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 * 4. Neither the name of the University nor the names of its contributors 17 * may be used to endorse or promote products derived from this software 18 * without specific prior written permission. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30 * SUCH DAMAGE. 31 * 32 * from: @(#)vm_pager.c 8.6 (Berkeley) 1/12/94 33 * 34 * 35 * Copyright (c) 1987, 1990 Carnegie-Mellon University. 36 * All rights reserved. 37 * 38 * Authors: Avadis Tevanian, Jr., Michael Wayne Young 39 * 40 * Permission to use, copy, modify and distribute this software and 41 * its documentation is hereby granted, provided that both the copyright 42 * notice and this permission notice appear in all copies of the 43 * software, derivative works or modified versions, and any portions 44 * thereof, and that both notices appear in supporting documentation. 45 * 46 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" 47 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND 48 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. 49 * 50 * Carnegie Mellon requests users of this software to return to 51 * 52 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU 53 * School of Computer Science 54 * Carnegie Mellon University 55 * Pittsburgh PA 15213-3890 56 * 57 * any improvements or extensions that they make and grant Carnegie the 58 * rights to redistribute these changes. 59 */ 60 61 /* 62 * Paging space routine stubs. Emulates a matchmaker-like interface 63 * for builtin pagers. 64 */ 65 66 #include <sys/cdefs.h> 67 __FBSDID("$FreeBSD$"); 68 69 #include <sys/param.h> 70 #include <sys/systm.h> 71 #include <sys/kernel.h> 72 #include <sys/vnode.h> 73 #include <sys/bio.h> 74 #include <sys/buf.h> 75 #include <sys/ucred.h> 76 #include <sys/malloc.h> 77 #include <sys/rwlock.h> 78 79 #include <vm/vm.h> 80 #include <vm/vm_param.h> 81 #include <vm/vm_kern.h> 82 #include <vm/vm_object.h> 83 #include <vm/vm_page.h> 84 #include <vm/vm_pager.h> 85 #include <vm/vm_extern.h> 86 87 extern vm_page_t bogus_page; 88 89 int cluster_pbuf_freecnt = -1; /* unlimited to begin with */ 90 91 struct buf *swbuf; 92 93 static int dead_pager_getpages(vm_object_t, vm_page_t *, int, int *, int *); 94 static vm_object_t dead_pager_alloc(void *, vm_ooffset_t, vm_prot_t, 95 vm_ooffset_t, struct ucred *); 96 static void dead_pager_putpages(vm_object_t, vm_page_t *, int, int, int *); 97 static boolean_t dead_pager_haspage(vm_object_t, vm_pindex_t, int *, int *); 98 static void dead_pager_dealloc(vm_object_t); 99 100 static int 101 dead_pager_getpages(vm_object_t obj, vm_page_t *ma, int count, int *rbehind, 102 int *rahead) 103 { 104 105 return (VM_PAGER_FAIL); 106 } 107 108 static vm_object_t 109 dead_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot, 110 vm_ooffset_t off, struct ucred *cred) 111 { 112 return NULL; 113 } 114 115 static void 116 dead_pager_putpages(object, m, count, flags, rtvals) 117 vm_object_t object; 118 vm_page_t *m; 119 int count; 120 int flags; 121 int *rtvals; 122 { 123 int i; 124 125 for (i = 0; i < count; i++) { 126 rtvals[i] = VM_PAGER_AGAIN; 127 } 128 } 129 130 static int 131 dead_pager_haspage(object, pindex, prev, next) 132 vm_object_t object; 133 vm_pindex_t pindex; 134 int *prev; 135 int *next; 136 { 137 if (prev) 138 *prev = 0; 139 if (next) 140 *next = 0; 141 return FALSE; 142 } 143 144 static void 145 dead_pager_dealloc(object) 146 vm_object_t object; 147 { 148 return; 149 } 150 151 static struct pagerops deadpagerops = { 152 .pgo_alloc = dead_pager_alloc, 153 .pgo_dealloc = dead_pager_dealloc, 154 .pgo_getpages = dead_pager_getpages, 155 .pgo_putpages = dead_pager_putpages, 156 .pgo_haspage = dead_pager_haspage, 157 }; 158 159 struct pagerops *pagertab[] = { 160 &defaultpagerops, /* OBJT_DEFAULT */ 161 &swappagerops, /* OBJT_SWAP */ 162 &vnodepagerops, /* OBJT_VNODE */ 163 &devicepagerops, /* OBJT_DEVICE */ 164 &physpagerops, /* OBJT_PHYS */ 165 &deadpagerops, /* OBJT_DEAD */ 166 &sgpagerops, /* OBJT_SG */ 167 &mgtdevicepagerops, /* OBJT_MGTDEVICE */ 168 }; 169 170 /* 171 * Kernel address space for mapping pages. 172 * Used by pagers where KVAs are needed for IO. 173 * 174 * XXX needs to be large enough to support the number of pending async 175 * cleaning requests (NPENDINGIO == 64) * the maximum swap cluster size 176 * (MAXPHYS == 64k) if you want to get the most efficiency. 177 */ 178 struct mtx_padalign pbuf_mtx; 179 static TAILQ_HEAD(swqueue, buf) bswlist; 180 static int bswneeded; 181 vm_offset_t swapbkva; /* swap buffers kva */ 182 183 void 184 vm_pager_init() 185 { 186 struct pagerops **pgops; 187 188 TAILQ_INIT(&bswlist); 189 /* 190 * Initialize known pagers 191 */ 192 for (pgops = pagertab; pgops < &pagertab[nitems(pagertab)]; pgops++) 193 if ((*pgops)->pgo_init != NULL) 194 (*(*pgops)->pgo_init) (); 195 } 196 197 void 198 vm_pager_bufferinit() 199 { 200 struct buf *bp; 201 int i; 202 203 mtx_init(&pbuf_mtx, "pbuf mutex", NULL, MTX_DEF); 204 bp = swbuf; 205 /* 206 * Now set up swap and physical I/O buffer headers. 207 */ 208 for (i = 0; i < nswbuf; i++, bp++) { 209 TAILQ_INSERT_HEAD(&bswlist, bp, b_freelist); 210 BUF_LOCKINIT(bp); 211 LIST_INIT(&bp->b_dep); 212 bp->b_rcred = bp->b_wcred = NOCRED; 213 bp->b_xflags = 0; 214 } 215 216 cluster_pbuf_freecnt = nswbuf / 2; 217 vnode_pbuf_freecnt = nswbuf / 2 + 1; 218 vnode_async_pbuf_freecnt = nswbuf / 2; 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, 228 vm_prot_t prot, vm_ooffset_t off, struct ucred *cred) 229 { 230 vm_object_t ret; 231 struct pagerops *ops; 232 233 ops = pagertab[type]; 234 if (ops) 235 ret = (*ops->pgo_alloc) (handle, size, prot, off, cred); 236 else 237 ret = NULL; 238 return (ret); 239 } 240 241 /* 242 * The object must be locked. 243 */ 244 void 245 vm_pager_deallocate(object) 246 vm_object_t object; 247 { 248 249 VM_OBJECT_ASSERT_WLOCKED(object); 250 (*pagertab[object->type]->pgo_dealloc) (object); 251 } 252 253 static void 254 vm_pager_assert_in(vm_object_t object, vm_page_t *m, int count) 255 { 256 #ifdef INVARIANTS 257 258 VM_OBJECT_ASSERT_WLOCKED(object); 259 KASSERT(count > 0, ("%s: 0 count", __func__)); 260 /* 261 * All pages must be busied, not mapped, not fully valid, 262 * not dirty and belong to the proper object. 263 */ 264 for (int i = 0 ; i < count; i++) { 265 if (m[i] == bogus_page) 266 continue; 267 vm_page_assert_xbusied(m[i]); 268 KASSERT(!pmap_page_is_mapped(m[i]), 269 ("%s: page %p is mapped", __func__, m[i])); 270 KASSERT(m[i]->valid != VM_PAGE_BITS_ALL, 271 ("%s: request for a valid page %p", __func__, m[i])); 272 KASSERT(m[i]->dirty == 0, 273 ("%s: page %p is dirty", __func__, m[i])); 274 KASSERT(m[i]->object == object, 275 ("%s: wrong object %p/%p", __func__, object, m[i]->object)); 276 } 277 #endif 278 } 279 280 /* 281 * Page in the pages for the object using its associated pager. 282 * The requested page must be fully valid on successful return. 283 */ 284 int 285 vm_pager_get_pages(vm_object_t object, vm_page_t *m, int count, int *rbehind, 286 int *rahead) 287 { 288 #ifdef INVARIANTS 289 vm_pindex_t pindex = m[0]->pindex; 290 #endif 291 int r; 292 293 vm_pager_assert_in(object, m, count); 294 295 r = (*pagertab[object->type]->pgo_getpages)(object, m, count, rbehind, 296 rahead); 297 if (r != VM_PAGER_OK) 298 return (r); 299 300 for (int i = 0; i < count; i++) { 301 /* 302 * If pager has replaced a page, assert that it had 303 * updated the array. 304 */ 305 KASSERT(m[i] == vm_page_lookup(object, pindex++), 306 ("%s: mismatch page %p pindex %ju", __func__, 307 m[i], (uintmax_t )pindex - 1)); 308 /* 309 * Zero out partially filled data. 310 */ 311 if (m[i]->valid != VM_PAGE_BITS_ALL) 312 vm_page_zero_invalid(m[i], TRUE); 313 } 314 return (VM_PAGER_OK); 315 } 316 317 int 318 vm_pager_get_pages_async(vm_object_t object, vm_page_t *m, int count, 319 int *rbehind, int *rahead, pgo_getpages_iodone_t iodone, void *arg) 320 { 321 322 vm_pager_assert_in(object, m, count); 323 324 return ((*pagertab[object->type]->pgo_getpages_async)(object, m, 325 count, rbehind, rahead, iodone, arg)); 326 } 327 328 /* 329 * vm_pager_put_pages() - inline, see vm/vm_pager.h 330 * vm_pager_has_page() - inline, see vm/vm_pager.h 331 */ 332 333 /* 334 * Search the specified pager object list for an object with the 335 * specified handle. If an object with the specified handle is found, 336 * increase its reference count and return it. Otherwise, return NULL. 337 * 338 * The pager object list must be locked. 339 */ 340 vm_object_t 341 vm_pager_object_lookup(struct pagerlst *pg_list, void *handle) 342 { 343 vm_object_t object; 344 345 TAILQ_FOREACH(object, pg_list, pager_object_list) { 346 if (object->handle == handle) { 347 VM_OBJECT_WLOCK(object); 348 if ((object->flags & OBJ_DEAD) == 0) { 349 vm_object_reference_locked(object); 350 VM_OBJECT_WUNLOCK(object); 351 break; 352 } 353 VM_OBJECT_WUNLOCK(object); 354 } 355 } 356 return (object); 357 } 358 359 /* 360 * initialize a physical buffer 361 */ 362 363 /* 364 * XXX This probably belongs in vfs_bio.c 365 */ 366 static void 367 initpbuf(struct buf *bp) 368 { 369 KASSERT(bp->b_bufobj == NULL, ("initpbuf with bufobj")); 370 KASSERT(bp->b_vp == NULL, ("initpbuf with vp")); 371 bp->b_rcred = NOCRED; 372 bp->b_wcred = NOCRED; 373 bp->b_qindex = 0; /* On no queue (QUEUE_NONE) */ 374 bp->b_kvabase = (caddr_t) (MAXPHYS * (bp - swbuf)) + swapbkva; 375 bp->b_data = bp->b_kvabase; 376 bp->b_kvasize = MAXPHYS; 377 bp->b_flags = 0; 378 bp->b_xflags = 0; 379 bp->b_ioflags = 0; 380 bp->b_iodone = NULL; 381 bp->b_error = 0; 382 BUF_LOCK(bp, LK_EXCLUSIVE, NULL); 383 buf_track(bp, __func__); 384 } 385 386 /* 387 * allocate a physical buffer 388 * 389 * There are a limited number (nswbuf) of physical buffers. We need 390 * to make sure that no single subsystem is able to hog all of them, 391 * so each subsystem implements a counter which is typically initialized 392 * to 1/2 nswbuf. getpbuf() decrements this counter in allocation and 393 * increments it on release, and blocks if the counter hits zero. A 394 * subsystem may initialize the counter to -1 to disable the feature, 395 * but it must still be sure to match up all uses of getpbuf() with 396 * relpbuf() using the same variable. 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 struct buf * 402 getpbuf(int *pfreecnt) 403 { 404 struct buf *bp; 405 406 mtx_lock(&pbuf_mtx); 407 408 for (;;) { 409 if (pfreecnt) { 410 while (*pfreecnt == 0) { 411 msleep(pfreecnt, &pbuf_mtx, PVM, "wswbuf0", 0); 412 } 413 } 414 415 /* get a bp from the swap buffer header pool */ 416 if ((bp = TAILQ_FIRST(&bswlist)) != NULL) 417 break; 418 419 bswneeded = 1; 420 msleep(&bswneeded, &pbuf_mtx, PVM, "wswbuf1", 0); 421 /* loop in case someone else grabbed one */ 422 } 423 TAILQ_REMOVE(&bswlist, bp, b_freelist); 424 if (pfreecnt) 425 --*pfreecnt; 426 mtx_unlock(&pbuf_mtx); 427 428 initpbuf(bp); 429 return bp; 430 } 431 432 /* 433 * allocate a physical buffer, if one is available. 434 * 435 * Note that there is no NULL hack here - all subsystems using this 436 * call understand how to use pfreecnt. 437 */ 438 struct buf * 439 trypbuf(int *pfreecnt) 440 { 441 struct buf *bp; 442 443 mtx_lock(&pbuf_mtx); 444 if (*pfreecnt == 0 || (bp = TAILQ_FIRST(&bswlist)) == NULL) { 445 mtx_unlock(&pbuf_mtx); 446 return NULL; 447 } 448 TAILQ_REMOVE(&bswlist, bp, b_freelist); 449 450 --*pfreecnt; 451 452 mtx_unlock(&pbuf_mtx); 453 454 initpbuf(bp); 455 456 return bp; 457 } 458 459 /* 460 * release a physical buffer 461 * 462 * NOTE: pfreecnt can be NULL, but this 'feature' will be removed 463 * relatively soon when the rest of the subsystems get smart about it. XXX 464 */ 465 void 466 relpbuf(struct buf *bp, int *pfreecnt) 467 { 468 469 if (bp->b_rcred != NOCRED) { 470 crfree(bp->b_rcred); 471 bp->b_rcred = NOCRED; 472 } 473 if (bp->b_wcred != NOCRED) { 474 crfree(bp->b_wcred); 475 bp->b_wcred = NOCRED; 476 } 477 478 KASSERT(bp->b_vp == NULL, ("relpbuf with vp")); 479 KASSERT(bp->b_bufobj == NULL, ("relpbuf with bufobj")); 480 481 buf_track(bp, __func__); 482 BUF_UNLOCK(bp); 483 484 mtx_lock(&pbuf_mtx); 485 TAILQ_INSERT_HEAD(&bswlist, bp, b_freelist); 486 487 if (bswneeded) { 488 bswneeded = 0; 489 wakeup(&bswneeded); 490 } 491 if (pfreecnt) { 492 if (++*pfreecnt == 1) 493 wakeup(pfreecnt); 494 } 495 mtx_unlock(&pbuf_mtx); 496 } 497 498 /* 499 * Associate a p-buffer with a vnode. 500 * 501 * Also sets B_PAGING flag to indicate that vnode is not fully associated 502 * with the buffer. i.e. the bp has not been linked into the vnode or 503 * ref-counted. 504 */ 505 void 506 pbgetvp(struct vnode *vp, struct buf *bp) 507 { 508 509 KASSERT(bp->b_vp == NULL, ("pbgetvp: not free")); 510 KASSERT(bp->b_bufobj == NULL, ("pbgetvp: not free (bufobj)")); 511 512 bp->b_vp = vp; 513 bp->b_flags |= B_PAGING; 514 bp->b_bufobj = &vp->v_bufobj; 515 } 516 517 /* 518 * Associate a p-buffer with a vnode. 519 * 520 * Also sets B_PAGING flag to indicate that vnode is not fully associated 521 * with the buffer. i.e. the bp has not been linked into the vnode or 522 * ref-counted. 523 */ 524 void 525 pbgetbo(struct bufobj *bo, struct buf *bp) 526 { 527 528 KASSERT(bp->b_vp == NULL, ("pbgetbo: not free (vnode)")); 529 KASSERT(bp->b_bufobj == NULL, ("pbgetbo: not free (bufobj)")); 530 531 bp->b_flags |= B_PAGING; 532 bp->b_bufobj = bo; 533 } 534 535 /* 536 * Disassociate a p-buffer from a vnode. 537 */ 538 void 539 pbrelvp(struct buf *bp) 540 { 541 542 KASSERT(bp->b_vp != NULL, ("pbrelvp: NULL")); 543 KASSERT(bp->b_bufobj != NULL, ("pbrelvp: NULL bufobj")); 544 KASSERT((bp->b_xflags & (BX_VNDIRTY | BX_VNCLEAN)) == 0, 545 ("pbrelvp: pager buf on vnode list.")); 546 547 bp->b_vp = NULL; 548 bp->b_bufobj = NULL; 549 bp->b_flags &= ~B_PAGING; 550 } 551 552 /* 553 * Disassociate a p-buffer from a bufobj. 554 */ 555 void 556 pbrelbo(struct buf *bp) 557 { 558 559 KASSERT(bp->b_vp == NULL, ("pbrelbo: vnode")); 560 KASSERT(bp->b_bufobj != NULL, ("pbrelbo: NULL bufobj")); 561 KASSERT((bp->b_xflags & (BX_VNDIRTY | BX_VNCLEAN)) == 0, 562 ("pbrelbo: pager buf on vnode list.")); 563 564 bp->b_bufobj = NULL; 565 bp->b_flags &= ~B_PAGING; 566 } 567