/*- * SPDX-License-Identifier: BSD-4-Clause * * Copyright (c) 1990 University of Utah. * Copyright (c) 1991 The Regents of the University of California. * All rights reserved. * Copyright (c) 1993, 1994 John S. Dyson * Copyright (c) 1995, David Greenman * * This code is derived from software contributed to Berkeley by * the Systems Programming Group of the University of Utah Computer * Science Department. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed by the University of * California, Berkeley and its contributors. * 4. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * * from: @(#)vnode_pager.c 7.5 (Berkeley) 4/20/91 */ /* * Page to/from files (vnodes). */ /* * TODO: * Implement VOP_GETPAGES/PUTPAGES interface for filesystems. Will * greatly re-simplify the vnode_pager. */ #include __FBSDID("$FreeBSD$"); #include "opt_vm.h" #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include static int vnode_pager_addr(struct vnode *vp, vm_ooffset_t address, daddr_t *rtaddress, int *run); static int vnode_pager_input_smlfs(vm_object_t object, vm_page_t m); static int vnode_pager_input_old(vm_object_t object, vm_page_t m); static void vnode_pager_dealloc(vm_object_t); static int vnode_pager_getpages(vm_object_t, vm_page_t *, int, int *, int *); static int vnode_pager_getpages_async(vm_object_t, vm_page_t *, int, int *, int *, vop_getpages_iodone_t, void *); static void vnode_pager_putpages(vm_object_t, vm_page_t *, int, int, int *); static boolean_t vnode_pager_haspage(vm_object_t, vm_pindex_t, int *, int *); static vm_object_t vnode_pager_alloc(void *, vm_ooffset_t, vm_prot_t, vm_ooffset_t, struct ucred *cred); static int vnode_pager_generic_getpages_done(struct buf *); static void vnode_pager_generic_getpages_done_async(struct buf *); static void vnode_pager_update_writecount(vm_object_t, vm_offset_t, vm_offset_t); static void vnode_pager_release_writecount(vm_object_t, vm_offset_t, vm_offset_t); static void vnode_pager_getvp(vm_object_t, struct vnode **, bool *); const struct pagerops vnodepagerops = { .pgo_kvme_type = KVME_TYPE_VNODE, .pgo_alloc = vnode_pager_alloc, .pgo_dealloc = vnode_pager_dealloc, .pgo_getpages = vnode_pager_getpages, .pgo_getpages_async = vnode_pager_getpages_async, .pgo_putpages = vnode_pager_putpages, .pgo_haspage = vnode_pager_haspage, .pgo_update_writecount = vnode_pager_update_writecount, .pgo_release_writecount = vnode_pager_release_writecount, .pgo_set_writeable_dirty = vm_object_set_writeable_dirty_, .pgo_mightbedirty = vm_object_mightbedirty_, .pgo_getvp = vnode_pager_getvp, }; static struct domainset *vnode_domainset = NULL; SYSCTL_PROC(_debug, OID_AUTO, vnode_domainset, CTLTYPE_STRING | CTLFLAG_MPSAFE | CTLFLAG_RW, &vnode_domainset, 0, sysctl_handle_domainset, "A", "Default vnode NUMA policy"); static int nvnpbufs; SYSCTL_INT(_vm, OID_AUTO, vnode_pbufs, CTLFLAG_RDTUN | CTLFLAG_NOFETCH, &nvnpbufs, 0, "number of physical buffers allocated for vnode pager"); static uma_zone_t vnode_pbuf_zone; static void vnode_pager_init(void *dummy) { #ifdef __LP64__ nvnpbufs = nswbuf * 2; #else nvnpbufs = nswbuf / 2; #endif TUNABLE_INT_FETCH("vm.vnode_pbufs", &nvnpbufs); vnode_pbuf_zone = pbuf_zsecond_create("vnpbuf", nvnpbufs); } SYSINIT(vnode_pager, SI_SUB_CPU, SI_ORDER_ANY, vnode_pager_init, NULL); /* Create the VM system backing object for this vnode */ int vnode_create_vobject(struct vnode *vp, off_t isize, struct thread *td) { vm_object_t object; vm_ooffset_t size = isize; struct vattr va; bool last; if (!vn_isdisk(vp) && vn_canvmio(vp) == FALSE) return (0); object = vp->v_object; if (object != NULL) return (0); if (size == 0) { if (vn_isdisk(vp)) { size = IDX_TO_OFF(INT_MAX); } else { if (VOP_GETATTR(vp, &va, td->td_ucred)) return (0); size = va.va_size; } } object = vnode_pager_alloc(vp, size, 0, 0, td->td_ucred); /* * Dereference the reference we just created. This assumes * that the object is associated with the vp. We still have * to serialize with vnode_pager_dealloc() for the last * potential reference. */ VM_OBJECT_RLOCK(object); last = refcount_release(&object->ref_count); VM_OBJECT_RUNLOCK(object); if (last) vrele(vp); KASSERT(vp->v_object != NULL, ("vnode_create_vobject: NULL object")); return (0); } void vnode_destroy_vobject(struct vnode *vp) { struct vm_object *obj; obj = vp->v_object; if (obj == NULL || obj->handle != vp) return; ASSERT_VOP_ELOCKED(vp, "vnode_destroy_vobject"); VM_OBJECT_WLOCK(obj); MPASS(obj->type == OBJT_VNODE); umtx_shm_object_terminated(obj); if (obj->ref_count == 0) { KASSERT((obj->flags & OBJ_DEAD) == 0, ("vnode_destroy_vobject: Terminating dead object")); vm_object_set_flag(obj, OBJ_DEAD); /* * Clean pages and flush buffers. */ vm_object_page_clean(obj, 0, 0, OBJPC_SYNC); VM_OBJECT_WUNLOCK(obj); vinvalbuf(vp, V_SAVE, 0, 0); BO_LOCK(&vp->v_bufobj); vp->v_bufobj.bo_flag |= BO_DEAD; BO_UNLOCK(&vp->v_bufobj); VM_OBJECT_WLOCK(obj); vm_object_terminate(obj); } else { /* * Woe to the process that tries to page now :-). */ vm_pager_deallocate(obj); VM_OBJECT_WUNLOCK(obj); } KASSERT(vp->v_object == NULL, ("vp %p obj %p", vp, vp->v_object)); } /* * Allocate (or lookup) pager for a vnode. * Handle is a vnode pointer. */ vm_object_t vnode_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot, vm_ooffset_t offset, struct ucred *cred) { vm_object_t object; struct vnode *vp; /* * Pageout to vnode, no can do yet. */ if (handle == NULL) return (NULL); vp = (struct vnode *)handle; ASSERT_VOP_LOCKED(vp, "vnode_pager_alloc"); VNPASS(vp->v_usecount > 0, vp); retry: object = vp->v_object; if (object == NULL) { /* * Add an object of the appropriate size */ object = vm_object_allocate(OBJT_VNODE, OFF_TO_IDX(round_page(size))); object->un_pager.vnp.vnp_size = size; object->un_pager.vnp.writemappings = 0; object->domain.dr_policy = vnode_domainset; object->handle = handle; if ((vp->v_vflag & VV_VMSIZEVNLOCK) != 0) { VM_OBJECT_WLOCK(object); vm_object_set_flag(object, OBJ_SIZEVNLOCK); VM_OBJECT_WUNLOCK(object); } VI_LOCK(vp); if (vp->v_object != NULL) { /* * Object has been created while we were allocating. */ VI_UNLOCK(vp); VM_OBJECT_WLOCK(object); KASSERT(object->ref_count == 1, ("leaked ref %p %d", object, object->ref_count)); object->type = OBJT_DEAD; refcount_init(&object->ref_count, 0); VM_OBJECT_WUNLOCK(object); vm_object_destroy(object); goto retry; } vp->v_object = object; VI_UNLOCK(vp); vrefact(vp); } else { vm_object_reference(object); #if VM_NRESERVLEVEL > 0 if ((object->flags & OBJ_COLORED) == 0) { VM_OBJECT_WLOCK(object); vm_object_color(object, 0); VM_OBJECT_WUNLOCK(object); } #endif } return (object); } /* * The object must be locked. */ static void vnode_pager_dealloc(vm_object_t object) { struct vnode *vp; int refs; vp = object->handle; if (vp == NULL) panic("vnode_pager_dealloc: pager already dealloced"); VM_OBJECT_ASSERT_WLOCKED(object); vm_object_pip_wait(object, "vnpdea"); refs = object->ref_count; object->handle = NULL; object->type = OBJT_DEAD; ASSERT_VOP_ELOCKED(vp, "vnode_pager_dealloc"); if (object->un_pager.vnp.writemappings > 0) { object->un_pager.vnp.writemappings = 0; VOP_ADD_WRITECOUNT_CHECKED(vp, -1); CTR3(KTR_VFS, "%s: vp %p v_writecount decreased to %d", __func__, vp, vp->v_writecount); } vp->v_object = NULL; VI_LOCK(vp); /* * vm_map_entry_set_vnode_text() cannot reach this vnode by * following object->handle. Clear all text references now. * This also clears the transient references from * kern_execve(), which is fine because dead_vnodeops uses nop * for VOP_UNSET_TEXT(). */ if (vp->v_writecount < 0) vp->v_writecount = 0; VI_UNLOCK(vp); VM_OBJECT_WUNLOCK(object); if (refs > 0) vunref(vp); VM_OBJECT_WLOCK(object); } static boolean_t vnode_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before, int *after) { struct vnode *vp = object->handle; daddr_t bn; uintptr_t lockstate; int err; daddr_t reqblock; int poff; int bsize; int pagesperblock, blocksperpage; VM_OBJECT_ASSERT_LOCKED(object); /* * If no vp or vp is doomed or marked transparent to VM, we do not * have the page. */ if (vp == NULL || VN_IS_DOOMED(vp)) return FALSE; /* * If the offset is beyond end of file we do * not have the page. */ if (IDX_TO_OFF(pindex) >= object->un_pager.vnp.vnp_size) return FALSE; bsize = vp->v_mount->mnt_stat.f_iosize; pagesperblock = bsize / PAGE_SIZE; blocksperpage = 0; if (pagesperblock > 0) { reqblock = pindex / pagesperblock; } else { blocksperpage = (PAGE_SIZE / bsize); reqblock = pindex * blocksperpage; } lockstate = VM_OBJECT_DROP(object); err = VOP_BMAP(vp, reqblock, NULL, &bn, after, before); VM_OBJECT_PICKUP(object, lockstate); if (err) return TRUE; if (bn == -1) return FALSE; if (pagesperblock > 0) { poff = pindex - (reqblock * pagesperblock); if (before) { *before *= pagesperblock; *before += poff; } if (after) { /* * The BMAP vop can report a partial block in the * 'after', but must not report blocks after EOF. * Assert the latter, and truncate 'after' in case * of the former. */ KASSERT((reqblock + *after) * pagesperblock < roundup2(object->size, pagesperblock), ("%s: reqblock %jd after %d size %ju", __func__, (intmax_t )reqblock, *after, (uintmax_t )object->size)); *after *= pagesperblock; *after += pagesperblock - (poff + 1); if (pindex + *after >= object->size) *after = object->size - 1 - pindex; } } else { if (before) { *before /= blocksperpage; } if (after) { *after /= blocksperpage; } } return TRUE; } /* * Lets the VM system know about a change in size for a file. * We adjust our own internal size and flush any cached pages in * the associated object that are affected by the size change. * * Note: this routine may be invoked as a result of a pager put * operation (possibly at object termination time), so we must be careful. */ void vnode_pager_setsize(struct vnode *vp, vm_ooffset_t nsize) { vm_object_t object; vm_page_t m; vm_pindex_t nobjsize; if ((object = vp->v_object) == NULL) return; #ifdef DEBUG_VFS_LOCKS { struct mount *mp; mp = vp->v_mount; if (mp != NULL && (mp->mnt_kern_flag & MNTK_VMSETSIZE_BUG) == 0) assert_vop_elocked(vp, "vnode_pager_setsize and not locked vnode"); } #endif VM_OBJECT_WLOCK(object); if (object->type == OBJT_DEAD) { VM_OBJECT_WUNLOCK(object); return; } KASSERT(object->type == OBJT_VNODE, ("not vnode-backed object %p", object)); if (nsize == object->un_pager.vnp.vnp_size) { /* * Hasn't changed size */ VM_OBJECT_WUNLOCK(object); return; } nobjsize = OFF_TO_IDX(nsize + PAGE_MASK); if (nsize < object->un_pager.vnp.vnp_size) { /* * File has shrunk. Toss any cached pages beyond the new EOF. */ if (nobjsize < object->size) vm_object_page_remove(object, nobjsize, object->size, 0); /* * this gets rid of garbage at the end of a page that is now * only partially backed by the vnode. * * XXX for some reason (I don't know yet), if we take a * completely invalid page and mark it partially valid * it can screw up NFS reads, so we don't allow the case. */ if (!(nsize & PAGE_MASK)) goto out; m = vm_page_grab(object, OFF_TO_IDX(nsize), VM_ALLOC_NOCREAT); if (m == NULL) goto out; if (!vm_page_none_valid(m)) { int base = (int)nsize & PAGE_MASK; int size = PAGE_SIZE - base; /* * Clear out partial-page garbage in case * the page has been mapped. */ pmap_zero_page_area(m, base, size); /* * Update the valid bits to reflect the blocks that * have been zeroed. Some of these valid bits may * have already been set. */ vm_page_set_valid_range(m, base, size); /* * Round "base" to the next block boundary so that the * dirty bit for a partially zeroed block is not * cleared. */ base = roundup2(base, DEV_BSIZE); /* * Clear out partial-page dirty bits. * * note that we do not clear out the valid * bits. This would prevent bogus_page * replacement from working properly. */ vm_page_clear_dirty(m, base, PAGE_SIZE - base); } vm_page_xunbusy(m); } out: #if defined(__powerpc__) && !defined(__powerpc64__) object->un_pager.vnp.vnp_size = nsize; #else atomic_store_64(&object->un_pager.vnp.vnp_size, nsize); #endif object->size = nobjsize; VM_OBJECT_WUNLOCK(object); } /* * calculate the linear (byte) disk address of specified virtual * file address */ static int vnode_pager_addr(struct vnode *vp, vm_ooffset_t address, daddr_t *rtaddress, int *run) { int bsize; int err; daddr_t vblock; daddr_t voffset; if (VN_IS_DOOMED(vp)) return -1; bsize = vp->v_mount->mnt_stat.f_iosize; vblock = address / bsize; voffset = address % bsize; err = VOP_BMAP(vp, vblock, NULL, rtaddress, run, NULL); if (err == 0) { if (*rtaddress != -1) *rtaddress += voffset / DEV_BSIZE; if (run) { *run += 1; *run *= bsize / PAGE_SIZE; *run -= voffset / PAGE_SIZE; } } return (err); } /* * small block filesystem vnode pager input */ static int vnode_pager_input_smlfs(vm_object_t object, vm_page_t m) { struct vnode *vp; struct bufobj *bo; struct buf *bp; struct sf_buf *sf; daddr_t fileaddr; vm_offset_t bsize; vm_page_bits_t bits; int error, i; error = 0; vp = object->handle; if (VN_IS_DOOMED(vp)) return VM_PAGER_BAD; bsize = vp->v_mount->mnt_stat.f_iosize; VOP_BMAP(vp, 0, &bo, 0, NULL, NULL); sf = sf_buf_alloc(m, 0); for (i = 0; i < PAGE_SIZE / bsize; i++) { vm_ooffset_t address; bits = vm_page_bits(i * bsize, bsize); if (m->valid & bits) continue; address = IDX_TO_OFF(m->pindex) + i * bsize; if (address >= object->un_pager.vnp.vnp_size) { fileaddr = -1; } else { error = vnode_pager_addr(vp, address, &fileaddr, NULL); if (error) break; } if (fileaddr != -1) { bp = uma_zalloc(vnode_pbuf_zone, M_WAITOK); /* build a minimal buffer header */ bp->b_iocmd = BIO_READ; bp->b_iodone = bdone; KASSERT(bp->b_rcred == NOCRED, ("leaking read ucred")); KASSERT(bp->b_wcred == NOCRED, ("leaking write ucred")); bp->b_rcred = crhold(curthread->td_ucred); bp->b_wcred = crhold(curthread->td_ucred); bp->b_data = (caddr_t)sf_buf_kva(sf) + i * bsize; bp->b_blkno = fileaddr; pbgetbo(bo, bp); bp->b_vp = vp; bp->b_bcount = bsize; bp->b_bufsize = bsize; bp->b_runningbufspace = bp->b_bufsize; atomic_add_long(&runningbufspace, bp->b_runningbufspace); /* do the input */ bp->b_iooffset = dbtob(bp->b_blkno); bstrategy(bp); bwait(bp, PVM, "vnsrd"); if ((bp->b_ioflags & BIO_ERROR) != 0) { KASSERT(bp->b_error != 0, ("%s: buf error but b_error == 0\n", __func__)); error = bp->b_error; } /* * free the buffer header back to the swap buffer pool */ bp->b_vp = NULL; pbrelbo(bp); uma_zfree(vnode_pbuf_zone, bp); if (error) break; } else bzero((caddr_t)sf_buf_kva(sf) + i * bsize, bsize); KASSERT((m->dirty & bits) == 0, ("vnode_pager_input_smlfs: page %p is dirty", m)); vm_page_bits_set(m, &m->valid, bits); } sf_buf_free(sf); if (error) { return VM_PAGER_ERROR; } return VM_PAGER_OK; } /* * old style vnode pager input routine */ static int vnode_pager_input_old(vm_object_t object, vm_page_t m) { struct uio auio; struct iovec aiov; int error; int size; struct sf_buf *sf; struct vnode *vp; VM_OBJECT_ASSERT_WLOCKED(object); error = 0; /* * Return failure if beyond current EOF */ if (IDX_TO_OFF(m->pindex) >= object->un_pager.vnp.vnp_size) { return VM_PAGER_BAD; } else { size = PAGE_SIZE; if (IDX_TO_OFF(m->pindex) + size > object->un_pager.vnp.vnp_size) size = object->un_pager.vnp.vnp_size - IDX_TO_OFF(m->pindex); vp = object->handle; VM_OBJECT_WUNLOCK(object); /* * Allocate a kernel virtual address and initialize so that * we can use VOP_READ/WRITE routines. */ sf = sf_buf_alloc(m, 0); aiov.iov_base = (caddr_t)sf_buf_kva(sf); aiov.iov_len = size; auio.uio_iov = &aiov; auio.uio_iovcnt = 1; auio.uio_offset = IDX_TO_OFF(m->pindex); auio.uio_segflg = UIO_SYSSPACE; auio.uio_rw = UIO_READ; auio.uio_resid = size; auio.uio_td = curthread; error = VOP_READ(vp, &auio, 0, curthread->td_ucred); if (!error) { int count = size - auio.uio_resid; if (count == 0) error = EINVAL; else if (count != PAGE_SIZE) bzero((caddr_t)sf_buf_kva(sf) + count, PAGE_SIZE - count); } sf_buf_free(sf); VM_OBJECT_WLOCK(object); } KASSERT(m->dirty == 0, ("vnode_pager_input_old: page %p is dirty", m)); if (!error) vm_page_valid(m); return error ? VM_PAGER_ERROR : VM_PAGER_OK; } /* * generic vnode pager input routine */ /* * Local media VFS's that do not implement their own VOP_GETPAGES * should have their VOP_GETPAGES call to vnode_pager_generic_getpages() * to implement the previous behaviour. * * All other FS's should use the bypass to get to the local media * backing vp's VOP_GETPAGES. */ static int vnode_pager_getpages(vm_object_t object, vm_page_t *m, int count, int *rbehind, int *rahead) { struct vnode *vp; int rtval; /* Handle is stable with paging in progress. */ vp = object->handle; rtval = VOP_GETPAGES(vp, m, count, rbehind, rahead); KASSERT(rtval != EOPNOTSUPP, ("vnode_pager: FS getpages not implemented\n")); return rtval; } static int vnode_pager_getpages_async(vm_object_t object, vm_page_t *m, int count, int *rbehind, int *rahead, vop_getpages_iodone_t iodone, void *arg) { struct vnode *vp; int rtval; vp = object->handle; rtval = VOP_GETPAGES_ASYNC(vp, m, count, rbehind, rahead, iodone, arg); KASSERT(rtval != EOPNOTSUPP, ("vnode_pager: FS getpages_async not implemented\n")); return (rtval); } /* * The implementation of VOP_GETPAGES() and VOP_GETPAGES_ASYNC() for * local filesystems, where partially valid pages can only occur at * the end of file. */ int vnode_pager_local_getpages(struct vop_getpages_args *ap) { return (vnode_pager_generic_getpages(ap->a_vp, ap->a_m, ap->a_count, ap->a_rbehind, ap->a_rahead, NULL, NULL)); } int vnode_pager_local_getpages_async(struct vop_getpages_async_args *ap) { int error; error = vnode_pager_generic_getpages(ap->a_vp, ap->a_m, ap->a_count, ap->a_rbehind, ap->a_rahead, ap->a_iodone, ap->a_arg); if (error != 0 && ap->a_iodone != NULL) ap->a_iodone(ap->a_arg, ap->a_m, ap->a_count, error); return (error); } /* * This is now called from local media FS's to operate against their * own vnodes if they fail to implement VOP_GETPAGES. */ int vnode_pager_generic_getpages(struct vnode *vp, vm_page_t *m, int count, int *a_rbehind, int *a_rahead, vop_getpages_iodone_t iodone, void *arg) { vm_object_t object; struct bufobj *bo; struct buf *bp; off_t foff; #ifdef INVARIANTS off_t blkno0; #endif int bsize, pagesperblock; int error, before, after, rbehind, rahead, poff, i; int bytecount, secmask; KASSERT(vp->v_type != VCHR && vp->v_type != VBLK, ("%s does not support devices", __func__)); if (VN_IS_DOOMED(vp)) return (VM_PAGER_BAD); object = vp->v_object; foff = IDX_TO_OFF(m[0]->pindex); bsize = vp->v_mount->mnt_stat.f_iosize; pagesperblock = bsize / PAGE_SIZE; KASSERT(foff < object->un_pager.vnp.vnp_size, ("%s: page %p offset beyond vp %p size", __func__, m[0], vp)); KASSERT(count <= atop(maxphys), ("%s: requested %d pages", __func__, count)); /* * The last page has valid blocks. Invalid part can only * exist at the end of file, and the page is made fully valid * by zeroing in vm_pager_get_pages(). */ if (!vm_page_none_valid(m[count - 1]) && --count == 0) { if (iodone != NULL) iodone(arg, m, 1, 0); return (VM_PAGER_OK); } bp = uma_zalloc(vnode_pbuf_zone, M_WAITOK); MPASS((bp->b_flags & B_MAXPHYS) != 0); /* * Get the underlying device blocks for the file with VOP_BMAP(). * If the file system doesn't support VOP_BMAP, use old way of * getting pages via VOP_READ. */ error = VOP_BMAP(vp, foff / bsize, &bo, &bp->b_blkno, &after, &before); if (error == EOPNOTSUPP) { uma_zfree(vnode_pbuf_zone, bp); VM_OBJECT_WLOCK(object); for (i = 0; i < count; i++) { VM_CNT_INC(v_vnodein); VM_CNT_INC(v_vnodepgsin); error = vnode_pager_input_old(object, m[i]); if (error) break; } VM_OBJECT_WUNLOCK(object); return (error); } else if (error != 0) { uma_zfree(vnode_pbuf_zone, bp); return (VM_PAGER_ERROR); } /* * If the file system supports BMAP, but blocksize is smaller * than a page size, then use special small filesystem code. */ if (pagesperblock == 0) { uma_zfree(vnode_pbuf_zone, bp); for (i = 0; i < count; i++) { VM_CNT_INC(v_vnodein); VM_CNT_INC(v_vnodepgsin); error = vnode_pager_input_smlfs(object, m[i]); if (error) break; } return (error); } /* * A sparse file can be encountered only for a single page request, * which may not be preceded by call to vm_pager_haspage(). */ if (bp->b_blkno == -1) { KASSERT(count == 1, ("%s: array[%d] request to a sparse file %p", __func__, count, vp)); uma_zfree(vnode_pbuf_zone, bp); pmap_zero_page(m[0]); KASSERT(m[0]->dirty == 0, ("%s: page %p is dirty", __func__, m[0])); vm_page_valid(m[0]); return (VM_PAGER_OK); } #ifdef INVARIANTS blkno0 = bp->b_blkno; #endif bp->b_blkno += (foff % bsize) / DEV_BSIZE; /* Recalculate blocks available after/before to pages. */ poff = (foff % bsize) / PAGE_SIZE; before *= pagesperblock; before += poff; after *= pagesperblock; after += pagesperblock - (poff + 1); if (m[0]->pindex + after >= object->size) after = object->size - 1 - m[0]->pindex; KASSERT(count <= after + 1, ("%s: %d pages asked, can do only %d", __func__, count, after + 1)); after -= count - 1; /* Trim requested rbehind/rahead to possible values. */ rbehind = a_rbehind ? *a_rbehind : 0; rahead = a_rahead ? *a_rahead : 0; rbehind = min(rbehind, before); rbehind = min(rbehind, m[0]->pindex); rahead = min(rahead, after); rahead = min(rahead, object->size - m[count - 1]->pindex); /* * Check that total amount of pages fit into buf. Trim rbehind and * rahead evenly if not. */ if (rbehind + rahead + count > atop(maxphys)) { int trim, sum; trim = rbehind + rahead + count - atop(maxphys) + 1; sum = rbehind + rahead; if (rbehind == before) { /* Roundup rbehind trim to block size. */ rbehind -= roundup(trim * rbehind / sum, pagesperblock); if (rbehind < 0) rbehind = 0; } else rbehind -= trim * rbehind / sum; rahead -= trim * rahead / sum; } KASSERT(rbehind + rahead + count <= atop(maxphys), ("%s: behind %d ahead %d count %d maxphys %lu", __func__, rbehind, rahead, count, maxphys)); /* * Fill in the bp->b_pages[] array with requested and optional * read behind or read ahead pages. Read behind pages are looked * up in a backward direction, down to a first cached page. Same * for read ahead pages, but there is no need to shift the array * in case of encountering a cached page. */ i = bp->b_npages = 0; if (rbehind) { vm_pindex_t startpindex, tpindex; vm_page_t p; VM_OBJECT_WLOCK(object); startpindex = m[0]->pindex - rbehind; if ((p = TAILQ_PREV(m[0], pglist, listq)) != NULL && p->pindex >= startpindex) startpindex = p->pindex + 1; /* tpindex is unsigned; beware of numeric underflow. */ for (tpindex = m[0]->pindex - 1; tpindex >= startpindex && tpindex < m[0]->pindex; tpindex--, i++) { p = vm_page_alloc(object, tpindex, VM_ALLOC_NORMAL); if (p == NULL) { /* Shift the array. */ for (int j = 0; j < i; j++) bp->b_pages[j] = bp->b_pages[j + tpindex + 1 - startpindex]; break; } bp->b_pages[tpindex - startpindex] = p; } bp->b_pgbefore = i; bp->b_npages += i; bp->b_blkno -= IDX_TO_OFF(i) / DEV_BSIZE; } else bp->b_pgbefore = 0; /* Requested pages. */ for (int j = 0; j < count; j++, i++) bp->b_pages[i] = m[j]; bp->b_npages += count; if (rahead) { vm_pindex_t endpindex, tpindex; vm_page_t p; if (!VM_OBJECT_WOWNED(object)) VM_OBJECT_WLOCK(object); endpindex = m[count - 1]->pindex + rahead + 1; if ((p = TAILQ_NEXT(m[count - 1], listq)) != NULL && p->pindex < endpindex) endpindex = p->pindex; if (endpindex > object->size) endpindex = object->size; for (tpindex = m[count - 1]->pindex + 1; tpindex < endpindex; i++, tpindex++) { p = vm_page_alloc(object, tpindex, VM_ALLOC_NORMAL); if (p == NULL) break; bp->b_pages[i] = p; } bp->b_pgafter = i - bp->b_npages; bp->b_npages = i; } else bp->b_pgafter = 0; if (VM_OBJECT_WOWNED(object)) VM_OBJECT_WUNLOCK(object); /* Report back actual behind/ahead read. */ if (a_rbehind) *a_rbehind = bp->b_pgbefore; if (a_rahead) *a_rahead = bp->b_pgafter; #ifdef INVARIANTS KASSERT(bp->b_npages <= atop(maxphys), ("%s: buf %p overflowed", __func__, bp)); for (int j = 1, prev = 0; j < bp->b_npages; j++) { if (bp->b_pages[j] == bogus_page) continue; KASSERT(bp->b_pages[j]->pindex - bp->b_pages[prev]->pindex == j - prev, ("%s: pages array not consecutive, bp %p", __func__, bp)); prev = j; } #endif /* * Recalculate first offset and bytecount with regards to read behind. * Truncate bytecount to vnode real size and round up physical size * for real devices. */ foff = IDX_TO_OFF(bp->b_pages[0]->pindex); bytecount = bp->b_npages << PAGE_SHIFT; if ((foff + bytecount) > object->un_pager.vnp.vnp_size) bytecount = object->un_pager.vnp.vnp_size - foff; secmask = bo->bo_bsize - 1; KASSERT(secmask < PAGE_SIZE && secmask > 0, ("%s: sector size %d too large", __func__, secmask + 1)); bytecount = (bytecount + secmask) & ~secmask; /* * And map the pages to be read into the kva, if the filesystem * requires mapped buffers. */ if ((vp->v_mount->mnt_kern_flag & MNTK_UNMAPPED_BUFS) != 0 && unmapped_buf_allowed) { bp->b_data = unmapped_buf; bp->b_offset = 0; } else { bp->b_data = bp->b_kvabase; pmap_qenter((vm_offset_t)bp->b_data, bp->b_pages, bp->b_npages); } /* Build a minimal buffer header. */ bp->b_iocmd = BIO_READ; KASSERT(bp->b_rcred == NOCRED, ("leaking read ucred")); KASSERT(bp->b_wcred == NOCRED, ("leaking write ucred")); bp->b_rcred = crhold(curthread->td_ucred); bp->b_wcred = crhold(curthread->td_ucred); pbgetbo(bo, bp); bp->b_vp = vp; bp->b_bcount = bp->b_bufsize = bp->b_runningbufspace = bytecount; bp->b_iooffset = dbtob(bp->b_blkno); KASSERT(IDX_TO_OFF(m[0]->pindex - bp->b_pages[0]->pindex) == (blkno0 - bp->b_blkno) * DEV_BSIZE + IDX_TO_OFF(m[0]->pindex) % bsize, ("wrong offsets bsize %d m[0] %ju b_pages[0] %ju " "blkno0 %ju b_blkno %ju", bsize, (uintmax_t)m[0]->pindex, (uintmax_t)bp->b_pages[0]->pindex, (uintmax_t)blkno0, (uintmax_t)bp->b_blkno)); atomic_add_long(&runningbufspace, bp->b_runningbufspace); VM_CNT_INC(v_vnodein); VM_CNT_ADD(v_vnodepgsin, bp->b_npages); if (iodone != NULL) { /* async */ bp->b_pgiodone = iodone; bp->b_caller1 = arg; bp->b_iodone = vnode_pager_generic_getpages_done_async; bp->b_flags |= B_ASYNC; BUF_KERNPROC(bp); bstrategy(bp); return (VM_PAGER_OK); } else { bp->b_iodone = bdone; bstrategy(bp); bwait(bp, PVM, "vnread"); error = vnode_pager_generic_getpages_done(bp); for (i = 0; i < bp->b_npages; i++) bp->b_pages[i] = NULL; bp->b_vp = NULL; pbrelbo(bp); uma_zfree(vnode_pbuf_zone, bp); return (error != 0 ? VM_PAGER_ERROR : VM_PAGER_OK); } } static void vnode_pager_generic_getpages_done_async(struct buf *bp) { int error; error = vnode_pager_generic_getpages_done(bp); /* Run the iodone upon the requested range. */ bp->b_pgiodone(bp->b_caller1, bp->b_pages + bp->b_pgbefore, bp->b_npages - bp->b_pgbefore - bp->b_pgafter, error); for (int i = 0; i < bp->b_npages; i++) bp->b_pages[i] = NULL; bp->b_vp = NULL; pbrelbo(bp); uma_zfree(vnode_pbuf_zone, bp); } static int vnode_pager_generic_getpages_done(struct buf *bp) { vm_object_t object; off_t tfoff, nextoff; int i, error; KASSERT((bp->b_ioflags & BIO_ERROR) == 0 || bp->b_error != 0, ("%s: buf error but b_error == 0\n", __func__)); error = (bp->b_ioflags & BIO_ERROR) != 0 ? bp->b_error : 0; object = bp->b_vp->v_object; if (error == 0 && bp->b_bcount != bp->b_npages * PAGE_SIZE) { if (!buf_mapped(bp)) { bp->b_data = bp->b_kvabase; pmap_qenter((vm_offset_t)bp->b_data, bp->b_pages, bp->b_npages); } bzero(bp->b_data + bp->b_bcount, PAGE_SIZE * bp->b_npages - bp->b_bcount); } if (buf_mapped(bp)) { pmap_qremove((vm_offset_t)bp->b_data, bp->b_npages); bp->b_data = unmapped_buf; } /* * If the read failed, we must free any read ahead/behind pages here. * The requested pages are freed by the caller (for sync requests) * or by the bp->b_pgiodone callback (for async requests). */ if (error != 0) { VM_OBJECT_WLOCK(object); for (i = 0; i < bp->b_pgbefore; i++) vm_page_free_invalid(bp->b_pages[i]); for (i = bp->b_npages - bp->b_pgafter; i < bp->b_npages; i++) vm_page_free_invalid(bp->b_pages[i]); VM_OBJECT_WUNLOCK(object); return (error); } /* Read lock to protect size. */ VM_OBJECT_RLOCK(object); for (i = 0, tfoff = IDX_TO_OFF(bp->b_pages[0]->pindex); i < bp->b_npages; i++, tfoff = nextoff) { vm_page_t mt; nextoff = tfoff + PAGE_SIZE; mt = bp->b_pages[i]; if (mt == bogus_page) continue; if (nextoff <= object->un_pager.vnp.vnp_size) { /* * Read filled up entire page. */ vm_page_valid(mt); KASSERT(mt->dirty == 0, ("%s: page %p is dirty", __func__, mt)); KASSERT(!pmap_page_is_mapped(mt), ("%s: page %p is mapped", __func__, mt)); } else { /* * Read did not fill up entire page. * * Currently we do not set the entire page valid, * we just try to clear the piece that we couldn't * read. */ vm_page_set_valid_range(mt, 0, object->un_pager.vnp.vnp_size - tfoff); KASSERT((mt->dirty & vm_page_bits(0, object->un_pager.vnp.vnp_size - tfoff)) == 0, ("%s: page %p is dirty", __func__, mt)); } if (i < bp->b_pgbefore || i >= bp->b_npages - bp->b_pgafter) vm_page_readahead_finish(mt); } VM_OBJECT_RUNLOCK(object); return (error); } /* * EOPNOTSUPP is no longer legal. For local media VFS's that do not * implement their own VOP_PUTPAGES, their VOP_PUTPAGES should call to * vnode_pager_generic_putpages() to implement the previous behaviour. * * All other FS's should use the bypass to get to the local media * backing vp's VOP_PUTPAGES. */ static void vnode_pager_putpages(vm_object_t object, vm_page_t *m, int count, int flags, int *rtvals) { int rtval; struct vnode *vp; int bytes = count * PAGE_SIZE; /* * Force synchronous operation if we are extremely low on memory * to prevent a low-memory deadlock. VOP operations often need to * allocate more memory to initiate the I/O ( i.e. do a BMAP * operation ). The swapper handles the case by limiting the amount * of asynchronous I/O, but that sort of solution doesn't scale well * for the vnode pager without a lot of work. * * Also, the backing vnode's iodone routine may not wake the pageout * daemon up. This should be probably be addressed XXX. */ if (vm_page_count_min()) flags |= VM_PAGER_PUT_SYNC; /* * Call device-specific putpages function */ vp = object->handle; VM_OBJECT_WUNLOCK(object); rtval = VOP_PUTPAGES(vp, m, bytes, flags, rtvals); KASSERT(rtval != EOPNOTSUPP, ("vnode_pager: stale FS putpages\n")); VM_OBJECT_WLOCK(object); } static int vn_off2bidx(vm_ooffset_t offset) { return ((offset & PAGE_MASK) / DEV_BSIZE); } static bool vn_dirty_blk(vm_page_t m, vm_ooffset_t offset) { KASSERT(IDX_TO_OFF(m->pindex) <= offset && offset < IDX_TO_OFF(m->pindex + 1), ("page %p pidx %ju offset %ju", m, (uintmax_t)m->pindex, (uintmax_t)offset)); return ((m->dirty & ((vm_page_bits_t)1 << vn_off2bidx(offset))) != 0); } /* * This is now called from local media FS's to operate against their * own vnodes if they fail to implement VOP_PUTPAGES. * * This is typically called indirectly via the pageout daemon and * clustering has already typically occurred, so in general we ask the * underlying filesystem to write the data out asynchronously rather * then delayed. */ int vnode_pager_generic_putpages(struct vnode *vp, vm_page_t *ma, int bytecount, int flags, int *rtvals) { vm_object_t object; vm_page_t m; vm_ooffset_t maxblksz, next_offset, poffset, prev_offset; struct uio auio; struct iovec aiov; off_t prev_resid, wrsz; int count, error, i, maxsize, ncount, pgoff, ppscheck; bool in_hole; static struct timeval lastfail; static int curfail; object = vp->v_object; count = bytecount / PAGE_SIZE; for (i = 0; i < count; i++) rtvals[i] = VM_PAGER_ERROR; if ((int64_t)ma[0]->pindex < 0) { printf("vnode_pager_generic_putpages: " "attempt to write meta-data 0x%jx(%lx)\n", (uintmax_t)ma[0]->pindex, (u_long)ma[0]->dirty); rtvals[0] = VM_PAGER_BAD; return (VM_PAGER_BAD); } maxsize = count * PAGE_SIZE; ncount = count; poffset = IDX_TO_OFF(ma[0]->pindex); /* * If the page-aligned write is larger then the actual file we * have to invalidate pages occurring beyond the file EOF. However, * there is an edge case where a file may not be page-aligned where * the last page is partially invalid. In this case the filesystem * may not properly clear the dirty bits for the entire page (which * could be VM_PAGE_BITS_ALL due to the page having been mmap()d). * With the page busied we are free to fix up the dirty bits here. * * We do not under any circumstances truncate the valid bits, as * this will screw up bogus page replacement. */ VM_OBJECT_RLOCK(object); if (maxsize + poffset > object->un_pager.vnp.vnp_size) { if (object->un_pager.vnp.vnp_size > poffset) { maxsize = object->un_pager.vnp.vnp_size - poffset; ncount = btoc(maxsize); if ((pgoff = (int)maxsize & PAGE_MASK) != 0) { pgoff = roundup2(pgoff, DEV_BSIZE); /* * If the page is busy and the following * conditions hold, then the page's dirty * field cannot be concurrently changed by a * pmap operation. */ m = ma[ncount - 1]; vm_page_assert_sbusied(m); KASSERT(!pmap_page_is_write_mapped(m), ("vnode_pager_generic_putpages: page %p is not read-only", m)); MPASS(m->dirty != 0); vm_page_clear_dirty(m, pgoff, PAGE_SIZE - pgoff); } } else { maxsize = 0; ncount = 0; } for (i = ncount; i < count; i++) rtvals[i] = VM_PAGER_BAD; } VM_OBJECT_RUNLOCK(object); auio.uio_iov = &aiov; auio.uio_segflg = UIO_NOCOPY; auio.uio_rw = UIO_WRITE; auio.uio_td = NULL; maxblksz = roundup2(poffset + maxsize, DEV_BSIZE); for (prev_offset = poffset; prev_offset < maxblksz;) { /* Skip clean blocks. */ for (in_hole = true; in_hole && prev_offset < maxblksz;) { m = ma[OFF_TO_IDX(prev_offset - poffset)]; for (i = vn_off2bidx(prev_offset); i < sizeof(vm_page_bits_t) * NBBY && prev_offset < maxblksz; i++) { if (vn_dirty_blk(m, prev_offset)) { in_hole = false; break; } prev_offset += DEV_BSIZE; } } if (in_hole) goto write_done; /* Find longest run of dirty blocks. */ for (next_offset = prev_offset; next_offset < maxblksz;) { m = ma[OFF_TO_IDX(next_offset - poffset)]; for (i = vn_off2bidx(next_offset); i < sizeof(vm_page_bits_t) * NBBY && next_offset < maxblksz; i++) { if (!vn_dirty_blk(m, next_offset)) goto start_write; next_offset += DEV_BSIZE; } } start_write: if (next_offset > poffset + maxsize) next_offset = poffset + maxsize; /* * Getting here requires finding a dirty block in the * 'skip clean blocks' loop. */ MPASS(prev_offset < next_offset); aiov.iov_base = NULL; auio.uio_iovcnt = 1; auio.uio_offset = prev_offset; prev_resid = auio.uio_resid = aiov.iov_len = next_offset - prev_offset; error = VOP_WRITE(vp, &auio, vnode_pager_putpages_ioflags(flags), curthread->td_ucred); wrsz = prev_resid - auio.uio_resid; if (wrsz == 0) { if (ppsratecheck(&lastfail, &curfail, 1) != 0) { vn_printf(vp, "vnode_pager_putpages: " "zero-length write at %ju resid %zd\n", auio.uio_offset, auio.uio_resid); } break; } /* Adjust the starting offset for next iteration. */ prev_offset += wrsz; MPASS(auio.uio_offset == prev_offset); ppscheck = 0; if (error != 0 && (ppscheck = ppsratecheck(&lastfail, &curfail, 1)) != 0) vn_printf(vp, "vnode_pager_putpages: I/O error %d\n", error); if (auio.uio_resid != 0 && (ppscheck != 0 || ppsratecheck(&lastfail, &curfail, 1) != 0)) vn_printf(vp, "vnode_pager_putpages: residual I/O %zd " "at %ju\n", auio.uio_resid, (uintmax_t)ma[0]->pindex); if (error != 0 || auio.uio_resid != 0) break; } write_done: /* Mark completely processed pages. */ for (i = 0; i < OFF_TO_IDX(prev_offset - poffset); i++) rtvals[i] = VM_PAGER_OK; /* Mark partial EOF page. */ if (prev_offset == poffset + maxsize && (prev_offset & PAGE_MASK) != 0) rtvals[i++] = VM_PAGER_OK; /* Unwritten pages in range, free bonus if the page is clean. */ for (; i < ncount; i++) rtvals[i] = ma[i]->dirty == 0 ? VM_PAGER_OK : VM_PAGER_ERROR; VM_CNT_ADD(v_vnodepgsout, i); VM_CNT_INC(v_vnodeout); return (rtvals[0]); } int vnode_pager_putpages_ioflags(int pager_flags) { int ioflags; /* * Pageouts are already clustered, use IO_ASYNC to force a * bawrite() rather then a bdwrite() to prevent paging I/O * from saturating the buffer cache. Dummy-up the sequential * heuristic to cause large ranges to cluster. If neither * IO_SYNC or IO_ASYNC is set, the system decides how to * cluster. */ ioflags = IO_VMIO; if ((pager_flags & (VM_PAGER_PUT_SYNC | VM_PAGER_PUT_INVAL)) != 0) ioflags |= IO_SYNC; else if ((pager_flags & VM_PAGER_CLUSTER_OK) == 0) ioflags |= IO_ASYNC; ioflags |= (pager_flags & VM_PAGER_PUT_INVAL) != 0 ? IO_INVAL: 0; ioflags |= (pager_flags & VM_PAGER_PUT_NOREUSE) != 0 ? IO_NOREUSE : 0; ioflags |= IO_SEQMAX << IO_SEQSHIFT; return (ioflags); } /* * vnode_pager_undirty_pages(). * * A helper to mark pages as clean after pageout that was possibly * done with a short write. The lpos argument specifies the page run * length in bytes, and the written argument specifies how many bytes * were actually written. eof is the offset past the last valid byte * in the vnode using the absolute file position of the first byte in * the run as the base from which it is computed. */ void vnode_pager_undirty_pages(vm_page_t *ma, int *rtvals, int written, off_t eof, int lpos) { int i, pos, pos_devb; if (written == 0 && eof >= lpos) return; for (i = 0, pos = 0; pos < written; i++, pos += PAGE_SIZE) { if (pos < trunc_page(written)) { rtvals[i] = VM_PAGER_OK; vm_page_undirty(ma[i]); } else { /* Partially written page. */ rtvals[i] = VM_PAGER_AGAIN; vm_page_clear_dirty(ma[i], 0, written & PAGE_MASK); } } if (eof >= lpos) /* avoid truncation */ return; for (pos = eof, i = OFF_TO_IDX(trunc_page(pos)); pos < lpos; i++) { if (pos != trunc_page(pos)) { /* * The page contains the last valid byte in * the vnode, mark the rest of the page as * clean, potentially making the whole page * clean. */ pos_devb = roundup2(pos & PAGE_MASK, DEV_BSIZE); vm_page_clear_dirty(ma[i], pos_devb, PAGE_SIZE - pos_devb); /* * If the page was cleaned, report the pageout * on it as successful. msync() no longer * needs to write out the page, endlessly * creating write requests and dirty buffers. */ if (ma[i]->dirty == 0) rtvals[i] = VM_PAGER_OK; pos = round_page(pos); } else { /* vm_pageout_flush() clears dirty */ rtvals[i] = VM_PAGER_BAD; pos += PAGE_SIZE; } } } static void vnode_pager_update_writecount(vm_object_t object, vm_offset_t start, vm_offset_t end) { struct vnode *vp; vm_ooffset_t old_wm; VM_OBJECT_WLOCK(object); if (object->type != OBJT_VNODE) { VM_OBJECT_WUNLOCK(object); return; } old_wm = object->un_pager.vnp.writemappings; object->un_pager.vnp.writemappings += (vm_ooffset_t)end - start; vp = object->handle; if (old_wm == 0 && object->un_pager.vnp.writemappings != 0) { ASSERT_VOP_LOCKED(vp, "v_writecount inc"); VOP_ADD_WRITECOUNT_CHECKED(vp, 1); CTR3(KTR_VFS, "%s: vp %p v_writecount increased to %d", __func__, vp, vp->v_writecount); } else if (old_wm != 0 && object->un_pager.vnp.writemappings == 0) { ASSERT_VOP_LOCKED(vp, "v_writecount dec"); VOP_ADD_WRITECOUNT_CHECKED(vp, -1); CTR3(KTR_VFS, "%s: vp %p v_writecount decreased to %d", __func__, vp, vp->v_writecount); } VM_OBJECT_WUNLOCK(object); } static void vnode_pager_release_writecount(vm_object_t object, vm_offset_t start, vm_offset_t end) { struct vnode *vp; struct mount *mp; vm_offset_t inc; VM_OBJECT_WLOCK(object); /* * First, recheck the object type to account for the race when * the vnode is reclaimed. */ if (object->type != OBJT_VNODE) { VM_OBJECT_WUNLOCK(object); return; } /* * Optimize for the case when writemappings is not going to * zero. */ inc = end - start; if (object->un_pager.vnp.writemappings != inc) { object->un_pager.vnp.writemappings -= inc; VM_OBJECT_WUNLOCK(object); return; } vp = object->handle; vhold(vp); VM_OBJECT_WUNLOCK(object); mp = NULL; vn_start_write(vp, &mp, V_WAIT); vn_lock(vp, LK_SHARED | LK_RETRY); /* * Decrement the object's writemappings, by swapping the start * and end arguments for vnode_pager_update_writecount(). If * there was not a race with vnode reclaimation, then the * vnode's v_writecount is decremented. */ vnode_pager_update_writecount(object, end, start); VOP_UNLOCK(vp); vdrop(vp); if (mp != NULL) vn_finished_write(mp); } static void vnode_pager_getvp(vm_object_t object, struct vnode **vpp, bool *vp_heldp) { *vpp = object->handle; }