vm_pager.c revision 116226
1/* 2 * Copyright (c) 1991, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * This code is derived from software contributed to Berkeley by 6 * The Mach Operating System project at Carnegie-Mellon University. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. All advertising materials mentioning features or use of this software 17 * must display the following acknowledgement: 18 * This product includes software developed by the University of 19 * California, Berkeley and its contributors. 20 * 4. 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 * from: @(#)vm_pager.c 8.6 (Berkeley) 1/12/94 37 * 38 * 39 * Copyright (c) 1987, 1990 Carnegie-Mellon University. 40 * All rights reserved. 41 * 42 * Authors: Avadis Tevanian, Jr., Michael Wayne Young 43 * 44 * Permission to use, copy, modify and distribute this software and 45 * its documentation is hereby granted, provided that both the copyright 46 * notice and this permission notice appear in all copies of the 47 * software, derivative works or modified versions, and any portions 48 * thereof, and that both notices appear in supporting documentation. 49 * 50 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" 51 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND 52 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. 53 * 54 * Carnegie Mellon requests users of this software to return to 55 * 56 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU 57 * School of Computer Science 58 * Carnegie Mellon University 59 * Pittsburgh PA 15213-3890 60 * 61 * any improvements or extensions that they make and grant Carnegie the 62 * rights to redistribute these changes. 63 */ 64 65/* 66 * Paging space routine stubs. Emulates a matchmaker-like interface 67 * for builtin pagers. 68 */ 69 70#include <sys/cdefs.h> 71__FBSDID("$FreeBSD: head/sys/vm/vm_pager.c 116226 2003-06-11 23:50:51Z obrien $"); 72 73#include <sys/param.h> 74#include <sys/systm.h> 75#include <sys/kernel.h> 76#include <sys/vnode.h> 77#include <sys/bio.h> 78#include <sys/buf.h> 79#include <sys/ucred.h> 80#include <sys/malloc.h> 81 82#include <vm/vm.h> 83#include <vm/vm_param.h> 84#include <vm/vm_object.h> 85#include <vm/vm_page.h> 86#include <vm/vm_pager.h> 87#include <vm/vm_extern.h> 88 89MALLOC_DEFINE(M_VMPGDATA, "VM pgdata", "XXX: VM pager private data"); 90 91extern struct pagerops defaultpagerops; 92extern struct pagerops swappagerops; 93extern struct pagerops vnodepagerops; 94extern struct pagerops devicepagerops; 95extern struct pagerops physpagerops; 96 97int cluster_pbuf_freecnt = -1; /* unlimited to begin with */ 98 99static int dead_pager_getpages(vm_object_t, vm_page_t *, int, int); 100static vm_object_t dead_pager_alloc(void *, vm_ooffset_t, vm_prot_t, 101 vm_ooffset_t); 102static void dead_pager_putpages(vm_object_t, vm_page_t *, int, int, int *); 103static boolean_t dead_pager_haspage(vm_object_t, vm_pindex_t, int *, int *); 104static void dead_pager_dealloc(vm_object_t); 105 106static int 107dead_pager_getpages(obj, ma, count, req) 108 vm_object_t obj; 109 vm_page_t *ma; 110 int count; 111 int req; 112{ 113 return VM_PAGER_FAIL; 114} 115 116static vm_object_t 117dead_pager_alloc(handle, size, prot, off) 118 void *handle; 119 vm_ooffset_t size; 120 vm_prot_t prot; 121 vm_ooffset_t off; 122{ 123 return NULL; 124} 125 126static void 127dead_pager_putpages(object, m, count, flags, rtvals) 128 vm_object_t object; 129 vm_page_t *m; 130 int count; 131 int flags; 132 int *rtvals; 133{ 134 int i; 135 136 for (i = 0; i < count; i++) { 137 rtvals[i] = VM_PAGER_AGAIN; 138 } 139} 140 141static int 142dead_pager_haspage(object, pindex, prev, next) 143 vm_object_t object; 144 vm_pindex_t pindex; 145 int *prev; 146 int *next; 147{ 148 if (prev) 149 *prev = 0; 150 if (next) 151 *next = 0; 152 return FALSE; 153} 154 155static void 156dead_pager_dealloc(object) 157 vm_object_t object; 158{ 159 return; 160} 161 162static struct pagerops deadpagerops = { 163 NULL, 164 dead_pager_alloc, 165 dead_pager_dealloc, 166 dead_pager_getpages, 167 dead_pager_putpages, 168 dead_pager_haspage, 169 NULL 170}; 171 172struct pagerops *pagertab[] = { 173 &defaultpagerops, /* OBJT_DEFAULT */ 174 &swappagerops, /* OBJT_SWAP */ 175 &vnodepagerops, /* OBJT_VNODE */ 176 &devicepagerops, /* OBJT_DEVICE */ 177 &physpagerops, /* OBJT_PHYS */ 178 &deadpagerops /* OBJT_DEAD */ 179}; 180 181int npagers = sizeof(pagertab) / sizeof(pagertab[0]); 182 183/* 184 * Kernel address space for mapping pages. 185 * Used by pagers where KVAs are needed for IO. 186 * 187 * XXX needs to be large enough to support the number of pending async 188 * cleaning requests (NPENDINGIO == 64) * the maximum swap cluster size 189 * (MAXPHYS == 64k) if you want to get the most efficiency. 190 */ 191#define PAGER_MAP_SIZE (8 * 1024 * 1024) 192 193int pager_map_size = PAGER_MAP_SIZE; 194vm_map_t pager_map; 195static int bswneeded; 196static vm_offset_t swapbkva; /* swap buffers kva */ 197struct mtx pbuf_mtx; 198static TAILQ_HEAD(swqueue, buf) bswlist; 199 200void 201vm_pager_init() 202{ 203 struct pagerops **pgops; 204 205 TAILQ_INIT(&bswlist); 206 /* 207 * Initialize known pagers 208 */ 209 for (pgops = pagertab; pgops < &pagertab[npagers]; pgops++) 210 if (pgops && ((*pgops)->pgo_init != NULL)) 211 (*(*pgops)->pgo_init) (); 212} 213 214void 215vm_pager_bufferinit() 216{ 217 struct buf *bp; 218 int i; 219 220 mtx_init(&pbuf_mtx, "pbuf mutex", NULL, MTX_DEF); 221 bp = swbuf; 222 /* 223 * Now set up swap and physical I/O buffer headers. 224 */ 225 for (i = 0; i < nswbuf; i++, bp++) { 226 TAILQ_INSERT_HEAD(&bswlist, bp, b_freelist); 227 BUF_LOCKINIT(bp); 228 LIST_INIT(&bp->b_dep); 229 bp->b_rcred = bp->b_wcred = NOCRED; 230 bp->b_xflags = 0; 231 } 232 233 cluster_pbuf_freecnt = nswbuf / 2; 234 235 swapbkva = kmem_alloc_pageable(pager_map, nswbuf * MAXPHYS); 236 if (!swapbkva) 237 panic("Not enough pager_map VM space for physical buffers"); 238} 239 240/* 241 * Allocate an instance of a pager of the given type. 242 * Size, protection and offset parameters are passed in for pagers that 243 * need to perform page-level validation (e.g. the device pager). 244 */ 245vm_object_t 246vm_pager_allocate(objtype_t type, void *handle, vm_ooffset_t size, 247 vm_prot_t prot, vm_ooffset_t off) 248{ 249 vm_object_t ret; 250 struct pagerops *ops; 251 252 ops = pagertab[type]; 253 if (ops) 254 ret = (*ops->pgo_alloc) (handle, size, prot, off); 255 else 256 ret = NULL; 257 return (ret); 258} 259 260/* 261 * The object must be locked. 262 */ 263void 264vm_pager_deallocate(object) 265 vm_object_t object; 266{ 267 268 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 269 (*pagertab[object->type]->pgo_dealloc) (object); 270} 271 272/* 273 * vm_pager_strategy: 274 * 275 * called with no specific spl 276 * Execute strategy routine directly to pager. 277 */ 278void 279vm_pager_strategy(vm_object_t object, struct bio *bp) 280{ 281 if (pagertab[object->type]->pgo_strategy) { 282 (*pagertab[object->type]->pgo_strategy)(object, bp); 283 } else { 284 bp->bio_flags |= BIO_ERROR; 285 bp->bio_error = ENXIO; 286 biodone(bp); 287 } 288} 289 290/* 291 * vm_pager_get_pages() - inline, see vm/vm_pager.h 292 * vm_pager_put_pages() - inline, see vm/vm_pager.h 293 * vm_pager_has_page() - inline, see vm/vm_pager.h 294 * vm_pager_page_inserted() - inline, see vm/vm_pager.h 295 * vm_pager_page_removed() - inline, see vm/vm_pager.h 296 */ 297 298vm_offset_t 299vm_pager_map_page(m) 300 vm_page_t m; 301{ 302 vm_offset_t kva; 303 304 kva = kmem_alloc_wait(pager_map, PAGE_SIZE); 305 pmap_qenter(kva, &m, 1); 306 return (kva); 307} 308 309void 310vm_pager_unmap_page(kva) 311 vm_offset_t kva; 312{ 313 314 pmap_qremove(kva, 1); 315 kmem_free_wakeup(pager_map, kva, PAGE_SIZE); 316} 317 318vm_object_t 319vm_pager_object_lookup(pg_list, handle) 320 struct pagerlst *pg_list; 321 void *handle; 322{ 323 vm_object_t object; 324 325 TAILQ_FOREACH(object, pg_list, pager_object_list) 326 if (object->handle == handle) 327 return (object); 328 return (NULL); 329} 330 331/* 332 * initialize a physical buffer 333 */ 334 335/* 336 * XXX This probably belongs in vfs_bio.c 337 */ 338static void 339initpbuf(struct buf *bp) 340{ 341 bp->b_rcred = NOCRED; 342 bp->b_wcred = NOCRED; 343 bp->b_qindex = 0; /* On no queue (QUEUE_NONE) */ 344 bp->b_data = (caddr_t) (MAXPHYS * (bp - swbuf)) + swapbkva; 345 bp->b_kvabase = bp->b_data; 346 bp->b_kvasize = MAXPHYS; 347 bp->b_xflags = 0; 348 bp->b_flags = 0; 349 bp->b_ioflags = 0; 350 bp->b_iodone = NULL; 351 bp->b_error = 0; 352 bp->b_magic = B_MAGIC_BIO; 353 bp->b_op = &buf_ops_bio; 354 BUF_LOCK(bp, LK_EXCLUSIVE, NULL); 355} 356 357/* 358 * allocate a physical buffer 359 * 360 * There are a limited number (nswbuf) of physical buffers. We need 361 * to make sure that no single subsystem is able to hog all of them, 362 * so each subsystem implements a counter which is typically initialized 363 * to 1/2 nswbuf. getpbuf() decrements this counter in allocation and 364 * increments it on release, and blocks if the counter hits zero. A 365 * subsystem may initialize the counter to -1 to disable the feature, 366 * but it must still be sure to match up all uses of getpbuf() with 367 * relpbuf() using the same variable. 368 * 369 * NOTE: pfreecnt can be NULL, but this 'feature' will be removed 370 * relatively soon when the rest of the subsystems get smart about it. XXX 371 */ 372struct buf * 373getpbuf(pfreecnt) 374 int *pfreecnt; 375{ 376 int s; 377 struct buf *bp; 378 379 s = splvm(); 380 mtx_lock(&pbuf_mtx); 381 382 for (;;) { 383 if (pfreecnt) { 384 while (*pfreecnt == 0) { 385 msleep(pfreecnt, &pbuf_mtx, PVM, "wswbuf0", 0); 386 } 387 } 388 389 /* get a bp from the swap buffer header pool */ 390 if ((bp = TAILQ_FIRST(&bswlist)) != NULL) 391 break; 392 393 bswneeded = 1; 394 msleep(&bswneeded, &pbuf_mtx, PVM, "wswbuf1", 0); 395 /* loop in case someone else grabbed one */ 396 } 397 TAILQ_REMOVE(&bswlist, bp, b_freelist); 398 if (pfreecnt) 399 --*pfreecnt; 400 mtx_unlock(&pbuf_mtx); 401 splx(s); 402 403 initpbuf(bp); 404 return bp; 405} 406 407/* 408 * allocate a physical buffer, if one is available. 409 * 410 * Note that there is no NULL hack here - all subsystems using this 411 * call understand how to use pfreecnt. 412 */ 413struct buf * 414trypbuf(pfreecnt) 415 int *pfreecnt; 416{ 417 int s; 418 struct buf *bp; 419 420 s = splvm(); 421 mtx_lock(&pbuf_mtx); 422 if (*pfreecnt == 0 || (bp = TAILQ_FIRST(&bswlist)) == NULL) { 423 mtx_unlock(&pbuf_mtx); 424 splx(s); 425 return NULL; 426 } 427 TAILQ_REMOVE(&bswlist, bp, b_freelist); 428 429 --*pfreecnt; 430 431 mtx_unlock(&pbuf_mtx); 432 splx(s); 433 434 initpbuf(bp); 435 436 return bp; 437} 438 439/* 440 * release a physical buffer 441 * 442 * NOTE: pfreecnt can be NULL, but this 'feature' will be removed 443 * relatively soon when the rest of the subsystems get smart about it. XXX 444 */ 445void 446relpbuf(bp, pfreecnt) 447 struct buf *bp; 448 int *pfreecnt; 449{ 450 int s; 451 452 s = splvm(); 453 454 if (bp->b_rcred != NOCRED) { 455 crfree(bp->b_rcred); 456 bp->b_rcred = NOCRED; 457 } 458 if (bp->b_wcred != NOCRED) { 459 crfree(bp->b_wcred); 460 bp->b_wcred = NOCRED; 461 } 462 463 if (bp->b_vp) 464 pbrelvp(bp); 465 466 BUF_UNLOCK(bp); 467 468 mtx_lock(&pbuf_mtx); 469 TAILQ_INSERT_HEAD(&bswlist, bp, b_freelist); 470 471 if (bswneeded) { 472 bswneeded = 0; 473 wakeup(&bswneeded); 474 } 475 if (pfreecnt) { 476 if (++*pfreecnt == 1) 477 wakeup(pfreecnt); 478 } 479 mtx_unlock(&pbuf_mtx); 480 splx(s); 481} 482