vfs_bio.c revision 1.227
1/* $NetBSD: vfs_bio.c,v 1.227 2011/01/17 07:13:32 uebayasi Exp $ */ 2 3/*- 4 * Copyright (c) 2007, 2008, 2009 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to The NetBSD Foundation 8 * by Andrew Doran, and by Wasabi Systems, 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 * 19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 29 * POSSIBILITY OF SUCH DAMAGE. 30 */ 31 32/*- 33 * Copyright (c) 1982, 1986, 1989, 1993 34 * The Regents of the University of California. All rights reserved. 35 * (c) UNIX System Laboratories, Inc. 36 * All or some portions of this file are derived from material licensed 37 * to the University of California by American Telephone and Telegraph 38 * Co. or Unix System Laboratories, Inc. and are reproduced herein with 39 * the permission of UNIX System Laboratories, Inc. 40 * 41 * Redistribution and use in source and binary forms, with or without 42 * modification, are permitted provided that the following conditions 43 * are met: 44 * 1. Redistributions of source code must retain the above copyright 45 * notice, this list of conditions and the following disclaimer. 46 * 2. Redistributions in binary form must reproduce the above copyright 47 * notice, this list of conditions and the following disclaimer in the 48 * documentation and/or other materials provided with the distribution. 49 * 3. Neither the name of the University nor the names of its contributors 50 * may be used to endorse or promote products derived from this software 51 * without specific prior written permission. 52 * 53 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 54 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 55 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 56 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 57 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 58 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 59 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 60 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 61 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 62 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 63 * SUCH DAMAGE. 64 * 65 * @(#)vfs_bio.c 8.6 (Berkeley) 1/11/94 66 */ 67 68/*- 69 * Copyright (c) 1994 Christopher G. Demetriou 70 * 71 * Redistribution and use in source and binary forms, with or without 72 * modification, are permitted provided that the following conditions 73 * are met: 74 * 1. Redistributions of source code must retain the above copyright 75 * notice, this list of conditions and the following disclaimer. 76 * 2. Redistributions in binary form must reproduce the above copyright 77 * notice, this list of conditions and the following disclaimer in the 78 * documentation and/or other materials provided with the distribution. 79 * 3. All advertising materials mentioning features or use of this software 80 * must display the following acknowledgement: 81 * This product includes software developed by the University of 82 * California, Berkeley and its contributors. 83 * 4. Neither the name of the University nor the names of its contributors 84 * may be used to endorse or promote products derived from this software 85 * without specific prior written permission. 86 * 87 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 88 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 89 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 90 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 91 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 92 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 93 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 94 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 95 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 96 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 97 * SUCH DAMAGE. 98 * 99 * @(#)vfs_bio.c 8.6 (Berkeley) 1/11/94 100 */ 101 102/* 103 * The buffer cache subsystem. 104 * 105 * Some references: 106 * Bach: The Design of the UNIX Operating System (Prentice Hall, 1986) 107 * Leffler, et al.: The Design and Implementation of the 4.3BSD 108 * UNIX Operating System (Addison Welley, 1989) 109 * 110 * Locking 111 * 112 * There are three locks: 113 * - bufcache_lock: protects global buffer cache state. 114 * - BC_BUSY: a long term per-buffer lock. 115 * - buf_t::b_objlock: lock on completion (biowait vs biodone). 116 * 117 * For buffers associated with vnodes (a most common case) b_objlock points 118 * to the vnode_t::v_interlock. Otherwise, it points to generic buffer_lock. 119 * 120 * Lock order: 121 * bufcache_lock -> 122 * buf_t::b_objlock 123 */ 124 125#include <sys/cdefs.h> 126__KERNEL_RCSID(0, "$NetBSD: vfs_bio.c,v 1.227 2011/01/17 07:13:32 uebayasi Exp $"); 127 128#include "opt_bufcache.h" 129 130#include <sys/param.h> 131#include <sys/systm.h> 132#include <sys/kernel.h> 133#include <sys/proc.h> 134#include <sys/buf.h> 135#include <sys/vnode.h> 136#include <sys/mount.h> 137#include <sys/resourcevar.h> 138#include <sys/sysctl.h> 139#include <sys/conf.h> 140#include <sys/kauth.h> 141#include <sys/fstrans.h> 142#include <sys/intr.h> 143#include <sys/cpu.h> 144#include <sys/wapbl.h> 145 146#include <uvm/uvm.h> /* extern struct uvm uvm */ 147 148#include <miscfs/specfs/specdev.h> 149 150#ifndef BUFPAGES 151# define BUFPAGES 0 152#endif 153 154#ifdef BUFCACHE 155# if (BUFCACHE < 5) || (BUFCACHE > 95) 156# error BUFCACHE is not between 5 and 95 157# endif 158#else 159# define BUFCACHE 15 160#endif 161 162u_int nbuf; /* desired number of buffer headers */ 163u_int bufpages = BUFPAGES; /* optional hardwired count */ 164u_int bufcache = BUFCACHE; /* max % of RAM to use for buffer cache */ 165 166/* Function prototypes */ 167struct bqueue; 168 169static void buf_setwm(void); 170static int buf_trim(void); 171static void *bufpool_page_alloc(struct pool *, int); 172static void bufpool_page_free(struct pool *, void *); 173static buf_t *bio_doread(struct vnode *, daddr_t, int, 174 kauth_cred_t, int); 175static buf_t *getnewbuf(int, int, int); 176static int buf_lotsfree(void); 177static int buf_canrelease(void); 178static u_long buf_mempoolidx(u_long); 179static u_long buf_roundsize(u_long); 180static void *buf_malloc(size_t); 181static void buf_mrelease(void *, size_t); 182static void binsheadfree(buf_t *, struct bqueue *); 183static void binstailfree(buf_t *, struct bqueue *); 184int count_lock_queue(void); /* XXX */ 185#ifdef DEBUG 186static int checkfreelist(buf_t *, struct bqueue *, int); 187#endif 188static void biointr(void *); 189static void biodone2(buf_t *); 190static void bref(buf_t *); 191static void brele(buf_t *); 192static void sysctl_kern_buf_setup(void); 193static void sysctl_vm_buf_setup(void); 194 195/* 196 * Definitions for the buffer hash lists. 197 */ 198#define BUFHASH(dvp, lbn) \ 199 (&bufhashtbl[(((long)(dvp) >> 8) + (int)(lbn)) & bufhash]) 200LIST_HEAD(bufhashhdr, buf) *bufhashtbl, invalhash; 201u_long bufhash; 202struct bqueue bufqueues[BQUEUES]; 203 204static kcondvar_t needbuffer_cv; 205 206/* 207 * Buffer queue lock. 208 */ 209kmutex_t bufcache_lock; 210kmutex_t buffer_lock; 211 212/* Software ISR for completed transfers. */ 213static void *biodone_sih; 214 215/* Buffer pool for I/O buffers. */ 216static pool_cache_t buf_cache; 217static pool_cache_t bufio_cache; 218 219/* XXX - somewhat gross.. */ 220#if MAXBSIZE == 0x2000 221#define NMEMPOOLS 5 222#elif MAXBSIZE == 0x4000 223#define NMEMPOOLS 6 224#elif MAXBSIZE == 0x8000 225#define NMEMPOOLS 7 226#else 227#define NMEMPOOLS 8 228#endif 229 230#define MEMPOOL_INDEX_OFFSET 9 /* smallest pool is 512 bytes */ 231#if (1 << (NMEMPOOLS + MEMPOOL_INDEX_OFFSET - 1)) != MAXBSIZE 232#error update vfs_bio buffer memory parameters 233#endif 234 235/* Buffer memory pools */ 236static struct pool bmempools[NMEMPOOLS]; 237 238static struct vm_map *buf_map; 239 240/* 241 * Buffer memory pool allocator. 242 */ 243static void * 244bufpool_page_alloc(struct pool *pp, int flags) 245{ 246 247 return (void *)uvm_km_alloc(buf_map, 248 MAXBSIZE, MAXBSIZE, 249 ((flags & PR_WAITOK) ? 0 : UVM_KMF_NOWAIT | UVM_KMF_TRYLOCK) 250 | UVM_KMF_WIRED); 251} 252 253static void 254bufpool_page_free(struct pool *pp, void *v) 255{ 256 257 uvm_km_free(buf_map, (vaddr_t)v, MAXBSIZE, UVM_KMF_WIRED); 258} 259 260static struct pool_allocator bufmempool_allocator = { 261 .pa_alloc = bufpool_page_alloc, 262 .pa_free = bufpool_page_free, 263 .pa_pagesz = MAXBSIZE, 264}; 265 266/* Buffer memory management variables */ 267u_long bufmem_valimit; 268u_long bufmem_hiwater; 269u_long bufmem_lowater; 270u_long bufmem; 271 272/* 273 * MD code can call this to set a hard limit on the amount 274 * of virtual memory used by the buffer cache. 275 */ 276int 277buf_setvalimit(vsize_t sz) 278{ 279 280 /* We need to accommodate at least NMEMPOOLS of MAXBSIZE each */ 281 if (sz < NMEMPOOLS * MAXBSIZE) 282 return EINVAL; 283 284 bufmem_valimit = sz; 285 return 0; 286} 287 288static void 289buf_setwm(void) 290{ 291 292 bufmem_hiwater = buf_memcalc(); 293 /* lowater is approx. 2% of memory (with bufcache = 15) */ 294#define BUFMEM_WMSHIFT 3 295#define BUFMEM_HIWMMIN (64 * 1024 << BUFMEM_WMSHIFT) 296 if (bufmem_hiwater < BUFMEM_HIWMMIN) 297 /* Ensure a reasonable minimum value */ 298 bufmem_hiwater = BUFMEM_HIWMMIN; 299 bufmem_lowater = bufmem_hiwater >> BUFMEM_WMSHIFT; 300} 301 302#ifdef DEBUG 303int debug_verify_freelist = 0; 304static int 305checkfreelist(buf_t *bp, struct bqueue *dp, int ison) 306{ 307 buf_t *b; 308 309 if (!debug_verify_freelist) 310 return 1; 311 312 TAILQ_FOREACH(b, &dp->bq_queue, b_freelist) { 313 if (b == bp) 314 return ison ? 1 : 0; 315 } 316 317 return ison ? 0 : 1; 318} 319#endif 320 321/* 322 * Insq/Remq for the buffer hash lists. 323 * Call with buffer queue locked. 324 */ 325static void 326binsheadfree(buf_t *bp, struct bqueue *dp) 327{ 328 329 KASSERT(mutex_owned(&bufcache_lock)); 330 KASSERT(bp->b_freelistindex == -1); 331 TAILQ_INSERT_HEAD(&dp->bq_queue, bp, b_freelist); 332 dp->bq_bytes += bp->b_bufsize; 333 bp->b_freelistindex = dp - bufqueues; 334} 335 336static void 337binstailfree(buf_t *bp, struct bqueue *dp) 338{ 339 340 KASSERT(mutex_owned(&bufcache_lock)); 341 KASSERT(bp->b_freelistindex == -1); 342 TAILQ_INSERT_TAIL(&dp->bq_queue, bp, b_freelist); 343 dp->bq_bytes += bp->b_bufsize; 344 bp->b_freelistindex = dp - bufqueues; 345} 346 347void 348bremfree(buf_t *bp) 349{ 350 struct bqueue *dp; 351 int bqidx = bp->b_freelistindex; 352 353 KASSERT(mutex_owned(&bufcache_lock)); 354 355 KASSERT(bqidx != -1); 356 dp = &bufqueues[bqidx]; 357 KDASSERT(checkfreelist(bp, dp, 1)); 358 KASSERT(dp->bq_bytes >= bp->b_bufsize); 359 TAILQ_REMOVE(&dp->bq_queue, bp, b_freelist); 360 dp->bq_bytes -= bp->b_bufsize; 361 362 /* For the sysctl helper. */ 363 if (bp == dp->bq_marker) 364 dp->bq_marker = NULL; 365 366#if defined(DIAGNOSTIC) 367 bp->b_freelistindex = -1; 368#endif /* defined(DIAGNOSTIC) */ 369} 370 371/* 372 * Add a reference to an buffer structure that came from buf_cache. 373 */ 374static inline void 375bref(buf_t *bp) 376{ 377 378 KASSERT(mutex_owned(&bufcache_lock)); 379 KASSERT(bp->b_refcnt > 0); 380 381 bp->b_refcnt++; 382} 383 384/* 385 * Free an unused buffer structure that came from buf_cache. 386 */ 387static inline void 388brele(buf_t *bp) 389{ 390 391 KASSERT(mutex_owned(&bufcache_lock)); 392 KASSERT(bp->b_refcnt > 0); 393 394 if (bp->b_refcnt-- == 1) { 395 buf_destroy(bp); 396#ifdef DEBUG 397 memset((char *)bp, 0, sizeof(*bp)); 398#endif 399 pool_cache_put(buf_cache, bp); 400 } 401} 402 403/* 404 * note that for some ports this is used by pmap bootstrap code to 405 * determine kva size. 406 */ 407u_long 408buf_memcalc(void) 409{ 410 u_long n; 411 412 /* 413 * Determine the upper bound of memory to use for buffers. 414 * 415 * - If bufpages is specified, use that as the number 416 * pages. 417 * 418 * - Otherwise, use bufcache as the percentage of 419 * physical memory. 420 */ 421 if (bufpages != 0) { 422 n = bufpages; 423 } else { 424 if (bufcache < 5) { 425 printf("forcing bufcache %d -> 5", bufcache); 426 bufcache = 5; 427 } 428 if (bufcache > 95) { 429 printf("forcing bufcache %d -> 95", bufcache); 430 bufcache = 95; 431 } 432 n = calc_cache_size(buf_map, bufcache, 433 (buf_map != kernel_map) ? 100 : BUFCACHE_VA_MAXPCT) 434 / PAGE_SIZE; 435 } 436 437 n <<= PAGE_SHIFT; 438 if (bufmem_valimit != 0 && n > bufmem_valimit) 439 n = bufmem_valimit; 440 441 return (n); 442} 443 444/* 445 * Initialize buffers and hash links for buffers. 446 */ 447void 448bufinit(void) 449{ 450 struct bqueue *dp; 451 int use_std; 452 u_int i; 453 454 mutex_init(&bufcache_lock, MUTEX_DEFAULT, IPL_NONE); 455 mutex_init(&buffer_lock, MUTEX_DEFAULT, IPL_NONE); 456 cv_init(&needbuffer_cv, "needbuf"); 457 458 if (bufmem_valimit != 0) { 459 vaddr_t minaddr = 0, maxaddr; 460 buf_map = uvm_km_suballoc(kernel_map, &minaddr, &maxaddr, 461 bufmem_valimit, 0, false, 0); 462 if (buf_map == NULL) 463 panic("bufinit: cannot allocate submap"); 464 } else 465 buf_map = kernel_map; 466 467 /* 468 * Initialize buffer cache memory parameters. 469 */ 470 bufmem = 0; 471 buf_setwm(); 472 473 /* On "small" machines use small pool page sizes where possible */ 474 use_std = (physmem < atop(16*1024*1024)); 475 476 /* 477 * Also use them on systems that can map the pool pages using 478 * a direct-mapped segment. 479 */ 480#ifdef PMAP_MAP_POOLPAGE 481 use_std = 1; 482#endif 483 484 buf_cache = pool_cache_init(sizeof(buf_t), 0, 0, 0, 485 "bufpl", NULL, IPL_SOFTBIO, NULL, NULL, NULL); 486 bufio_cache = pool_cache_init(sizeof(buf_t), 0, 0, 0, 487 "biopl", NULL, IPL_BIO, NULL, NULL, NULL); 488 489 bufmempool_allocator.pa_backingmap = buf_map; 490 for (i = 0; i < NMEMPOOLS; i++) { 491 struct pool_allocator *pa; 492 struct pool *pp = &bmempools[i]; 493 u_int size = 1 << (i + MEMPOOL_INDEX_OFFSET); 494 char *name = kmem_alloc(8, KM_SLEEP); /* XXX: never freed */ 495 if (__predict_true(size >= 1024)) 496 (void)snprintf(name, 8, "buf%dk", size / 1024); 497 else 498 (void)snprintf(name, 8, "buf%db", size); 499 pa = (size <= PAGE_SIZE && use_std) 500 ? &pool_allocator_nointr 501 : &bufmempool_allocator; 502 pool_init(pp, size, 0, 0, 0, name, pa, IPL_NONE); 503 pool_setlowat(pp, 1); 504 pool_sethiwat(pp, 1); 505 } 506 507 /* Initialize the buffer queues */ 508 for (dp = bufqueues; dp < &bufqueues[BQUEUES]; dp++) { 509 TAILQ_INIT(&dp->bq_queue); 510 dp->bq_bytes = 0; 511 } 512 513 /* 514 * Estimate hash table size based on the amount of memory we 515 * intend to use for the buffer cache. The average buffer 516 * size is dependent on our clients (i.e. filesystems). 517 * 518 * For now, use an empirical 3K per buffer. 519 */ 520 nbuf = (bufmem_hiwater / 1024) / 3; 521 bufhashtbl = hashinit(nbuf, HASH_LIST, true, &bufhash); 522 523 sysctl_kern_buf_setup(); 524 sysctl_vm_buf_setup(); 525} 526 527void 528bufinit2(void) 529{ 530 531 biodone_sih = softint_establish(SOFTINT_BIO | SOFTINT_MPSAFE, biointr, 532 NULL); 533 if (biodone_sih == NULL) 534 panic("bufinit2: can't establish soft interrupt"); 535} 536 537static int 538buf_lotsfree(void) 539{ 540 int try, thresh; 541 542 /* Always allocate if less than the low water mark. */ 543 if (bufmem < bufmem_lowater) 544 return 1; 545 546 /* Never allocate if greater than the high water mark. */ 547 if (bufmem > bufmem_hiwater) 548 return 0; 549 550 /* If there's anything on the AGE list, it should be eaten. */ 551 if (TAILQ_FIRST(&bufqueues[BQ_AGE].bq_queue) != NULL) 552 return 0; 553 554 /* 555 * The probabily of getting a new allocation is inversely 556 * proportional to the current size of the cache, using 557 * a granularity of 16 steps. 558 */ 559 try = random() & 0x0000000fL; 560 561 /* Don't use "16 * bufmem" here to avoid a 32-bit overflow. */ 562 thresh = (bufmem - bufmem_lowater) / 563 ((bufmem_hiwater - bufmem_lowater) / 16); 564 565 if (try >= thresh) 566 return 1; 567 568 /* Otherwise don't allocate. */ 569 return 0; 570} 571 572/* 573 * Return estimate of bytes we think need to be 574 * released to help resolve low memory conditions. 575 * 576 * => called with bufcache_lock held. 577 */ 578static int 579buf_canrelease(void) 580{ 581 int pagedemand, ninvalid = 0; 582 583 KASSERT(mutex_owned(&bufcache_lock)); 584 585 if (bufmem < bufmem_lowater) 586 return 0; 587 588 if (bufmem > bufmem_hiwater) 589 return bufmem - bufmem_hiwater; 590 591 ninvalid += bufqueues[BQ_AGE].bq_bytes; 592 593 pagedemand = uvmexp.freetarg - uvmexp.free; 594 if (pagedemand < 0) 595 return ninvalid; 596 return MAX(ninvalid, MIN(2 * MAXBSIZE, 597 MIN((bufmem - bufmem_lowater) / 16, pagedemand * PAGE_SIZE))); 598} 599 600/* 601 * Buffer memory allocation helper functions 602 */ 603static u_long 604buf_mempoolidx(u_long size) 605{ 606 u_int n = 0; 607 608 size -= 1; 609 size >>= MEMPOOL_INDEX_OFFSET; 610 while (size) { 611 size >>= 1; 612 n += 1; 613 } 614 if (n >= NMEMPOOLS) 615 panic("buf mem pool index %d", n); 616 return n; 617} 618 619static u_long 620buf_roundsize(u_long size) 621{ 622 /* Round up to nearest power of 2 */ 623 return (1 << (buf_mempoolidx(size) + MEMPOOL_INDEX_OFFSET)); 624} 625 626static void * 627buf_malloc(size_t size) 628{ 629 u_int n = buf_mempoolidx(size); 630 void *addr; 631 632 while (1) { 633 addr = pool_get(&bmempools[n], PR_NOWAIT); 634 if (addr != NULL) 635 break; 636 637 /* No memory, see if we can free some. If so, try again */ 638 mutex_enter(&bufcache_lock); 639 if (buf_drain(1) > 0) { 640 mutex_exit(&bufcache_lock); 641 continue; 642 } 643 644 if (curlwp == uvm.pagedaemon_lwp) { 645 mutex_exit(&bufcache_lock); 646 return NULL; 647 } 648 649 /* Wait for buffers to arrive on the LRU queue */ 650 cv_timedwait(&needbuffer_cv, &bufcache_lock, hz / 4); 651 mutex_exit(&bufcache_lock); 652 } 653 654 return addr; 655} 656 657static void 658buf_mrelease(void *addr, size_t size) 659{ 660 661 pool_put(&bmempools[buf_mempoolidx(size)], addr); 662} 663 664/* 665 * bread()/breadn() helper. 666 */ 667static buf_t * 668bio_doread(struct vnode *vp, daddr_t blkno, int size, kauth_cred_t cred, 669 int async) 670{ 671 buf_t *bp; 672 struct mount *mp; 673 674 bp = getblk(vp, blkno, size, 0, 0); 675 676#ifdef DIAGNOSTIC 677 if (bp == NULL) { 678 panic("bio_doread: no such buf"); 679 } 680#endif 681 682 /* 683 * If buffer does not have data valid, start a read. 684 * Note that if buffer is BC_INVAL, getblk() won't return it. 685 * Therefore, it's valid if its I/O has completed or been delayed. 686 */ 687 if (!ISSET(bp->b_oflags, (BO_DONE | BO_DELWRI))) { 688 /* Start I/O for the buffer. */ 689 SET(bp->b_flags, B_READ | async); 690 if (async) 691 BIO_SETPRIO(bp, BPRIO_TIMELIMITED); 692 else 693 BIO_SETPRIO(bp, BPRIO_TIMECRITICAL); 694 VOP_STRATEGY(vp, bp); 695 696 /* Pay for the read. */ 697 curlwp->l_ru.ru_inblock++; 698 } else if (async) 699 brelse(bp, 0); 700 701 if (vp->v_type == VBLK) 702 mp = vp->v_specmountpoint; 703 else 704 mp = vp->v_mount; 705 706 /* 707 * Collect statistics on synchronous and asynchronous reads. 708 * Reads from block devices are charged to their associated 709 * filesystem (if any). 710 */ 711 if (mp != NULL) { 712 if (async == 0) 713 mp->mnt_stat.f_syncreads++; 714 else 715 mp->mnt_stat.f_asyncreads++; 716 } 717 718 return (bp); 719} 720 721/* 722 * Read a disk block. 723 * This algorithm described in Bach (p.54). 724 */ 725int 726bread(struct vnode *vp, daddr_t blkno, int size, kauth_cred_t cred, 727 int flags, buf_t **bpp) 728{ 729 buf_t *bp; 730 int error; 731 732 /* Get buffer for block. */ 733 bp = *bpp = bio_doread(vp, blkno, size, cred, 0); 734 735 /* Wait for the read to complete, and return result. */ 736 error = biowait(bp); 737 if (error == 0 && (flags & B_MODIFY) != 0) 738 error = fscow_run(bp, true); 739 740 return error; 741} 742 743/* 744 * Read-ahead multiple disk blocks. The first is sync, the rest async. 745 * Trivial modification to the breada algorithm presented in Bach (p.55). 746 */ 747int 748breadn(struct vnode *vp, daddr_t blkno, int size, daddr_t *rablks, 749 int *rasizes, int nrablks, kauth_cred_t cred, int flags, buf_t **bpp) 750{ 751 buf_t *bp; 752 int error, i; 753 754 bp = *bpp = bio_doread(vp, blkno, size, cred, 0); 755 756 /* 757 * For each of the read-ahead blocks, start a read, if necessary. 758 */ 759 mutex_enter(&bufcache_lock); 760 for (i = 0; i < nrablks; i++) { 761 /* If it's in the cache, just go on to next one. */ 762 if (incore(vp, rablks[i])) 763 continue; 764 765 /* Get a buffer for the read-ahead block */ 766 mutex_exit(&bufcache_lock); 767 (void) bio_doread(vp, rablks[i], rasizes[i], cred, B_ASYNC); 768 mutex_enter(&bufcache_lock); 769 } 770 mutex_exit(&bufcache_lock); 771 772 /* Otherwise, we had to start a read for it; wait until it's valid. */ 773 error = biowait(bp); 774 if (error == 0 && (flags & B_MODIFY) != 0) 775 error = fscow_run(bp, true); 776 return error; 777} 778 779/* 780 * Block write. Described in Bach (p.56) 781 */ 782int 783bwrite(buf_t *bp) 784{ 785 int rv, sync, wasdelayed; 786 struct vnode *vp; 787 struct mount *mp; 788 789 KASSERT(ISSET(bp->b_cflags, BC_BUSY)); 790 KASSERT(!cv_has_waiters(&bp->b_done)); 791 792 vp = bp->b_vp; 793 if (vp != NULL) { 794 KASSERT(bp->b_objlock == &vp->v_interlock); 795 if (vp->v_type == VBLK) 796 mp = vp->v_specmountpoint; 797 else 798 mp = vp->v_mount; 799 } else { 800 mp = NULL; 801 } 802 803 if (mp && mp->mnt_wapbl) { 804 if (bp->b_iodone != mp->mnt_wapbl_op->wo_wapbl_biodone) { 805 bdwrite(bp); 806 return 0; 807 } 808 } 809 810 /* 811 * Remember buffer type, to switch on it later. If the write was 812 * synchronous, but the file system was mounted with MNT_ASYNC, 813 * convert it to a delayed write. 814 * XXX note that this relies on delayed tape writes being converted 815 * to async, not sync writes (which is safe, but ugly). 816 */ 817 sync = !ISSET(bp->b_flags, B_ASYNC); 818 if (sync && mp != NULL && ISSET(mp->mnt_flag, MNT_ASYNC)) { 819 bdwrite(bp); 820 return (0); 821 } 822 823 /* 824 * Collect statistics on synchronous and asynchronous writes. 825 * Writes to block devices are charged to their associated 826 * filesystem (if any). 827 */ 828 if (mp != NULL) { 829 if (sync) 830 mp->mnt_stat.f_syncwrites++; 831 else 832 mp->mnt_stat.f_asyncwrites++; 833 } 834 835 /* 836 * Pay for the I/O operation and make sure the buf is on the correct 837 * vnode queue. 838 */ 839 bp->b_error = 0; 840 wasdelayed = ISSET(bp->b_oflags, BO_DELWRI); 841 CLR(bp->b_flags, B_READ); 842 if (wasdelayed) { 843 mutex_enter(&bufcache_lock); 844 mutex_enter(bp->b_objlock); 845 CLR(bp->b_oflags, BO_DONE | BO_DELWRI); 846 reassignbuf(bp, bp->b_vp); 847 mutex_exit(&bufcache_lock); 848 } else { 849 curlwp->l_ru.ru_oublock++; 850 mutex_enter(bp->b_objlock); 851 CLR(bp->b_oflags, BO_DONE | BO_DELWRI); 852 } 853 if (vp != NULL) 854 vp->v_numoutput++; 855 mutex_exit(bp->b_objlock); 856 857 /* Initiate disk write. */ 858 if (sync) 859 BIO_SETPRIO(bp, BPRIO_TIMECRITICAL); 860 else 861 BIO_SETPRIO(bp, BPRIO_TIMELIMITED); 862 863 VOP_STRATEGY(vp, bp); 864 865 if (sync) { 866 /* If I/O was synchronous, wait for it to complete. */ 867 rv = biowait(bp); 868 869 /* Release the buffer. */ 870 brelse(bp, 0); 871 872 return (rv); 873 } else { 874 return (0); 875 } 876} 877 878int 879vn_bwrite(void *v) 880{ 881 struct vop_bwrite_args *ap = v; 882 883 return (bwrite(ap->a_bp)); 884} 885 886/* 887 * Delayed write. 888 * 889 * The buffer is marked dirty, but is not queued for I/O. 890 * This routine should be used when the buffer is expected 891 * to be modified again soon, typically a small write that 892 * partially fills a buffer. 893 * 894 * NB: magnetic tapes cannot be delayed; they must be 895 * written in the order that the writes are requested. 896 * 897 * Described in Leffler, et al. (pp. 208-213). 898 */ 899void 900bdwrite(buf_t *bp) 901{ 902 903 KASSERT(bp->b_vp == NULL || bp->b_vp->v_tag != VT_UFS || 904 bp->b_vp->v_type == VBLK || ISSET(bp->b_flags, B_COWDONE)); 905 KASSERT(ISSET(bp->b_cflags, BC_BUSY)); 906 KASSERT(!cv_has_waiters(&bp->b_done)); 907 908 /* If this is a tape block, write the block now. */ 909 if (bdev_type(bp->b_dev) == D_TAPE) { 910 bawrite(bp); 911 return; 912 } 913 914 if (wapbl_vphaswapbl(bp->b_vp)) { 915 struct mount *mp = wapbl_vptomp(bp->b_vp); 916 917 if (bp->b_iodone != mp->mnt_wapbl_op->wo_wapbl_biodone) { 918 WAPBL_ADD_BUF(mp, bp); 919 } 920 } 921 922 /* 923 * If the block hasn't been seen before: 924 * (1) Mark it as having been seen, 925 * (2) Charge for the write, 926 * (3) Make sure it's on its vnode's correct block list. 927 */ 928 KASSERT(bp->b_vp == NULL || bp->b_objlock == &bp->b_vp->v_interlock); 929 930 if (!ISSET(bp->b_oflags, BO_DELWRI)) { 931 mutex_enter(&bufcache_lock); 932 mutex_enter(bp->b_objlock); 933 SET(bp->b_oflags, BO_DELWRI); 934 curlwp->l_ru.ru_oublock++; 935 reassignbuf(bp, bp->b_vp); 936 mutex_exit(&bufcache_lock); 937 } else { 938 mutex_enter(bp->b_objlock); 939 } 940 /* Otherwise, the "write" is done, so mark and release the buffer. */ 941 CLR(bp->b_oflags, BO_DONE); 942 mutex_exit(bp->b_objlock); 943 944 brelse(bp, 0); 945} 946 947/* 948 * Asynchronous block write; just an asynchronous bwrite(). 949 */ 950void 951bawrite(buf_t *bp) 952{ 953 954 KASSERT(ISSET(bp->b_cflags, BC_BUSY)); 955 956 SET(bp->b_flags, B_ASYNC); 957 VOP_BWRITE(bp); 958} 959 960/* 961 * Release a buffer on to the free lists. 962 * Described in Bach (p. 46). 963 */ 964void 965brelsel(buf_t *bp, int set) 966{ 967 struct bqueue *bufq; 968 struct vnode *vp; 969 970 KASSERT(mutex_owned(&bufcache_lock)); 971 KASSERT(!cv_has_waiters(&bp->b_done)); 972 KASSERT(bp->b_refcnt > 0); 973 974 SET(bp->b_cflags, set); 975 976 KASSERT(ISSET(bp->b_cflags, BC_BUSY)); 977 KASSERT(bp->b_iodone == NULL); 978 979 /* Wake up any processes waiting for any buffer to become free. */ 980 cv_signal(&needbuffer_cv); 981 982 /* Wake up any proceeses waiting for _this_ buffer to become */ 983 if (ISSET(bp->b_cflags, BC_WANTED)) 984 CLR(bp->b_cflags, BC_WANTED|BC_AGE); 985 986 /* If it's clean clear the copy-on-write flag. */ 987 if (ISSET(bp->b_flags, B_COWDONE)) { 988 mutex_enter(bp->b_objlock); 989 if (!ISSET(bp->b_oflags, BO_DELWRI)) 990 CLR(bp->b_flags, B_COWDONE); 991 mutex_exit(bp->b_objlock); 992 } 993 994 /* 995 * Determine which queue the buffer should be on, then put it there. 996 */ 997 998 /* If it's locked, don't report an error; try again later. */ 999 if (ISSET(bp->b_flags, B_LOCKED)) 1000 bp->b_error = 0; 1001 1002 /* If it's not cacheable, or an error, mark it invalid. */ 1003 if (ISSET(bp->b_cflags, BC_NOCACHE) || bp->b_error != 0) 1004 SET(bp->b_cflags, BC_INVAL); 1005 1006 if (ISSET(bp->b_cflags, BC_VFLUSH)) { 1007 /* 1008 * This is a delayed write buffer that was just flushed to 1009 * disk. It is still on the LRU queue. If it's become 1010 * invalid, then we need to move it to a different queue; 1011 * otherwise leave it in its current position. 1012 */ 1013 CLR(bp->b_cflags, BC_VFLUSH); 1014 if (!ISSET(bp->b_cflags, BC_INVAL|BC_AGE) && 1015 !ISSET(bp->b_flags, B_LOCKED) && bp->b_error == 0) { 1016 KDASSERT(checkfreelist(bp, &bufqueues[BQ_LRU], 1)); 1017 goto already_queued; 1018 } else { 1019 bremfree(bp); 1020 } 1021 } 1022 1023 KDASSERT(checkfreelist(bp, &bufqueues[BQ_AGE], 0)); 1024 KDASSERT(checkfreelist(bp, &bufqueues[BQ_LRU], 0)); 1025 KDASSERT(checkfreelist(bp, &bufqueues[BQ_LOCKED], 0)); 1026 1027 if ((bp->b_bufsize <= 0) || ISSET(bp->b_cflags, BC_INVAL)) { 1028 /* 1029 * If it's invalid or empty, dissociate it from its vnode 1030 * and put on the head of the appropriate queue. 1031 */ 1032 if (ISSET(bp->b_flags, B_LOCKED)) { 1033 if (wapbl_vphaswapbl(vp = bp->b_vp)) { 1034 struct mount *mp = wapbl_vptomp(vp); 1035 1036 KASSERT(bp->b_iodone 1037 != mp->mnt_wapbl_op->wo_wapbl_biodone); 1038 WAPBL_REMOVE_BUF(mp, bp); 1039 } 1040 } 1041 1042 mutex_enter(bp->b_objlock); 1043 CLR(bp->b_oflags, BO_DONE|BO_DELWRI); 1044 if ((vp = bp->b_vp) != NULL) { 1045 KASSERT(bp->b_objlock == &vp->v_interlock); 1046 reassignbuf(bp, bp->b_vp); 1047 brelvp(bp); 1048 mutex_exit(&vp->v_interlock); 1049 } else { 1050 KASSERT(bp->b_objlock == &buffer_lock); 1051 mutex_exit(bp->b_objlock); 1052 } 1053 1054 if (bp->b_bufsize <= 0) 1055 /* no data */ 1056 goto already_queued; 1057 else 1058 /* invalid data */ 1059 bufq = &bufqueues[BQ_AGE]; 1060 binsheadfree(bp, bufq); 1061 } else { 1062 /* 1063 * It has valid data. Put it on the end of the appropriate 1064 * queue, so that it'll stick around for as long as possible. 1065 * If buf is AGE, but has dependencies, must put it on last 1066 * bufqueue to be scanned, ie LRU. This protects against the 1067 * livelock where BQ_AGE only has buffers with dependencies, 1068 * and we thus never get to the dependent buffers in BQ_LRU. 1069 */ 1070 if (ISSET(bp->b_flags, B_LOCKED)) { 1071 /* locked in core */ 1072 bufq = &bufqueues[BQ_LOCKED]; 1073 } else if (!ISSET(bp->b_cflags, BC_AGE)) { 1074 /* valid data */ 1075 bufq = &bufqueues[BQ_LRU]; 1076 } else { 1077 /* stale but valid data */ 1078 bufq = &bufqueues[BQ_AGE]; 1079 } 1080 binstailfree(bp, bufq); 1081 } 1082already_queued: 1083 /* Unlock the buffer. */ 1084 CLR(bp->b_cflags, BC_AGE|BC_BUSY|BC_NOCACHE); 1085 CLR(bp->b_flags, B_ASYNC); 1086 cv_broadcast(&bp->b_busy); 1087 1088 if (bp->b_bufsize <= 0) 1089 brele(bp); 1090} 1091 1092void 1093brelse(buf_t *bp, int set) 1094{ 1095 1096 mutex_enter(&bufcache_lock); 1097 brelsel(bp, set); 1098 mutex_exit(&bufcache_lock); 1099} 1100 1101/* 1102 * Determine if a block is in the cache. 1103 * Just look on what would be its hash chain. If it's there, return 1104 * a pointer to it, unless it's marked invalid. If it's marked invalid, 1105 * we normally don't return the buffer, unless the caller explicitly 1106 * wants us to. 1107 */ 1108buf_t * 1109incore(struct vnode *vp, daddr_t blkno) 1110{ 1111 buf_t *bp; 1112 1113 KASSERT(mutex_owned(&bufcache_lock)); 1114 1115 /* Search hash chain */ 1116 LIST_FOREACH(bp, BUFHASH(vp, blkno), b_hash) { 1117 if (bp->b_lblkno == blkno && bp->b_vp == vp && 1118 !ISSET(bp->b_cflags, BC_INVAL)) { 1119 KASSERT(bp->b_objlock == &vp->v_interlock); 1120 return (bp); 1121 } 1122 } 1123 1124 return (NULL); 1125} 1126 1127/* 1128 * Get a block of requested size that is associated with 1129 * a given vnode and block offset. If it is found in the 1130 * block cache, mark it as having been found, make it busy 1131 * and return it. Otherwise, return an empty block of the 1132 * correct size. It is up to the caller to insure that the 1133 * cached blocks be of the correct size. 1134 */ 1135buf_t * 1136getblk(struct vnode *vp, daddr_t blkno, int size, int slpflag, int slptimeo) 1137{ 1138 int err, preserve; 1139 buf_t *bp; 1140 1141 mutex_enter(&bufcache_lock); 1142 loop: 1143 bp = incore(vp, blkno); 1144 if (bp != NULL) { 1145 err = bbusy(bp, ((slpflag & PCATCH) != 0), slptimeo, NULL); 1146 if (err != 0) { 1147 if (err == EPASSTHROUGH) 1148 goto loop; 1149 mutex_exit(&bufcache_lock); 1150 return (NULL); 1151 } 1152 KASSERT(!cv_has_waiters(&bp->b_done)); 1153#ifdef DIAGNOSTIC 1154 if (ISSET(bp->b_oflags, BO_DONE|BO_DELWRI) && 1155 bp->b_bcount < size && vp->v_type != VBLK) 1156 panic("getblk: block size invariant failed"); 1157#endif 1158 bremfree(bp); 1159 preserve = 1; 1160 } else { 1161 if ((bp = getnewbuf(slpflag, slptimeo, 0)) == NULL) 1162 goto loop; 1163 1164 if (incore(vp, blkno) != NULL) { 1165 /* The block has come into memory in the meantime. */ 1166 brelsel(bp, 0); 1167 goto loop; 1168 } 1169 1170 LIST_INSERT_HEAD(BUFHASH(vp, blkno), bp, b_hash); 1171 bp->b_blkno = bp->b_lblkno = bp->b_rawblkno = blkno; 1172 mutex_enter(&vp->v_interlock); 1173 bgetvp(vp, bp); 1174 mutex_exit(&vp->v_interlock); 1175 preserve = 0; 1176 } 1177 mutex_exit(&bufcache_lock); 1178 1179 /* 1180 * LFS can't track total size of B_LOCKED buffer (locked_queue_bytes) 1181 * if we re-size buffers here. 1182 */ 1183 if (ISSET(bp->b_flags, B_LOCKED)) { 1184 KASSERT(bp->b_bufsize >= size); 1185 } else { 1186 if (allocbuf(bp, size, preserve)) { 1187 mutex_enter(&bufcache_lock); 1188 LIST_REMOVE(bp, b_hash); 1189 mutex_exit(&bufcache_lock); 1190 brelse(bp, BC_INVAL); 1191 return NULL; 1192 } 1193 } 1194 BIO_SETPRIO(bp, BPRIO_DEFAULT); 1195 return (bp); 1196} 1197 1198/* 1199 * Get an empty, disassociated buffer of given size. 1200 */ 1201buf_t * 1202geteblk(int size) 1203{ 1204 buf_t *bp; 1205 int error; 1206 1207 mutex_enter(&bufcache_lock); 1208 while ((bp = getnewbuf(0, 0, 0)) == NULL) 1209 ; 1210 1211 SET(bp->b_cflags, BC_INVAL); 1212 LIST_INSERT_HEAD(&invalhash, bp, b_hash); 1213 mutex_exit(&bufcache_lock); 1214 BIO_SETPRIO(bp, BPRIO_DEFAULT); 1215 error = allocbuf(bp, size, 0); 1216 KASSERT(error == 0); 1217 return (bp); 1218} 1219 1220/* 1221 * Expand or contract the actual memory allocated to a buffer. 1222 * 1223 * If the buffer shrinks, data is lost, so it's up to the 1224 * caller to have written it out *first*; this routine will not 1225 * start a write. If the buffer grows, it's the callers 1226 * responsibility to fill out the buffer's additional contents. 1227 */ 1228int 1229allocbuf(buf_t *bp, int size, int preserve) 1230{ 1231 void *addr; 1232 vsize_t oldsize, desired_size; 1233 int oldcount; 1234 int delta; 1235 1236 desired_size = buf_roundsize(size); 1237 if (desired_size > MAXBSIZE) 1238 printf("allocbuf: buffer larger than MAXBSIZE requested"); 1239 1240 oldcount = bp->b_bcount; 1241 1242 bp->b_bcount = size; 1243 1244 oldsize = bp->b_bufsize; 1245 if (oldsize == desired_size) { 1246 /* 1247 * Do not short cut the WAPBL resize, as the buffer length 1248 * could still have changed and this would corrupt the 1249 * tracking of the transaction length. 1250 */ 1251 goto out; 1252 } 1253 1254 /* 1255 * If we want a buffer of a different size, re-allocate the 1256 * buffer's memory; copy old content only if needed. 1257 */ 1258 addr = buf_malloc(desired_size); 1259 if (addr == NULL) 1260 return ENOMEM; 1261 if (preserve) 1262 memcpy(addr, bp->b_data, MIN(oldsize,desired_size)); 1263 if (bp->b_data != NULL) 1264 buf_mrelease(bp->b_data, oldsize); 1265 bp->b_data = addr; 1266 bp->b_bufsize = desired_size; 1267 1268 /* 1269 * Update overall buffer memory counter (protected by bufcache_lock) 1270 */ 1271 delta = (long)desired_size - (long)oldsize; 1272 1273 mutex_enter(&bufcache_lock); 1274 if ((bufmem += delta) > bufmem_hiwater) { 1275 /* 1276 * Need to trim overall memory usage. 1277 */ 1278 while (buf_canrelease()) { 1279 if (curcpu()->ci_schedstate.spc_flags & 1280 SPCF_SHOULDYIELD) { 1281 mutex_exit(&bufcache_lock); 1282 preempt(); 1283 mutex_enter(&bufcache_lock); 1284 } 1285 if (buf_trim() == 0) 1286 break; 1287 } 1288 } 1289 mutex_exit(&bufcache_lock); 1290 1291 out: 1292 if (wapbl_vphaswapbl(bp->b_vp)) 1293 WAPBL_RESIZE_BUF(wapbl_vptomp(bp->b_vp), bp, oldsize, oldcount); 1294 1295 return 0; 1296} 1297 1298/* 1299 * Find a buffer which is available for use. 1300 * Select something from a free list. 1301 * Preference is to AGE list, then LRU list. 1302 * 1303 * Called with the buffer queues locked. 1304 * Return buffer locked. 1305 */ 1306buf_t * 1307getnewbuf(int slpflag, int slptimeo, int from_bufq) 1308{ 1309 buf_t *bp; 1310 struct vnode *vp; 1311 1312 start: 1313 KASSERT(mutex_owned(&bufcache_lock)); 1314 1315 /* 1316 * Get a new buffer from the pool. 1317 */ 1318 if (!from_bufq && buf_lotsfree()) { 1319 mutex_exit(&bufcache_lock); 1320 bp = pool_cache_get(buf_cache, PR_NOWAIT); 1321 if (bp != NULL) { 1322 memset((char *)bp, 0, sizeof(*bp)); 1323 buf_init(bp); 1324 SET(bp->b_cflags, BC_BUSY); /* mark buffer busy */ 1325 mutex_enter(&bufcache_lock); 1326#if defined(DIAGNOSTIC) 1327 bp->b_freelistindex = -1; 1328#endif /* defined(DIAGNOSTIC) */ 1329 return (bp); 1330 } 1331 mutex_enter(&bufcache_lock); 1332 } 1333 1334 KASSERT(mutex_owned(&bufcache_lock)); 1335 if ((bp = TAILQ_FIRST(&bufqueues[BQ_AGE].bq_queue)) != NULL || 1336 (bp = TAILQ_FIRST(&bufqueues[BQ_LRU].bq_queue)) != NULL) { 1337 KASSERT(!ISSET(bp->b_cflags, BC_BUSY) || ISSET(bp->b_cflags, BC_VFLUSH)); 1338 bremfree(bp); 1339 1340 /* Buffer is no longer on free lists. */ 1341 SET(bp->b_cflags, BC_BUSY); 1342 } else { 1343 /* 1344 * XXX: !from_bufq should be removed. 1345 */ 1346 if (!from_bufq || curlwp != uvm.pagedaemon_lwp) { 1347 /* wait for a free buffer of any kind */ 1348 if ((slpflag & PCATCH) != 0) 1349 (void)cv_timedwait_sig(&needbuffer_cv, 1350 &bufcache_lock, slptimeo); 1351 else 1352 (void)cv_timedwait(&needbuffer_cv, 1353 &bufcache_lock, slptimeo); 1354 } 1355 return (NULL); 1356 } 1357 1358#ifdef DIAGNOSTIC 1359 if (bp->b_bufsize <= 0) 1360 panic("buffer %p: on queue but empty", bp); 1361#endif 1362 1363 if (ISSET(bp->b_cflags, BC_VFLUSH)) { 1364 /* 1365 * This is a delayed write buffer being flushed to disk. Make 1366 * sure it gets aged out of the queue when it's finished, and 1367 * leave it off the LRU queue. 1368 */ 1369 CLR(bp->b_cflags, BC_VFLUSH); 1370 SET(bp->b_cflags, BC_AGE); 1371 goto start; 1372 } 1373 1374 KASSERT(ISSET(bp->b_cflags, BC_BUSY)); 1375 KASSERT(bp->b_refcnt > 0); 1376 KASSERT(!cv_has_waiters(&bp->b_done)); 1377 1378 /* 1379 * If buffer was a delayed write, start it and return NULL 1380 * (since we might sleep while starting the write). 1381 */ 1382 if (ISSET(bp->b_oflags, BO_DELWRI)) { 1383 /* 1384 * This buffer has gone through the LRU, so make sure it gets 1385 * reused ASAP. 1386 */ 1387 SET(bp->b_cflags, BC_AGE); 1388 mutex_exit(&bufcache_lock); 1389 bawrite(bp); 1390 mutex_enter(&bufcache_lock); 1391 return (NULL); 1392 } 1393 1394 vp = bp->b_vp; 1395 1396 /* clear out various other fields */ 1397 bp->b_cflags = BC_BUSY; 1398 bp->b_oflags = 0; 1399 bp->b_flags = 0; 1400 bp->b_dev = NODEV; 1401 bp->b_blkno = 0; 1402 bp->b_lblkno = 0; 1403 bp->b_rawblkno = 0; 1404 bp->b_iodone = 0; 1405 bp->b_error = 0; 1406 bp->b_resid = 0; 1407 bp->b_bcount = 0; 1408 1409 LIST_REMOVE(bp, b_hash); 1410 1411 /* Disassociate us from our vnode, if we had one... */ 1412 if (vp != NULL) { 1413 mutex_enter(&vp->v_interlock); 1414 brelvp(bp); 1415 mutex_exit(&vp->v_interlock); 1416 } 1417 1418 return (bp); 1419} 1420 1421/* 1422 * Attempt to free an aged buffer off the queues. 1423 * Called with queue lock held. 1424 * Returns the amount of buffer memory freed. 1425 */ 1426static int 1427buf_trim(void) 1428{ 1429 buf_t *bp; 1430 long size = 0; 1431 1432 KASSERT(mutex_owned(&bufcache_lock)); 1433 1434 /* Instruct getnewbuf() to get buffers off the queues */ 1435 if ((bp = getnewbuf(PCATCH, 1, 1)) == NULL) 1436 return 0; 1437 1438 KASSERT((bp->b_cflags & BC_WANTED) == 0); 1439 size = bp->b_bufsize; 1440 bufmem -= size; 1441 if (size > 0) { 1442 buf_mrelease(bp->b_data, size); 1443 bp->b_bcount = bp->b_bufsize = 0; 1444 } 1445 /* brelse() will return the buffer to the global buffer pool */ 1446 brelsel(bp, 0); 1447 return size; 1448} 1449 1450int 1451buf_drain(int n) 1452{ 1453 int size = 0, sz; 1454 1455 KASSERT(mutex_owned(&bufcache_lock)); 1456 1457 while (size < n && bufmem > bufmem_lowater) { 1458 sz = buf_trim(); 1459 if (sz <= 0) 1460 break; 1461 size += sz; 1462 } 1463 1464 return size; 1465} 1466 1467/* 1468 * Wait for operations on the buffer to complete. 1469 * When they do, extract and return the I/O's error value. 1470 */ 1471int 1472biowait(buf_t *bp) 1473{ 1474 1475 KASSERT(ISSET(bp->b_cflags, BC_BUSY)); 1476 KASSERT(bp->b_refcnt > 0); 1477 1478 mutex_enter(bp->b_objlock); 1479 while (!ISSET(bp->b_oflags, BO_DONE | BO_DELWRI)) 1480 cv_wait(&bp->b_done, bp->b_objlock); 1481 mutex_exit(bp->b_objlock); 1482 1483 return bp->b_error; 1484} 1485 1486/* 1487 * Mark I/O complete on a buffer. 1488 * 1489 * If a callback has been requested, e.g. the pageout 1490 * daemon, do so. Otherwise, awaken waiting processes. 1491 * 1492 * [ Leffler, et al., says on p.247: 1493 * "This routine wakes up the blocked process, frees the buffer 1494 * for an asynchronous write, or, for a request by the pagedaemon 1495 * process, invokes a procedure specified in the buffer structure" ] 1496 * 1497 * In real life, the pagedaemon (or other system processes) wants 1498 * to do async stuff to, and doesn't want the buffer brelse()'d. 1499 * (for swap pager, that puts swap buffers on the free lists (!!!), 1500 * for the vn device, that puts malloc'd buffers on the free lists!) 1501 */ 1502void 1503biodone(buf_t *bp) 1504{ 1505 int s; 1506 1507 KASSERT(!ISSET(bp->b_oflags, BO_DONE)); 1508 1509 if (cpu_intr_p()) { 1510 /* From interrupt mode: defer to a soft interrupt. */ 1511 s = splvm(); 1512 TAILQ_INSERT_TAIL(&curcpu()->ci_data.cpu_biodone, bp, b_actq); 1513 softint_schedule(biodone_sih); 1514 splx(s); 1515 } else { 1516 /* Process now - the buffer may be freed soon. */ 1517 biodone2(bp); 1518 } 1519} 1520 1521static void 1522biodone2(buf_t *bp) 1523{ 1524 void (*callout)(buf_t *); 1525 1526 mutex_enter(bp->b_objlock); 1527 /* Note that the transfer is done. */ 1528 if (ISSET(bp->b_oflags, BO_DONE)) 1529 panic("biodone2 already"); 1530 CLR(bp->b_flags, B_COWDONE); 1531 SET(bp->b_oflags, BO_DONE); 1532 BIO_SETPRIO(bp, BPRIO_DEFAULT); 1533 1534 /* Wake up waiting writers. */ 1535 if (!ISSET(bp->b_flags, B_READ)) 1536 vwakeup(bp); 1537 1538 if ((callout = bp->b_iodone) != NULL) { 1539 /* Note callout done, then call out. */ 1540 KASSERT(!cv_has_waiters(&bp->b_done)); 1541 KERNEL_LOCK(1, NULL); /* XXXSMP */ 1542 bp->b_iodone = NULL; 1543 mutex_exit(bp->b_objlock); 1544 (*callout)(bp); 1545 KERNEL_UNLOCK_ONE(NULL); /* XXXSMP */ 1546 } else if (ISSET(bp->b_flags, B_ASYNC)) { 1547 /* If async, release. */ 1548 KASSERT(!cv_has_waiters(&bp->b_done)); 1549 mutex_exit(bp->b_objlock); 1550 brelse(bp, 0); 1551 } else { 1552 /* Otherwise just wake up waiters in biowait(). */ 1553 cv_broadcast(&bp->b_done); 1554 mutex_exit(bp->b_objlock); 1555 } 1556} 1557 1558static void 1559biointr(void *cookie) 1560{ 1561 struct cpu_info *ci; 1562 buf_t *bp; 1563 int s; 1564 1565 ci = curcpu(); 1566 1567 while (!TAILQ_EMPTY(&ci->ci_data.cpu_biodone)) { 1568 KASSERT(curcpu() == ci); 1569 1570 s = splvm(); 1571 bp = TAILQ_FIRST(&ci->ci_data.cpu_biodone); 1572 TAILQ_REMOVE(&ci->ci_data.cpu_biodone, bp, b_actq); 1573 splx(s); 1574 1575 biodone2(bp); 1576 } 1577} 1578 1579/* 1580 * Return a count of buffers on the "locked" queue. 1581 */ 1582int 1583count_lock_queue(void) 1584{ 1585 buf_t *bp; 1586 int n = 0; 1587 1588 mutex_enter(&bufcache_lock); 1589 TAILQ_FOREACH(bp, &bufqueues[BQ_LOCKED].bq_queue, b_freelist) 1590 n++; 1591 mutex_exit(&bufcache_lock); 1592 return (n); 1593} 1594 1595/* 1596 * Wait for all buffers to complete I/O 1597 * Return the number of "stuck" buffers. 1598 */ 1599int 1600buf_syncwait(void) 1601{ 1602 buf_t *bp; 1603 int iter, nbusy, nbusy_prev = 0, dcount, ihash; 1604 1605 dcount = 10000; 1606 for (iter = 0; iter < 20;) { 1607 mutex_enter(&bufcache_lock); 1608 nbusy = 0; 1609 for (ihash = 0; ihash < bufhash+1; ihash++) { 1610 LIST_FOREACH(bp, &bufhashtbl[ihash], b_hash) { 1611 if ((bp->b_cflags & (BC_BUSY|BC_INVAL)) == BC_BUSY) 1612 nbusy += ((bp->b_flags & B_READ) == 0); 1613 } 1614 } 1615 mutex_exit(&bufcache_lock); 1616 1617 if (nbusy == 0) 1618 break; 1619 if (nbusy_prev == 0) 1620 nbusy_prev = nbusy; 1621 printf("%d ", nbusy); 1622 kpause("bflush", false, MAX(1, hz / 25 * iter), NULL); 1623 if (nbusy >= nbusy_prev) /* we didn't flush anything */ 1624 iter++; 1625 else 1626 nbusy_prev = nbusy; 1627 } 1628 1629 if (nbusy) { 1630#if defined(DEBUG) || defined(DEBUG_HALT_BUSY) 1631 printf("giving up\nPrinting vnodes for busy buffers\n"); 1632 for (ihash = 0; ihash < bufhash+1; ihash++) { 1633 LIST_FOREACH(bp, &bufhashtbl[ihash], b_hash) { 1634 if ((bp->b_cflags & (BC_BUSY|BC_INVAL)) == BC_BUSY && 1635 (bp->b_flags & B_READ) == 0) 1636 vprint(NULL, bp->b_vp); 1637 } 1638 } 1639#endif 1640 } 1641 1642 return nbusy; 1643} 1644 1645static void 1646sysctl_fillbuf(buf_t *i, struct buf_sysctl *o) 1647{ 1648 1649 o->b_flags = i->b_flags | i->b_cflags | i->b_oflags; 1650 o->b_error = i->b_error; 1651 o->b_prio = i->b_prio; 1652 o->b_dev = i->b_dev; 1653 o->b_bufsize = i->b_bufsize; 1654 o->b_bcount = i->b_bcount; 1655 o->b_resid = i->b_resid; 1656 o->b_addr = PTRTOUINT64(i->b_data); 1657 o->b_blkno = i->b_blkno; 1658 o->b_rawblkno = i->b_rawblkno; 1659 o->b_iodone = PTRTOUINT64(i->b_iodone); 1660 o->b_proc = PTRTOUINT64(i->b_proc); 1661 o->b_vp = PTRTOUINT64(i->b_vp); 1662 o->b_saveaddr = PTRTOUINT64(i->b_saveaddr); 1663 o->b_lblkno = i->b_lblkno; 1664} 1665 1666#define KERN_BUFSLOP 20 1667static int 1668sysctl_dobuf(SYSCTLFN_ARGS) 1669{ 1670 buf_t *bp; 1671 struct buf_sysctl bs; 1672 struct bqueue *bq; 1673 char *dp; 1674 u_int i, op, arg; 1675 size_t len, needed, elem_size, out_size; 1676 int error, elem_count, retries; 1677 1678 if (namelen == 1 && name[0] == CTL_QUERY) 1679 return (sysctl_query(SYSCTLFN_CALL(rnode))); 1680 1681 if (namelen != 4) 1682 return (EINVAL); 1683 1684 retries = 100; 1685 retry: 1686 dp = oldp; 1687 len = (oldp != NULL) ? *oldlenp : 0; 1688 op = name[0]; 1689 arg = name[1]; 1690 elem_size = name[2]; 1691 elem_count = name[3]; 1692 out_size = MIN(sizeof(bs), elem_size); 1693 1694 /* 1695 * at the moment, these are just "placeholders" to make the 1696 * API for retrieving kern.buf data more extensible in the 1697 * future. 1698 * 1699 * XXX kern.buf currently has "netbsd32" issues. hopefully 1700 * these will be resolved at a later point. 1701 */ 1702 if (op != KERN_BUF_ALL || arg != KERN_BUF_ALL || 1703 elem_size < 1 || elem_count < 0) 1704 return (EINVAL); 1705 1706 error = 0; 1707 needed = 0; 1708 sysctl_unlock(); 1709 mutex_enter(&bufcache_lock); 1710 for (i = 0; i < BQUEUES; i++) { 1711 bq = &bufqueues[i]; 1712 TAILQ_FOREACH(bp, &bq->bq_queue, b_freelist) { 1713 bq->bq_marker = bp; 1714 if (len >= elem_size && elem_count > 0) { 1715 sysctl_fillbuf(bp, &bs); 1716 mutex_exit(&bufcache_lock); 1717 error = copyout(&bs, dp, out_size); 1718 mutex_enter(&bufcache_lock); 1719 if (error) 1720 break; 1721 if (bq->bq_marker != bp) { 1722 /* 1723 * This sysctl node is only for 1724 * statistics. Retry; if the 1725 * queue keeps changing, then 1726 * bail out. 1727 */ 1728 if (retries-- == 0) { 1729 error = EAGAIN; 1730 break; 1731 } 1732 mutex_exit(&bufcache_lock); 1733 goto retry; 1734 } 1735 dp += elem_size; 1736 len -= elem_size; 1737 } 1738 needed += elem_size; 1739 if (elem_count > 0 && elem_count != INT_MAX) 1740 elem_count--; 1741 } 1742 if (error != 0) 1743 break; 1744 } 1745 mutex_exit(&bufcache_lock); 1746 sysctl_relock(); 1747 1748 *oldlenp = needed; 1749 if (oldp == NULL) 1750 *oldlenp += KERN_BUFSLOP * sizeof(buf_t); 1751 1752 return (error); 1753} 1754 1755static int 1756sysctl_bufvm_update(SYSCTLFN_ARGS) 1757{ 1758 int t, error, rv; 1759 struct sysctlnode node; 1760 1761 node = *rnode; 1762 node.sysctl_data = &t; 1763 t = *(int *)rnode->sysctl_data; 1764 error = sysctl_lookup(SYSCTLFN_CALL(&node)); 1765 if (error || newp == NULL) 1766 return (error); 1767 1768 if (t < 0) 1769 return EINVAL; 1770 if (rnode->sysctl_data == &bufcache) { 1771 if (t > 100) 1772 return (EINVAL); 1773 bufcache = t; 1774 buf_setwm(); 1775 } else if (rnode->sysctl_data == &bufmem_lowater) { 1776 if (bufmem_hiwater - t < 16) 1777 return (EINVAL); 1778 bufmem_lowater = t; 1779 } else if (rnode->sysctl_data == &bufmem_hiwater) { 1780 if (t - bufmem_lowater < 16) 1781 return (EINVAL); 1782 bufmem_hiwater = t; 1783 } else 1784 return (EINVAL); 1785 1786 /* Drain until below new high water mark */ 1787 sysctl_unlock(); 1788 mutex_enter(&bufcache_lock); 1789 while ((t = bufmem - bufmem_hiwater) >= 0) { 1790 rv = buf_drain(t / (2 * 1024)); 1791 if (rv <= 0) 1792 break; 1793 } 1794 mutex_exit(&bufcache_lock); 1795 sysctl_relock(); 1796 1797 return 0; 1798} 1799 1800static struct sysctllog *vfsbio_sysctllog; 1801 1802static void 1803sysctl_kern_buf_setup(void) 1804{ 1805 1806 sysctl_createv(&vfsbio_sysctllog, 0, NULL, NULL, 1807 CTLFLAG_PERMANENT, 1808 CTLTYPE_NODE, "kern", NULL, 1809 NULL, 0, NULL, 0, 1810 CTL_KERN, CTL_EOL); 1811 sysctl_createv(&vfsbio_sysctllog, 0, NULL, NULL, 1812 CTLFLAG_PERMANENT, 1813 CTLTYPE_NODE, "buf", 1814 SYSCTL_DESCR("Kernel buffer cache information"), 1815 sysctl_dobuf, 0, NULL, 0, 1816 CTL_KERN, KERN_BUF, CTL_EOL); 1817} 1818 1819static void 1820sysctl_vm_buf_setup(void) 1821{ 1822 1823 sysctl_createv(&vfsbio_sysctllog, 0, NULL, NULL, 1824 CTLFLAG_PERMANENT, 1825 CTLTYPE_NODE, "vm", NULL, 1826 NULL, 0, NULL, 0, 1827 CTL_VM, CTL_EOL); 1828 sysctl_createv(&vfsbio_sysctllog, 0, NULL, NULL, 1829 CTLFLAG_PERMANENT|CTLFLAG_READWRITE, 1830 CTLTYPE_INT, "bufcache", 1831 SYSCTL_DESCR("Percentage of physical memory to use for " 1832 "buffer cache"), 1833 sysctl_bufvm_update, 0, &bufcache, 0, 1834 CTL_VM, CTL_CREATE, CTL_EOL); 1835 sysctl_createv(&vfsbio_sysctllog, 0, NULL, NULL, 1836 CTLFLAG_PERMANENT|CTLFLAG_READONLY, 1837 CTLTYPE_INT, "bufmem", 1838 SYSCTL_DESCR("Amount of kernel memory used by buffer " 1839 "cache"), 1840 NULL, 0, &bufmem, 0, 1841 CTL_VM, CTL_CREATE, CTL_EOL); 1842 sysctl_createv(&vfsbio_sysctllog, 0, NULL, NULL, 1843 CTLFLAG_PERMANENT|CTLFLAG_READWRITE, 1844 CTLTYPE_INT, "bufmem_lowater", 1845 SYSCTL_DESCR("Minimum amount of kernel memory to " 1846 "reserve for buffer cache"), 1847 sysctl_bufvm_update, 0, &bufmem_lowater, 0, 1848 CTL_VM, CTL_CREATE, CTL_EOL); 1849 sysctl_createv(&vfsbio_sysctllog, 0, NULL, NULL, 1850 CTLFLAG_PERMANENT|CTLFLAG_READWRITE, 1851 CTLTYPE_INT, "bufmem_hiwater", 1852 SYSCTL_DESCR("Maximum amount of kernel memory to use " 1853 "for buffer cache"), 1854 sysctl_bufvm_update, 0, &bufmem_hiwater, 0, 1855 CTL_VM, CTL_CREATE, CTL_EOL); 1856} 1857 1858#ifdef DEBUG 1859/* 1860 * Print out statistics on the current allocation of the buffer pool. 1861 * Can be enabled to print out on every ``sync'' by setting "syncprt" 1862 * in vfs_syscalls.c using sysctl. 1863 */ 1864void 1865vfs_bufstats(void) 1866{ 1867 int i, j, count; 1868 buf_t *bp; 1869 struct bqueue *dp; 1870 int counts[(MAXBSIZE / PAGE_SIZE) + 1]; 1871 static const char *bname[BQUEUES] = { "LOCKED", "LRU", "AGE" }; 1872 1873 for (dp = bufqueues, i = 0; dp < &bufqueues[BQUEUES]; dp++, i++) { 1874 count = 0; 1875 for (j = 0; j <= MAXBSIZE/PAGE_SIZE; j++) 1876 counts[j] = 0; 1877 TAILQ_FOREACH(bp, &dp->bq_queue, b_freelist) { 1878 counts[bp->b_bufsize/PAGE_SIZE]++; 1879 count++; 1880 } 1881 printf("%s: total-%d", bname[i], count); 1882 for (j = 0; j <= MAXBSIZE/PAGE_SIZE; j++) 1883 if (counts[j] != 0) 1884 printf(", %d-%d", j * PAGE_SIZE, counts[j]); 1885 printf("\n"); 1886 } 1887} 1888#endif /* DEBUG */ 1889 1890/* ------------------------------ */ 1891 1892buf_t * 1893getiobuf(struct vnode *vp, bool waitok) 1894{ 1895 buf_t *bp; 1896 1897 bp = pool_cache_get(bufio_cache, (waitok ? PR_WAITOK : PR_NOWAIT)); 1898 if (bp == NULL) 1899 return bp; 1900 1901 buf_init(bp); 1902 1903 if ((bp->b_vp = vp) == NULL) 1904 bp->b_objlock = &buffer_lock; 1905 else 1906 bp->b_objlock = &vp->v_interlock; 1907 1908 return bp; 1909} 1910 1911void 1912putiobuf(buf_t *bp) 1913{ 1914 1915 buf_destroy(bp); 1916 pool_cache_put(bufio_cache, bp); 1917} 1918 1919/* 1920 * nestiobuf_iodone: b_iodone callback for nested buffers. 1921 */ 1922 1923void 1924nestiobuf_iodone(buf_t *bp) 1925{ 1926 buf_t *mbp = bp->b_private; 1927 int error; 1928 int donebytes; 1929 1930 KASSERT(bp->b_bcount <= bp->b_bufsize); 1931 KASSERT(mbp != bp); 1932 1933 error = bp->b_error; 1934 if (bp->b_error == 0 && 1935 (bp->b_bcount < bp->b_bufsize || bp->b_resid > 0)) { 1936 /* 1937 * Not all got transfered, raise an error. We have no way to 1938 * propagate these conditions to mbp. 1939 */ 1940 error = EIO; 1941 } 1942 1943 donebytes = bp->b_bufsize; 1944 1945 putiobuf(bp); 1946 nestiobuf_done(mbp, donebytes, error); 1947} 1948 1949/* 1950 * nestiobuf_setup: setup a "nested" buffer. 1951 * 1952 * => 'mbp' is a "master" buffer which is being divided into sub pieces. 1953 * => 'bp' should be a buffer allocated by getiobuf. 1954 * => 'offset' is a byte offset in the master buffer. 1955 * => 'size' is a size in bytes of this nested buffer. 1956 */ 1957 1958void 1959nestiobuf_setup(buf_t *mbp, buf_t *bp, int offset, size_t size) 1960{ 1961 const int b_read = mbp->b_flags & B_READ; 1962 struct vnode *vp = mbp->b_vp; 1963 1964 KASSERT(mbp->b_bcount >= offset + size); 1965 bp->b_vp = vp; 1966 bp->b_dev = mbp->b_dev; 1967 bp->b_objlock = mbp->b_objlock; 1968 bp->b_cflags = BC_BUSY; 1969 bp->b_flags = B_ASYNC | b_read; 1970 bp->b_iodone = nestiobuf_iodone; 1971 bp->b_data = (char *)mbp->b_data + offset; 1972 bp->b_resid = bp->b_bcount = size; 1973 bp->b_bufsize = bp->b_bcount; 1974 bp->b_private = mbp; 1975 BIO_COPYPRIO(bp, mbp); 1976 if (!b_read && vp != NULL) { 1977 mutex_enter(&vp->v_interlock); 1978 vp->v_numoutput++; 1979 mutex_exit(&vp->v_interlock); 1980 } 1981} 1982 1983/* 1984 * nestiobuf_done: propagate completion to the master buffer. 1985 * 1986 * => 'donebytes' specifies how many bytes in the 'mbp' is completed. 1987 * => 'error' is an errno(2) that 'donebytes' has been completed with. 1988 */ 1989 1990void 1991nestiobuf_done(buf_t *mbp, int donebytes, int error) 1992{ 1993 1994 if (donebytes == 0) { 1995 return; 1996 } 1997 mutex_enter(mbp->b_objlock); 1998 KASSERT(mbp->b_resid >= donebytes); 1999 mbp->b_resid -= donebytes; 2000 if (error) 2001 mbp->b_error = error; 2002 if (mbp->b_resid == 0) { 2003 if (mbp->b_error) 2004 mbp->b_resid = mbp->b_bcount; 2005 mutex_exit(mbp->b_objlock); 2006 biodone(mbp); 2007 } else 2008 mutex_exit(mbp->b_objlock); 2009} 2010 2011void 2012buf_init(buf_t *bp) 2013{ 2014 2015 cv_init(&bp->b_busy, "biolock"); 2016 cv_init(&bp->b_done, "biowait"); 2017 bp->b_dev = NODEV; 2018 bp->b_error = 0; 2019 bp->b_flags = 0; 2020 bp->b_cflags = 0; 2021 bp->b_oflags = 0; 2022 bp->b_objlock = &buffer_lock; 2023 bp->b_iodone = NULL; 2024 bp->b_refcnt = 1; 2025 bp->b_dev = NODEV; 2026 bp->b_vnbufs.le_next = NOLIST; 2027 BIO_SETPRIO(bp, BPRIO_DEFAULT); 2028} 2029 2030void 2031buf_destroy(buf_t *bp) 2032{ 2033 2034 cv_destroy(&bp->b_done); 2035 cv_destroy(&bp->b_busy); 2036} 2037 2038int 2039bbusy(buf_t *bp, bool intr, int timo, kmutex_t *interlock) 2040{ 2041 int error; 2042 2043 KASSERT(mutex_owned(&bufcache_lock)); 2044 2045 if ((bp->b_cflags & BC_BUSY) != 0) { 2046 if (curlwp == uvm.pagedaemon_lwp) 2047 return EDEADLK; 2048 bp->b_cflags |= BC_WANTED; 2049 bref(bp); 2050 if (interlock != NULL) 2051 mutex_exit(interlock); 2052 if (intr) { 2053 error = cv_timedwait_sig(&bp->b_busy, &bufcache_lock, 2054 timo); 2055 } else { 2056 error = cv_timedwait(&bp->b_busy, &bufcache_lock, 2057 timo); 2058 } 2059 brele(bp); 2060 if (interlock != NULL) 2061 mutex_enter(interlock); 2062 if (error != 0) 2063 return error; 2064 return EPASSTHROUGH; 2065 } 2066 bp->b_cflags |= BC_BUSY; 2067 2068 return 0; 2069} 2070