FreeBSD/Linux Kernel Cross Reference
sys/fs/nullfs/null.h

     /*-
      * SPDX-License-Identifier: BSD-3-Clause
      *
      * Copyright (c) 1992, 1993
      *      The Regents of the University of California.  All rights reserved.
      *
      * This code is derived from software donated to Berkeley by
      * Jan-Simon Pendry.
      *
     * Redistribution and use in source and binary forms, with or without
     * modification, are permitted provided that the following conditions
     * are met:
     * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     * 3. Neither the name of the University nor the names of its contributors
     *    may be used to endorse or promote products derived from this software
     *    without specific prior written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     *
     *      @(#)null.h      8.3 (Berkeley) 8/20/94
     *
     * $FreeBSD$
     */
    
    #ifndef FS_NULL_H
    #define FS_NULL_H
    
    #define NULLM_CACHE     0x0001
    
    struct null_mount {
            struct mount    *nullm_vfs;
            struct vnode    *nullm_lowerrootvp;     /* Ref to lower root vnode */
            uint64_t        nullm_flags;
            struct mount_upper_node upper_node;
            struct mount_upper_node notify_node;
    };
    
    #ifdef _KERNEL
    /*
     * A cache of vnode references
     */
    struct null_node {
            LIST_ENTRY(null_node)   null_hash;      /* Hash list */
            struct vnode            *null_lowervp;  /* VREFed once */
            struct vnode            *null_vnode;    /* Back pointer */
            u_int                   null_flags;
    };
    
    #define NULLV_NOUNLOCK  0x0001
    #define NULLV_DROP      0x0002
    
    #define MOUNTTONULLMOUNT(mp) ((struct null_mount *)((mp)->mnt_data))
    #define VTONULL(vp) ((struct null_node *)(vp)->v_data)
    #define NULLTOV(xp) ((xp)->null_vnode)
    
    int nullfs_init(struct vfsconf *vfsp);
    int nullfs_uninit(struct vfsconf *vfsp);
    int null_nodeget(struct mount *mp, struct vnode *target, struct vnode **vpp);
    struct vnode *null_hashget(struct mount *mp, struct vnode *lowervp);
    void null_hashrem(struct null_node *xp);
    int null_bypass(struct vop_generic_args *ap);
    
    #ifdef DIAGNOSTIC
    struct vnode *null_checkvp(struct vnode *vp, char *fil, int lno);
    #define NULLVPTOLOWERVP(vp) null_checkvp((vp), __FILE__, __LINE__)
    #else
    #define NULLVPTOLOWERVP(vp) (VTONULL(vp)->null_lowervp)
    #endif
    
    extern struct vop_vector null_vnodeops;
    
    #ifdef MALLOC_DECLARE
    MALLOC_DECLARE(M_NULLFSNODE);
    #endif
    
    #ifdef NULLFS_DEBUG
    #define NULLFSDEBUG(format, args...) printf(format ,## args)
    #else
    #define NULLFSDEBUG(format, args...)
    #endif /* NULLFS_DEBUG */
    
    #endif /* _KERNEL */
    
    #endif

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