sys/kern/kern_lockf.c

   1 /*
   2  * Copyright (c) 2004 Joerg Sonnenberger <joerg@bec.de>
   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 1.15 2004/05/11 20:37:21 dillon 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
  57 #ifdef INVARIANTS
  58 int lf_global_counter = 0;
  59 #endif
  60 #ifdef LOCKF_DEBUG
  61 int lf_print_ranges = 0;
  62
  63 static void     lf_print_lock(const struct lockf *);
  64 #endif
  65
  66 static MALLOC_DEFINE(M_LOCKF, "lockf", "Byte-range locking structures");
  67
  68 static void     lf_wakeup(struct lockf *, off_t, off_t);
  69 static int      lf_overlap(const struct lockf_range *, off_t, off_t);
  70 static int      lf_overlap_left(const struct lockf_range *, off_t, off_t);
  71 static int      lf_overlap_right(const struct lockf_range *, off_t, off_t);
  72 static int      lf_overlap_left2(const struct lockf_range *, off_t, off_t);
  73 static int      lf_overlap_right2(const struct lockf_range *, off_t, off_t);
  74 static int      lf_overlap_embedded(const struct lockf_range *, off_t, off_t);
  75 static struct lockf_range *lf_alloc_range(void);
  76 static void     lf_create_range(struct lockf_range *, struct proc *, int, int,
  77                                 off_t, off_t, int);
  78 static void     lf_destroy_range(struct lockf_range *, int);
  79
  80 static int      lf_setlock(struct lockf *, struct proc *, int, int,
  81                            off_t, off_t);
  82 static int      lf_clearlock(struct lockf *, struct proc *, int, int,
  83                              off_t, off_t);
  84 static int      lf_getlock(struct flock *, struct lockf *, struct proc *,
  85                            int, int, off_t, off_t);
  86
  87 static int      lf_count_change(struct proc *, int);
  88
  89 /*
  90  * Change the POSIX lock accounting for the given process.
  91  */
  92 void
  93 lf_count_adjust(struct proc *p, int increase)
  94 {
  95         struct uidinfo *uip;
  96
  97         KKASSERT(p != NULL);
  98
  99         uip = p->p_ucred->cr_uidinfo;
 100
 101         if (increase)
 102                 uip->ui_posixlocks += p->p_numposixlocks;
 103         else
 104                 uip->ui_posixlocks -= p->p_numposixlocks;
 105
 106         KASSERT(uip->ui_posixlocks >= 0,
 107                 ("Negative number of POSIX locks held by %s user: %d.",
 108                  increase ? "new" : "old", uip->ui_posixlocks));
 109 }
 110
 111 static int
 112 lf_count_change(struct proc *owner, int diff)
 113 {
 114         struct uidinfo *uip;
 115         int max;
 116
 117         /* we might actually not have a process context */
 118         if (owner == NULL)
 119                 return(0);
 120
 121         uip = owner->p_ucred->cr_uidinfo;
 122
 123         max = MIN(owner->p_rlimit[RLIMIT_POSIXLOCKS].rlim_cur,
 124                   maxposixlocksperuid);
 125         if (diff > 0 && owner->p_ucred->cr_uid != 0 && max != -1 &&
 126             uip->ui_posixlocks >= max )
 127                 return(1);
 128
 129         uip->ui_posixlocks += diff;
 130
 131         KASSERT(uip->ui_posixlocks >= 0,
 132                 ("Negative number of POSIX locks held by user: %d.",
 133                  uip->ui_posixlocks));
 134
 135         return(0);
 136 }
 137
 138 /*
 139  * Advisory record locking support
 140  */
 141 int
 142 lf_advlock(struct vop_advlock_args *ap, struct lockf *lock, u_quad_t size)
 143 {
 144         struct flock *fl = ap->a_fl;
 145         struct proc *owner;
 146         off_t start, end;
 147         int type, flags, error;
 148         lwkt_tokref ilock;
 149
 150         if (lock->init_done == 0) {
 151                 TAILQ_INIT(&lock->lf_range);
 152                 TAILQ_INIT(&lock->lf_blocked);
 153                 lock->init_done = 1;
 154         }
 155
 156         /*
 157          * Convert the flock structure into a start and end.
 158          */
 159         switch (fl->l_whence) {
 160         case SEEK_SET:
 161         case SEEK_CUR:
 162                 /*
 163                  * Caller is responsible for adding any necessary offset
 164                  * when SEEK_CUR is used.
 165                  */
 166                 start = fl->l_start;
 167                 break;
 168
 169         case SEEK_END:
 170                 start = size + fl->l_start;
 171                 break;
 172
 173         default:
 174                 return(EINVAL);
 175         }
 176         if (start < 0)
 177                 return(EINVAL);
 178         if (fl->l_len == 0) {
 179                 flags |= F_NOEND;
 180                 end = LLONG_MAX;
 181         } else {
 182                 end = start + fl->l_len - 1;
 183                 if (end < start)
 184                         return(EINVAL);
 185         }
 186
 187         flags = ap->a_flags;
 188         type = fl->l_type;
 189         /*
 190          * This isn't really correct for flock-style locks,
 191          * but the current handling is somewhat broken anyway.
 192          */
 193         owner = (struct proc *)ap->a_id;
 194
 195         /*
 196          * Do the requested operation.
 197          */
 198         lwkt_gettoken(&ilock, lwkt_token_pool_get(lock));
 199         switch(ap->a_op) {
 200         case F_SETLK:
 201                 error = lf_setlock(lock, owner, type, flags, start, end);
 202                 break;
 203
 204         case F_UNLCK:
 205                 error = lf_clearlock(lock, owner, type, flags, start, end);
 206                 break;
 207
 208         case F_GETLK:
 209                 error = lf_getlock(fl, lock, owner, type, flags, start, end);
 210                 break;
 211
 212         default:
 213                 error = EINVAL;
 214                 break;
 215         }
 216         lwkt_reltoken(&ilock);
 217         return(error);
 218 }
 219
 220 static int
 221 lf_setlock(struct lockf *lock, struct proc *owner, int type, int flags,
 222            off_t start, off_t end)
 223 {
 224         struct lockf_range *range, *first_match, *insert_point;
 225         int wakeup_needed, lock_needed;
 226         /* pre-allocation to avoid blocking in the middle of the algorithm */
 227         struct lockf_range *new_range1 = NULL, *new_range2 = NULL;
 228         int error = 0;
 229
 230         /* for restauration in case of hitting the POSIX lock limit below */
 231         struct lockf_range *orig_first_match = NULL;
 232         off_t orig_end = -1;
 233         int orig_flags = 0;
 234
 235 restart:
 236         if (new_range1 == NULL)
 237                 new_range1 = lf_alloc_range();
 238         if (new_range2 == NULL)
 239                 new_range2 = lf_alloc_range();
 240         first_match = NULL;
 241         insert_point = NULL;
 242         wakeup_needed = 0;
 243
 244 #ifdef LOCKF_DEBUG
 245         if (lf_print_ranges)
 246                 lf_print_lock(lock);
 247 #endif
 248
 249         TAILQ_FOREACH(range, &lock->lf_range, lf_link) {
 250                 if (insert_point == NULL && range->lf_start >= start)
 251                         insert_point = range;
 252                 if (lf_overlap(range, start, end) == 0)
 253                         continue;
 254                 if (range->lf_owner == owner) {
 255                         if (first_match == NULL)
 256                                 first_match = range;
 257                         continue;
 258                 }
 259                 if (type == F_WRLCK || range->lf_type == F_WRLCK)
 260                         break;
 261         }
 262
 263         if (range != NULL) {
 264                 struct lockf_range *brange;
 265
 266                 if ((flags & F_WAIT) == 0) {
 267                         error = EAGAIN;
 268                         goto do_cleanup;
 269                 }
 270
 271                 /*
 272                  * We are blocked. For POSIX locks we have to check
 273                  * for deadlocks and return with EDEADLK. This is done
 274                  * by checking wether range->lf_owner is already
 275                  * blocked.
 276                  *
 277                  * Since flock-style locks cover the whole file, a
 278                  * deadlock between those is nearly impossible.
 279                  * This can only occur if a process tries to lock the
 280                  * same inode exclusively while holding a shared lock
 281                  * with another descriptor.
 282                  * XXX How can we cleanly detect this?
 283                  * XXX The current mixing of flock & fcntl/lockf is evil.
 284                  *
 285                  * Handle existing locks of flock-style like POSIX locks.
 286                  */
 287                 if (flags & F_POSIX) {
 288                         TAILQ_FOREACH(brange, &lock->lf_blocked, lf_link)
 289                                 if (brange->lf_owner == range->lf_owner) {
 290                                         error = EDEADLK;
 291                                         goto do_cleanup;
 292                                 }
 293                 }
 294
 295                 /*
 296                  * For flock-style locks, we must first remove
 297                  * any shared locks that we hold before we sleep
 298                  * waiting for an exclusive lock.
 299                  */
 300                 if ((flags & F_FLOCK) && type == F_WRLCK)
 301                         lf_clearlock(lock, owner, type, flags, start, end);
 302
 303                 brange = new_range1;
 304                 new_range1 = NULL;
 305                 lf_create_range(brange, owner, type, 0, start, end, 0);
 306                 TAILQ_INSERT_TAIL(&lock->lf_blocked, brange, lf_link);
 307                 error = tsleep(brange, PCATCH, "lockf", 0);
 308
 309                 /*
 310                  * We may have been awaked by a signal and/or by a
 311                  * debugger continuing us (in which case we must remove
 312                  * ourselves from the blocked list) and/or by another
 313                  * process releasing/downgrading a lock (in which case
 314                  * we have already been removed from the blocked list
 315                  * and our lf_flags field is 1).
 316                  */
 317                 if (brange->lf_flags == 0)
 318                         TAILQ_REMOVE(&lock->lf_blocked, brange, lf_link);
 319                 lf_destroy_range(brange, 0);
 320
 321                 if (error)
 322                         goto do_cleanup;
 323                 goto restart;
 324         }
 325
 326         if (first_match == NULL) {
 327                 if (flags & F_POSIX) {
 328                         if (lf_count_change(owner, 1)) {
 329                                 error = ENOLCK;
 330                                 goto do_cleanup;
 331                         }
 332                 }
 333                 range = new_range1;
 334                 new_range1 = NULL;
 335                 lf_create_range(range, owner, type, flags, start, end, 1);
 336                 if (insert_point != NULL)
 337                         TAILQ_INSERT_BEFORE(insert_point, range, lf_link);
 338                 else
 339                         TAILQ_INSERT_TAIL(&lock->lf_range, range, lf_link);
 340                 goto do_wakeup;
 341         }
 342
 343         lock_needed = 1;
 344
 345         if (lf_overlap_left(first_match, start, end)) {
 346                 KKASSERT((flags & F_POSIX) != 0);
 347                 if (first_match->lf_end > end) {
 348                         if (first_match->lf_type == type)
 349                                 goto do_wakeup;
 350                         if (lf_count_change(owner, 2)) {
 351                                 error = ENOLCK;
 352                                 goto do_cleanup;
 353                         }
 354                         range = new_range1;
 355                         new_range1 = NULL;
 356                         lf_create_range(range, owner, type, flags,
 357                                         start, end, 1);
 358                         if (insert_point != NULL)
 359                                 TAILQ_INSERT_BEFORE(insert_point, range,
 360                                                     lf_link);
 361                         else
 362                                 TAILQ_INSERT_TAIL(&lock->lf_range, range,
 363                                                   lf_link);
 364                         insert_point = range;
 365                         range = new_range2;
 366                         new_range2 = NULL;
 367                         lf_create_range(range, owner, first_match->lf_type,
 368                                         first_match->lf_flags, end + 1,
 369                                         first_match->lf_end, 1);
 370                         TAILQ_INSERT_AFTER(&lock->lf_range, insert_point,
 371                                            range, lf_link);
 372                         first_match->lf_flags &= ~F_NOEND;
 373                         first_match->lf_end = start - 1;
 374                         if (type == F_RDLCK)
 375                                 wakeup_needed = 1;
 376                         goto do_wakeup;
 377                 }
 378                 /*
 379                  * left match, but not right match
 380                  *
 381                  * handle the lf_type != type case directly,
 382                  * merge the other case with the !lock_needed path.
 383                  */
 384                 if (first_match->lf_type != type) {
 385                         /*
 386                          * This is needed if the lockf acquisition below fails.
 387                          */
 388                         orig_first_match = first_match;
 389                         orig_end = first_match->lf_end;
 390                         orig_flags = first_match->lf_flags;
 391                         first_match->lf_end = start - 1;
 392                         first_match->lf_flags &= ~F_NOEND;
 393                         if (type == F_RDLCK)
 394                                 wakeup_needed = 1;
 395                         /* Try to find the next matching range */
 396                         range = TAILQ_NEXT(first_match, lf_link);
 397                         while (range != NULL) {
 398                                 if (range->lf_owner == owner &&
 399                                     lf_overlap(range, start, end))
 400                                         break;
 401                                 range = TAILQ_NEXT(range, lf_link);
 402                         }
 403                         if (range == NULL)
 404                                 goto do_wakeup;
 405                         first_match = range;
 406                         /* fall through to !left_match behaviour */
 407                 } else {
 408                         first_match->lf_end = end;
 409                         first_match->lf_flags |= flags & F_NOEND;
 410                         lock_needed = 0;
 411                 }
 412         }
 413
 414         if (lf_overlap_embedded(first_match, start, end)) {
 415                 if (first_match != insert_point) {
 416                         TAILQ_REMOVE(&lock->lf_range, first_match, lf_link);
 417                         TAILQ_INSERT_BEFORE(insert_point, first_match, lf_link);
 418                 }
 419                 first_match->lf_start = start;
 420                 first_match->lf_end = end;
 421                 first_match->lf_flags |= flags & F_NOEND;
 422                 first_match->lf_type = type;
 423                 lock_needed = 0;
 424         }
 425
 426         if (lock_needed == 0) {
 427                 struct lockf_range *nrange;
 428
 429                 range = TAILQ_NEXT(first_match, lf_link);
 430                 while (range != NULL) {
 431                         if (range->lf_owner != owner) {
 432                                 range = TAILQ_NEXT(range, lf_link);
 433                                 continue;
 434                         }
 435                         if (lf_overlap_embedded(range, start, end)) {
 436                                 nrange = TAILQ_NEXT(range, lf_link);
 437                                 TAILQ_REMOVE(&lock->lf_range, range,
 438                                              lf_link);
 439                                 lf_count_change(owner, -1);
 440                                 lf_destroy_range(range, 1);
 441                                 range = nrange;
 442                                 continue;
 443                         }
 444                         if (lf_overlap_right(range, start, end) == 0) {
 445                                 range = TAILQ_NEXT(range, lf_link);
 446                                 continue;
 447                         }
 448                         if (range->lf_type != type) {
 449                                 range->lf_start = end + 1;
 450                                 nrange = TAILQ_NEXT(range, lf_link);
 451                                 TAILQ_REMOVE(&lock->lf_range, range, lf_link);
 452                                 while (nrange != NULL) {
 453                                         if (nrange->lf_start >= end + 1)
 454                                                 break;
 455                                         nrange = TAILQ_NEXT(nrange, lf_link);
 456                                 }
 457                                 if (nrange != NULL)
 458                                         TAILQ_INSERT_BEFORE(nrange, range,
 459                                                             lf_link);
 460                                 else
 461                                         TAILQ_INSERT_TAIL(&lock->lf_range,
 462                                                           range, lf_link);
 463                                 break;
 464                         }
 465                         first_match->lf_end = range->lf_end;
 466                         first_match->lf_flags |=
 467                             range->lf_flags & F_NOEND;
 468                         TAILQ_REMOVE(&lock->lf_range, range, lf_link);
 469                         lf_count_change(owner, -1);
 470                         lf_destroy_range(range, 1);
 471                         break;
 472                 }
 473                 goto do_wakeup;
 474         }
 475
 476         if (lf_overlap_right(first_match, start, end)) {
 477                 KKASSERT((flags & F_POSIX) != 0);
 478                 if (first_match->lf_type == type) {
 479                         first_match->lf_start = start;
 480                         if (first_match != insert_point) {
 481                                 TAILQ_REMOVE(&lock->lf_range, first_match,
 482                                              lf_link);
 483                                 TAILQ_INSERT_BEFORE(insert_point, first_match,
 484                                                     lf_link);
 485                         }
 486                         goto do_wakeup;
 487                 }
 488                 if (lf_count_change(owner, 1)) {
 489                         if (orig_first_match != NULL) {
 490                                 orig_first_match->lf_end = orig_end;
 491                                 orig_first_match->lf_flags = orig_end;
 492                         }
 493                         error = ENOLCK;
 494                         goto do_cleanup;
 495                 }
 496                 first_match->lf_start = end + 1;
 497                 KKASSERT(new_range1 != NULL);
 498                 range = new_range1;
 499                 new_range1 = NULL;
 500                 lf_create_range(range, owner, type, flags, start, end, 1);
 501                 TAILQ_INSERT_BEFORE(insert_point, range, lf_link);
 502                 range = TAILQ_NEXT(first_match, lf_link);
 503                 TAILQ_REMOVE(&lock->lf_range, first_match, lf_link);
 504                 while (range != NULL) {
 505                         if (range->lf_start >= first_match->lf_start)
 506                                 break;
 507                         range = TAILQ_NEXT(range, lf_link);
 508                 }
 509                 if (range != NULL)
 510                         TAILQ_INSERT_BEFORE(range, first_match, lf_link);
 511                 else
 512                         TAILQ_INSERT_TAIL(&lock->lf_range, first_match, lf_link);
 513                 goto do_wakeup;
 514         }
 515
 516 do_wakeup:
 517 #ifdef LOCKF_DEBUG
 518         if (lf_print_ranges)
 519                 lf_print_lock(lock);
 520 #endif
 521         if (wakeup_needed)
 522                 lf_wakeup(lock, start, end);
 523         error = 0;
 524 do_cleanup:
 525         if (new_range1 != NULL)
 526                 lf_destroy_range(new_range1, 0);
 527         if (new_range2 != NULL)
 528                 lf_destroy_range(new_range2, 0);
 529         return(error);
 530 }
 531
 532 static int
 533 lf_clearlock(struct lockf *lock, struct proc *owner, int type, int flags,
 534              off_t start, off_t end)
 535 {
 536         struct lockf_range *range, *trange;
 537         struct lockf_range *new_range;
 538         int error = 0;
 539
 540         new_range = lf_alloc_range();
 541
 542         TAILQ_FOREACH_MUTABLE(range, &lock->lf_range, lf_link, trange) {
 543                 if (range->lf_end < start)
 544                         continue;
 545                 if (range->lf_start > end)
 546                         break;
 547                 if (range->lf_owner != owner)
 548                         continue;
 549                 if (lf_overlap_embedded(range, start, end)) {
 550                         TAILQ_REMOVE(&lock->lf_range, range, lf_link);
 551                         /* flock-locks are equal */
 552                         if (range->lf_flags & F_POSIX)
 553                                 lf_count_change(owner, -1);
 554                         lf_destroy_range(range, 1);
 555                         continue;
 556                 }
 557                 if (lf_overlap_left2(range, start, end)) {
 558                         KKASSERT(range->lf_flags & F_POSIX);
 559                         if (lf_overlap_right2(range, start, end)) {
 560                                 struct lockf_range *nrange;
 561
 562                                 if (lf_count_change(owner, 1)) {
 563                                         error = ENOLCK;
 564                                         goto do_cleanup;
 565                                 }
 566                                 nrange = new_range;
 567                                 new_range = NULL;
 568                                 lf_create_range(nrange, range->lf_owner,
 569                                     range->lf_type, range->lf_flags,
 570                                     end + 1, range->lf_end, 1);
 571                                 range->lf_end = start;
 572                                 range->lf_flags &= ~F_NOEND;
 573                                 for (; range != NULL;
 574                                      range = TAILQ_NEXT(range, lf_link))
 575                                         if (range->lf_start >= nrange->lf_start)
 576                                                 break;
 577                                 if (range != NULL)
 578                                         TAILQ_INSERT_BEFORE(range, nrange,
 579                                                             lf_link);
 580                                 else
 581                                         TAILQ_INSERT_TAIL(&lock->lf_range,
 582                                                           nrange, lf_link);
 583                                 break;
 584                         }
 585                         range->lf_end = start - 1;
 586                         range->lf_flags &= ~F_NOEND;
 587                         continue;
 588                 }
 589                 if (lf_overlap_right2(range, start, end)) {
 590                         struct lockf_range *nrange = range;
 591
 592                         KKASSERT(range->lf_flags & F_POSIX);
 593
 594                         range  = TAILQ_NEXT(range, lf_link);
 595                         TAILQ_REMOVE(&lock->lf_range, nrange, lf_link);
 596                         for (; range != NULL;
 597                              range = TAILQ_NEXT(range, lf_link))
 598                                 if (range->lf_start >= nrange->lf_start)
 599                                         break;
 600                         if (range != NULL)
 601                                 TAILQ_INSERT_BEFORE(range, nrange, lf_link);
 602                         else
 603                                 TAILQ_INSERT_TAIL(&lock->lf_range, nrange,
 604                                                   lf_link);
 605                         break;
 606                 }
 607         }
 608
 609         lf_wakeup(lock, start, end);
 610         error = 0;
 611
 612 do_cleanup:
 613         if (new_range != NULL)
 614                 lf_destroy_range(new_range, 0);
 615
 616         return(error);
 617 }
 618
 619 /*
 620  * Check whether there is a blocking lock,
 621  * and if so return its process identifier.
 622  */
 623 static int
 624 lf_getlock(struct flock *fl, struct lockf *lock, struct proc *owner,
 625            int type, int flags, off_t start, off_t end)
 626 {
 627         struct lockf_range *range;
 628
 629         TAILQ_FOREACH(range, &lock->lf_range, lf_link)
 630                 if (range->lf_owner != owner &&
 631                     lf_overlap(range, start, end) &&
 632                     (type == F_WRLCK || range->lf_type == F_WRLCK))
 633                         break;
 634         if (range == NULL) {
 635                 fl->l_type = F_UNLCK;
 636                 return(0);
 637         }
 638         fl->l_type = range->lf_type;
 639         fl->l_whence = SEEK_SET;
 640         fl->l_start = range->lf_start;
 641         if (range->lf_flags & F_NOEND)
 642                 fl->l_len = 0;
 643         else
 644                 fl->l_len = range->lf_end - range->lf_start + 1;
 645         if (range->lf_owner != NULL && (range->lf_flags & F_POSIX))
 646                 fl->l_pid = range->lf_owner->p_pid;
 647         else
 648                 fl->l_pid = -1;
 649         return(0);
 650 }
 651
 652 /*
 653  * Check wether range and [start, end] overlap.
 654  */
 655 static int
 656 lf_overlap(const struct lockf_range *range, off_t start, off_t end)
 657 {
 658         if (range->lf_start >= start && range->lf_start <= end)
 659                 return(1);
 660         else if (start >= range->lf_start && start <= range->lf_end)
 661                 return(1);
 662         else
 663                 return(0);
 664 }
 665
 666 /*
 667  * Wakeup pending lock attempts.
 668  */
 669 static void
 670 lf_wakeup(struct lockf *lock, off_t start, off_t end)
 671 {
 672         struct lockf_range *range, *nrange;
 673         TAILQ_FOREACH_MUTABLE(range, &lock->lf_blocked, lf_link, nrange) {
 674                 if (lf_overlap(range, start, end) == 0)
 675                         continue;
 676                 TAILQ_REMOVE(&lock->lf_blocked, range, lf_link);
 677                 range->lf_flags = 1;
 678                 wakeup(range);
 679         }
 680 }
 681
 682 static int
 683 lf_overlap_left(const struct lockf_range *range, off_t start, off_t end)
 684 {
 685         if (range->lf_start < start && range->lf_end >= start - 1 &&
 686             range->lf_end <= end)
 687                 return(1);
 688         else
 689                 return(0);
 690
 691 }
 692
 693 static int
 694 lf_overlap_right(const struct lockf_range *range, off_t start, off_t end)
 695 {
 696         if (range->lf_end > end && range->lf_start >= start &&
 697             range->lf_start - 1 <= end)
 698                 return(1);
 699         else
 700                 return(0);
 701 }
 702
 703 static int
 704 lf_overlap_left2(const struct lockf_range *range, off_t start, off_t end)
 705 {
 706         if (range->lf_start < start && range->lf_end >= start &&
 707             range->lf_end <= end)
 708                 return(1);
 709         else
 710                 return(0);
 711
 712 }
 713
 714 static int
 715 lf_overlap_right2(const struct lockf_range *range, off_t start, off_t end)
 716 {
 717         if (range->lf_end > end && range->lf_start >= start &&
 718             range->lf_start <= end)
 719                 return(1);
 720         else
 721                 return(0);
 722 }
 723
 724 static int
 725 lf_overlap_embedded(const struct lockf_range *range, off_t start, off_t end)
 726 {
 727         if (range->lf_start >= start && range->lf_end <= end)
 728                 return(1);
 729         else
 730                 return(0);
 731 }
 732
 733 /*
 734  * Allocate a range structure and initialize it sufficiently such that
 735  * lf_destroy_range() does not barf.
 736  */
 737 static struct lockf_range *
 738 lf_alloc_range(void)
 739 {
 740         struct lockf_range *range;
 741
 742 #ifdef INVARIANTS
 743         lf_global_counter++;
 744 #endif
 745         range = malloc(sizeof(struct lockf_range), M_LOCKF, M_WAITOK);
 746         range->lf_owner = NULL;
 747         return(range);
 748 }
 749
 750 static void
 751 lf_create_range(struct lockf_range *range, struct proc *owner, int type,
 752                 int flags, off_t start, off_t end, int accounting)
 753 {
 754         KKASSERT(start <= end);
 755         if (owner != NULL && (flags & F_POSIX) && accounting)
 756                 ++owner->p_numposixlocks;
 757         range->lf_type = type;
 758         range->lf_flags = flags;
 759         range->lf_start = start;
 760         range->lf_end = end;
 761         range->lf_owner = owner;
 762
 763 #ifdef LOCKF_DEBUG
 764         if (lf_print_ranges)
 765                 printf("lf_create_range: %lld..%lld\n", range->lf_start,
 766                        range->lf_end);
 767 #endif
 768 }
 769
 770 static void
 771 lf_destroy_range(struct lockf_range *range, int accounting)
 772 {
 773         struct proc *owner = range->lf_owner;
 774         int flags = range->lf_flags;
 775
 776 #ifdef LOCKF_DEBUG
 777         if (lf_print_ranges)
 778                 printf("lf_destroy_range: %lld..%lld\n", range->lf_start,
 779                        range->lf_end);
 780 #endif
 781
 782         free(range, M_LOCKF);
 783         if (owner != NULL && (flags & F_POSIX) && accounting) {
 784                 --owner->p_numposixlocks;
 785                 KASSERT(owner->p_numposixlocks >= 0,
 786                         ("Negative number of POSIX locks held by process: %d",
 787                          owner->p_numposixlocks));
 788         }
 789
 790 #ifdef INVARIANTS
 791         lf_global_counter--;
 792         KKASSERT(lf_global_counter>=0);
 793 #endif
 794 }
 795
 796 #ifdef LOCKF_DEBUG
 797 static void
 798 lf_print_lock(const struct lockf *lock)
 799 {
 800         struct lockf_range *range;
 801
 802         if (TAILQ_EMPTY(&lock->lf_range))
 803                 printf("lockf %p: no ranges locked\n", lock);
 804         else
 805                 printf("lockf %p:\n", lock);
 806         TAILQ_FOREACH(range, &lock->lf_range, lf_link)
 807                 printf("\t%lld..%lld type %s owned by %d\n",
 808                        range->lf_start, range->lf_end,
 809                        range->lf_type == F_RDLCK ? "shared" : "exclusive",
 810                        range->lf_flags & F_POSIX ? range->lf_owner->p_pid : -1);
 811         if (TAILQ_EMPTY(&lock->lf_blocked))
 812                 printf("no process waiting for range\n");
 813         else
 814                 printf("blocked locks:");
 815         TAILQ_FOREACH(range, &lock->lf_range, lf_link)
 816                 printf("\t%lld..%lld type %s waiting on %p\n",
 817                        range->lf_start, range->lf_end,
 818                        range->lf_type == F_RDLCK ? "shared" : "exclusive",
 819                        range);
 820 }
 821 #endif /* LOCKF_DEBUG */