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 struct buf *swbuf; 90 91 static int dead_pager_getpages(vm_object_t, vm_page_t *, int, int *, int *); 92 static vm_object_t dead_pager_alloc(void *, vm_ooffset_t, vm_prot_t, 93 vm_ooffset_t, struct ucred *); 94 static void dead_pager_putpages(vm_object_t, vm_page_t *, int, int, int *); 95 static boolean_t dead_pager_haspage(vm_object_t, vm_pindex_t, int *, int *); 96 static void dead_pager_dealloc(vm_object_t); 97 98 static int 99 dead_pager_getpages(vm_object_t obj, vm_page_t *ma, int count, int *rbehind, 100 int *rahead) 101 { 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 /* 169 * Kernel address space for mapping pages. 170 * Used by pagers where KVAs are needed for IO. 171 * 172 * XXX needs to be large enough to support the number of pending async 173 * cleaning requests (NPENDINGIO == 64) * the maximum swap cluster size 174 * (MAXPHYS == 64k) if you want to get the most efficiency. 175 */ 176 struct mtx_padalign pbuf_mtx; 177 static TAILQ_HEAD(swqueue, buf) bswlist; 178 static int bswneeded; 179 vm_offset_t swapbkva; /* swap buffers kva */ 180 181 void 182 vm_pager_init() 183 { 184 struct pagerops **pgops; 185 186 TAILQ_INIT(&bswlist); 187 /* 188 * Initialize known pagers 189 */ 190 for (pgops = pagertab; pgops < &pagertab[nitems(pagertab)]; pgops++) 191 if ((*pgops)->pgo_init != NULL) 192 (*(*pgops)->pgo_init) (); 193 } 194 195 void 196 vm_pager_bufferinit() 197 { 198 struct buf *bp; 199 int i; 200 201 mtx_init(&pbuf_mtx, "pbuf mutex", NULL, MTX_DEF); 202 bp = swbuf; 203 /* 204 * Now set up swap and physical I/O buffer headers. 205 */ 206 for (i = 0; i < nswbuf; i++, bp++) { 207 TAILQ_INSERT_HEAD(&bswlist, bp, b_freelist); 208 BUF_LOCKINIT(bp); 209 LIST_INIT(&bp->b_dep); 210 bp->b_rcred = bp->b_wcred = NOCRED; 211 bp->b_xflags = 0; 212 } 213 214 cluster_pbuf_freecnt = nswbuf / 2; 215 vnode_pbuf_freecnt = nswbuf / 2 + 1; 216 vnode_async_pbuf_freecnt = nswbuf / 2; 217 } 218 219 /* 220 * Allocate an instance of a pager of the given type. 221 * Size, protection and offset parameters are passed in for pagers that 222 * need to perform page-level validation (e.g. the device pager). 223 */ 224 vm_object_t 225 vm_pager_allocate(objtype_t type, void *handle, vm_ooffset_t size, 226 vm_prot_t prot, vm_ooffset_t off, struct ucred *cred) 227 { 228 vm_object_t ret; 229 struct pagerops *ops; 230 231 ops = pagertab[type]; 232 if (ops) 233 ret = (*ops->pgo_alloc) (handle, size, prot, off, cred); 234 else 235 ret = NULL; 236 return (ret); 237 } 238 239 /* 240 * The object must be locked. 241 */ 242 void 243 vm_pager_deallocate(object) 244 vm_object_t object; 245 { 246 247 VM_OBJECT_ASSERT_WLOCKED(object); 248 (*pagertab[object->type]->pgo_dealloc) (object); 249 } 250 251 static void 252 vm_pager_assert_in(vm_object_t object, vm_page_t *m, int count) 253 { 254 #ifdef INVARIANTS 255 256 VM_OBJECT_ASSERT_WLOCKED(object); 257 KASSERT(count > 0, ("%s: 0 count", __func__)); 258 /* 259 * All pages must be busied, not mapped, not fully valid, 260 * not dirty and belong to the proper object. 261 */ 262 for (int i = 0 ; i < count; i++) { 263 vm_page_assert_xbusied(m[i]); 264 KASSERT(!pmap_page_is_mapped(m[i]), 265 ("%s: page %p is mapped", __func__, m[i])); 266 KASSERT(m[i]->valid != VM_PAGE_BITS_ALL, 267 ("%s: request for a valid page %p", __func__, m[i])); 268 KASSERT(m[i]->dirty == 0, 269 ("%s: page %p is dirty", __func__, m[i])); 270 KASSERT(m[i]->object == object, 271 ("%s: wrong object %p/%p", __func__, object, m[i]->object)); 272 } 273 #endif 274 } 275 276 /* 277 * Page in the pages for the object using its associated pager. 278 * The requested page must be fully valid on successful return. 279 */ 280 int 281 vm_pager_get_pages(vm_object_t object, vm_page_t *m, int count, int *rbehind, 282 int *rahead) 283 { 284 #ifdef INVARIANTS 285 vm_pindex_t pindex = m[0]->pindex; 286 #endif 287 int r; 288 289 vm_pager_assert_in(object, m, count); 290 291 r = (*pagertab[object->type]->pgo_getpages)(object, m, count, rbehind, 292 rahead); 293 if (r != VM_PAGER_OK) 294 return (r); 295 296 for (int i = 0; i < count; i++) { 297 /* 298 * If pager has replaced a page, assert that it had 299 * updated the array. 300 */ 301 KASSERT(m[i] == vm_page_lookup(object, pindex++), 302 ("%s: mismatch page %p pindex %ju", __func__, 303 m[i], (uintmax_t )pindex - 1)); 304 /* 305 * Zero out partially filled data. 306 */ 307 if (m[i]->valid != VM_PAGE_BITS_ALL) 308 vm_page_zero_invalid(m[i], 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 *rbehind, int *rahead, 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, rbehind, rahead, 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 * initialize a physical buffer 357 */ 358 359 /* 360 * XXX This probably belongs in vfs_bio.c 361 */ 362 static void 363 initpbuf(struct buf *bp) 364 { 365 KASSERT(bp->b_bufobj == NULL, ("initpbuf with bufobj")); 366 KASSERT(bp->b_vp == NULL, ("initpbuf with vp")); 367 bp->b_rcred = NOCRED; 368 bp->b_wcred = NOCRED; 369 bp->b_qindex = 0; /* On no queue (QUEUE_NONE) */ 370 bp->b_kvabase = (caddr_t) (MAXPHYS * (bp - swbuf)) + swapbkva; 371 bp->b_data = bp->b_kvabase; 372 bp->b_kvasize = MAXPHYS; 373 bp->b_flags = 0; 374 bp->b_xflags = 0; 375 bp->b_ioflags = 0; 376 bp->b_iodone = NULL; 377 bp->b_error = 0; 378 BUF_LOCK(bp, LK_EXCLUSIVE, NULL); 379 buf_track(bp, __func__); 380 } 381 382 /* 383 * allocate a physical buffer 384 * 385 * There are a limited number (nswbuf) of physical buffers. We need 386 * to make sure that no single subsystem is able to hog all of them, 387 * so each subsystem implements a counter which is typically initialized 388 * to 1/2 nswbuf. getpbuf() decrements this counter in allocation and 389 * increments it on release, and blocks if the counter hits zero. A 390 * subsystem may initialize the counter to -1 to disable the feature, 391 * but it must still be sure to match up all uses of getpbuf() with 392 * relpbuf() using the same variable. 393 * 394 * NOTE: pfreecnt can be NULL, but this 'feature' will be removed 395 * relatively soon when the rest of the subsystems get smart about it. XXX 396 */ 397 struct buf * 398 getpbuf(int *pfreecnt) 399 { 400 struct buf *bp; 401 402 mtx_lock(&pbuf_mtx); 403 404 for (;;) { 405 if (pfreecnt) { 406 while (*pfreecnt == 0) { 407 msleep(pfreecnt, &pbuf_mtx, PVM, "wswbuf0", 0); 408 } 409 } 410 411 /* get a bp from the swap buffer header pool */ 412 if ((bp = TAILQ_FIRST(&bswlist)) != NULL) 413 break; 414 415 bswneeded = 1; 416 msleep(&bswneeded, &pbuf_mtx, PVM, "wswbuf1", 0); 417 /* loop in case someone else grabbed one */ 418 } 419 TAILQ_REMOVE(&bswlist, bp, b_freelist); 420 if (pfreecnt) 421 --*pfreecnt; 422 mtx_unlock(&pbuf_mtx); 423 424 initpbuf(bp); 425 return bp; 426 } 427 428 /* 429 * allocate a physical buffer, if one is available. 430 * 431 * Note that there is no NULL hack here - all subsystems using this 432 * call understand how to use pfreecnt. 433 */ 434 struct buf * 435 trypbuf(int *pfreecnt) 436 { 437 struct buf *bp; 438 439 mtx_lock(&pbuf_mtx); 440 if (*pfreecnt == 0 || (bp = TAILQ_FIRST(&bswlist)) == NULL) { 441 mtx_unlock(&pbuf_mtx); 442 return NULL; 443 } 444 TAILQ_REMOVE(&bswlist, bp, b_freelist); 445 446 --*pfreecnt; 447 448 mtx_unlock(&pbuf_mtx); 449 450 initpbuf(bp); 451 452 return bp; 453 } 454 455 /* 456 * release a physical buffer 457 * 458 * NOTE: pfreecnt can be NULL, but this 'feature' will be removed 459 * relatively soon when the rest of the subsystems get smart about it. XXX 460 */ 461 void 462 relpbuf(struct buf *bp, int *pfreecnt) 463 { 464 465 if (bp->b_rcred != NOCRED) { 466 crfree(bp->b_rcred); 467 bp->b_rcred = NOCRED; 468 } 469 if (bp->b_wcred != NOCRED) { 470 crfree(bp->b_wcred); 471 bp->b_wcred = NOCRED; 472 } 473 474 KASSERT(bp->b_vp == NULL, ("relpbuf with vp")); 475 KASSERT(bp->b_bufobj == NULL, ("relpbuf with bufobj")); 476 477 buf_track(bp, __func__); 478 BUF_UNLOCK(bp); 479 480 mtx_lock(&pbuf_mtx); 481 TAILQ_INSERT_HEAD(&bswlist, bp, b_freelist); 482 483 if (bswneeded) { 484 bswneeded = 0; 485 wakeup(&bswneeded); 486 } 487 if (pfreecnt) { 488 if (++*pfreecnt == 1) 489 wakeup(pfreecnt); 490 } 491 mtx_unlock(&pbuf_mtx); 492 } 493 494 /* 495 * Associate a p-buffer with a vnode. 496 * 497 * Also sets B_PAGING flag to indicate that vnode is not fully associated 498 * with the buffer. i.e. the bp has not been linked into the vnode or 499 * ref-counted. 500 */ 501 void 502 pbgetvp(struct vnode *vp, struct buf *bp) 503 { 504 505 KASSERT(bp->b_vp == NULL, ("pbgetvp: not free")); 506 KASSERT(bp->b_bufobj == NULL, ("pbgetvp: not free (bufobj)")); 507 508 bp->b_vp = vp; 509 bp->b_flags |= B_PAGING; 510 bp->b_bufobj = &vp->v_bufobj; 511 } 512 513 /* 514 * Associate a p-buffer with a vnode. 515 * 516 * Also sets B_PAGING flag to indicate that vnode is not fully associated 517 * with the buffer. i.e. the bp has not been linked into the vnode or 518 * ref-counted. 519 */ 520 void 521 pbgetbo(struct bufobj *bo, struct buf *bp) 522 { 523 524 KASSERT(bp->b_vp == NULL, ("pbgetbo: not free (vnode)")); 525 KASSERT(bp->b_bufobj == NULL, ("pbgetbo: not free (bufobj)")); 526 527 bp->b_flags |= B_PAGING; 528 bp->b_bufobj = bo; 529 } 530 531 /* 532 * Disassociate a p-buffer from a vnode. 533 */ 534 void 535 pbrelvp(struct buf *bp) 536 { 537 538 KASSERT(bp->b_vp != NULL, ("pbrelvp: NULL")); 539 KASSERT(bp->b_bufobj != NULL, ("pbrelvp: NULL bufobj")); 540 KASSERT((bp->b_xflags & (BX_VNDIRTY | BX_VNCLEAN)) == 0, 541 ("pbrelvp: pager buf on vnode list.")); 542 543 bp->b_vp = NULL; 544 bp->b_bufobj = NULL; 545 bp->b_flags &= ~B_PAGING; 546 } 547 548 /* 549 * Disassociate a p-buffer from a bufobj. 550 */ 551 void 552 pbrelbo(struct buf *bp) 553 { 554 555 KASSERT(bp->b_vp == NULL, ("pbrelbo: vnode")); 556 KASSERT(bp->b_bufobj != NULL, ("pbrelbo: NULL bufobj")); 557 KASSERT((bp->b_xflags & (BX_VNDIRTY | BX_VNCLEAN)) == 0, 558 ("pbrelbo: pager buf on vnode list.")); 559 560 bp->b_bufobj = NULL; 561 bp->b_flags &= ~B_PAGING; 562 } 563