1 /*- 2 * SPDX-License-Identifier: (BSD-3-Clause AND MIT-CMU) 3 * 4 * Copyright (c) 1991, 1993 5 * The Regents of the University of California. All rights reserved. 6 * 7 * This code is derived from software contributed to Berkeley by 8 * The Mach Operating System project at Carnegie-Mellon University. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. Neither the name of the University nor the names of its contributors 19 * may be used to endorse or promote products derived from this software 20 * without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 * 34 * from: @(#)vm_pager.c 8.6 (Berkeley) 1/12/94 35 * 36 * 37 * Copyright (c) 1987, 1990 Carnegie-Mellon University. 38 * All rights reserved. 39 * 40 * Authors: Avadis Tevanian, Jr., Michael Wayne Young 41 * 42 * Permission to use, copy, modify and distribute this software and 43 * its documentation is hereby granted, provided that both the copyright 44 * notice and this permission notice appear in all copies of the 45 * software, derivative works or modified versions, and any portions 46 * thereof, and that both notices appear in supporting documentation. 47 * 48 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" 49 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND 50 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. 51 * 52 * Carnegie Mellon requests users of this software to return to 53 * 54 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU 55 * School of Computer Science 56 * Carnegie Mellon University 57 * Pittsburgh PA 15213-3890 58 * 59 * any improvements or extensions that they make and grant Carnegie the 60 * rights to redistribute these changes. 61 */ 62 63 /* 64 * Paging space routine stubs. Emulates a matchmaker-like interface 65 * for builtin pagers. 66 */ 67 68 #include <sys/cdefs.h> 69 __FBSDID("$FreeBSD$"); 70 71 #include <sys/param.h> 72 #include <sys/systm.h> 73 #include <sys/kernel.h> 74 #include <sys/vnode.h> 75 #include <sys/bio.h> 76 #include <sys/buf.h> 77 #include <sys/ucred.h> 78 #include <sys/malloc.h> 79 #include <sys/rwlock.h> 80 81 #include <vm/vm.h> 82 #include <vm/vm_param.h> 83 #include <vm/vm_kern.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 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 { 112 113 return (NULL); 114 } 115 116 static void 117 dead_pager_putpages(vm_object_t object, vm_page_t *m, int count, 118 int flags, int *rtvals) 119 { 120 int i; 121 122 for (i = 0; i < count; i++) 123 rtvals[i] = VM_PAGER_AGAIN; 124 } 125 126 static int 127 dead_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *prev, int *next) 128 { 129 130 if (prev != NULL) 131 *prev = 0; 132 if (next != NULL) 133 *next = 0; 134 return (FALSE); 135 } 136 137 static void 138 dead_pager_dealloc(vm_object_t object) 139 { 140 141 } 142 143 static struct pagerops deadpagerops = { 144 .pgo_alloc = dead_pager_alloc, 145 .pgo_dealloc = dead_pager_dealloc, 146 .pgo_getpages = dead_pager_getpages, 147 .pgo_putpages = dead_pager_putpages, 148 .pgo_haspage = dead_pager_haspage, 149 }; 150 151 struct pagerops *pagertab[] = { 152 &defaultpagerops, /* OBJT_DEFAULT */ 153 &swappagerops, /* OBJT_SWAP */ 154 &vnodepagerops, /* OBJT_VNODE */ 155 &devicepagerops, /* OBJT_DEVICE */ 156 &physpagerops, /* OBJT_PHYS */ 157 &deadpagerops, /* OBJT_DEAD */ 158 &sgpagerops, /* OBJT_SG */ 159 &mgtdevicepagerops, /* OBJT_MGTDEVICE */ 160 }; 161 162 /* 163 * Kernel address space for mapping pages. 164 * Used by pagers where KVAs are needed for IO. 165 * 166 * XXX needs to be large enough to support the number of pending async 167 * cleaning requests (NPENDINGIO == 64) * the maximum swap cluster size 168 * (MAXPHYS == 64k) if you want to get the most efficiency. 169 */ 170 struct mtx_padalign __exclusive_cache_line pbuf_mtx; 171 static TAILQ_HEAD(swqueue, buf) bswlist; 172 static int bswneeded; 173 vm_offset_t swapbkva; /* swap buffers kva */ 174 175 void 176 vm_pager_init(void) 177 { 178 struct pagerops **pgops; 179 180 TAILQ_INIT(&bswlist); 181 /* 182 * Initialize known pagers 183 */ 184 for (pgops = pagertab; pgops < &pagertab[nitems(pagertab)]; pgops++) 185 if ((*pgops)->pgo_init != NULL) 186 (*(*pgops)->pgo_init)(); 187 } 188 189 void 190 vm_pager_bufferinit(void) 191 { 192 struct buf *bp; 193 int i; 194 195 mtx_init(&pbuf_mtx, "pbuf mutex", NULL, MTX_DEF); 196 bp = swbuf; 197 /* 198 * Now set up swap and physical I/O buffer headers. 199 */ 200 for (i = 0; i < nswbuf; i++, bp++) { 201 TAILQ_INSERT_HEAD(&bswlist, bp, b_freelist); 202 BUF_LOCKINIT(bp); 203 LIST_INIT(&bp->b_dep); 204 bp->b_rcred = bp->b_wcred = NOCRED; 205 bp->b_xflags = 0; 206 } 207 208 cluster_pbuf_freecnt = nswbuf / 2; 209 vnode_pbuf_freecnt = nswbuf / 2 + 1; 210 vnode_async_pbuf_freecnt = nswbuf / 2; 211 } 212 213 /* 214 * Allocate an instance of a pager of the given type. 215 * Size, protection and offset parameters are passed in for pagers that 216 * need to perform page-level validation (e.g. the device pager). 217 */ 218 vm_object_t 219 vm_pager_allocate(objtype_t type, void *handle, vm_ooffset_t size, 220 vm_prot_t prot, vm_ooffset_t off, struct ucred *cred) 221 { 222 vm_object_t ret; 223 struct pagerops *ops; 224 225 ops = pagertab[type]; 226 if (ops) 227 ret = (*ops->pgo_alloc)(handle, size, prot, off, cred); 228 else 229 ret = NULL; 230 return (ret); 231 } 232 233 /* 234 * The object must be locked. 235 */ 236 void 237 vm_pager_deallocate(vm_object_t object) 238 { 239 240 VM_OBJECT_ASSERT_WLOCKED(object); 241 (*pagertab[object->type]->pgo_dealloc) (object); 242 } 243 244 static void 245 vm_pager_assert_in(vm_object_t object, vm_page_t *m, int count) 246 { 247 #ifdef INVARIANTS 248 249 VM_OBJECT_ASSERT_WLOCKED(object); 250 KASSERT(count > 0, ("%s: 0 count", __func__)); 251 /* 252 * All pages must be busied, not mapped, not fully valid, 253 * not dirty and belong to the proper object. 254 */ 255 for (int i = 0 ; i < count; i++) { 256 if (m[i] == bogus_page) 257 continue; 258 vm_page_assert_xbusied(m[i]); 259 KASSERT(!pmap_page_is_mapped(m[i]), 260 ("%s: page %p is mapped", __func__, m[i])); 261 KASSERT(m[i]->valid != VM_PAGE_BITS_ALL, 262 ("%s: request for a valid page %p", __func__, m[i])); 263 KASSERT(m[i]->dirty == 0, 264 ("%s: page %p is dirty", __func__, m[i])); 265 KASSERT(m[i]->object == object, 266 ("%s: wrong object %p/%p", __func__, object, m[i]->object)); 267 } 268 #endif 269 } 270 271 /* 272 * Page in the pages for the object using its associated pager. 273 * The requested page must be fully valid on successful return. 274 */ 275 int 276 vm_pager_get_pages(vm_object_t object, vm_page_t *m, int count, int *rbehind, 277 int *rahead) 278 { 279 #ifdef INVARIANTS 280 vm_pindex_t pindex = m[0]->pindex; 281 #endif 282 int r; 283 284 vm_pager_assert_in(object, m, count); 285 286 r = (*pagertab[object->type]->pgo_getpages)(object, m, count, rbehind, 287 rahead); 288 if (r != VM_PAGER_OK) 289 return (r); 290 291 for (int i = 0; i < count; i++) { 292 /* 293 * If pager has replaced a page, assert that it had 294 * updated the array. 295 */ 296 KASSERT(m[i] == vm_page_lookup(object, pindex++), 297 ("%s: mismatch page %p pindex %ju", __func__, 298 m[i], (uintmax_t )pindex - 1)); 299 /* 300 * Zero out partially filled data. 301 */ 302 if (m[i]->valid != VM_PAGE_BITS_ALL) 303 vm_page_zero_invalid(m[i], TRUE); 304 } 305 return (VM_PAGER_OK); 306 } 307 308 int 309 vm_pager_get_pages_async(vm_object_t object, vm_page_t *m, int count, 310 int *rbehind, int *rahead, pgo_getpages_iodone_t iodone, void *arg) 311 { 312 313 vm_pager_assert_in(object, m, count); 314 315 return ((*pagertab[object->type]->pgo_getpages_async)(object, m, 316 count, rbehind, rahead, iodone, arg)); 317 } 318 319 /* 320 * vm_pager_put_pages() - inline, see vm/vm_pager.h 321 * vm_pager_has_page() - inline, see vm/vm_pager.h 322 */ 323 324 /* 325 * Search the specified pager object list for an object with the 326 * specified handle. If an object with the specified handle is found, 327 * increase its reference count and return it. Otherwise, return NULL. 328 * 329 * The pager object list must be locked. 330 */ 331 vm_object_t 332 vm_pager_object_lookup(struct pagerlst *pg_list, void *handle) 333 { 334 vm_object_t object; 335 336 TAILQ_FOREACH(object, pg_list, pager_object_list) { 337 if (object->handle == handle) { 338 VM_OBJECT_WLOCK(object); 339 if ((object->flags & OBJ_DEAD) == 0) { 340 vm_object_reference_locked(object); 341 VM_OBJECT_WUNLOCK(object); 342 break; 343 } 344 VM_OBJECT_WUNLOCK(object); 345 } 346 } 347 return (object); 348 } 349 350 /* 351 * initialize a physical buffer 352 */ 353 354 /* 355 * XXX This probably belongs in vfs_bio.c 356 */ 357 static void 358 initpbuf(struct buf *bp) 359 { 360 361 KASSERT(bp->b_bufobj == NULL, ("initpbuf with bufobj")); 362 KASSERT(bp->b_vp == NULL, ("initpbuf with vp")); 363 bp->b_rcred = NOCRED; 364 bp->b_wcred = NOCRED; 365 bp->b_qindex = 0; /* On no queue (QUEUE_NONE) */ 366 bp->b_kvabase = (caddr_t)(MAXPHYS * (bp - swbuf)) + swapbkva; 367 bp->b_data = bp->b_kvabase; 368 bp->b_kvasize = MAXPHYS; 369 bp->b_flags = 0; 370 bp->b_xflags = 0; 371 bp->b_ioflags = 0; 372 bp->b_iodone = NULL; 373 bp->b_error = 0; 374 BUF_LOCK(bp, LK_EXCLUSIVE, NULL); 375 buf_track(bp, __func__); 376 } 377 378 /* 379 * allocate a physical buffer 380 * 381 * There are a limited number (nswbuf) of physical buffers. We need 382 * to make sure that no single subsystem is able to hog all of them, 383 * so each subsystem implements a counter which is typically initialized 384 * to 1/2 nswbuf. getpbuf() decrements this counter in allocation and 385 * increments it on release, and blocks if the counter hits zero. A 386 * subsystem may initialize the counter to -1 to disable the feature, 387 * but it must still be sure to match up all uses of getpbuf() with 388 * relpbuf() using the same variable. 389 * 390 * NOTE: pfreecnt can be NULL, but this 'feature' will be removed 391 * relatively soon when the rest of the subsystems get smart about it. XXX 392 */ 393 struct buf * 394 getpbuf(int *pfreecnt) 395 { 396 struct buf *bp; 397 398 mtx_lock(&pbuf_mtx); 399 for (;;) { 400 if (pfreecnt != NULL) { 401 while (*pfreecnt == 0) { 402 msleep(pfreecnt, &pbuf_mtx, PVM, "wswbuf0", 0); 403 } 404 } 405 406 /* get a bp from the swap buffer header pool */ 407 if ((bp = TAILQ_FIRST(&bswlist)) != NULL) 408 break; 409 410 bswneeded = 1; 411 msleep(&bswneeded, &pbuf_mtx, PVM, "wswbuf1", 0); 412 /* loop in case someone else grabbed one */ 413 } 414 TAILQ_REMOVE(&bswlist, bp, b_freelist); 415 if (pfreecnt) 416 --*pfreecnt; 417 mtx_unlock(&pbuf_mtx); 418 initpbuf(bp); 419 return (bp); 420 } 421 422 /* 423 * allocate a physical buffer, if one is available. 424 * 425 * Note that there is no NULL hack here - all subsystems using this 426 * call understand how to use pfreecnt. 427 */ 428 struct buf * 429 trypbuf(int *pfreecnt) 430 { 431 struct buf *bp; 432 433 mtx_lock(&pbuf_mtx); 434 if (*pfreecnt == 0 || (bp = TAILQ_FIRST(&bswlist)) == NULL) { 435 mtx_unlock(&pbuf_mtx); 436 return NULL; 437 } 438 TAILQ_REMOVE(&bswlist, bp, b_freelist); 439 --*pfreecnt; 440 mtx_unlock(&pbuf_mtx); 441 initpbuf(bp); 442 return (bp); 443 } 444 445 /* 446 * release a physical buffer 447 * 448 * NOTE: pfreecnt can be NULL, but this 'feature' will be removed 449 * relatively soon when the rest of the subsystems get smart about it. XXX 450 */ 451 void 452 relpbuf(struct buf *bp, int *pfreecnt) 453 { 454 455 if (bp->b_rcred != NOCRED) { 456 crfree(bp->b_rcred); 457 bp->b_rcred = NOCRED; 458 } 459 if (bp->b_wcred != NOCRED) { 460 crfree(bp->b_wcred); 461 bp->b_wcred = NOCRED; 462 } 463 464 KASSERT(bp->b_vp == NULL, ("relpbuf with vp")); 465 KASSERT(bp->b_bufobj == NULL, ("relpbuf with bufobj")); 466 467 buf_track(bp, __func__); 468 BUF_UNLOCK(bp); 469 470 mtx_lock(&pbuf_mtx); 471 TAILQ_INSERT_HEAD(&bswlist, bp, b_freelist); 472 473 if (bswneeded) { 474 bswneeded = 0; 475 wakeup(&bswneeded); 476 } 477 if (pfreecnt) { 478 if (++*pfreecnt == 1) 479 wakeup(pfreecnt); 480 } 481 mtx_unlock(&pbuf_mtx); 482 } 483 484 /* 485 * Associate a p-buffer with a vnode. 486 * 487 * Also sets B_PAGING flag to indicate that vnode is not fully associated 488 * with the buffer. i.e. the bp has not been linked into the vnode or 489 * ref-counted. 490 */ 491 void 492 pbgetvp(struct vnode *vp, struct buf *bp) 493 { 494 495 KASSERT(bp->b_vp == NULL, ("pbgetvp: not free")); 496 KASSERT(bp->b_bufobj == NULL, ("pbgetvp: not free (bufobj)")); 497 498 bp->b_vp = vp; 499 bp->b_flags |= B_PAGING; 500 bp->b_bufobj = &vp->v_bufobj; 501 } 502 503 /* 504 * Associate a p-buffer with a vnode. 505 * 506 * Also sets B_PAGING flag to indicate that vnode is not fully associated 507 * with the buffer. i.e. the bp has not been linked into the vnode or 508 * ref-counted. 509 */ 510 void 511 pbgetbo(struct bufobj *bo, struct buf *bp) 512 { 513 514 KASSERT(bp->b_vp == NULL, ("pbgetbo: not free (vnode)")); 515 KASSERT(bp->b_bufobj == NULL, ("pbgetbo: not free (bufobj)")); 516 517 bp->b_flags |= B_PAGING; 518 bp->b_bufobj = bo; 519 } 520 521 /* 522 * Disassociate a p-buffer from a vnode. 523 */ 524 void 525 pbrelvp(struct buf *bp) 526 { 527 528 KASSERT(bp->b_vp != NULL, ("pbrelvp: NULL")); 529 KASSERT(bp->b_bufobj != NULL, ("pbrelvp: NULL bufobj")); 530 KASSERT((bp->b_xflags & (BX_VNDIRTY | BX_VNCLEAN)) == 0, 531 ("pbrelvp: pager buf on vnode list.")); 532 533 bp->b_vp = NULL; 534 bp->b_bufobj = NULL; 535 bp->b_flags &= ~B_PAGING; 536 } 537 538 /* 539 * Disassociate a p-buffer from a bufobj. 540 */ 541 void 542 pbrelbo(struct buf *bp) 543 { 544 545 KASSERT(bp->b_vp == NULL, ("pbrelbo: vnode")); 546 KASSERT(bp->b_bufobj != NULL, ("pbrelbo: NULL bufobj")); 547 KASSERT((bp->b_xflags & (BX_VNDIRTY | BX_VNCLEAN)) == 0, 548 ("pbrelbo: pager buf on vnode list.")); 549 550 bp->b_bufobj = NULL; 551 bp->b_flags &= ~B_PAGING; 552 } 553