861 lines
25 KiB
C
861 lines
25 KiB
C
/*
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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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* ...and...
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* @(#)null_vnodeops.c 1.20 92/07/07 UCLA Ficus project
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*
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* $FreeBSD$
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*/
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/*
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* Null Layer
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*
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* (See mount_nullfs(8) for more information.)
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*
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* The null layer duplicates a portion of the filesystem
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* name space under a new name. In this respect, it is
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* similar to the loopback filesystem. It differs from
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* the loopback fs in two respects: it is implemented using
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* a stackable layers techniques, and its "null-node"s stack above
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* all lower-layer vnodes, not just over directory vnodes.
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*
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* The null layer has two purposes. First, it serves as a demonstration
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* of layering by proving a layer which does nothing. (It actually
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* does everything the loopback filesystem does, which is slightly
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* more than nothing.) Second, the null layer can serve as a prototype
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* layer. Since it provides all necessary layer framework,
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* new filesystem layers can be created very easily be starting
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* with a null layer.
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*
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* The remainder of this man page examines the null 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 NULL LAYERS
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*
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* New null layers are created with mount_nullfs(8).
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* Mount_nullfs(8) takes two arguments, the pathname
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* of the lower vfs (target-pn) and the pathname where the null
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* layer will appear in the namespace (alias-pn). After
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* the null layer is put into place, the contents
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* of target-pn subtree will be aliased under alias-pn.
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*
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*
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* OPERATION OF A NULL LAYER
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*
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* The null layer is the minimum filesystem layer,
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* simply bypassing all possible operations to the lower layer
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* for processing there. The majority of its activity centers
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* on the bypass routine, through which nearly all vnode operations
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* pass.
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*
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* The bypass routine accepts arbitrary vnode operations for
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* handling by the lower layer. It begins by examing vnode
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* operation arguments and replacing any null-nodes by their
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* lower-layer equivlants. It then invokes the operation
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* on the lower layer. Finally, it replaces the null-nodes
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* in the arguments and, if a vnode is return by the operation,
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* stacks a null-node on top of the returned vnode.
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*
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* Although bypass handles most operations, vop_getattr, vop_lock,
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* vop_unlock, vop_inactive, vop_reclaim, and vop_print are not
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* bypassed. Vop_getattr must change the fsid being returned.
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* Vop_lock and vop_unlock must handle any locking for the
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* current vnode as well as pass the lock request down.
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* Vop_inactive and vop_reclaim are not bypassed so that
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* they can handle freeing null-layer specific data. Vop_print
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* is not bypassed to avoid excessive debugging information.
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* Also, certain vnode operations change the locking state within
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* the operation (create, mknod, remove, link, rename, mkdir, rmdir,
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* and symlink). Ideally these operations should not change the
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* lock state, but should be changed to let the caller of the
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* function unlock them. Otherwise all intermediate vnode layers
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* (such as union, umapfs, etc) must catch these functions to do
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* the necessary locking at their layer.
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*
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*
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* INSTANTIATING VNODE STACKS
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*
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* Mounting associates the null layer with a lower layer,
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* effect stacking two VFSes. Vnode stacks are instead
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* created on demand as files are accessed.
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*
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* The initial mount creates a single vnode stack for the
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* root of the new null layer. All other vnode stacks
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* are created as a result of vnode operations on
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* this or other null vnode stacks.
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*
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* New vnode stacks come into existance as a result of
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* an operation which returns a vnode.
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* The bypass routine stacks a null-node above the new
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* vnode before returning it to the caller.
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*
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* For example, imagine mounting a null layer with
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* "mount_nullfs /usr/include /dev/layer/null".
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* Changing directory to /dev/layer/null will assign
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* the root null-node (which was created when the null layer was mounted).
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* Now consider opening "sys". A vop_lookup would be
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* done on the root null-node. This operation would bypass through
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* to the lower layer which would return a vnode representing
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* the UFS "sys". Null_bypass then builds a null-node
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* aliasing the UFS "sys" and returns this to the caller.
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* Later operations on the null-node "sys" will repeat this
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* process when constructing other vnode stacks.
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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 filesystem layers is to make
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* a copy of the null layer, rename all files and variables, and
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* then begin modifing the copy. Sed can be used to easily rename
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* all variables.
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*
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* The umap layer is an example of a layer descended from the
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* null layer.
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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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* There are two techniques to invoke operations on a lower layer
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* when the operation cannot be completely bypassed. Each method
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* is appropriate in different situations. In both cases,
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* it is the responsibility of the aliasing layer to make
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* the operation arguments "correct" for the lower layer
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* by mapping an vnode arguments to the lower layer.
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*
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* The first approach is to call the aliasing layer's bypass routine.
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* This method is most suitable when you wish to invoke the operation
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* currently being handled on the lower layer. It has the advantage
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* that the bypass routine already must do argument mapping.
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* An example of this is null_getattrs in the null layer.
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*
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* A second approach is to directly invoke vnode operations on
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* the lower layer with the VOP_OPERATIONNAME interface.
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* The advantage of this method is that it is easy to invoke
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* arbitrary operations on the lower layer. The disadvantage
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* is that vnode arguments must be manualy mapped.
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*
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*/
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/conf.h>
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#include <sys/kernel.h>
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#include <sys/lock.h>
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#include <sys/malloc.h>
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#include <sys/mount.h>
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#include <sys/mutex.h>
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#include <sys/namei.h>
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#include <sys/sysctl.h>
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#include <sys/vnode.h>
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#include <fs/nullfs/null.h>
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#include <vm/vm.h>
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#include <vm/vm_extern.h>
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#include <vm/vm_object.h>
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#include <vm/vnode_pager.h>
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static int null_bug_bypass = 0; /* for debugging: enables bypass printf'ing */
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SYSCTL_INT(_debug, OID_AUTO, nullfs_bug_bypass, CTLFLAG_RW,
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&null_bug_bypass, 0, "");
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static int null_access(struct vop_access_args *ap);
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static int null_createvobject(struct vop_createvobject_args *ap);
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static int null_destroyvobject(struct vop_destroyvobject_args *ap);
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static int null_getattr(struct vop_getattr_args *ap);
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static int null_getvobject(struct vop_getvobject_args *ap);
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static int null_inactive(struct vop_inactive_args *ap);
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static int null_islocked(struct vop_islocked_args *ap);
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static int null_lock(struct vop_lock_args *ap);
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static int null_lookup(struct vop_lookup_args *ap);
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static int null_open(struct vop_open_args *ap);
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static int null_print(struct vop_print_args *ap);
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static int null_reclaim(struct vop_reclaim_args *ap);
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static int null_rename(struct vop_rename_args *ap);
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static int null_setattr(struct vop_setattr_args *ap);
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static int null_unlock(struct vop_unlock_args *ap);
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/*
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* This is the 10-Apr-92 bypass routine.
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* This version has been optimized for speed, throwing away some
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* safety checks. It should still always work, but it's not as
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* robust to programmer errors.
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*
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* In general, we map all vnodes going down and unmap them on the way back.
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* As an exception to this, vnodes can be marked "unmapped" by setting
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* the Nth bit in operation's vdesc_flags.
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*
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* Also, some BSD vnode operations have the side effect of vrele'ing
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* their arguments. With stacking, the reference counts are held
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* by the upper node, not the lower one, so we must handle these
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* side-effects here. This is not of concern in Sun-derived systems
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* since there are no such side-effects.
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*
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* This makes the following assumptions:
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* - only one returned vpp
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* - no INOUT vpp's (Sun's vop_open has one of these)
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* - the vnode operation vector of the first vnode should be used
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* to determine what implementation of the op should be invoked
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* - all mapped vnodes are of our vnode-type (NEEDSWORK:
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* problems on rmdir'ing mount points and renaming?)
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*/
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int
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null_bypass(ap)
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struct vop_generic_args /* {
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struct vnodeop_desc *a_desc;
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<other random data follows, presumably>
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} */ *ap;
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{
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register struct vnode **this_vp_p;
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int error;
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struct vnode *old_vps[VDESC_MAX_VPS];
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struct vnode **vps_p[VDESC_MAX_VPS];
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struct vnode ***vppp;
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struct vnodeop_desc *descp = ap->a_desc;
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int reles, i;
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if (null_bug_bypass)
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printf ("null_bypass: %s\n", descp->vdesc_name);
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#ifdef DIAGNOSTIC
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/*
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* We require at least one vp.
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*/
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if (descp->vdesc_vp_offsets == NULL ||
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descp->vdesc_vp_offsets[0] == VDESC_NO_OFFSET)
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panic ("null_bypass: no vp's in map");
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#endif
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/*
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* Map the vnodes going in.
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* Later, we'll invoke the operation based on
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* the first mapped vnode's operation vector.
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*/
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reles = descp->vdesc_flags;
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for (i = 0; i < VDESC_MAX_VPS; reles >>= 1, i++) {
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if (descp->vdesc_vp_offsets[i] == VDESC_NO_OFFSET)
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break; /* bail out at end of list */
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vps_p[i] = this_vp_p =
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VOPARG_OFFSETTO(struct vnode**,descp->vdesc_vp_offsets[i],ap);
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/*
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* We're not guaranteed that any but the first vnode
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* are of our type. Check for and don't map any
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* that aren't. (We must always map first vp or vclean fails.)
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*/
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if (i && (*this_vp_p == NULLVP ||
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(*this_vp_p)->v_op != null_vnodeop_p)) {
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old_vps[i] = NULLVP;
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} else {
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old_vps[i] = *this_vp_p;
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*(vps_p[i]) = NULLVPTOLOWERVP(*this_vp_p);
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/*
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* XXX - Several operations have the side effect
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* of vrele'ing their vp's. We must account for
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* that. (This should go away in the future.)
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*/
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if (reles & VDESC_VP0_WILLRELE)
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VREF(*this_vp_p);
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}
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}
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/*
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* Call the operation on the lower layer
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* with the modified argument structure.
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*/
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if (vps_p[0] && *vps_p[0])
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error = VCALL(*(vps_p[0]), descp->vdesc_offset, ap);
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else {
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printf("null_bypass: no map for %s\n", descp->vdesc_name);
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error = EINVAL;
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}
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/*
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* Maintain the illusion of call-by-value
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* by restoring vnodes in the argument structure
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* to their original value.
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*/
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reles = descp->vdesc_flags;
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for (i = 0; i < VDESC_MAX_VPS; reles >>= 1, i++) {
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if (descp->vdesc_vp_offsets[i] == VDESC_NO_OFFSET)
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break; /* bail out at end of list */
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if (old_vps[i]) {
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*(vps_p[i]) = old_vps[i];
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#if 0
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if (reles & VDESC_VP0_WILLUNLOCK)
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VOP_UNLOCK(*(vps_p[i]), LK_THISLAYER, curthread);
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#endif
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if (reles & VDESC_VP0_WILLRELE)
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vrele(*(vps_p[i]));
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}
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}
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/*
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* Map the possible out-going vpp
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* (Assumes that the lower layer always returns
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* a VREF'ed vpp unless it gets an error.)
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*/
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if (descp->vdesc_vpp_offset != VDESC_NO_OFFSET &&
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!(descp->vdesc_flags & VDESC_NOMAP_VPP) &&
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!error) {
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/*
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* XXX - even though some ops have vpp returned vp's,
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* several ops actually vrele this before returning.
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* We must avoid these ops.
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* (This should go away when these ops are regularized.)
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*/
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if (descp->vdesc_flags & VDESC_VPP_WILLRELE)
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goto out;
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vppp = VOPARG_OFFSETTO(struct vnode***,
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descp->vdesc_vpp_offset,ap);
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if (*vppp)
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error = null_node_create(old_vps[0]->v_mount, **vppp, *vppp);
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}
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out:
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return (error);
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}
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/*
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* We have to carry on the locking protocol on the null layer vnodes
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* as we progress through the tree. We also have to enforce read-only
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* if this layer is mounted read-only.
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*/
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static int
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null_lookup(ap)
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struct vop_lookup_args /* {
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struct vnode * a_dvp;
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struct vnode ** a_vpp;
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struct componentname * a_cnp;
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} */ *ap;
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{
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struct componentname *cnp = ap->a_cnp;
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struct vnode *dvp = ap->a_dvp;
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struct thread *td = cnp->cn_thread;
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int flags = cnp->cn_flags;
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struct vnode *vp, *ldvp, *lvp;
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int error;
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if ((flags & ISLASTCN) && (dvp->v_mount->mnt_flag & MNT_RDONLY) &&
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(cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME))
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return (EROFS);
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/*
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* Although it is possible to call null_bypass(), we'll do
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* a direct call to reduce overhead
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*/
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ldvp = NULLVPTOLOWERVP(dvp);
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vp = lvp = NULL;
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error = VOP_LOOKUP(ldvp, &lvp, cnp);
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if (error == EJUSTRETURN && (flags & ISLASTCN) &&
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(dvp->v_mount->mnt_flag & MNT_RDONLY) &&
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(cnp->cn_nameiop == CREATE || cnp->cn_nameiop == RENAME))
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error = EROFS;
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/*
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* Rely only on the PDIRUNLOCK flag which should be carefully
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* tracked by underlying filesystem.
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*/
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if (cnp->cn_flags & PDIRUNLOCK)
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VOP_UNLOCK(dvp, LK_THISLAYER, td);
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if ((error == 0 || error == EJUSTRETURN) && lvp != NULL) {
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if (ldvp == lvp) {
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*ap->a_vpp = dvp;
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VREF(dvp);
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vrele(lvp);
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} else {
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error = null_node_create(dvp->v_mount, lvp, &vp);
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if (error == 0)
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*ap->a_vpp = vp;
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}
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}
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return (error);
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}
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/*
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* Setattr call. Disallow write attempts if the layer is mounted read-only.
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*/
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int
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null_setattr(ap)
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struct vop_setattr_args /* {
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struct vnodeop_desc *a_desc;
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struct vnode *a_vp;
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struct vattr *a_vap;
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struct ucred *a_cred;
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struct thread *a_td;
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} */ *ap;
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{
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struct vnode *vp = ap->a_vp;
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struct vattr *vap = ap->a_vap;
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if ((vap->va_flags != VNOVAL || vap->va_uid != (uid_t)VNOVAL ||
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vap->va_gid != (gid_t)VNOVAL || vap->va_atime.tv_sec != VNOVAL ||
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vap->va_mtime.tv_sec != VNOVAL || vap->va_mode != (mode_t)VNOVAL) &&
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(vp->v_mount->mnt_flag & MNT_RDONLY))
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return (EROFS);
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if (vap->va_size != VNOVAL) {
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switch (vp->v_type) {
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case VDIR:
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return (EISDIR);
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case VCHR:
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case VBLK:
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case VSOCK:
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case VFIFO:
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if (vap->va_flags != VNOVAL)
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return (EOPNOTSUPP);
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return (0);
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case VREG:
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case VLNK:
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default:
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/*
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* Disallow write attempts if the filesystem is
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* mounted read-only.
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*/
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if (vp->v_mount->mnt_flag & MNT_RDONLY)
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return (EROFS);
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}
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}
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return (null_bypass((struct vop_generic_args *)ap));
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}
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/*
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* We handle getattr only to change the fsid.
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*/
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static int
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null_getattr(ap)
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struct vop_getattr_args /* {
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struct vnode *a_vp;
|
|
struct vattr *a_vap;
|
|
struct ucred *a_cred;
|
|
struct thread *a_td;
|
|
} */ *ap;
|
|
{
|
|
int error;
|
|
|
|
if ((error = null_bypass((struct vop_generic_args *)ap)) != 0)
|
|
return (error);
|
|
|
|
ap->a_vap->va_fsid = ap->a_vp->v_mount->mnt_stat.f_fsid.val[0];
|
|
return (0);
|
|
}
|
|
|
|
/*
|
|
* Handle to disallow write access if mounted read-only.
|
|
*/
|
|
static int
|
|
null_access(ap)
|
|
struct vop_access_args /* {
|
|
struct vnode *a_vp;
|
|
int a_mode;
|
|
struct ucred *a_cred;
|
|
struct thread *a_td;
|
|
} */ *ap;
|
|
{
|
|
struct vnode *vp = ap->a_vp;
|
|
mode_t mode = ap->a_mode;
|
|
|
|
/*
|
|
* Disallow write attempts on read-only layers;
|
|
* unless the file is a socket, fifo, or a block or
|
|
* character device resident on the filesystem.
|
|
*/
|
|
if (mode & VWRITE) {
|
|
switch (vp->v_type) {
|
|
case VDIR:
|
|
case VLNK:
|
|
case VREG:
|
|
if (vp->v_mount->mnt_flag & MNT_RDONLY)
|
|
return (EROFS);
|
|
break;
|
|
default:
|
|
break;
|
|
}
|
|
}
|
|
return (null_bypass((struct vop_generic_args *)ap));
|
|
}
|
|
|
|
/*
|
|
* We must handle open to be able to catch MNT_NODEV and friends.
|
|
*/
|
|
static int
|
|
null_open(ap)
|
|
struct vop_open_args /* {
|
|
struct vnode *a_vp;
|
|
int a_mode;
|
|
struct ucred *a_cred;
|
|
struct thread *a_td;
|
|
} */ *ap;
|
|
{
|
|
struct vnode *vp = ap->a_vp;
|
|
struct vnode *lvp = NULLVPTOLOWERVP(ap->a_vp);
|
|
|
|
if ((vp->v_mount->mnt_flag & MNT_NODEV) &&
|
|
(lvp->v_type == VBLK || lvp->v_type == VCHR))
|
|
return ENXIO;
|
|
|
|
return (null_bypass((struct vop_generic_args *)ap));
|
|
}
|
|
|
|
/*
|
|
* We handle this to eliminate null FS to lower FS
|
|
* file moving. Don't know why we don't allow this,
|
|
* possibly we should.
|
|
*/
|
|
static int
|
|
null_rename(ap)
|
|
struct vop_rename_args /* {
|
|
struct vnode *a_fdvp;
|
|
struct vnode *a_fvp;
|
|
struct componentname *a_fcnp;
|
|
struct vnode *a_tdvp;
|
|
struct vnode *a_tvp;
|
|
struct componentname *a_tcnp;
|
|
} */ *ap;
|
|
{
|
|
struct vnode *tdvp = ap->a_tdvp;
|
|
struct vnode *fvp = ap->a_fvp;
|
|
struct vnode *fdvp = ap->a_fdvp;
|
|
struct vnode *tvp = ap->a_tvp;
|
|
|
|
/* Check for cross-device rename. */
|
|
if ((fvp->v_mount != tdvp->v_mount) ||
|
|
(tvp && (fvp->v_mount != tvp->v_mount))) {
|
|
if (tdvp == tvp)
|
|
vrele(tdvp);
|
|
else
|
|
vput(tdvp);
|
|
if (tvp)
|
|
vput(tvp);
|
|
vrele(fdvp);
|
|
vrele(fvp);
|
|
return (EXDEV);
|
|
}
|
|
|
|
return (null_bypass((struct vop_generic_args *)ap));
|
|
}
|
|
|
|
/*
|
|
* We need to process our own vnode lock and then clear the
|
|
* interlock flag as it applies only to our vnode, not the
|
|
* vnodes below us on the stack.
|
|
*/
|
|
static int
|
|
null_lock(ap)
|
|
struct vop_lock_args /* {
|
|
struct vnode *a_vp;
|
|
int a_flags;
|
|
struct thread *a_td;
|
|
} */ *ap;
|
|
{
|
|
struct vnode *vp = ap->a_vp;
|
|
int flags = ap->a_flags;
|
|
struct thread *td = ap->a_td;
|
|
struct vnode *lvp;
|
|
int error;
|
|
|
|
if (flags & LK_THISLAYER) {
|
|
if (vp->v_vnlock != NULL) {
|
|
/* lock is shared across layers */
|
|
if (flags & LK_INTERLOCK)
|
|
mtx_unlock(&vp->v_interlock);
|
|
return 0;
|
|
}
|
|
error = lockmgr(&vp->v_lock, flags & ~LK_THISLAYER,
|
|
&vp->v_interlock, td);
|
|
return (error);
|
|
}
|
|
|
|
if (vp->v_vnlock != NULL) {
|
|
/*
|
|
* The lower level has exported a struct lock to us. Use
|
|
* it so that all vnodes in the stack lock and unlock
|
|
* simultaneously. Note: we don't DRAIN the lock as DRAIN
|
|
* decommissions the lock - just because our vnode is
|
|
* going away doesn't mean the struct lock below us is.
|
|
* LK_EXCLUSIVE is fine.
|
|
*/
|
|
if ((flags & LK_TYPE_MASK) == LK_DRAIN) {
|
|
NULLFSDEBUG("null_lock: avoiding LK_DRAIN\n");
|
|
return(lockmgr(vp->v_vnlock,
|
|
(flags & ~LK_TYPE_MASK) | LK_EXCLUSIVE,
|
|
&vp->v_interlock, td));
|
|
}
|
|
return(lockmgr(vp->v_vnlock, flags, &vp->v_interlock, td));
|
|
} else {
|
|
/*
|
|
* To prevent race conditions involving doing a lookup
|
|
* on "..", we have to lock the lower node, then lock our
|
|
* node. Most of the time it won't matter that we lock our
|
|
* node (as any locking would need the lower one locked
|
|
* first). But we can LK_DRAIN the upper lock as a step
|
|
* towards decomissioning it.
|
|
*/
|
|
lvp = NULLVPTOLOWERVP(vp);
|
|
if (lvp == NULL)
|
|
return (lockmgr(&vp->v_lock, flags, &vp->v_interlock, td));
|
|
if (flags & LK_INTERLOCK) {
|
|
mtx_unlock(&vp->v_interlock);
|
|
flags &= ~LK_INTERLOCK;
|
|
}
|
|
if ((flags & LK_TYPE_MASK) == LK_DRAIN) {
|
|
error = VOP_LOCK(lvp,
|
|
(flags & ~LK_TYPE_MASK) | LK_EXCLUSIVE, td);
|
|
} else
|
|
error = VOP_LOCK(lvp, flags, td);
|
|
if (error)
|
|
return (error);
|
|
error = lockmgr(&vp->v_lock, flags, &vp->v_interlock, td);
|
|
if (error)
|
|
VOP_UNLOCK(lvp, 0, td);
|
|
return (error);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* We need to process our own vnode unlock and then clear the
|
|
* interlock flag as it applies only to our vnode, not the
|
|
* vnodes below us on the stack.
|
|
*/
|
|
static int
|
|
null_unlock(ap)
|
|
struct vop_unlock_args /* {
|
|
struct vnode *a_vp;
|
|
int a_flags;
|
|
struct thread *a_td;
|
|
} */ *ap;
|
|
{
|
|
struct vnode *vp = ap->a_vp;
|
|
int flags = ap->a_flags;
|
|
struct thread *td = ap->a_td;
|
|
struct vnode *lvp;
|
|
|
|
if (vp->v_vnlock != NULL) {
|
|
if (flags & LK_THISLAYER)
|
|
return 0; /* the lock is shared across layers */
|
|
flags &= ~LK_THISLAYER;
|
|
return (lockmgr(vp->v_vnlock, flags | LK_RELEASE,
|
|
&vp->v_interlock, td));
|
|
}
|
|
lvp = NULLVPTOLOWERVP(vp);
|
|
if (lvp == NULL)
|
|
return (lockmgr(&vp->v_lock, flags | LK_RELEASE, &vp->v_interlock, td));
|
|
if ((flags & LK_THISLAYER) == 0) {
|
|
if (flags & LK_INTERLOCK) {
|
|
mtx_unlock(&vp->v_interlock);
|
|
flags &= ~LK_INTERLOCK;
|
|
}
|
|
VOP_UNLOCK(lvp, flags & ~LK_INTERLOCK, td);
|
|
} else
|
|
flags &= ~LK_THISLAYER;
|
|
return (lockmgr(&vp->v_lock, flags | LK_RELEASE, &vp->v_interlock, td));
|
|
}
|
|
|
|
static int
|
|
null_islocked(ap)
|
|
struct vop_islocked_args /* {
|
|
struct vnode *a_vp;
|
|
struct thread *a_td;
|
|
} */ *ap;
|
|
{
|
|
struct vnode *vp = ap->a_vp;
|
|
struct thread *td = ap->a_td;
|
|
|
|
if (vp->v_vnlock != NULL)
|
|
return (lockstatus(vp->v_vnlock, td));
|
|
return (lockstatus(&vp->v_lock, td));
|
|
}
|
|
|
|
/*
|
|
* There is no way to tell that someone issued remove/rmdir operation
|
|
* on the underlying filesystem. For now we just have to release lowevrp
|
|
* as soon as possible.
|
|
*/
|
|
static int
|
|
null_inactive(ap)
|
|
struct vop_inactive_args /* {
|
|
struct vnode *a_vp;
|
|
struct thread *a_td;
|
|
} */ *ap;
|
|
{
|
|
struct vnode *vp = ap->a_vp;
|
|
struct thread *td = ap->a_td;
|
|
|
|
VOP_UNLOCK(vp, 0, td);
|
|
|
|
/*
|
|
* If this is the last reference, then free up the vnode
|
|
* so as not to tie up the lower vnodes.
|
|
*/
|
|
vrecycle(vp, NULL, td);
|
|
|
|
return (0);
|
|
}
|
|
|
|
/*
|
|
* We can free memory in null_inactive, but we do this
|
|
* here. (Possible to guard vp->v_data to point somewhere)
|
|
*/
|
|
static int
|
|
null_reclaim(ap)
|
|
struct vop_reclaim_args /* {
|
|
struct vnode *a_vp;
|
|
struct thread *a_td;
|
|
} */ *ap;
|
|
{
|
|
struct thread *td = ap->a_td;
|
|
struct vnode *vp = ap->a_vp;
|
|
struct null_node *xp = VTONULL(vp);
|
|
struct vnode *lowervp = xp->null_lowervp;
|
|
void *vdata;
|
|
|
|
lockmgr(&null_hashlock, LK_EXCLUSIVE, NULL, td);
|
|
LIST_REMOVE(xp, null_hash);
|
|
lockmgr(&null_hashlock, LK_RELEASE, NULL, td);
|
|
|
|
/*
|
|
* Now it is safe to drop references to the lower vnode.
|
|
* VOP_INACTIVE() will be called by vrele() if necessary.
|
|
*/
|
|
vrele(lowervp);
|
|
vrele(lowervp);
|
|
|
|
vdata = vp->v_data;
|
|
vp->v_data = NULL;
|
|
FREE(vdata, M_NULLFSNODE);
|
|
|
|
return (0);
|
|
}
|
|
|
|
static int
|
|
null_print(ap)
|
|
struct vop_print_args /* {
|
|
struct vnode *a_vp;
|
|
} */ *ap;
|
|
{
|
|
register struct vnode *vp = ap->a_vp;
|
|
printf ("\ttag VT_NULLFS, vp=%p, lowervp=%p\n", vp, NULLVPTOLOWERVP(vp));
|
|
return (0);
|
|
}
|
|
|
|
/*
|
|
* Let an underlying filesystem do the work
|
|
*/
|
|
static int
|
|
null_createvobject(ap)
|
|
struct vop_createvobject_args /* {
|
|
struct vnode *vp;
|
|
struct ucred *cred;
|
|
struct thread *td;
|
|
} */ *ap;
|
|
{
|
|
struct vnode *vp = ap->a_vp;
|
|
struct vnode *lowervp = VTONULL(vp) ? NULLVPTOLOWERVP(vp) : NULL;
|
|
int error;
|
|
|
|
if (vp->v_type == VNON || lowervp == NULL)
|
|
return 0;
|
|
error = VOP_CREATEVOBJECT(lowervp, ap->a_cred, ap->a_td);
|
|
if (error)
|
|
return (error);
|
|
vp->v_flag |= VOBJBUF;
|
|
return (0);
|
|
}
|
|
|
|
/*
|
|
* We have nothing to destroy and this operation shouldn't be bypassed.
|
|
*/
|
|
static int
|
|
null_destroyvobject(ap)
|
|
struct vop_destroyvobject_args /* {
|
|
struct vnode *vp;
|
|
} */ *ap;
|
|
{
|
|
struct vnode *vp = ap->a_vp;
|
|
|
|
vp->v_flag &= ~VOBJBUF;
|
|
return (0);
|
|
}
|
|
|
|
static int
|
|
null_getvobject(ap)
|
|
struct vop_getvobject_args /* {
|
|
struct vnode *vp;
|
|
struct vm_object **objpp;
|
|
} */ *ap;
|
|
{
|
|
struct vnode *lvp = NULLVPTOLOWERVP(ap->a_vp);
|
|
|
|
if (lvp == NULL)
|
|
return EINVAL;
|
|
return (VOP_GETVOBJECT(lvp, ap->a_objpp));
|
|
}
|
|
|
|
/*
|
|
* Global vfs data structures
|
|
*/
|
|
vop_t **null_vnodeop_p;
|
|
static struct vnodeopv_entry_desc null_vnodeop_entries[] = {
|
|
{ &vop_default_desc, (vop_t *) null_bypass },
|
|
|
|
{ &vop_access_desc, (vop_t *) null_access },
|
|
{ &vop_bmap_desc, (vop_t *) vop_eopnotsupp },
|
|
{ &vop_createvobject_desc, (vop_t *) null_createvobject },
|
|
{ &vop_destroyvobject_desc, (vop_t *) null_destroyvobject },
|
|
{ &vop_getattr_desc, (vop_t *) null_getattr },
|
|
{ &vop_getvobject_desc, (vop_t *) null_getvobject },
|
|
{ &vop_getwritemount_desc, (vop_t *) vop_stdgetwritemount},
|
|
{ &vop_inactive_desc, (vop_t *) null_inactive },
|
|
{ &vop_islocked_desc, (vop_t *) null_islocked },
|
|
{ &vop_lock_desc, (vop_t *) null_lock },
|
|
{ &vop_lookup_desc, (vop_t *) null_lookup },
|
|
{ &vop_open_desc, (vop_t *) null_open },
|
|
{ &vop_print_desc, (vop_t *) null_print },
|
|
{ &vop_reclaim_desc, (vop_t *) null_reclaim },
|
|
{ &vop_rename_desc, (vop_t *) null_rename },
|
|
{ &vop_setattr_desc, (vop_t *) null_setattr },
|
|
{ &vop_strategy_desc, (vop_t *) vop_eopnotsupp },
|
|
{ &vop_unlock_desc, (vop_t *) null_unlock },
|
|
{ NULL, NULL }
|
|
};
|
|
static struct vnodeopv_desc null_vnodeop_opv_desc =
|
|
{ &null_vnodeop_p, null_vnodeop_entries };
|
|
|
|
VNODEOP_SET(null_vnodeop_opv_desc);
|