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 }; 164 165 static const int npagers = sizeof(pagertab) / sizeof(pagertab[0]); 166 167 /* 168 * Kernel address space for mapping pages. 169 * Used by pagers where KVAs are needed for IO. 170 * 171 * XXX needs to be large enough to support the number of pending async 172 * cleaning requests (NPENDINGIO == 64) * the maximum swap cluster size 173 * (MAXPHYS == 64k) if you want to get the most efficiency. 174 */ 175 vm_map_t pager_map; 176 static int bswneeded; 177 static vm_offset_t swapbkva; /* swap buffers kva */ 178 struct mtx pbuf_mtx; 179 static TAILQ_HEAD(swqueue, buf) bswlist; 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[npagers]; 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; 216 217 swapbkva = kmem_alloc_nofault(pager_map, nswbuf * MAXPHYS); 218 if (!swapbkva) 219 panic("Not enough pager_map VM space for physical buffers"); 220 } 221 222 /* 223 * Allocate an instance of a pager of the given type. 224 * Size, protection and offset parameters are passed in for pagers that 225 * need to perform page-level validation (e.g. the device pager). 226 */ 227 vm_object_t 228 vm_pager_allocate(objtype_t type, void *handle, vm_ooffset_t size, 229 vm_prot_t prot, vm_ooffset_t off, struct ucred *cred) 230 { 231 vm_object_t ret; 232 struct pagerops *ops; 233 234 ops = pagertab[type]; 235 if (ops) 236 ret = (*ops->pgo_alloc) (handle, size, prot, off, cred); 237 else 238 ret = NULL; 239 return (ret); 240 } 241 242 /* 243 * The object must be locked. 244 */ 245 void 246 vm_pager_deallocate(object) 247 vm_object_t object; 248 { 249 250 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 251 (*pagertab[object->type]->pgo_dealloc) (object); 252 } 253 254 /* 255 * vm_pager_get_pages() - inline, see vm/vm_pager.h 256 * vm_pager_put_pages() - inline, see vm/vm_pager.h 257 * vm_pager_has_page() - inline, see vm/vm_pager.h 258 */ 259 260 /* 261 * Search the specified pager object list for an object with the 262 * specified handle. If an object with the specified handle is found, 263 * increase its reference count and return it. Otherwise, return NULL. 264 * 265 * The pager object list must be locked. 266 */ 267 vm_object_t 268 vm_pager_object_lookup(struct pagerlst *pg_list, void *handle) 269 { 270 vm_object_t object; 271 272 TAILQ_FOREACH(object, pg_list, pager_object_list) { 273 VM_OBJECT_LOCK(object); 274 if (object->handle == handle && 275 (object->flags & OBJ_DEAD) == 0) { 276 vm_object_reference_locked(object); 277 VM_OBJECT_UNLOCK(object); 278 break; 279 } 280 VM_OBJECT_UNLOCK(object); 281 } 282 return (object); 283 } 284 285 /* 286 * initialize a physical buffer 287 */ 288 289 /* 290 * XXX This probably belongs in vfs_bio.c 291 */ 292 static void 293 initpbuf(struct buf *bp) 294 { 295 KASSERT(bp->b_bufobj == NULL, ("initpbuf with bufobj")); 296 KASSERT(bp->b_vp == NULL, ("initpbuf with vp")); 297 bp->b_rcred = NOCRED; 298 bp->b_wcred = NOCRED; 299 bp->b_qindex = 0; /* On no queue (QUEUE_NONE) */ 300 bp->b_saveaddr = (caddr_t) (MAXPHYS * (bp - swbuf)) + swapbkva; 301 bp->b_data = bp->b_saveaddr; 302 bp->b_kvabase = bp->b_saveaddr; 303 bp->b_kvasize = MAXPHYS; 304 bp->b_xflags = 0; 305 bp->b_flags = 0; 306 bp->b_ioflags = 0; 307 bp->b_iodone = NULL; 308 bp->b_error = 0; 309 BUF_LOCK(bp, LK_EXCLUSIVE, NULL); 310 } 311 312 /* 313 * allocate a physical buffer 314 * 315 * There are a limited number (nswbuf) of physical buffers. We need 316 * to make sure that no single subsystem is able to hog all of them, 317 * so each subsystem implements a counter which is typically initialized 318 * to 1/2 nswbuf. getpbuf() decrements this counter in allocation and 319 * increments it on release, and blocks if the counter hits zero. A 320 * subsystem may initialize the counter to -1 to disable the feature, 321 * but it must still be sure to match up all uses of getpbuf() with 322 * relpbuf() using the same variable. 323 * 324 * NOTE: pfreecnt can be NULL, but this 'feature' will be removed 325 * relatively soon when the rest of the subsystems get smart about it. XXX 326 */ 327 struct buf * 328 getpbuf(int *pfreecnt) 329 { 330 struct buf *bp; 331 332 mtx_lock(&pbuf_mtx); 333 334 for (;;) { 335 if (pfreecnt) { 336 while (*pfreecnt == 0) { 337 msleep(pfreecnt, &pbuf_mtx, PVM, "wswbuf0", 0); 338 } 339 } 340 341 /* get a bp from the swap buffer header pool */ 342 if ((bp = TAILQ_FIRST(&bswlist)) != NULL) 343 break; 344 345 bswneeded = 1; 346 msleep(&bswneeded, &pbuf_mtx, PVM, "wswbuf1", 0); 347 /* loop in case someone else grabbed one */ 348 } 349 TAILQ_REMOVE(&bswlist, bp, b_freelist); 350 if (pfreecnt) 351 --*pfreecnt; 352 mtx_unlock(&pbuf_mtx); 353 354 initpbuf(bp); 355 return bp; 356 } 357 358 /* 359 * allocate a physical buffer, if one is available. 360 * 361 * Note that there is no NULL hack here - all subsystems using this 362 * call understand how to use pfreecnt. 363 */ 364 struct buf * 365 trypbuf(int *pfreecnt) 366 { 367 struct buf *bp; 368 369 mtx_lock(&pbuf_mtx); 370 if (*pfreecnt == 0 || (bp = TAILQ_FIRST(&bswlist)) == NULL) { 371 mtx_unlock(&pbuf_mtx); 372 return NULL; 373 } 374 TAILQ_REMOVE(&bswlist, bp, b_freelist); 375 376 --*pfreecnt; 377 378 mtx_unlock(&pbuf_mtx); 379 380 initpbuf(bp); 381 382 return bp; 383 } 384 385 /* 386 * release a physical buffer 387 * 388 * NOTE: pfreecnt can be NULL, but this 'feature' will be removed 389 * relatively soon when the rest of the subsystems get smart about it. XXX 390 */ 391 void 392 relpbuf(struct buf *bp, int *pfreecnt) 393 { 394 395 if (bp->b_rcred != NOCRED) { 396 crfree(bp->b_rcred); 397 bp->b_rcred = NOCRED; 398 } 399 if (bp->b_wcred != NOCRED) { 400 crfree(bp->b_wcred); 401 bp->b_wcred = NOCRED; 402 } 403 404 KASSERT(bp->b_vp == NULL, ("relpbuf with vp")); 405 KASSERT(bp->b_bufobj == NULL, ("relpbuf with bufobj")); 406 407 BUF_UNLOCK(bp); 408 409 mtx_lock(&pbuf_mtx); 410 TAILQ_INSERT_HEAD(&bswlist, bp, b_freelist); 411 412 if (bswneeded) { 413 bswneeded = 0; 414 wakeup(&bswneeded); 415 } 416 if (pfreecnt) { 417 if (++*pfreecnt == 1) 418 wakeup(pfreecnt); 419 } 420 mtx_unlock(&pbuf_mtx); 421 } 422 423 /* 424 * Associate a p-buffer with a vnode. 425 * 426 * Also sets B_PAGING flag to indicate that vnode is not fully associated 427 * with the buffer. i.e. the bp has not been linked into the vnode or 428 * ref-counted. 429 */ 430 void 431 pbgetvp(struct vnode *vp, struct buf *bp) 432 { 433 434 KASSERT(bp->b_vp == NULL, ("pbgetvp: not free")); 435 KASSERT(bp->b_bufobj == NULL, ("pbgetvp: not free (bufobj)")); 436 437 bp->b_vp = vp; 438 bp->b_flags |= B_PAGING; 439 bp->b_bufobj = &vp->v_bufobj; 440 } 441 442 /* 443 * Associate a p-buffer with a vnode. 444 * 445 * Also sets B_PAGING flag to indicate that vnode is not fully associated 446 * with the buffer. i.e. the bp has not been linked into the vnode or 447 * ref-counted. 448 */ 449 void 450 pbgetbo(struct bufobj *bo, struct buf *bp) 451 { 452 453 KASSERT(bp->b_vp == NULL, ("pbgetbo: not free (vnode)")); 454 KASSERT(bp->b_bufobj == NULL, ("pbgetbo: not free (bufobj)")); 455 456 bp->b_flags |= B_PAGING; 457 bp->b_bufobj = bo; 458 } 459 460 /* 461 * Disassociate a p-buffer from a vnode. 462 */ 463 void 464 pbrelvp(struct buf *bp) 465 { 466 467 KASSERT(bp->b_vp != NULL, ("pbrelvp: NULL")); 468 KASSERT(bp->b_bufobj != NULL, ("pbrelvp: NULL bufobj")); 469 470 /* XXX REMOVE ME */ 471 BO_LOCK(bp->b_bufobj); 472 if (TAILQ_NEXT(bp, b_bobufs) != NULL) { 473 panic( 474 "relpbuf(): b_vp was probably reassignbuf()d %p %x", 475 bp, 476 (int)bp->b_flags 477 ); 478 } 479 BO_UNLOCK(bp->b_bufobj); 480 bp->b_vp = NULL; 481 bp->b_bufobj = NULL; 482 bp->b_flags &= ~B_PAGING; 483 } 484 485 /* 486 * Disassociate a p-buffer from a bufobj. 487 */ 488 void 489 pbrelbo(struct buf *bp) 490 { 491 492 KASSERT(bp->b_vp == NULL, ("pbrelbo: vnode")); 493 KASSERT(bp->b_bufobj != NULL, ("pbrelbo: NULL bufobj")); 494 495 /* XXX REMOVE ME */ 496 BO_LOCK(bp->b_bufobj); 497 if (TAILQ_NEXT(bp, b_bobufs) != NULL) { 498 panic( 499 "relpbuf(): b_vp was probably reassignbuf()d %p %x", 500 bp, 501 (int)bp->b_flags 502 ); 503 } 504 BO_UNLOCK(bp->b_bufobj); 505 bp->b_bufobj = NULL; 506 bp->b_flags &= ~B_PAGING; 507 } 508