/fs/locks.c

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   1/*
   2 *  linux/fs/locks.c
   3 *
   4 *  Provide support for fcntl()'s F_GETLK, F_SETLK, and F_SETLKW calls.
   5 *  Doug Evans (dje@spiff.uucp), August 07, 1992
   6 *
   7 *  Deadlock detection added.
   8 *  FIXME: one thing isn't handled yet:
   9 *	- mandatory locks (requires lots of changes elsewhere)
  10 *  Kelly Carmichael (kelly@[142.24.8.65]), September 17, 1994.
  11 *
  12 *  Miscellaneous edits, and a total rewrite of posix_lock_file() code.
  13 *  Kai Petzke (wpp@marie.physik.tu-berlin.de), 1994
  14 *  
  15 *  Converted file_lock_table to a linked list from an array, which eliminates
  16 *  the limits on how many active file locks are open.
  17 *  Chad Page (pageone@netcom.com), November 27, 1994
  18 * 
  19 *  Removed dependency on file descriptors. dup()'ed file descriptors now
  20 *  get the same locks as the original file descriptors, and a close() on
  21 *  any file descriptor removes ALL the locks on the file for the current
  22 *  process. Since locks still depend on the process id, locks are inherited
  23 *  after an exec() but not after a fork(). This agrees with POSIX, and both
  24 *  BSD and SVR4 practice.
  25 *  Andy Walker (andy@lysaker.kvaerner.no), February 14, 1995
  26 *
  27 *  Scrapped free list which is redundant now that we allocate locks
  28 *  dynamically with kmalloc()/kfree().
  29 *  Andy Walker (andy@lysaker.kvaerner.no), February 21, 1995
  30 *
  31 *  Implemented two lock personalities - FL_FLOCK and FL_POSIX.
  32 *
  33 *  FL_POSIX locks are created with calls to fcntl() and lockf() through the
  34 *  fcntl() system call. They have the semantics described above.
  35 *
  36 *  FL_FLOCK locks are created with calls to flock(), through the flock()
  37 *  system call, which is new. Old C libraries implement flock() via fcntl()
  38 *  and will continue to use the old, broken implementation.
  39 *
  40 *  FL_FLOCK locks follow the 4.4 BSD flock() semantics. They are associated
  41 *  with a file pointer (filp). As a result they can be shared by a parent
  42 *  process and its children after a fork(). They are removed when the last
  43 *  file descriptor referring to the file pointer is closed (unless explicitly
  44 *  unlocked). 
  45 *
  46 *  FL_FLOCK locks never deadlock, an existing lock is always removed before
  47 *  upgrading from shared to exclusive (or vice versa). When this happens
  48 *  any processes blocked by the current lock are woken up and allowed to
  49 *  run before the new lock is applied.
  50 *  Andy Walker (andy@lysaker.kvaerner.no), June 09, 1995
  51 *
  52 *  Removed some race conditions in flock_lock_file(), marked other possible
  53 *  races. Just grep for FIXME to see them. 
  54 *  Dmitry Gorodchanin (pgmdsg@ibi.com), February 09, 1996.
  55 *
  56 *  Addressed Dmitry's concerns. Deadlock checking no longer recursive.
  57 *  Lock allocation changed to GFP_ATOMIC as we can't afford to sleep
  58 *  once we've checked for blocking and deadlocking.
  59 *  Andy Walker (andy@lysaker.kvaerner.no), April 03, 1996.
  60 *
  61 *  Initial implementation of mandatory locks. SunOS turned out to be
  62 *  a rotten model, so I implemented the "obvious" semantics.
  63 *  See 'Documentation/mandatory.txt' for details.
  64 *  Andy Walker (andy@lysaker.kvaerner.no), April 06, 1996.
  65 *
  66 *  Don't allow mandatory locks on mmap()'ed files. Added simple functions to
  67 *  check if a file has mandatory locks, used by mmap(), open() and creat() to
  68 *  see if system call should be rejected. Ref. HP-UX/SunOS/Solaris Reference
  69 *  Manual, Section 2.
  70 *  Andy Walker (andy@lysaker.kvaerner.no), April 09, 1996.
  71 *
  72 *  Tidied up block list handling. Added '/proc/locks' interface.
  73 *  Andy Walker (andy@lysaker.kvaerner.no), April 24, 1996.
  74 *
  75 *  Fixed deadlock condition for pathological code that mixes calls to
  76 *  flock() and fcntl().
  77 *  Andy Walker (andy@lysaker.kvaerner.no), April 29, 1996.
  78 *
  79 *  Allow only one type of locking scheme (FL_POSIX or FL_FLOCK) to be in use
  80 *  for a given file at a time. Changed the CONFIG_LOCK_MANDATORY scheme to
  81 *  guarantee sensible behaviour in the case where file system modules might
  82 *  be compiled with different options than the kernel itself.
  83 *  Andy Walker (andy@lysaker.kvaerner.no), May 15, 1996.
  84 *
  85 *  Added a couple of missing wake_up() calls. Thanks to Thomas Meckel
  86 *  (Thomas.Meckel@mni.fh-giessen.de) for spotting this.
  87 *  Andy Walker (andy@lysaker.kvaerner.no), May 15, 1996.
  88 *
  89 *  Changed FL_POSIX locks to use the block list in the same way as FL_FLOCK
  90 *  locks. Changed process synchronisation to avoid dereferencing locks that
  91 *  have already been freed.
  92 *  Andy Walker (andy@lysaker.kvaerner.no), Sep 21, 1996.
  93 *
  94 *  Made the block list a circular list to minimise searching in the list.
  95 *  Andy Walker (andy@lysaker.kvaerner.no), Sep 25, 1996.
  96 *
  97 *  Made mandatory locking a mount option. Default is not to allow mandatory
  98 *  locking.
  99 *  Andy Walker (andy@lysaker.kvaerner.no), Oct 04, 1996.
 100 *
 101 *  Some adaptations for NFS support.
 102 *  Olaf Kirch (okir@monad.swb.de), Dec 1996,
 103 *
 104 *  Fixed /proc/locks interface so that we can't overrun the buffer we are handed.
 105 *  Andy Walker (andy@lysaker.kvaerner.no), May 12, 1997.
 106 *
 107 *  Use slab allocator instead of kmalloc/kfree.
 108 *  Use generic list implementation from <linux/list.h>.
 109 *  Sped up posix_locks_deadlock by only considering blocked locks.
 110 *  Matthew Wilcox <willy@debian.org>, March, 2000.
 111 *
 112 *  Leases and LOCK_MAND
 113 *  Matthew Wilcox <willy@debian.org>, June, 2000.
 114 *  Stephen Rothwell <sfr@canb.auug.org.au>, June, 2000.
 115 */
 116
 117#include <linux/capability.h>
 118#include <linux/file.h>
 119#include <linux/fs.h>
 120#include <linux/init.h>
 121#include <linux/module.h>
 122#include <linux/security.h>
 123#include <linux/slab.h>
 124#include <linux/smp_lock.h>
 125#include <linux/syscalls.h>
 126#include <linux/time.h>
 127
 128#include <asm/semaphore.h>
 129#include <asm/uaccess.h>
 130
 131#define IS_POSIX(fl)	(fl->fl_flags & FL_POSIX)
 132#define IS_FLOCK(fl)	(fl->fl_flags & FL_FLOCK)
 133#define IS_LEASE(fl)	(fl->fl_flags & FL_LEASE)
 134
 135int leases_enable = 1;
 136int lease_break_time = 45;
 137
 138#define for_each_lock(inode, lockp) \
 139	for (lockp = &inode->i_flock; *lockp != NULL; lockp = &(*lockp)->fl_next)
 140
 141LIST_HEAD(file_lock_list);
 142
 143EXPORT_SYMBOL(file_lock_list);
 144
 145static LIST_HEAD(blocked_list);
 146
 147static kmem_cache_t *filelock_cache;
 148
 149/* Allocate an empty lock structure. */
 150static struct file_lock *locks_alloc_lock(void)
 151{
 152	return kmem_cache_alloc(filelock_cache, SLAB_KERNEL);
 153}
 154
 155/* Free a lock which is not in use. */
 156static inline void locks_free_lock(struct file_lock *fl)
 157{
 158	if (fl == NULL) {
 159		BUG();
 160		return;
 161	}
 162	if (waitqueue_active(&fl->fl_wait))
 163		panic("Attempting to free lock with active wait queue");
 164
 165	if (!list_empty(&fl->fl_block))
 166		panic("Attempting to free lock with active block list");
 167
 168	if (!list_empty(&fl->fl_link))
 169		panic("Attempting to free lock on active lock list");
 170
 171	if (fl->fl_ops) {
 172		if (fl->fl_ops->fl_release_private)
 173			fl->fl_ops->fl_release_private(fl);
 174		fl->fl_ops = NULL;
 175	}
 176
 177	if (fl->fl_lmops) {
 178		if (fl->fl_lmops->fl_release_private)
 179			fl->fl_lmops->fl_release_private(fl);
 180		fl->fl_lmops = NULL;
 181	}
 182
 183	kmem_cache_free(filelock_cache, fl);
 184}
 185
 186void locks_init_lock(struct file_lock *fl)
 187{
 188	INIT_LIST_HEAD(&fl->fl_link);
 189	INIT_LIST_HEAD(&fl->fl_block);
 190	init_waitqueue_head(&fl->fl_wait);
 191	fl->fl_next = NULL;
 192	fl->fl_fasync = NULL;
 193	fl->fl_owner = NULL;
 194	fl->fl_pid = 0;
 195	fl->fl_file = NULL;
 196	fl->fl_flags = 0;
 197	fl->fl_type = 0;
 198	fl->fl_start = fl->fl_end = 0;
 199	fl->fl_ops = NULL;
 200	fl->fl_lmops = NULL;
 201}
 202
 203EXPORT_SYMBOL(locks_init_lock);
 204
 205/*
 206 * Initialises the fields of the file lock which are invariant for
 207 * free file_locks.
 208 */
 209static void init_once(void *foo, kmem_cache_t *cache, unsigned long flags)
 210{
 211	struct file_lock *lock = (struct file_lock *) foo;
 212
 213	if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) !=
 214					SLAB_CTOR_CONSTRUCTOR)
 215		return;
 216
 217	locks_init_lock(lock);
 218}
 219
 220/*
 221 * Initialize a new lock from an existing file_lock structure.
 222 */
 223void locks_copy_lock(struct file_lock *new, struct file_lock *fl)
 224{
 225	new->fl_owner = fl->fl_owner;
 226	new->fl_pid = fl->fl_pid;
 227	new->fl_file = fl->fl_file;
 228	new->fl_flags = fl->fl_flags;
 229	new->fl_type = fl->fl_type;
 230	new->fl_start = fl->fl_start;
 231	new->fl_end = fl->fl_end;
 232	new->fl_ops = fl->fl_ops;
 233	new->fl_lmops = fl->fl_lmops;
 234	if (fl->fl_ops && fl->fl_ops->fl_copy_lock)
 235		fl->fl_ops->fl_copy_lock(new, fl);
 236	if (fl->fl_lmops && fl->fl_lmops->fl_copy_lock)
 237		fl->fl_lmops->fl_copy_lock(new, fl);
 238}
 239
 240EXPORT_SYMBOL(locks_copy_lock);
 241
 242static inline int flock_translate_cmd(int cmd) {
 243	if (cmd & LOCK_MAND)
 244		return cmd & (LOCK_MAND | LOCK_RW);
 245	switch (cmd) {
 246	case LOCK_SH:
 247		return F_RDLCK;
 248	case LOCK_EX:
 249		return F_WRLCK;
 250	case LOCK_UN:
 251		return F_UNLCK;
 252	}
 253	return -EINVAL;
 254}
 255
 256/* Fill in a file_lock structure with an appropriate FLOCK lock. */
 257static int flock_make_lock(struct file *filp, struct file_lock **lock,
 258		unsigned int cmd)
 259{
 260	struct file_lock *fl;
 261	int type = flock_translate_cmd(cmd);
 262	if (type < 0)
 263		return type;
 264	
 265	fl = locks_alloc_lock();
 266	if (fl == NULL)
 267		return -ENOMEM;
 268
 269	fl->fl_file = filp;
 270	fl->fl_pid = current->tgid;
 271	fl->fl_flags = FL_FLOCK;
 272	fl->fl_type = type;
 273	fl->fl_end = OFFSET_MAX;
 274	
 275	*lock = fl;
 276	return 0;
 277}
 278
 279static int assign_type(struct file_lock *fl, int type)
 280{
 281	switch (type) {
 282	case F_RDLCK:
 283	case F_WRLCK:
 284	case F_UNLCK:
 285		fl->fl_type = type;
 286		break;
 287	default:
 288		return -EINVAL;
 289	}
 290	return 0;
 291}
 292
 293/* Verify a "struct flock" and copy it to a "struct file_lock" as a POSIX
 294 * style lock.
 295 */
 296static int flock_to_posix_lock(struct file *filp, struct file_lock *fl,
 297			       struct flock *l)
 298{
 299	off_t start, end;
 300
 301	switch (l->l_whence) {
 302	case 0: /*SEEK_SET*/
 303		start = 0;
 304		break;
 305	case 1: /*SEEK_CUR*/
 306		start = filp->f_pos;
 307		break;
 308	case 2: /*SEEK_END*/
 309		start = i_size_read(filp->f_dentry->d_inode);
 310		break;
 311	default:
 312		return -EINVAL;
 313	}
 314
 315	/* POSIX-1996 leaves the case l->l_len < 0 undefined;
 316	   POSIX-2001 defines it. */
 317	start += l->l_start;
 318	end = start + l->l_len - 1;
 319	if (l->l_len < 0) {
 320		end = start - 1;
 321		start += l->l_len;
 322	}
 323
 324	if (start < 0)
 325		return -EINVAL;
 326	if (l->l_len > 0 && end < 0)
 327		return -EOVERFLOW;
 328
 329	fl->fl_start = start;	/* we record the absolute position */
 330	fl->fl_end = end;
 331	if (l->l_len == 0)
 332		fl->fl_end = OFFSET_MAX;
 333	
 334	fl->fl_owner = current->files;
 335	fl->fl_pid = current->tgid;
 336	fl->fl_file = filp;
 337	fl->fl_flags = FL_POSIX;
 338	fl->fl_ops = NULL;
 339	fl->fl_lmops = NULL;
 340
 341	return assign_type(fl, l->l_type);
 342}
 343
 344#if BITS_PER_LONG == 32
 345static int flock64_to_posix_lock(struct file *filp, struct file_lock *fl,
 346				 struct flock64 *l)
 347{
 348	loff_t start;
 349
 350	switch (l->l_whence) {
 351	case 0: /*SEEK_SET*/
 352		start = 0;
 353		break;
 354	case 1: /*SEEK_CUR*/
 355		start = filp->f_pos;
 356		break;
 357	case 2: /*SEEK_END*/
 358		start = i_size_read(filp->f_dentry->d_inode);
 359		break;
 360	default:
 361		return -EINVAL;
 362	}
 363
 364	if (((start += l->l_start) < 0) || (l->l_len < 0))
 365		return -EINVAL;
 366	fl->fl_end = start + l->l_len - 1;
 367	if (l->l_len > 0 && fl->fl_end < 0)
 368		return -EOVERFLOW;
 369	fl->fl_start = start;	/* we record the absolute position */
 370	if (l->l_len == 0)
 371		fl->fl_end = OFFSET_MAX;
 372	
 373	fl->fl_owner = current->files;
 374	fl->fl_pid = current->tgid;
 375	fl->fl_file = filp;
 376	fl->fl_flags = FL_POSIX;
 377	fl->fl_ops = NULL;
 378	fl->fl_lmops = NULL;
 379
 380	switch (l->l_type) {
 381	case F_RDLCK:
 382	case F_WRLCK:
 383	case F_UNLCK:
 384		fl->fl_type = l->l_type;
 385		break;
 386	default:
 387		return -EINVAL;
 388	}
 389
 390	return (0);
 391}
 392#endif
 393
 394/* default lease lock manager operations */
 395static void lease_break_callback(struct file_lock *fl)
 396{
 397	kill_fasync(&fl->fl_fasync, SIGIO, POLL_MSG);
 398}
 399
 400static void lease_release_private_callback(struct file_lock *fl)
 401{
 402	if (!fl->fl_file)
 403		return;
 404
 405	f_delown(fl->fl_file);
 406	fl->fl_file->f_owner.signum = 0;
 407}
 408
 409int lease_mylease_callback(struct file_lock *fl, struct file_lock *try)
 410{
 411	return fl->fl_file == try->fl_file;
 412}
 413
 414struct lock_manager_operations lease_manager_ops = {
 415	.fl_break = lease_break_callback,
 416	.fl_release_private = lease_release_private_callback,
 417	.fl_mylease = lease_mylease_callback,
 418	.fl_change = lease_modify,
 419};
 420
 421/*
 422 * Initialize a lease, use the default lock manager operations
 423 */
 424static int lease_init(struct file *filp, int type, struct file_lock *fl)
 425 {
 426	fl->fl_owner = current->files;
 427	fl->fl_pid = current->tgid;
 428
 429	fl->fl_file = filp;
 430	fl->fl_flags = FL_LEASE;
 431	if (assign_type(fl, type) != 0) {
 432		locks_free_lock(fl);
 433		return -EINVAL;
 434	}
 435	fl->fl_start = 0;
 436	fl->fl_end = OFFSET_MAX;
 437	fl->fl_ops = NULL;
 438	fl->fl_lmops = &lease_manager_ops;
 439	return 0;
 440}
 441
 442/* Allocate a file_lock initialised to this type of lease */
 443static int lease_alloc(struct file *filp, int type, struct file_lock **flp)
 444{
 445	struct file_lock *fl = locks_alloc_lock();
 446	int error;
 447
 448	if (fl == NULL)
 449		return -ENOMEM;
 450
 451	error = lease_init(filp, type, fl);
 452	if (error)
 453		return error;
 454	*flp = fl;
 455	return 0;
 456}
 457
 458/* Check if two locks overlap each other.
 459 */
 460static inline int locks_overlap(struct file_lock *fl1, struct file_lock *fl2)
 461{
 462	return ((fl1->fl_end >= fl2->fl_start) &&
 463		(fl2->fl_end >= fl1->fl_start));
 464}
 465
 466/*
 467 * Check whether two locks have the same owner.
 468 */
 469static inline int
 470posix_same_owner(struct file_lock *fl1, struct file_lock *fl2)
 471{
 472	if (fl1->fl_lmops && fl1->fl_lmops->fl_compare_owner)
 473		return fl2->fl_lmops == fl1->fl_lmops &&
 474			fl1->fl_lmops->fl_compare_owner(fl1, fl2);
 475	return fl1->fl_owner == fl2->fl_owner;
 476}
 477
 478/* Remove waiter from blocker's block list.
 479 * When blocker ends up pointing to itself then the list is empty.
 480 */
 481static inline void __locks_delete_block(struct file_lock *waiter)
 482{
 483	list_del_init(&waiter->fl_block);
 484	list_del_init(&waiter->fl_link);
 485	waiter->fl_next = NULL;
 486}
 487
 488/*
 489 */
 490static void locks_delete_block(struct file_lock *waiter)
 491{
 492	lock_kernel();
 493	__locks_delete_block(waiter);
 494	unlock_kernel();
 495}
 496
 497/* Insert waiter into blocker's block list.
 498 * We use a circular list so that processes can be easily woken up in
 499 * the order they blocked. The documentation doesn't require this but
 500 * it seems like the reasonable thing to do.
 501 */
 502static void locks_insert_block(struct file_lock *blocker, 
 503			       struct file_lock *waiter)
 504{
 505	if (!list_empty(&waiter->fl_block)) {
 506		printk(KERN_ERR "locks_insert_block: removing duplicated lock "
 507			"(pid=%d %Ld-%Ld type=%d)\n", waiter->fl_pid,
 508			waiter->fl_start, waiter->fl_end, waiter->fl_type);
 509		__locks_delete_block(waiter);
 510	}
 511	list_add_tail(&waiter->fl_block, &blocker->fl_block);
 512	waiter->fl_next = blocker;
 513	if (IS_POSIX(blocker))
 514		list_add(&waiter->fl_link, &blocked_list);
 515}
 516
 517/* Wake up processes blocked waiting for blocker.
 518 * If told to wait then schedule the processes until the block list
 519 * is empty, otherwise empty the block list ourselves.
 520 */
 521static void locks_wake_up_blocks(struct file_lock *blocker)
 522{
 523	while (!list_empty(&blocker->fl_block)) {
 524		struct file_lock *waiter = list_entry(blocker->fl_block.next,
 525				struct file_lock, fl_block);
 526		__locks_delete_block(waiter);
 527		if (waiter->fl_lmops && waiter->fl_lmops->fl_notify)
 528			waiter->fl_lmops->fl_notify(waiter);
 529		else
 530			wake_up(&waiter->fl_wait);
 531	}
 532}
 533
 534/* Insert file lock fl into an inode's lock list at the position indicated
 535 * by pos. At the same time add the lock to the global file lock list.
 536 */
 537static void locks_insert_lock(struct file_lock **pos, struct file_lock *fl)
 538{
 539	list_add(&fl->fl_link, &file_lock_list);
 540
 541	/* insert into file's list */
 542	fl->fl_next = *pos;
 543	*pos = fl;
 544
 545	if (fl->fl_ops && fl->fl_ops->fl_insert)
 546		fl->fl_ops->fl_insert(fl);
 547}
 548
 549/*
 550 * Delete a lock and then free it.
 551 * Wake up processes that are blocked waiting for this lock,
 552 * notify the FS that the lock has been cleared and
 553 * finally free the lock.
 554 */
 555static void locks_delete_lock(struct file_lock **thisfl_p)
 556{
 557	struct file_lock *fl = *thisfl_p;
 558
 559	*thisfl_p = fl->fl_next;
 560	fl->fl_next = NULL;
 561	list_del_init(&fl->fl_link);
 562
 563	fasync_helper(0, fl->fl_file, 0, &fl->fl_fasync);
 564	if (fl->fl_fasync != NULL) {
 565		printk(KERN_ERR "locks_delete_lock: fasync == %p\n", fl->fl_fasync);
 566		fl->fl_fasync = NULL;
 567	}
 568
 569	if (fl->fl_ops && fl->fl_ops->fl_remove)
 570		fl->fl_ops->fl_remove(fl);
 571
 572	locks_wake_up_blocks(fl);
 573	locks_free_lock(fl);
 574}
 575
 576/* Determine if lock sys_fl blocks lock caller_fl. Common functionality
 577 * checks for shared/exclusive status of overlapping locks.
 578 */
 579static int locks_conflict(struct file_lock *caller_fl, struct file_lock *sys_fl)
 580{
 581	if (sys_fl->fl_type == F_WRLCK)
 582		return 1;
 583	if (caller_fl->fl_type == F_WRLCK)
 584		return 1;
 585	return 0;
 586}
 587
 588/* Determine if lock sys_fl blocks lock caller_fl. POSIX specific
 589 * checking before calling the locks_conflict().
 590 */
 591static int posix_locks_conflict(struct file_lock *caller_fl, struct file_lock *sys_fl)
 592{
 593	/* POSIX locks owned by the same process do not conflict with
 594	 * each other.
 595	 */
 596	if (!IS_POSIX(sys_fl) || posix_same_owner(caller_fl, sys_fl))
 597		return (0);
 598
 599	/* Check whether they overlap */
 600	if (!locks_overlap(caller_fl, sys_fl))
 601		return 0;
 602
 603	return (locks_conflict(caller_fl, sys_fl));
 604}
 605
 606/* Determine if lock sys_fl blocks lock caller_fl. FLOCK specific
 607 * checking before calling the locks_conflict().
 608 */
 609static int flock_locks_conflict(struct file_lock *caller_fl, struct file_lock *sys_fl)
 610{
 611	/* FLOCK locks referring to the same filp do not conflict with
 612	 * each other.
 613	 */
 614	if (!IS_FLOCK(sys_fl) || (caller_fl->fl_file == sys_fl->fl_file))
 615		return (0);
 616	if ((caller_fl->fl_type & LOCK_MAND) || (sys_fl->fl_type & LOCK_MAND))
 617		return 0;
 618
 619	return (locks_conflict(caller_fl, sys_fl));
 620}
 621
 622static int interruptible_sleep_on_locked(wait_queue_head_t *fl_wait, int timeout)
 623{
 624	int result = 0;
 625	DECLARE_WAITQUEUE(wait, current);
 626
 627	__set_current_state(TASK_INTERRUPTIBLE);
 628	add_wait_queue(fl_wait, &wait);
 629	if (timeout == 0)
 630		schedule();
 631	else
 632		result = schedule_timeout(timeout);
 633	if (signal_pending(current))
 634		result = -ERESTARTSYS;
 635	remove_wait_queue(fl_wait, &wait);
 636	__set_current_state(TASK_RUNNING);
 637	return result;
 638}
 639
 640static int locks_block_on_timeout(struct file_lock *blocker, struct file_lock *waiter, int time)
 641{
 642	int result;
 643	locks_insert_block(blocker, waiter);
 644	result = interruptible_sleep_on_locked(&waiter->fl_wait, time);
 645	__locks_delete_block(waiter);
 646	return result;
 647}
 648
 649struct file_lock *
 650posix_test_lock(struct file *filp, struct file_lock *fl)
 651{
 652	struct file_lock *cfl;
 653
 654	lock_kernel();
 655	for (cfl = filp->f_dentry->d_inode->i_flock; cfl; cfl = cfl->fl_next) {
 656		if (!IS_POSIX(cfl))
 657			continue;
 658		if (posix_locks_conflict(cfl, fl))
 659			break;
 660	}
 661	unlock_kernel();
 662
 663	return (cfl);
 664}
 665
 666EXPORT_SYMBOL(posix_test_lock);
 667
 668/* This function tests for deadlock condition before putting a process to
 669 * sleep. The detection scheme is no longer recursive. Recursive was neat,
 670 * but dangerous - we risked stack corruption if the lock data was bad, or
 671 * if the recursion was too deep for any other reason.
 672 *
 673 * We rely on the fact that a task can only be on one lock's wait queue
 674 * at a time. When we find blocked_task on a wait queue we can re-search
 675 * with blocked_task equal to that queue's owner, until either blocked_task
 676 * isn't found, or blocked_task is found on a queue owned by my_task.
 677 *
 678 * Note: the above assumption may not be true when handling lock requests
 679 * from a broken NFS client. But broken NFS clients have a lot more to
 680 * worry about than proper deadlock detection anyway... --okir
 681 */
 682int posix_locks_deadlock(struct file_lock *caller_fl,
 683				struct file_lock *block_fl)
 684{
 685	struct list_head *tmp;
 686
 687next_task:
 688	if (posix_same_owner(caller_fl, block_fl))
 689		return 1;
 690	list_for_each(tmp, &blocked_list) {
 691		struct file_lock *fl = list_entry(tmp, struct file_lock, fl_link);
 692		if (posix_same_owner(fl, block_fl)) {
 693			fl = fl->fl_next;
 694			block_fl = fl;
 695			goto next_task;
 696		}
 697	}
 698	return 0;
 699}
 700
 701EXPORT_SYMBOL(posix_locks_deadlock);
 702
 703/* Try to create a FLOCK lock on filp. We always insert new FLOCK locks
 704 * at the head of the list, but that's secret knowledge known only to
 705 * flock_lock_file and posix_lock_file.
 706 */
 707static int flock_lock_file(struct file *filp, struct file_lock *new_fl)
 708{
 709	struct file_lock **before;
 710	struct inode * inode = filp->f_dentry->d_inode;
 711	int error = 0;
 712	int found = 0;
 713
 714	lock_kernel();
 715	for_each_lock(inode, before) {
 716		struct file_lock *fl = *before;
 717		if (IS_POSIX(fl))
 718			break;
 719		if (IS_LEASE(fl))
 720			continue;
 721		if (filp != fl->fl_file)
 722			continue;
 723		if (new_fl->fl_type == fl->fl_type)
 724			goto out;
 725		found = 1;
 726		locks_delete_lock(before);
 727		break;
 728	}
 729	unlock_kernel();
 730
 731	if (new_fl->fl_type == F_UNLCK)
 732		return 0;
 733
 734	/*
 735	 * If a higher-priority process was blocked on the old file lock,
 736	 * give it the opportunity to lock the file.
 737	 */
 738	if (found)
 739		cond_resched();
 740
 741	lock_kernel();
 742	for_each_lock(inode, before) {
 743		struct file_lock *fl = *before;
 744		if (IS_POSIX(fl))
 745			break;
 746		if (IS_LEASE(fl))
 747			continue;
 748		if (!flock_locks_conflict(new_fl, fl))
 749			continue;
 750		error = -EAGAIN;
 751		if (new_fl->fl_flags & FL_SLEEP) {
 752			locks_insert_block(fl, new_fl);
 753		}
 754		goto out;
 755	}
 756	locks_insert_lock(&inode->i_flock, new_fl);
 757	error = 0;
 758
 759out:
 760	unlock_kernel();
 761	return error;
 762}
 763
 764EXPORT_SYMBOL(posix_lock_file);
 765
 766static int __posix_lock_file(struct inode *inode, struct file_lock *request)
 767{
 768	struct file_lock *fl;
 769	struct file_lock *new_fl, *new_fl2;
 770	struct file_lock *left = NULL;
 771	struct file_lock *right = NULL;
 772	struct file_lock **before;
 773	int error, added = 0;
 774
 775	/*
 776	 * We may need two file_lock structures for this operation,
 777	 * so we get them in advance to avoid races.
 778	 */
 779	new_fl = locks_alloc_lock();
 780	new_fl2 = locks_alloc_lock();
 781
 782	lock_kernel();
 783	if (request->fl_type != F_UNLCK) {
 784		for_each_lock(inode, before) {
 785			struct file_lock *fl = *before;
 786			if (!IS_POSIX(fl))
 787				continue;
 788			if (!posix_locks_conflict(request, fl))
 789				continue;
 790			error = -EAGAIN;
 791			if (!(request->fl_flags & FL_SLEEP))
 792				goto out;
 793			error = -EDEADLK;
 794			if (posix_locks_deadlock(request, fl))
 795				goto out;
 796			error = -EAGAIN;
 797			locks_insert_block(fl, request);
 798			goto out;
 799  		}
 800  	}
 801
 802	/* If we're just looking for a conflict, we're done. */
 803	error = 0;
 804	if (request->fl_flags & FL_ACCESS)
 805		goto out;
 806
 807	error = -ENOLCK; /* "no luck" */
 808	if (!(new_fl && new_fl2))
 809		goto out;
 810
 811	/*
 812	 * We've allocated the new locks in advance, so there are no
 813	 * errors possible (and no blocking operations) from here on.
 814	 * 
 815	 * Find the first old lock with the same owner as the new lock.
 816	 */
 817	
 818	before = &inode->i_flock;
 819
 820	/* First skip locks owned by other processes.  */
 821	while ((fl = *before) && (!IS_POSIX(fl) ||
 822				  !posix_same_owner(request, fl))) {
 823		before = &fl->fl_next;
 824	}
 825
 826	/* Process locks with this owner.  */
 827	while ((fl = *before) && posix_same_owner(request, fl)) {
 828		/* Detect adjacent or overlapping regions (if same lock type)
 829		 */
 830		if (request->fl_type == fl->fl_type) {
 831			if (fl->fl_end < request->fl_start - 1)
 832				goto next_lock;
 833			/* If the next lock in the list has entirely bigger
 834			 * addresses than the new one, insert the lock here.
 835			 */
 836			if (fl->fl_start > request->fl_end + 1)
 837				break;
 838
 839			/* If we come here, the new and old lock are of the
 840			 * same type and adjacent or overlapping. Make one
 841			 * lock yielding from the lower start address of both
 842			 * locks to the higher end address.
 843			 */
 844			if (fl->fl_start > request->fl_start)
 845				fl->fl_start = request->fl_start;
 846			else
 847				request->fl_start = fl->fl_start;
 848			if (fl->fl_end < request->fl_end)
 849				fl->fl_end = request->fl_end;
 850			else
 851				request->fl_end = fl->fl_end;
 852			if (added) {
 853				locks_delete_lock(before);
 854				continue;
 855			}
 856			request = fl;
 857			added = 1;
 858		}
 859		else {
 860			/* Processing for different lock types is a bit
 861			 * more complex.
 862			 */
 863			if (fl->fl_end < request->fl_start)
 864				goto next_lock;
 865			if (fl->fl_start > request->fl_end)
 866				break;
 867			if (request->fl_type == F_UNLCK)
 868				added = 1;
 869			if (fl->fl_start < request->fl_start)
 870				left = fl;
 871			/* If the next lock in the list has a higher end
 872			 * address than the new one, insert the new one here.
 873			 */
 874			if (fl->fl_end > request->fl_end) {
 875				right = fl;
 876				break;
 877			}
 878			if (fl->fl_start >= request->fl_start) {
 879				/* The new lock completely replaces an old
 880				 * one (This may happen several times).
 881				 */
 882				if (added) {
 883					locks_delete_lock(before);
 884					continue;
 885				}
 886				/* Replace the old lock with the new one.
 887				 * Wake up anybody waiting for the old one,
 888				 * as the change in lock type might satisfy
 889				 * their needs.
 890				 */
 891				locks_wake_up_blocks(fl);
 892				fl->fl_start = request->fl_start;
 893				fl->fl_end = request->fl_end;
 894				fl->fl_type = request->fl_type;
 895				fl->fl_u = request->fl_u;
 896				request = fl;
 897				added = 1;
 898			}
 899		}
 900		/* Go on to next lock.
 901		 */
 902	next_lock:
 903		before = &fl->fl_next;
 904	}
 905
 906	error = 0;
 907	if (!added) {
 908		if (request->fl_type == F_UNLCK)
 909			goto out;
 910		locks_copy_lock(new_fl, request);
 911		locks_insert_lock(before, new_fl);
 912		new_fl = NULL;
 913	}
 914	if (right) {
 915		if (left == right) {
 916			/* The new lock breaks the old one in two pieces,
 917			 * so we have to use the second new lock.
 918			 */
 919			left = new_fl2;
 920			new_fl2 = NULL;
 921			locks_copy_lock(left, right);
 922			locks_insert_lock(before, left);
 923		}
 924		right->fl_start = request->fl_end + 1;
 925		locks_wake_up_blocks(right);
 926	}
 927	if (left) {
 928		left->fl_end = request->fl_start - 1;
 929		locks_wake_up_blocks(left);
 930	}
 931 out:
 932	unlock_kernel();
 933	/*
 934	 * Free any unused locks.
 935	 */
 936	if (new_fl)
 937		locks_free_lock(new_fl);
 938	if (new_fl2)
 939		locks_free_lock(new_fl2);
 940	return error;
 941}
 942
 943/**
 944 * posix_lock_file - Apply a POSIX-style lock to a file
 945 * @filp: The file to apply the lock to
 946 * @fl: The lock to be applied
 947 *
 948 * Add a POSIX style lock to a file.
 949 * We merge adjacent & overlapping locks whenever possible.
 950 * POSIX locks are sorted by owner task, then by starting address
 951 */
 952int posix_lock_file(struct file *filp, struct file_lock *fl)
 953{
 954	return __posix_lock_file(filp->f_dentry->d_inode, fl);
 955}
 956
 957/**
 958 * posix_lock_file_wait - Apply a POSIX-style lock to a file
 959 * @filp: The file to apply the lock to
 960 * @fl: The lock to be applied
 961 *
 962 * Add a POSIX style lock to a file.
 963 * We merge adjacent & overlapping locks whenever possible.
 964 * POSIX locks are sorted by owner task, then by starting address
 965 */
 966int posix_lock_file_wait(struct file *filp, struct file_lock *fl)
 967{
 968	int error;
 969	might_sleep ();
 970	for (;;) {
 971		error = __posix_lock_file(filp->f_dentry->d_inode, fl);
 972		if ((error != -EAGAIN) || !(fl->fl_flags & FL_SLEEP))
 973			break;
 974		error = wait_event_interruptible(fl->fl_wait, !fl->fl_next);
 975		if (!error)
 976			continue;
 977
 978		locks_delete_block(fl);
 979		break;
 980	}
 981	return error;
 982}
 983EXPORT_SYMBOL(posix_lock_file_wait);
 984
 985/**
 986 * locks_mandatory_locked - Check for an active lock
 987 * @inode: the file to check
 988 *
 989 * Searches the inode's list of locks to find any POSIX locks which conflict.
 990 * This function is called from locks_verify_locked() only.
 991 */
 992int locks_mandatory_locked(struct inode *inode)
 993{
 994	fl_owner_t owner = current->files;
 995	struct file_lock *fl;
 996
 997	/*
 998	 * Search the lock list for this inode for any POSIX locks.
 999	 */
1000	lock_kernel();
1001	for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) {
1002		if (!IS_POSIX(fl))
1003			continue;
1004		if (fl->fl_owner != owner)
1005			break;
1006	}
1007	unlock_kernel();
1008	return fl ? -EAGAIN : 0;
1009}
1010
1011/**
1012 * locks_mandatory_area - Check for a conflicting lock
1013 * @read_write: %FLOCK_VERIFY_WRITE for exclusive access, %FLOCK_VERIFY_READ
1014 *		for shared
1015 * @inode:      the file to check
1016 * @filp:       how the file was opened (if it was)
1017 * @offset:     start of area to check
1018 * @count:      length of area to check
1019 *
1020 * Searches the inode's list of locks to find any POSIX locks which conflict.
1021 * This function is called from rw_verify_area() and
1022 * locks_verify_truncate().
1023 */
1024int locks_mandatory_area(int read_write, struct inode *inode,
1025			 struct file *filp, loff_t offset,
1026			 size_t count)
1027{
1028	struct file_lock fl;
1029	int error;
1030
1031	locks_init_lock(&fl);
1032	fl.fl_owner = current->files;
1033	fl.fl_pid = current->tgid;
1034	fl.fl_file = filp;
1035	fl.fl_flags = FL_POSIX | FL_ACCESS;
1036	if (filp && !(filp->f_flags & O_NONBLOCK))
1037		fl.fl_flags |= FL_SLEEP;
1038	fl.fl_type = (read_write == FLOCK_VERIFY_WRITE) ? F_WRLCK : F_RDLCK;
1039	fl.fl_start = offset;
1040	fl.fl_end = offset + count - 1;
1041
1042	for (;;) {
1043		error = __posix_lock_file(inode, &fl);
1044		if (error != -EAGAIN)
1045			break;
1046		if (!(fl.fl_flags & FL_SLEEP))
1047			break;
1048		error = wait_event_interruptible(fl.fl_wait, !fl.fl_next);
1049		if (!error) {
1050			/*
1051			 * If we've been sleeping someone might have
1052			 * changed the permissions behind our back.
1053			 */
1054			if ((inode->i_mode & (S_ISGID | S_IXGRP)) == S_ISGID)
1055				continue;
1056		}
1057
1058		locks_delete_block(&fl);
1059		break;
1060	}
1061
1062	return error;
1063}
1064
1065EXPORT_SYMBOL(locks_mandatory_area);
1066
1067/* We already had a lease on this file; just change its type */
1068int lease_modify(struct file_lock **before, int arg)
1069{
1070	struct file_lock *fl = *before;
1071	int error = assign_type(fl, arg);
1072
1073	if (error)
1074		return error;
1075	locks_wake_up_blocks(fl);
1076	if (arg == F_UNLCK)
1077		locks_delete_lock(before);
1078	return 0;
1079}
1080
1081EXPORT_SYMBOL(lease_modify);
1082
1083static void time_out_leases(struct inode *inode)
1084{
1085	struct file_lock **before;
1086	struct file_lock *fl;
1087
1088	before = &inode->i_flock;
1089	while ((fl = *before) && IS_LEASE(fl) && (fl->fl_type & F_INPROGRESS)) {
1090		if ((fl->fl_break_time == 0)
1091				|| time_before(jiffies, fl->fl_break_time)) {
1092			before = &fl->fl_next;
1093			continue;
1094		}
1095		printk(KERN_INFO "lease broken - owner pid = %d\n", fl->fl_pid);
1096		lease_modify(before, fl->fl_type & ~F_INPROGRESS);
1097		if (fl == *before)	/* lease_modify may have freed fl */
1098			before = &fl->fl_next;
1099	}
1100}
1101
1102/**
1103 *	__break_lease	-	revoke all outstanding leases on file
1104 *	@inode: the inode of the file to return
1105 *	@mode: the open mode (read or write)
1106 *
1107 *	break_lease (inlined for speed) has checked there already
1108 *	is a lease on this file.  Leases are broken on a call to open()
1109 *	or truncate().  This function can sleep unless you
1110 *	specified %O_NONBLOCK to your open().
1111 */
1112int __break_lease(struct inode *inode, unsigned int mode)
1113{
1114	int error = 0, future;
1115	struct file_lock *new_fl, *flock;
1116	struct file_lock *fl;
1117	int alloc_err;
1118	unsigned long break_time;
1119	int i_have_this_lease = 0;
1120
1121	alloc_err = lease_alloc(NULL, mode & FMODE_WRITE ? F_WRLCK : F_RDLCK,
1122			&new_fl);
1123
1124	lock_kernel();
1125
1126	time_out_leases(inode);
1127
1128	flock = inode->i_flock;
1129	if ((flock == NULL) || !IS_LEASE(flock))
1130		goto out;
1131
1132	for (fl = flock; fl && IS_LEASE(fl); fl = fl->fl_next)
1133		if (fl->fl_owner == current->files)
1134			i_have_this_lease = 1;
1135
1136	if (mode & FMODE_WRITE) {
1137		/* If we want write access, we have to revoke any lease. */
1138		future = F_UNLCK | F_INPROGRESS;
1139	} else if (flock->fl_type & F_INPROGRESS) {
1140		/* If the lease is already being broken, we just leave it */
1141		future = flock->fl_type;
1142	} else if (flock->fl_type & F_WRLCK) {
1143		/* Downgrade the exclusive lease to a read-only lease. */
1144		future = F_RDLCK | F_INPROGRESS;
1145	} else {
1146		/* the existing lease was read-only, so we can read too. */
1147		goto out;
1148	}
1149
1150	if (alloc_err && !i_have_this_lease && ((mode & O_NONBLOCK) == 0)) {
1151		error = alloc_err;
1152		goto out;
1153	}
1154
1155	break_time = 0;
1156	if (lease_break_time > 0) {
1157		break_time = jiffies + lease_break_time * HZ;
1158		if (break_time == 0)
1159			break_time++;	/* so that 0 means no break time */
1160	}
1161
1162	for (fl = flock; fl && IS_LEASE(fl); fl = fl->fl_next) {
1163		if (fl->fl_type != future) {
1164			fl->fl_type = future;
1165			fl->fl_break_time = break_time;
1166			/* lease must have lmops break callback */
1167			fl->fl_lmops->fl_break(fl);
1168		}
1169	}
1170
1171	if (i_have_this_lease || (mode & O_NONBLOCK)) {
1172		error = -EWOULDBLOCK;
1173		goto out;
1174	}
1175
1176restart:
1177	break_time = flock->fl_break_time;
1178	if (break_time != 0) {
1179		break_time -= jiffies;
1180		if (break_time == 0)
1181			break_time++;
1182	}
1183	error = locks_block_on_timeout(flock, new_fl, break_time);
1184	if (error >= 0) {
1185		if (error == 0)
1186			time_out_leases(inode);
1187		/* Wait for the next lease that has not been broken yet */
1188		for (flock = inode->i_flock; flock && IS_LEASE(flock);
1189				flock = flock->fl_next) {
1190			if (flock->fl_type & F_INPROGRESS)
1191				goto restart;
1192		}
1193		error = 0;
1194	}
1195
1196out:
1197	unlock_kernel();
1198	if (!alloc_err)
1199		locks_free_lock(new_fl);
1200	return error;
1201}
1202
1203EXPORT_SYMBOL(__break_lease);
1204
1205/**
1206 *	lease_get_mtime
1207 *	@inode: the inode
1208 *      @time:  pointer to a timespec which will contain the last modified time
1209 *
1210 * This is to force NFS clients to flush their caches for files with
1211 * exclusive leases.  The justification is that if someone has an
1212 * exclusive lease, then they could be modifiying it.
1213 */
1214void lease_get_mtime(struct inode *inode, struct timespec *time)
1215{
1216	struct file_lock *flock = inode->i_flock;
1217	if (flock && IS_LEASE(flock) && (flock->fl_type & F_WRLCK))
1218		*time = current_fs_time(inode->i_sb);
1219	else
1220		*time = inode->i_mtime;
1221}
1222
1223EXPORT_SYMBOL(lease_get_mtime);
1224
1225/**
1226 *	fcntl_getlease - Enquire what lease is currently active
1227 *	@filp: the file
1228 *
1229 *	The value returned by this function will be one of
1230 *	(if no lease break is pending):
1231 *
1232 *	%F_RDLCK to indicate a shared lease is held.
1233 *
1234 *	%F_WRLCK to indicate an exclusive lease is held.
1235 *
1236 *	%F_UNLCK to indicate no lease is held.
1237 *
1238 *	(if a lease break is pending):
1239 *
1240 *	%F_RDLCK to indicate an exclusive lease needs to be
1241 *		changed to a shared lease (or removed).
1242 *
1243 *	%F_UNLCK to indicate the lease needs to be removed.
1244 *
1245 *	XXX: sfr & willy disagree over whether F_INPROGRESS
1246 *	should be returned to userspace.
1247 */
1248int fcntl_getlease(struct file *filp)
1249{
1250	struct file_lock *fl;
1251	int type = F_UNLCK;
1252
1253	lock_kernel();
1254	time_out_leases(filp->f_dentry->d_inode);
1255	for (fl = filp->f_dentry->d_inode->i_flock; fl && IS_LEASE(fl);
1256			fl = fl->fl_next) {
1257		if (fl->fl_file == filp) {
1258			type = fl->fl_type & ~F_INPROGRESS;
1259			break;
1260		}
1261	}
1262	unlock_kernel();
1263	return type;
1264}
1265
1266/**
1267 *	__setlease	-	sets a lease on an open file
1268 *	@filp: file pointer
1269 *	@arg: type of lease to obtain
1270 *	@flp: input - file_lock to use, output - file_lock inserted
1271 *
1272 *	The (input) flp->fl_lmops->fl_break function is required
1273 *	by break_lease().
1274 *
1275 *	Called with kernel lock held.
1276 */
1277int __setlease(struct file *filp, long arg, struct file_lock **flp)
1278{
1279	struct file_lock *fl, **before, **my_before = NULL, *lease = *flp;
1280	struct dentry *dentry = filp->f_dentry;
1281	struct inode *inode = dentry->d_inode;
1282	int error, rdlease_count = 0, wrlease_count = 0;
1283
1284	time_out_leases(inode);
1285
1286	error = -EINVAL;
1287	if (!flp || !(*flp) || !(*flp)->fl_lmops || !(*flp)->fl_lmops->fl_break)
1288		goto out;
1289
1290	error = -EAGAIN;
1291	if ((arg == F_RDLCK) && (atomic_read(&inode->i_writecount) > 0))
1292		goto out;
1293	if ((arg == F_WRLCK)
1294	    && ((atomic_read(&dentry->d_count) > 1)
1295		|| (atomic_read(&inode->i_count) > 1)))
1296		goto out;
1297
1298	/*
1299	 * At this point, we know that if there is an exclusive
1300	 * lease on this file, then we hold it on this filp
1301	 * (otherwise our open of this file would have blocked).
1302	 * And if we are trying to acquire an exclusive lease,
1303	 * then the file is not open by anyone (including us)
1304	 * except for this filp.
1305	 */
1306	for (before = &inode->i_flock;
1307			((fl = *before) != NULL) && IS_LEASE(fl);
1308			before = &fl->fl_next) {
1309		if (lease->fl_lmops->fl_mylease(fl, lease))
1310			my_before = before;
1311		else if (fl->fl_type == (F_INPROGRESS | F_UNLCK))
1312			/*
1313			 * Someone is in the process of opening this
1314			 * file for writing so we may not take an
1315			 * exclusive lease on it.
1316			 */
1317			wrlease_count++;
1318		else
1319			rdlease_count++;
1320	}
1321
1322	if ((arg == F_RDLCK && (wrlease_count > 0)) ||
1323	    (arg == F_WRLCK && ((rdlease_count + wrlease_count) > 0)))
1324		goto out;
1325
1326	if (my_before != NULL) {
1327		error = lease->fl_lmops->fl_change(my_before, arg);
1328		goto out;
1329	}
1330
1331	error = 0;
1332	if (arg == F_UNLCK)
1333		goto out;
1334
1335	error = -EINVAL;
1336	if (!leases_enable)
1337		goto out;
1338
1339	error = lease_alloc(filp, arg, &fl);
1340	if (error)
1341		goto out;
1342
1343	locks_copy_lock(fl, lease);
1344
1345	locks_insert_lock(before, fl);
1346
1347	*flp = fl;
1348out:
1349	return error;
1350}
1351
1352 /**
1353 *	setlease        -       sets a lease on an open file
1354 *	@filp: file pointer
1355 *	@arg: type of lease to obtain
1356 *	@lease: file_lock to use
1357 *
1358 *	Call this to establish a lease on the file.
1359 *	The fl_lmops fl_break function is required by break_lease
1360 */
1361
1362int setlease(struct file *filp, long arg, struct file_lock **lease)
1363{
1364	struct dentry *dentry = filp->f_dentry;
1365	struct inode *inode = dentry->d_inode;
1366	int error;
1367
1368	if ((current->fsuid != inode->i_uid) && !capable(CAP_LEASE))
1369		return -EACCES;
1370	if (!S_ISREG(inode->i_mode))
1371		return -EINVAL;
1372	error = security_file_lock(filp, arg);
1373	if (error)
1374		return error;
1375
1376	lock_kernel();
1377	error = __setlease(filp, arg, lease);
1378	unlock_kernel();
1379
1380	return error;
1381}
1382
1383EXPORT_SYMBOL(setlease);
1384
1385/**
1386 *	fcntl_setlease	-	sets a lease on an open file
1387 *	@fd: open file descriptor
1388 *	@filp: file pointer
1389 *	@arg: type of lease to obtain
1390 *
1391 *	Call this fcntl to establish a lease on the file.
1392 *	Note that you also need to call %F_SETSIG to
1393 *	receive a signal when the lease is broken.
1394 */
1395int fcntl_setlease(unsigned int fd, struct file *filp, long arg)
1396{
1397	struct file_lock fl, *flp = &fl;
1398	struct dentry *dentry = filp->f_dentry;
1399	struct inode *inode = dentry->d_inode;
1400	int error;
1401
1402	if ((current->fsuid != inode->i_uid) && !capable(CAP_LEASE))
1403		return -EACCES;
1404	if (!S_ISREG(inode->i_mode))
1405		return -EINVAL;
1406	error = security_file_lock(filp, arg);
1407	if (error)
1408		return error;
1409
1410	locks_init_lock(&fl);
1411	error = lease_init(filp, arg, &fl);
1412	if (error)
1413		return error;
1414
1415	lock_kernel();
1416
1417	error = __setlease(filp, arg, &flp);
1418	if (error)
1419		goto out_unlock;
1420
1421	error = fasync_helper(fd, filp, 1, &flp->fl_fasync);
1422	if (error < 0) {
1423		/* remove lease just inserted by __setlease */
1424		flp->fl_type = F_UNLCK | F_INPROGRESS;
1425		flp->fl_break_time = jiffies- 10;
1426		time_out_leases(inode);
1427		goto out_unlock;
1428	}
1429
1430	error = f_setown(filp, current->pid, 0);
1431out_unlock:
1432	unlock_kernel();
1433	return error;
1434}
1435
1436/**
1437 * flock_lock_file_wait - Apply a FLOCK-style lock to a file
1438 * @filp: The file to apply the lock to
1439 * @fl: The lock to be applied
1440 *
1441 * Add a FLOCK style lock to a file.
1442 */
1443int flock_lock_file_wait(struct file *filp, struct file_lock *fl)
1444{
1445	int error;
1446	might_sleep();
1447	for (;;) {
1448		error = flock_lock_file(filp, fl);
1449		if ((error != -EAGAIN) || !(fl->fl_flags & FL_SLEEP))
1450			break;
1451		error = wait_event_interruptible(fl->fl_wait, !fl->fl_next);
1452		if (!error)
1453			continue;
1454
1455		locks_delete_block(fl);
1456		break;
1457	}
1458	return error;
1459}
1460
1461EXPORT_SYMBOL(flock_lock_file_wait);
1462
1463/**
1464 *	sys_flock: - flock() system call.
1465 *	@fd: the file descriptor to lock.
1466 *	@cmd: the type of lock to apply.
1467 *
1468 *	Apply a %FL_FLOCK style lock to an open file descriptor.
1469 *	The @cmd can be one of
1470 *
1471 *	%LOCK_SH -- a shared lock.
1472 *
1473 *	%LOCK_EX -- an exclusive lock.
1474 *
1475 *	%LOCK_UN -- remove an existing lock.
1476 *
1477 *	%LOCK_MAND -- a `mandatory' flock.  This exists to emulate Windows Share Modes.
1478 *
1479 *	%LOCK_MAND can be combined with %LOCK_READ or %LOCK_WRITE to allow other
1480 *	processes read and write access respectively.
1481 */
1482asmlinkage long sys_flock(unsigned int fd, unsigned int cmd)
1483{
1484	struct file *filp;
1485	struct file_lock *lock;
1486	int can_sleep, unlock;
1487	int error;
1488
1489	error = -EBADF;
1490	filp = fget(fd);
1491	if (!filp)
1492		goto out;
1493
1494	can_sleep = !(cmd & LOCK_NB);
1495	cmd &= ~LOCK_NB;
1496	unlock = (cmd == LOCK_UN);
1497
1498	if (!unlock && !(cmd & LOCK_MAND) && !(filp->f_mode & 3))
1499		goto out_putf;
1500
1501	error = flock_make_lock(filp, &lock, cmd);
1502	if (error)
1503		goto out_putf;
1504	if (can_sleep)
1505		lock->fl_flags |= FL_SLEEP;
1506
1507	error = security_file_lock(filp, cmd);
1508	if (error)
1509		goto out_free;
1510
1511	if (filp->f_op && filp->f_op->flock)
1512		error = filp->f_op->flock(filp,
1513					  (can_sleep) ? F_SETLKW : F_SETLK,
1514					  lock);
1515	else
1516		error = flock_lock_file_wait(filp, lock);
1517
1518 out_free:
1519	if (list_empty(&lock->fl_link)) {
1520		locks_free_lock(lock);
1521	}
1522
1523 out_putf:
1524	fput(filp);
1525 out:
1526	return error;
1527}
1528
1529/* Report the first existing lock that would conflict with l.
1530 * This implements the F_GETLK command of fcntl().
1531 */
1532int fcntl_getlk(struct file *filp, struct flock __user *l)
1533{
1534	struct file_lock *fl, file_lock;
1535	struct flock flock;
1536	int error;
1537
1538	error = -EFAULT;
1539	if (copy_from_user(&flock, l, sizeof(flock)))
1540		goto out;
1541	error = -EINVAL;
1542	if ((flock.l_type != F_RDLCK) && (flock.l_type != F_WRLCK))
1543		goto out;
1544
1545	error = flock_to_posix_lock(filp, &file_lock, &flock);
1546	if (error)
1547		goto out;
1548
1549	if (filp->f_op && filp->f_op->lock) {
1550		error = filp->f_op->lock(filp, F_GETLK, &file_lock);
1551		if (error < 0)
1552			goto out;
1553		else
1554		  fl = (file_lock.fl_type == F_UNLCK ? NULL : &file_lock);
1555	} else {
1556		fl = posix_test_lock(filp, &file_lock);
1557	}
1558 
1559	flock.l_type = F_UNLCK;
1560	if (fl != NULL) {
1561		flock.l_pid = fl->fl_pid;
1562#if BITS_PER_LONG == 32
1563		/*
1564		 * Make sure we can represent the posix lock via
1565		 * legacy 32bit flock.
1566		 */
1567		error = -EOVERFLOW;
1568		if (fl->fl_start > OFFT_OFFSET_MAX)
1569			goto out;
1570		if ((fl->fl_end != OFFSET_MAX)
1571		    && (fl->fl_end > OFFT_OFFSET_MAX))
1572			goto out;
1573#endif
1574		flock.l_start = fl->fl_start;
1575		flock.l_len = fl->fl_end == OFFSET_MAX ? 0 :
1576			fl->fl_end - fl->fl_start + 1;
1577		flock.l_whence = 0;
1578		flock.l_type = fl->fl_type;
1579	}
1580	error = -EFAULT;
1581	if (!copy_to_user(l, &flock, sizeof(flock)))
1582		error = 0;
1583out:
1584	return error;
1585}
1586
1587/* Apply the lock described by l to an open file descriptor.
1588 * This implements both the F_SETLK and F_SETLKW commands of fcntl().
1589 */
1590int fcntl_setlk(struct file *filp, unsigned int cmd, struct flock __user *l)
1591{
1592	struct file_lock *file_lock = locks_alloc_lock();
1593	struct flock flock;
1594	struct inode *inode;
1595	int error;
1596
1597	if (file_lock == NULL)
1598		return -ENOLCK;
1599
1600	/*
1601	 * This might block, so we do it before checking the inode.
1602	 */
1603	error = -EFAULT;
1604	if (copy_from_user(&flock, l, sizeof(flock)))
1605		goto out;
1606
1607	inode = filp->f_dentry->d_inode;
1608
1609	/* Don't allow mandatory locks on files that may be memory mapped
1610	 * and shared.
1611	 */
1612	if (IS_MANDLOCK(inode) &&
1613	    (inode->i_mode & (S_ISGID | S_IXGRP)) == S_ISGID &&
1614	    mapping_writably_mapped(filp->f_mapping)) {
1615		error = -EAGAIN;
1616		goto out;
1617	}
1618
1619	error = flock_to_posix_lock(filp, file_lock, &flock);
1620	if (error)
1621		goto out;
1622	if (cmd == F_SETLKW) {
1623		file_lock->fl_flags |= FL_SLEEP;
1624	}
1625	
1626	error = -EBADF;
1627	switch (flock.l_type) {
1628	case F_RDLCK:
1629		if (!(filp->f_mode & FMODE_READ))
1630			goto out;
1631		break;
1632	case F_WRLCK:
1633		if (!(filp->f_mode & FMODE_WRITE))
1634			goto out;
1635		break;
1636	case F_UNLCK:
1637		break;
1638	default:
1639		error = -EINVAL;
1640		goto out;
1641	}
1642
1643	error = security_file_lock(filp, file_lock->fl_type);
1644	if (error)
1645		goto out;
1646
1647	if (filp->f_op && filp->f_op->lock != NULL) {
1648		error = filp->f_op->lock(filp, cmd, file_lock);
1649		goto out;
1650	}
1651
1652	for (;;) {
1653		error = __posix_lock_file(inode, file_lock);
1654		if ((error != -EAGAIN) || (cmd == F_SETLK))
1655			break;
1656		error = wait_event_interruptible(file_lock->fl_wait,
1657				!file_lock->fl_next);
1658		if (!error)
1659			continue;
1660
1661		locks_delete_block(file_lock);
1662		break;
1663	}
1664
1665 out:
1666	locks_free_lock(file_lock);
1667	return error;
1668}
1669
1670#if BITS_PER_LONG == 32
1671/* Report the first existing lock that would conflict with l.
1672 * This implements the F_GETLK command of fcntl().
1673 */
1674int fcntl_getlk64(struct file *filp, struct flock64 __user *l)
1675{
1676	struct file_lock *fl, file_lock;
1677	struct flock64 flock;
1678	int error;
1679
1680	error = -EFAULT;
1681	if (copy_from_user(&flock, l, sizeof(flock)))
1682		goto out;
1683	error = -EINVAL;
1684	if ((flock.l_type != F_RDLCK) && (flock.l_type != F_WRLCK))
1685		goto out;
1686
1687	error = flock64_to_posix_lock(filp, &file_lock, &flock);
1688	if (error)
1689		goto out;
1690
1691	if (filp->f_op && filp->f_op->lock) {
1692		error = filp->f_op->lock(filp, F_GETLK, &file_lock);
1693		if (error < 0)
1694			goto out;
1695		else
1696		  fl = (file_lock.fl_type == F_UNLCK ? NULL : &file_lock);
1697	} else {
1698		fl = posix_test_lock(filp, &file_lock);
1699	}
1700 
1701	flock.l_type = F_UNLCK;
1702	if (fl != NULL) {
1703		flock.l_pid = fl->fl_pid;
1704		flock.l_start = fl->fl_start;
1705		flock.l_len = fl->fl_end == OFFSET_MAX ? 0 :
1706			fl->fl_end - fl->fl_start + 1;
1707		flock.l_whence = 0;
1708		flock.l_type = fl->fl_type;
1709	}
1710	error = -EFAULT;
1711	if (!copy_to_user(l, &flock, sizeof(flock)))
1712		error = 0;
1713  
1714out:
1715	return error;
1716}
1717
1718/* Apply the lock described by l to an open file descriptor.
1719 * This implements both the F_SETLK and F_SETLKW commands of fcntl().
1720 */
1721int fcntl_setlk64(struct file *filp, unsigned int cmd, struct flock64 __user *l)
1722{
1723	struct file_lock *file_lock = locks_alloc_lock();
1724	struct flock64 flock;
1725	struct inode *inode;
1726	int error;
1727
1728	if (file_lock == NULL)
1729		return -ENOLCK;
1730
1731	/*
1732	 * This might block, so we do it before checking the inode.
1733	 */
1734	error = -EFAULT;
1735	if (copy_from_user(&flock, l, sizeof(flock)))
1736		goto out;
1737
1738	inode = filp->f_dentry->d_inode;
1739
1740	/* Don't allow mandatory locks on files that may be memory mapped
1741	 * and shared.
1742	 */
1743	if (IS_MANDLOCK(inode) &&
1744	    (inode->i_mode & (S_ISGID | S_IXGRP)) == S_ISGID &&
1745	    mapping_writably_mapped(filp->f_mapping)) {
1746		error = -EAGAIN;
1747		goto out;
1748	}
1749
1750	error = flock64_to_posix_lock(filp, file_lock, &flock);
1751	if (error)
1752		goto out;
1753	if (cmd == F_SETLKW64) {
1754		file_lock->fl_flags |= FL_SLEEP;
1755	}
1756	
1757	error = -EBADF;
1758	switch (flock.l_type) {
1759	case F_RDLCK:
1760		if (!(filp->f_mode & FMODE_READ))
1761			goto out;
1762		break;
1763	case F_WRLCK:
1764		if (!(filp->f_mode & FMODE_WRITE))
1765			goto out;
1766		break;
1767	case F_UNLCK:
1768		break;
1769	default:
1770		error = -EINVAL;
1771		goto out;
1772	}
1773
1774	error = security_file_lock(filp, file_lock->fl_type);
1775	if (error)
1776		goto out;
1777
1778	if (filp->f_op && filp->f_op->lock != NULL) {
1779		error = filp->f_op->lock(filp, cmd, file_lock);
1780		goto out;
1781	}
1782
1783	for (;;) {
1784		error = __posix_lock_file(inode, file_lock);
1785		if ((error != -EAGAIN) || (cmd == F_SETLK64))
1786			break;
1787		error = wait_event_interruptible(file_lock->fl_wait,
1788				!file_lock->fl_next);
1789		if (!error)
1790			continue;
1791
1792		locks_delete_block(file_lock);
1793		break;
1794	}
1795
1796out:
1797	locks_free_lock(file_lock);
1798	return error;
1799}
1800#endif /* BITS_PER_LONG == 32 */
1801
1802/*
1803 * This function is called when the file is being removed
1804 * from the task's fd array.  POSIX locks belonging to this task
1805 * are deleted at this time.
1806 */
1807void locks_remove_posix(struct file *filp, fl_owner_t owner)
1808{
1809	struct file_lock lock, **before;
1810
1811	/*
1812	 * If there are no locks held on this file, we don't need to call
1813	 * posix_lock_file().  Another process could be setting a lock on this
1814	 * file at the same time, but we wouldn't remove that lock anyway.
1815	 */
1816	before = &filp->f_dentry->d_inode->i_flock;
1817	if (*before == NULL)
1818		return;
1819
1820	lock.fl_type = F_UNLCK;
1821	lock.fl_flags = FL_POSIX;
1822	lock.fl_start = 0;
1823	lock.fl_end = OFFSET_MAX;
1824	lock.fl_owner = owner;
1825	lock.fl_pid = current->tgid;
1826	lock.fl_file = filp;
1827	lock.fl_ops = NULL;
1828	lock.fl_lmops = NULL;
1829
1830	if (filp->f_op && filp->f_op->lock != NULL) {
1831		filp->f_op->lock(filp, F_SETLK, &lock);
1832		goto out;
1833	}
1834
1835	/* Can't use posix_lock_file here; we need to remove it no matter
1836	 * which pid we have.
1837	 */
1838	lock_kernel();
1839	while (*before != NULL) {
1840		struct file_lock *fl = *before;
1841		if (IS_POSIX(fl) && posix_same_owner(fl, &lock)) {
1842			locks_delete_lock(before);
1843			continue;
1844		}
1845		before = &fl->fl_next;
1846	}
1847	unlock_kernel();
1848out:
1849	if (lock.fl_ops && lock.fl_ops->fl_release_private)
1850		lock.fl_ops->fl_release_private(&lock);
1851}
1852
1853EXPORT_SYMBOL(locks_remove_posix);
1854
1855/*
1856 * This function is called on the last close of an open file.
1857 */
1858void locks_remove_flock(struct file *filp)
1859{
1860	struct inode * inode = filp->f_dentry->d_inode; 
1861	struct file_lock *fl;
1862	struct file_lock **before;
1863
1864	if (!inode->i_flock)
1865		return;
1866
1867	if (filp->f_op && filp->f_op->flock) {
1868		struct file_lock fl = {
1869			.fl_pid = current->tgid,
1870			.fl_file = filp,
1871			.fl_flags = FL_FLOCK,
1872			.fl_type = F_UNLCK,
1873			.fl_end = OFFSET_MAX,
1874		};
1875		filp->f_op->flock(filp, F_SETLKW, &fl);
1876	}
1877
1878	lock_kernel();
1879	before = &inode->i_flock;
1880
1881	while ((fl = *before) != NULL) {
1882		if (fl->fl_file == filp) {
1883			/*
1884			 * We might have a POSIX lock that was created at the same time
1885			 * the filp was closed for the last time. Just remove that too,
1886			 * regardless of ownership, since nobody can own it.
1887			 */
1888			if (IS_FLOCK(fl) || IS_POSIX(fl)) {
1889				locks_delete_lock(before);
1890				continue;
1891			}
1892			if (IS_LEASE(fl)) {
1893				lease_modify(before, F_UNLCK);
1894				continue;
1895			}
1896			/* What? */
1897			BUG();
1898 		}
1899		before = &fl->fl_next;
1900	}
1901	unlock_kernel();
1902}
1903
1904/**
1905 *	posix_block_lock - blocks waiting for a file lock
1906 *	@blocker: the lock which is blocking
1907 *	@waiter: the lock which conflicts and has to wait
1908 *
1909 * lockd needs to block waiting for locks.
1910 */
1911void
1912posix_block_lock(struct file_lock *blocker, struct file_lock *waiter)
1913{
1914	locks_insert_block(blocker, waiter);
1915}
1916
1917EXPORT_SYMBOL(posix_block_lock);
1918
1919/**
1920 *	posix_unblock_lock - stop waiting for a file lock
1921 *      @filp:   how the file was opened
1922 *	@waiter: the lock which was waiting
1923 *
1924 *	lockd needs to block waiting for locks.
1925 */
1926void
1927posix_unblock_lock(struct file *filp, struct file_lock *waiter)
1928{
1929	/* 
1930	 * A remote machine may cancel the lock request after it's been
1931	 * granted locally.  If that happens, we need to delete the lock.
1932	 */
1933	lock_kernel();
1934	if (waiter->fl_next) {
1935		__locks_delete_block(waiter);
1936		unlock_kernel();
1937	} else {
1938		unlock_kernel();
1939		waiter->fl_type = F_UNLCK;
1940		posix_lock_file(filp, waiter);
1941	}
1942}
1943
1944EXPORT_SYMBOL(posix_unblock_lock);
1945
1946static void lock_get_status(char* out, struct file_lock *fl, int id, char *pfx)
1947{
1948	struct inode *inode = NULL;
1949
1950	if (fl->fl_file != NULL)
1951		inode = fl->fl_file->f_dentry->d_inode;
1952
1953	out += sprintf(out, "%d:%s ", id, pfx);
1954	if (IS_POSIX(fl)) {
1955		out += sprintf(out, "%6s %s ",
1956			     (fl->fl_flags & FL_ACCESS) ? "ACCESS" : "POSIX ",
1957			     (inode == NULL) ? "*NOINODE*" :
1958			     (IS_MANDLOCK(inode) &&
1959			      (inode->i_mode & (S_IXGRP | S_ISGID)) == S_ISGID) ?
1960			     "MANDATORY" : "ADVISORY ");
1961	} else if (IS_FLOCK(fl)) {
1962		if (fl->fl_type & LOCK_MAND) {
1963			out += sprintf(out, "FLOCK  MSNFS     ");
1964		} else {
1965			out += sprintf(out, "FLOCK  ADVISORY  ");
1966		}
1967	} else if (IS_LEASE(fl)) {
1968		out += sprintf(out, "LEASE  ");
1969		if (fl->fl_type & F_INPROGRESS)
1970			out += sprintf(out, "BREAKING  ");
1971		else if (fl->fl_file)
1972			out += sprintf(out, "ACTIVE    ");
1973		else
1974			out += sprintf(out, "BREAKER   ");
1975	} else {
1976		out += sprintf(out, "UNKNOWN UNKNOWN  ");
1977	}
1978	if (fl->fl_type & LOCK_MAND) {
1979		out += sprintf(out, "%s ",
1980			       (fl->fl_type & LOCK_READ)
1981			       ? (fl->fl_type & LOCK_WRITE) ? "RW   " : "READ "
1982			       : (fl->fl_type & LOCK_WRITE) …