| 1 | /* $NetBSD: vfs_bio.c,v 1.262 2016/10/28 20:17:27 jdolecek 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 1.262 2016/10/28 20:17:27 jdolecek Exp $" ); |
| 127 | |
| 128 | #ifdef _KERNEL_OPT |
| 129 | #include "opt_bufcache.h" |
| 130 | #include "opt_dtrace.h" |
| 131 | #endif |
| 132 | |
| 133 | #include <sys/param.h> |
| 134 | #include <sys/systm.h> |
| 135 | #include <sys/kernel.h> |
| 136 | #include <sys/proc.h> |
| 137 | #include <sys/buf.h> |
| 138 | #include <sys/vnode.h> |
| 139 | #include <sys/mount.h> |
| 140 | #include <sys/resourcevar.h> |
| 141 | #include <sys/sysctl.h> |
| 142 | #include <sys/conf.h> |
| 143 | #include <sys/kauth.h> |
| 144 | #include <sys/fstrans.h> |
| 145 | #include <sys/intr.h> |
| 146 | #include <sys/cpu.h> |
| 147 | #include <sys/wapbl.h> |
| 148 | #include <sys/bitops.h> |
| 149 | #include <sys/cprng.h> |
| 150 | #include <sys/sdt.h> |
| 151 | |
| 152 | #include <uvm/uvm.h> /* extern struct uvm uvm */ |
| 153 | |
| 154 | #include <miscfs/specfs/specdev.h> |
| 155 | |
| 156 | #ifndef BUFPAGES |
| 157 | # define BUFPAGES 0 |
| 158 | #endif |
| 159 | |
| 160 | #ifdef BUFCACHE |
| 161 | # if (BUFCACHE < 5) || (BUFCACHE > 95) |
| 162 | # error BUFCACHE is not between 5 and 95 |
| 163 | # endif |
| 164 | #else |
| 165 | # define BUFCACHE 15 |
| 166 | #endif |
| 167 | |
| 168 | u_int nbuf; /* desired number of buffer headers */ |
| 169 | u_int bufpages = BUFPAGES; /* optional hardwired count */ |
| 170 | u_int bufcache = BUFCACHE; /* max % of RAM to use for buffer cache */ |
| 171 | |
| 172 | /* Function prototypes */ |
| 173 | struct bqueue; |
| 174 | |
| 175 | static void buf_setwm(void); |
| 176 | static int buf_trim(void); |
| 177 | static void *bufpool_page_alloc(struct pool *, int); |
| 178 | static void bufpool_page_free(struct pool *, void *); |
| 179 | static buf_t *bio_doread(struct vnode *, daddr_t, int, int); |
| 180 | static buf_t *getnewbuf(int, int, int); |
| 181 | static int buf_lotsfree(void); |
| 182 | static int buf_canrelease(void); |
| 183 | static u_long buf_mempoolidx(u_long); |
| 184 | static u_long buf_roundsize(u_long); |
| 185 | static void *buf_alloc(size_t); |
| 186 | static void buf_mrelease(void *, size_t); |
| 187 | static void binsheadfree(buf_t *, struct bqueue *); |
| 188 | static void binstailfree(buf_t *, struct bqueue *); |
| 189 | #ifdef DEBUG |
| 190 | static int checkfreelist(buf_t *, struct bqueue *, int); |
| 191 | #endif |
| 192 | static void biointr(void *); |
| 193 | static void biodone2(buf_t *); |
| 194 | static void bref(buf_t *); |
| 195 | static void brele(buf_t *); |
| 196 | static void sysctl_kern_buf_setup(void); |
| 197 | static void sysctl_vm_buf_setup(void); |
| 198 | |
| 199 | /* |
| 200 | * Definitions for the buffer hash lists. |
| 201 | */ |
| 202 | #define BUFHASH(dvp, lbn) \ |
| 203 | (&bufhashtbl[(((long)(dvp) >> 8) + (int)(lbn)) & bufhash]) |
| 204 | LIST_HEAD(bufhashhdr, buf) *bufhashtbl, invalhash; |
| 205 | u_long bufhash; |
| 206 | struct bqueue bufqueues[BQUEUES]; |
| 207 | |
| 208 | static kcondvar_t needbuffer_cv; |
| 209 | |
| 210 | /* |
| 211 | * Buffer queue lock. |
| 212 | */ |
| 213 | kmutex_t bufcache_lock; |
| 214 | kmutex_t buffer_lock; |
| 215 | |
| 216 | /* Software ISR for completed transfers. */ |
| 217 | static void *biodone_sih; |
| 218 | |
| 219 | /* Buffer pool for I/O buffers. */ |
| 220 | static pool_cache_t buf_cache; |
| 221 | static pool_cache_t bufio_cache; |
| 222 | |
| 223 | #define MEMPOOL_INDEX_OFFSET (ilog2(DEV_BSIZE)) /* smallest pool is 512 bytes */ |
| 224 | #define NMEMPOOLS (ilog2(MAXBSIZE) - MEMPOOL_INDEX_OFFSET + 1) |
| 225 | __CTASSERT((1 << (NMEMPOOLS + MEMPOOL_INDEX_OFFSET - 1)) == MAXBSIZE); |
| 226 | |
| 227 | /* Buffer memory pools */ |
| 228 | static struct pool bmempools[NMEMPOOLS]; |
| 229 | |
| 230 | static struct vm_map *buf_map; |
| 231 | |
| 232 | /* |
| 233 | * Buffer memory pool allocator. |
| 234 | */ |
| 235 | static void * |
| 236 | bufpool_page_alloc(struct pool *pp, int flags) |
| 237 | { |
| 238 | |
| 239 | return (void *)uvm_km_alloc(buf_map, |
| 240 | MAXBSIZE, MAXBSIZE, |
| 241 | ((flags & PR_WAITOK) ? 0 : UVM_KMF_NOWAIT|UVM_KMF_TRYLOCK) |
| 242 | | UVM_KMF_WIRED); |
| 243 | } |
| 244 | |
| 245 | static void |
| 246 | bufpool_page_free(struct pool *pp, void *v) |
| 247 | { |
| 248 | |
| 249 | uvm_km_free(buf_map, (vaddr_t)v, MAXBSIZE, UVM_KMF_WIRED); |
| 250 | } |
| 251 | |
| 252 | static struct pool_allocator bufmempool_allocator = { |
| 253 | .pa_alloc = bufpool_page_alloc, |
| 254 | .pa_free = bufpool_page_free, |
| 255 | .pa_pagesz = MAXBSIZE, |
| 256 | }; |
| 257 | |
| 258 | /* Buffer memory management variables */ |
| 259 | u_long bufmem_valimit; |
| 260 | u_long bufmem_hiwater; |
| 261 | u_long bufmem_lowater; |
| 262 | u_long bufmem; |
| 263 | |
| 264 | /* |
| 265 | * MD code can call this to set a hard limit on the amount |
| 266 | * of virtual memory used by the buffer cache. |
| 267 | */ |
| 268 | int |
| 269 | buf_setvalimit(vsize_t sz) |
| 270 | { |
| 271 | |
| 272 | /* We need to accommodate at least NMEMPOOLS of MAXBSIZE each */ |
| 273 | if (sz < NMEMPOOLS * MAXBSIZE) |
| 274 | return EINVAL; |
| 275 | |
| 276 | bufmem_valimit = sz; |
| 277 | return 0; |
| 278 | } |
| 279 | |
| 280 | static void |
| 281 | buf_setwm(void) |
| 282 | { |
| 283 | |
| 284 | bufmem_hiwater = buf_memcalc(); |
| 285 | /* lowater is approx. 2% of memory (with bufcache = 15) */ |
| 286 | #define BUFMEM_WMSHIFT 3 |
| 287 | #define BUFMEM_HIWMMIN (64 * 1024 << BUFMEM_WMSHIFT) |
| 288 | if (bufmem_hiwater < BUFMEM_HIWMMIN) |
| 289 | /* Ensure a reasonable minimum value */ |
| 290 | bufmem_hiwater = BUFMEM_HIWMMIN; |
| 291 | bufmem_lowater = bufmem_hiwater >> BUFMEM_WMSHIFT; |
| 292 | } |
| 293 | |
| 294 | #ifdef DEBUG |
| 295 | int debug_verify_freelist = 0; |
| 296 | static int |
| 297 | checkfreelist(buf_t *bp, struct bqueue *dp, int ison) |
| 298 | { |
| 299 | buf_t *b; |
| 300 | |
| 301 | if (!debug_verify_freelist) |
| 302 | return 1; |
| 303 | |
| 304 | TAILQ_FOREACH(b, &dp->bq_queue, b_freelist) { |
| 305 | if (b == bp) |
| 306 | return ison ? 1 : 0; |
| 307 | } |
| 308 | |
| 309 | return ison ? 0 : 1; |
| 310 | } |
| 311 | #endif |
| 312 | |
| 313 | /* |
| 314 | * Insq/Remq for the buffer hash lists. |
| 315 | * Call with buffer queue locked. |
| 316 | */ |
| 317 | static void |
| 318 | binsheadfree(buf_t *bp, struct bqueue *dp) |
| 319 | { |
| 320 | |
| 321 | KASSERT(mutex_owned(&bufcache_lock)); |
| 322 | KASSERT(bp->b_freelistindex == -1); |
| 323 | TAILQ_INSERT_HEAD(&dp->bq_queue, bp, b_freelist); |
| 324 | dp->bq_bytes += bp->b_bufsize; |
| 325 | bp->b_freelistindex = dp - bufqueues; |
| 326 | } |
| 327 | |
| 328 | static void |
| 329 | binstailfree(buf_t *bp, struct bqueue *dp) |
| 330 | { |
| 331 | |
| 332 | KASSERT(mutex_owned(&bufcache_lock)); |
| 333 | KASSERTMSG(bp->b_freelistindex == -1, "double free of buffer? " |
| 334 | "bp=%p, b_freelistindex=%d\n" , bp, bp->b_freelistindex); |
| 335 | TAILQ_INSERT_TAIL(&dp->bq_queue, bp, b_freelist); |
| 336 | dp->bq_bytes += bp->b_bufsize; |
| 337 | bp->b_freelistindex = dp - bufqueues; |
| 338 | } |
| 339 | |
| 340 | void |
| 341 | bremfree(buf_t *bp) |
| 342 | { |
| 343 | struct bqueue *dp; |
| 344 | int bqidx = bp->b_freelistindex; |
| 345 | |
| 346 | KASSERT(mutex_owned(&bufcache_lock)); |
| 347 | |
| 348 | KASSERT(bqidx != -1); |
| 349 | dp = &bufqueues[bqidx]; |
| 350 | KDASSERT(checkfreelist(bp, dp, 1)); |
| 351 | KASSERT(dp->bq_bytes >= bp->b_bufsize); |
| 352 | TAILQ_REMOVE(&dp->bq_queue, bp, b_freelist); |
| 353 | dp->bq_bytes -= bp->b_bufsize; |
| 354 | |
| 355 | /* For the sysctl helper. */ |
| 356 | if (bp == dp->bq_marker) |
| 357 | dp->bq_marker = NULL; |
| 358 | |
| 359 | #if defined(DIAGNOSTIC) |
| 360 | bp->b_freelistindex = -1; |
| 361 | #endif /* defined(DIAGNOSTIC) */ |
| 362 | } |
| 363 | |
| 364 | /* |
| 365 | * Add a reference to an buffer structure that came from buf_cache. |
| 366 | */ |
| 367 | static inline void |
| 368 | bref(buf_t *bp) |
| 369 | { |
| 370 | |
| 371 | KASSERT(mutex_owned(&bufcache_lock)); |
| 372 | KASSERT(bp->b_refcnt > 0); |
| 373 | |
| 374 | bp->b_refcnt++; |
| 375 | } |
| 376 | |
| 377 | /* |
| 378 | * Free an unused buffer structure that came from buf_cache. |
| 379 | */ |
| 380 | static inline void |
| 381 | brele(buf_t *bp) |
| 382 | { |
| 383 | |
| 384 | KASSERT(mutex_owned(&bufcache_lock)); |
| 385 | KASSERT(bp->b_refcnt > 0); |
| 386 | |
| 387 | if (bp->b_refcnt-- == 1) { |
| 388 | buf_destroy(bp); |
| 389 | #ifdef DEBUG |
| 390 | memset((char *)bp, 0, sizeof(*bp)); |
| 391 | #endif |
| 392 | pool_cache_put(buf_cache, bp); |
| 393 | } |
| 394 | } |
| 395 | |
| 396 | /* |
| 397 | * note that for some ports this is used by pmap bootstrap code to |
| 398 | * determine kva size. |
| 399 | */ |
| 400 | u_long |
| 401 | buf_memcalc(void) |
| 402 | { |
| 403 | u_long n; |
| 404 | vsize_t mapsz = 0; |
| 405 | |
| 406 | /* |
| 407 | * Determine the upper bound of memory to use for buffers. |
| 408 | * |
| 409 | * - If bufpages is specified, use that as the number |
| 410 | * pages. |
| 411 | * |
| 412 | * - Otherwise, use bufcache as the percentage of |
| 413 | * physical memory. |
| 414 | */ |
| 415 | if (bufpages != 0) { |
| 416 | n = bufpages; |
| 417 | } else { |
| 418 | if (bufcache < 5) { |
| 419 | printf("forcing bufcache %d -> 5" , bufcache); |
| 420 | bufcache = 5; |
| 421 | } |
| 422 | if (bufcache > 95) { |
| 423 | printf("forcing bufcache %d -> 95" , bufcache); |
| 424 | bufcache = 95; |
| 425 | } |
| 426 | if (buf_map != NULL) |
| 427 | mapsz = vm_map_max(buf_map) - vm_map_min(buf_map); |
| 428 | n = calc_cache_size(mapsz, bufcache, |
| 429 | (buf_map != kernel_map) ? 100 : BUFCACHE_VA_MAXPCT) |
| 430 | / PAGE_SIZE; |
| 431 | } |
| 432 | |
| 433 | n <<= PAGE_SHIFT; |
| 434 | if (bufmem_valimit != 0 && n > bufmem_valimit) |
| 435 | n = bufmem_valimit; |
| 436 | |
| 437 | return (n); |
| 438 | } |
| 439 | |
| 440 | /* |
| 441 | * Initialize buffers and hash links for buffers. |
| 442 | */ |
| 443 | void |
| 444 | bufinit(void) |
| 445 | { |
| 446 | struct bqueue *dp; |
| 447 | int use_std; |
| 448 | u_int i; |
| 449 | |
| 450 | biodone_vfs = biodone; |
| 451 | |
| 452 | mutex_init(&bufcache_lock, MUTEX_DEFAULT, IPL_NONE); |
| 453 | mutex_init(&buffer_lock, MUTEX_DEFAULT, IPL_NONE); |
| 454 | cv_init(&needbuffer_cv, "needbuf" ); |
| 455 | |
| 456 | if (bufmem_valimit != 0) { |
| 457 | vaddr_t minaddr = 0, maxaddr; |
| 458 | buf_map = uvm_km_suballoc(kernel_map, &minaddr, &maxaddr, |
| 459 | bufmem_valimit, 0, false, 0); |
| 460 | if (buf_map == NULL) |
| 461 | panic("bufinit: cannot allocate submap" ); |
| 462 | } else |
| 463 | buf_map = kernel_map; |
| 464 | |
| 465 | /* |
| 466 | * Initialize buffer cache memory parameters. |
| 467 | */ |
| 468 | bufmem = 0; |
| 469 | buf_setwm(); |
| 470 | |
| 471 | /* On "small" machines use small pool page sizes where possible */ |
| 472 | use_std = (physmem < atop(16*1024*1024)); |
| 473 | |
| 474 | /* |
| 475 | * Also use them on systems that can map the pool pages using |
| 476 | * a direct-mapped segment. |
| 477 | */ |
| 478 | #ifdef PMAP_MAP_POOLPAGE |
| 479 | use_std = 1; |
| 480 | #endif |
| 481 | |
| 482 | buf_cache = pool_cache_init(sizeof(buf_t), 0, 0, 0, |
| 483 | "bufpl" , NULL, IPL_SOFTBIO, NULL, NULL, NULL); |
| 484 | bufio_cache = pool_cache_init(sizeof(buf_t), 0, 0, 0, |
| 485 | "biopl" , NULL, IPL_BIO, NULL, NULL, NULL); |
| 486 | |
| 487 | for (i = 0; i < NMEMPOOLS; i++) { |
| 488 | struct pool_allocator *pa; |
| 489 | struct pool *pp = &bmempools[i]; |
| 490 | u_int size = 1 << (i + MEMPOOL_INDEX_OFFSET); |
| 491 | char *name = kmem_alloc(8, KM_SLEEP); /* XXX: never freed */ |
| 492 | if (__predict_false(size >= 1048576)) |
| 493 | (void)snprintf(name, 8, "buf%um" , size / 1048576); |
| 494 | else if (__predict_true(size >= 1024)) |
| 495 | (void)snprintf(name, 8, "buf%uk" , size / 1024); |
| 496 | else |
| 497 | (void)snprintf(name, 8, "buf%ub" , size); |
| 498 | pa = (size <= PAGE_SIZE && use_std) |
| 499 | ? &pool_allocator_nointr |
| 500 | : &bufmempool_allocator; |
| 501 | pool_init(pp, size, 0, 0, 0, name, pa, IPL_NONE); |
| 502 | pool_setlowat(pp, 1); |
| 503 | pool_sethiwat(pp, 1); |
| 504 | } |
| 505 | |
| 506 | /* Initialize the buffer queues */ |
| 507 | for (dp = bufqueues; dp < &bufqueues[BQUEUES]; dp++) { |
| 508 | TAILQ_INIT(&dp->bq_queue); |
| 509 | dp->bq_bytes = 0; |
| 510 | } |
| 511 | |
| 512 | /* |
| 513 | * Estimate hash table size based on the amount of memory we |
| 514 | * intend to use for the buffer cache. The average buffer |
| 515 | * size is dependent on our clients (i.e. filesystems). |
| 516 | * |
| 517 | * For now, use an empirical 3K per buffer. |
| 518 | */ |
| 519 | nbuf = (bufmem_hiwater / 1024) / 3; |
| 520 | bufhashtbl = hashinit(nbuf, HASH_LIST, true, &bufhash); |
| 521 | |
| 522 | sysctl_kern_buf_setup(); |
| 523 | sysctl_vm_buf_setup(); |
| 524 | } |
| 525 | |
| 526 | void |
| 527 | bufinit2(void) |
| 528 | { |
| 529 | |
| 530 | biodone_sih = softint_establish(SOFTINT_BIO | SOFTINT_MPSAFE, biointr, |
| 531 | NULL); |
| 532 | if (biodone_sih == NULL) |
| 533 | panic("bufinit2: can't establish soft interrupt" ); |
| 534 | } |
| 535 | |
| 536 | static int |
| 537 | buf_lotsfree(void) |
| 538 | { |
| 539 | u_long guess; |
| 540 | |
| 541 | /* Always allocate if less than the low water mark. */ |
| 542 | if (bufmem < bufmem_lowater) |
| 543 | return 1; |
| 544 | |
| 545 | /* Never allocate if greater than the high water mark. */ |
| 546 | if (bufmem > bufmem_hiwater) |
| 547 | return 0; |
| 548 | |
| 549 | /* If there's anything on the AGE list, it should be eaten. */ |
| 550 | if (TAILQ_FIRST(&bufqueues[BQ_AGE].bq_queue) != NULL) |
| 551 | return 0; |
| 552 | |
| 553 | /* |
| 554 | * The probabily of getting a new allocation is inversely |
| 555 | * proportional to the current size of the cache above |
| 556 | * the low water mark. Divide the total first to avoid overflows |
| 557 | * in the product. |
| 558 | */ |
| 559 | guess = cprng_fast32() % 16; |
| 560 | |
| 561 | if ((bufmem_hiwater - bufmem_lowater) / 16 * guess >= |
| 562 | (bufmem - bufmem_lowater)) |
| 563 | return 1; |
| 564 | |
| 565 | /* Otherwise don't allocate. */ |
| 566 | return 0; |
| 567 | } |
| 568 | |
| 569 | /* |
| 570 | * Return estimate of bytes we think need to be |
| 571 | * released to help resolve low memory conditions. |
| 572 | * |
| 573 | * => called with bufcache_lock held. |
| 574 | */ |
| 575 | static int |
| 576 | buf_canrelease(void) |
| 577 | { |
| 578 | int pagedemand, ninvalid = 0; |
| 579 | |
| 580 | KASSERT(mutex_owned(&bufcache_lock)); |
| 581 | |
| 582 | if (bufmem < bufmem_lowater) |
| 583 | return 0; |
| 584 | |
| 585 | if (bufmem > bufmem_hiwater) |
| 586 | return bufmem - bufmem_hiwater; |
| 587 | |
| 588 | ninvalid += bufqueues[BQ_AGE].bq_bytes; |
| 589 | |
| 590 | pagedemand = uvmexp.freetarg - uvmexp.free; |
| 591 | if (pagedemand < 0) |
| 592 | return ninvalid; |
| 593 | return MAX(ninvalid, MIN(2 * MAXBSIZE, |
| 594 | MIN((bufmem - bufmem_lowater) / 16, pagedemand * PAGE_SIZE))); |
| 595 | } |
| 596 | |
| 597 | /* |
| 598 | * Buffer memory allocation helper functions |
| 599 | */ |
| 600 | static u_long |
| 601 | buf_mempoolidx(u_long size) |
| 602 | { |
| 603 | u_int n = 0; |
| 604 | |
| 605 | size -= 1; |
| 606 | size >>= MEMPOOL_INDEX_OFFSET; |
| 607 | while (size) { |
| 608 | size >>= 1; |
| 609 | n += 1; |
| 610 | } |
| 611 | if (n >= NMEMPOOLS) |
| 612 | panic("buf mem pool index %d" , n); |
| 613 | return n; |
| 614 | } |
| 615 | |
| 616 | static u_long |
| 617 | buf_roundsize(u_long size) |
| 618 | { |
| 619 | /* Round up to nearest power of 2 */ |
| 620 | return (1 << (buf_mempoolidx(size) + MEMPOOL_INDEX_OFFSET)); |
| 621 | } |
| 622 | |
| 623 | static void * |
| 624 | buf_alloc(size_t size) |
| 625 | { |
| 626 | u_int n = buf_mempoolidx(size); |
| 627 | void *addr; |
| 628 | |
| 629 | while (1) { |
| 630 | addr = pool_get(&bmempools[n], PR_NOWAIT); |
| 631 | if (addr != NULL) |
| 632 | break; |
| 633 | |
| 634 | /* No memory, see if we can free some. If so, try again */ |
| 635 | mutex_enter(&bufcache_lock); |
| 636 | if (buf_drain(1) > 0) { |
| 637 | mutex_exit(&bufcache_lock); |
| 638 | continue; |
| 639 | } |
| 640 | |
| 641 | if (curlwp == uvm.pagedaemon_lwp) { |
| 642 | mutex_exit(&bufcache_lock); |
| 643 | return NULL; |
| 644 | } |
| 645 | |
| 646 | /* Wait for buffers to arrive on the LRU queue */ |
| 647 | cv_timedwait(&needbuffer_cv, &bufcache_lock, hz / 4); |
| 648 | mutex_exit(&bufcache_lock); |
| 649 | } |
| 650 | |
| 651 | return addr; |
| 652 | } |
| 653 | |
| 654 | static void |
| 655 | buf_mrelease(void *addr, size_t size) |
| 656 | { |
| 657 | |
| 658 | pool_put(&bmempools[buf_mempoolidx(size)], addr); |
| 659 | } |
| 660 | |
| 661 | /* |
| 662 | * bread()/breadn() helper. |
| 663 | */ |
| 664 | static buf_t * |
| 665 | bio_doread(struct vnode *vp, daddr_t blkno, int size, int async) |
| 666 | { |
| 667 | buf_t *bp; |
| 668 | struct mount *mp; |
| 669 | |
| 670 | bp = getblk(vp, blkno, size, 0, 0); |
| 671 | |
| 672 | /* |
| 673 | * getblk() may return NULL if we are the pagedaemon. |
| 674 | */ |
| 675 | if (bp == NULL) { |
| 676 | KASSERT(curlwp == uvm.pagedaemon_lwp); |
| 677 | return NULL; |
| 678 | } |
| 679 | |
| 680 | /* |
| 681 | * If buffer does not have data valid, start a read. |
| 682 | * Note that if buffer is BC_INVAL, getblk() won't return it. |
| 683 | * Therefore, it's valid if its I/O has completed or been delayed. |
| 684 | */ |
| 685 | if (!ISSET(bp->b_oflags, (BO_DONE | BO_DELWRI))) { |
| 686 | /* Start I/O for the buffer. */ |
| 687 | SET(bp->b_flags, B_READ | async); |
| 688 | if (async) |
| 689 | BIO_SETPRIO(bp, BPRIO_TIMELIMITED); |
| 690 | else |
| 691 | BIO_SETPRIO(bp, BPRIO_TIMECRITICAL); |
| 692 | VOP_STRATEGY(vp, bp); |
| 693 | |
| 694 | /* Pay for the read. */ |
| 695 | curlwp->l_ru.ru_inblock++; |
| 696 | } else if (async) |
| 697 | brelse(bp, 0); |
| 698 | |
| 699 | if (vp->v_type == VBLK) |
| 700 | mp = spec_node_getmountedfs(vp); |
| 701 | else |
| 702 | mp = vp->v_mount; |
| 703 | |
| 704 | /* |
| 705 | * Collect statistics on synchronous and asynchronous reads. |
| 706 | * Reads from block devices are charged to their associated |
| 707 | * filesystem (if any). |
| 708 | */ |
| 709 | if (mp != NULL) { |
| 710 | if (async == 0) |
| 711 | mp->mnt_stat.f_syncreads++; |
| 712 | else |
| 713 | mp->mnt_stat.f_asyncreads++; |
| 714 | } |
| 715 | |
| 716 | return (bp); |
| 717 | } |
| 718 | |
| 719 | /* |
| 720 | * Read a disk block. |
| 721 | * This algorithm described in Bach (p.54). |
| 722 | */ |
| 723 | int |
| 724 | bread(struct vnode *vp, daddr_t blkno, int size, int flags, buf_t **bpp) |
| 725 | { |
| 726 | buf_t *bp; |
| 727 | int error; |
| 728 | |
| 729 | /* Get buffer for block. */ |
| 730 | bp = *bpp = bio_doread(vp, blkno, size, 0); |
| 731 | if (bp == NULL) |
| 732 | return ENOMEM; |
| 733 | |
| 734 | /* Wait for the read to complete, and return result. */ |
| 735 | error = biowait(bp); |
| 736 | if (error == 0 && (flags & B_MODIFY) != 0) |
| 737 | error = fscow_run(bp, true); |
| 738 | if (error) { |
| 739 | brelse(bp, 0); |
| 740 | *bpp = NULL; |
| 741 | } |
| 742 | |
| 743 | return error; |
| 744 | } |
| 745 | |
| 746 | /* |
| 747 | * Read-ahead multiple disk blocks. The first is sync, the rest async. |
| 748 | * Trivial modification to the breada algorithm presented in Bach (p.55). |
| 749 | */ |
| 750 | int |
| 751 | breadn(struct vnode *vp, daddr_t blkno, int size, daddr_t *rablks, |
| 752 | int *rasizes, int nrablks, int flags, buf_t **bpp) |
| 753 | { |
| 754 | buf_t *bp; |
| 755 | int error, i; |
| 756 | |
| 757 | bp = *bpp = bio_doread(vp, blkno, size, 0); |
| 758 | if (bp == NULL) |
| 759 | return ENOMEM; |
| 760 | |
| 761 | /* |
| 762 | * For each of the read-ahead blocks, start a read, if necessary. |
| 763 | */ |
| 764 | mutex_enter(&bufcache_lock); |
| 765 | for (i = 0; i < nrablks; i++) { |
| 766 | /* If it's in the cache, just go on to next one. */ |
| 767 | if (incore(vp, rablks[i])) |
| 768 | continue; |
| 769 | |
| 770 | /* Get a buffer for the read-ahead block */ |
| 771 | mutex_exit(&bufcache_lock); |
| 772 | (void) bio_doread(vp, rablks[i], rasizes[i], B_ASYNC); |
| 773 | mutex_enter(&bufcache_lock); |
| 774 | } |
| 775 | mutex_exit(&bufcache_lock); |
| 776 | |
| 777 | /* Otherwise, we had to start a read for it; wait until it's valid. */ |
| 778 | error = biowait(bp); |
| 779 | if (error == 0 && (flags & B_MODIFY) != 0) |
| 780 | error = fscow_run(bp, true); |
| 781 | if (error) { |
| 782 | brelse(bp, 0); |
| 783 | *bpp = NULL; |
| 784 | } |
| 785 | |
| 786 | return error; |
| 787 | } |
| 788 | |
| 789 | /* |
| 790 | * Block write. Described in Bach (p.56) |
| 791 | */ |
| 792 | int |
| 793 | bwrite(buf_t *bp) |
| 794 | { |
| 795 | int rv, sync, wasdelayed; |
| 796 | struct vnode *vp; |
| 797 | struct mount *mp; |
| 798 | |
| 799 | KASSERT(ISSET(bp->b_cflags, BC_BUSY)); |
| 800 | KASSERT(!cv_has_waiters(&bp->b_done)); |
| 801 | |
| 802 | vp = bp->b_vp; |
| 803 | |
| 804 | /* |
| 805 | * dholland 20160728 AFAICT vp==NULL must be impossible as it |
| 806 | * will crash upon reaching VOP_STRATEGY below... see further |
| 807 | * analysis on tech-kern. |
| 808 | */ |
| 809 | KASSERTMSG(vp != NULL, "bwrite given buffer with null vnode" ); |
| 810 | |
| 811 | if (vp != NULL) { |
| 812 | KASSERT(bp->b_objlock == vp->v_interlock); |
| 813 | if (vp->v_type == VBLK) |
| 814 | mp = spec_node_getmountedfs(vp); |
| 815 | else |
| 816 | mp = vp->v_mount; |
| 817 | } else { |
| 818 | mp = NULL; |
| 819 | } |
| 820 | |
| 821 | if (mp && mp->mnt_wapbl) { |
| 822 | if (bp->b_iodone != mp->mnt_wapbl_op->wo_wapbl_biodone) { |
| 823 | bdwrite(bp); |
| 824 | return 0; |
| 825 | } |
| 826 | } |
| 827 | |
| 828 | /* |
| 829 | * Remember buffer type, to switch on it later. If the write was |
| 830 | * synchronous, but the file system was mounted with MNT_ASYNC, |
| 831 | * convert it to a delayed write. |
| 832 | * XXX note that this relies on delayed tape writes being converted |
| 833 | * to async, not sync writes (which is safe, but ugly). |
| 834 | */ |
| 835 | sync = !ISSET(bp->b_flags, B_ASYNC); |
| 836 | if (sync && mp != NULL && ISSET(mp->mnt_flag, MNT_ASYNC)) { |
| 837 | bdwrite(bp); |
| 838 | return (0); |
| 839 | } |
| 840 | |
| 841 | /* |
| 842 | * Collect statistics on synchronous and asynchronous writes. |
| 843 | * Writes to block devices are charged to their associated |
| 844 | * filesystem (if any). |
| 845 | */ |
| 846 | if (mp != NULL) { |
| 847 | if (sync) |
| 848 | mp->mnt_stat.f_syncwrites++; |
| 849 | else |
| 850 | mp->mnt_stat.f_asyncwrites++; |
| 851 | } |
| 852 | |
| 853 | /* |
| 854 | * Pay for the I/O operation and make sure the buf is on the correct |
| 855 | * vnode queue. |
| 856 | */ |
| 857 | bp->b_error = 0; |
| 858 | wasdelayed = ISSET(bp->b_oflags, BO_DELWRI); |
| 859 | CLR(bp->b_flags, B_READ); |
| 860 | if (wasdelayed) { |
| 861 | mutex_enter(&bufcache_lock); |
| 862 | mutex_enter(bp->b_objlock); |
| 863 | CLR(bp->b_oflags, BO_DONE | BO_DELWRI); |
| 864 | reassignbuf(bp, bp->b_vp); |
| 865 | mutex_exit(&bufcache_lock); |
| 866 | } else { |
| 867 | curlwp->l_ru.ru_oublock++; |
| 868 | mutex_enter(bp->b_objlock); |
| 869 | CLR(bp->b_oflags, BO_DONE | BO_DELWRI); |
| 870 | } |
| 871 | if (vp != NULL) |
| 872 | vp->v_numoutput++; |
| 873 | mutex_exit(bp->b_objlock); |
| 874 | |
| 875 | /* Initiate disk write. */ |
| 876 | if (sync) |
| 877 | BIO_SETPRIO(bp, BPRIO_TIMECRITICAL); |
| 878 | else |
| 879 | BIO_SETPRIO(bp, BPRIO_TIMELIMITED); |
| 880 | |
| 881 | VOP_STRATEGY(vp, bp); |
| 882 | |
| 883 | if (sync) { |
| 884 | /* If I/O was synchronous, wait for it to complete. */ |
| 885 | rv = biowait(bp); |
| 886 | |
| 887 | /* Release the buffer. */ |
| 888 | brelse(bp, 0); |
| 889 | |
| 890 | return (rv); |
| 891 | } else { |
| 892 | return (0); |
| 893 | } |
| 894 | } |
| 895 | |
| 896 | int |
| 897 | vn_bwrite(void *v) |
| 898 | { |
| 899 | struct vop_bwrite_args *ap = v; |
| 900 | |
| 901 | return (bwrite(ap->a_bp)); |
| 902 | } |
| 903 | |
| 904 | /* |
| 905 | * Delayed write. |
| 906 | * |
| 907 | * The buffer is marked dirty, but is not queued for I/O. |
| 908 | * This routine should be used when the buffer is expected |
| 909 | * to be modified again soon, typically a small write that |
| 910 | * partially fills a buffer. |
| 911 | * |
| 912 | * NB: magnetic tapes cannot be delayed; they must be |
| 913 | * written in the order that the writes are requested. |
| 914 | * |
| 915 | * Described in Leffler, et al. (pp. 208-213). |
| 916 | */ |
| 917 | void |
| 918 | bdwrite(buf_t *bp) |
| 919 | { |
| 920 | |
| 921 | KASSERT(bp->b_vp == NULL || bp->b_vp->v_tag != VT_UFS || |
| 922 | bp->b_vp->v_type == VBLK || ISSET(bp->b_flags, B_COWDONE)); |
| 923 | KASSERT(ISSET(bp->b_cflags, BC_BUSY)); |
| 924 | KASSERT(!cv_has_waiters(&bp->b_done)); |
| 925 | |
| 926 | /* If this is a tape block, write the block now. */ |
| 927 | if (bdev_type(bp->b_dev) == D_TAPE) { |
| 928 | bawrite(bp); |
| 929 | return; |
| 930 | } |
| 931 | |
| 932 | if (wapbl_vphaswapbl(bp->b_vp)) { |
| 933 | struct mount *mp = wapbl_vptomp(bp->b_vp); |
| 934 | |
| 935 | if (bp->b_iodone != mp->mnt_wapbl_op->wo_wapbl_biodone) { |
| 936 | WAPBL_ADD_BUF(mp, bp); |
| 937 | } |
| 938 | } |
| 939 | |
| 940 | /* |
| 941 | * If the block hasn't been seen before: |
| 942 | * (1) Mark it as having been seen, |
| 943 | * (2) Charge for the write, |
| 944 | * (3) Make sure it's on its vnode's correct block list. |
| 945 | */ |
| 946 | KASSERT(bp->b_vp == NULL || bp->b_objlock == bp->b_vp->v_interlock); |
| 947 | |
| 948 | if (!ISSET(bp->b_oflags, BO_DELWRI)) { |
| 949 | mutex_enter(&bufcache_lock); |
| 950 | mutex_enter(bp->b_objlock); |
| 951 | SET(bp->b_oflags, BO_DELWRI); |
| 952 | curlwp->l_ru.ru_oublock++; |
| 953 | reassignbuf(bp, bp->b_vp); |
| 954 | mutex_exit(&bufcache_lock); |
| 955 | } else { |
| 956 | mutex_enter(bp->b_objlock); |
| 957 | } |
| 958 | /* Otherwise, the "write" is done, so mark and release the buffer. */ |
| 959 | CLR(bp->b_oflags, BO_DONE); |
| 960 | mutex_exit(bp->b_objlock); |
| 961 | |
| 962 | brelse(bp, 0); |
| 963 | } |
| 964 | |
| 965 | /* |
| 966 | * Asynchronous block write; just an asynchronous bwrite(). |
| 967 | */ |
| 968 | void |
| 969 | bawrite(buf_t *bp) |
| 970 | { |
| 971 | |
| 972 | KASSERT(ISSET(bp->b_cflags, BC_BUSY)); |
| 973 | KASSERT(bp->b_vp != NULL); |
| 974 | |
| 975 | SET(bp->b_flags, B_ASYNC); |
| 976 | VOP_BWRITE(bp->b_vp, bp); |
| 977 | } |
| 978 | |
| 979 | /* |
| 980 | * Release a buffer on to the free lists. |
| 981 | * Described in Bach (p. 46). |
| 982 | */ |
| 983 | void |
| 984 | brelsel(buf_t *bp, int set) |
| 985 | { |
| 986 | struct bqueue *bufq; |
| 987 | struct vnode *vp; |
| 988 | |
| 989 | KASSERT(bp != NULL); |
| 990 | KASSERT(mutex_owned(&bufcache_lock)); |
| 991 | KASSERT(!cv_has_waiters(&bp->b_done)); |
| 992 | KASSERT(bp->b_refcnt > 0); |
| 993 | |
| 994 | SET(bp->b_cflags, set); |
| 995 | |
| 996 | KASSERT(ISSET(bp->b_cflags, BC_BUSY)); |
| 997 | KASSERT(bp->b_iodone == NULL); |
| 998 | |
| 999 | /* Wake up any processes waiting for any buffer to become free. */ |
| 1000 | cv_signal(&needbuffer_cv); |
| 1001 | |
| 1002 | /* Wake up any proceeses waiting for _this_ buffer to become free */ |
| 1003 | if (ISSET(bp->b_cflags, BC_WANTED)) |
| 1004 | CLR(bp->b_cflags, BC_WANTED|BC_AGE); |
| 1005 | |
| 1006 | /* If it's clean clear the copy-on-write flag. */ |
| 1007 | if (ISSET(bp->b_flags, B_COWDONE)) { |
| 1008 | mutex_enter(bp->b_objlock); |
| 1009 | if (!ISSET(bp->b_oflags, BO_DELWRI)) |
| 1010 | CLR(bp->b_flags, B_COWDONE); |
| 1011 | mutex_exit(bp->b_objlock); |
| 1012 | } |
| 1013 | |
| 1014 | /* |
| 1015 | * Determine which queue the buffer should be on, then put it there. |
| 1016 | */ |
| 1017 | |
| 1018 | /* If it's locked, don't report an error; try again later. */ |
| 1019 | if (ISSET(bp->b_flags, B_LOCKED)) |
| 1020 | bp->b_error = 0; |
| 1021 | |
| 1022 | /* If it's not cacheable, or an error, mark it invalid. */ |
| 1023 | if (ISSET(bp->b_cflags, BC_NOCACHE) || bp->b_error != 0) |
| 1024 | SET(bp->b_cflags, BC_INVAL); |
| 1025 | |
| 1026 | if (ISSET(bp->b_cflags, BC_VFLUSH)) { |
| 1027 | /* |
| 1028 | * This is a delayed write buffer that was just flushed to |
| 1029 | * disk. It is still on the LRU queue. If it's become |
| 1030 | * invalid, then we need to move it to a different queue; |
| 1031 | * otherwise leave it in its current position. |
| 1032 | */ |
| 1033 | CLR(bp->b_cflags, BC_VFLUSH); |
| 1034 | if (!ISSET(bp->b_cflags, BC_INVAL|BC_AGE) && |
| 1035 | !ISSET(bp->b_flags, B_LOCKED) && bp->b_error == 0) { |
| 1036 | KDASSERT(checkfreelist(bp, &bufqueues[BQ_LRU], 1)); |
| 1037 | goto already_queued; |
| 1038 | } else { |
| 1039 | bremfree(bp); |
| 1040 | } |
| 1041 | } |
| 1042 | |
| 1043 | KDASSERT(checkfreelist(bp, &bufqueues[BQ_AGE], 0)); |
| 1044 | KDASSERT(checkfreelist(bp, &bufqueues[BQ_LRU], 0)); |
| 1045 | KDASSERT(checkfreelist(bp, &bufqueues[BQ_LOCKED], 0)); |
| 1046 | |
| 1047 | if ((bp->b_bufsize <= 0) || ISSET(bp->b_cflags, BC_INVAL)) { |
| 1048 | /* |
| 1049 | * If it's invalid or empty, dissociate it from its vnode |
| 1050 | * and put on the head of the appropriate queue. |
| 1051 | */ |
| 1052 | if (ISSET(bp->b_flags, B_LOCKED)) { |
| 1053 | if (wapbl_vphaswapbl(vp = bp->b_vp)) { |
| 1054 | struct mount *mp = wapbl_vptomp(vp); |
| 1055 | |
| 1056 | KASSERT(bp->b_iodone |
| 1057 | != mp->mnt_wapbl_op->wo_wapbl_biodone); |
| 1058 | WAPBL_REMOVE_BUF(mp, bp); |
| 1059 | } |
| 1060 | } |
| 1061 | |
| 1062 | mutex_enter(bp->b_objlock); |
| 1063 | CLR(bp->b_oflags, BO_DONE|BO_DELWRI); |
| 1064 | if ((vp = bp->b_vp) != NULL) { |
| 1065 | KASSERT(bp->b_objlock == vp->v_interlock); |
| 1066 | reassignbuf(bp, bp->b_vp); |
| 1067 | brelvp(bp); |
| 1068 | mutex_exit(vp->v_interlock); |
| 1069 | } else { |
| 1070 | KASSERT(bp->b_objlock == &buffer_lock); |
| 1071 | mutex_exit(bp->b_objlock); |
| 1072 | } |
| 1073 | |
| 1074 | if (bp->b_bufsize <= 0) |
| 1075 | /* no data */ |
| 1076 | goto already_queued; |
| 1077 | else |
| 1078 | /* invalid data */ |
| 1079 | bufq = &bufqueues[BQ_AGE]; |
| 1080 | binsheadfree(bp, bufq); |
| 1081 | } else { |
| 1082 | /* |
| 1083 | * It has valid data. Put it on the end of the appropriate |
| 1084 | * queue, so that it'll stick around for as long as possible. |
| 1085 | * If buf is AGE, but has dependencies, must put it on last |
| 1086 | * bufqueue to be scanned, ie LRU. This protects against the |
| 1087 | * livelock where BQ_AGE only has buffers with dependencies, |
| 1088 | * and we thus never get to the dependent buffers in BQ_LRU. |
| 1089 | */ |
| 1090 | if (ISSET(bp->b_flags, B_LOCKED)) { |
| 1091 | /* locked in core */ |
| 1092 | bufq = &bufqueues[BQ_LOCKED]; |
| 1093 | } else if (!ISSET(bp->b_cflags, BC_AGE)) { |
| 1094 | /* valid data */ |
| 1095 | bufq = &bufqueues[BQ_LRU]; |
| 1096 | } else { |
| 1097 | /* stale but valid data */ |
| 1098 | bufq = &bufqueues[BQ_AGE]; |
| 1099 | } |
| 1100 | binstailfree(bp, bufq); |
| 1101 | } |
| 1102 | already_queued: |
| 1103 | /* Unlock the buffer. */ |
| 1104 | CLR(bp->b_cflags, BC_AGE|BC_BUSY|BC_NOCACHE); |
| 1105 | CLR(bp->b_flags, B_ASYNC); |
| 1106 | cv_broadcast(&bp->b_busy); |
| 1107 | |
| 1108 | if (bp->b_bufsize <= 0) |
| 1109 | brele(bp); |
| 1110 | } |
| 1111 | |
| 1112 | void |
| 1113 | brelse(buf_t *bp, int set) |
| 1114 | { |
| 1115 | |
| 1116 | mutex_enter(&bufcache_lock); |
| 1117 | brelsel(bp, set); |
| 1118 | mutex_exit(&bufcache_lock); |
| 1119 | } |
| 1120 | |
| 1121 | /* |
| 1122 | * Determine if a block is in the cache. |
| 1123 | * Just look on what would be its hash chain. If it's there, return |
| 1124 | * a pointer to it, unless it's marked invalid. If it's marked invalid, |
| 1125 | * we normally don't return the buffer, unless the caller explicitly |
| 1126 | * wants us to. |
| 1127 | */ |
| 1128 | buf_t * |
| 1129 | incore(struct vnode *vp, daddr_t blkno) |
| 1130 | { |
| 1131 | buf_t *bp; |
| 1132 | |
| 1133 | KASSERT(mutex_owned(&bufcache_lock)); |
| 1134 | |
| 1135 | /* Search hash chain */ |
| 1136 | LIST_FOREACH(bp, BUFHASH(vp, blkno), b_hash) { |
| 1137 | if (bp->b_lblkno == blkno && bp->b_vp == vp && |
| 1138 | !ISSET(bp->b_cflags, BC_INVAL)) { |
| 1139 | KASSERT(bp->b_objlock == vp->v_interlock); |
| 1140 | return (bp); |
| 1141 | } |
| 1142 | } |
| 1143 | |
| 1144 | return (NULL); |
| 1145 | } |
| 1146 | |
| 1147 | /* |
| 1148 | * Get a block of requested size that is associated with |
| 1149 | * a given vnode and block offset. If it is found in the |
| 1150 | * block cache, mark it as having been found, make it busy |
| 1151 | * and return it. Otherwise, return an empty block of the |
| 1152 | * correct size. It is up to the caller to insure that the |
| 1153 | * cached blocks be of the correct size. |
| 1154 | */ |
| 1155 | buf_t * |
| 1156 | getblk(struct vnode *vp, daddr_t blkno, int size, int slpflag, int slptimeo) |
| 1157 | { |
| 1158 | int err, preserve; |
| 1159 | buf_t *bp; |
| 1160 | |
| 1161 | mutex_enter(&bufcache_lock); |
| 1162 | loop: |
| 1163 | bp = incore(vp, blkno); |
| 1164 | if (bp != NULL) { |
| 1165 | err = bbusy(bp, ((slpflag & PCATCH) != 0), slptimeo, NULL); |
| 1166 | if (err != 0) { |
| 1167 | if (err == EPASSTHROUGH) |
| 1168 | goto loop; |
| 1169 | mutex_exit(&bufcache_lock); |
| 1170 | return (NULL); |
| 1171 | } |
| 1172 | KASSERT(!cv_has_waiters(&bp->b_done)); |
| 1173 | #ifdef DIAGNOSTIC |
| 1174 | if (ISSET(bp->b_oflags, BO_DONE|BO_DELWRI) && |
| 1175 | bp->b_bcount < size && vp->v_type != VBLK) |
| 1176 | panic("getblk: block size invariant failed" ); |
| 1177 | #endif |
| 1178 | bremfree(bp); |
| 1179 | preserve = 1; |
| 1180 | } else { |
| 1181 | if ((bp = getnewbuf(slpflag, slptimeo, 0)) == NULL) |
| 1182 | goto loop; |
| 1183 | |
| 1184 | if (incore(vp, blkno) != NULL) { |
| 1185 | /* The block has come into memory in the meantime. */ |
| 1186 | brelsel(bp, 0); |
| 1187 | goto loop; |
| 1188 | } |
| 1189 | |
| 1190 | LIST_INSERT_HEAD(BUFHASH(vp, blkno), bp, b_hash); |
| 1191 | bp->b_blkno = bp->b_lblkno = bp->b_rawblkno = blkno; |
| 1192 | mutex_enter(vp->v_interlock); |
| 1193 | bgetvp(vp, bp); |
| 1194 | mutex_exit(vp->v_interlock); |
| 1195 | preserve = 0; |
| 1196 | } |
| 1197 | mutex_exit(&bufcache_lock); |
| 1198 | |
| 1199 | /* |
| 1200 | * LFS can't track total size of B_LOCKED buffer (locked_queue_bytes) |
| 1201 | * if we re-size buffers here. |
| 1202 | */ |
| 1203 | if (ISSET(bp->b_flags, B_LOCKED)) { |
| 1204 | KASSERT(bp->b_bufsize >= size); |
| 1205 | } else { |
| 1206 | if (allocbuf(bp, size, preserve)) { |
| 1207 | mutex_enter(&bufcache_lock); |
| 1208 | LIST_REMOVE(bp, b_hash); |
| 1209 | mutex_exit(&bufcache_lock); |
| 1210 | brelse(bp, BC_INVAL); |
| 1211 | return NULL; |
| 1212 | } |
| 1213 | } |
| 1214 | BIO_SETPRIO(bp, BPRIO_DEFAULT); |
| 1215 | return (bp); |
| 1216 | } |
| 1217 | |
| 1218 | /* |
| 1219 | * Get an empty, disassociated buffer of given size. |
| 1220 | */ |
| 1221 | buf_t * |
| 1222 | geteblk(int size) |
| 1223 | { |
| 1224 | buf_t *bp; |
| 1225 | int error __diagused; |
| 1226 | |
| 1227 | mutex_enter(&bufcache_lock); |
| 1228 | while ((bp = getnewbuf(0, 0, 0)) == NULL) |
| 1229 | ; |
| 1230 | |
| 1231 | SET(bp->b_cflags, BC_INVAL); |
| 1232 | LIST_INSERT_HEAD(&invalhash, bp, b_hash); |
| 1233 | mutex_exit(&bufcache_lock); |
| 1234 | BIO_SETPRIO(bp, BPRIO_DEFAULT); |
| 1235 | error = allocbuf(bp, size, 0); |
| 1236 | KASSERT(error == 0); |
| 1237 | return (bp); |
| 1238 | } |
| 1239 | |
| 1240 | /* |
| 1241 | * Expand or contract the actual memory allocated to a buffer. |
| 1242 | * |
| 1243 | * If the buffer shrinks, data is lost, so it's up to the |
| 1244 | * caller to have written it out *first*; this routine will not |
| 1245 | * start a write. If the buffer grows, it's the callers |
| 1246 | * responsibility to fill out the buffer's additional contents. |
| 1247 | */ |
| 1248 | int |
| 1249 | allocbuf(buf_t *bp, int size, int preserve) |
| 1250 | { |
| 1251 | void *addr; |
| 1252 | vsize_t oldsize, desired_size; |
| 1253 | int oldcount; |
| 1254 | int delta; |
| 1255 | |
| 1256 | desired_size = buf_roundsize(size); |
| 1257 | if (desired_size > MAXBSIZE) |
| 1258 | printf("allocbuf: buffer larger than MAXBSIZE requested" ); |
| 1259 | |
| 1260 | oldcount = bp->b_bcount; |
| 1261 | |
| 1262 | bp->b_bcount = size; |
| 1263 | |
| 1264 | oldsize = bp->b_bufsize; |
| 1265 | if (oldsize == desired_size) { |
| 1266 | /* |
| 1267 | * Do not short cut the WAPBL resize, as the buffer length |
| 1268 | * could still have changed and this would corrupt the |
| 1269 | * tracking of the transaction length. |
| 1270 | */ |
| 1271 | goto out; |
| 1272 | } |
| 1273 | |
| 1274 | /* |
| 1275 | * If we want a buffer of a different size, re-allocate the |
| 1276 | * buffer's memory; copy old content only if needed. |
| 1277 | */ |
| 1278 | addr = buf_alloc(desired_size); |
| 1279 | if (addr == NULL) |
| 1280 | return ENOMEM; |
| 1281 | if (preserve) |
| 1282 | memcpy(addr, bp->b_data, MIN(oldsize,desired_size)); |
| 1283 | if (bp->b_data != NULL) |
| 1284 | buf_mrelease(bp->b_data, oldsize); |
| 1285 | bp->b_data = addr; |
| 1286 | bp->b_bufsize = desired_size; |
| 1287 | |
| 1288 | /* |
| 1289 | * Update overall buffer memory counter (protected by bufcache_lock) |
| 1290 | */ |
| 1291 | delta = (long)desired_size - (long)oldsize; |
| 1292 | |
| 1293 | mutex_enter(&bufcache_lock); |
| 1294 | if ((bufmem += delta) > bufmem_hiwater) { |
| 1295 | /* |
| 1296 | * Need to trim overall memory usage. |
| 1297 | */ |
| 1298 | while (buf_canrelease()) { |
| 1299 | if (curcpu()->ci_schedstate.spc_flags & |
| 1300 | SPCF_SHOULDYIELD) { |
| 1301 | mutex_exit(&bufcache_lock); |
| 1302 | preempt(); |
| 1303 | mutex_enter(&bufcache_lock); |
| 1304 | } |
| 1305 | if (buf_trim() == 0) |
| 1306 | break; |
| 1307 | } |
| 1308 | } |
| 1309 | mutex_exit(&bufcache_lock); |
| 1310 | |
| 1311 | out: |
| 1312 | if (wapbl_vphaswapbl(bp->b_vp)) |
| 1313 | WAPBL_RESIZE_BUF(wapbl_vptomp(bp->b_vp), bp, oldsize, oldcount); |
| 1314 | |
| 1315 | return 0; |
| 1316 | } |
| 1317 | |
| 1318 | /* |
| 1319 | * Find a buffer which is available for use. |
| 1320 | * Select something from a free list. |
| 1321 | * Preference is to AGE list, then LRU list. |
| 1322 | * |
| 1323 | * Called with the buffer queues locked. |
| 1324 | * Return buffer locked. |
| 1325 | */ |
| 1326 | buf_t * |
| 1327 | getnewbuf(int slpflag, int slptimeo, int from_bufq) |
| 1328 | { |
| 1329 | buf_t *bp; |
| 1330 | struct vnode *vp; |
| 1331 | |
| 1332 | start: |
| 1333 | KASSERT(mutex_owned(&bufcache_lock)); |
| 1334 | |
| 1335 | /* |
| 1336 | * Get a new buffer from the pool. |
| 1337 | */ |
| 1338 | if (!from_bufq && buf_lotsfree()) { |
| 1339 | mutex_exit(&bufcache_lock); |
| 1340 | bp = pool_cache_get(buf_cache, PR_NOWAIT); |
| 1341 | if (bp != NULL) { |
| 1342 | memset((char *)bp, 0, sizeof(*bp)); |
| 1343 | buf_init(bp); |
| 1344 | SET(bp->b_cflags, BC_BUSY); /* mark buffer busy */ |
| 1345 | mutex_enter(&bufcache_lock); |
| 1346 | #if defined(DIAGNOSTIC) |
| 1347 | bp->b_freelistindex = -1; |
| 1348 | #endif /* defined(DIAGNOSTIC) */ |
| 1349 | return (bp); |
| 1350 | } |
| 1351 | mutex_enter(&bufcache_lock); |
| 1352 | } |
| 1353 | |
| 1354 | KASSERT(mutex_owned(&bufcache_lock)); |
| 1355 | if ((bp = TAILQ_FIRST(&bufqueues[BQ_AGE].bq_queue)) != NULL || |
| 1356 | (bp = TAILQ_FIRST(&bufqueues[BQ_LRU].bq_queue)) != NULL) { |
| 1357 | KASSERT(!ISSET(bp->b_cflags, BC_BUSY) || ISSET(bp->b_cflags, BC_VFLUSH)); |
| 1358 | bremfree(bp); |
| 1359 | |
| 1360 | /* Buffer is no longer on free lists. */ |
| 1361 | SET(bp->b_cflags, BC_BUSY); |
| 1362 | } else { |
| 1363 | /* |
| 1364 | * XXX: !from_bufq should be removed. |
| 1365 | */ |
| 1366 | if (!from_bufq || curlwp != uvm.pagedaemon_lwp) { |
| 1367 | /* wait for a free buffer of any kind */ |
| 1368 | if ((slpflag & PCATCH) != 0) |
| 1369 | (void)cv_timedwait_sig(&needbuffer_cv, |
| 1370 | &bufcache_lock, slptimeo); |
| 1371 | else |
| 1372 | (void)cv_timedwait(&needbuffer_cv, |
| 1373 | &bufcache_lock, slptimeo); |
| 1374 | } |
| 1375 | return (NULL); |
| 1376 | } |
| 1377 | |
| 1378 | #ifdef DIAGNOSTIC |
| 1379 | if (bp->b_bufsize <= 0) |
| 1380 | panic("buffer %p: on queue but empty" , bp); |
| 1381 | #endif |
| 1382 | |
| 1383 | if (ISSET(bp->b_cflags, BC_VFLUSH)) { |
| 1384 | /* |
| 1385 | * This is a delayed write buffer being flushed to disk. Make |
| 1386 | * sure it gets aged out of the queue when it's finished, and |
| 1387 | * leave it off the LRU queue. |
| 1388 | */ |
| 1389 | CLR(bp->b_cflags, BC_VFLUSH); |
| 1390 | SET(bp->b_cflags, BC_AGE); |
| 1391 | goto start; |
| 1392 | } |
| 1393 | |
| 1394 | KASSERT(ISSET(bp->b_cflags, BC_BUSY)); |
| 1395 | KASSERT(bp->b_refcnt > 0); |
| 1396 | KASSERT(!cv_has_waiters(&bp->b_done)); |
| 1397 | |
| 1398 | /* |
| 1399 | * If buffer was a delayed write, start it and return NULL |
| 1400 | * (since we might sleep while starting the write). |
| 1401 | */ |
| 1402 | if (ISSET(bp->b_oflags, BO_DELWRI)) { |
| 1403 | /* |
| 1404 | * This buffer has gone through the LRU, so make sure it gets |
| 1405 | * reused ASAP. |
| 1406 | */ |
| 1407 | SET(bp->b_cflags, BC_AGE); |
| 1408 | mutex_exit(&bufcache_lock); |
| 1409 | bawrite(bp); |
| 1410 | mutex_enter(&bufcache_lock); |
| 1411 | return (NULL); |
| 1412 | } |
| 1413 | |
| 1414 | vp = bp->b_vp; |
| 1415 | |
| 1416 | /* clear out various other fields */ |
| 1417 | bp->b_cflags = BC_BUSY; |
| 1418 | bp->b_oflags = 0; |
| 1419 | bp->b_flags = 0; |
| 1420 | bp->b_dev = NODEV; |
| 1421 | bp->b_blkno = 0; |
| 1422 | bp->b_lblkno = 0; |
| 1423 | bp->b_rawblkno = 0; |
| 1424 | bp->b_iodone = 0; |
| 1425 | bp->b_error = 0; |
| 1426 | bp->b_resid = 0; |
| 1427 | bp->b_bcount = 0; |
| 1428 | |
| 1429 | LIST_REMOVE(bp, b_hash); |
| 1430 | |
| 1431 | /* Disassociate us from our vnode, if we had one... */ |
| 1432 | if (vp != NULL) { |
| 1433 | mutex_enter(vp->v_interlock); |
| 1434 | brelvp(bp); |
| 1435 | mutex_exit(vp->v_interlock); |
| 1436 | } |
| 1437 | |
| 1438 | return (bp); |
| 1439 | } |
| 1440 | |
| 1441 | /* |
| 1442 | * Attempt to free an aged buffer off the queues. |
| 1443 | * Called with queue lock held. |
| 1444 | * Returns the amount of buffer memory freed. |
| 1445 | */ |
| 1446 | static int |
| 1447 | buf_trim(void) |
| 1448 | { |
| 1449 | buf_t *bp; |
| 1450 | long size; |
| 1451 | |
| 1452 | KASSERT(mutex_owned(&bufcache_lock)); |
| 1453 | |
| 1454 | /* Instruct getnewbuf() to get buffers off the queues */ |
| 1455 | if ((bp = getnewbuf(PCATCH, 1, 1)) == NULL) |
| 1456 | return 0; |
| 1457 | |
| 1458 | KASSERT((bp->b_cflags & BC_WANTED) == 0); |
| 1459 | size = bp->b_bufsize; |
| 1460 | bufmem -= size; |
| 1461 | if (size > 0) { |
| 1462 | buf_mrelease(bp->b_data, size); |
| 1463 | bp->b_bcount = bp->b_bufsize = 0; |
| 1464 | } |
| 1465 | /* brelse() will return the buffer to the global buffer pool */ |
| 1466 | brelsel(bp, 0); |
| 1467 | return size; |
| 1468 | } |
| 1469 | |
| 1470 | int |
| 1471 | buf_drain(int n) |
| 1472 | { |
| 1473 | int size = 0, sz; |
| 1474 | |
| 1475 | KASSERT(mutex_owned(&bufcache_lock)); |
| 1476 | |
| 1477 | while (size < n && bufmem > bufmem_lowater) { |
| 1478 | sz = buf_trim(); |
| 1479 | if (sz <= 0) |
| 1480 | break; |
| 1481 | size += sz; |
| 1482 | } |
| 1483 | |
| 1484 | return size; |
| 1485 | } |
| 1486 | |
| 1487 | SDT_PROVIDER_DEFINE(io); |
| 1488 | |
| 1489 | SDT_PROBE_DEFINE1(io, kernel, , wait__start, "struct buf *" /*bp*/); |
| 1490 | SDT_PROBE_DEFINE1(io, kernel, , wait__done, "struct buf *" /*bp*/); |
| 1491 | |
| 1492 | /* |
| 1493 | * Wait for operations on the buffer to complete. |
| 1494 | * When they do, extract and return the I/O's error value. |
| 1495 | */ |
| 1496 | int |
| 1497 | biowait(buf_t *bp) |
| 1498 | { |
| 1499 | |
| 1500 | KASSERT(ISSET(bp->b_cflags, BC_BUSY)); |
| 1501 | KASSERT(bp->b_refcnt > 0); |
| 1502 | |
| 1503 | SDT_PROBE1(io, kernel, , wait__start, bp); |
| 1504 | |
| 1505 | mutex_enter(bp->b_objlock); |
| 1506 | while (!ISSET(bp->b_oflags, BO_DONE | BO_DELWRI)) |
| 1507 | cv_wait(&bp->b_done, bp->b_objlock); |
| 1508 | mutex_exit(bp->b_objlock); |
| 1509 | |
| 1510 | SDT_PROBE1(io, kernel, , wait__done, bp); |
| 1511 | |
| 1512 | return bp->b_error; |
| 1513 | } |
| 1514 | |
| 1515 | /* |
| 1516 | * Mark I/O complete on a buffer. |
| 1517 | * |
| 1518 | * If a callback has been requested, e.g. the pageout |
| 1519 | * daemon, do so. Otherwise, awaken waiting processes. |
| 1520 | * |
| 1521 | * [ Leffler, et al., says on p.247: |
| 1522 | * "This routine wakes up the blocked process, frees the buffer |
| 1523 | * for an asynchronous write, or, for a request by the pagedaemon |
| 1524 | * process, invokes a procedure specified in the buffer structure" ] |
| 1525 | * |
| 1526 | * In real life, the pagedaemon (or other system processes) wants |
| 1527 | * to do async stuff to, and doesn't want the buffer brelse()'d. |
| 1528 | * (for swap pager, that puts swap buffers on the free lists (!!!), |
| 1529 | * for the vn device, that puts allocated buffers on the free lists!) |
| 1530 | */ |
| 1531 | void |
| 1532 | biodone(buf_t *bp) |
| 1533 | { |
| 1534 | int s; |
| 1535 | |
| 1536 | KASSERT(!ISSET(bp->b_oflags, BO_DONE)); |
| 1537 | |
| 1538 | if (cpu_intr_p()) { |
| 1539 | /* From interrupt mode: defer to a soft interrupt. */ |
| 1540 | s = splvm(); |
| 1541 | TAILQ_INSERT_TAIL(&curcpu()->ci_data.cpu_biodone, bp, b_actq); |
| 1542 | softint_schedule(biodone_sih); |
| 1543 | splx(s); |
| 1544 | } else { |
| 1545 | /* Process now - the buffer may be freed soon. */ |
| 1546 | biodone2(bp); |
| 1547 | } |
| 1548 | } |
| 1549 | |
| 1550 | SDT_PROBE_DEFINE1(io, kernel, , done, "struct buf *" /*bp*/); |
| 1551 | |
| 1552 | static void |
| 1553 | biodone2(buf_t *bp) |
| 1554 | { |
| 1555 | void (*callout)(buf_t *); |
| 1556 | |
| 1557 | SDT_PROBE1(io, kernel, ,done, bp); |
| 1558 | |
| 1559 | mutex_enter(bp->b_objlock); |
| 1560 | /* Note that the transfer is done. */ |
| 1561 | if (ISSET(bp->b_oflags, BO_DONE)) |
| 1562 | panic("biodone2 already" ); |
| 1563 | CLR(bp->b_flags, B_COWDONE); |
| 1564 | SET(bp->b_oflags, BO_DONE); |
| 1565 | BIO_SETPRIO(bp, BPRIO_DEFAULT); |
| 1566 | |
| 1567 | /* Wake up waiting writers. */ |
| 1568 | if (!ISSET(bp->b_flags, B_READ)) |
| 1569 | vwakeup(bp); |
| 1570 | |
| 1571 | if ((callout = bp->b_iodone) != NULL) { |
| 1572 | /* Note callout done, then call out. */ |
| 1573 | KASSERT(!cv_has_waiters(&bp->b_done)); |
| 1574 | KERNEL_LOCK(1, NULL); /* XXXSMP */ |
| 1575 | bp->b_iodone = NULL; |
| 1576 | mutex_exit(bp->b_objlock); |
| 1577 | (*callout)(bp); |
| 1578 | KERNEL_UNLOCK_ONE(NULL); /* XXXSMP */ |
| 1579 | } else if (ISSET(bp->b_flags, B_ASYNC)) { |
| 1580 | /* If async, release. */ |
| 1581 | KASSERT(!cv_has_waiters(&bp->b_done)); |
| 1582 | mutex_exit(bp->b_objlock); |
| 1583 | brelse(bp, 0); |
| 1584 | } else { |
| 1585 | /* Otherwise just wake up waiters in biowait(). */ |
| 1586 | cv_broadcast(&bp->b_done); |
| 1587 | mutex_exit(bp->b_objlock); |
| 1588 | } |
| 1589 | } |
| 1590 | |
| 1591 | static void |
| 1592 | biointr(void *cookie) |
| 1593 | { |
| 1594 | struct cpu_info *ci; |
| 1595 | buf_t *bp; |
| 1596 | int s; |
| 1597 | |
| 1598 | ci = curcpu(); |
| 1599 | |
| 1600 | while (!TAILQ_EMPTY(&ci->ci_data.cpu_biodone)) { |
| 1601 | KASSERT(curcpu() == ci); |
| 1602 | |
| 1603 | s = splvm(); |
| 1604 | bp = TAILQ_FIRST(&ci->ci_data.cpu_biodone); |
| 1605 | TAILQ_REMOVE(&ci->ci_data.cpu_biodone, bp, b_actq); |
| 1606 | splx(s); |
| 1607 | |
| 1608 | biodone2(bp); |
| 1609 | } |
| 1610 | } |
| 1611 | |
| 1612 | /* |
| 1613 | * Wait for all buffers to complete I/O |
| 1614 | * Return the number of "stuck" buffers. |
| 1615 | */ |
| 1616 | int |
| 1617 | buf_syncwait(void) |
| 1618 | { |
| 1619 | buf_t *bp; |
| 1620 | int iter, nbusy, nbusy_prev = 0, ihash; |
| 1621 | |
| 1622 | for (iter = 0; iter < 20;) { |
| 1623 | mutex_enter(&bufcache_lock); |
| 1624 | nbusy = 0; |
| 1625 | for (ihash = 0; ihash < bufhash+1; ihash++) { |
| 1626 | LIST_FOREACH(bp, &bufhashtbl[ihash], b_hash) { |
| 1627 | if ((bp->b_cflags & (BC_BUSY|BC_INVAL)) == BC_BUSY) |
| 1628 | nbusy += ((bp->b_flags & B_READ) == 0); |
| 1629 | } |
| 1630 | } |
| 1631 | mutex_exit(&bufcache_lock); |
| 1632 | |
| 1633 | if (nbusy == 0) |
| 1634 | break; |
| 1635 | if (nbusy_prev == 0) |
| 1636 | nbusy_prev = nbusy; |
| 1637 | printf("%d " , nbusy); |
| 1638 | kpause("bflush" , false, MAX(1, hz / 25 * iter), NULL); |
| 1639 | if (nbusy >= nbusy_prev) /* we didn't flush anything */ |
| 1640 | iter++; |
| 1641 | else |
| 1642 | nbusy_prev = nbusy; |
| 1643 | } |
| 1644 | |
| 1645 | if (nbusy) { |
| 1646 | #if defined(DEBUG) || defined(DEBUG_HALT_BUSY) |
| 1647 | printf("giving up\nPrinting vnodes for busy buffers\n" ); |
| 1648 | for (ihash = 0; ihash < bufhash+1; ihash++) { |
| 1649 | LIST_FOREACH(bp, &bufhashtbl[ihash], b_hash) { |
| 1650 | if ((bp->b_cflags & (BC_BUSY|BC_INVAL)) == BC_BUSY && |
| 1651 | (bp->b_flags & B_READ) == 0) |
| 1652 | vprint(NULL, bp->b_vp); |
| 1653 | } |
| 1654 | } |
| 1655 | #endif |
| 1656 | } |
| 1657 | |
| 1658 | return nbusy; |
| 1659 | } |
| 1660 | |
| 1661 | static void |
| 1662 | sysctl_fillbuf(buf_t *i, struct buf_sysctl *o) |
| 1663 | { |
| 1664 | |
| 1665 | o->b_flags = i->b_flags | i->b_cflags | i->b_oflags; |
| 1666 | o->b_error = i->b_error; |
| 1667 | o->b_prio = i->b_prio; |
| 1668 | o->b_dev = i->b_dev; |
| 1669 | o->b_bufsize = i->b_bufsize; |
| 1670 | o->b_bcount = i->b_bcount; |
| 1671 | o->b_resid = i->b_resid; |
| 1672 | o->b_addr = PTRTOUINT64(i->b_data); |
| 1673 | o->b_blkno = i->b_blkno; |
| 1674 | o->b_rawblkno = i->b_rawblkno; |
| 1675 | o->b_iodone = PTRTOUINT64(i->b_iodone); |
| 1676 | o->b_proc = PTRTOUINT64(i->b_proc); |
| 1677 | o->b_vp = PTRTOUINT64(i->b_vp); |
| 1678 | o->b_saveaddr = PTRTOUINT64(i->b_saveaddr); |
| 1679 | o->b_lblkno = i->b_lblkno; |
| 1680 | } |
| 1681 | |
| 1682 | #define KERN_BUFSLOP 20 |
| 1683 | static int |
| 1684 | sysctl_dobuf(SYSCTLFN_ARGS) |
| 1685 | { |
| 1686 | buf_t *bp; |
| 1687 | struct buf_sysctl bs; |
| 1688 | struct bqueue *bq; |
| 1689 | char *dp; |
| 1690 | u_int i, op, arg; |
| 1691 | size_t len, needed, elem_size, out_size; |
| 1692 | int error, elem_count, retries; |
| 1693 | |
| 1694 | if (namelen == 1 && name[0] == CTL_QUERY) |
| 1695 | return (sysctl_query(SYSCTLFN_CALL(rnode))); |
| 1696 | |
| 1697 | if (namelen != 4) |
| 1698 | return (EINVAL); |
| 1699 | |
| 1700 | retries = 100; |
| 1701 | retry: |
| 1702 | dp = oldp; |
| 1703 | len = (oldp != NULL) ? *oldlenp : 0; |
| 1704 | op = name[0]; |
| 1705 | arg = name[1]; |
| 1706 | elem_size = name[2]; |
| 1707 | elem_count = name[3]; |
| 1708 | out_size = MIN(sizeof(bs), elem_size); |
| 1709 | |
| 1710 | /* |
| 1711 | * at the moment, these are just "placeholders" to make the |
| 1712 | * API for retrieving kern.buf data more extensible in the |
| 1713 | * future. |
| 1714 | * |
| 1715 | * XXX kern.buf currently has "netbsd32" issues. hopefully |
| 1716 | * these will be resolved at a later point. |
| 1717 | */ |
| 1718 | if (op != KERN_BUF_ALL || arg != KERN_BUF_ALL || |
| 1719 | elem_size < 1 || elem_count < 0) |
| 1720 | return (EINVAL); |
| 1721 | |
| 1722 | error = 0; |
| 1723 | needed = 0; |
| 1724 | sysctl_unlock(); |
| 1725 | mutex_enter(&bufcache_lock); |
| 1726 | for (i = 0; i < BQUEUES; i++) { |
| 1727 | bq = &bufqueues[i]; |
| 1728 | TAILQ_FOREACH(bp, &bq->bq_queue, b_freelist) { |
| 1729 | bq->bq_marker = bp; |
| 1730 | if (len >= elem_size && elem_count > 0) { |
| 1731 | sysctl_fillbuf(bp, &bs); |
| 1732 | mutex_exit(&bufcache_lock); |
| 1733 | error = copyout(&bs, dp, out_size); |
| 1734 | mutex_enter(&bufcache_lock); |
| 1735 | if (error) |
| 1736 | break; |
| 1737 | if (bq->bq_marker != bp) { |
| 1738 | /* |
| 1739 | * This sysctl node is only for |
| 1740 | * statistics. Retry; if the |
| 1741 | * queue keeps changing, then |
| 1742 | * bail out. |
| 1743 | */ |
| 1744 | if (retries-- == 0) { |
| 1745 | error = EAGAIN; |
| 1746 | break; |
| 1747 | } |
| 1748 | mutex_exit(&bufcache_lock); |
| 1749 | sysctl_relock(); |
| 1750 | goto retry; |
| 1751 | } |
| 1752 | dp += elem_size; |
| 1753 | len -= elem_size; |
| 1754 | } |
| 1755 | needed += elem_size; |
| 1756 | if (elem_count > 0 && elem_count != INT_MAX) |
| 1757 | elem_count--; |
| 1758 | } |
| 1759 | if (error != 0) |
| 1760 | break; |
| 1761 | } |
| 1762 | mutex_exit(&bufcache_lock); |
| 1763 | sysctl_relock(); |
| 1764 | |
| 1765 | *oldlenp = needed; |
| 1766 | if (oldp == NULL) |
| 1767 | *oldlenp += KERN_BUFSLOP * sizeof(buf_t); |
| 1768 | |
| 1769 | return (error); |
| 1770 | } |
| 1771 | |
| 1772 | static int |
| 1773 | sysctl_bufvm_update(SYSCTLFN_ARGS) |
| 1774 | { |
| 1775 | int error, rv; |
| 1776 | struct sysctlnode node; |
| 1777 | unsigned int temp_bufcache; |
| 1778 | unsigned long temp_water; |
| 1779 | |
| 1780 | /* Take a copy of the supplied node and its data */ |
| 1781 | node = *rnode; |
| 1782 | if (node.sysctl_data == &bufcache) { |
| 1783 | node.sysctl_data = &temp_bufcache; |
| 1784 | temp_bufcache = *(unsigned int *)rnode->sysctl_data; |
| 1785 | } else { |
| 1786 | node.sysctl_data = &temp_water; |
| 1787 | temp_water = *(unsigned long *)rnode->sysctl_data; |
| 1788 | } |
| 1789 | |
| 1790 | /* Update the copy */ |
| 1791 | error = sysctl_lookup(SYSCTLFN_CALL(&node)); |
| 1792 | if (error || newp == NULL) |
| 1793 | return (error); |
| 1794 | |
| 1795 | if (rnode->sysctl_data == &bufcache) { |
| 1796 | if (temp_bufcache > 100) |
| 1797 | return (EINVAL); |
| 1798 | bufcache = temp_bufcache; |
| 1799 | buf_setwm(); |
| 1800 | } else if (rnode->sysctl_data == &bufmem_lowater) { |
| 1801 | if (bufmem_hiwater - temp_water < 16) |
| 1802 | return (EINVAL); |
| 1803 | bufmem_lowater = temp_water; |
| 1804 | } else if (rnode->sysctl_data == &bufmem_hiwater) { |
| 1805 | if (temp_water - bufmem_lowater < 16) |
| 1806 | return (EINVAL); |
| 1807 | bufmem_hiwater = temp_water; |
| 1808 | } else |
| 1809 | return (EINVAL); |
| 1810 | |
| 1811 | /* Drain until below new high water mark */ |
| 1812 | sysctl_unlock(); |
| 1813 | mutex_enter(&bufcache_lock); |
| 1814 | while (bufmem > bufmem_hiwater) { |
| 1815 | rv = buf_drain((bufmem - bufmem_hiwater) / (2 * 1024)); |
| 1816 | if (rv <= 0) |
| 1817 | break; |
| 1818 | } |
| 1819 | mutex_exit(&bufcache_lock); |
| 1820 | sysctl_relock(); |
| 1821 | |
| 1822 | return 0; |
| 1823 | } |
| 1824 | |
| 1825 | static struct sysctllog *vfsbio_sysctllog; |
| 1826 | |
| 1827 | static void |
| 1828 | sysctl_kern_buf_setup(void) |
| 1829 | { |
| 1830 | |
| 1831 | sysctl_createv(&vfsbio_sysctllog, 0, NULL, NULL, |
| 1832 | CTLFLAG_PERMANENT, |
| 1833 | CTLTYPE_NODE, "buf" , |
| 1834 | SYSCTL_DESCR("Kernel buffer cache information" ), |
| 1835 | sysctl_dobuf, 0, NULL, 0, |
| 1836 | CTL_KERN, KERN_BUF, CTL_EOL); |
| 1837 | } |
| 1838 | |
| 1839 | static void |
| 1840 | sysctl_vm_buf_setup(void) |
| 1841 | { |
| 1842 | |
| 1843 | sysctl_createv(&vfsbio_sysctllog, 0, NULL, NULL, |
| 1844 | CTLFLAG_PERMANENT|CTLFLAG_READWRITE, |
| 1845 | CTLTYPE_INT, "bufcache" , |
| 1846 | SYSCTL_DESCR("Percentage of physical memory to use for " |
| 1847 | "buffer cache" ), |
| 1848 | sysctl_bufvm_update, 0, &bufcache, 0, |
| 1849 | CTL_VM, CTL_CREATE, CTL_EOL); |
| 1850 | sysctl_createv(&vfsbio_sysctllog, 0, NULL, NULL, |
| 1851 | CTLFLAG_PERMANENT|CTLFLAG_READONLY, |
| 1852 | CTLTYPE_LONG, "bufmem" , |
| 1853 | SYSCTL_DESCR("Amount of kernel memory used by buffer " |
| 1854 | "cache" ), |
| 1855 | NULL, 0, &bufmem, 0, |
| 1856 | CTL_VM, CTL_CREATE, CTL_EOL); |
| 1857 | sysctl_createv(&vfsbio_sysctllog, 0, NULL, NULL, |
| 1858 | CTLFLAG_PERMANENT|CTLFLAG_READWRITE, |
| 1859 | CTLTYPE_LONG, "bufmem_lowater" , |
| 1860 | SYSCTL_DESCR("Minimum amount of kernel memory to " |
| 1861 | "reserve for buffer cache" ), |
| 1862 | sysctl_bufvm_update, 0, &bufmem_lowater, 0, |
| 1863 | CTL_VM, CTL_CREATE, CTL_EOL); |
| 1864 | sysctl_createv(&vfsbio_sysctllog, 0, NULL, NULL, |
| 1865 | CTLFLAG_PERMANENT|CTLFLAG_READWRITE, |
| 1866 | CTLTYPE_LONG, "bufmem_hiwater" , |
| 1867 | SYSCTL_DESCR("Maximum amount of kernel memory to use " |
| 1868 | "for buffer cache" ), |
| 1869 | sysctl_bufvm_update, 0, &bufmem_hiwater, 0, |
| 1870 | CTL_VM, CTL_CREATE, CTL_EOL); |
| 1871 | } |
| 1872 | |
| 1873 | #ifdef DEBUG |
| 1874 | /* |
| 1875 | * Print out statistics on the current allocation of the buffer pool. |
| 1876 | * Can be enabled to print out on every ``sync'' by setting "syncprt" |
| 1877 | * in vfs_syscalls.c using sysctl. |
| 1878 | */ |
| 1879 | void |
| 1880 | vfs_bufstats(void) |
| 1881 | { |
| 1882 | int i, j, count; |
| 1883 | buf_t *bp; |
| 1884 | struct bqueue *dp; |
| 1885 | int counts[MAXBSIZE / MIN_PAGE_SIZE + 1]; |
| 1886 | static const char *bname[BQUEUES] = { "LOCKED" , "LRU" , "AGE" }; |
| 1887 | |
| 1888 | for (dp = bufqueues, i = 0; dp < &bufqueues[BQUEUES]; dp++, i++) { |
| 1889 | count = 0; |
| 1890 | memset(counts, 0, sizeof(counts)); |
| 1891 | TAILQ_FOREACH(bp, &dp->bq_queue, b_freelist) { |
| 1892 | counts[bp->b_bufsize / PAGE_SIZE]++; |
| 1893 | count++; |
| 1894 | } |
| 1895 | printf("%s: total-%d" , bname[i], count); |
| 1896 | for (j = 0; j <= MAXBSIZE / PAGE_SIZE; j++) |
| 1897 | if (counts[j] != 0) |
| 1898 | printf(", %d-%d" , j * PAGE_SIZE, counts[j]); |
| 1899 | printf("\n" ); |
| 1900 | } |
| 1901 | } |
| 1902 | #endif /* DEBUG */ |
| 1903 | |
| 1904 | /* ------------------------------ */ |
| 1905 | |
| 1906 | buf_t * |
| 1907 | getiobuf(struct vnode *vp, bool waitok) |
| 1908 | { |
| 1909 | buf_t *bp; |
| 1910 | |
| 1911 | bp = pool_cache_get(bufio_cache, (waitok ? PR_WAITOK : PR_NOWAIT)); |
| 1912 | if (bp == NULL) |
| 1913 | return bp; |
| 1914 | |
| 1915 | buf_init(bp); |
| 1916 | |
| 1917 | if ((bp->b_vp = vp) == NULL) |
| 1918 | bp->b_objlock = &buffer_lock; |
| 1919 | else |
| 1920 | bp->b_objlock = vp->v_interlock; |
| 1921 | |
| 1922 | return bp; |
| 1923 | } |
| 1924 | |
| 1925 | void |
| 1926 | putiobuf(buf_t *bp) |
| 1927 | { |
| 1928 | |
| 1929 | buf_destroy(bp); |
| 1930 | pool_cache_put(bufio_cache, bp); |
| 1931 | } |
| 1932 | |
| 1933 | /* |
| 1934 | * nestiobuf_iodone: b_iodone callback for nested buffers. |
| 1935 | */ |
| 1936 | |
| 1937 | void |
| 1938 | nestiobuf_iodone(buf_t *bp) |
| 1939 | { |
| 1940 | buf_t *mbp = bp->b_private; |
| 1941 | int error; |
| 1942 | int donebytes; |
| 1943 | |
| 1944 | KASSERT(bp->b_bcount <= bp->b_bufsize); |
| 1945 | KASSERT(mbp != bp); |
| 1946 | |
| 1947 | error = bp->b_error; |
| 1948 | if (bp->b_error == 0 && |
| 1949 | (bp->b_bcount < bp->b_bufsize || bp->b_resid > 0)) { |
| 1950 | /* |
| 1951 | * Not all got transfered, raise an error. We have no way to |
| 1952 | * propagate these conditions to mbp. |
| 1953 | */ |
| 1954 | error = EIO; |
| 1955 | } |
| 1956 | |
| 1957 | donebytes = bp->b_bufsize; |
| 1958 | |
| 1959 | putiobuf(bp); |
| 1960 | nestiobuf_done(mbp, donebytes, error); |
| 1961 | } |
| 1962 | |
| 1963 | /* |
| 1964 | * nestiobuf_setup: setup a "nested" buffer. |
| 1965 | * |
| 1966 | * => 'mbp' is a "master" buffer which is being divided into sub pieces. |
| 1967 | * => 'bp' should be a buffer allocated by getiobuf. |
| 1968 | * => 'offset' is a byte offset in the master buffer. |
| 1969 | * => 'size' is a size in bytes of this nested buffer. |
| 1970 | */ |
| 1971 | |
| 1972 | void |
| 1973 | nestiobuf_setup(buf_t *mbp, buf_t *bp, int offset, size_t size) |
| 1974 | { |
| 1975 | const int b_read = mbp->b_flags & B_READ; |
| 1976 | struct vnode *vp = mbp->b_vp; |
| 1977 | |
| 1978 | KASSERT(mbp->b_bcount >= offset + size); |
| 1979 | bp->b_vp = vp; |
| 1980 | bp->b_dev = mbp->b_dev; |
| 1981 | bp->b_objlock = mbp->b_objlock; |
| 1982 | bp->b_cflags = BC_BUSY; |
| 1983 | bp->b_flags = B_ASYNC | b_read; |
| 1984 | bp->b_iodone = nestiobuf_iodone; |
| 1985 | bp->b_data = (char *)mbp->b_data + offset; |
| 1986 | bp->b_resid = bp->b_bcount = size; |
| 1987 | bp->b_bufsize = bp->b_bcount; |
| 1988 | bp->b_private = mbp; |
| 1989 | BIO_COPYPRIO(bp, mbp); |
| 1990 | if (!b_read && vp != NULL) { |
| 1991 | mutex_enter(vp->v_interlock); |
| 1992 | vp->v_numoutput++; |
| 1993 | mutex_exit(vp->v_interlock); |
| 1994 | } |
| 1995 | } |
| 1996 | |
| 1997 | /* |
| 1998 | * nestiobuf_done: propagate completion to the master buffer. |
| 1999 | * |
| 2000 | * => 'donebytes' specifies how many bytes in the 'mbp' is completed. |
| 2001 | * => 'error' is an errno(2) that 'donebytes' has been completed with. |
| 2002 | */ |
| 2003 | |
| 2004 | void |
| 2005 | nestiobuf_done(buf_t *mbp, int donebytes, int error) |
| 2006 | { |
| 2007 | |
| 2008 | if (donebytes == 0) { |
| 2009 | return; |
| 2010 | } |
| 2011 | mutex_enter(mbp->b_objlock); |
| 2012 | KASSERT(mbp->b_resid >= donebytes); |
| 2013 | mbp->b_resid -= donebytes; |
| 2014 | if (error) |
| 2015 | mbp->b_error = error; |
| 2016 | if (mbp->b_resid == 0) { |
| 2017 | if (mbp->b_error) |
| 2018 | mbp->b_resid = mbp->b_bcount; |
| 2019 | mutex_exit(mbp->b_objlock); |
| 2020 | biodone(mbp); |
| 2021 | } else |
| 2022 | mutex_exit(mbp->b_objlock); |
| 2023 | } |
| 2024 | |
| 2025 | void |
| 2026 | buf_init(buf_t *bp) |
| 2027 | { |
| 2028 | |
| 2029 | cv_init(&bp->b_busy, "biolock" ); |
| 2030 | cv_init(&bp->b_done, "biowait" ); |
| 2031 | bp->b_dev = NODEV; |
| 2032 | bp->b_error = 0; |
| 2033 | bp->b_flags = 0; |
| 2034 | bp->b_cflags = 0; |
| 2035 | bp->b_oflags = 0; |
| 2036 | bp->b_objlock = &buffer_lock; |
| 2037 | bp->b_iodone = NULL; |
| 2038 | bp->b_refcnt = 1; |
| 2039 | bp->b_dev = NODEV; |
| 2040 | bp->b_vnbufs.le_next = NOLIST; |
| 2041 | BIO_SETPRIO(bp, BPRIO_DEFAULT); |
| 2042 | } |
| 2043 | |
| 2044 | void |
| 2045 | buf_destroy(buf_t *bp) |
| 2046 | { |
| 2047 | |
| 2048 | cv_destroy(&bp->b_done); |
| 2049 | cv_destroy(&bp->b_busy); |
| 2050 | } |
| 2051 | |
| 2052 | int |
| 2053 | bbusy(buf_t *bp, bool intr, int timo, kmutex_t *interlock) |
| 2054 | { |
| 2055 | int error; |
| 2056 | |
| 2057 | KASSERT(mutex_owned(&bufcache_lock)); |
| 2058 | |
| 2059 | if ((bp->b_cflags & BC_BUSY) != 0) { |
| 2060 | if (curlwp == uvm.pagedaemon_lwp) |
| 2061 | return EDEADLK; |
| 2062 | bp->b_cflags |= BC_WANTED; |
| 2063 | bref(bp); |
| 2064 | if (interlock != NULL) |
| 2065 | mutex_exit(interlock); |
| 2066 | if (intr) { |
| 2067 | error = cv_timedwait_sig(&bp->b_busy, &bufcache_lock, |
| 2068 | timo); |
| 2069 | } else { |
| 2070 | error = cv_timedwait(&bp->b_busy, &bufcache_lock, |
| 2071 | timo); |
| 2072 | } |
| 2073 | brele(bp); |
| 2074 | if (interlock != NULL) |
| 2075 | mutex_enter(interlock); |
| 2076 | if (error != 0) |
| 2077 | return error; |
| 2078 | return EPASSTHROUGH; |
| 2079 | } |
| 2080 | bp->b_cflags |= BC_BUSY; |
| 2081 | |
| 2082 | return 0; |
| 2083 | } |
| 2084 | |