vm_pager.c revision 58634
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 acknowledgment: 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 * $FreeBSD: head/sys/vm/vm_pager.c 58634 2000-03-26 15:20:23Z charnier $ 65 */ 66 67/* 68 * Paging space routine stubs. Emulates a matchmaker-like interface 69 * for builtin pagers. 70 */ 71 72#include <sys/param.h> 73#include <sys/systm.h> 74#include <sys/kernel.h> 75#include <sys/vnode.h> 76#include <sys/buf.h> 77#include <sys/ucred.h> 78#include <sys/malloc.h> 79#include <sys/proc.h> 80 81#include <vm/vm.h> 82#include <vm/vm_param.h> 83#include <vm/vm_object.h> 84#include <vm/vm_page.h> 85#include <vm/vm_pager.h> 86#include <vm/vm_extern.h> 87 88MALLOC_DEFINE(M_VMPGDATA, "VM pgdata", "XXX: VM pager private data"); 89 90extern struct pagerops defaultpagerops; 91extern struct pagerops swappagerops; 92extern struct pagerops vnodepagerops; 93extern struct pagerops devicepagerops; 94 95int cluster_pbuf_freecnt = -1; /* unlimited to begin with */ 96 97static int dead_pager_getpages __P((vm_object_t, vm_page_t *, int, int)); 98static vm_object_t dead_pager_alloc __P((void *, vm_ooffset_t, vm_prot_t, 99 vm_ooffset_t)); 100static void dead_pager_putpages __P((vm_object_t, vm_page_t *, int, int, int *)); 101static boolean_t dead_pager_haspage __P((vm_object_t, vm_pindex_t, int *, int *)); 102static void dead_pager_dealloc __P((vm_object_t)); 103 104static int 105dead_pager_getpages(obj, ma, count, req) 106 vm_object_t obj; 107 vm_page_t *ma; 108 int count; 109 int req; 110{ 111 return VM_PAGER_FAIL; 112} 113 114static vm_object_t 115dead_pager_alloc(handle, size, prot, off) 116 void *handle; 117 vm_ooffset_t size; 118 vm_prot_t prot; 119 vm_ooffset_t off; 120{ 121 return NULL; 122} 123 124static void 125dead_pager_putpages(object, m, count, flags, rtvals) 126 vm_object_t object; 127 vm_page_t *m; 128 int count; 129 int flags; 130 int *rtvals; 131{ 132 int i; 133 134 for (i = 0; i < count; i++) { 135 rtvals[i] = VM_PAGER_AGAIN; 136 } 137} 138 139static int 140dead_pager_haspage(object, pindex, prev, next) 141 vm_object_t object; 142 vm_pindex_t pindex; 143 int *prev; 144 int *next; 145{ 146 if (prev) 147 *prev = 0; 148 if (next) 149 *next = 0; 150 return FALSE; 151} 152 153static void 154dead_pager_dealloc(object) 155 vm_object_t object; 156{ 157 return; 158} 159 160static struct pagerops deadpagerops = { 161 NULL, 162 dead_pager_alloc, 163 dead_pager_dealloc, 164 dead_pager_getpages, 165 dead_pager_putpages, 166 dead_pager_haspage, 167 NULL 168}; 169 170struct pagerops *pagertab[] = { 171 &defaultpagerops, /* OBJT_DEFAULT */ 172 &swappagerops, /* OBJT_SWAP */ 173 &vnodepagerops, /* OBJT_VNODE */ 174 &devicepagerops, /* OBJT_DEVICE */ 175 &deadpagerops /* OBJT_DEAD */ 176}; 177 178int npagers = sizeof(pagertab) / sizeof(pagertab[0]); 179 180/* 181 * Kernel address space for mapping pages. 182 * Used by pagers where KVAs are needed for IO. 183 * 184 * XXX needs to be large enough to support the number of pending async 185 * cleaning requests (NPENDINGIO == 64) * the maximum swap cluster size 186 * (MAXPHYS == 64k) if you want to get the most efficiency. 187 */ 188#define PAGER_MAP_SIZE (8 * 1024 * 1024) 189 190int pager_map_size = PAGER_MAP_SIZE; 191vm_map_t pager_map; 192static int bswneeded; 193static vm_offset_t swapbkva; /* swap buffers kva */ 194 195void 196vm_pager_init() 197{ 198 struct pagerops **pgops; 199 200 /* 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 bp = swbuf; 215 /* 216 * Now set up swap and physical I/O buffer headers. 217 */ 218 for (i = 0; i < nswbuf; i++, bp++) { 219 TAILQ_INSERT_HEAD(&bswlist, bp, b_freelist); 220 BUF_LOCKINIT(bp); 221 LIST_INIT(&bp->b_dep); 222 bp->b_rcred = bp->b_wcred = NOCRED; 223 bp->b_xflags = 0; 224 } 225 226 cluster_pbuf_freecnt = nswbuf / 2; 227 228 swapbkva = kmem_alloc_pageable(pager_map, nswbuf * MAXPHYS); 229 if (!swapbkva) 230 panic("Not enough pager_map VM space for physical buffers"); 231} 232 233/* 234 * Allocate an instance of a pager of the given type. 235 * Size, protection and offset parameters are passed in for pagers that 236 * need to perform page-level validation (e.g. the device pager). 237 */ 238vm_object_t 239vm_pager_allocate(objtype_t type, void *handle, vm_ooffset_t size, vm_prot_t prot, 240 vm_ooffset_t off) 241{ 242 struct pagerops *ops; 243 244 ops = pagertab[type]; 245 if (ops) 246 return ((*ops->pgo_alloc) (handle, size, prot, off)); 247 return (NULL); 248} 249 250void 251vm_pager_deallocate(object) 252 vm_object_t object; 253{ 254 (*pagertab[object->type]->pgo_dealloc) (object); 255} 256 257/* 258 * vm_pager_strategy: 259 * 260 * called with no specific spl 261 * Execute strategy routine directly to pager. 262 */ 263 264void 265vm_pager_strategy(vm_object_t object, struct buf *bp) 266{ 267 if (pagertab[object->type]->pgo_strategy) { 268 (*pagertab[object->type]->pgo_strategy)(object, bp); 269 } else { 270 bp->b_flags |= B_ERROR; 271 bp->b_error = ENXIO; 272 biodone(bp); 273 } 274} 275 276/* 277 * vm_pager_get_pages() - inline, see vm/vm_pager.h 278 * vm_pager_put_pages() - inline, see vm/vm_pager.h 279 * vm_pager_has_page() - inline, see vm/vm_pager.h 280 * vm_pager_page_inserted() - inline, see vm/vm_pager.h 281 * vm_pager_page_removed() - inline, see vm/vm_pager.h 282 */ 283 284#if 0 285/* 286 * vm_pager_sync: 287 * 288 * Called by pageout daemon before going back to sleep. 289 * Gives pagers a chance to clean up any completed async pageing 290 * operations. 291 */ 292void 293vm_pager_sync() 294{ 295 struct pagerops **pgops; 296 297 for (pgops = pagertab; pgops < &pagertab[npagers]; pgops++) 298 if (pgops && ((*pgops)->pgo_sync != NULL)) 299 (*(*pgops)->pgo_sync) (); 300} 301 302#endif 303 304vm_offset_t 305vm_pager_map_page(m) 306 vm_page_t m; 307{ 308 vm_offset_t kva; 309 310 kva = kmem_alloc_wait(pager_map, PAGE_SIZE); 311 pmap_kenter(kva, VM_PAGE_TO_PHYS(m)); 312 return (kva); 313} 314 315void 316vm_pager_unmap_page(kva) 317 vm_offset_t kva; 318{ 319 pmap_kremove(kva); 320 kmem_free_wakeup(pager_map, kva, PAGE_SIZE); 321} 322 323vm_object_t 324vm_pager_object_lookup(pg_list, handle) 325 register struct pagerlst *pg_list; 326 void *handle; 327{ 328 register vm_object_t object; 329 330 for (object = TAILQ_FIRST(pg_list); object != NULL; object = TAILQ_NEXT(object,pager_object_list)) 331 if (object->handle == handle) 332 return (object); 333 return (NULL); 334} 335 336/* 337 * initialize a physical buffer 338 */ 339 340static void 341initpbuf(struct buf *bp) 342{ 343 bp->b_rcred = NOCRED; 344 bp->b_wcred = NOCRED; 345 bp->b_qindex = QUEUE_NONE; 346 bp->b_data = (caddr_t) (MAXPHYS * (bp - swbuf)) + swapbkva; 347 bp->b_kvabase = bp->b_data; 348 bp->b_kvasize = MAXPHYS; 349 bp->b_xflags = 0; 350 bp->b_flags = 0; 351 bp->b_iodone = NULL; 352 bp->b_error = 0; 353 BUF_LOCK(bp, LK_EXCLUSIVE); 354} 355 356/* 357 * allocate a physical buffer 358 * 359 * There are a limited number (nswbuf) of physical buffers. We need 360 * to make sure that no single subsystem is able to hog all of them, 361 * so each subsystem implements a counter which is typically initialized 362 * to 1/2 nswbuf. getpbuf() decrements this counter in allocation and 363 * increments it on release, and blocks if the counter hits zero. A 364 * subsystem may initialize the counter to -1 to disable the feature, 365 * but it must still be sure to match up all uses of getpbuf() with 366 * relpbuf() using the same variable. 367 * 368 * NOTE: pfreecnt can be NULL, but this 'feature' will be removed 369 * relatively soon when the rest of the subsystems get smart about it. XXX 370 */ 371struct buf * 372getpbuf(pfreecnt) 373 int *pfreecnt; 374{ 375 int s; 376 struct buf *bp; 377 378 s = splvm(); 379 380 for (;;) { 381 if (pfreecnt) { 382 while (*pfreecnt == 0) { 383 tsleep(pfreecnt, PVM, "wswbuf0", 0); 384 } 385 } 386 387 /* get a bp from the swap buffer header pool */ 388 if ((bp = TAILQ_FIRST(&bswlist)) != NULL) 389 break; 390 391 bswneeded = 1; 392 tsleep(&bswneeded, PVM, "wswbuf1", 0); 393 /* loop in case someone else grabbed one */ 394 } 395 TAILQ_REMOVE(&bswlist, bp, b_freelist); 396 if (pfreecnt) 397 --*pfreecnt; 398 splx(s); 399 400 initpbuf(bp); 401 return bp; 402} 403 404/* 405 * allocate a physical buffer, if one is available. 406 * 407 * Note that there is no NULL hack here - all subsystems using this 408 * call understand how to use pfreecnt. 409 */ 410struct buf * 411trypbuf(pfreecnt) 412 int *pfreecnt; 413{ 414 int s; 415 struct buf *bp; 416 417 s = splvm(); 418 if (*pfreecnt == 0 || (bp = TAILQ_FIRST(&bswlist)) == NULL) { 419 splx(s); 420 return NULL; 421 } 422 TAILQ_REMOVE(&bswlist, bp, b_freelist); 423 424 --*pfreecnt; 425 426 splx(s); 427 428 initpbuf(bp); 429 430 return bp; 431} 432 433/* 434 * release a physical buffer 435 * 436 * NOTE: pfreecnt can be NULL, but this 'feature' will be removed 437 * relatively soon when the rest of the subsystems get smart about it. XXX 438 */ 439void 440relpbuf(bp, pfreecnt) 441 struct buf *bp; 442 int *pfreecnt; 443{ 444 int s; 445 446 s = splvm(); 447 448 if (bp->b_rcred != NOCRED) { 449 crfree(bp->b_rcred); 450 bp->b_rcred = NOCRED; 451 } 452 if (bp->b_wcred != NOCRED) { 453 crfree(bp->b_wcred); 454 bp->b_wcred = NOCRED; 455 } 456 457 if (bp->b_vp) 458 pbrelvp(bp); 459 460 BUF_UNLOCK(bp); 461 462 TAILQ_INSERT_HEAD(&bswlist, bp, b_freelist); 463 464 if (bswneeded) { 465 bswneeded = 0; 466 wakeup(&bswneeded); 467 } 468 if (pfreecnt) { 469 if (++*pfreecnt == 1) 470 wakeup(pfreecnt); 471 } 472 splx(s); 473} 474 475/******************************************************** 476 * CHAINING FUNCTIONS * 477 ******************************************************** 478 * 479 * These functions support recursion of I/O operations 480 * on bp's, typically by chaining one or more 'child' bp's 481 * to the parent. Synchronous, asynchronous, and semi-synchronous 482 * chaining is possible. 483 */ 484 485/* 486 * vm_pager_chain_iodone: 487 * 488 * io completion routine for child bp. Currently we fudge a bit 489 * on dealing with b_resid. Since users of these routines may issue 490 * multiple children simultaneously, sequencing of the error can be lost. 491 */ 492 493static void 494vm_pager_chain_iodone(struct buf *nbp) 495{ 496 struct buf *bp; 497 498 if ((bp = nbp->b_chain.parent) != NULL) { 499 if (nbp->b_flags & B_ERROR) { 500 bp->b_flags |= B_ERROR; 501 bp->b_error = nbp->b_error; 502 } else if (nbp->b_resid != 0) { 503 bp->b_flags |= B_ERROR; 504 bp->b_error = EINVAL; 505 } else { 506 bp->b_resid -= nbp->b_bcount; 507 } 508 nbp->b_chain.parent = NULL; 509 --bp->b_chain.count; 510 if (bp->b_flags & B_WANT) { 511 bp->b_flags &= ~B_WANT; 512 wakeup(bp); 513 } 514 if (!bp->b_chain.count && (bp->b_flags & B_AUTOCHAINDONE)) { 515 bp->b_flags &= ~B_AUTOCHAINDONE; 516 if (bp->b_resid != 0 && !(bp->b_flags & B_ERROR)) { 517 bp->b_flags |= B_ERROR; 518 bp->b_error = EINVAL; 519 } 520 biodone(bp); 521 } 522 } 523 nbp->b_flags |= B_DONE; 524 nbp->b_flags &= ~B_ASYNC; 525 relpbuf(nbp, NULL); 526} 527 528/* 529 * getchainbuf: 530 * 531 * Obtain a physical buffer and chain it to its parent buffer. When 532 * I/O completes, the parent buffer will be B_SIGNAL'd. Errors are 533 * automatically propagated to the parent 534 * 535 * Since these are brand new buffers, we do not have to clear B_INVAL 536 * and B_ERROR because they are already clear. 537 */ 538 539struct buf * 540getchainbuf(struct buf *bp, struct vnode *vp, int flags) 541{ 542 struct buf *nbp = getpbuf(NULL); 543 544 nbp->b_chain.parent = bp; 545 ++bp->b_chain.count; 546 547 if (bp->b_chain.count > 4) 548 waitchainbuf(bp, 4, 0); 549 550 nbp->b_flags = (bp->b_flags & B_ORDERED) | flags; 551 nbp->b_rcred = nbp->b_wcred = proc0.p_ucred; 552 nbp->b_iodone = vm_pager_chain_iodone; 553 554 crhold(nbp->b_rcred); 555 crhold(nbp->b_wcred); 556 557 if (vp) 558 pbgetvp(vp, nbp); 559 return(nbp); 560} 561 562void 563flushchainbuf(struct buf *nbp) 564{ 565 if (nbp->b_bcount) { 566 nbp->b_bufsize = nbp->b_bcount; 567 if (nbp->b_iocmd == BIO_WRITE) 568 nbp->b_dirtyend = nbp->b_bcount; 569 BUF_KERNPROC(nbp); 570 BUF_STRATEGY(nbp); 571 } else { 572 biodone(nbp); 573 } 574} 575 576void 577waitchainbuf(struct buf *bp, int count, int done) 578{ 579 int s; 580 581 s = splbio(); 582 while (bp->b_chain.count > count) { 583 bp->b_flags |= B_WANT; 584 tsleep(bp, PRIBIO + 4, "bpchain", 0); 585 } 586 if (done) { 587 if (bp->b_resid != 0 && !(bp->b_flags & B_ERROR)) { 588 bp->b_flags |= B_ERROR; 589 bp->b_error = EINVAL; 590 } 591 biodone(bp); 592 } 593 splx(s); 594} 595 596void 597autochaindone(struct buf *bp) 598{ 599 int s; 600 601 s = splbio(); 602 if (bp->b_chain.count == 0) 603 biodone(bp); 604 else 605 bp->b_flags |= B_AUTOCHAINDONE; 606 splx(s); 607} 608 609