179 lines
7.3 KiB
C
179 lines
7.3 KiB
C
/* $NetBSD: overlay_vnops.c,v 1.9 2002/01/04 07:19:34 chs Exp $ */
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/*
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* Copyright (c) 1999, 2000 National Aeronautics & Space Administration
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* All rights reserved.
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*
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* This software was written by William Studenmund of the
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* Numerical Aerospace Simulation Facility, NASA Ames Research Center.
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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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* 3. Neither the name of the National Aeronautics & Space Administration
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* nor the names of its contributors may be used to endorse or promote
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* products derived from this software without specific prior written
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* permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE NATIONAL AERONAUTICS & SPACE ADMINISTRATION
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* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE ADMINISTRATION OR CONTRIB-
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* UTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
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* OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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/*
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* Copyright (c) 1992, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* This code is derived from software contributed to Berkeley by
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* John Heidemann of the UCLA Ficus project.
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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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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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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* @(#)null_vnops.c 8.6 (Berkeley) 5/27/95
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*
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* Ancestors:
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* @(#)lofs_vnops.c 1.2 (Berkeley) 6/18/92
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* $Id: overlay_vnops.c,v 1.9 2002/01/04 07:19:34 chs Exp $
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* ...and...
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* @(#)null_vnodeops.c 1.20 92/07/07 UCLA Ficus project
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*/
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/*
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* Overlay Layer
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*
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* (See mount_overlay(8) for more information.)
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*
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* The overlay layer has two purposes. First, it serves as a demonstration
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* of layering by providing a layer which really does nothing (the null
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* layer makes the underlying files appear elsewhere in the file hierarchy).
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* Second, the overlay layer can serve as a prototype layer. Since it
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* provides all necessary layer framework, new file system layers can be
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* created very easily by starting with an overlay layer.
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*
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* The remainder of this comment examines the overlay layer as a basis
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* for constructing new layers.
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*
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*
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* INSTANTIATING NEW OVERLAY LAYERS
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*
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* New overlay layers are created with mount_overlay(8).
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* mount_overlay(8) takes two arguments, an ignored string
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* and the pathname which the overlay will mount over. After
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* the overlay layer is put into place, all access to the mount
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* point path will proceed through the overlay layer.
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*
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*
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* OPERATION OF AN OVERLAY LAYER
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*
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* The operation of an overlay layer is identical to that of a null
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* layer. See the null layer (and layerfs) documentation for more info.
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*
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*
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* CREATING OTHER FILE SYSTEM LAYERS
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*
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* One of the easiest ways to construct new file system layers is to make
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* a copy of either the null layer or the overlay layer, rename all files
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* and variables, and then begin modifying the copy. sed(1) can be used to
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* easily rename all variables.
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*
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* The choice between using a null and an overlay layer depends on
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* the desirability of retaining access to the underlying filestore.
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* For instance, the umap filesystem presents both a uid-translated and an
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* untranslated view of the underlying files, and so it is based off of
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* the null layer. However a layer implementing Access Control Lists
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* might prefer to block access to the underlying filestore, for which
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* the overlay layer is a better basis.
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*
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*
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* INVOKING OPERATIONS ON LOWER LAYERS
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*
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* See the null layer documentation.
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*
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*/
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#include <sys/cdefs.h>
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__KERNEL_RCSID(0, "$NetBSD: overlay_vnops.c,v 1.9 2002/01/04 07:19:34 chs Exp $");
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/proc.h>
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#include <sys/time.h>
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#include <sys/vnode.h>
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#include <sys/mount.h>
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#include <sys/namei.h>
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#include <sys/malloc.h>
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#include <sys/buf.h>
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#include <miscfs/genfs/genfs.h>
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#include <miscfs/overlay/overlay.h>
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#include <miscfs/genfs/layer_extern.h>
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/*
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* Global vfs data structures
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*/
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int (**overlay_vnodeop_p) __P((void *));
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const struct vnodeopv_entry_desc overlay_vnodeop_entries[] = {
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{ &vop_default_desc, layer_bypass },
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{ &vop_lookup_desc, layer_lookup },
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{ &vop_setattr_desc, layer_setattr },
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{ &vop_getattr_desc, layer_getattr },
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{ &vop_access_desc, layer_access },
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{ &vop_lock_desc, layer_lock },
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{ &vop_unlock_desc, layer_unlock },
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{ &vop_islocked_desc, layer_islocked },
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{ &vop_fsync_desc, layer_fsync },
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{ &vop_inactive_desc, layer_inactive },
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{ &vop_reclaim_desc, layer_reclaim },
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{ &vop_print_desc, layer_print },
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{ &vop_open_desc, layer_open }, /* mount option handling */
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{ &vop_strategy_desc, layer_strategy },
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{ &vop_bwrite_desc, layer_bwrite },
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{ &vop_bmap_desc, layer_bmap },
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{ &vop_getpages_desc, layer_getpages },
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{ &vop_putpages_desc, layer_putpages },
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{ NULL, NULL }
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};
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const struct vnodeopv_desc overlay_vnodeop_opv_desc =
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{ &overlay_vnodeop_p, overlay_vnodeop_entries };
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