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Document vnode_pager_setsize(9)

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MFC after:	3 days
Sponsored by:	The FreeBSD Foundation
Reviewed by:	bcr
Approved by:	philip (mentor)
Differential Revision:	https://reviews.freebsd.org/D29408
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Ka Ho Ng 2021-04-07 19:00:31 +08:00
parent 2bca8aa7a7
commit 86a52e262a
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1
share/man/man9/Makefile
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@ -401,6 +401,7 @@ MAN= accept_filter.9 \
vn_isdisk.9 \
vnet.9 \
vnode.9 \
vnode_pager_setsize.9 \
VOP_ACCESS.9 \
VOP_ACLCHECK.9 \
VOP_ADVISE.9 \

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share/man/man9/vnode_pager_setsize.9 Normal file
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@ -0,0 +1,74 @@
.\"
.\" SPDX-License-Identifier: BSD-2-Clause-FreeBSD
.\"
.\" Copyright (c) 2021 The FreeBSD Foundation
.\"
.\" Portions of this software were developed by Ka Ho Ng
.\" under sponsorship from the FreeBSD Foundation.
.\"
.\" 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.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
.\"
.Dd April 6, 2021
.Dt VNODE_PAGER_SETSIZE 9
.Os
.Sh NAME
.Nm vnode_pager_setsize
.Nd "notify the VM system about updates in the file size"
.Sh SYNOPSIS
.In sys/param.h
.In vm/vm.h
.In vm/vm_extern.h
.Ft void
.Fn vnode_pager_setsize "struct vnode *vp" "vm_ooffset_t nsize"
.Sh DESCRIPTION
.Nm
lets the VM system know about a change in size for a file.
Content beyond the new EOF specified by the
.Fa nsize
argument will be purged from the cache.
This function is useful for use within file system code to implement
truncation in
.Xr VOP_SETATTR 9 .
.Sh IMPLEMENTATION NOTES
In case the new EOF specified by the
.Fa nsize
argument is not aligned to page boundaries,
partial-page area starting beyond the EOF will be zeroed.
In partial-page area,
for content occupying whole blocks within block
boundaries,
the dirty bits for the corresponding blocks will be cleared.
.Sh LOCKING
Writer lock of the VM object of
.Fa vp
will be held within the function.
.Sh SEE ALSO
.Xr vnode 9
.Sh HISTORY
The
.Nm
manual page first appeared in
.Fx 14 .
.Sh AUTHORS
This
manual page was written by
.An Ka Ho Ng Aq Mt khng@FreeBSD.org .