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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.rst' 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}
729
730static void __locks_wake_up_blocks(struct file_lock *blocker)
731{
732 while (!list_empty(&blocker->fl_blocked_requests)) {
733 struct file_lock *waiter;
734
735 waiter = list_first_entry(&blocker->fl_blocked_requests,
736 struct file_lock, fl_blocked_member);
737 __locks_delete_block(waiter);
738 if (waiter->fl_lmops && waiter->fl_lmops->lm_notify)
739 waiter->fl_lmops->lm_notify(waiter);
740 else
741 wake_up(&waiter->fl_wait);
742
743 /*
744 * The setting of fl_blocker to NULL marks the "done"
745 * point in deleting a block. Paired with acquire at the top
746 * of locks_delete_block().
747 */
748 smp_store_release(&waiter->fl_blocker, NULL);
749 }
750}
751
752/**
753 * locks_delete_lock - stop waiting for a file lock
754 * @waiter: the lock which was waiting
755 *
756 * lockd/nfsd need to disconnect the lock while working on it.
757 */
758int locks_delete_block(struct file_lock *waiter)
759{
760 int status = -ENOENT;
761
762 /*
763 * If fl_blocker is NULL, it won't be set again as this thread "owns"
764 * the lock and is the only one that might try to claim the lock.
765 *
766 * We use acquire/release to manage fl_blocker so that we can
767 * optimize away taking the blocked_lock_lock in many cases.
768 *
769 * The smp_load_acquire guarantees two things:
770 *
771 * 1/ that fl_blocked_requests can be tested locklessly. If something
772 * was recently added to that list it must have been in a locked region
773 * *before* the locked region when fl_blocker was set to NULL.
774 *
775 * 2/ that no other thread is accessing 'waiter', so it is safe to free
776 * it. __locks_wake_up_blocks is careful not to touch waiter after
777 * fl_blocker is released.
778 *
779 * If a lockless check of fl_blocker shows it to be NULL, we know that
780 * no new locks can be inserted into its fl_blocked_requests list, and
781 * can avoid doing anything further if the list is empty.
782 */
783 if (!smp_load_acquire(&waiter->fl_blocker) &&
784 list_empty(&waiter->fl_blocked_requests))
785 return status;
786
787 spin_lock(&blocked_lock_lock);
788 if (waiter->fl_blocker)
789 status = 0;
790 __locks_wake_up_blocks(waiter);
791 __locks_delete_block(waiter);
792
793 /*
794 * The setting of fl_blocker to NULL marks the "done" point in deleting
795 * a block. Paired with acquire at the top of this function.
796 */
797 smp_store_release(&waiter->fl_blocker, NULL);
798 spin_unlock(&blocked_lock_lock);
799 return status;
800}
801EXPORT_SYMBOL(locks_delete_block);
802
803/* Insert waiter into blocker's block list.
804 * We use a circular list so that processes can be easily woken up in
805 * the order they blocked. The documentation doesn't require this but
806 * it seems like the reasonable thing to do.
807 *
808 * Must be called with both the flc_lock and blocked_lock_lock held. The
809 * fl_blocked_requests list itself is protected by the blocked_lock_lock,
810 * but by ensuring that the flc_lock is also held on insertions we can avoid
811 * taking the blocked_lock_lock in some cases when we see that the
812 * fl_blocked_requests list is empty.
813 *
814 * Rather than just adding to the list, we check for conflicts with any existing
815 * waiters, and add beneath any waiter that blocks the new waiter.
816 * Thus wakeups don't happen until needed.
817 */
818static void __locks_insert_block(struct file_lock *blocker,
819 struct file_lock *waiter,
820 bool conflict(struct file_lock *,
821 struct file_lock *))
822{
823 struct file_lock *fl;
824 BUG_ON(!list_empty(&waiter->fl_blocked_member));
825
826new_blocker:
827 list_for_each_entry(fl, &blocker->fl_blocked_requests, fl_blocked_member)
828 if (conflict(fl, waiter)) {
829 blocker = fl;
830 goto new_blocker;
831 }
832 waiter->fl_blocker = blocker;
833 list_add_tail(&waiter->fl_blocked_member, &blocker->fl_blocked_requests);
834 if (IS_POSIX(blocker) && !IS_OFDLCK(blocker))
835 locks_insert_global_blocked(waiter);
836
837 /* The requests in waiter->fl_blocked are known to conflict with
838 * waiter, but might not conflict with blocker, or the requests
839 * and lock which block it. So they all need to be woken.
840 */
841 __locks_wake_up_blocks(waiter);
842}
843
844/* Must be called with flc_lock held. */
845static void locks_insert_block(struct file_lock *blocker,
846 struct file_lock *waiter,
847 bool conflict(struct file_lock *,
848 struct file_lock *))
849{
850 spin_lock(&blocked_lock_lock);
851 __locks_insert_block(blocker, waiter, conflict);
852 spin_unlock(&blocked_lock_lock);
853}
854
855/*
856 * Wake up processes blocked waiting for blocker.
857 *
858 * Must be called with the inode->flc_lock held!
859 */
860static void locks_wake_up_blocks(struct file_lock *blocker)
861{
862 /*
863 * Avoid taking global lock if list is empty. This is safe since new
864 * blocked requests are only added to the list under the flc_lock, and
865 * the flc_lock is always held here. Note that removal from the
866 * fl_blocked_requests list does not require the flc_lock, so we must
867 * recheck list_empty() after acquiring the blocked_lock_lock.
868 */
869 if (list_empty(&blocker->fl_blocked_requests))
870 return;
871
872 spin_lock(&blocked_lock_lock);
873 __locks_wake_up_blocks(blocker);
874 spin_unlock(&blocked_lock_lock);
875}
876
877static void
878locks_insert_lock_ctx(struct file_lock *fl, struct list_head *before)
879{
880 list_add_tail(&fl->fl_list, before);
881 locks_insert_global_locks(fl);
882}
883
884static void
885locks_unlink_lock_ctx(struct file_lock *fl)
886{
887 locks_delete_global_locks(fl);
888 list_del_init(&fl->fl_list);
889 locks_wake_up_blocks(fl);
890}
891
892static void
893locks_delete_lock_ctx(struct file_lock *fl, struct list_head *dispose)
894{
895 locks_unlink_lock_ctx(fl);
896 if (dispose)
897 list_add(&fl->fl_list, dispose);
898 else
899 locks_free_lock(fl);
900}
901
902/* Determine if lock sys_fl blocks lock caller_fl. Common functionality
903 * checks for shared/exclusive status of overlapping locks.
904 */
905static bool locks_conflict(struct file_lock *caller_fl,
906 struct file_lock *sys_fl)
907{
908 if (sys_fl->fl_type == F_WRLCK)
909 return true;
910 if (caller_fl->fl_type == F_WRLCK)
911 return true;
912 return false;
913}
914
915/* Determine if lock sys_fl blocks lock caller_fl. POSIX specific
916 * checking before calling the locks_conflict().
917 */
918static bool posix_locks_conflict(struct file_lock *caller_fl,
919 struct file_lock *sys_fl)
920{
921 /* POSIX locks owned by the same process do not conflict with
922 * each other.
923 */
924 if (posix_same_owner(caller_fl, sys_fl))
925 return false;
926
927 /* Check whether they overlap */
928 if (!locks_overlap(caller_fl, sys_fl))
929 return false;
930
931 return locks_conflict(caller_fl, sys_fl);
932}
933
934/* Determine if lock sys_fl blocks lock caller_fl. FLOCK specific
935 * checking before calling the locks_conflict().
936 */
937static bool flock_locks_conflict(struct file_lock *caller_fl,
938 struct file_lock *sys_fl)
939{
940 /* FLOCK locks referring to the same filp do not conflict with
941 * each other.
942 */
943 if (caller_fl->fl_file == sys_fl->fl_file)
944 return false;
945 if ((caller_fl->fl_type & LOCK_MAND) || (sys_fl->fl_type & LOCK_MAND))
946 return false;
947
948 return locks_conflict(caller_fl, sys_fl);
949}
950
951void
952posix_test_lock(struct file *filp, struct file_lock *fl)
953{
954 struct file_lock *cfl;
955 struct file_lock_context *ctx;
956 struct inode *inode = locks_inode(filp);
957
958 ctx = smp_load_acquire(&inode->i_flctx);
959 if (!ctx || list_empty_careful(&ctx->flc_posix)) {
960 fl->fl_type = F_UNLCK;
961 return;
962 }
963
964 spin_lock(&ctx->flc_lock);
965 list_for_each_entry(cfl, &ctx->flc_posix, fl_list) {
966 if (posix_locks_conflict(fl, cfl)) {
967 locks_copy_conflock(fl, cfl);
968 goto out;
969 }
970 }
971 fl->fl_type = F_UNLCK;
972out:
973 spin_unlock(&ctx->flc_lock);
974 return;
975}
976EXPORT_SYMBOL(posix_test_lock);
977
978/*
979 * Deadlock detection:
980 *
981 * We attempt to detect deadlocks that are due purely to posix file
982 * locks.
983 *
984 * We assume that a task can be waiting for at most one lock at a time.
985 * So for any acquired lock, the process holding that lock may be
986 * waiting on at most one other lock. That lock in turns may be held by
987 * someone waiting for at most one other lock. Given a requested lock
988 * caller_fl which is about to wait for a conflicting lock block_fl, we
989 * follow this chain of waiters to ensure we are not about to create a
990 * cycle.
991 *
992 * Since we do this before we ever put a process to sleep on a lock, we
993 * are ensured that there is never a cycle; that is what guarantees that
994 * the while() loop in posix_locks_deadlock() eventually completes.
995 *
996 * Note: the above assumption may not be true when handling lock
997 * requests from a broken NFS client. It may also fail in the presence
998 * of tasks (such as posix threads) sharing the same open file table.
999 * To handle those cases, we just bail out after a few iterations.
1000 *
1001 * For FL_OFDLCK locks, the owner is the filp, not the files_struct.
1002 * Because the owner is not even nominally tied to a thread of
1003 * execution, the deadlock detection below can't reasonably work well. Just
1004 * skip it for those.
1005 *
1006 * In principle, we could do a more limited deadlock detection on FL_OFDLCK
1007 * locks that just checks for the case where two tasks are attempting to
1008 * upgrade from read to write locks on the same inode.
1009 */
1010
1011#define MAX_DEADLK_ITERATIONS 10
1012
1013/* Find a lock that the owner of the given block_fl is blocking on. */
1014static struct file_lock *what_owner_is_waiting_for(struct file_lock *block_fl)
1015{
1016 struct file_lock *fl;
1017
1018 hash_for_each_possible(blocked_hash, fl, fl_link, posix_owner_key(block_fl)) {
1019 if (posix_same_owner(fl, block_fl)) {
1020 while (fl->fl_blocker)
1021 fl = fl->fl_blocker;
1022 return fl;
1023 }
1024 }
1025 return NULL;
1026}
1027
1028/* Must be called with the blocked_lock_lock held! */
1029static int posix_locks_deadlock(struct file_lock *caller_fl,
1030 struct file_lock *block_fl)
1031{
1032 int i = 0;
1033
1034 lockdep_assert_held(&blocked_lock_lock);
1035
1036 /*
1037 * This deadlock detector can't reasonably detect deadlocks with
1038 * FL_OFDLCK locks, since they aren't owned by a process, per-se.
1039 */
1040 if (IS_OFDLCK(caller_fl))
1041 return 0;
1042
1043 while ((block_fl = what_owner_is_waiting_for(block_fl))) {
1044 if (i++ > MAX_DEADLK_ITERATIONS)
1045 return 0;
1046 if (posix_same_owner(caller_fl, block_fl))
1047 return 1;
1048 }
1049 return 0;
1050}
1051
1052/* Try to create a FLOCK lock on filp. We always insert new FLOCK locks
1053 * after any leases, but before any posix locks.
1054 *
1055 * Note that if called with an FL_EXISTS argument, the caller may determine
1056 * whether or not a lock was successfully freed by testing the return
1057 * value for -ENOENT.
1058 */
1059static int flock_lock_inode(struct inode *inode, struct file_lock *request)
1060{
1061 struct file_lock *new_fl = NULL;
1062 struct file_lock *fl;
1063 struct file_lock_context *ctx;
1064 int error = 0;
1065 bool found = false;
1066 LIST_HEAD(dispose);
1067
1068 ctx = locks_get_lock_context(inode, request->fl_type);
1069 if (!ctx) {
1070 if (request->fl_type != F_UNLCK)
1071 return -ENOMEM;
1072 return (request->fl_flags & FL_EXISTS) ? -ENOENT : 0;
1073 }
1074
1075 if (!(request->fl_flags & FL_ACCESS) && (request->fl_type != F_UNLCK)) {
1076 new_fl = locks_alloc_lock();
1077 if (!new_fl)
1078 return -ENOMEM;
1079 }
1080
1081 percpu_down_read(&file_rwsem);
1082 spin_lock(&ctx->flc_lock);
1083 if (request->fl_flags & FL_ACCESS)
1084 goto find_conflict;
1085
1086 list_for_each_entry(fl, &ctx->flc_flock, fl_list) {
1087 if (request->fl_file != fl->fl_file)
1088 continue;
1089 if (request->fl_type == fl->fl_type)
1090 goto out;
1091 found = true;
1092 locks_delete_lock_ctx(fl, &dispose);
1093 break;
1094 }
1095
1096 if (request->fl_type == F_UNLCK) {
1097 if ((request->fl_flags & FL_EXISTS) && !found)
1098 error = -ENOENT;
1099 goto out;
1100 }
1101
1102find_conflict:
1103 list_for_each_entry(fl, &ctx->flc_flock, fl_list) {
1104 if (!flock_locks_conflict(request, fl))
1105 continue;
1106 error = -EAGAIN;
1107 if (!(request->fl_flags & FL_SLEEP))
1108 goto out;
1109 error = FILE_LOCK_DEFERRED;
1110 locks_insert_block(fl, request, flock_locks_conflict);
1111 goto out;
1112 }
1113 if (request->fl_flags & FL_ACCESS)
1114 goto out;
1115 locks_copy_lock(new_fl, request);
1116 locks_move_blocks(new_fl, request);
1117 locks_insert_lock_ctx(new_fl, &ctx->flc_flock);
1118 new_fl = NULL;
1119 error = 0;
1120
1121out:
1122 spin_unlock(&ctx->flc_lock);
1123 percpu_up_read(&file_rwsem);
1124 if (new_fl)
1125 locks_free_lock(new_fl);
1126 locks_dispose_list(&dispose);
1127 trace_flock_lock_inode(inode, request, error);
1128 return error;
1129}
1130
1131static int posix_lock_inode(struct inode *inode, struct file_lock *request,
1132 struct file_lock *conflock)
1133{
1134 struct file_lock *fl, *tmp;
1135 struct file_lock *new_fl = NULL;
1136 struct file_lock *new_fl2 = NULL;
1137 struct file_lock *left = NULL;
1138 struct file_lock *right = NULL;
1139 struct file_lock_context *ctx;
1140 int error;
1141 bool added = false;
1142 LIST_HEAD(dispose);
1143
1144 ctx = locks_get_lock_context(inode, request->fl_type);
1145 if (!ctx)
1146 return (request->fl_type == F_UNLCK) ? 0 : -ENOMEM;
1147
1148 /*
1149 * We may need two file_lock structures for this operation,
1150 * so we get them in advance to avoid races.
1151 *
1152 * In some cases we can be sure, that no new locks will be needed
1153 */
1154 if (!(request->fl_flags & FL_ACCESS) &&
1155 (request->fl_type != F_UNLCK ||
1156 request->fl_start != 0 || request->fl_end != OFFSET_MAX)) {
1157 new_fl = locks_alloc_lock();
1158 new_fl2 = locks_alloc_lock();
1159 }
1160
1161 percpu_down_read(&file_rwsem);
1162 spin_lock(&ctx->flc_lock);
1163 /*
1164 * New lock request. Walk all POSIX locks and look for conflicts. If
1165 * there are any, either return error or put the request on the
1166 * blocker's list of waiters and the global blocked_hash.
1167 */
1168 if (request->fl_type != F_UNLCK) {
1169 list_for_each_entry(fl, &ctx->flc_posix, fl_list) {
1170 if (!posix_locks_conflict(request, fl))
1171 continue;
1172 if (conflock)
1173 locks_copy_conflock(conflock, fl);
1174 error = -EAGAIN;
1175 if (!(request->fl_flags & FL_SLEEP))
1176 goto out;
1177 /*
1178 * Deadlock detection and insertion into the blocked
1179 * locks list must be done while holding the same lock!
1180 */
1181 error = -EDEADLK;
1182 spin_lock(&blocked_lock_lock);
1183 /*
1184 * Ensure that we don't find any locks blocked on this
1185 * request during deadlock detection.
1186 */
1187 __locks_wake_up_blocks(request);
1188 if (likely(!posix_locks_deadlock(request, fl))) {
1189 error = FILE_LOCK_DEFERRED;
1190 __locks_insert_block(fl, request,
1191 posix_locks_conflict);
1192 }
1193 spin_unlock(&blocked_lock_lock);
1194 goto out;
1195 }
1196 }
1197
1198 /* If we're just looking for a conflict, we're done. */
1199 error = 0;
1200 if (request->fl_flags & FL_ACCESS)
1201 goto out;
1202
1203 /* Find the first old lock with the same owner as the new lock */
1204 list_for_each_entry(fl, &ctx->flc_posix, fl_list) {
1205 if (posix_same_owner(request, fl))
1206 break;
1207 }
1208
1209 /* Process locks with this owner. */
1210 list_for_each_entry_safe_from(fl, tmp, &ctx->flc_posix, fl_list) {
1211 if (!posix_same_owner(request, fl))
1212 break;
1213
1214 /* Detect adjacent or overlapping regions (if same lock type) */
1215 if (request->fl_type == fl->fl_type) {
1216 /* In all comparisons of start vs end, use
1217 * "start - 1" rather than "end + 1". If end
1218 * is OFFSET_MAX, end + 1 will become negative.
1219 */
1220 if (fl->fl_end < request->fl_start - 1)
1221 continue;
1222 /* If the next lock in the list has entirely bigger
1223 * addresses than the new one, insert the lock here.
1224 */
1225 if (fl->fl_start - 1 > request->fl_end)
1226 break;
1227
1228 /* If we come here, the new and old lock are of the
1229 * same type and adjacent or overlapping. Make one
1230 * lock yielding from the lower start address of both
1231 * locks to the higher end address.
1232 */
1233 if (fl->fl_start > request->fl_start)
1234 fl->fl_start = request->fl_start;
1235 else
1236 request->fl_start = fl->fl_start;
1237 if (fl->fl_end < request->fl_end)
1238 fl->fl_end = request->fl_end;
1239 else
1240 request->fl_end = fl->fl_end;
1241 if (added) {
1242 locks_delete_lock_ctx(fl, &dispose);
1243 continue;
1244 }
1245 request = fl;
1246 added = true;
1247 } else {
1248 /* Processing for different lock types is a bit
1249 * more complex.
1250 */
1251 if (fl->fl_end < request->fl_start)
1252 continue;
1253 if (fl->fl_start > request->fl_end)
1254 break;
1255 if (request->fl_type == F_UNLCK)
1256 added = true;
1257 if (fl->fl_start < request->fl_start)
1258 left = fl;
1259 /* If the next lock in the list has a higher end
1260 * address than the new one, insert the new one here.
1261 */
1262 if (fl->fl_end > request->fl_end) {
1263 right = fl;
1264 break;
1265 }
1266 if (fl->fl_start >= request->fl_start) {
1267 /* The new lock completely replaces an old
1268 * one (This may happen several times).
1269 */
1270 if (added) {
1271 locks_delete_lock_ctx(fl, &dispose);
1272 continue;
1273 }
1274 /*
1275 * Replace the old lock with new_fl, and
1276 * remove the old one. It's safe to do the
1277 * insert here since we know that we won't be
1278 * using new_fl later, and that the lock is
1279 * just replacing an existing lock.
1280 */
1281 error = -ENOLCK;
1282 if (!new_fl)
1283 goto out;
1284 locks_copy_lock(new_fl, request);
1285 locks_move_blocks(new_fl, request);
1286 request = new_fl;
1287 new_fl = NULL;
1288 locks_insert_lock_ctx(request, &fl->fl_list);
1289 locks_delete_lock_ctx(fl, &dispose);
1290 added = true;
1291 }
1292 }
1293 }
1294
1295 /*
1296 * The above code only modifies existing locks in case of merging or
1297 * replacing. If new lock(s) need to be inserted all modifications are
1298 * done below this, so it's safe yet to bail out.
1299 */
1300 error = -ENOLCK; /* "no luck" */
1301 if (right && left == right && !new_fl2)
1302 goto out;
1303
1304 error = 0;
1305 if (!added) {
1306 if (request->fl_type == F_UNLCK) {
1307 if (request->fl_flags & FL_EXISTS)
1308 error = -ENOENT;
1309 goto out;
1310 }
1311
1312 if (!new_fl) {
1313 error = -ENOLCK;
1314 goto out;
1315 }
1316 locks_copy_lock(new_fl, request);
1317 locks_move_blocks(new_fl, request);
1318 locks_insert_lock_ctx(new_fl, &fl->fl_list);
1319 fl = new_fl;
1320 new_fl = NULL;
1321 }
1322 if (right) {
1323 if (left == right) {
1324 /* The new lock breaks the old one in two pieces,
1325 * so we have to use the second new lock.
1326 */
1327 left = new_fl2;
1328 new_fl2 = NULL;
1329 locks_copy_lock(left, right);
1330 locks_insert_lock_ctx(left, &fl->fl_list);
1331 }
1332 right->fl_start = request->fl_end + 1;
1333 locks_wake_up_blocks(right);
1334 }
1335 if (left) {
1336 left->fl_end = request->fl_start - 1;
1337 locks_wake_up_blocks(left);
1338 }
1339 out:
1340 spin_unlock(&ctx->flc_lock);
1341 percpu_up_read(&file_rwsem);
1342 /*
1343 * Free any unused locks.
1344 */
1345 if (new_fl)
1346 locks_free_lock(new_fl);
1347 if (new_fl2)
1348 locks_free_lock(new_fl2);
1349 locks_dispose_list(&dispose);
1350 trace_posix_lock_inode(inode, request, error);
1351
1352 return error;
1353}
1354
1355/**
1356 * posix_lock_file - Apply a POSIX-style lock to a file
1357 * @filp: The file to apply the lock to
1358 * @fl: The lock to be applied
1359 * @conflock: Place to return a copy of the conflicting lock, if found.
1360 *
1361 * Add a POSIX style lock to a file.
1362 * We merge adjacent & overlapping locks whenever possible.
1363 * POSIX locks are sorted by owner task, then by starting address
1364 *
1365 * Note that if called with an FL_EXISTS argument, the caller may determine
1366 * whether or not a lock was successfully freed by testing the return
1367 * value for -ENOENT.
1368 */
1369int posix_lock_file(struct file *filp, struct file_lock *fl,
1370 struct file_lock *conflock)
1371{
1372 return posix_lock_inode(locks_inode(filp), fl, conflock);
1373}
1374EXPORT_SYMBOL(posix_lock_file);
1375
1376/**
1377 * posix_lock_inode_wait - Apply a POSIX-style lock to a file
1378 * @inode: inode of file to which lock request should be applied
1379 * @fl: The lock to be applied
1380 *
1381 * Apply a POSIX style lock request to an inode.
1382 */
1383static int posix_lock_inode_wait(struct inode *inode, struct file_lock *fl)
1384{
1385 int error;
1386 might_sleep ();
1387 for (;;) {
1388 error = posix_lock_inode(inode, fl, NULL);
1389 if (error != FILE_LOCK_DEFERRED)
1390 break;
1391 error = wait_event_interruptible(fl->fl_wait,
1392 list_empty(&fl->fl_blocked_member));
1393 if (error)
1394 break;
1395 }
1396 locks_delete_block(fl);
1397 return error;
1398}
1399
1400#ifdef CONFIG_MANDATORY_FILE_LOCKING
1401/**
1402 * locks_mandatory_locked - Check for an active lock
1403 * @file: the file to check
1404 *
1405 * Searches the inode's list of locks to find any POSIX locks which conflict.
1406 * This function is called from locks_verify_locked() only.
1407 */
1408int locks_mandatory_locked(struct file *file)
1409{
1410 int ret;
1411 struct inode *inode = locks_inode(file);
1412 struct file_lock_context *ctx;
1413 struct file_lock *fl;
1414
1415 ctx = smp_load_acquire(&inode->i_flctx);
1416 if (!ctx || list_empty_careful(&ctx->flc_posix))
1417 return 0;
1418
1419 /*
1420 * Search the lock list for this inode for any POSIX locks.
1421 */
1422 spin_lock(&ctx->flc_lock);
1423 ret = 0;
1424 list_for_each_entry(fl, &ctx->flc_posix, fl_list) {
1425 if (fl->fl_owner != current->files &&
1426 fl->fl_owner != file) {
1427 ret = -EAGAIN;
1428 break;
1429 }
1430 }
1431 spin_unlock(&ctx->flc_lock);
1432 return ret;
1433}
1434
1435/**
1436 * locks_mandatory_area - Check for a conflicting lock
1437 * @inode: the file to check
1438 * @filp: how the file was opened (if it was)
1439 * @start: first byte in the file to check
1440 * @end: lastbyte in the file to check
1441 * @type: %F_WRLCK for a write lock, else %F_RDLCK
1442 *
1443 * Searches the inode's list of locks to find any POSIX locks which conflict.
1444 */
1445int locks_mandatory_area(struct inode *inode, struct file *filp, loff_t start,
1446 loff_t end, unsigned char type)
1447{
1448 struct file_lock fl;
1449 int error;
1450 bool sleep = false;
1451
1452 locks_init_lock(&fl);
1453 fl.fl_pid = current->tgid;
1454 fl.fl_file = filp;
1455 fl.fl_flags = FL_POSIX | FL_ACCESS;
1456 if (filp && !(filp->f_flags & O_NONBLOCK))
1457 sleep = true;
1458 fl.fl_type = type;
1459 fl.fl_start = start;
1460 fl.fl_end = end;
1461
1462 for (;;) {
1463 if (filp) {
1464 fl.fl_owner = filp;
1465 fl.fl_flags &= ~FL_SLEEP;
1466 error = posix_lock_inode(inode, &fl, NULL);
1467 if (!error)
1468 break;
1469 }
1470
1471 if (sleep)
1472 fl.fl_flags |= FL_SLEEP;
1473 fl.fl_owner = current->files;
1474 error = posix_lock_inode(inode, &fl, NULL);
1475 if (error != FILE_LOCK_DEFERRED)
1476 break;
1477 error = wait_event_interruptible(fl.fl_wait,
1478 list_empty(&fl.fl_blocked_member));
1479 if (!error) {
1480 /*
1481 * If we've been sleeping someone might have
1482 * changed the permissions behind our back.
1483 */
1484 if (__mandatory_lock(inode))
1485 continue;
1486 }
1487
1488 break;
1489 }
1490 locks_delete_block(&fl);
1491
1492 return error;
1493}
1494EXPORT_SYMBOL(locks_mandatory_area);
1495#endif /* CONFIG_MANDATORY_FILE_LOCKING */
1496
1497static void lease_clear_pending(struct file_lock *fl, int arg)
1498{
1499 switch (arg) {
1500 case F_UNLCK:
1501 fl->fl_flags &= ~FL_UNLOCK_PENDING;
1502 fallthrough;
1503 case F_RDLCK:
1504 fl->fl_flags &= ~FL_DOWNGRADE_PENDING;
1505 }
1506}
1507
1508/* We already had a lease on this file; just change its type */
1509int lease_modify(struct file_lock *fl, int arg, struct list_head *dispose)
1510{
1511 int error = assign_type(fl, arg);
1512
1513 if (error)
1514 return error;
1515 lease_clear_pending(fl, arg);
1516 locks_wake_up_blocks(fl);
1517 if (arg == F_UNLCK) {
1518 struct file *filp = fl->fl_file;
1519
1520 f_delown(filp);
1521 filp->f_owner.signum = 0;
1522 fasync_helper(0, fl->fl_file, 0, &fl->fl_fasync);
1523 if (fl->fl_fasync != NULL) {
1524 printk(KERN_ERR "locks_delete_lock: fasync == %p\n", fl->fl_fasync);
1525 fl->fl_fasync = NULL;
1526 }
1527 locks_delete_lock_ctx(fl, dispose);
1528 }
1529 return 0;
1530}
1531EXPORT_SYMBOL(lease_modify);
1532
1533static bool past_time(unsigned long then)
1534{
1535 if (!then)
1536 /* 0 is a special value meaning "this never expires": */
1537 return false;
1538 return time_after(jiffies, then);
1539}
1540
1541static void time_out_leases(struct inode *inode, struct list_head *dispose)
1542{
1543 struct file_lock_context *ctx = inode->i_flctx;
1544 struct file_lock *fl, *tmp;
1545
1546 lockdep_assert_held(&ctx->flc_lock);
1547
1548 list_for_each_entry_safe(fl, tmp, &ctx->flc_lease, fl_list) {
1549 trace_time_out_leases(inode, fl);
1550 if (past_time(fl->fl_downgrade_time))
1551 lease_modify(fl, F_RDLCK, dispose);
1552 if (past_time(fl->fl_break_time))
1553 lease_modify(fl, F_UNLCK, dispose);
1554 }
1555}
1556
1557static bool leases_conflict(struct file_lock *lease, struct file_lock *breaker)
1558{
1559 bool rc;
1560
1561 if (lease->fl_lmops->lm_breaker_owns_lease
1562 && lease->fl_lmops->lm_breaker_owns_lease(lease))
1563 return false;
1564 if ((breaker->fl_flags & FL_LAYOUT) != (lease->fl_flags & FL_LAYOUT)) {
1565 rc = false;
1566 goto trace;
1567 }
1568 if ((breaker->fl_flags & FL_DELEG) && (lease->fl_flags & FL_LEASE)) {
1569 rc = false;
1570 goto trace;
1571 }
1572
1573 rc = locks_conflict(breaker, lease);
1574trace:
1575 trace_leases_conflict(rc, lease, breaker);
1576 return rc;
1577}
1578
1579static bool
1580any_leases_conflict(struct inode *inode, struct file_lock *breaker)
1581{
1582 struct file_lock_context *ctx = inode->i_flctx;
1583 struct file_lock *fl;
1584
1585 lockdep_assert_held(&ctx->flc_lock);
1586
1587 list_for_each_entry(fl, &ctx->flc_lease, fl_list) {
1588 if (leases_conflict(fl, breaker))
1589 return true;
1590 }
1591 return false;
1592}
1593
1594/**
1595 * __break_lease - revoke all outstanding leases on file
1596 * @inode: the inode of the file to return
1597 * @mode: O_RDONLY: break only write leases; O_WRONLY or O_RDWR:
1598 * break all leases
1599 * @type: FL_LEASE: break leases and delegations; FL_DELEG: break
1600 * only delegations
1601 *
1602 * break_lease (inlined for speed) has checked there already is at least
1603 * some kind of lock (maybe a lease) on this file. Leases are broken on
1604 * a call to open() or truncate(). This function can sleep unless you
1605 * specified %O_NONBLOCK to your open().
1606 */
1607int __break_lease(struct inode *inode, unsigned int mode, unsigned int type)
1608{
1609 int error = 0;
1610 struct file_lock_context *ctx;
1611 struct file_lock *new_fl, *fl, *tmp;
1612 unsigned long break_time;
1613 int want_write = (mode & O_ACCMODE) != O_RDONLY;
1614 LIST_HEAD(dispose);
1615
1616 new_fl = lease_alloc(NULL, want_write ? F_WRLCK : F_RDLCK);
1617 if (IS_ERR(new_fl))
1618 return PTR_ERR(new_fl);
1619 new_fl->fl_flags = type;
1620
1621 /* typically we will check that ctx is non-NULL before calling */
1622 ctx = smp_load_acquire(&inode->i_flctx);
1623 if (!ctx) {
1624 WARN_ON_ONCE(1);
1625 goto free_lock;
1626 }
1627
1628 percpu_down_read(&file_rwsem);
1629 spin_lock(&ctx->flc_lock);
1630
1631 time_out_leases(inode, &dispose);
1632
1633 if (!any_leases_conflict(inode, new_fl))
1634 goto out;
1635
1636 break_time = 0;
1637 if (lease_break_time > 0) {
1638 break_time = jiffies + lease_break_time * HZ;
1639 if (break_time == 0)
1640 break_time++; /* so that 0 means no break time */
1641 }
1642
1643 list_for_each_entry_safe(fl, tmp, &ctx->flc_lease, fl_list) {
1644 if (!leases_conflict(fl, new_fl))
1645 continue;
1646 if (want_write) {
1647 if (fl->fl_flags & FL_UNLOCK_PENDING)
1648 continue;
1649 fl->fl_flags |= FL_UNLOCK_PENDING;
1650 fl->fl_break_time = break_time;
1651 } else {
1652 if (lease_breaking(fl))
1653 continue;
1654 fl->fl_flags |= FL_DOWNGRADE_PENDING;
1655 fl->fl_downgrade_time = break_time;
1656 }
1657 if (fl->fl_lmops->lm_break(fl))
1658 locks_delete_lock_ctx(fl, &dispose);
1659 }
1660
1661 if (list_empty(&ctx->flc_lease))
1662 goto out;
1663
1664 if (mode & O_NONBLOCK) {
1665 trace_break_lease_noblock(inode, new_fl);
1666 error = -EWOULDBLOCK;
1667 goto out;
1668 }
1669
1670restart:
1671 fl = list_first_entry(&ctx->flc_lease, struct file_lock, fl_list);
1672 break_time = fl->fl_break_time;
1673 if (break_time != 0)
1674 break_time -= jiffies;
1675 if (break_time == 0)
1676 break_time++;
1677 locks_insert_block(fl, new_fl, leases_conflict);
1678 trace_break_lease_block(inode, new_fl);
1679 spin_unlock(&ctx->flc_lock);
1680 percpu_up_read(&file_rwsem);
1681
1682 locks_dispose_list(&dispose);
1683 error = wait_event_interruptible_timeout(new_fl->fl_wait,
1684 list_empty(&new_fl->fl_blocked_member),
1685 break_time);
1686
1687 percpu_down_read(&file_rwsem);
1688 spin_lock(&ctx->flc_lock);
1689 trace_break_lease_unblock(inode, new_fl);
1690 locks_delete_block(new_fl);
1691 if (error >= 0) {
1692 /*
1693 * Wait for the next conflicting lease that has not been
1694 * broken yet
1695 */
1696 if (error == 0)
1697 time_out_leases(inode, &dispose);
1698 if (any_leases_conflict(inode, new_fl))
1699 goto restart;
1700 error = 0;
1701 }
1702out:
1703 spin_unlock(&ctx->flc_lock);
1704 percpu_up_read(&file_rwsem);
1705 locks_dispose_list(&dispose);
1706free_lock:
1707 locks_free_lock(new_fl);
1708 return error;
1709}
1710EXPORT_SYMBOL(__break_lease);
1711
1712/**
1713 * lease_get_mtime - update modified time of an inode with exclusive lease
1714 * @inode: the inode
1715 * @time: pointer to a timespec which contains the last modified time
1716 *
1717 * This is to force NFS clients to flush their caches for files with
1718 * exclusive leases. The justification is that if someone has an
1719 * exclusive lease, then they could be modifying it.
1720 */
1721void lease_get_mtime(struct inode *inode, struct timespec64 *time)
1722{
1723 bool has_lease = false;
1724 struct file_lock_context *ctx;
1725 struct file_lock *fl;
1726
1727 ctx = smp_load_acquire(&inode->i_flctx);
1728 if (ctx && !list_empty_careful(&ctx->flc_lease)) {
1729 spin_lock(&ctx->flc_lock);
1730 fl = list_first_entry_or_null(&ctx->flc_lease,
1731 struct file_lock, fl_list);
1732 if (fl && (fl->fl_type == F_WRLCK))
1733 has_lease = true;
1734 spin_unlock(&ctx->flc_lock);
1735 }
1736
1737 if (has_lease)
1738 *time = current_time(inode);
1739}
1740EXPORT_SYMBOL(lease_get_mtime);
1741
1742/**
1743 * fcntl_getlease - Enquire what lease is currently active
1744 * @filp: the file
1745 *
1746 * The value returned by this function will be one of
1747 * (if no lease break is pending):
1748 *
1749 * %F_RDLCK to indicate a shared lease is held.
1750 *
1751 * %F_WRLCK to indicate an exclusive lease is held.
1752 *
1753 * %F_UNLCK to indicate no lease is held.
1754 *
1755 * (if a lease break is pending):
1756 *
1757 * %F_RDLCK to indicate an exclusive lease needs to be
1758 * changed to a shared lease (or removed).
1759 *
1760 * %F_UNLCK to indicate the lease needs to be removed.
1761 *
1762 * XXX: sfr & willy disagree over whether F_INPROGRESS
1763 * should be returned to userspace.
1764 */
1765int fcntl_getlease(struct file *filp)
1766{
1767 struct file_lock *fl;
1768 struct inode *inode = locks_inode(filp);
1769 struct file_lock_context *ctx;
1770 int type = F_UNLCK;
1771 LIST_HEAD(dispose);
1772
1773 ctx = smp_load_acquire(&inode->i_flctx);
1774 if (ctx && !list_empty_careful(&ctx->flc_lease)) {
1775 percpu_down_read(&file_rwsem);
1776 spin_lock(&ctx->flc_lock);
1777 time_out_leases(inode, &dispose);
1778 list_for_each_entry(fl, &ctx->flc_lease, fl_list) {
1779 if (fl->fl_file != filp)
1780 continue;
1781 type = target_leasetype(fl);
1782 break;
1783 }
1784 spin_unlock(&ctx->flc_lock);
1785 percpu_up_read(&file_rwsem);
1786
1787 locks_dispose_list(&dispose);
1788 }
1789 return type;
1790}
1791
1792/**
1793 * check_conflicting_open - see if the given file points to an inode that has
1794 * an existing open that would conflict with the
1795 * desired lease.
1796 * @filp: file to check
1797 * @arg: type of lease that we're trying to acquire
1798 * @flags: current lock flags
1799 *
1800 * Check to see if there's an existing open fd on this file that would
1801 * conflict with the lease we're trying to set.
1802 */
1803static int
1804check_conflicting_open(struct file *filp, const long arg, int flags)
1805{
1806 struct inode *inode = locks_inode(filp);
1807 int self_wcount = 0, self_rcount = 0;
1808
1809 if (flags & FL_LAYOUT)
1810 return 0;
1811 if (flags & FL_DELEG)
1812 /* We leave these checks to the caller. */
1813 return 0;
1814
1815 if (arg == F_RDLCK)
1816 return inode_is_open_for_write(inode) ? -EAGAIN : 0;
1817 else if (arg != F_WRLCK)
1818 return 0;
1819
1820 /*
1821 * Make sure that only read/write count is from lease requestor.
1822 * Note that this will result in denying write leases when i_writecount
1823 * is negative, which is what we want. (We shouldn't grant write leases
1824 * on files open for execution.)
1825 */
1826 if (filp->f_mode & FMODE_WRITE)
1827 self_wcount = 1;
1828 else if (filp->f_mode & FMODE_READ)
1829 self_rcount = 1;
1830
1831 if (atomic_read(&inode->i_writecount) != self_wcount ||
1832 atomic_read(&inode->i_readcount) != self_rcount)
1833 return -EAGAIN;
1834
1835 return 0;
1836}
1837
1838static int
1839generic_add_lease(struct file *filp, long arg, struct file_lock **flp, void **priv)
1840{
1841 struct file_lock *fl, *my_fl = NULL, *lease;
1842 struct inode *inode = locks_inode(filp);
1843 struct file_lock_context *ctx;
1844 bool is_deleg = (*flp)->fl_flags & FL_DELEG;
1845 int error;
1846 LIST_HEAD(dispose);
1847
1848 lease = *flp;
1849 trace_generic_add_lease(inode, lease);
1850
1851 /* Note that arg is never F_UNLCK here */
1852 ctx = locks_get_lock_context(inode, arg);
1853 if (!ctx)
1854 return -ENOMEM;
1855
1856 /*
1857 * In the delegation case we need mutual exclusion with
1858 * a number of operations that take the i_mutex. We trylock
1859 * because delegations are an optional optimization, and if
1860 * there's some chance of a conflict--we'd rather not
1861 * bother, maybe that's a sign this just isn't a good file to
1862 * hand out a delegation on.
1863 */
1864 if (is_deleg && !inode_trylock(inode))
1865 return -EAGAIN;
1866
1867 if (is_deleg && arg == F_WRLCK) {
1868 /* Write delegations are not currently supported: */
1869 inode_unlock(inode);
1870 WARN_ON_ONCE(1);
1871 return -EINVAL;
1872 }
1873
1874 percpu_down_read(&file_rwsem);
1875 spin_lock(&ctx->flc_lock);
1876 time_out_leases(inode, &dispose);
1877 error = check_conflicting_open(filp, arg, lease->fl_flags);
1878 if (error)
1879 goto out;
1880
1881 /*
1882 * At this point, we know that if there is an exclusive
1883 * lease on this file, then we hold it on this filp
1884 * (otherwise our open of this file would have blocked).
1885 * And if we are trying to acquire an exclusive lease,
1886 * then the file is not open by anyone (including us)
1887 * except for this filp.
1888 */
1889 error = -EAGAIN;
1890 list_for_each_entry(fl, &ctx->flc_lease, fl_list) {
1891 if (fl->fl_file == filp &&
1892 fl->fl_owner == lease->fl_owner) {
1893 my_fl = fl;
1894 continue;
1895 }
1896
1897 /*
1898 * No exclusive leases if someone else has a lease on
1899 * this file:
1900 */
1901 if (arg == F_WRLCK)
1902 goto out;
1903 /*
1904 * Modifying our existing lease is OK, but no getting a
1905 * new lease if someone else is opening for write:
1906 */
1907 if (fl->fl_flags & FL_UNLOCK_PENDING)
1908 goto out;
1909 }
1910
1911 if (my_fl != NULL) {
1912 lease = my_fl;
1913 error = lease->fl_lmops->lm_change(lease, arg, &dispose);
1914 if (error)
1915 goto out;
1916 goto out_setup;
1917 }
1918
1919 error = -EINVAL;
1920 if (!leases_enable)
1921 goto out;
1922
1923 locks_insert_lock_ctx(lease, &ctx->flc_lease);
1924 /*
1925 * The check in break_lease() is lockless. It's possible for another
1926 * open to race in after we did the earlier check for a conflicting
1927 * open but before the lease was inserted. Check again for a
1928 * conflicting open and cancel the lease if there is one.
1929 *
1930 * We also add a barrier here to ensure that the insertion of the lock
1931 * precedes these checks.
1932 */
1933 smp_mb();
1934 error = check_conflicting_open(filp, arg, lease->fl_flags);
1935 if (error) {
1936 locks_unlink_lock_ctx(lease);
1937 goto out;
1938 }
1939
1940out_setup:
1941 if (lease->fl_lmops->lm_setup)
1942 lease->fl_lmops->lm_setup(lease, priv);
1943out:
1944 spin_unlock(&ctx->flc_lock);
1945 percpu_up_read(&file_rwsem);
1946 locks_dispose_list(&dispose);
1947 if (is_deleg)
1948 inode_unlock(inode);
1949 if (!error && !my_fl)
1950 *flp = NULL;
1951 return error;
1952}
1953
1954static int generic_delete_lease(struct file *filp, void *owner)
1955{
1956 int error = -EAGAIN;
1957 struct file_lock *fl, *victim = NULL;
1958 struct inode *inode = locks_inode(filp);
1959 struct file_lock_context *ctx;
1960 LIST_HEAD(dispose);
1961
1962 ctx = smp_load_acquire(&inode->i_flctx);
1963 if (!ctx) {
1964 trace_generic_delete_lease(inode, NULL);
1965 return error;
1966 }
1967
1968 percpu_down_read(&file_rwsem);
1969 spin_lock(&ctx->flc_lock);
1970 list_for_each_entry(fl, &ctx->flc_lease, fl_list) {
1971 if (fl->fl_file == filp &&
1972 fl->fl_owner == owner) {
1973 victim = fl;
1974 break;
1975 }
1976 }
1977 trace_generic_delete_lease(inode, victim);
1978 if (victim)
1979 error = fl->fl_lmops->lm_change(victim, F_UNLCK, &dispose);
1980 spin_unlock(&ctx->flc_lock);
1981 percpu_up_read(&file_rwsem);
1982 locks_dispose_list(&dispose);
1983 return error;
1984}
1985
1986/**
1987 * generic_setlease - sets a lease on an open file
1988 * @filp: file pointer
1989 * @arg: type of lease to obtain
1990 * @flp: input - file_lock to use, output - file_lock inserted
1991 * @priv: private data for lm_setup (may be NULL if lm_setup
1992 * doesn't require it)
1993 *
1994 * The (input) flp->fl_lmops->lm_break function is required
1995 * by break_lease().
1996 */
1997int generic_setlease(struct file *filp, long arg, struct file_lock **flp,
1998 void **priv)
1999{
2000 struct inode *inode = locks_inode(filp);
2001 int error;
2002
2003 if ((!uid_eq(current_fsuid(), inode->i_uid)) && !capable(CAP_LEASE))
2004 return -EACCES;
2005 if (!S_ISREG(inode->i_mode))
2006 return -EINVAL;
2007 error = security_file_lock(filp, arg);
2008 if (error)
2009 return error;
2010
2011 switch (arg) {
2012 case F_UNLCK:
2013 return generic_delete_lease(filp, *priv);
2014 case F_RDLCK:
2015 case F_WRLCK:
2016 if (!(*flp)->fl_lmops->lm_break) {
2017 WARN_ON_ONCE(1);
2018 return -ENOLCK;
2019 }
2020
2021 return generic_add_lease(filp, arg, flp, priv);
2022 default:
2023 return -EINVAL;
2024 }
2025}
2026EXPORT_SYMBOL(generic_setlease);
2027
2028#if IS_ENABLED(CONFIG_SRCU)
2029/*
2030 * Kernel subsystems can register to be notified on any attempt to set
2031 * a new lease with the lease_notifier_chain. This is used by (e.g.) nfsd
2032 * to close files that it may have cached when there is an attempt to set a
2033 * conflicting lease.
2034 */
2035static struct srcu_notifier_head lease_notifier_chain;
2036
2037static inline void
2038lease_notifier_chain_init(void)
2039{
2040 srcu_init_notifier_head(&lease_notifier_chain);
2041}
2042
2043static inline void
2044setlease_notifier(long arg, struct file_lock *lease)
2045{
2046 if (arg != F_UNLCK)
2047 srcu_notifier_call_chain(&lease_notifier_chain, arg, lease);
2048}
2049
2050int lease_register_notifier(struct notifier_block *nb)
2051{
2052 return srcu_notifier_chain_register(&lease_notifier_chain, nb);
2053}
2054EXPORT_SYMBOL_GPL(lease_register_notifier);
2055
2056void lease_unregister_notifier(struct notifier_block *nb)
2057{
2058 srcu_notifier_chain_unregister(&lease_notifier_chain, nb);
2059}
2060EXPORT_SYMBOL_GPL(lease_unregister_notifier);
2061
2062#else /* !IS_ENABLED(CONFIG_SRCU) */
2063static inline void
2064lease_notifier_chain_init(void)
2065{
2066}
2067
2068static inline void
2069setlease_notifier(long arg, struct file_lock *lease)
2070{
2071}
2072
2073int lease_register_notifier(struct notifier_block *nb)
2074{
2075 return 0;
2076}
2077EXPORT_SYMBOL_GPL(lease_register_notifier);
2078
2079void lease_unregister_notifier(struct notifier_block *nb)
2080{
2081}
2082EXPORT_SYMBOL_GPL(lease_unregister_notifier);
2083
2084#endif /* IS_ENABLED(CONFIG_SRCU) */
2085
2086/**
2087 * vfs_setlease - sets a lease on an open file
2088 * @filp: file pointer
2089 * @arg: type of lease to obtain
2090 * @lease: file_lock to use when adding a lease
2091 * @priv: private info for lm_setup when adding a lease (may be
2092 * NULL if lm_setup doesn't require it)
2093 *
2094 * Call this to establish a lease on the file. The "lease" argument is not
2095 * used for F_UNLCK requests and may be NULL. For commands that set or alter
2096 * an existing lease, the ``(*lease)->fl_lmops->lm_break`` operation must be
2097 * set; if not, this function will return -ENOLCK (and generate a scary-looking
2098 * stack trace).
2099 *
2100 * The "priv" pointer is passed directly to the lm_setup function as-is. It
2101 * may be NULL if the lm_setup operation doesn't require it.
2102 */
2103int
2104vfs_setlease(struct file *filp, long arg, struct file_lock **lease, void **priv)
2105{
2106 if (lease)
2107 setlease_notifier(arg, *lease);
2108 if (filp->f_op->setlease)
2109 return filp->f_op->setlease(filp, arg, lease, priv);
2110 else
2111 return generic_setlease(filp, arg, lease, priv);
2112}
2113EXPORT_SYMBOL_GPL(vfs_setlease);
2114
2115static int do_fcntl_add_lease(unsigned int fd, struct file *filp, long arg)
2116{
2117 struct file_lock *fl;
2118 struct fasync_struct *new;
2119 int error;
2120
2121 fl = lease_alloc(filp, arg);
2122 if (IS_ERR(fl))
2123 return PTR_ERR(fl);
2124
2125 new = fasync_alloc();
2126 if (!new) {
2127 locks_free_lock(fl);
2128 return -ENOMEM;
2129 }
2130 new->fa_fd = fd;
2131
2132 error = vfs_setlease(filp, arg, &fl, (void **)&new);
2133 if (fl)
2134 locks_free_lock(fl);
2135 if (new)
2136 fasync_free(new);
2137 return error;
2138}
2139
2140/**
2141 * fcntl_setlease - sets a lease on an open file
2142 * @fd: open file descriptor
2143 * @filp: file pointer
2144 * @arg: type of lease to obtain
2145 *
2146 * Call this fcntl to establish a lease on the file.
2147 * Note that you also need to call %F_SETSIG to
2148 * receive a signal when the lease is broken.
2149 */
2150int fcntl_setlease(unsigned int fd, struct file *filp, long arg)
2151{
2152 if (arg == F_UNLCK)
2153 return vfs_setlease(filp, F_UNLCK, NULL, (void **)&filp);
2154 return do_fcntl_add_lease(fd, filp, arg);
2155}
2156
2157/**
2158 * flock_lock_inode_wait - Apply a FLOCK-style lock to a file
2159 * @inode: inode of the file to apply to
2160 * @fl: The lock to be applied
2161 *
2162 * Apply a FLOCK style lock request to an inode.
2163 */
2164static int flock_lock_inode_wait(struct inode *inode, struct file_lock *fl)
2165{
2166 int error;
2167 might_sleep();
2168 for (;;) {
2169 error = flock_lock_inode(inode, fl);
2170 if (error != FILE_LOCK_DEFERRED)
2171 break;
2172 error = wait_event_interruptible(fl->fl_wait,
2173 list_empty(&fl->fl_blocked_member));
2174 if (error)
2175 break;
2176 }
2177 locks_delete_block(fl);
2178 return error;
2179}
2180
2181/**
2182 * locks_lock_inode_wait - Apply a lock to an inode
2183 * @inode: inode of the file to apply to
2184 * @fl: The lock to be applied
2185 *
2186 * Apply a POSIX or FLOCK style lock request to an inode.
2187 */
2188int locks_lock_inode_wait(struct inode *inode, struct file_lock *fl)
2189{
2190 int res = 0;
2191 switch (fl->fl_flags & (FL_POSIX|FL_FLOCK)) {
2192 case FL_POSIX:
2193 res = posix_lock_inode_wait(inode, fl);
2194 break;
2195 case FL_FLOCK:
2196 res = flock_lock_inode_wait(inode, fl);
2197 break;
2198 default:
2199 BUG();
2200 }
2201 return res;
2202}
2203EXPORT_SYMBOL(locks_lock_inode_wait);
2204
2205/**
2206 * sys_flock: - flock() system call.
2207 * @fd: the file descriptor to lock.
2208 * @cmd: the type of lock to apply.
2209 *
2210 * Apply a %FL_FLOCK style lock to an open file descriptor.
2211 * The @cmd can be one of:
2212 *
2213 * - %LOCK_SH -- a shared lock.
2214 * - %LOCK_EX -- an exclusive lock.
2215 * - %LOCK_UN -- remove an existing lock.
2216 * - %LOCK_MAND -- a 'mandatory' flock.
2217 * This exists to emulate Windows Share Modes.
2218 *
2219 * %LOCK_MAND can be combined with %LOCK_READ or %LOCK_WRITE to allow other
2220 * processes read and write access respectively.
2221 */
2222SYSCALL_DEFINE2(flock, unsigned int, fd, unsigned int, cmd)
2223{
2224 struct fd f = fdget(fd);
2225 struct file_lock *lock;
2226 int can_sleep, unlock;
2227 int error;
2228
2229 error = -EBADF;
2230 if (!f.file)
2231 goto out;
2232
2233 can_sleep = !(cmd & LOCK_NB);
2234 cmd &= ~LOCK_NB;
2235 unlock = (cmd == LOCK_UN);
2236
2237 if (!unlock && !(cmd & LOCK_MAND) &&
2238 !(f.file->f_mode & (FMODE_READ|FMODE_WRITE)))
2239 goto out_putf;
2240
2241 lock = flock_make_lock(f.file, cmd, NULL);
2242 if (IS_ERR(lock)) {
2243 error = PTR_ERR(lock);
2244 goto out_putf;
2245 }
2246
2247 if (can_sleep)
2248 lock->fl_flags |= FL_SLEEP;
2249
2250 error = security_file_lock(f.file, lock->fl_type);
2251 if (error)
2252 goto out_free;
2253
2254 if (f.file->f_op->flock)
2255 error = f.file->f_op->flock(f.file,
2256 (can_sleep) ? F_SETLKW : F_SETLK,
2257 lock);
2258 else
2259 error = locks_lock_file_wait(f.file, lock);
2260
2261 out_free:
2262 locks_free_lock(lock);
2263
2264 out_putf:
2265 fdput(f);
2266 out:
2267 return error;
2268}
2269
2270/**
2271 * vfs_test_lock - test file byte range lock
2272 * @filp: The file to test lock for
2273 * @fl: The lock to test; also used to hold result
2274 *
2275 * Returns -ERRNO on failure. Indicates presence of conflicting lock by
2276 * setting conf->fl_type to something other than F_UNLCK.
2277 */
2278int vfs_test_lock(struct file *filp, struct file_lock *fl)
2279{
2280 if (filp->f_op->lock)
2281 return filp->f_op->lock(filp, F_GETLK, fl);
2282 posix_test_lock(filp, fl);
2283 return 0;
2284}
2285EXPORT_SYMBOL_GPL(vfs_test_lock);
2286
2287/**
2288 * locks_translate_pid - translate a file_lock's fl_pid number into a namespace
2289 * @fl: The file_lock who's fl_pid should be translated
2290 * @ns: The namespace into which the pid should be translated
2291 *
2292 * Used to tranlate a fl_pid into a namespace virtual pid number
2293 */
2294static pid_t locks_translate_pid(struct file_lock *fl, struct pid_namespace *ns)
2295{
2296 pid_t vnr;
2297 struct pid *pid;
2298
2299 if (IS_OFDLCK(fl))
2300 return -1;
2301 if (IS_REMOTELCK(fl))
2302 return fl->fl_pid;
2303 /*
2304 * If the flock owner process is dead and its pid has been already
2305 * freed, the translation below won't work, but we still want to show
2306 * flock owner pid number in init pidns.
2307 */
2308 if (ns == &init_pid_ns)
2309 return (pid_t)fl->fl_pid;
2310
2311 rcu_read_lock();
2312 pid = find_pid_ns(fl->fl_pid, &init_pid_ns);
2313 vnr = pid_nr_ns(pid, ns);
2314 rcu_read_unlock();
2315 return vnr;
2316}
2317
2318static int posix_lock_to_flock(struct flock *flock, struct file_lock *fl)
2319{
2320 flock->l_pid = locks_translate_pid(fl, task_active_pid_ns(current));
2321#if BITS_PER_LONG == 32
2322 /*
2323 * Make sure we can represent the posix lock via
2324 * legacy 32bit flock.
2325 */
2326 if (fl->fl_start > OFFT_OFFSET_MAX)
2327 return -EOVERFLOW;
2328 if (fl->fl_end != OFFSET_MAX && fl->fl_end > OFFT_OFFSET_MAX)
2329 return -EOVERFLOW;
2330#endif
2331 flock->l_start = fl->fl_start;
2332 flock->l_len = fl->fl_end == OFFSET_MAX ? 0 :
2333 fl->fl_end - fl->fl_start + 1;
2334 flock->l_whence = 0;
2335 flock->l_type = fl->fl_type;
2336 return 0;
2337}
2338
2339#if BITS_PER_LONG == 32
2340static void posix_lock_to_flock64(struct flock64 *flock, struct file_lock *fl)
2341{
2342 flock->l_pid = locks_translate_pid(fl, task_active_pid_ns(current));
2343 flock->l_start = fl->fl_start;
2344 flock->l_len = fl->fl_end == OFFSET_MAX ? 0 :
2345 fl->fl_end - fl->fl_start + 1;
2346 flock->l_whence = 0;
2347 flock->l_type = fl->fl_type;
2348}
2349#endif
2350
2351/* Report the first existing lock that would conflict with l.
2352 * This implements the F_GETLK command of fcntl().
2353 */
2354int fcntl_getlk(struct file *filp, unsigned int cmd, struct flock *flock)
2355{
2356 struct file_lock *fl;
2357 int error;
2358
2359 fl = locks_alloc_lock();
2360 if (fl == NULL)
2361 return -ENOMEM;
2362 error = -EINVAL;
2363 if (flock->l_type != F_RDLCK && flock->l_type != F_WRLCK)
2364 goto out;
2365
2366 error = flock_to_posix_lock(filp, fl, flock);
2367 if (error)
2368 goto out;
2369
2370 if (cmd == F_OFD_GETLK) {
2371 error = -EINVAL;
2372 if (flock->l_pid != 0)
2373 goto out;
2374
2375 cmd = F_GETLK;
2376 fl->fl_flags |= FL_OFDLCK;
2377 fl->fl_owner = filp;
2378 }
2379
2380 error = vfs_test_lock(filp, fl);
2381 if (error)
2382 goto out;
2383
2384 flock->l_type = fl->fl_type;
2385 if (fl->fl_type != F_UNLCK) {
2386 error = posix_lock_to_flock(flock, fl);
2387 if (error)
2388 goto out;
2389 }
2390out:
2391 locks_free_lock(fl);
2392 return error;
2393}
2394
2395/**
2396 * vfs_lock_file - file byte range lock
2397 * @filp: The file to apply the lock to
2398 * @cmd: type of locking operation (F_SETLK, F_GETLK, etc.)
2399 * @fl: The lock to be applied
2400 * @conf: Place to return a copy of the conflicting lock, if found.
2401 *
2402 * A caller that doesn't care about the conflicting lock may pass NULL
2403 * as the final argument.
2404 *
2405 * If the filesystem defines a private ->lock() method, then @conf will
2406 * be left unchanged; so a caller that cares should initialize it to
2407 * some acceptable default.
2408 *
2409 * To avoid blocking kernel daemons, such as lockd, that need to acquire POSIX
2410 * locks, the ->lock() interface may return asynchronously, before the lock has
2411 * been granted or denied by the underlying filesystem, if (and only if)
2412 * lm_grant is set. Callers expecting ->lock() to return asynchronously
2413 * will only use F_SETLK, not F_SETLKW; they will set FL_SLEEP if (and only if)
2414 * the request is for a blocking lock. When ->lock() does return asynchronously,
2415 * it must return FILE_LOCK_DEFERRED, and call ->lm_grant() when the lock
2416 * request completes.
2417 * If the request is for non-blocking lock the file system should return
2418 * FILE_LOCK_DEFERRED then try to get the lock and call the callback routine
2419 * with the result. If the request timed out the callback routine will return a
2420 * nonzero return code and the file system should release the lock. The file
2421 * system is also responsible to keep a corresponding posix lock when it
2422 * grants a lock so the VFS can find out which locks are locally held and do
2423 * the correct lock cleanup when required.
2424 * The underlying filesystem must not drop the kernel lock or call
2425 * ->lm_grant() before returning to the caller with a FILE_LOCK_DEFERRED
2426 * return code.
2427 */
2428int vfs_lock_file(struct file *filp, unsigned int cmd, struct file_lock *fl, struct file_lock *conf)
2429{
2430 if (filp->f_op->lock)
2431 return filp->f_op->lock(filp, cmd, fl);
2432 else
2433 return posix_lock_file(filp, fl, conf);
2434}
2435EXPORT_SYMBOL_GPL(vfs_lock_file);
2436
2437static int do_lock_file_wait(struct file *filp, unsigned int cmd,
2438 struct file_lock *fl)
2439{
2440 int error;
2441
2442 error = security_file_lock(filp, fl->fl_type);
2443 if (error)
2444 return error;
2445
2446 for (;;) {
2447 error = vfs_lock_file(filp, cmd, fl, NULL);
2448 if (error != FILE_LOCK_DEFERRED)
2449 break;
2450 error = wait_event_interruptible(fl->fl_wait,
2451 list_empty(&fl->fl_blocked_member));
2452 if (error)
2453 break;
2454 }
2455 locks_delete_block(fl);
2456
2457 return error;
2458}
2459
2460/* Ensure that fl->fl_file has compatible f_mode for F_SETLK calls */
2461static int
2462check_fmode_for_setlk(struct file_lock *fl)
2463{
2464 switch (fl->fl_type) {
2465 case F_RDLCK:
2466 if (!(fl->fl_file->f_mode & FMODE_READ))
2467 return -EBADF;
2468 break;
2469 case F_WRLCK:
2470 if (!(fl->fl_file->f_mode & FMODE_WRITE))
2471 return -EBADF;
2472 }
2473 return 0;
2474}
2475
2476/* Apply the lock described by l to an open file descriptor.
2477 * This implements both the F_SETLK and F_SETLKW commands of fcntl().
2478 */
2479int fcntl_setlk(unsigned int fd, struct file *filp, unsigned int cmd,
2480 struct flock *flock)
2481{
2482 struct file_lock *file_lock = locks_alloc_lock();
2483 struct inode *inode = locks_inode(filp);
2484 struct file *f;
2485 int error;
2486
2487 if (file_lock == NULL)
2488 return -ENOLCK;
2489
2490 /* Don't allow mandatory locks on files that may be memory mapped
2491 * and shared.
2492 */
2493 if (mandatory_lock(inode) && mapping_writably_mapped(filp->f_mapping)) {
2494 error = -EAGAIN;
2495 goto out;
2496 }
2497
2498 error = flock_to_posix_lock(filp, file_lock, flock);
2499 if (error)
2500 goto out;
2501
2502 error = check_fmode_for_setlk(file_lock);
2503 if (error)
2504 goto out;
2505
2506 /*
2507 * If the cmd is requesting file-private locks, then set the
2508 * FL_OFDLCK flag and override the owner.
2509 */
2510 switch (cmd) {
2511 case F_OFD_SETLK:
2512 error = -EINVAL;
2513 if (flock->l_pid != 0)
2514 goto out;
2515
2516 cmd = F_SETLK;
2517 file_lock->fl_flags |= FL_OFDLCK;
2518 file_lock->fl_owner = filp;
2519 break;
2520 case F_OFD_SETLKW:
2521 error = -EINVAL;
2522 if (flock->l_pid != 0)
2523 goto out;
2524
2525 cmd = F_SETLKW;
2526 file_lock->fl_flags |= FL_OFDLCK;
2527 file_lock->fl_owner = filp;
2528 fallthrough;
2529 case F_SETLKW:
2530 file_lock->fl_flags |= FL_SLEEP;
2531 }
2532
2533 error = do_lock_file_wait(filp, cmd, file_lock);
2534
2535 /*
2536 * Attempt to detect a close/fcntl race and recover by releasing the
2537 * lock that was just acquired. There is no need to do that when we're
2538 * unlocking though, or for OFD locks.
2539 */
2540 if (!error && file_lock->fl_type != F_UNLCK &&
2541 !(file_lock->fl_flags & FL_OFDLCK)) {
2542 /*
2543 * We need that spin_lock here - it prevents reordering between
2544 * update of i_flctx->flc_posix and check for it done in
2545 * close(). rcu_read_lock() wouldn't do.
2546 */
2547 spin_lock(¤t->files->file_lock);
2548 f = fcheck(fd);
2549 spin_unlock(¤t->files->file_lock);
2550 if (f != filp) {
2551 file_lock->fl_type = F_UNLCK;
2552 error = do_lock_file_wait(filp, cmd, file_lock);
2553 WARN_ON_ONCE(error);
2554 error = -EBADF;
2555 }
2556 }
2557out:
2558 trace_fcntl_setlk(inode, file_lock, error);
2559 locks_free_lock(file_lock);
2560 return error;
2561}
2562
2563#if BITS_PER_LONG == 32
2564/* Report the first existing lock that would conflict with l.
2565 * This implements the F_GETLK command of fcntl().
2566 */
2567int fcntl_getlk64(struct file *filp, unsigned int cmd, struct flock64 *flock)
2568{
2569 struct file_lock *fl;
2570 int error;
2571
2572 fl = locks_alloc_lock();
2573 if (fl == NULL)
2574 return -ENOMEM;
2575
2576 error = -EINVAL;
2577 if (flock->l_type != F_RDLCK && flock->l_type != F_WRLCK)
2578 goto out;
2579
2580 error = flock64_to_posix_lock(filp, fl, flock);
2581 if (error)
2582 goto out;
2583
2584 if (cmd == F_OFD_GETLK) {
2585 error = -EINVAL;
2586 if (flock->l_pid != 0)
2587 goto out;
2588
2589 cmd = F_GETLK64;
2590 fl->fl_flags |= FL_OFDLCK;
2591 fl->fl_owner = filp;
2592 }
2593
2594 error = vfs_test_lock(filp, fl);
2595 if (error)
2596 goto out;
2597
2598 flock->l_type = fl->fl_type;
2599 if (fl->fl_type != F_UNLCK)
2600 posix_lock_to_flock64(flock, fl);
2601
2602out:
2603 locks_free_lock(fl);
2604 return error;
2605}
2606
2607/* Apply the lock described by l to an open file descriptor.
2608 * This implements both the F_SETLK and F_SETLKW commands of fcntl().
2609 */
2610int fcntl_setlk64(unsigned int fd, struct file *filp, unsigned int cmd,
2611 struct flock64 *flock)
2612{
2613 struct file_lock *file_lock = locks_alloc_lock();
2614 struct inode *inode = locks_inode(filp);
2615 struct file *f;
2616 int error;
2617
2618 if (file_lock == NULL)
2619 return -ENOLCK;
2620
2621 /* Don't allow mandatory locks on files that may be memory mapped
2622 * and shared.
2623 */
2624 if (mandatory_lock(inode) && mapping_writably_mapped(filp->f_mapping)) {
2625 error = -EAGAIN;
2626 goto out;
2627 }
2628
2629 error = flock64_to_posix_lock(filp, file_lock, flock);
2630 if (error)
2631 goto out;
2632
2633 error = check_fmode_for_setlk(file_lock);
2634 if (error)
2635 goto out;
2636
2637 /*
2638 * If the cmd is requesting file-private locks, then set the
2639 * FL_OFDLCK flag and override the owner.
2640 */
2641 switch (cmd) {
2642 case F_OFD_SETLK:
2643 error = -EINVAL;
2644 if (flock->l_pid != 0)
2645 goto out;
2646
2647 cmd = F_SETLK64;
2648 file_lock->fl_flags |= FL_OFDLCK;
2649 file_lock->fl_owner = filp;
2650 break;
2651 case F_OFD_SETLKW:
2652 error = -EINVAL;
2653 if (flock->l_pid != 0)
2654 goto out;
2655
2656 cmd = F_SETLKW64;
2657 file_lock->fl_flags |= FL_OFDLCK;
2658 file_lock->fl_owner = filp;
2659 fallthrough;
2660 case F_SETLKW64:
2661 file_lock->fl_flags |= FL_SLEEP;
2662 }
2663
2664 error = do_lock_file_wait(filp, cmd, file_lock);
2665
2666 /*
2667 * Attempt to detect a close/fcntl race and recover by releasing the
2668 * lock that was just acquired. There is no need to do that when we're
2669 * unlocking though, or for OFD locks.
2670 */
2671 if (!error && file_lock->fl_type != F_UNLCK &&
2672 !(file_lock->fl_flags & FL_OFDLCK)) {
2673 /*
2674 * We need that spin_lock here - it prevents reordering between
2675 * update of i_flctx->flc_posix and check for it done in
2676 * close(). rcu_read_lock() wouldn't do.
2677 */
2678 spin_lock(¤t->files->file_lock);
2679 f = fcheck(fd);
2680 spin_unlock(¤t->files->file_lock);
2681 if (f != filp) {
2682 file_lock->fl_type = F_UNLCK;
2683 error = do_lock_file_wait(filp, cmd, file_lock);
2684 WARN_ON_ONCE(error);
2685 error = -EBADF;
2686 }
2687 }
2688out:
2689 locks_free_lock(file_lock);
2690 return error;
2691}
2692#endif /* BITS_PER_LONG == 32 */
2693
2694/*
2695 * This function is called when the file is being removed
2696 * from the task's fd array. POSIX locks belonging to this task
2697 * are deleted at this time.
2698 */
2699void locks_remove_posix(struct file *filp, fl_owner_t owner)
2700{
2701 int error;
2702 struct inode *inode = locks_inode(filp);
2703 struct file_lock lock;
2704 struct file_lock_context *ctx;
2705
2706 /*
2707 * If there are no locks held on this file, we don't need to call
2708 * posix_lock_file(). Another process could be setting a lock on this
2709 * file at the same time, but we wouldn't remove that lock anyway.
2710 */
2711 ctx = smp_load_acquire(&inode->i_flctx);
2712 if (!ctx || list_empty(&ctx->flc_posix))
2713 return;
2714
2715 locks_init_lock(&lock);
2716 lock.fl_type = F_UNLCK;
2717 lock.fl_flags = FL_POSIX | FL_CLOSE;
2718 lock.fl_start = 0;
2719 lock.fl_end = OFFSET_MAX;
2720 lock.fl_owner = owner;
2721 lock.fl_pid = current->tgid;
2722 lock.fl_file = filp;
2723 lock.fl_ops = NULL;
2724 lock.fl_lmops = NULL;
2725
2726 error = vfs_lock_file(filp, F_SETLK, &lock, NULL);
2727
2728 if (lock.fl_ops && lock.fl_ops->fl_release_private)
2729 lock.fl_ops->fl_release_private(&lock);
2730 trace_locks_remove_posix(inode, &lock, error);
2731}
2732EXPORT_SYMBOL(locks_remove_posix);
2733
2734/* The i_flctx must be valid when calling into here */
2735static void
2736locks_remove_flock(struct file *filp, struct file_lock_context *flctx)
2737{
2738 struct file_lock fl;
2739 struct inode *inode = locks_inode(filp);
2740
2741 if (list_empty(&flctx->flc_flock))
2742 return;
2743
2744 flock_make_lock(filp, LOCK_UN, &fl);
2745 fl.fl_flags |= FL_CLOSE;
2746
2747 if (filp->f_op->flock)
2748 filp->f_op->flock(filp, F_SETLKW, &fl);
2749 else
2750 flock_lock_inode(inode, &fl);
2751
2752 if (fl.fl_ops && fl.fl_ops->fl_release_private)
2753 fl.fl_ops->fl_release_private(&fl);
2754}
2755
2756/* The i_flctx must be valid when calling into here */
2757static void
2758locks_remove_lease(struct file *filp, struct file_lock_context *ctx)
2759{
2760 struct file_lock *fl, *tmp;
2761 LIST_HEAD(dispose);
2762
2763 if (list_empty(&ctx->flc_lease))
2764 return;
2765
2766 percpu_down_read(&file_rwsem);
2767 spin_lock(&ctx->flc_lock);
2768 list_for_each_entry_safe(fl, tmp, &ctx->flc_lease, fl_list)
2769 if (filp == fl->fl_file)
2770 lease_modify(fl, F_UNLCK, &dispose);
2771 spin_unlock(&ctx->flc_lock);
2772 percpu_up_read(&file_rwsem);
2773
2774 locks_dispose_list(&dispose);
2775}
2776
2777/*
2778 * This function is called on the last close of an open file.
2779 */
2780void locks_remove_file(struct file *filp)
2781{
2782 struct file_lock_context *ctx;
2783
2784 ctx = smp_load_acquire(&locks_inode(filp)->i_flctx);
2785 if (!ctx)
2786 return;
2787
2788 /* remove any OFD locks */
2789 locks_remove_posix(filp, filp);
2790
2791 /* remove flock locks */
2792 locks_remove_flock(filp, ctx);
2793
2794 /* remove any leases */
2795 locks_remove_lease(filp, ctx);
2796
2797 spin_lock(&ctx->flc_lock);
2798 locks_check_ctx_file_list(filp, &ctx->flc_posix, "POSIX");
2799 locks_check_ctx_file_list(filp, &ctx->flc_flock, "FLOCK");
2800 locks_check_ctx_file_list(filp, &ctx->flc_lease, "LEASE");
2801 spin_unlock(&ctx->flc_lock);
2802}
2803
2804/**
2805 * vfs_cancel_lock - file byte range unblock lock
2806 * @filp: The file to apply the unblock to
2807 * @fl: The lock to be unblocked
2808 *
2809 * Used by lock managers to cancel blocked requests
2810 */
2811int vfs_cancel_lock(struct file *filp, struct file_lock *fl)
2812{
2813 if (filp->f_op->lock)
2814 return filp->f_op->lock(filp, F_CANCELLK, fl);
2815 return 0;
2816}
2817EXPORT_SYMBOL_GPL(vfs_cancel_lock);
2818
2819#ifdef CONFIG_PROC_FS
2820#include <linux/proc_fs.h>
2821#include <linux/seq_file.h>
2822
2823struct locks_iterator {
2824 int li_cpu;
2825 loff_t li_pos;
2826};
2827
2828static void lock_get_status(struct seq_file *f, struct file_lock *fl,
2829 loff_t id, char *pfx)
2830{
2831 struct inode *inode = NULL;
2832 unsigned int fl_pid;
2833 struct pid_namespace *proc_pidns = proc_pid_ns(file_inode(f->file)->i_sb);
2834
2835 fl_pid = locks_translate_pid(fl, proc_pidns);
2836 /*
2837 * If lock owner is dead (and pid is freed) or not visible in current
2838 * pidns, zero is shown as a pid value. Check lock info from
2839 * init_pid_ns to get saved lock pid value.
2840 */
2841
2842 if (fl->fl_file != NULL)
2843 inode = locks_inode(fl->fl_file);
2844
2845 seq_printf(f, "%lld:%s ", id, pfx);
2846 if (IS_POSIX(fl)) {
2847 if (fl->fl_flags & FL_ACCESS)
2848 seq_puts(f, "ACCESS");
2849 else if (IS_OFDLCK(fl))
2850 seq_puts(f, "OFDLCK");
2851 else
2852 seq_puts(f, "POSIX ");
2853
2854 seq_printf(f, " %s ",
2855 (inode == NULL) ? "*NOINODE*" :
2856 mandatory_lock(inode) ? "MANDATORY" : "ADVISORY ");
2857 } else if (IS_FLOCK(fl)) {
2858 if (fl->fl_type & LOCK_MAND) {
2859 seq_puts(f, "FLOCK MSNFS ");
2860 } else {
2861 seq_puts(f, "FLOCK ADVISORY ");
2862 }
2863 } else if (IS_LEASE(fl)) {
2864 if (fl->fl_flags & FL_DELEG)
2865 seq_puts(f, "DELEG ");
2866 else
2867 seq_puts(f, "LEASE ");
2868
2869 if (lease_breaking(fl))
2870 seq_puts(f, "BREAKING ");
2871 else if (fl->fl_file)
2872 seq_puts(f, "ACTIVE ");
2873 else
2874 seq_puts(f, "BREAKER ");
2875 } else {
2876 seq_puts(f, "UNKNOWN UNKNOWN ");
2877 }
2878 if (fl->fl_type & LOCK_MAND) {
2879 seq_printf(f, "%s ",
2880 (fl->fl_type & LOCK_READ)
2881 ? (fl->fl_type & LOCK_WRITE) ? "RW " : "READ "
2882 : (fl->fl_type & LOCK_WRITE) ? "WRITE" : "NONE ");
2883 } else {
2884 int type = IS_LEASE(fl) ? target_leasetype(fl) : fl->fl_type;
2885
2886 seq_printf(f, "%s ", (type == F_WRLCK) ? "WRITE" :
2887 (type == F_RDLCK) ? "READ" : "UNLCK");
2888 }
2889 if (inode) {
2890 /* userspace relies on this representation of dev_t */
2891 seq_printf(f, "%d %02x:%02x:%lu ", fl_pid,
2892 MAJOR(inode->i_sb->s_dev),
2893 MINOR(inode->i_sb->s_dev), inode->i_ino);
2894 } else {
2895 seq_printf(f, "%d <none>:0 ", fl_pid);
2896 }
2897 if (IS_POSIX(fl)) {
2898 if (fl->fl_end == OFFSET_MAX)
2899 seq_printf(f, "%Ld EOF\n", fl->fl_start);
2900 else
2901 seq_printf(f, "%Ld %Ld\n", fl->fl_start, fl->fl_end);
2902 } else {
2903 seq_puts(f, "0 EOF\n");
2904 }
2905}
2906
2907static int locks_show(struct seq_file *f, void *v)
2908{
2909 struct locks_iterator *iter = f->private;
2910 struct file_lock *fl, *bfl;
2911 struct pid_namespace *proc_pidns = proc_pid_ns(file_inode(f->file)->i_sb);
2912
2913 fl = hlist_entry(v, struct file_lock, fl_link);
2914
2915 if (locks_translate_pid(fl, proc_pidns) == 0)
2916 return 0;
2917
2918 lock_get_status(f, fl, iter->li_pos, "");
2919
2920 list_for_each_entry(bfl, &fl->fl_blocked_requests, fl_blocked_member)
2921 lock_get_status(f, bfl, iter->li_pos, " ->");
2922
2923 return 0;
2924}
2925
2926static void __show_fd_locks(struct seq_file *f,
2927 struct list_head *head, int *id,
2928 struct file *filp, struct files_struct *files)
2929{
2930 struct file_lock *fl;
2931
2932 list_for_each_entry(fl, head, fl_list) {
2933
2934 if (filp != fl->fl_file)
2935 continue;
2936 if (fl->fl_owner != files &&
2937 fl->fl_owner != filp)
2938 continue;
2939
2940 (*id)++;
2941 seq_puts(f, "lock:\t");
2942 lock_get_status(f, fl, *id, "");
2943 }
2944}
2945
2946void show_fd_locks(struct seq_file *f,
2947 struct file *filp, struct files_struct *files)
2948{
2949 struct inode *inode = locks_inode(filp);
2950 struct file_lock_context *ctx;
2951 int id = 0;
2952
2953 ctx = smp_load_acquire(&inode->i_flctx);
2954 if (!ctx)
2955 return;
2956
2957 spin_lock(&ctx->flc_lock);
2958 __show_fd_locks(f, &ctx->flc_flock, &id, filp, files);
2959 __show_fd_locks(f, &ctx->flc_posix, &id, filp, files);
2960 __show_fd_locks(f, &ctx->flc_lease, &id, filp, files);
2961 spin_unlock(&ctx->flc_lock);
2962}
2963
2964static void *locks_start(struct seq_file *f, loff_t *pos)
2965 __acquires(&blocked_lock_lock)
2966{
2967 struct locks_iterator *iter = f->private;
2968
2969 iter->li_pos = *pos + 1;
2970 percpu_down_write(&file_rwsem);
2971 spin_lock(&blocked_lock_lock);
2972 return seq_hlist_start_percpu(&file_lock_list.hlist, &iter->li_cpu, *pos);
2973}
2974
2975static void *locks_next(struct seq_file *f, void *v, loff_t *pos)
2976{
2977 struct locks_iterator *iter = f->private;
2978
2979 ++iter->li_pos;
2980 return seq_hlist_next_percpu(v, &file_lock_list.hlist, &iter->li_cpu, pos);
2981}
2982
2983static void locks_stop(struct seq_file *f, void *v)
2984 __releases(&blocked_lock_lock)
2985{
2986 spin_unlock(&blocked_lock_lock);
2987 percpu_up_write(&file_rwsem);
2988}
2989
2990static const struct seq_operations locks_seq_operations = {
2991 .start = locks_start,
2992 .next = locks_next,
2993 .stop = locks_stop,
2994 .show = locks_show,
2995};
2996
2997static int __init proc_locks_init(void)
2998{
2999 proc_create_seq_private("locks", 0, NULL, &locks_seq_operations,
3000 sizeof(struct locks_iterator), NULL);
3001 return 0;
3002}
3003fs_initcall(proc_locks_init);
3004#endif
3005
3006static int __init filelock_init(void)
3007{
3008 int i;
3009
3010 flctx_cache = kmem_cache_create("file_lock_ctx",
3011 sizeof(struct file_lock_context), 0, SLAB_PANIC, NULL);
3012
3013 filelock_cache = kmem_cache_create("file_lock_cache",
3014 sizeof(struct file_lock), 0, SLAB_PANIC, NULL);
3015
3016 for_each_possible_cpu(i) {
3017 struct file_lock_list_struct *fll = per_cpu_ptr(&file_lock_list, i);
3018
3019 spin_lock_init(&fll->lock);
3020 INIT_HLIST_HEAD(&fll->hlist);
3021 }
3022
3023 lease_notifier_chain_init();
3024 return 0;
3025}
3026core_initcall(filelock_init);
1/*
2 * linux/fs/locks.c
3 *
4 * Provide support for fcntl()'s F_GETLK, F_SETLK, and F_SETLKW calls.
5 * Doug Evans (dje@spiff.uucp), August 07, 1992
6 *
7 * Deadlock detection added.
8 * FIXME: one thing isn't handled yet:
9 * - mandatory locks (requires lots of changes elsewhere)
10 * Kelly Carmichael (kelly@[142.24.8.65]), September 17, 1994.
11 *
12 * Miscellaneous edits, and a total rewrite of posix_lock_file() code.
13 * Kai Petzke (wpp@marie.physik.tu-berlin.de), 1994
14 *
15 * Converted file_lock_table to a linked list from an array, which eliminates
16 * the limits on how many active file locks are open.
17 * Chad Page (pageone@netcom.com), November 27, 1994
18 *
19 * Removed dependency on file descriptors. dup()'ed file descriptors now
20 * get the same locks as the original file descriptors, and a close() on
21 * any file descriptor removes ALL the locks on the file for the current
22 * process. Since locks still depend on the process id, locks are inherited
23 * after an exec() but not after a fork(). This agrees with POSIX, and both
24 * BSD and SVR4 practice.
25 * Andy Walker (andy@lysaker.kvaerner.no), February 14, 1995
26 *
27 * Scrapped free list which is redundant now that we allocate locks
28 * dynamically with kmalloc()/kfree().
29 * Andy Walker (andy@lysaker.kvaerner.no), February 21, 1995
30 *
31 * Implemented two lock personalities - FL_FLOCK and FL_POSIX.
32 *
33 * FL_POSIX locks are created with calls to fcntl() and lockf() through the
34 * fcntl() system call. They have the semantics described above.
35 *
36 * FL_FLOCK locks are created with calls to flock(), through the flock()
37 * system call, which is new. Old C libraries implement flock() via fcntl()
38 * and will continue to use the old, broken implementation.
39 *
40 * FL_FLOCK locks follow the 4.4 BSD flock() semantics. They are associated
41 * with a file pointer (filp). As a result they can be shared by a parent
42 * process and its children after a fork(). They are removed when the last
43 * file descriptor referring to the file pointer is closed (unless explicitly
44 * unlocked).
45 *
46 * FL_FLOCK locks never deadlock, an existing lock is always removed before
47 * upgrading from shared to exclusive (or vice versa). When this happens
48 * any processes blocked by the current lock are woken up and allowed to
49 * run before the new lock is applied.
50 * Andy Walker (andy@lysaker.kvaerner.no), June 09, 1995
51 *
52 * Removed some race conditions in flock_lock_file(), marked other possible
53 * races. Just grep for FIXME to see them.
54 * Dmitry Gorodchanin (pgmdsg@ibi.com), February 09, 1996.
55 *
56 * Addressed Dmitry's concerns. Deadlock checking no longer recursive.
57 * Lock allocation changed to GFP_ATOMIC as we can't afford to sleep
58 * once we've checked for blocking and deadlocking.
59 * Andy Walker (andy@lysaker.kvaerner.no), April 03, 1996.
60 *
61 * Initial implementation of mandatory locks. SunOS turned out to be
62 * a rotten model, so I implemented the "obvious" semantics.
63 * See 'Documentation/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);