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 return NULL;
111 }
112
113 static void
dead_pager_putpages(object,m,count,flags,rtvals)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
dead_pager_haspage(object,pindex,prev,next)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
dead_pager_dealloc(object)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
vm_pager_init()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
vm_pager_bufferinit()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
vm_pager_allocate(objtype_t type,void * handle,vm_ooffset_t size,vm_prot_t prot,vm_ooffset_t off,struct ucred * cred)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
vm_pager_deallocate(object)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 static void
vm_pager_assert_in(vm_object_t object,vm_page_t * m,int count)254 vm_pager_assert_in(vm_object_t object, vm_page_t *m, int count)
255 {
256 #ifdef INVARIANTS
257
258 VM_OBJECT_ASSERT_WLOCKED(object);
259 KASSERT(count > 0, ("%s: 0 count", __func__));
260 /*
261 * All pages must be busied, not mapped, not fully valid,
262 * not dirty and belong to the proper object.
263 */
264 for (int i = 0 ; i < count; i++) {
265 vm_page_assert_xbusied(m[i]);
266 KASSERT(!pmap_page_is_mapped(m[i]),
267 ("%s: page %p is mapped", __func__, m[i]));
268 KASSERT(m[i]->valid != VM_PAGE_BITS_ALL,
269 ("%s: request for a valid page %p", __func__, m[i]));
270 KASSERT(m[i]->dirty == 0,
271 ("%s: page %p is dirty", __func__, m[i]));
272 KASSERT(m[i]->object == object,
273 ("%s: wrong object %p/%p", __func__, object, m[i]->object));
274 }
275 #endif
276 }
277
278 /*
279 * Page in the pages for the object using its associated pager.
280 * The requested page must be fully valid on successful return.
281 */
282 int
vm_pager_get_pages(vm_object_t object,vm_page_t * m,int count,int * rbehind,int * rahead)283 vm_pager_get_pages(vm_object_t object, vm_page_t *m, int count, int *rbehind,
284 int *rahead)
285 {
286 #ifdef INVARIANTS
287 vm_pindex_t pindex = m[0]->pindex;
288 #endif
289 int r;
290
291 vm_pager_assert_in(object, m, count);
292
293 r = (*pagertab[object->type]->pgo_getpages)(object, m, count, rbehind,
294 rahead);
295 if (r != VM_PAGER_OK)
296 return (r);
297
298 for (int i = 0; i < count; i++) {
299 /*
300 * If pager has replaced a page, assert that it had
301 * updated the array.
302 */
303 KASSERT(m[i] == vm_page_lookup(object, pindex++),
304 ("%s: mismatch page %p pindex %ju", __func__,
305 m[i], (uintmax_t )pindex - 1));
306 /*
307 * Zero out partially filled data.
308 */
309 if (m[i]->valid != VM_PAGE_BITS_ALL)
310 vm_page_zero_invalid(m[i], TRUE);
311 }
312 return (VM_PAGER_OK);
313 }
314
315 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)316 vm_pager_get_pages_async(vm_object_t object, vm_page_t *m, int count,
317 int *rbehind, int *rahead, pgo_getpages_iodone_t iodone, void *arg)
318 {
319
320 vm_pager_assert_in(object, m, count);
321
322 return ((*pagertab[object->type]->pgo_getpages_async)(object, m,
323 count, rbehind, rahead, iodone, arg));
324 }
325
326 /*
327 * vm_pager_put_pages() - inline, see vm/vm_pager.h
328 * vm_pager_has_page() - inline, see vm/vm_pager.h
329 */
330
331 /*
332 * Search the specified pager object list for an object with the
333 * specified handle. If an object with the specified handle is found,
334 * increase its reference count and return it. Otherwise, return NULL.
335 *
336 * The pager object list must be locked.
337 */
338 vm_object_t
vm_pager_object_lookup(struct pagerlst * pg_list,void * handle)339 vm_pager_object_lookup(struct pagerlst *pg_list, void *handle)
340 {
341 vm_object_t object;
342
343 TAILQ_FOREACH(object, pg_list, pager_object_list) {
344 if (object->handle == handle) {
345 VM_OBJECT_WLOCK(object);
346 if ((object->flags & OBJ_DEAD) == 0) {
347 vm_object_reference_locked(object);
348 VM_OBJECT_WUNLOCK(object);
349 break;
350 }
351 VM_OBJECT_WUNLOCK(object);
352 }
353 }
354 return (object);
355 }
356
357 /*
358 * initialize a physical buffer
359 */
360
361 /*
362 * XXX This probably belongs in vfs_bio.c
363 */
364 static void
initpbuf(struct buf * bp)365 initpbuf(struct buf *bp)
366 {
367 KASSERT(bp->b_bufobj == NULL, ("initpbuf with bufobj"));
368 KASSERT(bp->b_vp == NULL, ("initpbuf with vp"));
369 bp->b_rcred = NOCRED;
370 bp->b_wcred = NOCRED;
371 bp->b_qindex = 0; /* On no queue (QUEUE_NONE) */
372 bp->b_kvabase = (caddr_t) (MAXPHYS * (bp - swbuf)) + swapbkva;
373 bp->b_data = bp->b_kvabase;
374 bp->b_kvasize = MAXPHYS;
375 bp->b_flags = 0;
376 bp->b_xflags = 0;
377 bp->b_ioflags = 0;
378 bp->b_iodone = NULL;
379 bp->b_error = 0;
380 BUF_LOCK(bp, LK_EXCLUSIVE, NULL);
381 }
382
383 /*
384 * allocate a physical buffer
385 *
386 * There are a limited number (nswbuf) of physical buffers. We need
387 * to make sure that no single subsystem is able to hog all of them,
388 * so each subsystem implements a counter which is typically initialized
389 * to 1/2 nswbuf. getpbuf() decrements this counter in allocation and
390 * increments it on release, and blocks if the counter hits zero. A
391 * subsystem may initialize the counter to -1 to disable the feature,
392 * but it must still be sure to match up all uses of getpbuf() with
393 * relpbuf() using the same variable.
394 *
395 * NOTE: pfreecnt can be NULL, but this 'feature' will be removed
396 * relatively soon when the rest of the subsystems get smart about it. XXX
397 */
398 struct buf *
getpbuf(int * pfreecnt)399 getpbuf(int *pfreecnt)
400 {
401 struct buf *bp;
402
403 mtx_lock(&pbuf_mtx);
404
405 for (;;) {
406 if (pfreecnt) {
407 while (*pfreecnt == 0) {
408 msleep(pfreecnt, &pbuf_mtx, PVM, "wswbuf0", 0);
409 }
410 }
411
412 /* get a bp from the swap buffer header pool */
413 if ((bp = TAILQ_FIRST(&bswlist)) != NULL)
414 break;
415
416 bswneeded = 1;
417 msleep(&bswneeded, &pbuf_mtx, PVM, "wswbuf1", 0);
418 /* loop in case someone else grabbed one */
419 }
420 TAILQ_REMOVE(&bswlist, bp, b_freelist);
421 if (pfreecnt)
422 --*pfreecnt;
423 mtx_unlock(&pbuf_mtx);
424
425 initpbuf(bp);
426 return bp;
427 }
428
429 /*
430 * allocate a physical buffer, if one is available.
431 *
432 * Note that there is no NULL hack here - all subsystems using this
433 * call understand how to use pfreecnt.
434 */
435 struct buf *
trypbuf(int * pfreecnt)436 trypbuf(int *pfreecnt)
437 {
438 struct buf *bp;
439
440 mtx_lock(&pbuf_mtx);
441 if (*pfreecnt == 0 || (bp = TAILQ_FIRST(&bswlist)) == NULL) {
442 mtx_unlock(&pbuf_mtx);
443 return NULL;
444 }
445 TAILQ_REMOVE(&bswlist, bp, b_freelist);
446
447 --*pfreecnt;
448
449 mtx_unlock(&pbuf_mtx);
450
451 initpbuf(bp);
452
453 return bp;
454 }
455
456 /*
457 * release a physical buffer
458 *
459 * NOTE: pfreecnt can be NULL, but this 'feature' will be removed
460 * relatively soon when the rest of the subsystems get smart about it. XXX
461 */
462 void
relpbuf(struct buf * bp,int * pfreecnt)463 relpbuf(struct buf *bp, int *pfreecnt)
464 {
465
466 if (bp->b_rcred != NOCRED) {
467 crfree(bp->b_rcred);
468 bp->b_rcred = NOCRED;
469 }
470 if (bp->b_wcred != NOCRED) {
471 crfree(bp->b_wcred);
472 bp->b_wcred = NOCRED;
473 }
474
475 KASSERT(bp->b_vp == NULL, ("relpbuf with vp"));
476 KASSERT(bp->b_bufobj == NULL, ("relpbuf with bufobj"));
477
478 BUF_UNLOCK(bp);
479
480 mtx_lock(&pbuf_mtx);
481 TAILQ_INSERT_HEAD(&bswlist, bp, b_freelist);
482
483 if (bswneeded) {
484 bswneeded = 0;
485 wakeup(&bswneeded);
486 }
487 if (pfreecnt) {
488 if (++*pfreecnt == 1)
489 wakeup(pfreecnt);
490 }
491 mtx_unlock(&pbuf_mtx);
492 }
493
494 /*
495 * Associate a p-buffer with a vnode.
496 *
497 * Also sets B_PAGING flag to indicate that vnode is not fully associated
498 * with the buffer. i.e. the bp has not been linked into the vnode or
499 * ref-counted.
500 */
501 void
pbgetvp(struct vnode * vp,struct buf * bp)502 pbgetvp(struct vnode *vp, struct buf *bp)
503 {
504
505 KASSERT(bp->b_vp == NULL, ("pbgetvp: not free"));
506 KASSERT(bp->b_bufobj == NULL, ("pbgetvp: not free (bufobj)"));
507
508 bp->b_vp = vp;
509 bp->b_flags |= B_PAGING;
510 bp->b_bufobj = &vp->v_bufobj;
511 }
512
513 /*
514 * Associate a p-buffer with a vnode.
515 *
516 * Also sets B_PAGING flag to indicate that vnode is not fully associated
517 * with the buffer. i.e. the bp has not been linked into the vnode or
518 * ref-counted.
519 */
520 void
pbgetbo(struct bufobj * bo,struct buf * bp)521 pbgetbo(struct bufobj *bo, struct buf *bp)
522 {
523
524 KASSERT(bp->b_vp == NULL, ("pbgetbo: not free (vnode)"));
525 KASSERT(bp->b_bufobj == NULL, ("pbgetbo: not free (bufobj)"));
526
527 bp->b_flags |= B_PAGING;
528 bp->b_bufobj = bo;
529 }
530
531 /*
532 * Disassociate a p-buffer from a vnode.
533 */
534 void
pbrelvp(struct buf * bp)535 pbrelvp(struct buf *bp)
536 {
537
538 KASSERT(bp->b_vp != NULL, ("pbrelvp: NULL"));
539 KASSERT(bp->b_bufobj != NULL, ("pbrelvp: NULL bufobj"));
540 KASSERT((bp->b_xflags & (BX_VNDIRTY | BX_VNCLEAN)) == 0,
541 ("pbrelvp: pager buf on vnode list."));
542
543 bp->b_vp = NULL;
544 bp->b_bufobj = NULL;
545 bp->b_flags &= ~B_PAGING;
546 }
547
548 /*
549 * Disassociate a p-buffer from a bufobj.
550 */
551 void
pbrelbo(struct buf * bp)552 pbrelbo(struct buf *bp)
553 {
554
555 KASSERT(bp->b_vp == NULL, ("pbrelbo: vnode"));
556 KASSERT(bp->b_bufobj != NULL, ("pbrelbo: NULL bufobj"));
557 KASSERT((bp->b_xflags & (BX_VNDIRTY | BX_VNCLEAN)) == 0,
558 ("pbrelbo: pager buf on vnode list."));
559
560 bp->b_bufobj = NULL;
561 bp->b_flags &= ~B_PAGING;
562 }
563