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 * $FreeBSD: src/sys/vm/vm_pager.c,v 1.54.2.2 2001/11/18 07:11:00 dillon Exp $ 65 * $DragonFly: src/sys/vm/vm_pager.c,v 1.11 2004/07/14 03:10:17 hmp Exp $ 66 */ 67 68 /* 69 * Paging space routine stubs. Emulates a matchmaker-like interface 70 * for builtin pagers. 71 */ 72 73 #include <sys/param.h> 74 #include <sys/systm.h> 75 #include <sys/kernel.h> 76 #include <sys/vnode.h> 77 #include <sys/buf.h> 78 #include <sys/ucred.h> 79 #include <sys/malloc.h> 80 #include <sys/proc.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 89 #include <sys/buf2.h> 90 91 MALLOC_DEFINE(M_VMPGDATA, "VM pgdata", "XXX: VM pager private data"); 92 93 extern struct pagerops defaultpagerops; 94 extern struct pagerops swappagerops; 95 extern struct pagerops vnodepagerops; 96 extern struct pagerops devicepagerops; 97 extern struct pagerops physpagerops; 98 99 int cluster_pbuf_freecnt = -1; /* unlimited to begin with */ 100 101 static int dead_pager_getpages (vm_object_t, vm_page_t *, int, int); 102 static vm_object_t dead_pager_alloc (void *, vm_ooffset_t, vm_prot_t, 103 vm_ooffset_t); 104 static void dead_pager_putpages (vm_object_t, vm_page_t *, int, int, int *); 105 static boolean_t dead_pager_haspage (vm_object_t, vm_pindex_t, int *, int *); 106 static void dead_pager_dealloc (vm_object_t); 107 108 static int 109 dead_pager_getpages(vm_object_t obj, vm_page_t *ma, int count, int req) 110 { 111 return VM_PAGER_FAIL; 112 } 113 114 static vm_object_t 115 dead_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot, 116 vm_ooffset_t off) 117 { 118 return NULL; 119 } 120 121 static void 122 dead_pager_putpages(vm_object_t object, vm_page_t *m, int count, int flags, 123 int *rtvals) 124 { 125 int i; 126 127 for (i = 0; i < count; i++) { 128 rtvals[i] = VM_PAGER_AGAIN; 129 } 130 } 131 132 static int 133 dead_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *prev, int *next) 134 { 135 if (prev) 136 *prev = 0; 137 if (next) 138 *next = 0; 139 return FALSE; 140 } 141 142 static void 143 dead_pager_dealloc(vm_object_t object) 144 { 145 return; 146 } 147 148 static struct pagerops deadpagerops = { 149 NULL, 150 dead_pager_alloc, 151 dead_pager_dealloc, 152 dead_pager_getpages, 153 dead_pager_putpages, 154 dead_pager_haspage, 155 NULL 156 }; 157 158 struct pagerops *pagertab[] = { 159 &defaultpagerops, /* OBJT_DEFAULT */ 160 &swappagerops, /* OBJT_SWAP */ 161 &vnodepagerops, /* OBJT_VNODE */ 162 &devicepagerops, /* OBJT_DEVICE */ 163 &physpagerops, /* OBJT_PHYS */ 164 &deadpagerops /* OBJT_DEAD */ 165 }; 166 167 int npagers = sizeof(pagertab) / sizeof(pagertab[0]); 168 169 /* 170 * Kernel address space for mapping pages. 171 * Used by pagers where KVAs are needed for IO. 172 * 173 * XXX needs to be large enough to support the number of pending async 174 * cleaning requests (NPENDINGIO == 64) * the maximum swap cluster size 175 * (MAXPHYS == 64k) if you want to get the most efficiency. 176 */ 177 #define PAGER_MAP_SIZE (8 * 1024 * 1024) 178 179 int pager_map_size = PAGER_MAP_SIZE; 180 vm_map_t pager_map; 181 static int bswneeded; 182 static vm_offset_t swapbkva; /* swap buffers kva */ 183 184 void 185 vm_pager_init(void) 186 { 187 struct pagerops **pgops; 188 189 /* 190 * Initialize known pagers 191 */ 192 for (pgops = pagertab; pgops < &pagertab[npagers]; pgops++) 193 if (pgops && ((*pgops)->pgo_init != NULL)) 194 (*(*pgops)->pgo_init) (); 195 } 196 197 void 198 vm_pager_bufferinit(void) 199 { 200 struct buf *bp; 201 int i; 202 203 bp = swbuf; 204 /* 205 * Now set up swap and physical I/O buffer headers. 206 */ 207 for (i = 0; i < nswbuf; i++, bp++) { 208 TAILQ_INSERT_HEAD(&bswlist, bp, b_freelist); 209 BUF_LOCKINIT(bp); 210 LIST_INIT(&bp->b_dep); 211 bp->b_xflags = 0; 212 } 213 214 cluster_pbuf_freecnt = nswbuf / 2; 215 216 swapbkva = kmem_alloc_pageable(pager_map, nswbuf * MAXPHYS); 217 if (!swapbkva) 218 panic("Not enough pager_map VM space for physical buffers"); 219 } 220 221 /* 222 * Allocate an instance of a pager of the given type. 223 * Size, protection and offset parameters are passed in for pagers that 224 * need to perform page-level validation (e.g. the device pager). 225 */ 226 vm_object_t 227 vm_pager_allocate(objtype_t type, void *handle, vm_ooffset_t size, vm_prot_t prot, 228 vm_ooffset_t off) 229 { 230 struct pagerops *ops; 231 232 ops = pagertab[type]; 233 if (ops) 234 return ((*ops->pgo_alloc) (handle, size, prot, off)); 235 return (NULL); 236 } 237 238 void 239 vm_pager_deallocate(vm_object_t object) 240 { 241 (*pagertab[object->type]->pgo_dealloc) (object); 242 } 243 244 /* 245 * vm_pager_strategy: 246 * 247 * called with no specific spl 248 * Execute strategy routine directly to pager. 249 */ 250 251 void 252 vm_pager_strategy(vm_object_t object, struct buf *bp) 253 { 254 if (pagertab[object->type]->pgo_strategy) { 255 (*pagertab[object->type]->pgo_strategy)(object, bp); 256 } else { 257 bp->b_flags |= B_ERROR; 258 bp->b_error = ENXIO; 259 biodone(bp); 260 } 261 } 262 263 /* 264 * vm_pager_get_pages() - inline, see vm/vm_pager.h 265 * vm_pager_put_pages() - inline, see vm/vm_pager.h 266 * vm_pager_has_page() - inline, see vm/vm_pager.h 267 * vm_pager_page_inserted() - inline, see vm/vm_pager.h 268 * vm_pager_page_removed() - inline, see vm/vm_pager.h 269 */ 270 271 #if 0 272 /* 273 * vm_pager_sync: 274 * 275 * Called by pageout daemon before going back to sleep. 276 * Gives pagers a chance to clean up any completed async pageing 277 * operations. 278 */ 279 void 280 vm_pager_sync(void) 281 { 282 struct pagerops **pgops; 283 284 for (pgops = pagertab; pgops < &pagertab[npagers]; pgops++) 285 if (pgops && ((*pgops)->pgo_sync != NULL)) 286 (*(*pgops)->pgo_sync) (); 287 } 288 289 #endif 290 291 vm_object_t 292 vm_pager_object_lookup(struct pagerlst *pg_list, void *handle) 293 { 294 vm_object_t object; 295 296 for (object = TAILQ_FIRST(pg_list); object != NULL; object = TAILQ_NEXT(object,pager_object_list)) 297 if (object->handle == handle) 298 return (object); 299 return (NULL); 300 } 301 302 /* 303 * initialize a physical buffer 304 */ 305 306 static void 307 initpbuf(struct buf *bp) 308 { 309 bp->b_qindex = QUEUE_NONE; 310 bp->b_data = (caddr_t) (MAXPHYS * (bp - swbuf)) + swapbkva; 311 bp->b_kvabase = bp->b_data; 312 bp->b_kvasize = MAXPHYS; 313 bp->b_xflags = 0; 314 bp->b_flags = 0; 315 bp->b_error = 0; 316 xio_init(&bp->b_xio); 317 BUF_LOCK(bp, LK_EXCLUSIVE); 318 } 319 320 /* 321 * allocate a physical buffer 322 * 323 * There are a limited number (nswbuf) of physical buffers. We need 324 * to make sure that no single subsystem is able to hog all of them, 325 * so each subsystem implements a counter which is typically initialized 326 * to 1/2 nswbuf. getpbuf() decrements this counter in allocation and 327 * increments it on release, and blocks if the counter hits zero. A 328 * subsystem may initialize the counter to -1 to disable the feature, 329 * but it must still be sure to match up all uses of getpbuf() with 330 * relpbuf() using the same variable. 331 * 332 * NOTE: pfreecnt can be NULL, but this 'feature' will be removed 333 * relatively soon when the rest of the subsystems get smart about it. XXX 334 */ 335 struct buf * 336 getpbuf(int *pfreecnt) 337 { 338 int s; 339 struct buf *bp; 340 341 s = splvm(); 342 343 for (;;) { 344 if (pfreecnt) { 345 while (*pfreecnt == 0) { 346 tsleep(pfreecnt, 0, "wswbuf0", 0); 347 } 348 } 349 350 /* get a bp from the swap buffer header pool */ 351 if ((bp = TAILQ_FIRST(&bswlist)) != NULL) 352 break; 353 354 bswneeded = 1; 355 tsleep(&bswneeded, 0, "wswbuf1", 0); 356 /* loop in case someone else grabbed one */ 357 } 358 TAILQ_REMOVE(&bswlist, bp, b_freelist); 359 if (pfreecnt) 360 --*pfreecnt; 361 splx(s); 362 363 initpbuf(bp); 364 return bp; 365 } 366 367 /* 368 * allocate a physical buffer, if one is available. 369 * 370 * Note that there is no NULL hack here - all subsystems using this 371 * call understand how to use pfreecnt. 372 */ 373 struct buf * 374 trypbuf(int *pfreecnt) 375 { 376 int s; 377 struct buf *bp; 378 379 s = splvm(); 380 if (*pfreecnt == 0 || (bp = TAILQ_FIRST(&bswlist)) == NULL) { 381 splx(s); 382 return NULL; 383 } 384 TAILQ_REMOVE(&bswlist, bp, b_freelist); 385 386 --*pfreecnt; 387 388 splx(s); 389 390 initpbuf(bp); 391 392 return bp; 393 } 394 395 /* 396 * release a physical buffer 397 * 398 * NOTE: pfreecnt can be NULL, but this 'feature' will be removed 399 * relatively soon when the rest of the subsystems get smart about it. XXX 400 */ 401 void 402 relpbuf(struct buf *bp, int *pfreecnt) 403 { 404 int s; 405 406 s = splvm(); 407 408 if (bp->b_vp) 409 pbrelvp(bp); 410 411 BUF_UNLOCK(bp); 412 413 TAILQ_INSERT_HEAD(&bswlist, bp, b_freelist); 414 415 if (bswneeded) { 416 bswneeded = 0; 417 wakeup(&bswneeded); 418 } 419 if (pfreecnt) { 420 if (++*pfreecnt == 1) 421 wakeup(pfreecnt); 422 } 423 splx(s); 424 } 425 426 /******************************************************** 427 * CHAINING FUNCTIONS * 428 ******************************************************** 429 * 430 * These functions support recursion of I/O operations 431 * on bp's, typically by chaining one or more 'child' bp's 432 * to the parent. Synchronous, asynchronous, and semi-synchronous 433 * chaining is possible. 434 */ 435 436 /* 437 * vm_pager_chain_iodone: 438 * 439 * io completion routine for child bp. Currently we fudge a bit 440 * on dealing with b_resid. Since users of these routines may issue 441 * multiple children simultaniously, sequencing of the error can be lost. 442 */ 443 444 static void 445 vm_pager_chain_iodone(struct buf *nbp) 446 { 447 struct buf *bp; 448 449 if ((bp = nbp->b_chain.parent) != NULL) { 450 if (nbp->b_flags & B_ERROR) { 451 bp->b_flags |= B_ERROR; 452 bp->b_error = nbp->b_error; 453 } else if (nbp->b_resid != 0) { 454 bp->b_flags |= B_ERROR; 455 bp->b_error = EINVAL; 456 } else { 457 bp->b_resid -= nbp->b_bcount; 458 } 459 nbp->b_chain.parent = NULL; 460 --bp->b_chain.count; 461 if (bp->b_flags & B_WANT) { 462 bp->b_flags &= ~B_WANT; 463 wakeup(bp); 464 } 465 if (!bp->b_chain.count && (bp->b_xflags & BX_AUTOCHAINDONE)) { 466 bp->b_xflags &= ~BX_AUTOCHAINDONE; 467 if (bp->b_resid != 0 && !(bp->b_flags & B_ERROR)) { 468 bp->b_flags |= B_ERROR; 469 bp->b_error = EINVAL; 470 } 471 biodone(bp); 472 } 473 } 474 nbp->b_flags |= B_DONE; 475 nbp->b_flags &= ~B_ASYNC; 476 relpbuf(nbp, NULL); 477 } 478 479 /* 480 * getchainbuf: 481 * 482 * Obtain a physical buffer and chain it to its parent buffer. When 483 * I/O completes, the parent buffer will be B_SIGNAL'd. Errors are 484 * automatically propogated to the parent 485 * 486 * Since these are brand new buffers, we do not have to clear B_INVAL 487 * and B_ERROR because they are already clear. 488 */ 489 490 struct buf * 491 getchainbuf(struct buf *bp, struct vnode *vp, int flags) 492 { 493 struct buf *nbp = getpbuf(NULL); 494 495 nbp->b_chain.parent = bp; 496 ++bp->b_chain.count; 497 498 if (bp->b_chain.count > 4) 499 waitchainbuf(bp, 4, 0); 500 501 nbp->b_flags = B_CALL | (bp->b_flags & B_ORDERED) | flags; 502 nbp->b_iodone = vm_pager_chain_iodone; 503 504 if (vp) 505 pbgetvp(vp, nbp); 506 return(nbp); 507 } 508 509 void 510 flushchainbuf(struct buf *nbp) 511 { 512 if (nbp->b_bcount) { 513 nbp->b_bufsize = nbp->b_bcount; 514 if ((nbp->b_flags & B_READ) == 0) 515 nbp->b_dirtyend = nbp->b_bcount; 516 BUF_KERNPROC(nbp); 517 VOP_STRATEGY(nbp->b_vp, nbp); 518 } else { 519 biodone(nbp); 520 } 521 } 522 523 void 524 waitchainbuf(struct buf *bp, int count, int done) 525 { 526 int s; 527 528 s = splbio(); 529 while (bp->b_chain.count > count) { 530 bp->b_flags |= B_WANT; 531 tsleep(bp, 0, "bpchain", 0); 532 } 533 if (done) { 534 if (bp->b_resid != 0 && !(bp->b_flags & B_ERROR)) { 535 bp->b_flags |= B_ERROR; 536 bp->b_error = EINVAL; 537 } 538 biodone(bp); 539 } 540 splx(s); 541 } 542 543 void 544 autochaindone(struct buf *bp) 545 { 546 int s; 547 548 s = splbio(); 549 if (bp->b_chain.count == 0) 550 biodone(bp); 551 else 552 bp->b_xflags |= BX_AUTOCHAINDONE; 553 splx(s); 554 } 555