1.\" 2.\" SPDX-License-Identifier: BSD-2-Clause-FreeBSD 3.\" 4.\" Copyright (c) 2021 The FreeBSD Foundation 5.\" 6.\" Portions of this software were developed by Ka Ho Ng 7.\" under sponsorship from the FreeBSD Foundation. 8.\" 9.\" Redistribution and use in source and binary forms, with or without 10.\" modification, are permitted provided that the following conditions 11.\" are met: 12.\" 1. Redistributions of source code must retain the above copyright 13.\" notice, this list of conditions and the following disclaimer. 14.\" 2. Redistributions in binary form must reproduce the above copyright 15.\" notice, this list of conditions and the following disclaimer in the 16.\" documentation and/or other materials provided with the distribution. 17.\" 18.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 19.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 20.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 21.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 22.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 23.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 24.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 25.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 26.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 27.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 28.\" SUCH DAMAGE. 29.\" 30.Dd April 8, 2021 31.Dt VNODE_PAGER_SETSIZE 9 32.Os 33.Sh NAME 34.Nm vnode_pager_setsize 35.Nd "notify the VM system about updates in the file size" 36.Sh SYNOPSIS 37.In sys/param.h 38.In vm/vm.h 39.In vm/vm_extern.h 40.Ft void 41.Fn vnode_pager_setsize "struct vnode *vp" "vm_ooffset_t nsize" 42.Sh DESCRIPTION 43.Nm 44lets the VM system know about a change in size for a file, 45and updates the object size and vnode pager size of the vm object in 46.Fa vp 47with 48.Fa nsize . 49Page faults on the object mapping with offset beyond the new object 50size results in 51.Va SIGBUS . 52.Pp 53Pages between the old EOF and the new EOF are removed from the object queue 54if the file size shrinks. 55In case the new EOF specified by the 56.Fa nsize 57argument is not aligned to page boundary, 58partial-page area starting beyond the EOF is zeroed and marked invalid. 59if the page exists resident. 60.Pp 61In case the vnode 62.Fa vp 63does not have a VM object allocated, the effect of calling this function is no-op. 64.Pp 65This function must be used within file system code to implement truncation 66if the file system allocates vm objects for vnodes. 67.Sh LOCKS 68The vnode should be exclusively locked on entry and will still be locked on exit. 69.Sh SEE ALSO 70.Xr vnode 9 71.Sh HISTORY 72The 73.Nm 74manual page first appeared in 75.Fx 14 . 76.Sh AUTHORS 77This 78manual page was written by 79.An Ka Ho Ng Aq Mt khng@FreeBSD.org . 80