blob: b27a3005d78df9fccd74343bd4a9f93f9f6753b1 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
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.
Paul Bolle395cf962011-08-15 02:02:26 +020063 * See 'Documentation/filesystems/mandatory-locking.txt' for details.
Linus Torvalds1da177e2005-04-16 15:20:36 -070064 * Andy Walker (andy@lysaker.kvaerner.no), April 06, 1996.
65 *
66 * Don't allow mandatory locks on mmap()'ed files. Added simple functions to
67 * check if a file has mandatory locks, used by mmap(), open() and creat() to
68 * see if system call should be rejected. Ref. HP-UX/SunOS/Solaris Reference
69 * Manual, Section 2.
70 * Andy Walker (andy@lysaker.kvaerner.no), April 09, 1996.
71 *
72 * Tidied up block list handling. Added '/proc/locks' interface.
73 * Andy Walker (andy@lysaker.kvaerner.no), April 24, 1996.
74 *
75 * Fixed deadlock condition for pathological code that mixes calls to
76 * flock() and fcntl().
77 * Andy Walker (andy@lysaker.kvaerner.no), April 29, 1996.
78 *
79 * Allow only one type of locking scheme (FL_POSIX or FL_FLOCK) to be in use
80 * for a given file at a time. Changed the CONFIG_LOCK_MANDATORY scheme to
81 * guarantee sensible behaviour in the case where file system modules might
82 * be compiled with different options than the kernel itself.
83 * Andy Walker (andy@lysaker.kvaerner.no), May 15, 1996.
84 *
85 * Added a couple of missing wake_up() calls. Thanks to Thomas Meckel
86 * (Thomas.Meckel@mni.fh-giessen.de) for spotting this.
87 * Andy Walker (andy@lysaker.kvaerner.no), May 15, 1996.
88 *
89 * Changed FL_POSIX locks to use the block list in the same way as FL_FLOCK
90 * locks. Changed process synchronisation to avoid dereferencing locks that
91 * have already been freed.
92 * Andy Walker (andy@lysaker.kvaerner.no), Sep 21, 1996.
93 *
94 * Made the block list a circular list to minimise searching in the list.
95 * Andy Walker (andy@lysaker.kvaerner.no), Sep 25, 1996.
96 *
97 * Made mandatory locking a mount option. Default is not to allow mandatory
98 * locking.
99 * Andy Walker (andy@lysaker.kvaerner.no), Oct 04, 1996.
100 *
101 * Some adaptations for NFS support.
102 * Olaf Kirch (okir@monad.swb.de), Dec 1996,
103 *
104 * Fixed /proc/locks interface so that we can't overrun the buffer we are handed.
105 * Andy Walker (andy@lysaker.kvaerner.no), May 12, 1997.
106 *
107 * Use slab allocator instead of kmalloc/kfree.
108 * Use generic list implementation from <linux/list.h>.
109 * Sped up posix_locks_deadlock by only considering blocked locks.
110 * Matthew Wilcox <willy@debian.org>, March, 2000.
111 *
112 * Leases and LOCK_MAND
113 * Matthew Wilcox <willy@debian.org>, June, 2000.
114 * Stephen Rothwell <sfr@canb.auug.org.au>, June, 2000.
115 */
116
117#include <linux/capability.h>
118#include <linux/file.h>
Al Viro9f3acc32008-04-24 07:44:08 -0400119#include <linux/fdtable.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -0700120#include <linux/fs.h>
121#include <linux/init.h>
122#include <linux/module.h>
123#include <linux/security.h>
124#include <linux/slab.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -0700125#include <linux/syscalls.h>
126#include <linux/time.h>
Dipankar Sarma4fb3a532005-09-16 19:28:13 -0700127#include <linux/rcupdate.h>
Vitaliy Gusevab1f1612008-01-17 00:07:08 +0000128#include <linux/pid_namespace.h>
Jeff Layton48f74182013-06-21 08:58:18 -0400129#include <linux/hashtable.h>
Jeff Layton7012b022013-06-21 08:58:22 -0400130#include <linux/percpu.h>
131#include <linux/lglock.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -0700132
Linus Torvalds1da177e2005-04-16 15:20:36 -0700133#include <asm/uaccess.h>
134
135#define IS_POSIX(fl) (fl->fl_flags & FL_POSIX)
136#define IS_FLOCK(fl) (fl->fl_flags & FL_FLOCK)
137#define IS_LEASE(fl) (fl->fl_flags & FL_LEASE)
138
J. Bruce Fieldsab83fa42011-07-26 20:10:51 -0400139static bool lease_breaking(struct file_lock *fl)
140{
J. Bruce Fields778fc542011-07-26 18:25:49 -0400141 return fl->fl_flags & (FL_UNLOCK_PENDING | FL_DOWNGRADE_PENDING);
142}
143
144static int target_leasetype(struct file_lock *fl)
145{
146 if (fl->fl_flags & FL_UNLOCK_PENDING)
147 return F_UNLCK;
148 if (fl->fl_flags & FL_DOWNGRADE_PENDING)
149 return F_RDLCK;
150 return fl->fl_type;
J. Bruce Fieldsab83fa42011-07-26 20:10:51 -0400151}
152
Linus Torvalds1da177e2005-04-16 15:20:36 -0700153int leases_enable = 1;
154int lease_break_time = 45;
155
156#define for_each_lock(inode, lockp) \
157 for (lockp = &inode->i_flock; *lockp != NULL; lockp = &(*lockp)->fl_next)
158
Jeff Layton1c8c6012013-06-21 08:58:15 -0400159/*
Jeff Layton7012b022013-06-21 08:58:22 -0400160 * The global file_lock_list is only used for displaying /proc/locks, so we
161 * keep a list on each CPU, with each list protected by its own spinlock via
162 * the file_lock_lglock. Note that alterations to the list also require that
163 * the relevant i_lock is held.
Jeff Layton1c8c6012013-06-21 08:58:15 -0400164 */
Jeff Layton7012b022013-06-21 08:58:22 -0400165DEFINE_STATIC_LGLOCK(file_lock_lglock);
166static DEFINE_PER_CPU(struct hlist_head, file_lock_list);
Jeff Layton88974692013-06-21 08:58:14 -0400167
Jeff Layton1c8c6012013-06-21 08:58:15 -0400168/*
Jeff Layton48f74182013-06-21 08:58:18 -0400169 * The blocked_hash is used to find POSIX lock loops for deadlock detection.
Jeff Layton7b2296a2013-06-21 08:58:20 -0400170 * It is protected by blocked_lock_lock.
Jeff Layton48f74182013-06-21 08:58:18 -0400171 *
172 * We hash locks by lockowner in order to optimize searching for the lock a
173 * particular lockowner is waiting on.
174 *
175 * FIXME: make this value scale via some heuristic? We generally will want more
176 * buckets when we have more lockowners holding locks, but that's a little
177 * difficult to determine without knowing what the workload will look like.
Jeff Layton1c8c6012013-06-21 08:58:15 -0400178 */
Jeff Layton48f74182013-06-21 08:58:18 -0400179#define BLOCKED_HASH_BITS 7
180static DEFINE_HASHTABLE(blocked_hash, BLOCKED_HASH_BITS);
Jeff Layton88974692013-06-21 08:58:14 -0400181
Jeff Layton1c8c6012013-06-21 08:58:15 -0400182/*
Jeff Layton7b2296a2013-06-21 08:58:20 -0400183 * This lock protects the blocked_hash. Generally, if you're accessing it, you
184 * want to be holding this lock.
Jeff Layton1c8c6012013-06-21 08:58:15 -0400185 *
186 * In addition, it also protects the fl->fl_block list, and the fl->fl_next
187 * pointer for file_lock structures that are acting as lock requests (in
188 * contrast to those that are acting as records of acquired locks).
189 *
190 * Note that when we acquire this lock in order to change the above fields,
191 * we often hold the i_lock as well. In certain cases, when reading the fields
192 * protected by this lock, we can skip acquiring it iff we already hold the
193 * i_lock.
194 *
195 * In particular, adding an entry to the fl_block list requires that you hold
196 * both the i_lock and the blocked_lock_lock (acquired in that order). Deleting
197 * an entry from the list however only requires the file_lock_lock.
198 */
Jeff Layton7b2296a2013-06-21 08:58:20 -0400199static DEFINE_SPINLOCK(blocked_lock_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700200
Christoph Lametere18b8902006-12-06 20:33:20 -0800201static struct kmem_cache *filelock_cache __read_mostly;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700202
Miklos Szerediee19cc42011-07-07 13:06:09 +0200203static void locks_init_lock_heads(struct file_lock *fl)
Miklos Szeredia51cb912011-07-06 12:33:55 +0200204{
Jeff Layton139ca042013-06-21 08:58:17 -0400205 INIT_HLIST_NODE(&fl->fl_link);
Miklos Szerediee19cc42011-07-07 13:06:09 +0200206 INIT_LIST_HEAD(&fl->fl_block);
207 init_waitqueue_head(&fl->fl_wait);
Miklos Szeredia51cb912011-07-06 12:33:55 +0200208}
209
Linus Torvalds1da177e2005-04-16 15:20:36 -0700210/* Allocate an empty lock structure. */
Arnd Bergmannc5b1f0d2010-10-27 15:46:08 +0200211struct file_lock *locks_alloc_lock(void)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700212{
Miklos Szerediee19cc42011-07-07 13:06:09 +0200213 struct file_lock *fl = kmem_cache_zalloc(filelock_cache, GFP_KERNEL);
Miklos Szeredia51cb912011-07-06 12:33:55 +0200214
215 if (fl)
Miklos Szerediee19cc42011-07-07 13:06:09 +0200216 locks_init_lock_heads(fl);
Miklos Szeredia51cb912011-07-06 12:33:55 +0200217
218 return fl;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700219}
Arnd Bergmannc5b1f0d2010-10-27 15:46:08 +0200220EXPORT_SYMBOL_GPL(locks_alloc_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700221
Felix Blyakhera9e61e22009-03-31 15:12:56 -0500222void locks_release_private(struct file_lock *fl)
Trond Myklebust47831f32006-03-20 13:44:05 -0500223{
224 if (fl->fl_ops) {
225 if (fl->fl_ops->fl_release_private)
226 fl->fl_ops->fl_release_private(fl);
227 fl->fl_ops = NULL;
228 }
J. Bruce Fields068535f2012-08-01 07:56:16 -0400229 fl->fl_lmops = NULL;
Trond Myklebust47831f32006-03-20 13:44:05 -0500230
231}
Felix Blyakhera9e61e22009-03-31 15:12:56 -0500232EXPORT_SYMBOL_GPL(locks_release_private);
Trond Myklebust47831f32006-03-20 13:44:05 -0500233
Linus Torvalds1da177e2005-04-16 15:20:36 -0700234/* Free a lock which is not in use. */
J. Bruce Fields05fa3132010-10-30 17:31:15 -0400235void locks_free_lock(struct file_lock *fl)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700236{
Miklos Szeredi5ce29642006-03-31 02:30:29 -0800237 BUG_ON(waitqueue_active(&fl->fl_wait));
238 BUG_ON(!list_empty(&fl->fl_block));
Jeff Layton139ca042013-06-21 08:58:17 -0400239 BUG_ON(!hlist_unhashed(&fl->fl_link));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700240
Trond Myklebust47831f32006-03-20 13:44:05 -0500241 locks_release_private(fl);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700242 kmem_cache_free(filelock_cache, fl);
243}
J. Bruce Fields05fa3132010-10-30 17:31:15 -0400244EXPORT_SYMBOL(locks_free_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700245
246void locks_init_lock(struct file_lock *fl)
247{
Miklos Szerediee19cc42011-07-07 13:06:09 +0200248 memset(fl, 0, sizeof(struct file_lock));
249 locks_init_lock_heads(fl);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700250}
251
252EXPORT_SYMBOL(locks_init_lock);
253
Trond Myklebust47831f32006-03-20 13:44:05 -0500254static void locks_copy_private(struct file_lock *new, struct file_lock *fl)
255{
256 if (fl->fl_ops) {
257 if (fl->fl_ops->fl_copy_lock)
258 fl->fl_ops->fl_copy_lock(new, fl);
259 new->fl_ops = fl->fl_ops;
260 }
Christoph Hellwigbb8430a2010-10-31 08:35:31 -0400261 if (fl->fl_lmops)
Trond Myklebust47831f32006-03-20 13:44:05 -0500262 new->fl_lmops = fl->fl_lmops;
Trond Myklebust47831f32006-03-20 13:44:05 -0500263}
264
Linus Torvalds1da177e2005-04-16 15:20:36 -0700265/*
266 * Initialize a new lock from an existing file_lock structure.
267 */
J. Bruce Fields1a747ee2008-04-24 10:08:22 -0400268void __locks_copy_lock(struct file_lock *new, const struct file_lock *fl)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700269{
270 new->fl_owner = fl->fl_owner;
271 new->fl_pid = fl->fl_pid;
Trond Myklebust09969052006-03-20 13:44:38 -0500272 new->fl_file = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700273 new->fl_flags = fl->fl_flags;
274 new->fl_type = fl->fl_type;
275 new->fl_start = fl->fl_start;
276 new->fl_end = fl->fl_end;
Trond Myklebust09969052006-03-20 13:44:38 -0500277 new->fl_ops = NULL;
278 new->fl_lmops = NULL;
279}
Roland Dreier3dd7b712008-04-25 15:32:51 -0700280EXPORT_SYMBOL(__locks_copy_lock);
Trond Myklebust09969052006-03-20 13:44:38 -0500281
282void locks_copy_lock(struct file_lock *new, struct file_lock *fl)
283{
284 locks_release_private(new);
285
286 __locks_copy_lock(new, fl);
287 new->fl_file = fl->fl_file;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700288 new->fl_ops = fl->fl_ops;
289 new->fl_lmops = fl->fl_lmops;
Trond Myklebust47831f32006-03-20 13:44:05 -0500290
291 locks_copy_private(new, fl);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700292}
293
294EXPORT_SYMBOL(locks_copy_lock);
295
296static inline int flock_translate_cmd(int cmd) {
297 if (cmd & LOCK_MAND)
298 return cmd & (LOCK_MAND | LOCK_RW);
299 switch (cmd) {
300 case LOCK_SH:
301 return F_RDLCK;
302 case LOCK_EX:
303 return F_WRLCK;
304 case LOCK_UN:
305 return F_UNLCK;
306 }
307 return -EINVAL;
308}
309
310/* Fill in a file_lock structure with an appropriate FLOCK lock. */
311static int flock_make_lock(struct file *filp, struct file_lock **lock,
312 unsigned int cmd)
313{
314 struct file_lock *fl;
315 int type = flock_translate_cmd(cmd);
316 if (type < 0)
317 return type;
318
319 fl = locks_alloc_lock();
320 if (fl == NULL)
321 return -ENOMEM;
322
323 fl->fl_file = filp;
324 fl->fl_pid = current->tgid;
325 fl->fl_flags = FL_FLOCK;
326 fl->fl_type = type;
327 fl->fl_end = OFFSET_MAX;
328
329 *lock = fl;
330 return 0;
331}
332
J. Bruce Fields0ec4f432012-07-23 15:17:17 -0400333static int assign_type(struct file_lock *fl, long type)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700334{
335 switch (type) {
336 case F_RDLCK:
337 case F_WRLCK:
338 case F_UNLCK:
339 fl->fl_type = type;
340 break;
341 default:
342 return -EINVAL;
343 }
344 return 0;
345}
346
347/* Verify a "struct flock" and copy it to a "struct file_lock" as a POSIX
348 * style lock.
349 */
350static int flock_to_posix_lock(struct file *filp, struct file_lock *fl,
351 struct flock *l)
352{
353 off_t start, end;
354
355 switch (l->l_whence) {
Josef 'Jeff' Sipekf5579f82006-09-30 23:27:35 -0700356 case SEEK_SET:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700357 start = 0;
358 break;
Josef 'Jeff' Sipekf5579f82006-09-30 23:27:35 -0700359 case SEEK_CUR:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700360 start = filp->f_pos;
361 break;
Josef 'Jeff' Sipekf5579f82006-09-30 23:27:35 -0700362 case SEEK_END:
Al Viro496ad9a2013-01-23 17:07:38 -0500363 start = i_size_read(file_inode(filp));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700364 break;
365 default:
366 return -EINVAL;
367 }
368
369 /* POSIX-1996 leaves the case l->l_len < 0 undefined;
370 POSIX-2001 defines it. */
371 start += l->l_start;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700372 if (start < 0)
373 return -EINVAL;
Trond Myklebust4c780a42005-10-18 14:20:21 -0700374 fl->fl_end = OFFSET_MAX;
375 if (l->l_len > 0) {
376 end = start + l->l_len - 1;
377 fl->fl_end = end;
378 } else if (l->l_len < 0) {
379 end = start - 1;
380 fl->fl_end = end;
381 start += l->l_len;
382 if (start < 0)
383 return -EINVAL;
384 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700385 fl->fl_start = start; /* we record the absolute position */
Trond Myklebust4c780a42005-10-18 14:20:21 -0700386 if (fl->fl_end < fl->fl_start)
387 return -EOVERFLOW;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700388
389 fl->fl_owner = current->files;
390 fl->fl_pid = current->tgid;
391 fl->fl_file = filp;
392 fl->fl_flags = FL_POSIX;
393 fl->fl_ops = NULL;
394 fl->fl_lmops = NULL;
395
396 return assign_type(fl, l->l_type);
397}
398
399#if BITS_PER_LONG == 32
400static int flock64_to_posix_lock(struct file *filp, struct file_lock *fl,
401 struct flock64 *l)
402{
403 loff_t start;
404
405 switch (l->l_whence) {
Josef 'Jeff' Sipekf5579f82006-09-30 23:27:35 -0700406 case SEEK_SET:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700407 start = 0;
408 break;
Josef 'Jeff' Sipekf5579f82006-09-30 23:27:35 -0700409 case SEEK_CUR:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700410 start = filp->f_pos;
411 break;
Josef 'Jeff' Sipekf5579f82006-09-30 23:27:35 -0700412 case SEEK_END:
Al Viro496ad9a2013-01-23 17:07:38 -0500413 start = i_size_read(file_inode(filp));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700414 break;
415 default:
416 return -EINVAL;
417 }
418
Trond Myklebust4c780a42005-10-18 14:20:21 -0700419 start += l->l_start;
420 if (start < 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700421 return -EINVAL;
Trond Myklebust4c780a42005-10-18 14:20:21 -0700422 fl->fl_end = OFFSET_MAX;
423 if (l->l_len > 0) {
424 fl->fl_end = start + l->l_len - 1;
425 } else if (l->l_len < 0) {
426 fl->fl_end = start - 1;
427 start += l->l_len;
428 if (start < 0)
429 return -EINVAL;
430 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700431 fl->fl_start = start; /* we record the absolute position */
Trond Myklebust4c780a42005-10-18 14:20:21 -0700432 if (fl->fl_end < fl->fl_start)
433 return -EOVERFLOW;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700434
435 fl->fl_owner = current->files;
436 fl->fl_pid = current->tgid;
437 fl->fl_file = filp;
438 fl->fl_flags = FL_POSIX;
439 fl->fl_ops = NULL;
440 fl->fl_lmops = NULL;
441
Namhyung Kimf32cb532011-01-17 15:45:59 +0900442 return assign_type(fl, l->l_type);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700443}
444#endif
445
446/* default lease lock manager operations */
447static void lease_break_callback(struct file_lock *fl)
448{
449 kill_fasync(&fl->fl_fasync, SIGIO, POLL_MSG);
450}
451
Alexey Dobriyan7b021962009-09-21 17:01:12 -0700452static const struct lock_manager_operations lease_manager_ops = {
J. Bruce Fields8fb47a42011-07-20 20:21:59 -0400453 .lm_break = lease_break_callback,
J. Bruce Fields8fb47a42011-07-20 20:21:59 -0400454 .lm_change = lease_modify,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700455};
456
457/*
458 * Initialize a lease, use the default lock manager operations
459 */
J. Bruce Fields0ec4f432012-07-23 15:17:17 -0400460static int lease_init(struct file *filp, long type, struct file_lock *fl)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700461 {
Trond Myklebust75dff552006-05-07 23:02:42 -0400462 if (assign_type(fl, type) != 0)
463 return -EINVAL;
464
Linus Torvalds1da177e2005-04-16 15:20:36 -0700465 fl->fl_owner = current->files;
466 fl->fl_pid = current->tgid;
467
468 fl->fl_file = filp;
469 fl->fl_flags = FL_LEASE;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700470 fl->fl_start = 0;
471 fl->fl_end = OFFSET_MAX;
472 fl->fl_ops = NULL;
473 fl->fl_lmops = &lease_manager_ops;
474 return 0;
475}
476
477/* Allocate a file_lock initialised to this type of lease */
J. Bruce Fields0ec4f432012-07-23 15:17:17 -0400478static struct file_lock *lease_alloc(struct file *filp, long type)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700479{
480 struct file_lock *fl = locks_alloc_lock();
Trond Myklebust75dff552006-05-07 23:02:42 -0400481 int error = -ENOMEM;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700482
483 if (fl == NULL)
J. Bruce Fieldse32b8ee2007-03-01 14:34:35 -0500484 return ERR_PTR(error);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700485
486 error = lease_init(filp, type, fl);
Trond Myklebust75dff552006-05-07 23:02:42 -0400487 if (error) {
488 locks_free_lock(fl);
J. Bruce Fieldse32b8ee2007-03-01 14:34:35 -0500489 return ERR_PTR(error);
Trond Myklebust75dff552006-05-07 23:02:42 -0400490 }
J. Bruce Fieldse32b8ee2007-03-01 14:34:35 -0500491 return fl;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700492}
493
494/* Check if two locks overlap each other.
495 */
496static inline int locks_overlap(struct file_lock *fl1, struct file_lock *fl2)
497{
498 return ((fl1->fl_end >= fl2->fl_start) &&
499 (fl2->fl_end >= fl1->fl_start));
500}
501
502/*
503 * Check whether two locks have the same owner.
504 */
Matt Mackall33443c42006-01-08 01:05:22 -0800505static int posix_same_owner(struct file_lock *fl1, struct file_lock *fl2)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700506{
J. Bruce Fields8fb47a42011-07-20 20:21:59 -0400507 if (fl1->fl_lmops && fl1->fl_lmops->lm_compare_owner)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700508 return fl2->fl_lmops == fl1->fl_lmops &&
J. Bruce Fields8fb47a42011-07-20 20:21:59 -0400509 fl1->fl_lmops->lm_compare_owner(fl1, fl2);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700510 return fl1->fl_owner == fl2->fl_owner;
511}
512
Jeff Layton7012b022013-06-21 08:58:22 -0400513/* Must be called with the i_lock held! */
Jeff Layton88974692013-06-21 08:58:14 -0400514static inline void
515locks_insert_global_locks(struct file_lock *fl)
516{
Jeff Layton7012b022013-06-21 08:58:22 -0400517 lg_local_lock(&file_lock_lglock);
518 fl->fl_link_cpu = smp_processor_id();
519 hlist_add_head(&fl->fl_link, this_cpu_ptr(&file_lock_list));
520 lg_local_unlock(&file_lock_lglock);
Jeff Layton88974692013-06-21 08:58:14 -0400521}
522
Jeff Layton7012b022013-06-21 08:58:22 -0400523/* Must be called with the i_lock held! */
Jeff Layton88974692013-06-21 08:58:14 -0400524static inline void
525locks_delete_global_locks(struct file_lock *fl)
526{
Jeff Layton7012b022013-06-21 08:58:22 -0400527 /*
528 * Avoid taking lock if already unhashed. This is safe since this check
529 * is done while holding the i_lock, and new insertions into the list
530 * also require that it be held.
531 */
532 if (hlist_unhashed(&fl->fl_link))
533 return;
534 lg_local_lock_cpu(&file_lock_lglock, fl->fl_link_cpu);
Jeff Layton139ca042013-06-21 08:58:17 -0400535 hlist_del_init(&fl->fl_link);
Jeff Layton7012b022013-06-21 08:58:22 -0400536 lg_local_unlock_cpu(&file_lock_lglock, fl->fl_link_cpu);
Jeff Layton88974692013-06-21 08:58:14 -0400537}
538
Jeff Layton3999e492013-06-21 08:58:19 -0400539static unsigned long
540posix_owner_key(struct file_lock *fl)
541{
542 if (fl->fl_lmops && fl->fl_lmops->lm_owner_key)
543 return fl->fl_lmops->lm_owner_key(fl);
544 return (unsigned long)fl->fl_owner;
545}
546
Jeff Layton88974692013-06-21 08:58:14 -0400547static inline void
548locks_insert_global_blocked(struct file_lock *waiter)
549{
Jeff Layton3999e492013-06-21 08:58:19 -0400550 hash_add(blocked_hash, &waiter->fl_link, posix_owner_key(waiter));
Jeff Layton88974692013-06-21 08:58:14 -0400551}
552
553static inline void
554locks_delete_global_blocked(struct file_lock *waiter)
555{
Jeff Layton48f74182013-06-21 08:58:18 -0400556 hash_del(&waiter->fl_link);
Jeff Layton88974692013-06-21 08:58:14 -0400557}
558
Linus Torvalds1da177e2005-04-16 15:20:36 -0700559/* Remove waiter from blocker's block list.
560 * When blocker ends up pointing to itself then the list is empty.
Jeff Layton1c8c6012013-06-21 08:58:15 -0400561 *
Jeff Layton7b2296a2013-06-21 08:58:20 -0400562 * Must be called with blocked_lock_lock held.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700563 */
Matt Mackall33443c42006-01-08 01:05:22 -0800564static void __locks_delete_block(struct file_lock *waiter)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700565{
Jeff Layton88974692013-06-21 08:58:14 -0400566 locks_delete_global_blocked(waiter);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700567 list_del_init(&waiter->fl_block);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700568 waiter->fl_next = NULL;
569}
570
Jeff Layton1a9e64a2013-06-21 08:58:10 -0400571static void locks_delete_block(struct file_lock *waiter)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700572{
Jeff Layton7b2296a2013-06-21 08:58:20 -0400573 spin_lock(&blocked_lock_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700574 __locks_delete_block(waiter);
Jeff Layton7b2296a2013-06-21 08:58:20 -0400575 spin_unlock(&blocked_lock_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700576}
577
578/* Insert waiter into blocker's block list.
579 * We use a circular list so that processes can be easily woken up in
580 * the order they blocked. The documentation doesn't require this but
581 * it seems like the reasonable thing to do.
Jeff Layton1c8c6012013-06-21 08:58:15 -0400582 *
Jeff Layton7b2296a2013-06-21 08:58:20 -0400583 * Must be called with both the i_lock and blocked_lock_lock held. The fl_block
Jeff Layton4e8c7652013-06-21 08:58:16 -0400584 * list itself is protected by the file_lock_list, but by ensuring that the
Jeff Layton7b2296a2013-06-21 08:58:20 -0400585 * i_lock is also held on insertions we can avoid taking the blocked_lock_lock
Jeff Layton4e8c7652013-06-21 08:58:16 -0400586 * in some cases when we see that the fl_block list is empty.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700587 */
Jeff Layton1c8c6012013-06-21 08:58:15 -0400588static void __locks_insert_block(struct file_lock *blocker,
589 struct file_lock *waiter)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700590{
J. Bruce Fields6dc0fe82006-03-26 01:37:24 -0800591 BUG_ON(!list_empty(&waiter->fl_block));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700592 waiter->fl_next = blocker;
Jeff Layton88974692013-06-21 08:58:14 -0400593 list_add_tail(&waiter->fl_block, &blocker->fl_block);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700594 if (IS_POSIX(blocker))
Jeff Layton1c8c6012013-06-21 08:58:15 -0400595 locks_insert_global_blocked(waiter);
596}
597
598/* Must be called with i_lock held. */
599static void locks_insert_block(struct file_lock *blocker,
600 struct file_lock *waiter)
601{
Jeff Layton7b2296a2013-06-21 08:58:20 -0400602 spin_lock(&blocked_lock_lock);
Jeff Layton1c8c6012013-06-21 08:58:15 -0400603 __locks_insert_block(blocker, waiter);
Jeff Layton7b2296a2013-06-21 08:58:20 -0400604 spin_unlock(&blocked_lock_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700605}
606
Jeff Layton1cb36012013-06-21 08:58:12 -0400607/*
608 * Wake up processes blocked waiting for blocker.
609 *
Jeff Layton1c8c6012013-06-21 08:58:15 -0400610 * Must be called with the inode->i_lock held!
Linus Torvalds1da177e2005-04-16 15:20:36 -0700611 */
612static void locks_wake_up_blocks(struct file_lock *blocker)
613{
Jeff Layton4e8c7652013-06-21 08:58:16 -0400614 /*
615 * Avoid taking global lock if list is empty. This is safe since new
616 * blocked requests are only added to the list under the i_lock, and
617 * the i_lock is always held here. Note that removal from the fl_block
618 * list does not require the i_lock, so we must recheck list_empty()
Jeff Layton7b2296a2013-06-21 08:58:20 -0400619 * after acquiring the blocked_lock_lock.
Jeff Layton4e8c7652013-06-21 08:58:16 -0400620 */
621 if (list_empty(&blocker->fl_block))
622 return;
623
Jeff Layton7b2296a2013-06-21 08:58:20 -0400624 spin_lock(&blocked_lock_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700625 while (!list_empty(&blocker->fl_block)) {
Pavel Emelyanovf0c1cd02007-09-19 16:44:07 +0400626 struct file_lock *waiter;
627
628 waiter = list_first_entry(&blocker->fl_block,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700629 struct file_lock, fl_block);
630 __locks_delete_block(waiter);
J. Bruce Fields8fb47a42011-07-20 20:21:59 -0400631 if (waiter->fl_lmops && waiter->fl_lmops->lm_notify)
632 waiter->fl_lmops->lm_notify(waiter);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700633 else
634 wake_up(&waiter->fl_wait);
635 }
Jeff Layton7b2296a2013-06-21 08:58:20 -0400636 spin_unlock(&blocked_lock_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700637}
638
639/* Insert file lock fl into an inode's lock list at the position indicated
640 * by pos. At the same time add the lock to the global file lock list.
Jeff Layton1c8c6012013-06-21 08:58:15 -0400641 *
642 * Must be called with the i_lock held!
Linus Torvalds1da177e2005-04-16 15:20:36 -0700643 */
644static void locks_insert_lock(struct file_lock **pos, struct file_lock *fl)
645{
Vitaliy Gusevab1f1612008-01-17 00:07:08 +0000646 fl->fl_nspid = get_pid(task_tgid(current));
647
Linus Torvalds1da177e2005-04-16 15:20:36 -0700648 /* insert into file's list */
649 fl->fl_next = *pos;
650 *pos = fl;
Jeff Layton88974692013-06-21 08:58:14 -0400651
652 locks_insert_global_locks(fl);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700653}
654
655/*
656 * Delete a lock and then free it.
657 * Wake up processes that are blocked waiting for this lock,
658 * notify the FS that the lock has been cleared and
659 * finally free the lock.
Jeff Layton1c8c6012013-06-21 08:58:15 -0400660 *
661 * Must be called with the i_lock held!
Linus Torvalds1da177e2005-04-16 15:20:36 -0700662 */
663static void locks_delete_lock(struct file_lock **thisfl_p)
664{
665 struct file_lock *fl = *thisfl_p;
666
Jeff Layton88974692013-06-21 08:58:14 -0400667 locks_delete_global_locks(fl);
668
Linus Torvalds1da177e2005-04-16 15:20:36 -0700669 *thisfl_p = fl->fl_next;
670 fl->fl_next = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700671
Vitaliy Gusevab1f1612008-01-17 00:07:08 +0000672 if (fl->fl_nspid) {
673 put_pid(fl->fl_nspid);
674 fl->fl_nspid = NULL;
675 }
676
Linus Torvalds1da177e2005-04-16 15:20:36 -0700677 locks_wake_up_blocks(fl);
678 locks_free_lock(fl);
679}
680
681/* Determine if lock sys_fl blocks lock caller_fl. Common functionality
682 * checks for shared/exclusive status of overlapping locks.
683 */
684static int locks_conflict(struct file_lock *caller_fl, struct file_lock *sys_fl)
685{
686 if (sys_fl->fl_type == F_WRLCK)
687 return 1;
688 if (caller_fl->fl_type == F_WRLCK)
689 return 1;
690 return 0;
691}
692
693/* Determine if lock sys_fl blocks lock caller_fl. POSIX specific
694 * checking before calling the locks_conflict().
695 */
696static int posix_locks_conflict(struct file_lock *caller_fl, struct file_lock *sys_fl)
697{
698 /* POSIX locks owned by the same process do not conflict with
699 * each other.
700 */
701 if (!IS_POSIX(sys_fl) || posix_same_owner(caller_fl, sys_fl))
702 return (0);
703
704 /* Check whether they overlap */
705 if (!locks_overlap(caller_fl, sys_fl))
706 return 0;
707
708 return (locks_conflict(caller_fl, sys_fl));
709}
710
711/* Determine if lock sys_fl blocks lock caller_fl. FLOCK specific
712 * checking before calling the locks_conflict().
713 */
714static int flock_locks_conflict(struct file_lock *caller_fl, struct file_lock *sys_fl)
715{
716 /* FLOCK locks referring to the same filp do not conflict with
717 * each other.
718 */
719 if (!IS_FLOCK(sys_fl) || (caller_fl->fl_file == sys_fl->fl_file))
720 return (0);
721 if ((caller_fl->fl_type & LOCK_MAND) || (sys_fl->fl_type & LOCK_MAND))
722 return 0;
723
724 return (locks_conflict(caller_fl, sys_fl));
725}
726
J. Bruce Fields6d34ac12007-05-11 16:09:32 -0400727void
Marc Eshel9d6a8c52007-02-21 00:55:18 -0500728posix_test_lock(struct file *filp, struct file_lock *fl)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700729{
730 struct file_lock *cfl;
Jeff Layton1c8c6012013-06-21 08:58:15 -0400731 struct inode *inode = file_inode(filp);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700732
Jeff Layton1c8c6012013-06-21 08:58:15 -0400733 spin_lock(&inode->i_lock);
Al Viro496ad9a2013-01-23 17:07:38 -0500734 for (cfl = file_inode(filp)->i_flock; cfl; cfl = cfl->fl_next) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700735 if (!IS_POSIX(cfl))
736 continue;
J. Bruce Fieldsb842e242007-05-10 19:02:07 -0400737 if (posix_locks_conflict(fl, cfl))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700738 break;
739 }
Vitaliy Gusevab1f1612008-01-17 00:07:08 +0000740 if (cfl) {
Marc Eshel9d6a8c52007-02-21 00:55:18 -0500741 __locks_copy_lock(fl, cfl);
Vitaliy Gusevab1f1612008-01-17 00:07:08 +0000742 if (cfl->fl_nspid)
Pavel Emelyanov6c5f3e72008-02-08 04:19:20 -0800743 fl->fl_pid = pid_vnr(cfl->fl_nspid);
Vitaliy Gusevab1f1612008-01-17 00:07:08 +0000744 } else
J. Bruce Fields129a84d2007-05-10 18:38:43 -0400745 fl->fl_type = F_UNLCK;
Jeff Layton1c8c6012013-06-21 08:58:15 -0400746 spin_unlock(&inode->i_lock);
J. Bruce Fields6d34ac12007-05-11 16:09:32 -0400747 return;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700748}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700749EXPORT_SYMBOL(posix_test_lock);
750
J. Bruce Fieldsb5331842007-10-26 18:05:40 -0400751/*
752 * Deadlock detection:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700753 *
J. Bruce Fieldsb5331842007-10-26 18:05:40 -0400754 * We attempt to detect deadlocks that are due purely to posix file
755 * locks.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700756 *
J. Bruce Fieldsb5331842007-10-26 18:05:40 -0400757 * We assume that a task can be waiting for at most one lock at a time.
758 * So for any acquired lock, the process holding that lock may be
759 * waiting on at most one other lock. That lock in turns may be held by
760 * someone waiting for at most one other lock. Given a requested lock
761 * caller_fl which is about to wait for a conflicting lock block_fl, we
762 * follow this chain of waiters to ensure we are not about to create a
763 * cycle.
J. Bruce Fields97855b42007-10-30 11:20:02 -0400764 *
J. Bruce Fieldsb5331842007-10-26 18:05:40 -0400765 * Since we do this before we ever put a process to sleep on a lock, we
766 * are ensured that there is never a cycle; that is what guarantees that
767 * the while() loop in posix_locks_deadlock() eventually completes.
768 *
769 * Note: the above assumption may not be true when handling lock
770 * requests from a broken NFS client. It may also fail in the presence
771 * of tasks (such as posix threads) sharing the same open file table.
772 *
773 * To handle those cases, we just bail out after a few iterations.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700774 */
J. Bruce Fields97855b42007-10-30 11:20:02 -0400775
776#define MAX_DEADLK_ITERATIONS 10
777
J. Bruce Fieldsb5331842007-10-26 18:05:40 -0400778/* Find a lock that the owner of the given block_fl is blocking on. */
779static struct file_lock *what_owner_is_waiting_for(struct file_lock *block_fl)
780{
781 struct file_lock *fl;
782
Jeff Layton3999e492013-06-21 08:58:19 -0400783 hash_for_each_possible(blocked_hash, fl, fl_link, posix_owner_key(block_fl)) {
J. Bruce Fieldsb5331842007-10-26 18:05:40 -0400784 if (posix_same_owner(fl, block_fl))
785 return fl->fl_next;
786 }
787 return NULL;
788}
789
Jeff Layton7b2296a2013-06-21 08:58:20 -0400790/* Must be called with the blocked_lock_lock held! */
Adrian Bunkb0904e12006-06-23 02:05:13 -0700791static int posix_locks_deadlock(struct file_lock *caller_fl,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700792 struct file_lock *block_fl)
793{
J. Bruce Fields97855b42007-10-30 11:20:02 -0400794 int i = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700795
J. Bruce Fieldsb5331842007-10-26 18:05:40 -0400796 while ((block_fl = what_owner_is_waiting_for(block_fl))) {
797 if (i++ > MAX_DEADLK_ITERATIONS)
798 return 0;
799 if (posix_same_owner(caller_fl, block_fl))
800 return 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700801 }
802 return 0;
803}
804
Linus Torvalds1da177e2005-04-16 15:20:36 -0700805/* Try to create a FLOCK lock on filp. We always insert new FLOCK locks
J. Bruce Fields02888f42007-09-12 15:45:07 -0400806 * after any leases, but before any posix locks.
Trond Myklebustf475ae92006-06-29 16:38:32 -0400807 *
808 * Note that if called with an FL_EXISTS argument, the caller may determine
809 * whether or not a lock was successfully freed by testing the return
810 * value for -ENOENT.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700811 */
Trond Myklebust993dfa82006-03-31 02:30:55 -0800812static int flock_lock_file(struct file *filp, struct file_lock *request)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700813{
Trond Myklebust993dfa82006-03-31 02:30:55 -0800814 struct file_lock *new_fl = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700815 struct file_lock **before;
Al Viro496ad9a2013-01-23 17:07:38 -0500816 struct inode * inode = file_inode(filp);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700817 int error = 0;
818 int found = 0;
819
Arnd Bergmannb89f4322010-09-18 15:09:31 +0200820 if (!(request->fl_flags & FL_ACCESS) && (request->fl_type != F_UNLCK)) {
821 new_fl = locks_alloc_lock();
822 if (!new_fl)
823 return -ENOMEM;
824 }
825
Jeff Layton1c8c6012013-06-21 08:58:15 -0400826 spin_lock(&inode->i_lock);
Trond Myklebustf07f18d2006-06-29 16:38:37 -0400827 if (request->fl_flags & FL_ACCESS)
828 goto find_conflict;
Pavel Emelyanov84d535a2007-09-11 16:38:13 +0400829
Linus Torvalds1da177e2005-04-16 15:20:36 -0700830 for_each_lock(inode, before) {
831 struct file_lock *fl = *before;
832 if (IS_POSIX(fl))
833 break;
834 if (IS_LEASE(fl))
835 continue;
836 if (filp != fl->fl_file)
837 continue;
Trond Myklebust993dfa82006-03-31 02:30:55 -0800838 if (request->fl_type == fl->fl_type)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700839 goto out;
840 found = 1;
841 locks_delete_lock(before);
842 break;
843 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700844
Trond Myklebustf475ae92006-06-29 16:38:32 -0400845 if (request->fl_type == F_UNLCK) {
846 if ((request->fl_flags & FL_EXISTS) && !found)
847 error = -ENOENT;
Trond Myklebust993dfa82006-03-31 02:30:55 -0800848 goto out;
Trond Myklebustf475ae92006-06-29 16:38:32 -0400849 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700850
851 /*
852 * If a higher-priority process was blocked on the old file lock,
853 * give it the opportunity to lock the file.
854 */
Arnd Bergmannb89f4322010-09-18 15:09:31 +0200855 if (found) {
Jeff Layton1c8c6012013-06-21 08:58:15 -0400856 spin_unlock(&inode->i_lock);
Frederic Weisbeckerdef01bc2009-07-16 15:44:29 +0200857 cond_resched();
Jeff Layton1c8c6012013-06-21 08:58:15 -0400858 spin_lock(&inode->i_lock);
Arnd Bergmannb89f4322010-09-18 15:09:31 +0200859 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700860
Trond Myklebustf07f18d2006-06-29 16:38:37 -0400861find_conflict:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700862 for_each_lock(inode, before) {
863 struct file_lock *fl = *before;
864 if (IS_POSIX(fl))
865 break;
866 if (IS_LEASE(fl))
867 continue;
Trond Myklebust993dfa82006-03-31 02:30:55 -0800868 if (!flock_locks_conflict(request, fl))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700869 continue;
870 error = -EAGAIN;
Miklos Szeredibde74e42008-07-25 01:48:57 -0700871 if (!(request->fl_flags & FL_SLEEP))
872 goto out;
873 error = FILE_LOCK_DEFERRED;
874 locks_insert_block(fl, request);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700875 goto out;
876 }
Trond Myklebustf07f18d2006-06-29 16:38:37 -0400877 if (request->fl_flags & FL_ACCESS)
878 goto out;
Trond Myklebust993dfa82006-03-31 02:30:55 -0800879 locks_copy_lock(new_fl, request);
Pavel Emelyanov0e2f6db2007-09-11 15:24:01 -0700880 locks_insert_lock(before, new_fl);
Trond Myklebust993dfa82006-03-31 02:30:55 -0800881 new_fl = NULL;
Kirill Korotaev9cedc192006-06-14 17:59:35 +0400882 error = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700883
884out:
Jeff Layton1c8c6012013-06-21 08:58:15 -0400885 spin_unlock(&inode->i_lock);
Trond Myklebust993dfa82006-03-31 02:30:55 -0800886 if (new_fl)
887 locks_free_lock(new_fl);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700888 return error;
889}
890
Marc Eshel150b3932007-01-18 16:15:35 -0500891static int __posix_lock_file(struct inode *inode, struct file_lock *request, struct file_lock *conflock)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700892{
893 struct file_lock *fl;
Miklos Szeredi39005d02006-06-23 02:05:10 -0700894 struct file_lock *new_fl = NULL;
895 struct file_lock *new_fl2 = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700896 struct file_lock *left = NULL;
897 struct file_lock *right = NULL;
898 struct file_lock **before;
Jeff Laytonb9746ef2013-06-21 08:58:13 -0400899 int error;
900 bool added = false;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700901
902 /*
903 * We may need two file_lock structures for this operation,
904 * so we get them in advance to avoid races.
Miklos Szeredi39005d02006-06-23 02:05:10 -0700905 *
906 * In some cases we can be sure, that no new locks will be needed
Linus Torvalds1da177e2005-04-16 15:20:36 -0700907 */
Miklos Szeredi39005d02006-06-23 02:05:10 -0700908 if (!(request->fl_flags & FL_ACCESS) &&
909 (request->fl_type != F_UNLCK ||
910 request->fl_start != 0 || request->fl_end != OFFSET_MAX)) {
911 new_fl = locks_alloc_lock();
912 new_fl2 = locks_alloc_lock();
913 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700914
Jeff Layton1c8c6012013-06-21 08:58:15 -0400915 spin_lock(&inode->i_lock);
Jeff Layton1cb36012013-06-21 08:58:12 -0400916 /*
917 * New lock request. Walk all POSIX locks and look for conflicts. If
918 * there are any, either return error or put the request on the
Jeff Layton48f74182013-06-21 08:58:18 -0400919 * blocker's list of waiters and the global blocked_hash.
Jeff Layton1cb36012013-06-21 08:58:12 -0400920 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700921 if (request->fl_type != F_UNLCK) {
922 for_each_lock(inode, before) {
J. Bruce Fields526985b2006-11-14 16:54:36 -0500923 fl = *before;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700924 if (!IS_POSIX(fl))
925 continue;
926 if (!posix_locks_conflict(request, fl))
927 continue;
Andy Adamson5842add2006-03-26 01:37:26 -0800928 if (conflock)
J. Bruce Fields1a747ee2008-04-24 10:08:22 -0400929 __locks_copy_lock(conflock, fl);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700930 error = -EAGAIN;
931 if (!(request->fl_flags & FL_SLEEP))
932 goto out;
Jeff Layton1c8c6012013-06-21 08:58:15 -0400933 /*
934 * Deadlock detection and insertion into the blocked
935 * locks list must be done while holding the same lock!
936 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700937 error = -EDEADLK;
Jeff Layton7b2296a2013-06-21 08:58:20 -0400938 spin_lock(&blocked_lock_lock);
Jeff Layton1c8c6012013-06-21 08:58:15 -0400939 if (likely(!posix_locks_deadlock(request, fl))) {
940 error = FILE_LOCK_DEFERRED;
941 __locks_insert_block(fl, request);
942 }
Jeff Layton7b2296a2013-06-21 08:58:20 -0400943 spin_unlock(&blocked_lock_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700944 goto out;
945 }
946 }
947
948 /* If we're just looking for a conflict, we're done. */
949 error = 0;
950 if (request->fl_flags & FL_ACCESS)
951 goto out;
952
Linus Torvalds1da177e2005-04-16 15:20:36 -0700953 /*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700954 * Find the first old lock with the same owner as the new lock.
955 */
956
957 before = &inode->i_flock;
958
959 /* First skip locks owned by other processes. */
960 while ((fl = *before) && (!IS_POSIX(fl) ||
961 !posix_same_owner(request, fl))) {
962 before = &fl->fl_next;
963 }
964
Jeff Layton1cb36012013-06-21 08:58:12 -0400965 /* Process locks with this owner. */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700966 while ((fl = *before) && posix_same_owner(request, fl)) {
967 /* Detect adjacent or overlapping regions (if same lock type)
968 */
969 if (request->fl_type == fl->fl_type) {
Olaf Kirch449231d2005-08-25 16:25:35 -0700970 /* In all comparisons of start vs end, use
971 * "start - 1" rather than "end + 1". If end
972 * is OFFSET_MAX, end + 1 will become negative.
973 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700974 if (fl->fl_end < request->fl_start - 1)
975 goto next_lock;
976 /* If the next lock in the list has entirely bigger
977 * addresses than the new one, insert the lock here.
978 */
Olaf Kirch449231d2005-08-25 16:25:35 -0700979 if (fl->fl_start - 1 > request->fl_end)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700980 break;
981
982 /* If we come here, the new and old lock are of the
983 * same type and adjacent or overlapping. Make one
984 * lock yielding from the lower start address of both
985 * locks to the higher end address.
986 */
987 if (fl->fl_start > request->fl_start)
988 fl->fl_start = request->fl_start;
989 else
990 request->fl_start = fl->fl_start;
991 if (fl->fl_end < request->fl_end)
992 fl->fl_end = request->fl_end;
993 else
994 request->fl_end = fl->fl_end;
995 if (added) {
996 locks_delete_lock(before);
997 continue;
998 }
999 request = fl;
Jeff Laytonb9746ef2013-06-21 08:58:13 -04001000 added = true;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001001 }
1002 else {
1003 /* Processing for different lock types is a bit
1004 * more complex.
1005 */
1006 if (fl->fl_end < request->fl_start)
1007 goto next_lock;
1008 if (fl->fl_start > request->fl_end)
1009 break;
1010 if (request->fl_type == F_UNLCK)
Jeff Laytonb9746ef2013-06-21 08:58:13 -04001011 added = true;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001012 if (fl->fl_start < request->fl_start)
1013 left = fl;
1014 /* If the next lock in the list has a higher end
1015 * address than the new one, insert the new one here.
1016 */
1017 if (fl->fl_end > request->fl_end) {
1018 right = fl;
1019 break;
1020 }
1021 if (fl->fl_start >= request->fl_start) {
1022 /* The new lock completely replaces an old
1023 * one (This may happen several times).
1024 */
1025 if (added) {
1026 locks_delete_lock(before);
1027 continue;
1028 }
1029 /* Replace the old lock with the new one.
1030 * Wake up anybody waiting for the old one,
1031 * as the change in lock type might satisfy
1032 * their needs.
1033 */
1034 locks_wake_up_blocks(fl);
1035 fl->fl_start = request->fl_start;
1036 fl->fl_end = request->fl_end;
1037 fl->fl_type = request->fl_type;
Trond Myklebust47831f32006-03-20 13:44:05 -05001038 locks_release_private(fl);
1039 locks_copy_private(fl, request);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001040 request = fl;
Jeff Laytonb9746ef2013-06-21 08:58:13 -04001041 added = true;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001042 }
1043 }
1044 /* Go on to next lock.
1045 */
1046 next_lock:
1047 before = &fl->fl_next;
1048 }
1049
Miklos Szeredi0d9a4902006-06-23 02:05:09 -07001050 /*
Jeff Layton1cb36012013-06-21 08:58:12 -04001051 * The above code only modifies existing locks in case of merging or
1052 * replacing. If new lock(s) need to be inserted all modifications are
1053 * done below this, so it's safe yet to bail out.
Miklos Szeredi0d9a4902006-06-23 02:05:09 -07001054 */
1055 error = -ENOLCK; /* "no luck" */
1056 if (right && left == right && !new_fl2)
1057 goto out;
1058
Linus Torvalds1da177e2005-04-16 15:20:36 -07001059 error = 0;
1060 if (!added) {
Trond Myklebustf475ae92006-06-29 16:38:32 -04001061 if (request->fl_type == F_UNLCK) {
1062 if (request->fl_flags & FL_EXISTS)
1063 error = -ENOENT;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001064 goto out;
Trond Myklebustf475ae92006-06-29 16:38:32 -04001065 }
Miklos Szeredi0d9a4902006-06-23 02:05:09 -07001066
1067 if (!new_fl) {
1068 error = -ENOLCK;
1069 goto out;
1070 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001071 locks_copy_lock(new_fl, request);
1072 locks_insert_lock(before, new_fl);
1073 new_fl = NULL;
1074 }
1075 if (right) {
1076 if (left == right) {
1077 /* The new lock breaks the old one in two pieces,
1078 * so we have to use the second new lock.
1079 */
1080 left = new_fl2;
1081 new_fl2 = NULL;
1082 locks_copy_lock(left, right);
1083 locks_insert_lock(before, left);
1084 }
1085 right->fl_start = request->fl_end + 1;
1086 locks_wake_up_blocks(right);
1087 }
1088 if (left) {
1089 left->fl_end = request->fl_start - 1;
1090 locks_wake_up_blocks(left);
1091 }
1092 out:
Jeff Layton1c8c6012013-06-21 08:58:15 -04001093 spin_unlock(&inode->i_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001094 /*
1095 * Free any unused locks.
1096 */
1097 if (new_fl)
1098 locks_free_lock(new_fl);
1099 if (new_fl2)
1100 locks_free_lock(new_fl2);
1101 return error;
1102}
1103
1104/**
1105 * posix_lock_file - Apply a POSIX-style lock to a file
1106 * @filp: The file to apply the lock to
1107 * @fl: The lock to be applied
Marc Eshel150b3932007-01-18 16:15:35 -05001108 * @conflock: Place to return a copy of the conflicting lock, if found.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001109 *
1110 * Add a POSIX style lock to a file.
1111 * We merge adjacent & overlapping locks whenever possible.
1112 * POSIX locks are sorted by owner task, then by starting address
Trond Myklebustf475ae92006-06-29 16:38:32 -04001113 *
1114 * Note that if called with an FL_EXISTS argument, the caller may determine
1115 * whether or not a lock was successfully freed by testing the return
1116 * value for -ENOENT.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001117 */
Marc Eshel150b3932007-01-18 16:15:35 -05001118int posix_lock_file(struct file *filp, struct file_lock *fl,
Andy Adamson5842add2006-03-26 01:37:26 -08001119 struct file_lock *conflock)
1120{
Al Viro496ad9a2013-01-23 17:07:38 -05001121 return __posix_lock_file(file_inode(filp), fl, conflock);
Andy Adamson5842add2006-03-26 01:37:26 -08001122}
Marc Eshel150b3932007-01-18 16:15:35 -05001123EXPORT_SYMBOL(posix_lock_file);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001124
1125/**
1126 * posix_lock_file_wait - Apply a POSIX-style lock to a file
1127 * @filp: The file to apply the lock to
1128 * @fl: The lock to be applied
1129 *
1130 * Add a POSIX style lock to a file.
1131 * We merge adjacent & overlapping locks whenever possible.
1132 * POSIX locks are sorted by owner task, then by starting address
1133 */
1134int posix_lock_file_wait(struct file *filp, struct file_lock *fl)
1135{
1136 int error;
1137 might_sleep ();
1138 for (;;) {
Marc Eshel150b3932007-01-18 16:15:35 -05001139 error = posix_lock_file(filp, fl, NULL);
Miklos Szeredibde74e42008-07-25 01:48:57 -07001140 if (error != FILE_LOCK_DEFERRED)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001141 break;
1142 error = wait_event_interruptible(fl->fl_wait, !fl->fl_next);
1143 if (!error)
1144 continue;
1145
1146 locks_delete_block(fl);
1147 break;
1148 }
1149 return error;
1150}
1151EXPORT_SYMBOL(posix_lock_file_wait);
1152
1153/**
1154 * locks_mandatory_locked - Check for an active lock
1155 * @inode: the file to check
1156 *
1157 * Searches the inode's list of locks to find any POSIX locks which conflict.
1158 * This function is called from locks_verify_locked() only.
1159 */
1160int locks_mandatory_locked(struct inode *inode)
1161{
1162 fl_owner_t owner = current->files;
1163 struct file_lock *fl;
1164
1165 /*
1166 * Search the lock list for this inode for any POSIX locks.
1167 */
Jeff Layton1c8c6012013-06-21 08:58:15 -04001168 spin_lock(&inode->i_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001169 for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) {
1170 if (!IS_POSIX(fl))
1171 continue;
1172 if (fl->fl_owner != owner)
1173 break;
1174 }
Jeff Layton1c8c6012013-06-21 08:58:15 -04001175 spin_unlock(&inode->i_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001176 return fl ? -EAGAIN : 0;
1177}
1178
1179/**
1180 * locks_mandatory_area - Check for a conflicting lock
1181 * @read_write: %FLOCK_VERIFY_WRITE for exclusive access, %FLOCK_VERIFY_READ
1182 * for shared
1183 * @inode: the file to check
1184 * @filp: how the file was opened (if it was)
1185 * @offset: start of area to check
1186 * @count: length of area to check
1187 *
1188 * Searches the inode's list of locks to find any POSIX locks which conflict.
1189 * This function is called from rw_verify_area() and
1190 * locks_verify_truncate().
1191 */
1192int locks_mandatory_area(int read_write, struct inode *inode,
1193 struct file *filp, loff_t offset,
1194 size_t count)
1195{
1196 struct file_lock fl;
1197 int error;
1198
1199 locks_init_lock(&fl);
1200 fl.fl_owner = current->files;
1201 fl.fl_pid = current->tgid;
1202 fl.fl_file = filp;
1203 fl.fl_flags = FL_POSIX | FL_ACCESS;
1204 if (filp && !(filp->f_flags & O_NONBLOCK))
1205 fl.fl_flags |= FL_SLEEP;
1206 fl.fl_type = (read_write == FLOCK_VERIFY_WRITE) ? F_WRLCK : F_RDLCK;
1207 fl.fl_start = offset;
1208 fl.fl_end = offset + count - 1;
1209
1210 for (;;) {
Marc Eshel150b3932007-01-18 16:15:35 -05001211 error = __posix_lock_file(inode, &fl, NULL);
Miklos Szeredibde74e42008-07-25 01:48:57 -07001212 if (error != FILE_LOCK_DEFERRED)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001213 break;
1214 error = wait_event_interruptible(fl.fl_wait, !fl.fl_next);
1215 if (!error) {
1216 /*
1217 * If we've been sleeping someone might have
1218 * changed the permissions behind our back.
1219 */
Pavel Emelyanova16877c2007-10-01 14:41:11 -07001220 if (__mandatory_lock(inode))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001221 continue;
1222 }
1223
1224 locks_delete_block(&fl);
1225 break;
1226 }
1227
1228 return error;
1229}
1230
1231EXPORT_SYMBOL(locks_mandatory_area);
1232
J. Bruce Fields778fc542011-07-26 18:25:49 -04001233static void lease_clear_pending(struct file_lock *fl, int arg)
1234{
1235 switch (arg) {
1236 case F_UNLCK:
1237 fl->fl_flags &= ~FL_UNLOCK_PENDING;
1238 /* fall through: */
1239 case F_RDLCK:
1240 fl->fl_flags &= ~FL_DOWNGRADE_PENDING;
1241 }
1242}
1243
Linus Torvalds1da177e2005-04-16 15:20:36 -07001244/* We already had a lease on this file; just change its type */
1245int lease_modify(struct file_lock **before, int arg)
1246{
1247 struct file_lock *fl = *before;
1248 int error = assign_type(fl, arg);
1249
1250 if (error)
1251 return error;
J. Bruce Fields778fc542011-07-26 18:25:49 -04001252 lease_clear_pending(fl, arg);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001253 locks_wake_up_blocks(fl);
Filipe Brandenburger3b6e2722012-07-27 00:42:52 -04001254 if (arg == F_UNLCK) {
1255 struct file *filp = fl->fl_file;
1256
1257 f_delown(filp);
1258 filp->f_owner.signum = 0;
J. Bruce Fields96d6d592012-07-27 16:18:00 -04001259 fasync_helper(0, fl->fl_file, 0, &fl->fl_fasync);
1260 if (fl->fl_fasync != NULL) {
1261 printk(KERN_ERR "locks_delete_lock: fasync == %p\n", fl->fl_fasync);
1262 fl->fl_fasync = NULL;
1263 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001264 locks_delete_lock(before);
Filipe Brandenburger3b6e2722012-07-27 00:42:52 -04001265 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001266 return 0;
1267}
1268
1269EXPORT_SYMBOL(lease_modify);
1270
J. Bruce Fields778fc542011-07-26 18:25:49 -04001271static bool past_time(unsigned long then)
1272{
1273 if (!then)
1274 /* 0 is a special value meaning "this never expires": */
1275 return false;
1276 return time_after(jiffies, then);
1277}
1278
Linus Torvalds1da177e2005-04-16 15:20:36 -07001279static void time_out_leases(struct inode *inode)
1280{
1281 struct file_lock **before;
1282 struct file_lock *fl;
1283
1284 before = &inode->i_flock;
J. Bruce Fieldsab83fa42011-07-26 20:10:51 -04001285 while ((fl = *before) && IS_LEASE(fl) && lease_breaking(fl)) {
J. Bruce Fields778fc542011-07-26 18:25:49 -04001286 if (past_time(fl->fl_downgrade_time))
1287 lease_modify(before, F_RDLCK);
1288 if (past_time(fl->fl_break_time))
1289 lease_modify(before, F_UNLCK);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001290 if (fl == *before) /* lease_modify may have freed fl */
1291 before = &fl->fl_next;
1292 }
1293}
1294
1295/**
1296 * __break_lease - revoke all outstanding leases on file
1297 * @inode: the inode of the file to return
1298 * @mode: the open mode (read or write)
1299 *
david m. richter87250dd2007-05-09 16:10:27 -04001300 * break_lease (inlined for speed) has checked there already is at least
1301 * some kind of lock (maybe a lease) on this file. Leases are broken on
1302 * a call to open() or truncate(). This function can sleep unless you
Linus Torvalds1da177e2005-04-16 15:20:36 -07001303 * specified %O_NONBLOCK to your open().
1304 */
1305int __break_lease(struct inode *inode, unsigned int mode)
1306{
J. Bruce Fields778fc542011-07-26 18:25:49 -04001307 int error = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001308 struct file_lock *new_fl, *flock;
1309 struct file_lock *fl;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001310 unsigned long break_time;
1311 int i_have_this_lease = 0;
Al Viro8737c932009-12-24 06:47:55 -05001312 int want_write = (mode & O_ACCMODE) != O_RDONLY;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001313
Al Viro8737c932009-12-24 06:47:55 -05001314 new_fl = lease_alloc(NULL, want_write ? F_WRLCK : F_RDLCK);
Linus Torvalds6d4b9e32011-12-26 10:25:26 -08001315 if (IS_ERR(new_fl))
1316 return PTR_ERR(new_fl);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001317
Jeff Layton1c8c6012013-06-21 08:58:15 -04001318 spin_lock(&inode->i_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001319
1320 time_out_leases(inode);
1321
1322 flock = inode->i_flock;
1323 if ((flock == NULL) || !IS_LEASE(flock))
1324 goto out;
1325
J. Bruce Fields778fc542011-07-26 18:25:49 -04001326 if (!locks_conflict(flock, new_fl))
1327 goto out;
1328
Linus Torvalds1da177e2005-04-16 15:20:36 -07001329 for (fl = flock; fl && IS_LEASE(fl); fl = fl->fl_next)
1330 if (fl->fl_owner == current->files)
1331 i_have_this_lease = 1;
1332
Linus Torvalds1da177e2005-04-16 15:20:36 -07001333 break_time = 0;
1334 if (lease_break_time > 0) {
1335 break_time = jiffies + lease_break_time * HZ;
1336 if (break_time == 0)
1337 break_time++; /* so that 0 means no break time */
1338 }
1339
1340 for (fl = flock; fl && IS_LEASE(fl); fl = fl->fl_next) {
J. Bruce Fields778fc542011-07-26 18:25:49 -04001341 if (want_write) {
1342 if (fl->fl_flags & FL_UNLOCK_PENDING)
1343 continue;
1344 fl->fl_flags |= FL_UNLOCK_PENDING;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001345 fl->fl_break_time = break_time;
J. Bruce Fields778fc542011-07-26 18:25:49 -04001346 } else {
1347 if (lease_breaking(flock))
1348 continue;
1349 fl->fl_flags |= FL_DOWNGRADE_PENDING;
1350 fl->fl_downgrade_time = break_time;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001351 }
J. Bruce Fields778fc542011-07-26 18:25:49 -04001352 fl->fl_lmops->lm_break(fl);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001353 }
1354
1355 if (i_have_this_lease || (mode & O_NONBLOCK)) {
1356 error = -EWOULDBLOCK;
1357 goto out;
1358 }
1359
1360restart:
1361 break_time = flock->fl_break_time;
1362 if (break_time != 0) {
1363 break_time -= jiffies;
1364 if (break_time == 0)
1365 break_time++;
1366 }
Matthew Wilcox4321e012008-01-14 21:28:30 -07001367 locks_insert_block(flock, new_fl);
Jeff Layton1c8c6012013-06-21 08:58:15 -04001368 spin_unlock(&inode->i_lock);
Matthew Wilcox4321e012008-01-14 21:28:30 -07001369 error = wait_event_interruptible_timeout(new_fl->fl_wait,
1370 !new_fl->fl_next, break_time);
Jeff Layton1c8c6012013-06-21 08:58:15 -04001371 spin_lock(&inode->i_lock);
1372 locks_delete_block(new_fl);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001373 if (error >= 0) {
1374 if (error == 0)
1375 time_out_leases(inode);
J. Bruce Fields778fc542011-07-26 18:25:49 -04001376 /*
1377 * Wait for the next conflicting lease that has not been
1378 * broken yet
1379 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001380 for (flock = inode->i_flock; flock && IS_LEASE(flock);
1381 flock = flock->fl_next) {
J. Bruce Fields778fc542011-07-26 18:25:49 -04001382 if (locks_conflict(new_fl, flock))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001383 goto restart;
1384 }
1385 error = 0;
1386 }
1387
1388out:
Jeff Layton1c8c6012013-06-21 08:58:15 -04001389 spin_unlock(&inode->i_lock);
Linus Torvalds6d4b9e32011-12-26 10:25:26 -08001390 locks_free_lock(new_fl);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001391 return error;
1392}
1393
1394EXPORT_SYMBOL(__break_lease);
1395
1396/**
Randy Dunlapa6b91912008-03-19 17:01:00 -07001397 * lease_get_mtime - get the last modified time of an inode
Linus Torvalds1da177e2005-04-16 15:20:36 -07001398 * @inode: the inode
1399 * @time: pointer to a timespec which will contain the last modified time
1400 *
1401 * This is to force NFS clients to flush their caches for files with
1402 * exclusive leases. The justification is that if someone has an
Randy Dunlapa6b91912008-03-19 17:01:00 -07001403 * exclusive lease, then they could be modifying it.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001404 */
1405void lease_get_mtime(struct inode *inode, struct timespec *time)
1406{
1407 struct file_lock *flock = inode->i_flock;
Jeff Layton0ee5c6d2012-08-02 15:46:30 -04001408 if (flock && IS_LEASE(flock) && (flock->fl_type == F_WRLCK))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001409 *time = current_fs_time(inode->i_sb);
1410 else
1411 *time = inode->i_mtime;
1412}
1413
1414EXPORT_SYMBOL(lease_get_mtime);
1415
1416/**
1417 * fcntl_getlease - Enquire what lease is currently active
1418 * @filp: the file
1419 *
1420 * The value returned by this function will be one of
1421 * (if no lease break is pending):
1422 *
1423 * %F_RDLCK to indicate a shared lease is held.
1424 *
1425 * %F_WRLCK to indicate an exclusive lease is held.
1426 *
1427 * %F_UNLCK to indicate no lease is held.
1428 *
1429 * (if a lease break is pending):
1430 *
1431 * %F_RDLCK to indicate an exclusive lease needs to be
1432 * changed to a shared lease (or removed).
1433 *
1434 * %F_UNLCK to indicate the lease needs to be removed.
1435 *
1436 * XXX: sfr & willy disagree over whether F_INPROGRESS
1437 * should be returned to userspace.
1438 */
1439int fcntl_getlease(struct file *filp)
1440{
1441 struct file_lock *fl;
Jeff Layton1c8c6012013-06-21 08:58:15 -04001442 struct inode *inode = file_inode(filp);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001443 int type = F_UNLCK;
1444
Jeff Layton1c8c6012013-06-21 08:58:15 -04001445 spin_lock(&inode->i_lock);
Al Viro496ad9a2013-01-23 17:07:38 -05001446 time_out_leases(file_inode(filp));
1447 for (fl = file_inode(filp)->i_flock; fl && IS_LEASE(fl);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001448 fl = fl->fl_next) {
1449 if (fl->fl_file == filp) {
J. Bruce Fields778fc542011-07-26 18:25:49 -04001450 type = target_leasetype(fl);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001451 break;
1452 }
1453 }
Jeff Layton1c8c6012013-06-21 08:58:15 -04001454 spin_unlock(&inode->i_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001455 return type;
1456}
1457
Jeff Laytond4f22d12013-06-21 08:58:11 -04001458static int generic_add_lease(struct file *filp, long arg, struct file_lock **flp)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001459{
KAMBAROV, ZAUR7eaae282005-07-07 17:57:06 -07001460 struct file_lock *fl, **before, **my_before = NULL, *lease;
Josef "Jeff" Sipek0f7fc9e2006-12-08 02:36:35 -08001461 struct dentry *dentry = filp->f_path.dentry;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001462 struct inode *inode = dentry->d_inode;
J. Bruce Fieldsc1f24ef2011-08-19 10:59:49 -04001463 int error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001464
J. Bruce Fields096657b2010-10-30 17:31:14 -04001465 lease = *flp;
1466
J. Bruce Fields8335ebd2011-09-21 08:34:32 -04001467 error = -EAGAIN;
1468 if ((arg == F_RDLCK) && (atomic_read(&inode->i_writecount) > 0))
J. Bruce Fields096657b2010-10-30 17:31:14 -04001469 goto out;
J. Bruce Fields8335ebd2011-09-21 08:34:32 -04001470 if ((arg == F_WRLCK)
Al Viro84d08fa2013-07-05 18:59:33 +04001471 && ((d_count(dentry) > 1)
J. Bruce Fields8335ebd2011-09-21 08:34:32 -04001472 || (atomic_read(&inode->i_count) > 1)))
J. Bruce Fields096657b2010-10-30 17:31:14 -04001473 goto out;
Pavel Emelyanov85c59582007-09-20 12:45:02 +04001474
Linus Torvalds1da177e2005-04-16 15:20:36 -07001475 /*
1476 * At this point, we know that if there is an exclusive
1477 * lease on this file, then we hold it on this filp
1478 * (otherwise our open of this file would have blocked).
1479 * And if we are trying to acquire an exclusive lease,
1480 * then the file is not open by anyone (including us)
1481 * except for this filp.
1482 */
J. Bruce Fieldsc1f24ef2011-08-19 10:59:49 -04001483 error = -EAGAIN;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001484 for (before = &inode->i_flock;
1485 ((fl = *before) != NULL) && IS_LEASE(fl);
1486 before = &fl->fl_next) {
J. Bruce Fieldsc1f24ef2011-08-19 10:59:49 -04001487 if (fl->fl_file == filp) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001488 my_before = before;
J. Bruce Fieldsc1f24ef2011-08-19 10:59:49 -04001489 continue;
1490 }
1491 /*
1492 * No exclusive leases if someone else has a lease on
1493 * this file:
1494 */
1495 if (arg == F_WRLCK)
1496 goto out;
1497 /*
1498 * Modifying our existing lease is OK, but no getting a
1499 * new lease if someone else is opening for write:
1500 */
1501 if (fl->fl_flags & FL_UNLOCK_PENDING)
1502 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001503 }
1504
Linus Torvalds1da177e2005-04-16 15:20:36 -07001505 if (my_before != NULL) {
J. Bruce Fields8fb47a42011-07-20 20:21:59 -04001506 error = lease->fl_lmops->lm_change(my_before, arg);
Christoph Hellwig51ee4b82010-10-31 08:35:10 -04001507 if (!error)
1508 *flp = *my_before;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001509 goto out;
1510 }
1511
Linus Torvalds1da177e2005-04-16 15:20:36 -07001512 error = -EINVAL;
1513 if (!leases_enable)
1514 goto out;
1515
Arnd Bergmannc5b1f0d2010-10-27 15:46:08 +02001516 locks_insert_lock(before, lease);
Pavel Emelyanov85c59582007-09-20 12:45:02 +04001517 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001518
Linus Torvalds1da177e2005-04-16 15:20:36 -07001519out:
1520 return error;
1521}
J. Bruce Fields8335ebd2011-09-21 08:34:32 -04001522
Jeff Laytond4f22d12013-06-21 08:58:11 -04001523static int generic_delete_lease(struct file *filp, struct file_lock **flp)
J. Bruce Fields8335ebd2011-09-21 08:34:32 -04001524{
1525 struct file_lock *fl, **before;
1526 struct dentry *dentry = filp->f_path.dentry;
1527 struct inode *inode = dentry->d_inode;
1528
1529 for (before = &inode->i_flock;
1530 ((fl = *before) != NULL) && IS_LEASE(fl);
1531 before = &fl->fl_next) {
1532 if (fl->fl_file != filp)
1533 continue;
1534 return (*flp)->fl_lmops->lm_change(before, F_UNLCK);
1535 }
1536 return -EAGAIN;
1537}
1538
Linus Torvalds1da177e2005-04-16 15:20:36 -07001539/**
1540 * generic_setlease - sets a lease on an open file
1541 * @filp: file pointer
1542 * @arg: type of lease to obtain
1543 * @flp: input - file_lock to use, output - file_lock inserted
1544 *
1545 * The (input) flp->fl_lmops->lm_break function is required
1546 * by break_lease().
1547 *
Jeff Layton1c8c6012013-06-21 08:58:15 -04001548 * Called with inode->i_lock held.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001549 */
1550int generic_setlease(struct file *filp, long arg, struct file_lock **flp)
1551{
Linus Torvalds1da177e2005-04-16 15:20:36 -07001552 struct dentry *dentry = filp->f_path.dentry;
1553 struct inode *inode = dentry->d_inode;
J. Bruce Fields8335ebd2011-09-21 08:34:32 -04001554 int error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001555
Eric W. Biederman8e96e3b2012-03-03 21:17:15 -08001556 if ((!uid_eq(current_fsuid(), inode->i_uid)) && !capable(CAP_LEASE))
J. Bruce Fields8335ebd2011-09-21 08:34:32 -04001557 return -EACCES;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001558 if (!S_ISREG(inode->i_mode))
J. Bruce Fields8335ebd2011-09-21 08:34:32 -04001559 return -EINVAL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001560 error = security_file_lock(filp, arg);
1561 if (error)
J. Bruce Fields8335ebd2011-09-21 08:34:32 -04001562 return error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001563
1564 time_out_leases(inode);
1565
1566 BUG_ON(!(*flp)->fl_lmops->lm_break);
1567
J. Bruce Fields8335ebd2011-09-21 08:34:32 -04001568 switch (arg) {
1569 case F_UNLCK:
1570 return generic_delete_lease(filp, flp);
1571 case F_RDLCK:
1572 case F_WRLCK:
1573 return generic_add_lease(filp, arg, flp);
1574 default:
Dave Jones8d657eb2012-07-13 13:35:36 -04001575 return -EINVAL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001576 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001577}
Christoph Hellwig0af1a452007-07-31 00:39:22 -07001578EXPORT_SYMBOL(generic_setlease);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001579
Arnd Bergmannb89f4322010-09-18 15:09:31 +02001580static int __vfs_setlease(struct file *filp, long arg, struct file_lock **lease)
1581{
1582 if (filp->f_op && filp->f_op->setlease)
1583 return filp->f_op->setlease(filp, arg, lease);
1584 else
1585 return generic_setlease(filp, arg, lease);
1586}
1587
1588/**
J. Bruce Fieldsa9933ce2007-06-07 17:09:49 -04001589 * vfs_setlease - sets a lease on an open file
Linus Torvalds1da177e2005-04-16 15:20:36 -07001590 * @filp: file pointer
1591 * @arg: type of lease to obtain
1592 * @lease: file_lock to use
1593 *
1594 * Call this to establish a lease on the file.
J. Bruce Fields8fb47a42011-07-20 20:21:59 -04001595 * The (*lease)->fl_lmops->lm_break operation must be set; if not,
J. Bruce Fieldsf9ffed22006-11-14 15:51:40 -05001596 * break_lease will oops!
1597 *
1598 * This will call the filesystem's setlease file method, if
1599 * defined. Note that there is no getlease method; instead, the
1600 * filesystem setlease method should call back to setlease() to
1601 * add a lease to the inode's lease list, where fcntl_getlease() can
1602 * find it. Since fcntl_getlease() only reports whether the current
1603 * task holds a lease, a cluster filesystem need only do this for
1604 * leases held by processes on this node.
1605 *
1606 * There is also no break_lease method; filesystems that
Adam Buchbinderc9404c92009-12-18 15:40:42 -05001607 * handle their own leases should break leases themselves from the
J. Bruce Fieldsf9ffed22006-11-14 15:51:40 -05001608 * filesystem's open, create, and (on truncate) setattr methods.
1609 *
1610 * Warning: the only current setlease methods exist only to disable
1611 * leases in certain cases. More vfs changes may be required to
1612 * allow a full filesystem lease implementation.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001613 */
1614
J. Bruce Fieldsa9933ce2007-06-07 17:09:49 -04001615int vfs_setlease(struct file *filp, long arg, struct file_lock **lease)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001616{
Jeff Layton1c8c6012013-06-21 08:58:15 -04001617 struct inode *inode = file_inode(filp);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001618 int error;
1619
Jeff Layton1c8c6012013-06-21 08:58:15 -04001620 spin_lock(&inode->i_lock);
Arnd Bergmannb89f4322010-09-18 15:09:31 +02001621 error = __vfs_setlease(filp, arg, lease);
Jeff Layton1c8c6012013-06-21 08:58:15 -04001622 spin_unlock(&inode->i_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001623
1624 return error;
1625}
J. Bruce Fieldsa9933ce2007-06-07 17:09:49 -04001626EXPORT_SYMBOL_GPL(vfs_setlease);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001627
J. Bruce Fields0ceaf6c2010-10-30 17:31:13 -04001628static int do_fcntl_delete_lease(struct file *filp)
1629{
1630 struct file_lock fl, *flp = &fl;
1631
1632 lease_init(filp, F_UNLCK, flp);
1633
1634 return vfs_setlease(filp, F_UNLCK, &flp);
1635}
1636
1637static int do_fcntl_add_lease(unsigned int fd, struct file *filp, long arg)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001638{
J. Bruce Fields3df057a2010-11-03 16:49:44 -04001639 struct file_lock *fl, *ret;
Jeff Layton1c8c6012013-06-21 08:58:15 -04001640 struct inode *inode = file_inode(filp);
Linus Torvaldsf7347ce2010-10-27 12:38:12 -04001641 struct fasync_struct *new;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001642 int error;
1643
Arnd Bergmannc5b1f0d2010-10-27 15:46:08 +02001644 fl = lease_alloc(filp, arg);
1645 if (IS_ERR(fl))
1646 return PTR_ERR(fl);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001647
Linus Torvaldsf7347ce2010-10-27 12:38:12 -04001648 new = fasync_alloc();
1649 if (!new) {
1650 locks_free_lock(fl);
1651 return -ENOMEM;
1652 }
J. Bruce Fields3df057a2010-11-03 16:49:44 -04001653 ret = fl;
Jeff Layton1c8c6012013-06-21 08:58:15 -04001654 spin_lock(&inode->i_lock);
J. Bruce Fields8896b932010-11-03 18:09:18 -04001655 error = __vfs_setlease(filp, arg, &ret);
Christoph Hellwig51ee4b82010-10-31 08:35:10 -04001656 if (error) {
Jeff Layton1c8c6012013-06-21 08:58:15 -04001657 spin_unlock(&inode->i_lock);
Christoph Hellwig51ee4b82010-10-31 08:35:10 -04001658 locks_free_lock(fl);
1659 goto out_free_fasync;
1660 }
J. Bruce Fields3df057a2010-11-03 16:49:44 -04001661 if (ret != fl)
1662 locks_free_lock(fl);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001663
Linus Torvaldsf7347ce2010-10-27 12:38:12 -04001664 /*
1665 * fasync_insert_entry() returns the old entry if any.
1666 * If there was no old entry, then it used 'new' and
1667 * inserted it into the fasync list. Clear new so that
1668 * we don't release it here.
1669 */
J. Bruce Fields3df057a2010-11-03 16:49:44 -04001670 if (!fasync_insert_entry(fd, filp, &ret->fl_fasync, new))
Linus Torvaldsf7347ce2010-10-27 12:38:12 -04001671 new = NULL;
1672
J. Bruce Fields8896b932010-11-03 18:09:18 -04001673 error = __f_setown(filp, task_pid(current), PIDTYPE_PID, 0);
Jeff Layton1c8c6012013-06-21 08:58:15 -04001674 spin_unlock(&inode->i_lock);
Christoph Hellwig51ee4b82010-10-31 08:35:10 -04001675
1676out_free_fasync:
Linus Torvaldsf7347ce2010-10-27 12:38:12 -04001677 if (new)
1678 fasync_free(new);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001679 return error;
1680}
1681
1682/**
J. Bruce Fields0ceaf6c2010-10-30 17:31:13 -04001683 * fcntl_setlease - sets a lease on an open file
1684 * @fd: open file descriptor
1685 * @filp: file pointer
1686 * @arg: type of lease to obtain
1687 *
1688 * Call this fcntl to establish a lease on the file.
1689 * Note that you also need to call %F_SETSIG to
1690 * receive a signal when the lease is broken.
1691 */
1692int fcntl_setlease(unsigned int fd, struct file *filp, long arg)
1693{
1694 if (arg == F_UNLCK)
1695 return do_fcntl_delete_lease(filp);
1696 return do_fcntl_add_lease(fd, filp, arg);
1697}
1698
1699/**
Linus Torvalds1da177e2005-04-16 15:20:36 -07001700 * flock_lock_file_wait - Apply a FLOCK-style lock to a file
1701 * @filp: The file to apply the lock to
1702 * @fl: The lock to be applied
1703 *
1704 * Add a FLOCK style lock to a file.
1705 */
1706int flock_lock_file_wait(struct file *filp, struct file_lock *fl)
1707{
1708 int error;
1709 might_sleep();
1710 for (;;) {
1711 error = flock_lock_file(filp, fl);
Miklos Szeredibde74e42008-07-25 01:48:57 -07001712 if (error != FILE_LOCK_DEFERRED)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001713 break;
1714 error = wait_event_interruptible(fl->fl_wait, !fl->fl_next);
1715 if (!error)
1716 continue;
1717
1718 locks_delete_block(fl);
1719 break;
1720 }
1721 return error;
1722}
1723
1724EXPORT_SYMBOL(flock_lock_file_wait);
1725
1726/**
1727 * sys_flock: - flock() system call.
1728 * @fd: the file descriptor to lock.
1729 * @cmd: the type of lock to apply.
1730 *
1731 * Apply a %FL_FLOCK style lock to an open file descriptor.
1732 * The @cmd can be one of
1733 *
1734 * %LOCK_SH -- a shared lock.
1735 *
1736 * %LOCK_EX -- an exclusive lock.
1737 *
1738 * %LOCK_UN -- remove an existing lock.
1739 *
1740 * %LOCK_MAND -- a `mandatory' flock. This exists to emulate Windows Share Modes.
1741 *
1742 * %LOCK_MAND can be combined with %LOCK_READ or %LOCK_WRITE to allow other
1743 * processes read and write access respectively.
1744 */
Heiko Carstens002c8972009-01-14 14:14:18 +01001745SYSCALL_DEFINE2(flock, unsigned int, fd, unsigned int, cmd)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001746{
Al Viro2903ff02012-08-28 12:52:22 -04001747 struct fd f = fdget(fd);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001748 struct file_lock *lock;
1749 int can_sleep, unlock;
1750 int error;
1751
1752 error = -EBADF;
Al Viro2903ff02012-08-28 12:52:22 -04001753 if (!f.file)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001754 goto out;
1755
1756 can_sleep = !(cmd & LOCK_NB);
1757 cmd &= ~LOCK_NB;
1758 unlock = (cmd == LOCK_UN);
1759
Al Viroaeb5d722008-09-02 15:28:45 -04001760 if (!unlock && !(cmd & LOCK_MAND) &&
Al Viro2903ff02012-08-28 12:52:22 -04001761 !(f.file->f_mode & (FMODE_READ|FMODE_WRITE)))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001762 goto out_putf;
1763
Al Viro2903ff02012-08-28 12:52:22 -04001764 error = flock_make_lock(f.file, &lock, cmd);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001765 if (error)
1766 goto out_putf;
1767 if (can_sleep)
1768 lock->fl_flags |= FL_SLEEP;
1769
Al Viro2903ff02012-08-28 12:52:22 -04001770 error = security_file_lock(f.file, lock->fl_type);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001771 if (error)
1772 goto out_free;
1773
Al Viro2903ff02012-08-28 12:52:22 -04001774 if (f.file->f_op && f.file->f_op->flock)
1775 error = f.file->f_op->flock(f.file,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001776 (can_sleep) ? F_SETLKW : F_SETLK,
1777 lock);
1778 else
Al Viro2903ff02012-08-28 12:52:22 -04001779 error = flock_lock_file_wait(f.file, lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001780
1781 out_free:
Trond Myklebust993dfa82006-03-31 02:30:55 -08001782 locks_free_lock(lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001783
1784 out_putf:
Al Viro2903ff02012-08-28 12:52:22 -04001785 fdput(f);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001786 out:
1787 return error;
1788}
1789
J. Bruce Fields3ee17ab2007-02-21 00:58:50 -05001790/**
1791 * vfs_test_lock - test file byte range lock
1792 * @filp: The file to test lock for
J. Bruce Fields6924c552007-05-11 16:22:50 -04001793 * @fl: The lock to test; also used to hold result
J. Bruce Fields3ee17ab2007-02-21 00:58:50 -05001794 *
1795 * Returns -ERRNO on failure. Indicates presence of conflicting lock by
1796 * setting conf->fl_type to something other than F_UNLCK.
1797 */
1798int vfs_test_lock(struct file *filp, struct file_lock *fl)
1799{
1800 if (filp->f_op && filp->f_op->lock)
1801 return filp->f_op->lock(filp, F_GETLK, fl);
1802 posix_test_lock(filp, fl);
1803 return 0;
1804}
1805EXPORT_SYMBOL_GPL(vfs_test_lock);
1806
J. Bruce Fieldsc2fa1b82007-02-20 16:10:11 -05001807static int posix_lock_to_flock(struct flock *flock, struct file_lock *fl)
1808{
1809 flock->l_pid = fl->fl_pid;
1810#if BITS_PER_LONG == 32
1811 /*
1812 * Make sure we can represent the posix lock via
1813 * legacy 32bit flock.
1814 */
1815 if (fl->fl_start > OFFT_OFFSET_MAX)
1816 return -EOVERFLOW;
1817 if (fl->fl_end != OFFSET_MAX && fl->fl_end > OFFT_OFFSET_MAX)
1818 return -EOVERFLOW;
1819#endif
1820 flock->l_start = fl->fl_start;
1821 flock->l_len = fl->fl_end == OFFSET_MAX ? 0 :
1822 fl->fl_end - fl->fl_start + 1;
1823 flock->l_whence = 0;
J. Bruce Fields129a84d2007-05-10 18:38:43 -04001824 flock->l_type = fl->fl_type;
J. Bruce Fieldsc2fa1b82007-02-20 16:10:11 -05001825 return 0;
1826}
1827
1828#if BITS_PER_LONG == 32
1829static void posix_lock_to_flock64(struct flock64 *flock, struct file_lock *fl)
1830{
1831 flock->l_pid = fl->fl_pid;
1832 flock->l_start = fl->fl_start;
1833 flock->l_len = fl->fl_end == OFFSET_MAX ? 0 :
1834 fl->fl_end - fl->fl_start + 1;
1835 flock->l_whence = 0;
1836 flock->l_type = fl->fl_type;
1837}
1838#endif
1839
Linus Torvalds1da177e2005-04-16 15:20:36 -07001840/* Report the first existing lock that would conflict with l.
1841 * This implements the F_GETLK command of fcntl().
1842 */
1843int fcntl_getlk(struct file *filp, struct flock __user *l)
1844{
Marc Eshel9d6a8c52007-02-21 00:55:18 -05001845 struct file_lock file_lock;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001846 struct flock flock;
1847 int error;
1848
1849 error = -EFAULT;
1850 if (copy_from_user(&flock, l, sizeof(flock)))
1851 goto out;
1852 error = -EINVAL;
1853 if ((flock.l_type != F_RDLCK) && (flock.l_type != F_WRLCK))
1854 goto out;
1855
1856 error = flock_to_posix_lock(filp, &file_lock, &flock);
1857 if (error)
1858 goto out;
1859
J. Bruce Fields3ee17ab2007-02-21 00:58:50 -05001860 error = vfs_test_lock(filp, &file_lock);
1861 if (error)
1862 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001863
Marc Eshel9d6a8c52007-02-21 00:55:18 -05001864 flock.l_type = file_lock.fl_type;
1865 if (file_lock.fl_type != F_UNLCK) {
1866 error = posix_lock_to_flock(&flock, &file_lock);
J. Bruce Fieldsc2fa1b82007-02-20 16:10:11 -05001867 if (error)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001868 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001869 }
1870 error = -EFAULT;
1871 if (!copy_to_user(l, &flock, sizeof(flock)))
1872 error = 0;
1873out:
1874 return error;
1875}
1876
Marc Eshel7723ec92007-01-18 15:08:55 -05001877/**
1878 * vfs_lock_file - file byte range lock
1879 * @filp: The file to apply the lock to
1880 * @cmd: type of locking operation (F_SETLK, F_GETLK, etc.)
1881 * @fl: The lock to be applied
Marc Eshel150b3932007-01-18 16:15:35 -05001882 * @conf: Place to return a copy of the conflicting lock, if found.
1883 *
1884 * A caller that doesn't care about the conflicting lock may pass NULL
1885 * as the final argument.
1886 *
1887 * If the filesystem defines a private ->lock() method, then @conf will
1888 * be left unchanged; so a caller that cares should initialize it to
1889 * some acceptable default.
Marc Eshel2beb6612006-12-05 23:31:28 -05001890 *
1891 * To avoid blocking kernel daemons, such as lockd, that need to acquire POSIX
1892 * locks, the ->lock() interface may return asynchronously, before the lock has
1893 * been granted or denied by the underlying filesystem, if (and only if)
J. Bruce Fields8fb47a42011-07-20 20:21:59 -04001894 * lm_grant is set. Callers expecting ->lock() to return asynchronously
Marc Eshel2beb6612006-12-05 23:31:28 -05001895 * will only use F_SETLK, not F_SETLKW; they will set FL_SLEEP if (and only if)
1896 * the request is for a blocking lock. When ->lock() does return asynchronously,
J. Bruce Fields8fb47a42011-07-20 20:21:59 -04001897 * it must return FILE_LOCK_DEFERRED, and call ->lm_grant() when the lock
Marc Eshel2beb6612006-12-05 23:31:28 -05001898 * request completes.
1899 * If the request is for non-blocking lock the file system should return
Miklos Szeredibde74e42008-07-25 01:48:57 -07001900 * FILE_LOCK_DEFERRED then try to get the lock and call the callback routine
1901 * with the result. If the request timed out the callback routine will return a
Marc Eshel2beb6612006-12-05 23:31:28 -05001902 * nonzero return code and the file system should release the lock. The file
1903 * system is also responsible to keep a corresponding posix lock when it
1904 * grants a lock so the VFS can find out which locks are locally held and do
1905 * the correct lock cleanup when required.
1906 * The underlying filesystem must not drop the kernel lock or call
J. Bruce Fields8fb47a42011-07-20 20:21:59 -04001907 * ->lm_grant() before returning to the caller with a FILE_LOCK_DEFERRED
Marc Eshel2beb6612006-12-05 23:31:28 -05001908 * return code.
Marc Eshel7723ec92007-01-18 15:08:55 -05001909 */
Marc Eshel150b3932007-01-18 16:15:35 -05001910int vfs_lock_file(struct file *filp, unsigned int cmd, struct file_lock *fl, struct file_lock *conf)
Marc Eshel7723ec92007-01-18 15:08:55 -05001911{
1912 if (filp->f_op && filp->f_op->lock)
1913 return filp->f_op->lock(filp, cmd, fl);
1914 else
Marc Eshel150b3932007-01-18 16:15:35 -05001915 return posix_lock_file(filp, fl, conf);
Marc Eshel7723ec92007-01-18 15:08:55 -05001916}
1917EXPORT_SYMBOL_GPL(vfs_lock_file);
1918
Miklos Szeredib648a6d2008-07-25 01:48:57 -07001919static int do_lock_file_wait(struct file *filp, unsigned int cmd,
1920 struct file_lock *fl)
1921{
1922 int error;
1923
1924 error = security_file_lock(filp, fl->fl_type);
1925 if (error)
1926 return error;
1927
Miklos Szeredi764c76b2008-07-25 01:48:58 -07001928 for (;;) {
1929 error = vfs_lock_file(filp, cmd, fl, NULL);
1930 if (error != FILE_LOCK_DEFERRED)
Miklos Szeredib648a6d2008-07-25 01:48:57 -07001931 break;
Miklos Szeredi764c76b2008-07-25 01:48:58 -07001932 error = wait_event_interruptible(fl->fl_wait, !fl->fl_next);
1933 if (!error)
1934 continue;
1935
1936 locks_delete_block(fl);
1937 break;
Miklos Szeredib648a6d2008-07-25 01:48:57 -07001938 }
1939
1940 return error;
1941}
1942
Linus Torvalds1da177e2005-04-16 15:20:36 -07001943/* Apply the lock described by l to an open file descriptor.
1944 * This implements both the F_SETLK and F_SETLKW commands of fcntl().
1945 */
Peter Staubachc2936212005-07-27 11:45:09 -07001946int fcntl_setlk(unsigned int fd, struct file *filp, unsigned int cmd,
1947 struct flock __user *l)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001948{
1949 struct file_lock *file_lock = locks_alloc_lock();
1950 struct flock flock;
1951 struct inode *inode;
Al Viro0b2bac22008-05-06 13:58:34 -04001952 struct file *f;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001953 int error;
1954
1955 if (file_lock == NULL)
1956 return -ENOLCK;
1957
1958 /*
1959 * This might block, so we do it before checking the inode.
1960 */
1961 error = -EFAULT;
1962 if (copy_from_user(&flock, l, sizeof(flock)))
1963 goto out;
1964
Al Viro496ad9a2013-01-23 17:07:38 -05001965 inode = file_inode(filp);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001966
1967 /* Don't allow mandatory locks on files that may be memory mapped
1968 * and shared.
1969 */
Pavel Emelyanova16877c2007-10-01 14:41:11 -07001970 if (mandatory_lock(inode) && mapping_writably_mapped(filp->f_mapping)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001971 error = -EAGAIN;
1972 goto out;
1973 }
1974
Peter Staubachc2936212005-07-27 11:45:09 -07001975again:
Linus Torvalds1da177e2005-04-16 15:20:36 -07001976 error = flock_to_posix_lock(filp, file_lock, &flock);
1977 if (error)
1978 goto out;
1979 if (cmd == F_SETLKW) {
1980 file_lock->fl_flags |= FL_SLEEP;
1981 }
1982
1983 error = -EBADF;
1984 switch (flock.l_type) {
1985 case F_RDLCK:
1986 if (!(filp->f_mode & FMODE_READ))
1987 goto out;
1988 break;
1989 case F_WRLCK:
1990 if (!(filp->f_mode & FMODE_WRITE))
1991 goto out;
1992 break;
1993 case F_UNLCK:
1994 break;
1995 default:
1996 error = -EINVAL;
1997 goto out;
1998 }
1999
Miklos Szeredib648a6d2008-07-25 01:48:57 -07002000 error = do_lock_file_wait(filp, cmd, file_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002001
Peter Staubachc2936212005-07-27 11:45:09 -07002002 /*
2003 * Attempt to detect a close/fcntl race and recover by
2004 * releasing the lock that was just acquired.
2005 */
Al Viro0b2bac22008-05-06 13:58:34 -04002006 /*
2007 * we need that spin_lock here - it prevents reordering between
2008 * update of inode->i_flock and check for it done in close().
2009 * rcu_read_lock() wouldn't do.
2010 */
2011 spin_lock(&current->files->file_lock);
2012 f = fcheck(fd);
2013 spin_unlock(&current->files->file_lock);
2014 if (!error && f != filp && flock.l_type != F_UNLCK) {
Peter Staubachc2936212005-07-27 11:45:09 -07002015 flock.l_type = F_UNLCK;
2016 goto again;
2017 }
2018
2019out:
Linus Torvalds1da177e2005-04-16 15:20:36 -07002020 locks_free_lock(file_lock);
2021 return error;
2022}
2023
2024#if BITS_PER_LONG == 32
2025/* Report the first existing lock that would conflict with l.
2026 * This implements the F_GETLK command of fcntl().
2027 */
2028int fcntl_getlk64(struct file *filp, struct flock64 __user *l)
2029{
Marc Eshel9d6a8c52007-02-21 00:55:18 -05002030 struct file_lock file_lock;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002031 struct flock64 flock;
2032 int error;
2033
2034 error = -EFAULT;
2035 if (copy_from_user(&flock, l, sizeof(flock)))
2036 goto out;
2037 error = -EINVAL;
2038 if ((flock.l_type != F_RDLCK) && (flock.l_type != F_WRLCK))
2039 goto out;
2040
2041 error = flock64_to_posix_lock(filp, &file_lock, &flock);
2042 if (error)
2043 goto out;
2044
J. Bruce Fields3ee17ab2007-02-21 00:58:50 -05002045 error = vfs_test_lock(filp, &file_lock);
2046 if (error)
2047 goto out;
2048
Marc Eshel9d6a8c52007-02-21 00:55:18 -05002049 flock.l_type = file_lock.fl_type;
2050 if (file_lock.fl_type != F_UNLCK)
2051 posix_lock_to_flock64(&flock, &file_lock);
2052
Linus Torvalds1da177e2005-04-16 15:20:36 -07002053 error = -EFAULT;
2054 if (!copy_to_user(l, &flock, sizeof(flock)))
2055 error = 0;
2056
2057out:
2058 return error;
2059}
2060
2061/* Apply the lock described by l to an open file descriptor.
2062 * This implements both the F_SETLK and F_SETLKW commands of fcntl().
2063 */
Peter Staubachc2936212005-07-27 11:45:09 -07002064int fcntl_setlk64(unsigned int fd, struct file *filp, unsigned int cmd,
2065 struct flock64 __user *l)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002066{
2067 struct file_lock *file_lock = locks_alloc_lock();
2068 struct flock64 flock;
2069 struct inode *inode;
Al Viro0b2bac22008-05-06 13:58:34 -04002070 struct file *f;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002071 int error;
2072
2073 if (file_lock == NULL)
2074 return -ENOLCK;
2075
2076 /*
2077 * This might block, so we do it before checking the inode.
2078 */
2079 error = -EFAULT;
2080 if (copy_from_user(&flock, l, sizeof(flock)))
2081 goto out;
2082
Al Viro496ad9a2013-01-23 17:07:38 -05002083 inode = file_inode(filp);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002084
2085 /* Don't allow mandatory locks on files that may be memory mapped
2086 * and shared.
2087 */
Pavel Emelyanova16877c2007-10-01 14:41:11 -07002088 if (mandatory_lock(inode) && mapping_writably_mapped(filp->f_mapping)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002089 error = -EAGAIN;
2090 goto out;
2091 }
2092
Peter Staubachc2936212005-07-27 11:45:09 -07002093again:
Linus Torvalds1da177e2005-04-16 15:20:36 -07002094 error = flock64_to_posix_lock(filp, file_lock, &flock);
2095 if (error)
2096 goto out;
2097 if (cmd == F_SETLKW64) {
2098 file_lock->fl_flags |= FL_SLEEP;
2099 }
2100
2101 error = -EBADF;
2102 switch (flock.l_type) {
2103 case F_RDLCK:
2104 if (!(filp->f_mode & FMODE_READ))
2105 goto out;
2106 break;
2107 case F_WRLCK:
2108 if (!(filp->f_mode & FMODE_WRITE))
2109 goto out;
2110 break;
2111 case F_UNLCK:
2112 break;
2113 default:
2114 error = -EINVAL;
2115 goto out;
2116 }
2117
Miklos Szeredib648a6d2008-07-25 01:48:57 -07002118 error = do_lock_file_wait(filp, cmd, file_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002119
Peter Staubachc2936212005-07-27 11:45:09 -07002120 /*
2121 * Attempt to detect a close/fcntl race and recover by
2122 * releasing the lock that was just acquired.
2123 */
Al Viro0b2bac22008-05-06 13:58:34 -04002124 spin_lock(&current->files->file_lock);
2125 f = fcheck(fd);
2126 spin_unlock(&current->files->file_lock);
2127 if (!error && f != filp && flock.l_type != F_UNLCK) {
Peter Staubachc2936212005-07-27 11:45:09 -07002128 flock.l_type = F_UNLCK;
2129 goto again;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002130 }
2131
2132out:
2133 locks_free_lock(file_lock);
2134 return error;
2135}
2136#endif /* BITS_PER_LONG == 32 */
2137
2138/*
2139 * This function is called when the file is being removed
2140 * from the task's fd array. POSIX locks belonging to this task
2141 * are deleted at this time.
2142 */
2143void locks_remove_posix(struct file *filp, fl_owner_t owner)
2144{
Miklos Szerediff7b86b2006-06-23 02:05:11 -07002145 struct file_lock lock;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002146
2147 /*
2148 * If there are no locks held on this file, we don't need to call
2149 * posix_lock_file(). Another process could be setting a lock on this
2150 * file at the same time, but we wouldn't remove that lock anyway.
2151 */
Al Viro496ad9a2013-01-23 17:07:38 -05002152 if (!file_inode(filp)->i_flock)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002153 return;
2154
2155 lock.fl_type = F_UNLCK;
Miklos Szeredi75e1fcc2006-06-23 02:05:12 -07002156 lock.fl_flags = FL_POSIX | FL_CLOSE;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002157 lock.fl_start = 0;
2158 lock.fl_end = OFFSET_MAX;
2159 lock.fl_owner = owner;
2160 lock.fl_pid = current->tgid;
2161 lock.fl_file = filp;
2162 lock.fl_ops = NULL;
2163 lock.fl_lmops = NULL;
2164
Marc Eshel150b3932007-01-18 16:15:35 -05002165 vfs_lock_file(filp, F_SETLK, &lock, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002166
Linus Torvalds1da177e2005-04-16 15:20:36 -07002167 if (lock.fl_ops && lock.fl_ops->fl_release_private)
2168 lock.fl_ops->fl_release_private(&lock);
2169}
2170
2171EXPORT_SYMBOL(locks_remove_posix);
2172
2173/*
2174 * This function is called on the last close of an open file.
2175 */
2176void locks_remove_flock(struct file *filp)
2177{
Al Viro496ad9a2013-01-23 17:07:38 -05002178 struct inode * inode = file_inode(filp);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002179 struct file_lock *fl;
2180 struct file_lock **before;
2181
2182 if (!inode->i_flock)
2183 return;
2184
2185 if (filp->f_op && filp->f_op->flock) {
2186 struct file_lock fl = {
2187 .fl_pid = current->tgid,
2188 .fl_file = filp,
2189 .fl_flags = FL_FLOCK,
2190 .fl_type = F_UNLCK,
2191 .fl_end = OFFSET_MAX,
2192 };
2193 filp->f_op->flock(filp, F_SETLKW, &fl);
Trond Myklebust80fec4c2005-06-22 17:16:31 +00002194 if (fl.fl_ops && fl.fl_ops->fl_release_private)
2195 fl.fl_ops->fl_release_private(&fl);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002196 }
2197
Jeff Layton1c8c6012013-06-21 08:58:15 -04002198 spin_lock(&inode->i_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002199 before = &inode->i_flock;
2200
2201 while ((fl = *before) != NULL) {
2202 if (fl->fl_file == filp) {
Peter Staubachc2936212005-07-27 11:45:09 -07002203 if (IS_FLOCK(fl)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002204 locks_delete_lock(before);
2205 continue;
2206 }
2207 if (IS_LEASE(fl)) {
2208 lease_modify(before, F_UNLCK);
2209 continue;
2210 }
2211 /* What? */
2212 BUG();
2213 }
2214 before = &fl->fl_next;
2215 }
Jeff Layton1c8c6012013-06-21 08:58:15 -04002216 spin_unlock(&inode->i_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002217}
2218
2219/**
Linus Torvalds1da177e2005-04-16 15:20:36 -07002220 * posix_unblock_lock - stop waiting for a file lock
Linus Torvalds1da177e2005-04-16 15:20:36 -07002221 * @waiter: the lock which was waiting
2222 *
2223 * lockd needs to block waiting for locks.
2224 */
J. Bruce Fields64a318e2006-01-03 09:55:46 +01002225int
Jeff Laytonf891a292013-06-21 08:58:09 -04002226posix_unblock_lock(struct file_lock *waiter)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002227{
J. Bruce Fields64a318e2006-01-03 09:55:46 +01002228 int status = 0;
2229
Jeff Layton7b2296a2013-06-21 08:58:20 -04002230 spin_lock(&blocked_lock_lock);
J. Bruce Fields5996a292006-01-03 09:55:44 +01002231 if (waiter->fl_next)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002232 __locks_delete_block(waiter);
J. Bruce Fields64a318e2006-01-03 09:55:46 +01002233 else
2234 status = -ENOENT;
Jeff Layton7b2296a2013-06-21 08:58:20 -04002235 spin_unlock(&blocked_lock_lock);
J. Bruce Fields64a318e2006-01-03 09:55:46 +01002236 return status;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002237}
Linus Torvalds1da177e2005-04-16 15:20:36 -07002238EXPORT_SYMBOL(posix_unblock_lock);
2239
Marc Eshel9b9d2ab2007-01-18 17:52:58 -05002240/**
2241 * vfs_cancel_lock - file byte range unblock lock
2242 * @filp: The file to apply the unblock to
2243 * @fl: The lock to be unblocked
2244 *
2245 * Used by lock managers to cancel blocked requests
2246 */
2247int vfs_cancel_lock(struct file *filp, struct file_lock *fl)
2248{
2249 if (filp->f_op && filp->f_op->lock)
2250 return filp->f_op->lock(filp, F_CANCELLK, fl);
2251 return 0;
2252}
2253
2254EXPORT_SYMBOL_GPL(vfs_cancel_lock);
2255
Pavel Emelyanov7f8ada92007-10-01 14:41:15 -07002256#ifdef CONFIG_PROC_FS
Alexey Dobriyand8ba7a32008-10-04 22:34:18 +04002257#include <linux/proc_fs.h>
Pavel Emelyanov7f8ada92007-10-01 14:41:15 -07002258#include <linux/seq_file.h>
2259
Jeff Layton7012b022013-06-21 08:58:22 -04002260struct locks_iterator {
2261 int li_cpu;
2262 loff_t li_pos;
2263};
2264
Pavel Emelyanov7f8ada92007-10-01 14:41:15 -07002265static void lock_get_status(struct seq_file *f, struct file_lock *fl,
Jerome Marchand99dc8292010-10-26 14:22:33 -07002266 loff_t id, char *pfx)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002267{
2268 struct inode *inode = NULL;
Vitaliy Gusevab1f1612008-01-17 00:07:08 +00002269 unsigned int fl_pid;
2270
2271 if (fl->fl_nspid)
Pavel Emelyanov6c5f3e72008-02-08 04:19:20 -08002272 fl_pid = pid_vnr(fl->fl_nspid);
Vitaliy Gusevab1f1612008-01-17 00:07:08 +00002273 else
2274 fl_pid = fl->fl_pid;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002275
2276 if (fl->fl_file != NULL)
Al Viro496ad9a2013-01-23 17:07:38 -05002277 inode = file_inode(fl->fl_file);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002278
Jerome Marchand99dc8292010-10-26 14:22:33 -07002279 seq_printf(f, "%lld:%s ", id, pfx);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002280 if (IS_POSIX(fl)) {
Pavel Emelyanov7f8ada92007-10-01 14:41:15 -07002281 seq_printf(f, "%6s %s ",
Linus Torvalds1da177e2005-04-16 15:20:36 -07002282 (fl->fl_flags & FL_ACCESS) ? "ACCESS" : "POSIX ",
2283 (inode == NULL) ? "*NOINODE*" :
Pavel Emelyanova16877c2007-10-01 14:41:11 -07002284 mandatory_lock(inode) ? "MANDATORY" : "ADVISORY ");
Linus Torvalds1da177e2005-04-16 15:20:36 -07002285 } else if (IS_FLOCK(fl)) {
2286 if (fl->fl_type & LOCK_MAND) {
Pavel Emelyanov7f8ada92007-10-01 14:41:15 -07002287 seq_printf(f, "FLOCK MSNFS ");
Linus Torvalds1da177e2005-04-16 15:20:36 -07002288 } else {
Pavel Emelyanov7f8ada92007-10-01 14:41:15 -07002289 seq_printf(f, "FLOCK ADVISORY ");
Linus Torvalds1da177e2005-04-16 15:20:36 -07002290 }
2291 } else if (IS_LEASE(fl)) {
Pavel Emelyanov7f8ada92007-10-01 14:41:15 -07002292 seq_printf(f, "LEASE ");
J. Bruce Fieldsab83fa42011-07-26 20:10:51 -04002293 if (lease_breaking(fl))
Pavel Emelyanov7f8ada92007-10-01 14:41:15 -07002294 seq_printf(f, "BREAKING ");
Linus Torvalds1da177e2005-04-16 15:20:36 -07002295 else if (fl->fl_file)
Pavel Emelyanov7f8ada92007-10-01 14:41:15 -07002296 seq_printf(f, "ACTIVE ");
Linus Torvalds1da177e2005-04-16 15:20:36 -07002297 else
Pavel Emelyanov7f8ada92007-10-01 14:41:15 -07002298 seq_printf(f, "BREAKER ");
Linus Torvalds1da177e2005-04-16 15:20:36 -07002299 } else {
Pavel Emelyanov7f8ada92007-10-01 14:41:15 -07002300 seq_printf(f, "UNKNOWN UNKNOWN ");
Linus Torvalds1da177e2005-04-16 15:20:36 -07002301 }
2302 if (fl->fl_type & LOCK_MAND) {
Pavel Emelyanov7f8ada92007-10-01 14:41:15 -07002303 seq_printf(f, "%s ",
Linus Torvalds1da177e2005-04-16 15:20:36 -07002304 (fl->fl_type & LOCK_READ)
2305 ? (fl->fl_type & LOCK_WRITE) ? "RW " : "READ "
2306 : (fl->fl_type & LOCK_WRITE) ? "WRITE" : "NONE ");
2307 } else {
Pavel Emelyanov7f8ada92007-10-01 14:41:15 -07002308 seq_printf(f, "%s ",
J. Bruce Fieldsab83fa42011-07-26 20:10:51 -04002309 (lease_breaking(fl))
Jeff Layton0ee5c6d2012-08-02 15:46:30 -04002310 ? (fl->fl_type == F_UNLCK) ? "UNLCK" : "READ "
2311 : (fl->fl_type == F_WRLCK) ? "WRITE" : "READ ");
Linus Torvalds1da177e2005-04-16 15:20:36 -07002312 }
2313 if (inode) {
2314#ifdef WE_CAN_BREAK_LSLK_NOW
Vitaliy Gusevab1f1612008-01-17 00:07:08 +00002315 seq_printf(f, "%d %s:%ld ", fl_pid,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002316 inode->i_sb->s_id, inode->i_ino);
2317#else
2318 /* userspace relies on this representation of dev_t ;-( */
Vitaliy Gusevab1f1612008-01-17 00:07:08 +00002319 seq_printf(f, "%d %02x:%02x:%ld ", fl_pid,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002320 MAJOR(inode->i_sb->s_dev),
2321 MINOR(inode->i_sb->s_dev), inode->i_ino);
2322#endif
2323 } else {
Vitaliy Gusevab1f1612008-01-17 00:07:08 +00002324 seq_printf(f, "%d <none>:0 ", fl_pid);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002325 }
2326 if (IS_POSIX(fl)) {
2327 if (fl->fl_end == OFFSET_MAX)
Pavel Emelyanov7f8ada92007-10-01 14:41:15 -07002328 seq_printf(f, "%Ld EOF\n", fl->fl_start);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002329 else
Pavel Emelyanov7f8ada92007-10-01 14:41:15 -07002330 seq_printf(f, "%Ld %Ld\n", fl->fl_start, fl->fl_end);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002331 } else {
Pavel Emelyanov7f8ada92007-10-01 14:41:15 -07002332 seq_printf(f, "0 EOF\n");
Linus Torvalds1da177e2005-04-16 15:20:36 -07002333 }
2334}
2335
Pavel Emelyanov7f8ada92007-10-01 14:41:15 -07002336static int locks_show(struct seq_file *f, void *v)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002337{
Jeff Layton7012b022013-06-21 08:58:22 -04002338 struct locks_iterator *iter = f->private;
Pavel Emelyanov7f8ada92007-10-01 14:41:15 -07002339 struct file_lock *fl, *bfl;
2340
Jeff Layton139ca042013-06-21 08:58:17 -04002341 fl = hlist_entry(v, struct file_lock, fl_link);
Pavel Emelyanov7f8ada92007-10-01 14:41:15 -07002342
Jeff Layton7012b022013-06-21 08:58:22 -04002343 lock_get_status(f, fl, iter->li_pos, "");
Pavel Emelyanov7f8ada92007-10-01 14:41:15 -07002344
2345 list_for_each_entry(bfl, &fl->fl_block, fl_block)
Jeff Layton7012b022013-06-21 08:58:22 -04002346 lock_get_status(f, bfl, iter->li_pos, " ->");
Pavel Emelyanov7f8ada92007-10-01 14:41:15 -07002347
Pavel Emelyanov7f8ada92007-10-01 14:41:15 -07002348 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002349}
2350
Pavel Emelyanov7f8ada92007-10-01 14:41:15 -07002351static void *locks_start(struct seq_file *f, loff_t *pos)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002352{
Jeff Layton7012b022013-06-21 08:58:22 -04002353 struct locks_iterator *iter = f->private;
Jerome Marchand99dc8292010-10-26 14:22:33 -07002354
Jeff Layton7012b022013-06-21 08:58:22 -04002355 iter->li_pos = *pos + 1;
2356 lg_global_lock(&file_lock_lglock);
Jeff Layton7b2296a2013-06-21 08:58:20 -04002357 spin_lock(&blocked_lock_lock);
Jeff Layton7012b022013-06-21 08:58:22 -04002358 return seq_hlist_start_percpu(&file_lock_list, &iter->li_cpu, *pos);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002359}
2360
Pavel Emelyanov7f8ada92007-10-01 14:41:15 -07002361static void *locks_next(struct seq_file *f, void *v, loff_t *pos)
2362{
Jeff Layton7012b022013-06-21 08:58:22 -04002363 struct locks_iterator *iter = f->private;
2364
2365 ++iter->li_pos;
2366 return seq_hlist_next_percpu(v, &file_lock_list, &iter->li_cpu, pos);
Pavel Emelyanov7f8ada92007-10-01 14:41:15 -07002367}
2368
2369static void locks_stop(struct seq_file *f, void *v)
2370{
Jeff Layton7b2296a2013-06-21 08:58:20 -04002371 spin_unlock(&blocked_lock_lock);
Jeff Layton7012b022013-06-21 08:58:22 -04002372 lg_global_unlock(&file_lock_lglock);
Pavel Emelyanov7f8ada92007-10-01 14:41:15 -07002373}
2374
Alexey Dobriyand8ba7a32008-10-04 22:34:18 +04002375static const struct seq_operations locks_seq_operations = {
Pavel Emelyanov7f8ada92007-10-01 14:41:15 -07002376 .start = locks_start,
2377 .next = locks_next,
2378 .stop = locks_stop,
2379 .show = locks_show,
2380};
Alexey Dobriyand8ba7a32008-10-04 22:34:18 +04002381
2382static int locks_open(struct inode *inode, struct file *filp)
2383{
Jeff Layton7012b022013-06-21 08:58:22 -04002384 return seq_open_private(filp, &locks_seq_operations,
2385 sizeof(struct locks_iterator));
Alexey Dobriyand8ba7a32008-10-04 22:34:18 +04002386}
2387
2388static const struct file_operations proc_locks_operations = {
2389 .open = locks_open,
2390 .read = seq_read,
2391 .llseek = seq_lseek,
Jerome Marchand99dc8292010-10-26 14:22:33 -07002392 .release = seq_release_private,
Alexey Dobriyand8ba7a32008-10-04 22:34:18 +04002393};
2394
2395static int __init proc_locks_init(void)
2396{
2397 proc_create("locks", 0, NULL, &proc_locks_operations);
2398 return 0;
2399}
2400module_init(proc_locks_init);
Pavel Emelyanov7f8ada92007-10-01 14:41:15 -07002401#endif
2402
Linus Torvalds1da177e2005-04-16 15:20:36 -07002403/**
2404 * lock_may_read - checks that the region is free of locks
2405 * @inode: the inode that is being read
2406 * @start: the first byte to read
2407 * @len: the number of bytes to read
2408 *
2409 * Emulates Windows locking requirements. Whole-file
2410 * mandatory locks (share modes) can prohibit a read and
2411 * byte-range POSIX locks can prohibit a read if they overlap.
2412 *
2413 * N.B. this function is only ever called
2414 * from knfsd and ownership of locks is never checked.
2415 */
2416int lock_may_read(struct inode *inode, loff_t start, unsigned long len)
2417{
2418 struct file_lock *fl;
2419 int result = 1;
Jeff Layton1c8c6012013-06-21 08:58:15 -04002420
2421 spin_lock(&inode->i_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002422 for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) {
2423 if (IS_POSIX(fl)) {
2424 if (fl->fl_type == F_RDLCK)
2425 continue;
2426 if ((fl->fl_end < start) || (fl->fl_start > (start + len)))
2427 continue;
2428 } else if (IS_FLOCK(fl)) {
2429 if (!(fl->fl_type & LOCK_MAND))
2430 continue;
2431 if (fl->fl_type & LOCK_READ)
2432 continue;
2433 } else
2434 continue;
2435 result = 0;
2436 break;
2437 }
Jeff Layton1c8c6012013-06-21 08:58:15 -04002438 spin_unlock(&inode->i_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002439 return result;
2440}
2441
2442EXPORT_SYMBOL(lock_may_read);
2443
2444/**
2445 * lock_may_write - checks that the region is free of locks
2446 * @inode: the inode that is being written
2447 * @start: the first byte to write
2448 * @len: the number of bytes to write
2449 *
2450 * Emulates Windows locking requirements. Whole-file
2451 * mandatory locks (share modes) can prohibit a write and
2452 * byte-range POSIX locks can prohibit a write if they overlap.
2453 *
2454 * N.B. this function is only ever called
2455 * from knfsd and ownership of locks is never checked.
2456 */
2457int lock_may_write(struct inode *inode, loff_t start, unsigned long len)
2458{
2459 struct file_lock *fl;
2460 int result = 1;
Jeff Layton1c8c6012013-06-21 08:58:15 -04002461
2462 spin_lock(&inode->i_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002463 for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) {
2464 if (IS_POSIX(fl)) {
2465 if ((fl->fl_end < start) || (fl->fl_start > (start + len)))
2466 continue;
2467 } else if (IS_FLOCK(fl)) {
2468 if (!(fl->fl_type & LOCK_MAND))
2469 continue;
2470 if (fl->fl_type & LOCK_WRITE)
2471 continue;
2472 } else
2473 continue;
2474 result = 0;
2475 break;
2476 }
Jeff Layton1c8c6012013-06-21 08:58:15 -04002477 spin_unlock(&inode->i_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002478 return result;
2479}
2480
2481EXPORT_SYMBOL(lock_may_write);
2482
Linus Torvalds1da177e2005-04-16 15:20:36 -07002483static int __init filelock_init(void)
2484{
Jeff Layton7012b022013-06-21 08:58:22 -04002485 int i;
2486
Linus Torvalds1da177e2005-04-16 15:20:36 -07002487 filelock_cache = kmem_cache_create("file_lock_cache",
Miklos Szerediee19cc42011-07-07 13:06:09 +02002488 sizeof(struct file_lock), 0, SLAB_PANIC, NULL);
2489
Jeff Layton7012b022013-06-21 08:58:22 -04002490 lg_lock_init(&file_lock_lglock, "file_lock_lglock");
2491
2492 for_each_possible_cpu(i)
2493 INIT_HLIST_HEAD(per_cpu_ptr(&file_lock_list, i));
2494
Linus Torvalds1da177e2005-04-16 15:20:36 -07002495 return 0;
2496}
2497
2498core_initcall(filelock_init);