2 * SPDX-License-Identifier: BSD-4-Clause
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
46 * Page to/from files (vnodes).
51 * Implement VOP_GETPAGES/PUTPAGES interface for filesystems. Will
52 * greatly re-simplify the vnode_pager.
55 #include <sys/cdefs.h>
56 __FBSDID("$FreeBSD$");
60 #include <sys/param.h>
61 #include <sys/kernel.h>
62 #include <sys/systm.h>
63 #include <sys/sysctl.h>
65 #include <sys/vnode.h>
66 #include <sys/mount.h>
69 #include <sys/vmmeter.h>
71 #include <sys/limits.h>
73 #include <sys/refcount.h>
74 #include <sys/rwlock.h>
75 #include <sys/sf_buf.h>
76 #include <sys/domainset.h>
78 #include <machine/atomic.h>
81 #include <vm/vm_param.h>
82 #include <vm/vm_object.h>
83 #include <vm/vm_page.h>
84 #include <vm/vm_pager.h>
85 #include <vm/vm_map.h>
86 #include <vm/vnode_pager.h>
87 #include <vm/vm_extern.h>
90 static int vnode_pager_addr(struct vnode *vp, vm_ooffset_t address,
91 daddr_t *rtaddress, int *run);
92 static int vnode_pager_input_smlfs(vm_object_t object, vm_page_t m);
93 static int vnode_pager_input_old(vm_object_t object, vm_page_t m);
94 static void vnode_pager_dealloc(vm_object_t);
95 static int vnode_pager_getpages(vm_object_t, vm_page_t *, int, int *, int *);
96 static int vnode_pager_getpages_async(vm_object_t, vm_page_t *, int, int *,
97 int *, vop_getpages_iodone_t, void *);
98 static void vnode_pager_putpages(vm_object_t, vm_page_t *, int, int, int *);
99 static boolean_t vnode_pager_haspage(vm_object_t, vm_pindex_t, int *, int *);
100 static vm_object_t vnode_pager_alloc(void *, vm_ooffset_t, vm_prot_t,
101 vm_ooffset_t, struct ucred *cred);
102 static int vnode_pager_generic_getpages_done(struct buf *);
103 static void vnode_pager_generic_getpages_done_async(struct buf *);
104 static void vnode_pager_update_writecount(vm_object_t, vm_offset_t,
106 static void vnode_pager_release_writecount(vm_object_t, vm_offset_t,
109 struct pagerops vnodepagerops = {
110 .pgo_alloc = vnode_pager_alloc,
111 .pgo_dealloc = vnode_pager_dealloc,
112 .pgo_getpages = vnode_pager_getpages,
113 .pgo_getpages_async = vnode_pager_getpages_async,
114 .pgo_putpages = vnode_pager_putpages,
115 .pgo_haspage = vnode_pager_haspage,
116 .pgo_update_writecount = vnode_pager_update_writecount,
117 .pgo_release_writecount = vnode_pager_release_writecount,
120 static struct domainset *vnode_domainset = NULL;
122 SYSCTL_PROC(_debug, OID_AUTO, vnode_domainset,
123 CTLTYPE_STRING | CTLFLAG_MPSAFE | CTLFLAG_RW, &vnode_domainset, 0,
124 sysctl_handle_domainset, "A", "Default vnode NUMA policy");
127 SYSCTL_INT(_vm, OID_AUTO, vnode_pbufs, CTLFLAG_RDTUN | CTLFLAG_NOFETCH,
128 &nvnpbufs, 0, "number of physical buffers allocated for vnode pager");
130 static uma_zone_t vnode_pbuf_zone;
133 vnode_pager_init(void *dummy)
137 nvnpbufs = nswbuf * 2;
139 nvnpbufs = nswbuf / 2;
141 TUNABLE_INT_FETCH("vm.vnode_pbufs", &nvnpbufs);
142 vnode_pbuf_zone = pbuf_zsecond_create("vnpbuf", nvnpbufs);
144 SYSINIT(vnode_pager, SI_SUB_CPU, SI_ORDER_ANY, vnode_pager_init, NULL);
146 /* Create the VM system backing object for this vnode */
148 vnode_create_vobject(struct vnode *vp, off_t isize, struct thread *td)
151 vm_ooffset_t size = isize;
155 if (!vn_isdisk(vp) && vn_canvmio(vp) == FALSE)
158 object = vp->v_object;
164 size = IDX_TO_OFF(INT_MAX);
166 if (VOP_GETATTR(vp, &va, td->td_ucred))
172 object = vnode_pager_alloc(vp, size, 0, 0, td->td_ucred);
174 * Dereference the reference we just created. This assumes
175 * that the object is associated with the vp. We still have
176 * to serialize with vnode_pager_dealloc() for the last
177 * potential reference.
179 VM_OBJECT_RLOCK(object);
180 last = refcount_release(&object->ref_count);
181 VM_OBJECT_RUNLOCK(object);
185 KASSERT(vp->v_object != NULL, ("vnode_create_vobject: NULL object"));
191 vnode_destroy_vobject(struct vnode *vp)
193 struct vm_object *obj;
196 if (obj == NULL || obj->handle != vp)
198 ASSERT_VOP_ELOCKED(vp, "vnode_destroy_vobject");
199 VM_OBJECT_WLOCK(obj);
200 MPASS(obj->type == OBJT_VNODE);
201 umtx_shm_object_terminated(obj);
202 if (obj->ref_count == 0) {
203 KASSERT((obj->flags & OBJ_DEAD) == 0,
204 ("vnode_destroy_vobject: Terminating dead object"));
205 vm_object_set_flag(obj, OBJ_DEAD);
208 * Clean pages and flush buffers.
210 vm_object_page_clean(obj, 0, 0, OBJPC_SYNC);
211 VM_OBJECT_WUNLOCK(obj);
213 vinvalbuf(vp, V_SAVE, 0, 0);
215 BO_LOCK(&vp->v_bufobj);
216 vp->v_bufobj.bo_flag |= BO_DEAD;
217 BO_UNLOCK(&vp->v_bufobj);
219 VM_OBJECT_WLOCK(obj);
220 vm_object_terminate(obj);
223 * Woe to the process that tries to page now :-).
225 vm_pager_deallocate(obj);
226 VM_OBJECT_WUNLOCK(obj);
228 KASSERT(vp->v_object == NULL, ("vp %p obj %p", vp, vp->v_object));
232 * Allocate (or lookup) pager for a vnode.
233 * Handle is a vnode pointer.
236 vnode_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot,
237 vm_ooffset_t offset, struct ucred *cred)
243 * Pageout to vnode, no can do yet.
248 vp = (struct vnode *)handle;
249 ASSERT_VOP_LOCKED(vp, "vnode_pager_alloc");
250 VNPASS(vp->v_usecount > 0, vp);
252 object = vp->v_object;
254 if (object == NULL) {
256 * Add an object of the appropriate size
258 object = vm_object_allocate(OBJT_VNODE,
259 OFF_TO_IDX(round_page(size)));
261 object->un_pager.vnp.vnp_size = size;
262 object->un_pager.vnp.writemappings = 0;
263 object->domain.dr_policy = vnode_domainset;
264 object->handle = handle;
265 if ((vp->v_vflag & VV_VMSIZEVNLOCK) != 0) {
266 VM_OBJECT_WLOCK(object);
267 vm_object_set_flag(object, OBJ_SIZEVNLOCK);
268 VM_OBJECT_WUNLOCK(object);
271 if (vp->v_object != NULL) {
273 * Object has been created while we were allocating.
276 VM_OBJECT_WLOCK(object);
277 KASSERT(object->ref_count == 1,
278 ("leaked ref %p %d", object, object->ref_count));
279 object->type = OBJT_DEAD;
280 refcount_init(&object->ref_count, 0);
281 VM_OBJECT_WUNLOCK(object);
282 vm_object_destroy(object);
285 vp->v_object = object;
289 vm_object_reference(object);
290 #if VM_NRESERVLEVEL > 0
291 if ((object->flags & OBJ_COLORED) == 0) {
292 VM_OBJECT_WLOCK(object);
293 vm_object_color(object, 0);
294 VM_OBJECT_WUNLOCK(object);
302 * The object must be locked.
305 vnode_pager_dealloc(vm_object_t object)
312 panic("vnode_pager_dealloc: pager already dealloced");
314 VM_OBJECT_ASSERT_WLOCKED(object);
315 vm_object_pip_wait(object, "vnpdea");
316 refs = object->ref_count;
318 object->handle = NULL;
319 object->type = OBJT_DEAD;
320 ASSERT_VOP_ELOCKED(vp, "vnode_pager_dealloc");
321 if (object->un_pager.vnp.writemappings > 0) {
322 object->un_pager.vnp.writemappings = 0;
323 VOP_ADD_WRITECOUNT_CHECKED(vp, -1);
324 CTR3(KTR_VFS, "%s: vp %p v_writecount decreased to %d",
325 __func__, vp, vp->v_writecount);
331 * vm_map_entry_set_vnode_text() cannot reach this vnode by
332 * following object->handle. Clear all text references now.
333 * This also clears the transient references from
334 * kern_execve(), which is fine because dead_vnodeops uses nop
335 * for VOP_UNSET_TEXT().
337 if (vp->v_writecount < 0)
338 vp->v_writecount = 0;
340 VM_OBJECT_WUNLOCK(object);
343 VM_OBJECT_WLOCK(object);
347 vnode_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before,
350 struct vnode *vp = object->handle;
357 int pagesperblock, blocksperpage;
359 VM_OBJECT_ASSERT_LOCKED(object);
361 * If no vp or vp is doomed or marked transparent to VM, we do not
364 if (vp == NULL || VN_IS_DOOMED(vp))
367 * If the offset is beyond end of file we do
370 if (IDX_TO_OFF(pindex) >= object->un_pager.vnp.vnp_size)
373 bsize = vp->v_mount->mnt_stat.f_iosize;
374 pagesperblock = bsize / PAGE_SIZE;
376 if (pagesperblock > 0) {
377 reqblock = pindex / pagesperblock;
379 blocksperpage = (PAGE_SIZE / bsize);
380 reqblock = pindex * blocksperpage;
382 lockstate = VM_OBJECT_DROP(object);
383 err = VOP_BMAP(vp, reqblock, NULL, &bn, after, before);
384 VM_OBJECT_PICKUP(object, lockstate);
389 if (pagesperblock > 0) {
390 poff = pindex - (reqblock * pagesperblock);
392 *before *= pagesperblock;
397 * The BMAP vop can report a partial block in the
398 * 'after', but must not report blocks after EOF.
399 * Assert the latter, and truncate 'after' in case
402 KASSERT((reqblock + *after) * pagesperblock <
403 roundup2(object->size, pagesperblock),
404 ("%s: reqblock %jd after %d size %ju", __func__,
405 (intmax_t )reqblock, *after,
406 (uintmax_t )object->size));
407 *after *= pagesperblock;
408 *after += pagesperblock - (poff + 1);
409 if (pindex + *after >= object->size)
410 *after = object->size - 1 - pindex;
414 *before /= blocksperpage;
418 *after /= blocksperpage;
425 * Lets the VM system know about a change in size for a file.
426 * We adjust our own internal size and flush any cached pages in
427 * the associated object that are affected by the size change.
429 * Note: this routine may be invoked as a result of a pager put
430 * operation (possibly at object termination time), so we must be careful.
433 vnode_pager_setsize(struct vnode *vp, vm_ooffset_t nsize)
437 vm_pindex_t nobjsize;
439 if ((object = vp->v_object) == NULL)
441 #ifdef DEBUG_VFS_LOCKS
446 if (mp != NULL && (mp->mnt_kern_flag & MNTK_VMSETSIZE_BUG) == 0)
447 assert_vop_elocked(vp,
448 "vnode_pager_setsize and not locked vnode");
451 VM_OBJECT_WLOCK(object);
452 if (object->type == OBJT_DEAD) {
453 VM_OBJECT_WUNLOCK(object);
456 KASSERT(object->type == OBJT_VNODE,
457 ("not vnode-backed object %p", object));
458 if (nsize == object->un_pager.vnp.vnp_size) {
460 * Hasn't changed size
462 VM_OBJECT_WUNLOCK(object);
465 nobjsize = OFF_TO_IDX(nsize + PAGE_MASK);
466 if (nsize < object->un_pager.vnp.vnp_size) {
468 * File has shrunk. Toss any cached pages beyond the new EOF.
470 if (nobjsize < object->size)
471 vm_object_page_remove(object, nobjsize, object->size,
474 * this gets rid of garbage at the end of a page that is now
475 * only partially backed by the vnode.
477 * XXX for some reason (I don't know yet), if we take a
478 * completely invalid page and mark it partially valid
479 * it can screw up NFS reads, so we don't allow the case.
481 if (!(nsize & PAGE_MASK))
483 m = vm_page_grab(object, OFF_TO_IDX(nsize), VM_ALLOC_NOCREAT);
486 if (!vm_page_none_valid(m)) {
487 int base = (int)nsize & PAGE_MASK;
488 int size = PAGE_SIZE - base;
491 * Clear out partial-page garbage in case
492 * the page has been mapped.
494 pmap_zero_page_area(m, base, size);
497 * Update the valid bits to reflect the blocks that
498 * have been zeroed. Some of these valid bits may
499 * have already been set.
501 vm_page_set_valid_range(m, base, size);
504 * Round "base" to the next block boundary so that the
505 * dirty bit for a partially zeroed block is not
508 base = roundup2(base, DEV_BSIZE);
511 * Clear out partial-page dirty bits.
513 * note that we do not clear out the valid
514 * bits. This would prevent bogus_page
515 * replacement from working properly.
517 vm_page_clear_dirty(m, base, PAGE_SIZE - base);
522 #if defined(__powerpc__) && !defined(__powerpc64__)
523 object->un_pager.vnp.vnp_size = nsize;
525 atomic_store_64(&object->un_pager.vnp.vnp_size, nsize);
527 object->size = nobjsize;
528 VM_OBJECT_WUNLOCK(object);
532 * calculate the linear (byte) disk address of specified virtual
536 vnode_pager_addr(struct vnode *vp, vm_ooffset_t address, daddr_t *rtaddress,
544 if (VN_IS_DOOMED(vp))
547 bsize = vp->v_mount->mnt_stat.f_iosize;
548 vblock = address / bsize;
549 voffset = address % bsize;
551 err = VOP_BMAP(vp, vblock, NULL, rtaddress, run, NULL);
553 if (*rtaddress != -1)
554 *rtaddress += voffset / DEV_BSIZE;
557 *run *= bsize / PAGE_SIZE;
558 *run -= voffset / PAGE_SIZE;
566 * small block filesystem vnode pager input
569 vnode_pager_input_smlfs(vm_object_t object, vm_page_t m)
582 if (VN_IS_DOOMED(vp))
585 bsize = vp->v_mount->mnt_stat.f_iosize;
587 VOP_BMAP(vp, 0, &bo, 0, NULL, NULL);
589 sf = sf_buf_alloc(m, 0);
591 for (i = 0; i < PAGE_SIZE / bsize; i++) {
592 vm_ooffset_t address;
594 bits = vm_page_bits(i * bsize, bsize);
598 address = IDX_TO_OFF(m->pindex) + i * bsize;
599 if (address >= object->un_pager.vnp.vnp_size) {
602 error = vnode_pager_addr(vp, address, &fileaddr, NULL);
606 if (fileaddr != -1) {
607 bp = uma_zalloc(vnode_pbuf_zone, M_WAITOK);
609 /* build a minimal buffer header */
610 bp->b_iocmd = BIO_READ;
611 bp->b_iodone = bdone;
612 KASSERT(bp->b_rcred == NOCRED, ("leaking read ucred"));
613 KASSERT(bp->b_wcred == NOCRED, ("leaking write ucred"));
614 bp->b_rcred = crhold(curthread->td_ucred);
615 bp->b_wcred = crhold(curthread->td_ucred);
616 bp->b_data = (caddr_t)sf_buf_kva(sf) + i * bsize;
617 bp->b_blkno = fileaddr;
620 bp->b_bcount = bsize;
621 bp->b_bufsize = bsize;
622 bp->b_runningbufspace = bp->b_bufsize;
623 atomic_add_long(&runningbufspace, bp->b_runningbufspace);
626 bp->b_iooffset = dbtob(bp->b_blkno);
629 bwait(bp, PVM, "vnsrd");
631 if ((bp->b_ioflags & BIO_ERROR) != 0) {
632 KASSERT(bp->b_error != 0,
633 ("%s: buf error but b_error == 0\n", __func__));
638 * free the buffer header back to the swap buffer pool
642 uma_zfree(vnode_pbuf_zone, bp);
646 bzero((caddr_t)sf_buf_kva(sf) + i * bsize, bsize);
647 KASSERT((m->dirty & bits) == 0,
648 ("vnode_pager_input_smlfs: page %p is dirty", m));
649 vm_page_bits_set(m, &m->valid, bits);
653 return VM_PAGER_ERROR;
659 * old style vnode pager input routine
662 vnode_pager_input_old(vm_object_t object, vm_page_t m)
671 VM_OBJECT_ASSERT_WLOCKED(object);
675 * Return failure if beyond current EOF
677 if (IDX_TO_OFF(m->pindex) >= object->un_pager.vnp.vnp_size) {
681 if (IDX_TO_OFF(m->pindex) + size > object->un_pager.vnp.vnp_size)
682 size = object->un_pager.vnp.vnp_size - IDX_TO_OFF(m->pindex);
684 VM_OBJECT_WUNLOCK(object);
687 * Allocate a kernel virtual address and initialize so that
688 * we can use VOP_READ/WRITE routines.
690 sf = sf_buf_alloc(m, 0);
692 aiov.iov_base = (caddr_t)sf_buf_kva(sf);
694 auio.uio_iov = &aiov;
696 auio.uio_offset = IDX_TO_OFF(m->pindex);
697 auio.uio_segflg = UIO_SYSSPACE;
698 auio.uio_rw = UIO_READ;
699 auio.uio_resid = size;
700 auio.uio_td = curthread;
702 error = VOP_READ(vp, &auio, 0, curthread->td_ucred);
704 int count = size - auio.uio_resid;
708 else if (count != PAGE_SIZE)
709 bzero((caddr_t)sf_buf_kva(sf) + count,
714 VM_OBJECT_WLOCK(object);
716 KASSERT(m->dirty == 0, ("vnode_pager_input_old: page %p is dirty", m));
719 return error ? VM_PAGER_ERROR : VM_PAGER_OK;
723 * generic vnode pager input routine
727 * Local media VFS's that do not implement their own VOP_GETPAGES
728 * should have their VOP_GETPAGES call to vnode_pager_generic_getpages()
729 * to implement the previous behaviour.
731 * All other FS's should use the bypass to get to the local media
732 * backing vp's VOP_GETPAGES.
735 vnode_pager_getpages(vm_object_t object, vm_page_t *m, int count, int *rbehind,
741 /* Handle is stable with paging in progress. */
743 rtval = VOP_GETPAGES(vp, m, count, rbehind, rahead);
744 KASSERT(rtval != EOPNOTSUPP,
745 ("vnode_pager: FS getpages not implemented\n"));
750 vnode_pager_getpages_async(vm_object_t object, vm_page_t *m, int count,
751 int *rbehind, int *rahead, vop_getpages_iodone_t iodone, void *arg)
757 rtval = VOP_GETPAGES_ASYNC(vp, m, count, rbehind, rahead, iodone, arg);
758 KASSERT(rtval != EOPNOTSUPP,
759 ("vnode_pager: FS getpages_async not implemented\n"));
764 * The implementation of VOP_GETPAGES() and VOP_GETPAGES_ASYNC() for
765 * local filesystems, where partially valid pages can only occur at
769 vnode_pager_local_getpages(struct vop_getpages_args *ap)
772 return (vnode_pager_generic_getpages(ap->a_vp, ap->a_m, ap->a_count,
773 ap->a_rbehind, ap->a_rahead, NULL, NULL));
777 vnode_pager_local_getpages_async(struct vop_getpages_async_args *ap)
781 error = vnode_pager_generic_getpages(ap->a_vp, ap->a_m, ap->a_count,
782 ap->a_rbehind, ap->a_rahead, ap->a_iodone, ap->a_arg);
783 if (error != 0 && ap->a_iodone != NULL)
784 ap->a_iodone(ap->a_arg, ap->a_m, ap->a_count, error);
789 * This is now called from local media FS's to operate against their
790 * own vnodes if they fail to implement VOP_GETPAGES.
793 vnode_pager_generic_getpages(struct vnode *vp, vm_page_t *m, int count,
794 int *a_rbehind, int *a_rahead, vop_getpages_iodone_t iodone, void *arg)
803 int bsize, pagesperblock;
804 int error, before, after, rbehind, rahead, poff, i;
805 int bytecount, secmask;
807 KASSERT(vp->v_type != VCHR && vp->v_type != VBLK,
808 ("%s does not support devices", __func__));
810 if (VN_IS_DOOMED(vp))
811 return (VM_PAGER_BAD);
813 object = vp->v_object;
814 foff = IDX_TO_OFF(m[0]->pindex);
815 bsize = vp->v_mount->mnt_stat.f_iosize;
816 pagesperblock = bsize / PAGE_SIZE;
818 KASSERT(foff < object->un_pager.vnp.vnp_size,
819 ("%s: page %p offset beyond vp %p size", __func__, m[0], vp));
820 KASSERT(count <= nitems(bp->b_pages),
821 ("%s: requested %d pages", __func__, count));
824 * The last page has valid blocks. Invalid part can only
825 * exist at the end of file, and the page is made fully valid
826 * by zeroing in vm_pager_get_pages().
828 if (!vm_page_none_valid(m[count - 1]) && --count == 0) {
830 iodone(arg, m, 1, 0);
831 return (VM_PAGER_OK);
834 bp = uma_zalloc(vnode_pbuf_zone, M_WAITOK);
837 * Get the underlying device blocks for the file with VOP_BMAP().
838 * If the file system doesn't support VOP_BMAP, use old way of
839 * getting pages via VOP_READ.
841 error = VOP_BMAP(vp, foff / bsize, &bo, &bp->b_blkno, &after, &before);
842 if (error == EOPNOTSUPP) {
843 uma_zfree(vnode_pbuf_zone, bp);
844 VM_OBJECT_WLOCK(object);
845 for (i = 0; i < count; i++) {
846 VM_CNT_INC(v_vnodein);
847 VM_CNT_INC(v_vnodepgsin);
848 error = vnode_pager_input_old(object, m[i]);
852 VM_OBJECT_WUNLOCK(object);
854 } else if (error != 0) {
855 uma_zfree(vnode_pbuf_zone, bp);
856 return (VM_PAGER_ERROR);
860 * If the file system supports BMAP, but blocksize is smaller
861 * than a page size, then use special small filesystem code.
863 if (pagesperblock == 0) {
864 uma_zfree(vnode_pbuf_zone, bp);
865 for (i = 0; i < count; i++) {
866 VM_CNT_INC(v_vnodein);
867 VM_CNT_INC(v_vnodepgsin);
868 error = vnode_pager_input_smlfs(object, m[i]);
876 * A sparse file can be encountered only for a single page request,
877 * which may not be preceded by call to vm_pager_haspage().
879 if (bp->b_blkno == -1) {
881 ("%s: array[%d] request to a sparse file %p", __func__,
883 uma_zfree(vnode_pbuf_zone, bp);
884 pmap_zero_page(m[0]);
885 KASSERT(m[0]->dirty == 0, ("%s: page %p is dirty",
888 return (VM_PAGER_OK);
892 blkno0 = bp->b_blkno;
894 bp->b_blkno += (foff % bsize) / DEV_BSIZE;
896 /* Recalculate blocks available after/before to pages. */
897 poff = (foff % bsize) / PAGE_SIZE;
898 before *= pagesperblock;
900 after *= pagesperblock;
901 after += pagesperblock - (poff + 1);
902 if (m[0]->pindex + after >= object->size)
903 after = object->size - 1 - m[0]->pindex;
904 KASSERT(count <= after + 1, ("%s: %d pages asked, can do only %d",
905 __func__, count, after + 1));
908 /* Trim requested rbehind/rahead to possible values. */
909 rbehind = a_rbehind ? *a_rbehind : 0;
910 rahead = a_rahead ? *a_rahead : 0;
911 rbehind = min(rbehind, before);
912 rbehind = min(rbehind, m[0]->pindex);
913 rahead = min(rahead, after);
914 rahead = min(rahead, object->size - m[count - 1]->pindex);
916 * Check that total amount of pages fit into buf. Trim rbehind and
917 * rahead evenly if not.
919 if (rbehind + rahead + count > nitems(bp->b_pages)) {
922 trim = rbehind + rahead + count - nitems(bp->b_pages) + 1;
923 sum = rbehind + rahead;
924 if (rbehind == before) {
925 /* Roundup rbehind trim to block size. */
926 rbehind -= roundup(trim * rbehind / sum, pagesperblock);
930 rbehind -= trim * rbehind / sum;
931 rahead -= trim * rahead / sum;
933 KASSERT(rbehind + rahead + count <= nitems(bp->b_pages),
934 ("%s: behind %d ahead %d count %d", __func__,
935 rbehind, rahead, count));
938 * Fill in the bp->b_pages[] array with requested and optional
939 * read behind or read ahead pages. Read behind pages are looked
940 * up in a backward direction, down to a first cached page. Same
941 * for read ahead pages, but there is no need to shift the array
942 * in case of encountering a cached page.
944 i = bp->b_npages = 0;
946 vm_pindex_t startpindex, tpindex;
949 VM_OBJECT_WLOCK(object);
950 startpindex = m[0]->pindex - rbehind;
951 if ((p = TAILQ_PREV(m[0], pglist, listq)) != NULL &&
952 p->pindex >= startpindex)
953 startpindex = p->pindex + 1;
955 /* tpindex is unsigned; beware of numeric underflow. */
956 for (tpindex = m[0]->pindex - 1;
957 tpindex >= startpindex && tpindex < m[0]->pindex;
959 p = vm_page_alloc(object, tpindex, VM_ALLOC_NORMAL);
961 /* Shift the array. */
962 for (int j = 0; j < i; j++)
963 bp->b_pages[j] = bp->b_pages[j +
964 tpindex + 1 - startpindex];
967 bp->b_pages[tpindex - startpindex] = p;
972 bp->b_blkno -= IDX_TO_OFF(i) / DEV_BSIZE;
976 /* Requested pages. */
977 for (int j = 0; j < count; j++, i++)
978 bp->b_pages[i] = m[j];
979 bp->b_npages += count;
982 vm_pindex_t endpindex, tpindex;
985 if (!VM_OBJECT_WOWNED(object))
986 VM_OBJECT_WLOCK(object);
987 endpindex = m[count - 1]->pindex + rahead + 1;
988 if ((p = TAILQ_NEXT(m[count - 1], listq)) != NULL &&
989 p->pindex < endpindex)
990 endpindex = p->pindex;
991 if (endpindex > object->size)
992 endpindex = object->size;
994 for (tpindex = m[count - 1]->pindex + 1;
995 tpindex < endpindex; i++, tpindex++) {
996 p = vm_page_alloc(object, tpindex, VM_ALLOC_NORMAL);
1002 bp->b_pgafter = i - bp->b_npages;
1007 if (VM_OBJECT_WOWNED(object))
1008 VM_OBJECT_WUNLOCK(object);
1010 /* Report back actual behind/ahead read. */
1012 *a_rbehind = bp->b_pgbefore;
1014 *a_rahead = bp->b_pgafter;
1017 KASSERT(bp->b_npages <= nitems(bp->b_pages),
1018 ("%s: buf %p overflowed", __func__, bp));
1019 for (int j = 1, prev = 0; j < bp->b_npages; j++) {
1020 if (bp->b_pages[j] == bogus_page)
1022 KASSERT(bp->b_pages[j]->pindex - bp->b_pages[prev]->pindex ==
1023 j - prev, ("%s: pages array not consecutive, bp %p",
1030 * Recalculate first offset and bytecount with regards to read behind.
1031 * Truncate bytecount to vnode real size and round up physical size
1034 foff = IDX_TO_OFF(bp->b_pages[0]->pindex);
1035 bytecount = bp->b_npages << PAGE_SHIFT;
1036 if ((foff + bytecount) > object->un_pager.vnp.vnp_size)
1037 bytecount = object->un_pager.vnp.vnp_size - foff;
1038 secmask = bo->bo_bsize - 1;
1039 KASSERT(secmask < PAGE_SIZE && secmask > 0,
1040 ("%s: sector size %d too large", __func__, secmask + 1));
1041 bytecount = (bytecount + secmask) & ~secmask;
1044 * And map the pages to be read into the kva, if the filesystem
1045 * requires mapped buffers.
1047 if ((vp->v_mount->mnt_kern_flag & MNTK_UNMAPPED_BUFS) != 0 &&
1048 unmapped_buf_allowed) {
1049 bp->b_data = unmapped_buf;
1052 bp->b_data = bp->b_kvabase;
1053 pmap_qenter((vm_offset_t)bp->b_data, bp->b_pages, bp->b_npages);
1056 /* Build a minimal buffer header. */
1057 bp->b_iocmd = BIO_READ;
1058 KASSERT(bp->b_rcred == NOCRED, ("leaking read ucred"));
1059 KASSERT(bp->b_wcred == NOCRED, ("leaking write ucred"));
1060 bp->b_rcred = crhold(curthread->td_ucred);
1061 bp->b_wcred = crhold(curthread->td_ucred);
1064 bp->b_bcount = bp->b_bufsize = bp->b_runningbufspace = bytecount;
1065 bp->b_iooffset = dbtob(bp->b_blkno);
1066 KASSERT(IDX_TO_OFF(m[0]->pindex - bp->b_pages[0]->pindex) ==
1067 (blkno0 - bp->b_blkno) * DEV_BSIZE +
1068 IDX_TO_OFF(m[0]->pindex) % bsize,
1069 ("wrong offsets bsize %d m[0] %ju b_pages[0] %ju "
1070 "blkno0 %ju b_blkno %ju", bsize,
1071 (uintmax_t)m[0]->pindex, (uintmax_t)bp->b_pages[0]->pindex,
1072 (uintmax_t)blkno0, (uintmax_t)bp->b_blkno));
1074 atomic_add_long(&runningbufspace, bp->b_runningbufspace);
1075 VM_CNT_INC(v_vnodein);
1076 VM_CNT_ADD(v_vnodepgsin, bp->b_npages);
1078 if (iodone != NULL) { /* async */
1079 bp->b_pgiodone = iodone;
1080 bp->b_caller1 = arg;
1081 bp->b_iodone = vnode_pager_generic_getpages_done_async;
1082 bp->b_flags |= B_ASYNC;
1085 return (VM_PAGER_OK);
1087 bp->b_iodone = bdone;
1089 bwait(bp, PVM, "vnread");
1090 error = vnode_pager_generic_getpages_done(bp);
1091 for (i = 0; i < bp->b_npages; i++)
1092 bp->b_pages[i] = NULL;
1095 uma_zfree(vnode_pbuf_zone, bp);
1096 return (error != 0 ? VM_PAGER_ERROR : VM_PAGER_OK);
1101 vnode_pager_generic_getpages_done_async(struct buf *bp)
1105 error = vnode_pager_generic_getpages_done(bp);
1106 /* Run the iodone upon the requested range. */
1107 bp->b_pgiodone(bp->b_caller1, bp->b_pages + bp->b_pgbefore,
1108 bp->b_npages - bp->b_pgbefore - bp->b_pgafter, error);
1109 for (int i = 0; i < bp->b_npages; i++)
1110 bp->b_pages[i] = NULL;
1113 uma_zfree(vnode_pbuf_zone, bp);
1117 vnode_pager_generic_getpages_done(struct buf *bp)
1120 off_t tfoff, nextoff;
1123 KASSERT((bp->b_ioflags & BIO_ERROR) == 0 || bp->b_error != 0,
1124 ("%s: buf error but b_error == 0\n", __func__));
1125 error = (bp->b_ioflags & BIO_ERROR) != 0 ? bp->b_error : 0;
1126 object = bp->b_vp->v_object;
1128 if (error == 0 && bp->b_bcount != bp->b_npages * PAGE_SIZE) {
1129 if (!buf_mapped(bp)) {
1130 bp->b_data = bp->b_kvabase;
1131 pmap_qenter((vm_offset_t)bp->b_data, bp->b_pages,
1134 bzero(bp->b_data + bp->b_bcount,
1135 PAGE_SIZE * bp->b_npages - bp->b_bcount);
1137 if (buf_mapped(bp)) {
1138 pmap_qremove((vm_offset_t)bp->b_data, bp->b_npages);
1139 bp->b_data = unmapped_buf;
1143 * If the read failed, we must free any read ahead/behind pages here.
1144 * The requested pages are freed by the caller (for sync requests)
1145 * or by the bp->b_pgiodone callback (for async requests).
1148 VM_OBJECT_WLOCK(object);
1149 for (i = 0; i < bp->b_pgbefore; i++)
1150 vm_page_free_invalid(bp->b_pages[i]);
1151 for (i = bp->b_npages - bp->b_pgafter; i < bp->b_npages; i++)
1152 vm_page_free_invalid(bp->b_pages[i]);
1153 VM_OBJECT_WUNLOCK(object);
1157 /* Read lock to protect size. */
1158 VM_OBJECT_RLOCK(object);
1159 for (i = 0, tfoff = IDX_TO_OFF(bp->b_pages[0]->pindex);
1160 i < bp->b_npages; i++, tfoff = nextoff) {
1163 nextoff = tfoff + PAGE_SIZE;
1164 mt = bp->b_pages[i];
1165 if (mt == bogus_page)
1168 if (nextoff <= object->un_pager.vnp.vnp_size) {
1170 * Read filled up entire page.
1173 KASSERT(mt->dirty == 0,
1174 ("%s: page %p is dirty", __func__, mt));
1175 KASSERT(!pmap_page_is_mapped(mt),
1176 ("%s: page %p is mapped", __func__, mt));
1179 * Read did not fill up entire page.
1181 * Currently we do not set the entire page valid,
1182 * we just try to clear the piece that we couldn't
1185 vm_page_set_valid_range(mt, 0,
1186 object->un_pager.vnp.vnp_size - tfoff);
1187 KASSERT((mt->dirty & vm_page_bits(0,
1188 object->un_pager.vnp.vnp_size - tfoff)) == 0,
1189 ("%s: page %p is dirty", __func__, mt));
1192 if (i < bp->b_pgbefore || i >= bp->b_npages - bp->b_pgafter)
1193 vm_page_readahead_finish(mt);
1195 VM_OBJECT_RUNLOCK(object);
1201 * EOPNOTSUPP is no longer legal. For local media VFS's that do not
1202 * implement their own VOP_PUTPAGES, their VOP_PUTPAGES should call to
1203 * vnode_pager_generic_putpages() to implement the previous behaviour.
1205 * All other FS's should use the bypass to get to the local media
1206 * backing vp's VOP_PUTPAGES.
1209 vnode_pager_putpages(vm_object_t object, vm_page_t *m, int count,
1210 int flags, int *rtvals)
1214 int bytes = count * PAGE_SIZE;
1217 * Force synchronous operation if we are extremely low on memory
1218 * to prevent a low-memory deadlock. VOP operations often need to
1219 * allocate more memory to initiate the I/O ( i.e. do a BMAP
1220 * operation ). The swapper handles the case by limiting the amount
1221 * of asynchronous I/O, but that sort of solution doesn't scale well
1222 * for the vnode pager without a lot of work.
1224 * Also, the backing vnode's iodone routine may not wake the pageout
1225 * daemon up. This should be probably be addressed XXX.
1228 if (vm_page_count_min())
1229 flags |= VM_PAGER_PUT_SYNC;
1232 * Call device-specific putpages function
1234 vp = object->handle;
1235 VM_OBJECT_WUNLOCK(object);
1236 rtval = VOP_PUTPAGES(vp, m, bytes, flags, rtvals);
1237 KASSERT(rtval != EOPNOTSUPP,
1238 ("vnode_pager: stale FS putpages\n"));
1239 VM_OBJECT_WLOCK(object);
1243 vn_off2bidx(vm_ooffset_t offset)
1246 return ((offset & PAGE_MASK) / DEV_BSIZE);
1250 vn_dirty_blk(vm_page_t m, vm_ooffset_t offset)
1253 KASSERT(IDX_TO_OFF(m->pindex) <= offset &&
1254 offset < IDX_TO_OFF(m->pindex + 1),
1255 ("page %p pidx %ju offset %ju", m, (uintmax_t)m->pindex,
1256 (uintmax_t)offset));
1257 return ((m->dirty & ((vm_page_bits_t)1 << vn_off2bidx(offset))) != 0);
1261 * This is now called from local media FS's to operate against their
1262 * own vnodes if they fail to implement VOP_PUTPAGES.
1264 * This is typically called indirectly via the pageout daemon and
1265 * clustering has already typically occurred, so in general we ask the
1266 * underlying filesystem to write the data out asynchronously rather
1270 vnode_pager_generic_putpages(struct vnode *vp, vm_page_t *ma, int bytecount,
1271 int flags, int *rtvals)
1275 vm_ooffset_t maxblksz, next_offset, poffset, prev_offset;
1278 off_t prev_resid, wrsz;
1279 int count, error, i, maxsize, ncount, pgoff, ppscheck;
1281 static struct timeval lastfail;
1284 object = vp->v_object;
1285 count = bytecount / PAGE_SIZE;
1287 for (i = 0; i < count; i++)
1288 rtvals[i] = VM_PAGER_ERROR;
1290 if ((int64_t)ma[0]->pindex < 0) {
1291 printf("vnode_pager_generic_putpages: "
1292 "attempt to write meta-data 0x%jx(%lx)\n",
1293 (uintmax_t)ma[0]->pindex, (u_long)ma[0]->dirty);
1294 rtvals[0] = VM_PAGER_BAD;
1295 return (VM_PAGER_BAD);
1298 maxsize = count * PAGE_SIZE;
1301 poffset = IDX_TO_OFF(ma[0]->pindex);
1304 * If the page-aligned write is larger then the actual file we
1305 * have to invalidate pages occurring beyond the file EOF. However,
1306 * there is an edge case where a file may not be page-aligned where
1307 * the last page is partially invalid. In this case the filesystem
1308 * may not properly clear the dirty bits for the entire page (which
1309 * could be VM_PAGE_BITS_ALL due to the page having been mmap()d).
1310 * With the page busied we are free to fix up the dirty bits here.
1312 * We do not under any circumstances truncate the valid bits, as
1313 * this will screw up bogus page replacement.
1315 VM_OBJECT_RLOCK(object);
1316 if (maxsize + poffset > object->un_pager.vnp.vnp_size) {
1317 if (object->un_pager.vnp.vnp_size > poffset) {
1318 maxsize = object->un_pager.vnp.vnp_size - poffset;
1319 ncount = btoc(maxsize);
1320 if ((pgoff = (int)maxsize & PAGE_MASK) != 0) {
1321 pgoff = roundup2(pgoff, DEV_BSIZE);
1324 * If the page is busy and the following
1325 * conditions hold, then the page's dirty
1326 * field cannot be concurrently changed by a
1330 vm_page_assert_sbusied(m);
1331 KASSERT(!pmap_page_is_write_mapped(m),
1332 ("vnode_pager_generic_putpages: page %p is not read-only", m));
1333 MPASS(m->dirty != 0);
1334 vm_page_clear_dirty(m, pgoff, PAGE_SIZE -
1341 for (i = ncount; i < count; i++)
1342 rtvals[i] = VM_PAGER_BAD;
1344 VM_OBJECT_RUNLOCK(object);
1346 auio.uio_iov = &aiov;
1347 auio.uio_segflg = UIO_NOCOPY;
1348 auio.uio_rw = UIO_WRITE;
1350 maxblksz = roundup2(poffset + maxsize, DEV_BSIZE);
1352 for (prev_offset = poffset; prev_offset < maxblksz;) {
1353 /* Skip clean blocks. */
1354 for (in_hole = true; in_hole && prev_offset < maxblksz;) {
1355 m = ma[OFF_TO_IDX(prev_offset - poffset)];
1356 for (i = vn_off2bidx(prev_offset);
1357 i < sizeof(vm_page_bits_t) * NBBY &&
1358 prev_offset < maxblksz; i++) {
1359 if (vn_dirty_blk(m, prev_offset)) {
1363 prev_offset += DEV_BSIZE;
1369 /* Find longest run of dirty blocks. */
1370 for (next_offset = prev_offset; next_offset < maxblksz;) {
1371 m = ma[OFF_TO_IDX(next_offset - poffset)];
1372 for (i = vn_off2bidx(next_offset);
1373 i < sizeof(vm_page_bits_t) * NBBY &&
1374 next_offset < maxblksz; i++) {
1375 if (!vn_dirty_blk(m, next_offset))
1377 next_offset += DEV_BSIZE;
1381 if (next_offset > poffset + maxsize)
1382 next_offset = poffset + maxsize;
1385 * Getting here requires finding a dirty block in the
1386 * 'skip clean blocks' loop.
1388 MPASS(prev_offset < next_offset);
1390 aiov.iov_base = NULL;
1391 auio.uio_iovcnt = 1;
1392 auio.uio_offset = prev_offset;
1393 prev_resid = auio.uio_resid = aiov.iov_len = next_offset -
1395 error = VOP_WRITE(vp, &auio,
1396 vnode_pager_putpages_ioflags(flags), curthread->td_ucred);
1398 wrsz = prev_resid - auio.uio_resid;
1400 if (ppsratecheck(&lastfail, &curfail, 1) != 0) {
1401 vn_printf(vp, "vnode_pager_putpages: "
1402 "zero-length write at %ju resid %zd\n",
1403 auio.uio_offset, auio.uio_resid);
1408 /* Adjust the starting offset for next iteration. */
1409 prev_offset += wrsz;
1410 MPASS(auio.uio_offset == prev_offset);
1413 if (error != 0 && (ppscheck = ppsratecheck(&lastfail,
1415 vn_printf(vp, "vnode_pager_putpages: I/O error %d\n",
1417 if (auio.uio_resid != 0 && (ppscheck != 0 ||
1418 ppsratecheck(&lastfail, &curfail, 1) != 0))
1419 vn_printf(vp, "vnode_pager_putpages: residual I/O %zd "
1420 "at %ju\n", auio.uio_resid,
1421 (uintmax_t)ma[0]->pindex);
1422 if (error != 0 || auio.uio_resid != 0)
1426 /* Mark completely processed pages. */
1427 for (i = 0; i < OFF_TO_IDX(prev_offset - poffset); i++)
1428 rtvals[i] = VM_PAGER_OK;
1429 /* Mark partial EOF page. */
1430 if (prev_offset == poffset + maxsize && (prev_offset & PAGE_MASK) != 0)
1431 rtvals[i++] = VM_PAGER_OK;
1432 /* Unwritten pages in range, free bonus if the page is clean. */
1433 for (; i < ncount; i++)
1434 rtvals[i] = ma[i]->dirty == 0 ? VM_PAGER_OK : VM_PAGER_ERROR;
1435 VM_CNT_ADD(v_vnodepgsout, i);
1436 VM_CNT_INC(v_vnodeout);
1441 vnode_pager_putpages_ioflags(int pager_flags)
1446 * Pageouts are already clustered, use IO_ASYNC to force a
1447 * bawrite() rather then a bdwrite() to prevent paging I/O
1448 * from saturating the buffer cache. Dummy-up the sequential
1449 * heuristic to cause large ranges to cluster. If neither
1450 * IO_SYNC or IO_ASYNC is set, the system decides how to
1454 if ((pager_flags & (VM_PAGER_PUT_SYNC | VM_PAGER_PUT_INVAL)) != 0)
1456 else if ((pager_flags & VM_PAGER_CLUSTER_OK) == 0)
1457 ioflags |= IO_ASYNC;
1458 ioflags |= (pager_flags & VM_PAGER_PUT_INVAL) != 0 ? IO_INVAL: 0;
1459 ioflags |= (pager_flags & VM_PAGER_PUT_NOREUSE) != 0 ? IO_NOREUSE : 0;
1460 ioflags |= IO_SEQMAX << IO_SEQSHIFT;
1465 * vnode_pager_undirty_pages().
1467 * A helper to mark pages as clean after pageout that was possibly
1468 * done with a short write. The lpos argument specifies the page run
1469 * length in bytes, and the written argument specifies how many bytes
1470 * were actually written. eof is the offset past the last valid byte
1471 * in the vnode using the absolute file position of the first byte in
1472 * the run as the base from which it is computed.
1475 vnode_pager_undirty_pages(vm_page_t *ma, int *rtvals, int written, off_t eof,
1479 int i, pos, pos_devb;
1481 if (written == 0 && eof >= lpos)
1483 obj = ma[0]->object;
1484 for (i = 0, pos = 0; pos < written; i++, pos += PAGE_SIZE) {
1485 if (pos < trunc_page(written)) {
1486 rtvals[i] = VM_PAGER_OK;
1487 vm_page_undirty(ma[i]);
1489 /* Partially written page. */
1490 rtvals[i] = VM_PAGER_AGAIN;
1491 vm_page_clear_dirty(ma[i], 0, written & PAGE_MASK);
1494 if (eof >= lpos) /* avoid truncation */
1496 for (pos = eof, i = OFF_TO_IDX(trunc_page(pos)); pos < lpos; i++) {
1497 if (pos != trunc_page(pos)) {
1499 * The page contains the last valid byte in
1500 * the vnode, mark the rest of the page as
1501 * clean, potentially making the whole page
1504 pos_devb = roundup2(pos & PAGE_MASK, DEV_BSIZE);
1505 vm_page_clear_dirty(ma[i], pos_devb, PAGE_SIZE -
1509 * If the page was cleaned, report the pageout
1510 * on it as successful. msync() no longer
1511 * needs to write out the page, endlessly
1512 * creating write requests and dirty buffers.
1514 if (ma[i]->dirty == 0)
1515 rtvals[i] = VM_PAGER_OK;
1517 pos = round_page(pos);
1519 /* vm_pageout_flush() clears dirty */
1520 rtvals[i] = VM_PAGER_BAD;
1527 vnode_pager_update_writecount(vm_object_t object, vm_offset_t start,
1531 vm_ooffset_t old_wm;
1533 VM_OBJECT_WLOCK(object);
1534 if (object->type != OBJT_VNODE) {
1535 VM_OBJECT_WUNLOCK(object);
1538 old_wm = object->un_pager.vnp.writemappings;
1539 object->un_pager.vnp.writemappings += (vm_ooffset_t)end - start;
1540 vp = object->handle;
1541 if (old_wm == 0 && object->un_pager.vnp.writemappings != 0) {
1542 ASSERT_VOP_LOCKED(vp, "v_writecount inc");
1543 VOP_ADD_WRITECOUNT_CHECKED(vp, 1);
1544 CTR3(KTR_VFS, "%s: vp %p v_writecount increased to %d",
1545 __func__, vp, vp->v_writecount);
1546 } else if (old_wm != 0 && object->un_pager.vnp.writemappings == 0) {
1547 ASSERT_VOP_LOCKED(vp, "v_writecount dec");
1548 VOP_ADD_WRITECOUNT_CHECKED(vp, -1);
1549 CTR3(KTR_VFS, "%s: vp %p v_writecount decreased to %d",
1550 __func__, vp, vp->v_writecount);
1552 VM_OBJECT_WUNLOCK(object);
1556 vnode_pager_release_writecount(vm_object_t object, vm_offset_t start,
1563 VM_OBJECT_WLOCK(object);
1566 * First, recheck the object type to account for the race when
1567 * the vnode is reclaimed.
1569 if (object->type != OBJT_VNODE) {
1570 VM_OBJECT_WUNLOCK(object);
1575 * Optimize for the case when writemappings is not going to
1579 if (object->un_pager.vnp.writemappings != inc) {
1580 object->un_pager.vnp.writemappings -= inc;
1581 VM_OBJECT_WUNLOCK(object);
1585 vp = object->handle;
1587 VM_OBJECT_WUNLOCK(object);
1589 vn_start_write(vp, &mp, V_WAIT);
1590 vn_lock(vp, LK_SHARED | LK_RETRY);
1593 * Decrement the object's writemappings, by swapping the start
1594 * and end arguments for vnode_pager_update_writecount(). If
1595 * there was not a race with vnode reclaimation, then the
1596 * vnode's v_writecount is decremented.
1598 vnode_pager_update_writecount(object, end, start);
1602 vn_finished_write(mp);