xref: /netbsd-src/sys/uvm/uvm_bio.c (revision 8a5e2a50be13e77dd4df5daf258ddceeeeb47ce6)
1 /*	$NetBSD: uvm_bio.c,v 1.41 2005/07/23 12:18:41 yamt Exp $	*/
2 
3 /*
4  * Copyright (c) 1998 Chuck Silvers.
5  * All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer.
12  * 2. Redistributions in binary form must reproduce the above copyright
13  *    notice, this list of conditions and the following disclaimer in the
14  *    documentation and/or other materials provided with the distribution.
15  * 3. The name of the author may not be used to endorse or promote products
16  *    derived from this software without specific prior written permission.
17  *
18  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
19  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
20  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
21  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
22  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
23  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
24  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
25  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
26  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
27  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
28  * SUCH DAMAGE.
29  *
30  */
31 
32 /*
33  * uvm_bio.c: buffered i/o object mapping cache
34  */
35 
36 #include <sys/cdefs.h>
37 __KERNEL_RCSID(0, "$NetBSD: uvm_bio.c,v 1.41 2005/07/23 12:18:41 yamt Exp $");
38 
39 #include "opt_uvmhist.h"
40 
41 #include <sys/param.h>
42 #include <sys/systm.h>
43 #include <sys/malloc.h>
44 #include <sys/kernel.h>
45 
46 #include <uvm/uvm.h>
47 
48 /*
49  * global data structures
50  */
51 
52 /*
53  * local functions
54  */
55 
56 static int	ubc_fault(struct uvm_faultinfo *, vaddr_t, struct vm_page **,
57 			  int, int, vm_fault_t, vm_prot_t, int);
58 static struct ubc_map *ubc_find_mapping(struct uvm_object *, voff_t);
59 
60 /*
61  * local data structues
62  */
63 
64 #define UBC_HASH(uobj, offset) 						\
65 	(((((u_long)(uobj)) >> 8) + (((u_long)(offset)) >> PAGE_SHIFT)) & \
66 				ubc_object.hashmask)
67 
68 #define UBC_QUEUE(offset)						\
69 	(&ubc_object.inactive[(((u_long)(offset)) >> ubc_winshift) &	\
70 			     (UBC_NQUEUES - 1)])
71 
72 #define UBC_UMAP_ADDR(u)						\
73 	(vaddr_t)(ubc_object.kva + (((u) - ubc_object.umap) << ubc_winshift))
74 
75 
76 #define UMAP_PAGES_LOCKED	0x0001
77 #define UMAP_MAPPING_CACHED	0x0002
78 
79 struct ubc_map
80 {
81 	struct uvm_object *	uobj;		/* mapped object */
82 	voff_t			offset;		/* offset into uobj */
83 	voff_t			writeoff;	/* write offset */
84 	vsize_t			writelen;	/* write len */
85 	int			refcount;	/* refcount on mapping */
86 	int			flags;		/* extra state */
87 
88 	LIST_ENTRY(ubc_map)	hash;		/* hash table */
89 	TAILQ_ENTRY(ubc_map)	inactive;	/* inactive queue */
90 };
91 
92 static struct ubc_object
93 {
94 	struct uvm_object uobj;		/* glue for uvm_map() */
95 	char *kva;			/* where ubc_object is mapped */
96 	struct ubc_map *umap;		/* array of ubc_map's */
97 
98 	LIST_HEAD(, ubc_map) *hash;	/* hashtable for cached ubc_map's */
99 	u_long hashmask;		/* mask for hashtable */
100 
101 	TAILQ_HEAD(ubc_inactive_head, ubc_map) *inactive;
102 					/* inactive queues for ubc_map's */
103 
104 } ubc_object;
105 
106 struct uvm_pagerops ubc_pager =
107 {
108 	NULL,		/* init */
109 	NULL,		/* reference */
110 	NULL,		/* detach */
111 	ubc_fault,	/* fault */
112 	/* ... rest are NULL */
113 };
114 
115 int ubc_nwins = UBC_NWINS;
116 int ubc_winshift = UBC_WINSHIFT;
117 int ubc_winsize;
118 #if defined(PMAP_PREFER)
119 int ubc_nqueues;
120 #define UBC_NQUEUES ubc_nqueues
121 #else
122 #define UBC_NQUEUES 1
123 #endif
124 
125 /*
126  * ubc_init
127  *
128  * init pager private data structures.
129  */
130 
131 void
132 ubc_init(void)
133 {
134 	struct ubc_map *umap;
135 	vaddr_t va;
136 	int i;
137 
138 	/*
139 	 * Make sure ubc_winshift is sane.
140 	 */
141 	if (ubc_winshift < PAGE_SHIFT)
142 		ubc_winshift = PAGE_SHIFT;
143 
144 	/*
145 	 * init ubc_object.
146 	 * alloc and init ubc_map's.
147 	 * init inactive queues.
148 	 * alloc and init hashtable.
149 	 * map in ubc_object.
150 	 */
151 
152 	UVM_OBJ_INIT(&ubc_object.uobj, &ubc_pager, UVM_OBJ_KERN);
153 
154 	ubc_object.umap = malloc(ubc_nwins * sizeof(struct ubc_map),
155 				 M_TEMP, M_NOWAIT);
156 	if (ubc_object.umap == NULL)
157 		panic("ubc_init: failed to allocate ubc_map");
158 	memset(ubc_object.umap, 0, ubc_nwins * sizeof(struct ubc_map));
159 
160 	if (ubc_winshift < PAGE_SHIFT) {
161 		ubc_winshift = PAGE_SHIFT;
162 	}
163 	va = (vaddr_t)1L;
164 #ifdef PMAP_PREFER
165 	PMAP_PREFER(0, &va, 0, 0);	/* kernel is never topdown */
166 	ubc_nqueues = va >> ubc_winshift;
167 	if (ubc_nqueues == 0) {
168 		ubc_nqueues = 1;
169 	}
170 #endif
171 	ubc_winsize = 1 << ubc_winshift;
172 	ubc_object.inactive = malloc(UBC_NQUEUES *
173 	    sizeof(struct ubc_inactive_head), M_TEMP, M_NOWAIT);
174 	if (ubc_object.inactive == NULL)
175 		panic("ubc_init: failed to allocate inactive queue heads");
176 	for (i = 0; i < UBC_NQUEUES; i++) {
177 		TAILQ_INIT(&ubc_object.inactive[i]);
178 	}
179 	for (i = 0; i < ubc_nwins; i++) {
180 		umap = &ubc_object.umap[i];
181 		TAILQ_INSERT_TAIL(&ubc_object.inactive[i & (UBC_NQUEUES - 1)],
182 				  umap, inactive);
183 	}
184 
185 	ubc_object.hash = hashinit(ubc_nwins, HASH_LIST, M_TEMP, M_NOWAIT,
186 				   &ubc_object.hashmask);
187 	for (i = 0; i <= ubc_object.hashmask; i++) {
188 		LIST_INIT(&ubc_object.hash[i]);
189 	}
190 
191 	if (uvm_map(kernel_map, (vaddr_t *)&ubc_object.kva,
192 		    ubc_nwins << ubc_winshift, &ubc_object.uobj, 0, (vsize_t)va,
193 		    UVM_MAPFLAG(UVM_PROT_ALL, UVM_PROT_ALL, UVM_INH_NONE,
194 				UVM_ADV_RANDOM, UVM_FLAG_NOMERGE)) != 0) {
195 		panic("ubc_init: failed to map ubc_object");
196 	}
197 	UVMHIST_INIT(ubchist, 300);
198 }
199 
200 /*
201  * ubc_fault: fault routine for ubc mapping
202  */
203 
204 static int
205 ubc_fault(struct uvm_faultinfo *ufi, vaddr_t ign1, struct vm_page **ign2,
206     int ign3, int ign4, vm_fault_t fault_type, vm_prot_t access_type,
207     int flags)
208 {
209 	struct uvm_object *uobj;
210 	struct ubc_map *umap;
211 	vaddr_t va, eva, ubc_offset, slot_offset;
212 	int i, error, npages;
213 	struct vm_page *pgs[ubc_winsize >> PAGE_SHIFT], *pg;
214 	vm_prot_t prot;
215 	UVMHIST_FUNC("ubc_fault");  UVMHIST_CALLED(ubchist);
216 
217 	/*
218 	 * no need to try with PGO_LOCKED...
219 	 * we don't need to have the map locked since we know that
220 	 * no one will mess with it until our reference is released.
221 	 */
222 
223 	if (flags & PGO_LOCKED) {
224 		uvmfault_unlockall(ufi, NULL, &ubc_object.uobj, NULL);
225 		flags &= ~PGO_LOCKED;
226 	}
227 
228 	va = ufi->orig_rvaddr;
229 	ubc_offset = va - (vaddr_t)ubc_object.kva;
230 	umap = &ubc_object.umap[ubc_offset >> ubc_winshift];
231 	KASSERT(umap->refcount != 0);
232 	slot_offset = ubc_offset & (ubc_winsize - 1);
233 
234 	/*
235 	 * some platforms cannot write to individual bytes atomically, so
236 	 * software has to do read/modify/write of larger quantities instead.
237 	 * this means that the access_type for "write" operations
238 	 * can be VM_PROT_READ, which confuses us mightily.
239 	 *
240 	 * deal with this by resetting access_type based on the info
241 	 * that ubc_alloc() stores for us.
242 	 */
243 
244 	access_type = umap->writelen ? VM_PROT_WRITE : VM_PROT_READ;
245 	UVMHIST_LOG(ubchist, "va 0x%lx ubc_offset 0x%lx access_type %d",
246 	    va, ubc_offset, access_type, 0);
247 
248 #ifdef DIAGNOSTIC
249 	if ((access_type & VM_PROT_WRITE) != 0) {
250 		if (slot_offset < trunc_page(umap->writeoff) ||
251 		    umap->writeoff + umap->writelen <= slot_offset) {
252 			panic("ubc_fault: out of range write");
253 		}
254 	}
255 #endif
256 
257 	/* no umap locking needed since we have a ref on the umap */
258 	uobj = umap->uobj;
259 
260 	if ((access_type & VM_PROT_WRITE) == 0) {
261 		npages = (ubc_winsize - slot_offset) >> PAGE_SHIFT;
262 	} else {
263 		npages = (round_page(umap->offset + umap->writeoff +
264 		    umap->writelen) - (umap->offset + slot_offset))
265 		    >> PAGE_SHIFT;
266 		flags |= PGO_PASTEOF;
267 	}
268 
269 again:
270 	memset(pgs, 0, sizeof (pgs));
271 	simple_lock(&uobj->vmobjlock);
272 
273 	UVMHIST_LOG(ubchist, "slot_offset 0x%x writeoff 0x%x writelen 0x%x ",
274 	    slot_offset, umap->writeoff, umap->writelen, 0);
275 	UVMHIST_LOG(ubchist, "getpages uobj %p offset 0x%x npages %d",
276 	    uobj, umap->offset + slot_offset, npages, 0);
277 
278 	error = (*uobj->pgops->pgo_get)(uobj, umap->offset + slot_offset, pgs,
279 	    &npages, 0, access_type, 0, flags | PGO_NOBLOCKALLOC |
280 	    PGO_NOTIMESTAMP);
281 	UVMHIST_LOG(ubchist, "getpages error %d npages %d", error, npages, 0,
282 	    0);
283 
284 	if (error == EAGAIN) {
285 		tsleep(&lbolt, PVM, "ubc_fault", 0);
286 		goto again;
287 	}
288 	if (error) {
289 		return error;
290 	}
291 
292 	va = ufi->orig_rvaddr;
293 	eva = ufi->orig_rvaddr + (npages << PAGE_SHIFT);
294 
295 	UVMHIST_LOG(ubchist, "va 0x%lx eva 0x%lx", va, eva, 0, 0);
296 	simple_lock(&uobj->vmobjlock);
297 	uvm_lock_pageq();
298 	for (i = 0; va < eva; i++, va += PAGE_SIZE) {
299 		boolean_t rdonly;
300 		vm_prot_t mask;
301 
302 		/*
303 		 * for virtually-indexed, virtually-tagged caches we should
304 		 * avoid creating writable mappings when we don't absolutely
305 		 * need them, since the "compatible alias" trick doesn't work
306 		 * on such caches.  otherwise, we can always map the pages
307 		 * writable.
308 		 */
309 
310 #ifdef PMAP_CACHE_VIVT
311 		prot = VM_PROT_READ | access_type;
312 #else
313 		prot = VM_PROT_READ | VM_PROT_WRITE;
314 #endif
315 		UVMHIST_LOG(ubchist, "pgs[%d] = %p", i, pgs[i], 0, 0);
316 		pg = pgs[i];
317 
318 		if (pg == NULL || pg == PGO_DONTCARE) {
319 			continue;
320 		}
321 		if (pg->flags & PG_WANTED) {
322 			wakeup(pg);
323 		}
324 		KASSERT((pg->flags & PG_FAKE) == 0);
325 		if (pg->flags & PG_RELEASED) {
326 			uvm_pagefree(pg);
327 			continue;
328 		}
329 		if (pg->loan_count != 0) {
330 
331 			/*
332 			 * avoid unneeded loan break if possible.
333 			 */
334 
335 			if ((access_type & VM_PROT_WRITE) == 0)
336 				prot &= ~VM_PROT_WRITE;
337 
338 			if (prot & VM_PROT_WRITE) {
339 				uvm_unlock_pageq();
340 				pg = uvm_loanbreak(pg);
341 				uvm_lock_pageq();
342 				if (pg == NULL)
343 					continue; /* will re-fault */
344 			}
345 		}
346 
347 		/*
348 		 * note that a page whose backing store is partially allocated
349 		 * is marked as PG_RDONLY.
350 		 */
351 
352 		rdonly = (access_type & VM_PROT_WRITE) == 0 &&
353 		    (pg->flags & PG_RDONLY) != 0;
354 		KASSERT((pg->flags & PG_RDONLY) == 0 ||
355 		    (access_type & VM_PROT_WRITE) == 0 ||
356 		    pg->offset < umap->writeoff ||
357 		    pg->offset + PAGE_SIZE > umap->writeoff + umap->writelen);
358 		mask = rdonly ? ~VM_PROT_WRITE : VM_PROT_ALL;
359 		pmap_enter(ufi->orig_map->pmap, va, VM_PAGE_TO_PHYS(pg),
360 		    prot & mask, access_type & mask);
361 		uvm_pageactivate(pg);
362 		pg->flags &= ~(PG_BUSY);
363 		UVM_PAGE_OWN(pg, NULL);
364 	}
365 	uvm_unlock_pageq();
366 	simple_unlock(&uobj->vmobjlock);
367 	pmap_update(ufi->orig_map->pmap);
368 	return 0;
369 }
370 
371 /*
372  * local functions
373  */
374 
375 static struct ubc_map *
376 ubc_find_mapping(struct uvm_object *uobj, voff_t offset)
377 {
378 	struct ubc_map *umap;
379 
380 	LIST_FOREACH(umap, &ubc_object.hash[UBC_HASH(uobj, offset)], hash) {
381 		if (umap->uobj == uobj && umap->offset == offset) {
382 			return umap;
383 		}
384 	}
385 	return NULL;
386 }
387 
388 
389 /*
390  * ubc interface functions
391  */
392 
393 /*
394  * ubc_alloc:  allocate a file mapping window
395  */
396 
397 void *
398 ubc_alloc(struct uvm_object *uobj, voff_t offset, vsize_t *lenp, int flags)
399 {
400 	vaddr_t slot_offset, va;
401 	struct ubc_map *umap;
402 	voff_t umap_offset;
403 	int error;
404 	UVMHIST_FUNC("ubc_alloc"); UVMHIST_CALLED(ubchist);
405 
406 	UVMHIST_LOG(ubchist, "uobj %p offset 0x%lx len 0x%lx",
407 	    uobj, offset, *lenp, 0);
408 
409 	KASSERT(*lenp > 0);
410 	umap_offset = (offset & ~((voff_t)ubc_winsize - 1));
411 	slot_offset = (vaddr_t)(offset & ((voff_t)ubc_winsize - 1));
412 	*lenp = MIN(*lenp, ubc_winsize - slot_offset);
413 
414 	/*
415 	 * the object is always locked here, so we don't need to add a ref.
416 	 */
417 
418 again:
419 	simple_lock(&ubc_object.uobj.vmobjlock);
420 	umap = ubc_find_mapping(uobj, umap_offset);
421 	if (umap == NULL) {
422 		umap = TAILQ_FIRST(UBC_QUEUE(offset));
423 		if (umap == NULL) {
424 			simple_unlock(&ubc_object.uobj.vmobjlock);
425 			tsleep(&lbolt, PVM, "ubc_alloc", 0);
426 			goto again;
427 		}
428 
429 		/*
430 		 * remove from old hash (if any), add to new hash.
431 		 */
432 
433 		if (umap->uobj != NULL) {
434 			LIST_REMOVE(umap, hash);
435 		}
436 		umap->uobj = uobj;
437 		umap->offset = umap_offset;
438 		LIST_INSERT_HEAD(&ubc_object.hash[UBC_HASH(uobj, umap_offset)],
439 		    umap, hash);
440 		va = UBC_UMAP_ADDR(umap);
441 		if (umap->flags & UMAP_MAPPING_CACHED) {
442 			umap->flags &= ~UMAP_MAPPING_CACHED;
443 			pmap_remove(pmap_kernel(), va, va + ubc_winsize);
444 			pmap_update(pmap_kernel());
445 		}
446 	} else {
447 		va = UBC_UMAP_ADDR(umap);
448 	}
449 
450 	if (umap->refcount == 0) {
451 		TAILQ_REMOVE(UBC_QUEUE(offset), umap, inactive);
452 	}
453 
454 #ifdef DIAGNOSTIC
455 	if ((flags & UBC_WRITE) && (umap->writeoff || umap->writelen)) {
456 		panic("ubc_alloc: concurrent writes uobj %p", uobj);
457 	}
458 #endif
459 	if (flags & UBC_WRITE) {
460 		umap->writeoff = slot_offset;
461 		umap->writelen = *lenp;
462 	}
463 
464 	umap->refcount++;
465 	simple_unlock(&ubc_object.uobj.vmobjlock);
466 	UVMHIST_LOG(ubchist, "umap %p refs %d va %p flags 0x%x",
467 	    umap, umap->refcount, va, flags);
468 
469 	if (flags & UBC_FAULTBUSY) {
470 		int npages = (*lenp + PAGE_SIZE - 1) >> PAGE_SHIFT;
471 		struct vm_page *pgs[npages];
472 		int gpflags =
473 		    PGO_SYNCIO|PGO_OVERWRITE|PGO_PASTEOF|PGO_NOBLOCKALLOC|
474 		    PGO_NOTIMESTAMP;
475 		int i;
476 		KDASSERT(flags & UBC_WRITE);
477 
478 		if (umap->flags & UMAP_MAPPING_CACHED) {
479 			umap->flags &= ~UMAP_MAPPING_CACHED;
480 			pmap_remove(pmap_kernel(), va, va + ubc_winsize);
481 		}
482 		memset(pgs, 0, sizeof(pgs));
483 		simple_lock(&uobj->vmobjlock);
484 		error = (*uobj->pgops->pgo_get)(uobj, trunc_page(offset), pgs,
485 		    &npages, 0, VM_PROT_READ | VM_PROT_WRITE, 0, gpflags);
486 		UVMHIST_LOG(ubchist, "faultbusy getpages %d", error, 0, 0, 0);
487 		if (error) {
488 			goto out;
489 		}
490 		for (i = 0; i < npages; i++) {
491 			pmap_kenter_pa(va + slot_offset + (i << PAGE_SHIFT),
492 			    VM_PAGE_TO_PHYS(pgs[i]),
493 			    VM_PROT_READ | VM_PROT_WRITE);
494 		}
495 		pmap_update(pmap_kernel());
496 		umap->flags |= UMAP_PAGES_LOCKED;
497 	}
498 
499 out:
500 	return (void *)(va + slot_offset);
501 }
502 
503 /*
504  * ubc_release:  free a file mapping window.
505  */
506 
507 void
508 ubc_release(void *va, int flags)
509 {
510 	struct ubc_map *umap;
511 	struct uvm_object *uobj;
512 	vaddr_t umapva;
513 	boolean_t unmapped;
514 	UVMHIST_FUNC("ubc_release"); UVMHIST_CALLED(ubchist);
515 
516 	UVMHIST_LOG(ubchist, "va %p", va, 0, 0, 0);
517 	umap = &ubc_object.umap[((char *)va - ubc_object.kva) >> ubc_winshift];
518 	umapva = UBC_UMAP_ADDR(umap);
519 	uobj = umap->uobj;
520 	KASSERT(uobj != NULL);
521 
522 	if (umap->flags & UMAP_PAGES_LOCKED) {
523 		int slot_offset = umap->writeoff;
524 		int endoff = umap->writeoff + umap->writelen;
525 		int zerolen = round_page(endoff) - endoff;
526 		int npages = (int)(round_page(umap->writeoff + umap->writelen)
527 				   - trunc_page(umap->writeoff)) >> PAGE_SHIFT;
528 		struct vm_page *pgs[npages];
529 		paddr_t pa;
530 		int i;
531 		boolean_t rv;
532 
533 		if (zerolen) {
534 			memset((char *)umapva + endoff, 0, zerolen);
535 		}
536 		umap->flags &= ~UMAP_PAGES_LOCKED;
537 		uvm_lock_pageq();
538 		for (i = 0; i < npages; i++) {
539 			rv = pmap_extract(pmap_kernel(),
540 			    umapva + slot_offset + (i << PAGE_SHIFT), &pa);
541 			KASSERT(rv);
542 			pgs[i] = PHYS_TO_VM_PAGE(pa);
543 			pgs[i]->flags &= ~(PG_FAKE|PG_CLEAN);
544 			KASSERT(pgs[i]->loan_count == 0);
545 			uvm_pageactivate(pgs[i]);
546 		}
547 		uvm_unlock_pageq();
548 		pmap_kremove(umapva, ubc_winsize);
549 		pmap_update(pmap_kernel());
550 		simple_lock(&uobj->vmobjlock);
551 		uvm_page_unbusy(pgs, npages);
552 		simple_unlock(&uobj->vmobjlock);
553 		unmapped = TRUE;
554 	} else {
555 		unmapped = FALSE;
556 	}
557 
558 	simple_lock(&ubc_object.uobj.vmobjlock);
559 	umap->writeoff = 0;
560 	umap->writelen = 0;
561 	umap->refcount--;
562 	if (umap->refcount == 0) {
563 		if (flags & UBC_UNMAP) {
564 
565 			/*
566 			 * Invalidate any cached mappings if requested.
567 			 * This is typically used to avoid leaving
568 			 * incompatible cache aliases around indefinitely.
569 			 */
570 
571 			pmap_remove(pmap_kernel(), umapva,
572 				    umapva + ubc_winsize);
573 			umap->flags &= ~UMAP_MAPPING_CACHED;
574 			pmap_update(pmap_kernel());
575 			LIST_REMOVE(umap, hash);
576 			umap->uobj = NULL;
577 			TAILQ_INSERT_HEAD(UBC_QUEUE(umap->offset), umap,
578 			    inactive);
579 		} else {
580 			if (!unmapped) {
581 				umap->flags |= UMAP_MAPPING_CACHED;
582 			}
583 			TAILQ_INSERT_TAIL(UBC_QUEUE(umap->offset), umap,
584 			    inactive);
585 		}
586 	}
587 	UVMHIST_LOG(ubchist, "umap %p refs %d", umap, umap->refcount, 0, 0);
588 	simple_unlock(&ubc_object.uobj.vmobjlock);
589 }
590 
591 
592 #if 0 /* notused */
593 /*
594  * removing a range of mappings from the ubc mapping cache.
595  */
596 
597 void
598 ubc_flush(struct uvm_object *uobj, voff_t start, voff_t end)
599 {
600 	struct ubc_map *umap;
601 	vaddr_t va;
602 	UVMHIST_FUNC("ubc_flush");  UVMHIST_CALLED(ubchist);
603 
604 	UVMHIST_LOG(ubchist, "uobj %p start 0x%lx end 0x%lx",
605 		    uobj, start, end, 0);
606 
607 	simple_lock(&ubc_object.uobj.vmobjlock);
608 	for (umap = ubc_object.umap;
609 	     umap < &ubc_object.umap[ubc_nwins];
610 	     umap++) {
611 
612 		if (umap->uobj != uobj || umap->offset < start ||
613 		    (umap->offset >= end && end != 0) ||
614 		    umap->refcount > 0) {
615 			continue;
616 		}
617 
618 		/*
619 		 * remove from hash,
620 		 * move to head of inactive queue.
621 		 */
622 
623 		va = (vaddr_t)(ubc_object.kva +
624 		    ((umap - ubc_object.umap) << ubc_winshift));
625 		pmap_remove(pmap_kernel(), va, va + ubc_winsize);
626 
627 		LIST_REMOVE(umap, hash);
628 		umap->uobj = NULL;
629 		TAILQ_REMOVE(UBC_QUEUE(umap->offset), umap, inactive);
630 		TAILQ_INSERT_HEAD(UBC_QUEUE(umap->offset), umap, inactive);
631 	}
632 	pmap_update(pmap_kernel());
633 	simple_unlock(&ubc_object.uobj.vmobjlock);
634 }
635 #endif /* notused */
636