1 /* $NetBSD: vfs_bio.c,v 1.276 2017/10/28 00:37:11 pgoyette 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 1.276 2017/10/28 00:37:11 pgoyette Exp $"); 127 128 #ifdef _KERNEL_OPT 129 #include "opt_bufcache.h" 130 #include "opt_dtrace.h" 131 #include "opt_biohist.h" 132 #endif 133 134 #include <sys/param.h> 135 #include <sys/systm.h> 136 #include <sys/kernel.h> 137 #include <sys/proc.h> 138 #include <sys/buf.h> 139 #include <sys/vnode.h> 140 #include <sys/mount.h> 141 #include <sys/resourcevar.h> 142 #include <sys/sysctl.h> 143 #include <sys/conf.h> 144 #include <sys/kauth.h> 145 #include <sys/fstrans.h> 146 #include <sys/intr.h> 147 #include <sys/cpu.h> 148 #include <sys/wapbl.h> 149 #include <sys/bitops.h> 150 #include <sys/cprng.h> 151 #include <sys/sdt.h> 152 153 #include <uvm/uvm.h> /* extern struct uvm uvm */ 154 155 #include <miscfs/specfs/specdev.h> 156 157 #ifndef BUFPAGES 158 # define BUFPAGES 0 159 #endif 160 161 #ifdef BUFCACHE 162 # if (BUFCACHE < 5) || (BUFCACHE > 95) 163 # error BUFCACHE is not between 5 and 95 164 # endif 165 #else 166 # define BUFCACHE 15 167 #endif 168 169 u_int nbuf; /* desired number of buffer headers */ 170 u_int bufpages = BUFPAGES; /* optional hardwired count */ 171 u_int bufcache = BUFCACHE; /* max % of RAM to use for buffer cache */ 172 173 /* 174 * Definitions for the buffer free lists. 175 */ 176 #define BQUEUES 3 /* number of free buffer queues */ 177 178 #define BQ_LOCKED 0 /* super-blocks &c */ 179 #define BQ_LRU 1 /* lru, useful buffers */ 180 #define BQ_AGE 2 /* rubbish */ 181 182 struct bqueue { 183 TAILQ_HEAD(, buf) bq_queue; 184 uint64_t bq_bytes; 185 buf_t *bq_marker; 186 }; 187 static struct bqueue bufqueues[BQUEUES]; 188 189 /* Function prototypes */ 190 static void buf_setwm(void); 191 static int buf_trim(void); 192 static void *bufpool_page_alloc(struct pool *, int); 193 static void bufpool_page_free(struct pool *, void *); 194 static buf_t *bio_doread(struct vnode *, daddr_t, int, int); 195 static buf_t *getnewbuf(int, int, int); 196 static int buf_lotsfree(void); 197 static int buf_canrelease(void); 198 static u_long buf_mempoolidx(u_long); 199 static u_long buf_roundsize(u_long); 200 static void *buf_alloc(size_t); 201 static void buf_mrelease(void *, size_t); 202 static void binsheadfree(buf_t *, struct bqueue *); 203 static void binstailfree(buf_t *, struct bqueue *); 204 #ifdef DEBUG 205 static int checkfreelist(buf_t *, struct bqueue *, int); 206 #endif 207 static void biointr(void *); 208 static void biodone2(buf_t *); 209 static void bref(buf_t *); 210 static void brele(buf_t *); 211 static void sysctl_kern_buf_setup(void); 212 static void sysctl_vm_buf_setup(void); 213 214 /* Initialization for biohist */ 215 216 #include <sys/biohist.h> 217 218 BIOHIST_DEFINE(biohist); 219 220 void 221 biohist_init(void) 222 { 223 224 BIOHIST_INIT(biohist, BIOHIST_SIZE); 225 } 226 227 /* 228 * Definitions for the buffer hash lists. 229 */ 230 #define BUFHASH(dvp, lbn) \ 231 (&bufhashtbl[(((long)(dvp) >> 8) + (int)(lbn)) & bufhash]) 232 LIST_HEAD(bufhashhdr, buf) *bufhashtbl, invalhash; 233 u_long bufhash; 234 235 static kcondvar_t needbuffer_cv; 236 237 /* 238 * Buffer queue lock. 239 */ 240 kmutex_t bufcache_lock; 241 kmutex_t buffer_lock; 242 243 /* Software ISR for completed transfers. */ 244 static void *biodone_sih; 245 246 /* Buffer pool for I/O buffers. */ 247 static pool_cache_t buf_cache; 248 static pool_cache_t bufio_cache; 249 250 #define MEMPOOL_INDEX_OFFSET (ilog2(DEV_BSIZE)) /* smallest pool is 512 bytes */ 251 #define NMEMPOOLS (ilog2(MAXBSIZE) - MEMPOOL_INDEX_OFFSET + 1) 252 __CTASSERT((1 << (NMEMPOOLS + MEMPOOL_INDEX_OFFSET - 1)) == MAXBSIZE); 253 254 /* Buffer memory pools */ 255 static struct pool bmempools[NMEMPOOLS]; 256 257 static struct vm_map *buf_map; 258 259 /* 260 * Buffer memory pool allocator. 261 */ 262 static void * 263 bufpool_page_alloc(struct pool *pp, int flags) 264 { 265 266 return (void *)uvm_km_alloc(buf_map, 267 MAXBSIZE, MAXBSIZE, 268 ((flags & PR_WAITOK) ? 0 : UVM_KMF_NOWAIT|UVM_KMF_TRYLOCK) 269 | UVM_KMF_WIRED); 270 } 271 272 static void 273 bufpool_page_free(struct pool *pp, void *v) 274 { 275 276 uvm_km_free(buf_map, (vaddr_t)v, MAXBSIZE, UVM_KMF_WIRED); 277 } 278 279 static struct pool_allocator bufmempool_allocator = { 280 .pa_alloc = bufpool_page_alloc, 281 .pa_free = bufpool_page_free, 282 .pa_pagesz = MAXBSIZE, 283 }; 284 285 /* Buffer memory management variables */ 286 u_long bufmem_valimit; 287 u_long bufmem_hiwater; 288 u_long bufmem_lowater; 289 u_long bufmem; 290 291 /* 292 * MD code can call this to set a hard limit on the amount 293 * of virtual memory used by the buffer cache. 294 */ 295 int 296 buf_setvalimit(vsize_t sz) 297 { 298 299 /* We need to accommodate at least NMEMPOOLS of MAXBSIZE each */ 300 if (sz < NMEMPOOLS * MAXBSIZE) 301 return EINVAL; 302 303 bufmem_valimit = sz; 304 return 0; 305 } 306 307 static void 308 buf_setwm(void) 309 { 310 311 bufmem_hiwater = buf_memcalc(); 312 /* lowater is approx. 2% of memory (with bufcache = 15) */ 313 #define BUFMEM_WMSHIFT 3 314 #define BUFMEM_HIWMMIN (64 * 1024 << BUFMEM_WMSHIFT) 315 if (bufmem_hiwater < BUFMEM_HIWMMIN) 316 /* Ensure a reasonable minimum value */ 317 bufmem_hiwater = BUFMEM_HIWMMIN; 318 bufmem_lowater = bufmem_hiwater >> BUFMEM_WMSHIFT; 319 } 320 321 #ifdef DEBUG 322 int debug_verify_freelist = 0; 323 static int 324 checkfreelist(buf_t *bp, struct bqueue *dp, int ison) 325 { 326 buf_t *b; 327 328 if (!debug_verify_freelist) 329 return 1; 330 331 TAILQ_FOREACH(b, &dp->bq_queue, b_freelist) { 332 if (b == bp) 333 return ison ? 1 : 0; 334 } 335 336 return ison ? 0 : 1; 337 } 338 #endif 339 340 /* 341 * Insq/Remq for the buffer hash lists. 342 * Call with buffer queue locked. 343 */ 344 static void 345 binsheadfree(buf_t *bp, struct bqueue *dp) 346 { 347 348 KASSERT(mutex_owned(&bufcache_lock)); 349 KASSERT(bp->b_freelistindex == -1); 350 TAILQ_INSERT_HEAD(&dp->bq_queue, bp, b_freelist); 351 dp->bq_bytes += bp->b_bufsize; 352 bp->b_freelistindex = dp - bufqueues; 353 } 354 355 static void 356 binstailfree(buf_t *bp, struct bqueue *dp) 357 { 358 359 KASSERT(mutex_owned(&bufcache_lock)); 360 KASSERTMSG(bp->b_freelistindex == -1, "double free of buffer? " 361 "bp=%p, b_freelistindex=%d\n", bp, bp->b_freelistindex); 362 TAILQ_INSERT_TAIL(&dp->bq_queue, bp, b_freelist); 363 dp->bq_bytes += bp->b_bufsize; 364 bp->b_freelistindex = dp - bufqueues; 365 } 366 367 void 368 bremfree(buf_t *bp) 369 { 370 struct bqueue *dp; 371 int bqidx = bp->b_freelistindex; 372 373 KASSERT(mutex_owned(&bufcache_lock)); 374 375 KASSERT(bqidx != -1); 376 dp = &bufqueues[bqidx]; 377 KDASSERT(checkfreelist(bp, dp, 1)); 378 KASSERT(dp->bq_bytes >= bp->b_bufsize); 379 TAILQ_REMOVE(&dp->bq_queue, bp, b_freelist); 380 dp->bq_bytes -= bp->b_bufsize; 381 382 /* For the sysctl helper. */ 383 if (bp == dp->bq_marker) 384 dp->bq_marker = NULL; 385 386 #if defined(DIAGNOSTIC) 387 bp->b_freelistindex = -1; 388 #endif /* defined(DIAGNOSTIC) */ 389 } 390 391 /* 392 * Add a reference to an buffer structure that came from buf_cache. 393 */ 394 static inline void 395 bref(buf_t *bp) 396 { 397 398 KASSERT(mutex_owned(&bufcache_lock)); 399 KASSERT(bp->b_refcnt > 0); 400 401 bp->b_refcnt++; 402 } 403 404 /* 405 * Free an unused buffer structure that came from buf_cache. 406 */ 407 static inline void 408 brele(buf_t *bp) 409 { 410 411 KASSERT(mutex_owned(&bufcache_lock)); 412 KASSERT(bp->b_refcnt > 0); 413 414 if (bp->b_refcnt-- == 1) { 415 buf_destroy(bp); 416 #ifdef DEBUG 417 memset((char *)bp, 0, sizeof(*bp)); 418 #endif 419 pool_cache_put(buf_cache, bp); 420 } 421 } 422 423 /* 424 * note that for some ports this is used by pmap bootstrap code to 425 * determine kva size. 426 */ 427 u_long 428 buf_memcalc(void) 429 { 430 u_long n; 431 vsize_t mapsz = 0; 432 433 /* 434 * Determine the upper bound of memory to use for buffers. 435 * 436 * - If bufpages is specified, use that as the number 437 * pages. 438 * 439 * - Otherwise, use bufcache as the percentage of 440 * physical memory. 441 */ 442 if (bufpages != 0) { 443 n = bufpages; 444 } else { 445 if (bufcache < 5) { 446 printf("forcing bufcache %d -> 5", bufcache); 447 bufcache = 5; 448 } 449 if (bufcache > 95) { 450 printf("forcing bufcache %d -> 95", bufcache); 451 bufcache = 95; 452 } 453 if (buf_map != NULL) 454 mapsz = vm_map_max(buf_map) - vm_map_min(buf_map); 455 n = calc_cache_size(mapsz, bufcache, 456 (buf_map != kernel_map) ? 100 : BUFCACHE_VA_MAXPCT) 457 / PAGE_SIZE; 458 } 459 460 n <<= PAGE_SHIFT; 461 if (bufmem_valimit != 0 && n > bufmem_valimit) 462 n = bufmem_valimit; 463 464 return (n); 465 } 466 467 /* 468 * Initialize buffers and hash links for buffers. 469 */ 470 void 471 bufinit(void) 472 { 473 struct bqueue *dp; 474 int use_std; 475 u_int i; 476 477 biodone_vfs = biodone; 478 479 mutex_init(&bufcache_lock, MUTEX_DEFAULT, IPL_NONE); 480 mutex_init(&buffer_lock, MUTEX_DEFAULT, IPL_NONE); 481 cv_init(&needbuffer_cv, "needbuf"); 482 483 if (bufmem_valimit != 0) { 484 vaddr_t minaddr = 0, maxaddr; 485 buf_map = uvm_km_suballoc(kernel_map, &minaddr, &maxaddr, 486 bufmem_valimit, 0, false, 0); 487 if (buf_map == NULL) 488 panic("bufinit: cannot allocate submap"); 489 } else 490 buf_map = kernel_map; 491 492 /* 493 * Initialize buffer cache memory parameters. 494 */ 495 bufmem = 0; 496 buf_setwm(); 497 498 /* On "small" machines use small pool page sizes where possible */ 499 use_std = (physmem < atop(16*1024*1024)); 500 501 /* 502 * Also use them on systems that can map the pool pages using 503 * a direct-mapped segment. 504 */ 505 #ifdef PMAP_MAP_POOLPAGE 506 use_std = 1; 507 #endif 508 509 buf_cache = pool_cache_init(sizeof(buf_t), 0, 0, 0, 510 "bufpl", NULL, IPL_SOFTBIO, NULL, NULL, NULL); 511 bufio_cache = pool_cache_init(sizeof(buf_t), 0, 0, 0, 512 "biopl", NULL, IPL_BIO, NULL, NULL, NULL); 513 514 for (i = 0; i < NMEMPOOLS; i++) { 515 struct pool_allocator *pa; 516 struct pool *pp = &bmempools[i]; 517 u_int size = 1 << (i + MEMPOOL_INDEX_OFFSET); 518 char *name = kmem_alloc(8, KM_SLEEP); /* XXX: never freed */ 519 if (__predict_false(size >= 1048576)) 520 (void)snprintf(name, 8, "buf%um", size / 1048576); 521 else if (__predict_true(size >= 1024)) 522 (void)snprintf(name, 8, "buf%uk", size / 1024); 523 else 524 (void)snprintf(name, 8, "buf%ub", size); 525 pa = (size <= PAGE_SIZE && use_std) 526 ? &pool_allocator_nointr 527 : &bufmempool_allocator; 528 pool_init(pp, size, 0, 0, 0, name, pa, IPL_NONE); 529 pool_setlowat(pp, 1); 530 pool_sethiwat(pp, 1); 531 } 532 533 /* Initialize the buffer queues */ 534 for (dp = bufqueues; dp < &bufqueues[BQUEUES]; dp++) { 535 TAILQ_INIT(&dp->bq_queue); 536 dp->bq_bytes = 0; 537 } 538 539 /* 540 * Estimate hash table size based on the amount of memory we 541 * intend to use for the buffer cache. The average buffer 542 * size is dependent on our clients (i.e. filesystems). 543 * 544 * For now, use an empirical 3K per buffer. 545 */ 546 nbuf = (bufmem_hiwater / 1024) / 3; 547 bufhashtbl = hashinit(nbuf, HASH_LIST, true, &bufhash); 548 549 sysctl_kern_buf_setup(); 550 sysctl_vm_buf_setup(); 551 } 552 553 void 554 bufinit2(void) 555 { 556 557 biodone_sih = softint_establish(SOFTINT_BIO | SOFTINT_MPSAFE, biointr, 558 NULL); 559 if (biodone_sih == NULL) 560 panic("bufinit2: can't establish soft interrupt"); 561 } 562 563 static int 564 buf_lotsfree(void) 565 { 566 u_long guess; 567 568 /* Always allocate if less than the low water mark. */ 569 if (bufmem < bufmem_lowater) 570 return 1; 571 572 /* Never allocate if greater than the high water mark. */ 573 if (bufmem > bufmem_hiwater) 574 return 0; 575 576 /* If there's anything on the AGE list, it should be eaten. */ 577 if (TAILQ_FIRST(&bufqueues[BQ_AGE].bq_queue) != NULL) 578 return 0; 579 580 /* 581 * The probabily of getting a new allocation is inversely 582 * proportional to the current size of the cache above 583 * the low water mark. Divide the total first to avoid overflows 584 * in the product. 585 */ 586 guess = cprng_fast32() % 16; 587 588 if ((bufmem_hiwater - bufmem_lowater) / 16 * guess >= 589 (bufmem - bufmem_lowater)) 590 return 1; 591 592 /* Otherwise don't allocate. */ 593 return 0; 594 } 595 596 /* 597 * Return estimate of bytes we think need to be 598 * released to help resolve low memory conditions. 599 * 600 * => called with bufcache_lock held. 601 */ 602 static int 603 buf_canrelease(void) 604 { 605 int pagedemand, ninvalid = 0; 606 607 KASSERT(mutex_owned(&bufcache_lock)); 608 609 if (bufmem < bufmem_lowater) 610 return 0; 611 612 if (bufmem > bufmem_hiwater) 613 return bufmem - bufmem_hiwater; 614 615 ninvalid += bufqueues[BQ_AGE].bq_bytes; 616 617 pagedemand = uvmexp.freetarg - uvmexp.free; 618 if (pagedemand < 0) 619 return ninvalid; 620 return MAX(ninvalid, MIN(2 * MAXBSIZE, 621 MIN((bufmem - bufmem_lowater) / 16, pagedemand * PAGE_SIZE))); 622 } 623 624 /* 625 * Buffer memory allocation helper functions 626 */ 627 static u_long 628 buf_mempoolidx(u_long size) 629 { 630 u_int n = 0; 631 632 size -= 1; 633 size >>= MEMPOOL_INDEX_OFFSET; 634 while (size) { 635 size >>= 1; 636 n += 1; 637 } 638 if (n >= NMEMPOOLS) 639 panic("buf mem pool index %d", n); 640 return n; 641 } 642 643 static u_long 644 buf_roundsize(u_long size) 645 { 646 /* Round up to nearest power of 2 */ 647 return (1 << (buf_mempoolidx(size) + MEMPOOL_INDEX_OFFSET)); 648 } 649 650 static void * 651 buf_alloc(size_t size) 652 { 653 u_int n = buf_mempoolidx(size); 654 void *addr; 655 656 while (1) { 657 addr = pool_get(&bmempools[n], PR_NOWAIT); 658 if (addr != NULL) 659 break; 660 661 /* No memory, see if we can free some. If so, try again */ 662 mutex_enter(&bufcache_lock); 663 if (buf_drain(1) > 0) { 664 mutex_exit(&bufcache_lock); 665 continue; 666 } 667 668 if (curlwp == uvm.pagedaemon_lwp) { 669 mutex_exit(&bufcache_lock); 670 return NULL; 671 } 672 673 /* Wait for buffers to arrive on the LRU queue */ 674 cv_timedwait(&needbuffer_cv, &bufcache_lock, hz / 4); 675 mutex_exit(&bufcache_lock); 676 } 677 678 return addr; 679 } 680 681 static void 682 buf_mrelease(void *addr, size_t size) 683 { 684 685 pool_put(&bmempools[buf_mempoolidx(size)], addr); 686 } 687 688 /* 689 * bread()/breadn() helper. 690 */ 691 static buf_t * 692 bio_doread(struct vnode *vp, daddr_t blkno, int size, int async) 693 { 694 buf_t *bp; 695 struct mount *mp; 696 697 bp = getblk(vp, blkno, size, 0, 0); 698 699 /* 700 * getblk() may return NULL if we are the pagedaemon. 701 */ 702 if (bp == NULL) { 703 KASSERT(curlwp == uvm.pagedaemon_lwp); 704 return NULL; 705 } 706 707 /* 708 * If buffer does not have data valid, start a read. 709 * Note that if buffer is BC_INVAL, getblk() won't return it. 710 * Therefore, it's valid if its I/O has completed or been delayed. 711 */ 712 if (!ISSET(bp->b_oflags, (BO_DONE | BO_DELWRI))) { 713 /* Start I/O for the buffer. */ 714 SET(bp->b_flags, B_READ | async); 715 if (async) 716 BIO_SETPRIO(bp, BPRIO_TIMELIMITED); 717 else 718 BIO_SETPRIO(bp, BPRIO_TIMECRITICAL); 719 VOP_STRATEGY(vp, bp); 720 721 /* Pay for the read. */ 722 curlwp->l_ru.ru_inblock++; 723 } else if (async) 724 brelse(bp, 0); 725 726 if (vp->v_type == VBLK) 727 mp = spec_node_getmountedfs(vp); 728 else 729 mp = vp->v_mount; 730 731 /* 732 * Collect statistics on synchronous and asynchronous reads. 733 * Reads from block devices are charged to their associated 734 * filesystem (if any). 735 */ 736 if (mp != NULL) { 737 if (async == 0) 738 mp->mnt_stat.f_syncreads++; 739 else 740 mp->mnt_stat.f_asyncreads++; 741 } 742 743 return (bp); 744 } 745 746 /* 747 * Read a disk block. 748 * This algorithm described in Bach (p.54). 749 */ 750 int 751 bread(struct vnode *vp, daddr_t blkno, int size, int flags, buf_t **bpp) 752 { 753 buf_t *bp; 754 int error; 755 756 BIOHIST_FUNC(__func__); BIOHIST_CALLED(biohist); 757 758 /* Get buffer for block. */ 759 bp = *bpp = bio_doread(vp, blkno, size, 0); 760 if (bp == NULL) 761 return ENOMEM; 762 763 /* Wait for the read to complete, and return result. */ 764 error = biowait(bp); 765 if (error == 0 && (flags & B_MODIFY) != 0) 766 error = fscow_run(bp, true); 767 if (error) { 768 brelse(bp, 0); 769 *bpp = NULL; 770 } 771 772 return error; 773 } 774 775 /* 776 * Read-ahead multiple disk blocks. The first is sync, the rest async. 777 * Trivial modification to the breada algorithm presented in Bach (p.55). 778 */ 779 int 780 breadn(struct vnode *vp, daddr_t blkno, int size, daddr_t *rablks, 781 int *rasizes, int nrablks, int flags, buf_t **bpp) 782 { 783 buf_t *bp; 784 int error, i; 785 786 BIOHIST_FUNC(__func__); BIOHIST_CALLED(biohist); 787 788 bp = *bpp = bio_doread(vp, blkno, size, 0); 789 if (bp == NULL) 790 return ENOMEM; 791 792 /* 793 * For each of the read-ahead blocks, start a read, if necessary. 794 */ 795 mutex_enter(&bufcache_lock); 796 for (i = 0; i < nrablks; i++) { 797 /* If it's in the cache, just go on to next one. */ 798 if (incore(vp, rablks[i])) 799 continue; 800 801 /* Get a buffer for the read-ahead block */ 802 mutex_exit(&bufcache_lock); 803 (void) bio_doread(vp, rablks[i], rasizes[i], B_ASYNC); 804 mutex_enter(&bufcache_lock); 805 } 806 mutex_exit(&bufcache_lock); 807 808 /* Otherwise, we had to start a read for it; wait until it's valid. */ 809 error = biowait(bp); 810 if (error == 0 && (flags & B_MODIFY) != 0) 811 error = fscow_run(bp, true); 812 if (error) { 813 brelse(bp, 0); 814 *bpp = NULL; 815 } 816 817 return error; 818 } 819 820 /* 821 * Block write. Described in Bach (p.56) 822 */ 823 int 824 bwrite(buf_t *bp) 825 { 826 int rv, sync, wasdelayed; 827 struct vnode *vp; 828 struct mount *mp; 829 830 BIOHIST_FUNC(__func__); BIOHIST_CALLARGS(biohist, "bp=%#jx", 831 (uintptr_t)bp, 0, 0, 0); 832 833 KASSERT(ISSET(bp->b_cflags, BC_BUSY)); 834 KASSERT(!cv_has_waiters(&bp->b_done)); 835 836 vp = bp->b_vp; 837 838 /* 839 * dholland 20160728 AFAICT vp==NULL must be impossible as it 840 * will crash upon reaching VOP_STRATEGY below... see further 841 * analysis on tech-kern. 842 */ 843 KASSERTMSG(vp != NULL, "bwrite given buffer with null vnode"); 844 845 if (vp != NULL) { 846 KASSERT(bp->b_objlock == vp->v_interlock); 847 if (vp->v_type == VBLK) 848 mp = spec_node_getmountedfs(vp); 849 else 850 mp = vp->v_mount; 851 } else { 852 mp = NULL; 853 } 854 855 if (mp && mp->mnt_wapbl) { 856 if (bp->b_iodone != mp->mnt_wapbl_op->wo_wapbl_biodone) { 857 bdwrite(bp); 858 return 0; 859 } 860 } 861 862 /* 863 * Remember buffer type, to switch on it later. If the write was 864 * synchronous, but the file system was mounted with MNT_ASYNC, 865 * convert it to a delayed write. 866 * XXX note that this relies on delayed tape writes being converted 867 * to async, not sync writes (which is safe, but ugly). 868 */ 869 sync = !ISSET(bp->b_flags, B_ASYNC); 870 if (sync && mp != NULL && ISSET(mp->mnt_flag, MNT_ASYNC)) { 871 bdwrite(bp); 872 return (0); 873 } 874 875 /* 876 * Collect statistics on synchronous and asynchronous writes. 877 * Writes to block devices are charged to their associated 878 * filesystem (if any). 879 */ 880 if (mp != NULL) { 881 if (sync) 882 mp->mnt_stat.f_syncwrites++; 883 else 884 mp->mnt_stat.f_asyncwrites++; 885 } 886 887 /* 888 * Pay for the I/O operation and make sure the buf is on the correct 889 * vnode queue. 890 */ 891 bp->b_error = 0; 892 wasdelayed = ISSET(bp->b_oflags, BO_DELWRI); 893 CLR(bp->b_flags, B_READ); 894 if (wasdelayed) { 895 mutex_enter(&bufcache_lock); 896 mutex_enter(bp->b_objlock); 897 CLR(bp->b_oflags, BO_DONE | BO_DELWRI); 898 reassignbuf(bp, bp->b_vp); 899 mutex_exit(&bufcache_lock); 900 } else { 901 curlwp->l_ru.ru_oublock++; 902 mutex_enter(bp->b_objlock); 903 CLR(bp->b_oflags, BO_DONE | BO_DELWRI); 904 } 905 if (vp != NULL) 906 vp->v_numoutput++; 907 mutex_exit(bp->b_objlock); 908 909 /* Initiate disk write. */ 910 if (sync) 911 BIO_SETPRIO(bp, BPRIO_TIMECRITICAL); 912 else 913 BIO_SETPRIO(bp, BPRIO_TIMELIMITED); 914 915 VOP_STRATEGY(vp, bp); 916 917 if (sync) { 918 /* If I/O was synchronous, wait for it to complete. */ 919 rv = biowait(bp); 920 921 /* Release the buffer. */ 922 brelse(bp, 0); 923 924 return (rv); 925 } else { 926 return (0); 927 } 928 } 929 930 int 931 vn_bwrite(void *v) 932 { 933 struct vop_bwrite_args *ap = v; 934 935 return (bwrite(ap->a_bp)); 936 } 937 938 /* 939 * Delayed write. 940 * 941 * The buffer is marked dirty, but is not queued for I/O. 942 * This routine should be used when the buffer is expected 943 * to be modified again soon, typically a small write that 944 * partially fills a buffer. 945 * 946 * NB: magnetic tapes cannot be delayed; they must be 947 * written in the order that the writes are requested. 948 * 949 * Described in Leffler, et al. (pp. 208-213). 950 */ 951 void 952 bdwrite(buf_t *bp) 953 { 954 955 BIOHIST_FUNC(__func__); BIOHIST_CALLARGS(biohist, "bp=%#jx", 956 (uintptr_t)bp, 0, 0, 0); 957 958 KASSERT(bp->b_vp == NULL || bp->b_vp->v_tag != VT_UFS || 959 bp->b_vp->v_type == VBLK || ISSET(bp->b_flags, B_COWDONE)); 960 KASSERT(ISSET(bp->b_cflags, BC_BUSY)); 961 KASSERT(!cv_has_waiters(&bp->b_done)); 962 963 /* If this is a tape block, write the block now. */ 964 if (bdev_type(bp->b_dev) == D_TAPE) { 965 bawrite(bp); 966 return; 967 } 968 969 if (wapbl_vphaswapbl(bp->b_vp)) { 970 struct mount *mp = wapbl_vptomp(bp->b_vp); 971 972 if (bp->b_iodone != mp->mnt_wapbl_op->wo_wapbl_biodone) { 973 WAPBL_ADD_BUF(mp, bp); 974 } 975 } 976 977 /* 978 * If the block hasn't been seen before: 979 * (1) Mark it as having been seen, 980 * (2) Charge for the write, 981 * (3) Make sure it's on its vnode's correct block list. 982 */ 983 KASSERT(bp->b_vp == NULL || bp->b_objlock == bp->b_vp->v_interlock); 984 985 if (!ISSET(bp->b_oflags, BO_DELWRI)) { 986 mutex_enter(&bufcache_lock); 987 mutex_enter(bp->b_objlock); 988 SET(bp->b_oflags, BO_DELWRI); 989 curlwp->l_ru.ru_oublock++; 990 reassignbuf(bp, bp->b_vp); 991 mutex_exit(&bufcache_lock); 992 } else { 993 mutex_enter(bp->b_objlock); 994 } 995 /* Otherwise, the "write" is done, so mark and release the buffer. */ 996 CLR(bp->b_oflags, BO_DONE); 997 mutex_exit(bp->b_objlock); 998 999 brelse(bp, 0); 1000 } 1001 1002 /* 1003 * Asynchronous block write; just an asynchronous bwrite(). 1004 */ 1005 void 1006 bawrite(buf_t *bp) 1007 { 1008 1009 KASSERT(ISSET(bp->b_cflags, BC_BUSY)); 1010 KASSERT(bp->b_vp != NULL); 1011 1012 SET(bp->b_flags, B_ASYNC); 1013 VOP_BWRITE(bp->b_vp, bp); 1014 } 1015 1016 /* 1017 * Release a buffer on to the free lists. 1018 * Described in Bach (p. 46). 1019 */ 1020 void 1021 brelsel(buf_t *bp, int set) 1022 { 1023 struct bqueue *bufq; 1024 struct vnode *vp; 1025 1026 KASSERT(bp != NULL); 1027 KASSERT(mutex_owned(&bufcache_lock)); 1028 KASSERT(!cv_has_waiters(&bp->b_done)); 1029 KASSERT(bp->b_refcnt > 0); 1030 1031 SET(bp->b_cflags, set); 1032 1033 KASSERT(ISSET(bp->b_cflags, BC_BUSY)); 1034 KASSERT(bp->b_iodone == NULL); 1035 1036 /* Wake up any processes waiting for any buffer to become free. */ 1037 cv_signal(&needbuffer_cv); 1038 1039 /* Wake up any proceeses waiting for _this_ buffer to become free */ 1040 if (ISSET(bp->b_cflags, BC_WANTED)) 1041 CLR(bp->b_cflags, BC_WANTED|BC_AGE); 1042 1043 /* If it's clean clear the copy-on-write flag. */ 1044 if (ISSET(bp->b_flags, B_COWDONE)) { 1045 mutex_enter(bp->b_objlock); 1046 if (!ISSET(bp->b_oflags, BO_DELWRI)) 1047 CLR(bp->b_flags, B_COWDONE); 1048 mutex_exit(bp->b_objlock); 1049 } 1050 1051 /* 1052 * Determine which queue the buffer should be on, then put it there. 1053 */ 1054 1055 /* If it's locked, don't report an error; try again later. */ 1056 if (ISSET(bp->b_flags, B_LOCKED)) 1057 bp->b_error = 0; 1058 1059 /* If it's not cacheable, or an error, mark it invalid. */ 1060 if (ISSET(bp->b_cflags, BC_NOCACHE) || bp->b_error != 0) 1061 SET(bp->b_cflags, BC_INVAL); 1062 1063 if (ISSET(bp->b_cflags, BC_VFLUSH)) { 1064 /* 1065 * This is a delayed write buffer that was just flushed to 1066 * disk. It is still on the LRU queue. If it's become 1067 * invalid, then we need to move it to a different queue; 1068 * otherwise leave it in its current position. 1069 */ 1070 CLR(bp->b_cflags, BC_VFLUSH); 1071 if (!ISSET(bp->b_cflags, BC_INVAL|BC_AGE) && 1072 !ISSET(bp->b_flags, B_LOCKED) && bp->b_error == 0) { 1073 KDASSERT(checkfreelist(bp, &bufqueues[BQ_LRU], 1)); 1074 goto already_queued; 1075 } else { 1076 bremfree(bp); 1077 } 1078 } 1079 1080 KDASSERT(checkfreelist(bp, &bufqueues[BQ_AGE], 0)); 1081 KDASSERT(checkfreelist(bp, &bufqueues[BQ_LRU], 0)); 1082 KDASSERT(checkfreelist(bp, &bufqueues[BQ_LOCKED], 0)); 1083 1084 if ((bp->b_bufsize <= 0) || ISSET(bp->b_cflags, BC_INVAL)) { 1085 /* 1086 * If it's invalid or empty, dissociate it from its vnode 1087 * and put on the head of the appropriate queue. 1088 */ 1089 if (ISSET(bp->b_flags, B_LOCKED)) { 1090 if (wapbl_vphaswapbl(vp = bp->b_vp)) { 1091 struct mount *mp = wapbl_vptomp(vp); 1092 1093 KASSERT(bp->b_iodone 1094 != mp->mnt_wapbl_op->wo_wapbl_biodone); 1095 WAPBL_REMOVE_BUF(mp, bp); 1096 } 1097 } 1098 1099 mutex_enter(bp->b_objlock); 1100 CLR(bp->b_oflags, BO_DONE|BO_DELWRI); 1101 if ((vp = bp->b_vp) != NULL) { 1102 KASSERT(bp->b_objlock == vp->v_interlock); 1103 reassignbuf(bp, bp->b_vp); 1104 brelvp(bp); 1105 mutex_exit(vp->v_interlock); 1106 } else { 1107 KASSERT(bp->b_objlock == &buffer_lock); 1108 mutex_exit(bp->b_objlock); 1109 } 1110 1111 if (bp->b_bufsize <= 0) 1112 /* no data */ 1113 goto already_queued; 1114 else 1115 /* invalid data */ 1116 bufq = &bufqueues[BQ_AGE]; 1117 binsheadfree(bp, bufq); 1118 } else { 1119 /* 1120 * It has valid data. Put it on the end of the appropriate 1121 * queue, so that it'll stick around for as long as possible. 1122 * If buf is AGE, but has dependencies, must put it on last 1123 * bufqueue to be scanned, ie LRU. This protects against the 1124 * livelock where BQ_AGE only has buffers with dependencies, 1125 * and we thus never get to the dependent buffers in BQ_LRU. 1126 */ 1127 if (ISSET(bp->b_flags, B_LOCKED)) { 1128 /* locked in core */ 1129 bufq = &bufqueues[BQ_LOCKED]; 1130 } else if (!ISSET(bp->b_cflags, BC_AGE)) { 1131 /* valid data */ 1132 bufq = &bufqueues[BQ_LRU]; 1133 } else { 1134 /* stale but valid data */ 1135 bufq = &bufqueues[BQ_AGE]; 1136 } 1137 binstailfree(bp, bufq); 1138 } 1139 already_queued: 1140 /* Unlock the buffer. */ 1141 CLR(bp->b_cflags, BC_AGE|BC_BUSY|BC_NOCACHE); 1142 CLR(bp->b_flags, B_ASYNC); 1143 cv_broadcast(&bp->b_busy); 1144 1145 if (bp->b_bufsize <= 0) 1146 brele(bp); 1147 } 1148 1149 void 1150 brelse(buf_t *bp, int set) 1151 { 1152 1153 mutex_enter(&bufcache_lock); 1154 brelsel(bp, set); 1155 mutex_exit(&bufcache_lock); 1156 } 1157 1158 /* 1159 * Determine if a block is in the cache. 1160 * Just look on what would be its hash chain. If it's there, return 1161 * a pointer to it, unless it's marked invalid. If it's marked invalid, 1162 * we normally don't return the buffer, unless the caller explicitly 1163 * wants us to. 1164 */ 1165 buf_t * 1166 incore(struct vnode *vp, daddr_t blkno) 1167 { 1168 buf_t *bp; 1169 1170 KASSERT(mutex_owned(&bufcache_lock)); 1171 1172 /* Search hash chain */ 1173 LIST_FOREACH(bp, BUFHASH(vp, blkno), b_hash) { 1174 if (bp->b_lblkno == blkno && bp->b_vp == vp && 1175 !ISSET(bp->b_cflags, BC_INVAL)) { 1176 KASSERT(bp->b_objlock == vp->v_interlock); 1177 return (bp); 1178 } 1179 } 1180 1181 return (NULL); 1182 } 1183 1184 /* 1185 * Get a block of requested size that is associated with 1186 * a given vnode and block offset. If it is found in the 1187 * block cache, mark it as having been found, make it busy 1188 * and return it. Otherwise, return an empty block of the 1189 * correct size. It is up to the caller to insure that the 1190 * cached blocks be of the correct size. 1191 */ 1192 buf_t * 1193 getblk(struct vnode *vp, daddr_t blkno, int size, int slpflag, int slptimeo) 1194 { 1195 int err, preserve; 1196 buf_t *bp; 1197 1198 mutex_enter(&bufcache_lock); 1199 loop: 1200 bp = incore(vp, blkno); 1201 if (bp != NULL) { 1202 err = bbusy(bp, ((slpflag & PCATCH) != 0), slptimeo, NULL); 1203 if (err != 0) { 1204 if (err == EPASSTHROUGH) 1205 goto loop; 1206 mutex_exit(&bufcache_lock); 1207 return (NULL); 1208 } 1209 KASSERT(!cv_has_waiters(&bp->b_done)); 1210 #ifdef DIAGNOSTIC 1211 if (ISSET(bp->b_oflags, BO_DONE|BO_DELWRI) && 1212 bp->b_bcount < size && vp->v_type != VBLK) 1213 panic("getblk: block size invariant failed"); 1214 #endif 1215 bremfree(bp); 1216 preserve = 1; 1217 } else { 1218 if ((bp = getnewbuf(slpflag, slptimeo, 0)) == NULL) 1219 goto loop; 1220 1221 if (incore(vp, blkno) != NULL) { 1222 /* The block has come into memory in the meantime. */ 1223 brelsel(bp, 0); 1224 goto loop; 1225 } 1226 1227 LIST_INSERT_HEAD(BUFHASH(vp, blkno), bp, b_hash); 1228 bp->b_blkno = bp->b_lblkno = bp->b_rawblkno = blkno; 1229 mutex_enter(vp->v_interlock); 1230 bgetvp(vp, bp); 1231 mutex_exit(vp->v_interlock); 1232 preserve = 0; 1233 } 1234 mutex_exit(&bufcache_lock); 1235 1236 /* 1237 * LFS can't track total size of B_LOCKED buffer (locked_queue_bytes) 1238 * if we re-size buffers here. 1239 */ 1240 if (ISSET(bp->b_flags, B_LOCKED)) { 1241 KASSERT(bp->b_bufsize >= size); 1242 } else { 1243 if (allocbuf(bp, size, preserve)) { 1244 mutex_enter(&bufcache_lock); 1245 LIST_REMOVE(bp, b_hash); 1246 brelsel(bp, BC_INVAL); 1247 mutex_exit(&bufcache_lock); 1248 return NULL; 1249 } 1250 } 1251 BIO_SETPRIO(bp, BPRIO_DEFAULT); 1252 return (bp); 1253 } 1254 1255 /* 1256 * Get an empty, disassociated buffer of given size. 1257 */ 1258 buf_t * 1259 geteblk(int size) 1260 { 1261 buf_t *bp; 1262 int error __diagused; 1263 1264 mutex_enter(&bufcache_lock); 1265 while ((bp = getnewbuf(0, 0, 0)) == NULL) 1266 ; 1267 1268 SET(bp->b_cflags, BC_INVAL); 1269 LIST_INSERT_HEAD(&invalhash, bp, b_hash); 1270 mutex_exit(&bufcache_lock); 1271 BIO_SETPRIO(bp, BPRIO_DEFAULT); 1272 error = allocbuf(bp, size, 0); 1273 KASSERT(error == 0); 1274 return (bp); 1275 } 1276 1277 /* 1278 * Expand or contract the actual memory allocated to a buffer. 1279 * 1280 * If the buffer shrinks, data is lost, so it's up to the 1281 * caller to have written it out *first*; this routine will not 1282 * start a write. If the buffer grows, it's the callers 1283 * responsibility to fill out the buffer's additional contents. 1284 */ 1285 int 1286 allocbuf(buf_t *bp, int size, int preserve) 1287 { 1288 void *addr; 1289 vsize_t oldsize, desired_size; 1290 int oldcount; 1291 int delta; 1292 1293 desired_size = buf_roundsize(size); 1294 if (desired_size > MAXBSIZE) 1295 printf("allocbuf: buffer larger than MAXBSIZE requested"); 1296 1297 oldcount = bp->b_bcount; 1298 1299 bp->b_bcount = size; 1300 1301 oldsize = bp->b_bufsize; 1302 if (oldsize == desired_size) { 1303 /* 1304 * Do not short cut the WAPBL resize, as the buffer length 1305 * could still have changed and this would corrupt the 1306 * tracking of the transaction length. 1307 */ 1308 goto out; 1309 } 1310 1311 /* 1312 * If we want a buffer of a different size, re-allocate the 1313 * buffer's memory; copy old content only if needed. 1314 */ 1315 addr = buf_alloc(desired_size); 1316 if (addr == NULL) 1317 return ENOMEM; 1318 if (preserve) 1319 memcpy(addr, bp->b_data, MIN(oldsize,desired_size)); 1320 if (bp->b_data != NULL) 1321 buf_mrelease(bp->b_data, oldsize); 1322 bp->b_data = addr; 1323 bp->b_bufsize = desired_size; 1324 1325 /* 1326 * Update overall buffer memory counter (protected by bufcache_lock) 1327 */ 1328 delta = (long)desired_size - (long)oldsize; 1329 1330 mutex_enter(&bufcache_lock); 1331 if ((bufmem += delta) > bufmem_hiwater) { 1332 /* 1333 * Need to trim overall memory usage. 1334 */ 1335 while (buf_canrelease()) { 1336 if (curcpu()->ci_schedstate.spc_flags & 1337 SPCF_SHOULDYIELD) { 1338 mutex_exit(&bufcache_lock); 1339 preempt(); 1340 mutex_enter(&bufcache_lock); 1341 } 1342 if (buf_trim() == 0) 1343 break; 1344 } 1345 } 1346 mutex_exit(&bufcache_lock); 1347 1348 out: 1349 if (wapbl_vphaswapbl(bp->b_vp)) 1350 WAPBL_RESIZE_BUF(wapbl_vptomp(bp->b_vp), bp, oldsize, oldcount); 1351 1352 return 0; 1353 } 1354 1355 /* 1356 * Find a buffer which is available for use. 1357 * Select something from a free list. 1358 * Preference is to AGE list, then LRU list. 1359 * 1360 * Called with the buffer queues locked. 1361 * Return buffer locked. 1362 */ 1363 buf_t * 1364 getnewbuf(int slpflag, int slptimeo, int from_bufq) 1365 { 1366 buf_t *bp; 1367 struct vnode *vp; 1368 1369 start: 1370 KASSERT(mutex_owned(&bufcache_lock)); 1371 1372 /* 1373 * Get a new buffer from the pool. 1374 */ 1375 if (!from_bufq && buf_lotsfree()) { 1376 mutex_exit(&bufcache_lock); 1377 bp = pool_cache_get(buf_cache, PR_NOWAIT); 1378 if (bp != NULL) { 1379 memset((char *)bp, 0, sizeof(*bp)); 1380 buf_init(bp); 1381 SET(bp->b_cflags, BC_BUSY); /* mark buffer busy */ 1382 mutex_enter(&bufcache_lock); 1383 #if defined(DIAGNOSTIC) 1384 bp->b_freelistindex = -1; 1385 #endif /* defined(DIAGNOSTIC) */ 1386 return (bp); 1387 } 1388 mutex_enter(&bufcache_lock); 1389 } 1390 1391 KASSERT(mutex_owned(&bufcache_lock)); 1392 if ((bp = TAILQ_FIRST(&bufqueues[BQ_AGE].bq_queue)) != NULL || 1393 (bp = TAILQ_FIRST(&bufqueues[BQ_LRU].bq_queue)) != NULL) { 1394 KASSERT(!ISSET(bp->b_cflags, BC_BUSY) || ISSET(bp->b_cflags, BC_VFLUSH)); 1395 bremfree(bp); 1396 1397 /* Buffer is no longer on free lists. */ 1398 SET(bp->b_cflags, BC_BUSY); 1399 } else { 1400 /* 1401 * XXX: !from_bufq should be removed. 1402 */ 1403 if (!from_bufq || curlwp != uvm.pagedaemon_lwp) { 1404 /* wait for a free buffer of any kind */ 1405 if ((slpflag & PCATCH) != 0) 1406 (void)cv_timedwait_sig(&needbuffer_cv, 1407 &bufcache_lock, slptimeo); 1408 else 1409 (void)cv_timedwait(&needbuffer_cv, 1410 &bufcache_lock, slptimeo); 1411 } 1412 return (NULL); 1413 } 1414 1415 #ifdef DIAGNOSTIC 1416 if (bp->b_bufsize <= 0) 1417 panic("buffer %p: on queue but empty", bp); 1418 #endif 1419 1420 if (ISSET(bp->b_cflags, BC_VFLUSH)) { 1421 /* 1422 * This is a delayed write buffer being flushed to disk. Make 1423 * sure it gets aged out of the queue when it's finished, and 1424 * leave it off the LRU queue. 1425 */ 1426 CLR(bp->b_cflags, BC_VFLUSH); 1427 SET(bp->b_cflags, BC_AGE); 1428 goto start; 1429 } 1430 1431 KASSERT(ISSET(bp->b_cflags, BC_BUSY)); 1432 KASSERT(bp->b_refcnt > 0); 1433 KASSERT(!cv_has_waiters(&bp->b_done)); 1434 1435 /* 1436 * If buffer was a delayed write, start it and return NULL 1437 * (since we might sleep while starting the write). 1438 */ 1439 if (ISSET(bp->b_oflags, BO_DELWRI)) { 1440 /* 1441 * This buffer has gone through the LRU, so make sure it gets 1442 * reused ASAP. 1443 */ 1444 SET(bp->b_cflags, BC_AGE); 1445 mutex_exit(&bufcache_lock); 1446 bawrite(bp); 1447 mutex_enter(&bufcache_lock); 1448 return (NULL); 1449 } 1450 1451 vp = bp->b_vp; 1452 1453 /* clear out various other fields */ 1454 bp->b_cflags = BC_BUSY; 1455 bp->b_oflags = 0; 1456 bp->b_flags = 0; 1457 bp->b_dev = NODEV; 1458 bp->b_blkno = 0; 1459 bp->b_lblkno = 0; 1460 bp->b_rawblkno = 0; 1461 bp->b_iodone = 0; 1462 bp->b_error = 0; 1463 bp->b_resid = 0; 1464 bp->b_bcount = 0; 1465 1466 LIST_REMOVE(bp, b_hash); 1467 1468 /* Disassociate us from our vnode, if we had one... */ 1469 if (vp != NULL) { 1470 mutex_enter(vp->v_interlock); 1471 brelvp(bp); 1472 mutex_exit(vp->v_interlock); 1473 } 1474 1475 return (bp); 1476 } 1477 1478 /* 1479 * Attempt to free an aged buffer off the queues. 1480 * Called with queue lock held. 1481 * Returns the amount of buffer memory freed. 1482 */ 1483 static int 1484 buf_trim(void) 1485 { 1486 buf_t *bp; 1487 long size; 1488 1489 KASSERT(mutex_owned(&bufcache_lock)); 1490 1491 /* Instruct getnewbuf() to get buffers off the queues */ 1492 if ((bp = getnewbuf(PCATCH, 1, 1)) == NULL) 1493 return 0; 1494 1495 KASSERT((bp->b_cflags & BC_WANTED) == 0); 1496 size = bp->b_bufsize; 1497 bufmem -= size; 1498 if (size > 0) { 1499 buf_mrelease(bp->b_data, size); 1500 bp->b_bcount = bp->b_bufsize = 0; 1501 } 1502 /* brelse() will return the buffer to the global buffer pool */ 1503 brelsel(bp, 0); 1504 return size; 1505 } 1506 1507 int 1508 buf_drain(int n) 1509 { 1510 int size = 0, sz; 1511 1512 KASSERT(mutex_owned(&bufcache_lock)); 1513 1514 while (size < n && bufmem > bufmem_lowater) { 1515 sz = buf_trim(); 1516 if (sz <= 0) 1517 break; 1518 size += sz; 1519 } 1520 1521 return size; 1522 } 1523 1524 SDT_PROVIDER_DEFINE(io); 1525 1526 SDT_PROBE_DEFINE1(io, kernel, , wait__start, "struct buf *"/*bp*/); 1527 SDT_PROBE_DEFINE1(io, kernel, , wait__done, "struct buf *"/*bp*/); 1528 1529 /* 1530 * Wait for operations on the buffer to complete. 1531 * When they do, extract and return the I/O's error value. 1532 */ 1533 int 1534 biowait(buf_t *bp) 1535 { 1536 1537 BIOHIST_FUNC(__func__); 1538 1539 KASSERT(ISSET(bp->b_cflags, BC_BUSY)); 1540 KASSERT(bp->b_refcnt > 0); 1541 1542 SDT_PROBE1(io, kernel, , wait__start, bp); 1543 1544 mutex_enter(bp->b_objlock); 1545 1546 BIOHIST_CALLARGS(biohist, "bp=%#jx, oflags=0x%jx, ret_addr=%#jx", 1547 (uintptr_t)bp, bp->b_oflags, 1548 (uintptr_t)__builtin_return_address(0), 0); 1549 1550 while (!ISSET(bp->b_oflags, BO_DONE | BO_DELWRI)) { 1551 BIOHIST_LOG(biohist, "waiting bp=%#jx", (uintptr_t)bp, 0, 0, 0); 1552 cv_wait(&bp->b_done, bp->b_objlock); 1553 } 1554 mutex_exit(bp->b_objlock); 1555 1556 SDT_PROBE1(io, kernel, , wait__done, bp); 1557 1558 BIOHIST_LOG(biohist, "return %jd", bp->b_error, 0, 0, 0); 1559 1560 return bp->b_error; 1561 } 1562 1563 /* 1564 * Mark I/O complete on a buffer. 1565 * 1566 * If a callback has been requested, e.g. the pageout 1567 * daemon, do so. Otherwise, awaken waiting processes. 1568 * 1569 * [ Leffler, et al., says on p.247: 1570 * "This routine wakes up the blocked process, frees the buffer 1571 * for an asynchronous write, or, for a request by the pagedaemon 1572 * process, invokes a procedure specified in the buffer structure" ] 1573 * 1574 * In real life, the pagedaemon (or other system processes) wants 1575 * to do async stuff too, and doesn't want the buffer brelse()'d. 1576 * (for swap pager, that puts swap buffers on the free lists (!!!), 1577 * for the vn device, that puts allocated buffers on the free lists!) 1578 */ 1579 void 1580 biodone(buf_t *bp) 1581 { 1582 int s; 1583 1584 BIOHIST_FUNC(__func__); 1585 1586 KASSERT(!ISSET(bp->b_oflags, BO_DONE)); 1587 1588 if (cpu_intr_p()) { 1589 /* From interrupt mode: defer to a soft interrupt. */ 1590 s = splvm(); 1591 TAILQ_INSERT_TAIL(&curcpu()->ci_data.cpu_biodone, bp, b_actq); 1592 1593 BIOHIST_CALLARGS(biohist, "bp=%#jx, softint scheduled", 1594 (uintptr_t)bp, 0, 0, 0); 1595 softint_schedule(biodone_sih); 1596 splx(s); 1597 } else { 1598 /* Process now - the buffer may be freed soon. */ 1599 biodone2(bp); 1600 } 1601 } 1602 1603 SDT_PROBE_DEFINE1(io, kernel, , done, "struct buf *"/*bp*/); 1604 1605 static void 1606 biodone2(buf_t *bp) 1607 { 1608 void (*callout)(buf_t *); 1609 1610 SDT_PROBE1(io, kernel, ,done, bp); 1611 1612 BIOHIST_FUNC(__func__); 1613 BIOHIST_CALLARGS(biohist, "bp=%#jx", (uintptr_t)bp, 0, 0, 0); 1614 1615 mutex_enter(bp->b_objlock); 1616 /* Note that the transfer is done. */ 1617 if (ISSET(bp->b_oflags, BO_DONE)) 1618 panic("biodone2 already"); 1619 CLR(bp->b_flags, B_COWDONE); 1620 SET(bp->b_oflags, BO_DONE); 1621 BIO_SETPRIO(bp, BPRIO_DEFAULT); 1622 1623 /* Wake up waiting writers. */ 1624 if (!ISSET(bp->b_flags, B_READ)) 1625 vwakeup(bp); 1626 1627 if ((callout = bp->b_iodone) != NULL) { 1628 BIOHIST_LOG(biohist, "callout %#jx", (uintptr_t)callout, 1629 0, 0, 0); 1630 1631 /* Note callout done, then call out. */ 1632 KASSERT(!cv_has_waiters(&bp->b_done)); 1633 KERNEL_LOCK(1, NULL); /* XXXSMP */ 1634 bp->b_iodone = NULL; 1635 mutex_exit(bp->b_objlock); 1636 (*callout)(bp); 1637 KERNEL_UNLOCK_ONE(NULL); /* XXXSMP */ 1638 } else if (ISSET(bp->b_flags, B_ASYNC)) { 1639 /* If async, release. */ 1640 BIOHIST_LOG(biohist, "async", 0, 0, 0, 0); 1641 KASSERT(!cv_has_waiters(&bp->b_done)); 1642 mutex_exit(bp->b_objlock); 1643 brelse(bp, 0); 1644 } else { 1645 /* Otherwise just wake up waiters in biowait(). */ 1646 BIOHIST_LOG(biohist, "wake-up", 0, 0, 0, 0); 1647 cv_broadcast(&bp->b_done); 1648 mutex_exit(bp->b_objlock); 1649 } 1650 } 1651 1652 static void 1653 biointr(void *cookie) 1654 { 1655 struct cpu_info *ci; 1656 buf_t *bp; 1657 int s; 1658 1659 BIOHIST_FUNC(__func__); BIOHIST_CALLED(biohist); 1660 1661 ci = curcpu(); 1662 1663 s = splvm(); 1664 while (!TAILQ_EMPTY(&ci->ci_data.cpu_biodone)) { 1665 KASSERT(curcpu() == ci); 1666 1667 bp = TAILQ_FIRST(&ci->ci_data.cpu_biodone); 1668 TAILQ_REMOVE(&ci->ci_data.cpu_biodone, bp, b_actq); 1669 splx(s); 1670 1671 BIOHIST_LOG(biohist, "bp=%#jx", (uintptr_t)bp, 0, 0, 0); 1672 biodone2(bp); 1673 1674 s = splvm(); 1675 } 1676 splx(s); 1677 } 1678 1679 /* 1680 * Wait for all buffers to complete I/O 1681 * Return the number of "stuck" buffers. 1682 */ 1683 int 1684 buf_syncwait(void) 1685 { 1686 buf_t *bp; 1687 int iter, nbusy, nbusy_prev = 0, ihash; 1688 1689 BIOHIST_FUNC(__func__); BIOHIST_CALLED(biohist); 1690 1691 for (iter = 0; iter < 20;) { 1692 mutex_enter(&bufcache_lock); 1693 nbusy = 0; 1694 for (ihash = 0; ihash < bufhash+1; ihash++) { 1695 LIST_FOREACH(bp, &bufhashtbl[ihash], b_hash) { 1696 if ((bp->b_cflags & (BC_BUSY|BC_INVAL)) == BC_BUSY) 1697 nbusy += ((bp->b_flags & B_READ) == 0); 1698 } 1699 } 1700 mutex_exit(&bufcache_lock); 1701 1702 if (nbusy == 0) 1703 break; 1704 if (nbusy_prev == 0) 1705 nbusy_prev = nbusy; 1706 printf("%d ", nbusy); 1707 kpause("bflush", false, MAX(1, hz / 25 * iter), NULL); 1708 if (nbusy >= nbusy_prev) /* we didn't flush anything */ 1709 iter++; 1710 else 1711 nbusy_prev = nbusy; 1712 } 1713 1714 if (nbusy) { 1715 #if defined(DEBUG) || defined(DEBUG_HALT_BUSY) 1716 printf("giving up\nPrinting vnodes for busy buffers\n"); 1717 for (ihash = 0; ihash < bufhash+1; ihash++) { 1718 LIST_FOREACH(bp, &bufhashtbl[ihash], b_hash) { 1719 if ((bp->b_cflags & (BC_BUSY|BC_INVAL)) == BC_BUSY && 1720 (bp->b_flags & B_READ) == 0) 1721 vprint(NULL, bp->b_vp); 1722 } 1723 } 1724 #endif 1725 } 1726 1727 return nbusy; 1728 } 1729 1730 static void 1731 sysctl_fillbuf(buf_t *i, struct buf_sysctl *o) 1732 { 1733 1734 o->b_flags = i->b_flags | i->b_cflags | i->b_oflags; 1735 o->b_error = i->b_error; 1736 o->b_prio = i->b_prio; 1737 o->b_dev = i->b_dev; 1738 o->b_bufsize = i->b_bufsize; 1739 o->b_bcount = i->b_bcount; 1740 o->b_resid = i->b_resid; 1741 o->b_addr = PTRTOUINT64(i->b_data); 1742 o->b_blkno = i->b_blkno; 1743 o->b_rawblkno = i->b_rawblkno; 1744 o->b_iodone = PTRTOUINT64(i->b_iodone); 1745 o->b_proc = PTRTOUINT64(i->b_proc); 1746 o->b_vp = PTRTOUINT64(i->b_vp); 1747 o->b_saveaddr = PTRTOUINT64(i->b_saveaddr); 1748 o->b_lblkno = i->b_lblkno; 1749 } 1750 1751 #define KERN_BUFSLOP 20 1752 static int 1753 sysctl_dobuf(SYSCTLFN_ARGS) 1754 { 1755 buf_t *bp; 1756 struct buf_sysctl bs; 1757 struct bqueue *bq; 1758 char *dp; 1759 u_int i, op, arg; 1760 size_t len, needed, elem_size, out_size; 1761 int error, elem_count, retries; 1762 1763 if (namelen == 1 && name[0] == CTL_QUERY) 1764 return (sysctl_query(SYSCTLFN_CALL(rnode))); 1765 1766 if (namelen != 4) 1767 return (EINVAL); 1768 1769 retries = 100; 1770 retry: 1771 dp = oldp; 1772 len = (oldp != NULL) ? *oldlenp : 0; 1773 op = name[0]; 1774 arg = name[1]; 1775 elem_size = name[2]; 1776 elem_count = name[3]; 1777 out_size = MIN(sizeof(bs), elem_size); 1778 1779 /* 1780 * at the moment, these are just "placeholders" to make the 1781 * API for retrieving kern.buf data more extensible in the 1782 * future. 1783 * 1784 * XXX kern.buf currently has "netbsd32" issues. hopefully 1785 * these will be resolved at a later point. 1786 */ 1787 if (op != KERN_BUF_ALL || arg != KERN_BUF_ALL || 1788 elem_size < 1 || elem_count < 0) 1789 return (EINVAL); 1790 1791 error = 0; 1792 needed = 0; 1793 sysctl_unlock(); 1794 mutex_enter(&bufcache_lock); 1795 for (i = 0; i < BQUEUES; i++) { 1796 bq = &bufqueues[i]; 1797 TAILQ_FOREACH(bp, &bq->bq_queue, b_freelist) { 1798 bq->bq_marker = bp; 1799 if (len >= elem_size && elem_count > 0) { 1800 sysctl_fillbuf(bp, &bs); 1801 mutex_exit(&bufcache_lock); 1802 error = copyout(&bs, dp, out_size); 1803 mutex_enter(&bufcache_lock); 1804 if (error) 1805 break; 1806 if (bq->bq_marker != bp) { 1807 /* 1808 * This sysctl node is only for 1809 * statistics. Retry; if the 1810 * queue keeps changing, then 1811 * bail out. 1812 */ 1813 if (retries-- == 0) { 1814 error = EAGAIN; 1815 break; 1816 } 1817 mutex_exit(&bufcache_lock); 1818 sysctl_relock(); 1819 goto retry; 1820 } 1821 dp += elem_size; 1822 len -= elem_size; 1823 } 1824 needed += elem_size; 1825 if (elem_count > 0 && elem_count != INT_MAX) 1826 elem_count--; 1827 } 1828 if (error != 0) 1829 break; 1830 } 1831 mutex_exit(&bufcache_lock); 1832 sysctl_relock(); 1833 1834 *oldlenp = needed; 1835 if (oldp == NULL) 1836 *oldlenp += KERN_BUFSLOP * sizeof(buf_t); 1837 1838 return (error); 1839 } 1840 1841 static int 1842 sysctl_bufvm_update(SYSCTLFN_ARGS) 1843 { 1844 int error, rv; 1845 struct sysctlnode node; 1846 unsigned int temp_bufcache; 1847 unsigned long temp_water; 1848 1849 /* Take a copy of the supplied node and its data */ 1850 node = *rnode; 1851 if (node.sysctl_data == &bufcache) { 1852 node.sysctl_data = &temp_bufcache; 1853 temp_bufcache = *(unsigned int *)rnode->sysctl_data; 1854 } else { 1855 node.sysctl_data = &temp_water; 1856 temp_water = *(unsigned long *)rnode->sysctl_data; 1857 } 1858 1859 /* Update the copy */ 1860 error = sysctl_lookup(SYSCTLFN_CALL(&node)); 1861 if (error || newp == NULL) 1862 return (error); 1863 1864 if (rnode->sysctl_data == &bufcache) { 1865 if (temp_bufcache > 100) 1866 return (EINVAL); 1867 bufcache = temp_bufcache; 1868 buf_setwm(); 1869 } else if (rnode->sysctl_data == &bufmem_lowater) { 1870 if (bufmem_hiwater - temp_water < 16) 1871 return (EINVAL); 1872 bufmem_lowater = temp_water; 1873 } else if (rnode->sysctl_data == &bufmem_hiwater) { 1874 if (temp_water - bufmem_lowater < 16) 1875 return (EINVAL); 1876 bufmem_hiwater = temp_water; 1877 } else 1878 return (EINVAL); 1879 1880 /* Drain until below new high water mark */ 1881 sysctl_unlock(); 1882 mutex_enter(&bufcache_lock); 1883 while (bufmem > bufmem_hiwater) { 1884 rv = buf_drain((bufmem - bufmem_hiwater) / (2 * 1024)); 1885 if (rv <= 0) 1886 break; 1887 } 1888 mutex_exit(&bufcache_lock); 1889 sysctl_relock(); 1890 1891 return 0; 1892 } 1893 1894 static struct sysctllog *vfsbio_sysctllog; 1895 1896 static void 1897 sysctl_kern_buf_setup(void) 1898 { 1899 1900 sysctl_createv(&vfsbio_sysctllog, 0, NULL, NULL, 1901 CTLFLAG_PERMANENT, 1902 CTLTYPE_NODE, "buf", 1903 SYSCTL_DESCR("Kernel buffer cache information"), 1904 sysctl_dobuf, 0, NULL, 0, 1905 CTL_KERN, KERN_BUF, CTL_EOL); 1906 } 1907 1908 static void 1909 sysctl_vm_buf_setup(void) 1910 { 1911 1912 sysctl_createv(&vfsbio_sysctllog, 0, NULL, NULL, 1913 CTLFLAG_PERMANENT|CTLFLAG_READWRITE, 1914 CTLTYPE_INT, "bufcache", 1915 SYSCTL_DESCR("Percentage of physical memory to use for " 1916 "buffer cache"), 1917 sysctl_bufvm_update, 0, &bufcache, 0, 1918 CTL_VM, CTL_CREATE, CTL_EOL); 1919 sysctl_createv(&vfsbio_sysctllog, 0, NULL, NULL, 1920 CTLFLAG_PERMANENT|CTLFLAG_READONLY, 1921 CTLTYPE_LONG, "bufmem", 1922 SYSCTL_DESCR("Amount of kernel memory used by buffer " 1923 "cache"), 1924 NULL, 0, &bufmem, 0, 1925 CTL_VM, CTL_CREATE, CTL_EOL); 1926 sysctl_createv(&vfsbio_sysctllog, 0, NULL, NULL, 1927 CTLFLAG_PERMANENT|CTLFLAG_READWRITE, 1928 CTLTYPE_LONG, "bufmem_lowater", 1929 SYSCTL_DESCR("Minimum amount of kernel memory to " 1930 "reserve for buffer cache"), 1931 sysctl_bufvm_update, 0, &bufmem_lowater, 0, 1932 CTL_VM, CTL_CREATE, CTL_EOL); 1933 sysctl_createv(&vfsbio_sysctllog, 0, NULL, NULL, 1934 CTLFLAG_PERMANENT|CTLFLAG_READWRITE, 1935 CTLTYPE_LONG, "bufmem_hiwater", 1936 SYSCTL_DESCR("Maximum amount of kernel memory to use " 1937 "for buffer cache"), 1938 sysctl_bufvm_update, 0, &bufmem_hiwater, 0, 1939 CTL_VM, CTL_CREATE, CTL_EOL); 1940 } 1941 1942 #ifdef DEBUG 1943 /* 1944 * Print out statistics on the current allocation of the buffer pool. 1945 * Can be enabled to print out on every ``sync'' by setting "syncprt" 1946 * in vfs_syscalls.c using sysctl. 1947 */ 1948 void 1949 vfs_bufstats(void) 1950 { 1951 int i, j, count; 1952 buf_t *bp; 1953 struct bqueue *dp; 1954 int counts[MAXBSIZE / MIN_PAGE_SIZE + 1]; 1955 static const char *bname[BQUEUES] = { "LOCKED", "LRU", "AGE" }; 1956 1957 for (dp = bufqueues, i = 0; dp < &bufqueues[BQUEUES]; dp++, i++) { 1958 count = 0; 1959 memset(counts, 0, sizeof(counts)); 1960 TAILQ_FOREACH(bp, &dp->bq_queue, b_freelist) { 1961 counts[bp->b_bufsize / PAGE_SIZE]++; 1962 count++; 1963 } 1964 printf("%s: total-%d", bname[i], count); 1965 for (j = 0; j <= MAXBSIZE / PAGE_SIZE; j++) 1966 if (counts[j] != 0) 1967 printf(", %d-%d", j * PAGE_SIZE, counts[j]); 1968 printf("\n"); 1969 } 1970 } 1971 #endif /* DEBUG */ 1972 1973 /* ------------------------------ */ 1974 1975 buf_t * 1976 getiobuf(struct vnode *vp, bool waitok) 1977 { 1978 buf_t *bp; 1979 1980 bp = pool_cache_get(bufio_cache, (waitok ? PR_WAITOK : PR_NOWAIT)); 1981 if (bp == NULL) 1982 return bp; 1983 1984 buf_init(bp); 1985 1986 if ((bp->b_vp = vp) != NULL) { 1987 bp->b_objlock = vp->v_interlock; 1988 } else { 1989 KASSERT(bp->b_objlock == &buffer_lock); 1990 } 1991 1992 return bp; 1993 } 1994 1995 void 1996 putiobuf(buf_t *bp) 1997 { 1998 1999 buf_destroy(bp); 2000 pool_cache_put(bufio_cache, bp); 2001 } 2002 2003 /* 2004 * nestiobuf_iodone: b_iodone callback for nested buffers. 2005 */ 2006 2007 void 2008 nestiobuf_iodone(buf_t *bp) 2009 { 2010 buf_t *mbp = bp->b_private; 2011 int error; 2012 int donebytes; 2013 2014 KASSERT(bp->b_bcount <= bp->b_bufsize); 2015 KASSERT(mbp != bp); 2016 2017 error = bp->b_error; 2018 if (bp->b_error == 0 && 2019 (bp->b_bcount < bp->b_bufsize || bp->b_resid > 0)) { 2020 /* 2021 * Not all got transfered, raise an error. We have no way to 2022 * propagate these conditions to mbp. 2023 */ 2024 error = EIO; 2025 } 2026 2027 donebytes = bp->b_bufsize; 2028 2029 putiobuf(bp); 2030 nestiobuf_done(mbp, donebytes, error); 2031 } 2032 2033 /* 2034 * nestiobuf_setup: setup a "nested" buffer. 2035 * 2036 * => 'mbp' is a "master" buffer which is being divided into sub pieces. 2037 * => 'bp' should be a buffer allocated by getiobuf. 2038 * => 'offset' is a byte offset in the master buffer. 2039 * => 'size' is a size in bytes of this nested buffer. 2040 */ 2041 2042 void 2043 nestiobuf_setup(buf_t *mbp, buf_t *bp, int offset, size_t size) 2044 { 2045 const int b_pass = mbp->b_flags & (B_READ|B_MEDIA_FLAGS); 2046 struct vnode *vp = mbp->b_vp; 2047 2048 KASSERT(mbp->b_bcount >= offset + size); 2049 bp->b_vp = vp; 2050 bp->b_dev = mbp->b_dev; 2051 bp->b_objlock = mbp->b_objlock; 2052 bp->b_cflags = BC_BUSY; 2053 bp->b_flags = B_ASYNC | b_pass; 2054 bp->b_iodone = nestiobuf_iodone; 2055 bp->b_data = (char *)mbp->b_data + offset; 2056 bp->b_resid = bp->b_bcount = size; 2057 bp->b_bufsize = bp->b_bcount; 2058 bp->b_private = mbp; 2059 BIO_COPYPRIO(bp, mbp); 2060 if (BUF_ISWRITE(bp) && vp != NULL) { 2061 mutex_enter(vp->v_interlock); 2062 vp->v_numoutput++; 2063 mutex_exit(vp->v_interlock); 2064 } 2065 } 2066 2067 /* 2068 * nestiobuf_done: propagate completion to the master buffer. 2069 * 2070 * => 'donebytes' specifies how many bytes in the 'mbp' is completed. 2071 * => 'error' is an errno(2) that 'donebytes' has been completed with. 2072 */ 2073 2074 void 2075 nestiobuf_done(buf_t *mbp, int donebytes, int error) 2076 { 2077 2078 if (donebytes == 0) { 2079 return; 2080 } 2081 mutex_enter(mbp->b_objlock); 2082 KASSERT(mbp->b_resid >= donebytes); 2083 mbp->b_resid -= donebytes; 2084 if (error) 2085 mbp->b_error = error; 2086 if (mbp->b_resid == 0) { 2087 if (mbp->b_error) 2088 mbp->b_resid = mbp->b_bcount; 2089 mutex_exit(mbp->b_objlock); 2090 biodone(mbp); 2091 } else 2092 mutex_exit(mbp->b_objlock); 2093 } 2094 2095 void 2096 buf_init(buf_t *bp) 2097 { 2098 2099 cv_init(&bp->b_busy, "biolock"); 2100 cv_init(&bp->b_done, "biowait"); 2101 bp->b_dev = NODEV; 2102 bp->b_error = 0; 2103 bp->b_flags = 0; 2104 bp->b_cflags = 0; 2105 bp->b_oflags = 0; 2106 bp->b_objlock = &buffer_lock; 2107 bp->b_iodone = NULL; 2108 bp->b_refcnt = 1; 2109 bp->b_dev = NODEV; 2110 bp->b_vnbufs.le_next = NOLIST; 2111 BIO_SETPRIO(bp, BPRIO_DEFAULT); 2112 } 2113 2114 void 2115 buf_destroy(buf_t *bp) 2116 { 2117 2118 cv_destroy(&bp->b_done); 2119 cv_destroy(&bp->b_busy); 2120 } 2121 2122 int 2123 bbusy(buf_t *bp, bool intr, int timo, kmutex_t *interlock) 2124 { 2125 int error; 2126 2127 KASSERT(mutex_owned(&bufcache_lock)); 2128 2129 if ((bp->b_cflags & BC_BUSY) != 0) { 2130 if (curlwp == uvm.pagedaemon_lwp) 2131 return EDEADLK; 2132 bp->b_cflags |= BC_WANTED; 2133 bref(bp); 2134 if (interlock != NULL) 2135 mutex_exit(interlock); 2136 if (intr) { 2137 error = cv_timedwait_sig(&bp->b_busy, &bufcache_lock, 2138 timo); 2139 } else { 2140 error = cv_timedwait(&bp->b_busy, &bufcache_lock, 2141 timo); 2142 } 2143 brele(bp); 2144 if (interlock != NULL) 2145 mutex_enter(interlock); 2146 if (error != 0) 2147 return error; 2148 return EPASSTHROUGH; 2149 } 2150 bp->b_cflags |= BC_BUSY; 2151 2152 return 0; 2153 } 2154 2155 /* 2156 * Nothing outside this file should really need to know about nbuf, 2157 * but a few things still want to read it, so give them a way to do that. 2158 */ 2159 int 2160 buf_nbuf(void) 2161 { 2162 2163 return nbuf; 2164 } 2165