Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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FreeBSD/Linux Kernel Cross Reference
sys/kern/kern_lockf.c
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1 /*- 2 * Copyright (c) 1982, 1986, 1989, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * This code is derived from software contributed to Berkeley by 6 * Scooter Morris at Genentech Inc. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 4. Neither the name of the University nor the names of its contributors 17 * may be used to endorse or promote products derived from this software 18 * without specific prior written permission. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30 * SUCH DAMAGE. 31 * 32 * @(#)ufs_lockf.c 8.3 (Berkeley) 1/6/94 33 */ 34 35 #include <sys/cdefs.h> 36 __FBSDID("$FreeBSD$"); 37 38 #include "opt_debug_lockf.h" 39 40 #include <sys/param.h> 41 #include <sys/systm.h> 42 #include <sys/kernel.h> 43 #include <sys/limits.h> 44 #include <sys/lock.h> 45 #include <sys/mount.h> 46 #include <sys/mutex.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/lockf.h> 53 54 /* 55 * This variable controls the maximum number of processes that will 56 * be checked in doing deadlock detection. 57 */ 58 static int maxlockdepth = MAXDEPTH; 59 60 #ifdef LOCKF_DEBUG 61 #include <sys/sysctl.h> 62 63 #include <ufs/ufs/quota.h> 64 #include <ufs/ufs/inode.h> 65 66 67 static int lockf_debug = 0; 68 SYSCTL_INT(_debug, OID_AUTO, lockf_debug, CTLFLAG_RW, &lockf_debug, 0, ""); 69 #endif 70 71 MALLOC_DEFINE(M_LOCKF, "lockf", "Byte-range locking structures"); 72 73 #define NOLOCKF (struct lockf *)0 74 #define SELF 0x1 75 #define OTHERS 0x2 76 static int lf_clearlock(struct lockf *, struct lockf **); 77 static int lf_findoverlap(struct lockf *, 78 struct lockf *, int, struct lockf ***, struct lockf **); 79 static struct lockf * 80 lf_getblock(struct lockf *); 81 static int lf_getlock(struct lockf *, struct flock *); 82 static int lf_setlock(struct lockf *, struct vnode *, struct lockf **); 83 static void lf_split(struct lockf *, struct lockf *, struct lockf **); 84 static void lf_wakelock(struct lockf *); 85 #ifdef LOCKF_DEBUG 86 static void lf_print(char *, struct lockf *); 87 static void lf_printlist(char *, struct lockf *); 88 #endif 89 90 /* 91 * Advisory record locking support 92 */ 93 int 94 lf_advlock(ap, head, size) 95 struct vop_advlock_args /* { 96 struct vnode *a_vp; 97 caddr_t a_id; 98 int a_op; 99 struct flock *a_fl; 100 int a_flags; 101 } */ *ap; 102 struct lockf **head; 103 u_quad_t size; 104 { 105 struct flock *fl = ap->a_fl; 106 struct lockf *lock; 107 struct vnode *vp = ap->a_vp; 108 off_t start, end, oadd; 109 struct lockf *clean, *n; 110 int error; 111 112 /* 113 * Convert the flock structure into a start and end. 114 */ 115 switch (fl->l_whence) { 116 117 case SEEK_SET: 118 case SEEK_CUR: 119 /* 120 * Caller is responsible for adding any necessary offset 121 * when SEEK_CUR is used. 122 */ 123 start = fl->l_start; 124 break; 125 126 case SEEK_END: 127 if (size > OFF_MAX || 128 (fl->l_start > 0 && size > OFF_MAX - fl->l_start)) 129 return (EOVERFLOW); 130 start = size + fl->l_start; 131 break; 132 133 default: 134 return (EINVAL); 135 } 136 if (start < 0) 137 return (EINVAL); 138 if (fl->l_len < 0) { 139 if (start == 0) 140 return (EINVAL); 141 end = start - 1; 142 start += fl->l_len; 143 if (start < 0) 144 return (EINVAL); 145 } else if (fl->l_len == 0) 146 end = -1; 147 else { 148 oadd = fl->l_len - 1; 149 if (oadd > OFF_MAX - start) 150 return (EOVERFLOW); 151 end = start + oadd; 152 } 153 /* 154 * Avoid the common case of unlocking when inode has no locks. 155 */ 156 if (*head == (struct lockf *)0) { 157 if (ap->a_op != F_SETLK) { 158 fl->l_type = F_UNLCK; 159 return (0); 160 } 161 } 162 /* 163 * Allocate a spare structure in case we have to split. 164 */ 165 clean = NULL; 166 if (ap->a_op == F_SETLK || ap->a_op == F_UNLCK) { 167 MALLOC(clean, struct lockf *, sizeof *lock, M_LOCKF, M_WAITOK); 168 clean->lf_next = NULL; 169 } 170 /* 171 * Create the lockf structure 172 */ 173 MALLOC(lock, struct lockf *, sizeof *lock, M_LOCKF, M_WAITOK); 174 lock->lf_start = start; 175 lock->lf_end = end; 176 lock->lf_id = ap->a_id; 177 /* 178 * XXX The problem is that VTOI is ufs specific, so it will 179 * break LOCKF_DEBUG for all other FS's other than UFS because 180 * it casts the vnode->data ptr to struct inode *. 181 */ 182 /* lock->lf_inode = VTOI(ap->a_vp); */ 183 lock->lf_inode = (struct inode *)0; 184 lock->lf_type = fl->l_type; 185 lock->lf_head = head; 186 lock->lf_next = (struct lockf *)0; 187 TAILQ_INIT(&lock->lf_blkhd); 188 lock->lf_flags = ap->a_flags; 189 /* 190 * Do the requested operation. 191 */ 192 VI_LOCK(vp); 193 switch(ap->a_op) { 194 case F_SETLK: 195 error = lf_setlock(lock, vp, &clean); 196 break; 197 198 case F_UNLCK: 199 error = lf_clearlock(lock, &clean); 200 lock->lf_next = clean; 201 clean = lock; 202 break; 203 204 case F_GETLK: 205 error = lf_getlock(lock, fl); 206 lock->lf_next = clean; 207 clean = lock; 208 break; 209 210 default: 211 lock->lf_next = clean; 212 clean = lock; 213 error = EINVAL; 214 break; 215 } 216 VI_UNLOCK(vp); 217 for (lock = clean; lock != NULL; ) { 218 n = lock->lf_next; 219 free(lock, M_LOCKF); 220 lock = n; 221 } 222 return (error); 223 } 224 225 /* 226 * Set a byte-range lock. 227 */ 228 static int 229 lf_setlock(lock, vp, clean) 230 struct lockf *lock; 231 struct vnode *vp; 232 struct lockf **clean; 233 { 234 struct lockf *block; 235 struct lockf **head = lock->lf_head; 236 struct lockf **prev, *overlap, *ltmp; 237 static char lockstr[] = "lockf"; 238 int ovcase, priority, needtolink, error; 239 240 #ifdef LOCKF_DEBUG 241 if (lockf_debug & 1) 242 lf_print("lf_setlock", lock); 243 #endif /* LOCKF_DEBUG */ 244 245 /* 246 * Set the priority 247 */ 248 priority = PLOCK; 249 if (lock->lf_type == F_WRLCK) 250 priority += 4; 251 priority |= PCATCH; 252 /* 253 * Scan lock list for this file looking for locks that would block us. 254 */ 255 while ((block = lf_getblock(lock))) { 256 /* 257 * Free the structure and return if nonblocking. 258 */ 259 if ((lock->lf_flags & F_WAIT) == 0) { 260 lock->lf_next = *clean; 261 *clean = lock; 262 return (EAGAIN); 263 } 264 /* 265 * We are blocked. Since flock style locks cover 266 * the whole file, there is no chance for deadlock. 267 * For byte-range locks we must check for deadlock. 268 * 269 * Deadlock detection is done by looking through the 270 * wait channels to see if there are any cycles that 271 * involve us. MAXDEPTH is set just to make sure we 272 * do not go off into neverland. 273 */ 274 if ((lock->lf_flags & F_POSIX) && 275 (block->lf_flags & F_POSIX)) { 276 struct proc *wproc; 277 struct proc *nproc; 278 struct thread *td; 279 struct lockf *waitblock; 280 int i = 0; 281 282 /* The block is waiting on something */ 283 wproc = (struct proc *)block->lf_id; 284 restart: 285 nproc = NULL; 286 PROC_SLOCK(wproc); 287 FOREACH_THREAD_IN_PROC(wproc, td) { 288 thread_lock(td); 289 while (td->td_wchan && 290 (td->td_wmesg == lockstr) && 291 (i++ < maxlockdepth)) { 292 waitblock = (struct lockf *)td->td_wchan; 293 /* Get the owner of the blocking lock */ 294 waitblock = waitblock->lf_next; 295 if ((waitblock->lf_flags & F_POSIX) == 0) 296 break; 297 nproc = (struct proc *)waitblock->lf_id; 298 if (nproc == (struct proc *)lock->lf_id) { 299 PROC_SUNLOCK(wproc); 300 thread_unlock(td); 301 lock->lf_next = *clean; 302 *clean = lock; 303 return (EDEADLK); 304 } 305 } 306 thread_unlock(td); 307 } 308 PROC_SUNLOCK(wproc); 309 wproc = nproc; 310 if (wproc) 311 goto restart; 312 } 313 /* 314 * For flock type locks, we must first remove 315 * any shared locks that we hold before we sleep 316 * waiting for an exclusive lock. 317 */ 318 if ((lock->lf_flags & F_FLOCK) && 319 lock->lf_type == F_WRLCK) { 320 lock->lf_type = F_UNLCK; 321 (void) lf_clearlock(lock, clean); 322 lock->lf_type = F_WRLCK; 323 } 324 /* 325 * Add our lock to the blocked list and sleep until we're free. 326 * Remember who blocked us (for deadlock detection). 327 */ 328 lock->lf_next = block; 329 TAILQ_INSERT_TAIL(&block->lf_blkhd, lock, lf_block); 330 #ifdef LOCKF_DEBUG 331 if (lockf_debug & 1) { 332 lf_print("lf_setlock: blocking on", block); 333 lf_printlist("lf_setlock", block); 334 } 335 #endif /* LOCKF_DEBUG */ 336 error = msleep(lock, VI_MTX(vp), priority, lockstr, 0); 337 /* 338 * We may have been awakened by a signal and/or by a 339 * debugger continuing us (in which cases we must remove 340 * ourselves from the blocked list) and/or by another 341 * process releasing a lock (in which case we have 342 * already been removed from the blocked list and our 343 * lf_next field set to NOLOCKF). 344 */ 345 if (lock->lf_next) { 346 TAILQ_REMOVE(&lock->lf_next->lf_blkhd, lock, lf_block); 347 lock->lf_next = NOLOCKF; 348 } 349 if (error) { 350 lock->lf_next = *clean; 351 *clean = lock; 352 return (error); 353 } 354 } 355 /* 356 * No blocks!! Add the lock. Note that we will 357 * downgrade or upgrade any overlapping locks this 358 * process already owns. 359 * 360 * Skip over locks owned by other processes. 361 * Handle any locks that overlap and are owned by ourselves. 362 */ 363 prev = head; 364 block = *head; 365 needtolink = 1; 366 for (;;) { 367 ovcase = lf_findoverlap(block, lock, SELF, &prev, &overlap); 368 if (ovcase) 369 block = overlap->lf_next; 370 /* 371 * Six cases: 372 * 0) no overlap 373 * 1) overlap == lock 374 * 2) overlap contains lock 375 * 3) lock contains overlap 376 * 4) overlap starts before lock 377 * 5) overlap ends after lock 378 */ 379 switch (ovcase) { 380 case 0: /* no overlap */ 381 if (needtolink) { 382 *prev = lock; 383 lock->lf_next = overlap; 384 } 385 break; 386 387 case 1: /* overlap == lock */ 388 /* 389 * If downgrading lock, others may be 390 * able to acquire it. 391 */ 392 if (lock->lf_type == F_RDLCK && 393 overlap->lf_type == F_WRLCK) 394 lf_wakelock(overlap); 395 overlap->lf_type = lock->lf_type; 396 lock->lf_next = *clean; 397 *clean = lock; 398 lock = overlap; /* for debug output below */ 399 break; 400 401 case 2: /* overlap contains lock */ 402 /* 403 * Check for common starting point and different types. 404 */ 405 if (overlap->lf_type == lock->lf_type) { 406 lock->lf_next = *clean; 407 *clean = lock; 408 lock = overlap; /* for debug output below */ 409 break; 410 } 411 if (overlap->lf_start == lock->lf_start) { 412 *prev = lock; 413 lock->lf_next = overlap; 414 overlap->lf_start = lock->lf_end + 1; 415 } else 416 lf_split(overlap, lock, clean); 417 lf_wakelock(overlap); 418 break; 419 420 case 3: /* lock contains overlap */ 421 /* 422 * If downgrading lock, others may be able to 423 * acquire it, otherwise take the list. 424 */ 425 if (lock->lf_type == F_RDLCK && 426 overlap->lf_type == F_WRLCK) { 427 lf_wakelock(overlap); 428 } else { 429 while (!TAILQ_EMPTY(&overlap->lf_blkhd)) { 430 ltmp = TAILQ_FIRST(&overlap->lf_blkhd); 431 TAILQ_REMOVE(&overlap->lf_blkhd, ltmp, 432 lf_block); 433 TAILQ_INSERT_TAIL(&lock->lf_blkhd, 434 ltmp, lf_block); 435 ltmp->lf_next = lock; 436 } 437 } 438 /* 439 * Add the new lock if necessary and delete the overlap. 440 */ 441 if (needtolink) { 442 *prev = lock; 443 lock->lf_next = overlap->lf_next; 444 prev = &lock->lf_next; 445 needtolink = 0; 446 } else 447 *prev = overlap->lf_next; 448 overlap->lf_next = *clean; 449 *clean = overlap; 450 continue; 451 452 case 4: /* overlap starts before lock */ 453 /* 454 * Add lock after overlap on the list. 455 */ 456 lock->lf_next = overlap->lf_next; 457 overlap->lf_next = lock; 458 overlap->lf_end = lock->lf_start - 1; 459 prev = &lock->lf_next; 460 lf_wakelock(overlap); 461 needtolink = 0; 462 continue; 463 464 case 5: /* overlap ends after lock */ 465 /* 466 * Add the new lock before overlap. 467 */ 468 if (needtolink) { 469 *prev = lock; 470 lock->lf_next = overlap; 471 } 472 overlap->lf_start = lock->lf_end + 1; 473 lf_wakelock(overlap); 474 break; 475 } 476 break; 477 } 478 #ifdef LOCKF_DEBUG 479 if (lockf_debug & 1) { 480 lf_print("lf_setlock: got the lock", lock); 481 lf_printlist("lf_setlock", lock); 482 } 483 #endif /* LOCKF_DEBUG */ 484 return (0); 485 } 486 487 /* 488 * Remove a byte-range lock on an inode. 489 * 490 * Generally, find the lock (or an overlap to that lock) 491 * and remove it (or shrink it), then wakeup anyone we can. 492 */ 493 static int 494 lf_clearlock(unlock, clean) 495 struct lockf *unlock; 496 struct lockf **clean; 497 { 498 struct lockf **head = unlock->lf_head; 499 register struct lockf *lf = *head; 500 struct lockf *overlap, **prev; 501 int ovcase; 502 503 if (lf == NOLOCKF) 504 return (0); 505 #ifdef LOCKF_DEBUG 506 if (unlock->lf_type != F_UNLCK) 507 panic("lf_clearlock: bad type"); 508 if (lockf_debug & 1) 509 lf_print("lf_clearlock", unlock); 510 #endif /* LOCKF_DEBUG */ 511 prev = head; 512 while ((ovcase = lf_findoverlap(lf, unlock, SELF, &prev, &overlap))) { 513 /* 514 * Wakeup the list of locks to be retried. 515 */ 516 lf_wakelock(overlap); 517 518 switch (ovcase) { 519 520 case 1: /* overlap == lock */ 521 *prev = overlap->lf_next; 522 overlap->lf_next = *clean; 523 *clean = overlap; 524 break; 525 526 case 2: /* overlap contains lock: split it */ 527 if (overlap->lf_start == unlock->lf_start) { 528 overlap->lf_start = unlock->lf_end + 1; 529 break; 530 } 531 lf_split(overlap, unlock, clean); 532 overlap->lf_next = unlock->lf_next; 533 break; 534 535 case 3: /* lock contains overlap */ 536 *prev = overlap->lf_next; 537 lf = overlap->lf_next; 538 overlap->lf_next = *clean; 539 *clean = overlap; 540 continue; 541 542 case 4: /* overlap starts before lock */ 543 overlap->lf_end = unlock->lf_start - 1; 544 prev = &overlap->lf_next; 545 lf = overlap->lf_next; 546 continue; 547 548 case 5: /* overlap ends after lock */ 549 overlap->lf_start = unlock->lf_end + 1; 550 break; 551 } 552 break; 553 } 554 #ifdef LOCKF_DEBUG 555 if (lockf_debug & 1) 556 lf_printlist("lf_clearlock", unlock); 557 #endif /* LOCKF_DEBUG */ 558 return (0); 559 } 560 561 /* 562 * Check whether there is a blocking lock, 563 * and if so return its process identifier. 564 */ 565 static int 566 lf_getlock(lock, fl) 567 register struct lockf *lock; 568 register struct flock *fl; 569 { 570 register struct lockf *block; 571 572 #ifdef LOCKF_DEBUG 573 if (lockf_debug & 1) 574 lf_print("lf_getlock", lock); 575 #endif /* LOCKF_DEBUG */ 576 577 if ((block = lf_getblock(lock))) { 578 fl->l_type = block->lf_type; 579 fl->l_whence = SEEK_SET; 580 fl->l_start = block->lf_start; 581 if (block->lf_end == -1) 582 fl->l_len = 0; 583 else 584 fl->l_len = block->lf_end - block->lf_start + 1; 585 if (block->lf_flags & F_POSIX) 586 fl->l_pid = ((struct proc *)(block->lf_id))->p_pid; 587 else 588 fl->l_pid = -1; 589 } else { 590 fl->l_type = F_UNLCK; 591 } 592 return (0); 593 } 594 595 /* 596 * Walk the list of locks for an inode and 597 * return the first blocking lock. 598 */ 599 static struct lockf * 600 lf_getblock(lock) 601 register struct lockf *lock; 602 { 603 struct lockf **prev, *overlap, *lf = *(lock->lf_head); 604 int ovcase; 605 606 prev = lock->lf_head; 607 while ((ovcase = lf_findoverlap(lf, lock, OTHERS, &prev, &overlap))) { 608 /* 609 * We've found an overlap, see if it blocks us 610 */ 611 if ((lock->lf_type == F_WRLCK || overlap->lf_type == F_WRLCK)) 612 return (overlap); 613 /* 614 * Nope, point to the next one on the list and 615 * see if it blocks us 616 */ 617 lf = overlap->lf_next; 618 } 619 return (NOLOCKF); 620 } 621 622 /* 623 * Walk the list of locks for an inode to 624 * find an overlapping lock (if any). 625 * 626 * NOTE: this returns only the FIRST overlapping lock. There 627 * may be more than one. 628 */ 629 static int 630 lf_findoverlap(lf, lock, type, prev, overlap) 631 register struct lockf *lf; 632 struct lockf *lock; 633 int type; 634 struct lockf ***prev; 635 struct lockf **overlap; 636 { 637 off_t start, end; 638 639 *overlap = lf; 640 if (lf == NOLOCKF) 641 return (0); 642 #ifdef LOCKF_DEBUG 643 if (lockf_debug & 2) 644 lf_print("lf_findoverlap: looking for overlap in", lock); 645 #endif /* LOCKF_DEBUG */ 646 start = lock->lf_start; 647 end = lock->lf_end; 648 while (lf != NOLOCKF) { 649 if (((type & SELF) && lf->lf_id != lock->lf_id) || 650 ((type & OTHERS) && lf->lf_id == lock->lf_id)) { 651 *prev = &lf->lf_next; 652 *overlap = lf = lf->lf_next; 653 continue; 654 } 655 #ifdef LOCKF_DEBUG 656 if (lockf_debug & 2) 657 lf_print("\tchecking", lf); 658 #endif /* LOCKF_DEBUG */ 659 /* 660 * OK, check for overlap 661 * 662 * Six cases: 663 * 0) no overlap 664 * 1) overlap == lock 665 * 2) overlap contains lock 666 * 3) lock contains overlap 667 * 4) overlap starts before lock 668 * 5) overlap ends after lock 669 */ 670 if ((lf->lf_end != -1 && start > lf->lf_end) || 671 (end != -1 && lf->lf_start > end)) { 672 /* Case 0 */ 673 #ifdef LOCKF_DEBUG 674 if (lockf_debug & 2) 675 printf("no overlap\n"); 676 #endif /* LOCKF_DEBUG */ 677 if ((type & SELF) && end != -1 && lf->lf_start > end) 678 return (0); 679 *prev = &lf->lf_next; 680 *overlap = lf = lf->lf_next; 681 continue; 682 } 683 if ((lf->lf_start == start) && (lf->lf_end == end)) { 684 /* Case 1 */ 685 #ifdef LOCKF_DEBUG 686 if (lockf_debug & 2) 687 printf("overlap == lock\n"); 688 #endif /* LOCKF_DEBUG */ 689 return (1); 690 } 691 if ((lf->lf_start <= start) && 692 (end != -1) && 693 ((lf->lf_end >= end) || (lf->lf_end == -1))) { 694 /* Case 2 */ 695 #ifdef LOCKF_DEBUG 696 if (lockf_debug & 2) 697 printf("overlap contains lock\n"); 698 #endif /* LOCKF_DEBUG */ 699 return (2); 700 } 701 if (start <= lf->lf_start && 702 (end == -1 || 703 (lf->lf_end != -1 && end >= lf->lf_end))) { 704 /* Case 3 */ 705 #ifdef LOCKF_DEBUG 706 if (lockf_debug & 2) 707 printf("lock contains overlap\n"); 708 #endif /* LOCKF_DEBUG */ 709 return (3); 710 } 711 if ((lf->lf_start < start) && 712 ((lf->lf_end >= start) || (lf->lf_end == -1))) { 713 /* Case 4 */ 714 #ifdef LOCKF_DEBUG 715 if (lockf_debug & 2) 716 printf("overlap starts before lock\n"); 717 #endif /* LOCKF_DEBUG */ 718 return (4); 719 } 720 if ((lf->lf_start > start) && 721 (end != -1) && 722 ((lf->lf_end > end) || (lf->lf_end == -1))) { 723 /* Case 5 */ 724 #ifdef LOCKF_DEBUG 725 if (lockf_debug & 2) 726 printf("overlap ends after lock\n"); 727 #endif /* LOCKF_DEBUG */ 728 return (5); 729 } 730 panic("lf_findoverlap: default"); 731 } 732 return (0); 733 } 734 735 /* 736 * Split a lock and a contained region into 737 * two or three locks as necessary. 738 */ 739 static void 740 lf_split(lock1, lock2, split) 741 struct lockf *lock1; 742 struct lockf *lock2; 743 struct lockf **split; 744 { 745 struct lockf *splitlock; 746 747 #ifdef LOCKF_DEBUG 748 if (lockf_debug & 2) { 749 lf_print("lf_split", lock1); 750 lf_print("splitting from", lock2); 751 } 752 #endif /* LOCKF_DEBUG */ 753 /* 754 * Check to see if spliting into only two pieces. 755 */ 756 if (lock1->lf_start == lock2->lf_start) { 757 lock1->lf_start = lock2->lf_end + 1; 758 lock2->lf_next = lock1; 759 return; 760 } 761 if (lock1->lf_end == lock2->lf_end) { 762 lock1->lf_end = lock2->lf_start - 1; 763 lock2->lf_next = lock1->lf_next; 764 lock1->lf_next = lock2; 765 return; 766 } 767 /* 768 * Make a new lock consisting of the last part of 769 * the encompassing lock. We use the preallocated 770 * splitlock so we don't have to block. 771 */ 772 splitlock = *split; 773 KASSERT(splitlock != NULL, ("no split")); 774 *split = splitlock->lf_next; 775 bcopy(lock1, splitlock, sizeof *splitlock); 776 splitlock->lf_start = lock2->lf_end + 1; 777 TAILQ_INIT(&splitlock->lf_blkhd); 778 lock1->lf_end = lock2->lf_start - 1; 779 /* 780 * OK, now link it in 781 */ 782 splitlock->lf_next = lock1->lf_next; 783 lock2->lf_next = splitlock; 784 lock1->lf_next = lock2; 785 } 786 787 /* 788 * Wakeup a blocklist 789 */ 790 static void 791 lf_wakelock(listhead) 792 struct lockf *listhead; 793 { 794 register struct lockf *wakelock; 795 796 while (!TAILQ_EMPTY(&listhead->lf_blkhd)) { 797 wakelock = TAILQ_FIRST(&listhead->lf_blkhd); 798 TAILQ_REMOVE(&listhead->lf_blkhd, wakelock, lf_block); 799 wakelock->lf_next = NOLOCKF; 800 #ifdef LOCKF_DEBUG 801 if (lockf_debug & 2) 802 lf_print("lf_wakelock: awakening", wakelock); 803 #endif /* LOCKF_DEBUG */ 804 wakeup(wakelock); 805 } 806 } 807 808 #ifdef LOCKF_DEBUG 809 /* 810 * Print out a lock. 811 */ 812 static void 813 lf_print(tag, lock) 814 char *tag; 815 register struct lockf *lock; 816 { 817 818 printf("%s: lock %p for ", tag, (void *)lock); 819 if (lock->lf_flags & F_POSIX) 820 printf("proc %ld", (long)((struct proc *)lock->lf_id)->p_pid); 821 else 822 printf("id %p", (void *)lock->lf_id); 823 if (lock->lf_inode != (struct inode *)0) 824 printf(" in ino %ju on dev <%s>, %s, start %jd, end %jd", 825 (uintmax_t)lock->lf_inode->i_number, 826 devtoname(lock->lf_inode->i_dev), 827 lock->lf_type == F_RDLCK ? "shared" : 828 lock->lf_type == F_WRLCK ? "exclusive" : 829 lock->lf_type == F_UNLCK ? "unlock" : "unknown", 830 (intmax_t)lock->lf_start, (intmax_t)lock->lf_end); 831 else 832 printf(" %s, start %jd, end %jd", 833 lock->lf_type == F_RDLCK ? "shared" : 834 lock->lf_type == F_WRLCK ? "exclusive" : 835 lock->lf_type == F_UNLCK ? "unlock" : "unknown", 836 (intmax_t)lock->lf_start, (intmax_t)lock->lf_end); 837 if (!TAILQ_EMPTY(&lock->lf_blkhd)) 838 printf(" block %p\n", (void *)TAILQ_FIRST(&lock->lf_blkhd)); 839 else 840 printf("\n"); 841 } 842 843 static void 844 lf_printlist(tag, lock) 845 char *tag; 846 struct lockf *lock; 847 { 848 register struct lockf *lf, *blk; 849 850 if (lock->lf_inode == (struct inode *)0) 851 return; 852 853 printf("%s: Lock list for ino %ju on dev <%s>:\n", 854 tag, (uintmax_t)lock->lf_inode->i_number, 855 devtoname(lock->lf_inode->i_dev)); 856 for (lf = lock->lf_inode->i_lockf; lf; lf = lf->lf_next) { 857 printf("\tlock %p for ",(void *)lf); 858 if (lf->lf_flags & F_POSIX) 859 printf("proc %ld", 860 (long)((struct proc *)lf->lf_id)->p_pid); 861 else 862 printf("id %p", (void *)lf->lf_id); 863 printf(", %s, start %jd, end %jd", 864 lf->lf_type == F_RDLCK ? "shared" : 865 lf->lf_type == F_WRLCK ? "exclusive" : 866 lf->lf_type == F_UNLCK ? "unlock" : 867 "unknown", (intmax_t)lf->lf_start, (intmax_t)lf->lf_end); 868 TAILQ_FOREACH(blk, &lf->lf_blkhd, lf_block) { 869 printf("\n\t\tlock request %p for ", (void *)blk); 870 if (blk->lf_flags & F_POSIX) 871 printf("proc %ld", 872 (long)((struct proc *)blk->lf_id)->p_pid); 873 else 874 printf("id %p", (void *)blk->lf_id); 875 printf(", %s, start %jd, end %jd", 876 blk->lf_type == F_RDLCK ? "shared" : 877 blk->lf_type == F_WRLCK ? "exclusive" : 878 blk->lf_type == F_UNLCK ? "unlock" : 879 "unknown", (intmax_t)blk->lf_start, 880 (intmax_t)blk->lf_end); 881 if (!TAILQ_EMPTY(&blk->lf_blkhd)) 882 panic("lf_printlist: bad list"); 883 } 884 printf("\n"); 885 } 886 } 887 #endif /* LOCKF_DEBUG */
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