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/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/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
 130#include <asm/uaccess.h>
 131
 132#define IS_POSIX(fl)    (fl->fl_flags & FL_POSIX)
 133#define IS_FLOCK(fl)    (fl->fl_flags & FL_FLOCK)
 134#define IS_LEASE(fl)    (fl->fl_flags & FL_LEASE)
 135
 136int leases_enable = 1;
 137int lease_break_time = 45;
 138
 139#define for_each_lock(inode, lockp) \
 140        for (lockp = &inode->i_flock; *lockp != NULL; lockp = &(*lockp)->fl_next)
 141
 142static LIST_HEAD(file_lock_list);
 143static LIST_HEAD(blocked_list);
 144static DEFINE_SPINLOCK(file_lock_lock);
 145
 146/*
 147 * Protects the two list heads above, plus the inode->i_flock list
 148 */
 149void lock_flocks(void)
 150{
 151        spin_lock(&file_lock_lock);
 152}
 153EXPORT_SYMBOL_GPL(lock_flocks);
 154
 155void unlock_flocks(void)
 156{
 157        spin_unlock(&file_lock_lock);
 158}
 159EXPORT_SYMBOL_GPL(unlock_flocks);
 160
 161static struct kmem_cache *filelock_cache __read_mostly;
 162
 163static void locks_init_lock_heads(struct file_lock *fl)
 164{
 165        INIT_LIST_HEAD(&fl->fl_link);
 166        INIT_LIST_HEAD(&fl->fl_block);
 167        init_waitqueue_head(&fl->fl_wait);
 168}
 169
 170/* Allocate an empty lock structure. */
 171struct file_lock *locks_alloc_lock(void)
 172{
 173        struct file_lock *fl = kmem_cache_zalloc(filelock_cache, GFP_KERNEL);
 174
 175        if (fl)
 176                locks_init_lock_heads(fl);
 177
 178        return fl;
 179}
 180EXPORT_SYMBOL_GPL(locks_alloc_lock);
 181
 182void locks_release_private(struct file_lock *fl)
 183{
 184        if (fl->fl_ops) {
 185                if (fl->fl_ops->fl_release_private)
 186                        fl->fl_ops->fl_release_private(fl);
 187                fl->fl_ops = NULL;
 188        }
 189        if (fl->fl_lmops) {
 190                if (fl->fl_lmops->lm_release_private)
 191                        fl->fl_lmops->lm_release_private(fl);
 192                fl->fl_lmops = NULL;
 193        }
 194
 195}
 196EXPORT_SYMBOL_GPL(locks_release_private);
 197
 198/* Free a lock which is not in use. */
 199void locks_free_lock(struct file_lock *fl)
 200{
 201        BUG_ON(waitqueue_active(&fl->fl_wait));
 202        BUG_ON(!list_empty(&fl->fl_block));
 203        BUG_ON(!list_empty(&fl->fl_link));
 204
 205        locks_release_private(fl);
 206        kmem_cache_free(filelock_cache, fl);
 207}
 208EXPORT_SYMBOL(locks_free_lock);
 209
 210void locks_init_lock(struct file_lock *fl)
 211{
 212        memset(fl, 0, sizeof(struct file_lock));
 213        locks_init_lock_heads(fl);
 214}
 215
 216EXPORT_SYMBOL(locks_init_lock);
 217
 218static void locks_copy_private(struct file_lock *new, struct file_lock *fl)
 219{
 220        if (fl->fl_ops) {
 221                if (fl->fl_ops->fl_copy_lock)
 222                        fl->fl_ops->fl_copy_lock(new, fl);
 223                new->fl_ops = fl->fl_ops;
 224        }
 225        if (fl->fl_lmops)
 226                new->fl_lmops = fl->fl_lmops;
 227}
 228
 229/*
 230 * Initialize a new lock from an existing file_lock structure.
 231 */
 232void __locks_copy_lock(struct file_lock *new, const struct file_lock *fl)
 233{
 234        new->fl_owner = fl->fl_owner;
 235        new->fl_pid = fl->fl_pid;
 236        new->fl_file = NULL;
 237        new->fl_flags = fl->fl_flags;
 238        new->fl_type = fl->fl_type;
 239        new->fl_start = fl->fl_start;
 240        new->fl_end = fl->fl_end;
 241        new->fl_ops = NULL;
 242        new->fl_lmops = NULL;
 243}
 244EXPORT_SYMBOL(__locks_copy_lock);
 245
 246void locks_copy_lock(struct file_lock *new, struct file_lock *fl)
 247{
 248        locks_release_private(new);
 249
 250        __locks_copy_lock(new, fl);
 251        new->fl_file = fl->fl_file;
 252        new->fl_ops = fl->fl_ops;
 253        new->fl_lmops = fl->fl_lmops;
 254
 255        locks_copy_private(new, fl);
 256}
 257
 258EXPORT_SYMBOL(locks_copy_lock);
 259
 260static inline int flock_translate_cmd(int cmd) {
 261        if (cmd & LOCK_MAND)
 262                return cmd & (LOCK_MAND | LOCK_RW);
 263        switch (cmd) {
 264        case LOCK_SH:
 265                return F_RDLCK;
 266        case LOCK_EX:
 267                return F_WRLCK;
 268        case LOCK_UN:
 269                return F_UNLCK;
 270        }
 271        return -EINVAL;
 272}
 273
 274/* Fill in a file_lock structure with an appropriate FLOCK lock. */
 275static int flock_make_lock(struct file *filp, struct file_lock **lock,
 276                unsigned int cmd)
 277{
 278        struct file_lock *fl;
 279        int type = flock_translate_cmd(cmd);
 280        if (type < 0)
 281                return type;
 282        
 283        fl = locks_alloc_lock();
 284        if (fl == NULL)
 285                return -ENOMEM;
 286
 287        fl->fl_file = filp;
 288        fl->fl_pid = current->tgid;
 289        fl->fl_flags = FL_FLOCK;
 290        fl->fl_type = type;
 291        fl->fl_end = OFFSET_MAX;
 292        
 293        *lock = fl;
 294        return 0;
 295}
 296
 297static int assign_type(struct file_lock *fl, int type)
 298{
 299        switch (type) {
 300        case F_RDLCK:
 301        case F_WRLCK:
 302        case F_UNLCK:
 303                fl->fl_type = type;
 304                break;
 305        default:
 306                return -EINVAL;
 307        }
 308        return 0;
 309}
 310
 311/* Verify a "struct flock" and copy it to a "struct file_lock" as a POSIX
 312 * style lock.
 313 */
 314static int flock_to_posix_lock(struct file *filp, struct file_lock *fl,
 315                               struct flock *l)
 316{
 317        off_t start, end;
 318
 319        switch (l->l_whence) {
 320        case SEEK_SET:
 321                start = 0;
 322                break;
 323        case SEEK_CUR:
 324                start = filp->f_pos;
 325                break;
 326        case SEEK_END:
 327                start = i_size_read(filp->f_path.dentry->d_inode);
 328                break;
 329        default:
 330                return -EINVAL;
 331        }
 332
 333        /* POSIX-1996 leaves the case l->l_len < 0 undefined;
 334           POSIX-2001 defines it. */
 335        start += l->l_start;
 336        if (start < 0)
 337                return -EINVAL;
 338        fl->fl_end = OFFSET_MAX;
 339        if (l->l_len > 0) {
 340                end = start + l->l_len - 1;
 341                fl->fl_end = end;
 342        } else if (l->l_len < 0) {
 343                end = start - 1;
 344                fl->fl_end = end;
 345                start += l->l_len;
 346                if (start < 0)
 347                        return -EINVAL;
 348        }
 349        fl->fl_start = start;   /* we record the absolute position */
 350        if (fl->fl_end < fl->fl_start)
 351                return -EOVERFLOW;
 352        
 353        fl->fl_owner = current->files;
 354        fl->fl_pid = current->tgid;
 355        fl->fl_file = filp;
 356        fl->fl_flags = FL_POSIX;
 357        fl->fl_ops = NULL;
 358        fl->fl_lmops = NULL;
 359
 360        return assign_type(fl, l->l_type);
 361}
 362
 363#if BITS_PER_LONG == 32
 364static int flock64_to_posix_lock(struct file *filp, struct file_lock *fl,
 365                                 struct flock64 *l)
 366{
 367        loff_t start;
 368
 369        switch (l->l_whence) {
 370        case SEEK_SET:
 371                start = 0;
 372                break;
 373        case SEEK_CUR:
 374                start = filp->f_pos;
 375                break;
 376        case SEEK_END:
 377                start = i_size_read(filp->f_path.dentry->d_inode);
 378                break;
 379        default:
 380                return -EINVAL;
 381        }
 382
 383        start += l->l_start;
 384        if (start < 0)
 385                return -EINVAL;
 386        fl->fl_end = OFFSET_MAX;
 387        if (l->l_len > 0) {
 388                fl->fl_end = start + l->l_len - 1;
 389        } else if (l->l_len < 0) {
 390                fl->fl_end = start - 1;
 391                start += l->l_len;
 392                if (start < 0)
 393                        return -EINVAL;
 394        }
 395        fl->fl_start = start;   /* we record the absolute position */
 396        if (fl->fl_end < fl->fl_start)
 397                return -EOVERFLOW;
 398        
 399        fl->fl_owner = current->files;
 400        fl->fl_pid = current->tgid;
 401        fl->fl_file = filp;
 402        fl->fl_flags = FL_POSIX;
 403        fl->fl_ops = NULL;
 404        fl->fl_lmops = NULL;
 405
 406        return assign_type(fl, l->l_type);
 407}
 408#endif
 409
 410/* default lease lock manager operations */
 411static void lease_break_callback(struct file_lock *fl)
 412{
 413        kill_fasync(&fl->fl_fasync, SIGIO, POLL_MSG);
 414}
 415
 416static void lease_release_private_callback(struct file_lock *fl)
 417{
 418        if (!fl->fl_file)
 419                return;
 420
 421        f_delown(fl->fl_file);
 422        fl->fl_file->f_owner.signum = 0;
 423}
 424
 425static const struct lock_manager_operations lease_manager_ops = {
 426        .lm_break = lease_break_callback,
 427        .lm_release_private = lease_release_private_callback,
 428        .lm_change = lease_modify,
 429};
 430
 431/*
 432 * Initialize a lease, use the default lock manager operations
 433 */
 434static int lease_init(struct file *filp, int type, struct file_lock *fl)
 435 {
 436        if (assign_type(fl, type) != 0)
 437                return -EINVAL;
 438
 439        fl->fl_owner = current->files;
 440        fl->fl_pid = current->tgid;
 441
 442        fl->fl_file = filp;
 443        fl->fl_flags = FL_LEASE;
 444        fl->fl_start = 0;
 445        fl->fl_end = OFFSET_MAX;
 446        fl->fl_ops = NULL;
 447        fl->fl_lmops = &lease_manager_ops;
 448        return 0;
 449}
 450
 451/* Allocate a file_lock initialised to this type of lease */
 452static struct file_lock *lease_alloc(struct file *filp, int type)
 453{
 454        struct file_lock *fl = locks_alloc_lock();
 455        int error = -ENOMEM;
 456
 457        if (fl == NULL)
 458                return ERR_PTR(error);
 459
 460        error = lease_init(filp, type, fl);
 461        if (error) {
 462                locks_free_lock(fl);
 463                return ERR_PTR(error);
 464        }
 465        return fl;
 466}
 467
 468/* Check if two locks overlap each other.
 469 */
 470static inline int locks_overlap(struct file_lock *fl1, struct file_lock *fl2)
 471{
 472        return ((fl1->fl_end >= fl2->fl_start) &&
 473                (fl2->fl_end >= fl1->fl_start));
 474}
 475
 476/*
 477 * Check whether two locks have the same owner.
 478 */
 479static int posix_same_owner(struct file_lock *fl1, struct file_lock *fl2)
 480{
 481        if (fl1->fl_lmops && fl1->fl_lmops->lm_compare_owner)
 482                return fl2->fl_lmops == fl1->fl_lmops &&
 483                        fl1->fl_lmops->lm_compare_owner(fl1, fl2);
 484        return fl1->fl_owner == fl2->fl_owner;
 485}
 486
 487/* Remove waiter from blocker's block list.
 488 * When blocker ends up pointing to itself then the list is empty.
 489 */
 490static void __locks_delete_block(struct file_lock *waiter)
 491{
 492        list_del_init(&waiter->fl_block);
 493        list_del_init(&waiter->fl_link);
 494        waiter->fl_next = NULL;
 495}
 496
 497/*
 498 */
 499static void locks_delete_block(struct file_lock *waiter)
 500{
 501        lock_flocks();
 502        __locks_delete_block(waiter);
 503        unlock_flocks();
 504}
 505
 506/* Insert waiter into blocker's block list.
 507 * We use a circular list so that processes can be easily woken up in
 508 * the order they blocked. The documentation doesn't require this but
 509 * it seems like the reasonable thing to do.
 510 */
 511static void locks_insert_block(struct file_lock *blocker, 
 512                               struct file_lock *waiter)
 513{
 514        BUG_ON(!list_empty(&waiter->fl_block));
 515        list_add_tail(&waiter->fl_block, &blocker->fl_block);
 516        waiter->fl_next = blocker;
 517        if (IS_POSIX(blocker))
 518                list_add(&waiter->fl_link, &blocked_list);
 519}
 520
 521/* Wake up processes blocked waiting for blocker.
 522 * If told to wait then schedule the processes until the block list
 523 * is empty, otherwise empty the block list ourselves.
 524 */
 525static void locks_wake_up_blocks(struct file_lock *blocker)
 526{
 527        while (!list_empty(&blocker->fl_block)) {
 528                struct file_lock *waiter;
 529
 530                waiter = list_first_entry(&blocker->fl_block,
 531                                struct file_lock, fl_block);
 532                __locks_delete_block(waiter);
 533                if (waiter->fl_lmops && waiter->fl_lmops->lm_notify)
 534                        waiter->fl_lmops->lm_notify(waiter);
 535                else
 536                        wake_up(&waiter->fl_wait);
 537        }
 538}
 539
 540/* Insert file lock fl into an inode's lock list at the position indicated
 541 * by pos. At the same time add the lock to the global file lock list.
 542 */
 543static void locks_insert_lock(struct file_lock **pos, struct file_lock *fl)
 544{
 545        list_add(&fl->fl_link, &file_lock_list);
 546
 547        fl->fl_nspid = get_pid(task_tgid(current));
 548
 549        /* insert into file's list */
 550        fl->fl_next = *pos;
 551        *pos = fl;
 552}
 553
 554/*
 555 * Delete a lock and then free it.
 556 * Wake up processes that are blocked waiting for this lock,
 557 * notify the FS that the lock has been cleared and
 558 * finally free the lock.
 559 */
 560static void locks_delete_lock(struct file_lock **thisfl_p)
 561{
 562        struct file_lock *fl = *thisfl_p;
 563
 564        *thisfl_p = fl->fl_next;
 565        fl->fl_next = NULL;
 566        list_del_init(&fl->fl_link);
 567
 568        fasync_helper(0, fl->fl_file, 0, &fl->fl_fasync);
 569        if (fl->fl_fasync != NULL) {
 570                printk(KERN_ERR "locks_delete_lock: fasync == %p\n", fl->fl_fasync);
 571                fl->fl_fasync = NULL;
 572        }
 573
 574        if (fl->fl_nspid) {
 575                put_pid(fl->fl_nspid);
 576                fl->fl_nspid = NULL;
 577        }
 578
 579        locks_wake_up_blocks(fl);
 580        locks_free_lock(fl);
 581}
 582
 583/* Determine if lock sys_fl blocks lock caller_fl. Common functionality
 584 * checks for shared/exclusive status of overlapping locks.
 585 */
 586static int locks_conflict(struct file_lock *caller_fl, struct file_lock *sys_fl)
 587{
 588        if (sys_fl->fl_type == F_WRLCK)
 589                return 1;
 590        if (caller_fl->fl_type == F_WRLCK)
 591                return 1;
 592        return 0;
 593}
 594
 595/* Determine if lock sys_fl blocks lock caller_fl. POSIX specific
 596 * checking before calling the locks_conflict().
 597 */
 598static int posix_locks_conflict(struct file_lock *caller_fl, struct file_lock *sys_fl)
 599{
 600        /* POSIX locks owned by the same process do not conflict with
 601         * each other.
 602         */
 603        if (!IS_POSIX(sys_fl) || posix_same_owner(caller_fl, sys_fl))
 604                return (0);
 605
 606        /* Check whether they overlap */
 607        if (!locks_overlap(caller_fl, sys_fl))
 608                return 0;
 609
 610        return (locks_conflict(caller_fl, sys_fl));
 611}
 612
 613/* Determine if lock sys_fl blocks lock caller_fl. FLOCK specific
 614 * checking before calling the locks_conflict().
 615 */
 616static int flock_locks_conflict(struct file_lock *caller_fl, struct file_lock *sys_fl)
 617{
 618        /* FLOCK locks referring to the same filp do not conflict with
 619         * each other.
 620         */
 621        if (!IS_FLOCK(sys_fl) || (caller_fl->fl_file == sys_fl->fl_file))
 622                return (0);
 623        if ((caller_fl->fl_type & LOCK_MAND) || (sys_fl->fl_type & LOCK_MAND))
 624                return 0;
 625
 626        return (locks_conflict(caller_fl, sys_fl));
 627}
 628
 629void
 630posix_test_lock(struct file *filp, struct file_lock *fl)
 631{
 632        struct file_lock *cfl;
 633
 634        lock_flocks();
 635        for (cfl = filp->f_path.dentry->d_inode->i_flock; cfl; cfl = cfl->fl_next) {
 636                if (!IS_POSIX(cfl))
 637                        continue;
 638                if (posix_locks_conflict(fl, cfl))
 639                        break;
 640        }
 641        if (cfl) {
 642                __locks_copy_lock(fl, cfl);
 643                if (cfl->fl_nspid)
 644                        fl->fl_pid = pid_vnr(cfl->fl_nspid);
 645        } else
 646                fl->fl_type = F_UNLCK;
 647        unlock_flocks();
 648        return;
 649}
 650EXPORT_SYMBOL(posix_test_lock);
 651
 652/*
 653 * Deadlock detection:
 654 *
 655 * We attempt to detect deadlocks that are due purely to posix file
 656 * locks.
 657 *
 658 * We assume that a task can be waiting for at most one lock at a time.
 659 * So for any acquired lock, the process holding that lock may be
 660 * waiting on at most one other lock.  That lock in turns may be held by
 661 * someone waiting for at most one other lock.  Given a requested lock
 662 * caller_fl which is about to wait for a conflicting lock block_fl, we
 663 * follow this chain of waiters to ensure we are not about to create a
 664 * cycle.
 665 *
 666 * Since we do this before we ever put a process to sleep on a lock, we
 667 * are ensured that there is never a cycle; that is what guarantees that
 668 * the while() loop in posix_locks_deadlock() eventually completes.
 669 *
 670 * Note: the above assumption may not be true when handling lock
 671 * requests from a broken NFS client. It may also fail in the presence
 672 * of tasks (such as posix threads) sharing the same open file table.
 673 *
 674 * To handle those cases, we just bail out after a few iterations.
 675 */
 676
 677#define MAX_DEADLK_ITERATIONS 10
 678
 679/* Find a lock that the owner of the given block_fl is blocking on. */
 680static struct file_lock *what_owner_is_waiting_for(struct file_lock *block_fl)
 681{
 682        struct file_lock *fl;
 683
 684        list_for_each_entry(fl, &blocked_list, fl_link) {
 685                if (posix_same_owner(fl, block_fl))
 686                        return fl->fl_next;
 687        }
 688        return NULL;
 689}
 690
 691static int posix_locks_deadlock(struct file_lock *caller_fl,
 692                                struct file_lock *block_fl)
 693{
 694        int i = 0;
 695
 696        while ((block_fl = what_owner_is_waiting_for(block_fl))) {
 697                if (i++ > MAX_DEADLK_ITERATIONS)
 698                        return 0;
 699                if (posix_same_owner(caller_fl, block_fl))
 700                        return 1;
 701        }
 702        return 0;
 703}
 704
 705/* Try to create a FLOCK lock on filp. We always insert new FLOCK locks
 706 * after any leases, but before any posix locks.
 707 *
 708 * Note that if called with an FL_EXISTS argument, the caller may determine
 709 * whether or not a lock was successfully freed by testing the return
 710 * value for -ENOENT.
 711 */
 712static int flock_lock_file(struct file *filp, struct file_lock *request)
 713{
 714        struct file_lock *new_fl = NULL;
 715        struct file_lock **before;
 716        struct inode * inode = filp->f_path.dentry->d_inode;
 717        int error = 0;
 718        int found = 0;
 719
 720        if (!(request->fl_flags & FL_ACCESS) && (request->fl_type != F_UNLCK)) {
 721                new_fl = locks_alloc_lock();
 722                if (!new_fl)
 723                        return -ENOMEM;
 724        }
 725
 726        lock_flocks();
 727        if (request->fl_flags & FL_ACCESS)
 728                goto find_conflict;
 729
 730        for_each_lock(inode, before) {
 731                struct file_lock *fl = *before;
 732                if (IS_POSIX(fl))
 733                        break;
 734                if (IS_LEASE(fl))
 735                        continue;
 736                if (filp != fl->fl_file)
 737                        continue;
 738                if (request->fl_type == fl->fl_type)
 739                        goto out;
 740                found = 1;
 741                locks_delete_lock(before);
 742                break;
 743        }
 744
 745        if (request->fl_type == F_UNLCK) {
 746                if ((request->fl_flags & FL_EXISTS) && !found)
 747                        error = -ENOENT;
 748                goto out;
 749        }
 750
 751        /*
 752         * If a higher-priority process was blocked on the old file lock,
 753         * give it the opportunity to lock the file.
 754         */
 755        if (found) {
 756                unlock_flocks();
 757                cond_resched();
 758                lock_flocks();
 759        }
 760
 761find_conflict:
 762        for_each_lock(inode, before) {
 763                struct file_lock *fl = *before;
 764                if (IS_POSIX(fl))
 765                        break;
 766                if (IS_LEASE(fl))
 767                        continue;
 768                if (!flock_locks_conflict(request, fl))
 769                        continue;
 770                error = -EAGAIN;
 771                if (!(request->fl_flags & FL_SLEEP))
 772                        goto out;
 773                error = FILE_LOCK_DEFERRED;
 774                locks_insert_block(fl, request);
 775                goto out;
 776        }
 777        if (request->fl_flags & FL_ACCESS)
 778                goto out;
 779        locks_copy_lock(new_fl, request);
 780        locks_insert_lock(before, new_fl);
 781        new_fl = NULL;
 782        error = 0;
 783
 784out:
 785        unlock_flocks();
 786        if (new_fl)
 787                locks_free_lock(new_fl);
 788        return error;
 789}
 790
 791static int __posix_lock_file(struct inode *inode, struct file_lock *request, struct file_lock *conflock)
 792{
 793        struct file_lock *fl;
 794        struct file_lock *new_fl = NULL;
 795        struct file_lock *new_fl2 = NULL;
 796        struct file_lock *left = NULL;
 797        struct file_lock *right = NULL;
 798        struct file_lock **before;
 799        int error, added = 0;
 800
 801        /*
 802         * We may need two file_lock structures for this operation,
 803         * so we get them in advance to avoid races.
 804         *
 805         * In some cases we can be sure, that no new locks will be needed
 806         */
 807        if (!(request->fl_flags & FL_ACCESS) &&
 808            (request->fl_type != F_UNLCK ||
 809             request->fl_start != 0 || request->fl_end != OFFSET_MAX)) {
 810                new_fl = locks_alloc_lock();
 811                new_fl2 = locks_alloc_lock();
 812        }
 813
 814        lock_flocks();
 815        if (request->fl_type != F_UNLCK) {
 816                for_each_lock(inode, before) {
 817                        fl = *before;
 818                        if (!IS_POSIX(fl))
 819                                continue;
 820                        if (!posix_locks_conflict(request, fl))
 821                                continue;
 822                        if (conflock)
 823                                __locks_copy_lock(conflock, fl);
 824                        error = -EAGAIN;
 825                        if (!(request->fl_flags & FL_SLEEP))
 826                                goto out;
 827                        error = -EDEADLK;
 828                        if (posix_locks_deadlock(request, fl))
 829                                goto out;
 830                        error = FILE_LOCK_DEFERRED;
 831                        locks_insert_block(fl, request);
 832                        goto out;
 833                }
 834        }
 835
 836        /* If we're just looking for a conflict, we're done. */
 837        error = 0;
 838        if (request->fl_flags & FL_ACCESS)
 839                goto out;
 840
 841        /*
 842         * Find the first old lock with the same owner as the new lock.
 843         */
 844        
 845        before = &inode->i_flock;
 846
 847        /* First skip locks owned by other processes.  */
 848        while ((fl = *before) && (!IS_POSIX(fl) ||
 849                                  !posix_same_owner(request, fl))) {
 850                before = &fl->fl_next;
 851        }
 852
 853        /* Process locks with this owner.  */
 854        while ((fl = *before) && posix_same_owner(request, fl)) {
 855                /* Detect adjacent or overlapping regions (if same lock type)
 856                 */
 857                if (request->fl_type == fl->fl_type) {
 858                        /* In all comparisons of start vs end, use
 859                         * "start - 1" rather than "end + 1". If end
 860                         * is OFFSET_MAX, end + 1 will become negative.
 861                         */
 862                        if (fl->fl_end < request->fl_start - 1)
 863                                goto next_lock;
 864                        /* If the next lock in the list has entirely bigger
 865                         * addresses than the new one, insert the lock here.
 866                         */
 867                        if (fl->fl_start - 1 > request->fl_end)
 868                                break;
 869
 870                        /* If we come here, the new and old lock are of the
 871                         * same type and adjacent or overlapping. Make one
 872                         * lock yielding from the lower start address of both
 873                         * locks to the higher end address.
 874                         */
 875                        if (fl->fl_start > request->fl_start)
 876                                fl->fl_start = request->fl_start;
 877                        else
 878                                request->fl_start = fl->fl_start;
 879                        if (fl->fl_end < request->fl_end)
 880                                fl->fl_end = request->fl_end;
 881                        else
 882                                request->fl_end = fl->fl_end;
 883                        if (added) {
 884                                locks_delete_lock(before);
 885                                continue;
 886                        }
 887                        request = fl;
 888                        added = 1;
 889                }
 890                else {
 891                        /* Processing for different lock types is a bit
 892                         * more complex.
 893                         */
 894                        if (fl->fl_end < request->fl_start)
 895                                goto next_lock;
 896                        if (fl->fl_start > request->fl_end)
 897                                break;
 898                        if (request->fl_type == F_UNLCK)
 899                                added = 1;
 900                        if (fl->fl_start < request->fl_start)
 901                                left = fl;
 902                        /* If the next lock in the list has a higher end
 903                         * address than the new one, insert the new one here.
 904                         */
 905                        if (fl->fl_end > request->fl_end) {
 906                                right = fl;
 907                                break;
 908                        }
 909                        if (fl->fl_start >= request->fl_start) {
 910                                /* The new lock completely replaces an old
 911                                 * one (This may happen several times).
 912                                 */
 913                                if (added) {
 914                                        locks_delete_lock(before);
 915                                        continue;
 916                                }
 917                                /* Replace the old lock with the new one.
 918                                 * Wake up anybody waiting for the old one,
 919                                 * as the change in lock type might satisfy
 920                                 * their needs.
 921                                 */
 922                                locks_wake_up_blocks(fl);
 923                                fl->fl_start = request->fl_start;
 924                                fl->fl_end = request->fl_end;
 925                                fl->fl_type = request->fl_type;
 926                                locks_release_private(fl);
 927                                locks_copy_private(fl, request);
 928                                request = fl;
 929                                added = 1;
 930                        }
 931                }
 932                /* Go on to next lock.
 933                 */
 934        next_lock:
 935                before = &fl->fl_next;
 936        }
 937
 938        /*
 939         * The above code only modifies existing locks in case of
 940         * merging or replacing.  If new lock(s) need to be inserted
 941         * all modifications are done bellow this, so it's safe yet to
 942         * bail out.
 943         */
 944        error = -ENOLCK; /* "no luck" */
 945        if (right && left == right && !new_fl2)
 946                goto out;
 947
 948        error = 0;
 949        if (!added) {
 950                if (request->fl_type == F_UNLCK) {
 951                        if (request->fl_flags & FL_EXISTS)
 952                                error = -ENOENT;
 953                        goto out;
 954                }
 955
 956                if (!new_fl) {
 957                        error = -ENOLCK;
 958                        goto out;
 959                }
 960                locks_copy_lock(new_fl, request);
 961                locks_insert_lock(before, new_fl);
 962                new_fl = NULL;
 963        }
 964        if (right) {
 965                if (left == right) {
 966                        /* The new lock breaks the old one in two pieces,
 967                         * so we have to use the second new lock.
 968                         */
 969                        left = new_fl2;
 970                        new_fl2 = NULL;
 971                        locks_copy_lock(left, right);
 972                        locks_insert_lock(before, left);
 973                }
 974                right->fl_start = request->fl_end + 1;
 975                locks_wake_up_blocks(right);
 976        }
 977        if (left) {
 978                left->fl_end = request->fl_start - 1;
 979                locks_wake_up_blocks(left);
 980        }
 981 out:
 982        unlock_flocks();
 983        /*
 984         * Free any unused locks.
 985         */
 986        if (new_fl)
 987                locks_free_lock(new_fl);
 988        if (new_fl2)
 989                locks_free_lock(new_fl2);
 990        return error;
 991}
 992
 993/**
 994 * posix_lock_file - Apply a POSIX-style lock to a file
 995 * @filp: The file to apply the lock to
 996 * @fl: The lock to be applied
 997 * @conflock: Place to return a copy of the conflicting lock, if found.
 998 *
 999 * Add a POSIX style lock to a file.
1000 * We merge adjacent & overlapping locks whenever possible.
1001 * POSIX locks are sorted by owner task, then by starting address
1002 *
1003 * Note that if called with an FL_EXISTS argument, the caller may determine
1004 * whether or not a lock was successfully freed by testing the return
1005 * value for -ENOENT.
1006 */
1007int posix_lock_file(struct file *filp, struct file_lock *fl,
1008                        struct file_lock *conflock)
1009{
1010        return __posix_lock_file(filp->f_path.dentry->d_inode, fl, conflock);
1011}
1012EXPORT_SYMBOL(posix_lock_file);
1013
1014/**
1015 * posix_lock_file_wait - Apply a POSIX-style lock to a file
1016 * @filp: The file to apply the lock to
1017 * @fl: The lock to be applied
1018 *
1019 * Add a POSIX style lock to a file.
1020 * We merge adjacent & overlapping locks whenever possible.
1021 * POSIX locks are sorted by owner task, then by starting address
1022 */
1023int posix_lock_file_wait(struct file *filp, struct file_lock *fl)
1024{
1025        int error;
1026        might_sleep ();
1027        for (;;) {
1028                error = posix_lock_file(filp, fl, NULL);
1029                if (error != FILE_LOCK_DEFERRED)
1030                        break;
1031                error = wait_event_interruptible(fl->fl_wait, !fl->fl_next);
1032                if (!error)
1033                        continue;
1034
1035                locks_delete_block(fl);
1036                break;
1037        }
1038        return error;
1039}
1040EXPORT_SYMBOL(posix_lock_file_wait);
1041
1042/**
1043 * locks_mandatory_locked - Check for an active lock
1044 * @inode: the file to check
1045 *
1046 * Searches the inode's list of locks to find any POSIX locks which conflict.
1047 * This function is called from locks_verify_locked() only.
1048 */
1049int locks_mandatory_locked(struct inode *inode)
1050{
1051        fl_owner_t owner = current->files;
1052        struct file_lock *fl;
1053
1054        /*
1055         * Search the lock list for this inode for any POSIX locks.
1056         */
1057        lock_flocks();
1058        for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) {
1059                if (!IS_POSIX(fl))
1060                        continue;
1061                if (fl->fl_owner != owner)
1062                        break;
1063        }
1064        unlock_flocks();
1065        return fl ? -EAGAIN : 0;
1066}
1067
1068/**
1069 * locks_mandatory_area - Check for a conflicting lock
1070 * @read_write: %FLOCK_VERIFY_WRITE for exclusive access, %FLOCK_VERIFY_READ
1071 *              for shared
1072 * @inode:      the file to check
1073 * @filp:       how the file was opened (if it was)
1074 * @offset:     start of area to check
1075 * @count:      length of area to check
1076 *
1077 * Searches the inode's list of locks to find any POSIX locks which conflict.
1078 * This function is called from rw_verify_area() and
1079 * locks_verify_truncate().
1080 */
1081int locks_mandatory_area(int read_write, struct inode *inode,
1082                         struct file *filp, loff_t offset,
1083                         size_t count)
1084{
1085        struct file_lock fl;
1086        int error;
1087
1088        locks_init_lock(&fl);
1089        fl.fl_owner = current->files;
1090        fl.fl_pid = current->tgid;
1091        fl.fl_file = filp;
1092        fl.fl_flags = FL_POSIX | FL_ACCESS;
1093        if (filp && !(filp->f_flags & O_NONBLOCK))
1094                fl.fl_flags |= FL_SLEEP;
1095        fl.fl_type = (read_write == FLOCK_VERIFY_WRITE) ? F_WRLCK : F_RDLCK;
1096        fl.fl_start = offset;
1097        fl.fl_end = offset + count - 1;
1098
1099        for (;;) {
1100                error = __posix_lock_file(inode, &fl, NULL);
1101                if (error != FILE_LOCK_DEFERRED)
1102                        break;
1103                error = wait_event_interruptible(fl.fl_wait, !fl.fl_next);
1104                if (!error) {
1105                        /*
1106                         * If we've been sleeping someone might have
1107                         * changed the permissions behind our back.
1108                         */
1109                        if (__mandatory_lock(inode))
1110                                continue;
1111                }
1112
1113                locks_delete_block(&fl);
1114                break;
1115        }
1116
1117        return error;
1118}
1119
1120EXPORT_SYMBOL(locks_mandatory_area);
1121
1122/* We already had a lease on this file; just change its type */
1123int lease_modify(struct file_lock **before, int arg)
1124{
1125        struct file_lock *fl = *before;
1126        int error = assign_type(fl, arg);
1127
1128        if (error)
1129                return error;
1130        locks_wake_up_blocks(fl);
1131        if (arg == F_UNLCK)
1132                locks_delete_lock(before);
1133        return 0;
1134}
1135
1136EXPORT_SYMBOL(lease_modify);
1137
1138static void time_out_leases(struct inode *inode)
1139{
1140        struct file_lock **before;
1141        struct file_lock *fl;
1142
1143        before = &inode->i_flock;
1144        while ((fl = *before) && IS_LEASE(fl) && (fl->fl_type & F_INPROGRESS)) {
1145                if ((fl->fl_break_time == 0)
1146                                || time_before(jiffies, fl->fl_break_time)) {
1147                        before = &fl->fl_next;
1148                        continue;
1149                }
1150                lease_modify(before, fl->fl_type & ~F_INPROGRESS);
1151                if (fl == *before)      /* lease_modify may have freed fl */
1152                        before = &fl->fl_next;
1153        }
1154}
1155
1156/**
1157 *      __break_lease   -       revoke all outstanding leases on file
1158 *      @inode: the inode of the file to return
1159 *      @mode: the open mode (read or write)
1160 *
1161 *      break_lease (inlined for speed) has checked there already is at least
1162 *      some kind of lock (maybe a lease) on this file.  Leases are broken on
1163 *      a call to open() or truncate().  This function can sleep unless you
1164 *      specified %O_NONBLOCK to your open().
1165 */
1166int __break_lease(struct inode *inode, unsigned int mode)
1167{
1168        int error = 0, future;
1169        struct file_lock *new_fl, *flock;
1170        struct file_lock *fl;
1171        unsigned long break_time;
1172        int i_have_this_lease = 0;
1173        int want_write = (mode & O_ACCMODE) != O_RDONLY;
1174
1175        new_fl = lease_alloc(NULL, want_write ? F_WRLCK : F_RDLCK);
1176
1177        lock_flocks();
1178
1179        time_out_leases(inode);
1180
1181        flock = inode->i_flock;
1182        if ((flock == NULL) || !IS_LEASE(flock))
1183                goto out;
1184
1185        for (fl = flock; fl && IS_LEASE(fl); fl = fl->fl_next)
1186                if (fl->fl_owner == current->files)
1187                        i_have_this_lease = 1;
1188
1189        if (want_write) {
1190                /* If we want write access, we have to revoke any lease. */
1191                future = F_UNLCK | F_INPROGRESS;
1192        } else if (flock->fl_type & F_INPROGRESS) {
1193                /* If the lease is already being broken, we just leave it */
1194                future = flock->fl_type;
1195        } else if (flock->fl_type & F_WRLCK) {
1196                /* Downgrade the exclusive lease to a read-only lease. */
1197                future = F_RDLCK | F_INPROGRESS;
1198        } else {
1199                /* the existing lease was read-only, so we can read too. */
1200                goto out;
1201        }
1202
1203        if (IS_ERR(new_fl) && !i_have_this_lease
1204                        && ((mode & O_NONBLOCK) == 0)) {
1205                error = PTR_ERR(new_fl);
1206                goto out;
1207        }
1208
1209        break_time = 0;
1210        if (lease_break_time > 0) {
1211                break_time = jiffies + lease_break_time * HZ;
1212                if (break_time == 0)
1213                        break_time++;   /* so that 0 means no break time */
1214        }
1215
1216        for (fl = flock; fl && IS_LEASE(fl); fl = fl->fl_next) {
1217                if (fl->fl_type != future) {
1218                        fl->fl_type = future;
1219                        fl->fl_break_time = break_time;
1220                        /* lease must have lmops break callback */
1221                        fl->fl_lmops->lm_break(fl);
1222                }
1223        }
1224
1225        if (i_have_this_lease || (mode & O_NONBLOCK)) {
1226                error = -EWOULDBLOCK;
1227                goto out;
1228        }
1229
1230restart:
1231        break_time = flock->fl_break_time;
1232        if (break_time != 0) {
1233                break_time -= jiffies;
1234                if (break_time == 0)
1235                        break_time++;
1236        }
1237        locks_insert_block(flock, new_fl);
1238        unlock_flocks();
1239        error = wait_event_interruptible_timeout(new_fl->fl_wait,
1240                                                !new_fl->fl_next, break_time);
1241        lock_flocks();
1242        __locks_delete_block(new_fl);
1243        if (error >= 0) {
1244                if (error == 0)
1245                        time_out_leases(inode);
1246                /* Wait for the next lease that has not been broken yet */
1247                for (flock = inode->i_flock; flock && IS_LEASE(flock);
1248                                flock = flock->fl_next) {
1249                        if (flock->fl_type & F_INPROGRESS)
1250                                goto restart;
1251                }
1252                error = 0;
1253        }
1254
1255out:
1256        unlock_flocks();
1257        if (!IS_ERR(new_fl))
1258                locks_free_lock(new_fl);
1259        return error;
1260}
1261
1262EXPORT_SYMBOL(__break_lease);
1263
1264/**
1265 *      lease_get_mtime - get the last modified time of an inode
1266 *      @inode: the inode
1267 *      @time:  pointer to a timespec which will contain the last modified time
1268 *
1269 * This is to force NFS clients to flush their caches for files with
1270 * exclusive leases.  The justification is that if someone has an
1271 * exclusive lease, then they could be modifying it.
1272 */
1273void lease_get_mtime(struct inode *inode, struct timespec *time)
1274{
1275        struct file_lock *flock = inode->i_flock;
1276        if (flock && IS_LEASE(flock) && (flock->fl_type & F_WRLCK))
1277                *time = current_fs_time(inode->i_sb);
1278        else
1279                *time = inode->i_mtime;
1280}
1281
1282EXPORT_SYMBOL(lease_get_mtime);
1283
1284/**
1285 *      fcntl_getlease - Enquire what lease is currently active
1286 *      @filp: the file
1287 *
1288 *      The value returned by this function will be one of
1289 *      (if no lease break is pending):
1290 *
1291 *      %F_RDLCK to indicate a shared lease is held.
1292 *
1293 *      %F_WRLCK to indicate an exclusive lease is held.
1294 *
1295 *      %F_UNLCK to indicate no lease is held.
1296 *
1297 *      (if a lease break is pending):
1298 *
1299 *      %F_RDLCK to indicate an exclusive lease needs to be
1300 *              changed to a shared lease (or removed).
1301 *
1302 *      %F_UNLCK to indicate the lease needs to be removed.
1303 *
1304 *      XXX: sfr & willy disagree over whether F_INPROGRESS
1305 *      should be returned to userspace.
1306 */
1307int fcntl_getlease(struct file *filp)
1308{
1309        struct file_lock *fl;
1310        int type = F_UNLCK;
1311
1312        lock_flocks();
1313        time_out_leases(filp->f_path.dentry->d_inode);
1314        for (fl = filp->f_path.dentry->d_inode->i_flock; fl && IS_LEASE(fl);
1315                        fl = fl->fl_next) {
1316                if (fl->fl_file == filp) {
1317                        type = fl->fl_type & ~F_INPROGRESS;
1318                        break;
1319                }
1320        }
1321        unlock_flocks();
1322        return type;
1323}
1324
1325/**
1326 *      generic_setlease        -       sets a lease on an open file
1327 *      @filp: file pointer
1328 *      @arg: type of lease to obtain
1329 *      @flp: input - file_lock to use, output - file_lock inserted
1330 *
1331 *      The (input) flp->fl_lmops->lm_break function is required
1332 *      by break_lease().
1333 *
1334 *      Called with file_lock_lock held.
1335 */
1336int generic_setlease(struct file *filp, long arg, struct file_lock **flp)
1337{
1338        struct file_lock *fl, **before, **my_before = NULL, *lease;
1339        struct dentry *dentry = filp->f_path.dentry;
1340        struct inode *inode = dentry->d_inode;
1341        int error, rdlease_count = 0, wrlease_count = 0;
1342
1343        lease = *flp;
1344
1345        error = -EACCES;
1346        if ((current_fsuid() != inode->i_uid) && !capable(CAP_LEASE))
1347                goto out;
1348        error = -EINVAL;
1349        if (!S_ISREG(inode->i_mode))
1350                goto out;
1351        error = security_file_lock(filp, arg);
1352        if (error)
1353                goto out;
1354
1355        time_out_leases(inode);
1356
1357        BUG_ON(!(*flp)->fl_lmops->lm_break);
1358
1359        if (arg != F_UNLCK) {
1360                error = -EAGAIN;
1361                if ((arg == F_RDLCK) && (atomic_read(&inode->i_writecount) > 0))
1362                        goto out;
1363                if ((arg == F_WRLCK)
1364                    && ((dentry->d_count > 1)
1365                        || (atomic_read(&inode->i_count) > 1)))
1366                        goto out;
1367        }
1368
1369        /*
1370         * At this point, we know that if there is an exclusive
1371         * lease on this file, then we hold it on this filp
1372         * (otherwise our open of this file would have blocked).
1373         * And if we are trying to acquire an exclusive lease,
1374         * then the file is not open by anyone (including us)
1375         * except for this filp.
1376         */
1377        for (before = &inode->i_flock;
1378                        ((fl = *before) != NULL) && IS_LEASE(fl);
1379                        before = &fl->fl_next) {
1380                if (fl->fl_file == filp)
1381                        my_before = before;
1382                else if (fl->fl_type == (F_INPROGRESS | F_UNLCK))
1383                        /*
1384                         * Someone is in the process of opening this
1385                         * file for writing so we may not take an
1386                         * exclusive lease on it.
1387                         */
1388                        wrlease_count++;
1389                else
1390                        rdlease_count++;
1391        }
1392
1393        error = -EAGAIN;
1394        if ((arg == F_RDLCK && (wrlease_count > 0)) ||
1395            (arg == F_WRLCK && ((rdlease_count + wrlease_count) > 0)))
1396                goto out;
1397
1398        if (my_before != NULL) {
1399                error = lease->fl_lmops->lm_change(my_before, arg);
1400                if (!error)
1401                        *flp = *my_before;
1402                goto out;
1403        }
1404
1405        if (arg == F_UNLCK)
1406                goto out;
1407
1408        error = -EINVAL;
1409        if (!leases_enable)
1410                goto out;
1411
1412        locks_insert_lock(before, lease);
1413        return 0;
1414
1415out:
1416        return error;
1417}
1418EXPORT_SYMBOL(generic_setlease);
1419
1420static int __vfs_setlease(struct file *filp, long arg, struct file_lock **lease)
1421{
1422        if (filp->f_op && filp->f_op->setlease)
1423                return filp->f_op->setlease(filp, arg, lease);
1424        else
1425                return generic_setlease(filp, arg, lease);
1426}
1427
1428/**
1429 *      vfs_setlease        -       sets a lease on an open file
1430 *      @filp: file pointer
1431 *      @arg: type of lease to obtain
1432 *      @lease: file_lock to use
1433 *
1434 *      Call this to establish a lease on the file.
1435 *      The (*lease)->fl_lmops->lm_break operation must be set; if not,
1436 *      break_lease will oops!
1437 *
1438 *      This will call the filesystem's setlease file method, if
1439 *      defined.  Note that there is no getlease method; instead, the
1440 *      filesystem setlease method should call back to setlease() to
1441 *      add a lease to the inode's lease list, where fcntl_getlease() can
1442 *      find it.  Since fcntl_getlease() only reports whether the current
1443 *      task holds a lease, a cluster filesystem need only do this for
1444 *      leases held by processes on this node.
1445 *
1446 *      There is also no break_lease method; filesystems that
1447 *      handle their own leases should break leases themselves from the
1448 *      filesystem's open, create, and (on truncate) setattr methods.
1449 *
1450 *      Warning: the only current setlease methods exist only to disable
1451 *      leases in certain cases.  More vfs changes may be required to
1452 *      allow a full filesystem lease implementation.
1453 */
1454
1455int vfs_setlease(struct file *filp, long arg, struct file_lock **lease)
1456{
1457        int error;
1458
1459        lock_flocks();
1460        error = __vfs_setlease(filp, arg, lease);
1461        unlock_flocks();
1462
1463        return error;
1464}
1465EXPORT_SYMBOL_GPL(vfs_setlease);
1466
1467static int do_fcntl_delete_lease(struct file *filp)
1468{
1469        struct file_lock fl, *flp = &fl;
1470
1471        lease_init(filp, F_UNLCK, flp);
1472
1473        return vfs_setlease(filp, F_UNLCK, &flp);
1474}
1475
1476static int do_fcntl_add_lease(unsigned int fd, struct file *filp, long arg)
1477{
1478        struct file_lock *fl, *ret;
1479        struct fasync_struct *new;
1480        int error;
1481
1482        fl = lease_alloc(filp, arg);
1483        if (IS_ERR(fl))
1484                return PTR_ERR(fl);
1485
1486        new = fasync_alloc();
1487        if (!new) {
1488                locks_free_lock(fl);
1489                return -ENOMEM;
1490        }
1491        ret = fl;
1492        lock_flocks();
1493        error = __vfs_setlease(filp, arg, &ret);
1494        if (error) {
1495                unlock_flocks();
1496                locks_free_lock(fl);
1497                goto out_free_fasync;
1498        }
1499        if (ret != fl)
1500                locks_free_lock(fl);
1501
1502        /*
1503         * fasync_insert_entry() returns the old entry if any.
1504         * If there was no old entry, then it used 'new' and
1505         * inserted it into the fasync list. Clear new so that
1506         * we don't release it here.
1507         */
1508        if (!fasync_insert_entry(fd, filp, &ret->fl_fasync, new))
1509                new = NULL;
1510
1511        error = __f_setown(filp, task_pid(current), PIDTYPE_PID, 0);
1512        unlock_flocks();
1513
1514out_free_fasync:
1515        if (new)
1516                fasync_free(new);
1517        return error;
1518}
1519
1520/**
1521 *      fcntl_setlease  -       sets a lease on an open file
1522 *      @fd: open file descriptor
1523 *      @filp: file pointer
1524 *      @arg: type of lease to obtain
1525 *
1526 *      Call this fcntl to establish a lease on the file.
1527 *      Note that you also need to call %F_SETSIG to
1528 *      receive a signal when the lease is broken.
1529 */
1530int fcntl_setlease(unsigned int fd, struct file *filp, long arg)
1531{
1532        if (arg == F_UNLCK)
1533                return do_fcntl_delete_lease(filp);
1534        return do_fcntl_add_lease(fd, filp, arg);
1535}
1536
1537/**
1538 * flock_lock_file_wait - Apply a FLOCK-style lock to a file
1539 * @filp: The file to apply the lock to
1540 * @fl: The lock to be applied
1541 *
1542 * Add a FLOCK style lock to a file.
1543 */
1544int flock_lock_file_wait(struct file *filp, struct file_lock *fl)
1545{
1546        int error;
1547        might_sleep();
1548        for (;;) {
1549                error = flock_lock_file(filp, fl);
1550                if (error != FILE_LOCK_DEFERRED)
1551                        break;
1552                error = wait_event_interruptible(fl->fl_wait, !fl->fl_next);
1553                if (!error)
1554                        continue;
1555
1556                locks_delete_block(fl);
1557                break;
1558        }
1559        return error;
1560}
1561
1562EXPORT_SYMBOL(flock_lock_file_wait);
1563
1564/**
1565 *      sys_flock: - flock() system call.
1566 *      @fd: the file descriptor to lock.
1567 *      @cmd: the type of lock to apply.
1568 *
1569 *      Apply a %FL_FLOCK style lock to an open file descriptor.
1570 *      The @cmd can be one of
1571 *
1572 *      %LOCK_SH -- a shared lock.
1573 *
1574 *      %LOCK_EX -- an exclusive lock.
1575 *
1576 *      %LOCK_UN -- remove an existing lock.
1577 *
1578 *      %LOCK_MAND -- a `mandatory' flock.  This exists to emulate Windows Share Modes.
1579 *
1580 *      %LOCK_MAND can be combined with %LOCK_READ or %LOCK_WRITE to allow other
1581 *      processes read and write access respectively.
1582 */
1583SYSCALL_DEFINE2(flock, unsigned int, fd, unsigned int, cmd)
1584{
1585        struct file *filp;
1586        struct file_lock *lock;
1587        int can_sleep, unlock;
1588        int error;
1589
1590        error = -EBADF;
1591        filp = fget(fd);
1592        if (!filp)
1593                goto out;
1594
1595        can_sleep = !(cmd & LOCK_NB);
1596        cmd &= ~LOCK_NB;
1597        unlock = (cmd == LOCK_UN);
1598
1599        if (!unlock && !(cmd & LOCK_MAND) &&
1600            !(filp->f_mode & (FMODE_READ|FMODE_WRITE)))
1601                goto out_putf;
1602
1603        error = flock_make_lock(filp, &lock, cmd);
1604        if (error)
1605                goto out_putf;
1606        if (can_sleep)
1607                lock->fl_flags |= FL_SLEEP;
1608
1609        error = security_file_lock(filp, lock->fl_type);
1610        if (error)
1611                goto out_free;
1612
1613        if (filp->f_op && filp->f_op->flock)
1614                error = filp->f_op->flock(filp,
1615                                          (can_sleep) ? F_SETLKW : F_SETLK,
1616                                          lock);
1617        else
1618                error = flock_lock_file_wait(filp, lock);
1619
1620 out_free:
1621        locks_free_lock(lock);
1622
1623 out_putf:
1624        fput(filp);
1625 out:
1626        return error;
1627}
1628
1629/**
1630 * vfs_test_lock - test file byte range lock
1631 * @filp: The file to test lock for
1632 * @fl: The lock to test; also used to hold result
1633 *
1634 * Returns -ERRNO on failure.  Indicates presence of conflicting lock by
1635 * setting conf->fl_type to something other than F_UNLCK.
1636 */
1637int vfs_test_lock(struct file *filp, struct file_lock *fl)
1638{
1639        if (filp->f_op && filp->f_op->lock)
1640                return filp->f_op->lock(filp, F_GETLK, fl);
1641        posix_test_lock(filp, fl);
1642        return 0;
1643}
1644EXPORT_SYMBOL_GPL(vfs_test_lock);
1645
1646static int posix_lock_to_flock(struct flock *flock, struct file_lock *fl)
1647{
1648        flock->l_pid = fl->fl_pid;
1649#if BITS_PER_LONG == 32
1650        /*
1651         * Make sure we can represent the posix lock via
1652         * legacy 32bit flock.
1653         */
1654        if (fl->fl_start > OFFT_OFFSET_MAX)
1655                return -EOVERFLOW;
1656        if (fl->fl_end != OFFSET_MAX && fl->fl_end > OFFT_OFFSET_MAX)
1657                return -EOVERFLOW;
1658#endif
1659        flock->l_start = fl->fl_start;
1660        flock->l_len = fl->fl_end == OFFSET_MAX ? 0 :
1661                fl->fl_end - fl->fl_start + 1;
1662        flock->l_whence = 0;
1663        flock->l_type = fl->fl_type;
1664        return 0;
1665}
1666
1667#if BITS_PER_LONG == 32
1668static void posix_lock_to_flock64(struct flock64 *flock, struct file_lock *fl)
1669{
1670        flock->l_pid = fl->fl_pid;
1671        flock->l_start = fl->fl_start;
1672        flock->l_len = fl->fl_end == OFFSET_MAX ? 0 :
1673                fl->fl_end - fl->fl_start + 1;
1674        flock->l_whence = 0;
1675        flock->l_type = fl->fl_type;
1676}
1677#endif
1678
1679/* Report the first existing lock that would conflict with l.
1680 * This implements the F_GETLK command of fcntl().
1681 */
1682int fcntl_getlk(struct file *filp, struct flock __user *l)
1683{
1684        struct file_lock file_lock;
1685        struct flock flock;
1686        int error;
1687
1688        error = -EFAULT;
1689        if (copy_from_user(&flock, l, sizeof(flock)))
1690                goto out;
1691        error = -EINVAL;
1692        if ((flock.l_type != F_RDLCK) && (flock.l_type != F_WRLCK))
1693                goto out;
1694
1695        error = flock_to_posix_lock(filp, &file_lock, &flock);
1696        if (error)
1697                goto out;
1698
1699        error = vfs_test_lock(filp, &file_lock);
1700        if (error)
1701                goto out;
1702 
1703        flock.l_type = file_lock.fl_type;
1704        if (file_lock.fl_type != F_UNLCK) {
1705                error = posix_lock_to_flock(&flock, &file_lock);
1706                if (error)
1707                        goto out;
1708        }
1709        error = -EFAULT;
1710        if (!copy_to_user(l, &flock, sizeof(flock)))
1711                error = 0;
1712out:
1713        return error;
1714}
1715
1716/**
1717 * vfs_lock_file - file byte range lock
1718 * @filp: The file to apply the lock to
1719 * @cmd: type of locking operation (F_SETLK, F_GETLK, etc.)
1720 * @fl: The lock to be applied
1721 * @conf: Place to return a copy of the conflicting lock, if found.
1722 *
1723 * A caller that doesn't care about the conflicting lock may pass NULL
1724 * as the final argument.
1725 *
1726 * If the filesystem defines a private ->lock() method, then @conf will
1727 * be left unchanged; so a caller that cares should initialize it to
1728 * some acceptable default.
1729 *
1730 * To avoid blocking kernel daemons, such as lockd, that need to acquire POSIX
1731 * locks, the ->lock() interface may return asynchronously, before the lock has
1732 * been granted or denied by the underlying filesystem, if (and only if)
1733 * lm_grant is set. Callers expecting ->lock() to return asynchronously
1734 * will only use F_SETLK, not F_SETLKW; they will set FL_SLEEP if (and only if)
1735 * the request is for a blocking lock. When ->lock() does return asynchronously,
1736 * it must return FILE_LOCK_DEFERRED, and call ->lm_grant() when the lock
1737 * request completes.
1738 * If the request is for non-blocking lock the file system should return
1739 * FILE_LOCK_DEFERRED then try to get the lock and call the callback routine
1740 * with the result. If the request timed out the callback routine will return a
1741 * nonzero return code and the file system should release the lock. The file
1742 * system is also responsible to keep a corresponding posix lock when it
1743 * grants a lock so the VFS can find out which locks are locally held and do
1744 * the correct lock cleanup when required.
1745 * The underlying filesystem must not drop the kernel lock or call
1746 * ->lm_grant() before returning to the caller with a FILE_LOCK_DEFERRED
1747 * return code.
1748 */
1749int vfs_lock_file(struct file *filp, unsigned int cmd, struct file_lock *fl, struct file_lock *conf)
1750{
1751        if (filp->f_op && filp->f_op->lock)
1752                return filp->f_op->lock(filp, cmd, fl);
1753        else
1754                return posix_lock_file(filp, fl, conf);
1755}
1756EXPORT_SYMBOL_GPL(vfs_lock_file);
1757
1758static int do_lock_file_wait(struct file *filp, unsigned int cmd,
1759                             struct file_lock *fl)
1760{
1761        int error;
1762
1763        error = security_file_lock(filp, fl->fl_type);
1764        if (error)
1765                return error;
1766
1767        for (;;) {
1768                error = vfs_lock_file(filp, cmd, fl, NULL);
1769                if (error != FILE_LOCK_DEFERRED)
1770                        break;
1771                error = wait_event_interruptible(fl->fl_wait, !fl->fl_next);
1772                if (!error)
1773                        continue;
1774
1775                locks_delete_block(fl);
1776                break;
1777        }
1778
1779        return error;
1780}
1781
1782/* Apply the lock described by l to an open file descriptor.
1783 * This implements both the F_SETLK and F_SETLKW commands of fcntl().
1784 */
1785int fcntl_setlk(unsigned int fd, struct file *filp, unsigned int cmd,
1786                struct flock __user *l)
1787{
1788        struct file_lock *file_lock = locks_alloc_lock();
1789        struct flock flock;
1790        struct inode *inode;
1791        struct file *f;
1792        int error;
1793
1794        if (file_lock == NULL)
1795                return -ENOLCK;
1796
1797        /*
1798         * This might block, so we do it before checking the inode.
1799         */
1800        error = -EFAULT;
1801        if (copy_from_user(&flock, l, sizeof(flock)))
1802                goto out;
1803
1804        inode = filp->f_path.dentry->d_inode;
1805
1806        /* Don't allow mandatory locks on files that may be memory mapped
1807         * and shared.
1808         */
1809        if (mandatory_lock(inode) && mapping_writably_mapped(filp->f_mapping)) {
1810                error = -EAGAIN;
1811                goto out;
1812        }
1813
1814again:
1815        error = flock_to_posix_lock(filp, file_lock, &flock);
1816        if (error)
1817                goto out;
1818        if (cmd == F_SETLKW) {
1819                file_lock->fl_flags |= FL_SLEEP;
1820        }
1821        
1822        error = -EBADF;
1823        switch (flock.l_type) {
1824        case F_RDLCK:
1825                if (!(filp->f_mode & FMODE_READ))
1826                        goto out;
1827                break;
1828        case F_WRLCK:
1829                if (!(filp->f_mode & FMODE_WRITE))
1830                        goto out;
1831                break;
1832        case F_UNLCK:
1833                break;
1834        default:
1835                error = -EINVAL;
1836                goto out;
1837        }
1838
1839        error = do_lock_file_wait(filp, cmd, file_lock);
1840
1841        /*
1842         * Attempt to detect a close/fcntl race and recover by
1843         * releasing the lock that was just acquired.
1844         */
1845        /*
1846         * we need that spin_lock here - it prevents reordering between
1847         * update of inode->i_flock and check for it done in close().
1848         * rcu_read_lock() wouldn't do.
1849         */
1850        spin_lock(&current->files->file_lock);
1851        f = fcheck(fd);
1852        spin_unlock(&current->files->file_lock);
1853        if (!error && f != filp && flock.l_type != F_UNLCK) {
1854                flock.l_type = F_UNLCK;
1855                goto again;
1856        }
1857
1858out:
1859        locks_free_lock(file_lock);
1860        return error;
1861}
1862
1863#if BITS_PER_LONG == 32
1864/* Report the first existing lock that would conflict with l.
1865 * This implements the F_GETLK command of fcntl().
1866 */
1867int fcntl_getlk64(struct file *filp, struct flock64 __user *l)
1868{
1869        struct file_lock file_lock;
1870        struct flock64 flock;
1871        int error;
1872
1873        error = -EFAULT;
1874        if (copy_from_user(&flock, l, sizeof(flock)))
1875                goto out;
1876        error = -EINVAL;
1877        if ((flock.l_type != F_RDLCK) && (flock.l_type != F_WRLCK))
1878                goto out;
1879
1880        error = flock64_to_posix_lock(filp, &file_lock, &flock);
1881        if (error)
1882                goto out;
1883
1884        error = vfs_test_lock(filp, &file_lock);
1885        if (error)
1886                goto out;
1887
1888        flock.l_type = file_lock.fl_type;
1889        if (file_lock.fl_type != F_UNLCK)
1890                posix_lock_to_flock64(&flock, &file_lock);
1891
1892        error = -EFAULT;
1893        if (!copy_to_user(l, &flock, sizeof(flock)))
1894                error = 0;
1895  
1896out:
1897        return error;
1898}
1899
1900/* Apply the lock described by l to an open file descriptor.
1901 * This implements both the F_SETLK and F_SETLKW commands of fcntl().
1902 */
1903int fcntl_setlk64(unsigned int fd, struct file *filp, unsigned int cmd,
1904                struct flock64 __user *l)
1905{
1906        struct file_lock *file_lock = locks_alloc_lock();
1907        struct flock64 flock;
1908        struct inode *inode;
1909        struct file *f;
1910        int error;
1911
1912        if (file_lock == NULL)
1913                return -ENOLCK;
1914
1915        /*
1916         * This might block, so we do it before checking the inode.
1917         */
1918        error = -EFAULT;
1919        if (copy_from_user(&flock, l, sizeof(flock)))
1920                goto out;
1921
1922        inode = filp->f_path.dentry->d_inode;
1923
1924        /* Don't allow mandatory locks on files that may be memory mapped
1925         * and shared.
1926         */
1927        if (mandatory_lock(inode) && mapping_writably_mapped(filp->f_mapping)) {
1928                error = -EAGAIN;
1929                goto out;
1930        }
1931
1932again:
1933        error = flock64_to_posix_lock(filp, file_lock, &flock);
1934        if (error)
1935                goto out;
1936        if (cmd == F_SETLKW64) {
1937                file_lock->fl_flags |= FL_SLEEP;
1938        }
1939        
1940        error = -EBADF;
1941        switch (flock.l_type) {
1942        case F_RDLCK:
1943                if (!(filp->f_mode & FMODE_READ))
1944                        goto out;
1945                break;
1946        case F_WRLCK:
1947                if (!(filp->f_mode & FMODE_WRITE))
1948                        goto out;
1949                break;
1950        case F_UNLCK:
1951                break;
1952        default:
1953                error = -EINVAL;
1954                goto out;
1955        }
1956
1957        error = do_lock_file_wait(filp, cmd, file_lock);
1958
1959        /*
1960         * Attempt to detect a close/fcntl race and recover by
1961         * releasing the lock that was just acquired.
1962         */
1963        spin_lock(&current->files->file_lock);
1964        f = fcheck(fd);
1965        spin_unlock(&current->files->file_lock);
1966        if (!error && f != filp && flock.l_type != F_UNLCK) {
1967                flock.l_type = F_UNLCK;
1968                goto again;
1969        }
1970
1971out:
1972        locks_free_lock(file_lock);
1973        return error;
1974}
1975#endif /* BITS_PER_LONG == 32 */
1976
1977/*
1978 * This function is called when the file is being removed
1979 * from the task's fd array.  POSIX locks belonging to this task
1980 * are deleted at this time.
1981 */
1982void locks_remove_posix(struct file *filp, fl_owner_t owner)
1983{
1984        struct file_lock lock;
1985
1986        /*
1987         * If there are no locks held on this file, we don't need to call
1988         * posix_lock_file().  Another process could be setting a lock on this
1989         * file at the same time, but we wouldn't remove that lock anyway.
1990         */
1991        if (!filp->f_path.dentry->d_inode->i_flock)
1992                return;
1993
1994        lock.fl_type = F_UNLCK;
1995        lock.fl_flags = FL_POSIX | FL_CLOSE;
1996        lock.fl_start = 0;
1997        lock.fl_end = OFFSET_MAX;
1998        lock.fl_owner = owner;
1999        lock.fl_pid = current->tgid;
2000        lock.fl_file = filp;
2001        lock.fl_ops = NULL;
2002        lock.fl_lmops = NULL;
2003
2004        vfs_lock_file(filp, F_SETLK, &lock, NULL);
2005
2006        if (lock.fl_ops && lock.fl_ops->fl_release_private)
2007                lock.fl_ops->fl_release_private(&lock);
2008}
2009
2010EXPORT_SYMBOL(locks_remove_posix);
2011
2012/*
2013 * This function is called on the last close of an open file.
2014 */
2015void locks_remove_flock(struct file *filp)
2016{
2017        struct inode * inode = filp->f_path.dentry->d_inode;
2018        struct file_lock *fl;
2019        struct file_lock **before;
2020
2021        if (!inode->i_flock)
2022                return;
2023
2024        if (filp->f_op && filp->f_op->flock) {
2025                struct file_lock fl = {
2026                        .fl_pid = current->tgid,
2027                        .fl_file = filp,
2028                        .fl_flags = FL_FLOCK,
2029                        .fl_type = F_UNLCK,
2030                        .fl_end = OFFSET_MAX,
2031                };
2032                filp->f_op->flock(filp, F_SETLKW, &fl);
2033                if (fl.fl_ops && fl.fl_ops->fl_release_private)
2034                        fl.fl_ops->fl_release_private(&fl);
2035        }
2036
2037        lock_flocks();
2038        before = &inode->i_flock;
2039
2040        while ((fl = *before) != NULL) {
2041                if (fl->fl_file == filp) {
2042                        if (IS_FLOCK(fl)) {
2043                                locks_delete_lock(before);
2044                                continue;
2045                        }
2046                        if (IS_LEASE(fl)) {
2047                                lease_modify(before, F_UNLCK);
2048                                continue;
2049                        }
2050                        /* What? */
2051                        BUG();
2052                }
2053                before = &fl->fl_next;
2054        }
2055        unlock_flocks();
2056}
2057
2058/**
2059 *      posix_unblock_lock - stop waiting for a file lock
2060 *      @filp:   how the file was opened
2061 *      @waiter: the lock which was waiting
2062 *
2063 *      lockd needs to block waiting for locks.
2064 */
2065int
2066posix_unblock_lock(struct file *filp, struct file_lock *waiter)
2067{
2068        int status = 0;
2069
2070        lock_flocks();
2071        if (waiter->fl_next)
2072                __locks_delete_block(waiter);
2073        else
2074                status = -ENOENT;
2075        unlock_flocks();
2076        return status;
2077}
2078
2079EXPORT_SYMBOL(posix_unblock_lock);
2080
2081/**
2082 * vfs_cancel_lock - file byte range unblock lock
2083 * @filp: The file to apply the unblock to
2084 * @fl: The lock to be unblocked
2085 *
2086 * Used by lock managers to cancel blocked requests
2087 */
2088int vfs_cancel_lock(struct file *filp, struct file_lock *fl)
2089{
2090        if (filp->f_op && filp->f_op->lock)
2091                return filp->f_op->lock(filp, F_CANCELLK, fl);
2092        return 0;
2093}
2094
2095EXPORT_SYMBOL_GPL(vfs_cancel_lock);
2096
2097#ifdef CONFIG_PROC_FS
2098#include <linux/proc_fs.h>
2099#include <linux/seq_file.h>
2100
2101static void lock_get_status(struct seq_file *f, struct file_lock *fl,
2102                            loff_t id, char *pfx)
2103{
2104        struct inode *inode = NULL;
2105        unsigned int fl_pid;
2106
2107        if (fl->fl_nspid)
2108                fl_pid = pid_vnr(fl->fl_nspid);
2109        else
2110                fl_pid = fl->fl_pid;
2111
2112        if (fl->fl_file != NULL)
2113                inode = fl->fl_file->f_path.dentry->d_inode;
2114
2115        seq_printf(f, "%lld:%s ", id, pfx);
2116        if (IS_POSIX(fl)) {
2117                seq_printf(f, "%6s %s ",
2118                             (fl->fl_flags & FL_ACCESS) ? "ACCESS" : "POSIX ",
2119                             (inode == NULL) ? "*NOINODE*" :
2120                             mandatory_lock(inode) ? "MANDATORY" : "ADVISORY ");
2121        } else if (IS_FLOCK(fl)) {
2122                if (fl->fl_type & LOCK_MAND) {
2123                        seq_printf(f, "FLOCK  MSNFS     ");
2124                } else {
2125                        seq_printf(f, "FLOCK  ADVISORY  ");
2126                }
2127        } else if (IS_LEASE(fl)) {
2128                seq_printf(f, "LEASE  ");
2129                if (fl->fl_type & F_INPROGRESS)
2130                        seq_printf(f, "BREAKING  ");
2131                else if (fl->fl_file)
2132                        seq_printf(f, "ACTIVE    ");
2133                else
2134                        seq_printf(f, "BREAKER   ");
2135        } else {
2136                seq_printf(f, "UNKNOWN UNKNOWN  ");
2137        }
2138        if (fl->fl_type & LOCK_MAND) {
2139                seq_printf(f, "%s ",
2140                               (fl->fl_type & LOCK_READ)
2141                               ? (fl->fl_type & LOCK_WRITE) ? "RW   " : "READ "
2142                               : (fl->fl_type & LOCK_WRITE) ? "WRITE" : "NONE ");
2143        } else {
2144                seq_printf(f, "%s ",
2145                               (fl->fl_type & F_INPROGRESS)
2146                               ? (fl->fl_type & F_UNLCK) ? "UNLCK" : "READ "
2147                               : (fl->fl_type & F_WRLCK) ? "WRITE" : "READ ");
2148        }
2149        if (inode) {
2150#ifdef WE_CAN_BREAK_LSLK_NOW
2151                seq_printf(f, "%d %s:%ld ", fl_pid,
2152                                inode->i_sb->s_id, inode->i_ino);
2153#else
2154                /* userspace relies on this representation of dev_t ;-( */
2155                seq_printf(f, "%d %02x:%02x:%ld ", fl_pid,
2156                                MAJOR(inode->i_sb->s_dev),
2157                                MINOR(inode->i_sb->s_dev), inode->i_ino);
2158#endif
2159        } else {
2160                seq_printf(f, "%d <none>:0 ", fl_pid);
2161        }
2162        if (IS_POSIX(fl)) {
2163                if (fl->fl_end == OFFSET_MAX)
2164                        seq_printf(f, "%Ld EOF\n", fl->fl_start);
2165                else
2166                        seq_printf(f, "%Ld %Ld\n", fl->fl_start, fl->fl_end);
2167        } else {
2168                seq_printf(f, "0 EOF\n");
2169        }
2170}
2171
2172static int locks_show(struct seq_file *f, void *v)
2173{
2174        struct file_lock *fl, *bfl;
2175
2176        fl = list_entry(v, struct file_lock, fl_link);
2177
2178        lock_get_status(f, fl, *((loff_t *)f->private), "");
2179
2180        list_for_each_entry(bfl, &fl->fl_block, fl_block)
2181                lock_get_status(f, bfl, *((loff_t *)f->private), " ->");
2182
2183        return 0;
2184}
2185
2186static void *locks_start(struct seq_file *f, loff_t *pos)
2187{
2188        loff_t *p = f->private;
2189
2190        lock_flocks();
2191        *p = (*pos + 1);
2192        return seq_list_start(&file_lock_list, *pos);
2193}
2194
2195static void *locks_next(struct seq_file *f, void *v, loff_t *pos)
2196{
2197        loff_t *p = f->private;
2198        ++*p;
2199        return seq_list_next(v, &file_lock_list, pos);
2200}
2201
2202static void locks_stop(struct seq_file *f, void *v)
2203{
2204        unlock_flocks();
2205}
2206
2207static const struct seq_operations locks_seq_operations = {
2208        .start  = locks_start,
2209        .next   = locks_next,
2210        .stop   = locks_stop,
2211        .show   = locks_show,
2212};
2213
2214static int locks_open(struct inode *inode, struct file *filp)
2215{
2216        return seq_open_private(filp, &locks_seq_operations, sizeof(loff_t));
2217}
2218
2219static const struct file_operations proc_locks_operations = {
2220        .open           = locks_open,
2221        .read           = seq_read,
2222        .llseek         = seq_lseek,
2223        .release        = seq_release_private,
2224};
2225
2226static int __init proc_locks_init(void)
2227{
2228        proc_create("locks", 0, NULL, &proc_locks_operations);
2229        return 0;
2230}
2231module_init(proc_locks_init);
2232#endif
2233
2234/**
2235 *      lock_may_read - checks that the region is free of locks
2236 *      @inode: the inode that is being read
2237 *      @start: the first byte to read
2238 *      @len: the number of bytes to read
2239 *
2240 *      Emulates Windows locking requirements.  Whole-file
2241 *      mandatory locks (share modes) can prohibit a read and
2242 *      byte-range POSIX locks can prohibit a read if they overlap.
2243 *
2244 *      N.B. this function is only ever called
2245 *      from knfsd and ownership of locks is never checked.
2246 */
2247int lock_may_read(struct inode *inode, loff_t start, unsigned long len)
2248{
2249        struct file_lock *fl;
2250        int result = 1;
2251        lock_flocks();
2252        for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) {
2253                if (IS_POSIX(fl)) {
2254                        if (fl->fl_type == F_RDLCK)
2255                                continue;
2256                        if ((fl->fl_end < start) || (fl->fl_start > (start + len)))
2257                                continue;
2258                } else if (IS_FLOCK(fl)) {
2259                        if (!(fl->fl_type & LOCK_MAND))
2260                                continue;
2261                        if (fl->fl_type & LOCK_READ)
2262                                continue;
2263                } else
2264                        continue;
2265                result = 0;
2266                break;
2267        }
2268        unlock_flocks();
2269        return result;
2270}
2271
2272EXPORT_SYMBOL(lock_may_read);
2273
2274/**
2275 *      lock_may_write - checks that the region is free of locks
2276 *      @inode: the inode that is being written
2277 *      @start: the first byte to write
2278 *      @len: the number of bytes to write
2279 *
2280 *      Emulates Windows locking requirements.  Whole-file
2281 *      mandatory locks (share modes) can prohibit a write and
2282 *      byte-range POSIX locks can prohibit a write if they overlap.
2283 *
2284 *      N.B. this function is only ever called
2285 *      from knfsd and ownership of locks is never checked.
2286 */
2287int lock_may_write(struct inode *inode, loff_t start, unsigned long len)
2288{
2289        struct file_lock *fl;
2290        int result = 1;
2291        lock_flocks();
2292        for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) {
2293                if (IS_POSIX(fl)) {
2294                        if ((fl->fl_end < start) || (fl->fl_start > (start + len)))
2295                                continue;
2296                } else if (IS_FLOCK(fl)) {
2297                        if (!(fl->fl_type & LOCK_MAND))
2298                                continue;
2299                        if (fl->fl_type & LOCK_WRITE)
2300                                continue;
2301                } else
2302                        continue;
2303                result = 0;
2304                break;
2305        }
2306        unlock_flocks();
2307        return result;
2308}
2309
2310EXPORT_SYMBOL(lock_may_write);
2311
2312static int __init filelock_init(void)
2313{
2314        filelock_cache = kmem_cache_create("file_lock_cache",
2315                        sizeof(struct file_lock), 0, SLAB_PANIC, NULL);
2316
2317        return 0;
2318}
2319
2320core_initcall(filelock_init);
2321
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