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 $
44 * $DragonFly: src/sys/vm/vnode_pager.c,v 1.43 2008/06/19 23:27:39 dillon Exp $
48 * Page to/from files (vnodes).
53 * Implement VOP_GETPAGES/PUTPAGES interface for filesystems. Will
54 * greatly re-simplify the vnode_pager.
57 #include <sys/param.h>
58 #include <sys/systm.h>
59 #include <sys/kernel.h>
61 #include <sys/vnode.h>
62 #include <sys/mount.h>
64 #include <sys/vmmeter.h>
67 #include <cpu/lwbuf.h>
70 #include <vm/vm_object.h>
71 #include <vm/vm_page.h>
72 #include <vm/vm_pager.h>
73 #include <vm/vm_map.h>
74 #include <vm/vnode_pager.h>
75 #include <vm/swap_pager.h>
76 #include <vm/vm_extern.h>
78 #include <sys/thread2.h>
79 #include <vm/vm_page2.h>
81 static void vnode_pager_dealloc (vm_object_t);
82 static int vnode_pager_getpage (vm_object_t, vm_page_t *, int);
83 static void vnode_pager_putpages (vm_object_t, vm_page_t *, int, boolean_t, int *);
84 static boolean_t vnode_pager_haspage (vm_object_t, vm_pindex_t);
86 struct pagerops vnodepagerops = {
93 static struct krate vbadrate = { 1 };
94 static struct krate vresrate = { 1 };
96 int vnode_pbuf_freecnt = -1; /* start out unlimited */
99 * Allocate a VM object for a vnode, typically a regular file vnode.
101 * Some additional information is required to generate a properly sized
102 * object which covers the entire buffer cache buffer straddling the file
103 * EOF. Userland does not see the extra pages as the VM fault code tests
104 * against v_filesize.
107 vnode_pager_alloc(void *handle, off_t length, vm_prot_t prot, off_t offset,
108 int blksize, int boff)
116 * Pageout to vnode, no can do yet.
122 * XXX hack - This initialization should be put somewhere else.
124 if (vnode_pbuf_freecnt < 0) {
125 vnode_pbuf_freecnt = nswbuf / 2 + 1;
129 * Serialize potential vnode/object teardowns and interlocks
131 vp = (struct vnode *)handle;
132 lwkt_gettoken(&vp->v_token);
135 * Prevent race condition when allocating the object. This
136 * can happen with NFS vnodes since the nfsnode isn't locked.
138 while (vp->v_flag & VOLOCK) {
139 vsetflags(vp, VOWANT);
140 tsleep(vp, 0, "vnpobj", 0);
142 vsetflags(vp, VOLOCK);
143 lwkt_reltoken(&vp->v_token);
146 * If the object is being terminated, wait for it to
149 while ((object = vp->v_object) != NULL) {
150 vm_object_hold(object);
151 if ((object->flags & OBJ_DEAD) == 0)
153 vm_object_dead_sleep(object, "vadead");
154 vm_object_drop(object);
157 if (vp->v_sysref.refcnt <= 0)
158 panic("vnode_pager_alloc: no vnode reference");
161 * Round up to the *next* block, then destroy the buffers in question.
162 * Since we are only removing some of the buffers we must rely on the
163 * scan count to determine whether a loop is necessary.
165 * Destroy any pages beyond the last buffer.
168 boff = (int)(length % blksize);
170 loffset = length + (blksize - boff);
173 lsize = OFF_TO_IDX(round_page64(loffset));
175 if (object == NULL) {
177 * And an object of the appropriate size
179 object = vm_object_allocate_hold(OBJT_VNODE, lsize);
181 object->handle = handle;
182 vp->v_object = object;
183 vp->v_filesize = length;
184 if (vp->v_mount && (vp->v_mount->mnt_kern_flag & MNTK_NOMSYNC))
185 vm_object_set_flag(object, OBJ_NOMSYNC);
188 if (object->size != lsize) {
189 kprintf("vnode_pager_alloc: Warning, objsize "
190 "mismatch %jd/%jd vp=%p obj=%p\n",
191 (intmax_t)object->size,
195 if (vp->v_filesize != length) {
196 kprintf("vnode_pager_alloc: Warning, filesize "
197 "mismatch %jd/%jd vp=%p obj=%p\n",
198 (intmax_t)vp->v_filesize,
205 lwkt_gettoken(&vp->v_token);
206 vclrflags(vp, VOLOCK);
207 if (vp->v_flag & VOWANT) {
208 vclrflags(vp, VOWANT);
211 lwkt_reltoken(&vp->v_token);
213 vm_object_drop(object);
219 * Add a ref to a vnode's existing VM object, return the object or
220 * NULL if the vnode did not have one. This does not create the
221 * object (we can't since we don't know what the proper blocksize/boff
222 * is to match the VFS's use of the buffer cache).
225 vnode_pager_reference(struct vnode *vp)
230 * Prevent race condition when allocating the object. This
231 * can happen with NFS vnodes since the nfsnode isn't locked.
233 * Serialize potential vnode/object teardowns and interlocks
235 lwkt_gettoken(&vp->v_token);
236 while (vp->v_flag & VOLOCK) {
237 vsetflags(vp, VOWANT);
238 tsleep(vp, 0, "vnpobj", 0);
240 vsetflags(vp, VOLOCK);
241 lwkt_reltoken(&vp->v_token);
244 * Prevent race conditions against deallocation of the VM
247 while ((object = vp->v_object) != NULL) {
248 vm_object_hold(object);
249 if ((object->flags & OBJ_DEAD) == 0)
251 vm_object_dead_sleep(object, "vadead");
252 vm_object_drop(object);
256 * The object is expected to exist, the caller will handle
257 * NULL returns if it does not.
264 lwkt_gettoken(&vp->v_token);
265 vclrflags(vp, VOLOCK);
266 if (vp->v_flag & VOWANT) {
267 vclrflags(vp, VOWANT);
270 lwkt_reltoken(&vp->v_token);
272 vm_object_drop(object);
278 vnode_pager_dealloc(vm_object_t object)
280 struct vnode *vp = object->handle;
283 panic("vnode_pager_dealloc: pager already dealloced");
285 vm_object_pip_wait(object, "vnpdea");
287 object->handle = NULL;
288 object->type = OBJT_DEAD;
290 vp->v_filesize = NOOFFSET;
291 vclrflags(vp, VTEXT | VOBJBUF);
292 swap_pager_freespace_all(object);
296 * Return whether the vnode pager has the requested page. Return the
297 * number of disk-contiguous pages before and after the requested page,
298 * not including the requested page.
301 vnode_pager_haspage(vm_object_t object, vm_pindex_t pindex)
303 struct vnode *vp = object->handle;
311 * If no vp or vp is doomed or marked transparent to VM, we do not
314 if ((vp == NULL) || (vp->v_flag & VRECLAIMED))
318 * If filesystem no longer mounted or offset beyond end of file we do
321 loffset = IDX_TO_OFF(pindex);
323 if (vp->v_mount == NULL || loffset >= vp->v_filesize)
326 bsize = vp->v_mount->mnt_stat.f_iosize;
327 voff = loffset % bsize;
332 * BMAP returns byte counts before and after, where after
333 * is inclusive of the base page. haspage must return page
334 * counts before and after where after does not include the
337 * BMAP is allowed to return a *after of 0 for backwards
338 * compatibility. The base page is still considered valid if
339 * no error is returned.
341 error = VOP_BMAP(vp, loffset - voff, &doffset, NULL, NULL, 0);
344 if (doffset == NOOFFSET)
350 * Lets the VM system know about a change in size for a file.
351 * We adjust our own internal size and flush any cached pages in
352 * the associated object that are affected by the size change.
354 * NOTE: This routine may be invoked as a result of a pager put
355 * operation (possibly at object termination time), so we must be careful.
357 * NOTE: vp->v_filesize is initialized to NOOFFSET (-1), be sure that
358 * we do not blow up on the case. nsize will always be >= 0, however.
361 vnode_pager_setsize(struct vnode *vp, vm_ooffset_t nsize)
363 vm_pindex_t nobjsize;
364 vm_pindex_t oobjsize;
367 while ((object = vp->v_object) != NULL) {
368 vm_object_hold(object);
369 if (vp->v_object == object)
371 vm_object_drop(object);
377 * Hasn't changed size
379 if (nsize == vp->v_filesize) {
380 vm_object_drop(object);
385 * Has changed size. Adjust the VM object's size and v_filesize
386 * before we start scanning pages to prevent new pages from being
387 * allocated during the scan.
389 nobjsize = OFF_TO_IDX(nsize + PAGE_MASK);
390 oobjsize = object->size;
391 object->size = nobjsize;
394 * File has shrunk. Toss any cached pages beyond the new EOF.
396 if (nsize < vp->v_filesize) {
397 vp->v_filesize = nsize;
398 if (nobjsize < oobjsize) {
399 vm_object_page_remove(object, nobjsize, oobjsize,
403 * This gets rid of garbage at the end of a page that is now
404 * only partially backed by the vnode. Since we are setting
405 * the entire page valid & clean after we are done we have
406 * to be sure that the portion of the page within the file
407 * bounds is already valid. If it isn't then making it
408 * valid would create a corrupt block.
410 if (nsize & PAGE_MASK) {
414 m = vm_page_lookup_busy_wait(object, OFF_TO_IDX(nsize),
418 int base = (int)nsize & PAGE_MASK;
419 int size = PAGE_SIZE - base;
421 struct lwbuf lwb_cache;
424 * Clear out partial-page garbage in case
425 * the page has been mapped.
427 * This is byte aligned.
429 lwb = lwbuf_alloc(m, &lwb_cache);
430 kva = lwbuf_kva(lwb);
431 bzero((caddr_t)kva + base, size);
435 * XXX work around SMP data integrity race
436 * by unmapping the page from user processes.
437 * The garbage we just cleared may be mapped
438 * to a user process running on another cpu
439 * and this code is not running through normal
440 * I/O channels which handle SMP issues for
441 * us, so unmap page to synchronize all cpus.
443 * XXX should vm_pager_unmap_page() have
446 vm_page_protect(m, VM_PROT_NONE);
449 * Clear out partial-page dirty bits. This
450 * has the side effect of setting the valid
451 * bits, but that is ok. There are a bunch
452 * of places in the VM system where we expected
453 * m->dirty == VM_PAGE_BITS_ALL. The file EOF
454 * case is one of them. If the page is still
455 * partially dirty, make it fully dirty.
457 * NOTE: We do not clear out the valid
458 * bits. This would prevent bogus_page
459 * replacement from working properly.
461 * NOTE: We do not want to clear the dirty
462 * bit for a partial DEV_BSIZE'd truncation!
463 * This is DEV_BSIZE aligned!
465 vm_page_clear_dirty_beg_nonincl(m, base, size);
467 m->dirty = VM_PAGE_BITS_ALL;
474 vp->v_filesize = nsize;
476 vm_object_drop(object);
480 * Release a page busied for a getpages operation. The page may have become
481 * wired (typically due to being used by the buffer cache) or otherwise been
482 * soft-busied and cannot be freed in that case. A held page can still be
486 vnode_pager_freepage(vm_page_t m)
488 if (m->busy || m->wire_count) {
497 * EOPNOTSUPP is no longer legal. For local media VFS's that do not
498 * implement their own VOP_GETPAGES, their VOP_GETPAGES should call to
499 * vnode_pager_generic_getpages() to implement the previous behaviour.
501 * All other FS's should use the bypass to get to the local media
502 * backing vp's VOP_GETPAGES.
505 vnode_pager_getpage(vm_object_t object, vm_page_t *mpp, int seqaccess)
511 rtval = VOP_GETPAGES(vp, mpp, PAGE_SIZE, 0, 0, seqaccess);
512 if (rtval == EOPNOTSUPP)
513 panic("vnode_pager: vfs's must implement vop_getpages\n");
518 * This is now called from local media FS's to operate against their
519 * own vnodes if they fail to implement VOP_GETPAGES.
521 * With all the caching local media devices do these days there is really
522 * very little point to attempting to restrict the I/O size to contiguous
523 * blocks on-disk, especially if our caller thinks we need all the specified
524 * pages. Just construct and issue a READ.
527 vnode_pager_generic_getpages(struct vnode *vp, vm_page_t *mpp, int bytecount,
528 int reqpage, int seqaccess)
539 * Do not do anything if the vnode is bad.
541 if (vp->v_mount == NULL)
545 * Calculate the number of pages. Since we are paging in whole
546 * pages, adjust bytecount to be an integral multiple of the page
547 * size. It will be clipped to the file EOF later on.
549 bytecount = round_page(bytecount);
550 count = bytecount / PAGE_SIZE;
553 * We could check m[reqpage]->valid here and shortcut the operation,
554 * but doing so breaks read-ahead. Instead assume that the VM
555 * system has already done at least the check, don't worry about
556 * any races, and issue the VOP_READ to allow read-ahead to function.
558 * This keeps the pipeline full for I/O bound sequentially scanned
564 * Discard pages past the file EOF. If the requested page is past
565 * the file EOF we just leave its valid bits set to 0, the caller
566 * expects to maintain ownership of the requested page. If the
567 * entire range is past file EOF discard everything and generate
570 foff = IDX_TO_OFF(mpp[0]->pindex);
571 if (foff >= vp->v_filesize) {
572 for (i = 0; i < count; i++) {
574 vnode_pager_freepage(mpp[i]);
576 return VM_PAGER_ERROR;
579 if (foff + bytecount > vp->v_filesize) {
580 bytecount = vp->v_filesize - foff;
581 i = round_page(bytecount) / PAGE_SIZE;
584 if (count != reqpage)
585 vnode_pager_freepage(mpp[count]);
590 * The size of the transfer is bytecount. bytecount will be an
591 * integral multiple of the page size unless it has been clipped
592 * to the file EOF. The transfer cannot exceed the file EOF.
594 * When dealing with real devices we must round-up to the device
597 if (vp->v_type == VBLK || vp->v_type == VCHR) {
598 int secmask = vp->v_rdev->si_bsize_phys - 1;
599 KASSERT(secmask < PAGE_SIZE, ("vnode_pager_generic_getpages: sector size %d too large\n", secmask + 1));
600 bytecount = (bytecount + secmask) & ~secmask;
604 * Severe hack to avoid deadlocks with the buffer cache
606 for (i = 0; i < count; ++i) {
607 vm_page_t mt = mpp[i];
609 vm_page_io_start(mt);
614 * Issue the I/O with some read-ahead if bytecount > PAGE_SIZE
618 ioflags |= IO_SEQMAX << IO_SEQSHIFT;
620 aiov.iov_base = NULL;
621 aiov.iov_len = bytecount;
622 auio.uio_iov = &aiov;
624 auio.uio_offset = foff;
625 auio.uio_segflg = UIO_NOCOPY;
626 auio.uio_rw = UIO_READ;
627 auio.uio_resid = bytecount;
629 mycpu->gd_cnt.v_vnodein++;
630 mycpu->gd_cnt.v_vnodepgsin += count;
632 error = VOP_READ(vp, &auio, ioflags, proc0.p_ucred);
635 * Severe hack to avoid deadlocks with the buffer cache
637 for (i = 0; i < count; ++i) {
638 vm_page_busy_wait(mpp[i], FALSE, "getpgs");
639 vm_page_io_finish(mpp[i]);
643 * Calculate the actual number of bytes read and clean up the
646 bytecount -= auio.uio_resid;
648 for (i = 0; i < count; ++i) {
649 vm_page_t mt = mpp[i];
652 if (error == 0 && mt->valid) {
653 if (mt->flags & PG_REFERENCED)
654 vm_page_activate(mt);
656 vm_page_deactivate(mt);
659 vnode_pager_freepage(mt);
661 } else if (mt->valid == 0) {
663 kprintf("page failed but no I/O error page "
664 "%p object %p pindex %d\n",
665 mt, mt->object, (int) mt->pindex);
666 /* whoops, something happened */
669 } else if (mt->valid != VM_PAGE_BITS_ALL) {
671 * Zero-extend the requested page if necessary (if
672 * the filesystem is using a small block size).
674 vm_page_zero_invalid(mt, TRUE);
678 kprintf("vnode_pager_getpage: I/O read error\n");
680 return (error ? VM_PAGER_ERROR : VM_PAGER_OK);
684 * EOPNOTSUPP is no longer legal. For local media VFS's that do not
685 * implement their own VOP_PUTPAGES, their VOP_PUTPAGES should call to
686 * vnode_pager_generic_putpages() to implement the previous behaviour.
688 * Caller has already cleared the pmap modified bits, if any.
690 * All other FS's should use the bypass to get to the local media
691 * backing vp's VOP_PUTPAGES.
694 vnode_pager_putpages(vm_object_t object, vm_page_t *m, int count,
695 boolean_t sync, int *rtvals)
699 int bytes = count * PAGE_SIZE;
702 * Force synchronous operation if we are extremely low on memory
703 * to prevent a low-memory deadlock. VOP operations often need to
704 * allocate more memory to initiate the I/O ( i.e. do a BMAP
705 * operation ). The swapper handles the case by limiting the amount
706 * of asynchronous I/O, but that sort of solution doesn't scale well
707 * for the vnode pager without a lot of work.
709 * Also, the backing vnode's iodone routine may not wake the pageout
710 * daemon up. This should be probably be addressed XXX.
713 if ((vmstats.v_free_count + vmstats.v_cache_count) <
714 vmstats.v_pageout_free_min) {
719 * Call device-specific putpages function
722 rtval = VOP_PUTPAGES(vp, m, bytes, sync, rtvals, 0);
723 if (rtval == EOPNOTSUPP) {
724 kprintf("vnode_pager: *** WARNING *** stale FS putpages\n");
725 rtval = vnode_pager_generic_putpages( vp, m, bytes, sync, rtvals);
731 * This is now called from local media FS's to operate against their
732 * own vnodes if they fail to implement VOP_PUTPAGES.
734 * This is typically called indirectly via the pageout daemon and
735 * clustering has already typically occured, so in general we ask the
736 * underlying filesystem to write the data out asynchronously rather
740 vnode_pager_generic_putpages(struct vnode *vp, vm_page_t *m, int bytecount,
741 int flags, int *rtvals)
745 int maxsize, ncount, count;
746 vm_ooffset_t poffset;
752 object = vp->v_object;
753 count = bytecount / PAGE_SIZE;
755 for (i = 0; i < count; i++)
756 rtvals[i] = VM_PAGER_AGAIN;
758 if ((int) m[0]->pindex < 0) {
759 kprintf("vnode_pager_putpages: attempt to write meta-data!!! -- 0x%lx(%x)\n",
760 (long)m[0]->pindex, m[0]->dirty);
761 rtvals[0] = VM_PAGER_BAD;
765 maxsize = count * PAGE_SIZE;
768 poffset = IDX_TO_OFF(m[0]->pindex);
771 * If the page-aligned write is larger then the actual file we
772 * have to invalidate pages occuring beyond the file EOF.
774 * If the file EOF resides in the middle of a page we still clear
775 * all of that page's dirty bits later on. If we didn't it would
776 * endlessly re-write.
778 * We do not under any circumstances truncate the valid bits, as
779 * this will screw up bogus page replacement.
781 * The caller has already read-protected the pages. The VFS must
782 * use the buffer cache to wrap the pages. The pages might not
783 * be immediately flushed by the buffer cache but once under its
784 * control the pages themselves can wind up being marked clean
785 * and their covering buffer cache buffer can be marked dirty.
787 if (poffset + maxsize > vp->v_filesize) {
788 if (poffset < vp->v_filesize) {
789 maxsize = vp->v_filesize - poffset;
790 ncount = btoc(maxsize);
795 if (ncount < count) {
796 for (i = ncount; i < count; i++) {
797 rtvals[i] = VM_PAGER_BAD;
803 * pageouts are already clustered, use IO_ASYNC to force a bawrite()
804 * rather then a bdwrite() to prevent paging I/O from saturating
805 * the buffer cache. Dummy-up the sequential heuristic to cause
806 * large ranges to cluster. If neither IO_SYNC or IO_ASYNC is set,
807 * the system decides how to cluster.
810 if (flags & (VM_PAGER_PUT_SYNC | VM_PAGER_PUT_INVAL))
812 else if ((flags & VM_PAGER_CLUSTER_OK) == 0)
814 ioflags |= (flags & VM_PAGER_PUT_INVAL) ? IO_INVAL: 0;
815 ioflags |= IO_SEQMAX << IO_SEQSHIFT;
817 aiov.iov_base = (caddr_t) 0;
818 aiov.iov_len = maxsize;
819 auio.uio_iov = &aiov;
821 auio.uio_offset = poffset;
822 auio.uio_segflg = UIO_NOCOPY;
823 auio.uio_rw = UIO_WRITE;
824 auio.uio_resid = maxsize;
826 error = VOP_WRITE(vp, &auio, ioflags, proc0.p_ucred);
827 mycpu->gd_cnt.v_vnodeout++;
828 mycpu->gd_cnt.v_vnodepgsout += ncount;
831 krateprintf(&vbadrate,
832 "vnode_pager_putpages: I/O error %d\n", error);
834 if (auio.uio_resid) {
835 krateprintf(&vresrate,
836 "vnode_pager_putpages: residual I/O %zd at %lu\n",
837 auio.uio_resid, (u_long)m[0]->pindex);
840 for (i = 0; i < ncount; i++) {
841 rtvals[i] = VM_PAGER_OK;
842 vm_page_undirty(m[i]);
849 * Run the chain and if the bottom-most object is a vnode-type lock the
850 * underlying vnode. A locked vnode or NULL is returned.
853 vnode_pager_lock(vm_object_t object)
855 struct vnode *vp = NULL;
863 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object));
866 while (lobject->type != OBJT_VNODE) {
867 if (lobject->flags & OBJ_DEAD)
869 tobject = lobject->backing_object;
872 vm_object_hold(tobject);
873 if (tobject == lobject->backing_object) {
874 if (lobject != object) {
875 vm_object_lock_swap();
876 vm_object_drop(lobject);
880 vm_object_drop(tobject);
883 while (lobject->type == OBJT_VNODE &&
884 (lobject->flags & OBJ_DEAD) == 0) {
888 vp = lobject->handle;
889 error = vget(vp, LK_SHARED | LK_RETRY | LK_CANRECURSE);
891 if (lobject->handle == vp)
895 kprintf("vnode_pager_lock: vp %p error %d "
896 "lockstatus %d, retrying\n",
898 lockstatus(&vp->v_lock, curthread));
899 tsleep(object->handle, 0, "vnpgrl", hz);
903 if (lobject != object)
904 vm_object_drop(lobject);