vm_pager.c revision 118413
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 118413 2003-08-04 04:35:04Z alc $"); 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 91int cluster_pbuf_freecnt = -1; /* unlimited to begin with */ 92 93static int dead_pager_getpages(vm_object_t, vm_page_t *, int, int); 94static vm_object_t dead_pager_alloc(void *, vm_ooffset_t, vm_prot_t, 95 vm_ooffset_t); 96static void dead_pager_putpages(vm_object_t, vm_page_t *, int, int, int *); 97static boolean_t dead_pager_haspage(vm_object_t, vm_pindex_t, int *, int *); 98static void dead_pager_dealloc(vm_object_t); 99 100static int 101dead_pager_getpages(obj, ma, count, req) 102 vm_object_t obj; 103 vm_page_t *ma; 104 int count; 105 int req; 106{ 107 return VM_PAGER_FAIL; 108} 109 110static vm_object_t 111dead_pager_alloc(handle, size, prot, off) 112 void *handle; 113 vm_ooffset_t size; 114 vm_prot_t prot; 115 vm_ooffset_t off; 116{ 117 return NULL; 118} 119 120static void 121dead_pager_putpages(object, m, count, flags, rtvals) 122 vm_object_t object; 123 vm_page_t *m; 124 int count; 125 int flags; 126 int *rtvals; 127{ 128 int i; 129 130 for (i = 0; i < count; i++) { 131 rtvals[i] = VM_PAGER_AGAIN; 132 } 133} 134 135static int 136dead_pager_haspage(object, pindex, prev, next) 137 vm_object_t object; 138 vm_pindex_t pindex; 139 int *prev; 140 int *next; 141{ 142 if (prev) 143 *prev = 0; 144 if (next) 145 *next = 0; 146 return FALSE; 147} 148 149static void 150dead_pager_dealloc(object) 151 vm_object_t object; 152{ 153 return; 154} 155 156static struct pagerops deadpagerops = { 157 NULL, 158 dead_pager_alloc, 159 dead_pager_dealloc, 160 dead_pager_getpages, 161 dead_pager_putpages, 162 dead_pager_haspage, 163 NULL 164}; 165 166struct pagerops *pagertab[] = { 167 &defaultpagerops, /* OBJT_DEFAULT */ 168 &swappagerops, /* OBJT_SWAP */ 169 &vnodepagerops, /* OBJT_VNODE */ 170 &devicepagerops, /* OBJT_DEVICE */ 171 &physpagerops, /* OBJT_PHYS */ 172 &deadpagerops /* OBJT_DEAD */ 173}; 174 175int npagers = sizeof(pagertab) / sizeof(pagertab[0]); 176 177/* 178 * Kernel address space for mapping pages. 179 * Used by pagers where KVAs are needed for IO. 180 * 181 * XXX needs to be large enough to support the number of pending async 182 * cleaning requests (NPENDINGIO == 64) * the maximum swap cluster size 183 * (MAXPHYS == 64k) if you want to get the most efficiency. 184 */ 185#define PAGER_MAP_SIZE (8 * 1024 * 1024) 186 187int pager_map_size = PAGER_MAP_SIZE; 188vm_map_t pager_map; 189static int bswneeded; 190static vm_offset_t swapbkva; /* swap buffers kva */ 191struct mtx pbuf_mtx; 192static TAILQ_HEAD(swqueue, buf) bswlist; 193 194void 195vm_pager_init() 196{ 197 struct pagerops **pgops; 198 199 TAILQ_INIT(&bswlist); 200 /* 201 * Initialize known pagers 202 */ 203 for (pgops = pagertab; pgops < &pagertab[npagers]; pgops++) 204 if (pgops && ((*pgops)->pgo_init != NULL)) 205 (*(*pgops)->pgo_init) (); 206} 207 208void 209vm_pager_bufferinit() 210{ 211 struct buf *bp; 212 int i; 213 214 mtx_init(&pbuf_mtx, "pbuf mutex", NULL, MTX_DEF); 215 bp = swbuf; 216 /* 217 * Now set up swap and physical I/O buffer headers. 218 */ 219 for (i = 0; i < nswbuf; i++, bp++) { 220 TAILQ_INSERT_HEAD(&bswlist, bp, b_freelist); 221 BUF_LOCKINIT(bp); 222 LIST_INIT(&bp->b_dep); 223 bp->b_rcred = bp->b_wcred = NOCRED; 224 bp->b_xflags = 0; 225 } 226 227 cluster_pbuf_freecnt = nswbuf / 2; 228 229 swapbkva = kmem_alloc_nofault(pager_map, nswbuf * MAXPHYS); 230 if (!swapbkva) 231 panic("Not enough pager_map VM space for physical buffers"); 232} 233 234/* 235 * Allocate an instance of a pager of the given type. 236 * Size, protection and offset parameters are passed in for pagers that 237 * need to perform page-level validation (e.g. the device pager). 238 */ 239vm_object_t 240vm_pager_allocate(objtype_t type, void *handle, vm_ooffset_t size, 241 vm_prot_t prot, vm_ooffset_t off) 242{ 243 vm_object_t ret; 244 struct pagerops *ops; 245 246 ops = pagertab[type]; 247 if (ops) 248 ret = (*ops->pgo_alloc) (handle, size, prot, off); 249 else 250 ret = NULL; 251 return (ret); 252} 253 254/* 255 * The object must be locked. 256 */ 257void 258vm_pager_deallocate(object) 259 vm_object_t object; 260{ 261 262 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 263 (*pagertab[object->type]->pgo_dealloc) (object); 264} 265 266/* 267 * vm_pager_strategy: 268 * 269 * called with no specific spl 270 * Execute strategy routine directly to pager. 271 */ 272void 273vm_pager_strategy(vm_object_t object, struct bio *bp) 274{ 275 if (pagertab[object->type]->pgo_strategy) { 276 (*pagertab[object->type]->pgo_strategy)(object, bp); 277 } else { 278 bp->bio_flags |= BIO_ERROR; 279 bp->bio_error = ENXIO; 280 biodone(bp); 281 } 282} 283 284/* 285 * vm_pager_get_pages() - inline, see vm/vm_pager.h 286 * vm_pager_put_pages() - inline, see vm/vm_pager.h 287 * vm_pager_has_page() - inline, see vm/vm_pager.h 288 * vm_pager_page_inserted() - inline, see vm/vm_pager.h 289 * vm_pager_page_removed() - inline, see vm/vm_pager.h 290 */ 291 292vm_offset_t 293vm_pager_map_page(m) 294 vm_page_t m; 295{ 296 vm_offset_t kva; 297 298 kva = kmem_alloc_wait(pager_map, PAGE_SIZE); 299 pmap_qenter(kva, &m, 1); 300 return (kva); 301} 302 303void 304vm_pager_unmap_page(kva) 305 vm_offset_t kva; 306{ 307 308 pmap_qremove(kva, 1); 309 kmem_free_wakeup(pager_map, kva, PAGE_SIZE); 310} 311 312vm_object_t 313vm_pager_object_lookup(pg_list, handle) 314 struct pagerlst *pg_list; 315 void *handle; 316{ 317 vm_object_t object; 318 319 TAILQ_FOREACH(object, pg_list, pager_object_list) 320 if (object->handle == handle) 321 return (object); 322 return (NULL); 323} 324 325/* 326 * initialize a physical buffer 327 */ 328 329/* 330 * XXX This probably belongs in vfs_bio.c 331 */ 332static void 333initpbuf(struct buf *bp) 334{ 335 bp->b_rcred = NOCRED; 336 bp->b_wcred = NOCRED; 337 bp->b_qindex = 0; /* On no queue (QUEUE_NONE) */ 338 bp->b_saveaddr = (caddr_t) (MAXPHYS * (bp - swbuf)) + swapbkva; 339 bp->b_data = bp->b_saveaddr; 340 bp->b_kvabase = bp->b_saveaddr; 341 bp->b_kvasize = MAXPHYS; 342 bp->b_xflags = 0; 343 bp->b_flags = 0; 344 bp->b_ioflags = 0; 345 bp->b_iodone = NULL; 346 bp->b_error = 0; 347 bp->b_magic = B_MAGIC_BIO; 348 bp->b_op = &buf_ops_bio; 349 BUF_LOCK(bp, LK_EXCLUSIVE, NULL); 350} 351 352/* 353 * allocate a physical buffer 354 * 355 * There are a limited number (nswbuf) of physical buffers. We need 356 * to make sure that no single subsystem is able to hog all of them, 357 * so each subsystem implements a counter which is typically initialized 358 * to 1/2 nswbuf. getpbuf() decrements this counter in allocation and 359 * increments it on release, and blocks if the counter hits zero. A 360 * subsystem may initialize the counter to -1 to disable the feature, 361 * but it must still be sure to match up all uses of getpbuf() with 362 * relpbuf() using the same variable. 363 * 364 * NOTE: pfreecnt can be NULL, but this 'feature' will be removed 365 * relatively soon when the rest of the subsystems get smart about it. XXX 366 */ 367struct buf * 368getpbuf(pfreecnt) 369 int *pfreecnt; 370{ 371 int s; 372 struct buf *bp; 373 374 s = splvm(); 375 mtx_lock(&pbuf_mtx); 376 377 for (;;) { 378 if (pfreecnt) { 379 while (*pfreecnt == 0) { 380 msleep(pfreecnt, &pbuf_mtx, PVM, "wswbuf0", 0); 381 } 382 } 383 384 /* get a bp from the swap buffer header pool */ 385 if ((bp = TAILQ_FIRST(&bswlist)) != NULL) 386 break; 387 388 bswneeded = 1; 389 msleep(&bswneeded, &pbuf_mtx, PVM, "wswbuf1", 0); 390 /* loop in case someone else grabbed one */ 391 } 392 TAILQ_REMOVE(&bswlist, bp, b_freelist); 393 if (pfreecnt) 394 --*pfreecnt; 395 mtx_unlock(&pbuf_mtx); 396 splx(s); 397 398 initpbuf(bp); 399 return bp; 400} 401 402/* 403 * allocate a physical buffer, if one is available. 404 * 405 * Note that there is no NULL hack here - all subsystems using this 406 * call understand how to use pfreecnt. 407 */ 408struct buf * 409trypbuf(pfreecnt) 410 int *pfreecnt; 411{ 412 int s; 413 struct buf *bp; 414 415 s = splvm(); 416 mtx_lock(&pbuf_mtx); 417 if (*pfreecnt == 0 || (bp = TAILQ_FIRST(&bswlist)) == NULL) { 418 mtx_unlock(&pbuf_mtx); 419 splx(s); 420 return NULL; 421 } 422 TAILQ_REMOVE(&bswlist, bp, b_freelist); 423 424 --*pfreecnt; 425 426 mtx_unlock(&pbuf_mtx); 427 splx(s); 428 429 initpbuf(bp); 430 431 return bp; 432} 433 434/* 435 * release a physical buffer 436 * 437 * NOTE: pfreecnt can be NULL, but this 'feature' will be removed 438 * relatively soon when the rest of the subsystems get smart about it. XXX 439 */ 440void 441relpbuf(bp, pfreecnt) 442 struct buf *bp; 443 int *pfreecnt; 444{ 445 int s; 446 447 s = splvm(); 448 449 if (bp->b_rcred != NOCRED) { 450 crfree(bp->b_rcred); 451 bp->b_rcred = NOCRED; 452 } 453 if (bp->b_wcred != NOCRED) { 454 crfree(bp->b_wcred); 455 bp->b_wcred = NOCRED; 456 } 457 458 if (bp->b_vp) 459 pbrelvp(bp); 460 461 BUF_UNLOCK(bp); 462 463 mtx_lock(&pbuf_mtx); 464 TAILQ_INSERT_HEAD(&bswlist, bp, b_freelist); 465 466 if (bswneeded) { 467 bswneeded = 0; 468 wakeup(&bswneeded); 469 } 470 if (pfreecnt) { 471 if (++*pfreecnt == 1) 472 wakeup(pfreecnt); 473 } 474 mtx_unlock(&pbuf_mtx); 475 splx(s); 476} 477