4 * Copyright (c) 1990 University of Utah.
5 * Copyright (c) 1991 The Regents of the University of California.
7 * Copyright (c) 1993, 1994 John S. Dyson
8 * Copyright (c) 1995, David Greenman
10 * This code is derived from software contributed to Berkeley by
11 * the Systems Programming Group of the University of Utah Computer
14 * Redistribution and use in source and binary forms, with or without
15 * modification, are permitted provided that the following conditions
17 * 1. Redistributions of source code must retain the above copyright
18 * notice, this list of conditions and the following disclaimer.
19 * 2. Redistributions in binary form must reproduce the above copyright
20 * notice, this list of conditions and the following disclaimer in the
21 * documentation and/or other materials provided with the distribution.
22 * 3. All advertising materials mentioning features or use of this software
23 * must display the following acknowledgement:
24 * This product includes software developed by the University of
25 * California, Berkeley and its contributors.
26 * 4. Neither the name of the University nor the names of its contributors
27 * may be used to endorse or promote products derived from this software
28 * without specific prior written permission.
30 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
31 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
32 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
33 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
34 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
35 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
36 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
37 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
38 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
39 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
42 * from: @(#)vnode_pager.c 7.5 (Berkeley) 4/20/91
43 * $FreeBSD: src/sys/vm/vnode_pager.c,v 1.116.2.7 2002/12/31 09:34:51 dillon Exp $
47 * Page to/from files (vnodes).
52 * Implement VOP_GETPAGES/PUTPAGES interface for filesystems. Will
53 * greatly re-simplify the vnode_pager.
56 #include <sys/param.h>
57 #include <sys/systm.h>
58 #include <sys/kernel.h>
60 #include <sys/vnode.h>
61 #include <sys/mount.h>
63 #include <sys/vmmeter.h>
66 #include <cpu/lwbuf.h>
69 #include <vm/vm_object.h>
70 #include <vm/vm_page.h>
71 #include <vm/vm_pager.h>
72 #include <vm/vm_map.h>
73 #include <vm/vnode_pager.h>
74 #include <vm/swap_pager.h>
75 #include <vm/vm_extern.h>
77 #include <sys/thread2.h>
78 #include <vm/vm_page2.h>
80 static void vnode_pager_dealloc (vm_object_t);
81 static int vnode_pager_getpage (vm_object_t, vm_page_t *, int);
82 static void vnode_pager_putpages (vm_object_t, vm_page_t *, int, boolean_t, int *);
83 static boolean_t vnode_pager_haspage (vm_object_t, vm_pindex_t);
85 struct pagerops vnodepagerops = {
92 static struct krate vbadrate = { 1 };
93 static struct krate vresrate = { 1 };
95 int vnode_pbuf_freecnt = -1; /* start out unlimited */
98 * Allocate a VM object for a vnode, typically a regular file vnode.
100 * Some additional information is required to generate a properly sized
101 * object which covers the entire buffer cache buffer straddling the file
102 * EOF. Userland does not see the extra pages as the VM fault code tests
103 * against v_filesize.
106 vnode_pager_alloc(void *handle, off_t length, vm_prot_t prot, off_t offset,
107 int blksize, int boff)
115 * Pageout to vnode, no can do yet.
121 * XXX hack - This initialization should be put somewhere else.
123 if (vnode_pbuf_freecnt < 0) {
124 vnode_pbuf_freecnt = nswbuf / 2 + 1;
128 * Serialize potential vnode/object teardowns and interlocks
130 vp = (struct vnode *)handle;
131 lwkt_gettoken(&vp->v_token);
134 * Prevent race condition when allocating the object. This
135 * can happen with NFS vnodes since the nfsnode isn't locked.
137 while (vp->v_flag & VOLOCK) {
138 vsetflags(vp, VOWANT);
139 tsleep(vp, 0, "vnpobj", 0);
141 vsetflags(vp, VOLOCK);
142 lwkt_reltoken(&vp->v_token);
145 * If the object is being terminated, wait for it to
148 while ((object = vp->v_object) != NULL) {
149 vm_object_hold(object);
150 if ((object->flags & OBJ_DEAD) == 0)
152 vm_object_dead_sleep(object, "vadead");
153 vm_object_drop(object);
156 if (vp->v_sysref.refcnt <= 0)
157 panic("vnode_pager_alloc: no vnode reference");
160 * Round up to the *next* block, then destroy the buffers in question.
161 * Since we are only removing some of the buffers we must rely on the
162 * scan count to determine whether a loop is necessary.
164 * Destroy any pages beyond the last buffer.
167 boff = (int)(length % blksize);
169 loffset = length + (blksize - boff);
172 lsize = OFF_TO_IDX(round_page64(loffset));
174 if (object == NULL) {
176 * And an object of the appropriate size
178 object = vm_object_allocate_hold(OBJT_VNODE, lsize);
179 object->handle = handle;
180 vp->v_object = object;
181 vp->v_filesize = length;
182 if (vp->v_mount && (vp->v_mount->mnt_kern_flag & MNTK_NOMSYNC))
183 vm_object_set_flag(object, OBJ_NOMSYNC);
186 if (object->size != lsize) {
187 kprintf("vnode_pager_alloc: Warning, objsize "
188 "mismatch %jd/%jd vp=%p obj=%p\n",
189 (intmax_t)object->size,
193 if (vp->v_filesize != length) {
194 kprintf("vnode_pager_alloc: Warning, filesize "
195 "mismatch %jd/%jd vp=%p obj=%p\n",
196 (intmax_t)vp->v_filesize,
203 lwkt_gettoken(&vp->v_token);
204 vclrflags(vp, VOLOCK);
205 if (vp->v_flag & VOWANT) {
206 vclrflags(vp, VOWANT);
209 lwkt_reltoken(&vp->v_token);
211 vm_object_drop(object);
217 * Add a ref to a vnode's existing VM object, return the object or
218 * NULL if the vnode did not have one. This does not create the
219 * object (we can't since we don't know what the proper blocksize/boff
220 * is to match the VFS's use of the buffer cache).
223 vnode_pager_reference(struct vnode *vp)
228 * Prevent race condition when allocating the object. This
229 * can happen with NFS vnodes since the nfsnode isn't locked.
231 * Serialize potential vnode/object teardowns and interlocks
233 lwkt_gettoken(&vp->v_token);
234 while (vp->v_flag & VOLOCK) {
235 vsetflags(vp, VOWANT);
236 tsleep(vp, 0, "vnpobj", 0);
238 vsetflags(vp, VOLOCK);
239 lwkt_reltoken(&vp->v_token);
242 * Prevent race conditions against deallocation of the VM
245 while ((object = vp->v_object) != NULL) {
246 vm_object_hold(object);
247 if ((object->flags & OBJ_DEAD) == 0)
249 vm_object_dead_sleep(object, "vadead");
250 vm_object_drop(object);
254 * The object is expected to exist, the caller will handle
255 * NULL returns if it does not.
262 lwkt_gettoken(&vp->v_token);
263 vclrflags(vp, VOLOCK);
264 if (vp->v_flag & VOWANT) {
265 vclrflags(vp, VOWANT);
268 lwkt_reltoken(&vp->v_token);
270 vm_object_drop(object);
276 vnode_pager_dealloc(vm_object_t object)
278 struct vnode *vp = object->handle;
281 panic("vnode_pager_dealloc: pager already dealloced");
283 vm_object_pip_wait(object, "vnpdea");
285 object->handle = NULL;
286 object->type = OBJT_DEAD;
288 vp->v_filesize = NOOFFSET;
289 vclrflags(vp, VTEXT | VOBJBUF);
290 swap_pager_freespace_all(object);
294 * Return whether the vnode pager has the requested page. Return the
295 * number of disk-contiguous pages before and after the requested page,
296 * not including the requested page.
299 vnode_pager_haspage(vm_object_t object, vm_pindex_t pindex)
301 struct vnode *vp = object->handle;
309 * If no vp or vp is doomed or marked transparent to VM, we do not
312 if ((vp == NULL) || (vp->v_flag & VRECLAIMED))
316 * If filesystem no longer mounted or offset beyond end of file we do
319 loffset = IDX_TO_OFF(pindex);
321 if (vp->v_mount == NULL || loffset >= vp->v_filesize)
324 bsize = vp->v_mount->mnt_stat.f_iosize;
325 voff = loffset % bsize;
330 * BMAP returns byte counts before and after, where after
331 * is inclusive of the base page. haspage must return page
332 * counts before and after where after does not include the
335 * BMAP is allowed to return a *after of 0 for backwards
336 * compatibility. The base page is still considered valid if
337 * no error is returned.
339 error = VOP_BMAP(vp, loffset - voff, &doffset, NULL, NULL, 0);
342 if (doffset == NOOFFSET)
348 * Lets the VM system know about a change in size for a file.
349 * We adjust our own internal size and flush any cached pages in
350 * the associated object that are affected by the size change.
352 * NOTE: This routine may be invoked as a result of a pager put
353 * operation (possibly at object termination time), so we must be careful.
355 * NOTE: vp->v_filesize is initialized to NOOFFSET (-1), be sure that
356 * we do not blow up on the case. nsize will always be >= 0, however.
359 vnode_pager_setsize(struct vnode *vp, vm_ooffset_t nsize)
361 vm_pindex_t nobjsize;
362 vm_pindex_t oobjsize;
365 while ((object = vp->v_object) != NULL) {
366 vm_object_hold(object);
367 if (vp->v_object == object)
369 vm_object_drop(object);
375 * Hasn't changed size
377 if (nsize == vp->v_filesize) {
378 vm_object_drop(object);
383 * Has changed size. Adjust the VM object's size and v_filesize
384 * before we start scanning pages to prevent new pages from being
385 * allocated during the scan.
387 nobjsize = OFF_TO_IDX(nsize + PAGE_MASK);
388 oobjsize = object->size;
389 object->size = nobjsize;
392 * File has shrunk. Toss any cached pages beyond the new EOF.
394 if (nsize < vp->v_filesize) {
395 vp->v_filesize = nsize;
396 if (nobjsize < oobjsize) {
397 vm_object_page_remove(object, nobjsize, oobjsize,
401 * This gets rid of garbage at the end of a page that is now
402 * only partially backed by the vnode. Since we are setting
403 * the entire page valid & clean after we are done we have
404 * to be sure that the portion of the page within the file
405 * bounds is already valid. If it isn't then making it
406 * valid would create a corrupt block.
408 if (nsize & PAGE_MASK) {
412 m = vm_page_lookup_busy_wait(object, OFF_TO_IDX(nsize),
416 int base = (int)nsize & PAGE_MASK;
417 int size = PAGE_SIZE - base;
419 struct lwbuf lwb_cache;
422 * Clear out partial-page garbage in case
423 * the page has been mapped.
425 * This is byte aligned.
427 lwb = lwbuf_alloc(m, &lwb_cache);
428 kva = lwbuf_kva(lwb);
429 bzero((caddr_t)kva + base, size);
433 * XXX work around SMP data integrity race
434 * by unmapping the page from user processes.
435 * The garbage we just cleared may be mapped
436 * to a user process running on another cpu
437 * and this code is not running through normal
438 * I/O channels which handle SMP issues for
439 * us, so unmap page to synchronize all cpus.
441 * XXX should vm_pager_unmap_page() have
444 vm_page_protect(m, VM_PROT_NONE);
447 * Clear out partial-page dirty bits. This
448 * has the side effect of setting the valid
449 * bits, but that is ok. There are a bunch
450 * of places in the VM system where we expected
451 * m->dirty == VM_PAGE_BITS_ALL. The file EOF
452 * case is one of them. If the page is still
453 * partially dirty, make it fully dirty.
455 * NOTE: We do not clear out the valid
456 * bits. This would prevent bogus_page
457 * replacement from working properly.
459 * NOTE: We do not want to clear the dirty
460 * bit for a partial DEV_BSIZE'd truncation!
461 * This is DEV_BSIZE aligned!
463 vm_page_clear_dirty_beg_nonincl(m, base, size);
465 m->dirty = VM_PAGE_BITS_ALL;
472 vp->v_filesize = nsize;
474 vm_object_drop(object);
478 * Release a page busied for a getpages operation. The page may have become
479 * wired (typically due to being used by the buffer cache) or otherwise been
480 * soft-busied and cannot be freed in that case. A held page can still be
484 vnode_pager_freepage(vm_page_t m)
486 if (m->busy || m->wire_count || (m->flags & PG_NEED_COMMIT)) {
495 * EOPNOTSUPP is no longer legal. For local media VFS's that do not
496 * implement their own VOP_GETPAGES, their VOP_GETPAGES should call to
497 * vnode_pager_generic_getpages() to implement the previous behaviour.
499 * All other FS's should use the bypass to get to the local media
500 * backing vp's VOP_GETPAGES.
503 vnode_pager_getpage(vm_object_t object, vm_page_t *mpp, int seqaccess)
509 rtval = VOP_GETPAGES(vp, mpp, PAGE_SIZE, 0, 0, seqaccess);
510 if (rtval == EOPNOTSUPP)
511 panic("vnode_pager: vfs's must implement vop_getpages");
516 * This is now called from local media FS's to operate against their
517 * own vnodes if they fail to implement VOP_GETPAGES.
519 * With all the caching local media devices do these days there is really
520 * very little point to attempting to restrict the I/O size to contiguous
521 * blocks on-disk, especially if our caller thinks we need all the specified
522 * pages. Just construct and issue a READ.
525 vnode_pager_generic_getpages(struct vnode *vp, vm_page_t *mpp, int bytecount,
526 int reqpage, int seqaccess)
537 * Do not do anything if the vnode is bad.
539 if (vp->v_mount == NULL)
543 * Calculate the number of pages. Since we are paging in whole
544 * pages, adjust bytecount to be an integral multiple of the page
545 * size. It will be clipped to the file EOF later on.
547 bytecount = round_page(bytecount);
548 count = bytecount / PAGE_SIZE;
551 * We could check m[reqpage]->valid here and shortcut the operation,
552 * but doing so breaks read-ahead. Instead assume that the VM
553 * system has already done at least the check, don't worry about
554 * any races, and issue the VOP_READ to allow read-ahead to function.
556 * This keeps the pipeline full for I/O bound sequentially scanned
562 * Discard pages past the file EOF. If the requested page is past
563 * the file EOF we just leave its valid bits set to 0, the caller
564 * expects to maintain ownership of the requested page. If the
565 * entire range is past file EOF discard everything and generate
568 foff = IDX_TO_OFF(mpp[0]->pindex);
569 if (foff >= vp->v_filesize) {
570 for (i = 0; i < count; i++) {
572 vnode_pager_freepage(mpp[i]);
574 return VM_PAGER_ERROR;
577 if (foff + bytecount > vp->v_filesize) {
578 bytecount = vp->v_filesize - foff;
579 i = round_page(bytecount) / PAGE_SIZE;
582 if (count != reqpage)
583 vnode_pager_freepage(mpp[count]);
588 * The size of the transfer is bytecount. bytecount will be an
589 * integral multiple of the page size unless it has been clipped
590 * to the file EOF. The transfer cannot exceed the file EOF.
592 * When dealing with real devices we must round-up to the device
595 if (vp->v_type == VBLK || vp->v_type == VCHR) {
596 int secmask = vp->v_rdev->si_bsize_phys - 1;
597 KASSERT(secmask < PAGE_SIZE, ("vnode_pager_generic_getpages: sector size %d too large", secmask + 1));
598 bytecount = (bytecount + secmask) & ~secmask;
602 * Severe hack to avoid deadlocks with the buffer cache
604 for (i = 0; i < count; ++i) {
605 vm_page_t mt = mpp[i];
607 vm_page_io_start(mt);
612 * Issue the I/O with some read-ahead if bytecount > PAGE_SIZE
616 ioflags |= IO_SEQMAX << IO_SEQSHIFT;
618 aiov.iov_base = NULL;
619 aiov.iov_len = bytecount;
620 auio.uio_iov = &aiov;
622 auio.uio_offset = foff;
623 auio.uio_segflg = UIO_NOCOPY;
624 auio.uio_rw = UIO_READ;
625 auio.uio_resid = bytecount;
627 mycpu->gd_cnt.v_vnodein++;
628 mycpu->gd_cnt.v_vnodepgsin += count;
630 error = VOP_READ(vp, &auio, ioflags, proc0.p_ucred);
633 * Severe hack to avoid deadlocks with the buffer cache
635 for (i = 0; i < count; ++i) {
636 vm_page_busy_wait(mpp[i], FALSE, "getpgs");
637 vm_page_io_finish(mpp[i]);
641 * Calculate the actual number of bytes read and clean up the
644 bytecount -= auio.uio_resid;
646 for (i = 0; i < count; ++i) {
647 vm_page_t mt = mpp[i];
650 if (error == 0 && mt->valid) {
651 if (mt->flags & PG_REFERENCED)
652 vm_page_activate(mt);
654 vm_page_deactivate(mt);
657 vnode_pager_freepage(mt);
659 } else if (mt->valid == 0) {
661 kprintf("page failed but no I/O error page "
662 "%p object %p pindex %d\n",
663 mt, mt->object, (int) mt->pindex);
664 /* whoops, something happened */
667 } else if (mt->valid != VM_PAGE_BITS_ALL) {
669 * Zero-extend the requested page if necessary (if
670 * the filesystem is using a small block size).
672 vm_page_zero_invalid(mt, TRUE);
676 kprintf("vnode_pager_getpage: I/O read error\n");
678 return (error ? VM_PAGER_ERROR : VM_PAGER_OK);
682 * EOPNOTSUPP is no longer legal. For local media VFS's that do not
683 * implement their own VOP_PUTPAGES, their VOP_PUTPAGES should call to
684 * vnode_pager_generic_putpages() to implement the previous behaviour.
686 * Caller has already cleared the pmap modified bits, if any.
688 * All other FS's should use the bypass to get to the local media
689 * backing vp's VOP_PUTPAGES.
692 vnode_pager_putpages(vm_object_t object, vm_page_t *m, int count,
693 boolean_t sync, int *rtvals)
697 int bytes = count * PAGE_SIZE;
700 * Force synchronous operation if we are extremely low on memory
701 * to prevent a low-memory deadlock. VOP operations often need to
702 * allocate more memory to initiate the I/O ( i.e. do a BMAP
703 * operation ). The swapper handles the case by limiting the amount
704 * of asynchronous I/O, but that sort of solution doesn't scale well
705 * for the vnode pager without a lot of work.
707 * Also, the backing vnode's iodone routine may not wake the pageout
708 * daemon up. This should be probably be addressed XXX.
711 if ((vmstats.v_free_count + vmstats.v_cache_count) <
712 vmstats.v_pageout_free_min) {
717 * Call device-specific putpages function
720 rtval = VOP_PUTPAGES(vp, m, bytes, sync, rtvals, 0);
721 if (rtval == EOPNOTSUPP) {
722 kprintf("vnode_pager: *** WARNING *** stale FS putpages\n");
723 rtval = vnode_pager_generic_putpages( vp, m, bytes, sync, rtvals);
729 * This is now called from local media FS's to operate against their
730 * own vnodes if they fail to implement VOP_PUTPAGES.
732 * This is typically called indirectly via the pageout daemon and
733 * clustering has already typically occured, so in general we ask the
734 * underlying filesystem to write the data out asynchronously rather
738 vnode_pager_generic_putpages(struct vnode *vp, vm_page_t *m, int bytecount,
739 int flags, int *rtvals)
742 int maxsize, ncount, count;
743 vm_ooffset_t poffset;
749 count = bytecount / PAGE_SIZE;
751 for (i = 0; i < count; i++)
752 rtvals[i] = VM_PAGER_AGAIN;
754 if ((int) m[0]->pindex < 0) {
755 kprintf("vnode_pager_putpages: attempt to write meta-data!!! -- 0x%lx(%x)\n",
756 (long)m[0]->pindex, m[0]->dirty);
757 rtvals[0] = VM_PAGER_BAD;
761 maxsize = count * PAGE_SIZE;
764 poffset = IDX_TO_OFF(m[0]->pindex);
767 * If the page-aligned write is larger then the actual file we
768 * have to invalidate pages occuring beyond the file EOF.
770 * If the file EOF resides in the middle of a page we still clear
771 * all of that page's dirty bits later on. If we didn't it would
772 * endlessly re-write.
774 * We do not under any circumstances truncate the valid bits, as
775 * this will screw up bogus page replacement.
777 * The caller has already read-protected the pages. The VFS must
778 * use the buffer cache to wrap the pages. The pages might not
779 * be immediately flushed by the buffer cache but once under its
780 * control the pages themselves can wind up being marked clean
781 * and their covering buffer cache buffer can be marked dirty.
783 if (poffset + maxsize > vp->v_filesize) {
784 if (poffset < vp->v_filesize) {
785 maxsize = vp->v_filesize - poffset;
786 ncount = btoc(maxsize);
791 if (ncount < count) {
792 for (i = ncount; i < count; i++) {
793 rtvals[i] = VM_PAGER_BAD;
799 * pageouts are already clustered, use IO_ASYNC to force a bawrite()
800 * rather then a bdwrite() to prevent paging I/O from saturating
801 * the buffer cache. Dummy-up the sequential heuristic to cause
802 * large ranges to cluster. If neither IO_SYNC or IO_ASYNC is set,
803 * the system decides how to cluster.
806 if (flags & (VM_PAGER_PUT_SYNC | VM_PAGER_PUT_INVAL))
808 else if ((flags & VM_PAGER_CLUSTER_OK) == 0)
810 ioflags |= (flags & VM_PAGER_PUT_INVAL) ? IO_INVAL: 0;
811 ioflags |= IO_SEQMAX << IO_SEQSHIFT;
813 aiov.iov_base = (caddr_t) 0;
814 aiov.iov_len = maxsize;
815 auio.uio_iov = &aiov;
817 auio.uio_offset = poffset;
818 auio.uio_segflg = UIO_NOCOPY;
819 auio.uio_rw = UIO_WRITE;
820 auio.uio_resid = maxsize;
822 error = VOP_WRITE(vp, &auio, ioflags, proc0.p_ucred);
823 mycpu->gd_cnt.v_vnodeout++;
824 mycpu->gd_cnt.v_vnodepgsout += ncount;
827 krateprintf(&vbadrate,
828 "vnode_pager_putpages: I/O error %d\n", error);
830 if (auio.uio_resid) {
831 krateprintf(&vresrate,
832 "vnode_pager_putpages: residual I/O %zd at %lu\n",
833 auio.uio_resid, (u_long)m[0]->pindex);
836 for (i = 0; i < ncount; i++) {
837 rtvals[i] = VM_PAGER_OK;
838 vm_page_undirty(m[i]);
845 * Run the chain and if the bottom-most object is a vnode-type lock the
846 * underlying vnode. A locked vnode or NULL is returned.
849 vnode_pager_lock(vm_object_t object)
851 struct vnode *vp = NULL;
859 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object));
862 while (lobject->type != OBJT_VNODE) {
863 if (lobject->flags & OBJ_DEAD)
865 tobject = lobject->backing_object;
868 vm_object_hold(tobject);
869 if (tobject == lobject->backing_object) {
870 if (lobject != object) {
871 vm_object_lock_swap();
872 vm_object_drop(lobject);
876 vm_object_drop(tobject);
879 while (lobject->type == OBJT_VNODE &&
880 (lobject->flags & OBJ_DEAD) == 0) {
884 vp = lobject->handle;
885 error = vget(vp, LK_SHARED | LK_RETRY | LK_CANRECURSE);
887 if (lobject->handle == vp)
891 kprintf("vnode_pager_lock: vp %p error %d "
892 "lockstatus %d, retrying\n",
894 lockstatus(&vp->v_lock, curthread));
895 tsleep(object->handle, 0, "vnpgrl", hz);
899 if (lobject != object)
900 vm_object_drop(lobject);