sys/miscfs/genfs/layer.h

   1 /*      $NetBSD: layer.h,v 1.12 2007/10/10 20:42:28 ad Exp $    */
   2
   3 /*
   4  * Copyright (c) 1999 National Aeronautics & Space Administration
   5  * All rights reserved.
   6  *
   7  * This software was written by William Studenmund of the
   8  * Numerical Aerospace Simulation Facility, NASA Ames Research Center.
   9  *
  10  * Redistribution and use in source and binary forms, with or without
  11  * modification, are permitted provided that the following conditions
  12  * are met:
  13  * 1. Redistributions of source code must retain the above copyright
  14  *    notice, this list of conditions and the following disclaimer.
  15  * 2. Redistributions in binary form must reproduce the above copyright
  16  *    notice, this list of conditions and the following disclaimer in the
  17  *    documentation and/or other materials provided with the distribution.
  18  * 3. Neither the name of the National Aeronautics & Space Administration
  19  *    nor the names of its contributors may be used to endorse or promote
  20  *    products derived from this software without specific prior written
  21  *    permission.
  22  *
  23  * THIS SOFTWARE IS PROVIDED BY THE NATIONAL AERONAUTICS & SPACE ADMINISTRATION
  24  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
  25  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  26  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE ADMINISTRATION OR CONTRIB-
  27  * UTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
  28  * OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  29  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  30  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  31  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  32  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  33  * POSSIBILITY OF SUCH DAMAGE.
  34  */
  35
  36 /*
  37  * Copyright (c) 1992, 1993
  38  *      The Regents of the University of California.  All rights reserved.
  39  *
  40  * This code is derived from software donated to Berkeley by
  41  * Jan-Simon Pendry.
  42  *
  43  * Redistribution and use in source and binary forms, with or without
  44  * modification, are permitted provided that the following conditions
  45  * are met:
  46  * 1. Redistributions of source code must retain the above copyright
  47  *    notice, this list of conditions and the following disclaimer.
  48  * 2. Redistributions in binary form must reproduce the above copyright
  49  *    notice, this list of conditions and the following disclaimer in the
  50  *    documentation and/or other materials provided with the distribution.
  51  * 3. Neither the name of the University nor the names of its contributors
  52  *    may be used to endorse or promote products derived from this software
  53  *    without specific prior written permission.
  54  *
  55  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  56  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  57  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  58  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  59  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  60  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  61  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  62  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  63  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  64  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  65  * SUCH DAMAGE.
  66  *
  67  *      from: Id: lofs.h,v 1.8 1992/05/30 10:05:43 jsp Exp
  68  *      @(#)null.h      8.2 (Berkeley) 1/21/94
  69  */
  70
  71 #ifndef _MISCFS_GENFS_LAYER_H_
  72 #define _MISCFS_GENFS_LAYER_H_
  73
  74 struct layer_args {
  75         char    *target;                /* Target of loopback  */
  76         struct export_args30 _pad1; /* compat with old userland tools */
  77 };
  78
  79 #ifdef _KERNEL
  80
  81 struct layer_node;
  82
  83 LIST_HEAD(layer_node_hashhead, layer_node);
  84
  85 struct layer_mount {
  86         struct mount            *layerm_vfs;
  87         struct vnode            *layerm_rootvp; /* Ref to root layer_node */
  88         u_int                   layerm_flags;   /* mount point layer flags */
  89         u_int                   layerm_size;    /* size of fs's struct node */
  90         enum vtype              layerm_tag;     /* vtag of our vnodes */
  91         int                             /* bypass routine for this mount */
  92                                 (*layerm_bypass)(void *);
  93         int                     (*layerm_alloc) /* alloc a new layer node */
  94                                 (struct mount *, struct vnode *,
  95                                                 struct vnode **);
  96         int                     (**layerm_vnodeop_p)    /* ops for our nodes */
  97                                 (void *);
  98         struct layer_node_hashhead      /* head of hash list for layer_nodes */
  99                                 *layerm_node_hashtbl;
 100         u_long                  layerm_node_hash; /* hash mask for hash chain */
 101         kmutex_t                layerm_hashlock; /* interlock for hash chain. */
 102 };
 103
 104 #define LAYERFS_MFLAGS          0x00000fff      /* reserved layer mount flags */
 105 #define LAYERFS_MBYPASSDEBUG    0x00000001
 106
 107 /*
 108  * A cache of vnode references
 109  */
 110 struct layer_node {
 111         LIST_ENTRY(layer_node)  layer_hash;     /* Hash list */
 112         struct vnode            *layer_lowervp; /* VREFed once */
 113         struct vnode            *layer_vnode;   /* Back pointer */
 114         unsigned int            layer_flags;    /* locking, etc. */
 115 };
 116
 117 #define LAYERFS_RESFLAGS        0x00000fff      /* flags reserved for layerfs */
 118 #define LAYERFS_REMOVED         0x00000001      /* Did a remove on this node */
 119
 120 /*
 121  * The following macros handle upperfs-specific locking. They are needed
 122  * when the lowerfs does not export a struct lock for locking use by the
 123  * upper layers. These macros are inteded for adjusting the upperfs
 124  * struct lock to reflect changes in the underlying vnode's lock state.
 125  */
 126 #define LAYERFS_UPPERLOCK(v, f, r)      do { \
 127         if ((v)->v_vnlock == NULL) \
 128                 r = vlockmgr(&(v)->v_lock, (f)); \
 129         else \
 130                 r = 0; \
 131         } while (0)
 132
 133 #define LAYERFS_UPPERUNLOCK(v, f, r)    do { \
 134         if ((v)->v_vnlock == NULL) \
 135             r = vlockmgr(&(v)->v_lock, (f) | LK_RELEASE); \
 136         else \
 137                 r = 0; \
 138         } while (0)
 139
 140 #define LAYERFS_UPPERISLOCKED(v, r)     do { \
 141         if ((v)->v_vnlock == NULL) \
 142                 r = vlockstatus(&(v)->v_lock); \
 143         else \
 144                 r = -1; \
 145         } while (0)
 146
 147 #define LAYERFS_DO_BYPASS(vp, ap)       \
 148         (*MOUNTTOLAYERMOUNT((vp)->v_mount)->layerm_bypass)((ap))
 149
 150 struct vnode *layer_checkvp(struct vnode *vp, const char *fil, int lno);
 151
 152 #define MOUNTTOLAYERMOUNT(mp) ((struct layer_mount *)((mp)->mnt_data))
 153 #define VTOLAYER(vp) ((struct layer_node *)(vp)->v_data)
 154 #define LAYERTOV(xp) ((xp)->layer_vnode)
 155 #ifdef LAYERFS_DIAGNOSTIC
 156 #define LAYERVPTOLOWERVP(vp) layer_checkvp((vp), __FILE__, __LINE__)
 157 extern int layerfs_debug;
 158 #else
 159 #define LAYERVPTOLOWERVP(vp) (VTOLAYER(vp)->layer_lowervp)
 160 #endif
 161
 162 #endif /* _KERNEL */
 163 #endif /* _MISCFS_GENFS_LAYER_H_ */