purely to posix file
959 * locks.
960 *
961 * We assume that a task can be waiting for at most one lock at a time.
962 * So for any acquired lock, the process holding that lock may be
963 * waiting on at most one other lock. That lock in turns may be held by
964 * someone waiting for at most one other lock. Given a requested lock
965 * caller_fl which is about to wait for a conflicting lock block_fl, we
966 * follow this chain of waiters to ensure we are not about to create a
967 * cycle.
968 *
969 * Since we do this before we ever put a process to sleep on a lock, we
970 * are ensured that there is never a cycle; that is what guarantees that
971 * the while() loop in posix_locks_deadlock() eventually completes.
972 *
973 * Note: the above assumption may not be true when handling lock
974 * requests from a broken NFS client. It may also fail in the presence
975 * of tasks (such as posix threads) sharing the same open file table.
976 * To handle those cases, we just bail out after a few iterations.
977 *
978 * For FL_OFDLCK locks, the owner is the filp, not the files_struct.
979 * Because the owner is not even nominally tied to a thread of
980 * execution, the deadlock detection below can't reasonably work well. Just
981 * skip it for those.
982 *
983 * In principle, we could do a more limited deadlock detection on FL_OFDLCK
984 * locks that just checks for the case where two tasks are attempting to
985 * upgrade from read to write locks on the same inode.
986 */
987
988#define MAX_DEADLK_ITERATIONS 10
989
990/* Find a lock that the owner of the given block_fl is blocking on. */
991static struct file_lock *what_owner_is_waiting_for(struct file_lock *block_fl)
992{
993 struct file_lock *fl;
994
995 hash_for_each_possible(blocked_hash, fl, fl_link, posix_owner_key(block_fl)) {
996 if (posix_same_owner(fl, block_fl)) {
997 while (fl->fl_blocker)
998 fl = fl->fl_blocker;
999 return fl;
1000 }
1001 }
1002 return NULL;
1003}
1004
1005/* Must be called with the blocked_lock_lock held! */
1006static int posix_locks_deadlock(struct file_lock *caller_fl,
1007 struct file_lock *block_fl)
1008{
1009 int i = 0;
1010
1011 lockdep_assert_held(&blocked_lock_lock);
1012
1013 /*
1014 * This deadlock detector can't reasonably detect deadlocks with
1015 * FL_OFDLCK locks, since they aren't owned by a process, per-se.
1016 */
1017 if (IS_OFDLCK(caller_fl))
1018 return 0;
1019
1020 while ((block_fl = what_owner_is_waiting_for(block_fl))) {
1021 if (i++ > MAX_DEADLK_ITERATIONS)
1022 return 0;
1023 if (posix_same_owner(caller_fl, block_fl))
1024 return 1;
1025 }
1026 return 0;
1027}
1028
1029/* Try to create a FLOCK lock on filp. We always insert new FLOCK locks
1030 * after any leases, but before any posix locks.
1031 *
1032 * Note that if called with an FL_EXISTS argument, the caller may determine
1033 * whether or not a lock was successfully freed by testing the return
1034 * value for -ENOENT.
1035 */
1036static int flock_lock_inode(struct inode *inode, struct file_lock *request)
1037{
1038 struct file_lock *new_fl = NULL;
1039 struct file_lock *fl;
1040 struct file_lock_context *ctx;
1041 int error = 0;
1042 bool found = false;
1043 LIST_HEAD(dispose);
1044
1045 ctx = locks_get_lock_context(inode, request->fl_type);
1046 if (!ctx) {
1047 if (request->fl_type != F_UNLCK)
1048 return -ENOMEM;
1049 return (request->fl_flags & FL_EXISTS) ? -ENOENT : 0;
1050 }
1051
1052 if (!(request->fl_flags & FL_ACCESS) && (request->fl_type != F_UNLCK)) {
1053 new_fl = locks_alloc_lock();
1054 if (!new_fl)
1055 return -ENOMEM;
1056 }
1057
1058 percpu_down_read(&file_rwsem);
1059 spin_lock(&ctx->flc_lock);
1060 if (request->fl_flags & FL_ACCESS)
1061 goto find_conflict;
1062
1063 list_for_each_entry(fl, &ctx->flc_flock, fl_list) {
1064 if (request->fl_file != fl->fl_file)
1065 continue;
1066 if (request->fl_type == fl->fl_type)
1067 goto out;
1068 found = true;
1069 locks_delete_lock_ctx(fl, &dispose);
1070 break;
1071 }
1072
1073 if (request->fl_type == F_UNLCK) {
1074 if ((request->fl_flags & FL_EXISTS) && !found)
1075 error = -ENOENT;
1076 goto out;
1077 }
1078
1079find_conflict:
1080 list_for_each_entry(fl, &ctx->flc_flock, fl_list) {
1081 if (!flock_locks_conflict(request, fl))
1082 continue;
1083 error = -EAGAIN;
1084 if (!(request->fl_flags & FL_SLEEP))
1085 goto out;
1086 error = FILE_LOCK_DEFERRED;
1087 locks_insert_block(fl, request, flock_locks_conflict);
1088 goto out;
1089 }
1090 if (request->fl_flags & FL_ACCESS)
1091 goto out;
1092 locks_copy_lock(new_fl, request);
1093 locks_move_blocks(new_fl, request);
1094 locks_insert_lock_ctx(new_fl, &ctx->flc_flock);
1095 new_fl = NULL;
1096 error = 0;
1097
1098out:
1099 spin_unlock(&ctx->flc_lock);
1100 percpu_up_read(&file_rwsem);
1101 if (new_fl)
1102 locks_free_lock(new_fl);
1103 locks_dispose_list(&dispose);
1104 trace_flock_lock_inode(inode, request, error);
1105 return error;
1106}
1107
1108static int posix_lock_inode(struct inode *inode, struct file_lock *request,
1109 struct file_lock *conflock)
1110{
1111 struct file_lock *fl, *tmp;
1112 struct file_lock *new_fl = NULL;
1113 struct file_lock *new_fl2 = NULL;
1114 struct file_lock *left = NULL;
1115 struct file_lock *right = NULL;
1116 struct file_lock_context *ctx;
1117 int error;
1118 bool added = false;
1119 LIST_HEAD(dispose);
1120
1121 ctx = locks_get_lock_context(inode, request->fl_type);
1122 if (!ctx)
1123 return (request->fl_type == F_UNLCK) ? 0 : -ENOMEM;
1124
1125 /*
1126 * We may need two file_lock structures for this operation,
1127 * so we get them in advance to avoid races.
1128 *
1129 * In some cases we can be sure, that no new locks will be needed
1130 */
1131 if (!(request->fl_flags & FL_ACCESS) &&
1132 (request->fl_type != F_UNLCK ||
1133 request->fl_start != 0 || request->fl_end != OFFSET_MAX)) {
1134 new_fl = locks_alloc_lock();
1135 new_fl2 = locks_alloc_lock();
1136 }
1137
1138 percpu_down_read(&file_rwsem);
1139 spin_lock(&ctx->flc_lock);
1140 /*
1141 * New lock request. Walk all POSIX locks and look for conflicts. If
1142 * there are any, either return error or put the request on the
1143 * blocker's list of waiters and the global blocked_hash.
1144 */
1145 if (request->fl_type != F_UNLCK) {
1146 list_for_each_entry(fl, &ctx->flc_posix, fl_list) {
1147 if (!posix_locks_conflict(request, fl))
1148 continue;
1149 if (conflock)
1150 locks_copy_conflock(conflock, fl);
1151 error = -EAGAIN;
1152 if (!(request->fl_flags & FL_SLEEP))
1153 goto out;
1154 /*
1155 * Deadlock detection and insertion into the blocked
1156 * locks list must be done while holding the same lock!
1157 */
1158 error = -EDEADLK;
1159 spin_lock(&blocked_lock_lock);
1160 /*
1161 * Ensure that we don't find any locks blocked on this
1162 * request during deadlock detection.
1163 */
1164 __locks_wake_up_blocks(request);
1165 if (likely(!posix_locks_deadlock(request, fl))) {
1166 error = FILE_LOCK_DEFERRED;
1167 __locks_insert_block(fl, request,
1168 posix_locks_conflict);
1169 }
1170 spin_unlock(&blocked_lock_lock);
1171 goto out;
1172 }
1173 }
1174
1175 /* If we're just looking for a conflict, we're done. */
1176 error = 0;
1177 if (request->fl_flags & FL_ACCESS)
1178 goto out;
1179
1180 /* Find the first old lock with the same owner as the new lock */
1181 list_for_each_entry(fl, &ctx->flc_posix, fl_list) {
1182 if (posix_same_owner(request, fl))
1183 break;
1184 }
1185
1186 /* Process locks with this owner. */
1187 list_for_each_entry_safe_from(fl, tmp, &ctx->flc_posix, fl_list) {
1188 if (!posix_same_owner(request, fl))
1189 break;
1190
1191 /* Detect adjacent or overlapping regions (if same lock type) */
1192 if (request->fl_type == fl->fl_type) {
1193 /* In all comparisons of start vs end, use
1194 * "start - 1" rather than "end + 1". If end
1195 * is OFFSET_MAX, end + 1 will become negative.
1196 */
1197 if (fl->fl_end < request->fl_start - 1)
1198 continue;
1199 /* If the next lock in the list has entirely bigger
1200 * addresses than the new one, insert the lock here.
1201 */
1202 if (fl->fl_start - 1 > request->fl_end)
1203 break;
1204
1205 /* If we come here, the new and old lock are of the
1206 * same type and adjacent or overlapping. Make one
1207 * lock yielding from the lower start address of both
1208 * locks to the higher end address.
1209 */
1210 if (fl->fl_start > request->fl_start)
1211 fl->fl_start = request->fl_start;
1212 else
1213 request->fl_start = fl->fl_start;
1214 if (fl->fl_end < request->fl_end)
1215 fl->fl_end = request->fl_end;
1216 else
1217 request->fl_end = fl->fl_end;
1218 if (added) {
1219 locks_delete_lock_ctx(fl, &dispose);
1220 continue;
1221 }
1222 request = fl;
1223 added = true;
1224 } else {
1225 /* Processing for different lock types is a bit
1226 * more complex.
1227 */
1228 if (fl->fl_end < request->fl_start)
1229 continue;
1230 if (fl->fl_start > request->fl_end)
1231 break;
1232 if (request->fl_type == F_UNLCK)
1233 added = true;
1234 if (fl->fl_start < request->fl_start)
1235 left = fl;
1236 /* If the next lock in the list has a higher end
1237 * address than the new one, insert the new one here.
1238 */
1239 if (fl->fl_end > request->fl_end) {
1240 right = fl;
1241 break;
1242 }
1243 if (fl->fl_start >= request->fl_start) {
1244 /* The new lock completely replaces an old
1245 * one (This may happen several times).
1246 */
1247 if (added) {
1248 locks_delete_lock_ctx(fl, &dispose);
1249 continue;
1250 }
1251 /*
1252 * Replace the old lock with new_fl, and
1253 * remove the old one. It's safe to do the
1254 * insert here since we know that we won't be
1255 * using new_fl later, and that the lock is
1256 * just replacing an existing lock.
1257 */
1258 error = -ENOLCK;
1259 if (!new_fl)
1260 goto out;
1261 locks_copy_lock(new_fl, request);
1262 request = new_fl;
1263 new_fl = NULL;
1264 locks_insert_lock_ctx(request, &fl->fl_list);
1265 locks_delete_lock_ctx(fl, &dispose);
1266 added = true;
1267 }
1268 }
1269 }
1270
1271 /*
1272 * The above code only modifies existing locks in case of merging or
1273 * replacing. If new lock(s) need to be inserted all modifications are
1274 * done below this, so it's safe yet to bail out.
1275 */
1276 error = -ENOLCK; /* "no luck" */
1277 if (right && left == right && !new_fl2)
1278 goto out;
1279
1280 error = 0;
1281 if (!added) {
1282 if (request->fl_type == F_UNLCK) {
1283 if (request->fl_flags & FL_EXISTS)
1284 error = -ENOENT;
1285 goto out;
1286 }
1287
1288 if (!new_fl) {
1289 error = -ENOLCK;
1290 goto out;
1291 }
1292 locks_copy_lock(new_fl, request);
1293 locks_move_blocks(new_fl, request);
1294 locks_insert_lock_ctx(new_fl, &fl->fl_list);
1295 fl = new_fl;
1296 new_fl = NULL;
1297 }
1298 if (right) {
1299 if (left == right) {
1300 /* The new lock breaks the old one in two pieces,
1301 * so we have to use the second new lock.
1302 */
1303 left = new_fl2;
1304 new_fl2 = NULL;
1305 locks_copy_lock(left, right);
1306 locks_insert_lock_ctx(left, &fl->fl_list);
1307 }
1308 right->fl_start = request->fl_end + 1;
1309 locks_wake_up_blocks(right);
1310 }
1311 if (left) {
1312 left->fl_end = request->fl_start - 1;
1313 locks_wake_up_blocks(left);
1314 }
1315 out:
1316 spin_unlock(&ctx->flc_lock);
1317 percpu_up_read(&file_rwsem);
1318 /*
1319 * Free any unused locks.
1320 */
1321 if (new_fl)
1322 locks_free_lock(new_fl);
1323 if (new_fl2)
1324 locks_free_lock(new_fl2);
1325 locks_dispose_list(&dispose);
1326 trace_posix_lock_inode(inode, request, error);
1327
1328 return error;
1329}
1330
1331/**
1332 * posix_lock_file - Apply a POSIX-style lock to a file
1333 * @filp: The file to apply the lock to
1334 * @fl: The lock to be applied
1335 * @conflock: Place to return a copy of the conflicting lock, if found.
1336 *
1337 * Add a POSIX style lock to a file.
1338 * We merge adjacent & overlapping locks whenever possible.
1339 * POSIX locks are sorted by owner task, then by starting address
1340 *
1341 * Note that if called with an FL_EXISTS argument, the caller may determine
1342 * whether or not a lock was successfully freed by testing the return
1343 * value for -ENOENT.
1344 */
1345int posix_lock_file(struct file *filp, struct file_lock *fl,
1346 struct file_lock *conflock)
1347{
1348 return posix_lock_inode(locks_inode(filp), fl, conflock);
1349}
1350EXPORT_SYMBOL(posix_lock_file);
1351
1352/**
1353 * posix_lock_inode_wait - Apply a POSIX-style lock to a file
1354 * @inode: inode of file to which lock request should be applied
1355 * @fl: The lock to be applied
1356 *
1357 * Apply a POSIX style lock request to an inode.
1358 */
1359static int posix_lock_inode_wait(struct inode *inode, struct file_lock *fl)
1360{
1361 int error;
1362 might_sleep ();
1363 for (;;) {
1364 error = posix_lock_inode(inode, fl, NULL);
1365 if (error != FILE_LOCK_DEFERRED)
1366 break;
1367 error = wait_event_interruptible(fl->fl_wait, !fl->fl_blocker);
1368 if (error)
1369 break;
1370 }
1371 locks_delete_block(fl);
1372 return error;
1373}
1374
1375#ifdef CONFIG_MANDATORY_FILE_LOCKING
1376/**
1377 * locks_mandatory_locked - Check for an active lock
1378 * @file: the file to check
1379 *
1380 * Searches the inode's list of locks to find any POSIX locks which conflict.
1381 * This function is called from locks_verify_locked() only.
1382 */
1383int locks_mandatory_locked(struct file *file)
1384{
1385 int ret;
1386 struct inode *inode = locks_inode(file);
1387 struct file_lock_context *ctx;
1388 struct file_lock *fl;
1389
1390 ctx = smp_load_acquire(&inode->i_flctx);
1391 if (!ctx || list_empty_careful(&ctx->flc_posix))
1392 return 0;
1393
1394 /*
1395 * Search the lock list for this inode for any POSIX locks.
1396 */
1397 spin_lock(&ctx->flc_lock);
1398 ret = 0;
1399 list_for_each_entry(fl, &ctx->flc_posix, fl_list) {
1400 if (fl->fl_owner != current->files &&
1401 fl->fl_owner != file) {
1402 ret = -EAGAIN;
1403 break;
1404 }
1405 }
1406 spin_unlock(&ctx->flc_lock);
1407 return ret;
1408}
1409
1410/**
1411 * locks_mandatory_area - Check for a conflicting lock
1412 * @inode: the file to check
1413 * @filp: how the file was opened (if it was)
1414 * @start: first byte in the file to check
1415 * @end: lastbyte in the file to check
1416 * @type: %F_WRLCK for a write lock, else %F_RDLCK
1417 *
1418 * Searches the inode's list of locks to find any POSIX locks which conflict.
1419 */
1420int locks_mandatory_area(struct inode *inode, struct file *filp, loff_t start,
1421 loff_t end, unsigned char type)
1422{
1423 struct file_lock fl;
1424 int error;
1425 bool sleep = false;
1426
1427 locks_init_lock(&fl);
1428 fl.fl_pid = current->tgid;
1429 fl.fl_file = filp;
1430 fl.fl_flags = FL_POSIX | FL_ACCESS;
1431 if (filp && !(filp->f_flags & O_NONBLOCK))
1432 sleep = true;
1433 fl.fl_type = type;
1434 fl.fl_start = start;
1435 fl.fl_end = end;
1436
1437 for (;;) {
1438 if (filp) {
1439 fl.fl_owner = filp;
1440 fl.fl_flags &= ~FL_SLEEP;
1441 error = posix_lock_inode(inode, &fl, NULL);
1442 if (!error)
1443 break;
1444 }
1445
1446 if (sleep)
1447 fl.fl_flags |= FL_SLEEP;
1448 fl.fl_owner = current->files;
1449 error = posix_lock_inode(inode, &fl, NULL);
1450 if (error != FILE_LOCK_DEFERRED)
1451 break;
1452 error = wait_event_interruptible(fl.fl_wait, !fl.fl_blocker);
1453 if (!error) {
1454 /*
1455 * If we've been sleeping someone might have
1456 * changed the permissions behind our back.
1457 */
1458 if (__mandatory_lock(inode))
1459 continue;
1460 }
1461
1462 break;
1463 }
1464 locks_delete_block(&fl);
1465
1466 return error;
1467}
1468EXPORT_SYMBOL(locks_mandatory_area);
1469#endif /* CONFIG_MANDATORY_FILE_LOCKING */
1470
1471static void lease_clear_pending(struct file_lock *fl, int arg)
1472{
1473 switch (arg) {
1474 case F_UNLCK:
1475 fl->fl_flags &= ~FL_UNLOCK_PENDING;
1476 /* fall through */
1477 case F_RDLCK:
1478 fl->fl_flags &= ~FL_DOWNGRADE_PENDING;
1479 }
1480}
1481
1482/* We already had a lease on this file; just change its type */
1483int lease_modify(struct file_lock *fl, int arg, struct list_head *dispose)
1484{
1485 int error = assign_type(fl, arg);
1486
1487 if (error)
1488 return error;
1489 lease_clear_pending(fl, arg);
1490 locks_wake_up_blocks(fl);
1491 if (arg == F_UNLCK) {
1492 struct file *filp = fl->fl_file;
1493
1494 f_delown(filp);
1495 filp->f_owner.signum = 0;
1496 fasync_helper(0, fl->fl_file, 0, &fl->fl_fasync);
1497 if (fl->fl_fasync != NULL) {
1498 printk(KERN_ERR "locks_delete_lock: fasync == %p\n", fl->fl_fasync);
1499 fl->fl_fasync = NULL;
1500 }
1501 locks_delete_lock_ctx(fl, dispose);
1502 }
1503 return 0;
1504}
1505EXPORT_SYMBOL(lease_modify);
1506
1507static bool past_time(unsigned long then)
1508{
1509 if (!then)
1510 /* 0 is a special value meaning "this never expires": */
1511 return false;
1512 return time_after(jiffies, then);
1513}
1514
1515static void time_out_leases(struct inode *inode, struct list_head *dispose)
1516{
1517 struct file_lock_context *ctx = inode->i_flctx;
1518 struct file_lock *fl, *tmp;
1519
1520 lockdep_assert_held(&ctx->flc_lock);
1521
1522 list_for_each_entry_safe(fl, tmp, &ctx->flc_lease, fl_list) {
1523 trace_time_out_leases(inode, fl);
1524 if (past_time(fl->fl_downgrade_time))
1525 lease_modify(fl, F_RDLCK, dispose);
1526 if (past_time(fl->fl_break_time))
1527 lease_modify(fl, F_UNLCK, dispose);
1528 }
1529}
1530
1531static bool leases_conflict(struct file_lock *lease, struct file_lock *breaker)
1532{
1533 bool rc;
1534
1535 if ((breaker->fl_flags & FL_LAYOUT) != (lease->fl_flags & FL_LAYOUT)) {
1536 rc = false;
1537 goto trace;
1538 }
1539 if ((breaker->fl_flags & FL_DELEG) && (lease->fl_flags & FL_LEASE)) {
1540 rc = false;
1541 goto trace;
1542 }
1543
1544 rc = locks_conflict(breaker, lease);
1545trace:
1546 trace_leases_conflict(rc, lease, breaker);
1547 return rc;
1548}
1549
1550static bool
1551any_leases_conflict(struct inode *inode, struct file_lock *breaker)
1552{
1553 struct file_lock_context *ctx = inode->i_flctx;
1554 struct file_lock *fl;
1555
1556 lockdep_assert_held(&ctx->flc_lock);
1557
1558 list_for_each_entry(fl, &ctx->flc_lease, fl_list) {
1559 if (leases_conflict(fl, breaker))
1560 return true;
1561 }
1562 return false;
1563}
1564
1565/**
1566 * __break_lease - revoke all outstanding leases on file
1567 * @inode: the inode of the file to return
1568 * @mode: O_RDONLY: break only write leases; O_WRONLY or O_RDWR:
1569 * break all leases
1570 * @type: FL_LEASE: break leases and delegations; FL_DELEG: break
1571 * only delegations
1572 *
1573 * break_lease (inlined for speed) has checked there already is at least
1574 * some kind of lock (maybe a lease) on this file. Leases are broken on
1575 * a call to open() or truncate(). This function can sleep unless you
1576 * specified %O_NONBLOCK to your open().
1577 */
1578int __break_lease(struct inode *inode, unsigned int mode, unsigned int type)
1579{
1580 int error = 0;
1581 struct file_lock_context *ctx;
1582 struct file_lock *new_fl, *fl, *tmp;
1583 unsigned long break_time;
1584 int want_write = (mode & O_ACCMODE) != O_RDONLY;
1585 LIST_HEAD(dispose);
1586
1587 new_fl = lease_alloc(NULL, want_write ? F_WRLCK : F_RDLCK);
1588 if (IS_ERR(new_fl))
1589 return PTR_ERR(new_fl);
1590 new_fl->fl_flags = type;
1591
1592 /* typically we will check that ctx is non-NULL before calling */
1593 ctx = smp_load_acquire(&inode->i_flctx);
1594 if (!ctx) {
1595 WARN_ON_ONCE(1);
1596 goto free_lock;
1597 }
1598
1599 percpu_down_read(&file_rwsem);
1600 spin_lock(&ctx->flc_lock);
1601
1602 time_out_leases(inode, &dispose);
1603
1604 if (!any_leases_conflict(inode, new_fl))
1605 goto out;
1606
1607 break_time = 0;
1608 if (lease_break_time > 0) {
1609 break_time = jiffies + lease_break_time * HZ;
1610 if (break_time == 0)
1611 break_time++; /* so that 0 means no break time */
1612 }
1613
1614 list_for_each_entry_safe(fl, tmp, &ctx->flc_lease, fl_list) {
1615 if (!leases_conflict(fl, new_fl))
1616 continue;
1617 if (want_write) {
1618 if (fl->fl_flags & FL_UNLOCK_PENDING)
1619 continue;
1620 fl->fl_flags |= FL_UNLOCK_PENDING;
1621 fl->fl_break_time = break_time;
1622 } else {
1623 if (lease_breaking(fl))
1624 continue;
1625 fl->fl_flags |= FL_DOWNGRADE_PENDING;
1626 fl->fl_downgrade_time = break_time;
1627 }
1628 if (fl->fl_lmops->lm_break(fl))
1629 locks_delete_lock_ctx(fl, &dispose);
1630 }
1631
1632 if (list_empty(&ctx->flc_lease))
1633 goto out;
1634
1635 if (mode & O_NONBLOCK) {
1636 trace_break_lease_noblock(inode, new_fl);
1637 error = -EWOULDBLOCK;
1638 goto out;
1639 }
1640
1641restart:
1642 fl = list_first_entry(&ctx->flc_lease, struct file_lock, fl_list);
1643 break_time = fl->fl_break_time;
1644 if (break_time != 0)
1645 break_time -= jiffies;
1646 if (break_time == 0)
1647 break_time++;
1648 locks_insert_block(fl, new_fl, leases_conflict);
1649 trace_break_lease_block(inode, new_fl);
1650 spin_unlock(&ctx->flc_lock);
1651 percpu_up_read(&file_rwsem);
1652
1653 locks_dispose_list(&dispose);
1654 error = wait_event_interruptible_timeout(new_fl->fl_wait,
1655 !new_fl->fl_blocker, break_time);
1656
1657 percpu_down_read(&file_rwsem);
1658 spin_lock(&ctx->flc_lock);
1659 trace_break_lease_unblock(inode, new_fl);
1660 locks_delete_block(new_fl);
1661 if (error >= 0) {
1662 /*
1663 * Wait for the next conflicting lease that has not been
1664 * broken yet
1665 */
1666 if (error == 0)
1667 time_out_leases(inode, &dispose);
1668 if (any_leases_conflict(inode, new_fl))
1669 goto restart;
1670 error = 0;
1671 }
1672out:
1673 spin_unlock(&ctx->flc_lock);
1674 percpu_up_read(&file_rwsem);
1675 locks_dispose_list(&dispose);
1676free_lock:
1677 locks_free_lock(new_fl);
1678 return error;
1679}
1680EXPORT_SYMBOL(__break_lease);
1681
1682/**
1683 * lease_get_mtime - update modified time of an inode with exclusive lease
1684 * @inode: the inode
1685 * @time: pointer to a timespec which contains the last modified time
1686 *
1687 * This is to force NFS clients to flush their caches for files with
1688 * exclusive leases. The justification is that if someone has an
1689 * exclusive lease, then they could be modifying it.
1690 */
1691void lease_get_mtime(struct inode *inode, struct timespec64 *time)
1692{
1693 bool has_lease = false;
1694 struct file_lock_context *ctx;
1695 struct file_lock *fl;
1696
1697 ctx = smp_load_acquire(&inode->i_flctx);
1698 if (ctx && !list_empty_careful(&ctx->flc_lease)) {
1699 spin_lock(&ctx->flc_lock);
1700 fl = list_first_entry_or_null(&ctx->flc_lease,
1701 struct file_lock, fl_list);
1702 if (fl && (fl->fl_type == F_WRLCK))
1703 has_lease = true;
1704 spin_unlock(&ctx->flc_lock);
1705 }
1706
1707 if (has_lease)
1708 *time = current_time(inode);
1709}
1710EXPORT_SYMBOL(lease_get_mtime);
1711
1712/**
1713 * fcntl_getlease - Enquire what lease is currently active
1714 * @filp: the file
1715 *
1716 * The value returned by this function will be one of
1717 * (if no lease break is pending):
1718 *
1719 * %F_RDLCK to indicate a shared lease is held.
1720 *
1721 * %F_WRLCK to indicate an exclusive lease is held.
1722 *
1723 * %F_UNLCK to indicate no lease is held.
1724 *
1725 * (if a lease break is pending):
1726 *
1727 * %F_RDLCK to indicate an exclusive lease needs to be
1728 * changed to a shared lease (or removed).
1729 *
1730 * %F_UNLCK to indicate the lease needs to be removed.
1731 *
1732 * XXX: sfr & willy disagree over whether F_INPROGRESS
1733 * should be returned to userspace.
1734 */
1735int fcntl_getlease(struct file *filp)
1736{
1737 struct file_lock *fl;
1738 struct inode *inode = locks_inode(filp);
1739 struct file_lock_context *ctx;
1740 int type = F_UNLCK;
1741 LIST_HEAD(dispose);
1742
1743 ctx = smp_load_acquire(&inode->i_flctx);
1744 if (ctx && !list_empty_careful(&ctx->flc_lease)) {
1745 percpu_down_read(&file_rwsem);
1746 spin_lock(&ctx->flc_lock);
1747 time_out_leases(inode, &dispose);
1748 list_for_each_entry(fl, &ctx->flc_lease, fl_list) {
1749 if (fl->fl_file != filp)
1750 continue;
1751 type = target_leasetype(fl);
1752 break;
1753 }
1754 spin_unlock(&ctx->flc_lock);
1755 percpu_up_read(&file_rwsem);
1756
1757 locks_dispose_list(&dispose);
1758 }
1759 return type;
1760}
1761
1762/**
1763 * check_conflicting_open - see if the given file points to an inode that has
1764 * an existing open that would conflict with the
1765 * desired lease.
1766 * @filp: file to check
1767 * @arg: type of lease that we're trying to acquire
1768 * @flags: current lock flags
1769 *
1770 * Check to see if there's an existing open fd on this file that would
1771 * conflict with the lease we're trying to set.
1772 */
1773static int
1774check_conflicting_open(struct file *filp, const long arg, int flags)
1775{
1776 struct inode *inode = locks_inode(filp);
1777 int self_wcount = 0, self_rcount = 0;
1778
1779 if (flags & FL_LAYOUT)
1780 return 0;
1781
1782 if (arg == F_RDLCK)
1783 return inode_is_open_for_write(inode) ? -EAGAIN : 0;
1784 else if (arg != F_WRLCK)
1785 return 0;
1786
1787 /*
1788 * Make sure that only read/write count is from lease requestor.
1789 * Note that this will result in denying write leases when i_writecount
1790 * is negative, which is what we want. (We shouldn't grant write leases
1791 * on files open for execution.)
1792 */
1793 if (filp->f_mode & FMODE_WRITE)
1794 self_wcount = 1;
1795 else if (filp->f_mode & FMODE_READ)
1796 self_rcount = 1;
1797
1798 if (atomic_read(&inode->i_writecount) != self_wcount ||
1799 atomic_read(&inode->i_readcount) != self_rcount)
1800 return -EAGAIN;
1801
1802 return 0;
1803}
1804
1805static int
1806generic_add_lease(struct file *filp, long arg, struct file_lock **flp, void **priv)
1807{
1808 struct file_lock *fl, *my_fl = NULL, *lease;
1809 struct inode *inode = locks_inode(filp);
1810 struct file_lock_context *ctx;
1811 bool is_deleg = (*flp)->fl_flags & FL_DELEG;
1812 int error;
1813 LIST_HEAD(dispose);
1814
1815 lease = *flp;
1816 trace_generic_add_lease(inode, lease);
1817
1818 /* Note that arg is never F_UNLCK here */
1819 ctx = locks_get_lock_context(inode, arg);
1820 if (!ctx)
1821 return -ENOMEM;
1822
1823 /*
1824 * In the delegation case we need mutual exclusion with
1825 * a number of operations that take the i_mutex. We trylock
1826 * because delegations are an optional optimization, and if
1827 * there's some chance of a conflict--we'd rather not
1828 * bother, maybe that's a sign this just isn't a good file to
1829 * hand out a delegation on.
1830 */
1831 if (is_deleg && !inode_trylock(inode))
1832 return -EAGAIN;
1833
1834 if (is_deleg && arg == F_WRLCK) {
1835 /* Write delegations are not currently supported: */
1836 inode_unlock(inode);
1837 WARN_ON_ONCE(1);
1838 return -EINVAL;
1839 }
1840
1841 percpu_down_read(&file_rwsem);
1842 spin_lock(&ctx->flc_lock);
1843 time_out_leases(inode, &dispose);
1844 error = check_conflicting_open(filp, arg, lease->fl_flags);
1845 if (error)
1846 goto out;
1847
1848 /*
1849 * At this point, we know that if there is an exclusive
1850 * lease on this file, then we hold it on this filp
1851 * (otherwise our open of this file would have blocked).
1852 * And if we are trying to acquire an exclusive lease,
1853 * then the file is not open by anyone (including us)
1854 * except for this filp.
1855 */
1856 error = -EAGAIN;
1857 list_for_each_entry(fl, &ctx->flc_lease, fl_list) {
1858 if (fl->fl_file == filp &&
1859 fl->fl_owner == lease->fl_owner) {
1860 my_fl = fl;
1861 continue;
1862 }
1863
1864 /*
1865 * No exclusive leases if someone else has a lease on
1866 * this file:
1867 */
1868 if (arg == F_WRLCK)
1869 goto out;
1870 /*
1871 * Modifying our existing lease is OK, but no getting a
1872 * new lease if someone else is opening for write:
1873 */
1874 if (fl->fl_flags & FL_UNLOCK_PENDING)
1875 goto out;
1876 }
1877
1878 if (my_fl != NULL) {
1879 lease = my_fl;
1880 error = lease->fl_lmops->lm_change(lease, arg, &dispose);
1881 if (error)
1882 goto out;
1883 goto out_setup;
1884 }
1885
1886 error = -EINVAL;
1887 if (!leases_enable)
1888 goto out;
1889
1890 locks_insert_lock_ctx(lease, &ctx->flc_lease);
1891 /*
1892 * The check in break_lease() is lockless. It's possible for another
1893 * open to race in after we did the earlier check for a conflicting
1894 * open but before the lease was inserted. Check again for a
1895 * conflicting open and cancel the lease if there is one.
1896 *
1897 * We also add a barrier here to ensure that the insertion of the lock
1898 * precedes these checks.
1899 */
1900 smp_mb();
1901 error = check_conflicting_open(filp, arg, lease->fl_flags);
1902 if (error) {
1903 locks_unlink_lock_ctx(lease);
1904 goto out;
1905 }
1906
1907out_setup:
1908 if (lease->fl_lmops->lm_setup)
1909 lease->fl_lmops->lm_setup(lease, priv);
1910out:
1911 spin_unlock(&ctx->flc_lock);
1912 percpu_up_read(&file_rwsem);
1913 locks_dispose_list(&dispose);
1914 if (is_deleg)
1915 inode_unlock(inode);
1916 if (!error && !my_fl)
1917 *flp = NULL;
1918 return error;
1919}
1920
1921static int generic_delete_lease(struct file *filp, void *owner)
1922{
1923 int error = -EAGAIN;
1924 struct file_lock *fl, *victim = NULL;
1925 struct inode *inode = locks_inode(filp);
1926 struct file_lock_context *ctx;
1927 LIST_HEAD(dispose);
1928
1929 ctx = smp_load_acquire(&inode->i_flctx);
1930 if (!ctx) {
1931 trace_generic_delete_lease(inode, NULL);
1932 return error;
1933 }
1934
1935 percpu_down_read(&file_rwsem);
1936 spin_lock(&ctx->flc_lock);
1937 list_for_each_entry(fl, &ctx->flc_lease, fl_list) {
1938 if (fl->fl_file == filp &&
1939 fl->fl_owner == owner) {
1940 victim = fl;
1941 break;
1942 }
1943 }
1944 trace_generic_delete_lease(inode, victim);
1945 if (victim)
1946 error = fl->fl_lmops->lm_change(victim, F_UNLCK, &dispose);
1947 spin_unlock(&ctx->flc_lock);
1948 percpu_up_read(&file_rwsem);
1949 locks_dispose_list(&dispose);
1950 return error;
1951}
1952
1953/**
1954 * generic_setlease - sets a lease on an open file
1955 * @filp: file pointer
1956 * @arg: type of lease to obtain
1957 * @flp: input - file_lock to use, output - file_lock inserted
1958 * @priv: private data for lm_setup (may be NULL if lm_setup
1959 * doesn't require it)
1960 *
1961 * The (input) flp->fl_lmops->lm_break function is required
1962 * by break_lease().
1963 */
1964int generic_setlease(struct file *filp, long arg, struct file_lock **flp,
1965 void **priv)
1966{
1967 struct inode *inode = locks_inode(filp);
1968 int error;
1969
1970 if ((!uid_eq(current_fsuid(), inode->i_uid)) && !capable(CAP_LEASE))
1971 return -EACCES;
1972 if (!S_ISREG(inode->i_mode))
1973 return -EINVAL;
1974 error = security_file_lock(filp, arg);
1975 if (error)
1976 return error;
1977
1978 switch (arg) {
1979 case F_UNLCK:
1980 return generic_delete_lease(filp, *priv);
1981 case F_RDLCK:
1982 case F_WRLCK:
1983 if (!(*flp)->fl_lmops->lm_break) {
1984 WARN_ON_ONCE(1);
1985 return -ENOLCK;
1986 }
1987
1988 return generic_add_lease(filp, arg, flp, priv);
1989 default:
1990 return -EINVAL;
1991 }
1992}
1993EXPORT_SYMBOL(generic_setlease);
1994
1995#if IS_ENABLED(CONFIG_SRCU)
1996/*
1997 * Kernel subsystems can register to be notified on any attempt to set
1998 * a new lease with the lease_notifier_chain. This is used by (e.g.) nfsd
1999 * to close files that it may have cached when there is an attempt to set a
2000 * conflicting lease.
2001 */
2002static struct srcu_notifier_head lease_notifier_chain;
2003
2004static inline void
2005lease_notifier_chain_init(void)
2006{
2007 srcu_init_notifier_head(&lease_notifier_chain);
2008}
2009
2010static inline void
2011setlease_notifier(long arg, struct file_lock *lease)
2012{
2013 if (arg != F_UNLCK)
2014 srcu_notifier_call_chain(&lease_notifier_chain, arg, lease);
2015}
2016
2017int lease_register_notifier(struct notifier_block *nb)
2018{
2019 return srcu_notifier_chain_register(&lease_notifier_chain, nb);
2020}
2021EXPORT_SYMBOL_GPL(lease_register_notifier);
2022
2023void lease_unregister_notifier(struct notifier_block *nb)
2024{
2025 srcu_notifier_chain_unregister(&lease_notifier_chain, nb);
2026}
2027EXPORT_SYMBOL_GPL(lease_unregister_notifier);
2028
2029#else /* !IS_ENABLED(CONFIG_SRCU) */
2030static inline void
2031lease_notifier_chain_init(void)
2032{
2033}
2034
2035static inline void
2036setlease_notifier(long arg, struct file_lock *lease)
2037{
2038}
2039
2040int lease_register_notifier(struct notifier_block *nb)
2041{
2042 return 0;
2043}
2044EXPORT_SYMBOL_GPL(lease_register_notifier);
2045
2046void lease_unregister_notifier(struct notifier_block *nb)
2047{
2048}
2049EXPORT_SYMBOL_GPL(lease_unregister_notifier);
2050
2051#endif /* IS_ENABLED(CONFIG_SRCU) */
2052
2053/**
2054 * vfs_setlease - sets a lease on an open file
2055 * @filp: file pointer
2056 * @arg: type of lease to obtain
2057 * @lease: file_lock to use when adding a lease
2058 * @priv: private info for lm_setup when adding a lease (may be
2059 * NULL if lm_setup doesn't require it)
2060 *
2061 * Call this to establish a lease on the file. The "lease" argument is not
2062 * used for F_UNLCK requests and may be NULL. For commands that set or alter
2063 * an existing lease, the ``(*lease)->fl_lmops->lm_break`` operation must be
2064 * set; if not, this function will return -ENOLCK (and generate a scary-looking
2065 * stack trace).
2066 *
2067 * The "priv" pointer is passed directly to the lm_setup function as-is. It
2068 * may be NULL if the lm_setup operation doesn't require it.
2069 */
2070int
2071vfs_setlease(struct file *filp, long arg, struct file_lock **lease, void **priv)
2072{
2073 if (lease)
2074 setlease_notifier(arg, *lease);
2075 if (filp->f_op->setlease)
2076 return filp->f_op->setlease(filp, arg, lease, priv);
2077 else
2078 return generic_setlease(filp, arg, lease, priv);
2079}
2080EXPORT_SYMBOL_GPL(vfs_setlease);
2081
2082static int do_fcntl_add_lease(unsigned int fd, struct file *filp, long arg)
2083{
2084 struct file_lock *fl;
2085 struct fasync_struct *new;
2086 int error;
2087
2088 fl = lease_alloc(filp, arg);
2089 if (IS_ERR(fl))
2090 return PTR_ERR(fl);
2091
2092 new = fasync_alloc();
2093 if (!new) {
2094 locks_free_lock(fl);
2095 return -ENOMEM;
2096 }
2097 new->fa_fd = fd;
2098
2099 error = vfs_setlease(filp, arg, &fl, (void **)&new);
2100 if (fl)
2101 locks_free_lock(fl);
2102 if (new)
2103 fasync_free(new);
2104 return error;
2105}
2106
2107/**
2108 * fcntl_setlease - sets a lease on an open file
2109 * @fd: open file descriptor
2110 * @filp: file pointer
2111 * @arg: type of lease to obtain
2112 *
2113 * Call this fcntl to establish a lease on the file.
2114 * Note that you also need to call %F_SETSIG to
2115 * receive a signal when the lease is broken.
2116 */
2117int fcntl_setlease(unsigned int fd, struct file *filp, long arg)
2118{
2119 if (arg == F_UNLCK)
2120 return vfs_setlease(filp, F_UNLCK, NULL, (void **)&filp);
2121 return do_fcntl_add_lease(fd, filp, arg);
2122}
2123
2124/**
2125 * flock_lock_inode_wait - Apply a FLOCK-style lock to a file
2126 * @inode: inode of the file to apply to
2127 * @fl: The lock to be applied
2128 *
2129 * Apply a FLOCK style lock request to an inode.
2130 */
2131static int flock_lock_inode_wait(struct inode *inode, struct file_lock *fl)
2132{
2133 int error;
2134 might_sleep();
2135 for (;;) {
2136 error = flock_lock_inode(inode, fl);
2137 if (error != FILE_LOCK_DEFERRED)
2138 break;
2139 error = wait_event_interruptible(fl->fl_wait, !fl->fl_blocker);
2140 if (error)
2141 break;
2142 }
2143 locks_delete_block(fl);
2144 return error;
2145}
2146
2147/**
2148 * locks_lock_inode_wait - Apply a lock to an inode
2149 * @inode: inode of the file to apply to
2150 * @fl: The lock to be applied
2151 *
2152 * Apply a POSIX or FLOCK style lock request to an inode.
2153 */
2154int locks_lock_inode_wait(struct inode *inode, struct file_lock *fl)
2155{
2156 int res = 0;
2157 switch (fl->fl_flags & (FL_POSIX|FL_FLOCK)) {
2158 case FL_POSIX:
2159 res = posix_lock_inode_wait(inode, fl);
2160 break;
2161 case FL_FLOCK:
2162 res = flock_lock_inode_wait(inode, fl);
2163 break;
2164 default:
2165 BUG();
2166 }
2167 return res;
2168}
2169EXPORT_SYMBOL(locks_lock_inode_wait);
2170
2171/**
2172 * sys_flock: - flock() system call.
2173 * @fd: the file descriptor to lock.
2174 * @cmd: the type of lock to apply.
2175 *
2176 * Apply a %FL_FLOCK style lock to an open file descriptor.
2177 * The @cmd can be one of:
2178 *
2179 * - %LOCK_SH -- a shared lock.
2180 * - %LOCK_EX -- an exclusive lock.
2181 * - %LOCK_UN -- remove an existing lock.
2182 * - %LOCK_MAND -- a 'mandatory' flock.
2183 * This exists to emulate Windows Share Modes.
2184 *
2185 * %LOCK_MAND can be combined with %LOCK_READ or %LOCK_WRITE to allow other
2186 * processes read and write access respectively.
2187 */
2188SYSCALL_DEFINE2(flock, unsigned int, fd, unsigned int, cmd)
2189{
2190 struct fd f = fdget(fd);
2191 struct file_lock *lock;
2192 int can_sleep, unlock;
2193 int error;
2194
2195 error = -EBADF;
2196 if (!f.file)
2197 goto out;
2198
2199 can_sleep = !(cmd & LOCK_NB);
2200 cmd &= ~LOCK_NB;
2201 unlock = (cmd == LOCK_UN);
2202
2203 if (!unlock && !(cmd & LOCK_MAND) &&
2204 !(f.file->f_mode & (FMODE_READ|FMODE_WRITE)))
2205 goto out_putf;
2206
2207 lock = flock_make_lock(f.file, cmd, NULL);
2208 if (IS_ERR(lock)) {
2209 error = PTR_ERR(lock);
2210 goto out_putf;
2211 }
2212
2213 if (can_sleep)
2214 lock->fl_flags |= FL_SLEEP;
2215
2216 error = security_file_lock(f.file, lock->fl_type);
2217 if (error)
2218 goto out_free;
2219
2220 if (f.file->f_op->flock)
2221 error = f.file->f_op->flock(f.file,
2222 (can_sleep) ? F_SETLKW : F_SETLK,
2223 lock);
2224 else
2225 error = locks_lock_file_wait(f.file, lock);
2226
2227 out_free:
2228 locks_free_lock(lock);
2229
2230 out_putf:
2231 fdput(f);
2232 out:
2233 return error;
2234}
2235
2236/**
2237 * vfs_test_lock - test file byte range lock
2238 * @filp: The file to test lock for
2239 * @fl: The lock to test; also used to hold result
2240 *
2241 * Returns -ERRNO on failure. Indicates presence of conflicting lock by
2242 * setting conf->fl_type to something other than F_UNLCK.
2243 */
2244int vfs_test_lock(struct file *filp, struct file_lock *fl)
2245{
2246 if (filp->f_op->lock)
2247 return filp->f_op->lock(filp, F_GETLK, fl);
2248 posix_test_lock(filp, fl);
2249 return 0;
2250}
2251EXPORT_SYMBOL_GPL(vfs_test_lock);
2252
2253/**
2254 * locks_translate_pid - translate a file_lock's fl_pid number into a namespace
2255 * @fl: The file_lock who's fl_pid should be translated
2256 * @ns: The namespace into which the pid should be translated
2257 *
2258 * Used to tranlate a fl_pid into a namespace virtual pid number
2259 */
2260static pid_t locks_translate_pid(struct file_lock *fl, struct pid_namespace *ns)
2261{
2262 pid_t vnr;
2263 struct pid *pid;
2264
2265 if (IS_OFDLCK(fl))
2266 return -1;
2267 if (IS_REMOTELCK(fl))
2268 return fl->fl_pid;
2269 /*
2270 * If the flock owner process is dead and its pid has been already
2271 * freed, the translation below won't work, but we still want to show
2272 * flock owner pid number in init pidns.
2273 */
2274 if (ns == &init_pid_ns)
2275 return (pid_t)fl->fl_pid;
2276
2277 rcu_read_lock();
2278 pid = find_pid_ns(fl->fl_pid, &init_pid_ns);
2279 vnr = pid_nr_ns(pid, ns);
2280 rcu_read_unlock();
2281 return vnr;
2282}
2283
2284static int posix_lock_to_flock(struct flock *flock, struct file_lock *fl)
2285{
2286 flock->l_pid = locks_translate_pid(fl, task_active_pid_ns(current));
2287#if BITS_PER_LONG == 32
2288 /*
2289 * Make sure we can represent the posix lock via
2290 * legacy 32bit flock.
2291 */
2292 if (fl->fl_start > OFFT_OFFSET_MAX)
2293 return -EOVERFLOW;
2294 if (fl->fl_end != OFFSET_MAX && fl->fl_end > OFFT_OFFSET_MAX)
2295 return -EOVERFLOW;
2296#endif
2297 flock->l_start = fl->fl_start;
2298 flock->l_len = fl->fl_end == OFFSET_MAX ? 0 :
2299 fl->fl_end - fl->fl_start + 1;
2300 flock->l_whence = 0;
2301 flock->l_type = fl->fl_type;
2302 return 0;
2303}
2304
2305#if BITS_PER_LONG == 32
2306static void posix_lock_to_flock64(struct flock64 *flock, struct file_lock *fl)
2307{
2308 flock->l_pid = locks_translate_pid(fl, task_active_pid_ns(current));
2309 flock->l_start = fl->fl_start;
2310 flock->l_len = fl->fl_end == OFFSET_MAX ? 0 :
2311 fl->fl_end - fl->fl_start + 1;
2312 flock->l_whence = 0;
2313 flock->l_type = fl->fl_type;
2314}
2315#endif
2316
2317/* Report the first existing lock that would conflict with l.
2318 * This implements the F_GETLK command of fcntl().
2319 */
2320int fcntl_getlk(struct file *filp, unsigned int cmd, struct flock *flock)
2321{
2322 struct file_lock *fl;
2323 int error;
2324
2325 fl = locks_alloc_lock();
2326 if (fl == NULL)
2327 return -ENOMEM;
2328 error = -EINVAL;
2329 if (flock->l_type != F_RDLCK && flock->l_type != F_WRLCK)
2330 goto out;
2331
2332 error = flock_to_posix_lock(filp, fl, flock);
2333 if (error)
2334 goto out;
2335
2336 if (cmd == F_OFD_GETLK) {
2337 error = -EINVAL;
2338 if (flock->l_pid != 0)
2339 goto out;
2340
2341 cmd = F_GETLK;
2342 fl->fl_flags |= FL_OFDLCK;
2343 fl->fl_owner = filp;
2344 }
2345
2346 error = vfs_test_lock(filp, fl);
2347 if (error)
2348 goto out;
2349
2350 flock->l_type = fl->fl_type;
2351 if (fl->fl_type != F_UNLCK) {
2352 error = posix_lock_to_flock(flock, fl);
2353 if (error)
2354 goto out;
2355 }
2356out:
2357 locks_free_lock(fl);
2358 return error;
2359}
2360
2361/**
2362 * vfs_lock_file - file byte range lock
2363 * @filp: The file to apply the lock to
2364 * @cmd: type of locking operation (F_SETLK, F_GETLK, etc.)
2365 * @fl: The lock to be applied
2366 * @conf: Place to return a copy of the conflicting lock, if found.
2367 *
2368 * A caller that doesn't care about the conflicting lock may pass NULL
2369 * as the final argument.
2370 *
2371 * If the filesystem defines a private ->lock() method, then @conf will
2372 * be left unchanged; so a caller that cares should initialize it to
2373 * some acceptable default.
2374 *
2375 * To avoid blocking kernel daemons, such as lockd, that need to acquire POSIX
2376 * locks, the ->lock() interface may return asynchronously, before the lock has
2377 * been granted or denied by the underlying filesystem, if (and only if)
2378 * lm_grant is set. Callers expecting ->lock() to return asynchronously
2379 * will only use F_SETLK, not F_SETLKW; they will set FL_SLEEP if (and only if)
2380 * the request is for a blocking lock. When ->lock() does return asynchronously,
2381 * it must return FILE_LOCK_DEFERRED, and call ->lm_grant() when the lock
2382 * request completes.
2383 * If the request is for non-blocking lock the file system should return
2384 * FILE_LOCK_DEFERRED then try to get the lock and call the callback routine
2385 * with the result. If the request timed out the callback routine will return a
2386 * nonzero return code and the file system should release the lock. The file
2387 * system is also responsible to keep a corresponding posix lock when it
2388 * grants a lock so the VFS can find out which locks are locally held and do
2389 * the correct lock cleanup when required.
2390 * The underlying filesystem must not drop the kernel lock or call
2391 * ->lm_grant() before returning to the caller with a FILE_LOCK_DEFERRED
2392 * return code.
2393 */
2394int vfs_lock_file(struct file *filp, unsigned int cmd, struct file_lock *fl, struct file_lock *conf)
2395{
2396 if (filp->f_op->lock)
2397 return filp->f_op->lock(filp, cmd, fl);
2398 else
2399 return posix_lock_file(filp, fl, conf);
2400}
2401EXPORT_SYMBOL_GPL(vfs_lock_file);
2402
2403static int do_lock_file_wait(struct file *filp, unsigned int cmd,
2404 struct file_lock *fl)
2405{
2406 int error;
2407
2408 error = security_file_lock(filp, fl->fl_type);
2409 if (error)
2410 return error;
2411
2412 for (;;) {
2413 error = vfs_lock_file(filp, cmd, fl, NULL);
2414 if (error != FILE_LOCK_DEFERRED)
2415 break;
2416 error = wait_event_interruptible(fl->fl_wait, !fl->fl_blocker);
2417 if (error)
2418 break;
2419 }
2420 locks_delete_block(fl);
2421
2422 return error;
2423}
2424
2425/* Ensure that fl->fl_file has compatible f_mode for F_SETLK calls */
2426static int
2427check_fmode_for_setlk(struct file_lock *fl)
2428{
2429 switch (fl->fl_type) {
2430 case F_RDLCK:
2431 if (!(fl->fl_file->f_mode & FMODE_READ))
2432 return -EBADF;
2433 break;
2434 case F_WRLCK:
2435 if (!(fl->fl_file->f_mode & FMODE_WRITE))
2436 return -EBADF;
2437 }
2438 return 0;
2439}
2440
2441/* Apply the lock described by l to an open file descriptor.
2442 * This implements both the F_SETLK and F_SETLKW commands of fcntl().
2443 */
2444int fcntl_setlk(unsigned int fd, struct file *filp, unsigned int cmd,
2445 struct flock *flock)
2446{
2447 struct file_lock *file_lock = locks_alloc_lock();
2448 struct inode *inode = locks_inode(filp);
2449 struct file *f;
2450 int error;
2451
2452 if (file_lock == NULL)
2453 return -ENOLCK;
2454
2455 /* Don't allow mandatory locks on files that may be memory mapped
2456 * and shared.
2457 */
2458 if (mandatory_lock(inode) && mapping_writably_mapped(filp->f_mapping)) {
2459 error = -EAGAIN;
2460 goto out;
2461 }
2462
2463 error = flock_to_posix_lock(filp, file_lock, flock);
2464 if (error)
2465 goto out;
2466
2467 error = check_fmode_for_setlk(file_lock);
2468 if (error)
2469 goto out;
2470
2471 /*
2472 * If the cmd is requesting file-private locks, then set the
2473 * FL_OFDLCK flag and override the owner.
2474 */
2475 switch (cmd) {
2476 case F_OFD_SETLK:
2477 error = -EINVAL;
2478 if (flock->l_pid != 0)
2479 goto out;
2480
2481 cmd = F_SETLK;
2482 file_lock->fl_flags |= FL_OFDLCK;
2483 file_lock->fl_owner = filp;
2484 break;
2485 case F_OFD_SETLKW:
2486 error = -EINVAL;
2487 if (flock->l_pid != 0)
2488 goto out;
2489
2490 cmd = F_SETLKW;
2491 file_lock->fl_flags |= FL_OFDLCK;
2492 file_lock->fl_owner = filp;
2493 /* Fallthrough */
2494 case F_SETLKW:
2495 file_lock->fl_flags |= FL_SLEEP;
2496 }
2497
2498 error = do_lock_file_wait(filp, cmd, file_lock);
2499
2500 /*
2501 * Attempt to detect a close/fcntl race and recover by releasing the
2502 * lock that was just acquired. There is no need to do that when we're
2503 * unlocking though, or for OFD locks.
2504 */
2505 if (!error && file_lock->fl_type != F_UNLCK &&
2506 !(file_lock->fl_flags & FL_OFDLCK)) {
2507 /*
2508 * We need that spin_lock here - it prevents reordering between
2509 * update of i_flctx->flc_posix and check for it done in
2510 * close(). rcu_read_lock() wouldn't do.
2511 */
2512 spin_lock(¤t->files->file_lock);
2513 f = fcheck(fd);
2514 spin_unlock(¤t->files->file_lock);
2515 if (f != filp) {
2516 file_lock->fl_type = F_UNLCK;
2517 error = do_lock_file_wait(filp, cmd, file_lock);
2518 WARN_ON_ONCE(error);
2519 error = -EBADF;
2520 }
2521 }
2522out:
2523 trace_fcntl_setlk(inode, file_lock, error);
2524 locks_free_lock(file_lock);
2525 return error;
2526}
2527
2528#if BITS_PER_LONG == 32
2529/* Report the first existing lock that would conflict with l.
2530 * This implements the F_GETLK command of fcntl().
2531 */
2532int fcntl_getlk64(struct file *filp, unsigned int cmd, struct flock64 *flock)
2533{
2534 struct file_lock *fl;
2535 int error;
2536
2537 fl = locks_alloc_lock();
2538 if (fl == NULL)
2539 return -ENOMEM;
2540
2541 error = -EINVAL;
2542 if (flock->l_type != F_RDLCK && flock->l_type != F_WRLCK)
2543 goto out;
2544
2545 error = flock64_to_posix_lock(filp, fl, flock);
2546 if (error)
2547 goto out;
2548
2549 if (cmd == F_OFD_GETLK) {
2550 error = -EINVAL;
2551 if (flock->l_pid != 0)
2552 goto out;
2553
2554 cmd = F_GETLK64;
2555 fl->fl_flags |= FL_OFDLCK;
2556 fl->fl_owner = filp;
2557 }
2558
2559 error = vfs_test_lock(filp, fl);
2560 if (error)
2561 goto out;
2562
2563 flock->l_type = fl->fl_type;
2564 if (fl->fl_type != F_UNLCK)
2565 posix_lock_to_flock64(flock, fl);
2566
2567out:
2568 locks_free_lock(fl);
2569 return error;
2570}
2571
2572/* Apply the lock described by l to an open file descriptor.
2573 * This implements both the F_SETLK and F_SETLKW commands of fcntl().
2574 */
2575int fcntl_setlk64(unsigned int fd, struct file *filp, unsigned int cmd,
2576 struct flock64 *flock)
2577{
2578 struct file_lock *file_lock = locks_alloc_lock();
2579 struct inode *inode = locks_inode(filp);
2580 struct file *f;
2581 int error;
2582
2583 if (file_lock == NULL)
2584 return -ENOLCK;
2585
2586 /* Don't allow mandatory locks on files that may be memory mapped
2587 * and shared.
2588 */
2589 if (mandatory_lock(inode) && mapping_writably_mapped(filp->f_mapping)) {
2590 error = -EAGAIN;
2591 goto out;
2592 }
2593
2594 error = flock64_to_posix_lock(filp, file_lock, flock);
2595 if (error)
2596 goto out;
2597
2598 error = check_fmode_for_setlk(file_lock);
2599 if (error)
2600 goto out;
2601
2602 /*
2603 * If the cmd is requesting file-private locks, then set the
2604 * FL_OFDLCK flag and override the owner.
2605 */
2606 switch (cmd) {
2607 case F_OFD_SETLK:
2608 error = -EINVAL;
2609 if (flock->l_pid != 0)
2610 goto out;
2611
2612 cmd = F_SETLK64;
2613 file_lock->fl_flags |= FL_OFDLCK;
2614 file_lock->fl_owner = filp;
2615 break;
2616 case F_OFD_SETLKW:
2617 error = -EINVAL;
2618 if (flock->l_pid != 0)
2619 goto out;
2620
2621 cmd = F_SETLKW64;
2622 file_lock->fl_flags |= FL_OFDLCK;
2623 file_lock->fl_owner = filp;
2624 /* Fallthrough */
2625 case F_SETLKW64:
2626 file_lock->fl_flags |= FL_SLEEP;
2627 }
2628
2629 error = do_lock_file_wait(filp, cmd, file_lock);
2630
2631 /*
2632 * Attempt to detect a close/fcntl race and recover by releasing the
2633 * lock that was just acquired. There is no need to do that when we're
2634 * unlocking though, or for OFD locks.
2635 */
2636 if (!error && file_lock->fl_type != F_UNLCK &&
2637 !(file_lock->fl_flags & FL_OFDLCK)) {
2638 /*
2639 * We need that spin_lock here - it prevents reordering between
2640 * update of i_flctx->flc_posix and check for it done in
2641 * close(). rcu_read_lock() wouldn't do.
2642 */
2643 spin_lock(¤t->files->file_lock);
2644 f = fcheck(fd);
2645 spin_unlock(¤t->files->file_lock);
2646 if (f != filp) {
2647 file_lock->fl_type = F_UNLCK;
2648 error = do_lock_file_wait(filp, cmd, file_lock);
2649 WARN_ON_ONCE(error);
2650 error = -EBADF;
2651 }
2652 }
2653out:
2654 locks_free_lock(file_lock);
2655 return error;
2656}
2657#endif /* BITS_PER_LONG == 32 */
2658
2659/*
2660 * This function is called when the file is being removed
2661 * from the task's fd array. POSIX locks belonging to this task
2662 * are deleted at this time.
2663 */
2664void locks_remove_posix(struct file *filp, fl_owner_t owner)
2665{
2666 int error;
2667 struct inode *inode = locks_inode(filp);
2668 struct file_lock lock;
2669 struct file_lock_context *ctx;
2670
2671 /*
2672 * If there are no locks held on this file, we don't need to call
2673 * posix_lock_file(). Another process could be setting a lock on this
2674 * file at the same time, but we wouldn't remove that lock anyway.
2675 */
2676 ctx = smp_load_acquire(&inode->i_flctx);
2677 if (!ctx || list_empty(&ctx->flc_posix))
2678 return;
2679
2680 locks_init_lock(&lock);
2681 lock.fl_type = F_UNLCK;
2682 lock.fl_flags = FL_POSIX | FL_CLOSE;
2683 lock.fl_start = 0;
2684 lock.fl_end = OFFSET_MAX;
2685 lock.fl_owner = owner;
2686 lock.fl_pid = current->tgid;
2687 lock.fl_file = filp;
2688 lock.fl_ops = NULL;
2689 lock.fl_lmops = NULL;
2690
2691 error = vfs_lock_file(filp, F_SETLK, &lock, NULL);
2692
2693 if (lock.fl_ops && lock.fl_ops->fl_release_private)
2694 lock.fl_ops->fl_release_private(&lock);
2695 trace_locks_remove_posix(inode, &lock, error);
2696}
2697EXPORT_SYMBOL(locks_remove_posix);
2698
2699/* The i_flctx must be valid when calling into here */
2700static void
2701locks_remove_flock(struct file *filp, struct file_lock_context *flctx)
2702{
2703 struct file_lock fl;
2704 struct inode *inode = locks_inode(filp);
2705
2706 if (list_empty(&flctx->flc_flock))
2707 return;
2708
2709 flock_make_lock(filp, LOCK_UN, &fl);
2710 fl.fl_flags |= FL_CLOSE;
2711
2712 if (filp->f_op->flock)
2713 filp->f_op->flock(filp, F_SETLKW, &fl);
2714 else
2715 flock_lock_inode(inode, &fl);
2716
2717 if (fl.fl_ops && fl.fl_ops->fl_release_private)
2718 fl.fl_ops->fl_release_private(&fl);
2719}
2720
2721/* The i_flctx must be valid when calling into here */
2722static void
2723locks_remove_lease(struct file *filp, struct file_lock_context *ctx)
2724{
2725 struct file_lock *fl, *tmp;
2726 LIST_HEAD(dispose);
2727
2728 if (list_empty(&ctx->flc_lease))
2729 return;
2730
2731 percpu_down_read(&file_rwsem);
2732 spin_lock(&ctx->flc_lock);
2733 list_for_each_entry_safe(fl, tmp, &ctx->flc_lease, fl_list)
2734 if (filp == fl->fl_file)
2735 lease_modify(fl, F_UNLCK, &dispose);
2736 spin_unlock(&ctx->flc_lock);
2737 percpu_up_read(&file_rwsem);
2738
2739 locks_dispose_list(&dispose);
2740}
2741
2742/*
2743 * This function is called on the last close of an open file.
2744 */
2745void locks_remove_file(struct file *filp)
2746{
2747 struct file_lock_context *ctx;
2748
2749 ctx = smp_load_acquire(&locks_inode(filp)->i_flctx);
2750 if (!ctx)
2751 return;
2752
2753 /* remove any OFD locks */
2754 locks_remove_posix(filp, filp);
2755
2756 /* remove flock locks */
2757 locks_remove_flock(filp, ctx);
2758
2759 /* remove any leases */
2760 locks_remove_lease(filp, ctx);
2761
2762 spin_lock(&ctx->flc_lock);
2763 locks_check_ctx_file_list(filp, &ctx->flc_posix, "POSIX");
2764 locks_check_ctx_file_list(filp, &ctx->flc_flock, "FLOCK");
2765 locks_check_ctx_file_list(filp, &ctx->flc_lease, "LEASE");
2766 spin_unlock(&ctx->flc_lock);
2767}
2768
2769/**
2770 * vfs_cancel_lock - file byte range unblock lock
2771 * @filp: The file to apply the unblock to
2772 * @fl: The lock to be unblocked
2773 *
2774 * Used by lock managers to cancel blocked requests
2775 */
2776int vfs_cancel_lock(struct file *filp, struct file_lock *fl)
2777{
2778 if (filp->f_op->lock)
2779 return filp->f_op->lock(filp, F_CANCELLK, fl);
2780 return 0;
2781}
2782EXPORT_SYMBOL_GPL(vfs_cancel_lock);
2783
2784#ifdef CONFIG_PROC_FS
2785#include <linux/proc_fs.h>
2786#include <linux/seq_file.h>
2787
2788struct locks_iterator {
2789 int li_cpu;
2790 loff_t li_pos;
2791};
2792
2793static void lock_get_status(struct seq_file *f, struct file_lock *fl,
2794 loff_t id, char *pfx)
2795{
2796 struct inode *inode = NULL;
2797 unsigned int fl_pid;
2798 struct pid_namespace *proc_pidns = file_inode(f->file)->i_sb->s_fs_info;
2799
2800 fl_pid = locks_translate_pid(fl, proc_pidns);
2801 /*
2802 * If lock owner is dead (and pid is freed) or not visible in current
2803 * pidns, zero is shown as a pid value. Check lock info from
2804 * init_pid_ns to get saved lock pid value.
2805 */
2806
2807 if (fl->fl_file != NULL)
2808 inode = locks_inode(fl->fl_file);
2809
2810 seq_printf(f, "%lld:%s ", id, pfx);
2811 if (IS_POSIX(fl)) {
2812 if (fl->fl_flags & FL_ACCESS)
2813 seq_puts(f, "ACCESS");
2814 else if (IS_OFDLCK(fl))
2815 seq_puts(f, "OFDLCK");
2816 else
2817 seq_puts(f, "POSIX ");
2818
2819 seq_printf(f, " %s ",
2820 (inode == NULL) ? "*NOINODE*" :
2821 mandatory_lock(inode) ? "MANDATORY" : "ADVISORY ");
2822 } else if (IS_FLOCK(fl)) {
2823 if (fl->fl_type & LOCK_MAND) {
2824 seq_puts(f, "FLOCK MSNFS ");
2825 } else {
2826 seq_puts(f, "FLOCK ADVISORY ");
2827 }
2828 } else if (IS_LEASE(fl)) {
2829 if (fl->fl_flags & FL_DELEG)
2830 seq_puts(f, "DELEG ");
2831 else
2832 seq_puts(f, "LEASE ");
2833
2834 if (lease_breaking(fl))
2835 seq_puts(f, "BREAKING ");
2836 else if (fl->fl_file)
2837 seq_puts(f, "ACTIVE ");
2838 else
2839 seq_puts(f, "BREAKER ");
2840 } else {
2841 seq_puts(f, "UNKNOWN UNKNOWN ");
2842 }
2843 if (fl->fl_type & LOCK_MAND) {
2844 seq_printf(f, "%s ",
2845 (fl->fl_type & LOCK_READ)
2846 ? (fl->fl_type & LOCK_WRITE) ? "RW " : "READ "
2847 : (fl->fl_type & LOCK_WRITE) ? "WRITE" : "NONE ");
2848 } else {
2849 int type = IS_LEASE(fl) ? target_leasetype(fl) : fl->fl_type;
2850
2851 seq_printf(f, "%s ", (type == F_WRLCK) ? "WRITE" :
2852 (type == F_RDLCK) ? "READ" : "UNLCK");
2853 }
2854 if (inode) {
2855 /* userspace relies on this representation of dev_t */
2856 seq_printf(f, "%d %02x:%02x:%ld ", fl_pid,
2857 MAJOR(inode->i_sb->s_dev),
2858 MINOR(inode->i_sb->s_dev), inode->i_ino);
2859 } else {
2860 seq_printf(f, "%d <none>:0 ", fl_pid);
2861 }
2862 if (IS_POSIX(fl)) {
2863 if (fl->fl_end == OFFSET_MAX)
2864 seq_printf(f, "%Ld EOF\n", fl->fl_start);
2865 else
2866 seq_printf(f, "%Ld %Ld\n", fl->fl_start, fl->fl_end);
2867 } else {
2868 seq_puts(f, "0 EOF\n");
2869 }
2870}
2871
2872static int locks_show(struct seq_file *f, void *v)
2873{
2874 struct locks_iterator *iter = f->private;
2875 struct file_lock *fl, *bfl;
2876 struct pid_namespace *proc_pidns = file_inode(f->file)->i_sb->s_fs_info;
2877
2878 fl = hlist_entry(v, struct file_lock, fl_link);
2879
2880 if (locks_translate_pid(fl, proc_pidns) == 0)
2881 return 0;
2882
2883 lock_get_status(f, fl, iter->li_pos, "");
2884
2885 list_for_each_entry(bfl, &fl->fl_blocked_requests, fl_blocked_member)
2886 lock_get_status(f, bfl, iter->li_pos, " ->");
2887
2888 return 0;
2889}
2890
2891static void __show_fd_locks(struct seq_file *f,
2892 struct list_head *head, int *id,
2893 struct file *filp, struct files_struct *files)
2894{
2895 struct file_lock *fl;
2896
2897 list_for_each_entry(fl, head, fl_list) {
2898
2899 if (filp != fl->fl_file)
2900 continue;
2901 if (fl->fl_owner != files &&
2902 fl->fl_owner != filp)
2903 continue;
2904
2905 (*id)++;
2906 seq_puts(f, "lock:\t");
2907 lock_get_status(f, fl, *id, "");
2908 }
2909}
2910
2911void show_fd_locks(struct seq_file *f,
2912 struct file *filp, struct files_struct *files)
2913{
2914 struct inode *inode = locks_inode(filp);
2915 struct file_lock_context *ctx;
2916 int id = 0;
2917
2918 ctx = smp_load_acquire(&inode->i_flctx);
2919 if (!ctx)
2920 return;
2921
2922 spin_lock(&ctx->flc_lock);
2923 __show_fd_locks(f, &ctx->flc_flock, &id, filp, files);
2924 __show_fd_locks(f, &ctx->flc_posix, &id, filp, files);
2925 __show_fd_locks(f, &ctx->flc_lease, &id, filp, files);
2926 spin_unlock(&ctx->flc_lock);
2927}
2928
2929static void *locks_start(struct seq_file *f, loff_t *pos)
2930 __acquires(&blocked_lock_lock)
2931{
2932 struct locks_iterator *iter = f->private;
2933
2934 iter->li_pos = *pos + 1;
2935 percpu_down_write(&file_rwsem);
2936 spin_lock(&blocked_lock_lock);
2937 return seq_hlist_start_percpu(&file_lock_list.hlist, &iter->li_cpu, *pos);
2938}
2939
2940static void *locks_next(struct seq_file *f, void *v, loff_t *pos)
2941{
2942 struct locks_iterator *iter = f->private;
2943
2944 ++iter->li_pos;
2945 return seq_hlist_next_percpu(v, &file_lock_list.hlist, &iter->li_cpu, pos);
2946}
2947
2948static void locks_stop(struct seq_file *f, void *v)
2949 __releases(&blocked_lock_lock)
2950{
2951 spin_unlock(&blocked_lock_lock);
2952 percpu_up_write(&file_rwsem);
2953}
2954
2955static const struct seq_operations locks_seq_operations = {
2956 .start = locks_start,
2957 .next = locks_next,
2958 .stop = locks_stop,
2959 .show = locks_show,
2960};
2961
2962static int __init proc_locks_init(void)
2963{
2964 proc_create_seq_private("locks", 0, NULL, &locks_seq_operations,
2965 sizeof(struct locks_iterator), NULL);
2966 return 0;
2967}
2968fs_initcall(proc_locks_init);
2969#endif
2970
2971static int __init filelock_init(void)
2972{
2973 int i;
2974
2975 flctx_cache = kmem_cache_create("file_lock_ctx",
2976 sizeof(struct file_lock_context), 0, SLAB_PANIC, NULL);
2977
2978 filelock_cache = kmem_cache_create("file_lock_cache",
2979 sizeof(struct file_lock), 0, SLAB_PANIC, NULL);
2980
2981 for_each_possible_cpu(i) {
2982 struct file_lock_list_struct *fll = per_cpu_ptr(&file_lock_list, i);
2983
2984 spin_lock_init(&fll->lock);
2985 INIT_HLIST_HEAD(&fll->hlist);
2986 }
2987
2988 lease_notifier_chain_init();
2989 return 0;
2990}
2991core_initcall(filelock_init);