sys/vfs/deadfs/dead_vnops.c

   1 /*
   2  * Copyright (c) 1989, 1993
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. Neither the name of the University nor the names of its contributors
  14  *    may be used to endorse or promote products derived from this software
  15  *    without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  *
  29  *      @(#)dead_vnops.c        8.1 (Berkeley) 6/10/93
  30  * $FreeBSD: src/sys/miscfs/deadfs/dead_vnops.c,v 1.26 1999/08/28 00:46:42 peter Exp $
  31  * $DragonFly: src/sys/vfs/deadfs/dead_vnops.c,v 1.20 2007/08/13 17:31:56 dillon Exp $
  32  */
  33
  34 #include <sys/param.h>
  35 #include <sys/systm.h>
  36 #include <sys/kernel.h>
  37 #include <sys/lock.h>
  38 #include <sys/vnode.h>
  39 #include <sys/fcntl.h>
  40 #include <sys/buf.h>
  41
  42 /*
  43  * Prototypes for dead operations on vnodes.
  44  */
  45 static int      dead_badop (void);
  46 static int      dead_bmap (struct vop_bmap_args *);
  47 static int      dead_ioctl (struct vop_ioctl_args *);
  48 static int      dead_lookup (struct vop_old_lookup_args *);
  49 static int      dead_open (struct vop_open_args *);
  50 static int      dead_close (struct vop_close_args *);
  51 static int      dead_print (struct vop_print_args *);
  52 static int      dead_read (struct vop_read_args *);
  53 static int      dead_write (struct vop_write_args *);
  54
  55 struct vop_ops dead_vnode_vops = {
  56         .vop_default =          vop_defaultop,
  57         .vop_access =           (void *)vop_ebadf,
  58         .vop_advlock =          (void *)vop_ebadf,
  59         .vop_bmap =             dead_bmap,
  60         .vop_old_create =       (void *)dead_badop,
  61         .vop_getattr =          (void *)vop_ebadf,
  62         .vop_inactive =         (void *)vop_null,
  63         .vop_ioctl =            dead_ioctl,
  64         .vop_old_link =         (void *)dead_badop,
  65         .vop_old_lookup =       dead_lookup,
  66         .vop_old_mkdir =        (void *)dead_badop,
  67         .vop_old_mknod =        (void *)dead_badop,
  68         .vop_mmap =             (void *)dead_badop,
  69         .vop_open =             dead_open,
  70         .vop_close =            dead_close,
  71         .vop_pathconf =         (void *)vop_ebadf,      /* per pathconf(2) */
  72         .vop_print =            dead_print,
  73         .vop_read =             dead_read,
  74         .vop_readdir =          (void *)vop_ebadf,
  75         .vop_readlink =         (void *)vop_ebadf,
  76         .vop_reclaim =          (void *)vop_null,
  77         .vop_old_remove =       (void *)dead_badop,
  78         .vop_old_rename =       (void *)dead_badop,
  79         .vop_old_rmdir =        (void *)dead_badop,
  80         .vop_setattr =          (void *)vop_ebadf,
  81         .vop_old_symlink =      (void *)dead_badop,
  82         .vop_write =            dead_write
  83 };
  84
  85 struct vop_ops *dead_vnode_vops_p = &dead_vnode_vops;
  86
  87 VNODEOP_SET(dead_vnode_vops);
  88
  89 /*
  90  * Trivial lookup routine that always fails.
  91  *
  92  * dead_lookup(struct vnode *a_dvp, struct vnode **a_vpp,
  93  *             struct componentname *a_cnp)
  94  */
  95 /* ARGSUSED */
  96 static int
  97 dead_lookup(struct vop_old_lookup_args *ap)
  98 {
  99         *ap->a_vpp = NULL;
 100         return (ENOTDIR);
 101 }
 102
 103 /*
 104  * Open always fails as if device did not exist.
 105  *
 106  * dead_open(struct vnode *a_vp, int a_mode, struct ucred *a_cred,
 107  *           struct proc *a_p)
 108  */
 109 /* ARGSUSED */
 110 static int
 111 dead_open(struct vop_open_args *ap)
 112 {
 113         return (ENXIO);
 114 }
 115
 116 /*
 117  * Close always succeeds, and does not warn or panic if v_opencount or
 118  * v_writecount is incorrect, because a forced unmount or revocation
 119  * might have closed the file out from under the descriptor.
 120  */
 121 static int
 122 dead_close(struct vop_close_args *ap)
 123 {
 124         struct vnode *vp = ap->a_vp;
 125
 126         vn_lock(vp, LK_UPGRADE | LK_RETRY);     /* safety */
 127         if (vp->v_opencount > 0) {
 128                 if ((ap->a_fflag & FWRITE) && vp->v_writecount > 0)
 129                         atomic_add_int(&vp->v_writecount, -1);
 130                 atomic_add_int(&vp->v_opencount, -1);
 131         }
 132         return (0);
 133 }
 134
 135 /*
 136  * Vnode op for read
 137  *
 138  * dead_read(struct vnode *a_vp, struct uio *a_uio, int a_ioflag,
 139  *           struct ucred *a_cred)
 140  */
 141 /* ARGSUSED */
 142 static int
 143 dead_read(struct vop_read_args *ap)
 144 {
 145         /*
 146          * Return EOF for tty devices, EIO for others
 147          */
 148         if ((ap->a_vp->v_flag & VISTTY) == 0)
 149                 return (EIO);
 150         return (0);
 151 }
 152
 153 /*
 154  * Vnode op for write
 155  *
 156  * dead_write(struct vnode *a_vp, struct uio *a_uio, int a_ioflag,
 157  *            struct ucred *a_cred)
 158  */
 159 /* ARGSUSED */
 160 static int
 161 dead_write(struct vop_write_args *ap)
 162 {
 163         return (EIO);
 164 }
 165
 166 /*
 167  * Device ioctl operation.
 168  *
 169  * dead_ioctl(struct vnode *a_vp, int a_command, caddr_t a_data, int a_fflag,
 170  *            struct ucred *a_cred, struct proc *a_p)
 171  */
 172 /* ARGSUSED */
 173 static int
 174 dead_ioctl(struct vop_ioctl_args *ap)
 175 {
 176         return (ENOTTY);
 177 }
 178
 179 /*
 180  * Wait until the vnode has finished changing state.
 181  *
 182  * dead_bmap(struct vnode *a_vp, off_t a_loffset,
 183  *           off_t *a_doffsetp, int *a_runp, int *a_runb)
 184  */
 185 static int
 186 dead_bmap(struct vop_bmap_args *ap)
 187 {
 188         return (EIO);
 189 }
 190
 191 /*
 192  * Print out the contents of a dead vnode.
 193  *
 194  * dead_print(struct vnode *a_vp)
 195  */
 196 /* ARGSUSED */
 197 static int
 198 dead_print(struct vop_print_args *ap)
 199 {
 200         kprintf("tag VT_NON, dead vnode\n");
 201         return (0);
 202 }
 203
 204 /*
 205  * Empty vnode bad operation
 206  */
 207 static int
 208 dead_badop(void)
 209 {
 210         panic("dead_badop called");
 211         /* NOTREACHED */
 212 }