115 lines
4.2 KiB
Groff
115 lines
4.2 KiB
Groff
.\" $NetBSD: puffs_flush.3,v 1.4 2007/05/17 13:31:30 pooka Exp $
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.\"
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.\" Copyright (c) 2007 Antti Kantee. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.Dd April 7, 2007
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.Dt PUFFS_FLUSH 3
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.Os
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.Sh NAME
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.Nm puffs_flush
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.Nd puffs kernel cache flushing and invalidation routines
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.Sh LIBRARY
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.Lb libpuffs
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.Sh SYNOPSIS
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.In puffs.h
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.Ft int
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.Fn puffs_inval_namecache_dir "struct puffs_usermount *pu" "void *cookie"
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.Ft int
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.Fn puffs_inval_namecache_all "struct puffs_usermount *pu"
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.Ft int
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.Fn puffs_inval_pagecache_node "struct puffs_usermount *pu" "void *cookie"
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.Ft int
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.Fo puffs_inval_pagecache_node_range
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.Fa "struct puffs_usermount *pu" "void *cookie" "off_t start" "off_t end"
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.Fc
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.Ft int
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.Fn puffs_flush_pagecache_node "struct puffs_usermount *pu" "void *cookie"
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.Ft int
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.Fo puffs_flush_pagecache_node_range
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.Fa "struct puffs_usermount *pu" "void *cookie" "off_t start" "off_t end"
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.Fc
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.Sh DESCRIPTION
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.Em IMPORTANT NOTE!
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This document describes interfaces which are not yet guaranteed to be
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stable.
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In case you update your system sources, please recompile everything
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and fix complation errors.
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If your sources are out-of-sync, incorrect operation may result.
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The interfaces in this document will most likely be hugely simplified
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in later versions or made transparent to the implementation.
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.Pp
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These routines are used inform the kernel that any information it might
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have cached is no longer valid.
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.Fn puffs_inval_namecache_dir
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invalidates the name cache for a given directory.
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The argument
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.Va cookie
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should describe an existing and valid directory cookie for the file
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system.
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Similarly,
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.Fn puffs_inval_namecache_all
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invalidates the name cache for the entire file system
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(this routine might go away).
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.Pp
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The cached pages (file contents) for a regular file described by
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.Va cookie
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are invalidated using
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.Fn puffs_inval_pagecache_node .
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A specific range can be invalidated using
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.Fn puffs_inval_pagecache_node_range
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for a platform specific page level granularity.
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The offset
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.Va start
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will be
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.Em truncated
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to a page boundary while
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.Va end
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will be
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.Em "rounded up"
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to the next page boundary.
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As a special case, specifying 0 as
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.Va end
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will invalidate all contents from
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.Va start
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to the end of the file.
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.Pp
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It is especially important to note that these routines will not only
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invalidate data in the "read cache", but also data in the "write back"
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cache (conceptually speaking; in reality they are the same cache), which
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has not yet been flushed to the file server.
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Therefore any unflushed data will be lost.
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.Pp
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The counterparts of the invalidation routines are the flushing routines
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.Fn puffs_flush_pagecache_node
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and
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.Fn puffs_flush_pagecache_node_range ,
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which force unwritten data from the kernel page cache to be written.
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For the flush range version, the same range rules as with the
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invalidation routine apply.
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The data is flushed asynchronously, i.e. if the routine returns
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succesfully, all the caller knows is that the data has been queued
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for writing.
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.Sh SEE ALSO
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.Xr puffs 3
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