+++ /dev/null
-/*
- * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
- *
- * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
- *
- * This file contains Original Code and/or Modifications of Original Code
- * as defined in and that are subject to the Apple Public Source License
- * Version 2.0 (the 'License'). You may not use this file except in
- * compliance with the License. The rights granted to you under the License
- * may not be used to create, or enable the creation or redistribution of,
- * unlawful or unlicensed copies of an Apple operating system, or to
- * circumvent, violate, or enable the circumvention or violation of, any
- * terms of an Apple operating system software license agreement.
- *
- * Please obtain a copy of the License at
- * http://www.opensource.apple.com/apsl/ and read it before using this file.
- *
- * The Original Code and all software distributed under the License are
- * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
- * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
- * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
- * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
- * Please see the License for the specific language governing rights and
- * limitations under the License.
- *
- * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
- */
-/* Copyright (c) 1995 NeXT Computer, Inc. All Rights Reserved */
-/*
- * 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
- * ...and...
- * @(#)null_vnodeops.c 1.20 92/07/07 UCLA Ficus project
- */
-
-/*
- * Null Layer
- *
- * (See mount_null(8) for more information.)
- *
- * The null layer duplicates a portion of the file system
- * name space under a new name. In this respect, it is
- * similar to the loopback file system. It differs from
- * the loopback fs in two respects: it is implemented using
- * a stackable layers techniques, and it's "null-node"s stack above
- * all lower-layer vnodes, not just over directory vnodes.
- *
- * The null layer has two purposes. First, it serves as a demonstration
- * of layering by proving a layer which does nothing. (It actually
- * does everything the loopback file system does, which is slightly
- * more than nothing.) Second, the null 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 a null layer.
- *
- * The remainder of this man page examines the null layer as a basis
- * for constructing new layers.
- *
- *
- * INSTANTIATING NEW NULL LAYERS
- *
- * New null layers are created with mount_null(8).
- * Mount_null(8) takes two arguments, the pathname
- * of the lower vfs (target-pn) and the pathname where the null
- * layer will appear in the namespace (alias-pn). After
- * the null layer is put into place, the contents
- * of target-pn subtree will be aliased under alias-pn.
- *
- *
- * OPERATION OF A NULL LAYER
- *
- * The null layer is the minimum file system layer,
- * simply bypassing all possible operations to the lower layer
- * for processing there. The majority of its activity centers
- * on the bypass routine, though which nearly all vnode operations
- * pass.
- *
- * The bypass routine accepts arbitrary vnode operations for
- * handling by the lower layer. It begins by examing vnode
- * operation arguments and replacing any null-nodes by their
- * lower-layer equivlants. It then invokes the operation
- * on the lower layer. Finally, it replaces the null-nodes
- * in the arguments and, if a vnode is return by the operation,
- * stacks a null-node on top of the returned vnode.
- *
- * Although bypass handles most operations, vnop_getattr, vnop_lock,
- * vnop_unlock, vnop_inactive, vnop_reclaim, and vnop_print are not
- * bypassed. Vop_getattr must change the fsid being returned.
- * Vop_lock and vnop_unlock must handle any locking for the
- * current vnode as well as pass the lock request down.
- * Vop_inactive and vnop_reclaim are not bypassed so that
- * they can handle freeing null-layer specific data. Vop_print
- * is not bypassed to avoid excessive debugging information.
- * Also, certain vnode operations change the locking state within
- * the operation (create, mknod, remove, link, rename, mkdir, rmdir,
- * and symlink). Ideally these operations should not change the
- * lock state, but should be changed to let the caller of the
- * function unlock them. Otherwise all intermediate vnode layers
- * (such as union, umapfs, etc) must catch these functions to do
- * the necessary locking at their layer.
- *
- *
- * INSTANTIATING VNODE STACKS
- *
- * Mounting associates the null layer with a lower layer,
- * effect stacking two VFSes. Vnode stacks are instead
- * created on demand as files are accessed.
- *
- * The initial mount creates a single vnode stack for the
- * root of the new null layer. All other vnode stacks
- * are created as a result of vnode operations on
- * this or other null vnode stacks.
- *
- * New vnode stacks come into existance as a result of
- * an operation which returns a vnode.
- * The bypass routine stacks a null-node above the new
- * vnode before returning it to the caller.
- *
- * For example, imagine mounting a null layer with
- * "mount_null /usr/include /dev/layer/null".
- * Changing directory to /dev/layer/null will assign
- * the root null-node (which was created when the null layer was mounted).
- * Now consider opening "sys". A vnop_lookup would be
- * done on the root null-node. This operation would bypass through
- * to the lower layer which would return a vnode representing
- * the UFS "sys". Null_bypass then builds a null-node
- * aliasing the UFS "sys" and returns this to the caller.
- * Later operations on the null-node "sys" will repeat this
- * process when constructing other vnode stacks.
- *
- *
- * CREATING OTHER FILE SYSTEM LAYERS
- *
- * One of the easiest ways to construct new file system layers is to make
- * a copy of the null layer, rename all files and variables, and
- * then begin modifing the copy. Sed can be used to easily rename
- * all variables.
- *
- * The umap layer is an example of a layer descended from the
- * null layer.
- *
- *
- * INVOKING OPERATIONS ON LOWER LAYERS
- *
- * There are two techniques to invoke operations on a lower layer
- * when the operation cannot be completely bypassed. Each method
- * is appropriate in different situations. In both cases,
- * it is the responsibility of the aliasing layer to make
- * the operation arguments "correct" for the lower layer
- * by mapping an vnode arguments to the lower layer.
- *
- * The first approach is to call the aliasing layer's bypass routine.
- * This method is most suitable when you wish to invoke the operation
- * currently being hanldled on the lower layer. It has the advantage
- * that the bypass routine already must do argument mapping.
- * An example of this is null_getattrs in the null layer.
- *
- * A second approach is to directly invoked vnode operations on
- * the lower layer with the VOP_OPERATIONNAME interface.
- * The advantage of this method is that it is easy to invoke
- * arbitrary operations on the lower layer. The disadvantage
- * is that vnodes arguments must be manualy mapped.
- *
- */
-
-#include <sys/param.h>
-#include <sys/systm.h>
-#include <sys/proc.h>
-#include <sys/kauth.h>
-#include <sys/time.h>
-#include <sys/types.h>
-#include <sys/vnode.h>
-#include <sys/mount_internal.h>
-#include <sys/namei.h>
-#include <sys/malloc.h>
-#include <sys/buf.h>
-#include <miscfs/nullfs/null.h>
-
-
-int null_bug_bypass = 0; /* for debugging: enables bypass printf'ing */
-
-/*
- * This is the 10-Apr-92 bypass routine.
- * This version has been optimized for speed, throwing away some
- * safety checks. It should still always work, but it's not as
- * robust to programmer errors.
- * Define SAFETY to include some error checking code.
- *
- * In general, we map all vnodes going down and unmap them on the way back.
- * As an exception to this, vnodes can be marked "unmapped" by setting
- * the Nth bit in operation's vdesc_flags.
- *
- * Also, some BSD vnode operations have the side effect of node_put'ing
- * their arguments. With stacking, the reference counts are held
- * by the upper node, not the lower one, so we must handle these
- * side-effects here. This is not of concern in Sun-derived systems
- * since there are no such side-effects.
- *
- * This makes the following assumptions:
- * - only one returned vpp
- * - no INOUT vpp's (Sun's vnop_open has one of these)
- * - the vnode operation vector of the first vnode should be used
- * to determine what implementation of the op should be invoked
- * - all mapped vnodes are of our vnode-type (NEEDSWORK:
- * problems on rmdir'ing mount points and renaming?)
- */
-int
-null_bypass(ap)
- struct vnop_generic_args /* {
- struct vnodeop_desc *a_desc;
- <other random data follows, presumably>
- } */ *ap;
-{
- extern int (**null_vnodeop_p)(void *); /* not extern, really "forward" */
- register struct vnode **this_vp_p;
- int error;
- struct vnode *old_vps[VDESC_MAX_VPS];
- struct vnode **vps_p[VDESC_MAX_VPS];
- struct vnode ***vppp;
- struct vnodeop_desc *descp = ap->a_desc;
- int reles, i;
-
- if (null_bug_bypass)
- printf ("null_bypass: %s\n", descp->vdesc_name);
-
-#ifdef SAFETY
- /*
- * We require at least one vp.
- */
- if (descp->vdesc_vp_offsets == NULL ||
- descp->vdesc_vp_offsets[0] == VDESC_NO_OFFSET)
- panic ("null_bypass: no vp's in map.\n");
-#endif
-
- /*
- * Map the vnodes going in.
- * Later, we'll invoke the operation based on
- * the first mapped vnode's operation vector.
- */
- reles = descp->vdesc_flags;
- for (i = 0; i < VDESC_MAX_VPS; reles >>= 1, i++) {
- if (descp->vdesc_vp_offsets[i] == VDESC_NO_OFFSET)
- break; /* bail out at end of list */
- vps_p[i] = this_vp_p =
- VOPARG_OFFSETTO(struct vnode**,descp->vdesc_vp_offsets[i],ap);
- /*
- * We're not guaranteed that any but the first vnode
- * are of our type. Check for and don't map any
- * that aren't. (We must always map first vp or vclean fails.)
- */
- if (i && (*this_vp_p == NULL ||
- (*this_vp_p)->v_op != null_vnodeop_p)) {
- old_vps[i] = NULL;
- } else {
- old_vps[i] = *this_vp_p;
- *(vps_p[i]) = NULLVPTOLOWERVP(*this_vp_p);
- /*
- * XXX - Several operations have the side effect
- * of vnode_put'ing their vp's. We must account for
- * that. (This should go away in the future.)
- */
- if (reles & 1)
- vnode_get(*this_vp_p);
- }
-
- }
-
- /*
- * Call the operation on the lower layer
- * with the modified argument structure.
- */
- error = VCALL(*(vps_p[0]), descp->vdesc_offset, ap);
-
- /*
- * Maintain the illusion of call-by-value
- * by restoring vnodes in the argument structure
- * to their original value.
- */
- reles = descp->vdesc_flags;
- for (i = 0; i < VDESC_MAX_VPS; reles >>= 1, i++) {
- if (descp->vdesc_vp_offsets[i] == VDESC_NO_OFFSET)
- break; /* bail out at end of list */
- if (old_vps[i]) {
- *(vps_p[i]) = old_vps[i];
- if (reles & 1)
- vnode_put(*(vps_p[i]));
- }
- }
-
- /*
- * Map the possible out-going vpp
- * (Assumes that the lower layer always returns
- * a vnode_get'ed vpp unless it gets an error.)
- */
- if (descp->vdesc_vpp_offset != VDESC_NO_OFFSET &&
- !(descp->vdesc_flags & VDESC_NOMAP_VPP) &&
- !error) {
- /*
- * XXX - even though some ops have vpp returned vp's,
- * several ops actually vnode_put this before returning.
- * We must avoid these ops.
- * (This should go away when these ops are regularized.)
- */
- if (descp->vdesc_flags & VDESC_VPP_WILLRELE)
- goto out;
- vppp = VOPARG_OFFSETTO(struct vnode***,
- descp->vdesc_vpp_offset,ap);
- error = null_node_create(old_vps[0]->v_mount, **vppp, *vppp);
- }
-
- out:
- return (error);
-}
-
-/*
- * We have to carry on the locking protocol on the null layer vnodes
- * as we progress through the tree. We also have to enforce read-only
- * if this layer is mounted read-only.
- */
-null_lookup(ap)
- struct vnop_lookup_args /* {
- struct vnode * a_dvp;
- struct vnode ** a_vpp;
- struct componentname * a_cnp;
- vfs_context_t a_context;
- } */ *ap;
-{
- struct componentname *cnp = ap->a_cnp;
- struct proc *p = cnp->cn_proc;
- int flags = cnp->cn_flags;
- struct vnode *dvp, *vp;
- int error;
-
- error = null_bypass(ap);
-
- /*
- * We must do the same locking and unlocking at this layer as
- * is done in the layers below us. We could figure this out
- * based on the error return and the LASTCN, LOCKPARENT, and
- * LOCKLEAF flags. However, it is more expidient to just find
- * out the state of the lower level vnodes and set ours to the
- * same state.
- */
- dvp = ap->a_dvp;
- vp = *ap->a_vpp;
- if (dvp == vp)
- return (error);
- return (error);
-}
-
-/*
- * Setattr call.
- */
-int
-null_setattr(
- struct vnop_setattr_args /* {
- struct vnodeop_desc *a_desc;
- struct vnode *a_vp;
- struct vnode_attr *a_vap;
- kauth_cred_t a_cred;
- struct proc *a_p;
- } */ *ap)
-{
- struct vnode *vp = ap->a_vp;
- struct vnode_attr *vap = ap->a_vap;
-
- if (VATTR_IS_ACTIVE(vap, va_data_size)) {
- switch (vp->v_type) {
- case VDIR:
- return (EISDIR);
- case VCHR:
- case VBLK:
- case VSOCK:
- case VFIFO:
- return (0);
- case VREG:
- case VLNK:
- default:
- }
- }
- return (null_bypass(ap));
-}
-
-/*
- * We handle getattr only to change the fsid.
- */
-int
-null_getattr(ap)
- struct vnop_getattr_args /* {
- struct vnode *a_vp;
- struct vnode_attr *a_vap;
- vfs_context_t a_context;
- } */ *ap;
-{
- int error;
-
- if (error = null_bypass(ap))
- return (error);
- /* Requires that arguments be restored. */
- VATTR_RETURN(ap->a_vap, va_fsid, ap->a_vp->v_mount->mnt_vfsstat.f_fsid.val[0]);
- return (0);
-}
-
-int
-null_access(ap)
- struct vnop_access_args /* {
- struct vnode *a_vp;
- int a_action;
- vfs_context_t a_context;
- } */ *ap;
-{
- return (null_bypass(ap));
-}
-
-int
-null_inactive(ap)
- struct vnop_inactive_args /* {
- struct vnode *a_vp;
- vfs_context_t a_context;
- } */ *ap;
-{
- /*
- * Do nothing (and _don't_ bypass).
- * Wait to vnode_put lowervp until reclaim,
- * so that until then our null_node is in the
- * cache and reusable.
- *
- * NEEDSWORK: Someday, consider inactive'ing
- * the lowervp and then trying to reactivate it
- * with capabilities (v_id)
- * like they do in the name lookup cache code.
- * That's too much work for now.
- */
- return (0);
-}
-
-int
-null_reclaim(ap)
- struct vnop_reclaim_args /* {
- struct vnode *a_vp;
- vfs_context_t a_context;
- } */ *ap;
-{
- struct vnode *vp = ap->a_vp;
- struct null_node *xp = VTONULL(vp);
- struct vnode *lowervp = xp->null_lowervp;
-
- /*
- * Note: in vnop_reclaim, vp->v_op == dead_vnodeop_p,
- * so we can't call VOPs on ourself.
- */
- /* After this assignment, this node will not be re-used. */
- xp->null_lowervp = NULL;
- LIST_REMOVE(xp, null_hash);
- FREE(vp->v_data, M_TEMP);
- vp->v_data = NULL;
- vnode_put (lowervp);
- return (0);
-}
-
-/*
- * XXX - vnop_strategy must be hand coded because it has no
- * vnode in its arguments.
- * This goes away with a merged VM/buffer cache.
- */
-int
-null_strategy(ap)
- struct vnop_strategy_args /* {
- struct buf *a_bp;
- } */ *ap;
-{
- struct buf *bp = ap->a_bp;
- int error;
- struct vnode *savedvp;
-
- savedvp = vnode(bp);
- buf_setvnode(bp, NULLVPTOLOWERVP(savedvp));
-
- error = VNOP_STRATEGY(bp);
-
- buf_setvnode(bp, savedvp);
-
- return (error);
-}
-
-/*
- * XXX - like vnop_strategy, vnop_bwrite must be hand coded because it has no
- * vnode in its arguments.
- * This goes away with a merged VM/buffer cache.
- */
-int
-null_bwrite(ap)
- struct vnop_bwrite_args /* {
- struct buf *a_bp;
- } */ *ap;
-{
- struct buf *bp = ap->a_bp;
- int error;
- struct vnode *savedvp;
-
- savedvp = buf_vnode(bp);
- buf_setvnode(bp, NULLVPTOLOWERVP(savedvp));
-
- error = VNOP_BWRITE(bp);
-
- buf_setvnode(bp, savedvp);
-
- return (error);
-}
-
-/*
- * Global vfs data structures
- */
-
-#define VOPFUNC int (*)(void *)
-
-int (**null_vnodeop_p)(void *);
-struct vnodeopv_entry_desc null_vnodeop_entries[] = {
- { &vnop_default_desc, (VOPFUNC)null_bypass },
-
- { &vnop_lookup_desc, (VOPFUNC)null_lookup },
- { &vnop_setattr_desc, (VOPFUNC)null_setattr },
- { &vnop_getattr_desc, (VOPFUNC)null_getattr },
- { &vnop_access_desc, (VOPFUNC)null_access },
- { &vnop_inactive_desc, (VOPFUNC)null_inactive },
- { &vnop_reclaim_desc, (VOPFUNC)null_reclaim },
-
- { &vnop_strategy_desc, (VOPFUNC)null_strategy },
- { &vnop_bwrite_desc, (VOPFUNC)null_bwrite },
-
- { (struct vnodeop_desc*)NULL, (int(*)())NULL }
-};
-struct vnodeopv_desc null_vnodeop_opv_desc =
- { &null_vnodeop_p, null_vnodeop_entries };
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