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
dead_pager_getpages(vm_object_t obj,vm_page_t * ma,int count,int * rbehind,int * rahead)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
dead_pager_alloc(void * handle,vm_ooffset_t size,vm_prot_t prot,vm_ooffset_t off,struct ucred * cred)107 dead_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot,
108 vm_ooffset_t off, struct ucred *cred)
109 {
110
111 return (NULL);
112 }
113
114 static void
dead_pager_putpages(vm_object_t object,vm_page_t * m,int count,int flags,int * rtvals)115 dead_pager_putpages(vm_object_t object, vm_page_t *m, int count,
116 int flags, int *rtvals)
117 {
118 int i;
119
120 for (i = 0; i < count; i++)
121 rtvals[i] = VM_PAGER_AGAIN;
122 }
123
124 static int
dead_pager_haspage(vm_object_t object,vm_pindex_t pindex,int * prev,int * next)125 dead_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *prev, int *next)
126 {
127
128 if (prev != NULL)
129 *prev = 0;
130 if (next != NULL)
131 *next = 0;
132 return (FALSE);
133 }
134
135 static void
dead_pager_dealloc(vm_object_t object)136 dead_pager_dealloc(vm_object_t object)
137 {
138
139 }
140
141 static struct pagerops deadpagerops = {
142 .pgo_alloc = dead_pager_alloc,
143 .pgo_dealloc = dead_pager_dealloc,
144 .pgo_getpages = dead_pager_getpages,
145 .pgo_putpages = dead_pager_putpages,
146 .pgo_haspage = dead_pager_haspage,
147 };
148
149 struct pagerops *pagertab[] = {
150 &defaultpagerops, /* OBJT_DEFAULT */
151 &swappagerops, /* OBJT_SWAP */
152 &vnodepagerops, /* OBJT_VNODE */
153 &devicepagerops, /* OBJT_DEVICE */
154 &physpagerops, /* OBJT_PHYS */
155 &deadpagerops, /* OBJT_DEAD */
156 &sgpagerops, /* OBJT_SG */
157 &mgtdevicepagerops, /* OBJT_MGTDEVICE */
158 };
159
160 /*
161 * Kernel address space for mapping pages.
162 * Used by pagers where KVAs are needed for IO.
163 *
164 * XXX needs to be large enough to support the number of pending async
165 * cleaning requests (NPENDINGIO == 64) * the maximum swap cluster size
166 * (MAXPHYS == 64k) if you want to get the most efficiency.
167 */
168 struct mtx_padalign __exclusive_cache_line pbuf_mtx;
169 static TAILQ_HEAD(swqueue, buf) bswlist;
170 static int bswneeded;
171 vm_offset_t swapbkva; /* swap buffers kva */
172
173 void
vm_pager_init(void)174 vm_pager_init(void)
175 {
176 struct pagerops **pgops;
177
178 TAILQ_INIT(&bswlist);
179 /*
180 * Initialize known pagers
181 */
182 for (pgops = pagertab; pgops < &pagertab[nitems(pagertab)]; pgops++)
183 if ((*pgops)->pgo_init != NULL)
184 (*(*pgops)->pgo_init)();
185 }
186
187 void
vm_pager_bufferinit(void)188 vm_pager_bufferinit(void)
189 {
190 struct buf *bp;
191 int i;
192
193 mtx_init(&pbuf_mtx, "pbuf mutex", NULL, MTX_DEF);
194 bp = swbuf;
195 /*
196 * Now set up swap and physical I/O buffer headers.
197 */
198 for (i = 0; i < nswbuf; i++, bp++) {
199 TAILQ_INSERT_HEAD(&bswlist, bp, b_freelist);
200 BUF_LOCKINIT(bp);
201 LIST_INIT(&bp->b_dep);
202 bp->b_rcred = bp->b_wcred = NOCRED;
203 bp->b_xflags = 0;
204 }
205
206 cluster_pbuf_freecnt = nswbuf / 2;
207 vnode_pbuf_freecnt = nswbuf / 2 + 1;
208 vnode_async_pbuf_freecnt = nswbuf / 2;
209 }
210
211 /*
212 * Allocate an instance of a pager of the given type.
213 * Size, protection and offset parameters are passed in for pagers that
214 * need to perform page-level validation (e.g. the device pager).
215 */
216 vm_object_t
vm_pager_allocate(objtype_t type,void * handle,vm_ooffset_t size,vm_prot_t prot,vm_ooffset_t off,struct ucred * cred)217 vm_pager_allocate(objtype_t type, void *handle, vm_ooffset_t size,
218 vm_prot_t prot, vm_ooffset_t off, struct ucred *cred)
219 {
220 vm_object_t ret;
221 struct pagerops *ops;
222
223 ops = pagertab[type];
224 if (ops)
225 ret = (*ops->pgo_alloc)(handle, size, prot, off, cred);
226 else
227 ret = NULL;
228 return (ret);
229 }
230
231 /*
232 * The object must be locked.
233 */
234 void
vm_pager_deallocate(vm_object_t object)235 vm_pager_deallocate(vm_object_t object)
236 {
237
238 VM_OBJECT_ASSERT_WLOCKED(object);
239 (*pagertab[object->type]->pgo_dealloc) (object);
240 }
241
242 static void
vm_pager_assert_in(vm_object_t object,vm_page_t * m,int count)243 vm_pager_assert_in(vm_object_t object, vm_page_t *m, int count)
244 {
245 #ifdef INVARIANTS
246
247 VM_OBJECT_ASSERT_WLOCKED(object);
248 KASSERT(count > 0, ("%s: 0 count", __func__));
249 /*
250 * All pages must be busied, not mapped, not fully valid,
251 * not dirty and belong to the proper object.
252 */
253 for (int i = 0 ; i < count; i++) {
254 vm_page_assert_xbusied(m[i]);
255 KASSERT(!pmap_page_is_mapped(m[i]),
256 ("%s: page %p is mapped", __func__, m[i]));
257 KASSERT(m[i]->valid != VM_PAGE_BITS_ALL,
258 ("%s: request for a valid page %p", __func__, m[i]));
259 KASSERT(m[i]->dirty == 0,
260 ("%s: page %p is dirty", __func__, m[i]));
261 KASSERT(m[i]->object == object,
262 ("%s: wrong object %p/%p", __func__, object, m[i]->object));
263 }
264 #endif
265 }
266
267 /*
268 * Page in the pages for the object using its associated pager.
269 * The requested page must be fully valid on successful return.
270 */
271 int
vm_pager_get_pages(vm_object_t object,vm_page_t * m,int count,int * rbehind,int * rahead)272 vm_pager_get_pages(vm_object_t object, vm_page_t *m, int count, int *rbehind,
273 int *rahead)
274 {
275 #ifdef INVARIANTS
276 vm_pindex_t pindex = m[0]->pindex;
277 #endif
278 int r;
279
280 vm_pager_assert_in(object, m, count);
281
282 r = (*pagertab[object->type]->pgo_getpages)(object, m, count, rbehind,
283 rahead);
284 if (r != VM_PAGER_OK)
285 return (r);
286
287 for (int i = 0; i < count; i++) {
288 /*
289 * If pager has replaced a page, assert that it had
290 * updated the array.
291 */
292 KASSERT(m[i] == vm_page_lookup(object, pindex++),
293 ("%s: mismatch page %p pindex %ju", __func__,
294 m[i], (uintmax_t )pindex - 1));
295 /*
296 * Zero out partially filled data.
297 */
298 if (m[i]->valid != VM_PAGE_BITS_ALL)
299 vm_page_zero_invalid(m[i], TRUE);
300 }
301 return (VM_PAGER_OK);
302 }
303
304 int
vm_pager_get_pages_async(vm_object_t object,vm_page_t * m,int count,int * rbehind,int * rahead,pgo_getpages_iodone_t iodone,void * arg)305 vm_pager_get_pages_async(vm_object_t object, vm_page_t *m, int count,
306 int *rbehind, int *rahead, pgo_getpages_iodone_t iodone, void *arg)
307 {
308
309 vm_pager_assert_in(object, m, count);
310
311 return ((*pagertab[object->type]->pgo_getpages_async)(object, m,
312 count, rbehind, rahead, iodone, arg));
313 }
314
315 /*
316 * vm_pager_put_pages() - inline, see vm/vm_pager.h
317 * vm_pager_has_page() - inline, see vm/vm_pager.h
318 */
319
320 /*
321 * Search the specified pager object list for an object with the
322 * specified handle. If an object with the specified handle is found,
323 * increase its reference count and return it. Otherwise, return NULL.
324 *
325 * The pager object list must be locked.
326 */
327 vm_object_t
vm_pager_object_lookup(struct pagerlst * pg_list,void * handle)328 vm_pager_object_lookup(struct pagerlst *pg_list, void *handle)
329 {
330 vm_object_t object;
331
332 TAILQ_FOREACH(object, pg_list, pager_object_list) {
333 if (object->handle == handle) {
334 VM_OBJECT_WLOCK(object);
335 if ((object->flags & OBJ_DEAD) == 0) {
336 vm_object_reference_locked(object);
337 VM_OBJECT_WUNLOCK(object);
338 break;
339 }
340 VM_OBJECT_WUNLOCK(object);
341 }
342 }
343 return (object);
344 }
345
346 /*
347 * initialize a physical buffer
348 */
349
350 /*
351 * XXX This probably belongs in vfs_bio.c
352 */
353 static void
initpbuf(struct buf * bp)354 initpbuf(struct buf *bp)
355 {
356
357 KASSERT(bp->b_bufobj == NULL, ("initpbuf with bufobj"));
358 KASSERT(bp->b_vp == NULL, ("initpbuf with vp"));
359 bp->b_rcred = NOCRED;
360 bp->b_wcred = NOCRED;
361 bp->b_qindex = 0; /* On no queue (QUEUE_NONE) */
362 bp->b_kvabase = (caddr_t)(MAXPHYS * (bp - swbuf)) + swapbkva;
363 bp->b_data = bp->b_kvabase;
364 bp->b_kvasize = MAXPHYS;
365 bp->b_flags = 0;
366 bp->b_xflags = 0;
367 bp->b_ioflags = 0;
368 bp->b_iodone = NULL;
369 bp->b_error = 0;
370 BUF_LOCK(bp, LK_EXCLUSIVE, NULL);
371 }
372
373 /*
374 * allocate a physical buffer
375 *
376 * There are a limited number (nswbuf) of physical buffers. We need
377 * to make sure that no single subsystem is able to hog all of them,
378 * so each subsystem implements a counter which is typically initialized
379 * to 1/2 nswbuf. getpbuf() decrements this counter in allocation and
380 * increments it on release, and blocks if the counter hits zero. A
381 * subsystem may initialize the counter to -1 to disable the feature,
382 * but it must still be sure to match up all uses of getpbuf() with
383 * relpbuf() using the same variable.
384 *
385 * NOTE: pfreecnt can be NULL, but this 'feature' will be removed
386 * relatively soon when the rest of the subsystems get smart about it. XXX
387 */
388 struct buf *
getpbuf(int * pfreecnt)389 getpbuf(int *pfreecnt)
390 {
391 struct buf *bp;
392
393 mtx_lock(&pbuf_mtx);
394 for (;;) {
395 if (pfreecnt != NULL) {
396 while (*pfreecnt == 0) {
397 msleep(pfreecnt, &pbuf_mtx, PVM, "wswbuf0", 0);
398 }
399 }
400
401 /* get a bp from the swap buffer header pool */
402 if ((bp = TAILQ_FIRST(&bswlist)) != NULL)
403 break;
404
405 bswneeded = 1;
406 msleep(&bswneeded, &pbuf_mtx, PVM, "wswbuf1", 0);
407 /* loop in case someone else grabbed one */
408 }
409 TAILQ_REMOVE(&bswlist, bp, b_freelist);
410 if (pfreecnt)
411 --*pfreecnt;
412 mtx_unlock(&pbuf_mtx);
413 initpbuf(bp);
414 return (bp);
415 }
416
417 /*
418 * allocate a physical buffer, if one is available.
419 *
420 * Note that there is no NULL hack here - all subsystems using this
421 * call understand how to use pfreecnt.
422 */
423 struct buf *
trypbuf(int * pfreecnt)424 trypbuf(int *pfreecnt)
425 {
426 struct buf *bp;
427
428 mtx_lock(&pbuf_mtx);
429 if (*pfreecnt == 0 || (bp = TAILQ_FIRST(&bswlist)) == NULL) {
430 mtx_unlock(&pbuf_mtx);
431 return NULL;
432 }
433 TAILQ_REMOVE(&bswlist, bp, b_freelist);
434 --*pfreecnt;
435 mtx_unlock(&pbuf_mtx);
436 initpbuf(bp);
437 return (bp);
438 }
439
440 /*
441 * release a physical buffer
442 *
443 * NOTE: pfreecnt can be NULL, but this 'feature' will be removed
444 * relatively soon when the rest of the subsystems get smart about it. XXX
445 */
446 void
relpbuf(struct buf * bp,int * pfreecnt)447 relpbuf(struct buf *bp, int *pfreecnt)
448 {
449
450 if (bp->b_rcred != NOCRED) {
451 crfree(bp->b_rcred);
452 bp->b_rcred = NOCRED;
453 }
454 if (bp->b_wcred != NOCRED) {
455 crfree(bp->b_wcred);
456 bp->b_wcred = NOCRED;
457 }
458
459 KASSERT(bp->b_vp == NULL, ("relpbuf with vp"));
460 KASSERT(bp->b_bufobj == NULL, ("relpbuf with bufobj"));
461
462 BUF_UNLOCK(bp);
463
464 mtx_lock(&pbuf_mtx);
465 TAILQ_INSERT_HEAD(&bswlist, bp, b_freelist);
466
467 if (bswneeded) {
468 bswneeded = 0;
469 wakeup(&bswneeded);
470 }
471 if (pfreecnt) {
472 if (++*pfreecnt == 1)
473 wakeup(pfreecnt);
474 }
475 mtx_unlock(&pbuf_mtx);
476 }
477
478 /*
479 * Associate a p-buffer with a vnode.
480 *
481 * Also sets B_PAGING flag to indicate that vnode is not fully associated
482 * with the buffer. i.e. the bp has not been linked into the vnode or
483 * ref-counted.
484 */
485 void
pbgetvp(struct vnode * vp,struct buf * bp)486 pbgetvp(struct vnode *vp, struct buf *bp)
487 {
488
489 KASSERT(bp->b_vp == NULL, ("pbgetvp: not free"));
490 KASSERT(bp->b_bufobj == NULL, ("pbgetvp: not free (bufobj)"));
491
492 bp->b_vp = vp;
493 bp->b_flags |= B_PAGING;
494 bp->b_bufobj = &vp->v_bufobj;
495 }
496
497 /*
498 * Associate a p-buffer with a vnode.
499 *
500 * Also sets B_PAGING flag to indicate that vnode is not fully associated
501 * with the buffer. i.e. the bp has not been linked into the vnode or
502 * ref-counted.
503 */
504 void
pbgetbo(struct bufobj * bo,struct buf * bp)505 pbgetbo(struct bufobj *bo, struct buf *bp)
506 {
507
508 KASSERT(bp->b_vp == NULL, ("pbgetbo: not free (vnode)"));
509 KASSERT(bp->b_bufobj == NULL, ("pbgetbo: not free (bufobj)"));
510
511 bp->b_flags |= B_PAGING;
512 bp->b_bufobj = bo;
513 }
514
515 /*
516 * Disassociate a p-buffer from a vnode.
517 */
518 void
pbrelvp(struct buf * bp)519 pbrelvp(struct buf *bp)
520 {
521
522 KASSERT(bp->b_vp != NULL, ("pbrelvp: NULL"));
523 KASSERT(bp->b_bufobj != NULL, ("pbrelvp: NULL bufobj"));
524 KASSERT((bp->b_xflags & (BX_VNDIRTY | BX_VNCLEAN)) == 0,
525 ("pbrelvp: pager buf on vnode list."));
526
527 bp->b_vp = NULL;
528 bp->b_bufobj = NULL;
529 bp->b_flags &= ~B_PAGING;
530 }
531
532 /*
533 * Disassociate a p-buffer from a bufobj.
534 */
535 void
pbrelbo(struct buf * bp)536 pbrelbo(struct buf *bp)
537 {
538
539 KASSERT(bp->b_vp == NULL, ("pbrelbo: vnode"));
540 KASSERT(bp->b_bufobj != NULL, ("pbrelbo: NULL bufobj"));
541 KASSERT((bp->b_xflags & (BX_VNDIRTY | BX_VNCLEAN)) == 0,
542 ("pbrelbo: pager buf on vnode list."));
543
544 bp->b_bufobj = NULL;
545 bp->b_flags &= ~B_PAGING;
546 }
547