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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// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * linux/fs/locks.c
4 *
5 * We implement four types of file locks: BSD locks, posix locks, open
6 * file description locks, and leases. For details about BSD locks,
7 * see the flock(2) man page; for details about the other three, see
8 * fcntl(2).
9 *
10 *
11 * Locking conflicts and dependencies:
12 * If multiple threads attempt to lock the same byte (or flock the same file)
13 * only one can be granted the lock, and other must wait their turn.
14 * The first lock has been "applied" or "granted", the others are "waiting"
15 * and are "blocked" by the "applied" lock..
16 *
17 * Waiting and applied locks are all kept in trees whose properties are:
18 *
19 * - the root of a tree may be an applied or waiting lock.
20 * - every other node in the tree is a waiting lock that
21 * conflicts with every ancestor of that node.
22 *
23 * Every such tree begins life as a waiting singleton which obviously
24 * satisfies the above properties.
25 *
26 * The only ways we modify trees preserve these properties:
27 *
28 * 1. We may add a new leaf node, but only after first verifying that it
29 * conflicts with all of its ancestors.
30 * 2. We may remove the root of a tree, creating a new singleton
31 * tree from the root and N new trees rooted in the immediate
32 * children.
33 * 3. If the root of a tree is not currently an applied lock, we may
34 * apply it (if possible).
35 * 4. We may upgrade the root of the tree (either extend its range,
36 * or upgrade its entire range from read to write).
37 *
38 * When an applied lock is modified in a way that reduces or downgrades any
39 * part of its range, we remove all its children (2 above). This particularly
40 * happens when a lock is unlocked.
41 *
42 * For each of those child trees we "wake up" the thread which is
43 * waiting for the lock so it can continue handling as follows: if the
44 * root of the tree applies, we do so (3). If it doesn't, it must
45 * conflict with some applied lock. We remove (wake up) all of its children
46 * (2), and add it is a new leaf to the tree rooted in the applied
47 * lock (1). We then repeat the process recursively with those
48 * children.
49 *
50 */
51#include <linux/capability.h>
52#include <linux/file.h>
53#include <linux/fdtable.h>
54#include <linux/filelock.h>
55#include <linux/fs.h>
56#include <linux/init.h>
57#include <linux/security.h>
58#include <linux/slab.h>
59#include <linux/syscalls.h>
60#include <linux/time.h>
61#include <linux/rcupdate.h>
62#include <linux/pid_namespace.h>
63#include <linux/hashtable.h>
64#include <linux/percpu.h>
65#include <linux/sysctl.h>
66
67#define CREATE_TRACE_POINTS
68#include <trace/events/filelock.h>
69
70#include <linux/uaccess.h>
71
72static struct file_lock *file_lock(struct file_lock_core *flc)
73{
74 return container_of(flc, struct file_lock, c);
75}
76
77static struct file_lease *file_lease(struct file_lock_core *flc)
78{
79 return container_of(flc, struct file_lease, c);
80}
81
82static bool lease_breaking(struct file_lease *fl)
83{
84 return fl->c.flc_flags & (FL_UNLOCK_PENDING | FL_DOWNGRADE_PENDING);
85}
86
87static int target_leasetype(struct file_lease *fl)
88{
89 if (fl->c.flc_flags & FL_UNLOCK_PENDING)
90 return F_UNLCK;
91 if (fl->c.flc_flags & FL_DOWNGRADE_PENDING)
92 return F_RDLCK;
93 return fl->c.flc_type;
94}
95
96static int leases_enable = 1;
97static int lease_break_time = 45;
98
99#ifdef CONFIG_SYSCTL
100static struct ctl_table locks_sysctls[] = {
101 {
102 .procname = "leases-enable",
103 .data = &leases_enable,
104 .maxlen = sizeof(int),
105 .mode = 0644,
106 .proc_handler = proc_dointvec,
107 },
108#ifdef CONFIG_MMU
109 {
110 .procname = "lease-break-time",
111 .data = &lease_break_time,
112 .maxlen = sizeof(int),
113 .mode = 0644,
114 .proc_handler = proc_dointvec,
115 },
116#endif /* CONFIG_MMU */
117};
118
119static int __init init_fs_locks_sysctls(void)
120{
121 register_sysctl_init("fs", locks_sysctls);
122 return 0;
123}
124early_initcall(init_fs_locks_sysctls);
125#endif /* CONFIG_SYSCTL */
126
127/*
128 * The global file_lock_list is only used for displaying /proc/locks, so we
129 * keep a list on each CPU, with each list protected by its own spinlock.
130 * Global serialization is done using file_rwsem.
131 *
132 * Note that alterations to the list also require that the relevant flc_lock is
133 * held.
134 */
135struct file_lock_list_struct {
136 spinlock_t lock;
137 struct hlist_head hlist;
138};
139static DEFINE_PER_CPU(struct file_lock_list_struct, file_lock_list);
140DEFINE_STATIC_PERCPU_RWSEM(file_rwsem);
141
142
143/*
144 * The blocked_hash is used to find POSIX lock loops for deadlock detection.
145 * It is protected by blocked_lock_lock.
146 *
147 * We hash locks by lockowner in order to optimize searching for the lock a
148 * particular lockowner is waiting on.
149 *
150 * FIXME: make this value scale via some heuristic? We generally will want more
151 * buckets when we have more lockowners holding locks, but that's a little
152 * difficult to determine without knowing what the workload will look like.
153 */
154#define BLOCKED_HASH_BITS 7
155static DEFINE_HASHTABLE(blocked_hash, BLOCKED_HASH_BITS);
156
157/*
158 * This lock protects the blocked_hash. Generally, if you're accessing it, you
159 * want to be holding this lock.
160 *
161 * In addition, it also protects the fl->fl_blocked_requests list, and the
162 * fl->fl_blocker pointer for file_lock structures that are acting as lock
163 * requests (in contrast to those that are acting as records of acquired locks).
164 *
165 * Note that when we acquire this lock in order to change the above fields,
166 * we often hold the flc_lock as well. In certain cases, when reading the fields
167 * protected by this lock, we can skip acquiring it iff we already hold the
168 * flc_lock.
169 */
170static DEFINE_SPINLOCK(blocked_lock_lock);
171
172static struct kmem_cache *flctx_cache __ro_after_init;
173static struct kmem_cache *filelock_cache __ro_after_init;
174static struct kmem_cache *filelease_cache __ro_after_init;
175
176static struct file_lock_context *
177locks_get_lock_context(struct inode *inode, int type)
178{
179 struct file_lock_context *ctx;
180
181 /* paired with cmpxchg() below */
182 ctx = locks_inode_context(inode);
183 if (likely(ctx) || type == F_UNLCK)
184 goto out;
185
186 ctx = kmem_cache_alloc(flctx_cache, GFP_KERNEL);
187 if (!ctx)
188 goto out;
189
190 spin_lock_init(&ctx->flc_lock);
191 INIT_LIST_HEAD(&ctx->flc_flock);
192 INIT_LIST_HEAD(&ctx->flc_posix);
193 INIT_LIST_HEAD(&ctx->flc_lease);
194
195 /*
196 * Assign the pointer if it's not already assigned. If it is, then
197 * free the context we just allocated.
198 */
199 if (cmpxchg(&inode->i_flctx, NULL, ctx)) {
200 kmem_cache_free(flctx_cache, ctx);
201 ctx = locks_inode_context(inode);
202 }
203out:
204 trace_locks_get_lock_context(inode, type, ctx);
205 return ctx;
206}
207
208static void
209locks_dump_ctx_list(struct list_head *list, char *list_type)
210{
211 struct file_lock_core *flc;
212
213 list_for_each_entry(flc, list, flc_list)
214 pr_warn("%s: fl_owner=%p fl_flags=0x%x fl_type=0x%x fl_pid=%u\n",
215 list_type, flc->flc_owner, flc->flc_flags,
216 flc->flc_type, flc->flc_pid);
217}
218
219static void
220locks_check_ctx_lists(struct inode *inode)
221{
222 struct file_lock_context *ctx = inode->i_flctx;
223
224 if (unlikely(!list_empty(&ctx->flc_flock) ||
225 !list_empty(&ctx->flc_posix) ||
226 !list_empty(&ctx->flc_lease))) {
227 pr_warn("Leaked locks on dev=0x%x:0x%x ino=0x%lx:\n",
228 MAJOR(inode->i_sb->s_dev), MINOR(inode->i_sb->s_dev),
229 inode->i_ino);
230 locks_dump_ctx_list(&ctx->flc_flock, "FLOCK");
231 locks_dump_ctx_list(&ctx->flc_posix, "POSIX");
232 locks_dump_ctx_list(&ctx->flc_lease, "LEASE");
233 }
234}
235
236static void
237locks_check_ctx_file_list(struct file *filp, struct list_head *list, char *list_type)
238{
239 struct file_lock_core *flc;
240 struct inode *inode = file_inode(filp);
241
242 list_for_each_entry(flc, list, flc_list)
243 if (flc->flc_file == filp)
244 pr_warn("Leaked %s lock on dev=0x%x:0x%x ino=0x%lx "
245 " fl_owner=%p fl_flags=0x%x fl_type=0x%x fl_pid=%u\n",
246 list_type, MAJOR(inode->i_sb->s_dev),
247 MINOR(inode->i_sb->s_dev), inode->i_ino,
248 flc->flc_owner, flc->flc_flags,
249 flc->flc_type, flc->flc_pid);
250}
251
252void
253locks_free_lock_context(struct inode *inode)
254{
255 struct file_lock_context *ctx = locks_inode_context(inode);
256
257 if (unlikely(ctx)) {
258 locks_check_ctx_lists(inode);
259 kmem_cache_free(flctx_cache, ctx);
260 }
261}
262
263static void locks_init_lock_heads(struct file_lock_core *flc)
264{
265 INIT_HLIST_NODE(&flc->flc_link);
266 INIT_LIST_HEAD(&flc->flc_list);
267 INIT_LIST_HEAD(&flc->flc_blocked_requests);
268 INIT_LIST_HEAD(&flc->flc_blocked_member);
269 init_waitqueue_head(&flc->flc_wait);
270}
271
272/* Allocate an empty lock structure. */
273struct file_lock *locks_alloc_lock(void)
274{
275 struct file_lock *fl = kmem_cache_zalloc(filelock_cache, GFP_KERNEL);
276
277 if (fl)
278 locks_init_lock_heads(&fl->c);
279
280 return fl;
281}
282EXPORT_SYMBOL_GPL(locks_alloc_lock);
283
284/* Allocate an empty lock structure. */
285struct file_lease *locks_alloc_lease(void)
286{
287 struct file_lease *fl = kmem_cache_zalloc(filelease_cache, GFP_KERNEL);
288
289 if (fl)
290 locks_init_lock_heads(&fl->c);
291
292 return fl;
293}
294EXPORT_SYMBOL_GPL(locks_alloc_lease);
295
296void locks_release_private(struct file_lock *fl)
297{
298 struct file_lock_core *flc = &fl->c;
299
300 BUG_ON(waitqueue_active(&flc->flc_wait));
301 BUG_ON(!list_empty(&flc->flc_list));
302 BUG_ON(!list_empty(&flc->flc_blocked_requests));
303 BUG_ON(!list_empty(&flc->flc_blocked_member));
304 BUG_ON(!hlist_unhashed(&flc->flc_link));
305
306 if (fl->fl_ops) {
307 if (fl->fl_ops->fl_release_private)
308 fl->fl_ops->fl_release_private(fl);
309 fl->fl_ops = NULL;
310 }
311
312 if (fl->fl_lmops) {
313 if (fl->fl_lmops->lm_put_owner) {
314 fl->fl_lmops->lm_put_owner(flc->flc_owner);
315 flc->flc_owner = NULL;
316 }
317 fl->fl_lmops = NULL;
318 }
319}
320EXPORT_SYMBOL_GPL(locks_release_private);
321
322/**
323 * locks_owner_has_blockers - Check for blocking lock requests
324 * @flctx: file lock context
325 * @owner: lock owner
326 *
327 * Return values:
328 * %true: @owner has at least one blocker
329 * %false: @owner has no blockers
330 */
331bool locks_owner_has_blockers(struct file_lock_context *flctx, fl_owner_t owner)
332{
333 struct file_lock_core *flc;
334
335 spin_lock(&flctx->flc_lock);
336 list_for_each_entry(flc, &flctx->flc_posix, flc_list) {
337 if (flc->flc_owner != owner)
338 continue;
339 if (!list_empty(&flc->flc_blocked_requests)) {
340 spin_unlock(&flctx->flc_lock);
341 return true;
342 }
343 }
344 spin_unlock(&flctx->flc_lock);
345 return false;
346}
347EXPORT_SYMBOL_GPL(locks_owner_has_blockers);
348
349/* Free a lock which is not in use. */
350void locks_free_lock(struct file_lock *fl)
351{
352 locks_release_private(fl);
353 kmem_cache_free(filelock_cache, fl);
354}
355EXPORT_SYMBOL(locks_free_lock);
356
357/* Free a lease which is not in use. */
358void locks_free_lease(struct file_lease *fl)
359{
360 kmem_cache_free(filelease_cache, fl);
361}
362EXPORT_SYMBOL(locks_free_lease);
363
364static void
365locks_dispose_list(struct list_head *dispose)
366{
367 struct file_lock_core *flc;
368
369 while (!list_empty(dispose)) {
370 flc = list_first_entry(dispose, struct file_lock_core, flc_list);
371 list_del_init(&flc->flc_list);
372 if (flc->flc_flags & (FL_LEASE|FL_DELEG|FL_LAYOUT))
373 locks_free_lease(file_lease(flc));
374 else
375 locks_free_lock(file_lock(flc));
376 }
377}
378
379void locks_init_lock(struct file_lock *fl)
380{
381 memset(fl, 0, sizeof(struct file_lock));
382 locks_init_lock_heads(&fl->c);
383}
384EXPORT_SYMBOL(locks_init_lock);
385
386void locks_init_lease(struct file_lease *fl)
387{
388 memset(fl, 0, sizeof(*fl));
389 locks_init_lock_heads(&fl->c);
390}
391EXPORT_SYMBOL(locks_init_lease);
392
393/*
394 * Initialize a new lock from an existing file_lock structure.
395 */
396void locks_copy_conflock(struct file_lock *new, struct file_lock *fl)
397{
398 new->c.flc_owner = fl->c.flc_owner;
399 new->c.flc_pid = fl->c.flc_pid;
400 new->c.flc_file = NULL;
401 new->c.flc_flags = fl->c.flc_flags;
402 new->c.flc_type = fl->c.flc_type;
403 new->fl_start = fl->fl_start;
404 new->fl_end = fl->fl_end;
405 new->fl_lmops = fl->fl_lmops;
406 new->fl_ops = NULL;
407
408 if (fl->fl_lmops) {
409 if (fl->fl_lmops->lm_get_owner)
410 fl->fl_lmops->lm_get_owner(fl->c.flc_owner);
411 }
412}
413EXPORT_SYMBOL(locks_copy_conflock);
414
415void locks_copy_lock(struct file_lock *new, struct file_lock *fl)
416{
417 /* "new" must be a freshly-initialized lock */
418 WARN_ON_ONCE(new->fl_ops);
419
420 locks_copy_conflock(new, fl);
421
422 new->c.flc_file = fl->c.flc_file;
423 new->fl_ops = fl->fl_ops;
424
425 if (fl->fl_ops) {
426 if (fl->fl_ops->fl_copy_lock)
427 fl->fl_ops->fl_copy_lock(new, fl);
428 }
429}
430EXPORT_SYMBOL(locks_copy_lock);
431
432static void locks_move_blocks(struct file_lock *new, struct file_lock *fl)
433{
434 struct file_lock *f;
435
436 /*
437 * As ctx->flc_lock is held, new requests cannot be added to
438 * ->flc_blocked_requests, so we don't need a lock to check if it
439 * is empty.
440 */
441 if (list_empty(&fl->c.flc_blocked_requests))
442 return;
443 spin_lock(&blocked_lock_lock);
444 list_splice_init(&fl->c.flc_blocked_requests,
445 &new->c.flc_blocked_requests);
446 list_for_each_entry(f, &new->c.flc_blocked_requests,
447 c.flc_blocked_member)
448 f->c.flc_blocker = &new->c;
449 spin_unlock(&blocked_lock_lock);
450}
451
452static inline int flock_translate_cmd(int cmd) {
453 switch (cmd) {
454 case LOCK_SH:
455 return F_RDLCK;
456 case LOCK_EX:
457 return F_WRLCK;
458 case LOCK_UN:
459 return F_UNLCK;
460 }
461 return -EINVAL;
462}
463
464/* Fill in a file_lock structure with an appropriate FLOCK lock. */
465static void flock_make_lock(struct file *filp, struct file_lock *fl, int type)
466{
467 locks_init_lock(fl);
468
469 fl->c.flc_file = filp;
470 fl->c.flc_owner = filp;
471 fl->c.flc_pid = current->tgid;
472 fl->c.flc_flags = FL_FLOCK;
473 fl->c.flc_type = type;
474 fl->fl_end = OFFSET_MAX;
475}
476
477static int assign_type(struct file_lock_core *flc, int type)
478{
479 switch (type) {
480 case F_RDLCK:
481 case F_WRLCK:
482 case F_UNLCK:
483 flc->flc_type = type;
484 break;
485 default:
486 return -EINVAL;
487 }
488 return 0;
489}
490
491static int flock64_to_posix_lock(struct file *filp, struct file_lock *fl,
492 struct flock64 *l)
493{
494 switch (l->l_whence) {
495 case SEEK_SET:
496 fl->fl_start = 0;
497 break;
498 case SEEK_CUR:
499 fl->fl_start = filp->f_pos;
500 break;
501 case SEEK_END:
502 fl->fl_start = i_size_read(file_inode(filp));
503 break;
504 default:
505 return -EINVAL;
506 }
507 if (l->l_start > OFFSET_MAX - fl->fl_start)
508 return -EOVERFLOW;
509 fl->fl_start += l->l_start;
510 if (fl->fl_start < 0)
511 return -EINVAL;
512
513 /* POSIX-1996 leaves the case l->l_len < 0 undefined;
514 POSIX-2001 defines it. */
515 if (l->l_len > 0) {
516 if (l->l_len - 1 > OFFSET_MAX - fl->fl_start)
517 return -EOVERFLOW;
518 fl->fl_end = fl->fl_start + (l->l_len - 1);
519
520 } else if (l->l_len < 0) {
521 if (fl->fl_start + l->l_len < 0)
522 return -EINVAL;
523 fl->fl_end = fl->fl_start - 1;
524 fl->fl_start += l->l_len;
525 } else
526 fl->fl_end = OFFSET_MAX;
527
528 fl->c.flc_owner = current->files;
529 fl->c.flc_pid = current->tgid;
530 fl->c.flc_file = filp;
531 fl->c.flc_flags = FL_POSIX;
532 fl->fl_ops = NULL;
533 fl->fl_lmops = NULL;
534
535 return assign_type(&fl->c, l->l_type);
536}
537
538/* Verify a "struct flock" and copy it to a "struct file_lock" as a POSIX
539 * style lock.
540 */
541static int flock_to_posix_lock(struct file *filp, struct file_lock *fl,
542 struct flock *l)
543{
544 struct flock64 ll = {
545 .l_type = l->l_type,
546 .l_whence = l->l_whence,
547 .l_start = l->l_start,
548 .l_len = l->l_len,
549 };
550
551 return flock64_to_posix_lock(filp, fl, &ll);
552}
553
554/* default lease lock manager operations */
555static bool
556lease_break_callback(struct file_lease *fl)
557{
558 kill_fasync(&fl->fl_fasync, SIGIO, POLL_MSG);
559 return false;
560}
561
562static void
563lease_setup(struct file_lease *fl, void **priv)
564{
565 struct file *filp = fl->c.flc_file;
566 struct fasync_struct *fa = *priv;
567
568 /*
569 * fasync_insert_entry() returns the old entry if any. If there was no
570 * old entry, then it used "priv" and inserted it into the fasync list.
571 * Clear the pointer to indicate that it shouldn't be freed.
572 */
573 if (!fasync_insert_entry(fa->fa_fd, filp, &fl->fl_fasync, fa))
574 *priv = NULL;
575
576 __f_setown(filp, task_pid(current), PIDTYPE_TGID, 0);
577}
578
579static const struct lease_manager_operations lease_manager_ops = {
580 .lm_break = lease_break_callback,
581 .lm_change = lease_modify,
582 .lm_setup = lease_setup,
583};
584
585/*
586 * Initialize a lease, use the default lock manager operations
587 */
588static int lease_init(struct file *filp, int type, struct file_lease *fl)
589{
590 if (assign_type(&fl->c, type) != 0)
591 return -EINVAL;
592
593 fl->c.flc_owner = filp;
594 fl->c.flc_pid = current->tgid;
595
596 fl->c.flc_file = filp;
597 fl->c.flc_flags = FL_LEASE;
598 fl->fl_lmops = &lease_manager_ops;
599 return 0;
600}
601
602/* Allocate a file_lock initialised to this type of lease */
603static struct file_lease *lease_alloc(struct file *filp, int type)
604{
605 struct file_lease *fl = locks_alloc_lease();
606 int error = -ENOMEM;
607
608 if (fl == NULL)
609 return ERR_PTR(error);
610
611 error = lease_init(filp, type, fl);
612 if (error) {
613 locks_free_lease(fl);
614 return ERR_PTR(error);
615 }
616 return fl;
617}
618
619/* Check if two locks overlap each other.
620 */
621static inline int locks_overlap(struct file_lock *fl1, struct file_lock *fl2)
622{
623 return ((fl1->fl_end >= fl2->fl_start) &&
624 (fl2->fl_end >= fl1->fl_start));
625}
626
627/*
628 * Check whether two locks have the same owner.
629 */
630static int posix_same_owner(struct file_lock_core *fl1, struct file_lock_core *fl2)
631{
632 return fl1->flc_owner == fl2->flc_owner;
633}
634
635/* Must be called with the flc_lock held! */
636static void locks_insert_global_locks(struct file_lock_core *flc)
637{
638 struct file_lock_list_struct *fll = this_cpu_ptr(&file_lock_list);
639
640 percpu_rwsem_assert_held(&file_rwsem);
641
642 spin_lock(&fll->lock);
643 flc->flc_link_cpu = smp_processor_id();
644 hlist_add_head(&flc->flc_link, &fll->hlist);
645 spin_unlock(&fll->lock);
646}
647
648/* Must be called with the flc_lock held! */
649static void locks_delete_global_locks(struct file_lock_core *flc)
650{
651 struct file_lock_list_struct *fll;
652
653 percpu_rwsem_assert_held(&file_rwsem);
654
655 /*
656 * Avoid taking lock if already unhashed. This is safe since this check
657 * is done while holding the flc_lock, and new insertions into the list
658 * also require that it be held.
659 */
660 if (hlist_unhashed(&flc->flc_link))
661 return;
662
663 fll = per_cpu_ptr(&file_lock_list, flc->flc_link_cpu);
664 spin_lock(&fll->lock);
665 hlist_del_init(&flc->flc_link);
666 spin_unlock(&fll->lock);
667}
668
669static unsigned long
670posix_owner_key(struct file_lock_core *flc)
671{
672 return (unsigned long) flc->flc_owner;
673}
674
675static void locks_insert_global_blocked(struct file_lock_core *waiter)
676{
677 lockdep_assert_held(&blocked_lock_lock);
678
679 hash_add(blocked_hash, &waiter->flc_link, posix_owner_key(waiter));
680}
681
682static void locks_delete_global_blocked(struct file_lock_core *waiter)
683{
684 lockdep_assert_held(&blocked_lock_lock);
685
686 hash_del(&waiter->flc_link);
687}
688
689/* Remove waiter from blocker's block list.
690 * When blocker ends up pointing to itself then the list is empty.
691 *
692 * Must be called with blocked_lock_lock held.
693 */
694static void __locks_unlink_block(struct file_lock_core *waiter)
695{
696 locks_delete_global_blocked(waiter);
697 list_del_init(&waiter->flc_blocked_member);
698}
699
700static void __locks_wake_up_blocks(struct file_lock_core *blocker)
701{
702 while (!list_empty(&blocker->flc_blocked_requests)) {
703 struct file_lock_core *waiter;
704 struct file_lock *fl;
705
706 waiter = list_first_entry(&blocker->flc_blocked_requests,
707 struct file_lock_core, flc_blocked_member);
708
709 fl = file_lock(waiter);
710 __locks_unlink_block(waiter);
711 if ((waiter->flc_flags & (FL_POSIX | FL_FLOCK)) &&
712 fl->fl_lmops && fl->fl_lmops->lm_notify)
713 fl->fl_lmops->lm_notify(fl);
714 else
715 locks_wake_up(fl);
716
717 /*
718 * The setting of flc_blocker to NULL marks the "done"
719 * point in deleting a block. Paired with acquire at the top
720 * of locks_delete_block().
721 */
722 smp_store_release(&waiter->flc_blocker, NULL);
723 }
724}
725
726static int __locks_delete_block(struct file_lock_core *waiter)
727{
728 int status = -ENOENT;
729
730 /*
731 * If fl_blocker is NULL, it won't be set again as this thread "owns"
732 * the lock and is the only one that might try to claim the lock.
733 *
734 * We use acquire/release to manage fl_blocker so that we can
735 * optimize away taking the blocked_lock_lock in many cases.
736 *
737 * The smp_load_acquire guarantees two things:
738 *
739 * 1/ that fl_blocked_requests can be tested locklessly. If something
740 * was recently added to that list it must have been in a locked region
741 * *before* the locked region when fl_blocker was set to NULL.
742 *
743 * 2/ that no other thread is accessing 'waiter', so it is safe to free
744 * it. __locks_wake_up_blocks is careful not to touch waiter after
745 * fl_blocker is released.
746 *
747 * If a lockless check of fl_blocker shows it to be NULL, we know that
748 * no new locks can be inserted into its fl_blocked_requests list, and
749 * can avoid doing anything further if the list is empty.
750 */
751 if (!smp_load_acquire(&waiter->flc_blocker) &&
752 list_empty(&waiter->flc_blocked_requests))
753 return status;
754
755 spin_lock(&blocked_lock_lock);
756 if (waiter->flc_blocker)
757 status = 0;
758 __locks_wake_up_blocks(waiter);
759 __locks_unlink_block(waiter);
760
761 /*
762 * The setting of fl_blocker to NULL marks the "done" point in deleting
763 * a block. Paired with acquire at the top of this function.
764 */
765 smp_store_release(&waiter->flc_blocker, NULL);
766 spin_unlock(&blocked_lock_lock);
767 return status;
768}
769
770/**
771 * locks_delete_block - stop waiting for a file lock
772 * @waiter: the lock which was waiting
773 *
774 * lockd/nfsd need to disconnect the lock while working on it.
775 */
776int locks_delete_block(struct file_lock *waiter)
777{
778 return __locks_delete_block(&waiter->c);
779}
780EXPORT_SYMBOL(locks_delete_block);
781
782/* Insert waiter into blocker's block list.
783 * We use a circular list so that processes can be easily woken up in
784 * the order they blocked. The documentation doesn't require this but
785 * it seems like the reasonable thing to do.
786 *
787 * Must be called with both the flc_lock and blocked_lock_lock held. The
788 * fl_blocked_requests list itself is protected by the blocked_lock_lock,
789 * but by ensuring that the flc_lock is also held on insertions we can avoid
790 * taking the blocked_lock_lock in some cases when we see that the
791 * fl_blocked_requests list is empty.
792 *
793 * Rather than just adding to the list, we check for conflicts with any existing
794 * waiters, and add beneath any waiter that blocks the new waiter.
795 * Thus wakeups don't happen until needed.
796 */
797static void __locks_insert_block(struct file_lock_core *blocker,
798 struct file_lock_core *waiter,
799 bool conflict(struct file_lock_core *,
800 struct file_lock_core *))
801{
802 struct file_lock_core *flc;
803
804 BUG_ON(!list_empty(&waiter->flc_blocked_member));
805new_blocker:
806 list_for_each_entry(flc, &blocker->flc_blocked_requests, flc_blocked_member)
807 if (conflict(flc, waiter)) {
808 blocker = flc;
809 goto new_blocker;
810 }
811 waiter->flc_blocker = blocker;
812 list_add_tail(&waiter->flc_blocked_member,
813 &blocker->flc_blocked_requests);
814
815 if ((blocker->flc_flags & (FL_POSIX|FL_OFDLCK)) == FL_POSIX)
816 locks_insert_global_blocked(waiter);
817
818 /* The requests in waiter->flc_blocked are known to conflict with
819 * waiter, but might not conflict with blocker, or the requests
820 * and lock which block it. So they all need to be woken.
821 */
822 __locks_wake_up_blocks(waiter);
823}
824
825/* Must be called with flc_lock held. */
826static void locks_insert_block(struct file_lock_core *blocker,
827 struct file_lock_core *waiter,
828 bool conflict(struct file_lock_core *,
829 struct file_lock_core *))
830{
831 spin_lock(&blocked_lock_lock);
832 __locks_insert_block(blocker, waiter, conflict);
833 spin_unlock(&blocked_lock_lock);
834}
835
836/*
837 * Wake up processes blocked waiting for blocker.
838 *
839 * Must be called with the inode->flc_lock held!
840 */
841static void locks_wake_up_blocks(struct file_lock_core *blocker)
842{
843 /*
844 * Avoid taking global lock if list is empty. This is safe since new
845 * blocked requests are only added to the list under the flc_lock, and
846 * the flc_lock is always held here. Note that removal from the
847 * fl_blocked_requests list does not require the flc_lock, so we must
848 * recheck list_empty() after acquiring the blocked_lock_lock.
849 */
850 if (list_empty(&blocker->flc_blocked_requests))
851 return;
852
853 spin_lock(&blocked_lock_lock);
854 __locks_wake_up_blocks(blocker);
855 spin_unlock(&blocked_lock_lock);
856}
857
858static void
859locks_insert_lock_ctx(struct file_lock_core *fl, struct list_head *before)
860{
861 list_add_tail(&fl->flc_list, before);
862 locks_insert_global_locks(fl);
863}
864
865static void
866locks_unlink_lock_ctx(struct file_lock_core *fl)
867{
868 locks_delete_global_locks(fl);
869 list_del_init(&fl->flc_list);
870 locks_wake_up_blocks(fl);
871}
872
873static void
874locks_delete_lock_ctx(struct file_lock_core *fl, struct list_head *dispose)
875{
876 locks_unlink_lock_ctx(fl);
877 if (dispose)
878 list_add(&fl->flc_list, dispose);
879 else
880 locks_free_lock(file_lock(fl));
881}
882
883/* Determine if lock sys_fl blocks lock caller_fl. Common functionality
884 * checks for shared/exclusive status of overlapping locks.
885 */
886static bool locks_conflict(struct file_lock_core *caller_flc,
887 struct file_lock_core *sys_flc)
888{
889 if (sys_flc->flc_type == F_WRLCK)
890 return true;
891 if (caller_flc->flc_type == F_WRLCK)
892 return true;
893 return false;
894}
895
896/* Determine if lock sys_fl blocks lock caller_fl. POSIX specific
897 * checking before calling the locks_conflict().
898 */
899static bool posix_locks_conflict(struct file_lock_core *caller_flc,
900 struct file_lock_core *sys_flc)
901{
902 struct file_lock *caller_fl = file_lock(caller_flc);
903 struct file_lock *sys_fl = file_lock(sys_flc);
904
905 /* POSIX locks owned by the same process do not conflict with
906 * each other.
907 */
908 if (posix_same_owner(caller_flc, sys_flc))
909 return false;
910
911 /* Check whether they overlap */
912 if (!locks_overlap(caller_fl, sys_fl))
913 return false;
914
915 return locks_conflict(caller_flc, sys_flc);
916}
917
918/* Determine if lock sys_fl blocks lock caller_fl. Used on xx_GETLK
919 * path so checks for additional GETLK-specific things like F_UNLCK.
920 */
921static bool posix_test_locks_conflict(struct file_lock *caller_fl,
922 struct file_lock *sys_fl)
923{
924 struct file_lock_core *caller = &caller_fl->c;
925 struct file_lock_core *sys = &sys_fl->c;
926
927 /* F_UNLCK checks any locks on the same fd. */
928 if (lock_is_unlock(caller_fl)) {
929 if (!posix_same_owner(caller, sys))
930 return false;
931 return locks_overlap(caller_fl, sys_fl);
932 }
933 return posix_locks_conflict(caller, sys);
934}
935
936/* Determine if lock sys_fl blocks lock caller_fl. FLOCK specific
937 * checking before calling the locks_conflict().
938 */
939static bool flock_locks_conflict(struct file_lock_core *caller_flc,
940 struct file_lock_core *sys_flc)
941{
942 /* FLOCK locks referring to the same filp do not conflict with
943 * each other.
944 */
945 if (caller_flc->flc_file == sys_flc->flc_file)
946 return false;
947
948 return locks_conflict(caller_flc, sys_flc);
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 = file_inode(filp);
957 void *owner;
958 void (*func)(void);
959
960 ctx = locks_inode_context(inode);
961 if (!ctx || list_empty_careful(&ctx->flc_posix)) {
962 fl->c.flc_type = F_UNLCK;
963 return;
964 }
965
966retry:
967 spin_lock(&ctx->flc_lock);
968 list_for_each_entry(cfl, &ctx->flc_posix, c.flc_list) {
969 if (!posix_test_locks_conflict(fl, cfl))
970 continue;
971 if (cfl->fl_lmops && cfl->fl_lmops->lm_lock_expirable
972 && (*cfl->fl_lmops->lm_lock_expirable)(cfl)) {
973 owner = cfl->fl_lmops->lm_mod_owner;
974 func = cfl->fl_lmops->lm_expire_lock;
975 __module_get(owner);
976 spin_unlock(&ctx->flc_lock);
977 (*func)();
978 module_put(owner);
979 goto retry;
980 }
981 locks_copy_conflock(fl, cfl);
982 goto out;
983 }
984 fl->c.flc_type = F_UNLCK;
985out:
986 spin_unlock(&ctx->flc_lock);
987 return;
988}
989EXPORT_SYMBOL(posix_test_lock);
990
991/*
992 * Deadlock detection:
993 *
994 * We attempt to detect deadlocks that are due purely to posix file
995 * locks.
996 *
997 * We assume that a task can be waiting for at most one lock at a time.
998 * So for any acquired lock, the process holding that lock may be
999 * waiting on at most one other lock. That lock in turns may be held by
1000 * someone waiting for at most one other lock. Given a requested lock
1001 * caller_fl which is about to wait for a conflicting lock block_fl, we
1002 * follow this chain of waiters to ensure we are not about to create a
1003 * cycle.
1004 *
1005 * Since we do this before we ever put a process to sleep on a lock, we
1006 * are ensured that there is never a cycle; that is what guarantees that
1007 * the while() loop in posix_locks_deadlock() eventually completes.
1008 *
1009 * Note: the above assumption may not be true when handling lock
1010 * requests from a broken NFS client. It may also fail in the presence
1011 * of tasks (such as posix threads) sharing the same open file table.
1012 * To handle those cases, we just bail out after a few iterations.
1013 *
1014 * For FL_OFDLCK locks, the owner is the filp, not the files_struct.
1015 * Because the owner is not even nominally tied to a thread of
1016 * execution, the deadlock detection below can't reasonably work well. Just
1017 * skip it for those.
1018 *
1019 * In principle, we could do a more limited deadlock detection on FL_OFDLCK
1020 * locks that just checks for the case where two tasks are attempting to
1021 * upgrade from read to write locks on the same inode.
1022 */
1023
1024#define MAX_DEADLK_ITERATIONS 10
1025
1026/* Find a lock that the owner of the given @blocker is blocking on. */
1027static struct file_lock_core *what_owner_is_waiting_for(struct file_lock_core *blocker)
1028{
1029 struct file_lock_core *flc;
1030
1031 hash_for_each_possible(blocked_hash, flc, flc_link, posix_owner_key(blocker)) {
1032 if (posix_same_owner(flc, blocker)) {
1033 while (flc->flc_blocker)
1034 flc = flc->flc_blocker;
1035 return flc;
1036 }
1037 }
1038 return NULL;
1039}
1040
1041/* Must be called with the blocked_lock_lock held! */
1042static bool posix_locks_deadlock(struct file_lock *caller_fl,
1043 struct file_lock *block_fl)
1044{
1045 struct file_lock_core *caller = &caller_fl->c;
1046 struct file_lock_core *blocker = &block_fl->c;
1047 int i = 0;
1048
1049 lockdep_assert_held(&blocked_lock_lock);
1050
1051 /*
1052 * This deadlock detector can't reasonably detect deadlocks with
1053 * FL_OFDLCK locks, since they aren't owned by a process, per-se.
1054 */
1055 if (caller->flc_flags & FL_OFDLCK)
1056 return false;
1057
1058 while ((blocker = what_owner_is_waiting_for(blocker))) {
1059 if (i++ > MAX_DEADLK_ITERATIONS)
1060 return false;
1061 if (posix_same_owner(caller, blocker))
1062 return true;
1063 }
1064 return false;
1065}
1066
1067/* Try to create a FLOCK lock on filp. We always insert new FLOCK locks
1068 * after any leases, but before any posix locks.
1069 *
1070 * Note that if called with an FL_EXISTS argument, the caller may determine
1071 * whether or not a lock was successfully freed by testing the return
1072 * value for -ENOENT.
1073 */
1074static int flock_lock_inode(struct inode *inode, struct file_lock *request)
1075{
1076 struct file_lock *new_fl = NULL;
1077 struct file_lock *fl;
1078 struct file_lock_context *ctx;
1079 int error = 0;
1080 bool found = false;
1081 LIST_HEAD(dispose);
1082
1083 ctx = locks_get_lock_context(inode, request->c.flc_type);
1084 if (!ctx) {
1085 if (request->c.flc_type != F_UNLCK)
1086 return -ENOMEM;
1087 return (request->c.flc_flags & FL_EXISTS) ? -ENOENT : 0;
1088 }
1089
1090 if (!(request->c.flc_flags & FL_ACCESS) && (request->c.flc_type != F_UNLCK)) {
1091 new_fl = locks_alloc_lock();
1092 if (!new_fl)
1093 return -ENOMEM;
1094 }
1095
1096 percpu_down_read(&file_rwsem);
1097 spin_lock(&ctx->flc_lock);
1098 if (request->c.flc_flags & FL_ACCESS)
1099 goto find_conflict;
1100
1101 list_for_each_entry(fl, &ctx->flc_flock, c.flc_list) {
1102 if (request->c.flc_file != fl->c.flc_file)
1103 continue;
1104 if (request->c.flc_type == fl->c.flc_type)
1105 goto out;
1106 found = true;
1107 locks_delete_lock_ctx(&fl->c, &dispose);
1108 break;
1109 }
1110
1111 if (lock_is_unlock(request)) {
1112 if ((request->c.flc_flags & FL_EXISTS) && !found)
1113 error = -ENOENT;
1114 goto out;
1115 }
1116
1117find_conflict:
1118 list_for_each_entry(fl, &ctx->flc_flock, c.flc_list) {
1119 if (!flock_locks_conflict(&request->c, &fl->c))
1120 continue;
1121 error = -EAGAIN;
1122 if (!(request->c.flc_flags & FL_SLEEP))
1123 goto out;
1124 error = FILE_LOCK_DEFERRED;
1125 locks_insert_block(&fl->c, &request->c, flock_locks_conflict);
1126 goto out;
1127 }
1128 if (request->c.flc_flags & FL_ACCESS)
1129 goto out;
1130 locks_copy_lock(new_fl, request);
1131 locks_move_blocks(new_fl, request);
1132 locks_insert_lock_ctx(&new_fl->c, &ctx->flc_flock);
1133 new_fl = NULL;
1134 error = 0;
1135
1136out:
1137 spin_unlock(&ctx->flc_lock);
1138 percpu_up_read(&file_rwsem);
1139 if (new_fl)
1140 locks_free_lock(new_fl);
1141 locks_dispose_list(&dispose);
1142 trace_flock_lock_inode(inode, request, error);
1143 return error;
1144}
1145
1146static int posix_lock_inode(struct inode *inode, struct file_lock *request,
1147 struct file_lock *conflock)
1148{
1149 struct file_lock *fl, *tmp;
1150 struct file_lock *new_fl = NULL;
1151 struct file_lock *new_fl2 = NULL;
1152 struct file_lock *left = NULL;
1153 struct file_lock *right = NULL;
1154 struct file_lock_context *ctx;
1155 int error;
1156 bool added = false;
1157 LIST_HEAD(dispose);
1158 void *owner;
1159 void (*func)(void);
1160
1161 ctx = locks_get_lock_context(inode, request->c.flc_type);
1162 if (!ctx)
1163 return lock_is_unlock(request) ? 0 : -ENOMEM;
1164
1165 /*
1166 * We may need two file_lock structures for this operation,
1167 * so we get them in advance to avoid races.
1168 *
1169 * In some cases we can be sure, that no new locks will be needed
1170 */
1171 if (!(request->c.flc_flags & FL_ACCESS) &&
1172 (request->c.flc_type != F_UNLCK ||
1173 request->fl_start != 0 || request->fl_end != OFFSET_MAX)) {
1174 new_fl = locks_alloc_lock();
1175 new_fl2 = locks_alloc_lock();
1176 }
1177
1178retry:
1179 percpu_down_read(&file_rwsem);
1180 spin_lock(&ctx->flc_lock);
1181 /*
1182 * New lock request. Walk all POSIX locks and look for conflicts. If
1183 * there are any, either return error or put the request on the
1184 * blocker's list of waiters and the global blocked_hash.
1185 */
1186 if (request->c.flc_type != F_UNLCK) {
1187 list_for_each_entry(fl, &ctx->flc_posix, c.flc_list) {
1188 if (!posix_locks_conflict(&request->c, &fl->c))
1189 continue;
1190 if (fl->fl_lmops && fl->fl_lmops->lm_lock_expirable
1191 && (*fl->fl_lmops->lm_lock_expirable)(fl)) {
1192 owner = fl->fl_lmops->lm_mod_owner;
1193 func = fl->fl_lmops->lm_expire_lock;
1194 __module_get(owner);
1195 spin_unlock(&ctx->flc_lock);
1196 percpu_up_read(&file_rwsem);
1197 (*func)();
1198 module_put(owner);
1199 goto retry;
1200 }
1201 if (conflock)
1202 locks_copy_conflock(conflock, fl);
1203 error = -EAGAIN;
1204 if (!(request->c.flc_flags & FL_SLEEP))
1205 goto out;
1206 /*
1207 * Deadlock detection and insertion into the blocked
1208 * locks list must be done while holding the same lock!
1209 */
1210 error = -EDEADLK;
1211 spin_lock(&blocked_lock_lock);
1212 /*
1213 * Ensure that we don't find any locks blocked on this
1214 * request during deadlock detection.
1215 */
1216 __locks_wake_up_blocks(&request->c);
1217 if (likely(!posix_locks_deadlock(request, fl))) {
1218 error = FILE_LOCK_DEFERRED;
1219 __locks_insert_block(&fl->c, &request->c,
1220 posix_locks_conflict);
1221 }
1222 spin_unlock(&blocked_lock_lock);
1223 goto out;
1224 }
1225 }
1226
1227 /* If we're just looking for a conflict, we're done. */
1228 error = 0;
1229 if (request->c.flc_flags & FL_ACCESS)
1230 goto out;
1231
1232 /* Find the first old lock with the same owner as the new lock */
1233 list_for_each_entry(fl, &ctx->flc_posix, c.flc_list) {
1234 if (posix_same_owner(&request->c, &fl->c))
1235 break;
1236 }
1237
1238 /* Process locks with this owner. */
1239 list_for_each_entry_safe_from(fl, tmp, &ctx->flc_posix, c.flc_list) {
1240 if (!posix_same_owner(&request->c, &fl->c))
1241 break;
1242
1243 /* Detect adjacent or overlapping regions (if same lock type) */
1244 if (request->c.flc_type == fl->c.flc_type) {
1245 /* In all comparisons of start vs end, use
1246 * "start - 1" rather than "end + 1". If end
1247 * is OFFSET_MAX, end + 1 will become negative.
1248 */
1249 if (fl->fl_end < request->fl_start - 1)
1250 continue;
1251 /* If the next lock in the list has entirely bigger
1252 * addresses than the new one, insert the lock here.
1253 */
1254 if (fl->fl_start - 1 > request->fl_end)
1255 break;
1256
1257 /* If we come here, the new and old lock are of the
1258 * same type and adjacent or overlapping. Make one
1259 * lock yielding from the lower start address of both
1260 * locks to the higher end address.
1261 */
1262 if (fl->fl_start > request->fl_start)
1263 fl->fl_start = request->fl_start;
1264 else
1265 request->fl_start = fl->fl_start;
1266 if (fl->fl_end < request->fl_end)
1267 fl->fl_end = request->fl_end;
1268 else
1269 request->fl_end = fl->fl_end;
1270 if (added) {
1271 locks_delete_lock_ctx(&fl->c, &dispose);
1272 continue;
1273 }
1274 request = fl;
1275 added = true;
1276 } else {
1277 /* Processing for different lock types is a bit
1278 * more complex.
1279 */
1280 if (fl->fl_end < request->fl_start)
1281 continue;
1282 if (fl->fl_start > request->fl_end)
1283 break;
1284 if (lock_is_unlock(request))
1285 added = true;
1286 if (fl->fl_start < request->fl_start)
1287 left = fl;
1288 /* If the next lock in the list has a higher end
1289 * address than the new one, insert the new one here.
1290 */
1291 if (fl->fl_end > request->fl_end) {
1292 right = fl;
1293 break;
1294 }
1295 if (fl->fl_start >= request->fl_start) {
1296 /* The new lock completely replaces an old
1297 * one (This may happen several times).
1298 */
1299 if (added) {
1300 locks_delete_lock_ctx(&fl->c, &dispose);
1301 continue;
1302 }
1303 /*
1304 * Replace the old lock with new_fl, and
1305 * remove the old one. It's safe to do the
1306 * insert here since we know that we won't be
1307 * using new_fl later, and that the lock is
1308 * just replacing an existing lock.
1309 */
1310 error = -ENOLCK;
1311 if (!new_fl)
1312 goto out;
1313 locks_copy_lock(new_fl, request);
1314 locks_move_blocks(new_fl, request);
1315 request = new_fl;
1316 new_fl = NULL;
1317 locks_insert_lock_ctx(&request->c,
1318 &fl->c.flc_list);
1319 locks_delete_lock_ctx(&fl->c, &dispose);
1320 added = true;
1321 }
1322 }
1323 }
1324
1325 /*
1326 * The above code only modifies existing locks in case of merging or
1327 * replacing. If new lock(s) need to be inserted all modifications are
1328 * done below this, so it's safe yet to bail out.
1329 */
1330 error = -ENOLCK; /* "no luck" */
1331 if (right && left == right && !new_fl2)
1332 goto out;
1333
1334 error = 0;
1335 if (!added) {
1336 if (lock_is_unlock(request)) {
1337 if (request->c.flc_flags & FL_EXISTS)
1338 error = -ENOENT;
1339 goto out;
1340 }
1341
1342 if (!new_fl) {
1343 error = -ENOLCK;
1344 goto out;
1345 }
1346 locks_copy_lock(new_fl, request);
1347 locks_move_blocks(new_fl, request);
1348 locks_insert_lock_ctx(&new_fl->c, &fl->c.flc_list);
1349 fl = new_fl;
1350 new_fl = NULL;
1351 }
1352 if (right) {
1353 if (left == right) {
1354 /* The new lock breaks the old one in two pieces,
1355 * so we have to use the second new lock.
1356 */
1357 left = new_fl2;
1358 new_fl2 = NULL;
1359 locks_copy_lock(left, right);
1360 locks_insert_lock_ctx(&left->c, &fl->c.flc_list);
1361 }
1362 right->fl_start = request->fl_end + 1;
1363 locks_wake_up_blocks(&right->c);
1364 }
1365 if (left) {
1366 left->fl_end = request->fl_start - 1;
1367 locks_wake_up_blocks(&left->c);
1368 }
1369 out:
1370 trace_posix_lock_inode(inode, request, error);
1371 spin_unlock(&ctx->flc_lock);
1372 percpu_up_read(&file_rwsem);
1373 /*
1374 * Free any unused locks.
1375 */
1376 if (new_fl)
1377 locks_free_lock(new_fl);
1378 if (new_fl2)
1379 locks_free_lock(new_fl2);
1380 locks_dispose_list(&dispose);
1381
1382 return error;
1383}
1384
1385/**
1386 * posix_lock_file - Apply a POSIX-style lock to a file
1387 * @filp: The file to apply the lock to
1388 * @fl: The lock to be applied
1389 * @conflock: Place to return a copy of the conflicting lock, if found.
1390 *
1391 * Add a POSIX style lock to a file.
1392 * We merge adjacent & overlapping locks whenever possible.
1393 * POSIX locks are sorted by owner task, then by starting address
1394 *
1395 * Note that if called with an FL_EXISTS argument, the caller may determine
1396 * whether or not a lock was successfully freed by testing the return
1397 * value for -ENOENT.
1398 */
1399int posix_lock_file(struct file *filp, struct file_lock *fl,
1400 struct file_lock *conflock)
1401{
1402 return posix_lock_inode(file_inode(filp), fl, conflock);
1403}
1404EXPORT_SYMBOL(posix_lock_file);
1405
1406/**
1407 * posix_lock_inode_wait - Apply a POSIX-style lock to a file
1408 * @inode: inode of file to which lock request should be applied
1409 * @fl: The lock to be applied
1410 *
1411 * Apply a POSIX style lock request to an inode.
1412 */
1413static int posix_lock_inode_wait(struct inode *inode, struct file_lock *fl)
1414{
1415 int error;
1416 might_sleep ();
1417 for (;;) {
1418 error = posix_lock_inode(inode, fl, NULL);
1419 if (error != FILE_LOCK_DEFERRED)
1420 break;
1421 error = wait_event_interruptible(fl->c.flc_wait,
1422 list_empty(&fl->c.flc_blocked_member));
1423 if (error)
1424 break;
1425 }
1426 locks_delete_block(fl);
1427 return error;
1428}
1429
1430static void lease_clear_pending(struct file_lease *fl, int arg)
1431{
1432 switch (arg) {
1433 case F_UNLCK:
1434 fl->c.flc_flags &= ~FL_UNLOCK_PENDING;
1435 fallthrough;
1436 case F_RDLCK:
1437 fl->c.flc_flags &= ~FL_DOWNGRADE_PENDING;
1438 }
1439}
1440
1441/* We already had a lease on this file; just change its type */
1442int lease_modify(struct file_lease *fl, int arg, struct list_head *dispose)
1443{
1444 int error = assign_type(&fl->c, arg);
1445
1446 if (error)
1447 return error;
1448 lease_clear_pending(fl, arg);
1449 locks_wake_up_blocks(&fl->c);
1450 if (arg == F_UNLCK) {
1451 struct file *filp = fl->c.flc_file;
1452
1453 f_delown(filp);
1454 file_f_owner(filp)->signum = 0;
1455 fasync_helper(0, fl->c.flc_file, 0, &fl->fl_fasync);
1456 if (fl->fl_fasync != NULL) {
1457 printk(KERN_ERR "locks_delete_lock: fasync == %p\n", fl->fl_fasync);
1458 fl->fl_fasync = NULL;
1459 }
1460 locks_delete_lock_ctx(&fl->c, dispose);
1461 }
1462 return 0;
1463}
1464EXPORT_SYMBOL(lease_modify);
1465
1466static bool past_time(unsigned long then)
1467{
1468 if (!then)
1469 /* 0 is a special value meaning "this never expires": */
1470 return false;
1471 return time_after(jiffies, then);
1472}
1473
1474static void time_out_leases(struct inode *inode, struct list_head *dispose)
1475{
1476 struct file_lock_context *ctx = inode->i_flctx;
1477 struct file_lease *fl, *tmp;
1478
1479 lockdep_assert_held(&ctx->flc_lock);
1480
1481 list_for_each_entry_safe(fl, tmp, &ctx->flc_lease, c.flc_list) {
1482 trace_time_out_leases(inode, fl);
1483 if (past_time(fl->fl_downgrade_time))
1484 lease_modify(fl, F_RDLCK, dispose);
1485 if (past_time(fl->fl_break_time))
1486 lease_modify(fl, F_UNLCK, dispose);
1487 }
1488}
1489
1490static bool leases_conflict(struct file_lock_core *lc, struct file_lock_core *bc)
1491{
1492 bool rc;
1493 struct file_lease *lease = file_lease(lc);
1494 struct file_lease *breaker = file_lease(bc);
1495
1496 if (lease->fl_lmops->lm_breaker_owns_lease
1497 && lease->fl_lmops->lm_breaker_owns_lease(lease))
1498 return false;
1499 if ((bc->flc_flags & FL_LAYOUT) != (lc->flc_flags & FL_LAYOUT)) {
1500 rc = false;
1501 goto trace;
1502 }
1503 if ((bc->flc_flags & FL_DELEG) && (lc->flc_flags & FL_LEASE)) {
1504 rc = false;
1505 goto trace;
1506 }
1507
1508 rc = locks_conflict(bc, lc);
1509trace:
1510 trace_leases_conflict(rc, lease, breaker);
1511 return rc;
1512}
1513
1514static bool
1515any_leases_conflict(struct inode *inode, struct file_lease *breaker)
1516{
1517 struct file_lock_context *ctx = inode->i_flctx;
1518 struct file_lock_core *flc;
1519
1520 lockdep_assert_held(&ctx->flc_lock);
1521
1522 list_for_each_entry(flc, &ctx->flc_lease, flc_list) {
1523 if (leases_conflict(flc, &breaker->c))
1524 return true;
1525 }
1526 return false;
1527}
1528
1529/**
1530 * __break_lease - revoke all outstanding leases on file
1531 * @inode: the inode of the file to return
1532 * @mode: O_RDONLY: break only write leases; O_WRONLY or O_RDWR:
1533 * break all leases
1534 * @type: FL_LEASE: break leases and delegations; FL_DELEG: break
1535 * only delegations
1536 *
1537 * break_lease (inlined for speed) has checked there already is at least
1538 * some kind of lock (maybe a lease) on this file. Leases are broken on
1539 * a call to open() or truncate(). This function can sleep unless you
1540 * specified %O_NONBLOCK to your open().
1541 */
1542int __break_lease(struct inode *inode, unsigned int mode, unsigned int type)
1543{
1544 int error = 0;
1545 struct file_lock_context *ctx;
1546 struct file_lease *new_fl, *fl, *tmp;
1547 unsigned long break_time;
1548 int want_write = (mode & O_ACCMODE) != O_RDONLY;
1549 LIST_HEAD(dispose);
1550
1551 new_fl = lease_alloc(NULL, want_write ? F_WRLCK : F_RDLCK);
1552 if (IS_ERR(new_fl))
1553 return PTR_ERR(new_fl);
1554 new_fl->c.flc_flags = type;
1555
1556 /* typically we will check that ctx is non-NULL before calling */
1557 ctx = locks_inode_context(inode);
1558 if (!ctx) {
1559 WARN_ON_ONCE(1);
1560 goto free_lock;
1561 }
1562
1563 percpu_down_read(&file_rwsem);
1564 spin_lock(&ctx->flc_lock);
1565
1566 time_out_leases(inode, &dispose);
1567
1568 if (!any_leases_conflict(inode, new_fl))
1569 goto out;
1570
1571 break_time = 0;
1572 if (lease_break_time > 0) {
1573 break_time = jiffies + lease_break_time * HZ;
1574 if (break_time == 0)
1575 break_time++; /* so that 0 means no break time */
1576 }
1577
1578 list_for_each_entry_safe(fl, tmp, &ctx->flc_lease, c.flc_list) {
1579 if (!leases_conflict(&fl->c, &new_fl->c))
1580 continue;
1581 if (want_write) {
1582 if (fl->c.flc_flags & FL_UNLOCK_PENDING)
1583 continue;
1584 fl->c.flc_flags |= FL_UNLOCK_PENDING;
1585 fl->fl_break_time = break_time;
1586 } else {
1587 if (lease_breaking(fl))
1588 continue;
1589 fl->c.flc_flags |= FL_DOWNGRADE_PENDING;
1590 fl->fl_downgrade_time = break_time;
1591 }
1592 if (fl->fl_lmops->lm_break(fl))
1593 locks_delete_lock_ctx(&fl->c, &dispose);
1594 }
1595
1596 if (list_empty(&ctx->flc_lease))
1597 goto out;
1598
1599 if (mode & O_NONBLOCK) {
1600 trace_break_lease_noblock(inode, new_fl);
1601 error = -EWOULDBLOCK;
1602 goto out;
1603 }
1604
1605restart:
1606 fl = list_first_entry(&ctx->flc_lease, struct file_lease, c.flc_list);
1607 break_time = fl->fl_break_time;
1608 if (break_time != 0)
1609 break_time -= jiffies;
1610 if (break_time == 0)
1611 break_time++;
1612 locks_insert_block(&fl->c, &new_fl->c, leases_conflict);
1613 trace_break_lease_block(inode, new_fl);
1614 spin_unlock(&ctx->flc_lock);
1615 percpu_up_read(&file_rwsem);
1616
1617 locks_dispose_list(&dispose);
1618 error = wait_event_interruptible_timeout(new_fl->c.flc_wait,
1619 list_empty(&new_fl->c.flc_blocked_member),
1620 break_time);
1621
1622 percpu_down_read(&file_rwsem);
1623 spin_lock(&ctx->flc_lock);
1624 trace_break_lease_unblock(inode, new_fl);
1625 __locks_delete_block(&new_fl->c);
1626 if (error >= 0) {
1627 /*
1628 * Wait for the next conflicting lease that has not been
1629 * broken yet
1630 */
1631 if (error == 0)
1632 time_out_leases(inode, &dispose);
1633 if (any_leases_conflict(inode, new_fl))
1634 goto restart;
1635 error = 0;
1636 }
1637out:
1638 spin_unlock(&ctx->flc_lock);
1639 percpu_up_read(&file_rwsem);
1640 locks_dispose_list(&dispose);
1641free_lock:
1642 locks_free_lease(new_fl);
1643 return error;
1644}
1645EXPORT_SYMBOL(__break_lease);
1646
1647/**
1648 * lease_get_mtime - update modified time of an inode with exclusive lease
1649 * @inode: the inode
1650 * @time: pointer to a timespec which contains the last modified time
1651 *
1652 * This is to force NFS clients to flush their caches for files with
1653 * exclusive leases. The justification is that if someone has an
1654 * exclusive lease, then they could be modifying it.
1655 */
1656void lease_get_mtime(struct inode *inode, struct timespec64 *time)
1657{
1658 bool has_lease = false;
1659 struct file_lock_context *ctx;
1660 struct file_lock_core *flc;
1661
1662 ctx = locks_inode_context(inode);
1663 if (ctx && !list_empty_careful(&ctx->flc_lease)) {
1664 spin_lock(&ctx->flc_lock);
1665 flc = list_first_entry_or_null(&ctx->flc_lease,
1666 struct file_lock_core, flc_list);
1667 if (flc && flc->flc_type == F_WRLCK)
1668 has_lease = true;
1669 spin_unlock(&ctx->flc_lock);
1670 }
1671
1672 if (has_lease)
1673 *time = current_time(inode);
1674}
1675EXPORT_SYMBOL(lease_get_mtime);
1676
1677/**
1678 * fcntl_getlease - Enquire what lease is currently active
1679 * @filp: the file
1680 *
1681 * The value returned by this function will be one of
1682 * (if no lease break is pending):
1683 *
1684 * %F_RDLCK to indicate a shared lease is held.
1685 *
1686 * %F_WRLCK to indicate an exclusive lease is held.
1687 *
1688 * %F_UNLCK to indicate no lease is held.
1689 *
1690 * (if a lease break is pending):
1691 *
1692 * %F_RDLCK to indicate an exclusive lease needs to be
1693 * changed to a shared lease (or removed).
1694 *
1695 * %F_UNLCK to indicate the lease needs to be removed.
1696 *
1697 * XXX: sfr & willy disagree over whether F_INPROGRESS
1698 * should be returned to userspace.
1699 */
1700int fcntl_getlease(struct file *filp)
1701{
1702 struct file_lease *fl;
1703 struct inode *inode = file_inode(filp);
1704 struct file_lock_context *ctx;
1705 int type = F_UNLCK;
1706 LIST_HEAD(dispose);
1707
1708 ctx = locks_inode_context(inode);
1709 if (ctx && !list_empty_careful(&ctx->flc_lease)) {
1710 percpu_down_read(&file_rwsem);
1711 spin_lock(&ctx->flc_lock);
1712 time_out_leases(inode, &dispose);
1713 list_for_each_entry(fl, &ctx->flc_lease, c.flc_list) {
1714 if (fl->c.flc_file != filp)
1715 continue;
1716 type = target_leasetype(fl);
1717 break;
1718 }
1719 spin_unlock(&ctx->flc_lock);
1720 percpu_up_read(&file_rwsem);
1721
1722 locks_dispose_list(&dispose);
1723 }
1724 return type;
1725}
1726
1727/**
1728 * check_conflicting_open - see if the given file points to an inode that has
1729 * an existing open that would conflict with the
1730 * desired lease.
1731 * @filp: file to check
1732 * @arg: type of lease that we're trying to acquire
1733 * @flags: current lock flags
1734 *
1735 * Check to see if there's an existing open fd on this file that would
1736 * conflict with the lease we're trying to set.
1737 */
1738static int
1739check_conflicting_open(struct file *filp, const int arg, int flags)
1740{
1741 struct inode *inode = file_inode(filp);
1742 int self_wcount = 0, self_rcount = 0;
1743
1744 if (flags & FL_LAYOUT)
1745 return 0;
1746 if (flags & FL_DELEG)
1747 /* We leave these checks to the caller */
1748 return 0;
1749
1750 if (arg == F_RDLCK)
1751 return inode_is_open_for_write(inode) ? -EAGAIN : 0;
1752 else if (arg != F_WRLCK)
1753 return 0;
1754
1755 /*
1756 * Make sure that only read/write count is from lease requestor.
1757 * Note that this will result in denying write leases when i_writecount
1758 * is negative, which is what we want. (We shouldn't grant write leases
1759 * on files open for execution.)
1760 */
1761 if (filp->f_mode & FMODE_WRITE)
1762 self_wcount = 1;
1763 else if (filp->f_mode & FMODE_READ)
1764 self_rcount = 1;
1765
1766 if (atomic_read(&inode->i_writecount) != self_wcount ||
1767 atomic_read(&inode->i_readcount) != self_rcount)
1768 return -EAGAIN;
1769
1770 return 0;
1771}
1772
1773static int
1774generic_add_lease(struct file *filp, int arg, struct file_lease **flp, void **priv)
1775{
1776 struct file_lease *fl, *my_fl = NULL, *lease;
1777 struct inode *inode = file_inode(filp);
1778 struct file_lock_context *ctx;
1779 bool is_deleg = (*flp)->c.flc_flags & FL_DELEG;
1780 int error;
1781 LIST_HEAD(dispose);
1782
1783 lease = *flp;
1784 trace_generic_add_lease(inode, lease);
1785
1786 error = file_f_owner_allocate(filp);
1787 if (error)
1788 return error;
1789
1790 /* Note that arg is never F_UNLCK here */
1791 ctx = locks_get_lock_context(inode, arg);
1792 if (!ctx)
1793 return -ENOMEM;
1794
1795 /*
1796 * In the delegation case we need mutual exclusion with
1797 * a number of operations that take the i_mutex. We trylock
1798 * because delegations are an optional optimization, and if
1799 * there's some chance of a conflict--we'd rather not
1800 * bother, maybe that's a sign this just isn't a good file to
1801 * hand out a delegation on.
1802 */
1803 if (is_deleg && !inode_trylock(inode))
1804 return -EAGAIN;
1805
1806 percpu_down_read(&file_rwsem);
1807 spin_lock(&ctx->flc_lock);
1808 time_out_leases(inode, &dispose);
1809 error = check_conflicting_open(filp, arg, lease->c.flc_flags);
1810 if (error)
1811 goto out;
1812
1813 /*
1814 * At this point, we know that if there is an exclusive
1815 * lease on this file, then we hold it on this filp
1816 * (otherwise our open of this file would have blocked).
1817 * And if we are trying to acquire an exclusive lease,
1818 * then the file is not open by anyone (including us)
1819 * except for this filp.
1820 */
1821 error = -EAGAIN;
1822 list_for_each_entry(fl, &ctx->flc_lease, c.flc_list) {
1823 if (fl->c.flc_file == filp &&
1824 fl->c.flc_owner == lease->c.flc_owner) {
1825 my_fl = fl;
1826 continue;
1827 }
1828
1829 /*
1830 * No exclusive leases if someone else has a lease on
1831 * this file:
1832 */
1833 if (arg == F_WRLCK)
1834 goto out;
1835 /*
1836 * Modifying our existing lease is OK, but no getting a
1837 * new lease if someone else is opening for write:
1838 */
1839 if (fl->c.flc_flags & FL_UNLOCK_PENDING)
1840 goto out;
1841 }
1842
1843 if (my_fl != NULL) {
1844 lease = my_fl;
1845 error = lease->fl_lmops->lm_change(lease, arg, &dispose);
1846 if (error)
1847 goto out;
1848 goto out_setup;
1849 }
1850
1851 error = -EINVAL;
1852 if (!leases_enable)
1853 goto out;
1854
1855 locks_insert_lock_ctx(&lease->c, &ctx->flc_lease);
1856 /*
1857 * The check in break_lease() is lockless. It's possible for another
1858 * open to race in after we did the earlier check for a conflicting
1859 * open but before the lease was inserted. Check again for a
1860 * conflicting open and cancel the lease if there is one.
1861 *
1862 * We also add a barrier here to ensure that the insertion of the lock
1863 * precedes these checks.
1864 */
1865 smp_mb();
1866 error = check_conflicting_open(filp, arg, lease->c.flc_flags);
1867 if (error) {
1868 locks_unlink_lock_ctx(&lease->c);
1869 goto out;
1870 }
1871
1872out_setup:
1873 if (lease->fl_lmops->lm_setup)
1874 lease->fl_lmops->lm_setup(lease, priv);
1875out:
1876 spin_unlock(&ctx->flc_lock);
1877 percpu_up_read(&file_rwsem);
1878 locks_dispose_list(&dispose);
1879 if (is_deleg)
1880 inode_unlock(inode);
1881 if (!error && !my_fl)
1882 *flp = NULL;
1883 return error;
1884}
1885
1886static int generic_delete_lease(struct file *filp, void *owner)
1887{
1888 int error = -EAGAIN;
1889 struct file_lease *fl, *victim = NULL;
1890 struct inode *inode = file_inode(filp);
1891 struct file_lock_context *ctx;
1892 LIST_HEAD(dispose);
1893
1894 ctx = locks_inode_context(inode);
1895 if (!ctx) {
1896 trace_generic_delete_lease(inode, NULL);
1897 return error;
1898 }
1899
1900 percpu_down_read(&file_rwsem);
1901 spin_lock(&ctx->flc_lock);
1902 list_for_each_entry(fl, &ctx->flc_lease, c.flc_list) {
1903 if (fl->c.flc_file == filp &&
1904 fl->c.flc_owner == owner) {
1905 victim = fl;
1906 break;
1907 }
1908 }
1909 trace_generic_delete_lease(inode, victim);
1910 if (victim)
1911 error = fl->fl_lmops->lm_change(victim, F_UNLCK, &dispose);
1912 spin_unlock(&ctx->flc_lock);
1913 percpu_up_read(&file_rwsem);
1914 locks_dispose_list(&dispose);
1915 return error;
1916}
1917
1918/**
1919 * generic_setlease - sets a lease on an open file
1920 * @filp: file pointer
1921 * @arg: type of lease to obtain
1922 * @flp: input - file_lock to use, output - file_lock inserted
1923 * @priv: private data for lm_setup (may be NULL if lm_setup
1924 * doesn't require it)
1925 *
1926 * The (input) flp->fl_lmops->lm_break function is required
1927 * by break_lease().
1928 */
1929int generic_setlease(struct file *filp, int arg, struct file_lease **flp,
1930 void **priv)
1931{
1932 switch (arg) {
1933 case F_UNLCK:
1934 return generic_delete_lease(filp, *priv);
1935 case F_RDLCK:
1936 case F_WRLCK:
1937 if (!(*flp)->fl_lmops->lm_break) {
1938 WARN_ON_ONCE(1);
1939 return -ENOLCK;
1940 }
1941
1942 return generic_add_lease(filp, arg, flp, priv);
1943 default:
1944 return -EINVAL;
1945 }
1946}
1947EXPORT_SYMBOL(generic_setlease);
1948
1949/*
1950 * Kernel subsystems can register to be notified on any attempt to set
1951 * a new lease with the lease_notifier_chain. This is used by (e.g.) nfsd
1952 * to close files that it may have cached when there is an attempt to set a
1953 * conflicting lease.
1954 */
1955static struct srcu_notifier_head lease_notifier_chain;
1956
1957static inline void
1958lease_notifier_chain_init(void)
1959{
1960 srcu_init_notifier_head(&lease_notifier_chain);
1961}
1962
1963static inline void
1964setlease_notifier(int arg, struct file_lease *lease)
1965{
1966 if (arg != F_UNLCK)
1967 srcu_notifier_call_chain(&lease_notifier_chain, arg, lease);
1968}
1969
1970int lease_register_notifier(struct notifier_block *nb)
1971{
1972 return srcu_notifier_chain_register(&lease_notifier_chain, nb);
1973}
1974EXPORT_SYMBOL_GPL(lease_register_notifier);
1975
1976void lease_unregister_notifier(struct notifier_block *nb)
1977{
1978 srcu_notifier_chain_unregister(&lease_notifier_chain, nb);
1979}
1980EXPORT_SYMBOL_GPL(lease_unregister_notifier);
1981
1982
1983int
1984kernel_setlease(struct file *filp, int arg, struct file_lease **lease, void **priv)
1985{
1986 if (lease)
1987 setlease_notifier(arg, *lease);
1988 if (filp->f_op->setlease)
1989 return filp->f_op->setlease(filp, arg, lease, priv);
1990 else
1991 return generic_setlease(filp, arg, lease, priv);
1992}
1993EXPORT_SYMBOL_GPL(kernel_setlease);
1994
1995/**
1996 * vfs_setlease - sets a lease on an open file
1997 * @filp: file pointer
1998 * @arg: type of lease to obtain
1999 * @lease: file_lock to use when adding a lease
2000 * @priv: private info for lm_setup when adding a lease (may be
2001 * NULL if lm_setup doesn't require it)
2002 *
2003 * Call this to establish a lease on the file. The "lease" argument is not
2004 * used for F_UNLCK requests and may be NULL. For commands that set or alter
2005 * an existing lease, the ``(*lease)->fl_lmops->lm_break`` operation must be
2006 * set; if not, this function will return -ENOLCK (and generate a scary-looking
2007 * stack trace).
2008 *
2009 * The "priv" pointer is passed directly to the lm_setup function as-is. It
2010 * may be NULL if the lm_setup operation doesn't require it.
2011 */
2012int
2013vfs_setlease(struct file *filp, int arg, struct file_lease **lease, void **priv)
2014{
2015 struct inode *inode = file_inode(filp);
2016 vfsuid_t vfsuid = i_uid_into_vfsuid(file_mnt_idmap(filp), inode);
2017 int error;
2018
2019 if ((!vfsuid_eq_kuid(vfsuid, current_fsuid())) && !capable(CAP_LEASE))
2020 return -EACCES;
2021 if (!S_ISREG(inode->i_mode))
2022 return -EINVAL;
2023 error = security_file_lock(filp, arg);
2024 if (error)
2025 return error;
2026 return kernel_setlease(filp, arg, lease, priv);
2027}
2028EXPORT_SYMBOL_GPL(vfs_setlease);
2029
2030static int do_fcntl_add_lease(unsigned int fd, struct file *filp, int arg)
2031{
2032 struct file_lease *fl;
2033 struct fasync_struct *new;
2034 int error;
2035
2036 fl = lease_alloc(filp, arg);
2037 if (IS_ERR(fl))
2038 return PTR_ERR(fl);
2039
2040 new = fasync_alloc();
2041 if (!new) {
2042 locks_free_lease(fl);
2043 return -ENOMEM;
2044 }
2045 new->fa_fd = fd;
2046
2047 error = vfs_setlease(filp, arg, &fl, (void **)&new);
2048 if (fl)
2049 locks_free_lease(fl);
2050 if (new)
2051 fasync_free(new);
2052 return error;
2053}
2054
2055/**
2056 * fcntl_setlease - sets a lease on an open file
2057 * @fd: open file descriptor
2058 * @filp: file pointer
2059 * @arg: type of lease to obtain
2060 *
2061 * Call this fcntl to establish a lease on the file.
2062 * Note that you also need to call %F_SETSIG to
2063 * receive a signal when the lease is broken.
2064 */
2065int fcntl_setlease(unsigned int fd, struct file *filp, int arg)
2066{
2067 if (arg == F_UNLCK)
2068 return vfs_setlease(filp, F_UNLCK, NULL, (void **)&filp);
2069 return do_fcntl_add_lease(fd, filp, arg);
2070}
2071
2072/**
2073 * flock_lock_inode_wait - Apply a FLOCK-style lock to a file
2074 * @inode: inode of the file to apply to
2075 * @fl: The lock to be applied
2076 *
2077 * Apply a FLOCK style lock request to an inode.
2078 */
2079static int flock_lock_inode_wait(struct inode *inode, struct file_lock *fl)
2080{
2081 int error;
2082 might_sleep();
2083 for (;;) {
2084 error = flock_lock_inode(inode, fl);
2085 if (error != FILE_LOCK_DEFERRED)
2086 break;
2087 error = wait_event_interruptible(fl->c.flc_wait,
2088 list_empty(&fl->c.flc_blocked_member));
2089 if (error)
2090 break;
2091 }
2092 locks_delete_block(fl);
2093 return error;
2094}
2095
2096/**
2097 * locks_lock_inode_wait - Apply a lock to an inode
2098 * @inode: inode of the file to apply to
2099 * @fl: The lock to be applied
2100 *
2101 * Apply a POSIX or FLOCK style lock request to an inode.
2102 */
2103int locks_lock_inode_wait(struct inode *inode, struct file_lock *fl)
2104{
2105 int res = 0;
2106 switch (fl->c.flc_flags & (FL_POSIX|FL_FLOCK)) {
2107 case FL_POSIX:
2108 res = posix_lock_inode_wait(inode, fl);
2109 break;
2110 case FL_FLOCK:
2111 res = flock_lock_inode_wait(inode, fl);
2112 break;
2113 default:
2114 BUG();
2115 }
2116 return res;
2117}
2118EXPORT_SYMBOL(locks_lock_inode_wait);
2119
2120/**
2121 * sys_flock: - flock() system call.
2122 * @fd: the file descriptor to lock.
2123 * @cmd: the type of lock to apply.
2124 *
2125 * Apply a %FL_FLOCK style lock to an open file descriptor.
2126 * The @cmd can be one of:
2127 *
2128 * - %LOCK_SH -- a shared lock.
2129 * - %LOCK_EX -- an exclusive lock.
2130 * - %LOCK_UN -- remove an existing lock.
2131 * - %LOCK_MAND -- a 'mandatory' flock. (DEPRECATED)
2132 *
2133 * %LOCK_MAND support has been removed from the kernel.
2134 */
2135SYSCALL_DEFINE2(flock, unsigned int, fd, unsigned int, cmd)
2136{
2137 int can_sleep, error, type;
2138 struct file_lock fl;
2139
2140 /*
2141 * LOCK_MAND locks were broken for a long time in that they never
2142 * conflicted with one another and didn't prevent any sort of open,
2143 * read or write activity.
2144 *
2145 * Just ignore these requests now, to preserve legacy behavior, but
2146 * throw a warning to let people know that they don't actually work.
2147 */
2148 if (cmd & LOCK_MAND) {
2149 pr_warn_once("%s(%d): Attempt to set a LOCK_MAND lock via flock(2). This support has been removed and the request ignored.\n", current->comm, current->pid);
2150 return 0;
2151 }
2152
2153 type = flock_translate_cmd(cmd & ~LOCK_NB);
2154 if (type < 0)
2155 return type;
2156
2157 CLASS(fd, f)(fd);
2158 if (fd_empty(f))
2159 return -EBADF;
2160
2161 if (type != F_UNLCK && !(fd_file(f)->f_mode & (FMODE_READ | FMODE_WRITE)))
2162 return -EBADF;
2163
2164 flock_make_lock(fd_file(f), &fl, type);
2165
2166 error = security_file_lock(fd_file(f), fl.c.flc_type);
2167 if (error)
2168 return error;
2169
2170 can_sleep = !(cmd & LOCK_NB);
2171 if (can_sleep)
2172 fl.c.flc_flags |= FL_SLEEP;
2173
2174 if (fd_file(f)->f_op->flock)
2175 error = fd_file(f)->f_op->flock(fd_file(f),
2176 (can_sleep) ? F_SETLKW : F_SETLK,
2177 &fl);
2178 else
2179 error = locks_lock_file_wait(fd_file(f), &fl);
2180
2181 locks_release_private(&fl);
2182 return error;
2183}
2184
2185/**
2186 * vfs_test_lock - test file byte range lock
2187 * @filp: The file to test lock for
2188 * @fl: The lock to test; also used to hold result
2189 *
2190 * Returns -ERRNO on failure. Indicates presence of conflicting lock by
2191 * setting conf->fl_type to something other than F_UNLCK.
2192 */
2193int vfs_test_lock(struct file *filp, struct file_lock *fl)
2194{
2195 WARN_ON_ONCE(filp != fl->c.flc_file);
2196 if (filp->f_op->lock)
2197 return filp->f_op->lock(filp, F_GETLK, fl);
2198 posix_test_lock(filp, fl);
2199 return 0;
2200}
2201EXPORT_SYMBOL_GPL(vfs_test_lock);
2202
2203/**
2204 * locks_translate_pid - translate a file_lock's fl_pid number into a namespace
2205 * @fl: The file_lock who's fl_pid should be translated
2206 * @ns: The namespace into which the pid should be translated
2207 *
2208 * Used to translate a fl_pid into a namespace virtual pid number
2209 */
2210static pid_t locks_translate_pid(struct file_lock_core *fl, struct pid_namespace *ns)
2211{
2212 pid_t vnr;
2213 struct pid *pid;
2214
2215 if (fl->flc_flags & FL_OFDLCK)
2216 return -1;
2217
2218 /* Remote locks report a negative pid value */
2219 if (fl->flc_pid <= 0)
2220 return fl->flc_pid;
2221
2222 /*
2223 * If the flock owner process is dead and its pid has been already
2224 * freed, the translation below won't work, but we still want to show
2225 * flock owner pid number in init pidns.
2226 */
2227 if (ns == &init_pid_ns)
2228 return (pid_t) fl->flc_pid;
2229
2230 rcu_read_lock();
2231 pid = find_pid_ns(fl->flc_pid, &init_pid_ns);
2232 vnr = pid_nr_ns(pid, ns);
2233 rcu_read_unlock();
2234 return vnr;
2235}
2236
2237static int posix_lock_to_flock(struct flock *flock, struct file_lock *fl)
2238{
2239 flock->l_pid = locks_translate_pid(&fl->c, task_active_pid_ns(current));
2240#if BITS_PER_LONG == 32
2241 /*
2242 * Make sure we can represent the posix lock via
2243 * legacy 32bit flock.
2244 */
2245 if (fl->fl_start > OFFT_OFFSET_MAX)
2246 return -EOVERFLOW;
2247 if (fl->fl_end != OFFSET_MAX && fl->fl_end > OFFT_OFFSET_MAX)
2248 return -EOVERFLOW;
2249#endif
2250 flock->l_start = fl->fl_start;
2251 flock->l_len = fl->fl_end == OFFSET_MAX ? 0 :
2252 fl->fl_end - fl->fl_start + 1;
2253 flock->l_whence = 0;
2254 flock->l_type = fl->c.flc_type;
2255 return 0;
2256}
2257
2258#if BITS_PER_LONG == 32
2259static void posix_lock_to_flock64(struct flock64 *flock, struct file_lock *fl)
2260{
2261 flock->l_pid = locks_translate_pid(&fl->c, task_active_pid_ns(current));
2262 flock->l_start = fl->fl_start;
2263 flock->l_len = fl->fl_end == OFFSET_MAX ? 0 :
2264 fl->fl_end - fl->fl_start + 1;
2265 flock->l_whence = 0;
2266 flock->l_type = fl->c.flc_type;
2267}
2268#endif
2269
2270/* Report the first existing lock that would conflict with l.
2271 * This implements the F_GETLK command of fcntl().
2272 */
2273int fcntl_getlk(struct file *filp, unsigned int cmd, struct flock *flock)
2274{
2275 struct file_lock *fl;
2276 int error;
2277
2278 fl = locks_alloc_lock();
2279 if (fl == NULL)
2280 return -ENOMEM;
2281 error = -EINVAL;
2282 if (cmd != F_OFD_GETLK && flock->l_type != F_RDLCK
2283 && flock->l_type != F_WRLCK)
2284 goto out;
2285
2286 error = flock_to_posix_lock(filp, fl, flock);
2287 if (error)
2288 goto out;
2289
2290 if (cmd == F_OFD_GETLK) {
2291 error = -EINVAL;
2292 if (flock->l_pid != 0)
2293 goto out;
2294
2295 fl->c.flc_flags |= FL_OFDLCK;
2296 fl->c.flc_owner = filp;
2297 }
2298
2299 error = vfs_test_lock(filp, fl);
2300 if (error)
2301 goto out;
2302
2303 flock->l_type = fl->c.flc_type;
2304 if (fl->c.flc_type != F_UNLCK) {
2305 error = posix_lock_to_flock(flock, fl);
2306 if (error)
2307 goto out;
2308 }
2309out:
2310 locks_free_lock(fl);
2311 return error;
2312}
2313
2314/**
2315 * vfs_lock_file - file byte range lock
2316 * @filp: The file to apply the lock to
2317 * @cmd: type of locking operation (F_SETLK, F_GETLK, etc.)
2318 * @fl: The lock to be applied
2319 * @conf: Place to return a copy of the conflicting lock, if found.
2320 *
2321 * A caller that doesn't care about the conflicting lock may pass NULL
2322 * as the final argument.
2323 *
2324 * If the filesystem defines a private ->lock() method, then @conf will
2325 * be left unchanged; so a caller that cares should initialize it to
2326 * some acceptable default.
2327 *
2328 * To avoid blocking kernel daemons, such as lockd, that need to acquire POSIX
2329 * locks, the ->lock() interface may return asynchronously, before the lock has
2330 * been granted or denied by the underlying filesystem, if (and only if)
2331 * lm_grant is set. Additionally EXPORT_OP_ASYNC_LOCK in export_operations
2332 * flags need to be set.
2333 *
2334 * Callers expecting ->lock() to return asynchronously will only use F_SETLK,
2335 * not F_SETLKW; they will set FL_SLEEP if (and only if) the request is for a
2336 * blocking lock. When ->lock() does return asynchronously, it must return
2337 * FILE_LOCK_DEFERRED, and call ->lm_grant() when the lock request completes.
2338 * If the request is for non-blocking lock the file system should return
2339 * FILE_LOCK_DEFERRED then try to get the lock and call the callback routine
2340 * with the result. If the request timed out the callback routine will return a
2341 * nonzero return code and the file system should release the lock. The file
2342 * system is also responsible to keep a corresponding posix lock when it
2343 * grants a lock so the VFS can find out which locks are locally held and do
2344 * the correct lock cleanup when required.
2345 * The underlying filesystem must not drop the kernel lock or call
2346 * ->lm_grant() before returning to the caller with a FILE_LOCK_DEFERRED
2347 * return code.
2348 */
2349int vfs_lock_file(struct file *filp, unsigned int cmd, struct file_lock *fl, struct file_lock *conf)
2350{
2351 WARN_ON_ONCE(filp != fl->c.flc_file);
2352 if (filp->f_op->lock)
2353 return filp->f_op->lock(filp, cmd, fl);
2354 else
2355 return posix_lock_file(filp, fl, conf);
2356}
2357EXPORT_SYMBOL_GPL(vfs_lock_file);
2358
2359static int do_lock_file_wait(struct file *filp, unsigned int cmd,
2360 struct file_lock *fl)
2361{
2362 int error;
2363
2364 error = security_file_lock(filp, fl->c.flc_type);
2365 if (error)
2366 return error;
2367
2368 for (;;) {
2369 error = vfs_lock_file(filp, cmd, fl, NULL);
2370 if (error != FILE_LOCK_DEFERRED)
2371 break;
2372 error = wait_event_interruptible(fl->c.flc_wait,
2373 list_empty(&fl->c.flc_blocked_member));
2374 if (error)
2375 break;
2376 }
2377 locks_delete_block(fl);
2378
2379 return error;
2380}
2381
2382/* Ensure that fl->fl_file has compatible f_mode for F_SETLK calls */
2383static int
2384check_fmode_for_setlk(struct file_lock *fl)
2385{
2386 switch (fl->c.flc_type) {
2387 case F_RDLCK:
2388 if (!(fl->c.flc_file->f_mode & FMODE_READ))
2389 return -EBADF;
2390 break;
2391 case F_WRLCK:
2392 if (!(fl->c.flc_file->f_mode & FMODE_WRITE))
2393 return -EBADF;
2394 }
2395 return 0;
2396}
2397
2398/* Apply the lock described by l to an open file descriptor.
2399 * This implements both the F_SETLK and F_SETLKW commands of fcntl().
2400 */
2401int fcntl_setlk(unsigned int fd, struct file *filp, unsigned int cmd,
2402 struct flock *flock)
2403{
2404 struct file_lock *file_lock = locks_alloc_lock();
2405 struct inode *inode = file_inode(filp);
2406 struct file *f;
2407 int error;
2408
2409 if (file_lock == NULL)
2410 return -ENOLCK;
2411
2412 error = flock_to_posix_lock(filp, file_lock, flock);
2413 if (error)
2414 goto out;
2415
2416 error = check_fmode_for_setlk(file_lock);
2417 if (error)
2418 goto out;
2419
2420 /*
2421 * If the cmd is requesting file-private locks, then set the
2422 * FL_OFDLCK flag and override the owner.
2423 */
2424 switch (cmd) {
2425 case F_OFD_SETLK:
2426 error = -EINVAL;
2427 if (flock->l_pid != 0)
2428 goto out;
2429
2430 cmd = F_SETLK;
2431 file_lock->c.flc_flags |= FL_OFDLCK;
2432 file_lock->c.flc_owner = filp;
2433 break;
2434 case F_OFD_SETLKW:
2435 error = -EINVAL;
2436 if (flock->l_pid != 0)
2437 goto out;
2438
2439 cmd = F_SETLKW;
2440 file_lock->c.flc_flags |= FL_OFDLCK;
2441 file_lock->c.flc_owner = filp;
2442 fallthrough;
2443 case F_SETLKW:
2444 file_lock->c.flc_flags |= FL_SLEEP;
2445 }
2446
2447 error = do_lock_file_wait(filp, cmd, file_lock);
2448
2449 /*
2450 * Detect close/fcntl races and recover by zapping all POSIX locks
2451 * associated with this file and our files_struct, just like on
2452 * filp_flush(). There is no need to do that when we're
2453 * unlocking though, or for OFD locks.
2454 */
2455 if (!error && file_lock->c.flc_type != F_UNLCK &&
2456 !(file_lock->c.flc_flags & FL_OFDLCK)) {
2457 struct files_struct *files = current->files;
2458 /*
2459 * We need that spin_lock here - it prevents reordering between
2460 * update of i_flctx->flc_posix and check for it done in
2461 * close(). rcu_read_lock() wouldn't do.
2462 */
2463 spin_lock(&files->file_lock);
2464 f = files_lookup_fd_locked(files, fd);
2465 spin_unlock(&files->file_lock);
2466 if (f != filp) {
2467 locks_remove_posix(filp, files);
2468 error = -EBADF;
2469 }
2470 }
2471out:
2472 trace_fcntl_setlk(inode, file_lock, error);
2473 locks_free_lock(file_lock);
2474 return error;
2475}
2476
2477#if BITS_PER_LONG == 32
2478/* Report the first existing lock that would conflict with l.
2479 * This implements the F_GETLK command of fcntl().
2480 */
2481int fcntl_getlk64(struct file *filp, unsigned int cmd, struct flock64 *flock)
2482{
2483 struct file_lock *fl;
2484 int error;
2485
2486 fl = locks_alloc_lock();
2487 if (fl == NULL)
2488 return -ENOMEM;
2489
2490 error = -EINVAL;
2491 if (cmd != F_OFD_GETLK && flock->l_type != F_RDLCK
2492 && flock->l_type != F_WRLCK)
2493 goto out;
2494
2495 error = flock64_to_posix_lock(filp, fl, flock);
2496 if (error)
2497 goto out;
2498
2499 if (cmd == F_OFD_GETLK) {
2500 error = -EINVAL;
2501 if (flock->l_pid != 0)
2502 goto out;
2503
2504 fl->c.flc_flags |= FL_OFDLCK;
2505 fl->c.flc_owner = filp;
2506 }
2507
2508 error = vfs_test_lock(filp, fl);
2509 if (error)
2510 goto out;
2511
2512 flock->l_type = fl->c.flc_type;
2513 if (fl->c.flc_type != F_UNLCK)
2514 posix_lock_to_flock64(flock, fl);
2515
2516out:
2517 locks_free_lock(fl);
2518 return error;
2519}
2520
2521/* Apply the lock described by l to an open file descriptor.
2522 * This implements both the F_SETLK and F_SETLKW commands of fcntl().
2523 */
2524int fcntl_setlk64(unsigned int fd, struct file *filp, unsigned int cmd,
2525 struct flock64 *flock)
2526{
2527 struct file_lock *file_lock = locks_alloc_lock();
2528 struct file *f;
2529 int error;
2530
2531 if (file_lock == NULL)
2532 return -ENOLCK;
2533
2534 error = flock64_to_posix_lock(filp, file_lock, flock);
2535 if (error)
2536 goto out;
2537
2538 error = check_fmode_for_setlk(file_lock);
2539 if (error)
2540 goto out;
2541
2542 /*
2543 * If the cmd is requesting file-private locks, then set the
2544 * FL_OFDLCK flag and override the owner.
2545 */
2546 switch (cmd) {
2547 case F_OFD_SETLK:
2548 error = -EINVAL;
2549 if (flock->l_pid != 0)
2550 goto out;
2551
2552 cmd = F_SETLK64;
2553 file_lock->c.flc_flags |= FL_OFDLCK;
2554 file_lock->c.flc_owner = filp;
2555 break;
2556 case F_OFD_SETLKW:
2557 error = -EINVAL;
2558 if (flock->l_pid != 0)
2559 goto out;
2560
2561 cmd = F_SETLKW64;
2562 file_lock->c.flc_flags |= FL_OFDLCK;
2563 file_lock->c.flc_owner = filp;
2564 fallthrough;
2565 case F_SETLKW64:
2566 file_lock->c.flc_flags |= FL_SLEEP;
2567 }
2568
2569 error = do_lock_file_wait(filp, cmd, file_lock);
2570
2571 /*
2572 * Detect close/fcntl races and recover by zapping all POSIX locks
2573 * associated with this file and our files_struct, just like on
2574 * filp_flush(). There is no need to do that when we're
2575 * unlocking though, or for OFD locks.
2576 */
2577 if (!error && file_lock->c.flc_type != F_UNLCK &&
2578 !(file_lock->c.flc_flags & FL_OFDLCK)) {
2579 struct files_struct *files = current->files;
2580 /*
2581 * We need that spin_lock here - it prevents reordering between
2582 * update of i_flctx->flc_posix and check for it done in
2583 * close(). rcu_read_lock() wouldn't do.
2584 */
2585 spin_lock(&files->file_lock);
2586 f = files_lookup_fd_locked(files, fd);
2587 spin_unlock(&files->file_lock);
2588 if (f != filp) {
2589 locks_remove_posix(filp, files);
2590 error = -EBADF;
2591 }
2592 }
2593out:
2594 locks_free_lock(file_lock);
2595 return error;
2596}
2597#endif /* BITS_PER_LONG == 32 */
2598
2599/*
2600 * This function is called when the file is being removed
2601 * from the task's fd array. POSIX locks belonging to this task
2602 * are deleted at this time.
2603 */
2604void locks_remove_posix(struct file *filp, fl_owner_t owner)
2605{
2606 int error;
2607 struct inode *inode = file_inode(filp);
2608 struct file_lock lock;
2609 struct file_lock_context *ctx;
2610
2611 /*
2612 * If there are no locks held on this file, we don't need to call
2613 * posix_lock_file(). Another process could be setting a lock on this
2614 * file at the same time, but we wouldn't remove that lock anyway.
2615 */
2616 ctx = locks_inode_context(inode);
2617 if (!ctx || list_empty(&ctx->flc_posix))
2618 return;
2619
2620 locks_init_lock(&lock);
2621 lock.c.flc_type = F_UNLCK;
2622 lock.c.flc_flags = FL_POSIX | FL_CLOSE;
2623 lock.fl_start = 0;
2624 lock.fl_end = OFFSET_MAX;
2625 lock.c.flc_owner = owner;
2626 lock.c.flc_pid = current->tgid;
2627 lock.c.flc_file = filp;
2628 lock.fl_ops = NULL;
2629 lock.fl_lmops = NULL;
2630
2631 error = vfs_lock_file(filp, F_SETLK, &lock, NULL);
2632
2633 if (lock.fl_ops && lock.fl_ops->fl_release_private)
2634 lock.fl_ops->fl_release_private(&lock);
2635 trace_locks_remove_posix(inode, &lock, error);
2636}
2637EXPORT_SYMBOL(locks_remove_posix);
2638
2639/* The i_flctx must be valid when calling into here */
2640static void
2641locks_remove_flock(struct file *filp, struct file_lock_context *flctx)
2642{
2643 struct file_lock fl;
2644 struct inode *inode = file_inode(filp);
2645
2646 if (list_empty(&flctx->flc_flock))
2647 return;
2648
2649 flock_make_lock(filp, &fl, F_UNLCK);
2650 fl.c.flc_flags |= FL_CLOSE;
2651
2652 if (filp->f_op->flock)
2653 filp->f_op->flock(filp, F_SETLKW, &fl);
2654 else
2655 flock_lock_inode(inode, &fl);
2656
2657 if (fl.fl_ops && fl.fl_ops->fl_release_private)
2658 fl.fl_ops->fl_release_private(&fl);
2659}
2660
2661/* The i_flctx must be valid when calling into here */
2662static void
2663locks_remove_lease(struct file *filp, struct file_lock_context *ctx)
2664{
2665 struct file_lease *fl, *tmp;
2666 LIST_HEAD(dispose);
2667
2668 if (list_empty(&ctx->flc_lease))
2669 return;
2670
2671 percpu_down_read(&file_rwsem);
2672 spin_lock(&ctx->flc_lock);
2673 list_for_each_entry_safe(fl, tmp, &ctx->flc_lease, c.flc_list)
2674 if (filp == fl->c.flc_file)
2675 lease_modify(fl, F_UNLCK, &dispose);
2676 spin_unlock(&ctx->flc_lock);
2677 percpu_up_read(&file_rwsem);
2678
2679 locks_dispose_list(&dispose);
2680}
2681
2682/*
2683 * This function is called on the last close of an open file.
2684 */
2685void locks_remove_file(struct file *filp)
2686{
2687 struct file_lock_context *ctx;
2688
2689 ctx = locks_inode_context(file_inode(filp));
2690 if (!ctx)
2691 return;
2692
2693 /* remove any OFD locks */
2694 locks_remove_posix(filp, filp);
2695
2696 /* remove flock locks */
2697 locks_remove_flock(filp, ctx);
2698
2699 /* remove any leases */
2700 locks_remove_lease(filp, ctx);
2701
2702 spin_lock(&ctx->flc_lock);
2703 locks_check_ctx_file_list(filp, &ctx->flc_posix, "POSIX");
2704 locks_check_ctx_file_list(filp, &ctx->flc_flock, "FLOCK");
2705 locks_check_ctx_file_list(filp, &ctx->flc_lease, "LEASE");
2706 spin_unlock(&ctx->flc_lock);
2707}
2708
2709/**
2710 * vfs_cancel_lock - file byte range unblock lock
2711 * @filp: The file to apply the unblock to
2712 * @fl: The lock to be unblocked
2713 *
2714 * Used by lock managers to cancel blocked requests
2715 */
2716int vfs_cancel_lock(struct file *filp, struct file_lock *fl)
2717{
2718 WARN_ON_ONCE(filp != fl->c.flc_file);
2719 if (filp->f_op->lock)
2720 return filp->f_op->lock(filp, F_CANCELLK, fl);
2721 return 0;
2722}
2723EXPORT_SYMBOL_GPL(vfs_cancel_lock);
2724
2725/**
2726 * vfs_inode_has_locks - are any file locks held on @inode?
2727 * @inode: inode to check for locks
2728 *
2729 * Return true if there are any FL_POSIX or FL_FLOCK locks currently
2730 * set on @inode.
2731 */
2732bool vfs_inode_has_locks(struct inode *inode)
2733{
2734 struct file_lock_context *ctx;
2735 bool ret;
2736
2737 ctx = locks_inode_context(inode);
2738 if (!ctx)
2739 return false;
2740
2741 spin_lock(&ctx->flc_lock);
2742 ret = !list_empty(&ctx->flc_posix) || !list_empty(&ctx->flc_flock);
2743 spin_unlock(&ctx->flc_lock);
2744 return ret;
2745}
2746EXPORT_SYMBOL_GPL(vfs_inode_has_locks);
2747
2748#ifdef CONFIG_PROC_FS
2749#include <linux/proc_fs.h>
2750#include <linux/seq_file.h>
2751
2752struct locks_iterator {
2753 int li_cpu;
2754 loff_t li_pos;
2755};
2756
2757static void lock_get_status(struct seq_file *f, struct file_lock_core *flc,
2758 loff_t id, char *pfx, int repeat)
2759{
2760 struct inode *inode = NULL;
2761 unsigned int pid;
2762 struct pid_namespace *proc_pidns = proc_pid_ns(file_inode(f->file)->i_sb);
2763 int type = flc->flc_type;
2764 struct file_lock *fl = file_lock(flc);
2765
2766 pid = locks_translate_pid(flc, proc_pidns);
2767
2768 /*
2769 * If lock owner is dead (and pid is freed) or not visible in current
2770 * pidns, zero is shown as a pid value. Check lock info from
2771 * init_pid_ns to get saved lock pid value.
2772 */
2773 if (flc->flc_file != NULL)
2774 inode = file_inode(flc->flc_file);
2775
2776 seq_printf(f, "%lld: ", id);
2777
2778 if (repeat)
2779 seq_printf(f, "%*s", repeat - 1 + (int)strlen(pfx), pfx);
2780
2781 if (flc->flc_flags & FL_POSIX) {
2782 if (flc->flc_flags & FL_ACCESS)
2783 seq_puts(f, "ACCESS");
2784 else if (flc->flc_flags & FL_OFDLCK)
2785 seq_puts(f, "OFDLCK");
2786 else
2787 seq_puts(f, "POSIX ");
2788
2789 seq_printf(f, " %s ",
2790 (inode == NULL) ? "*NOINODE*" : "ADVISORY ");
2791 } else if (flc->flc_flags & FL_FLOCK) {
2792 seq_puts(f, "FLOCK ADVISORY ");
2793 } else if (flc->flc_flags & (FL_LEASE|FL_DELEG|FL_LAYOUT)) {
2794 struct file_lease *lease = file_lease(flc);
2795
2796 type = target_leasetype(lease);
2797
2798 if (flc->flc_flags & FL_DELEG)
2799 seq_puts(f, "DELEG ");
2800 else
2801 seq_puts(f, "LEASE ");
2802
2803 if (lease_breaking(lease))
2804 seq_puts(f, "BREAKING ");
2805 else if (flc->flc_file)
2806 seq_puts(f, "ACTIVE ");
2807 else
2808 seq_puts(f, "BREAKER ");
2809 } else {
2810 seq_puts(f, "UNKNOWN UNKNOWN ");
2811 }
2812
2813 seq_printf(f, "%s ", (type == F_WRLCK) ? "WRITE" :
2814 (type == F_RDLCK) ? "READ" : "UNLCK");
2815 if (inode) {
2816 /* userspace relies on this representation of dev_t */
2817 seq_printf(f, "%d %02x:%02x:%lu ", pid,
2818 MAJOR(inode->i_sb->s_dev),
2819 MINOR(inode->i_sb->s_dev), inode->i_ino);
2820 } else {
2821 seq_printf(f, "%d <none>:0 ", pid);
2822 }
2823 if (flc->flc_flags & FL_POSIX) {
2824 if (fl->fl_end == OFFSET_MAX)
2825 seq_printf(f, "%Ld EOF\n", fl->fl_start);
2826 else
2827 seq_printf(f, "%Ld %Ld\n", fl->fl_start, fl->fl_end);
2828 } else {
2829 seq_puts(f, "0 EOF\n");
2830 }
2831}
2832
2833static struct file_lock_core *get_next_blocked_member(struct file_lock_core *node)
2834{
2835 struct file_lock_core *tmp;
2836
2837 /* NULL node or root node */
2838 if (node == NULL || node->flc_blocker == NULL)
2839 return NULL;
2840
2841 /* Next member in the linked list could be itself */
2842 tmp = list_next_entry(node, flc_blocked_member);
2843 if (list_entry_is_head(tmp, &node->flc_blocker->flc_blocked_requests,
2844 flc_blocked_member)
2845 || tmp == node) {
2846 return NULL;
2847 }
2848
2849 return tmp;
2850}
2851
2852static int locks_show(struct seq_file *f, void *v)
2853{
2854 struct locks_iterator *iter = f->private;
2855 struct file_lock_core *cur, *tmp;
2856 struct pid_namespace *proc_pidns = proc_pid_ns(file_inode(f->file)->i_sb);
2857 int level = 0;
2858
2859 cur = hlist_entry(v, struct file_lock_core, flc_link);
2860
2861 if (locks_translate_pid(cur, proc_pidns) == 0)
2862 return 0;
2863
2864 /* View this crossed linked list as a binary tree, the first member of flc_blocked_requests
2865 * is the left child of current node, the next silibing in flc_blocked_member is the
2866 * right child, we can alse get the parent of current node from flc_blocker, so this
2867 * question becomes traversal of a binary tree
2868 */
2869 while (cur != NULL) {
2870 if (level)
2871 lock_get_status(f, cur, iter->li_pos, "-> ", level);
2872 else
2873 lock_get_status(f, cur, iter->li_pos, "", level);
2874
2875 if (!list_empty(&cur->flc_blocked_requests)) {
2876 /* Turn left */
2877 cur = list_first_entry_or_null(&cur->flc_blocked_requests,
2878 struct file_lock_core,
2879 flc_blocked_member);
2880 level++;
2881 } else {
2882 /* Turn right */
2883 tmp = get_next_blocked_member(cur);
2884 /* Fall back to parent node */
2885 while (tmp == NULL && cur->flc_blocker != NULL) {
2886 cur = cur->flc_blocker;
2887 level--;
2888 tmp = get_next_blocked_member(cur);
2889 }
2890 cur = tmp;
2891 }
2892 }
2893
2894 return 0;
2895}
2896
2897static void __show_fd_locks(struct seq_file *f,
2898 struct list_head *head, int *id,
2899 struct file *filp, struct files_struct *files)
2900{
2901 struct file_lock_core *fl;
2902
2903 list_for_each_entry(fl, head, flc_list) {
2904
2905 if (filp != fl->flc_file)
2906 continue;
2907 if (fl->flc_owner != files && fl->flc_owner != filp)
2908 continue;
2909
2910 (*id)++;
2911 seq_puts(f, "lock:\t");
2912 lock_get_status(f, fl, *id, "", 0);
2913 }
2914}
2915
2916void show_fd_locks(struct seq_file *f,
2917 struct file *filp, struct files_struct *files)
2918{
2919 struct inode *inode = file_inode(filp);
2920 struct file_lock_context *ctx;
2921 int id = 0;
2922
2923 ctx = locks_inode_context(inode);
2924 if (!ctx)
2925 return;
2926
2927 spin_lock(&ctx->flc_lock);
2928 __show_fd_locks(f, &ctx->flc_flock, &id, filp, files);
2929 __show_fd_locks(f, &ctx->flc_posix, &id, filp, files);
2930 __show_fd_locks(f, &ctx->flc_lease, &id, filp, files);
2931 spin_unlock(&ctx->flc_lock);
2932}
2933
2934static void *locks_start(struct seq_file *f, loff_t *pos)
2935 __acquires(&blocked_lock_lock)
2936{
2937 struct locks_iterator *iter = f->private;
2938
2939 iter->li_pos = *pos + 1;
2940 percpu_down_write(&file_rwsem);
2941 spin_lock(&blocked_lock_lock);
2942 return seq_hlist_start_percpu(&file_lock_list.hlist, &iter->li_cpu, *pos);
2943}
2944
2945static void *locks_next(struct seq_file *f, void *v, loff_t *pos)
2946{
2947 struct locks_iterator *iter = f->private;
2948
2949 ++iter->li_pos;
2950 return seq_hlist_next_percpu(v, &file_lock_list.hlist, &iter->li_cpu, pos);
2951}
2952
2953static void locks_stop(struct seq_file *f, void *v)
2954 __releases(&blocked_lock_lock)
2955{
2956 spin_unlock(&blocked_lock_lock);
2957 percpu_up_write(&file_rwsem);
2958}
2959
2960static const struct seq_operations locks_seq_operations = {
2961 .start = locks_start,
2962 .next = locks_next,
2963 .stop = locks_stop,
2964 .show = locks_show,
2965};
2966
2967static int __init proc_locks_init(void)
2968{
2969 proc_create_seq_private("locks", 0, NULL, &locks_seq_operations,
2970 sizeof(struct locks_iterator), NULL);
2971 return 0;
2972}
2973fs_initcall(proc_locks_init);
2974#endif
2975
2976static int __init filelock_init(void)
2977{
2978 int i;
2979
2980 flctx_cache = kmem_cache_create("file_lock_ctx",
2981 sizeof(struct file_lock_context), 0, SLAB_PANIC, NULL);
2982
2983 filelock_cache = kmem_cache_create("file_lock_cache",
2984 sizeof(struct file_lock), 0, SLAB_PANIC, NULL);
2985
2986 filelease_cache = kmem_cache_create("file_lease_cache",
2987 sizeof(struct file_lease), 0, SLAB_PANIC, NULL);
2988
2989 for_each_possible_cpu(i) {
2990 struct file_lock_list_struct *fll = per_cpu_ptr(&file_lock_list, i);
2991
2992 spin_lock_init(&fll->lock);
2993 INIT_HLIST_HEAD(&fll->hlist);
2994 }
2995
2996 lease_notifier_chain_init();
2997 return 0;
2998}
2999core_initcall(filelock_init);