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 /* 254 * vm_pager_get_pages() - inline, see vm/vm_pager.h 255 * vm_pager_put_pages() - inline, see vm/vm_pager.h 256 * vm_pager_has_page() - inline, see vm/vm_pager.h 257 */ 258 259 /* 260 * Search the specified pager object list for an object with the 261 * specified handle. If an object with the specified handle is found, 262 * increase its reference count and return it. Otherwise, return NULL. 263 * 264 * The pager object list must be locked. 265 */ 266 vm_object_t 267 vm_pager_object_lookup(struct pagerlst *pg_list, void *handle) 268 { 269 vm_object_t object; 270 271 TAILQ_FOREACH(object, pg_list, pager_object_list) { 272 if (object->handle == handle) { 273 VM_OBJECT_WLOCK(object); 274 if ((object->flags & OBJ_DEAD) == 0) { 275 vm_object_reference_locked(object); 276 VM_OBJECT_WUNLOCK(object); 277 break; 278 } 279 VM_OBJECT_WUNLOCK(object); 280 } 281 } 282 return (object); 283 } 284 285 /* 286 * Free the non-requested pages from the given array. 287 */ 288 void 289 vm_pager_free_nonreq(vm_object_t object, vm_page_t ma[], int reqpage, 290 int npages) 291 { 292 int i; 293 boolean_t object_locked; 294 295 VM_OBJECT_ASSERT_UNLOCKED(object); 296 object_locked = FALSE; 297 for (i = 0; i < npages; ++i) { 298 if (i != reqpage) { 299 if (!object_locked) { 300 VM_OBJECT_WLOCK(object); 301 object_locked = TRUE; 302 } 303 vm_page_lock(ma[i]); 304 vm_page_free(ma[i]); 305 vm_page_unlock(ma[i]); 306 } 307 } 308 if (object_locked) 309 VM_OBJECT_WUNLOCK(object); 310 } 311 312 /* 313 * initialize a physical buffer 314 */ 315 316 /* 317 * XXX This probably belongs in vfs_bio.c 318 */ 319 static void 320 initpbuf(struct buf *bp) 321 { 322 KASSERT(bp->b_bufobj == NULL, ("initpbuf with bufobj")); 323 KASSERT(bp->b_vp == NULL, ("initpbuf with vp")); 324 bp->b_rcred = NOCRED; 325 bp->b_wcred = NOCRED; 326 bp->b_qindex = 0; /* On no queue (QUEUE_NONE) */ 327 bp->b_saveaddr = (caddr_t) (MAXPHYS * (bp - swbuf)) + swapbkva; 328 bp->b_data = bp->b_saveaddr; 329 bp->b_kvabase = bp->b_saveaddr; 330 bp->b_kvasize = MAXPHYS; 331 bp->b_xflags = 0; 332 bp->b_flags = 0; 333 bp->b_ioflags = 0; 334 bp->b_iodone = NULL; 335 bp->b_error = 0; 336 BUF_LOCK(bp, LK_EXCLUSIVE, NULL); 337 } 338 339 /* 340 * allocate a physical buffer 341 * 342 * There are a limited number (nswbuf) of physical buffers. We need 343 * to make sure that no single subsystem is able to hog all of them, 344 * so each subsystem implements a counter which is typically initialized 345 * to 1/2 nswbuf. getpbuf() decrements this counter in allocation and 346 * increments it on release, and blocks if the counter hits zero. A 347 * subsystem may initialize the counter to -1 to disable the feature, 348 * but it must still be sure to match up all uses of getpbuf() with 349 * relpbuf() using the same variable. 350 * 351 * NOTE: pfreecnt can be NULL, but this 'feature' will be removed 352 * relatively soon when the rest of the subsystems get smart about it. XXX 353 */ 354 struct buf * 355 getpbuf(int *pfreecnt) 356 { 357 struct buf *bp; 358 359 mtx_lock(&pbuf_mtx); 360 361 for (;;) { 362 if (pfreecnt) { 363 while (*pfreecnt == 0) { 364 msleep(pfreecnt, &pbuf_mtx, PVM, "wswbuf0", 0); 365 } 366 } 367 368 /* get a bp from the swap buffer header pool */ 369 if ((bp = TAILQ_FIRST(&bswlist)) != NULL) 370 break; 371 372 bswneeded = 1; 373 msleep(&bswneeded, &pbuf_mtx, PVM, "wswbuf1", 0); 374 /* loop in case someone else grabbed one */ 375 } 376 TAILQ_REMOVE(&bswlist, bp, b_freelist); 377 if (pfreecnt) 378 --*pfreecnt; 379 mtx_unlock(&pbuf_mtx); 380 381 initpbuf(bp); 382 return bp; 383 } 384 385 /* 386 * allocate a physical buffer, if one is available. 387 * 388 * Note that there is no NULL hack here - all subsystems using this 389 * call understand how to use pfreecnt. 390 */ 391 struct buf * 392 trypbuf(int *pfreecnt) 393 { 394 struct buf *bp; 395 396 mtx_lock(&pbuf_mtx); 397 if (*pfreecnt == 0 || (bp = TAILQ_FIRST(&bswlist)) == NULL) { 398 mtx_unlock(&pbuf_mtx); 399 return NULL; 400 } 401 TAILQ_REMOVE(&bswlist, bp, b_freelist); 402 403 --*pfreecnt; 404 405 mtx_unlock(&pbuf_mtx); 406 407 initpbuf(bp); 408 409 return bp; 410 } 411 412 /* 413 * release a physical buffer 414 * 415 * NOTE: pfreecnt can be NULL, but this 'feature' will be removed 416 * relatively soon when the rest of the subsystems get smart about it. XXX 417 */ 418 void 419 relpbuf(struct buf *bp, int *pfreecnt) 420 { 421 422 if (bp->b_rcred != NOCRED) { 423 crfree(bp->b_rcred); 424 bp->b_rcred = NOCRED; 425 } 426 if (bp->b_wcred != NOCRED) { 427 crfree(bp->b_wcred); 428 bp->b_wcred = NOCRED; 429 } 430 431 KASSERT(bp->b_vp == NULL, ("relpbuf with vp")); 432 KASSERT(bp->b_bufobj == NULL, ("relpbuf with bufobj")); 433 434 BUF_UNLOCK(bp); 435 436 mtx_lock(&pbuf_mtx); 437 TAILQ_INSERT_HEAD(&bswlist, bp, b_freelist); 438 439 if (bswneeded) { 440 bswneeded = 0; 441 wakeup(&bswneeded); 442 } 443 if (pfreecnt) { 444 if (++*pfreecnt == 1) 445 wakeup(pfreecnt); 446 } 447 mtx_unlock(&pbuf_mtx); 448 } 449 450 /* 451 * Associate a p-buffer with a vnode. 452 * 453 * Also sets B_PAGING flag to indicate that vnode is not fully associated 454 * with the buffer. i.e. the bp has not been linked into the vnode or 455 * ref-counted. 456 */ 457 void 458 pbgetvp(struct vnode *vp, struct buf *bp) 459 { 460 461 KASSERT(bp->b_vp == NULL, ("pbgetvp: not free")); 462 KASSERT(bp->b_bufobj == NULL, ("pbgetvp: not free (bufobj)")); 463 464 bp->b_vp = vp; 465 bp->b_flags |= B_PAGING; 466 bp->b_bufobj = &vp->v_bufobj; 467 } 468 469 /* 470 * Associate a p-buffer with a vnode. 471 * 472 * Also sets B_PAGING flag to indicate that vnode is not fully associated 473 * with the buffer. i.e. the bp has not been linked into the vnode or 474 * ref-counted. 475 */ 476 void 477 pbgetbo(struct bufobj *bo, struct buf *bp) 478 { 479 480 KASSERT(bp->b_vp == NULL, ("pbgetbo: not free (vnode)")); 481 KASSERT(bp->b_bufobj == NULL, ("pbgetbo: not free (bufobj)")); 482 483 bp->b_flags |= B_PAGING; 484 bp->b_bufobj = bo; 485 } 486 487 /* 488 * Disassociate a p-buffer from a vnode. 489 */ 490 void 491 pbrelvp(struct buf *bp) 492 { 493 494 KASSERT(bp->b_vp != NULL, ("pbrelvp: NULL")); 495 KASSERT(bp->b_bufobj != NULL, ("pbrelvp: NULL bufobj")); 496 KASSERT((bp->b_xflags & (BX_VNDIRTY | BX_VNCLEAN)) == 0, 497 ("pbrelvp: pager buf on vnode list.")); 498 499 bp->b_vp = NULL; 500 bp->b_bufobj = NULL; 501 bp->b_flags &= ~B_PAGING; 502 } 503 504 /* 505 * Disassociate a p-buffer from a bufobj. 506 */ 507 void 508 pbrelbo(struct buf *bp) 509 { 510 511 KASSERT(bp->b_vp == NULL, ("pbrelbo: vnode")); 512 KASSERT(bp->b_bufobj != NULL, ("pbrelbo: NULL bufobj")); 513 KASSERT((bp->b_xflags & (BX_VNDIRTY | BX_VNCLEAN)) == 0, 514 ("pbrelbo: pager buf on vnode list.")); 515 516 bp->b_bufobj = NULL; 517 bp->b_flags &= ~B_PAGING; 518 } 519