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
 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
 136static bool lease_breaking(struct file_lock *fl)
 137{
 138        return fl->fl_flags & (FL_UNLOCK_PENDING | FL_DOWNGRADE_PENDING);
 139}
 140
 141static int target_leasetype(struct file_lock *fl)
 142{
 143        if (fl->fl_flags & FL_UNLOCK_PENDING)
 144                return F_UNLCK;
 145        if (fl->fl_flags & FL_DOWNGRADE_PENDING)
 146                return F_RDLCK;
 147        return fl->fl_type;
 148}
 149
 150int leases_enable = 1;
 151int lease_break_time = 45;
 152
 153#define for_each_lock(inode, lockp) \
 154        for (lockp = &inode->i_flock; *lockp != NULL; lockp = &(*lockp)->fl_next)
 155
 156static LIST_HEAD(file_lock_list);
 157static LIST_HEAD(blocked_list);
 158static DEFINE_SPINLOCK(file_lock_lock);
 159
 160/*
 161 * Protects the two list heads above, plus the inode->i_flock list
 162 */
 163void lock_flocks(void)
 164{
 165        spin_lock(&file_lock_lock);
 166}
 167EXPORT_SYMBOL_GPL(lock_flocks);
 168
 169void unlock_flocks(void)
 170{
 171        spin_unlock(&file_lock_lock);
 172}
 173EXPORT_SYMBOL_GPL(unlock_flocks);
 174
 175static struct kmem_cache *filelock_cache __read_mostly;
 176
 177static void locks_init_lock_heads(struct file_lock *fl)
 178{
 179        INIT_LIST_HEAD(&fl->fl_link);
 180        INIT_LIST_HEAD(&fl->fl_block);
 181        init_waitqueue_head(&fl->fl_wait);
 182}
 183
 184/* Allocate an empty lock structure. */
 185struct file_lock *locks_alloc_lock(void)
 186{
 187        struct file_lock *fl = kmem_cache_zalloc(filelock_cache, GFP_KERNEL);
 188
 189        if (fl)
 190                locks_init_lock_heads(fl);
 191
 192        return fl;
 193}
 194EXPORT_SYMBOL_GPL(locks_alloc_lock);
 195
 196void locks_release_private(struct file_lock *fl)
 197{
 198        if (fl->fl_ops) {
 199                if (fl->fl_ops->fl_release_private)
 200                        fl->fl_ops->fl_release_private(fl);
 201                fl->fl_ops = NULL;
 202        }
 203        if (fl->fl_lmops) {
 204                if (fl->fl_lmops->lm_release_private)
 205                        fl->fl_lmops->lm_release_private(fl);
 206                fl->fl_lmops = NULL;
 207        }
 208
 209}
 210EXPORT_SYMBOL_GPL(locks_release_private);
 211
 212/* Free a lock which is not in use. */
 213void locks_free_lock(struct file_lock *fl)
 214{
 215        BUG_ON(waitqueue_active(&fl->fl_wait));
 216        BUG_ON(!list_empty(&fl->fl_block));
 217        BUG_ON(!list_empty(&fl->fl_link));
 218
 219        locks_release_private(fl);
 220        kmem_cache_free(filelock_cache, fl);
 221}
 222EXPORT_SYMBOL(locks_free_lock);
 223
 224void locks_init_lock(struct file_lock *fl)
 225{
 226        memset(fl, 0, sizeof(struct file_lock));
 227        locks_init_lock_heads(fl);
 228}
 229
 230EXPORT_SYMBOL(locks_init_lock);
 231
 232static void locks_copy_private(struct file_lock *new, struct file_lock *fl)
 233{
 234        if (fl->fl_ops) {
 235                if (fl->fl_ops->fl_copy_lock)
 236                        fl->fl_ops->fl_copy_lock(new, fl);
 237                new->fl_ops = fl->fl_ops;
 238        }
 239        if (fl->fl_lmops)
 240                new->fl_lmops = fl->fl_lmops;
 241}
 242
 243/*
 244 * Initialize a new lock from an existing file_lock structure.
 245 */
 246void __locks_copy_lock(struct file_lock *new, const struct file_lock *fl)
 247{
 248        new->fl_owner = fl->fl_owner;
 249        new->fl_pid = fl->fl_pid;
 250        new->fl_file = NULL;
 251        new->fl_flags = fl->fl_flags;
 252        new->fl_type = fl->fl_type;
 253        new->fl_start = fl->fl_start;
 254        new->fl_end = fl->fl_end;
 255        new->fl_ops = NULL;
 256        new->fl_lmops = NULL;
 257}
 258EXPORT_SYMBOL(__locks_copy_lock);
 259
 260void locks_copy_lock(struct file_lock *new, struct file_lock *fl)
 261{
 262        locks_release_private(new);
 263
 264        __locks_copy_lock(new, fl);
 265        new->fl_file = fl->fl_file;
 266        new->fl_ops = fl->fl_ops;
 267        new->fl_lmops = fl->fl_lmops;
 268
 269        locks_copy_private(new, fl);
 270}
 271
 272EXPORT_SYMBOL(locks_copy_lock);
 273
 274static inline int flock_translate_cmd(int cmd) {
 275        if (cmd & LOCK_MAND)
 276                return cmd & (LOCK_MAND | LOCK_RW);
 277        switch (cmd) {
 278        case LOCK_SH:
 279                return F_RDLCK;
 280        case LOCK_EX:
 281                return F_WRLCK;
 282        case LOCK_UN:
 283                return F_UNLCK;
 284        }
 285        return -EINVAL;
 286}
 287
 288/* Fill in a file_lock structure with an appropriate FLOCK lock. */
 289static int flock_make_lock(struct file *filp, struct file_lock **lock,
 290                unsigned int cmd)
 291{
 292        struct file_lock *fl;
 293        int type = flock_translate_cmd(cmd);
 294        if (type < 0)
 295                return type;
 296        
 297        fl = locks_alloc_lock();
 298        if (fl == NULL)
 299                return -ENOMEM;
 300
 301        fl->fl_file = filp;
 302        fl->fl_pid = current->tgid;
 303        fl->fl_flags = FL_FLOCK;
 304        fl->fl_type = type;
 305        fl->fl_end = OFFSET_MAX;
 306        
 307        *lock = fl;
 308        return 0;
 309}
 310
 311static int assign_type(struct file_lock *fl, long type)
 312{
 313        switch (type) {
 314        case F_RDLCK:
 315        case F_WRLCK:
 316        case F_UNLCK:
 317                fl->fl_type = type;
 318                break;
 319        default:
 320                return -EINVAL;
 321        }
 322        return 0;
 323}
 324
 325/* Verify a "struct flock" and copy it to a "struct file_lock" as a POSIX
 326 * style lock.
 327 */
 328static int flock_to_posix_lock(struct file *filp, struct file_lock *fl,
 329                               struct flock *l)
 330{
 331        off_t start, end;
 332
 333        switch (l->l_whence) {
 334        case SEEK_SET:
 335                start = 0;
 336                break;
 337        case SEEK_CUR:
 338                start = filp->f_pos;
 339                break;
 340        case SEEK_END:
 341                start = i_size_read(filp->f_path.dentry->d_inode);
 342                break;
 343        default:
 344                return -EINVAL;
 345        }
 346
 347        /* POSIX-1996 leaves the case l->l_len < 0 undefined;
 348           POSIX-2001 defines it. */
 349        start += l->l_start;
 350        if (start < 0)
 351                return -EINVAL;
 352        fl->fl_end = OFFSET_MAX;
 353        if (l->l_len > 0) {
 354                end = start + l->l_len - 1;
 355                fl->fl_end = end;
 356        } else if (l->l_len < 0) {
 357                end = start - 1;
 358                fl->fl_end = end;
 359                start += l->l_len;
 360                if (start < 0)
 361                        return -EINVAL;
 362        }
 363        fl->fl_start = start;   /* we record the absolute position */
 364        if (fl->fl_end < fl->fl_start)
 365                return -EOVERFLOW;
 366        
 367        fl->fl_owner = current->files;
 368        fl->fl_pid = current->tgid;
 369        fl->fl_file = filp;
 370        fl->fl_flags = FL_POSIX;
 371        fl->fl_ops = NULL;
 372        fl->fl_lmops = NULL;
 373
 374        return assign_type(fl, l->l_type);
 375}
 376
 377#if BITS_PER_LONG == 32
 378static int flock64_to_posix_lock(struct file *filp, struct file_lock *fl,
 379                                 struct flock64 *l)
 380{
 381        loff_t start;
 382
 383        switch (l->l_whence) {
 384        case SEEK_SET:
 385                start = 0;
 386                break;
 387        case SEEK_CUR:
 388                start = filp->f_pos;
 389                break;
 390        case SEEK_END:
 391                start = i_size_read(filp->f_path.dentry->d_inode);
 392                break;
 393        default:
 394                return -EINVAL;
 395        }
 396
 397        start += l->l_start;
 398        if (start < 0)
 399                return -EINVAL;
 400        fl->fl_end = OFFSET_MAX;
 401        if (l->l_len > 0) {
 402                fl->fl_end = start + l->l_len - 1;
 403        } else if (l->l_len < 0) {
 404                fl->fl_end = start - 1;
 405                start += l->l_len;
 406                if (start < 0)
 407                        return -EINVAL;
 408        }
 409        fl->fl_start = start;   /* we record the absolute position */
 410        if (fl->fl_end < fl->fl_start)
 411                return -EOVERFLOW;
 412        
 413        fl->fl_owner = current->files;
 414        fl->fl_pid = current->tgid;
 415        fl->fl_file = filp;
 416        fl->fl_flags = FL_POSIX;
 417        fl->fl_ops = NULL;
 418        fl->fl_lmops = NULL;
 419
 420        return assign_type(fl, l->l_type);
 421}
 422#endif
 423
 424/* default lease lock manager operations */
 425static void lease_break_callback(struct file_lock *fl)
 426{
 427        kill_fasync(&fl->fl_fasync, SIGIO, POLL_MSG);
 428}
 429
 430static void lease_release_private_callback(struct file_lock *fl)
 431{
 432        if (!fl->fl_file)
 433                return;
 434
 435        f_delown(fl->fl_file);
 436        fl->fl_file->f_owner.signum = 0;
 437}
 438
 439static const struct lock_manager_operations lease_manager_ops = {
 440        .lm_break = lease_break_callback,
 441        .lm_release_private = lease_release_private_callback,
 442        .lm_change = lease_modify,
 443};
 444
 445/*
 446 * Initialize a lease, use the default lock manager operations
 447 */
 448static int lease_init(struct file *filp, long type, struct file_lock *fl)
 449 {
 450        if (assign_type(fl, type) != 0)
 451                return -EINVAL;
 452
 453        fl->fl_owner = current->files;
 454        fl->fl_pid = current->tgid;
 455
 456        fl->fl_file = filp;
 457        fl->fl_flags = FL_LEASE;
 458        fl->fl_start = 0;
 459        fl->fl_end = OFFSET_MAX;
 460        fl->fl_ops = NULL;
 461        fl->fl_lmops = &lease_manager_ops;
 462        return 0;
 463}
 464
 465/* Allocate a file_lock initialised to this type of lease */
 466static struct file_lock *lease_alloc(struct file *filp, long type)
 467{
 468        struct file_lock *fl = locks_alloc_lock();
 469        int error = -ENOMEM;
 470
 471        if (fl == NULL)
 472                return ERR_PTR(error);
 473
 474        error = lease_init(filp, type, fl);
 475        if (error) {
 476                locks_free_lock(fl);
 477                return ERR_PTR(error);
 478        }
 479        return fl;
 480}
 481
 482/* Check if two locks overlap each other.
 483 */
 484static inline int locks_overlap(struct file_lock *fl1, struct file_lock *fl2)
 485{
 486        return ((fl1->fl_end >= fl2->fl_start) &&
 487                (fl2->fl_end >= fl1->fl_start));
 488}
 489
 490/*
 491 * Check whether two locks have the same owner.
 492 */
 493static int posix_same_owner(struct file_lock *fl1, struct file_lock *fl2)
 494{
 495        if (fl1->fl_lmops && fl1->fl_lmops->lm_compare_owner)
 496                return fl2->fl_lmops == fl1->fl_lmops &&
 497                        fl1->fl_lmops->lm_compare_owner(fl1, fl2);
 498        return fl1->fl_owner == fl2->fl_owner;
 499}
 500
 501/* Remove waiter from blocker's block list.
 502 * When blocker ends up pointing to itself then the list is empty.
 503 */
 504static void __locks_delete_block(struct file_lock *waiter)
 505{
 506        list_del_init(&waiter->fl_block);
 507        list_del_init(&waiter->fl_link);
 508        waiter->fl_next = NULL;
 509}
 510
 511/*
 512 */
 513void locks_delete_block(struct file_lock *waiter)
 514{
 515        lock_flocks();
 516        __locks_delete_block(waiter);
 517        unlock_flocks();
 518}
 519EXPORT_SYMBOL(locks_delete_block);
 520
 521/* Insert waiter into blocker's block list.
 522 * We use a circular list so that processes can be easily woken up in
 523 * the order they blocked. The documentation doesn't require this but
 524 * it seems like the reasonable thing to do.
 525 */
 526static void locks_insert_block(struct file_lock *blocker, 
 527                               struct file_lock *waiter)
 528{
 529        BUG_ON(!list_empty(&waiter->fl_block));
 530        list_add_tail(&waiter->fl_block, &blocker->fl_block);
 531        waiter->fl_next = blocker;
 532        if (IS_POSIX(blocker))
 533                list_add(&waiter->fl_link, &blocked_list);
 534}
 535
 536/* Wake up processes blocked waiting for blocker.
 537 * If told to wait then schedule the processes until the block list
 538 * is empty, otherwise empty the block list ourselves.
 539 */
 540static void locks_wake_up_blocks(struct file_lock *blocker)
 541{
 542        while (!list_empty(&blocker->fl_block)) {
 543                struct file_lock *waiter;
 544
 545                waiter = list_first_entry(&blocker->fl_block,
 546                                struct file_lock, fl_block);
 547                __locks_delete_block(waiter);
 548                if (waiter->fl_lmops && waiter->fl_lmops->lm_notify)
 549                        waiter->fl_lmops->lm_notify(waiter);
 550                else
 551                        wake_up(&waiter->fl_wait);
 552        }
 553}
 554
 555/* Insert file lock fl into an inode's lock list at the position indicated
 556 * by pos. At the same time add the lock to the global file lock list.
 557 */
 558static void locks_insert_lock(struct file_lock **pos, struct file_lock *fl)
 559{
 560        list_add(&fl->fl_link, &file_lock_list);
 561
 562        fl->fl_nspid = get_pid(task_tgid(current));
 563
 564        /* insert into file's list */
 565        fl->fl_next = *pos;
 566        *pos = fl;
 567}
 568
 569/*
 570 * Delete a lock and then free it.
 571 * Wake up processes that are blocked waiting for this lock,
 572 * notify the FS that the lock has been cleared and
 573 * finally free the lock.
 574 */
 575static void locks_delete_lock(struct file_lock **thisfl_p)
 576{
 577        struct file_lock *fl = *thisfl_p;
 578
 579        *thisfl_p = fl->fl_next;
 580        fl->fl_next = NULL;
 581        list_del_init(&fl->fl_link);
 582
 583        fasync_helper(0, fl->fl_file, 0, &fl->fl_fasync);
 584        if (fl->fl_fasync != NULL) {
 585                printk(KERN_ERR "locks_delete_lock: fasync == %p\n", fl->fl_fasync);
 586                fl->fl_fasync = NULL;
 587        }
 588
 589        if (fl->fl_nspid) {
 590                put_pid(fl->fl_nspid);
 591                fl->fl_nspid = NULL;
 592        }
 593
 594        locks_wake_up_blocks(fl);
 595        locks_free_lock(fl);
 596}
 597
 598/* Determine if lock sys_fl blocks lock caller_fl. Common functionality
 599 * checks for shared/exclusive status of overlapping locks.
 600 */
 601static int locks_conflict(struct file_lock *caller_fl, struct file_lock *sys_fl)
 602{
 603        if (sys_fl->fl_type == F_WRLCK)
 604                return 1;
 605        if (caller_fl->fl_type == F_WRLCK)
 606                return 1;
 607        return 0;
 608}
 609
 610/* Determine if lock sys_fl blocks lock caller_fl. POSIX specific
 611 * checking before calling the locks_conflict().
 612 */
 613static int posix_locks_conflict(struct file_lock *caller_fl, struct file_lock *sys_fl)
 614{
 615        /* POSIX locks owned by the same process do not conflict with
 616         * each other.
 617         */
 618        if (!IS_POSIX(sys_fl) || posix_same_owner(caller_fl, sys_fl))
 619                return (0);
 620
 621        /* Check whether they overlap */
 622        if (!locks_overlap(caller_fl, sys_fl))
 623                return 0;
 624
 625        return (locks_conflict(caller_fl, sys_fl));
 626}
 627
 628/* Determine if lock sys_fl blocks lock caller_fl. FLOCK specific
 629 * checking before calling the locks_conflict().
 630 */
 631static int flock_locks_conflict(struct file_lock *caller_fl, struct file_lock *sys_fl)
 632{
 633        /* FLOCK locks referring to the same filp do not conflict with
 634         * each other.
 635         */
 636        if (!IS_FLOCK(sys_fl) || (caller_fl->fl_file == sys_fl->fl_file))
 637                return (0);
 638        if ((caller_fl->fl_type & LOCK_MAND) || (sys_fl->fl_type & LOCK_MAND))
 639                return 0;
 640
 641        return (locks_conflict(caller_fl, sys_fl));
 642}
 643
 644void
 645posix_test_lock(struct file *filp, struct file_lock *fl)
 646{
 647        struct file_lock *cfl;
 648
 649        lock_flocks();
 650        for (cfl = filp->f_path.dentry->d_inode->i_flock; cfl; cfl = cfl->fl_next) {
 651                if (!IS_POSIX(cfl))
 652                        continue;
 653                if (posix_locks_conflict(fl, cfl))
 654                        break;
 655        }
 656        if (cfl) {
 657                __locks_copy_lock(fl, cfl);
 658                if (cfl->fl_nspid)
 659                        fl->fl_pid = pid_vnr(cfl->fl_nspid);
 660        } else
 661                fl->fl_type = F_UNLCK;
 662        unlock_flocks();
 663        return;
 664}
 665EXPORT_SYMBOL(posix_test_lock);
 666
 667/*
 668 * Deadlock detection:
 669 *
 670 * We attempt to detect deadlocks that are due purely to posix file
 671 * locks.
 672 *
 673 * We assume that a task can be waiting for at most one lock at a time.
 674 * So for any acquired lock, the process holding that lock may be
 675 * waiting on at most one other lock.  That lock in turns may be held by
 676 * someone waiting for at most one other lock.  Given a requested lock
 677 * caller_fl which is about to wait for a conflicting lock block_fl, we
 678 * follow this chain of waiters to ensure we are not about to create a
 679 * cycle.
 680 *
 681 * Since we do this before we ever put a process to sleep on a lock, we
 682 * are ensured that there is never a cycle; that is what guarantees that
 683 * the while() loop in posix_locks_deadlock() eventually completes.
 684 *
 685 * Note: the above assumption may not be true when handling lock
 686 * requests from a broken NFS client. It may also fail in the presence
 687 * of tasks (such as posix threads) sharing the same open file table.
 688 *
 689 * To handle those cases, we just bail out after a few iterations.
 690 */
 691
 692#define MAX_DEADLK_ITERATIONS 10
 693
 694/* Find a lock that the owner of the given block_fl is blocking on. */
 695static struct file_lock *what_owner_is_waiting_for(struct file_lock *block_fl)
 696{
 697        struct file_lock *fl;
 698
 699        list_for_each_entry(fl, &blocked_list, fl_link) {
 700                if (posix_same_owner(fl, block_fl))
 701                        return fl->fl_next;
 702        }
 703        return NULL;
 704}
 705
 706static int posix_locks_deadlock(struct file_lock *caller_fl,
 707                                struct file_lock *block_fl)
 708{
 709        int i = 0;
 710
 711        while ((block_fl = what_owner_is_waiting_for(block_fl))) {
 712                if (i++ > MAX_DEADLK_ITERATIONS)
 713                        return 0;
 714                if (posix_same_owner(caller_fl, block_fl))
 715                        return 1;
 716        }
 717        return 0;
 718}
 719
 720/* Try to create a FLOCK lock on filp. We always insert new FLOCK locks
 721 * after any leases, but before any posix locks.
 722 *
 723 * Note that if called with an FL_EXISTS argument, the caller may determine
 724 * whether or not a lock was successfully freed by testing the return
 725 * value for -ENOENT.
 726 */
 727static int flock_lock_file(struct file *filp, struct file_lock *request)
 728{
 729        struct file_lock *new_fl = NULL;
 730        struct file_lock **before;
 731        struct inode * inode = filp->f_path.dentry->d_inode;
 732        int error = 0;
 733        int found = 0;
 734
 735        if (!(request->fl_flags & FL_ACCESS) && (request->fl_type != F_UNLCK)) {
 736                new_fl = locks_alloc_lock();
 737                if (!new_fl)
 738                        return -ENOMEM;
 739        }
 740
 741        lock_flocks();
 742        if (request->fl_flags & FL_ACCESS)
 743                goto find_conflict;
 744
 745        for_each_lock(inode, before) {
 746                struct file_lock *fl = *before;
 747                if (IS_POSIX(fl))
 748                        break;
 749                if (IS_LEASE(fl))
 750                        continue;
 751                if (filp != fl->fl_file)
 752                        continue;
 753                if (request->fl_type == fl->fl_type)
 754                        goto out;
 755                found = 1;
 756                locks_delete_lock(before);
 757                break;
 758        }
 759
 760        if (request->fl_type == F_UNLCK) {
 761                if ((request->fl_flags & FL_EXISTS) && !found)
 762                        error = -ENOENT;
 763                goto out;
 764        }
 765
 766        /*
 767         * If a higher-priority process was blocked on the old file lock,
 768         * give it the opportunity to lock the file.
 769         */
 770        if (found) {
 771                unlock_flocks();
 772                cond_resched();
 773                lock_flocks();
 774        }
 775
 776find_conflict:
 777        for_each_lock(inode, before) {
 778                struct file_lock *fl = *before;
 779                if (IS_POSIX(fl))
 780                        break;
 781                if (IS_LEASE(fl))
 782                        continue;
 783                if (!flock_locks_conflict(request, fl))
 784                        continue;
 785                error = -EAGAIN;
 786                if (!(request->fl_flags & FL_SLEEP))
 787                        goto out;
 788                error = FILE_LOCK_DEFERRED;
 789                locks_insert_block(fl, request);
 790                goto out;
 791        }
 792        if (request->fl_flags & FL_ACCESS)
 793                goto out;
 794        locks_copy_lock(new_fl, request);
 795        locks_insert_lock(before, new_fl);
 796        new_fl = NULL;
 797        error = 0;
 798
 799out:
 800        unlock_flocks();
 801        if (new_fl)
 802                locks_free_lock(new_fl);
 803        return error;
 804}
 805
 806static int __posix_lock_file(struct inode *inode, struct file_lock *request, struct file_lock *conflock)
 807{
 808        struct file_lock *fl;
 809        struct file_lock *new_fl = NULL;
 810        struct file_lock *new_fl2 = NULL;
 811        struct file_lock *left = NULL;
 812        struct file_lock *right = NULL;
 813        struct file_lock **before;
 814        int error, added = 0;
 815
 816        /*
 817         * We may need two file_lock structures for this operation,
 818         * so we get them in advance to avoid races.
 819         *
 820         * In some cases we can be sure, that no new locks will be needed
 821         */
 822        if (!(request->fl_flags & FL_ACCESS) &&
 823            (request->fl_type != F_UNLCK ||
 824             request->fl_start != 0 || request->fl_end != OFFSET_MAX)) {
 825                new_fl = locks_alloc_lock();
 826                new_fl2 = locks_alloc_lock();
 827        }
 828
 829        lock_flocks();
 830        if (request->fl_type != F_UNLCK) {
 831                for_each_lock(inode, before) {
 832                        fl = *before;
 833                        if (!IS_POSIX(fl))
 834                                continue;
 835                        if (!posix_locks_conflict(request, fl))
 836                                continue;
 837                        if (conflock)
 838                                __locks_copy_lock(conflock, fl);
 839                        error = -EAGAIN;
 840                        if (!(request->fl_flags & FL_SLEEP))
 841                                goto out;
 842                        error = -EDEADLK;
 843                        if (posix_locks_deadlock(request, fl))
 844                                goto out;
 845                        error = FILE_LOCK_DEFERRED;
 846                        locks_insert_block(fl, request);
 847                        goto out;
 848                }
 849        }
 850
 851        /* If we're just looking for a conflict, we're done. */
 852        error = 0;
 853        if (request->fl_flags & FL_ACCESS)
 854                goto out;
 855
 856        /*
 857         * Find the first old lock with the same owner as the new lock.
 858         */
 859        
 860        before = &inode->i_flock;
 861
 862        /* First skip locks owned by other processes.  */
 863        while ((fl = *before) && (!IS_POSIX(fl) ||
 864                                  !posix_same_owner(request, fl))) {
 865                before = &fl->fl_next;
 866        }
 867
 868        /* Process locks with this owner.  */
 869        while ((fl = *before) && posix_same_owner(request, fl)) {
 870                /* Detect adjacent or overlapping regions (if same lock type)
 871                 */
 872                if (request->fl_type == fl->fl_type) {
 873                        /* In all comparisons of start vs end, use
 874                         * "start - 1" rather than "end + 1". If end
 875                         * is OFFSET_MAX, end + 1 will become negative.
 876                         */
 877                        if (fl->fl_end < request->fl_start - 1)
 878                                goto next_lock;
 879                        /* If the next lock in the list has entirely bigger
 880                         * addresses than the new one, insert the lock here.
 881                         */
 882                        if (fl->fl_start - 1 > request->fl_end)
 883                                break;
 884
 885                        /* If we come here, the new and old lock are of the
 886                         * same type and adjacent or overlapping. Make one
 887                         * lock yielding from the lower start address of both
 888                         * locks to the higher end address.
 889                         */
 890                        if (fl->fl_start > request->fl_start)
 891                                fl->fl_start = request->fl_start;
 892                        else
 893                                request->fl_start = fl->fl_start;
 894                        if (fl->fl_end < request->fl_end)
 895                                fl->fl_end = request->fl_end;
 896                        else
 897                                request->fl_end = fl->fl_end;
 898                        if (added) {
 899                                locks_delete_lock(before);
 900                                continue;
 901                        }
 902                        request = fl;
 903                        added = 1;
 904                }
 905                else {
 906                        /* Processing for different lock types is a bit
 907                         * more complex.
 908                         */
 909                        if (fl->fl_end < request->fl_start)
 910                                goto next_lock;
 911                        if (fl->fl_start > request->fl_end)
 912                                break;
 913                        if (request->fl_type == F_UNLCK)
 914                                added = 1;
 915                        if (fl->fl_start < request->fl_start)
 916                                left = fl;
 917                        /* If the next lock in the list has a higher end
 918                         * address than the new one, insert the new one here.
 919                         */
 920                        if (fl->fl_end > request->fl_end) {
 921                                right = fl;
 922                                break;
 923                        }
 924                        if (fl->fl_start >= request->fl_start) {
 925                                /* The new lock completely replaces an old
 926                                 * one (This may happen several times).
 927                                 */
 928                                if (added) {
 929                                        locks_delete_lock(before);
 930                                        continue;
 931                                }
 932                                /* Replace the old lock with the new one.
 933                                 * Wake up anybody waiting for the old one,
 934                                 * as the change in lock type might satisfy
 935                                 * their needs.
 936                                 */
 937                                locks_wake_up_blocks(fl);
 938                                fl->fl_start = request->fl_start;
 939                                fl->fl_end = request->fl_end;
 940                                fl->fl_type = request->fl_type;
 941                                locks_release_private(fl);
 942                                locks_copy_private(fl, request);
 943                                request = fl;
 944                                added = 1;
 945                        }
 946                }
 947                /* Go on to next lock.
 948                 */
 949        next_lock:
 950                before = &fl->fl_next;
 951        }
 952
 953        /*
 954         * The above code only modifies existing locks in case of
 955         * merging or replacing.  If new lock(s) need to be inserted
 956         * all modifications are done bellow this, so it's safe yet to
 957         * bail out.
 958         */
 959        error = -ENOLCK; /* "no luck" */
 960        if (right && left == right && !new_fl2)
 961                goto out;
 962
 963        error = 0;
 964        if (!added) {
 965                if (request->fl_type == F_UNLCK) {
 966                        if (request->fl_flags & FL_EXISTS)
 967                                error = -ENOENT;
 968                        goto out;
 969                }
 970
 971                if (!new_fl) {
 972                        error = -ENOLCK;
 973                        goto out;
 974                }
 975                locks_copy_lock(new_fl, request);
 976                locks_insert_lock(before, new_fl);
 977                new_fl = NULL;
 978        }
 979        if (right) {
 980                if (left == right) {
 981                        /* The new lock breaks the old one in two pieces,
 982                         * so we have to use the second new lock.
 983                         */
 984                        left = new_fl2;
 985                        new_fl2 = NULL;
 986                        locks_copy_lock(left, right);
 987                        locks_insert_lock(before, left);
 988                }
 989                right->fl_start = request->fl_end + 1;
 990                locks_wake_up_blocks(right);
 991        }
 992        if (left) {
 993                left->fl_end = request->fl_start - 1;
 994                locks_wake_up_blocks(left);
 995        }
 996 out:
 997        unlock_flocks();
 998        /*
 999         * Free any unused locks.
1000         */
1001        if (new_fl)
1002                locks_free_lock(new_fl);
1003        if (new_fl2)
1004                locks_free_lock(new_fl2);
1005        return error;
1006}
1007
1008/**
1009 * posix_lock_file - Apply a POSIX-style lock to a file
1010 * @filp: The file to apply the lock to
1011 * @fl: The lock to be applied
1012 * @conflock: Place to return a copy of the conflicting lock, if found.
1013 *
1014 * Add a POSIX style lock to a file.
1015 * We merge adjacent & overlapping locks whenever possible.
1016 * POSIX locks are sorted by owner task, then by starting address
1017 *
1018 * Note that if called with an FL_EXISTS argument, the caller may determine
1019 * whether or not a lock was successfully freed by testing the return
1020 * value for -ENOENT.
1021 */
1022int posix_lock_file(struct file *filp, struct file_lock *fl,
1023                        struct file_lock *conflock)
1024{
1025        return __posix_lock_file(filp->f_path.dentry->d_inode, fl, conflock);
1026}
1027EXPORT_SYMBOL(posix_lock_file);
1028
1029/**
1030 * posix_lock_file_wait - Apply a POSIX-style lock to a file
1031 * @filp: The file to apply the lock to
1032 * @fl: The lock to be applied
1033 *
1034 * Add a POSIX style lock to a file.
1035 * We merge adjacent & overlapping locks whenever possible.
1036 * POSIX locks are sorted by owner task, then by starting address
1037 */
1038int posix_lock_file_wait(struct file *filp, struct file_lock *fl)
1039{
1040        int error;
1041        might_sleep ();
1042        for (;;) {
1043                error = posix_lock_file(filp, fl, NULL);
1044                if (error != FILE_LOCK_DEFERRED)
1045                        break;
1046                error = wait_event_interruptible(fl->fl_wait, !fl->fl_next);
1047                if (!error)
1048                        continue;
1049
1050                locks_delete_block(fl);
1051                break;
1052        }
1053        return error;
1054}
1055EXPORT_SYMBOL(posix_lock_file_wait);
1056
1057/**
1058 * locks_mandatory_locked - Check for an active lock
1059 * @inode: the file to check
1060 *
1061 * Searches the inode's list of locks to find any POSIX locks which conflict.
1062 * This function is called from locks_verify_locked() only.
1063 */
1064int locks_mandatory_locked(struct inode *inode)
1065{
1066        fl_owner_t owner = current->files;
1067        struct file_lock *fl;
1068
1069        /*
1070         * Search the lock list for this inode for any POSIX locks.
1071         */
1072        lock_flocks();
1073        for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) {
1074                if (!IS_POSIX(fl))
1075                        continue;
1076                if (fl->fl_owner != owner)
1077                        break;
1078        }
1079        unlock_flocks();
1080        return fl ? -EAGAIN : 0;
1081}
1082
1083/**
1084 * locks_mandatory_area - Check for a conflicting lock
1085 * @read_write: %FLOCK_VERIFY_WRITE for exclusive access, %FLOCK_VERIFY_READ
1086 *              for shared
1087 * @inode:      the file to check
1088 * @filp:       how the file was opened (if it was)
1089 * @offset:     start of area to check
1090 * @count:      length of area to check
1091 *
1092 * Searches the inode's list of locks to find any POSIX locks which conflict.
1093 * This function is called from rw_verify_area() and
1094 * locks_verify_truncate().
1095 */
1096int locks_mandatory_area(int read_write, struct inode *inode,
1097                         struct file *filp, loff_t offset,
1098                         size_t count)
1099{
1100        struct file_lock fl;
1101        int error;
1102
1103        locks_init_lock(&fl);
1104        fl.fl_owner = current->files;
1105        fl.fl_pid = current->tgid;
1106        fl.fl_file = filp;
1107        fl.fl_flags = FL_POSIX | FL_ACCESS;
1108        if (filp && !(filp->f_flags & O_NONBLOCK))
1109                fl.fl_flags |= FL_SLEEP;
1110        fl.fl_type = (read_write == FLOCK_VERIFY_WRITE) ? F_WRLCK : F_RDLCK;
1111        fl.fl_start = offset;
1112        fl.fl_end = offset + count - 1;
1113
1114        for (;;) {
1115                error = __posix_lock_file(inode, &fl, NULL);
1116                if (error != FILE_LOCK_DEFERRED)
1117                        break;
1118                error = wait_event_interruptible(fl.fl_wait, !fl.fl_next);
1119                if (!error) {
1120                        /*
1121                         * If we've been sleeping someone might have
1122                         * changed the permissions behind our back.
1123                         */
1124                        if (__mandatory_lock(inode))
1125                                continue;
1126                }
1127
1128                locks_delete_block(&fl);
1129                break;
1130        }
1131
1132        return error;
1133}
1134
1135EXPORT_SYMBOL(locks_mandatory_area);
1136
1137static void lease_clear_pending(struct file_lock *fl, int arg)
1138{
1139        switch (arg) {
1140        case F_UNLCK:
1141                fl->fl_flags &= ~FL_UNLOCK_PENDING;
1142                /* fall through: */
1143        case F_RDLCK:
1144                fl->fl_flags &= ~FL_DOWNGRADE_PENDING;
1145        }
1146}
1147
1148/* We already had a lease on this file; just change its type */
1149int lease_modify(struct file_lock **before, int arg)
1150{
1151        struct file_lock *fl = *before;
1152        int error = assign_type(fl, arg);
1153
1154        if (error)
1155                return error;
1156        lease_clear_pending(fl, arg);
1157        locks_wake_up_blocks(fl);
1158        if (arg == F_UNLCK)
1159                locks_delete_lock(before);
1160        return 0;
1161}
1162
1163EXPORT_SYMBOL(lease_modify);
1164
1165static bool past_time(unsigned long then)
1166{
1167        if (!then)
1168                /* 0 is a special value meaning "this never expires": */
1169                return false;
1170        return time_after(jiffies, then);
1171}
1172
1173static void time_out_leases(struct inode *inode)
1174{
1175        struct file_lock **before;
1176        struct file_lock *fl;
1177
1178        before = &inode->i_flock;
1179        while ((fl = *before) && IS_LEASE(fl) && lease_breaking(fl)) {
1180                if (past_time(fl->fl_downgrade_time))
1181                        lease_modify(before, F_RDLCK);
1182                if (past_time(fl->fl_break_time))
1183                        lease_modify(before, F_UNLCK);
1184                if (fl == *before)      /* lease_modify may have freed fl */
1185                        before = &fl->fl_next;
1186        }
1187}
1188
1189/**
1190 *      __break_lease   -       revoke all outstanding leases on file
1191 *      @inode: the inode of the file to return
1192 *      @mode: the open mode (read or write)
1193 *
1194 *      break_lease (inlined for speed) has checked there already is at least
1195 *      some kind of lock (maybe a lease) on this file.  Leases are broken on
1196 *      a call to open() or truncate().  This function can sleep unless you
1197 *      specified %O_NONBLOCK to your open().
1198 */
1199int __break_lease(struct inode *inode, unsigned int mode)
1200{
1201        int error = 0;
1202        struct file_lock *new_fl, *flock;
1203        struct file_lock *fl;
1204        unsigned long break_time;
1205        int i_have_this_lease = 0;
1206        int want_write = (mode & O_ACCMODE) != O_RDONLY;
1207
1208        new_fl = lease_alloc(NULL, want_write ? F_WRLCK : F_RDLCK);
1209        if (IS_ERR(new_fl))
1210                return PTR_ERR(new_fl);
1211
1212        lock_flocks();
1213
1214        time_out_leases(inode);
1215
1216        flock = inode->i_flock;
1217        if ((flock == NULL) || !IS_LEASE(flock))
1218                goto out;
1219
1220        if (!locks_conflict(flock, new_fl))
1221                goto out;
1222
1223        for (fl = flock; fl && IS_LEASE(fl); fl = fl->fl_next)
1224                if (fl->fl_owner == current->files)
1225                        i_have_this_lease = 1;
1226
1227        break_time = 0;
1228        if (lease_break_time > 0) {
1229                break_time = jiffies + lease_break_time * HZ;
1230                if (break_time == 0)
1231                        break_time++;   /* so that 0 means no break time */
1232        }
1233
1234        for (fl = flock; fl && IS_LEASE(fl); fl = fl->fl_next) {
1235                if (want_write) {
1236                        if (fl->fl_flags & FL_UNLOCK_PENDING)
1237                                continue;
1238                        fl->fl_flags |= FL_UNLOCK_PENDING;
1239                        fl->fl_break_time = break_time;
1240                } else {
1241                        if (lease_breaking(flock))
1242                                continue;
1243                        fl->fl_flags |= FL_DOWNGRADE_PENDING;
1244                        fl->fl_downgrade_time = break_time;
1245                }
1246                fl->fl_lmops->lm_break(fl);
1247        }
1248
1249        if (i_have_this_lease || (mode & O_NONBLOCK)) {
1250                error = -EWOULDBLOCK;
1251                goto out;
1252        }
1253
1254restart:
1255        break_time = flock->fl_break_time;
1256        if (break_time != 0) {
1257                break_time -= jiffies;
1258                if (break_time == 0)
1259                        break_time++;
1260        }
1261        locks_insert_block(flock, new_fl);
1262        unlock_flocks();
1263        error = wait_event_interruptible_timeout(new_fl->fl_wait,
1264                                                !new_fl->fl_next, break_time);
1265        lock_flocks();
1266        __locks_delete_block(new_fl);
1267        if (error >= 0) {
1268                if (error == 0)
1269                        time_out_leases(inode);
1270                /*
1271                 * Wait for the next conflicting lease that has not been
1272                 * broken yet
1273                 */
1274                for (flock = inode->i_flock; flock && IS_LEASE(flock);
1275                                flock = flock->fl_next) {
1276                        if (locks_conflict(new_fl, flock))
1277                                goto restart;
1278                }
1279                error = 0;
1280        }
1281
1282out:
1283        unlock_flocks();
1284        locks_free_lock(new_fl);
1285        return error;
1286}
1287
1288EXPORT_SYMBOL(__break_lease);
1289
1290/**
1291 *      lease_get_mtime - get the last modified time of an inode
1292 *      @inode: the inode
1293 *      @time:  pointer to a timespec which will contain the last modified time
1294 *
1295 * This is to force NFS clients to flush their caches for files with
1296 * exclusive leases.  The justification is that if someone has an
1297 * exclusive lease, then they could be modifying it.
1298 */
1299void lease_get_mtime(struct inode *inode, struct timespec *time)
1300{
1301        struct file_lock *flock = inode->i_flock;
1302        if (flock && IS_LEASE(flock) && (flock->fl_type & F_WRLCK))
1303                *time = current_fs_time(inode->i_sb);
1304        else
1305                *time = inode->i_mtime;
1306}
1307
1308EXPORT_SYMBOL(lease_get_mtime);
1309
1310/**
1311 *      fcntl_getlease - Enquire what lease is currently active
1312 *      @filp: the file
1313 *
1314 *      The value returned by this function will be one of
1315 *      (if no lease break is pending):
1316 *
1317 *      %F_RDLCK to indicate a shared lease is held.
1318 *
1319 *      %F_WRLCK to indicate an exclusive lease is held.
1320 *
1321 *      %F_UNLCK to indicate no lease is held.
1322 *
1323 *      (if a lease break is pending):
1324 *
1325 *      %F_RDLCK to indicate an exclusive lease needs to be
1326 *              changed to a shared lease (or removed).
1327 *
1328 *      %F_UNLCK to indicate the lease needs to be removed.
1329 *
1330 *      XXX: sfr & willy disagree over whether F_INPROGRESS
1331 *      should be returned to userspace.
1332 */
1333int fcntl_getlease(struct file *filp)
1334{
1335        struct file_lock *fl;
1336        int type = F_UNLCK;
1337
1338        lock_flocks();
1339        time_out_leases(filp->f_path.dentry->d_inode);
1340        for (fl = filp->f_path.dentry->d_inode->i_flock; fl && IS_LEASE(fl);
1341                        fl = fl->fl_next) {
1342                if (fl->fl_file == filp) {
1343                        type = target_leasetype(fl);
1344                        break;
1345                }
1346        }
1347        unlock_flocks();
1348        return type;
1349}
1350
1351int generic_add_lease(struct file *filp, long arg, struct file_lock **flp)
1352{
1353        struct file_lock *fl, **before, **my_before = NULL, *lease;
1354        struct dentry *dentry = filp->f_path.dentry;
1355        struct inode *inode = dentry->d_inode;
1356        int error;
1357
1358        lease = *flp;
1359
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         * At this point, we know that if there is an exclusive
1370         * lease on this file, then we hold it on this filp
1371         * (otherwise our open of this file would have blocked).
1372         * And if we are trying to acquire an exclusive lease,
1373         * then the file is not open by anyone (including us)
1374         * except for this filp.
1375         */
1376        error = -EAGAIN;
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                        continue;
1383                }
1384                /*
1385                 * No exclusive leases if someone else has a lease on
1386                 * this file:
1387                 */
1388                if (arg == F_WRLCK)
1389                        goto out;
1390                /*
1391                 * Modifying our existing lease is OK, but no getting a
1392                 * new lease if someone else is opening for write:
1393                 */
1394                if (fl->fl_flags & FL_UNLOCK_PENDING)
1395                        goto out;
1396        }
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        error = -EINVAL;
1406        if (!leases_enable)
1407                goto out;
1408
1409        locks_insert_lock(before, lease);
1410        return 0;
1411
1412out:
1413        return error;
1414}
1415
1416int generic_delete_lease(struct file *filp, struct file_lock **flp)
1417{
1418        struct file_lock *fl, **before;
1419        struct dentry *dentry = filp->f_path.dentry;
1420        struct inode *inode = dentry->d_inode;
1421
1422        for (before = &inode->i_flock;
1423                        ((fl = *before) != NULL) && IS_LEASE(fl);
1424                        before = &fl->fl_next) {
1425                if (fl->fl_file != filp)
1426                        continue;
1427                return (*flp)->fl_lmops->lm_change(before, F_UNLCK);
1428        }
1429        return -EAGAIN;
1430}
1431
1432/**
1433 *      generic_setlease        -       sets a lease on an open file
1434 *      @filp: file pointer
1435 *      @arg: type of lease to obtain
1436 *      @flp: input - file_lock to use, output - file_lock inserted
1437 *
1438 *      The (input) flp->fl_lmops->lm_break function is required
1439 *      by break_lease().
1440 *
1441 *      Called with file_lock_lock held.
1442 */
1443int generic_setlease(struct file *filp, long arg, struct file_lock **flp)
1444{
1445        struct dentry *dentry = filp->f_path.dentry;
1446        struct inode *inode = dentry->d_inode;
1447        int error;
1448
1449        if ((!uid_eq(current_fsuid(), inode->i_uid)) && !capable(CAP_LEASE))
1450                return -EACCES;
1451        if (!S_ISREG(inode->i_mode))
1452                return -EINVAL;
1453        error = security_file_lock(filp, arg);
1454        if (error)
1455                return error;
1456
1457        time_out_leases(inode);
1458
1459        BUG_ON(!(*flp)->fl_lmops->lm_break);
1460
1461        switch (arg) {
1462        case F_UNLCK:
1463                return generic_delete_lease(filp, flp);
1464        case F_RDLCK:
1465        case F_WRLCK:
1466                return generic_add_lease(filp, arg, flp);
1467        default:
1468                return -EINVAL;
1469        }
1470}
1471EXPORT_SYMBOL(generic_setlease);
1472
1473static int __vfs_setlease(struct file *filp, long arg, struct file_lock **lease)
1474{
1475        if (filp->f_op && filp->f_op->setlease)
1476                return filp->f_op->setlease(filp, arg, lease);
1477        else
1478                return generic_setlease(filp, arg, lease);
1479}
1480
1481/**
1482 *      vfs_setlease        -       sets a lease on an open file
1483 *      @filp: file pointer
1484 *      @arg: type of lease to obtain
1485 *      @lease: file_lock to use
1486 *
1487 *      Call this to establish a lease on the file.
1488 *      The (*lease)->fl_lmops->lm_break operation must be set; if not,
1489 *      break_lease will oops!
1490 *
1491 *      This will call the filesystem's setlease file method, if
1492 *      defined.  Note that there is no getlease method; instead, the
1493 *      filesystem setlease method should call back to setlease() to
1494 *      add a lease to the inode's lease list, where fcntl_getlease() can
1495 *      find it.  Since fcntl_getlease() only reports whether the current
1496 *      task holds a lease, a cluster filesystem need only do this for
1497 *      leases held by processes on this node.
1498 *
1499 *      There is also no break_lease method; filesystems that
1500 *      handle their own leases should break leases themselves from the
1501 *      filesystem's open, create, and (on truncate) setattr methods.
1502 *
1503 *      Warning: the only current setlease methods exist only to disable
1504 *      leases in certain cases.  More vfs changes may be required to
1505 *      allow a full filesystem lease implementation.
1506 */
1507
1508int vfs_setlease(struct file *filp, long arg, struct file_lock **lease)
1509{
1510        int error;
1511
1512        lock_flocks();
1513        error = __vfs_setlease(filp, arg, lease);
1514        unlock_flocks();
1515
1516        return error;
1517}
1518EXPORT_SYMBOL_GPL(vfs_setlease);
1519
1520static int do_fcntl_delete_lease(struct file *filp)
1521{
1522        struct file_lock fl, *flp = &fl;
1523
1524        lease_init(filp, F_UNLCK, flp);
1525
1526        return vfs_setlease(filp, F_UNLCK, &flp);
1527}
1528
1529static int do_fcntl_add_lease(unsigned int fd, struct file *filp, long arg)
1530{
1531        struct file_lock *fl, *ret;
1532        struct fasync_struct *new;
1533        int error;
1534
1535        fl = lease_alloc(filp, arg);
1536        if (IS_ERR(fl))
1537                return PTR_ERR(fl);
1538
1539        new = fasync_alloc();
1540        if (!new) {
1541                locks_free_lock(fl);
1542                return -ENOMEM;
1543        }
1544        ret = fl;
1545        lock_flocks();
1546        error = __vfs_setlease(filp, arg, &ret);
1547        if (error) {
1548                unlock_flocks();
1549                locks_free_lock(fl);
1550                goto out_free_fasync;
1551        }
1552        if (ret != fl)
1553                locks_free_lock(fl);
1554
1555        /*
1556         * fasync_insert_entry() returns the old entry if any.
1557         * If there was no old entry, then it used 'new' and
1558         * inserted it into the fasync list. Clear new so that
1559         * we don't release it here.
1560         */
1561        if (!fasync_insert_entry(fd, filp, &ret->fl_fasync, new))
1562                new = NULL;
1563
1564        error = __f_setown(filp, task_pid(current), PIDTYPE_PID, 0);
1565        unlock_flocks();
1566
1567out_free_fasync:
1568        if (new)
1569                fasync_free(new);
1570        return error;
1571}
1572
1573/**
1574 *      fcntl_setlease  -       sets a lease on an open file
1575 *      @fd: open file descriptor
1576 *      @filp: file pointer
1577 *      @arg: type of lease to obtain
1578 *
1579 *      Call this fcntl to establish a lease on the file.
1580 *      Note that you also need to call %F_SETSIG to
1581 *      receive a signal when the lease is broken.
1582 */
1583int fcntl_setlease(unsigned int fd, struct file *filp, long arg)
1584{
1585        if (arg == F_UNLCK)
1586                return do_fcntl_delete_lease(filp);
1587        return do_fcntl_add_lease(fd, filp, arg);
1588}
1589
1590/**
1591 * flock_lock_file_wait - Apply a FLOCK-style lock to a file
1592 * @filp: The file to apply the lock to
1593 * @fl: The lock to be applied
1594 *
1595 * Add a FLOCK style lock to a file.
1596 */
1597int flock_lock_file_wait(struct file *filp, struct file_lock *fl)
1598{
1599        int error;
1600        might_sleep();
1601        for (;;) {
1602                error = flock_lock_file(filp, fl);
1603                if (error != FILE_LOCK_DEFERRED)
1604                        break;
1605                error = wait_event_interruptible(fl->fl_wait, !fl->fl_next);
1606                if (!error)
1607                        continue;
1608
1609                locks_delete_block(fl);
1610                break;
1611        }
1612        return error;
1613}
1614
1615EXPORT_SYMBOL(flock_lock_file_wait);
1616
1617/**
1618 *      sys_flock: - flock() system call.
1619 *      @fd: the file descriptor to lock.
1620 *      @cmd: the type of lock to apply.
1621 *
1622 *      Apply a %FL_FLOCK style lock to an open file descriptor.
1623 *      The @cmd can be one of
1624 *
1625 *      %LOCK_SH -- a shared lock.
1626 *
1627 *      %LOCK_EX -- an exclusive lock.
1628 *
1629 *      %LOCK_UN -- remove an existing lock.
1630 *
1631 *      %LOCK_MAND -- a `mandatory' flock.  This exists to emulate Windows Share Modes.
1632 *
1633 *      %LOCK_MAND can be combined with %LOCK_READ or %LOCK_WRITE to allow other
1634 *      processes read and write access respectively.
1635 */
1636SYSCALL_DEFINE2(flock, unsigned int, fd, unsigned int, cmd)
1637{
1638        struct file *filp;
1639        int fput_needed;
1640        struct file_lock *lock;
1641        int can_sleep, unlock;
1642        int error;
1643
1644        error = -EBADF;
1645        filp = fget_light(fd, &fput_needed);
1646        if (!filp)
1647                goto out;
1648
1649        can_sleep = !(cmd & LOCK_NB);
1650        cmd &= ~LOCK_NB;
1651        unlock = (cmd == LOCK_UN);
1652
1653        if (!unlock && !(cmd & LOCK_MAND) &&
1654            !(filp->f_mode & (FMODE_READ|FMODE_WRITE)))
1655                goto out_putf;
1656
1657        error = flock_make_lock(filp, &lock, cmd);
1658        if (error)
1659                goto out_putf;
1660        if (can_sleep)
1661                lock->fl_flags |= FL_SLEEP;
1662
1663        error = security_file_lock(filp, lock->fl_type);
1664        if (error)
1665                goto out_free;
1666
1667        if (filp->f_op && filp->f_op->flock)
1668                error = filp->f_op->flock(filp,
1669                                          (can_sleep) ? F_SETLKW : F_SETLK,
1670                                          lock);
1671        else
1672                error = flock_lock_file_wait(filp, lock);
1673
1674 out_free:
1675        locks_free_lock(lock);
1676
1677 out_putf:
1678        fput_light(filp, fput_needed);
1679 out:
1680        return error;
1681}
1682
1683/**
1684 * vfs_test_lock - test file byte range lock
1685 * @filp: The file to test lock for
1686 * @fl: The lock to test; also used to hold result
1687 *
1688 * Returns -ERRNO on failure.  Indicates presence of conflicting lock by
1689 * setting conf->fl_type to something other than F_UNLCK.
1690 */
1691int vfs_test_lock(struct file *filp, struct file_lock *fl)
1692{
1693        if (filp->f_op && filp->f_op->lock)
1694                return filp->f_op->lock(filp, F_GETLK, fl);
1695        posix_test_lock(filp, fl);
1696        return 0;
1697}
1698EXPORT_SYMBOL_GPL(vfs_test_lock);
1699
1700static int posix_lock_to_flock(struct flock *flock, struct file_lock *fl)
1701{
1702        flock->l_pid = fl->fl_pid;
1703#if BITS_PER_LONG == 32
1704        /*
1705         * Make sure we can represent the posix lock via
1706         * legacy 32bit flock.
1707         */
1708        if (fl->fl_start > OFFT_OFFSET_MAX)
1709                return -EOVERFLOW;
1710        if (fl->fl_end != OFFSET_MAX && fl->fl_end > OFFT_OFFSET_MAX)
1711                return -EOVERFLOW;
1712#endif
1713        flock->l_start = fl->fl_start;
1714        flock->l_len = fl->fl_end == OFFSET_MAX ? 0 :
1715                fl->fl_end - fl->fl_start + 1;
1716        flock->l_whence = 0;
1717        flock->l_type = fl->fl_type;
1718        return 0;
1719}
1720
1721#if BITS_PER_LONG == 32
1722static void posix_lock_to_flock64(struct flock64 *flock, struct file_lock *fl)
1723{
1724        flock->l_pid = fl->fl_pid;
1725        flock->l_start = fl->fl_start;
1726        flock->l_len = fl->fl_end == OFFSET_MAX ? 0 :
1727                fl->fl_end - fl->fl_start + 1;
1728        flock->l_whence = 0;
1729        flock->l_type = fl->fl_type;
1730}
1731#endif
1732
1733/* Report the first existing lock that would conflict with l.
1734 * This implements the F_GETLK command of fcntl().
1735 */
1736int fcntl_getlk(struct file *filp, struct flock __user *l)
1737{
1738        struct file_lock file_lock;
1739        struct flock flock;
1740        int error;
1741
1742        error = -EFAULT;
1743        if (copy_from_user(&flock, l, sizeof(flock)))
1744                goto out;
1745        error = -EINVAL;
1746        if ((flock.l_type != F_RDLCK) && (flock.l_type != F_WRLCK))
1747                goto out;
1748
1749        error = flock_to_posix_lock(filp, &file_lock, &flock);
1750        if (error)
1751                goto out;
1752
1753        error = vfs_test_lock(filp, &file_lock);
1754        if (error)
1755                goto out;
1756 
1757        flock.l_type = file_lock.fl_type;
1758        if (file_lock.fl_type != F_UNLCK) {
1759                error = posix_lock_to_flock(&flock, &file_lock);
1760                if (error)
1761                        goto out;
1762        }
1763        error = -EFAULT;
1764        if (!copy_to_user(l, &flock, sizeof(flock)))
1765                error = 0;
1766out:
1767        return error;
1768}
1769
1770/**
1771 * vfs_lock_file - file byte range lock
1772 * @filp: The file to apply the lock to
1773 * @cmd: type of locking operation (F_SETLK, F_GETLK, etc.)
1774 * @fl: The lock to be applied
1775 * @conf: Place to return a copy of the conflicting lock, if found.
1776 *
1777 * A caller that doesn't care about the conflicting lock may pass NULL
1778 * as the final argument.
1779 *
1780 * If the filesystem defines a private ->lock() method, then @conf will
1781 * be left unchanged; so a caller that cares should initialize it to
1782 * some acceptable default.
1783 *
1784 * To avoid blocking kernel daemons, such as lockd, that need to acquire POSIX
1785 * locks, the ->lock() interface may return asynchronously, before the lock has
1786 * been granted or denied by the underlying filesystem, if (and only if)
1787 * lm_grant is set. Callers expecting ->lock() to return asynchronously
1788 * will only use F_SETLK, not F_SETLKW; they will set FL_SLEEP if (and only if)
1789 * the request is for a blocking lock. When ->lock() does return asynchronously,
1790 * it must return FILE_LOCK_DEFERRED, and call ->lm_grant() when the lock
1791 * request completes.
1792 * If the request is for non-blocking lock the file system should return
1793 * FILE_LOCK_DEFERRED then try to get the lock and call the callback routine
1794 * with the result. If the request timed out the callback routine will return a
1795 * nonzero return code and the file system should release the lock. The file
1796 * system is also responsible to keep a corresponding posix lock when it
1797 * grants a lock so the VFS can find out which locks are locally held and do
1798 * the correct lock cleanup when required.
1799 * The underlying filesystem must not drop the kernel lock or call
1800 * ->lm_grant() before returning to the caller with a FILE_LOCK_DEFERRED
1801 * return code.
1802 */
1803int vfs_lock_file(struct file *filp, unsigned int cmd, struct file_lock *fl, struct file_lock *conf)
1804{
1805        if (filp->f_op && filp->f_op->lock)
1806                return filp->f_op->lock(filp, cmd, fl);
1807        else
1808                return posix_lock_file(filp, fl, conf);
1809}
1810EXPORT_SYMBOL_GPL(vfs_lock_file);
1811
1812static int do_lock_file_wait(struct file *filp, unsigned int cmd,
1813                             struct file_lock *fl)
1814{
1815        int error;
1816
1817        error = security_file_lock(filp, fl->fl_type);
1818        if (error)
1819                return error;
1820
1821        for (;;) {
1822                error = vfs_lock_file(filp, cmd, fl, NULL);
1823                if (error != FILE_LOCK_DEFERRED)
1824                        break;
1825                error = wait_event_interruptible(fl->fl_wait, !fl->fl_next);
1826                if (!error)
1827                        continue;
1828
1829                locks_delete_block(fl);
1830                break;
1831        }
1832
1833        return error;
1834}
1835
1836/* Apply the lock described by l to an open file descriptor.
1837 * This implements both the F_SETLK and F_SETLKW commands of fcntl().
1838 */
1839int fcntl_setlk(unsigned int fd, struct file *filp, unsigned int cmd,
1840                struct flock __user *l)
1841{
1842        struct file_lock *file_lock = locks_alloc_lock();
1843        struct flock flock;
1844        struct inode *inode;
1845        struct file *f;
1846        int error;
1847
1848        if (file_lock == NULL)
1849                return -ENOLCK;
1850
1851        /*
1852         * This might block, so we do it before checking the inode.
1853         */
1854        error = -EFAULT;
1855        if (copy_from_user(&flock, l, sizeof(flock)))
1856                goto out;
1857
1858        inode = filp->f_path.dentry->d_inode;
1859
1860        /* Don't allow mandatory locks on files that may be memory mapped
1861         * and shared.
1862         */
1863        if (mandatory_lock(inode) && mapping_writably_mapped(filp->f_mapping)) {
1864                error = -EAGAIN;
1865                goto out;
1866        }
1867
1868again:
1869        error = flock_to_posix_lock(filp, file_lock, &flock);
1870        if (error)
1871                goto out;
1872        if (cmd == F_SETLKW) {
1873                file_lock->fl_flags |= FL_SLEEP;
1874        }
1875        
1876        error = -EBADF;
1877        switch (flock.l_type) {
1878        case F_RDLCK:
1879                if (!(filp->f_mode & FMODE_READ))
1880                        goto out;
1881                break;
1882        case F_WRLCK:
1883                if (!(filp->f_mode & FMODE_WRITE))
1884                        goto out;
1885                break;
1886        case F_UNLCK:
1887                break;
1888        default:
1889                error = -EINVAL;
1890                goto out;
1891        }
1892
1893        error = do_lock_file_wait(filp, cmd, file_lock);
1894
1895        /*
1896         * Attempt to detect a close/fcntl race and recover by
1897         * releasing the lock that was just acquired.
1898         */
1899        /*
1900         * we need that spin_lock here - it prevents reordering between
1901         * update of inode->i_flock and check for it done in close().
1902         * rcu_read_lock() wouldn't do.
1903         */
1904        spin_lock(&current->files->file_lock);
1905        f = fcheck(fd);
1906        spin_unlock(&current->files->file_lock);
1907        if (!error && f != filp && flock.l_type != F_UNLCK) {
1908                flock.l_type = F_UNLCK;
1909                goto again;
1910        }
1911
1912out:
1913        locks_free_lock(file_lock);
1914        return error;
1915}
1916
1917#if BITS_PER_LONG == 32
1918/* Report the first existing lock that would conflict with l.
1919 * This implements the F_GETLK command of fcntl().
1920 */
1921int fcntl_getlk64(struct file *filp, struct flock64 __user *l)
1922{
1923        struct file_lock file_lock;
1924        struct flock64 flock;
1925        int error;
1926
1927        error = -EFAULT;
1928        if (copy_from_user(&flock, l, sizeof(flock)))
1929                goto out;
1930        error = -EINVAL;
1931        if ((flock.l_type != F_RDLCK) && (flock.l_type != F_WRLCK))
1932                goto out;
1933
1934        error = flock64_to_posix_lock(filp, &file_lock, &flock);
1935        if (error)
1936                goto out;
1937
1938        error = vfs_test_lock(filp, &file_lock);
1939        if (error)
1940                goto out;
1941
1942        flock.l_type = file_lock.fl_type;
1943        if (file_lock.fl_type != F_UNLCK)
1944                posix_lock_to_flock64(&flock, &file_lock);
1945
1946        error = -EFAULT;
1947        if (!copy_to_user(l, &flock, sizeof(flock)))
1948                error = 0;
1949  
1950out:
1951        return error;
1952}
1953
1954/* Apply the lock described by l to an open file descriptor.
1955 * This implements both the F_SETLK and F_SETLKW commands of fcntl().
1956 */
1957int fcntl_setlk64(unsigned int fd, struct file *filp, unsigned int cmd,
1958                struct flock64 __user *l)
1959{
1960        struct file_lock *file_lock = locks_alloc_lock();
1961        struct flock64 flock;
1962        struct inode *inode;
1963        struct file *f;
1964        int error;
1965
1966        if (file_lock == NULL)
1967                return -ENOLCK;
1968
1969        /*
1970         * This might block, so we do it before checking the inode.
1971         */
1972        error = -EFAULT;
1973        if (copy_from_user(&flock, l, sizeof(flock)))
1974                goto out;
1975
1976        inode = filp->f_path.dentry->d_inode;
1977
1978        /* Don't allow mandatory locks on files that may be memory mapped
1979         * and shared.
1980         */
1981        if (mandatory_lock(inode) && mapping_writably_mapped(filp->f_mapping)) {
1982                error = -EAGAIN;
1983                goto out;
1984        }
1985
1986again:
1987        error = flock64_to_posix_lock(filp, file_lock, &flock);
1988        if (error)
1989                goto out;
1990        if (cmd == F_SETLKW64) {
1991                file_lock->fl_flags |= FL_SLEEP;
1992        }
1993        
1994        error = -EBADF;
1995        switch (flock.l_type) {
1996        case F_RDLCK:
1997                if (!(filp->f_mode & FMODE_READ))
1998                        goto out;
1999                break;
2000        case F_WRLCK:
2001                if (!(filp->f_mode & FMODE_WRITE))
2002                        goto out;
2003                break;
2004        case F_UNLCK:
2005                break;
2006        default:
2007                error = -EINVAL;
2008                goto out;
2009        }
2010
2011        error = do_lock_file_wait(filp, cmd, file_lock);
2012
2013        /*
2014         * Attempt to detect a close/fcntl race and recover by
2015         * releasing the lock that was just acquired.
2016         */
2017        spin_lock(&current->files->file_lock);
2018        f = fcheck(fd);
2019        spin_unlock(&current->files->file_lock);
2020        if (!error && f != filp && flock.l_type != F_UNLCK) {
2021                flock.l_type = F_UNLCK;
2022                goto again;
2023        }
2024
2025out:
2026        locks_free_lock(file_lock);
2027        return error;
2028}
2029#endif /* BITS_PER_LONG == 32 */
2030
2031/*
2032 * This function is called when the file is being removed
2033 * from the task's fd array.  POSIX locks belonging to this task
2034 * are deleted at this time.
2035 */
2036void locks_remove_posix(struct file *filp, fl_owner_t owner)
2037{
2038        struct file_lock lock;
2039
2040        /*
2041         * If there are no locks held on this file, we don't need to call
2042         * posix_lock_file().  Another process could be setting a lock on this
2043         * file at the same time, but we wouldn't remove that lock anyway.
2044         */
2045        if (!filp->f_path.dentry->d_inode->i_flock)
2046                return;
2047
2048        lock.fl_type = F_UNLCK;
2049        lock.fl_flags = FL_POSIX | FL_CLOSE;
2050        lock.fl_start = 0;
2051        lock.fl_end = OFFSET_MAX;
2052        lock.fl_owner = owner;
2053        lock.fl_pid = current->tgid;
2054        lock.fl_file = filp;
2055        lock.fl_ops = NULL;
2056        lock.fl_lmops = NULL;
2057
2058        vfs_lock_file(filp, F_SETLK, &lock, NULL);
2059
2060        if (lock.fl_ops && lock.fl_ops->fl_release_private)
2061                lock.fl_ops->fl_release_private(&lock);
2062}
2063
2064EXPORT_SYMBOL(locks_remove_posix);
2065
2066/*
2067 * This function is called on the last close of an open file.
2068 */
2069void locks_remove_flock(struct file *filp)
2070{
2071        struct inode * inode = filp->f_path.dentry->d_inode;
2072        struct file_lock *fl;
2073        struct file_lock **before;
2074
2075        if (!inode->i_flock)
2076                return;
2077
2078        if (filp->f_op && filp->f_op->flock) {
2079                struct file_lock fl = {
2080                        .fl_pid = current->tgid,
2081                        .fl_file = filp,
2082                        .fl_flags = FL_FLOCK,
2083                        .fl_type = F_UNLCK,
2084                        .fl_end = OFFSET_MAX,
2085                };
2086                filp->f_op->flock(filp, F_SETLKW, &fl);
2087                if (fl.fl_ops && fl.fl_ops->fl_release_private)
2088                        fl.fl_ops->fl_release_private(&fl);
2089        }
2090
2091        lock_flocks();
2092        before = &inode->i_flock;
2093
2094        while ((fl = *before) != NULL) {
2095                if (fl->fl_file == filp) {
2096                        if (IS_FLOCK(fl)) {
2097                                locks_delete_lock(before);
2098                                continue;
2099                        }
2100                        if (IS_LEASE(fl)) {
2101                                lease_modify(before, F_UNLCK);
2102                                continue;
2103                        }
2104                        /* What? */
2105                        BUG();
2106                }
2107                before = &fl->fl_next;
2108        }
2109        unlock_flocks();
2110}
2111
2112/**
2113 *      posix_unblock_lock - stop waiting for a file lock
2114 *      @filp:   how the file was opened
2115 *      @waiter: the lock which was waiting
2116 *
2117 *      lockd needs to block waiting for locks.
2118 */
2119int
2120posix_unblock_lock(struct file *filp, struct file_lock *waiter)
2121{
2122        int status = 0;
2123
2124        lock_flocks();
2125        if (waiter->fl_next)
2126                __locks_delete_block(waiter);
2127        else
2128                status = -ENOENT;
2129        unlock_flocks();
2130        return status;
2131}
2132
2133EXPORT_SYMBOL(posix_unblock_lock);
2134
2135/**
2136 * vfs_cancel_lock - file byte range unblock lock
2137 * @filp: The file to apply the unblock to
2138 * @fl: The lock to be unblocked
2139 *
2140 * Used by lock managers to cancel blocked requests
2141 */
2142int vfs_cancel_lock(struct file *filp, struct file_lock *fl)
2143{
2144        if (filp->f_op && filp->f_op->lock)
2145                return filp->f_op->lock(filp, F_CANCELLK, fl);
2146        return 0;
2147}
2148
2149EXPORT_SYMBOL_GPL(vfs_cancel_lock);
2150
2151#ifdef CONFIG_PROC_FS
2152#include <linux/proc_fs.h>
2153#include <linux/seq_file.h>
2154
2155static void lock_get_status(struct seq_file *f, struct file_lock *fl,
2156                            loff_t id, char *pfx)
2157{
2158        struct inode *inode = NULL;
2159        unsigned int fl_pid;
2160
2161        if (fl->fl_nspid)
2162                fl_pid = pid_vnr(fl->fl_nspid);
2163        else
2164                fl_pid = fl->fl_pid;
2165
2166        if (fl->fl_file != NULL)
2167                inode = fl->fl_file->f_path.dentry->d_inode;
2168
2169        seq_printf(f, "%lld:%s ", id, pfx);
2170        if (IS_POSIX(fl)) {
2171                seq_printf(f, "%6s %s ",
2172                             (fl->fl_flags & FL_ACCESS) ? "ACCESS" : "POSIX ",
2173                             (inode == NULL) ? "*NOINODE*" :
2174                             mandatory_lock(inode) ? "MANDATORY" : "ADVISORY ");
2175        } else if (IS_FLOCK(fl)) {
2176                if (fl->fl_type & LOCK_MAND) {
2177                        seq_printf(f, "FLOCK  MSNFS     ");
2178                } else {
2179                        seq_printf(f, "FLOCK  ADVISORY  ");
2180                }
2181        } else if (IS_LEASE(fl)) {
2182                seq_printf(f, "LEASE  ");
2183                if (lease_breaking(fl))
2184                        seq_printf(f, "BREAKING  ");
2185                else if (fl->fl_file)
2186                        seq_printf(f, "ACTIVE    ");
2187                else
2188                        seq_printf(f, "BREAKER   ");
2189        } else {
2190                seq_printf(f, "UNKNOWN UNKNOWN  ");
2191        }
2192        if (fl->fl_type & LOCK_MAND) {
2193                seq_printf(f, "%s ",
2194                               (fl->fl_type & LOCK_READ)
2195                               ? (fl->fl_type & LOCK_WRITE) ? "RW   " : "READ "
2196                               : (fl->fl_type & LOCK_WRITE) ? "WRITE" : "NONE ");
2197        } else {
2198                seq_printf(f, "%s ",
2199                               (lease_breaking(fl))
2200                               ? (fl->fl_type & F_UNLCK) ? "UNLCK" : "READ "
2201                               : (fl->fl_type & F_WRLCK) ? "WRITE" : "READ ");
2202        }
2203        if (inode) {
2204#ifdef WE_CAN_BREAK_LSLK_NOW
2205                seq_printf(f, "%d %s:%ld ", fl_pid,
2206                                inode->i_sb->s_id, inode->i_ino);
2207#else
2208                /* userspace relies on this representation of dev_t ;-( */
2209                seq_printf(f, "%d %02x:%02x:%ld ", fl_pid,
2210                                MAJOR(inode->i_sb->s_dev),
2211                                MINOR(inode->i_sb->s_dev), inode->i_ino);
2212#endif
2213        } else {
2214                seq_printf(f, "%d <none>:0 ", fl_pid);
2215        }
2216        if (IS_POSIX(fl)) {
2217                if (fl->fl_end == OFFSET_MAX)
2218                        seq_printf(f, "%Ld EOF\n", fl->fl_start);
2219                else
2220                        seq_printf(f, "%Ld %Ld\n", fl->fl_start, fl->fl_end);
2221        } else {
2222                seq_printf(f, "0 EOF\n");
2223        }
2224}
2225
2226static int locks_show(struct seq_file *f, void *v)
2227{
2228        struct file_lock *fl, *bfl;
2229
2230        fl = list_entry(v, struct file_lock, fl_link);
2231
2232        lock_get_status(f, fl, *((loff_t *)f->private), "");
2233
2234        list_for_each_entry(bfl, &fl->fl_block, fl_block)
2235                lock_get_status(f, bfl, *((loff_t *)f->private), " ->");
2236
2237        return 0;
2238}
2239
2240static void *locks_start(struct seq_file *f, loff_t *pos)
2241{
2242        loff_t *p = f->private;
2243
2244        lock_flocks();
2245        *p = (*pos + 1);
2246        return seq_list_start(&file_lock_list, *pos);
2247}
2248
2249static void *locks_next(struct seq_file *f, void *v, loff_t *pos)
2250{
2251        loff_t *p = f->private;
2252        ++*p;
2253        return seq_list_next(v, &file_lock_list, pos);
2254}
2255
2256static void locks_stop(struct seq_file *f, void *v)
2257{
2258        unlock_flocks();
2259}
2260
2261static const struct seq_operations locks_seq_operations = {
2262        .start  = locks_start,
2263        .next   = locks_next,
2264        .stop   = locks_stop,
2265        .show   = locks_show,
2266};
2267
2268static int locks_open(struct inode *inode, struct file *filp)
2269{
2270        return seq_open_private(filp, &locks_seq_operations, sizeof(loff_t));
2271}
2272
2273static const struct file_operations proc_locks_operations = {
2274        .open           = locks_open,
2275        .read           = seq_read,
2276        .llseek         = seq_lseek,
2277        .release        = seq_release_private,
2278};
2279
2280static int __init proc_locks_init(void)
2281{
2282        proc_create("locks", 0, NULL, &proc_locks_operations);
2283        return 0;
2284}
2285module_init(proc_locks_init);
2286#endif
2287
2288/**
2289 *      lock_may_read - checks that the region is free of locks
2290 *      @inode: the inode that is being read
2291 *      @start: the first byte to read
2292 *      @len: the number of bytes to read
2293 *
2294 *      Emulates Windows locking requirements.  Whole-file
2295 *      mandatory locks (share modes) can prohibit a read and
2296 *      byte-range POSIX locks can prohibit a read if they overlap.
2297 *
2298 *      N.B. this function is only ever called
2299 *      from knfsd and ownership of locks is never checked.
2300 */
2301int lock_may_read(struct inode *inode, loff_t start, unsigned long len)
2302{
2303        struct file_lock *fl;
2304        int result = 1;
2305        lock_flocks();
2306        for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) {
2307                if (IS_POSIX(fl)) {
2308                        if (fl->fl_type == F_RDLCK)
2309                                continue;
2310                        if ((fl->fl_end < start) || (fl->fl_start > (start + len)))
2311                                continue;
2312                } else if (IS_FLOCK(fl)) {
2313                        if (!(fl->fl_type & LOCK_MAND))
2314                                continue;
2315                        if (fl->fl_type & LOCK_READ)
2316                                continue;
2317                } else
2318                        continue;
2319                result = 0;
2320                break;
2321        }
2322        unlock_flocks();
2323        return result;
2324}
2325
2326EXPORT_SYMBOL(lock_may_read);
2327
2328/**
2329 *      lock_may_write - checks that the region is free of locks
2330 *      @inode: the inode that is being written
2331 *      @start: the first byte to write
2332 *      @len: the number of bytes to write
2333 *
2334 *      Emulates Windows locking requirements.  Whole-file
2335 *      mandatory locks (share modes) can prohibit a write and
2336 *      byte-range POSIX locks can prohibit a write if they overlap.
2337 *
2338 *      N.B. this function is only ever called
2339 *      from knfsd and ownership of locks is never checked.
2340 */
2341int lock_may_write(struct inode *inode, loff_t start, unsigned long len)
2342{
2343        struct file_lock *fl;
2344        int result = 1;
2345        lock_flocks();
2346        for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) {
2347                if (IS_POSIX(fl)) {
2348                        if ((fl->fl_end < start) || (fl->fl_start > (start + len)))
2349                                continue;
2350                } else if (IS_FLOCK(fl)) {
2351                        if (!(fl->fl_type & LOCK_MAND))
2352                                continue;
2353                        if (fl->fl_type & LOCK_WRITE)
2354                                continue;
2355                } else
2356                        continue;
2357                result = 0;
2358                break;
2359        }
2360        unlock_flocks();
2361        return result;
2362}
2363
2364EXPORT_SYMBOL(lock_may_write);
2365
2366static int __init filelock_init(void)
2367{
2368        filelock_cache = kmem_cache_create("file_lock_cache",
2369                        sizeof(struct file_lock), 0, SLAB_PANIC, NULL);
2370
2371        return 0;
2372}
2373
2374core_initcall(filelock_init);
2375
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