xref: /netbsd/lib/libpuffs/puffs_flush.3 (revision 622f8591)

.\"	$NetBSD: puffs_flush.3,v 1.2 2007/04/06 16:44:01 pooka Exp $
.\"
.\" Copyright (c) 2007 Antti Kantee.  All rights reserved.
.\"
.\" 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 7, 2007
.Dt PUFFS_FLUSH 3
.Os
.Sh NAME
.Nm puffs_flush
.Nd puffs kernel cache flushing and invalidation routines
.Sh LIBRARY
.Lb libpuffs
.Sh SYNOPSIS
.In puffs.h
.Ft int
.Fn puffs_inval_namecache_dir "struct puffs_usermount *pu" "void *cookie"
.Ft int
.Fn puffs_inval_namecache_all "struct puffs_usermount *pu"
.Ft int
.Fn puffs_inval_pagecache_node "struct puffs_usermoint *pu" "void *cookie"
.Ft int
.Fo puffs_inval_pagecache_node_range
.Fa "struct puffs_usermoint *pu" "void *cookie" "off_t start" "off_t end"
.Fc
.Sh DESCRIPTION
.Em IMPORTANT NOTE!
This document describes interfaces which are not yet guaranteed to be
stable.
In case you update your system sources, please recompile everything
and fix complation errors.
If your sources are out-of-sync, incorrect operation may result.
The interfaces in this document will most likely be hugely simplified
in later versions or made transparent to the implementation.
.Pp
These routines are used inform the kernel that any information it might
have cached is no longer valid.
.Fn puffs_inval_namecache_dir
invalidates the name cache for a given directory.
The argument
.Va cookie
should describe an existing and valid directory cookie for the file
system.
Similarly,
.Fn puffs_inval_namecache_all
invalidates the name cache for the entire file system
(this routine might go away).
.Pp
The cached pages (file contents) for a regular file described by
.Va cookie
are invalidated using
.Fn puffs_inval_pagecache_node .
A specific range can be invalidated using
.Fn puffs_inval_pagecache_node_range
for a platform specific page level granularity.
The offset
.Va start
will be
.Em truncated
to a page boundary while
.Va end
will be
.Em "rounded up"
to the next page boundary.
As a special case, specifying 0 as
.Va end
will invalidate all contents from
.Va start
to the end of the file.
.Pp
It is especially important to note that these routines will not only
invalidate data in the "read cache", but also data in the "write back"
cache (conceptually speaking; in reality they are the same cache), which
has not yet been flushed to the file server.
Therefore any unflushed data will be lost.
.Sh SEE ALSO
.Xr puffs 3
.Sh BUGS
Routines for forcing a flush of the page cache for a node are not
yet implemented.