175 lines
7.1 KiB
C
175 lines
7.1 KiB
C
/* $NetBSD: overlay_vnops.c,v 1.2 2000/03/13 23:52:41 soren Exp $ */
|
|
|
|
/*
|
|
* Copyright (c) 1999, 2000 National Aeronautics & Space Administration
|
|
* All rights reserved.
|
|
*
|
|
* This software was written by William Studenmund of the
|
|
* Numerical Aerospace Similation Facility, NASA Ames Research Center.
|
|
*
|
|
* 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. Neither the name of the National Aeronautics & Space Administration
|
|
* 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 NATIONAL AERONAUTICS & SPACE ADMINISTRATION
|
|
* ``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 ADMINISTRATION OR CONTRIB-
|
|
* UTORS 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.
|
|
*/
|
|
/*
|
|
* Copyright (c) 1992, 1993
|
|
* The Regents of the University of California. All rights reserved.
|
|
*
|
|
* This code is derived from software contributed to Berkeley by
|
|
* John Heidemann of the UCLA Ficus project.
|
|
*
|
|
* 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.
|
|
*
|
|
* @(#)null_vnops.c 8.6 (Berkeley) 5/27/95
|
|
*
|
|
* Ancestors:
|
|
* @(#)lofs_vnops.c 1.2 (Berkeley) 6/18/92
|
|
* $Id: overlay_vnops.c,v 1.2 2000/03/13 23:52:41 soren Exp $
|
|
* ...and...
|
|
* @(#)null_vnodeops.c 1.20 92/07/07 UCLA Ficus project
|
|
*/
|
|
|
|
/*
|
|
* Overlay Layer
|
|
*
|
|
* (See mount_overlay(8) for more information.)
|
|
*
|
|
* The overlay layer has two purposes. First, it serves as a demonstration
|
|
* of layering by proving a layer which really does nothing. (the null
|
|
* layer makes the underlying files appear elsewhere in the file hierarchy)
|
|
* Second, the overlay layer can serve as a prototype layer. Since it
|
|
* provides all necessary layer framework, new file system layers can be
|
|
* created very easily be starting with an overlay layer.
|
|
*
|
|
* The remainder of this comment examines the overlay layer as a basis
|
|
* for constructing new layers.
|
|
*
|
|
*
|
|
* INSTANTIATING NEW OVERLAY LAYERS
|
|
*
|
|
* New null layers are created with mount_overlay(8).
|
|
* Mount_overlay(8) takes two arguments, an ignored string
|
|
* and the pathname which the overlay will mount over. After
|
|
* the overlay layer is put into place, all access to the mount
|
|
* point path will proceede through the overlay layer.
|
|
*
|
|
*
|
|
* OPERATION OF AN OVERLAY LAYER
|
|
*
|
|
* The operation of an overlay layer is identical to that of a null
|
|
* layer. See the null layer (and layerfs) documentation for more info.
|
|
*
|
|
*
|
|
* CREATING OTHER FILE SYSTEM LAYERS
|
|
*
|
|
* One of the easiest ways to construct new file system layers is to make
|
|
* a copy of either the null layer or the overlay layer, rename all files
|
|
* and variables, and then begin modifing the copy. Sed can be used to
|
|
* easily rename all variables.
|
|
*
|
|
* The choice between using a null and an overlay layer depends on
|
|
* the desirability of retaining access to the underlying filestore.
|
|
* For instance, the umap filesystem presents both a uid-translated and an
|
|
* untranslaged view of the underlying files, and so it is based off of
|
|
* the null layer. However a layer implimenting Access Controll Lists
|
|
* might prefer to block access to the underlying filestore, for which
|
|
* the overlay layer is a better basis.
|
|
*
|
|
*
|
|
* INVOKING OPERATIONS ON LOWER LAYERS
|
|
*
|
|
* See the null layer documentation.
|
|
*
|
|
*/
|
|
|
|
#include <sys/param.h>
|
|
#include <sys/systm.h>
|
|
#include <sys/proc.h>
|
|
#include <sys/time.h>
|
|
#include <sys/types.h>
|
|
#include <sys/vnode.h>
|
|
#include <sys/mount.h>
|
|
#include <sys/namei.h>
|
|
#include <sys/malloc.h>
|
|
#include <sys/buf.h>
|
|
#include <miscfs/genfs/genfs.h>
|
|
#include <miscfs/overlay/overlay.h>
|
|
#include <miscfs/genfs/layer_extern.h>
|
|
|
|
/*
|
|
* Global vfs data structures
|
|
*/
|
|
int (**overlay_vnodeop_p) __P((void *));
|
|
struct vnodeopv_entry_desc overlay_vnodeop_entries[] = {
|
|
{ &vop_default_desc, layer_bypass },
|
|
|
|
{ &vop_lookup_desc, layer_lookup },
|
|
{ &vop_setattr_desc, layer_setattr },
|
|
{ &vop_getattr_desc, layer_getattr },
|
|
{ &vop_access_desc, layer_access },
|
|
{ &vop_lock_desc, layer_lock },
|
|
{ &vop_unlock_desc, layer_unlock },
|
|
{ &vop_islocked_desc, layer_islocked },
|
|
{ &vop_fsync_desc, layer_fsync },
|
|
{ &vop_inactive_desc, layer_inactive },
|
|
{ &vop_reclaim_desc, layer_reclaim },
|
|
{ &vop_print_desc, layer_print },
|
|
|
|
{ &vop_open_desc, layer_open }, /* mount option handling */
|
|
|
|
{ &vop_strategy_desc, layer_strategy },
|
|
{ &vop_bwrite_desc, layer_bwrite },
|
|
{ &vop_bmap_desc, layer_bmap },
|
|
|
|
{ (struct vnodeop_desc*)NULL, (int(*)__P((void *)))NULL }
|
|
};
|
|
struct vnodeopv_desc overlay_vnodeop_opv_desc =
|
|
{ &overlay_vnodeop_p, overlay_vnodeop_entries };
|