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