sys/kern/kern_lockf.c

   1 /*
   2  * Copyright (c) 2004 Joerg Sonnenberger <joerg@bec.de>.  All rights reserved.
   3  *
   4  * Copyright (c) 1982, 1986, 1989, 1993
   5  *      The Regents of the University of California.  All rights reserved.
   6  *
   7  * This code is derived from software contributed to Berkeley by
   8  * Scooter Morris at Genentech Inc.
   9  *
  10  * Redistribution and use in source and binary forms, with or without
  11  * modification, are permitted provided that the following conditions
  12  * are met:
  13  * 1. Redistributions of source code must retain the above copyright
  14  *    notice, this list of conditions and the following disclaimer.
  15  * 2. Redistributions in binary form must reproduce the above copyright
  16  *    notice, this list of conditions and the following disclaimer in the
  17  *    documentation and/or other materials provided with the distribution.
  18  * 3. All advertising materials mentioning features or use of this software
  19  *    must display the following acknowledgement:
  20  *      This product includes software developed by the University of
  21  *      California, Berkeley and its contributors.
  22  * 4. Neither the name of the University nor the names of its contributors
  23  *    may be used to endorse or promote products derived from this software
  24  *    without specific prior written permission.
  25  *
  26  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  27  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  28  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  29  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  30  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  31  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  32  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  33  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  34  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  35  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  36  * SUCH DAMAGE.
  37  *
  38  *      @(#)ufs_lockf.c 8.3 (Berkeley) 1/6/94
  39  * $FreeBSD: src/sys/kern/kern_lockf.c,v 1.25 1999/11/16 16:28:56 phk Exp $
  40  * $DragonFly: src/sys/kern/kern_lockf.c,v 1.24 2005/04/14 08:14:31 joerg Exp $
  41  */
  42
  43 #include <sys/param.h>
  44 #include <sys/systm.h>
  45 #include <sys/kernel.h>
  46 #include <sys/lock.h>
  47 #include <sys/proc.h>
  48 #include <sys/unistd.h>
  49 #include <sys/vnode.h>
  50 #include <sys/malloc.h>
  51 #include <sys/fcntl.h>
  52 #include <sys/resourcevar.h>
  53
  54 #include <sys/lockf.h>
  55 #include <machine/limits.h>     /* for LLONG_MAX */
  56 #include <machine/stdarg.h>
  57
  58 #ifdef INVARIANTS
  59 int lf_global_counter = 0;
  60 #endif
  61
  62 #ifdef LOCKF_DEBUG
  63 int lf_print_ranges = 0;
  64
  65 static void _lf_print_lock(const struct lockf *);
  66 static void _lf_printf(const char *, ...);
  67
  68 #define lf_print_lock(lock) if (lf_print_ranges) _lf_print_lock(lock)
  69 #define lf_printf(ctl, args...) if (lf_print_ranges) _lf_printf(ctl, args)
  70 #else
  71 #define lf_print_lock(lock)
  72 #define lf_printf(ctl, args...)
  73 #endif
  74
  75 static MALLOC_DEFINE(M_LOCKF, "lockf", "Byte-range locking structures");
  76
  77 static void     lf_wakeup(struct lockf *, off_t, off_t);
  78 static int      lf_overlap(const struct lockf_range *, off_t, off_t);
  79 static int      lf_overlap_left(const struct lockf_range *, off_t, off_t);
  80 static int      lf_overlap_right(const struct lockf_range *, off_t, off_t);
  81 static int      lf_overlap_left2(const struct lockf_range *, off_t, off_t);
  82 static int      lf_overlap_right2(const struct lockf_range *, off_t, off_t);
  83 static int      lf_overlap_embedded(const struct lockf_range *, off_t, off_t);
  84 static struct lockf_range *lf_alloc_range(void);
  85 static void     lf_create_range(struct lockf_range *, struct proc *, int, int,
  86                                 off_t, off_t, int);
  87 static void     lf_destroy_range(struct lockf_range *, int);
  88
  89 static int      lf_setlock(struct lockf *, struct proc *, int, int,
  90                            off_t, off_t);
  91 static int      lf_clearlock(struct lockf *, struct proc *, int, int,
  92                              off_t, off_t);
  93 static int      lf_getlock(struct flock *, struct lockf *, struct proc *,
  94                            int, int, off_t, off_t);
  95
  96 static int      lf_count_change(struct proc *, int);
  97
  98 /*
  99  * Change the POSIX lock accounting for the given process.
 100  */
 101 void
 102 lf_count_adjust(struct proc *p, int increase)
 103 {
 104         struct uidinfo *uip;
 105
 106         KKASSERT(p != NULL);
 107
 108         uip = p->p_ucred->cr_uidinfo;
 109
 110         if (increase)
 111                 uip->ui_posixlocks += p->p_numposixlocks;
 112         else
 113                 uip->ui_posixlocks -= p->p_numposixlocks;
 114
 115         KASSERT(uip->ui_posixlocks >= 0,
 116                 ("Negative number of POSIX locks held by %s user: %d.",
 117                  increase ? "new" : "old", uip->ui_posixlocks));
 118 }
 119
 120 static int
 121 lf_count_change(struct proc *owner, int diff)
 122 {
 123         struct uidinfo *uip;
 124         int max;
 125
 126         /* we might actually not have a process context */
 127         if (owner == NULL)
 128                 return(0);
 129
 130         uip = owner->p_ucred->cr_uidinfo;
 131
 132         max = MIN(owner->p_rlimit[RLIMIT_POSIXLOCKS].rlim_cur,
 133                   maxposixlocksperuid);
 134         if (diff > 0 && owner->p_ucred->cr_uid != 0 && max != -1 &&
 135             uip->ui_posixlocks >= max )
 136                 return(1);
 137
 138         uip->ui_posixlocks += diff;
 139
 140         KASSERT(uip->ui_posixlocks >= 0,
 141                 ("Negative number of POSIX locks held by user: %d.",
 142                  uip->ui_posixlocks));
 143
 144         return(0);
 145 }
 146
 147 /*
 148  * Advisory record locking support
 149  */
 150 int
 151 lf_advlock(struct vop_advlock_args *ap, struct lockf *lock, u_quad_t size)
 152 {
 153         struct flock *fl = ap->a_fl;
 154         struct proc *owner;
 155         off_t start, end;
 156         int type, flags, error;
 157         lwkt_tokref ilock;
 158
 159         /*
 160          * Convert the flock structure into a start and end.
 161          */
 162         switch (fl->l_whence) {
 163         case SEEK_SET:
 164         case SEEK_CUR:
 165                 /*
 166                  * Caller is responsible for adding any necessary offset
 167                  * when SEEK_CUR is used.
 168                  */
 169                 start = fl->l_start;
 170                 break;
 171
 172         case SEEK_END:
 173                 start = size + fl->l_start;
 174                 break;
 175
 176         default:
 177                 return(EINVAL);
 178         }
 179         if (start < 0)
 180                 return(EINVAL);
 181         if (fl->l_len == 0) {
 182                 flags |= F_NOEND;
 183                 end = LLONG_MAX;
 184         } else {
 185                 end = start + fl->l_len - 1;
 186                 if (end < start)
 187                         return(EINVAL);
 188         }
 189
 190         flags = ap->a_flags;
 191         type = fl->l_type;
 192         /*
 193          * This isn't really correct for flock-style locks,
 194          * but the current handling is somewhat broken anyway.
 195          */
 196         owner = (struct proc *)ap->a_id;
 197
 198         /*
 199          * Do the requested operation.
 200          */
 201         lwkt_gettoken(&ilock, lwkt_token_pool_get(lock));
 202
 203         if (lock->init_done == 0) {
 204                 TAILQ_INIT(&lock->lf_range);
 205                 TAILQ_INIT(&lock->lf_blocked);
 206                 lock->init_done = 1;
 207         }
 208
 209         switch(ap->a_op) {
 210         case F_SETLK:
 211                 error = lf_setlock(lock, owner, type, flags, start, end);
 212                 break;
 213
 214         case F_UNLCK:
 215                 error = lf_clearlock(lock, owner, type, flags, start, end);
 216                 break;
 217
 218         case F_GETLK:
 219                 error = lf_getlock(fl, lock, owner, type, flags, start, end);
 220                 break;
 221
 222         default:
 223                 error = EINVAL;
 224                 break;
 225         }
 226         lwkt_reltoken(&ilock);
 227         return(error);
 228 }
 229
 230 static int
 231 lf_setlock(struct lockf *lock, struct proc *owner, int type, int flags,
 232            off_t start, off_t end)
 233 {
 234         struct lockf_range *range, *first_match, *insert_point;
 235         int wakeup_needed, lock_needed;
 236         /* pre-allocation to avoid blocking in the middle of the algorithm */
 237         struct lockf_range *new_range1 = NULL, *new_range2 = NULL;
 238         int error = 0;
 239
 240         /* for restauration in case of hitting the POSIX lock limit below */
 241         struct lockf_range *orig_first_match = NULL;
 242         off_t orig_end = -1;
 243         int orig_flags = 0;
 244
 245 restart:
 246         if (new_range1 == NULL)
 247                 new_range1 = lf_alloc_range();
 248         if (new_range2 == NULL)
 249                 new_range2 = lf_alloc_range();
 250         first_match = NULL;
 251         insert_point = NULL;
 252         wakeup_needed = 0;
 253
 254         lf_print_lock(lock);
 255
 256         TAILQ_FOREACH(range, &lock->lf_range, lf_link) {
 257                 if (insert_point == NULL && range->lf_start >= start)
 258                         insert_point = range;
 259                 if (lf_overlap(range, start, end) == 0)
 260                         continue;
 261                 if (range->lf_owner == owner) {
 262                         if (first_match == NULL)
 263                                 first_match = range;
 264                         continue;
 265                 }
 266                 if (type == F_WRLCK || range->lf_type == F_WRLCK)
 267                         break;
 268         }
 269
 270         if (range != NULL) {
 271                 struct lockf_range *brange;
 272
 273                 if ((flags & F_WAIT) == 0) {
 274                         error = EAGAIN;
 275                         goto do_cleanup;
 276                 }
 277
 278                 /*
 279                  * We are blocked. For POSIX locks we have to check
 280                  * for deadlocks and return with EDEADLK. This is done
 281                  * by checking whether range->lf_owner is already
 282                  * blocked.
 283                  *
 284                  * Since flock-style locks cover the whole file, a
 285                  * deadlock between those is nearly impossible.
 286                  * This can only occur if a process tries to lock the
 287                  * same inode exclusively while holding a shared lock
 288                  * with another descriptor.
 289                  * XXX How can we cleanly detect this?
 290                  * XXX The current mixing of flock & fcntl/lockf is evil.
 291                  *
 292                  * Handle existing locks of flock-style like POSIX locks.
 293                  */
 294                 if (flags & F_POSIX) {
 295                         TAILQ_FOREACH(brange, &lock->lf_blocked, lf_link)
 296                                 if (brange->lf_owner == range->lf_owner) {
 297                                         error = EDEADLK;
 298                                         goto do_cleanup;
 299                                 }
 300                 }
 301
 302                 /*
 303                  * For flock-style locks, we must first remove
 304                  * any shared locks that we hold before we sleep
 305                  * waiting for an exclusive lock.
 306                  */
 307                 if ((flags & F_FLOCK) && type == F_WRLCK)
 308                         lf_clearlock(lock, owner, type, flags, start, end);
 309
 310                 brange = new_range1;
 311                 new_range1 = NULL;
 312                 lf_create_range(brange, owner, type, 0, start, end, 0);
 313                 TAILQ_INSERT_TAIL(&lock->lf_blocked, brange, lf_link);
 314                 error = tsleep(brange, PCATCH, "lockf", 0);
 315
 316                 /*
 317                  * We may have been awaked by a signal and/or by a
 318                  * debugger continuing us (in which case we must remove
 319                  * ourselves from the blocked list) and/or by another
 320                  * process releasing/downgrading a lock (in which case
 321                  * we have already been removed from the blocked list
 322                  * and our lf_flags field is 1).
 323                  */
 324                 if (brange->lf_flags == 0)
 325                         TAILQ_REMOVE(&lock->lf_blocked, brange, lf_link);
 326                 tsleep(brange, 0, "lockfz", 2); /* XXX debug livelock */
 327                 lf_destroy_range(brange, 0);
 328
 329                 if (error)
 330                         goto do_cleanup;
 331                 goto restart;
 332         }
 333
 334         if (first_match == NULL) {
 335                 if (flags & F_POSIX) {
 336                         if (lf_count_change(owner, 1)) {
 337                                 error = ENOLCK;
 338                                 goto do_cleanup;
 339                         }
 340                 }
 341                 range = new_range1;
 342                 new_range1 = NULL;
 343                 lf_create_range(range, owner, type, flags, start, end, 1);
 344                 if (insert_point != NULL)
 345                         TAILQ_INSERT_BEFORE(insert_point, range, lf_link);
 346                 else
 347                         TAILQ_INSERT_TAIL(&lock->lf_range, range, lf_link);
 348                 goto do_wakeup;
 349         }
 350
 351         lock_needed = 1;
 352
 353         if (lf_overlap_left(first_match, start, end)) {
 354                 KKASSERT((flags & F_POSIX) != 0);
 355                 if (first_match->lf_end > end) {
 356                         if (first_match->lf_type == type)
 357                                 goto do_wakeup;
 358                         if (lf_count_change(owner, 2)) {
 359                                 error = ENOLCK;
 360                                 goto do_cleanup;
 361                         }
 362                         range = new_range1;
 363                         new_range1 = NULL;
 364                         lf_create_range(range, owner, type, flags,
 365                                         start, end, 1);
 366                         if (insert_point != NULL)
 367                                 TAILQ_INSERT_BEFORE(insert_point, range,
 368                                                     lf_link);
 369                         else
 370                                 TAILQ_INSERT_TAIL(&lock->lf_range, range,
 371                                                   lf_link);
 372                         insert_point = range;
 373                         range = new_range2;
 374                         new_range2 = NULL;
 375                         lf_create_range(range, owner, first_match->lf_type,
 376                                         first_match->lf_flags, end + 1,
 377                                         first_match->lf_end, 1);
 378                         TAILQ_INSERT_AFTER(&lock->lf_range, insert_point,
 379                                            range, lf_link);
 380                         first_match->lf_flags &= ~F_NOEND;
 381                         first_match->lf_end = start - 1;
 382                         if (type == F_RDLCK)
 383                                 wakeup_needed = 1;
 384                         goto do_wakeup;
 385                 }
 386                 /*
 387                  * left match, but not right match
 388                  *
 389                  * handle the lf_type != type case directly,
 390                  * merge the other case with the !lock_needed path.
 391                  */
 392                 if (first_match->lf_type != type) {
 393                         /*
 394                          * This is needed if the lockf acquisition below fails.
 395                          */
 396                         orig_first_match = first_match;
 397                         orig_end = first_match->lf_end;
 398                         orig_flags = first_match->lf_flags;
 399                         first_match->lf_end = start - 1;
 400                         first_match->lf_flags &= ~F_NOEND;
 401                         if (type == F_RDLCK)
 402                                 wakeup_needed = 1;
 403                         /* Try to find the next matching range */
 404                         range = TAILQ_NEXT(first_match, lf_link);
 405                         while (range != NULL) {
 406                                 if (range->lf_owner == owner &&
 407                                     lf_overlap(range, start, end))
 408                                         break;
 409                                 range = TAILQ_NEXT(range, lf_link);
 410                         }
 411                         if (range == NULL)
 412                                 goto do_wakeup;
 413                         first_match = range;
 414                         /* fall through to !left_match behaviour */
 415                 } else {
 416                         first_match->lf_end = end;
 417                         first_match->lf_flags |= flags & F_NOEND;
 418                         lock_needed = 0;
 419                 }
 420         }
 421
 422         if (lf_overlap_embedded(first_match, start, end)) {
 423                 if (first_match != insert_point) {
 424                         TAILQ_REMOVE(&lock->lf_range, first_match, lf_link);
 425                         TAILQ_INSERT_BEFORE(insert_point, first_match, lf_link);
 426                 }
 427                 first_match->lf_start = start;
 428                 first_match->lf_end = end;
 429                 first_match->lf_flags |= flags & F_NOEND;
 430                 first_match->lf_type = type;
 431                 lock_needed = 0;
 432         }
 433
 434         if (lock_needed == 0) {
 435                 struct lockf_range *nrange;
 436
 437                 range = TAILQ_NEXT(first_match, lf_link);
 438                 while (range != NULL) {
 439                         if (range->lf_owner != owner) {
 440                                 range = TAILQ_NEXT(range, lf_link);
 441                                 continue;
 442                         }
 443                         if (lf_overlap_embedded(range, start, end)) {
 444                                 nrange = TAILQ_NEXT(range, lf_link);
 445                                 TAILQ_REMOVE(&lock->lf_range, range,
 446                                              lf_link);
 447                                 lf_count_change(owner, -1);
 448                                 lf_destroy_range(range, 1);
 449                                 range = nrange;
 450                                 continue;
 451                         }
 452                         if (lf_overlap_right(range, start, end) == 0) {
 453                                 range = TAILQ_NEXT(range, lf_link);
 454                                 continue;
 455                         }
 456                         if (range->lf_type != type) {
 457                                 range->lf_start = end + 1;
 458                                 nrange = TAILQ_NEXT(range, lf_link);
 459                                 TAILQ_REMOVE(&lock->lf_range, range, lf_link);
 460                                 while (nrange != NULL) {
 461                                         if (nrange->lf_start >= end + 1)
 462                                                 break;
 463                                         nrange = TAILQ_NEXT(nrange, lf_link);
 464                                 }
 465                                 if (nrange != NULL)
 466                                         TAILQ_INSERT_BEFORE(nrange, range,
 467                                                             lf_link);
 468                                 else
 469                                         TAILQ_INSERT_TAIL(&lock->lf_range,
 470                                                           range, lf_link);
 471                                 break;
 472                         }
 473                         first_match->lf_end = range->lf_end;
 474                         first_match->lf_flags |=
 475                             range->lf_flags & F_NOEND;
 476                         TAILQ_REMOVE(&lock->lf_range, range, lf_link);
 477                         lf_count_change(owner, -1);
 478                         lf_destroy_range(range, 1);
 479                         break;
 480                 }
 481                 goto do_wakeup;
 482         }
 483
 484         if (lf_overlap_right(first_match, start, end)) {
 485                 KKASSERT((flags & F_POSIX) != 0);
 486                 if (first_match->lf_type == type) {
 487                         first_match->lf_start = start;
 488                         if (first_match != insert_point) {
 489                                 TAILQ_REMOVE(&lock->lf_range, first_match,
 490                                              lf_link);
 491                                 TAILQ_INSERT_BEFORE(insert_point, first_match,
 492                                                     lf_link);
 493                         }
 494                         goto do_wakeup;
 495                 }
 496                 if (lf_count_change(owner, 1)) {
 497                         if (orig_first_match != NULL) {
 498                                 orig_first_match->lf_end = orig_end;
 499                                 orig_first_match->lf_flags = orig_end;
 500                         }
 501                         error = ENOLCK;
 502                         goto do_cleanup;
 503                 }
 504                 first_match->lf_start = end + 1;
 505                 KKASSERT(new_range1 != NULL);
 506                 range = new_range1;
 507                 new_range1 = NULL;
 508                 lf_create_range(range, owner, type, flags, start, end, 1);
 509                 TAILQ_INSERT_BEFORE(insert_point, range, lf_link);
 510                 range = TAILQ_NEXT(first_match, lf_link);
 511                 TAILQ_REMOVE(&lock->lf_range, first_match, lf_link);
 512                 while (range != NULL) {
 513                         if (range->lf_start >= first_match->lf_start)
 514                                 break;
 515                         range = TAILQ_NEXT(range, lf_link);
 516                 }
 517                 if (range != NULL)
 518                         TAILQ_INSERT_BEFORE(range, first_match, lf_link);
 519                 else
 520                         TAILQ_INSERT_TAIL(&lock->lf_range, first_match, lf_link);
 521                 goto do_wakeup;
 522         }
 523
 524 do_wakeup:
 525         lf_print_lock(lock);
 526         if (wakeup_needed)
 527                 lf_wakeup(lock, start, end);
 528         error = 0;
 529 do_cleanup:
 530         if (new_range1 != NULL)
 531                 lf_destroy_range(new_range1, 0);
 532         if (new_range2 != NULL)
 533                 lf_destroy_range(new_range2, 0);
 534         return(error);
 535 }
 536
 537 static int
 538 lf_clearlock(struct lockf *lock, struct proc *owner, int type, int flags,
 539              off_t start, off_t end)
 540 {
 541         struct lockf_range *range, *trange;
 542         struct lockf_range *new_range;
 543         int error = 0;
 544
 545         new_range = lf_alloc_range();
 546
 547         TAILQ_FOREACH_MUTABLE(range, &lock->lf_range, lf_link, trange) {
 548                 if (range->lf_end < start)
 549                         continue;
 550                 if (range->lf_start > end)
 551                         break;
 552                 if (range->lf_owner != owner)
 553                         continue;
 554                 if (lf_overlap_embedded(range, start, end)) {
 555                         TAILQ_REMOVE(&lock->lf_range, range, lf_link);
 556                         /* flock-locks are equal */
 557                         if (range->lf_flags & F_POSIX)
 558                                 lf_count_change(owner, -1);
 559                         lf_destroy_range(range, 1);
 560                         continue;
 561                 }
 562                 if (lf_overlap_left2(range, start, end)) {
 563                         KKASSERT(range->lf_flags & F_POSIX);
 564                         if (lf_overlap_right2(range, start, end)) {
 565                                 struct lockf_range *nrange;
 566
 567                                 if (lf_count_change(owner, 1)) {
 568                                         error = ENOLCK;
 569                                         goto do_cleanup;
 570                                 }
 571                                 nrange = new_range;
 572                                 new_range = NULL;
 573                                 lf_create_range(nrange, range->lf_owner,
 574                                     range->lf_type, range->lf_flags,
 575                                     end + 1, range->lf_end, 1);
 576                                 range->lf_end = start;
 577                                 range->lf_flags &= ~F_NOEND;
 578                                 for (; range != NULL;
 579                                      range = TAILQ_NEXT(range, lf_link))
 580                                         if (range->lf_start >= nrange->lf_start)
 581                                                 break;
 582                                 if (range != NULL)
 583                                         TAILQ_INSERT_BEFORE(range, nrange,
 584                                                             lf_link);
 585                                 else
 586                                         TAILQ_INSERT_TAIL(&lock->lf_range,
 587                                                           nrange, lf_link);
 588                                 break;
 589                         }
 590                         range->lf_end = start - 1;
 591                         range->lf_flags &= ~F_NOEND;
 592                         continue;
 593                 }
 594                 if (lf_overlap_right2(range, start, end)) {
 595                         struct lockf_range *nrange = range;
 596
 597                         KKASSERT(range->lf_flags & F_POSIX);
 598
 599                         range  = TAILQ_NEXT(range, lf_link);
 600                         TAILQ_REMOVE(&lock->lf_range, nrange, lf_link);
 601                         for (; range != NULL;
 602                              range = TAILQ_NEXT(range, lf_link))
 603                                 if (range->lf_start >= nrange->lf_start)
 604                                         break;
 605                         if (range != NULL)
 606                                 TAILQ_INSERT_BEFORE(range, nrange, lf_link);
 607                         else
 608                                 TAILQ_INSERT_TAIL(&lock->lf_range, nrange,
 609                                                   lf_link);
 610                         break;
 611                 }
 612         }
 613
 614         lf_wakeup(lock, start, end);
 615         error = 0;
 616
 617 do_cleanup:
 618         if (new_range != NULL)
 619                 lf_destroy_range(new_range, 0);
 620
 621         return(error);
 622 }
 623
 624 /*
 625  * Check whether there is a blocking lock,
 626  * and if so return its process identifier.
 627  */
 628 static int
 629 lf_getlock(struct flock *fl, struct lockf *lock, struct proc *owner,
 630            int type, int flags, off_t start, off_t end)
 631 {
 632         struct lockf_range *range;
 633
 634         TAILQ_FOREACH(range, &lock->lf_range, lf_link)
 635                 if (range->lf_owner != owner &&
 636                     lf_overlap(range, start, end) &&
 637                     (type == F_WRLCK || range->lf_type == F_WRLCK))
 638                         break;
 639         if (range == NULL) {
 640                 fl->l_type = F_UNLCK;
 641                 return(0);
 642         }
 643         fl->l_type = range->lf_type;
 644         fl->l_whence = SEEK_SET;
 645         fl->l_start = range->lf_start;
 646         if (range->lf_flags & F_NOEND)
 647                 fl->l_len = 0;
 648         else
 649                 fl->l_len = range->lf_end - range->lf_start + 1;
 650         if (range->lf_owner != NULL && (range->lf_flags & F_POSIX))
 651                 fl->l_pid = range->lf_owner->p_pid;
 652         else
 653                 fl->l_pid = -1;
 654         return(0);
 655 }
 656
 657 /*
 658  * Check whether range and [start, end] overlap.
 659  */
 660 static int
 661 lf_overlap(const struct lockf_range *range, off_t start, off_t end)
 662 {
 663         if (range->lf_start >= start && range->lf_start <= end)
 664                 return(1);
 665         else if (start >= range->lf_start && start <= range->lf_end)
 666                 return(1);
 667         else
 668                 return(0);
 669 }
 670
 671 /*
 672  * Wakeup pending lock attempts.
 673  */
 674 static void
 675 lf_wakeup(struct lockf *lock, off_t start, off_t end)
 676 {
 677         struct lockf_range *range, *nrange;
 678         TAILQ_FOREACH_MUTABLE(range, &lock->lf_blocked, lf_link, nrange) {
 679                 if (lf_overlap(range, start, end) == 0)
 680                         continue;
 681                 TAILQ_REMOVE(&lock->lf_blocked, range, lf_link);
 682                 range->lf_flags = 1;
 683                 wakeup(range);
 684                 if (lf_overlap_embedded(range, start, end))
 685                         break;
 686         }
 687 }
 688
 689 static int
 690 lf_overlap_left(const struct lockf_range *range, off_t start, off_t end)
 691 {
 692         if (range->lf_start < start && range->lf_end >= start - 1 &&
 693             range->lf_end <= end)
 694                 return(1);
 695         else
 696                 return(0);
 697
 698 }
 699
 700 static int
 701 lf_overlap_right(const struct lockf_range *range, off_t start, off_t end)
 702 {
 703         if (range->lf_end > end && range->lf_start >= start &&
 704             range->lf_start - 1 <= end)
 705                 return(1);
 706         else
 707                 return(0);
 708 }
 709
 710 static int
 711 lf_overlap_left2(const struct lockf_range *range, off_t start, off_t end)
 712 {
 713         if (range->lf_start < start && range->lf_end >= start &&
 714             range->lf_end <= end)
 715                 return(1);
 716         else
 717                 return(0);
 718
 719 }
 720
 721 static int
 722 lf_overlap_right2(const struct lockf_range *range, off_t start, off_t end)
 723 {
 724         if (range->lf_end > end && range->lf_start >= start &&
 725             range->lf_start <= end)
 726                 return(1);
 727         else
 728                 return(0);
 729 }
 730
 731 static int
 732 lf_overlap_embedded(const struct lockf_range *range, off_t start, off_t end)
 733 {
 734         if (range->lf_start >= start && range->lf_end <= end)
 735                 return(1);
 736         else
 737                 return(0);
 738 }
 739
 740 /*
 741  * Allocate a range structure and initialize it sufficiently such that
 742  * lf_destroy_range() does not barf.
 743  */
 744 static struct lockf_range *
 745 lf_alloc_range(void)
 746 {
 747         struct lockf_range *range;
 748
 749 #ifdef INVARIANTS
 750         lf_global_counter++;
 751 #endif
 752         range = malloc(sizeof(struct lockf_range), M_LOCKF, M_WAITOK);
 753         range->lf_owner = NULL;
 754         return(range);
 755 }
 756
 757 static void
 758 lf_create_range(struct lockf_range *range, struct proc *owner, int type,
 759                 int flags, off_t start, off_t end, int accounting)
 760 {
 761         KKASSERT(start <= end);
 762         if (owner != NULL && (flags & F_POSIX) && accounting)
 763                 ++owner->p_numposixlocks;
 764         range->lf_type = type;
 765         range->lf_flags = flags;
 766         range->lf_start = start;
 767         range->lf_end = end;
 768         range->lf_owner = owner;
 769
 770         lf_printf("lf_create_range: %lld..%lld\n",
 771                         range->lf_start, range->lf_end);
 772 }
 773
 774 static void
 775 lf_destroy_range(struct lockf_range *range, int accounting)
 776 {
 777         struct proc *owner = range->lf_owner;
 778         int flags = range->lf_flags;
 779
 780         lf_printf("lf_destroy_range: %lld..%lld\n",
 781                         range->lf_start, range->lf_end);
 782
 783         free(range, M_LOCKF);
 784         if (owner != NULL && (flags & F_POSIX) && accounting) {
 785                 --owner->p_numposixlocks;
 786                 KASSERT(owner->p_numposixlocks >= 0,
 787                         ("Negative number of POSIX locks held by process: %d",
 788                          owner->p_numposixlocks));
 789         }
 790
 791 #ifdef INVARIANTS
 792         lf_global_counter--;
 793         KKASSERT(lf_global_counter>=0);
 794 #endif
 795 }
 796
 797 #ifdef LOCKF_DEBUG
 798
 799 static void
 800 _lf_printf(const char *ctl, ...)
 801 {
 802         struct proc *p;
 803         __va_list va;
 804
 805         if (lf_print_ranges) {
 806             if ((p = curproc) != NULL)
 807                 printf("pid %d (%s): ", p->p_pid, p->p_comm);
 808         }
 809         __va_start(va, ctl);
 810         vprintf(ctl, va);
 811         __va_end(va);
 812 }
 813
 814 static void
 815 _lf_print_lock(const struct lockf *lock)
 816 {
 817         struct lockf_range *range;
 818
 819         if (lf_print_ranges == 0)
 820                 return;
 821
 822         if (TAILQ_EMPTY(&lock->lf_range)) {
 823                 lf_printf("lockf %p: no ranges locked\n", lock);
 824         } else {
 825                 lf_printf("lockf %p:\n", lock);
 826         }
 827         TAILQ_FOREACH(range, &lock->lf_range, lf_link)
 828                 printf("\t%lld..%lld type %s owned by %d\n",
 829                        range->lf_start, range->lf_end,
 830                        range->lf_type == F_RDLCK ? "shared" : "exclusive",
 831                        range->lf_flags & F_POSIX ? range->lf_owner->p_pid : -1);
 832         if (TAILQ_EMPTY(&lock->lf_blocked))
 833                 printf("no process waiting for range\n");
 834         else
 835                 printf("blocked locks:");
 836         TAILQ_FOREACH(range, &lock->lf_blocked, lf_link)
 837                 printf("\t%lld..%lld type %s waiting on %p\n",
 838                        range->lf_start, range->lf_end,
 839                        range->lf_type == F_RDLCK ? "shared" : "exclusive",
 840                        range);
 841 }
 842 #endif /* LOCKF_DEBUG */