FreeBSD/Linux Kernel Cross Reference
sys/fs/deadfs/dead_vnops.c

     /*
      * Copyright (c) 1989, 1993
      *      The Regents of the University of California.  All rights reserved.
      *
      * 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. All advertising materials mentioning features or use of this software
     *    must display the following acknowledgement:
     *      This product includes software developed by the University of
     *      California, Berkeley and its contributors.
     * 4. 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.
     *
     *      @(#)dead_vnops.c        8.1 (Berkeley) 6/10/93
     * $FreeBSD: releng/5.2/sys/fs/deadfs/dead_vnops.c 111841 2003-03-03 19:15:40Z njl $
     */
    
    #include <sys/param.h>
    #include <sys/systm.h>
    #include <sys/kernel.h>
    #include <sys/lock.h>
    #include <sys/mutex.h>
    #include <sys/poll.h>
    #include <sys/vnode.h>
    
    static int      chkvnlock(struct vnode *);
    /*
     * Prototypes for dead operations on vnodes.
     */
    static int      dead_bmap(struct vop_bmap_args *);
    static int      dead_ioctl(struct vop_ioctl_args *);
    static int      dead_lock(struct vop_lock_args *);
    static int      dead_lookup(struct vop_lookup_args *);
    static int      dead_open(struct vop_open_args *);
    static int      dead_poll(struct vop_poll_args *);
    static int      dead_read(struct vop_read_args *);
    static int      dead_write(struct vop_write_args *);
    
    vop_t **dead_vnodeop_p;
    static struct vnodeopv_entry_desc dead_vnodeop_entries[] = {
            { &vop_default_desc,            (vop_t *) vop_defaultop },
            { &vop_access_desc,             (vop_t *) vop_ebadf },
            { &vop_advlock_desc,            (vop_t *) vop_ebadf },
            { &vop_bmap_desc,               (vop_t *) dead_bmap },
            { &vop_create_desc,             (vop_t *) vop_panic },
            { &vop_getattr_desc,            (vop_t *) vop_ebadf },
            { &vop_inactive_desc,           (vop_t *) vop_null },
            { &vop_ioctl_desc,              (vop_t *) dead_ioctl },
            { &vop_link_desc,               (vop_t *) vop_panic },
            { &vop_lock_desc,               (vop_t *) dead_lock },
            { &vop_lookup_desc,             (vop_t *) dead_lookup },
            { &vop_mkdir_desc,              (vop_t *) vop_panic },
            { &vop_mknod_desc,              (vop_t *) vop_panic },
            { &vop_open_desc,               (vop_t *) dead_open },
            { &vop_pathconf_desc,           (vop_t *) vop_ebadf },  /* per pathconf(2) */
            { &vop_poll_desc,               (vop_t *) dead_poll },
            { &vop_read_desc,               (vop_t *) dead_read },
            { &vop_readdir_desc,            (vop_t *) vop_ebadf },
            { &vop_readlink_desc,           (vop_t *) vop_ebadf },
            { &vop_reclaim_desc,            (vop_t *) vop_null },
            { &vop_remove_desc,             (vop_t *) vop_panic },
            { &vop_rename_desc,             (vop_t *) vop_panic },
            { &vop_rmdir_desc,              (vop_t *) vop_panic },
            { &vop_setattr_desc,            (vop_t *) vop_ebadf },
            { &vop_symlink_desc,            (vop_t *) vop_panic },
            { &vop_write_desc,              (vop_t *) dead_write },
            { NULL, NULL }
    };
    static struct vnodeopv_desc dead_vnodeop_opv_desc =
            { &dead_vnodeop_p, dead_vnodeop_entries };
    
    VNODEOP_SET(dead_vnodeop_opv_desc);
    
    /*
     * Trivial lookup routine that always fails.
     */
    /* ARGSUSED */
    static int
    dead_lookup(ap)
            struct vop_lookup_args /* {
                   struct vnode * a_dvp;
                   struct vnode ** a_vpp;
                   struct componentname * a_cnp;
           } */ *ap;
   {
   
           *ap->a_vpp = NULL;
           return (ENOTDIR);
   }
   
   /*
    * Open always fails as if device did not exist.
    */
   /* ARGSUSED */
   static int
   dead_open(ap)
           struct vop_open_args /* {
                   struct vnode *a_vp;
                   int  a_mode;
                   struct ucred *a_cred;
                   struct proc *a_p;
           } */ *ap;
   {
   
           return (ENXIO);
   }
   
   /*
    * Vnode op for read
    */
   /* ARGSUSED */
   static int
   dead_read(ap)
           struct vop_read_args /* {
                   struct vnode *a_vp;
                   struct uio *a_uio;
                   int  a_ioflag;
                   struct ucred *a_cred;
           } */ *ap;
   {
   
           if (chkvnlock(ap->a_vp))
                   panic("dead_read: lock");
           /*
            * Return EOF for tty devices, EIO for others
            */
           if ((ap->a_vp->v_vflag & VV_ISTTY) == 0)
                   return (EIO);
           return (0);
   }
   
   /*
    * Vnode op for write
    */
   /* ARGSUSED */
   static int
   dead_write(ap)
           struct vop_write_args /* {
                   struct vnode *a_vp;
                   struct uio *a_uio;
                   int  a_ioflag;
                   struct ucred *a_cred;
           } */ *ap;
   {
   
           if (chkvnlock(ap->a_vp))
                   panic("dead_write: lock");
           return (EIO);
   }
   
   /*
    * Device ioctl operation.
    */
   /* ARGSUSED */
   static int
   dead_ioctl(ap)
           struct vop_ioctl_args /* {
                   struct vnode *a_vp;
                   u_long  a_command;
                   caddr_t  a_data;
                   int  a_fflag;
                   struct ucred *a_cred;
                   struct proc *a_p;
           } */ *ap;
   {
   
           if (!chkvnlock(ap->a_vp))
                   return (ENOTTY);
           /* XXX: Doesn't this just recurse back here ? */
           return (VCALL(ap->a_vp, VOFFSET(vop_ioctl), ap));
   }
   
   
   /*
    * Wait until the vnode has finished changing state.
    */
   static int
   dead_lock(ap)
           struct vop_lock_args /* {
                   struct vnode *a_vp;
                   int a_flags;
                   struct proc *a_p;
           } */ *ap;
   {
           struct vnode *vp = ap->a_vp;
   
           /*
            * Since we are not using the lock manager, we must clear
            * the interlock here.
            */
           if (ap->a_flags & LK_INTERLOCK) {
                   mtx_unlock(&vp->v_interlock);
                   ap->a_flags &= ~LK_INTERLOCK;
           }
           if (!chkvnlock(vp))
                   return (0);
           return (VCALL(vp, VOFFSET(vop_lock), ap));
   }
   
   /*
    * Wait until the vnode has finished changing state.
    */
   static int
   dead_bmap(ap)
           struct vop_bmap_args /* {
                   struct vnode *a_vp;
                   daddr_t  a_bn;
                   struct vnode **a_vpp;
                   daddr_t *a_bnp;
                   int *a_runp;
                   int *a_runb;
           } */ *ap;
   {
   
           if (!chkvnlock(ap->a_vp))
                   return (EIO);
           return (VOP_BMAP(ap->a_vp, ap->a_bn, ap->a_vpp, ap->a_bnp, ap->a_runp, ap->a_runb));
   }
   
   /*
    * We have to wait during times when the vnode is
    * in a state of change.
    */
   static int
   chkvnlock(vp)
           register struct vnode *vp;
   {
           int locked = 0;
   
           VI_LOCK(vp);
           while (vp->v_iflag & VI_XLOCK) {
                   vp->v_iflag |= VI_XWANT;
                   (void) msleep((caddr_t)vp, VI_MTX(vp), PINOD, "ckvnlk", 0);
                   locked = 1;
           }
           VI_UNLOCK(vp);
           return (locked);
   }
   
   /*
    * Trivial poll routine that always returns POLLHUP.
    * This is necessary so that a process which is polling a file
    * gets notified when that file is revoke()d.
    */
   static int
   dead_poll(ap)
           struct vop_poll_args *ap;
   {
           return (POLLHUP);
   }

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