750 lines
21 KiB
C
750 lines
21 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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* 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 a 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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/*
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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(struct vop_generic_args *ap)
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{
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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_vnodeops)) {
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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(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]), 0);
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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_nodeget(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(struct vop_lookup_args *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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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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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_nodeget(dvp->v_mount, lvp, &vp);
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if (error) {
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/* XXX Cleanup needed... */
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panic("null_nodeget failed");
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}
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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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static int
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null_open(struct vop_open_args *ap)
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{
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int retval;
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struct vnode *vp, *ldvp;
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vp = ap->a_vp;
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ldvp = NULLVPTOLOWERVP(vp);
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retval = null_bypass(&ap->a_gen);
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if (retval == 0)
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vp->v_object = ldvp->v_object;
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return (retval);
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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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static int
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null_setattr(struct vop_setattr_args *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(struct vop_getattr_args *ap)
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{
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int error;
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if ((error = null_bypass((struct vop_generic_args *)ap)) != 0)
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return (error);
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ap->a_vap->va_fsid = ap->a_vp->v_mount->mnt_stat.f_fsid.val[0];
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return (0);
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}
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/*
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* Handle to disallow write access if mounted read-only.
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*/
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static int
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null_access(struct vop_access_args *ap)
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{
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struct vnode *vp = ap->a_vp;
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mode_t mode = ap->a_mode;
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/*
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* Disallow write attempts on read-only layers;
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* unless the file is a socket, fifo, or a block or
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* character device resident on the filesystem.
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*/
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if (mode & VWRITE) {
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switch (vp->v_type) {
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case VDIR:
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case VLNK:
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case VREG:
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if (vp->v_mount->mnt_flag & MNT_RDONLY)
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return (EROFS);
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break;
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default:
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break;
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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 this to eliminate null FS to lower FS
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* file moving. Don't know why we don't allow this,
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* possibly we should.
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*/
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static int
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null_rename(struct vop_rename_args *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(struct vop_lock1_args *ap)
|
|
{
|
|
struct vnode *vp = ap->a_vp;
|
|
int flags = ap->a_flags;
|
|
struct null_node *nn;
|
|
struct vnode *lvp;
|
|
int error;
|
|
|
|
|
|
if ((flags & LK_INTERLOCK) == 0) {
|
|
VI_LOCK(vp);
|
|
ap->a_flags = flags |= LK_INTERLOCK;
|
|
}
|
|
nn = VTONULL(vp);
|
|
/*
|
|
* If we're still active we must ask the lower layer to
|
|
* lock as ffs has special lock considerations in it's
|
|
* vop lock.
|
|
*/
|
|
if (nn != NULL && (lvp = NULLVPTOLOWERVP(vp)) != NULL) {
|
|
VI_LOCK_FLAGS(lvp, MTX_DUPOK);
|
|
VI_UNLOCK(vp);
|
|
/*
|
|
* We have to hold the vnode here to solve a potential
|
|
* reclaim race. If we're forcibly vgone'd while we
|
|
* still have refs, a thread could be sleeping inside
|
|
* the lowervp's vop_lock routine. When we vgone we will
|
|
* drop our last ref to the lowervp, which would allow it
|
|
* to be reclaimed. The lowervp could then be recycled,
|
|
* in which case it is not legal to be sleeping in it's VOP.
|
|
* We prevent it from being recycled by holding the vnode
|
|
* here.
|
|
*/
|
|
vholdl(lvp);
|
|
error = VOP_LOCK(lvp, flags);
|
|
|
|
/*
|
|
* We might have slept to get the lock and someone might have
|
|
* clean our vnode already, switching vnode lock from one in
|
|
* lowervp to v_lock in our own vnode structure. Handle this
|
|
* case by reacquiring correct lock in requested mode.
|
|
*/
|
|
if (VTONULL(vp) == NULL && error == 0) {
|
|
ap->a_flags &= ~(LK_TYPE_MASK | LK_INTERLOCK);
|
|
switch (flags & LK_TYPE_MASK) {
|
|
case LK_SHARED:
|
|
ap->a_flags |= LK_SHARED;
|
|
break;
|
|
case LK_UPGRADE:
|
|
case LK_EXCLUSIVE:
|
|
ap->a_flags |= LK_EXCLUSIVE;
|
|
break;
|
|
default:
|
|
panic("Unsupported lock request %d\n",
|
|
ap->a_flags);
|
|
}
|
|
VOP_UNLOCK(lvp, 0);
|
|
error = vop_stdlock(ap);
|
|
}
|
|
vdrop(lvp);
|
|
} else
|
|
error = vop_stdlock(ap);
|
|
|
|
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(struct vop_unlock_args *ap)
|
|
{
|
|
struct vnode *vp = ap->a_vp;
|
|
int flags = ap->a_flags;
|
|
int mtxlkflag = 0;
|
|
struct null_node *nn;
|
|
struct vnode *lvp;
|
|
int error;
|
|
|
|
if ((flags & LK_INTERLOCK) != 0)
|
|
mtxlkflag = 1;
|
|
else if (mtx_owned(VI_MTX(vp)) == 0) {
|
|
VI_LOCK(vp);
|
|
mtxlkflag = 2;
|
|
}
|
|
nn = VTONULL(vp);
|
|
if (nn != NULL && (lvp = NULLVPTOLOWERVP(vp)) != NULL) {
|
|
VI_LOCK_FLAGS(lvp, MTX_DUPOK);
|
|
flags |= LK_INTERLOCK;
|
|
vholdl(lvp);
|
|
VI_UNLOCK(vp);
|
|
error = VOP_UNLOCK(lvp, flags);
|
|
vdrop(lvp);
|
|
if (mtxlkflag == 0)
|
|
VI_LOCK(vp);
|
|
} else {
|
|
if (mtxlkflag == 2)
|
|
VI_UNLOCK(vp);
|
|
error = vop_stdunlock(ap);
|
|
}
|
|
|
|
return (error);
|
|
}
|
|
|
|
static int
|
|
null_islocked(struct vop_islocked_args *ap)
|
|
{
|
|
struct vnode *vp = ap->a_vp;
|
|
|
|
return (lockstatus(vp->v_vnlock));
|
|
}
|
|
|
|
/*
|
|
* There is no way to tell that someone issued remove/rmdir operation
|
|
* on the underlying filesystem. For now we just have to release lowervp
|
|
* as soon as possible.
|
|
*
|
|
* Note, we can't release any resources nor remove vnode from hash before
|
|
* appropriate VXLOCK stuff is is done because other process can find this
|
|
* vnode in hash during inactivation and may be sitting in vget() and waiting
|
|
* for null_inactive to unlock vnode. Thus we will do all those in VOP_RECLAIM.
|
|
*/
|
|
static int
|
|
null_inactive(struct vop_inactive_args *ap)
|
|
{
|
|
struct vnode *vp = ap->a_vp;
|
|
struct thread *td = ap->a_td;
|
|
|
|
vp->v_object = NULL;
|
|
|
|
/*
|
|
* If this is the last reference, then free up the vnode
|
|
* so as not to tie up the lower vnodes.
|
|
*/
|
|
vrecycle(vp, td);
|
|
|
|
return (0);
|
|
}
|
|
|
|
/*
|
|
* Now, the VXLOCK is in force and we're free to destroy the null vnode.
|
|
*/
|
|
static int
|
|
null_reclaim(struct vop_reclaim_args *ap)
|
|
{
|
|
struct vnode *vp = ap->a_vp;
|
|
struct null_node *xp = VTONULL(vp);
|
|
struct vnode *lowervp = xp->null_lowervp;
|
|
struct lock *vnlock;
|
|
|
|
if (lowervp)
|
|
null_hashrem(xp);
|
|
/*
|
|
* Use the interlock to protect the clearing of v_data to
|
|
* prevent faults in null_lock().
|
|
*/
|
|
VI_LOCK(vp);
|
|
vp->v_data = NULL;
|
|
vp->v_object = NULL;
|
|
vnlock = vp->v_vnlock;
|
|
vp->v_vnlock = &vp->v_lock;
|
|
if (lowervp) {
|
|
lockmgr(vp->v_vnlock, LK_EXCLUSIVE | LK_INTERLOCK, VI_MTX(vp));
|
|
vput(lowervp);
|
|
} else
|
|
panic("null_reclaim: reclaiming a node with no lowervp");
|
|
FREE(xp, M_NULLFSNODE);
|
|
|
|
return (0);
|
|
}
|
|
|
|
static int
|
|
null_print(struct vop_print_args *ap)
|
|
{
|
|
struct vnode *vp = ap->a_vp;
|
|
|
|
printf("\tvp=%p, lowervp=%p\n", vp, NULLVPTOLOWERVP(vp));
|
|
return (0);
|
|
}
|
|
|
|
/* ARGSUSED */
|
|
static int
|
|
null_getwritemount(struct vop_getwritemount_args *ap)
|
|
{
|
|
struct null_node *xp;
|
|
struct vnode *lowervp;
|
|
struct vnode *vp;
|
|
|
|
vp = ap->a_vp;
|
|
VI_LOCK(vp);
|
|
xp = VTONULL(vp);
|
|
if (xp && (lowervp = xp->null_lowervp)) {
|
|
VI_LOCK_FLAGS(lowervp, MTX_DUPOK);
|
|
VI_UNLOCK(vp);
|
|
vholdl(lowervp);
|
|
VI_UNLOCK(lowervp);
|
|
VOP_GETWRITEMOUNT(lowervp, ap->a_mpp);
|
|
vdrop(lowervp);
|
|
} else {
|
|
VI_UNLOCK(vp);
|
|
*(ap->a_mpp) = NULL;
|
|
}
|
|
return (0);
|
|
}
|
|
|
|
static int
|
|
null_vptofh(struct vop_vptofh_args *ap)
|
|
{
|
|
struct vnode *lvp;
|
|
|
|
lvp = NULLVPTOLOWERVP(ap->a_vp);
|
|
return VOP_VPTOFH(lvp, ap->a_fhp);
|
|
}
|
|
|
|
/*
|
|
* Global vfs data structures
|
|
*/
|
|
struct vop_vector null_vnodeops = {
|
|
.vop_bypass = null_bypass,
|
|
.vop_access = null_access,
|
|
.vop_bmap = VOP_EOPNOTSUPP,
|
|
.vop_getattr = null_getattr,
|
|
.vop_getwritemount = null_getwritemount,
|
|
.vop_inactive = null_inactive,
|
|
.vop_islocked = null_islocked,
|
|
.vop_lock1 = null_lock,
|
|
.vop_lookup = null_lookup,
|
|
.vop_open = null_open,
|
|
.vop_print = null_print,
|
|
.vop_reclaim = null_reclaim,
|
|
.vop_rename = null_rename,
|
|
.vop_setattr = null_setattr,
|
|
.vop_strategy = VOP_EOPNOTSUPP,
|
|
.vop_unlock = null_unlock,
|
|
.vop_vptofh = null_vptofh,
|
|
};
|