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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/mandatory.txt' for details.
64 * Andy Walker (andy@lysaker.kvaerner.no), April 06, 1996.
65 *
66 * Don't allow mandatory locks on mmap()'ed files. Added simple functions to
67 * check if a file has mandatory locks, used by mmap(), open() and creat() to
68 * see if system call should be rejected. Ref. HP-UX/SunOS/Solaris Reference
69 * Manual, Section 2.
70 * Andy Walker (andy@lysaker.kvaerner.no), April 09, 1996.
71 *
72 * Tidied up block list handling. Added '/proc/locks' interface.
73 * Andy Walker (andy@lysaker.kvaerner.no), April 24, 1996.
74 *
75 * Fixed deadlock condition for pathological code that mixes calls to
76 * flock() and fcntl().
77 * Andy Walker (andy@lysaker.kvaerner.no), April 29, 1996.
78 *
79 * Allow only one type of locking scheme (FL_POSIX or FL_FLOCK) to be in use
80 * for a given file at a time. Changed the CONFIG_LOCK_MANDATORY scheme to
81 * guarantee sensible behaviour in the case where file system modules might
82 * be compiled with different options than the kernel itself.
83 * Andy Walker (andy@lysaker.kvaerner.no), May 15, 1996.
84 *
85 * Added a couple of missing wake_up() calls. Thanks to Thomas Meckel
86 * (Thomas.Meckel@mni.fh-giessen.de) for spotting this.
87 * Andy Walker (andy@lysaker.kvaerner.no), May 15, 1996.
88 *
89 * Changed FL_POSIX locks to use the block list in the same way as FL_FLOCK
90 * locks. Changed process synchronisation to avoid dereferencing locks that
91 * have already been freed.
92 * Andy Walker (andy@lysaker.kvaerner.no), Sep 21, 1996.
93 *
94 * Made the block list a circular list to minimise searching in the list.
95 * Andy Walker (andy@lysaker.kvaerner.no), Sep 25, 1996.
96 *
97 * Made mandatory locking a mount option. Default is not to allow mandatory
98 * locking.
99 * Andy Walker (andy@lysaker.kvaerner.no), Oct 04, 1996.
100 *
101 * Some adaptations for NFS support.
102 * Olaf Kirch (okir@monad.swb.de), Dec 1996,
103 *
104 * Fixed /proc/locks interface so that we can't overrun the buffer we are handed.
105 * Andy Walker (andy@lysaker.kvaerner.no), May 12, 1997.
106 *
107 * Use slab allocator instead of kmalloc/kfree.
108 * Use generic list implementation from <linux/list.h>.
109 * Sped up posix_locks_deadlock by only considering blocked locks.
110 * Matthew Wilcox <willy@debian.org>, March, 2000.
111 *
112 * Leases and LOCK_MAND
113 * Matthew Wilcox <willy@debian.org>, June, 2000.
114 * Stephen Rothwell <sfr@canb.auug.org.au>, June, 2000.
115 */
116
117#include <linux/capability.h>
118#include <linux/file.h>
119#include <linux/fdtable.h>
120#include <linux/fs.h>
121#include <linux/init.h>
122#include <linux/module.h>
123#include <linux/security.h>
124#include <linux/slab.h>
125#include <linux/syscalls.h>
126#include <linux/time.h>
127#include <linux/rcupdate.h>
128#include <linux/pid_namespace.h>
129
130#include <asm/uaccess.h>
131
132#define IS_POSIX(fl) (fl->fl_flags & FL_POSIX)
133#define IS_FLOCK(fl) (fl->fl_flags & FL_FLOCK)
134#define IS_LEASE(fl) (fl->fl_flags & FL_LEASE)
135
136int leases_enable = 1;
137int lease_break_time = 45;
138
139#define for_each_lock(inode, lockp) \
140 for (lockp = &inode->i_flock; *lockp != NULL; lockp = &(*lockp)->fl_next)
141
142static LIST_HEAD(file_lock_list);
143static LIST_HEAD(blocked_list);
144static DEFINE_SPINLOCK(file_lock_lock);
145
146/*
147 * Protects the two list heads above, plus the inode->i_flock list
148 */
149void lock_flocks(void)
150{
151 spin_lock(&file_lock_lock);
152}
153EXPORT_SYMBOL_GPL(lock_flocks);
154
155void unlock_flocks(void)
156{
157 spin_unlock(&file_lock_lock);
158}
159EXPORT_SYMBOL_GPL(unlock_flocks);
160
161static struct kmem_cache *filelock_cache __read_mostly;
162
163static void locks_init_lock_heads(struct file_lock *fl)
164{
165 INIT_LIST_HEAD(&fl->fl_link);
166 INIT_LIST_HEAD(&fl->fl_block);
167 init_waitqueue_head(&fl->fl_wait);
168}
169
170/* Allocate an empty lock structure. */
171struct file_lock *locks_alloc_lock(void)
172{
173 struct file_lock *fl = kmem_cache_zalloc(filelock_cache, GFP_KERNEL);
174
175 if (fl)
176 locks_init_lock_heads(fl);
177
178 return fl;
179}
180EXPORT_SYMBOL_GPL(locks_alloc_lock);
181
182void locks_release_private(struct file_lock *fl)
183{
184 if (fl->fl_ops) {
185 if (fl->fl_ops->fl_release_private)
186 fl->fl_ops->fl_release_private(fl);
187 fl->fl_ops = NULL;
188 }
189 if (fl->fl_lmops) {
190 if (fl->fl_lmops->lm_release_private)
191 fl->fl_lmops->lm_release_private(fl);
192 fl->fl_lmops = NULL;
193 }
194
195}
196EXPORT_SYMBOL_GPL(locks_release_private);
197
198/* Free a lock which is not in use. */
199void locks_free_lock(struct file_lock *fl)
200{
201 BUG_ON(waitqueue_active(&fl->fl_wait));
202 BUG_ON(!list_empty(&fl->fl_block));
203 BUG_ON(!list_empty(&fl->fl_link));
204
205 locks_release_private(fl);
206 kmem_cache_free(filelock_cache, fl);
207}
208EXPORT_SYMBOL(locks_free_lock);
209
210void locks_init_lock(struct file_lock *fl)
211{
212 memset(fl, 0, sizeof(struct file_lock));
213 locks_init_lock_heads(fl);
214}
215
216EXPORT_SYMBOL(locks_init_lock);
217
218static void locks_copy_private(struct file_lock *new, struct file_lock *fl)
219{
220 if (fl->fl_ops) {
221 if (fl->fl_ops->fl_copy_lock)
222 fl->fl_ops->fl_copy_lock(new, fl);
223 new->fl_ops = fl->fl_ops;
224 }
225 if (fl->fl_lmops)
226 new->fl_lmops = fl->fl_lmops;
227}
228
229/*
230 * Initialize a new lock from an existing file_lock structure.
231 */
232void __locks_copy_lock(struct file_lock *new, const struct file_lock *fl)
233{
234 new->fl_owner = fl->fl_owner;
235 new->fl_pid = fl->fl_pid;
236 new->fl_file = NULL;
237 new->fl_flags = fl->fl_flags;
238 new->fl_type = fl->fl_type;
239 new->fl_start = fl->fl_start;
240 new->fl_end = fl->fl_end;
241 new->fl_ops = NULL;
242 new->fl_lmops = NULL;
243}
244EXPORT_SYMBOL(__locks_copy_lock);
245
246void locks_copy_lock(struct file_lock *new, struct file_lock *fl)
247{
248 locks_release_private(new);
249
250 __locks_copy_lock(new, fl);
251 new->fl_file = fl->fl_file;
252 new->fl_ops = fl->fl_ops;
253 new->fl_lmops = fl->fl_lmops;
254
255 locks_copy_private(new, fl);
256}
257
258EXPORT_SYMBOL(locks_copy_lock);
259
260static inline int flock_translate_cmd(int cmd) {
261 if (cmd & LOCK_MAND)
262 return cmd & (LOCK_MAND | LOCK_RW);
263 switch (cmd) {
264 case LOCK_SH:
265 return F_RDLCK;
266 case LOCK_EX:
267 return F_WRLCK;
268 case LOCK_UN:
269 return F_UNLCK;
270 }
271 return -EINVAL;
272}
273
274/* Fill in a file_lock structure with an appropriate FLOCK lock. */
275static int flock_make_lock(struct file *filp, struct file_lock **lock,
276 unsigned int cmd)
277{
278 struct file_lock *fl;
279 int type = flock_translate_cmd(cmd);
280 if (type < 0)
281 return type;
282
283 fl = locks_alloc_lock();
284 if (fl == NULL)
285 return -ENOMEM;
286
287 fl->fl_file = filp;
288 fl->fl_pid = current->tgid;
289 fl->fl_flags = FL_FLOCK;
290 fl->fl_type = type;
291 fl->fl_end = OFFSET_MAX;
292
293 *lock = fl;
294 return 0;
295}
296
297static int assign_type(struct file_lock *fl, int type)
298{
299 switch (type) {
300 case F_RDLCK:
301 case F_WRLCK:
302 case F_UNLCK:
303 fl->fl_type = type;
304 break;
305 default:
306 return -EINVAL;
307 }
308 return 0;
309}
310
311/* Verify a "struct flock" and copy it to a "struct file_lock" as a POSIX
312 * style lock.
313 */
314static int flock_to_posix_lock(struct file *filp, struct file_lock *fl,
315 struct flock *l)
316{
317 off_t start, end;
318
319 switch (l->l_whence) {
320 case SEEK_SET:
321 start = 0;
322 break;
323 case SEEK_CUR:
324 start = filp->f_pos;
325 break;
326 case SEEK_END:
327 start = i_size_read(filp->f_path.dentry->d_inode);
328 break;
329 default:
330 return -EINVAL;
331 }
332
333 /* POSIX-1996 leaves the case l->l_len < 0 undefined;
334 POSIX-2001 defines it. */
335 start += l->l_start;
336 if (start < 0)
337 return -EINVAL;
338 fl->fl_end = OFFSET_MAX;
339 if (l->l_len > 0) {
340 end = start + l->l_len - 1;
341 fl->fl_end = end;
342 } else if (l->l_len < 0) {
343 end = start - 1;
344 fl->fl_end = end;
345 start += l->l_len;
346 if (start < 0)
347 return -EINVAL;
348 }
349 fl->fl_start = start; /* we record the absolute position */
350 if (fl->fl_end < fl->fl_start)
351 return -EOVERFLOW;
352
353 fl->fl_owner = current->files;
354 fl->fl_pid = current->tgid;
355 fl->fl_file = filp;
356 fl->fl_flags = FL_POSIX;
357 fl->fl_ops = NULL;
358 fl->fl_lmops = NULL;
359
360 return assign_type(fl, l->l_type);
361}
362
363#if BITS_PER_LONG == 32
364static int flock64_to_posix_lock(struct file *filp, struct file_lock *fl,
365 struct flock64 *l)
366{
367 loff_t start;
368
369 switch (l->l_whence) {
370 case SEEK_SET:
371 start = 0;
372 break;
373 case SEEK_CUR:
374 start = filp->f_pos;
375 break;
376 case SEEK_END:
377 start = i_size_read(filp->f_path.dentry->d_inode);
378 break;
379 default:
380 return -EINVAL;
381 }
382
383 start += l->l_start;
384 if (start < 0)
385 return -EINVAL;
386 fl->fl_end = OFFSET_MAX;
387 if (l->l_len > 0) {
388 fl->fl_end = start + l->l_len - 1;
389 } else if (l->l_len < 0) {
390 fl->fl_end = start - 1;
391 start += l->l_len;
392 if (start < 0)
393 return -EINVAL;
394 }
395 fl->fl_start = start; /* we record the absolute position */
396 if (fl->fl_end < fl->fl_start)
397 return -EOVERFLOW;
398
399 fl->fl_owner = current->files;
400 fl->fl_pid = current->tgid;
401 fl->fl_file = filp;
402 fl->fl_flags = FL_POSIX;
403 fl->fl_ops = NULL;
404 fl->fl_lmops = NULL;
405
406 return assign_type(fl, l->l_type);
407}
408#endif
409
410/* default lease lock manager operations */
411static void lease_break_callback(struct file_lock *fl)
412{
413 kill_fasync(&fl->fl_fasync, SIGIO, POLL_MSG);
414}
415
416static void lease_release_private_callback(struct file_lock *fl)
417{
418 if (!fl->fl_file)
419 return;
420
421 f_delown(fl->fl_file);
422 fl->fl_file->f_owner.signum = 0;
423}
424
425static const struct lock_manager_operations lease_manager_ops = {
426 .lm_break = lease_break_callback,
427 .lm_release_private = lease_release_private_callback,
428 .lm_change = lease_modify,
429};
430
431/*
432 * Initialize a lease, use the default lock manager operations
433 */
434static int lease_init(struct file *filp, int type, struct file_lock *fl)
435 {
436 if (assign_type(fl, type) != 0)
437 return -EINVAL;
438
439 fl->fl_owner = current->files;
440 fl->fl_pid = current->tgid;
441
442 fl->fl_file = filp;
443 fl->fl_flags = FL_LEASE;
444 fl->fl_start = 0;
445 fl->fl_end = OFFSET_MAX;
446 fl->fl_ops = NULL;
447 fl->fl_lmops = &lease_manager_ops;
448 return 0;
449}
450
451/* Allocate a file_lock initialised to this type of lease */
452static struct file_lock *lease_alloc(struct file *filp, int type)
453{
454 struct file_lock *fl = locks_alloc_lock();
455 int error = -ENOMEM;
456
457 if (fl == NULL)
458 return ERR_PTR(error);
459
460 error = lease_init(filp, type, fl);
461 if (error) {
462 locks_free_lock(fl);
463 return ERR_PTR(error);
464 }
465 return fl;
466}
467
468/* Check if two locks overlap each other.
469 */
470static inline int locks_overlap(struct file_lock *fl1, struct file_lock *fl2)
471{
472 return ((fl1->fl_end >= fl2->fl_start) &&
473 (fl2->fl_end >= fl1->fl_start));
474}
475
476/*
477 * Check whether two locks have the same owner.
478 */
479static int posix_same_owner(struct file_lock *fl1, struct file_lock *fl2)
480{
481 if (fl1->fl_lmops && fl1->fl_lmops->lm_compare_owner)
482 return fl2->fl_lmops == fl1->fl_lmops &&
483 fl1->fl_lmops->lm_compare_owner(fl1, fl2);
484 return fl1->fl_owner == fl2->fl_owner;
485}
486
487/* Remove waiter from blocker's block list.
488 * When blocker ends up pointing to itself then the list is empty.
489 */
490static void __locks_delete_block(struct file_lock *waiter)
491{
492 list_del_init(&waiter->fl_block);
493 list_del_init(&waiter->fl_link);
494 waiter->fl_next = NULL;
495}
496
497/*
498 */
499static void locks_delete_block(struct file_lock *waiter)
500{
501 lock_flocks();
502 __locks_delete_block(waiter);
503 unlock_flocks();
504}
505
506/* Insert waiter into blocker's block list.
507 * We use a circular list so that processes can be easily woken up in
508 * the order they blocked. The documentation doesn't require this but
509 * it seems like the reasonable thing to do.
510 */
511static void locks_insert_block(struct file_lock *blocker,
512 struct file_lock *waiter)
513{
514 BUG_ON(!list_empty(&waiter->fl_block));
515 list_add_tail(&waiter->fl_block, &blocker->fl_block);
516 waiter->fl_next = blocker;
517 if (IS_POSIX(blocker))
518 list_add(&waiter->fl_link, &blocked_list);
519}
520
521/* Wake up processes blocked waiting for blocker.
522 * If told to wait then schedule the processes until the block list
523 * is empty, otherwise empty the block list ourselves.
524 */
525static void locks_wake_up_blocks(struct file_lock *blocker)
526{
527 while (!list_empty(&blocker->fl_block)) {
528 struct file_lock *waiter;
529
530 waiter = list_first_entry(&blocker->fl_block,
531 struct file_lock, fl_block);
532 __locks_delete_block(waiter);
533 if (waiter->fl_lmops && waiter->fl_lmops->lm_notify)
534 waiter->fl_lmops->lm_notify(waiter);
535 else
536 wake_up(&waiter->fl_wait);
537 }
538}
539
540/* Insert file lock fl into an inode's lock list at the position indicated
541 * by pos. At the same time add the lock to the global file lock list.
542 */
543static void locks_insert_lock(struct file_lock **pos, struct file_lock *fl)
544{
545 list_add(&fl->fl_link, &file_lock_list);
546
547 fl->fl_nspid = get_pid(task_tgid(current));
548
549 /* insert into file's list */
550 fl->fl_next = *pos;
551 *pos = fl;
552}
553
554/*
555 * Delete a lock and then free it.
556 * Wake up processes that are blocked waiting for this lock,
557 * notify the FS that the lock has been cleared and
558 * finally free the lock.
559 */
560static void locks_delete_lock(struct file_lock **thisfl_p)
561{
562 struct file_lock *fl = *thisfl_p;
563
564 *thisfl_p = fl->fl_next;
565 fl->fl_next = NULL;
566 list_del_init(&fl->fl_link);
567
568 fasync_helper(0, fl->fl_file, 0, &fl->fl_fasync);
569 if (fl->fl_fasync != NULL) {
570 printk(KERN_ERR "locks_delete_lock: fasync == %p\n", fl->fl_fasync);
571 fl->fl_fasync = NULL;
572 }
573
574 if (fl->fl_nspid) {
575 put_pid(fl->fl_nspid);
576 fl->fl_nspid = NULL;
577 }
578
579 locks_wake_up_blocks(fl);
580 locks_free_lock(fl);
581}
582
583/* Determine if lock sys_fl blocks lock caller_fl. Common functionality
584 * checks for shared/exclusive status of overlapping locks.
585 */
586static int locks_conflict(struct file_lock *caller_fl, struct file_lock *sys_fl)
587{
588 if (sys_fl->fl_type == F_WRLCK)
589 return 1;
590 if (caller_fl->fl_type == F_WRLCK)
591 return 1;
592 return 0;
593}
594
595/* Determine if lock sys_fl blocks lock caller_fl. POSIX specific
596 * checking before calling the locks_conflict().
597 */
598static int posix_locks_conflict(struct file_lock *caller_fl, struct file_lock *sys_fl)
599{
600 /* POSIX locks owned by the same process do not conflict with
601 * each other.
602 */
603 if (!IS_POSIX(sys_fl) || posix_same_owner(caller_fl, sys_fl))
604 return (0);
605
606 /* Check whether they overlap */
607 if (!locks_overlap(caller_fl, sys_fl))
608 return 0;
609
610 return (locks_conflict(caller_fl, sys_fl));
611}
612
613/* Determine if lock sys_fl blocks lock caller_fl. FLOCK specific
614 * checking before calling the locks_conflict().
615 */
616static int flock_locks_conflict(struct file_lock *caller_fl, struct file_lock *sys_fl)
617{
618 /* FLOCK locks referring to the same filp do not conflict with
619 * each other.
620 */
621 if (!IS_FLOCK(sys_fl) || (caller_fl->fl_file == sys_fl->fl_file))
622 return (0);
623 if ((caller_fl->fl_type & LOCK_MAND) || (sys_fl->fl_type & LOCK_MAND))
624 return 0;
625
626 return (locks_conflict(caller_fl, sys_fl));
627}
628
629void
630posix_test_lock(struct file *filp, struct file_lock *fl)
631{
632 struct file_lock *cfl;
633
634 lock_flocks();
635 for (cfl = filp->f_path.dentry->d_inode->i_flock; cfl; cfl = cfl->fl_next) {
636 if (!IS_POSIX(cfl))
637 continue;
638 if (posix_locks_conflict(fl, cfl))
639 break;
640 }
641 if (cfl) {
642 __locks_copy_lock(fl, cfl);
643 if (cfl->fl_nspid)
644 fl->fl_pid = pid_vnr(cfl->fl_nspid);
645 } else
646 fl->fl_type = F_UNLCK;
647 unlock_flocks();
648 return;
649}
650EXPORT_SYMBOL(posix_test_lock);
651
652/*
653 * Deadlock detection:
654 *
655 * We attempt to detect deadlocks that are due purely to posix file
656 * locks.
657 *
658 * We assume that a task can be waiting for at most one lock at a time.
659 * So for any acquired lock, the process holding that lock may be
660 * waiting on at most one other lock. That lock in turns may be held by
661 * someone waiting for at most one other lock. Given a requested lock
662 * caller_fl which is about to wait for a conflicting lock block_fl, we
663 * follow this chain of waiters to ensure we are not about to create a
664 * cycle.
665 *
666 * Since we do this before we ever put a process to sleep on a lock, we
667 * are ensured that there is never a cycle; that is what guarantees that
668 * the while() loop in posix_locks_deadlock() eventually completes.
669 *
670 * Note: the above assumption may not be true when handling lock
671 * requests from a broken NFS client. It may also fail in the presence
672 * of tasks (such as posix threads) sharing the same open file table.
673 *
674 * To handle those cases, we just bail out after a few iterations.
675 */
676
677#define MAX_DEADLK_ITERATIONS 10
678
679/* Find a lock that the owner of the given block_fl is blocking on. */
680static struct file_lock *what_owner_is_waiting_for(struct file_lock *block_fl)
681{
682 struct file_lock *fl;
683
684 list_for_each_entry(fl, &blocked_list, fl_link) {
685 if (posix_same_owner(fl, block_fl))
686 return fl->fl_next;
687 }
688 return NULL;
689}
690
691static int posix_locks_deadlock(struct file_lock *caller_fl,
692 struct file_lock *block_fl)
693{
694 int i = 0;
695
696 while ((block_fl = what_owner_is_waiting_for(block_fl))) {
697 if (i++ > MAX_DEADLK_ITERATIONS)
698 return 0;
699 if (posix_same_owner(caller_fl, block_fl))
700 return 1;
701 }
702 return 0;
703}
704
705/* Try to create a FLOCK lock on filp. We always insert new FLOCK locks
706 * after any leases, but before any posix locks.
707 *
708 * Note that if called with an FL_EXISTS argument, the caller may determine
709 * whether or not a lock was successfully freed by testing the return
710 * value for -ENOENT.
711 */
712static int flock_lock_file(struct file *filp, struct file_lock *request)
713{
714 struct file_lock *new_fl = NULL;
715 struct file_lock **before;
716 struct inode * inode = filp->f_path.dentry->d_inode;
717 int error = 0;
718 int found = 0;
719
720 if (!(request->fl_flags & FL_ACCESS) && (request->fl_type != F_UNLCK)) {
721 new_fl = locks_alloc_lock();
722 if (!new_fl)
723 return -ENOMEM;
724 }
725
726 lock_flocks();
727 if (request->fl_flags & FL_ACCESS)
728 goto find_conflict;
729
730 for_each_lock(inode, before) {
731 struct file_lock *fl = *before;
732 if (IS_POSIX(fl))
733 break;
734 if (IS_LEASE(fl))
735 continue;
736 if (filp != fl->fl_file)
737 continue;
738 if (request->fl_type == fl->fl_type)
739 goto out;
740 found = 1;
741 locks_delete_lock(before);
742 break;
743 }
744
745 if (request->fl_type == F_UNLCK) {
746 if ((request->fl_flags & FL_EXISTS) && !found)
747 error = -ENOENT;
748 goto out;
749 }
750
751 /*
752 * If a higher-priority process was blocked on the old file lock,
753 * give it the opportunity to lock the file.
754 */
755 if (found) {
756 unlock_flocks();
757 cond_resched();
758 lock_flocks();
759 }
760
761find_conflict:
762 for_each_lock(inode, before) {
763 struct file_lock *fl = *before;
764 if (IS_POSIX(fl))
765 break;
766 if (IS_LEASE(fl))
767 continue;
768 if (!flock_locks_conflict(request, fl))
769 continue;
770 error = -EAGAIN;
771 if (!(request->fl_flags & FL_SLEEP))
772 goto out;
773 error = FILE_LOCK_DEFERRED;
774 locks_insert_block(fl, request);
775 goto out;
776 }
777 if (request->fl_flags & FL_ACCESS)
778 goto out;
779 locks_copy_lock(new_fl, request);
780 locks_insert_lock(before, new_fl);
781 new_fl = NULL;
782 error = 0;
783
784out:
785 unlock_flocks();
786 if (new_fl)
787 locks_free_lock(new_fl);
788 return error;
789}
790
791static int __posix_lock_file(struct inode *inode, struct file_lock *request, struct file_lock *conflock)
792{
793 struct file_lock *fl;
794 struct file_lock *new_fl = NULL;
795 struct file_lock *new_fl2 = NULL;
796 struct file_lock *left = NULL;
797 struct file_lock *right = NULL;
798 struct file_lock **before;
799 int error, added = 0;
800
801 /*
802 * We may need two file_lock structures for this operation,
803 * so we get them in advance to avoid races.
804 *
805 * In some cases we can be sure, that no new locks will be needed
806 */
807 if (!(request->fl_flags & FL_ACCESS) &&
808 (request->fl_type != F_UNLCK ||
809 request->fl_start != 0 || request->fl_end != OFFSET_MAX)) {
810 new_fl = locks_alloc_lock();
811 new_fl2 = locks_alloc_lock();
812 }
813
814 lock_flocks();
815 if (request->fl_type != F_UNLCK) {
816 for_each_lock(inode, before) {
817 fl = *before;
818 if (!IS_POSIX(fl))
819 continue;
820 if (!posix_locks_conflict(request, fl))
821 continue;
822 if (conflock)
823 __locks_copy_lock(conflock, fl);
824 error = -EAGAIN;
825 if (!(request->fl_flags & FL_SLEEP))
826 goto out;
827 error = -EDEADLK;
828 if (posix_locks_deadlock(request, fl))
829 goto out;
830 error = FILE_LOCK_DEFERRED;
831 locks_insert_block(fl, request);
832 goto out;
833 }
834 }
835
836 /* If we're just looking for a conflict, we're done. */
837 error = 0;
838 if (request->fl_flags & FL_ACCESS)
839 goto out;
840
841 /*
842 * Find the first old lock with the same owner as the new lock.
843 */
844
845 before = &inode->i_flock;
846
847 /* First skip locks owned by other processes. */
848 while ((fl = *before) && (!IS_POSIX(fl) ||
849 !posix_same_owner(request, fl))) {
850 before = &fl->fl_next;
851 }
852
853 /* Process locks with this owner. */
854 while ((fl = *before) && posix_same_owner(request, fl)) {
855 /* Detect adjacent or overlapping regions (if same lock type)
856 */
857 if (request->fl_type == fl->fl_type) {
858 /* In all comparisons of start vs end, use
859 * "start - 1" rather than "end + 1". If end
860 * is OFFSET_MAX, end + 1 will become negative.
861 */
862 if (fl->fl_end < request->fl_start - 1)
863 goto next_lock;
864 /* If the next lock in the list has entirely bigger
865 * addresses than the new one, insert the lock here.
866 */
867 if (fl->fl_start - 1 > request->fl_end)
868 break;
869
870 /* If we come here, the new and old lock are of the
871 * same type and adjacent or overlapping. Make one
872 * lock yielding from the lower start address of both
873 * locks to the higher end address.
874 */
875 if (fl->fl_start > request->fl_start)
876 fl->fl_start = request->fl_start;
877 else
878 request->fl_start = fl->fl_start;
879 if (fl->fl_end < request->fl_end)
880 fl->fl_end = request->fl_end;
881 else
882 request->fl_end = fl->fl_end;
883 if (added) {
884 locks_delete_lock(before);
885 continue;
886 }
887 request = fl;
888 added = 1;
889 }
890 else {
891 /* Processing for different lock types is a bit
892 * more complex.
893 */
894 if (fl->fl_end < request->fl_start)
895 goto next_lock;
896 if (fl->fl_start > request->fl_end)
897 break;
898 if (request->fl_type == F_UNLCK)
899 added = 1;
900 if (fl->fl_start < request->fl_start)
901 left = fl;
902 /* If the next lock in the list has a higher end
903 * address than the new one, insert the new one here.
904 */
905 if (fl->fl_end > request->fl_end) {
906 right = fl;
907 break;
908 }
909 if (fl->fl_start >= request->fl_start) {
910 /* The new lock completely replaces an old
911 * one (This may happen several times).
912 */
913 if (added) {
914 locks_delete_lock(before);
915 continue;
916 }
917 /* Replace the old lock with the new one.
918 * Wake up anybody waiting for the old one,
919 * as the change in lock type might satisfy
920 * their needs.
921 */
922 locks_wake_up_blocks(fl);
923 fl->fl_start = request->fl_start;
924 fl->fl_end = request->fl_end;
925 fl->fl_type = request->fl_type;
926 locks_release_private(fl);
927 locks_copy_private(fl, request);
928 request = fl;
929 added = 1;
930 }
931 }
932 /* Go on to next lock.
933 */
934 next_lock:
935 before = &fl->fl_next;
936 }
937
938 /*
939 * The above code only modifies existing locks in case of
940 * merging or replacing. If new lock(s) need to be inserted
941 * all modifications are done bellow this, so it's safe yet to
942 * bail out.
943 */
944 error = -ENOLCK; /* "no luck" */
945 if (right && left == right && !new_fl2)
946 goto out;
947
948 error = 0;
949 if (!added) {
950 if (request->fl_type == F_UNLCK) {
951 if (request->fl_flags & FL_EXISTS)
952 error = -ENOENT;
953 goto out;
954 }
955
956 if (!new_fl) {
957 error = -ENOLCK;
958 goto out;
959 }
960 locks_copy_lock(new_fl, request);
961 locks_insert_lock(before, new_fl);
962 new_fl = NULL;
963 }
964 if (right) {
965 if (left == right) {
966 /* The new lock breaks the old one in two pieces,
967 * so we have to use the second new lock.
968 */
969 left = new_fl2;
970 new_fl2 = NULL;
971 locks_copy_lock(left, right);
972 locks_insert_lock(before, left);
973 }
974 right->fl_start = request->fl_end + 1;
975 locks_wake_up_blocks(right);
976 }
977 if (left) {
978 left->fl_end = request->fl_start - 1;
979 locks_wake_up_blocks(left);
980 }
981 out:
982 unlock_flocks();
983 /*
984 * Free any unused locks.
985 */
986 if (new_fl)
987 locks_free_lock(new_fl);
988 if (new_fl2)
989 locks_free_lock(new_fl2);
990 return error;
991}
992
993/**
994 * posix_lock_file - Apply a POSIX-style lock to a file
995 * @filp: The file to apply the lock to
996 * @fl: The lock to be applied
997 * @conflock: Place to return a copy of the conflicting lock, if found.
998 *
999 * Add a POSIX style lock to a file.
1000 * We merge adjacent & overlapping locks whenever possible.
1001 * POSIX locks are sorted by owner task, then by starting address
1002 *
1003 * Note that if called with an FL_EXISTS argument, the caller may determine
1004 * whether or not a lock was successfully freed by testing the return
1005 * value for -ENOENT.
1006 */
1007int posix_lock_file(struct file *filp, struct file_lock *fl,
1008 struct file_lock *conflock)
1009{
1010 return __posix_lock_file(filp->f_path.dentry->d_inode, fl, conflock);
1011}
1012EXPORT_SYMBOL(posix_lock_file);
1013
1014/**
1015 * posix_lock_file_wait - Apply a POSIX-style lock to a file
1016 * @filp: The file to apply the lock to
1017 * @fl: The lock to be applied
1018 *
1019 * Add a POSIX style lock to a file.
1020 * We merge adjacent & overlapping locks whenever possible.
1021 * POSIX locks are sorted by owner task, then by starting address
1022 */
1023int posix_lock_file_wait(struct file *filp, struct file_lock *fl)
1024{
1025 int error;
1026 might_sleep ();
1027 for (;;) {
1028 error = posix_lock_file(filp, fl, NULL);
1029 if (error != FILE_LOCK_DEFERRED)
1030 break;
1031 error = wait_event_interruptible(fl->fl_wait, !fl->fl_next);
1032 if (!error)
1033 continue;
1034
1035 locks_delete_block(fl);
1036 break;
1037 }
1038 return error;
1039}
1040EXPORT_SYMBOL(posix_lock_file_wait);
1041
1042/**
1043 * locks_mandatory_locked - Check for an active lock
1044 * @inode: the file to check
1045 *
1046 * Searches the inode's list of locks to find any POSIX locks which conflict.
1047 * This function is called from locks_verify_locked() only.
1048 */
1049int locks_mandatory_locked(struct inode *inode)
1050{
1051 fl_owner_t owner = current->files;
1052 struct file_lock *fl;
1053
1054 /*
1055 * Search the lock list for this inode for any POSIX locks.
1056 */
1057 lock_flocks();
1058 for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) {
1059 if (!IS_POSIX(fl))
1060 continue;
1061 if (fl->fl_owner != owner)
1062 break;
1063 }
1064 unlock_flocks();
1065 return fl ? -EAGAIN : 0;
1066}
1067
1068/**
1069 * locks_mandatory_area - Check for a conflicting lock
1070 * @read_write: %FLOCK_VERIFY_WRITE for exclusive access, %FLOCK_VERIFY_READ
1071 * for shared
1072 * @inode: the file to check
1073 * @filp: how the file was opened (if it was)
1074 * @offset: start of area to check
1075 * @count: length of area to check
1076 *
1077 * Searches the inode's list of locks to find any POSIX locks which conflict.
1078 * This function is called from rw_verify_area() and
1079 * locks_verify_truncate().
1080 */
1081int locks_mandatory_area(int read_write, struct inode *inode,
1082 struct file *filp, loff_t offset,
1083 size_t count)
1084{
1085 struct file_lock fl;
1086 int error;
1087
1088 locks_init_lock(&fl);
1089 fl.fl_owner = current->files;
1090 fl.fl_pid = current->tgid;
1091 fl.fl_file = filp;
1092 fl.fl_flags = FL_POSIX | FL_ACCESS;
1093 if (filp && !(filp->f_flags & O_NONBLOCK))
1094 fl.fl_flags |= FL_SLEEP;
1095 fl.fl_type = (read_write == FLOCK_VERIFY_WRITE) ? F_WRLCK : F_RDLCK;
1096 fl.fl_start = offset;
1097 fl.fl_end = offset + count - 1;
1098
1099 for (;;) {
1100 error = __posix_lock_file(inode, &fl, NULL);
1101 if (error != FILE_LOCK_DEFERRED)
1102 break;
1103 error = wait_event_interruptible(fl.fl_wait, !fl.fl_next);
1104 if (!error) {
1105 /*
1106 * If we've been sleeping someone might have
1107 * changed the permissions behind our back.
1108 */
1109 if (__mandatory_lock(inode))
1110 continue;
1111 }
1112
1113 locks_delete_block(&fl);
1114 break;
1115 }
1116
1117 return error;
1118}
1119
1120EXPORT_SYMBOL(locks_mandatory_area);
1121
1122/* We already had a lease on this file; just change its type */
1123int lease_modify(struct file_lock **before, int arg)
1124{
1125 struct file_lock *fl = *before;
1126 int error = assign_type(fl, arg);
1127
1128 if (error)
1129 return error;
1130 locks_wake_up_blocks(fl);
1131 if (arg == F_UNLCK)
1132 locks_delete_lock(before);
1133 return 0;
1134}
1135
1136EXPORT_SYMBOL(lease_modify);
1137
1138static void time_out_leases(struct inode *inode)
1139{
1140 struct file_lock **before;
1141 struct file_lock *fl;
1142
1143 before = &inode->i_flock;
1144 while ((fl = *before) && IS_LEASE(fl) && (fl->fl_type & F_INPROGRESS)) {
1145 if ((fl->fl_break_time == 0)
1146 || time_before(jiffies, fl->fl_break_time)) {
1147 before = &fl->fl_next;
1148 continue;
1149 }
1150 lease_modify(before, fl->fl_type & ~F_INPROGRESS);
1151 if (fl == *before) /* lease_modify may have freed fl */
1152 before = &fl->fl_next;
1153 }
1154}
1155
1156/**
1157 * __break_lease - revoke all outstanding leases on file
1158 * @inode: the inode of the file to return
1159 * @mode: the open mode (read or write)
1160 *
1161 * break_lease (inlined for speed) has checked there already is at least
1162 * some kind of lock (maybe a lease) on this file. Leases are broken on
1163 * a call to open() or truncate(). This function can sleep unless you
1164 * specified %O_NONBLOCK to your open().
1165 */
1166int __break_lease(struct inode *inode, unsigned int mode)
1167{
1168 int error = 0, future;
1169 struct file_lock *new_fl, *flock;
1170 struct file_lock *fl;
1171 unsigned long break_time;
1172 int i_have_this_lease = 0;
1173 int want_write = (mode & O_ACCMODE) != O_RDONLY;
1174
1175 new_fl = lease_alloc(NULL, want_write ? F_WRLCK : F_RDLCK);
1176
1177 lock_flocks();
1178
1179 time_out_leases(inode);
1180
1181 flock = inode->i_flock;
1182 if ((flock == NULL) || !IS_LEASE(flock))
1183 goto out;
1184
1185 for (fl = flock; fl && IS_LEASE(fl); fl = fl->fl_next)
1186 if (fl->fl_owner == current->files)
1187 i_have_this_lease = 1;
1188
1189 if (want_write) {
1190 /* If we want write access, we have to revoke any lease. */
1191 future = F_UNLCK | F_INPROGRESS;
1192 } else if (flock->fl_type & F_INPROGRESS) {
1193 /* If the lease is already being broken, we just leave it */
1194 future = flock->fl_type;
1195 } else if (flock->fl_type & F_WRLCK) {
1196 /* Downgrade the exclusive lease to a read-only lease. */
1197 future = F_RDLCK | F_INPROGRESS;
1198 } else {
1199 /* the existing lease was read-only, so we can read too. */
1200 goto out;
1201 }
1202
1203 if (IS_ERR(new_fl) && !i_have_this_lease
1204 && ((mode & O_NONBLOCK) == 0)) {
1205 error = PTR_ERR(new_fl);
1206 goto out;
1207 }
1208
1209 break_time = 0;
1210 if (lease_break_time > 0) {
1211 break_time = jiffies + lease_break_time * HZ;
1212 if (break_time == 0)
1213 break_time++; /* so that 0 means no break time */
1214 }
1215
1216 for (fl = flock; fl && IS_LEASE(fl); fl = fl->fl_next) {
1217 if (fl->fl_type != future) {
1218 fl->fl_type = future;
1219 fl->fl_break_time = break_time;
1220 /* lease must have lmops break callback */
1221 fl->fl_lmops->lm_break(fl);
1222 }
1223 }
1224
1225 if (i_have_this_lease || (mode & O_NONBLOCK)) {
1226 error = -EWOULDBLOCK;
1227 goto out;
1228 }
1229
1230restart:
1231 break_time = flock->fl_break_time;
1232 if (break_time != 0) {
1233 break_time -= jiffies;
1234 if (break_time == 0)
1235 break_time++;
1236 }
1237 locks_insert_block(flock, new_fl);
1238 unlock_flocks();
1239 error = wait_event_interruptible_timeout(new_fl->fl_wait,
1240 !new_fl->fl_next, break_time);
1241 lock_flocks();
1242 __locks_delete_block(new_fl);
1243 if (error >= 0) {
1244 if (error == 0)
1245 time_out_leases(inode);
1246 /* Wait for the next lease that has not been broken yet */
1247 for (flock = inode->i_flock; flock && IS_LEASE(flock);
1248 flock = flock->fl_next) {
1249 if (flock->fl_type & F_INPROGRESS)
1250 goto restart;
1251 }
1252 error = 0;
1253 }
1254
1255out:
1256 unlock_flocks();
1257 if (!IS_ERR(new_fl))
1258 locks_free_lock(new_fl);
1259 return error;
1260}
1261
1262EXPORT_SYMBOL(__break_lease);
1263
1264/**
1265 * lease_get_mtime - get the last modified time of an inode
1266 * @inode: the inode
1267 * @time: pointer to a timespec which will contain the last modified time
1268 *
1269 * This is to force NFS clients to flush their caches for files with
1270 * exclusive leases. The justification is that if someone has an
1271 * exclusive lease, then they could be modifying it.
1272 */
1273void lease_get_mtime(struct inode *inode, struct timespec *time)
1274{
1275 struct file_lock *flock = inode->i_flock;
1276 if (flock && IS_LEASE(flock) && (flock->fl_type & F_WRLCK))
1277 *time = current_fs_time(inode->i_sb);
1278 else
1279 *time = inode->i_mtime;
1280}
1281
1282EXPORT_SYMBOL(lease_get_mtime);
1283
1284/**
1285 * fcntl_getlease - Enquire what lease is currently active
1286 * @filp: the file
1287 *
1288 * The value returned by this function will be one of
1289 * (if no lease break is pending):
1290 *
1291 * %F_RDLCK to indicate a shared lease is held.
1292 *
1293 * %F_WRLCK to indicate an exclusive lease is held.
1294 *
1295 * %F_UNLCK to indicate no lease is held.
1296 *
1297 * (if a lease break is pending):
1298 *
1299 * %F_RDLCK to indicate an exclusive lease needs to be
1300 * changed to a shared lease (or removed).
1301 *
1302 * %F_UNLCK to indicate the lease needs to be removed.
1303 *
1304 * XXX: sfr & willy disagree over whether F_INPROGRESS
1305 * should be returned to userspace.
1306 */
1307int fcntl_getlease(struct file *filp)
1308{
1309 struct file_lock *fl;
1310 int type = F_UNLCK;
1311
1312 lock_flocks();
1313 time_out_leases(filp->f_path.dentry->d_inode);
1314 for (fl = filp->f_path.dentry->d_inode->i_flock; fl && IS_LEASE(fl);
1315 fl = fl->fl_next) {
1316 if (fl->fl_file == filp) {
1317 type = fl->fl_type & ~F_INPROGRESS;
1318 break;
1319 }
1320 }
1321 unlock_flocks();
1322 return type;
1323}
1324
1325/**
1326 * generic_setlease - sets a lease on an open file
1327 * @filp: file pointer
1328 * @arg: type of lease to obtain
1329 * @flp: input - file_lock to use, output - file_lock inserted
1330 *
1331 * The (input) flp->fl_lmops->lm_break function is required
1332 * by break_lease().
1333 *
1334 * Called with file_lock_lock held.
1335 */
1336int generic_setlease(struct file *filp, long arg, struct file_lock **flp)
1337{
1338 struct file_lock *fl, **before, **my_before = NULL, *lease;
1339 struct dentry *dentry = filp->f_path.dentry;
1340 struct inode *inode = dentry->d_inode;
1341 int error, rdlease_count = 0, wrlease_count = 0;
1342
1343 lease = *flp;
1344
1345 error = -EACCES;
1346 if ((current_fsuid() != inode->i_uid) && !capable(CAP_LEASE))
1347 goto out;
1348 error = -EINVAL;
1349 if (!S_ISREG(inode->i_mode))
1350 goto out;
1351 error = security_file_lock(filp, arg);
1352 if (error)
1353 goto out;
1354
1355 time_out_leases(inode);
1356
1357 BUG_ON(!(*flp)->fl_lmops->lm_break);
1358
1359 if (arg != F_UNLCK) {
1360 error = -EAGAIN;
1361 if ((arg == F_RDLCK) && (atomic_read(&inode->i_writecount) > 0))
1362 goto out;
1363 if ((arg == F_WRLCK)
1364 && ((dentry->d_count > 1)
1365 || (atomic_read(&inode->i_count) > 1)))
1366 goto out;
1367 }
1368
1369 /*
1370 * At this point, we know that if there is an exclusive
1371 * lease on this file, then we hold it on this filp
1372 * (otherwise our open of this file would have blocked).
1373 * And if we are trying to acquire an exclusive lease,
1374 * then the file is not open by anyone (including us)
1375 * except for this filp.
1376 */
1377 for (before = &inode->i_flock;
1378 ((fl = *before) != NULL) && IS_LEASE(fl);
1379 before = &fl->fl_next) {
1380 if (fl->fl_file == filp)
1381 my_before = before;
1382 else if (fl->fl_type == (F_INPROGRESS | F_UNLCK))
1383 /*
1384 * Someone is in the process of opening this
1385 * file for writing so we may not take an
1386 * exclusive lease on it.
1387 */
1388 wrlease_count++;
1389 else
1390 rdlease_count++;
1391 }
1392
1393 error = -EAGAIN;
1394 if ((arg == F_RDLCK && (wrlease_count > 0)) ||
1395 (arg == F_WRLCK && ((rdlease_count + wrlease_count) > 0)))
1396 goto out;
1397
1398 if (my_before != NULL) {
1399 error = lease->fl_lmops->lm_change(my_before, arg);
1400 if (!error)
1401 *flp = *my_before;
1402 goto out;
1403 }
1404
1405 if (arg == F_UNLCK)
1406 goto out;
1407
1408 error = -EINVAL;
1409 if (!leases_enable)
1410 goto out;
1411
1412 locks_insert_lock(before, lease);
1413 return 0;
1414
1415out:
1416 return error;
1417}
1418EXPORT_SYMBOL(generic_setlease);
1419
1420static int __vfs_setlease(struct file *filp, long arg, struct file_lock **lease)
1421{
1422 if (filp->f_op && filp->f_op->setlease)
1423 return filp->f_op->setlease(filp, arg, lease);
1424 else
1425 return generic_setlease(filp, arg, lease);
1426}
1427
1428/**
1429 * vfs_setlease - sets a lease on an open file
1430 * @filp: file pointer
1431 * @arg: type of lease to obtain
1432 * @lease: file_lock to use
1433 *
1434 * Call this to establish a lease on the file.
1435 * The (*lease)->fl_lmops->lm_break operation must be set; if not,
1436 * break_lease will oops!
1437 *
1438 * This will call the filesystem's setlease file method, if
1439 * defined. Note that there is no getlease method; instead, the
1440 * filesystem setlease method should call back to setlease() to
1441 * add a lease to the inode's lease list, where fcntl_getlease() can
1442 * find it. Since fcntl_getlease() only reports whether the current
1443 * task holds a lease, a cluster filesystem need only do this for
1444 * leases held by processes on this node.
1445 *
1446 * There is also no break_lease method; filesystems that
1447 * handle their own leases should break leases themselves from the
1448 * filesystem's open, create, and (on truncate) setattr methods.
1449 *
1450 * Warning: the only current setlease methods exist only to disable
1451 * leases in certain cases. More vfs changes may be required to
1452 * allow a full filesystem lease implementation.
1453 */
1454
1455int vfs_setlease(struct file *filp, long arg, struct file_lock **lease)
1456{
1457 int error;
1458
1459 lock_flocks();
1460 error = __vfs_setlease(filp, arg, lease);
1461 unlock_flocks();
1462
1463 return error;
1464}
1465EXPORT_SYMBOL_GPL(vfs_setlease);
1466
1467static int do_fcntl_delete_lease(struct file *filp)
1468{
1469 struct file_lock fl, *flp = &fl;
1470
1471 lease_init(filp, F_UNLCK, flp);
1472
1473 return vfs_setlease(filp, F_UNLCK, &flp);
1474}
1475
1476static int do_fcntl_add_lease(unsigned int fd, struct file *filp, long arg)
1477{
1478 struct file_lock *fl, *ret;
1479 struct fasync_struct *new;
1480 int error;
1481
1482 fl = lease_alloc(filp, arg);
1483 if (IS_ERR(fl))
1484 return PTR_ERR(fl);
1485
1486 new = fasync_alloc();
1487 if (!new) {
1488 locks_free_lock(fl);
1489 return -ENOMEM;
1490 }
1491 ret = fl;
1492 lock_flocks();
1493 error = __vfs_setlease(filp, arg, &ret);
1494 if (error) {
1495 unlock_flocks();
1496 locks_free_lock(fl);
1497 goto out_free_fasync;
1498 }
1499 if (ret != fl)
1500 locks_free_lock(fl);
1501
1502 /*
1503 * fasync_insert_entry() returns the old entry if any.
1504 * If there was no old entry, then it used 'new' and
1505 * inserted it into the fasync list. Clear new so that
1506 * we don't release it here.
1507 */
1508 if (!fasync_insert_entry(fd, filp, &ret->fl_fasync, new))
1509 new = NULL;
1510
1511 error = __f_setown(filp, task_pid(current), PIDTYPE_PID, 0);
1512 unlock_flocks();
1513
1514out_free_fasync:
1515 if (new)
1516 fasync_free(new);
1517 return error;
1518}
1519
1520/**
1521 * fcntl_setlease - sets a lease on an open file
1522 * @fd: open file descriptor
1523 * @filp: file pointer
1524 * @arg: type of lease to obtain
1525 *
1526 * Call this fcntl to establish a lease on the file.
1527 * Note that you also need to call %F_SETSIG to
1528 * receive a signal when the lease is broken.
1529 */
1530int fcntl_setlease(unsigned int fd, struct file *filp, long arg)
1531{
1532 if (arg == F_UNLCK)
1533 return do_fcntl_delete_lease(filp);
1534 return do_fcntl_add_lease(fd, filp, arg);
1535}
1536
1537/**
1538 * flock_lock_file_wait - Apply a FLOCK-style lock to a file
1539 * @filp: The file to apply the lock to
1540 * @fl: The lock to be applied
1541 *
1542 * Add a FLOCK style lock to a file.
1543 */
1544int flock_lock_file_wait(struct file *filp, struct file_lock *fl)
1545{
1546 int error;
1547 might_sleep();
1548 for (;;) {
1549 error = flock_lock_file(filp, fl);
1550 if (error != FILE_LOCK_DEFERRED)
1551 break;
1552 error = wait_event_interruptible(fl->fl_wait, !fl->fl_next);
1553 if (!error)
1554 continue;
1555
1556 locks_delete_block(fl);
1557 break;
1558 }
1559 return error;
1560}
1561
1562EXPORT_SYMBOL(flock_lock_file_wait);
1563
1564/**
1565 * sys_flock: - flock() system call.
1566 * @fd: the file descriptor to lock.
1567 * @cmd: the type of lock to apply.
1568 *
1569 * Apply a %FL_FLOCK style lock to an open file descriptor.
1570 * The @cmd can be one of
1571 *
1572 * %LOCK_SH -- a shared lock.
1573 *
1574 * %LOCK_EX -- an exclusive lock.
1575 *
1576 * %LOCK_UN -- remove an existing lock.
1577 *
1578 * %LOCK_MAND -- a `mandatory' flock. This exists to emulate Windows Share Modes.
1579 *
1580 * %LOCK_MAND can be combined with %LOCK_READ or %LOCK_WRITE to allow other
1581 * processes read and write access respectively.
1582 */
1583SYSCALL_DEFINE2(flock, unsigned int, fd, unsigned int, cmd)
1584{
1585 struct file *filp;
1586 struct file_lock *lock;
1587 int can_sleep, unlock;
1588 int error;
1589
1590 error = -EBADF;
1591 filp = fget(fd);
1592 if (!filp)
1593 goto out;
1594
1595 can_sleep = !(cmd & LOCK_NB);
1596 cmd &= ~LOCK_NB;
1597 unlock = (cmd == LOCK_UN);
1598
1599 if (!unlock && !(cmd & LOCK_MAND) &&
1600 !(filp->f_mode & (FMODE_READ|FMODE_WRITE)))
1601 goto out_putf;
1602
1603 error = flock_make_lock(filp, &lock, cmd);
1604 if (error)
1605 goto out_putf;
1606 if (can_sleep)
1607 lock->fl_flags |= FL_SLEEP;
1608
1609 error = security_file_lock(filp, lock->fl_type);
1610 if (error)
1611 goto out_free;
1612
1613 if (filp->f_op && filp->f_op->flock)
1614 error = filp->f_op->flock(filp,
1615 (can_sleep) ? F_SETLKW : F_SETLK,
1616 lock);
1617 else
1618 error = flock_lock_file_wait(filp, lock);
1619
1620 out_free:
1621 locks_free_lock(lock);
1622
1623 out_putf:
1624 fput(filp);
1625 out:
1626 return error;
1627}
1628
1629/**
1630 * vfs_test_lock - test file byte range lock
1631 * @filp: The file to test lock for
1632 * @fl: The lock to test; also used to hold result
1633 *
1634 * Returns -ERRNO on failure. Indicates presence of conflicting lock by
1635 * setting conf->fl_type to something other than F_UNLCK.
1636 */
1637int vfs_test_lock(struct file *filp, struct file_lock *fl)
1638{
1639 if (filp->f_op && filp->f_op->lock)
1640 return filp->f_op->lock(filp, F_GETLK, fl);
1641 posix_test_lock(filp, fl);
1642 return 0;
1643}
1644EXPORT_SYMBOL_GPL(vfs_test_lock);
1645
1646static int posix_lock_to_flock(struct flock *flock, struct file_lock *fl)
1647{
1648 flock->l_pid = fl->fl_pid;
1649#if BITS_PER_LONG == 32
1650 /*
1651 * Make sure we can represent the posix lock via
1652 * legacy 32bit flock.
1653 */
1654 if (fl->fl_start > OFFT_OFFSET_MAX)
1655 return -EOVERFLOW;
1656 if (fl->fl_end != OFFSET_MAX && fl->fl_end > OFFT_OFFSET_MAX)
1657 return -EOVERFLOW;
1658#endif
1659 flock->l_start = fl->fl_start;
1660 flock->l_len = fl->fl_end == OFFSET_MAX ? 0 :
1661 fl->fl_end - fl->fl_start + 1;
1662 flock->l_whence = 0;
1663 flock->l_type = fl->fl_type;
1664 return 0;
1665}
1666
1667#if BITS_PER_LONG == 32
1668static void posix_lock_to_flock64(struct flock64 *flock, struct file_lock *fl)
1669{
1670 flock->l_pid = fl->fl_pid;
1671 flock->l_start = fl->fl_start;
1672 flock->l_len = fl->fl_end == OFFSET_MAX ? 0 :
1673 fl->fl_end - fl->fl_start + 1;
1674 flock->l_whence = 0;
1675 flock->l_type = fl->fl_type;
1676}
1677#endif
1678
1679/* Report the first existing lock that would conflict with l.
1680 * This implements the F_GETLK command of fcntl().
1681 */
1682int fcntl_getlk(struct file *filp, struct flock __user *l)
1683{
1684 struct file_lock file_lock;
1685 struct flock flock;
1686 int error;
1687
1688 error = -EFAULT;
1689 if (copy_from_user(&flock, l, sizeof(flock)))
1690 goto out;
1691 error = -EINVAL;
1692 if ((flock.l_type != F_RDLCK) && (flock.l_type != F_WRLCK))
1693 goto out;
1694
1695 error = flock_to_posix_lock(filp, &file_lock, &flock);
1696 if (error)
1697 goto out;
1698
1699 error = vfs_test_lock(filp, &file_lock);
1700 if (error)
1701 goto out;
1702
1703 flock.l_type = file_lock.fl_type;
1704 if (file_lock.fl_type != F_UNLCK) {
1705 error = posix_lock_to_flock(&flock, &file_lock);
1706 if (error)
1707 goto out;
1708 }
1709 error = -EFAULT;
1710 if (!copy_to_user(l, &flock, sizeof(flock)))
1711 error = 0;
1712out:
1713 return error;
1714}
1715
1716/**
1717 * vfs_lock_file - file byte range lock
1718 * @filp: The file to apply the lock to
1719 * @cmd: type of locking operation (F_SETLK, F_GETLK, etc.)
1720 * @fl: The lock to be applied
1721 * @conf: Place to return a copy of the conflicting lock, if found.
1722 *
1723 * A caller that doesn't care about the conflicting lock may pass NULL
1724 * as the final argument.
1725 *
1726 * If the filesystem defines a private ->lock() method, then @conf will
1727 * be left unchanged; so a caller that cares should initialize it to
1728 * some acceptable default.
1729 *
1730 * To avoid blocking kernel daemons, such as lockd, that need to acquire POSIX
1731 * locks, the ->lock() interface may return asynchronously, before the lock has
1732 * been granted or denied by the underlying filesystem, if (and only if)
1733 * lm_grant is set. Callers expecting ->lock() to return asynchronously
1734 * will only use F_SETLK, not F_SETLKW; they will set FL_SLEEP if (and only if)
1735 * the request is for a blocking lock. When ->lock() does return asynchronously,
1736 * it must return FILE_LOCK_DEFERRED, and call ->lm_grant() when the lock
1737 * request completes.
1738 * If the request is for non-blocking lock the file system should return
1739 * FILE_LOCK_DEFERRED then try to get the lock and call the callback routine
1740 * with the result. If the request timed out the callback routine will return a
1741 * nonzero return code and the file system should release the lock. The file
1742 * system is also responsible to keep a corresponding posix lock when it
1743 * grants a lock so the VFS can find out which locks are locally held and do
1744 * the correct lock cleanup when required.
1745 * The underlying filesystem must not drop the kernel lock or call
1746 * ->lm_grant() before returning to the caller with a FILE_LOCK_DEFERRED
1747 * return code.
1748 */
1749int vfs_lock_file(struct file *filp, unsigned int cmd, struct file_lock *fl, struct file_lock *conf)
1750{
1751 if (filp->f_op && filp->f_op->lock)
1752 return filp->f_op->lock(filp, cmd, fl);
1753 else
1754 return posix_lock_file(filp, fl, conf);
1755}
1756EXPORT_SYMBOL_GPL(vfs_lock_file);
1757
1758static int do_lock_file_wait(struct file *filp, unsigned int cmd,
1759 struct file_lock *fl)
1760{
1761 int error;
1762
1763 error = security_file_lock(filp, fl->fl_type);
1764 if (error)
1765 return error;
1766
1767 for (;;) {
1768 error = vfs_lock_file(filp, cmd, fl, NULL);
1769 if (error != FILE_LOCK_DEFERRED)
1770 break;
1771 error = wait_event_interruptible(fl->fl_wait, !fl->fl_next);
1772 if (!error)
1773 continue;
1774
1775 locks_delete_block(fl);
1776 break;
1777 }
1778
1779 return error;
1780}
1781
1782/* Apply the lock described by l to an open file descriptor.
1783 * This implements both the F_SETLK and F_SETLKW commands of fcntl().
1784 */
1785int fcntl_setlk(unsigned int fd, struct file *filp, unsigned int cmd,
1786 struct flock __user *l)
1787{
1788 struct file_lock *file_lock = locks_alloc_lock();
1789 struct flock flock;
1790 struct inode *inode;
1791 struct file *f;
1792 int error;
1793
1794 if (file_lock == NULL)
1795 return -ENOLCK;
1796
1797 /*
1798 * This might block, so we do it before checking the inode.
1799 */
1800 error = -EFAULT;
1801 if (copy_from_user(&flock, l, sizeof(flock)))
1802 goto out;
1803
1804 inode = filp->f_path.dentry->d_inode;
1805
1806 /* Don't allow mandatory locks on files that may be memory mapped
1807 * and shared.
1808 */
1809 if (mandatory_lock(inode) && mapping_writably_mapped(filp->f_mapping)) {
1810 error = -EAGAIN;
1811 goto out;
1812 }
1813
1814again:
1815 error = flock_to_posix_lock(filp, file_lock, &flock);
1816 if (error)
1817 goto out;
1818 if (cmd == F_SETLKW) {
1819 file_lock->fl_flags |= FL_SLEEP;
1820 }
1821
1822 error = -EBADF;
1823 switch (flock.l_type) {
1824 case F_RDLCK:
1825 if (!(filp->f_mode & FMODE_READ))
1826 goto out;
1827 break;
1828 case F_WRLCK:
1829 if (!(filp->f_mode & FMODE_WRITE))
1830 goto out;
1831 break;
1832 case F_UNLCK:
1833 break;
1834 default:
1835 error = -EINVAL;
1836 goto out;
1837 }
1838
1839 error = do_lock_file_wait(filp, cmd, file_lock);
1840
1841 /*
1842 * Attempt to detect a close/fcntl race and recover by
1843 * releasing the lock that was just acquired.
1844 */
1845 /*
1846 * we need that spin_lock here - it prevents reordering between
1847 * update of inode->i_flock and check for it done in close().
1848 * rcu_read_lock() wouldn't do.
1849 */
1850 spin_lock(¤t->files->file_lock);
1851 f = fcheck(fd);
1852 spin_unlock(¤t->files->file_lock);
1853 if (!error && f != filp && flock.l_type != F_UNLCK) {
1854 flock.l_type = F_UNLCK;
1855 goto again;
1856 }
1857
1858out:
1859 locks_free_lock(file_lock);
1860 return error;
1861}
1862
1863#if BITS_PER_LONG == 32
1864/* Report the first existing lock that would conflict with l.
1865 * This implements the F_GETLK command of fcntl().
1866 */
1867int fcntl_getlk64(struct file *filp, struct flock64 __user *l)
1868{
1869 struct file_lock file_lock;
1870 struct flock64 flock;
1871 int error;
1872
1873 error = -EFAULT;
1874 if (copy_from_user(&flock, l, sizeof(flock)))
1875 goto out;
1876 error = -EINVAL;
1877 if ((flock.l_type != F_RDLCK) && (flock.l_type != F_WRLCK))
1878 goto out;
1879
1880 error = flock64_to_posix_lock(filp, &file_lock, &flock);
1881 if (error)
1882 goto out;
1883
1884 error = vfs_test_lock(filp, &file_lock);
1885 if (error)
1886 goto out;
1887
1888 flock.l_type = file_lock.fl_type;
1889 if (file_lock.fl_type != F_UNLCK)
1890 posix_lock_to_flock64(&flock, &file_lock);
1891
1892 error = -EFAULT;
1893 if (!copy_to_user(l, &flock, sizeof(flock)))
1894 error = 0;
1895
1896out:
1897 return error;
1898}
1899
1900/* Apply the lock described by l to an open file descriptor.
1901 * This implements both the F_SETLK and F_SETLKW commands of fcntl().
1902 */
1903int fcntl_setlk64(unsigned int fd, struct file *filp, unsigned int cmd,
1904 struct flock64 __user *l)
1905{
1906 struct file_lock *file_lock = locks_alloc_lock();
1907 struct flock64 flock;
1908 struct inode *inode;
1909 struct file *f;
1910 int error;
1911
1912 if (file_lock == NULL)
1913 return -ENOLCK;
1914
1915 /*
1916 * This might block, so we do it before checking the inode.
1917 */
1918 error = -EFAULT;
1919 if (copy_from_user(&flock, l, sizeof(flock)))
1920 goto out;
1921
1922 inode = filp->f_path.dentry->d_inode;
1923
1924 /* Don't allow mandatory locks on files that may be memory mapped
1925 * and shared.
1926 */
1927 if (mandatory_lock(inode) && mapping_writably_mapped(filp->f_mapping)) {
1928 error = -EAGAIN;
1929 goto out;
1930 }
1931
1932again:
1933 error = flock64_to_posix_lock(filp, file_lock, &flock);
1934 if (error)
1935 goto out;
1936 if (cmd == F_SETLKW64) {
1937 file_lock->fl_flags |= FL_SLEEP;
1938 }
1939
1940 error = -EBADF;
1941 switch (flock.l_type) {
1942 case F_RDLCK:
1943 if (!(filp->f_mode & FMODE_READ))
1944 goto out;
1945 break;
1946 case F_WRLCK:
1947 if (!(filp->f_mode & FMODE_WRITE))
1948 goto out;
1949 break;
1950 case F_UNLCK:
1951 break;
1952 default:
1953 error = -EINVAL;
1954 goto out;
1955 }
1956
1957 error = do_lock_file_wait(filp, cmd, file_lock);
1958
1959 /*
1960 * Attempt to detect a close/fcntl race and recover by
1961 * releasing the lock that was just acquired.
1962 */
1963 spin_lock(¤t->files->file_lock);
1964 f = fcheck(fd);
1965 spin_unlock(¤t->files->file_lock);
1966 if (!error && f != filp && flock.l_type != F_UNLCK) {
1967 flock.l_type = F_UNLCK;
1968 goto again;
1969 }
1970
1971out:
1972 locks_free_lock(file_lock);
1973 return error;
1974}
1975#endif /* BITS_PER_LONG == 32 */
1976
1977/*
1978 * This function is called when the file is being removed
1979 * from the task's fd array. POSIX locks belonging to this task
1980 * are deleted at this time.
1981 */
1982void locks_remove_posix(struct file *filp, fl_owner_t owner)
1983{
1984 struct file_lock lock;
1985
1986 /*
1987 * If there are no locks held on this file, we don't need to call
1988 * posix_lock_file(). Another process could be setting a lock on this
1989 * file at the same time, but we wouldn't remove that lock anyway.
1990 */
1991 if (!filp->f_path.dentry->d_inode->i_flock)
1992 return;
1993
1994 lock.fl_type = F_UNLCK;
1995 lock.fl_flags = FL_POSIX | FL_CLOSE;
1996 lock.fl_start = 0;
1997 lock.fl_end = OFFSET_MAX;
1998 lock.fl_owner = owner;
1999 lock.fl_pid = current->tgid;
2000 lock.fl_file = filp;
2001 lock.fl_ops = NULL;
2002 lock.fl_lmops = NULL;
2003
2004 vfs_lock_file(filp, F_SETLK, &lock, NULL);
2005
2006 if (lock.fl_ops && lock.fl_ops->fl_release_private)
2007 lock.fl_ops->fl_release_private(&lock);
2008}
2009
2010EXPORT_SYMBOL(locks_remove_posix);
2011
2012/*
2013 * This function is called on the last close of an open file.
2014 */
2015void locks_remove_flock(struct file *filp)
2016{
2017 struct inode * inode = filp->f_path.dentry->d_inode;
2018 struct file_lock *fl;
2019 struct file_lock **before;
2020
2021 if (!inode->i_flock)
2022 return;
2023
2024 if (filp->f_op && filp->f_op->flock) {
2025 struct file_lock fl = {
2026 .fl_pid = current->tgid,
2027 .fl_file = filp,
2028 .fl_flags = FL_FLOCK,
2029 .fl_type = F_UNLCK,
2030 .fl_end = OFFSET_MAX,
2031 };
2032 filp->f_op->flock(filp, F_SETLKW, &fl);
2033 if (fl.fl_ops && fl.fl_ops->fl_release_private)
2034 fl.fl_ops->fl_release_private(&fl);
2035 }
2036
2037 lock_flocks();
2038 before = &inode->i_flock;
2039
2040 while ((fl = *before) != NULL) {
2041 if (fl->fl_file == filp) {
2042 if (IS_FLOCK(fl)) {
2043 locks_delete_lock(before);
2044 continue;
2045 }
2046 if (IS_LEASE(fl)) {
2047 lease_modify(before, F_UNLCK);
2048 continue;
2049 }
2050 /* What? */
2051 BUG();
2052 }
2053 before = &fl->fl_next;
2054 }
2055 unlock_flocks();
2056}
2057
2058/**
2059 * posix_unblock_lock - stop waiting for a file lock
2060 * @filp: how the file was opened
2061 * @waiter: the lock which was waiting
2062 *
2063 * lockd needs to block waiting for locks.
2064 */
2065int
2066posix_unblock_lock(struct file *filp, struct file_lock *waiter)
2067{
2068 int status = 0;
2069
2070 lock_flocks();
2071 if (waiter->fl_next)
2072 __locks_delete_block(waiter);
2073 else
2074 status = -ENOENT;
2075 unlock_flocks();
2076 return status;
2077}
2078
2079EXPORT_SYMBOL(posix_unblock_lock);
2080
2081/**
2082 * vfs_cancel_lock - file byte range unblock lock
2083 * @filp: The file to apply the unblock to
2084 * @fl: The lock to be unblocked
2085 *
2086 * Used by lock managers to cancel blocked requests
2087 */
2088int vfs_cancel_lock(struct file *filp, struct file_lock *fl)
2089{
2090 if (filp->f_op && filp->f_op->lock)
2091 return filp->f_op->lock(filp, F_CANCELLK, fl);
2092 return 0;
2093}
2094
2095EXPORT_SYMBOL_GPL(vfs_cancel_lock);
2096
2097#ifdef CONFIG_PROC_FS
2098#include <linux/proc_fs.h>
2099#include <linux/seq_file.h>
2100
2101static void lock_get_status(struct seq_file *f, struct file_lock *fl,
2102 loff_t id, char *pfx)
2103{
2104 struct inode *inode = NULL;
2105 unsigned int fl_pid;
2106
2107 if (fl->fl_nspid)
2108 fl_pid = pid_vnr(fl->fl_nspid);
2109 else
2110 fl_pid = fl->fl_pid;
2111
2112 if (fl->fl_file != NULL)
2113 inode = fl->fl_file->f_path.dentry->d_inode;
2114
2115 seq_printf(f, "%lld:%s ", id, pfx);
2116 if (IS_POSIX(fl)) {
2117 seq_printf(f, "%6s %s ",
2118 (fl->fl_flags & FL_ACCESS) ? "ACCESS" : "POSIX ",
2119 (inode == NULL) ? "*NOINODE*" :
2120 mandatory_lock(inode) ? "MANDATORY" : "ADVISORY ");
2121 } else if (IS_FLOCK(fl)) {
2122 if (fl->fl_type & LOCK_MAND) {
2123 seq_printf(f, "FLOCK MSNFS ");
2124 } else {
2125 seq_printf(f, "FLOCK ADVISORY ");
2126 }
2127 } else if (IS_LEASE(fl)) {
2128 seq_printf(f, "LEASE ");
2129 if (fl->fl_type & F_INPROGRESS)
2130 seq_printf(f, "BREAKING ");
2131 else if (fl->fl_file)
2132 seq_printf(f, "ACTIVE ");
2133 else
2134 seq_printf(f, "BREAKER ");
2135 } else {
2136 seq_printf(f, "UNKNOWN UNKNOWN ");
2137 }
2138 if (fl->fl_type & LOCK_MAND) {
2139 seq_printf(f, "%s ",
2140 (fl->fl_type & LOCK_READ)
2141 ? (fl->fl_type & LOCK_WRITE) ? "RW " : "READ "
2142 : (fl->fl_type & LOCK_WRITE) ? "WRITE" : "NONE ");
2143 } else {
2144 seq_printf(f, "%s ",
2145 (fl->fl_type & F_INPROGRESS)
2146 ? (fl->fl_type & F_UNLCK) ? "UNLCK" : "READ "
2147 : (fl->fl_type & F_WRLCK) ? "WRITE" : "READ ");
2148 }
2149 if (inode) {
2150#ifdef WE_CAN_BREAK_LSLK_NOW
2151 seq_printf(f, "%d %s:%ld ", fl_pid,
2152 inode->i_sb->s_id, inode->i_ino);
2153#else
2154 /* userspace relies on this representation of dev_t ;-( */
2155 seq_printf(f, "%d %02x:%02x:%ld ", fl_pid,
2156 MAJOR(inode->i_sb->s_dev),
2157 MINOR(inode->i_sb->s_dev), inode->i_ino);
2158#endif
2159 } else {
2160 seq_printf(f, "%d <none>:0 ", fl_pid);
2161 }
2162 if (IS_POSIX(fl)) {
2163 if (fl->fl_end == OFFSET_MAX)
2164 seq_printf(f, "%Ld EOF\n", fl->fl_start);
2165 else
2166 seq_printf(f, "%Ld %Ld\n", fl->fl_start, fl->fl_end);
2167 } else {
2168 seq_printf(f, "0 EOF\n");
2169 }
2170}
2171
2172static int locks_show(struct seq_file *f, void *v)
2173{
2174 struct file_lock *fl, *bfl;
2175
2176 fl = list_entry(v, struct file_lock, fl_link);
2177
2178 lock_get_status(f, fl, *((loff_t *)f->private), "");
2179
2180 list_for_each_entry(bfl, &fl->fl_block, fl_block)
2181 lock_get_status(f, bfl, *((loff_t *)f->private), " ->");
2182
2183 return 0;
2184}
2185
2186static void *locks_start(struct seq_file *f, loff_t *pos)
2187{
2188 loff_t *p = f->private;
2189
2190 lock_flocks();
2191 *p = (*pos + 1);
2192 return seq_list_start(&file_lock_list, *pos);
2193}
2194
2195static void *locks_next(struct seq_file *f, void *v, loff_t *pos)
2196{
2197 loff_t *p = f->private;
2198 ++*p;
2199 return seq_list_next(v, &file_lock_list, pos);
2200}
2201
2202static void locks_stop(struct seq_file *f, void *v)
2203{
2204 unlock_flocks();
2205}
2206
2207static const struct seq_operations locks_seq_operations = {
2208 .start = locks_start,
2209 .next = locks_next,
2210 .stop = locks_stop,
2211 .show = locks_show,
2212};
2213
2214static int locks_open(struct inode *inode, struct file *filp)
2215{
2216 return seq_open_private(filp, &locks_seq_operations, sizeof(loff_t));
2217}
2218
2219static const struct file_operations proc_locks_operations = {
2220 .open = locks_open,
2221 .read = seq_read,
2222 .llseek = seq_lseek,
2223 .release = seq_release_private,
2224};
2225
2226static int __init proc_locks_init(void)
2227{
2228 proc_create("locks", 0, NULL, &proc_locks_operations);
2229 return 0;
2230}
2231module_init(proc_locks_init);
2232#endif
2233
2234/**
2235 * lock_may_read - checks that the region is free of locks
2236 * @inode: the inode that is being read
2237 * @start: the first byte to read
2238 * @len: the number of bytes to read
2239 *
2240 * Emulates Windows locking requirements. Whole-file
2241 * mandatory locks (share modes) can prohibit a read and
2242 * byte-range POSIX locks can prohibit a read if they overlap.
2243 *
2244 * N.B. this function is only ever called
2245 * from knfsd and ownership of locks is never checked.
2246 */
2247int lock_may_read(struct inode *inode, loff_t start, unsigned long len)
2248{
2249 struct file_lock *fl;
2250 int result = 1;
2251 lock_flocks();
2252 for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) {
2253 if (IS_POSIX(fl)) {
2254 if (fl->fl_type == F_RDLCK)
2255 continue;
2256 if ((fl->fl_end < start) || (fl->fl_start > (start + len)))
2257 continue;
2258 } else if (IS_FLOCK(fl)) {
2259 if (!(fl->fl_type & LOCK_MAND))
2260 continue;
2261 if (fl->fl_type & LOCK_READ)
2262 continue;
2263 } else
2264 continue;
2265 result = 0;
2266 break;
2267 }
2268 unlock_flocks();
2269 return result;
2270}
2271
2272EXPORT_SYMBOL(lock_may_read);
2273
2274/**
2275 * lock_may_write - checks that the region is free of locks
2276 * @inode: the inode that is being written
2277 * @start: the first byte to write
2278 * @len: the number of bytes to write
2279 *
2280 * Emulates Windows locking requirements. Whole-file
2281 * mandatory locks (share modes) can prohibit a write and
2282 * byte-range POSIX locks can prohibit a write if they overlap.
2283 *
2284 * N.B. this function is only ever called
2285 * from knfsd and ownership of locks is never checked.
2286 */
2287int lock_may_write(struct inode *inode, loff_t start, unsigned long len)
2288{
2289 struct file_lock *fl;
2290 int result = 1;
2291 lock_flocks();
2292 for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) {
2293 if (IS_POSIX(fl)) {
2294 if ((fl->fl_end < start) || (fl->fl_start > (start + len)))
2295 continue;
2296 } else if (IS_FLOCK(fl)) {
2297 if (!(fl->fl_type & LOCK_MAND))
2298 continue;
2299 if (fl->fl_type & LOCK_WRITE)
2300 continue;
2301 } else
2302 continue;
2303 result = 0;
2304 break;
2305 }
2306 unlock_flocks();
2307 return result;
2308}
2309
2310EXPORT_SYMBOL(lock_may_write);
2311
2312static int __init filelock_init(void)
2313{
2314 filelock_cache = kmem_cache_create("file_lock_cache",
2315 sizeof(struct file_lock), 0, SLAB_PANIC, NULL);
2316
2317 return 0;
2318}
2319
2320core_initcall(filelock_init);