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 int cluster_pbuf_freecnt = -1; /* unlimited to begin with */ 88 89 static int dead_pager_getpages(vm_object_t, vm_page_t *, int, int); 90 static vm_object_t dead_pager_alloc(void *, vm_ooffset_t, vm_prot_t, 91 vm_ooffset_t, struct ucred *); 92 static void dead_pager_putpages(vm_object_t, vm_page_t *, int, int, int *); 93 static boolean_t dead_pager_haspage(vm_object_t, vm_pindex_t, int *, int *); 94 static void dead_pager_dealloc(vm_object_t); 95 96 static int 97 dead_pager_getpages(obj, ma, count, req) 98 vm_object_t obj; 99 vm_page_t *ma; 100 int count; 101 int req; 102 { 103 return VM_PAGER_FAIL; 104 } 105 106 static vm_object_t 107 dead_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot, 108 vm_ooffset_t off, struct ucred *cred) 109 { 110 return NULL; 111 } 112 113 static void 114 dead_pager_putpages(object, m, count, flags, rtvals) 115 vm_object_t object; 116 vm_page_t *m; 117 int count; 118 int flags; 119 int *rtvals; 120 { 121 int i; 122 123 for (i = 0; i < count; i++) { 124 rtvals[i] = VM_PAGER_AGAIN; 125 } 126 } 127 128 static int 129 dead_pager_haspage(object, pindex, prev, next) 130 vm_object_t object; 131 vm_pindex_t pindex; 132 int *prev; 133 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(object) 144 vm_object_t object; 145 { 146 return; 147 } 148 149 static struct pagerops deadpagerops = { 150 .pgo_alloc = dead_pager_alloc, 151 .pgo_dealloc = dead_pager_dealloc, 152 .pgo_getpages = dead_pager_getpages, 153 .pgo_putpages = dead_pager_putpages, 154 .pgo_haspage = dead_pager_haspage, 155 }; 156 157 struct pagerops *pagertab[] = { 158 &defaultpagerops, /* OBJT_DEFAULT */ 159 &swappagerops, /* OBJT_SWAP */ 160 &vnodepagerops, /* OBJT_VNODE */ 161 &devicepagerops, /* OBJT_DEVICE */ 162 &physpagerops, /* OBJT_PHYS */ 163 &deadpagerops, /* OBJT_DEAD */ 164 &sgpagerops, /* OBJT_SG */ 165 &mgtdevicepagerops, /* OBJT_MGTDEVICE */ 166 }; 167 168 static const int npagers = sizeof(pagertab) / sizeof(pagertab[0]); 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[npagers]; 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 vm_page_assert_xbusied(m[i]); 266 KASSERT(!pmap_page_is_mapped(m[i]), 267 ("%s: page %p is mapped", __func__, m[i])); 268 KASSERT(m[i]->valid != VM_PAGE_BITS_ALL, 269 ("%s: request for a valid page %p", __func__, m[i])); 270 KASSERT(m[i]->dirty == 0, 271 ("%s: page %p is dirty", __func__, m[i])); 272 KASSERT(m[i]->object == object, 273 ("%s: wrong object %p/%p", __func__, object, m[i]->object)); 274 } 275 #endif 276 } 277 278 /* 279 * Page in the pages for the object using its associated pager. 280 * The requested page must be fully valid on successful return. 281 */ 282 int 283 vm_pager_get_pages(vm_object_t object, vm_page_t *m, int count, int reqpage) 284 { 285 int r; 286 287 vm_pager_assert_in(object, m, count); 288 289 r = (*pagertab[object->type]->pgo_getpages)(object, m, count, reqpage); 290 if (r != VM_PAGER_OK) 291 return (r); 292 293 /* 294 * If pager has replaced the page, assert that it had 295 * updated the array. Also assert that page is still 296 * busied. 297 */ 298 KASSERT(m[reqpage] == vm_page_lookup(object, m[reqpage]->pindex), 299 ("%s: mismatch page %p pindex %ju", __func__, 300 m[reqpage], (uintmax_t )m[reqpage]->pindex)); 301 vm_page_assert_xbusied(m[reqpage]); 302 303 /* 304 * Pager didn't fill up entire page. Zero out 305 * partially filled data. 306 */ 307 if (m[reqpage]->valid != VM_PAGE_BITS_ALL) 308 vm_page_zero_invalid(m[reqpage], TRUE); 309 310 return (VM_PAGER_OK); 311 } 312 313 int 314 vm_pager_get_pages_async(vm_object_t object, vm_page_t *m, int count, 315 int reqpage, pgo_getpages_iodone_t iodone, void *arg) 316 { 317 318 vm_pager_assert_in(object, m, count); 319 320 return ((*pagertab[object->type]->pgo_getpages_async)(object, m, 321 count, reqpage, iodone, arg)); 322 } 323 324 /* 325 * vm_pager_put_pages() - inline, see vm/vm_pager.h 326 * vm_pager_has_page() - inline, see vm/vm_pager.h 327 */ 328 329 /* 330 * Search the specified pager object list for an object with the 331 * specified handle. If an object with the specified handle is found, 332 * increase its reference count and return it. Otherwise, return NULL. 333 * 334 * The pager object list must be locked. 335 */ 336 vm_object_t 337 vm_pager_object_lookup(struct pagerlst *pg_list, void *handle) 338 { 339 vm_object_t object; 340 341 TAILQ_FOREACH(object, pg_list, pager_object_list) { 342 if (object->handle == handle) { 343 VM_OBJECT_WLOCK(object); 344 if ((object->flags & OBJ_DEAD) == 0) { 345 vm_object_reference_locked(object); 346 VM_OBJECT_WUNLOCK(object); 347 break; 348 } 349 VM_OBJECT_WUNLOCK(object); 350 } 351 } 352 return (object); 353 } 354 355 /* 356 * Free the non-requested pages from the given array. To remove all pages, 357 * caller should provide out of range reqpage number. 358 */ 359 void 360 vm_pager_free_nonreq(vm_object_t object, vm_page_t ma[], int reqpage, 361 int npages, boolean_t object_locked) 362 { 363 enum { UNLOCKED, CALLER_LOCKED, INTERNALLY_LOCKED } locked; 364 int i; 365 366 if (object_locked) { 367 VM_OBJECT_ASSERT_WLOCKED(object); 368 locked = CALLER_LOCKED; 369 } else { 370 VM_OBJECT_ASSERT_UNLOCKED(object); 371 locked = UNLOCKED; 372 } 373 for (i = 0; i < npages; ++i) { 374 if (i != reqpage) { 375 if (locked == UNLOCKED) { 376 VM_OBJECT_WLOCK(object); 377 locked = INTERNALLY_LOCKED; 378 } 379 vm_page_lock(ma[i]); 380 vm_page_free(ma[i]); 381 vm_page_unlock(ma[i]); 382 } 383 } 384 if (locked == INTERNALLY_LOCKED) 385 VM_OBJECT_WUNLOCK(object); 386 } 387 388 /* 389 * initialize a physical buffer 390 */ 391 392 /* 393 * XXX This probably belongs in vfs_bio.c 394 */ 395 static void 396 initpbuf(struct buf *bp) 397 { 398 KASSERT(bp->b_bufobj == NULL, ("initpbuf with bufobj")); 399 KASSERT(bp->b_vp == NULL, ("initpbuf with vp")); 400 bp->b_rcred = NOCRED; 401 bp->b_wcred = NOCRED; 402 bp->b_qindex = 0; /* On no queue (QUEUE_NONE) */ 403 bp->b_kvabase = (caddr_t) (MAXPHYS * (bp - swbuf)) + swapbkva; 404 bp->b_data = bp->b_kvabase; 405 bp->b_kvasize = MAXPHYS; 406 bp->b_flags = 0; 407 bp->b_xflags = 0; 408 bp->b_ioflags = 0; 409 bp->b_iodone = NULL; 410 bp->b_error = 0; 411 BUF_LOCK(bp, LK_EXCLUSIVE, NULL); 412 } 413 414 /* 415 * allocate a physical buffer 416 * 417 * There are a limited number (nswbuf) of physical buffers. We need 418 * to make sure that no single subsystem is able to hog all of them, 419 * so each subsystem implements a counter which is typically initialized 420 * to 1/2 nswbuf. getpbuf() decrements this counter in allocation and 421 * increments it on release, and blocks if the counter hits zero. A 422 * subsystem may initialize the counter to -1 to disable the feature, 423 * but it must still be sure to match up all uses of getpbuf() with 424 * relpbuf() using the same variable. 425 * 426 * NOTE: pfreecnt can be NULL, but this 'feature' will be removed 427 * relatively soon when the rest of the subsystems get smart about it. XXX 428 */ 429 struct buf * 430 getpbuf(int *pfreecnt) 431 { 432 struct buf *bp; 433 434 mtx_lock(&pbuf_mtx); 435 436 for (;;) { 437 if (pfreecnt) { 438 while (*pfreecnt == 0) { 439 msleep(pfreecnt, &pbuf_mtx, PVM, "wswbuf0", 0); 440 } 441 } 442 443 /* get a bp from the swap buffer header pool */ 444 if ((bp = TAILQ_FIRST(&bswlist)) != NULL) 445 break; 446 447 bswneeded = 1; 448 msleep(&bswneeded, &pbuf_mtx, PVM, "wswbuf1", 0); 449 /* loop in case someone else grabbed one */ 450 } 451 TAILQ_REMOVE(&bswlist, bp, b_freelist); 452 if (pfreecnt) 453 --*pfreecnt; 454 mtx_unlock(&pbuf_mtx); 455 456 initpbuf(bp); 457 return bp; 458 } 459 460 /* 461 * allocate a physical buffer, if one is available. 462 * 463 * Note that there is no NULL hack here - all subsystems using this 464 * call understand how to use pfreecnt. 465 */ 466 struct buf * 467 trypbuf(int *pfreecnt) 468 { 469 struct buf *bp; 470 471 mtx_lock(&pbuf_mtx); 472 if (*pfreecnt == 0 || (bp = TAILQ_FIRST(&bswlist)) == NULL) { 473 mtx_unlock(&pbuf_mtx); 474 return NULL; 475 } 476 TAILQ_REMOVE(&bswlist, bp, b_freelist); 477 478 --*pfreecnt; 479 480 mtx_unlock(&pbuf_mtx); 481 482 initpbuf(bp); 483 484 return bp; 485 } 486 487 /* 488 * release a physical buffer 489 * 490 * NOTE: pfreecnt can be NULL, but this 'feature' will be removed 491 * relatively soon when the rest of the subsystems get smart about it. XXX 492 */ 493 void 494 relpbuf(struct buf *bp, int *pfreecnt) 495 { 496 497 if (bp->b_rcred != NOCRED) { 498 crfree(bp->b_rcred); 499 bp->b_rcred = NOCRED; 500 } 501 if (bp->b_wcred != NOCRED) { 502 crfree(bp->b_wcred); 503 bp->b_wcred = NOCRED; 504 } 505 506 KASSERT(bp->b_vp == NULL, ("relpbuf with vp")); 507 KASSERT(bp->b_bufobj == NULL, ("relpbuf with bufobj")); 508 509 BUF_UNLOCK(bp); 510 511 mtx_lock(&pbuf_mtx); 512 TAILQ_INSERT_HEAD(&bswlist, bp, b_freelist); 513 514 if (bswneeded) { 515 bswneeded = 0; 516 wakeup(&bswneeded); 517 } 518 if (pfreecnt) { 519 if (++*pfreecnt == 1) 520 wakeup(pfreecnt); 521 } 522 mtx_unlock(&pbuf_mtx); 523 } 524 525 /* 526 * Associate a p-buffer with a vnode. 527 * 528 * Also sets B_PAGING flag to indicate that vnode is not fully associated 529 * with the buffer. i.e. the bp has not been linked into the vnode or 530 * ref-counted. 531 */ 532 void 533 pbgetvp(struct vnode *vp, struct buf *bp) 534 { 535 536 KASSERT(bp->b_vp == NULL, ("pbgetvp: not free")); 537 KASSERT(bp->b_bufobj == NULL, ("pbgetvp: not free (bufobj)")); 538 539 bp->b_vp = vp; 540 bp->b_flags |= B_PAGING; 541 bp->b_bufobj = &vp->v_bufobj; 542 } 543 544 /* 545 * Associate a p-buffer with a vnode. 546 * 547 * Also sets B_PAGING flag to indicate that vnode is not fully associated 548 * with the buffer. i.e. the bp has not been linked into the vnode or 549 * ref-counted. 550 */ 551 void 552 pbgetbo(struct bufobj *bo, struct buf *bp) 553 { 554 555 KASSERT(bp->b_vp == NULL, ("pbgetbo: not free (vnode)")); 556 KASSERT(bp->b_bufobj == NULL, ("pbgetbo: not free (bufobj)")); 557 558 bp->b_flags |= B_PAGING; 559 bp->b_bufobj = bo; 560 } 561 562 /* 563 * Disassociate a p-buffer from a vnode. 564 */ 565 void 566 pbrelvp(struct buf *bp) 567 { 568 569 KASSERT(bp->b_vp != NULL, ("pbrelvp: NULL")); 570 KASSERT(bp->b_bufobj != NULL, ("pbrelvp: NULL bufobj")); 571 KASSERT((bp->b_xflags & (BX_VNDIRTY | BX_VNCLEAN)) == 0, 572 ("pbrelvp: pager buf on vnode list.")); 573 574 bp->b_vp = NULL; 575 bp->b_bufobj = NULL; 576 bp->b_flags &= ~B_PAGING; 577 } 578 579 /* 580 * Disassociate a p-buffer from a bufobj. 581 */ 582 void 583 pbrelbo(struct buf *bp) 584 { 585 586 KASSERT(bp->b_vp == NULL, ("pbrelbo: vnode")); 587 KASSERT(bp->b_bufobj != NULL, ("pbrelbo: NULL bufobj")); 588 KASSERT((bp->b_xflags & (BX_VNDIRTY | BX_VNCLEAN)) == 0, 589 ("pbrelbo: pager buf on vnode list.")); 590 591 bp->b_bufobj = NULL; 592 bp->b_flags &= ~B_PAGING; 593 } 594