linux/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/filesystems/mandatory-locking.txt' for details.
  64 *  Andy Walker (andy@lysaker.kvaerner.no), April 06, 1996.
  65 *
  66 *  Don't allow mandatory locks on mmap()'ed files. Added simple functions to
  67 *  check if a file has mandatory locks, used by mmap(), open() and creat() to
  68 *  see if system call should be rejected. Ref. HP-UX/SunOS/Solaris Reference
  69 *  Manual, Section 2.
  70 *  Andy Walker (andy@lysaker.kvaerner.no), April 09, 1996.
  71 *
  72 *  Tidied up block list handling. Added '/proc/locks' interface.
  73 *  Andy Walker (andy@lysaker.kvaerner.no), April 24, 1996.
  74 *
  75 *  Fixed deadlock condition for pathological code that mixes calls to
  76 *  flock() and fcntl().
  77 *  Andy Walker (andy@lysaker.kvaerner.no), April 29, 1996.
  78 *
  79 *  Allow only one type of locking scheme (FL_POSIX or FL_FLOCK) to be in use
  80 *  for a given file at a time. Changed the CONFIG_LOCK_MANDATORY scheme to
  81 *  guarantee sensible behaviour in the case where file system modules might
  82 *  be compiled with different options than the kernel itself.
  83 *  Andy Walker (andy@lysaker.kvaerner.no), May 15, 1996.
  84 *
  85 *  Added a couple of missing wake_up() calls. Thanks to Thomas Meckel
  86 *  (Thomas.Meckel@mni.fh-giessen.de) for spotting this.
  87 *  Andy Walker (andy@lysaker.kvaerner.no), May 15, 1996.
  88 *
  89 *  Changed FL_POSIX locks to use the block list in the same way as FL_FLOCK
  90 *  locks. Changed process synchronisation to avoid dereferencing locks that
  91 *  have already been freed.
  92 *  Andy Walker (andy@lysaker.kvaerner.no), Sep 21, 1996.
  93 *
  94 *  Made the block list a circular list to minimise searching in the list.
  95 *  Andy Walker (andy@lysaker.kvaerner.no), Sep 25, 1996.
  96 *
  97 *  Made mandatory locking a mount option. Default is not to allow mandatory
  98 *  locking.
  99 *  Andy Walker (andy@lysaker.kvaerner.no), Oct 04, 1996.
 100 *
 101 *  Some adaptations for NFS support.
 102 *  Olaf Kirch (okir@monad.swb.de), Dec 1996,
 103 *
 104 *  Fixed /proc/locks interface so that we can't overrun the buffer we are handed.
 105 *  Andy Walker (andy@lysaker.kvaerner.no), May 12, 1997.
 106 *
 107 *  Use slab allocator instead of kmalloc/kfree.
 108 *  Use generic list implementation from <linux/list.h>.
 109 *  Sped up posix_locks_deadlock by only considering blocked locks.
 110 *  Matthew Wilcox <willy@debian.org>, March, 2000.
 111 *
 112 *  Leases and LOCK_MAND
 113 *  Matthew Wilcox <willy@debian.org>, June, 2000.
 114 *  Stephen Rothwell <sfr@canb.auug.org.au>, June, 2000.
 115 */
 116
 117#include <linux/capability.h>
 118#include <linux/file.h>
 119#include <linux/fdtable.h>
 120#include <linux/fs.h>
 121#include <linux/init.h>
 122#include <linux/module.h>
 123#include <linux/security.h>
 124#include <linux/slab.h>
 125#include <linux/syscalls.h>
 126#include <linux/time.h>
 127#include <linux/rcupdate.h>
 128#include <linux/pid_namespace.h>
 129#include <linux/hashtable.h>
 130#include <linux/percpu.h>
 131#include <linux/lglock.h>
 132
 133#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
 139static bool lease_breaking(struct file_lock *fl)
 140{
 141        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;
 151}
 152
 153int 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
 159/*
 160 * 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.
 164 */
 165DEFINE_STATIC_LGLOCK(file_lock_lglock);
 166static DEFINE_PER_CPU(struct hlist_head, file_lock_list);
 167
 168/*
 169 * The blocked_hash is used to find POSIX lock loops for deadlock detection.
 170 * It is protected by blocked_lock_lock.
 171 *
 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.
 178 */
 179#define BLOCKED_HASH_BITS       7
 180static DEFINE_HASHTABLE(blocked_hash, BLOCKED_HASH_BITS);
 181
 182/*
 183 * This lock protects the blocked_hash. Generally, if you're accessing it, you
 184 * want to be holding this lock.
 185 *
 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 */
 199static DEFINE_SPINLOCK(blocked_lock_lock);
 200
 201static struct kmem_cache *filelock_cache __read_mostly;
 202
 203static void locks_init_lock_heads(struct file_lock *fl)
 204{
 205        INIT_HLIST_NODE(&fl->fl_link);
 206        INIT_LIST_HEAD(&fl->fl_block);
 207        init_waitqueue_head(&fl->fl_wait);
 208}
 209
 210/* Allocate an empty lock structure. */
 211struct file_lock *locks_alloc_lock(void)
 212{
 213        struct file_lock *fl = kmem_cache_zalloc(filelock_cache, GFP_KERNEL);
 214
 215        if (fl)
 216                locks_init_lock_heads(fl);
 217
 218        return fl;
 219}
 220EXPORT_SYMBOL_GPL(locks_alloc_lock);
 221
 222void locks_release_private(struct file_lock *fl)
 223{
 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        }
 229        fl->fl_lmops = NULL;
 230
 231}
 232EXPORT_SYMBOL_GPL(locks_release_private);
 233
 234/* Free a lock which is not in use. */
 235void locks_free_lock(struct file_lock *fl)
 236{
 237        BUG_ON(waitqueue_active(&fl->fl_wait));
 238        BUG_ON(!list_empty(&fl->fl_block));
 239        BUG_ON(!hlist_unhashed(&fl->fl_link));
 240
 241        locks_release_private(fl);
 242        kmem_cache_free(filelock_cache, fl);
 243}
 244EXPORT_SYMBOL(locks_free_lock);
 245
 246void locks_init_lock(struct file_lock *fl)
 247{
 248        memset(fl, 0, sizeof(struct file_lock));
 249        locks_init_lock_heads(fl);
 250}
 251
 252EXPORT_SYMBOL(locks_init_lock);
 253
 254static 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        }
 261        if (fl->fl_lmops)
 262                new->fl_lmops = fl->fl_lmops;
 263}
 264
 265/*
 266 * Initialize a new lock from an existing file_lock structure.
 267 */
 268void __locks_copy_lock(struct file_lock *new, const struct file_lock *fl)
 269{
 270        new->fl_owner = fl->fl_owner;
 271        new->fl_pid = fl->fl_pid;
 272        new->fl_file = NULL;
 273        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;
 277        new->fl_ops = NULL;
 278        new->fl_lmops = NULL;
 279}
 280EXPORT_SYMBOL(__locks_copy_lock);
 281
 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;
 288        new->fl_ops = fl->fl_ops;
 289        new->fl_lmops = fl->fl_lmops;
 290
 291        locks_copy_private(new, fl);
 292}
 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
 333static int assign_type(struct file_lock *fl, long type)
 334{
 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) {
 356        case SEEK_SET:
 357                start = 0;
 358                break;
 359        case SEEK_CUR:
 360                start = filp->f_pos;
 361                break;
 362        case SEEK_END:
 363                start = i_size_read(file_inode(filp));
 364                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;
 372        if (start < 0)
 373                return -EINVAL;
 374        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        }
 385        fl->fl_start = start;   /* we record the absolute position */
 386        if (fl->fl_end < fl->fl_start)
 387                return -EOVERFLOW;
 388        
 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) {
 406        case SEEK_SET:
 407                start = 0;
 408                break;
 409        case SEEK_CUR:
 410                start = filp->f_pos;
 411                break;
 412        case SEEK_END:
 413                start = i_size_read(file_inode(filp));
 414                break;
 415        default:
 416                return -EINVAL;
 417        }
 418
 419        start += l->l_start;
 420        if (start < 0)
 421                return -EINVAL;
 422        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        }
 431        fl->fl_start = start;   /* we record the absolute position */
 432        if (fl->fl_end < fl->fl_start)
 433                return -EOVERFLOW;
 434        
 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
 442        return assign_type(fl, l->l_type);
 443}
 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
 452static const struct lock_manager_operations lease_manager_ops = {
 453        .lm_break = lease_break_callback,
 454        .lm_change = lease_modify,
 455};
 456
 457/*
 458 * Initialize a lease, use the default lock manager operations
 459 */
 460static int lease_init(struct file *filp, long type, struct file_lock *fl)
 461 {
 462        if (assign_type(fl, type) != 0)
 463                return -EINVAL;
 464
 465        fl->fl_owner = current->files;
 466        fl->fl_pid = current->tgid;
 467
 468        fl->fl_file = filp;
 469        fl->fl_flags = FL_LEASE;
 470        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 */
 478static struct file_lock *lease_alloc(struct file *filp, long type)
 479{
 480        struct file_lock *fl = locks_alloc_lock();
 481        int error = -ENOMEM;
 482
 483        if (fl == NULL)
 484                return ERR_PTR(error);
 485
 486        error = lease_init(filp, type, fl);
 487        if (error) {
 488                locks_free_lock(fl);
 489                return ERR_PTR(error);
 490        }
 491        return fl;
 492}
 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 */
 505static int posix_same_owner(struct file_lock *fl1, struct file_lock *fl2)
 506{
 507        if (fl1->fl_lmops && fl1->fl_lmops->lm_compare_owner)
 508                return fl2->fl_lmops == fl1->fl_lmops &&
 509                        fl1->fl_lmops->lm_compare_owner(fl1, fl2);
 510        return fl1->fl_owner == fl2->fl_owner;
 511}
 512
 513/* Must be called with the i_lock held! */
 514static inline void
 515locks_insert_global_locks(struct file_lock *fl)
 516{
 517        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);
 521}
 522
 523/* Must be called with the i_lock held! */
 524static inline void
 525locks_delete_global_locks(struct file_lock *fl)
 526{
 527        /*
 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);
 535        hlist_del_init(&fl->fl_link);
 536        lg_local_unlock_cpu(&file_lock_lglock, fl->fl_link_cpu);
 537}
 538
 539static 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
 547static inline void
 548locks_insert_global_blocked(struct file_lock *waiter)
 549{
 550        hash_add(blocked_hash, &waiter->fl_link, posix_owner_key(waiter));
 551}
 552
 553static inline void
 554locks_delete_global_blocked(struct file_lock *waiter)
 555{
 556        hash_del(&waiter->fl_link);
 557}
 558
 559/* Remove waiter from blocker's block list.
 560 * When blocker ends up pointing to itself then the list is empty.
 561 *
 562 * Must be called with blocked_lock_lock held.
 563 */
 564static void __locks_delete_block(struct file_lock *waiter)
 565{
 566        locks_delete_global_blocked(waiter);
 567        list_del_init(&waiter->fl_block);
 568        waiter->fl_next = NULL;
 569}
 570
 571static void locks_delete_block(struct file_lock *waiter)
 572{
 573        spin_lock(&blocked_lock_lock);
 574        __locks_delete_block(waiter);
 575        spin_unlock(&blocked_lock_lock);
 576}
 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.
 582 *
 583 * Must be called with both the i_lock and blocked_lock_lock held. The fl_block
 584 * list itself is protected by the file_lock_list, but by ensuring that the
 585 * i_lock is also held on insertions we can avoid taking the blocked_lock_lock
 586 * in some cases when we see that the fl_block list is empty.
 587 */
 588static void __locks_insert_block(struct file_lock *blocker,
 589                                        struct file_lock *waiter)
 590{
 591        BUG_ON(!list_empty(&waiter->fl_block));
 592        waiter->fl_next = blocker;
 593        list_add_tail(&waiter->fl_block, &blocker->fl_block);
 594        if (IS_POSIX(blocker))
 595                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{
 602        spin_lock(&blocked_lock_lock);
 603        __locks_insert_block(blocker, waiter);
 604        spin_unlock(&blocked_lock_lock);
 605}
 606
 607/*
 608 * Wake up processes blocked waiting for blocker.
 609 *
 610 * Must be called with the inode->i_lock held!
 611 */
 612static void locks_wake_up_blocks(struct file_lock *blocker)
 613{
 614        /*
 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()
 619         * after acquiring the blocked_lock_lock.
 620         */
 621        if (list_empty(&blocker->fl_block))
 622                return;
 623
 624        spin_lock(&blocked_lock_lock);
 625        while (!list_empty(&blocker->fl_block)) {
 626                struct file_lock *waiter;
 627
 628                waiter = list_first_entry(&blocker->fl_block,
 629                                struct file_lock, fl_block);
 630                __locks_delete_block(waiter);
 631                if (waiter->fl_lmops && waiter->fl_lmops->lm_notify)
 632                        waiter->fl_lmops->lm_notify(waiter);
 633                else
 634                        wake_up(&waiter->fl_wait);
 635        }
 636        spin_unlock(&blocked_lock_lock);
 637}
 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.
 641 *
 642 * Must be called with the i_lock held!
 643 */
 644static void locks_insert_lock(struct file_lock **pos, struct file_lock *fl)
 645{
 646        fl->fl_nspid = get_pid(task_tgid(current));
 647
 648        /* insert into file's list */
 649        fl->fl_next = *pos;
 650        *pos = fl;
 651
 652        locks_insert_global_locks(fl);
 653}
 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.
 660 *
 661 * Must be called with the i_lock held!
 662 */
 663static void locks_delete_lock(struct file_lock **thisfl_p)
 664{
 665        struct file_lock *fl = *thisfl_p;
 666
 667        locks_delete_global_locks(fl);
 668
 669        *thisfl_p = fl->fl_next;
 670        fl->fl_next = NULL;
 671
 672        if (fl->fl_nspid) {
 673                put_pid(fl->fl_nspid);
 674                fl->fl_nspid = NULL;
 675        }
 676
 677        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
 727void
 728posix_test_lock(struct file *filp, struct file_lock *fl)
 729{
 730        struct file_lock *cfl;
 731        struct inode *inode = file_inode(filp);
 732
 733        spin_lock(&inode->i_lock);
 734        for (cfl = file_inode(filp)->i_flock; cfl; cfl = cfl->fl_next) {
 735                if (!IS_POSIX(cfl))
 736                        continue;
 737                if (posix_locks_conflict(fl, cfl))
 738                        break;
 739        }
 740        if (cfl) {
 741                __locks_copy_lock(fl, cfl);
 742                if (cfl->fl_nspid)
 743                        fl->fl_pid = pid_vnr(cfl->fl_nspid);
 744        } else
 745                fl->fl_type = F_UNLCK;
 746        spin_unlock(&inode->i_lock);
 747        return;
 748}
 749EXPORT_SYMBOL(posix_test_lock);
 750
 751/*
 752 * Deadlock detection:
 753 *
 754 * We attempt to detect deadlocks that are due purely to posix file
 755 * locks.
 756 *
 757 * 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.
 764 *
 765 * 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.
 774 */
 775
 776#define MAX_DEADLK_ITERATIONS 10
 777
 778/* 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
 783        hash_for_each_possible(blocked_hash, fl, fl_link, posix_owner_key(block_fl)) {
 784                if (posix_same_owner(fl, block_fl))
 785                        return fl->fl_next;
 786        }
 787        return NULL;
 788}
 789
 790/* Must be called with the blocked_lock_lock held! */
 791static int posix_locks_deadlock(struct file_lock *caller_fl,
 792                                struct file_lock *block_fl)
 793{
 794        int i = 0;
 795
 796        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;
 801        }
 802        return 0;
 803}
 804
 805/* Try to create a FLOCK lock on filp. We always insert new FLOCK locks
 806 * after any leases, but before any posix locks.
 807 *
 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.
 811 */
 812static int flock_lock_file(struct file *filp, struct file_lock *request)
 813{
 814        struct file_lock *new_fl = NULL;
 815        struct file_lock **before;
 816        struct inode * inode = file_inode(filp);
 817        int error = 0;
 818        int found = 0;
 819
 820        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
 826        spin_lock(&inode->i_lock);
 827        if (request->fl_flags & FL_ACCESS)
 828                goto find_conflict;
 829
 830        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;
 838                if (request->fl_type == fl->fl_type)
 839                        goto out;
 840                found = 1;
 841                locks_delete_lock(before);
 842                break;
 843        }
 844
 845        if (request->fl_type == F_UNLCK) {
 846                if ((request->fl_flags & FL_EXISTS) && !found)
 847                        error = -ENOENT;
 848                goto out;
 849        }
 850
 851        /*
 852         * If a higher-priority process was blocked on the old file lock,
 853         * give it the opportunity to lock the file.
 854         */
 855        if (found) {
 856                spin_unlock(&inode->i_lock);
 857                cond_resched();
 858                spin_lock(&inode->i_lock);
 859        }
 860
 861find_conflict:
 862        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;
 868                if (!flock_locks_conflict(request, fl))
 869                        continue;
 870                error = -EAGAIN;
 871                if (!(request->fl_flags & FL_SLEEP))
 872                        goto out;
 873                error = FILE_LOCK_DEFERRED;
 874                locks_insert_block(fl, request);
 875                goto out;
 876        }
 877        if (request->fl_flags & FL_ACCESS)
 878                goto out;
 879        locks_copy_lock(new_fl, request);
 880        locks_insert_lock(before, new_fl);
 881        new_fl = NULL;
 882        error = 0;
 883
 884out:
 885        spin_unlock(&inode->i_lock);
 886        if (new_fl)
 887                locks_free_lock(new_fl);
 888        return error;
 889}
 890
 891static int __posix_lock_file(struct inode *inode, struct file_lock *request, struct file_lock *conflock)
 892{
 893        struct file_lock *fl;
 894        struct file_lock *new_fl = NULL;
 895        struct file_lock *new_fl2 = NULL;
 896        struct file_lock *left = NULL;
 897        struct file_lock *right = NULL;
 898        struct file_lock **before;
 899        int error;
 900        bool added = false;
 901
 902        /*
 903         * We may need two file_lock structures for this operation,
 904         * so we get them in advance to avoid races.
 905         *
 906         * In some cases we can be sure, that no new locks will be needed
 907         */
 908        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        }
 914
 915        spin_lock(&inode->i_lock);
 916        /*
 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
 919         * blocker's list of waiters and the global blocked_hash.
 920         */
 921        if (request->fl_type != F_UNLCK) {
 922                for_each_lock(inode, before) {
 923                        fl = *before;
 924                        if (!IS_POSIX(fl))
 925                                continue;
 926                        if (!posix_locks_conflict(request, fl))
 927                                continue;
 928                        if (conflock)
 929                                __locks_copy_lock(conflock, fl);
 930                        error = -EAGAIN;
 931                        if (!(request->fl_flags & FL_SLEEP))
 932                                goto out;
 933                        /*
 934                         * Deadlock detection and insertion into the blocked
 935                         * locks list must be done while holding the same lock!
 936                         */
 937                        error = -EDEADLK;
 938                        spin_lock(&blocked_lock_lock);
 939                        if (likely(!posix_locks_deadlock(request, fl))) {
 940                                error = FILE_LOCK_DEFERRED;
 941                                __locks_insert_block(fl, request);
 942                        }
 943                        spin_unlock(&blocked_lock_lock);
 944                        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
 953        /*
 954         * 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
 965        /* Process locks with this owner. */
 966        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) {
 970                        /* 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                         */
 974                        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                         */
 979                        if (fl->fl_start - 1 > request->fl_end)
 980                                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;
1000                        added = true;
1001                }
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)
1011                                added = true;
1012                        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;
1038                                locks_release_private(fl);
1039                                locks_copy_private(fl, request);
1040                                request = fl;
1041                                added = true;
1042                        }
1043                }
1044                /* Go on to next lock.
1045                 */
1046        next_lock:
1047                before = &fl->fl_next;
1048        }
1049
1050        /*
1051         * 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.
1054         */
1055        error = -ENOLCK; /* "no luck" */
1056        if (right && left == right && !new_fl2)
1057                goto out;
1058
1059        error = 0;
1060        if (!added) {
1061                if (request->fl_type == F_UNLCK) {
1062                        if (request->fl_flags & FL_EXISTS)
1063                                error = -ENOENT;
1064                        goto out;
1065                }
1066
1067                if (!new_fl) {
1068                        error = -ENOLCK;
1069                        goto out;
1070                }
1071                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:
1093        spin_unlock(&inode->i_lock);
1094        /*
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
1108 * @conflock: Place to return a copy of the conflicting lock, if found.
1109 *
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
1113 *
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.
1117 */
1118int posix_lock_file(struct file *filp, struct file_lock *fl,
1119                        struct file_lock *conflock)
1120{
1121        return __posix_lock_file(file_inode(filp), fl, conflock);
1122}
1123EXPORT_SYMBOL(posix_lock_file);
1124
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 (;;) {
1139                error = posix_lock_file(filp, fl, NULL);
1140                if (error != FILE_LOCK_DEFERRED)
1141                        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         */
1168        spin_lock(&inode->i_lock);
1169        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        }
1175        spin_unlock(&inode->i_lock);
1176        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 (;;) {
1211                error = __posix_lock_file(inode, &fl, NULL);
1212                if (error != FILE_LOCK_DEFERRED)
1213                        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                         */
1220                        if (__mandatory_lock(inode))
1221                                continue;
1222                }
1223
1224                locks_delete_block(&fl);
1225                break;
1226        }
1227
1228        return error;
1229}
1230
1231EXPORT_SYMBOL(locks_mandatory_area);
1232
1233static 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
1244/* 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;
1252        lease_clear_pending(fl, arg);
1253        locks_wake_up_blocks(fl);
1254        if (arg == F_UNLCK) {
1255                struct file *filp = fl->fl_file;
1256
1257                f_delown(filp);
1258                filp->f_owner.signum = 0;
1259                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                }
1264                locks_delete_lock(before);
1265        }
1266        return 0;
1267}
1268
1269EXPORT_SYMBOL(lease_modify);
1270
1271static 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
1279static void time_out_leases(struct inode *inode)
1280{
1281        struct file_lock **before;
1282        struct file_lock *fl;
1283
1284        before = &inode->i_flock;
1285        while ((fl = *before) && IS_LEASE(fl) && lease_breaking(fl)) {
1286                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);
1290                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 *
1300 *      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
1303 *      specified %O_NONBLOCK to your open().
1304 */
1305int __break_lease(struct inode *inode, unsigned int mode)
1306{
1307        int error = 0;
1308        struct file_lock *new_fl, *flock;
1309        struct file_lock *fl;
1310        unsigned long break_time;
1311        int i_have_this_lease = 0;
1312        int want_write = (mode & O_ACCMODE) != O_RDONLY;
1313
1314        new_fl = lease_alloc(NULL, want_write ? F_WRLCK : F_RDLCK);
1315        if (IS_ERR(new_fl))
1316                return PTR_ERR(new_fl);
1317
1318        spin_lock(&inode->i_lock);
1319
1320        time_out_leases(inode);
1321
1322        flock = inode->i_flock;
1323        if ((flock == NULL) || !IS_LEASE(flock))
1324                goto out;
1325
1326        if (!locks_conflict(flock, new_fl))
1327                goto out;
1328
1329        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
1333        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) {
1341                if (want_write) {
1342                        if (fl->fl_flags & FL_UNLOCK_PENDING)
1343                                continue;
1344                        fl->fl_flags |= FL_UNLOCK_PENDING;
1345                        fl->fl_break_time = break_time;
1346                } else {
1347                        if (lease_breaking(flock))
1348                                continue;
1349                        fl->fl_flags |= FL_DOWNGRADE_PENDING;
1350                        fl->fl_downgrade_time = break_time;
1351                }
1352                fl->fl_lmops->lm_break(fl);
1353        }
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        }
1367        locks_insert_block(flock, new_fl);
1368        spin_unlock(&inode->i_lock);
1369        error = wait_event_interruptible_timeout(new_fl->fl_wait,
1370                                                !new_fl->fl_next, break_time);
1371        spin_lock(&inode->i_lock);
1372        locks_delete_block(new_fl);
1373        if (error >= 0) {
1374                if (error == 0)
1375                        time_out_leases(inode);
1376                /*
1377                 * Wait for the next conflicting lease that has not been
1378                 * broken yet
1379                 */
1380                for (flock = inode->i_flock; flock && IS_LEASE(flock);
1381                                flock = flock->fl_next) {
1382                        if (locks_conflict(new_fl, flock))
1383                                goto restart;
1384                }
1385                error = 0;
1386        }
1387
1388out:
1389        spin_unlock(&inode->i_lock);
1390        locks_free_lock(new_fl);
1391        return error;
1392}
1393
1394EXPORT_SYMBOL(__break_lease);
1395
1396/**
1397 *      lease_get_mtime - get the last modified time of an inode
1398 *      @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
1403 * exclusive lease, then they could be modifying it.
1404 */
1405void lease_get_mtime(struct inode *inode, struct timespec *time)
1406{
1407        struct file_lock *flock = inode->i_flock;
1408        if (flock && IS_LEASE(flock) && (flock->fl_type == F_WRLCK))
1409                *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;
1442        struct inode *inode = file_inode(filp);
1443        int type = F_UNLCK;
1444
1445        spin_lock(&inode->i_lock);
1446        time_out_leases(file_inode(filp));
1447        for (fl = file_inode(filp)->i_flock; fl && IS_LEASE(fl);
1448                        fl = fl->fl_next) {
1449                if (fl->fl_file == filp) {
1450                        type = target_leasetype(fl);
1451                        break;
1452                }
1453        }
1454        spin_unlock(&inode->i_lock);
1455        return type;
1456}
1457
1458static int generic_add_lease(struct file *filp, long arg, struct file_lock **flp)
1459{
1460        struct file_lock *fl, **before, **my_before = NULL, *lease;
1461        struct dentry *dentry = filp->f_path.dentry;
1462        struct inode *inode = dentry->d_inode;
1463        int error;
1464
1465        lease = *flp;
1466
1467        error = -EAGAIN;
1468        if ((arg == F_RDLCK) && (atomic_read(&inode->i_writecount) > 0))
1469                goto out;
1470        if ((arg == F_WRLCK)
1471            && ((d_count(dentry) > 1)
1472                || (atomic_read(&inode->i_count) > 1)))
1473                goto out;
1474
1475        /*
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         */
1483        error = -EAGAIN;
1484        for (before = &inode->i_flock;
1485                        ((fl = *before) != NULL) && IS_LEASE(fl);
1486                        before = &fl->fl_next) {
1487                if (fl->fl_file == filp) {
1488                        my_before = before;
1489                        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;
1503        }
1504
1505        if (my_before != NULL) {
1506                error = lease->fl_lmops->lm_change(my_before, arg);
1507                if (!error)
1508                        *flp = *my_before;
1509                goto out;
1510        }
1511
1512        error = -EINVAL;
1513        if (!leases_enable)
1514                goto out;
1515
1516        locks_insert_lock(before, lease);
1517        return 0;
1518
1519out:
1520        return error;
1521}
1522
1523static int generic_delete_lease(struct file *filp, struct file_lock **flp)
1524{
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
1539/**
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 *
1548 *      Called with inode->i_lock held.
1549 */
1550int generic_setlease(struct file *filp, long arg, struct file_lock **flp)
1551{
1552        struct dentry *dentry = filp->f_path.dentry;
1553        struct inode *inode = dentry->d_inode;
1554        int error;
1555
1556        if ((!uid_eq(current_fsuid(), inode->i_uid)) && !capable(CAP_LEASE))
1557                return -EACCES;
1558        if (!S_ISREG(inode->i_mode))
1559                return -EINVAL;
1560        error = security_file_lock(filp, arg);
1561        if (error)
1562                return error;
1563
1564        time_out_leases(inode);
1565
1566        BUG_ON(!(*flp)->fl_lmops->lm_break);
1567
1568        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:
1575                return -EINVAL;
1576        }
1577}
1578EXPORT_SYMBOL(generic_setlease);
1579
1580static 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/**
1589 *      vfs_setlease        -       sets a lease on an open file
1590 *      @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.
1595 *      The (*lease)->fl_lmops->lm_break operation must be set; if not,
1596 *      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
1607 *      handle their own leases should break leases themselves from the
1608 *      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.
1613 */
1614
1615int vfs_setlease(struct file *filp, long arg, struct file_lock **lease)
1616{
1617        struct inode *inode = file_inode(filp);
1618        int error;
1619
1620        spin_lock(&inode->i_lock);
1621        error = __vfs_setlease(filp, arg, lease);
1622        spin_unlock(&inode->i_lock);
1623
1624        return error;
1625}
1626EXPORT_SYMBOL_GPL(vfs_setlease);
1627
1628static 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)
1638{
1639        struct file_lock *fl, *ret;
1640        struct inode *inode = file_inode(filp);
1641        struct fasync_struct *new;
1642        int error;
1643
1644        fl = lease_alloc(filp, arg);
1645        if (IS_ERR(fl))
1646                return PTR_ERR(fl);
1647
1648        new = fasync_alloc();
1649        if (!new) {
1650                locks_free_lock(fl);
1651                return -ENOMEM;
1652        }
1653        ret = fl;
1654        spin_lock(&inode->i_lock);
1655        error = __vfs_setlease(filp, arg, &ret);
1656        if (error) {
1657                spin_unlock(&inode->i_lock);
1658                locks_free_lock(fl);
1659                goto out_free_fasync;
1660        }
1661        if (ret != fl)
1662                locks_free_lock(fl);
1663
1664        /*
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         */
1670        if (!fasync_insert_entry(fd, filp, &ret->fl_fasync, new))
1671                new = NULL;
1672
1673        error = __f_setown(filp, task_pid(current), PIDTYPE_PID, 0);
1674        spin_unlock(&inode->i_lock);
1675
1676out_free_fasync:
1677        if (new)
1678                fasync_free(new);
1679        return error;
1680}
1681
1682/**
1683 *      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/**
1700 * 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);
1712                if (error != FILE_LOCK_DEFERRED)
1713                        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 */
1745SYSCALL_DEFINE2(flock, unsigned int, fd, unsigned int, cmd)
1746{
1747        struct fd f = fdget(fd);
1748        struct file_lock *lock;
1749        int can_sleep, unlock;
1750        int error;
1751
1752        error = -EBADF;
1753        if (!f.file)
1754                goto out;
1755
1756        can_sleep = !(cmd & LOCK_NB);
1757        cmd &= ~LOCK_NB;
1758        unlock = (cmd == LOCK_UN);
1759
1760        if (!unlock && !(cmd & LOCK_MAND) &&
1761            !(f.file->f_mode & (FMODE_READ|FMODE_WRITE)))
1762                goto out_putf;
1763
1764        error = flock_make_lock(f.file, &lock, cmd);
1765        if (error)
1766                goto out_putf;
1767        if (can_sleep)
1768                lock->fl_flags |= FL_SLEEP;
1769
1770        error = security_file_lock(f.file, lock->fl_type);
1771        if (error)
1772                goto out_free;
1773
1774        if (f.file->f_op && f.file->f_op->flock)
1775                error = f.file->f_op->flock(f.file,
1776                                          (can_sleep) ? F_SETLKW : F_SETLK,
1777                                          lock);
1778        else
1779                error = flock_lock_file_wait(f.file, lock);
1780
1781 out_free:
1782        locks_free_lock(lock);
1783
1784 out_putf:
1785        fdput(f);
1786 out:
1787        return error;
1788}
1789
1790/**
1791 * vfs_test_lock - test file byte range lock
1792 * @filp: The file to test lock for
1793 * @fl: The lock to test; also used to hold result
1794 *
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
1807static 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;
1824        flock->l_type = fl->fl_type;
1825        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
1840/* 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{
1845        struct file_lock file_lock;
1846        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
1860        error = vfs_test_lock(filp, &file_lock);
1861        if (error)
1862                goto out;
1863 
1864        flock.l_type = file_lock.fl_type;
1865        if (file_lock.fl_type != F_UNLCK) {
1866                error = posix_lock_to_flock(&flock, &file_lock);
1867                if (error)
1868                        goto out;
1869        }
1870        error = -EFAULT;
1871        if (!copy_to_user(l, &flock, sizeof(flock)))
1872                error = 0;
1873out:
1874        return error;
1875}
1876
1877/**
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
1882 * @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.
1890 *
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)
1894 * lm_grant is set. Callers expecting ->lock() to return asynchronously
1895 * 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,
1897 * it must return FILE_LOCK_DEFERRED, and call ->lm_grant() when the lock
1898 * request completes.
1899 * If the request is for non-blocking lock the file system should return
1900 * 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
1902 * 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
1907 * ->lm_grant() before returning to the caller with a FILE_LOCK_DEFERRED
1908 * return code.
1909 */
1910int vfs_lock_file(struct file *filp, unsigned int cmd, struct file_lock *fl, struct file_lock *conf)
1911{
1912        if (filp->f_op && filp->f_op->lock)
1913                return filp->f_op->lock(filp, cmd, fl);
1914        else
1915                return posix_lock_file(filp, fl, conf);
1916}
1917EXPORT_SYMBOL_GPL(vfs_lock_file);
1918
1919static 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
1928        for (;;) {
1929                error = vfs_lock_file(filp, cmd, fl, NULL);
1930                if (error != FILE_LOCK_DEFERRED)
1931                        break;
1932                error = wait_event_interruptible(fl->fl_wait, !fl->fl_next);
1933                if (!error)
1934                        continue;
1935
1936                locks_delete_block(fl);
1937                break;
1938        }
1939
1940        return error;
1941}
1942
1943/* 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 */
1946int fcntl_setlk(unsigned int fd, struct file *filp, unsigned int cmd,
1947                struct flock __user *l)
1948{
1949        struct file_lock *file_lock = locks_alloc_lock();
1950        struct flock flock;
1951        struct inode *inode;
1952        struct file *f;
1953        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
1965        inode = file_inode(filp);
1966
1967        /* Don't allow mandatory locks on files that may be memory mapped
1968         * and shared.
1969         */
1970        if (mandatory_lock(inode) && mapping_writably_mapped(filp->f_mapping)) {
1971                error = -EAGAIN;
1972                goto out;
1973        }
1974
1975again:
1976        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
2000        error = do_lock_file_wait(filp, cmd, file_lock);
2001
2002        /*
2003         * Attempt to detect a close/fcntl race and recover by
2004         * releasing the lock that was just acquired.
2005         */
2006        /*
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) {
2015                flock.l_type = F_UNLCK;
2016                goto again;
2017        }
2018
2019out:
2020        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{
2030        struct file_lock file_lock;
2031        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
2045        error = vfs_test_lock(filp, &file_lock);
2046        if (error)
2047                goto out;
2048
2049        flock.l_type = file_lock.fl_type;
2050        if (file_lock.fl_type != F_UNLCK)
2051                posix_lock_to_flock64(&flock, &file_lock);
2052
2053        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 */
2064int fcntl_setlk64(unsigned int fd, struct file *filp, unsigned int cmd,
2065                struct flock64 __user *l)
2066{
2067        struct file_lock *file_lock = locks_alloc_lock();
2068        struct flock64 flock;
2069        struct inode *inode;
2070        struct file *f;
2071        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
2083        inode = file_inode(filp);
2084
2085        /* Don't allow mandatory locks on files that may be memory mapped
2086         * and shared.
2087         */
2088        if (mandatory_lock(inode) && mapping_writably_mapped(filp->f_mapping)) {
2089                error = -EAGAIN;
2090                goto out;
2091        }
2092
2093again:
2094        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
2118        error = do_lock_file_wait(filp, cmd, file_lock);
2119
2120        /*
2121         * Attempt to detect a close/fcntl race and recover by
2122         * releasing the lock that was just acquired.
2123         */
2124        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) {
2128                flock.l_type = F_UNLCK;
2129                goto again;
2130        }
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{
2145        struct file_lock lock;
2146
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         */
2152        if (!file_inode(filp)->i_flock)
2153                return;
2154
2155        lock.fl_type = F_UNLCK;
2156        lock.fl_flags = FL_POSIX | FL_CLOSE;
2157        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
2165        vfs_lock_file(filp, F_SETLK, &lock, NULL);
2166
2167        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{
2178        struct inode * inode = file_inode(filp);
2179        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);
2194                if (fl.fl_ops && fl.fl_ops->fl_release_private)
2195                        fl.fl_ops->fl_release_private(&fl);
2196        }
2197
2198        spin_lock(&inode->i_lock);
2199        before = &inode->i_flock;
2200
2201        while ((fl = *before) != NULL) {
2202                if (fl->fl_file == filp) {
2203                        if (IS_FLOCK(fl)) {
2204                                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        }
2216        spin_unlock(&inode->i_lock);
2217}
2218
2219/**
2220 *      posix_unblock_lock - stop waiting for a file lock
2221 *      @waiter: the lock which was waiting
2222 *
2223 *      lockd needs to block waiting for locks.
2224 */
2225int
2226posix_unblock_lock(struct file_lock *waiter)
2227{
2228        int status = 0;
2229
2230        spin_lock(&blocked_lock_lock);
2231        if (waiter->fl_next)
2232                __locks_delete_block(waiter);
2233        else
2234                status = -ENOENT;
2235        spin_unlock(&blocked_lock_lock);
2236        return status;
2237}
2238EXPORT_SYMBOL(posix_unblock_lock);
2239
2240/**
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
2256#ifdef CONFIG_PROC_FS
2257#include <linux/proc_fs.h>
2258#include <linux/seq_file.h>
2259
2260struct locks_iterator {
2261        int     li_cpu;
2262        loff_t  li_pos;
2263};
2264
2265static void lock_get_status(struct seq_file *f, struct file_lock *fl,
2266                            loff_t id, char *pfx)
2267{
2268        struct inode *inode = NULL;
2269        unsigned int fl_pid;
2270
2271        if (fl->fl_nspid)
2272                fl_pid = pid_vnr(fl->fl_nspid);
2273        else
2274                fl_pid = fl->fl_pid;
2275
2276        if (fl->fl_file != NULL)
2277                inode = file_inode(fl->fl_file);
2278
2279        seq_printf(f, "%lld:%s ", id, pfx);
2280        if (IS_POSIX(fl)) {
2281                seq_printf(f, "%6s %s ",
2282                             (fl->fl_flags & FL_ACCESS) ? "ACCESS" : "POSIX ",
2283                             (inode == NULL) ? "*NOINODE*" :
2284                             mandatory_lock(inode) ? "MANDATORY" : "ADVISORY ");
2285        } else if (IS_FLOCK(fl)) {
2286                if (fl->fl_type & LOCK_MAND) {
2287                        seq_printf(f, "FLOCK  MSNFS     ");
2288                } else {
2289                        seq_printf(f, "FLOCK  ADVISORY  ");
2290                }
2291        } else if (IS_LEASE(fl)) {
2292                seq_printf(f, "LEASE  ");
2293                if (lease_breaking(fl))
2294                        seq_printf(f, "BREAKING  ");
2295                else if (fl->fl_file)
2296                        seq_printf(f, "ACTIVE    ");
2297                else
2298                        seq_printf(f, "BREAKER   ");
2299        } else {
2300                seq_printf(f, "UNKNOWN UNKNOWN  ");
2301        }
2302        if (fl->fl_type & LOCK_MAND) {
2303                seq_printf(f, "%s ",
2304                               (fl->fl_type & LOCK_READ)
2305                               ? (fl->fl_type & LOCK_WRITE) ? "RW   " : "READ "
2306                               : (fl->fl_type & LOCK_WRITE) ? "WRITE" : "NONE ");
2307        } else {
2308                seq_printf(f, "%s ",
2309                               (lease_breaking(fl))
2310                               ? (fl->fl_type == F_UNLCK) ? "UNLCK" : "READ "
2311                               : (fl->fl_type == F_WRLCK) ? "WRITE" : "READ ");
2312        }
2313        if (inode) {
2314#ifdef WE_CAN_BREAK_LSLK_NOW
2315                seq_printf(f, "%d %s:%ld ", fl_pid,
2316                                inode->i_sb->s_id, inode->i_ino);
2317#else
2318                /* userspace relies on this representation of dev_t ;-( */
2319                seq_printf(f, "%d %02x:%02x:%ld ", fl_pid,
2320                                MAJOR(inode->i_sb->s_dev),
2321                                MINOR(inode->i_sb->s_dev), inode->i_ino);
2322#endif
2323        } else {
2324                seq_printf(f, "%d <none>:0 ", fl_pid);
2325        }
2326        if (IS_POSIX(fl)) {
2327                if (fl->fl_end == OFFSET_MAX)
2328                        seq_printf(f, "%Ld EOF\n", fl->fl_start);
2329                else
2330                        seq_printf(f, "%Ld %Ld\n", fl->fl_start, fl->fl_end);
2331        } else {
2332                seq_printf(f, "0 EOF\n");
2333        }
2334}
2335
2336static int locks_show(struct seq_file *f, void *v)
2337{
2338        struct locks_iterator *iter = f->private;
2339        struct file_lock *fl, *bfl;
2340
2341        fl = hlist_entry(v, struct file_lock, fl_link);
2342
2343        lock_get_status(f, fl, iter->li_pos, "");
2344
2345        list_for_each_entry(bfl, &fl->fl_block, fl_block)
2346                lock_get_status(f, bfl, iter->li_pos, " ->");
2347
2348        return 0;
2349}
2350
2351static void *locks_start(struct seq_file *f, loff_t *pos)
2352{
2353        struct locks_iterator *iter = f->private;
2354
2355        iter->li_pos = *pos + 1;
2356        lg_global_lock(&file_lock_lglock);
2357        spin_lock(&blocked_lock_lock);
2358        return seq_hlist_start_percpu(&file_lock_list, &iter->li_cpu, *pos);
2359}
2360
2361static void *locks_next(struct seq_file *f, void *v, loff_t *pos)
2362{
2363        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);
2367}
2368
2369static void locks_stop(struct seq_file *f, void *v)
2370{
2371        spin_unlock(&blocked_lock_lock);
2372        lg_global_unlock(&file_lock_lglock);
2373}
2374
2375static const struct seq_operations locks_seq_operations = {
2376        .start  = locks_start,
2377        .next   = locks_next,
2378        .stop   = locks_stop,
2379        .show   = locks_show,
2380};
2381
2382static int locks_open(struct inode *inode, struct file *filp)
2383{
2384        return seq_open_private(filp, &locks_seq_operations,
2385                                        sizeof(struct locks_iterator));
2386}
2387
2388static const struct file_operations proc_locks_operations = {
2389        .open           = locks_open,
2390        .read           = seq_read,
2391        .llseek         = seq_lseek,
2392        .release        = seq_release_private,
2393};
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);
2401#endif
2402
2403/**
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;
2420
2421        spin_lock(&inode->i_lock);
2422        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        }
2438        spin_unlock(&inode->i_lock);
2439        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;
2461
2462        spin_lock(&inode->i_lock);
2463        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        }
2477        spin_unlock(&inode->i_lock);
2478        return result;
2479}
2480
2481EXPORT_SYMBOL(lock_may_write);
2482
2483static int __init filelock_init(void)
2484{
2485        int i;
2486
2487        filelock_cache = kmem_cache_create("file_lock_cache",
2488                        sizeof(struct file_lock), 0, SLAB_PANIC, NULL);
2489
2490        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
2495        return 0;
2496}
2497
2498core_initcall(filelock_init);
2499
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