1 /* $NetBSD: vfs_bio.c,v 1.142 2005/02/26 21:34:56 perry Exp $ */ 2 3 /*- 4 * Copyright (c) 1982, 1986, 1989, 1993 5 * The Regents of the University of California. All rights reserved. 6 * (c) UNIX System Laboratories, Inc. 7 * All or some portions of this file are derived from material licensed 8 * to the University of California by American Telephone and Telegraph 9 * Co. or Unix System Laboratories, Inc. and are reproduced herein with 10 * the permission of UNIX System Laboratories, Inc. 11 * 12 * Redistribution and use in source and binary forms, with or without 13 * modification, are permitted provided that the following conditions 14 * are met: 15 * 1. Redistributions of source code must retain the above copyright 16 * notice, this list of conditions and the following disclaimer. 17 * 2. Redistributions in binary form must reproduce the above copyright 18 * notice, this list of conditions and the following disclaimer in the 19 * documentation and/or other materials provided with the distribution. 20 * 3. Neither the name of the University nor the names of its contributors 21 * may be used to endorse or promote products derived from this software 22 * without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34 * SUCH DAMAGE. 35 * 36 * @(#)vfs_bio.c 8.6 (Berkeley) 1/11/94 37 */ 38 39 /*- 40 * Copyright (c) 1994 Christopher G. Demetriou 41 * 42 * Redistribution and use in source and binary forms, with or without 43 * modification, are permitted provided that the following conditions 44 * are met: 45 * 1. Redistributions of source code must retain the above copyright 46 * notice, this list of conditions and the following disclaimer. 47 * 2. Redistributions in binary form must reproduce the above copyright 48 * notice, this list of conditions and the following disclaimer in the 49 * documentation and/or other materials provided with the distribution. 50 * 3. All advertising materials mentioning features or use of this software 51 * must display the following acknowledgement: 52 * This product includes software developed by the University of 53 * California, Berkeley and its contributors. 54 * 4. Neither the name of the University nor the names of its contributors 55 * may be used to endorse or promote products derived from this software 56 * without specific prior written permission. 57 * 58 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 59 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 60 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 61 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 62 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 63 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 64 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 65 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 66 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 67 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 68 * SUCH DAMAGE. 69 * 70 * @(#)vfs_bio.c 8.6 (Berkeley) 1/11/94 71 */ 72 73 /* 74 * Some references: 75 * Bach: The Design of the UNIX Operating System (Prentice Hall, 1986) 76 * Leffler, et al.: The Design and Implementation of the 4.3BSD 77 * UNIX Operating System (Addison Welley, 1989) 78 */ 79 80 #include "opt_bufcache.h" 81 #include "opt_softdep.h" 82 83 #include <sys/cdefs.h> 84 __KERNEL_RCSID(0, "$NetBSD: vfs_bio.c,v 1.142 2005/02/26 21:34:56 perry Exp $"); 85 86 #include <sys/param.h> 87 #include <sys/systm.h> 88 #include <sys/kernel.h> 89 #include <sys/proc.h> 90 #include <sys/buf.h> 91 #include <sys/vnode.h> 92 #include <sys/mount.h> 93 #include <sys/malloc.h> 94 #include <sys/resourcevar.h> 95 #include <sys/sysctl.h> 96 #include <sys/conf.h> 97 98 #include <uvm/uvm.h> 99 100 #include <miscfs/specfs/specdev.h> 101 102 #ifndef BUFPAGES 103 # define BUFPAGES 0 104 #endif 105 106 #ifdef BUFCACHE 107 # if (BUFCACHE < 5) || (BUFCACHE > 95) 108 # error BUFCACHE is not between 5 and 95 109 # endif 110 #else 111 # define BUFCACHE 15 112 #endif 113 114 u_int nbuf; /* XXX - for softdep_lockedbufs */ 115 u_int bufpages = BUFPAGES; /* optional hardwired count */ 116 u_int bufcache = BUFCACHE; /* max % of RAM to use for buffer cache */ 117 118 /* Function prototypes */ 119 struct bqueue; 120 121 static void buf_setwm(void); 122 static int buf_trim(void); 123 static void *bufpool_page_alloc(struct pool *, int); 124 static void bufpool_page_free(struct pool *, void *); 125 static __inline struct buf *bio_doread(struct vnode *, daddr_t, int, 126 struct ucred *, int); 127 static int buf_lotsfree(void); 128 static int buf_canrelease(void); 129 static __inline u_long buf_mempoolidx(u_long); 130 static __inline u_long buf_roundsize(u_long); 131 static __inline caddr_t buf_malloc(size_t); 132 static void buf_mrelease(caddr_t, size_t); 133 static __inline void binsheadfree(struct buf *, struct bqueue *); 134 static __inline void binstailfree(struct buf *, struct bqueue *); 135 int count_lock_queue(void); /* XXX */ 136 #ifdef DEBUG 137 static int checkfreelist(struct buf *, struct bqueue *); 138 #endif 139 140 /* Macros to clear/set/test flags. */ 141 #define SET(t, f) (t) |= (f) 142 #define CLR(t, f) (t) &= ~(f) 143 #define ISSET(t, f) ((t) & (f)) 144 145 /* 146 * Definitions for the buffer hash lists. 147 */ 148 #define BUFHASH(dvp, lbn) \ 149 (&bufhashtbl[(((long)(dvp) >> 8) + (int)(lbn)) & bufhash]) 150 LIST_HEAD(bufhashhdr, buf) *bufhashtbl, invalhash; 151 u_long bufhash; 152 #if !defined(SOFTDEP) || !defined(FFS) 153 struct bio_ops bioops; /* I/O operation notification */ 154 #endif 155 156 /* 157 * Insq/Remq for the buffer hash lists. 158 */ 159 #define binshash(bp, dp) LIST_INSERT_HEAD(dp, bp, b_hash) 160 #define bremhash(bp) LIST_REMOVE(bp, b_hash) 161 162 /* 163 * Definitions for the buffer free lists. 164 */ 165 #define BQUEUES 3 /* number of free buffer queues */ 166 167 #define BQ_LOCKED 0 /* super-blocks &c */ 168 #define BQ_LRU 1 /* lru, useful buffers */ 169 #define BQ_AGE 2 /* rubbish */ 170 171 struct bqueue { 172 TAILQ_HEAD(, buf) bq_queue; 173 uint64_t bq_bytes; 174 } bufqueues[BQUEUES]; 175 int needbuffer; 176 177 /* 178 * Buffer queue lock. 179 * Take this lock first if also taking some buffer's b_interlock. 180 */ 181 struct simplelock bqueue_slock = SIMPLELOCK_INITIALIZER; 182 183 /* 184 * Buffer pool for I/O buffers. 185 */ 186 struct pool bufpool; 187 188 /* XXX - somewhat gross.. */ 189 #if MAXBSIZE == 0x2000 190 #define NMEMPOOLS 4 191 #elif MAXBSIZE == 0x4000 192 #define NMEMPOOLS 5 193 #elif MAXBSIZE == 0x8000 194 #define NMEMPOOLS 6 195 #else 196 #define NMEMPOOLS 7 197 #endif 198 199 #define MEMPOOL_INDEX_OFFSET 10 /* smallest pool is 1k */ 200 #if (1 << (NMEMPOOLS + MEMPOOL_INDEX_OFFSET - 1)) != MAXBSIZE 201 #error update vfs_bio buffer memory parameters 202 #endif 203 204 /* Buffer memory pools */ 205 static struct pool bmempools[NMEMPOOLS]; 206 207 struct vm_map *buf_map; 208 209 /* 210 * Buffer memory pool allocator. 211 */ 212 static void * 213 bufpool_page_alloc(struct pool *pp, int flags) 214 { 215 216 return (void *)uvm_km_kmemalloc1(buf_map, 217 uvm.kernel_object, MAXBSIZE, MAXBSIZE, UVM_UNKNOWN_OFFSET, 218 (flags & PR_WAITOK) ? 0 : UVM_KMF_NOWAIT | UVM_KMF_TRYLOCK); 219 } 220 221 static void 222 bufpool_page_free(struct pool *pp, void *v) 223 { 224 uvm_km_free(buf_map, (vaddr_t)v, MAXBSIZE); 225 } 226 227 static struct pool_allocator bufmempool_allocator = { 228 bufpool_page_alloc, bufpool_page_free, MAXBSIZE, 229 }; 230 231 /* Buffer memory management variables */ 232 u_long bufmem_valimit; 233 u_long bufmem_hiwater; 234 u_long bufmem_lowater; 235 u_long bufmem; 236 237 /* 238 * MD code can call this to set a hard limit on the amount 239 * of virtual memory used by the buffer cache. 240 */ 241 int 242 buf_setvalimit(vsize_t sz) 243 { 244 245 /* We need to accommodate at least NMEMPOOLS of MAXBSIZE each */ 246 if (sz < NMEMPOOLS * MAXBSIZE) 247 return EINVAL; 248 249 bufmem_valimit = sz; 250 return 0; 251 } 252 253 static void 254 buf_setwm(void) 255 { 256 257 bufmem_hiwater = buf_memcalc(); 258 /* lowater is approx. 2% of memory (with bufcache = 15) */ 259 #define BUFMEM_WMSHIFT 3 260 #define BUFMEM_HIWMMIN (64 * 1024 << BUFMEM_WMSHIFT) 261 if (bufmem_hiwater < BUFMEM_HIWMMIN) 262 /* Ensure a reasonable minimum value */ 263 bufmem_hiwater = BUFMEM_HIWMMIN; 264 bufmem_lowater = bufmem_hiwater >> BUFMEM_WMSHIFT; 265 } 266 267 #ifdef DEBUG 268 int debug_verify_freelist = 0; 269 static int 270 checkfreelist(struct buf *bp, struct bqueue *dp) 271 { 272 struct buf *b; 273 274 TAILQ_FOREACH(b, &dp->bq_queue, b_freelist) { 275 if (b == bp) 276 return 1; 277 } 278 return 0; 279 } 280 #endif 281 282 /* 283 * Insq/Remq for the buffer hash lists. 284 * Call with buffer queue locked. 285 */ 286 static __inline void 287 binsheadfree(struct buf *bp, struct bqueue *dp) 288 { 289 290 KASSERT(bp->b_freelistindex == -1); 291 TAILQ_INSERT_HEAD(&dp->bq_queue, bp, b_freelist); 292 dp->bq_bytes += bp->b_bufsize; 293 bp->b_freelistindex = dp - bufqueues; 294 } 295 296 static __inline void 297 binstailfree(struct buf *bp, struct bqueue *dp) 298 { 299 300 KASSERT(bp->b_freelistindex == -1); 301 TAILQ_INSERT_TAIL(&dp->bq_queue, bp, b_freelist); 302 dp->bq_bytes += bp->b_bufsize; 303 bp->b_freelistindex = dp - bufqueues; 304 } 305 306 void 307 bremfree(struct buf *bp) 308 { 309 struct bqueue *dp; 310 int bqidx = bp->b_freelistindex; 311 312 LOCK_ASSERT(simple_lock_held(&bqueue_slock)); 313 314 KASSERT(bqidx != -1); 315 dp = &bufqueues[bqidx]; 316 KDASSERT(!debug_verify_freelist || checkfreelist(bp, dp)); 317 KASSERT(dp->bq_bytes >= bp->b_bufsize); 318 TAILQ_REMOVE(&dp->bq_queue, bp, b_freelist); 319 dp->bq_bytes -= bp->b_bufsize; 320 #if defined(DIAGNOSTIC) 321 bp->b_freelistindex = -1; 322 #endif /* defined(DIAGNOSTIC) */ 323 } 324 325 u_long 326 buf_memcalc(void) 327 { 328 u_long n; 329 330 /* 331 * Determine the upper bound of memory to use for buffers. 332 * 333 * - If bufpages is specified, use that as the number 334 * pages. 335 * 336 * - Otherwise, use bufcache as the percentage of 337 * physical memory. 338 */ 339 if (bufpages != 0) { 340 n = bufpages; 341 } else { 342 if (bufcache < 5) { 343 printf("forcing bufcache %d -> 5", bufcache); 344 bufcache = 5; 345 } 346 if (bufcache > 95) { 347 printf("forcing bufcache %d -> 95", bufcache); 348 bufcache = 95; 349 } 350 n = physmem / 100 * bufcache; 351 } 352 353 n <<= PAGE_SHIFT; 354 if (bufmem_valimit != 0 && n > bufmem_valimit) 355 n = bufmem_valimit; 356 357 return (n); 358 } 359 360 /* 361 * Initialize buffers and hash links for buffers. 362 */ 363 void 364 bufinit(void) 365 { 366 struct bqueue *dp; 367 int use_std; 368 u_int i; 369 370 /* 371 * Initialize buffer cache memory parameters. 372 */ 373 bufmem = 0; 374 buf_setwm(); 375 376 if (bufmem_valimit != 0) { 377 vaddr_t minaddr = 0, maxaddr; 378 buf_map = uvm_km_suballoc(kernel_map, &minaddr, &maxaddr, 379 bufmem_valimit, VM_MAP_PAGEABLE, 380 FALSE, 0); 381 if (buf_map == NULL) 382 panic("bufinit: cannot allocate submap"); 383 } else 384 buf_map = kernel_map; 385 386 /* 387 * Initialize the buffer pools. 388 */ 389 pool_init(&bufpool, sizeof(struct buf), 0, 0, 0, "bufpl", NULL); 390 391 /* On "small" machines use small pool page sizes where possible */ 392 use_std = (physmem < atop(16*1024*1024)); 393 394 /* 395 * Also use them on systems that can map the pool pages using 396 * a direct-mapped segment. 397 */ 398 #ifdef PMAP_MAP_POOLPAGE 399 use_std = 1; 400 #endif 401 402 for (i = 0; i < NMEMPOOLS; i++) { 403 struct pool_allocator *pa; 404 struct pool *pp = &bmempools[i]; 405 u_int size = 1 << (i + MEMPOOL_INDEX_OFFSET); 406 char *name = malloc(8, M_TEMP, M_WAITOK); 407 snprintf(name, 8, "buf%dk", 1 << i); 408 pa = (size <= PAGE_SIZE && use_std) 409 ? &pool_allocator_nointr 410 : &bufmempool_allocator; 411 pool_init(pp, size, 0, 0, 0, name, pa); 412 pool_setlowat(pp, 1); 413 pool_sethiwat(pp, 1); 414 } 415 416 /* Initialize the buffer queues */ 417 for (dp = bufqueues; dp < &bufqueues[BQUEUES]; dp++) { 418 TAILQ_INIT(&dp->bq_queue); 419 dp->bq_bytes = 0; 420 } 421 422 /* 423 * Estimate hash table size based on the amount of memory we 424 * intend to use for the buffer cache. The average buffer 425 * size is dependent on our clients (i.e. filesystems). 426 * 427 * For now, use an empirical 3K per buffer. 428 */ 429 nbuf = (bufmem_hiwater / 1024) / 3; 430 bufhashtbl = hashinit(nbuf, HASH_LIST, M_CACHE, M_WAITOK, &bufhash); 431 } 432 433 static int 434 buf_lotsfree(void) 435 { 436 int try, thresh; 437 struct lwp *l = curlwp; 438 439 /* Always allocate if doing copy on write */ 440 if (l->l_flag & L_COWINPROGRESS) 441 return 1; 442 443 /* Always allocate if less than the low water mark. */ 444 if (bufmem < bufmem_lowater) 445 return 1; 446 447 /* Never allocate if greater than the high water mark. */ 448 if (bufmem > bufmem_hiwater) 449 return 0; 450 451 /* If there's anything on the AGE list, it should be eaten. */ 452 if (TAILQ_FIRST(&bufqueues[BQ_AGE].bq_queue) != NULL) 453 return 0; 454 455 /* 456 * The probabily of getting a new allocation is inversely 457 * proportional to the current size of the cache, using 458 * a granularity of 16 steps. 459 */ 460 try = random() & 0x0000000fL; 461 462 /* Don't use "16 * bufmem" here to avoid a 32-bit overflow. */ 463 thresh = (bufmem - bufmem_lowater) / 464 ((bufmem_hiwater - bufmem_lowater) / 16); 465 466 if (try >= thresh) 467 return 1; 468 469 /* Otherwise don't allocate. */ 470 return 0; 471 } 472 473 /* 474 * Return estimate of bytes we think need to be 475 * released to help resolve low memory conditions. 476 * 477 * => called at splbio. 478 * => called with bqueue_slock held. 479 */ 480 static int 481 buf_canrelease(void) 482 { 483 int pagedemand, ninvalid = 0; 484 485 LOCK_ASSERT(simple_lock_held(&bqueue_slock)); 486 487 if (bufmem < bufmem_lowater) 488 return 0; 489 490 if (bufmem > bufmem_hiwater) 491 return bufmem - bufmem_hiwater; 492 493 ninvalid += bufqueues[BQ_AGE].bq_bytes; 494 495 pagedemand = uvmexp.freetarg - uvmexp.free; 496 if (pagedemand < 0) 497 return ninvalid; 498 return MAX(ninvalid, MIN(2 * MAXBSIZE, 499 MIN((bufmem - bufmem_lowater) / 16, pagedemand * PAGE_SIZE))); 500 } 501 502 /* 503 * Buffer memory allocation helper functions 504 */ 505 static __inline u_long 506 buf_mempoolidx(u_long size) 507 { 508 u_int n = 0; 509 510 size -= 1; 511 size >>= MEMPOOL_INDEX_OFFSET; 512 while (size) { 513 size >>= 1; 514 n += 1; 515 } 516 if (n >= NMEMPOOLS) 517 panic("buf mem pool index %d", n); 518 return n; 519 } 520 521 static __inline u_long 522 buf_roundsize(u_long size) 523 { 524 /* Round up to nearest power of 2 */ 525 return (1 << (buf_mempoolidx(size) + MEMPOOL_INDEX_OFFSET)); 526 } 527 528 static __inline caddr_t 529 buf_malloc(size_t size) 530 { 531 u_int n = buf_mempoolidx(size); 532 caddr_t addr; 533 int s; 534 535 while (1) { 536 addr = pool_get(&bmempools[n], PR_NOWAIT); 537 if (addr != NULL) 538 break; 539 540 /* No memory, see if we can free some. If so, try again */ 541 if (buf_drain(1) > 0) 542 continue; 543 544 /* Wait for buffers to arrive on the LRU queue */ 545 s = splbio(); 546 simple_lock(&bqueue_slock); 547 needbuffer = 1; 548 ltsleep(&needbuffer, PNORELOCK | (PRIBIO + 1), 549 "buf_malloc", 0, &bqueue_slock); 550 splx(s); 551 } 552 553 return addr; 554 } 555 556 static void 557 buf_mrelease(caddr_t addr, size_t size) 558 { 559 560 pool_put(&bmempools[buf_mempoolidx(size)], addr); 561 } 562 563 /* 564 * bread()/breadn() helper. 565 */ 566 static __inline struct buf * 567 bio_doread(struct vnode *vp, daddr_t blkno, int size, struct ucred *cred, 568 int async) 569 { 570 struct buf *bp; 571 struct lwp *l = (curlwp != NULL ? curlwp : &lwp0); /* XXX */ 572 struct proc *p = l->l_proc; 573 struct mount *mp; 574 575 bp = getblk(vp, blkno, size, 0, 0); 576 577 #ifdef DIAGNOSTIC 578 if (bp == NULL) { 579 panic("bio_doread: no such buf"); 580 } 581 #endif 582 583 /* 584 * If buffer does not have data valid, start a read. 585 * Note that if buffer is B_INVAL, getblk() won't return it. 586 * Therefore, it's valid if its I/O has completed or been delayed. 587 */ 588 if (!ISSET(bp->b_flags, (B_DONE | B_DELWRI))) { 589 /* Start I/O for the buffer. */ 590 SET(bp->b_flags, B_READ | async); 591 if (async) 592 BIO_SETPRIO(bp, BPRIO_TIMELIMITED); 593 else 594 BIO_SETPRIO(bp, BPRIO_TIMECRITICAL); 595 VOP_STRATEGY(vp, bp); 596 597 /* Pay for the read. */ 598 p->p_stats->p_ru.ru_inblock++; 599 } else if (async) { 600 brelse(bp); 601 } 602 603 if (vp->v_type == VBLK) 604 mp = vp->v_specmountpoint; 605 else 606 mp = vp->v_mount; 607 608 /* 609 * Collect statistics on synchronous and asynchronous reads. 610 * Reads from block devices are charged to their associated 611 * filesystem (if any). 612 */ 613 if (mp != NULL) { 614 if (async == 0) 615 mp->mnt_stat.f_syncreads++; 616 else 617 mp->mnt_stat.f_asyncreads++; 618 } 619 620 return (bp); 621 } 622 623 /* 624 * Read a disk block. 625 * This algorithm described in Bach (p.54). 626 */ 627 int 628 bread(struct vnode *vp, daddr_t blkno, int size, struct ucred *cred, 629 struct buf **bpp) 630 { 631 struct buf *bp; 632 633 /* Get buffer for block. */ 634 bp = *bpp = bio_doread(vp, blkno, size, cred, 0); 635 636 /* Wait for the read to complete, and return result. */ 637 return (biowait(bp)); 638 } 639 640 /* 641 * Read-ahead multiple disk blocks. The first is sync, the rest async. 642 * Trivial modification to the breada algorithm presented in Bach (p.55). 643 */ 644 int 645 breadn(struct vnode *vp, daddr_t blkno, int size, daddr_t *rablks, 646 int *rasizes, int nrablks, struct ucred *cred, struct buf **bpp) 647 { 648 struct buf *bp; 649 int i; 650 651 bp = *bpp = bio_doread(vp, blkno, size, cred, 0); 652 653 /* 654 * For each of the read-ahead blocks, start a read, if necessary. 655 */ 656 for (i = 0; i < nrablks; i++) { 657 /* If it's in the cache, just go on to next one. */ 658 if (incore(vp, rablks[i])) 659 continue; 660 661 /* Get a buffer for the read-ahead block */ 662 (void) bio_doread(vp, rablks[i], rasizes[i], cred, B_ASYNC); 663 } 664 665 /* Otherwise, we had to start a read for it; wait until it's valid. */ 666 return (biowait(bp)); 667 } 668 669 /* 670 * Read with single-block read-ahead. Defined in Bach (p.55), but 671 * implemented as a call to breadn(). 672 * XXX for compatibility with old file systems. 673 */ 674 int 675 breada(struct vnode *vp, daddr_t blkno, int size, daddr_t rablkno, 676 int rabsize, struct ucred *cred, struct buf **bpp) 677 { 678 679 return (breadn(vp, blkno, size, &rablkno, &rabsize, 1, cred, bpp)); 680 } 681 682 /* 683 * Block write. Described in Bach (p.56) 684 */ 685 int 686 bwrite(struct buf *bp) 687 { 688 int rv, sync, wasdelayed, s; 689 struct lwp *l = (curlwp != NULL ? curlwp : &lwp0); /* XXX */ 690 struct proc *p = l->l_proc; 691 struct vnode *vp; 692 struct mount *mp; 693 694 KASSERT(ISSET(bp->b_flags, B_BUSY)); 695 696 vp = bp->b_vp; 697 if (vp != NULL) { 698 if (vp->v_type == VBLK) 699 mp = vp->v_specmountpoint; 700 else 701 mp = vp->v_mount; 702 } else { 703 mp = NULL; 704 } 705 706 /* 707 * Remember buffer type, to switch on it later. If the write was 708 * synchronous, but the file system was mounted with MNT_ASYNC, 709 * convert it to a delayed write. 710 * XXX note that this relies on delayed tape writes being converted 711 * to async, not sync writes (which is safe, but ugly). 712 */ 713 sync = !ISSET(bp->b_flags, B_ASYNC); 714 if (sync && mp != NULL && ISSET(mp->mnt_flag, MNT_ASYNC)) { 715 bdwrite(bp); 716 return (0); 717 } 718 719 /* 720 * Collect statistics on synchronous and asynchronous writes. 721 * Writes to block devices are charged to their associated 722 * filesystem (if any). 723 */ 724 if (mp != NULL) { 725 if (sync) 726 mp->mnt_stat.f_syncwrites++; 727 else 728 mp->mnt_stat.f_asyncwrites++; 729 } 730 731 s = splbio(); 732 simple_lock(&bp->b_interlock); 733 734 wasdelayed = ISSET(bp->b_flags, B_DELWRI); 735 736 CLR(bp->b_flags, (B_READ | B_DONE | B_ERROR | B_DELWRI)); 737 738 /* 739 * Pay for the I/O operation and make sure the buf is on the correct 740 * vnode queue. 741 */ 742 if (wasdelayed) 743 reassignbuf(bp, bp->b_vp); 744 else 745 p->p_stats->p_ru.ru_oublock++; 746 747 /* Initiate disk write. Make sure the appropriate party is charged. */ 748 V_INCR_NUMOUTPUT(bp->b_vp); 749 simple_unlock(&bp->b_interlock); 750 splx(s); 751 752 if (sync) 753 BIO_SETPRIO(bp, BPRIO_TIMECRITICAL); 754 else 755 BIO_SETPRIO(bp, BPRIO_TIMELIMITED); 756 757 VOP_STRATEGY(vp, bp); 758 759 if (sync) { 760 /* If I/O was synchronous, wait for it to complete. */ 761 rv = biowait(bp); 762 763 /* Release the buffer. */ 764 brelse(bp); 765 766 return (rv); 767 } else { 768 return (0); 769 } 770 } 771 772 int 773 vn_bwrite(void *v) 774 { 775 struct vop_bwrite_args *ap = v; 776 777 return (bwrite(ap->a_bp)); 778 } 779 780 /* 781 * Delayed write. 782 * 783 * The buffer is marked dirty, but is not queued for I/O. 784 * This routine should be used when the buffer is expected 785 * to be modified again soon, typically a small write that 786 * partially fills a buffer. 787 * 788 * NB: magnetic tapes cannot be delayed; they must be 789 * written in the order that the writes are requested. 790 * 791 * Described in Leffler, et al. (pp. 208-213). 792 */ 793 void 794 bdwrite(struct buf *bp) 795 { 796 struct lwp *l = (curlwp != NULL ? curlwp : &lwp0); /* XXX */ 797 struct proc *p = l->l_proc; 798 const struct bdevsw *bdev; 799 int s; 800 801 /* If this is a tape block, write the block now. */ 802 bdev = bdevsw_lookup(bp->b_dev); 803 if (bdev != NULL && bdev->d_type == D_TAPE) { 804 bawrite(bp); 805 return; 806 } 807 808 /* 809 * If the block hasn't been seen before: 810 * (1) Mark it as having been seen, 811 * (2) Charge for the write, 812 * (3) Make sure it's on its vnode's correct block list. 813 */ 814 s = splbio(); 815 simple_lock(&bp->b_interlock); 816 817 KASSERT(ISSET(bp->b_flags, B_BUSY)); 818 819 if (!ISSET(bp->b_flags, B_DELWRI)) { 820 SET(bp->b_flags, B_DELWRI); 821 p->p_stats->p_ru.ru_oublock++; 822 reassignbuf(bp, bp->b_vp); 823 } 824 825 /* Otherwise, the "write" is done, so mark and release the buffer. */ 826 CLR(bp->b_flags, B_DONE); 827 simple_unlock(&bp->b_interlock); 828 splx(s); 829 830 brelse(bp); 831 } 832 833 /* 834 * Asynchronous block write; just an asynchronous bwrite(). 835 */ 836 void 837 bawrite(struct buf *bp) 838 { 839 int s; 840 841 s = splbio(); 842 simple_lock(&bp->b_interlock); 843 844 KASSERT(ISSET(bp->b_flags, B_BUSY)); 845 846 SET(bp->b_flags, B_ASYNC); 847 simple_unlock(&bp->b_interlock); 848 splx(s); 849 VOP_BWRITE(bp); 850 } 851 852 /* 853 * Same as first half of bdwrite, mark buffer dirty, but do not release it. 854 * Call at splbio() and with the buffer interlock locked. 855 * Note: called only from biodone() through ffs softdep's bioops.io_complete() 856 */ 857 void 858 bdirty(struct buf *bp) 859 { 860 struct lwp *l = (curlwp != NULL ? curlwp : &lwp0); /* XXX */ 861 struct proc *p = l->l_proc; 862 863 LOCK_ASSERT(simple_lock_held(&bp->b_interlock)); 864 KASSERT(ISSET(bp->b_flags, B_BUSY)); 865 866 CLR(bp->b_flags, B_AGE); 867 868 if (!ISSET(bp->b_flags, B_DELWRI)) { 869 SET(bp->b_flags, B_DELWRI); 870 p->p_stats->p_ru.ru_oublock++; 871 reassignbuf(bp, bp->b_vp); 872 } 873 } 874 875 /* 876 * Release a buffer on to the free lists. 877 * Described in Bach (p. 46). 878 */ 879 void 880 brelse(struct buf *bp) 881 { 882 struct bqueue *bufq; 883 int s; 884 885 /* Block disk interrupts. */ 886 s = splbio(); 887 simple_lock(&bqueue_slock); 888 simple_lock(&bp->b_interlock); 889 890 KASSERT(ISSET(bp->b_flags, B_BUSY)); 891 KASSERT(!ISSET(bp->b_flags, B_CALL)); 892 893 /* Wake up any processes waiting for any buffer to become free. */ 894 if (needbuffer) { 895 needbuffer = 0; 896 wakeup(&needbuffer); 897 } 898 899 /* Wake up any proceeses waiting for _this_ buffer to become free. */ 900 if (ISSET(bp->b_flags, B_WANTED)) { 901 CLR(bp->b_flags, B_WANTED|B_AGE); 902 wakeup(bp); 903 } 904 905 /* 906 * Determine which queue the buffer should be on, then put it there. 907 */ 908 909 /* If it's locked, don't report an error; try again later. */ 910 if (ISSET(bp->b_flags, (B_LOCKED|B_ERROR)) == (B_LOCKED|B_ERROR)) 911 CLR(bp->b_flags, B_ERROR); 912 913 /* If it's not cacheable, or an error, mark it invalid. */ 914 if (ISSET(bp->b_flags, (B_NOCACHE|B_ERROR))) 915 SET(bp->b_flags, B_INVAL); 916 917 if (ISSET(bp->b_flags, B_VFLUSH)) { 918 /* 919 * This is a delayed write buffer that was just flushed to 920 * disk. It is still on the LRU queue. If it's become 921 * invalid, then we need to move it to a different queue; 922 * otherwise leave it in its current position. 923 */ 924 CLR(bp->b_flags, B_VFLUSH); 925 if (!ISSET(bp->b_flags, B_ERROR|B_INVAL|B_LOCKED|B_AGE)) { 926 KDASSERT(!debug_verify_freelist || checkfreelist(bp, &bufqueues[BQ_LRU])); 927 goto already_queued; 928 } else { 929 bremfree(bp); 930 } 931 } 932 933 KDASSERT(!debug_verify_freelist || !checkfreelist(bp, &bufqueues[BQ_AGE])); 934 KDASSERT(!debug_verify_freelist || !checkfreelist(bp, &bufqueues[BQ_LRU])); 935 KDASSERT(!debug_verify_freelist || !checkfreelist(bp, &bufqueues[BQ_LOCKED])); 936 937 if ((bp->b_bufsize <= 0) || ISSET(bp->b_flags, B_INVAL)) { 938 /* 939 * If it's invalid or empty, dissociate it from its vnode 940 * and put on the head of the appropriate queue. 941 */ 942 if (LIST_FIRST(&bp->b_dep) != NULL && bioops.io_deallocate) 943 (*bioops.io_deallocate)(bp); 944 CLR(bp->b_flags, B_DONE|B_DELWRI); 945 if (bp->b_vp) { 946 reassignbuf(bp, bp->b_vp); 947 brelvp(bp); 948 } 949 if (bp->b_bufsize <= 0) 950 /* no data */ 951 goto already_queued; 952 else 953 /* invalid data */ 954 bufq = &bufqueues[BQ_AGE]; 955 binsheadfree(bp, bufq); 956 } else { 957 /* 958 * It has valid data. Put it on the end of the appropriate 959 * queue, so that it'll stick around for as long as possible. 960 * If buf is AGE, but has dependencies, must put it on last 961 * bufqueue to be scanned, ie LRU. This protects against the 962 * livelock where BQ_AGE only has buffers with dependencies, 963 * and we thus never get to the dependent buffers in BQ_LRU. 964 */ 965 if (ISSET(bp->b_flags, B_LOCKED)) 966 /* locked in core */ 967 bufq = &bufqueues[BQ_LOCKED]; 968 else if (!ISSET(bp->b_flags, B_AGE)) 969 /* valid data */ 970 bufq = &bufqueues[BQ_LRU]; 971 else { 972 /* stale but valid data */ 973 int has_deps; 974 975 if (LIST_FIRST(&bp->b_dep) != NULL && 976 bioops.io_countdeps) 977 has_deps = (*bioops.io_countdeps)(bp, 0); 978 else 979 has_deps = 0; 980 bufq = has_deps ? &bufqueues[BQ_LRU] : 981 &bufqueues[BQ_AGE]; 982 } 983 binstailfree(bp, bufq); 984 } 985 986 already_queued: 987 /* Unlock the buffer. */ 988 CLR(bp->b_flags, B_AGE|B_ASYNC|B_BUSY|B_NOCACHE); 989 SET(bp->b_flags, B_CACHE); 990 991 /* Allow disk interrupts. */ 992 simple_unlock(&bp->b_interlock); 993 simple_unlock(&bqueue_slock); 994 if (bp->b_bufsize <= 0) { 995 #ifdef DEBUG 996 memset((char *)bp, 0, sizeof(*bp)); 997 #endif 998 pool_put(&bufpool, bp); 999 } 1000 splx(s); 1001 } 1002 1003 /* 1004 * Determine if a block is in the cache. 1005 * Just look on what would be its hash chain. If it's there, return 1006 * a pointer to it, unless it's marked invalid. If it's marked invalid, 1007 * we normally don't return the buffer, unless the caller explicitly 1008 * wants us to. 1009 */ 1010 struct buf * 1011 incore(struct vnode *vp, daddr_t blkno) 1012 { 1013 struct buf *bp; 1014 1015 /* Search hash chain */ 1016 LIST_FOREACH(bp, BUFHASH(vp, blkno), b_hash) { 1017 if (bp->b_lblkno == blkno && bp->b_vp == vp && 1018 !ISSET(bp->b_flags, B_INVAL)) 1019 return (bp); 1020 } 1021 1022 return (NULL); 1023 } 1024 1025 /* 1026 * Get a block of requested size that is associated with 1027 * a given vnode and block offset. If it is found in the 1028 * block cache, mark it as having been found, make it busy 1029 * and return it. Otherwise, return an empty block of the 1030 * correct size. It is up to the caller to insure that the 1031 * cached blocks be of the correct size. 1032 */ 1033 struct buf * 1034 getblk(struct vnode *vp, daddr_t blkno, int size, int slpflag, int slptimeo) 1035 { 1036 struct buf *bp; 1037 int s, err; 1038 int preserve; 1039 1040 start: 1041 s = splbio(); 1042 simple_lock(&bqueue_slock); 1043 bp = incore(vp, blkno); 1044 if (bp != NULL) { 1045 simple_lock(&bp->b_interlock); 1046 if (ISSET(bp->b_flags, B_BUSY)) { 1047 simple_unlock(&bqueue_slock); 1048 if (curproc == uvm.pagedaemon_proc) { 1049 simple_unlock(&bp->b_interlock); 1050 splx(s); 1051 return NULL; 1052 } 1053 SET(bp->b_flags, B_WANTED); 1054 err = ltsleep(bp, slpflag | (PRIBIO + 1) | PNORELOCK, 1055 "getblk", slptimeo, &bp->b_interlock); 1056 splx(s); 1057 if (err) 1058 return (NULL); 1059 goto start; 1060 } 1061 #ifdef DIAGNOSTIC 1062 if (ISSET(bp->b_flags, B_DONE|B_DELWRI) && 1063 bp->b_bcount < size && vp->v_type != VBLK) 1064 panic("getblk: block size invariant failed"); 1065 #endif 1066 SET(bp->b_flags, B_BUSY); 1067 bremfree(bp); 1068 preserve = 1; 1069 } else { 1070 if ((bp = getnewbuf(slpflag, slptimeo, 0)) == NULL) { 1071 simple_unlock(&bqueue_slock); 1072 splx(s); 1073 goto start; 1074 } 1075 1076 binshash(bp, BUFHASH(vp, blkno)); 1077 bp->b_blkno = bp->b_lblkno = bp->b_rawblkno = blkno; 1078 bgetvp(vp, bp); 1079 preserve = 0; 1080 } 1081 simple_unlock(&bp->b_interlock); 1082 simple_unlock(&bqueue_slock); 1083 splx(s); 1084 /* 1085 * LFS can't track total size of B_LOCKED buffer (locked_queue_bytes) 1086 * if we re-size buffers here. 1087 */ 1088 if (ISSET(bp->b_flags, B_LOCKED)) { 1089 KASSERT(bp->b_bufsize >= size); 1090 } else { 1091 allocbuf(bp, size, preserve); 1092 } 1093 BIO_SETPRIO(bp, BPRIO_DEFAULT); 1094 return (bp); 1095 } 1096 1097 /* 1098 * Get an empty, disassociated buffer of given size. 1099 */ 1100 struct buf * 1101 geteblk(int size) 1102 { 1103 struct buf *bp; 1104 int s; 1105 1106 s = splbio(); 1107 simple_lock(&bqueue_slock); 1108 while ((bp = getnewbuf(0, 0, 0)) == 0) 1109 ; 1110 1111 SET(bp->b_flags, B_INVAL); 1112 binshash(bp, &invalhash); 1113 simple_unlock(&bqueue_slock); 1114 simple_unlock(&bp->b_interlock); 1115 splx(s); 1116 BIO_SETPRIO(bp, BPRIO_DEFAULT); 1117 allocbuf(bp, size, 0); 1118 return (bp); 1119 } 1120 1121 /* 1122 * Expand or contract the actual memory allocated to a buffer. 1123 * 1124 * If the buffer shrinks, data is lost, so it's up to the 1125 * caller to have written it out *first*; this routine will not 1126 * start a write. If the buffer grows, it's the callers 1127 * responsibility to fill out the buffer's additional contents. 1128 */ 1129 void 1130 allocbuf(struct buf *bp, int size, int preserve) 1131 { 1132 vsize_t oldsize, desired_size; 1133 caddr_t addr; 1134 int s, delta; 1135 1136 desired_size = buf_roundsize(size); 1137 if (desired_size > MAXBSIZE) 1138 printf("allocbuf: buffer larger than MAXBSIZE requested"); 1139 1140 bp->b_bcount = size; 1141 1142 oldsize = bp->b_bufsize; 1143 if (oldsize == desired_size) 1144 return; 1145 1146 /* 1147 * If we want a buffer of a different size, re-allocate the 1148 * buffer's memory; copy old content only if needed. 1149 */ 1150 addr = buf_malloc(desired_size); 1151 if (preserve) 1152 memcpy(addr, bp->b_data, MIN(oldsize,desired_size)); 1153 if (bp->b_data != NULL) 1154 buf_mrelease(bp->b_data, oldsize); 1155 bp->b_data = addr; 1156 bp->b_bufsize = desired_size; 1157 1158 /* 1159 * Update overall buffer memory counter (protected by bqueue_slock) 1160 */ 1161 delta = (long)desired_size - (long)oldsize; 1162 1163 s = splbio(); 1164 simple_lock(&bqueue_slock); 1165 if ((bufmem += delta) > bufmem_hiwater) { 1166 /* 1167 * Need to trim overall memory usage. 1168 */ 1169 while (buf_canrelease()) { 1170 if (buf_trim() == 0) 1171 break; 1172 } 1173 } 1174 1175 simple_unlock(&bqueue_slock); 1176 splx(s); 1177 } 1178 1179 /* 1180 * Find a buffer which is available for use. 1181 * Select something from a free list. 1182 * Preference is to AGE list, then LRU list. 1183 * 1184 * Called at splbio and with buffer queues locked. 1185 * Return buffer locked. 1186 */ 1187 struct buf * 1188 getnewbuf(int slpflag, int slptimeo, int from_bufq) 1189 { 1190 struct buf *bp; 1191 1192 start: 1193 LOCK_ASSERT(simple_lock_held(&bqueue_slock)); 1194 1195 /* 1196 * Get a new buffer from the pool; but use NOWAIT because 1197 * we have the buffer queues locked. 1198 */ 1199 if (!from_bufq && buf_lotsfree() && 1200 (bp = pool_get(&bufpool, PR_NOWAIT)) != NULL) { 1201 memset((char *)bp, 0, sizeof(*bp)); 1202 BUF_INIT(bp); 1203 bp->b_dev = NODEV; 1204 bp->b_vnbufs.le_next = NOLIST; 1205 bp->b_flags = B_BUSY; 1206 simple_lock(&bp->b_interlock); 1207 #if defined(DIAGNOSTIC) 1208 bp->b_freelistindex = -1; 1209 #endif /* defined(DIAGNOSTIC) */ 1210 return (bp); 1211 } 1212 1213 if ((bp = TAILQ_FIRST(&bufqueues[BQ_AGE].bq_queue)) != NULL || 1214 (bp = TAILQ_FIRST(&bufqueues[BQ_LRU].bq_queue)) != NULL) { 1215 simple_lock(&bp->b_interlock); 1216 bremfree(bp); 1217 } else { 1218 /* 1219 * XXX: !from_bufq should be removed. 1220 */ 1221 if (!from_bufq || curproc != uvm.pagedaemon_proc) { 1222 /* wait for a free buffer of any kind */ 1223 needbuffer = 1; 1224 ltsleep(&needbuffer, slpflag|(PRIBIO + 1), 1225 "getnewbuf", slptimeo, &bqueue_slock); 1226 } 1227 return (NULL); 1228 } 1229 1230 #ifdef DIAGNOSTIC 1231 if (bp->b_bufsize <= 0) 1232 panic("buffer %p: on queue but empty", bp); 1233 #endif 1234 1235 if (ISSET(bp->b_flags, B_VFLUSH)) { 1236 /* 1237 * This is a delayed write buffer being flushed to disk. Make 1238 * sure it gets aged out of the queue when it's finished, and 1239 * leave it off the LRU queue. 1240 */ 1241 CLR(bp->b_flags, B_VFLUSH); 1242 SET(bp->b_flags, B_AGE); 1243 simple_unlock(&bp->b_interlock); 1244 goto start; 1245 } 1246 1247 /* Buffer is no longer on free lists. */ 1248 SET(bp->b_flags, B_BUSY); 1249 1250 /* 1251 * If buffer was a delayed write, start it and return NULL 1252 * (since we might sleep while starting the write). 1253 */ 1254 if (ISSET(bp->b_flags, B_DELWRI)) { 1255 /* 1256 * This buffer has gone through the LRU, so make sure it gets 1257 * reused ASAP. 1258 */ 1259 SET(bp->b_flags, B_AGE); 1260 simple_unlock(&bp->b_interlock); 1261 simple_unlock(&bqueue_slock); 1262 bawrite(bp); 1263 simple_lock(&bqueue_slock); 1264 return (NULL); 1265 } 1266 1267 /* disassociate us from our vnode, if we had one... */ 1268 if (bp->b_vp) 1269 brelvp(bp); 1270 1271 if (LIST_FIRST(&bp->b_dep) != NULL && bioops.io_deallocate) 1272 (*bioops.io_deallocate)(bp); 1273 1274 /* clear out various other fields */ 1275 bp->b_flags = B_BUSY; 1276 bp->b_dev = NODEV; 1277 bp->b_blkno = bp->b_lblkno = bp->b_rawblkno = 0; 1278 bp->b_iodone = 0; 1279 bp->b_error = 0; 1280 bp->b_resid = 0; 1281 bp->b_bcount = 0; 1282 1283 bremhash(bp); 1284 return (bp); 1285 } 1286 1287 /* 1288 * Attempt to free an aged buffer off the queues. 1289 * Called at splbio and with queue lock held. 1290 * Returns the amount of buffer memory freed. 1291 */ 1292 static int 1293 buf_trim(void) 1294 { 1295 struct buf *bp; 1296 long size = 0; 1297 1298 /* Instruct getnewbuf() to get buffers off the queues */ 1299 if ((bp = getnewbuf(PCATCH, 1, 1)) == NULL) 1300 return 0; 1301 1302 KASSERT(!ISSET(bp->b_flags, B_WANTED)); 1303 simple_unlock(&bp->b_interlock); 1304 size = bp->b_bufsize; 1305 bufmem -= size; 1306 simple_unlock(&bqueue_slock); 1307 if (size > 0) { 1308 buf_mrelease(bp->b_data, size); 1309 bp->b_bcount = bp->b_bufsize = 0; 1310 } 1311 /* brelse() will return the buffer to the global buffer pool */ 1312 brelse(bp); 1313 simple_lock(&bqueue_slock); 1314 return size; 1315 } 1316 1317 int 1318 buf_drain(int n) 1319 { 1320 int s, size = 0, sz; 1321 1322 s = splbio(); 1323 simple_lock(&bqueue_slock); 1324 1325 while (size < n && bufmem > bufmem_lowater) { 1326 sz = buf_trim(); 1327 if (sz <= 0) 1328 break; 1329 size += sz; 1330 } 1331 1332 simple_unlock(&bqueue_slock); 1333 splx(s); 1334 return size; 1335 } 1336 1337 /* 1338 * Wait for operations on the buffer to complete. 1339 * When they do, extract and return the I/O's error value. 1340 */ 1341 int 1342 biowait(struct buf *bp) 1343 { 1344 int s, error; 1345 1346 s = splbio(); 1347 simple_lock(&bp->b_interlock); 1348 while (!ISSET(bp->b_flags, B_DONE | B_DELWRI)) 1349 ltsleep(bp, PRIBIO + 1, "biowait", 0, &bp->b_interlock); 1350 1351 /* check for interruption of I/O (e.g. via NFS), then errors. */ 1352 if (ISSET(bp->b_flags, B_EINTR)) { 1353 CLR(bp->b_flags, B_EINTR); 1354 error = EINTR; 1355 } else if (ISSET(bp->b_flags, B_ERROR)) 1356 error = bp->b_error ? bp->b_error : EIO; 1357 else 1358 error = 0; 1359 1360 simple_unlock(&bp->b_interlock); 1361 splx(s); 1362 return (error); 1363 } 1364 1365 /* 1366 * Mark I/O complete on a buffer. 1367 * 1368 * If a callback has been requested, e.g. the pageout 1369 * daemon, do so. Otherwise, awaken waiting processes. 1370 * 1371 * [ Leffler, et al., says on p.247: 1372 * "This routine wakes up the blocked process, frees the buffer 1373 * for an asynchronous write, or, for a request by the pagedaemon 1374 * process, invokes a procedure specified in the buffer structure" ] 1375 * 1376 * In real life, the pagedaemon (or other system processes) wants 1377 * to do async stuff to, and doesn't want the buffer brelse()'d. 1378 * (for swap pager, that puts swap buffers on the free lists (!!!), 1379 * for the vn device, that puts malloc'd buffers on the free lists!) 1380 */ 1381 void 1382 biodone(struct buf *bp) 1383 { 1384 int s = splbio(); 1385 1386 simple_lock(&bp->b_interlock); 1387 if (ISSET(bp->b_flags, B_DONE)) 1388 panic("biodone already"); 1389 SET(bp->b_flags, B_DONE); /* note that it's done */ 1390 BIO_SETPRIO(bp, BPRIO_DEFAULT); 1391 1392 if (LIST_FIRST(&bp->b_dep) != NULL && bioops.io_complete) 1393 (*bioops.io_complete)(bp); 1394 1395 if (!ISSET(bp->b_flags, B_READ)) /* wake up reader */ 1396 vwakeup(bp); 1397 1398 /* 1399 * If necessary, call out. Unlock the buffer before calling 1400 * iodone() as the buffer isn't valid any more when it return. 1401 */ 1402 if (ISSET(bp->b_flags, B_CALL)) { 1403 CLR(bp->b_flags, B_CALL); /* but note callout done */ 1404 simple_unlock(&bp->b_interlock); 1405 (*bp->b_iodone)(bp); 1406 } else { 1407 if (ISSET(bp->b_flags, B_ASYNC)) { /* if async, release */ 1408 simple_unlock(&bp->b_interlock); 1409 brelse(bp); 1410 } else { /* or just wakeup the buffer */ 1411 CLR(bp->b_flags, B_WANTED); 1412 wakeup(bp); 1413 simple_unlock(&bp->b_interlock); 1414 } 1415 } 1416 1417 splx(s); 1418 } 1419 1420 /* 1421 * Return a count of buffers on the "locked" queue. 1422 */ 1423 int 1424 count_lock_queue(void) 1425 { 1426 struct buf *bp; 1427 int n = 0; 1428 1429 simple_lock(&bqueue_slock); 1430 TAILQ_FOREACH(bp, &bufqueues[BQ_LOCKED].bq_queue, b_freelist) 1431 n++; 1432 simple_unlock(&bqueue_slock); 1433 return (n); 1434 } 1435 1436 /* 1437 * Wait for all buffers to complete I/O 1438 * Return the number of "stuck" buffers. 1439 */ 1440 int 1441 buf_syncwait(void) 1442 { 1443 struct buf *bp; 1444 int iter, nbusy, nbusy_prev = 0, dcount, s, ihash; 1445 1446 dcount = 10000; 1447 for (iter = 0; iter < 20;) { 1448 s = splbio(); 1449 simple_lock(&bqueue_slock); 1450 nbusy = 0; 1451 for (ihash = 0; ihash < bufhash+1; ihash++) { 1452 LIST_FOREACH(bp, &bufhashtbl[ihash], b_hash) { 1453 if ((bp->b_flags & (B_BUSY|B_INVAL|B_READ)) == B_BUSY) 1454 nbusy++; 1455 /* 1456 * With soft updates, some buffers that are 1457 * written will be remarked as dirty until other 1458 * buffers are written. 1459 */ 1460 if (bp->b_vp && bp->b_vp->v_mount 1461 && (bp->b_vp->v_mount->mnt_flag & MNT_SOFTDEP) 1462 && (bp->b_flags & B_DELWRI)) { 1463 simple_lock(&bp->b_interlock); 1464 bremfree(bp); 1465 bp->b_flags |= B_BUSY; 1466 nbusy++; 1467 simple_unlock(&bp->b_interlock); 1468 simple_unlock(&bqueue_slock); 1469 bawrite(bp); 1470 if (dcount-- <= 0) { 1471 printf("softdep "); 1472 splx(s); 1473 goto fail; 1474 } 1475 simple_lock(&bqueue_slock); 1476 } 1477 } 1478 } 1479 1480 simple_unlock(&bqueue_slock); 1481 splx(s); 1482 1483 if (nbusy == 0) 1484 break; 1485 if (nbusy_prev == 0) 1486 nbusy_prev = nbusy; 1487 printf("%d ", nbusy); 1488 tsleep(&nbusy, PRIBIO, "bflush", 1489 (iter == 0) ? 1 : hz / 25 * iter); 1490 if (nbusy >= nbusy_prev) /* we didn't flush anything */ 1491 iter++; 1492 else 1493 nbusy_prev = nbusy; 1494 } 1495 1496 if (nbusy) { 1497 fail:; 1498 #if defined(DEBUG) || defined(DEBUG_HALT_BUSY) 1499 printf("giving up\nPrinting vnodes for busy buffers\n"); 1500 s = splbio(); 1501 for (ihash = 0; ihash < bufhash+1; ihash++) { 1502 LIST_FOREACH(bp, &bufhashtbl[ihash], b_hash) { 1503 if ((bp->b_flags & (B_BUSY|B_INVAL|B_READ)) == B_BUSY) 1504 vprint(NULL, bp->b_vp); 1505 } 1506 } 1507 splx(s); 1508 #endif 1509 } 1510 1511 return nbusy; 1512 } 1513 1514 static void 1515 sysctl_fillbuf(struct buf *i, struct buf_sysctl *o) 1516 { 1517 1518 o->b_flags = i->b_flags; 1519 o->b_error = i->b_error; 1520 o->b_prio = i->b_prio; 1521 o->b_dev = i->b_dev; 1522 o->b_bufsize = i->b_bufsize; 1523 o->b_bcount = i->b_bcount; 1524 o->b_resid = i->b_resid; 1525 o->b_addr = PTRTOUINT64(i->b_un.b_addr); 1526 o->b_blkno = i->b_blkno; 1527 o->b_rawblkno = i->b_rawblkno; 1528 o->b_iodone = PTRTOUINT64(i->b_iodone); 1529 o->b_proc = PTRTOUINT64(i->b_proc); 1530 o->b_vp = PTRTOUINT64(i->b_vp); 1531 o->b_saveaddr = PTRTOUINT64(i->b_saveaddr); 1532 o->b_lblkno = i->b_lblkno; 1533 } 1534 1535 #define KERN_BUFSLOP 20 1536 static int 1537 sysctl_dobuf(SYSCTLFN_ARGS) 1538 { 1539 struct buf *bp; 1540 struct buf_sysctl bs; 1541 char *dp; 1542 u_int i, op, arg; 1543 size_t len, needed, elem_size, out_size; 1544 int error, s, elem_count; 1545 1546 if (namelen == 1 && name[0] == CTL_QUERY) 1547 return (sysctl_query(SYSCTLFN_CALL(rnode))); 1548 1549 if (namelen != 4) 1550 return (EINVAL); 1551 1552 dp = oldp; 1553 len = (oldp != NULL) ? *oldlenp : 0; 1554 op = name[0]; 1555 arg = name[1]; 1556 elem_size = name[2]; 1557 elem_count = name[3]; 1558 out_size = MIN(sizeof(bs), elem_size); 1559 1560 /* 1561 * at the moment, these are just "placeholders" to make the 1562 * API for retrieving kern.buf data more extensible in the 1563 * future. 1564 * 1565 * XXX kern.buf currently has "netbsd32" issues. hopefully 1566 * these will be resolved at a later point. 1567 */ 1568 if (op != KERN_BUF_ALL || arg != KERN_BUF_ALL || 1569 elem_size < 1 || elem_count < 0) 1570 return (EINVAL); 1571 1572 error = 0; 1573 needed = 0; 1574 s = splbio(); 1575 simple_lock(&bqueue_slock); 1576 for (i = 0; i < BQUEUES; i++) { 1577 TAILQ_FOREACH(bp, &bufqueues[i].bq_queue, b_freelist) { 1578 if (len >= elem_size && elem_count > 0) { 1579 sysctl_fillbuf(bp, &bs); 1580 error = copyout(&bs, dp, out_size); 1581 if (error) 1582 goto cleanup; 1583 dp += elem_size; 1584 len -= elem_size; 1585 } 1586 if (elem_count > 0) { 1587 needed += elem_size; 1588 if (elem_count != INT_MAX) 1589 elem_count--; 1590 } 1591 } 1592 } 1593 cleanup: 1594 simple_unlock(&bqueue_slock); 1595 splx(s); 1596 1597 *oldlenp = needed; 1598 if (oldp == NULL) 1599 *oldlenp += KERN_BUFSLOP * sizeof(struct buf); 1600 1601 return (error); 1602 } 1603 1604 static int 1605 sysctl_bufvm_update(SYSCTLFN_ARGS) 1606 { 1607 int t, error; 1608 struct sysctlnode node; 1609 1610 node = *rnode; 1611 node.sysctl_data = &t; 1612 t = *(int*)rnode->sysctl_data; 1613 error = sysctl_lookup(SYSCTLFN_CALL(&node)); 1614 if (error || newp == NULL) 1615 return (error); 1616 1617 if (rnode->sysctl_data == &bufcache) { 1618 if (t < 0 || t > 100) 1619 return (EINVAL); 1620 bufcache = t; 1621 buf_setwm(); 1622 } else if (rnode->sysctl_data == &bufmem_lowater) { 1623 if (bufmem_hiwater - bufmem_lowater < 16) 1624 return (EINVAL); 1625 bufmem_lowater = t; 1626 } else if (rnode->sysctl_data == &bufmem_hiwater) { 1627 if (bufmem_hiwater - bufmem_lowater < 16) 1628 return (EINVAL); 1629 bufmem_hiwater = t; 1630 } else 1631 return (EINVAL); 1632 1633 /* Drain until below new high water mark */ 1634 while ((t = bufmem - bufmem_hiwater) >= 0) { 1635 if (buf_drain(t / (2*1024)) <= 0) 1636 break; 1637 } 1638 1639 return 0; 1640 } 1641 1642 SYSCTL_SETUP(sysctl_kern_buf_setup, "sysctl kern.buf subtree setup") 1643 { 1644 1645 sysctl_createv(clog, 0, NULL, NULL, 1646 CTLFLAG_PERMANENT, 1647 CTLTYPE_NODE, "kern", NULL, 1648 NULL, 0, NULL, 0, 1649 CTL_KERN, CTL_EOL); 1650 sysctl_createv(clog, 0, NULL, NULL, 1651 CTLFLAG_PERMANENT, 1652 CTLTYPE_NODE, "buf", 1653 SYSCTL_DESCR("Kernel buffer cache information"), 1654 sysctl_dobuf, 0, NULL, 0, 1655 CTL_KERN, KERN_BUF, CTL_EOL); 1656 } 1657 1658 SYSCTL_SETUP(sysctl_vm_buf_setup, "sysctl vm.buf* subtree setup") 1659 { 1660 1661 sysctl_createv(clog, 0, NULL, NULL, 1662 CTLFLAG_PERMANENT, 1663 CTLTYPE_NODE, "vm", NULL, 1664 NULL, 0, NULL, 0, 1665 CTL_VM, CTL_EOL); 1666 1667 sysctl_createv(clog, 0, NULL, NULL, 1668 CTLFLAG_PERMANENT|CTLFLAG_READWRITE, 1669 CTLTYPE_INT, "bufcache", 1670 SYSCTL_DESCR("Percentage of physical memory to use for " 1671 "buffer cache"), 1672 sysctl_bufvm_update, 0, &bufcache, 0, 1673 CTL_VM, CTL_CREATE, CTL_EOL); 1674 sysctl_createv(clog, 0, NULL, NULL, 1675 CTLFLAG_PERMANENT|CTLFLAG_READONLY, 1676 CTLTYPE_INT, "bufmem", 1677 SYSCTL_DESCR("Amount of kernel memory used by buffer " 1678 "cache"), 1679 NULL, 0, &bufmem, 0, 1680 CTL_VM, CTL_CREATE, CTL_EOL); 1681 sysctl_createv(clog, 0, NULL, NULL, 1682 CTLFLAG_PERMANENT|CTLFLAG_READWRITE, 1683 CTLTYPE_INT, "bufmem_lowater", 1684 SYSCTL_DESCR("Minimum amount of kernel memory to " 1685 "reserve for buffer cache"), 1686 sysctl_bufvm_update, 0, &bufmem_lowater, 0, 1687 CTL_VM, CTL_CREATE, CTL_EOL); 1688 sysctl_createv(clog, 0, NULL, NULL, 1689 CTLFLAG_PERMANENT|CTLFLAG_READWRITE, 1690 CTLTYPE_INT, "bufmem_hiwater", 1691 SYSCTL_DESCR("Maximum amount of kernel memory to use " 1692 "for buffer cache"), 1693 sysctl_bufvm_update, 0, &bufmem_hiwater, 0, 1694 CTL_VM, CTL_CREATE, CTL_EOL); 1695 } 1696 1697 #ifdef DEBUG 1698 /* 1699 * Print out statistics on the current allocation of the buffer pool. 1700 * Can be enabled to print out on every ``sync'' by setting "syncprt" 1701 * in vfs_syscalls.c using sysctl. 1702 */ 1703 void 1704 vfs_bufstats(void) 1705 { 1706 int s, i, j, count; 1707 struct buf *bp; 1708 struct bqueue *dp; 1709 int counts[(MAXBSIZE / PAGE_SIZE) + 1]; 1710 static char *bname[BQUEUES] = { "LOCKED", "LRU", "AGE" }; 1711 1712 for (dp = bufqueues, i = 0; dp < &bufqueues[BQUEUES]; dp++, i++) { 1713 count = 0; 1714 for (j = 0; j <= MAXBSIZE/PAGE_SIZE; j++) 1715 counts[j] = 0; 1716 s = splbio(); 1717 TAILQ_FOREACH(bp, &dp->bq_queue, b_freelist) { 1718 counts[bp->b_bufsize/PAGE_SIZE]++; 1719 count++; 1720 } 1721 splx(s); 1722 printf("%s: total-%d", bname[i], count); 1723 for (j = 0; j <= MAXBSIZE/PAGE_SIZE; j++) 1724 if (counts[j] != 0) 1725 printf(", %d-%d", j * PAGE_SIZE, counts[j]); 1726 printf("\n"); 1727 } 1728 } 1729 #endif /* DEBUG */ 1730