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