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);
180 object->handle = handle;
181 vp->v_object = object;
182 vp->v_filesize = length;
183 if (vp->v_mount && (vp->v_mount->mnt_kern_flag & MNTK_NOMSYNC))
184 vm_object_set_flag(object, OBJ_NOMSYNC);
187 if (object->size != lsize) {
188 kprintf("vnode_pager_alloc: Warning, objsize "
189 "mismatch %jd/%jd vp=%p obj=%p\n",
190 (intmax_t)object->size,
194 if (vp->v_filesize != length) {
195 kprintf("vnode_pager_alloc: Warning, filesize "
196 "mismatch %jd/%jd vp=%p obj=%p\n",
197 (intmax_t)vp->v_filesize,
204 lwkt_gettoken(&vp->v_token);
205 vclrflags(vp, VOLOCK);
206 if (vp->v_flag & VOWANT) {
207 vclrflags(vp, VOWANT);
210 lwkt_reltoken(&vp->v_token);
212 vm_object_drop(object);
218 * Add a ref to a vnode's existing VM object, return the object or
219 * NULL if the vnode did not have one. This does not create the
220 * object (we can't since we don't know what the proper blocksize/boff
221 * is to match the VFS's use of the buffer cache).
224 vnode_pager_reference(struct vnode *vp)
229 * Prevent race condition when allocating the object. This
230 * can happen with NFS vnodes since the nfsnode isn't locked.
232 * Serialize potential vnode/object teardowns and interlocks
234 lwkt_gettoken(&vp->v_token);
235 while (vp->v_flag & VOLOCK) {
236 vsetflags(vp, VOWANT);
237 tsleep(vp, 0, "vnpobj", 0);
239 vsetflags(vp, VOLOCK);
240 lwkt_reltoken(&vp->v_token);
243 * Prevent race conditions against deallocation of the VM
246 while ((object = vp->v_object) != NULL) {
247 vm_object_hold(object);
248 if ((object->flags & OBJ_DEAD) == 0)
250 vm_object_dead_sleep(object, "vadead");
251 vm_object_drop(object);
255 * The object is expected to exist, the caller will handle
256 * NULL returns if it does not.
263 lwkt_gettoken(&vp->v_token);
264 vclrflags(vp, VOLOCK);
265 if (vp->v_flag & VOWANT) {
266 vclrflags(vp, VOWANT);
269 lwkt_reltoken(&vp->v_token);
271 vm_object_drop(object);
277 vnode_pager_dealloc(vm_object_t object)
279 struct vnode *vp = object->handle;
282 panic("vnode_pager_dealloc: pager already dealloced");
284 vm_object_pip_wait(object, "vnpdea");
286 object->handle = NULL;
287 object->type = OBJT_DEAD;
289 vp->v_filesize = NOOFFSET;
290 vclrflags(vp, VTEXT | VOBJBUF);
291 swap_pager_freespace_all(object);
295 * Return whether the vnode pager has the requested page. Return the
296 * number of disk-contiguous pages before and after the requested page,
297 * not including the requested page.
300 vnode_pager_haspage(vm_object_t object, vm_pindex_t pindex)
302 struct vnode *vp = object->handle;
310 * If no vp or vp is doomed or marked transparent to VM, we do not
313 if ((vp == NULL) || (vp->v_flag & VRECLAIMED))
317 * If filesystem no longer mounted or offset beyond end of file we do
320 loffset = IDX_TO_OFF(pindex);
322 if (vp->v_mount == NULL || loffset >= vp->v_filesize)
325 bsize = vp->v_mount->mnt_stat.f_iosize;
326 voff = loffset % bsize;
331 * BMAP returns byte counts before and after, where after
332 * is inclusive of the base page. haspage must return page
333 * counts before and after where after does not include the
336 * BMAP is allowed to return a *after of 0 for backwards
337 * compatibility. The base page is still considered valid if
338 * no error is returned.
340 error = VOP_BMAP(vp, loffset - voff, &doffset, NULL, NULL, 0);
343 if (doffset == NOOFFSET)
349 * Lets the VM system know about a change in size for a file.
350 * We adjust our own internal size and flush any cached pages in
351 * the associated object that are affected by the size change.
353 * NOTE: This routine may be invoked as a result of a pager put
354 * operation (possibly at object termination time), so we must be careful.
356 * NOTE: vp->v_filesize is initialized to NOOFFSET (-1), be sure that
357 * we do not blow up on the case. nsize will always be >= 0, however.
360 vnode_pager_setsize(struct vnode *vp, vm_ooffset_t nsize)
362 vm_pindex_t nobjsize;
363 vm_pindex_t oobjsize;
366 while ((object = vp->v_object) != NULL) {
367 vm_object_hold(object);
368 if (vp->v_object == object)
370 vm_object_drop(object);
376 * Hasn't changed size
378 if (nsize == vp->v_filesize) {
379 vm_object_drop(object);
384 * Has changed size. Adjust the VM object's size and v_filesize
385 * before we start scanning pages to prevent new pages from being
386 * allocated during the scan.
388 nobjsize = OFF_TO_IDX(nsize + PAGE_MASK);
389 oobjsize = object->size;
390 object->size = nobjsize;
393 * File has shrunk. Toss any cached pages beyond the new EOF.
395 if (nsize < vp->v_filesize) {
396 vp->v_filesize = nsize;
397 if (nobjsize < oobjsize) {
398 vm_object_page_remove(object, nobjsize, oobjsize,
402 * This gets rid of garbage at the end of a page that is now
403 * only partially backed by the vnode. Since we are setting
404 * the entire page valid & clean after we are done we have
405 * to be sure that the portion of the page within the file
406 * bounds is already valid. If it isn't then making it
407 * valid would create a corrupt block.
409 if (nsize & PAGE_MASK) {
413 m = vm_page_lookup_busy_wait(object, OFF_TO_IDX(nsize),
417 int base = (int)nsize & PAGE_MASK;
418 int size = PAGE_SIZE - base;
420 struct lwbuf lwb_cache;
423 * Clear out partial-page garbage in case
424 * the page has been mapped.
426 * This is byte aligned.
428 lwb = lwbuf_alloc(m, &lwb_cache);
429 kva = lwbuf_kva(lwb);
430 bzero((caddr_t)kva + base, size);
434 * XXX work around SMP data integrity race
435 * by unmapping the page from user processes.
436 * The garbage we just cleared may be mapped
437 * to a user process running on another cpu
438 * and this code is not running through normal
439 * I/O channels which handle SMP issues for
440 * us, so unmap page to synchronize all cpus.
442 * XXX should vm_pager_unmap_page() have
445 vm_page_protect(m, VM_PROT_NONE);
448 * Clear out partial-page dirty bits. This
449 * has the side effect of setting the valid
450 * bits, but that is ok. There are a bunch
451 * of places in the VM system where we expected
452 * m->dirty == VM_PAGE_BITS_ALL. The file EOF
453 * case is one of them. If the page is still
454 * partially dirty, make it fully dirty.
456 * NOTE: We do not clear out the valid
457 * bits. This would prevent bogus_page
458 * replacement from working properly.
460 * NOTE: We do not want to clear the dirty
461 * bit for a partial DEV_BSIZE'd truncation!
462 * This is DEV_BSIZE aligned!
464 vm_page_clear_dirty_beg_nonincl(m, base, size);
466 m->dirty = VM_PAGE_BITS_ALL;
473 vp->v_filesize = nsize;
475 vm_object_drop(object);
479 * Release a page busied for a getpages operation. The page may have become
480 * wired (typically due to being used by the buffer cache) or otherwise been
481 * soft-busied and cannot be freed in that case. A held page can still be
485 vnode_pager_freepage(vm_page_t m)
487 if (m->busy || m->wire_count) {
496 * EOPNOTSUPP is no longer legal. For local media VFS's that do not
497 * implement their own VOP_GETPAGES, their VOP_GETPAGES should call to
498 * vnode_pager_generic_getpages() to implement the previous behaviour.
500 * All other FS's should use the bypass to get to the local media
501 * backing vp's VOP_GETPAGES.
504 vnode_pager_getpage(vm_object_t object, vm_page_t *mpp, int seqaccess)
510 rtval = VOP_GETPAGES(vp, mpp, PAGE_SIZE, 0, 0, seqaccess);
511 if (rtval == EOPNOTSUPP)
512 panic("vnode_pager: vfs's must implement vop_getpages\n");
517 * This is now called from local media FS's to operate against their
518 * own vnodes if they fail to implement VOP_GETPAGES.
520 * With all the caching local media devices do these days there is really
521 * very little point to attempting to restrict the I/O size to contiguous
522 * blocks on-disk, especially if our caller thinks we need all the specified
523 * pages. Just construct and issue a READ.
526 vnode_pager_generic_getpages(struct vnode *vp, vm_page_t *mpp, int bytecount,
527 int reqpage, int seqaccess)
538 * Do not do anything if the vnode is bad.
540 if (vp->v_mount == NULL)
544 * Calculate the number of pages. Since we are paging in whole
545 * pages, adjust bytecount to be an integral multiple of the page
546 * size. It will be clipped to the file EOF later on.
548 bytecount = round_page(bytecount);
549 count = bytecount / PAGE_SIZE;
552 * We could check m[reqpage]->valid here and shortcut the operation,
553 * but doing so breaks read-ahead. Instead assume that the VM
554 * system has already done at least the check, don't worry about
555 * any races, and issue the VOP_READ to allow read-ahead to function.
557 * This keeps the pipeline full for I/O bound sequentially scanned
563 * Discard pages past the file EOF. If the requested page is past
564 * the file EOF we just leave its valid bits set to 0, the caller
565 * expects to maintain ownership of the requested page. If the
566 * entire range is past file EOF discard everything and generate
569 foff = IDX_TO_OFF(mpp[0]->pindex);
570 if (foff >= vp->v_filesize) {
571 for (i = 0; i < count; i++) {
573 vnode_pager_freepage(mpp[i]);
575 return VM_PAGER_ERROR;
578 if (foff + bytecount > vp->v_filesize) {
579 bytecount = vp->v_filesize - foff;
580 i = round_page(bytecount) / PAGE_SIZE;
583 if (count != reqpage)
584 vnode_pager_freepage(mpp[count]);
589 * The size of the transfer is bytecount. bytecount will be an
590 * integral multiple of the page size unless it has been clipped
591 * to the file EOF. The transfer cannot exceed the file EOF.
593 * When dealing with real devices we must round-up to the device
596 if (vp->v_type == VBLK || vp->v_type == VCHR) {
597 int secmask = vp->v_rdev->si_bsize_phys - 1;
598 KASSERT(secmask < PAGE_SIZE, ("vnode_pager_generic_getpages: sector size %d too large\n", secmask + 1));
599 bytecount = (bytecount + secmask) & ~secmask;
603 * Severe hack to avoid deadlocks with the buffer cache
605 for (i = 0; i < count; ++i) {
606 vm_page_t mt = mpp[i];
608 vm_page_io_start(mt);
613 * Issue the I/O with some read-ahead if bytecount > PAGE_SIZE
617 ioflags |= IO_SEQMAX << IO_SEQSHIFT;
619 aiov.iov_base = NULL;
620 aiov.iov_len = bytecount;
621 auio.uio_iov = &aiov;
623 auio.uio_offset = foff;
624 auio.uio_segflg = UIO_NOCOPY;
625 auio.uio_rw = UIO_READ;
626 auio.uio_resid = bytecount;
628 mycpu->gd_cnt.v_vnodein++;
629 mycpu->gd_cnt.v_vnodepgsin += count;
631 error = VOP_READ(vp, &auio, ioflags, proc0.p_ucred);
634 * Severe hack to avoid deadlocks with the buffer cache
636 for (i = 0; i < count; ++i) {
637 vm_page_busy_wait(mpp[i], FALSE, "getpgs");
638 vm_page_io_finish(mpp[i]);
642 * Calculate the actual number of bytes read and clean up the
645 bytecount -= auio.uio_resid;
647 for (i = 0; i < count; ++i) {
648 vm_page_t mt = mpp[i];
651 if (error == 0 && mt->valid) {
652 if (mt->flags & PG_REFERENCED)
653 vm_page_activate(mt);
655 vm_page_deactivate(mt);
658 vnode_pager_freepage(mt);
660 } else if (mt->valid == 0) {
662 kprintf("page failed but no I/O error page "
663 "%p object %p pindex %d\n",
664 mt, mt->object, (int) mt->pindex);
665 /* whoops, something happened */
668 } else if (mt->valid != VM_PAGE_BITS_ALL) {
670 * Zero-extend the requested page if necessary (if
671 * the filesystem is using a small block size).
673 vm_page_zero_invalid(mt, TRUE);
677 kprintf("vnode_pager_getpage: I/O read error\n");
679 return (error ? VM_PAGER_ERROR : VM_PAGER_OK);
683 * EOPNOTSUPP is no longer legal. For local media VFS's that do not
684 * implement their own VOP_PUTPAGES, their VOP_PUTPAGES should call to
685 * vnode_pager_generic_putpages() to implement the previous behaviour.
687 * Caller has already cleared the pmap modified bits, if any.
689 * All other FS's should use the bypass to get to the local media
690 * backing vp's VOP_PUTPAGES.
693 vnode_pager_putpages(vm_object_t object, vm_page_t *m, int count,
694 boolean_t sync, int *rtvals)
698 int bytes = count * PAGE_SIZE;
701 * Force synchronous operation if we are extremely low on memory
702 * to prevent a low-memory deadlock. VOP operations often need to
703 * allocate more memory to initiate the I/O ( i.e. do a BMAP
704 * operation ). The swapper handles the case by limiting the amount
705 * of asynchronous I/O, but that sort of solution doesn't scale well
706 * for the vnode pager without a lot of work.
708 * Also, the backing vnode's iodone routine may not wake the pageout
709 * daemon up. This should be probably be addressed XXX.
712 if ((vmstats.v_free_count + vmstats.v_cache_count) <
713 vmstats.v_pageout_free_min) {
718 * Call device-specific putpages function
721 rtval = VOP_PUTPAGES(vp, m, bytes, sync, rtvals, 0);
722 if (rtval == EOPNOTSUPP) {
723 kprintf("vnode_pager: *** WARNING *** stale FS putpages\n");
724 rtval = vnode_pager_generic_putpages( vp, m, bytes, sync, rtvals);
730 * This is now called from local media FS's to operate against their
731 * own vnodes if they fail to implement VOP_PUTPAGES.
733 * This is typically called indirectly via the pageout daemon and
734 * clustering has already typically occured, so in general we ask the
735 * underlying filesystem to write the data out asynchronously rather
739 vnode_pager_generic_putpages(struct vnode *vp, vm_page_t *m, int bytecount,
740 int flags, int *rtvals)
744 int maxsize, ncount, count;
745 vm_ooffset_t poffset;
751 object = vp->v_object;
752 count = bytecount / PAGE_SIZE;
754 for (i = 0; i < count; i++)
755 rtvals[i] = VM_PAGER_AGAIN;
757 if ((int) m[0]->pindex < 0) {
758 kprintf("vnode_pager_putpages: attempt to write meta-data!!! -- 0x%lx(%x)\n",
759 (long)m[0]->pindex, m[0]->dirty);
760 rtvals[0] = VM_PAGER_BAD;
764 maxsize = count * PAGE_SIZE;
767 poffset = IDX_TO_OFF(m[0]->pindex);
770 * If the page-aligned write is larger then the actual file we
771 * have to invalidate pages occuring beyond the file EOF.
773 * If the file EOF resides in the middle of a page we still clear
774 * all of that page's dirty bits later on. If we didn't it would
775 * endlessly re-write.
777 * We do not under any circumstances truncate the valid bits, as
778 * this will screw up bogus page replacement.
780 * The caller has already read-protected the pages. The VFS must
781 * use the buffer cache to wrap the pages. The pages might not
782 * be immediately flushed by the buffer cache but once under its
783 * control the pages themselves can wind up being marked clean
784 * and their covering buffer cache buffer can be marked dirty.
786 if (poffset + maxsize > vp->v_filesize) {
787 if (poffset < vp->v_filesize) {
788 maxsize = vp->v_filesize - poffset;
789 ncount = btoc(maxsize);
794 if (ncount < count) {
795 for (i = ncount; i < count; i++) {
796 rtvals[i] = VM_PAGER_BAD;
802 * pageouts are already clustered, use IO_ASYNC to force a bawrite()
803 * rather then a bdwrite() to prevent paging I/O from saturating
804 * the buffer cache. Dummy-up the sequential heuristic to cause
805 * large ranges to cluster. If neither IO_SYNC or IO_ASYNC is set,
806 * the system decides how to cluster.
809 if (flags & (VM_PAGER_PUT_SYNC | VM_PAGER_PUT_INVAL))
811 else if ((flags & VM_PAGER_CLUSTER_OK) == 0)
813 ioflags |= (flags & VM_PAGER_PUT_INVAL) ? IO_INVAL: 0;
814 ioflags |= IO_SEQMAX << IO_SEQSHIFT;
816 aiov.iov_base = (caddr_t) 0;
817 aiov.iov_len = maxsize;
818 auio.uio_iov = &aiov;
820 auio.uio_offset = poffset;
821 auio.uio_segflg = UIO_NOCOPY;
822 auio.uio_rw = UIO_WRITE;
823 auio.uio_resid = maxsize;
825 error = VOP_WRITE(vp, &auio, ioflags, proc0.p_ucred);
826 mycpu->gd_cnt.v_vnodeout++;
827 mycpu->gd_cnt.v_vnodepgsout += ncount;
830 krateprintf(&vbadrate,
831 "vnode_pager_putpages: I/O error %d\n", error);
833 if (auio.uio_resid) {
834 krateprintf(&vresrate,
835 "vnode_pager_putpages: residual I/O %zd at %lu\n",
836 auio.uio_resid, (u_long)m[0]->pindex);
839 for (i = 0; i < ncount; i++) {
840 rtvals[i] = VM_PAGER_OK;
841 vm_page_undirty(m[i]);
848 * Run the chain and if the bottom-most object is a vnode-type lock the
849 * underlying vnode. A locked vnode or NULL is returned.
852 vnode_pager_lock(vm_object_t object)
854 struct vnode *vp = NULL;
862 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object));
865 while (lobject->type != OBJT_VNODE) {
866 if (lobject->flags & OBJ_DEAD)
868 tobject = lobject->backing_object;
871 vm_object_hold(tobject);
872 if (tobject == lobject->backing_object) {
873 if (lobject != object) {
874 vm_object_lock_swap();
875 vm_object_drop(lobject);
879 vm_object_drop(tobject);
882 while (lobject->type == OBJT_VNODE &&
883 (lobject->flags & OBJ_DEAD) == 0) {
887 vp = lobject->handle;
888 error = vget(vp, LK_SHARED | LK_RETRY | LK_CANRECURSE);
890 if (lobject->handle == vp)
894 kprintf("vnode_pager_lock: vp %p error %d "
895 "lockstatus %d, retrying\n",
897 lockstatus(&vp->v_lock, curthread));
898 tsleep(object->handle, 0, "vnpgrl", hz);
902 if (lobject != object)
903 vm_object_drop(lobject);