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