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 78 #include <vm/vm.h> 79 #include <vm/vm_param.h> 80 #include <vm/vm_object.h> 81 #include <vm/vm_page.h> 82 #include <vm/vm_pager.h> 83 #include <vm/vm_extern.h> 84 85 int cluster_pbuf_freecnt = -1; /* unlimited to begin with */ 86 87 static int dead_pager_getpages(vm_object_t, vm_page_t *, int, int); 88 static vm_object_t dead_pager_alloc(void *, vm_ooffset_t, vm_prot_t, 89 vm_ooffset_t, struct ucred *); 90 static void dead_pager_putpages(vm_object_t, vm_page_t *, int, int, int *); 91 static boolean_t dead_pager_haspage(vm_object_t, vm_pindex_t, int *, int *); 92 static void dead_pager_dealloc(vm_object_t); 93 94 static int 95 dead_pager_getpages(obj, ma, count, req) 96 vm_object_t obj; 97 vm_page_t *ma; 98 int count; 99 int req; 100 { 101 return VM_PAGER_FAIL; 102 } 103 104 static vm_object_t 105 dead_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot, 106 vm_ooffset_t off, struct ucred *cred) 107 { 108 return NULL; 109 } 110 111 static void 112 dead_pager_putpages(object, m, count, flags, rtvals) 113 vm_object_t object; 114 vm_page_t *m; 115 int count; 116 int flags; 117 int *rtvals; 118 { 119 int i; 120 121 for (i = 0; i < count; i++) { 122 rtvals[i] = VM_PAGER_AGAIN; 123 } 124 } 125 126 static int 127 dead_pager_haspage(object, pindex, prev, next) 128 vm_object_t object; 129 vm_pindex_t pindex; 130 int *prev; 131 int *next; 132 { 133 if (prev) 134 *prev = 0; 135 if (next) 136 *next = 0; 137 return FALSE; 138 } 139 140 static void 141 dead_pager_dealloc(object) 142 vm_object_t object; 143 { 144 return; 145 } 146 147 static struct pagerops deadpagerops = { 148 .pgo_alloc = dead_pager_alloc, 149 .pgo_dealloc = dead_pager_dealloc, 150 .pgo_getpages = dead_pager_getpages, 151 .pgo_putpages = dead_pager_putpages, 152 .pgo_haspage = dead_pager_haspage, 153 }; 154 155 struct pagerops *pagertab[] = { 156 &defaultpagerops, /* OBJT_DEFAULT */ 157 &swappagerops, /* OBJT_SWAP */ 158 &vnodepagerops, /* OBJT_VNODE */ 159 &devicepagerops, /* OBJT_DEVICE */ 160 &physpagerops, /* OBJT_PHYS */ 161 &deadpagerops, /* OBJT_DEAD */ 162 &sgpagerops, /* OBJT_SG */ 163 &mgtdevicepagerops, /* OBJT_MGTDEVICE */ 164 }; 165 166 static const int npagers = sizeof(pagertab) / sizeof(pagertab[0]); 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 vm_map_t pager_map; 177 static int bswneeded; 178 static vm_offset_t swapbkva; /* swap buffers kva */ 179 struct mtx pbuf_mtx; 180 static TAILQ_HEAD(swqueue, buf) bswlist; 181 182 void 183 vm_pager_init() 184 { 185 struct pagerops **pgops; 186 187 TAILQ_INIT(&bswlist); 188 /* 189 * Initialize known pagers 190 */ 191 for (pgops = pagertab; pgops < &pagertab[npagers]; pgops++) 192 if ((*pgops)->pgo_init != NULL) 193 (*(*pgops)->pgo_init) (); 194 } 195 196 void 197 vm_pager_bufferinit() 198 { 199 struct buf *bp; 200 int i; 201 202 mtx_init(&pbuf_mtx, "pbuf mutex", NULL, MTX_DEF); 203 bp = swbuf; 204 /* 205 * Now set up swap and physical I/O buffer headers. 206 */ 207 for (i = 0; i < nswbuf; i++, bp++) { 208 TAILQ_INSERT_HEAD(&bswlist, bp, b_freelist); 209 BUF_LOCKINIT(bp); 210 LIST_INIT(&bp->b_dep); 211 bp->b_rcred = bp->b_wcred = NOCRED; 212 bp->b_xflags = 0; 213 } 214 215 cluster_pbuf_freecnt = nswbuf / 2; 216 vnode_pbuf_freecnt = nswbuf / 2 + 1; 217 218 swapbkva = kmem_alloc_nofault(pager_map, nswbuf * MAXPHYS); 219 if (!swapbkva) 220 panic("Not enough pager_map VM space for physical buffers"); 221 } 222 223 /* 224 * Allocate an instance of a pager of the given type. 225 * Size, protection and offset parameters are passed in for pagers that 226 * need to perform page-level validation (e.g. the device pager). 227 */ 228 vm_object_t 229 vm_pager_allocate(objtype_t type, void *handle, vm_ooffset_t size, 230 vm_prot_t prot, vm_ooffset_t off, struct ucred *cred) 231 { 232 vm_object_t ret; 233 struct pagerops *ops; 234 235 ops = pagertab[type]; 236 if (ops) 237 ret = (*ops->pgo_alloc) (handle, size, prot, off, cred); 238 else 239 ret = NULL; 240 return (ret); 241 } 242 243 /* 244 * The object must be locked. 245 */ 246 void 247 vm_pager_deallocate(object) 248 vm_object_t object; 249 { 250 251 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 252 (*pagertab[object->type]->pgo_dealloc) (object); 253 } 254 255 /* 256 * vm_pager_get_pages() - inline, see vm/vm_pager.h 257 * vm_pager_put_pages() - inline, see vm/vm_pager.h 258 * vm_pager_has_page() - inline, see vm/vm_pager.h 259 */ 260 261 /* 262 * Search the specified pager object list for an object with the 263 * specified handle. If an object with the specified handle is found, 264 * increase its reference count and return it. Otherwise, return NULL. 265 * 266 * The pager object list must be locked. 267 */ 268 vm_object_t 269 vm_pager_object_lookup(struct pagerlst *pg_list, void *handle) 270 { 271 vm_object_t object; 272 273 TAILQ_FOREACH(object, pg_list, pager_object_list) { 274 VM_OBJECT_LOCK(object); 275 if (object->handle == handle && 276 (object->flags & OBJ_DEAD) == 0) { 277 vm_object_reference_locked(object); 278 VM_OBJECT_UNLOCK(object); 279 break; 280 } 281 VM_OBJECT_UNLOCK(object); 282 } 283 return (object); 284 } 285 286 /* 287 * initialize a physical buffer 288 */ 289 290 /* 291 * XXX This probably belongs in vfs_bio.c 292 */ 293 static void 294 initpbuf(struct buf *bp) 295 { 296 KASSERT(bp->b_bufobj == NULL, ("initpbuf with bufobj")); 297 KASSERT(bp->b_vp == NULL, ("initpbuf with vp")); 298 bp->b_rcred = NOCRED; 299 bp->b_wcred = NOCRED; 300 bp->b_qindex = 0; /* On no queue (QUEUE_NONE) */ 301 bp->b_saveaddr = (caddr_t) (MAXPHYS * (bp - swbuf)) + swapbkva; 302 bp->b_data = bp->b_saveaddr; 303 bp->b_kvabase = bp->b_saveaddr; 304 bp->b_kvasize = MAXPHYS; 305 bp->b_xflags = 0; 306 bp->b_flags = 0; 307 bp->b_ioflags = 0; 308 bp->b_iodone = NULL; 309 bp->b_error = 0; 310 BUF_LOCK(bp, LK_EXCLUSIVE, NULL); 311 } 312 313 /* 314 * allocate a physical buffer 315 * 316 * There are a limited number (nswbuf) of physical buffers. We need 317 * to make sure that no single subsystem is able to hog all of them, 318 * so each subsystem implements a counter which is typically initialized 319 * to 1/2 nswbuf. getpbuf() decrements this counter in allocation and 320 * increments it on release, and blocks if the counter hits zero. A 321 * subsystem may initialize the counter to -1 to disable the feature, 322 * but it must still be sure to match up all uses of getpbuf() with 323 * relpbuf() using the same variable. 324 * 325 * NOTE: pfreecnt can be NULL, but this 'feature' will be removed 326 * relatively soon when the rest of the subsystems get smart about it. XXX 327 */ 328 struct buf * 329 getpbuf(int *pfreecnt) 330 { 331 struct buf *bp; 332 333 mtx_lock(&pbuf_mtx); 334 335 for (;;) { 336 if (pfreecnt) { 337 while (*pfreecnt == 0) { 338 msleep(pfreecnt, &pbuf_mtx, PVM, "wswbuf0", 0); 339 } 340 } 341 342 /* get a bp from the swap buffer header pool */ 343 if ((bp = TAILQ_FIRST(&bswlist)) != NULL) 344 break; 345 346 bswneeded = 1; 347 msleep(&bswneeded, &pbuf_mtx, PVM, "wswbuf1", 0); 348 /* loop in case someone else grabbed one */ 349 } 350 TAILQ_REMOVE(&bswlist, bp, b_freelist); 351 if (pfreecnt) 352 --*pfreecnt; 353 mtx_unlock(&pbuf_mtx); 354 355 initpbuf(bp); 356 return bp; 357 } 358 359 /* 360 * allocate a physical buffer, if one is available. 361 * 362 * Note that there is no NULL hack here - all subsystems using this 363 * call understand how to use pfreecnt. 364 */ 365 struct buf * 366 trypbuf(int *pfreecnt) 367 { 368 struct buf *bp; 369 370 mtx_lock(&pbuf_mtx); 371 if (*pfreecnt == 0 || (bp = TAILQ_FIRST(&bswlist)) == NULL) { 372 mtx_unlock(&pbuf_mtx); 373 return NULL; 374 } 375 TAILQ_REMOVE(&bswlist, bp, b_freelist); 376 377 --*pfreecnt; 378 379 mtx_unlock(&pbuf_mtx); 380 381 initpbuf(bp); 382 383 return bp; 384 } 385 386 /* 387 * release a physical buffer 388 * 389 * NOTE: pfreecnt can be NULL, but this 'feature' will be removed 390 * relatively soon when the rest of the subsystems get smart about it. XXX 391 */ 392 void 393 relpbuf(struct buf *bp, int *pfreecnt) 394 { 395 396 if (bp->b_rcred != NOCRED) { 397 crfree(bp->b_rcred); 398 bp->b_rcred = NOCRED; 399 } 400 if (bp->b_wcred != NOCRED) { 401 crfree(bp->b_wcred); 402 bp->b_wcred = NOCRED; 403 } 404 405 KASSERT(bp->b_vp == NULL, ("relpbuf with vp")); 406 KASSERT(bp->b_bufobj == NULL, ("relpbuf with bufobj")); 407 408 BUF_UNLOCK(bp); 409 410 mtx_lock(&pbuf_mtx); 411 TAILQ_INSERT_HEAD(&bswlist, bp, b_freelist); 412 413 if (bswneeded) { 414 bswneeded = 0; 415 wakeup(&bswneeded); 416 } 417 if (pfreecnt) { 418 if (++*pfreecnt == 1) 419 wakeup(pfreecnt); 420 } 421 mtx_unlock(&pbuf_mtx); 422 } 423 424 /* 425 * Associate a p-buffer with a vnode. 426 * 427 * Also sets B_PAGING flag to indicate that vnode is not fully associated 428 * with the buffer. i.e. the bp has not been linked into the vnode or 429 * ref-counted. 430 */ 431 void 432 pbgetvp(struct vnode *vp, struct buf *bp) 433 { 434 435 KASSERT(bp->b_vp == NULL, ("pbgetvp: not free")); 436 KASSERT(bp->b_bufobj == NULL, ("pbgetvp: not free (bufobj)")); 437 438 bp->b_vp = vp; 439 bp->b_flags |= B_PAGING; 440 bp->b_bufobj = &vp->v_bufobj; 441 } 442 443 /* 444 * Associate a p-buffer with a vnode. 445 * 446 * Also sets B_PAGING flag to indicate that vnode is not fully associated 447 * with the buffer. i.e. the bp has not been linked into the vnode or 448 * ref-counted. 449 */ 450 void 451 pbgetbo(struct bufobj *bo, struct buf *bp) 452 { 453 454 KASSERT(bp->b_vp == NULL, ("pbgetbo: not free (vnode)")); 455 KASSERT(bp->b_bufobj == NULL, ("pbgetbo: not free (bufobj)")); 456 457 bp->b_flags |= B_PAGING; 458 bp->b_bufobj = bo; 459 } 460 461 /* 462 * Disassociate a p-buffer from a vnode. 463 */ 464 void 465 pbrelvp(struct buf *bp) 466 { 467 468 KASSERT(bp->b_vp != NULL, ("pbrelvp: NULL")); 469 KASSERT(bp->b_bufobj != NULL, ("pbrelvp: NULL bufobj")); 470 471 /* XXX REMOVE ME */ 472 BO_LOCK(bp->b_bufobj); 473 if (TAILQ_NEXT(bp, b_bobufs) != NULL) { 474 panic( 475 "relpbuf(): b_vp was probably reassignbuf()d %p %x", 476 bp, 477 (int)bp->b_flags 478 ); 479 } 480 BO_UNLOCK(bp->b_bufobj); 481 bp->b_vp = NULL; 482 bp->b_bufobj = NULL; 483 bp->b_flags &= ~B_PAGING; 484 } 485 486 /* 487 * Disassociate a p-buffer from a bufobj. 488 */ 489 void 490 pbrelbo(struct buf *bp) 491 { 492 493 KASSERT(bp->b_vp == NULL, ("pbrelbo: vnode")); 494 KASSERT(bp->b_bufobj != NULL, ("pbrelbo: NULL bufobj")); 495 496 /* XXX REMOVE ME */ 497 BO_LOCK(bp->b_bufobj); 498 if (TAILQ_NEXT(bp, b_bobufs) != NULL) { 499 panic( 500 "relpbuf(): b_vp was probably reassignbuf()d %p %x", 501 bp, 502 (int)bp->b_flags 503 ); 504 } 505 BO_UNLOCK(bp->b_bufobj); 506 bp->b_bufobj = NULL; 507 bp->b_flags &= ~B_PAGING; 508 } 509