1 /* $NetBSD: vfs_bio.c,v 1.250 2014/05/25 16:31:51 pooka 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 1.250 2014/05/25 16:31:51 pooka 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 #include <sys/bitops.h> 146 147 #include <uvm/uvm.h> /* extern struct uvm uvm */ 148 149 #include <miscfs/specfs/specdev.h> 150 151 #ifndef BUFPAGES 152 # define BUFPAGES 0 153 #endif 154 155 #ifdef BUFCACHE 156 # if (BUFCACHE < 5) || (BUFCACHE > 95) 157 # error BUFCACHE is not between 5 and 95 158 # endif 159 #else 160 # define BUFCACHE 15 161 #endif 162 163 u_int nbuf; /* desired number of buffer headers */ 164 u_int bufpages = BUFPAGES; /* optional hardwired count */ 165 u_int bufcache = BUFCACHE; /* max % of RAM to use for buffer cache */ 166 167 /* Function prototypes */ 168 struct bqueue; 169 170 static void buf_setwm(void); 171 static int buf_trim(void); 172 static void *bufpool_page_alloc(struct pool *, int); 173 static void bufpool_page_free(struct pool *, void *); 174 static buf_t *bio_doread(struct vnode *, daddr_t, int, 175 kauth_cred_t, int); 176 static buf_t *getnewbuf(int, int, int); 177 static int buf_lotsfree(void); 178 static int buf_canrelease(void); 179 static u_long buf_mempoolidx(u_long); 180 static u_long buf_roundsize(u_long); 181 static void *buf_alloc(size_t); 182 static void buf_mrelease(void *, size_t); 183 static void binsheadfree(buf_t *, struct bqueue *); 184 static void binstailfree(buf_t *, struct bqueue *); 185 #ifdef DEBUG 186 static int checkfreelist(buf_t *, struct bqueue *, int); 187 #endif 188 static void biointr(void *); 189 static void biodone2(buf_t *); 190 static void bref(buf_t *); 191 static void brele(buf_t *); 192 static void sysctl_kern_buf_setup(void); 193 static 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]) 200 LIST_HEAD(bufhashhdr, buf) *bufhashtbl, invalhash; 201 u_long bufhash; 202 struct bqueue bufqueues[BQUEUES]; 203 204 static kcondvar_t needbuffer_cv; 205 206 /* 207 * Buffer queue lock. 208 */ 209 kmutex_t bufcache_lock; 210 kmutex_t buffer_lock; 211 212 /* Software ISR for completed transfers. */ 213 static void *biodone_sih; 214 215 /* Buffer pool for I/O buffers. */ 216 static pool_cache_t buf_cache; 217 static pool_cache_t bufio_cache; 218 219 #define MEMPOOL_INDEX_OFFSET (ilog2(DEV_BSIZE)) /* smallest pool is 512 bytes */ 220 #define NMEMPOOLS (ilog2(MAXBSIZE) - MEMPOOL_INDEX_OFFSET + 1) 221 __CTASSERT((1 << (NMEMPOOLS + MEMPOOL_INDEX_OFFSET - 1)) == MAXBSIZE); 222 223 /* Buffer memory pools */ 224 static struct pool bmempools[NMEMPOOLS]; 225 226 static struct vm_map *buf_map; 227 228 /* 229 * Buffer memory pool allocator. 230 */ 231 static void * 232 bufpool_page_alloc(struct pool *pp, int flags) 233 { 234 235 return (void *)uvm_km_alloc(buf_map, 236 MAXBSIZE, MAXBSIZE, 237 ((flags & PR_WAITOK) ? 0 : UVM_KMF_NOWAIT|UVM_KMF_TRYLOCK) 238 | UVM_KMF_WIRED); 239 } 240 241 static void 242 bufpool_page_free(struct pool *pp, void *v) 243 { 244 245 uvm_km_free(buf_map, (vaddr_t)v, MAXBSIZE, UVM_KMF_WIRED); 246 } 247 248 static struct pool_allocator bufmempool_allocator = { 249 .pa_alloc = bufpool_page_alloc, 250 .pa_free = bufpool_page_free, 251 .pa_pagesz = MAXBSIZE, 252 }; 253 254 /* Buffer memory management variables */ 255 u_long bufmem_valimit; 256 u_long bufmem_hiwater; 257 u_long bufmem_lowater; 258 u_long bufmem; 259 260 /* 261 * MD code can call this to set a hard limit on the amount 262 * of virtual memory used by the buffer cache. 263 */ 264 int 265 buf_setvalimit(vsize_t sz) 266 { 267 268 /* We need to accommodate at least NMEMPOOLS of MAXBSIZE each */ 269 if (sz < NMEMPOOLS * MAXBSIZE) 270 return EINVAL; 271 272 bufmem_valimit = sz; 273 return 0; 274 } 275 276 static void 277 buf_setwm(void) 278 { 279 280 bufmem_hiwater = buf_memcalc(); 281 /* lowater is approx. 2% of memory (with bufcache = 15) */ 282 #define BUFMEM_WMSHIFT 3 283 #define BUFMEM_HIWMMIN (64 * 1024 << BUFMEM_WMSHIFT) 284 if (bufmem_hiwater < BUFMEM_HIWMMIN) 285 /* Ensure a reasonable minimum value */ 286 bufmem_hiwater = BUFMEM_HIWMMIN; 287 bufmem_lowater = bufmem_hiwater >> BUFMEM_WMSHIFT; 288 } 289 290 #ifdef DEBUG 291 int debug_verify_freelist = 0; 292 static int 293 checkfreelist(buf_t *bp, struct bqueue *dp, int ison) 294 { 295 buf_t *b; 296 297 if (!debug_verify_freelist) 298 return 1; 299 300 TAILQ_FOREACH(b, &dp->bq_queue, b_freelist) { 301 if (b == bp) 302 return ison ? 1 : 0; 303 } 304 305 return ison ? 0 : 1; 306 } 307 #endif 308 309 /* 310 * Insq/Remq for the buffer hash lists. 311 * Call with buffer queue locked. 312 */ 313 static void 314 binsheadfree(buf_t *bp, struct bqueue *dp) 315 { 316 317 KASSERT(mutex_owned(&bufcache_lock)); 318 KASSERT(bp->b_freelistindex == -1); 319 TAILQ_INSERT_HEAD(&dp->bq_queue, bp, b_freelist); 320 dp->bq_bytes += bp->b_bufsize; 321 bp->b_freelistindex = dp - bufqueues; 322 } 323 324 static void 325 binstailfree(buf_t *bp, struct bqueue *dp) 326 { 327 328 KASSERT(mutex_owned(&bufcache_lock)); 329 KASSERT(bp->b_freelistindex == -1); 330 TAILQ_INSERT_TAIL(&dp->bq_queue, bp, b_freelist); 331 dp->bq_bytes += bp->b_bufsize; 332 bp->b_freelistindex = dp - bufqueues; 333 } 334 335 void 336 bremfree(buf_t *bp) 337 { 338 struct bqueue *dp; 339 int bqidx = bp->b_freelistindex; 340 341 KASSERT(mutex_owned(&bufcache_lock)); 342 343 KASSERT(bqidx != -1); 344 dp = &bufqueues[bqidx]; 345 KDASSERT(checkfreelist(bp, dp, 1)); 346 KASSERT(dp->bq_bytes >= bp->b_bufsize); 347 TAILQ_REMOVE(&dp->bq_queue, bp, b_freelist); 348 dp->bq_bytes -= bp->b_bufsize; 349 350 /* For the sysctl helper. */ 351 if (bp == dp->bq_marker) 352 dp->bq_marker = NULL; 353 354 #if defined(DIAGNOSTIC) 355 bp->b_freelistindex = -1; 356 #endif /* defined(DIAGNOSTIC) */ 357 } 358 359 /* 360 * Add a reference to an buffer structure that came from buf_cache. 361 */ 362 static inline void 363 bref(buf_t *bp) 364 { 365 366 KASSERT(mutex_owned(&bufcache_lock)); 367 KASSERT(bp->b_refcnt > 0); 368 369 bp->b_refcnt++; 370 } 371 372 /* 373 * Free an unused buffer structure that came from buf_cache. 374 */ 375 static inline void 376 brele(buf_t *bp) 377 { 378 379 KASSERT(mutex_owned(&bufcache_lock)); 380 KASSERT(bp->b_refcnt > 0); 381 382 if (bp->b_refcnt-- == 1) { 383 buf_destroy(bp); 384 #ifdef DEBUG 385 memset((char *)bp, 0, sizeof(*bp)); 386 #endif 387 pool_cache_put(buf_cache, bp); 388 } 389 } 390 391 /* 392 * note that for some ports this is used by pmap bootstrap code to 393 * determine kva size. 394 */ 395 u_long 396 buf_memcalc(void) 397 { 398 u_long n; 399 vsize_t mapsz = 0; 400 401 /* 402 * Determine the upper bound of memory to use for buffers. 403 * 404 * - If bufpages is specified, use that as the number 405 * pages. 406 * 407 * - Otherwise, use bufcache as the percentage of 408 * physical memory. 409 */ 410 if (bufpages != 0) { 411 n = bufpages; 412 } else { 413 if (bufcache < 5) { 414 printf("forcing bufcache %d -> 5", bufcache); 415 bufcache = 5; 416 } 417 if (bufcache > 95) { 418 printf("forcing bufcache %d -> 95", bufcache); 419 bufcache = 95; 420 } 421 if (buf_map != NULL) 422 mapsz = vm_map_max(buf_map) - vm_map_min(buf_map); 423 n = calc_cache_size(mapsz, bufcache, 424 (buf_map != kernel_map) ? 100 : BUFCACHE_VA_MAXPCT) 425 / PAGE_SIZE; 426 } 427 428 n <<= PAGE_SHIFT; 429 if (bufmem_valimit != 0 && n > bufmem_valimit) 430 n = bufmem_valimit; 431 432 return (n); 433 } 434 435 /* 436 * Initialize buffers and hash links for buffers. 437 */ 438 void 439 bufinit(void) 440 { 441 struct bqueue *dp; 442 int use_std; 443 u_int i; 444 extern void (*biodone_vfs)(buf_t *); 445 446 biodone_vfs = biodone; 447 448 mutex_init(&bufcache_lock, MUTEX_DEFAULT, IPL_NONE); 449 mutex_init(&buffer_lock, MUTEX_DEFAULT, IPL_NONE); 450 cv_init(&needbuffer_cv, "needbuf"); 451 452 if (bufmem_valimit != 0) { 453 vaddr_t minaddr = 0, maxaddr; 454 buf_map = uvm_km_suballoc(kernel_map, &minaddr, &maxaddr, 455 bufmem_valimit, 0, false, 0); 456 if (buf_map == NULL) 457 panic("bufinit: cannot allocate submap"); 458 } else 459 buf_map = kernel_map; 460 461 /* 462 * Initialize buffer cache memory parameters. 463 */ 464 bufmem = 0; 465 buf_setwm(); 466 467 /* On "small" machines use small pool page sizes where possible */ 468 use_std = (physmem < atop(16*1024*1024)); 469 470 /* 471 * Also use them on systems that can map the pool pages using 472 * a direct-mapped segment. 473 */ 474 #ifdef PMAP_MAP_POOLPAGE 475 use_std = 1; 476 #endif 477 478 buf_cache = pool_cache_init(sizeof(buf_t), 0, 0, 0, 479 "bufpl", NULL, IPL_SOFTBIO, NULL, NULL, NULL); 480 bufio_cache = pool_cache_init(sizeof(buf_t), 0, 0, 0, 481 "biopl", NULL, IPL_BIO, NULL, NULL, NULL); 482 483 for (i = 0; i < NMEMPOOLS; i++) { 484 struct pool_allocator *pa; 485 struct pool *pp = &bmempools[i]; 486 u_int size = 1 << (i + MEMPOOL_INDEX_OFFSET); 487 char *name = kmem_alloc(8, KM_SLEEP); /* XXX: never freed */ 488 if (__predict_false(size >= 1048576)) 489 (void)snprintf(name, 8, "buf%um", size / 1048576); 490 else if (__predict_true(size >= 1024)) 491 (void)snprintf(name, 8, "buf%uk", size / 1024); 492 else 493 (void)snprintf(name, 8, "buf%ub", size); 494 pa = (size <= PAGE_SIZE && use_std) 495 ? &pool_allocator_nointr 496 : &bufmempool_allocator; 497 pool_init(pp, size, 0, 0, 0, name, pa, IPL_NONE); 498 pool_setlowat(pp, 1); 499 pool_sethiwat(pp, 1); 500 } 501 502 /* Initialize the buffer queues */ 503 for (dp = bufqueues; dp < &bufqueues[BQUEUES]; dp++) { 504 TAILQ_INIT(&dp->bq_queue); 505 dp->bq_bytes = 0; 506 } 507 508 /* 509 * Estimate hash table size based on the amount of memory we 510 * intend to use for the buffer cache. The average buffer 511 * size is dependent on our clients (i.e. filesystems). 512 * 513 * For now, use an empirical 3K per buffer. 514 */ 515 nbuf = (bufmem_hiwater / 1024) / 3; 516 bufhashtbl = hashinit(nbuf, HASH_LIST, true, &bufhash); 517 518 sysctl_kern_buf_setup(); 519 sysctl_vm_buf_setup(); 520 } 521 522 void 523 bufinit2(void) 524 { 525 526 biodone_sih = softint_establish(SOFTINT_BIO | SOFTINT_MPSAFE, biointr, 527 NULL); 528 if (biodone_sih == NULL) 529 panic("bufinit2: can't establish soft interrupt"); 530 } 531 532 static int 533 buf_lotsfree(void) 534 { 535 int try, thresh; 536 537 /* Always allocate if less than the low water mark. */ 538 if (bufmem < bufmem_lowater) 539 return 1; 540 541 /* Never allocate if greater than the high water mark. */ 542 if (bufmem > bufmem_hiwater) 543 return 0; 544 545 /* If there's anything on the AGE list, it should be eaten. */ 546 if (TAILQ_FIRST(&bufqueues[BQ_AGE].bq_queue) != NULL) 547 return 0; 548 549 /* 550 * The probabily of getting a new allocation is inversely 551 * proportional to the current size of the cache, using 552 * a granularity of 16 steps. 553 */ 554 try = random() & 0x0000000fL; 555 556 /* Don't use "16 * bufmem" here to avoid a 32-bit overflow. */ 557 thresh = (bufmem - bufmem_lowater) / 558 ((bufmem_hiwater - bufmem_lowater) / 16); 559 560 if (try >= thresh) 561 return 1; 562 563 /* Otherwise don't allocate. */ 564 return 0; 565 } 566 567 /* 568 * Return estimate of bytes we think need to be 569 * released to help resolve low memory conditions. 570 * 571 * => called with bufcache_lock held. 572 */ 573 static int 574 buf_canrelease(void) 575 { 576 int pagedemand, ninvalid = 0; 577 578 KASSERT(mutex_owned(&bufcache_lock)); 579 580 if (bufmem < bufmem_lowater) 581 return 0; 582 583 if (bufmem > bufmem_hiwater) 584 return bufmem - bufmem_hiwater; 585 586 ninvalid += bufqueues[BQ_AGE].bq_bytes; 587 588 pagedemand = uvmexp.freetarg - uvmexp.free; 589 if (pagedemand < 0) 590 return ninvalid; 591 return MAX(ninvalid, MIN(2 * MAXBSIZE, 592 MIN((bufmem - bufmem_lowater) / 16, pagedemand * PAGE_SIZE))); 593 } 594 595 /* 596 * Buffer memory allocation helper functions 597 */ 598 static u_long 599 buf_mempoolidx(u_long size) 600 { 601 u_int n = 0; 602 603 size -= 1; 604 size >>= MEMPOOL_INDEX_OFFSET; 605 while (size) { 606 size >>= 1; 607 n += 1; 608 } 609 if (n >= NMEMPOOLS) 610 panic("buf mem pool index %d", n); 611 return n; 612 } 613 614 static u_long 615 buf_roundsize(u_long size) 616 { 617 /* Round up to nearest power of 2 */ 618 return (1 << (buf_mempoolidx(size) + MEMPOOL_INDEX_OFFSET)); 619 } 620 621 static void * 622 buf_alloc(size_t size) 623 { 624 u_int n = buf_mempoolidx(size); 625 void *addr; 626 627 while (1) { 628 addr = pool_get(&bmempools[n], PR_NOWAIT); 629 if (addr != NULL) 630 break; 631 632 /* No memory, see if we can free some. If so, try again */ 633 mutex_enter(&bufcache_lock); 634 if (buf_drain(1) > 0) { 635 mutex_exit(&bufcache_lock); 636 continue; 637 } 638 639 if (curlwp == uvm.pagedaemon_lwp) { 640 mutex_exit(&bufcache_lock); 641 return NULL; 642 } 643 644 /* Wait for buffers to arrive on the LRU queue */ 645 cv_timedwait(&needbuffer_cv, &bufcache_lock, hz / 4); 646 mutex_exit(&bufcache_lock); 647 } 648 649 return addr; 650 } 651 652 static void 653 buf_mrelease(void *addr, size_t size) 654 { 655 656 pool_put(&bmempools[buf_mempoolidx(size)], addr); 657 } 658 659 /* 660 * bread()/breadn() helper. 661 */ 662 static buf_t * 663 bio_doread(struct vnode *vp, daddr_t blkno, int size, kauth_cred_t cred, 664 int async) 665 { 666 buf_t *bp; 667 struct mount *mp; 668 669 bp = getblk(vp, blkno, size, 0, 0); 670 671 /* 672 * getblk() may return NULL if we are the pagedaemon. 673 */ 674 if (bp == NULL) { 675 KASSERT(curlwp == uvm.pagedaemon_lwp); 676 return NULL; 677 } 678 679 /* 680 * If buffer does not have data valid, start a read. 681 * Note that if buffer is BC_INVAL, getblk() won't return it. 682 * Therefore, it's valid if its I/O has completed or been delayed. 683 */ 684 if (!ISSET(bp->b_oflags, (BO_DONE | BO_DELWRI))) { 685 /* Start I/O for the buffer. */ 686 SET(bp->b_flags, B_READ | async); 687 if (async) 688 BIO_SETPRIO(bp, BPRIO_TIMELIMITED); 689 else 690 BIO_SETPRIO(bp, BPRIO_TIMECRITICAL); 691 VOP_STRATEGY(vp, bp); 692 693 /* Pay for the read. */ 694 curlwp->l_ru.ru_inblock++; 695 } else if (async) 696 brelse(bp, 0); 697 698 if (vp->v_type == VBLK) 699 mp = spec_node_getmountedfs(vp); 700 else 701 mp = vp->v_mount; 702 703 /* 704 * Collect statistics on synchronous and asynchronous reads. 705 * Reads from block devices are charged to their associated 706 * filesystem (if any). 707 */ 708 if (mp != NULL) { 709 if (async == 0) 710 mp->mnt_stat.f_syncreads++; 711 else 712 mp->mnt_stat.f_asyncreads++; 713 } 714 715 return (bp); 716 } 717 718 /* 719 * Read a disk block. 720 * This algorithm described in Bach (p.54). 721 */ 722 int 723 bread(struct vnode *vp, daddr_t blkno, int size, kauth_cred_t cred, 724 int flags, buf_t **bpp) 725 { 726 buf_t *bp; 727 int error; 728 729 /* Get buffer for block. */ 730 bp = *bpp = bio_doread(vp, blkno, size, cred, 0); 731 if (bp == NULL) 732 return ENOMEM; 733 734 /* Wait for the read to complete, and return result. */ 735 error = biowait(bp); 736 if (error == 0 && (flags & B_MODIFY) != 0) 737 error = fscow_run(bp, true); 738 if (error) { 739 brelse(bp, 0); 740 *bpp = NULL; 741 } 742 743 return error; 744 } 745 746 /* 747 * Read-ahead multiple disk blocks. The first is sync, the rest async. 748 * Trivial modification to the breada algorithm presented in Bach (p.55). 749 */ 750 int 751 breadn(struct vnode *vp, daddr_t blkno, int size, daddr_t *rablks, 752 int *rasizes, int nrablks, kauth_cred_t cred, int flags, buf_t **bpp) 753 { 754 buf_t *bp; 755 int error, i; 756 757 bp = *bpp = bio_doread(vp, blkno, size, cred, 0); 758 if (bp == NULL) 759 return ENOMEM; 760 761 /* 762 * For each of the read-ahead blocks, start a read, if necessary. 763 */ 764 mutex_enter(&bufcache_lock); 765 for (i = 0; i < nrablks; i++) { 766 /* If it's in the cache, just go on to next one. */ 767 if (incore(vp, rablks[i])) 768 continue; 769 770 /* Get a buffer for the read-ahead block */ 771 mutex_exit(&bufcache_lock); 772 (void) bio_doread(vp, rablks[i], rasizes[i], cred, B_ASYNC); 773 mutex_enter(&bufcache_lock); 774 } 775 mutex_exit(&bufcache_lock); 776 777 /* Otherwise, we had to start a read for it; wait until it's valid. */ 778 error = biowait(bp); 779 if (error == 0 && (flags & B_MODIFY) != 0) 780 error = fscow_run(bp, true); 781 if (error) { 782 brelse(bp, 0); 783 *bpp = NULL; 784 } 785 786 return error; 787 } 788 789 /* 790 * Block write. Described in Bach (p.56) 791 */ 792 int 793 bwrite(buf_t *bp) 794 { 795 int rv, sync, wasdelayed; 796 struct vnode *vp; 797 struct mount *mp; 798 799 KASSERT(ISSET(bp->b_cflags, BC_BUSY)); 800 KASSERT(!cv_has_waiters(&bp->b_done)); 801 802 vp = bp->b_vp; 803 if (vp != NULL) { 804 KASSERT(bp->b_objlock == vp->v_interlock); 805 if (vp->v_type == VBLK) 806 mp = spec_node_getmountedfs(vp); 807 else 808 mp = vp->v_mount; 809 } else { 810 mp = NULL; 811 } 812 813 if (mp && mp->mnt_wapbl) { 814 if (bp->b_iodone != mp->mnt_wapbl_op->wo_wapbl_biodone) { 815 bdwrite(bp); 816 return 0; 817 } 818 } 819 820 /* 821 * Remember buffer type, to switch on it later. If the write was 822 * synchronous, but the file system was mounted with MNT_ASYNC, 823 * convert it to a delayed write. 824 * XXX note that this relies on delayed tape writes being converted 825 * to async, not sync writes (which is safe, but ugly). 826 */ 827 sync = !ISSET(bp->b_flags, B_ASYNC); 828 if (sync && mp != NULL && ISSET(mp->mnt_flag, MNT_ASYNC)) { 829 bdwrite(bp); 830 return (0); 831 } 832 833 /* 834 * Collect statistics on synchronous and asynchronous writes. 835 * Writes to block devices are charged to their associated 836 * filesystem (if any). 837 */ 838 if (mp != NULL) { 839 if (sync) 840 mp->mnt_stat.f_syncwrites++; 841 else 842 mp->mnt_stat.f_asyncwrites++; 843 } 844 845 /* 846 * Pay for the I/O operation and make sure the buf is on the correct 847 * vnode queue. 848 */ 849 bp->b_error = 0; 850 wasdelayed = ISSET(bp->b_oflags, BO_DELWRI); 851 CLR(bp->b_flags, B_READ); 852 if (wasdelayed) { 853 mutex_enter(&bufcache_lock); 854 mutex_enter(bp->b_objlock); 855 CLR(bp->b_oflags, BO_DONE | BO_DELWRI); 856 reassignbuf(bp, bp->b_vp); 857 mutex_exit(&bufcache_lock); 858 } else { 859 curlwp->l_ru.ru_oublock++; 860 mutex_enter(bp->b_objlock); 861 CLR(bp->b_oflags, BO_DONE | BO_DELWRI); 862 } 863 if (vp != NULL) 864 vp->v_numoutput++; 865 mutex_exit(bp->b_objlock); 866 867 /* Initiate disk write. */ 868 if (sync) 869 BIO_SETPRIO(bp, BPRIO_TIMECRITICAL); 870 else 871 BIO_SETPRIO(bp, BPRIO_TIMELIMITED); 872 873 VOP_STRATEGY(vp, bp); 874 875 if (sync) { 876 /* If I/O was synchronous, wait for it to complete. */ 877 rv = biowait(bp); 878 879 /* Release the buffer. */ 880 brelse(bp, 0); 881 882 return (rv); 883 } else { 884 return (0); 885 } 886 } 887 888 int 889 vn_bwrite(void *v) 890 { 891 struct vop_bwrite_args *ap = v; 892 893 return (bwrite(ap->a_bp)); 894 } 895 896 /* 897 * Delayed write. 898 * 899 * The buffer is marked dirty, but is not queued for I/O. 900 * This routine should be used when the buffer is expected 901 * to be modified again soon, typically a small write that 902 * partially fills a buffer. 903 * 904 * NB: magnetic tapes cannot be delayed; they must be 905 * written in the order that the writes are requested. 906 * 907 * Described in Leffler, et al. (pp. 208-213). 908 */ 909 void 910 bdwrite(buf_t *bp) 911 { 912 913 KASSERT(bp->b_vp == NULL || bp->b_vp->v_tag != VT_UFS || 914 bp->b_vp->v_type == VBLK || ISSET(bp->b_flags, B_COWDONE)); 915 KASSERT(ISSET(bp->b_cflags, BC_BUSY)); 916 KASSERT(!cv_has_waiters(&bp->b_done)); 917 918 /* If this is a tape block, write the block now. */ 919 if (bdev_type(bp->b_dev) == D_TAPE) { 920 bawrite(bp); 921 return; 922 } 923 924 if (wapbl_vphaswapbl(bp->b_vp)) { 925 struct mount *mp = wapbl_vptomp(bp->b_vp); 926 927 if (bp->b_iodone != mp->mnt_wapbl_op->wo_wapbl_biodone) { 928 WAPBL_ADD_BUF(mp, bp); 929 } 930 } 931 932 /* 933 * If the block hasn't been seen before: 934 * (1) Mark it as having been seen, 935 * (2) Charge for the write, 936 * (3) Make sure it's on its vnode's correct block list. 937 */ 938 KASSERT(bp->b_vp == NULL || bp->b_objlock == bp->b_vp->v_interlock); 939 940 if (!ISSET(bp->b_oflags, BO_DELWRI)) { 941 mutex_enter(&bufcache_lock); 942 mutex_enter(bp->b_objlock); 943 SET(bp->b_oflags, BO_DELWRI); 944 curlwp->l_ru.ru_oublock++; 945 reassignbuf(bp, bp->b_vp); 946 mutex_exit(&bufcache_lock); 947 } else { 948 mutex_enter(bp->b_objlock); 949 } 950 /* Otherwise, the "write" is done, so mark and release the buffer. */ 951 CLR(bp->b_oflags, BO_DONE); 952 mutex_exit(bp->b_objlock); 953 954 brelse(bp, 0); 955 } 956 957 /* 958 * Asynchronous block write; just an asynchronous bwrite(). 959 */ 960 void 961 bawrite(buf_t *bp) 962 { 963 964 KASSERT(ISSET(bp->b_cflags, BC_BUSY)); 965 KASSERT(bp->b_vp != NULL); 966 967 SET(bp->b_flags, B_ASYNC); 968 VOP_BWRITE(bp->b_vp, bp); 969 } 970 971 /* 972 * Release a buffer on to the free lists. 973 * Described in Bach (p. 46). 974 */ 975 void 976 brelsel(buf_t *bp, int set) 977 { 978 struct bqueue *bufq; 979 struct vnode *vp; 980 981 KASSERT(bp != NULL); 982 KASSERT(mutex_owned(&bufcache_lock)); 983 KASSERT(!cv_has_waiters(&bp->b_done)); 984 KASSERT(bp->b_refcnt > 0); 985 986 SET(bp->b_cflags, set); 987 988 KASSERT(ISSET(bp->b_cflags, BC_BUSY)); 989 KASSERT(bp->b_iodone == NULL); 990 991 /* Wake up any processes waiting for any buffer to become free. */ 992 cv_signal(&needbuffer_cv); 993 994 /* Wake up any proceeses waiting for _this_ buffer to become */ 995 if (ISSET(bp->b_cflags, BC_WANTED)) 996 CLR(bp->b_cflags, BC_WANTED|BC_AGE); 997 998 /* If it's clean clear the copy-on-write flag. */ 999 if (ISSET(bp->b_flags, B_COWDONE)) { 1000 mutex_enter(bp->b_objlock); 1001 if (!ISSET(bp->b_oflags, BO_DELWRI)) 1002 CLR(bp->b_flags, B_COWDONE); 1003 mutex_exit(bp->b_objlock); 1004 } 1005 1006 /* 1007 * Determine which queue the buffer should be on, then put it there. 1008 */ 1009 1010 /* If it's locked, don't report an error; try again later. */ 1011 if (ISSET(bp->b_flags, B_LOCKED)) 1012 bp->b_error = 0; 1013 1014 /* If it's not cacheable, or an error, mark it invalid. */ 1015 if (ISSET(bp->b_cflags, BC_NOCACHE) || bp->b_error != 0) 1016 SET(bp->b_cflags, BC_INVAL); 1017 1018 if (ISSET(bp->b_cflags, BC_VFLUSH)) { 1019 /* 1020 * This is a delayed write buffer that was just flushed to 1021 * disk. It is still on the LRU queue. If it's become 1022 * invalid, then we need to move it to a different queue; 1023 * otherwise leave it in its current position. 1024 */ 1025 CLR(bp->b_cflags, BC_VFLUSH); 1026 if (!ISSET(bp->b_cflags, BC_INVAL|BC_AGE) && 1027 !ISSET(bp->b_flags, B_LOCKED) && bp->b_error == 0) { 1028 KDASSERT(checkfreelist(bp, &bufqueues[BQ_LRU], 1)); 1029 goto already_queued; 1030 } else { 1031 bremfree(bp); 1032 } 1033 } 1034 1035 KDASSERT(checkfreelist(bp, &bufqueues[BQ_AGE], 0)); 1036 KDASSERT(checkfreelist(bp, &bufqueues[BQ_LRU], 0)); 1037 KDASSERT(checkfreelist(bp, &bufqueues[BQ_LOCKED], 0)); 1038 1039 if ((bp->b_bufsize <= 0) || ISSET(bp->b_cflags, BC_INVAL)) { 1040 /* 1041 * If it's invalid or empty, dissociate it from its vnode 1042 * and put on the head of the appropriate queue. 1043 */ 1044 if (ISSET(bp->b_flags, B_LOCKED)) { 1045 if (wapbl_vphaswapbl(vp = bp->b_vp)) { 1046 struct mount *mp = wapbl_vptomp(vp); 1047 1048 KASSERT(bp->b_iodone 1049 != mp->mnt_wapbl_op->wo_wapbl_biodone); 1050 WAPBL_REMOVE_BUF(mp, bp); 1051 } 1052 } 1053 1054 mutex_enter(bp->b_objlock); 1055 CLR(bp->b_oflags, BO_DONE|BO_DELWRI); 1056 if ((vp = bp->b_vp) != NULL) { 1057 KASSERT(bp->b_objlock == vp->v_interlock); 1058 reassignbuf(bp, bp->b_vp); 1059 brelvp(bp); 1060 mutex_exit(vp->v_interlock); 1061 } else { 1062 KASSERT(bp->b_objlock == &buffer_lock); 1063 mutex_exit(bp->b_objlock); 1064 } 1065 1066 if (bp->b_bufsize <= 0) 1067 /* no data */ 1068 goto already_queued; 1069 else 1070 /* invalid data */ 1071 bufq = &bufqueues[BQ_AGE]; 1072 binsheadfree(bp, bufq); 1073 } else { 1074 /* 1075 * It has valid data. Put it on the end of the appropriate 1076 * queue, so that it'll stick around for as long as possible. 1077 * If buf is AGE, but has dependencies, must put it on last 1078 * bufqueue to be scanned, ie LRU. This protects against the 1079 * livelock where BQ_AGE only has buffers with dependencies, 1080 * and we thus never get to the dependent buffers in BQ_LRU. 1081 */ 1082 if (ISSET(bp->b_flags, B_LOCKED)) { 1083 /* locked in core */ 1084 bufq = &bufqueues[BQ_LOCKED]; 1085 } else if (!ISSET(bp->b_cflags, BC_AGE)) { 1086 /* valid data */ 1087 bufq = &bufqueues[BQ_LRU]; 1088 } else { 1089 /* stale but valid data */ 1090 bufq = &bufqueues[BQ_AGE]; 1091 } 1092 binstailfree(bp, bufq); 1093 } 1094 already_queued: 1095 /* Unlock the buffer. */ 1096 CLR(bp->b_cflags, BC_AGE|BC_BUSY|BC_NOCACHE); 1097 CLR(bp->b_flags, B_ASYNC); 1098 cv_broadcast(&bp->b_busy); 1099 1100 if (bp->b_bufsize <= 0) 1101 brele(bp); 1102 } 1103 1104 void 1105 brelse(buf_t *bp, int set) 1106 { 1107 1108 mutex_enter(&bufcache_lock); 1109 brelsel(bp, set); 1110 mutex_exit(&bufcache_lock); 1111 } 1112 1113 /* 1114 * Determine if a block is in the cache. 1115 * Just look on what would be its hash chain. If it's there, return 1116 * a pointer to it, unless it's marked invalid. If it's marked invalid, 1117 * we normally don't return the buffer, unless the caller explicitly 1118 * wants us to. 1119 */ 1120 buf_t * 1121 incore(struct vnode *vp, daddr_t blkno) 1122 { 1123 buf_t *bp; 1124 1125 KASSERT(mutex_owned(&bufcache_lock)); 1126 1127 /* Search hash chain */ 1128 LIST_FOREACH(bp, BUFHASH(vp, blkno), b_hash) { 1129 if (bp->b_lblkno == blkno && bp->b_vp == vp && 1130 !ISSET(bp->b_cflags, BC_INVAL)) { 1131 KASSERT(bp->b_objlock == vp->v_interlock); 1132 return (bp); 1133 } 1134 } 1135 1136 return (NULL); 1137 } 1138 1139 /* 1140 * Get a block of requested size that is associated with 1141 * a given vnode and block offset. If it is found in the 1142 * block cache, mark it as having been found, make it busy 1143 * and return it. Otherwise, return an empty block of the 1144 * correct size. It is up to the caller to insure that the 1145 * cached blocks be of the correct size. 1146 */ 1147 buf_t * 1148 getblk(struct vnode *vp, daddr_t blkno, int size, int slpflag, int slptimeo) 1149 { 1150 int err, preserve; 1151 buf_t *bp; 1152 1153 mutex_enter(&bufcache_lock); 1154 loop: 1155 bp = incore(vp, blkno); 1156 if (bp != NULL) { 1157 err = bbusy(bp, ((slpflag & PCATCH) != 0), slptimeo, NULL); 1158 if (err != 0) { 1159 if (err == EPASSTHROUGH) 1160 goto loop; 1161 mutex_exit(&bufcache_lock); 1162 return (NULL); 1163 } 1164 KASSERT(!cv_has_waiters(&bp->b_done)); 1165 #ifdef DIAGNOSTIC 1166 if (ISSET(bp->b_oflags, BO_DONE|BO_DELWRI) && 1167 bp->b_bcount < size && vp->v_type != VBLK) 1168 panic("getblk: block size invariant failed"); 1169 #endif 1170 bremfree(bp); 1171 preserve = 1; 1172 } else { 1173 if ((bp = getnewbuf(slpflag, slptimeo, 0)) == NULL) 1174 goto loop; 1175 1176 if (incore(vp, blkno) != NULL) { 1177 /* The block has come into memory in the meantime. */ 1178 brelsel(bp, 0); 1179 goto loop; 1180 } 1181 1182 LIST_INSERT_HEAD(BUFHASH(vp, blkno), bp, b_hash); 1183 bp->b_blkno = bp->b_lblkno = bp->b_rawblkno = blkno; 1184 mutex_enter(vp->v_interlock); 1185 bgetvp(vp, bp); 1186 mutex_exit(vp->v_interlock); 1187 preserve = 0; 1188 } 1189 mutex_exit(&bufcache_lock); 1190 1191 /* 1192 * LFS can't track total size of B_LOCKED buffer (locked_queue_bytes) 1193 * if we re-size buffers here. 1194 */ 1195 if (ISSET(bp->b_flags, B_LOCKED)) { 1196 KASSERT(bp->b_bufsize >= size); 1197 } else { 1198 if (allocbuf(bp, size, preserve)) { 1199 mutex_enter(&bufcache_lock); 1200 LIST_REMOVE(bp, b_hash); 1201 mutex_exit(&bufcache_lock); 1202 brelse(bp, BC_INVAL); 1203 return NULL; 1204 } 1205 } 1206 BIO_SETPRIO(bp, BPRIO_DEFAULT); 1207 return (bp); 1208 } 1209 1210 /* 1211 * Get an empty, disassociated buffer of given size. 1212 */ 1213 buf_t * 1214 geteblk(int size) 1215 { 1216 buf_t *bp; 1217 int error __diagused; 1218 1219 mutex_enter(&bufcache_lock); 1220 while ((bp = getnewbuf(0, 0, 0)) == NULL) 1221 ; 1222 1223 SET(bp->b_cflags, BC_INVAL); 1224 LIST_INSERT_HEAD(&invalhash, bp, b_hash); 1225 mutex_exit(&bufcache_lock); 1226 BIO_SETPRIO(bp, BPRIO_DEFAULT); 1227 error = allocbuf(bp, size, 0); 1228 KASSERT(error == 0); 1229 return (bp); 1230 } 1231 1232 /* 1233 * Expand or contract the actual memory allocated to a buffer. 1234 * 1235 * If the buffer shrinks, data is lost, so it's up to the 1236 * caller to have written it out *first*; this routine will not 1237 * start a write. If the buffer grows, it's the callers 1238 * responsibility to fill out the buffer's additional contents. 1239 */ 1240 int 1241 allocbuf(buf_t *bp, int size, int preserve) 1242 { 1243 void *addr; 1244 vsize_t oldsize, desired_size; 1245 int oldcount; 1246 int delta; 1247 1248 desired_size = buf_roundsize(size); 1249 if (desired_size > MAXBSIZE) 1250 printf("allocbuf: buffer larger than MAXBSIZE requested"); 1251 1252 oldcount = bp->b_bcount; 1253 1254 bp->b_bcount = size; 1255 1256 oldsize = bp->b_bufsize; 1257 if (oldsize == desired_size) { 1258 /* 1259 * Do not short cut the WAPBL resize, as the buffer length 1260 * could still have changed and this would corrupt the 1261 * tracking of the transaction length. 1262 */ 1263 goto out; 1264 } 1265 1266 /* 1267 * If we want a buffer of a different size, re-allocate the 1268 * buffer's memory; copy old content only if needed. 1269 */ 1270 addr = buf_alloc(desired_size); 1271 if (addr == NULL) 1272 return ENOMEM; 1273 if (preserve) 1274 memcpy(addr, bp->b_data, MIN(oldsize,desired_size)); 1275 if (bp->b_data != NULL) 1276 buf_mrelease(bp->b_data, oldsize); 1277 bp->b_data = addr; 1278 bp->b_bufsize = desired_size; 1279 1280 /* 1281 * Update overall buffer memory counter (protected by bufcache_lock) 1282 */ 1283 delta = (long)desired_size - (long)oldsize; 1284 1285 mutex_enter(&bufcache_lock); 1286 if ((bufmem += delta) > bufmem_hiwater) { 1287 /* 1288 * Need to trim overall memory usage. 1289 */ 1290 while (buf_canrelease()) { 1291 if (curcpu()->ci_schedstate.spc_flags & 1292 SPCF_SHOULDYIELD) { 1293 mutex_exit(&bufcache_lock); 1294 preempt(); 1295 mutex_enter(&bufcache_lock); 1296 } 1297 if (buf_trim() == 0) 1298 break; 1299 } 1300 } 1301 mutex_exit(&bufcache_lock); 1302 1303 out: 1304 if (wapbl_vphaswapbl(bp->b_vp)) 1305 WAPBL_RESIZE_BUF(wapbl_vptomp(bp->b_vp), bp, oldsize, oldcount); 1306 1307 return 0; 1308 } 1309 1310 /* 1311 * Find a buffer which is available for use. 1312 * Select something from a free list. 1313 * Preference is to AGE list, then LRU list. 1314 * 1315 * Called with the buffer queues locked. 1316 * Return buffer locked. 1317 */ 1318 buf_t * 1319 getnewbuf(int slpflag, int slptimeo, int from_bufq) 1320 { 1321 buf_t *bp; 1322 struct vnode *vp; 1323 1324 start: 1325 KASSERT(mutex_owned(&bufcache_lock)); 1326 1327 /* 1328 * Get a new buffer from the pool. 1329 */ 1330 if (!from_bufq && buf_lotsfree()) { 1331 mutex_exit(&bufcache_lock); 1332 bp = pool_cache_get(buf_cache, PR_NOWAIT); 1333 if (bp != NULL) { 1334 memset((char *)bp, 0, sizeof(*bp)); 1335 buf_init(bp); 1336 SET(bp->b_cflags, BC_BUSY); /* mark buffer busy */ 1337 mutex_enter(&bufcache_lock); 1338 #if defined(DIAGNOSTIC) 1339 bp->b_freelistindex = -1; 1340 #endif /* defined(DIAGNOSTIC) */ 1341 return (bp); 1342 } 1343 mutex_enter(&bufcache_lock); 1344 } 1345 1346 KASSERT(mutex_owned(&bufcache_lock)); 1347 if ((bp = TAILQ_FIRST(&bufqueues[BQ_AGE].bq_queue)) != NULL || 1348 (bp = TAILQ_FIRST(&bufqueues[BQ_LRU].bq_queue)) != NULL) { 1349 KASSERT(!ISSET(bp->b_cflags, BC_BUSY) || ISSET(bp->b_cflags, BC_VFLUSH)); 1350 bremfree(bp); 1351 1352 /* Buffer is no longer on free lists. */ 1353 SET(bp->b_cflags, BC_BUSY); 1354 } else { 1355 /* 1356 * XXX: !from_bufq should be removed. 1357 */ 1358 if (!from_bufq || curlwp != uvm.pagedaemon_lwp) { 1359 /* wait for a free buffer of any kind */ 1360 if ((slpflag & PCATCH) != 0) 1361 (void)cv_timedwait_sig(&needbuffer_cv, 1362 &bufcache_lock, slptimeo); 1363 else 1364 (void)cv_timedwait(&needbuffer_cv, 1365 &bufcache_lock, slptimeo); 1366 } 1367 return (NULL); 1368 } 1369 1370 #ifdef DIAGNOSTIC 1371 if (bp->b_bufsize <= 0) 1372 panic("buffer %p: on queue but empty", bp); 1373 #endif 1374 1375 if (ISSET(bp->b_cflags, BC_VFLUSH)) { 1376 /* 1377 * This is a delayed write buffer being flushed to disk. Make 1378 * sure it gets aged out of the queue when it's finished, and 1379 * leave it off the LRU queue. 1380 */ 1381 CLR(bp->b_cflags, BC_VFLUSH); 1382 SET(bp->b_cflags, BC_AGE); 1383 goto start; 1384 } 1385 1386 KASSERT(ISSET(bp->b_cflags, BC_BUSY)); 1387 KASSERT(bp->b_refcnt > 0); 1388 KASSERT(!cv_has_waiters(&bp->b_done)); 1389 1390 /* 1391 * If buffer was a delayed write, start it and return NULL 1392 * (since we might sleep while starting the write). 1393 */ 1394 if (ISSET(bp->b_oflags, BO_DELWRI)) { 1395 /* 1396 * This buffer has gone through the LRU, so make sure it gets 1397 * reused ASAP. 1398 */ 1399 SET(bp->b_cflags, BC_AGE); 1400 mutex_exit(&bufcache_lock); 1401 bawrite(bp); 1402 mutex_enter(&bufcache_lock); 1403 return (NULL); 1404 } 1405 1406 vp = bp->b_vp; 1407 1408 /* clear out various other fields */ 1409 bp->b_cflags = BC_BUSY; 1410 bp->b_oflags = 0; 1411 bp->b_flags = 0; 1412 bp->b_dev = NODEV; 1413 bp->b_blkno = 0; 1414 bp->b_lblkno = 0; 1415 bp->b_rawblkno = 0; 1416 bp->b_iodone = 0; 1417 bp->b_error = 0; 1418 bp->b_resid = 0; 1419 bp->b_bcount = 0; 1420 1421 LIST_REMOVE(bp, b_hash); 1422 1423 /* Disassociate us from our vnode, if we had one... */ 1424 if (vp != NULL) { 1425 mutex_enter(vp->v_interlock); 1426 brelvp(bp); 1427 mutex_exit(vp->v_interlock); 1428 } 1429 1430 return (bp); 1431 } 1432 1433 /* 1434 * Attempt to free an aged buffer off the queues. 1435 * Called with queue lock held. 1436 * Returns the amount of buffer memory freed. 1437 */ 1438 static int 1439 buf_trim(void) 1440 { 1441 buf_t *bp; 1442 long size; 1443 1444 KASSERT(mutex_owned(&bufcache_lock)); 1445 1446 /* Instruct getnewbuf() to get buffers off the queues */ 1447 if ((bp = getnewbuf(PCATCH, 1, 1)) == NULL) 1448 return 0; 1449 1450 KASSERT((bp->b_cflags & BC_WANTED) == 0); 1451 size = bp->b_bufsize; 1452 bufmem -= size; 1453 if (size > 0) { 1454 buf_mrelease(bp->b_data, size); 1455 bp->b_bcount = bp->b_bufsize = 0; 1456 } 1457 /* brelse() will return the buffer to the global buffer pool */ 1458 brelsel(bp, 0); 1459 return size; 1460 } 1461 1462 int 1463 buf_drain(int n) 1464 { 1465 int size = 0, sz; 1466 1467 KASSERT(mutex_owned(&bufcache_lock)); 1468 1469 while (size < n && bufmem > bufmem_lowater) { 1470 sz = buf_trim(); 1471 if (sz <= 0) 1472 break; 1473 size += sz; 1474 } 1475 1476 return size; 1477 } 1478 1479 /* 1480 * Wait for operations on the buffer to complete. 1481 * When they do, extract and return the I/O's error value. 1482 */ 1483 int 1484 biowait(buf_t *bp) 1485 { 1486 1487 KASSERT(ISSET(bp->b_cflags, BC_BUSY)); 1488 KASSERT(bp->b_refcnt > 0); 1489 1490 mutex_enter(bp->b_objlock); 1491 while (!ISSET(bp->b_oflags, BO_DONE | BO_DELWRI)) 1492 cv_wait(&bp->b_done, bp->b_objlock); 1493 mutex_exit(bp->b_objlock); 1494 1495 return bp->b_error; 1496 } 1497 1498 /* 1499 * Mark I/O complete on a buffer. 1500 * 1501 * If a callback has been requested, e.g. the pageout 1502 * daemon, do so. Otherwise, awaken waiting processes. 1503 * 1504 * [ Leffler, et al., says on p.247: 1505 * "This routine wakes up the blocked process, frees the buffer 1506 * for an asynchronous write, or, for a request by the pagedaemon 1507 * process, invokes a procedure specified in the buffer structure" ] 1508 * 1509 * In real life, the pagedaemon (or other system processes) wants 1510 * to do async stuff to, and doesn't want the buffer brelse()'d. 1511 * (for swap pager, that puts swap buffers on the free lists (!!!), 1512 * for the vn device, that puts allocated buffers on the free lists!) 1513 */ 1514 void 1515 biodone(buf_t *bp) 1516 { 1517 int s; 1518 1519 KASSERT(!ISSET(bp->b_oflags, BO_DONE)); 1520 1521 if (cpu_intr_p()) { 1522 /* From interrupt mode: defer to a soft interrupt. */ 1523 s = splvm(); 1524 TAILQ_INSERT_TAIL(&curcpu()->ci_data.cpu_biodone, bp, b_actq); 1525 softint_schedule(biodone_sih); 1526 splx(s); 1527 } else { 1528 /* Process now - the buffer may be freed soon. */ 1529 biodone2(bp); 1530 } 1531 } 1532 1533 static void 1534 biodone2(buf_t *bp) 1535 { 1536 void (*callout)(buf_t *); 1537 1538 mutex_enter(bp->b_objlock); 1539 /* Note that the transfer is done. */ 1540 if (ISSET(bp->b_oflags, BO_DONE)) 1541 panic("biodone2 already"); 1542 CLR(bp->b_flags, B_COWDONE); 1543 SET(bp->b_oflags, BO_DONE); 1544 BIO_SETPRIO(bp, BPRIO_DEFAULT); 1545 1546 /* Wake up waiting writers. */ 1547 if (!ISSET(bp->b_flags, B_READ)) 1548 vwakeup(bp); 1549 1550 if ((callout = bp->b_iodone) != NULL) { 1551 /* Note callout done, then call out. */ 1552 KASSERT(!cv_has_waiters(&bp->b_done)); 1553 KERNEL_LOCK(1, NULL); /* XXXSMP */ 1554 bp->b_iodone = NULL; 1555 mutex_exit(bp->b_objlock); 1556 (*callout)(bp); 1557 KERNEL_UNLOCK_ONE(NULL); /* XXXSMP */ 1558 } else if (ISSET(bp->b_flags, B_ASYNC)) { 1559 /* If async, release. */ 1560 KASSERT(!cv_has_waiters(&bp->b_done)); 1561 mutex_exit(bp->b_objlock); 1562 brelse(bp, 0); 1563 } else { 1564 /* Otherwise just wake up waiters in biowait(). */ 1565 cv_broadcast(&bp->b_done); 1566 mutex_exit(bp->b_objlock); 1567 } 1568 } 1569 1570 static void 1571 biointr(void *cookie) 1572 { 1573 struct cpu_info *ci; 1574 buf_t *bp; 1575 int s; 1576 1577 ci = curcpu(); 1578 1579 while (!TAILQ_EMPTY(&ci->ci_data.cpu_biodone)) { 1580 KASSERT(curcpu() == ci); 1581 1582 s = splvm(); 1583 bp = TAILQ_FIRST(&ci->ci_data.cpu_biodone); 1584 TAILQ_REMOVE(&ci->ci_data.cpu_biodone, bp, b_actq); 1585 splx(s); 1586 1587 biodone2(bp); 1588 } 1589 } 1590 1591 /* 1592 * Wait for all buffers to complete I/O 1593 * Return the number of "stuck" buffers. 1594 */ 1595 int 1596 buf_syncwait(void) 1597 { 1598 buf_t *bp; 1599 int iter, nbusy, nbusy_prev = 0, ihash; 1600 1601 for (iter = 0; iter < 20;) { 1602 mutex_enter(&bufcache_lock); 1603 nbusy = 0; 1604 for (ihash = 0; ihash < bufhash+1; ihash++) { 1605 LIST_FOREACH(bp, &bufhashtbl[ihash], b_hash) { 1606 if ((bp->b_cflags & (BC_BUSY|BC_INVAL)) == BC_BUSY) 1607 nbusy += ((bp->b_flags & B_READ) == 0); 1608 } 1609 } 1610 mutex_exit(&bufcache_lock); 1611 1612 if (nbusy == 0) 1613 break; 1614 if (nbusy_prev == 0) 1615 nbusy_prev = nbusy; 1616 printf("%d ", nbusy); 1617 kpause("bflush", false, MAX(1, hz / 25 * iter), NULL); 1618 if (nbusy >= nbusy_prev) /* we didn't flush anything */ 1619 iter++; 1620 else 1621 nbusy_prev = nbusy; 1622 } 1623 1624 if (nbusy) { 1625 #if defined(DEBUG) || defined(DEBUG_HALT_BUSY) 1626 printf("giving up\nPrinting vnodes for busy buffers\n"); 1627 for (ihash = 0; ihash < bufhash+1; ihash++) { 1628 LIST_FOREACH(bp, &bufhashtbl[ihash], b_hash) { 1629 if ((bp->b_cflags & (BC_BUSY|BC_INVAL)) == BC_BUSY && 1630 (bp->b_flags & B_READ) == 0) 1631 vprint(NULL, bp->b_vp); 1632 } 1633 } 1634 #endif 1635 } 1636 1637 return nbusy; 1638 } 1639 1640 static void 1641 sysctl_fillbuf(buf_t *i, struct buf_sysctl *o) 1642 { 1643 1644 o->b_flags = i->b_flags | i->b_cflags | i->b_oflags; 1645 o->b_error = i->b_error; 1646 o->b_prio = i->b_prio; 1647 o->b_dev = i->b_dev; 1648 o->b_bufsize = i->b_bufsize; 1649 o->b_bcount = i->b_bcount; 1650 o->b_resid = i->b_resid; 1651 o->b_addr = PTRTOUINT64(i->b_data); 1652 o->b_blkno = i->b_blkno; 1653 o->b_rawblkno = i->b_rawblkno; 1654 o->b_iodone = PTRTOUINT64(i->b_iodone); 1655 o->b_proc = PTRTOUINT64(i->b_proc); 1656 o->b_vp = PTRTOUINT64(i->b_vp); 1657 o->b_saveaddr = PTRTOUINT64(i->b_saveaddr); 1658 o->b_lblkno = i->b_lblkno; 1659 } 1660 1661 #define KERN_BUFSLOP 20 1662 static int 1663 sysctl_dobuf(SYSCTLFN_ARGS) 1664 { 1665 buf_t *bp; 1666 struct buf_sysctl bs; 1667 struct bqueue *bq; 1668 char *dp; 1669 u_int i, op, arg; 1670 size_t len, needed, elem_size, out_size; 1671 int error, elem_count, retries; 1672 1673 if (namelen == 1 && name[0] == CTL_QUERY) 1674 return (sysctl_query(SYSCTLFN_CALL(rnode))); 1675 1676 if (namelen != 4) 1677 return (EINVAL); 1678 1679 retries = 100; 1680 retry: 1681 dp = oldp; 1682 len = (oldp != NULL) ? *oldlenp : 0; 1683 op = name[0]; 1684 arg = name[1]; 1685 elem_size = name[2]; 1686 elem_count = name[3]; 1687 out_size = MIN(sizeof(bs), elem_size); 1688 1689 /* 1690 * at the moment, these are just "placeholders" to make the 1691 * API for retrieving kern.buf data more extensible in the 1692 * future. 1693 * 1694 * XXX kern.buf currently has "netbsd32" issues. hopefully 1695 * these will be resolved at a later point. 1696 */ 1697 if (op != KERN_BUF_ALL || arg != KERN_BUF_ALL || 1698 elem_size < 1 || elem_count < 0) 1699 return (EINVAL); 1700 1701 error = 0; 1702 needed = 0; 1703 sysctl_unlock(); 1704 mutex_enter(&bufcache_lock); 1705 for (i = 0; i < BQUEUES; i++) { 1706 bq = &bufqueues[i]; 1707 TAILQ_FOREACH(bp, &bq->bq_queue, b_freelist) { 1708 bq->bq_marker = bp; 1709 if (len >= elem_size && elem_count > 0) { 1710 sysctl_fillbuf(bp, &bs); 1711 mutex_exit(&bufcache_lock); 1712 error = copyout(&bs, dp, out_size); 1713 mutex_enter(&bufcache_lock); 1714 if (error) 1715 break; 1716 if (bq->bq_marker != bp) { 1717 /* 1718 * This sysctl node is only for 1719 * statistics. Retry; if the 1720 * queue keeps changing, then 1721 * bail out. 1722 */ 1723 if (retries-- == 0) { 1724 error = EAGAIN; 1725 break; 1726 } 1727 mutex_exit(&bufcache_lock); 1728 sysctl_relock(); 1729 goto retry; 1730 } 1731 dp += elem_size; 1732 len -= elem_size; 1733 } 1734 needed += elem_size; 1735 if (elem_count > 0 && elem_count != INT_MAX) 1736 elem_count--; 1737 } 1738 if (error != 0) 1739 break; 1740 } 1741 mutex_exit(&bufcache_lock); 1742 sysctl_relock(); 1743 1744 *oldlenp = needed; 1745 if (oldp == NULL) 1746 *oldlenp += KERN_BUFSLOP * sizeof(buf_t); 1747 1748 return (error); 1749 } 1750 1751 static int 1752 sysctl_bufvm_update(SYSCTLFN_ARGS) 1753 { 1754 int error, rv; 1755 struct sysctlnode node; 1756 unsigned int temp_bufcache; 1757 unsigned long temp_water; 1758 1759 /* Take a copy of the supplied node and its data */ 1760 node = *rnode; 1761 if (node.sysctl_data == &bufcache) { 1762 node.sysctl_data = &temp_bufcache; 1763 temp_bufcache = *(unsigned int *)rnode->sysctl_data; 1764 } else { 1765 node.sysctl_data = &temp_water; 1766 temp_water = *(unsigned long *)rnode->sysctl_data; 1767 } 1768 1769 /* Update the copy */ 1770 error = sysctl_lookup(SYSCTLFN_CALL(&node)); 1771 if (error || newp == NULL) 1772 return (error); 1773 1774 if (rnode->sysctl_data == &bufcache) { 1775 if (temp_bufcache > 100) 1776 return (EINVAL); 1777 bufcache = temp_bufcache; 1778 buf_setwm(); 1779 } else if (rnode->sysctl_data == &bufmem_lowater) { 1780 if (bufmem_hiwater - temp_water < 16) 1781 return (EINVAL); 1782 bufmem_lowater = temp_water; 1783 } else if (rnode->sysctl_data == &bufmem_hiwater) { 1784 if (temp_water - bufmem_lowater < 16) 1785 return (EINVAL); 1786 bufmem_hiwater = temp_water; 1787 } else 1788 return (EINVAL); 1789 1790 /* Drain until below new high water mark */ 1791 sysctl_unlock(); 1792 mutex_enter(&bufcache_lock); 1793 while (bufmem > bufmem_hiwater) { 1794 rv = buf_drain((bufmem - bufmem_hiwater) / (2 * 1024)); 1795 if (rv <= 0) 1796 break; 1797 } 1798 mutex_exit(&bufcache_lock); 1799 sysctl_relock(); 1800 1801 return 0; 1802 } 1803 1804 static struct sysctllog *vfsbio_sysctllog; 1805 1806 static void 1807 sysctl_kern_buf_setup(void) 1808 { 1809 1810 sysctl_createv(&vfsbio_sysctllog, 0, NULL, NULL, 1811 CTLFLAG_PERMANENT, 1812 CTLTYPE_NODE, "buf", 1813 SYSCTL_DESCR("Kernel buffer cache information"), 1814 sysctl_dobuf, 0, NULL, 0, 1815 CTL_KERN, KERN_BUF, CTL_EOL); 1816 } 1817 1818 static void 1819 sysctl_vm_buf_setup(void) 1820 { 1821 1822 sysctl_createv(&vfsbio_sysctllog, 0, NULL, NULL, 1823 CTLFLAG_PERMANENT|CTLFLAG_READWRITE, 1824 CTLTYPE_INT, "bufcache", 1825 SYSCTL_DESCR("Percentage of physical memory to use for " 1826 "buffer cache"), 1827 sysctl_bufvm_update, 0, &bufcache, 0, 1828 CTL_VM, CTL_CREATE, CTL_EOL); 1829 sysctl_createv(&vfsbio_sysctllog, 0, NULL, NULL, 1830 CTLFLAG_PERMANENT|CTLFLAG_READONLY, 1831 CTLTYPE_LONG, "bufmem", 1832 SYSCTL_DESCR("Amount of kernel memory used by buffer " 1833 "cache"), 1834 NULL, 0, &bufmem, 0, 1835 CTL_VM, CTL_CREATE, CTL_EOL); 1836 sysctl_createv(&vfsbio_sysctllog, 0, NULL, NULL, 1837 CTLFLAG_PERMANENT|CTLFLAG_READWRITE, 1838 CTLTYPE_LONG, "bufmem_lowater", 1839 SYSCTL_DESCR("Minimum amount of kernel memory to " 1840 "reserve for buffer cache"), 1841 sysctl_bufvm_update, 0, &bufmem_lowater, 0, 1842 CTL_VM, CTL_CREATE, CTL_EOL); 1843 sysctl_createv(&vfsbio_sysctllog, 0, NULL, NULL, 1844 CTLFLAG_PERMANENT|CTLFLAG_READWRITE, 1845 CTLTYPE_LONG, "bufmem_hiwater", 1846 SYSCTL_DESCR("Maximum amount of kernel memory to use " 1847 "for buffer cache"), 1848 sysctl_bufvm_update, 0, &bufmem_hiwater, 0, 1849 CTL_VM, CTL_CREATE, CTL_EOL); 1850 } 1851 1852 #ifdef DEBUG 1853 /* 1854 * Print out statistics on the current allocation of the buffer pool. 1855 * Can be enabled to print out on every ``sync'' by setting "syncprt" 1856 * in vfs_syscalls.c using sysctl. 1857 */ 1858 void 1859 vfs_bufstats(void) 1860 { 1861 int i, j, count; 1862 buf_t *bp; 1863 struct bqueue *dp; 1864 int counts[(MAXBSIZE / PAGE_SIZE) + 1]; 1865 static const char *bname[BQUEUES] = { "LOCKED", "LRU", "AGE" }; 1866 1867 for (dp = bufqueues, i = 0; dp < &bufqueues[BQUEUES]; dp++, i++) { 1868 count = 0; 1869 for (j = 0; j <= MAXBSIZE/PAGE_SIZE; j++) 1870 counts[j] = 0; 1871 TAILQ_FOREACH(bp, &dp->bq_queue, b_freelist) { 1872 counts[bp->b_bufsize/PAGE_SIZE]++; 1873 count++; 1874 } 1875 printf("%s: total-%d", bname[i], count); 1876 for (j = 0; j <= MAXBSIZE/PAGE_SIZE; j++) 1877 if (counts[j] != 0) 1878 printf(", %d-%d", j * PAGE_SIZE, counts[j]); 1879 printf("\n"); 1880 } 1881 } 1882 #endif /* DEBUG */ 1883 1884 /* ------------------------------ */ 1885 1886 buf_t * 1887 getiobuf(struct vnode *vp, bool waitok) 1888 { 1889 buf_t *bp; 1890 1891 bp = pool_cache_get(bufio_cache, (waitok ? PR_WAITOK : PR_NOWAIT)); 1892 if (bp == NULL) 1893 return bp; 1894 1895 buf_init(bp); 1896 1897 if ((bp->b_vp = vp) == NULL) 1898 bp->b_objlock = &buffer_lock; 1899 else 1900 bp->b_objlock = vp->v_interlock; 1901 1902 return bp; 1903 } 1904 1905 void 1906 putiobuf(buf_t *bp) 1907 { 1908 1909 buf_destroy(bp); 1910 pool_cache_put(bufio_cache, bp); 1911 } 1912 1913 /* 1914 * nestiobuf_iodone: b_iodone callback for nested buffers. 1915 */ 1916 1917 void 1918 nestiobuf_iodone(buf_t *bp) 1919 { 1920 buf_t *mbp = bp->b_private; 1921 int error; 1922 int donebytes; 1923 1924 KASSERT(bp->b_bcount <= bp->b_bufsize); 1925 KASSERT(mbp != bp); 1926 1927 error = bp->b_error; 1928 if (bp->b_error == 0 && 1929 (bp->b_bcount < bp->b_bufsize || bp->b_resid > 0)) { 1930 /* 1931 * Not all got transfered, raise an error. We have no way to 1932 * propagate these conditions to mbp. 1933 */ 1934 error = EIO; 1935 } 1936 1937 donebytes = bp->b_bufsize; 1938 1939 putiobuf(bp); 1940 nestiobuf_done(mbp, donebytes, error); 1941 } 1942 1943 /* 1944 * nestiobuf_setup: setup a "nested" buffer. 1945 * 1946 * => 'mbp' is a "master" buffer which is being divided into sub pieces. 1947 * => 'bp' should be a buffer allocated by getiobuf. 1948 * => 'offset' is a byte offset in the master buffer. 1949 * => 'size' is a size in bytes of this nested buffer. 1950 */ 1951 1952 void 1953 nestiobuf_setup(buf_t *mbp, buf_t *bp, int offset, size_t size) 1954 { 1955 const int b_read = mbp->b_flags & B_READ; 1956 struct vnode *vp = mbp->b_vp; 1957 1958 KASSERT(mbp->b_bcount >= offset + size); 1959 bp->b_vp = vp; 1960 bp->b_dev = mbp->b_dev; 1961 bp->b_objlock = mbp->b_objlock; 1962 bp->b_cflags = BC_BUSY; 1963 bp->b_flags = B_ASYNC | b_read; 1964 bp->b_iodone = nestiobuf_iodone; 1965 bp->b_data = (char *)mbp->b_data + offset; 1966 bp->b_resid = bp->b_bcount = size; 1967 bp->b_bufsize = bp->b_bcount; 1968 bp->b_private = mbp; 1969 BIO_COPYPRIO(bp, mbp); 1970 if (!b_read && vp != NULL) { 1971 mutex_enter(vp->v_interlock); 1972 vp->v_numoutput++; 1973 mutex_exit(vp->v_interlock); 1974 } 1975 } 1976 1977 /* 1978 * nestiobuf_done: propagate completion to the master buffer. 1979 * 1980 * => 'donebytes' specifies how many bytes in the 'mbp' is completed. 1981 * => 'error' is an errno(2) that 'donebytes' has been completed with. 1982 */ 1983 1984 void 1985 nestiobuf_done(buf_t *mbp, int donebytes, int error) 1986 { 1987 1988 if (donebytes == 0) { 1989 return; 1990 } 1991 mutex_enter(mbp->b_objlock); 1992 KASSERT(mbp->b_resid >= donebytes); 1993 mbp->b_resid -= donebytes; 1994 if (error) 1995 mbp->b_error = error; 1996 if (mbp->b_resid == 0) { 1997 if (mbp->b_error) 1998 mbp->b_resid = mbp->b_bcount; 1999 mutex_exit(mbp->b_objlock); 2000 biodone(mbp); 2001 } else 2002 mutex_exit(mbp->b_objlock); 2003 } 2004 2005 void 2006 buf_init(buf_t *bp) 2007 { 2008 2009 cv_init(&bp->b_busy, "biolock"); 2010 cv_init(&bp->b_done, "biowait"); 2011 bp->b_dev = NODEV; 2012 bp->b_error = 0; 2013 bp->b_flags = 0; 2014 bp->b_cflags = 0; 2015 bp->b_oflags = 0; 2016 bp->b_objlock = &buffer_lock; 2017 bp->b_iodone = NULL; 2018 bp->b_refcnt = 1; 2019 bp->b_dev = NODEV; 2020 bp->b_vnbufs.le_next = NOLIST; 2021 BIO_SETPRIO(bp, BPRIO_DEFAULT); 2022 } 2023 2024 void 2025 buf_destroy(buf_t *bp) 2026 { 2027 2028 cv_destroy(&bp->b_done); 2029 cv_destroy(&bp->b_busy); 2030 } 2031 2032 int 2033 bbusy(buf_t *bp, bool intr, int timo, kmutex_t *interlock) 2034 { 2035 int error; 2036 2037 KASSERT(mutex_owned(&bufcache_lock)); 2038 2039 if ((bp->b_cflags & BC_BUSY) != 0) { 2040 if (curlwp == uvm.pagedaemon_lwp) 2041 return EDEADLK; 2042 bp->b_cflags |= BC_WANTED; 2043 bref(bp); 2044 if (interlock != NULL) 2045 mutex_exit(interlock); 2046 if (intr) { 2047 error = cv_timedwait_sig(&bp->b_busy, &bufcache_lock, 2048 timo); 2049 } else { 2050 error = cv_timedwait(&bp->b_busy, &bufcache_lock, 2051 timo); 2052 } 2053 brele(bp); 2054 if (interlock != NULL) 2055 mutex_enter(interlock); 2056 if (error != 0) 2057 return error; 2058 return EPASSTHROUGH; 2059 } 2060 bp->b_cflags |= BC_BUSY; 2061 2062 return 0; 2063 } 2064