1cbbd625cc
if one of the new poll types is requested; hopefully this will not break any existing code. (This is done so that programs have a dependable way of determining whether a filesystem supports the extended poll types or not.) The new poll types added are: POLLWRITE - file contents may have been modified POLLNLINK - file was linked, unlinked, or renamed POLLATTRIB - file's attributes may have been changed POLLEXTEND - file was extended Note that the internal operation of poll() means that it is impossible for two processes to reliably poll for the same event (this could be fixed but may not be worth it), so it is not possible to rewrite `tail -f' to use poll at this time.
306 lines
7.4 KiB
C
306 lines
7.4 KiB
C
/*
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* Copyright (c) 1989, 1993
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* The Regents of the University of California. All rights reserved.
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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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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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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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* @(#)dead_vnops.c 8.1 (Berkeley) 6/10/93
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* $Id: dead_vnops.c,v 1.22 1997/12/05 19:55:41 bde Exp $
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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/kernel.h>
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#include <sys/lock.h>
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#include <sys/vnode.h>
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#include <sys/buf.h>
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#include <sys/poll.h>
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static int chkvnlock __P((struct vnode *));
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/*
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* Prototypes for dead operations on vnodes.
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*/
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static int dead_badop __P((void));
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static int dead_bmap __P((struct vop_bmap_args *));
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static int dead_ioctl __P((struct vop_ioctl_args *));
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static int dead_lock __P((struct vop_lock_args *));
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static int dead_lookup __P((struct vop_lookup_args *));
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static int dead_open __P((struct vop_open_args *));
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static int dead_poll __P((struct vop_poll_args *));
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static int dead_print __P((struct vop_print_args *));
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static int dead_read __P((struct vop_read_args *));
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static int dead_write __P((struct vop_write_args *));
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vop_t **dead_vnodeop_p;
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static struct vnodeopv_entry_desc dead_vnodeop_entries[] = {
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{ &vop_default_desc, (vop_t *) vop_defaultop },
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{ &vop_access_desc, (vop_t *) vop_ebadf },
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{ &vop_advlock_desc, (vop_t *) vop_ebadf },
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{ &vop_bmap_desc, (vop_t *) dead_bmap },
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{ &vop_create_desc, (vop_t *) dead_badop },
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{ &vop_getattr_desc, (vop_t *) vop_ebadf },
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{ &vop_inactive_desc, (vop_t *) vop_null },
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{ &vop_ioctl_desc, (vop_t *) dead_ioctl },
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{ &vop_link_desc, (vop_t *) dead_badop },
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{ &vop_lock_desc, (vop_t *) dead_lock },
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{ &vop_lookup_desc, (vop_t *) dead_lookup },
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{ &vop_mkdir_desc, (vop_t *) dead_badop },
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{ &vop_mknod_desc, (vop_t *) dead_badop },
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{ &vop_mmap_desc, (vop_t *) dead_badop },
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{ &vop_open_desc, (vop_t *) dead_open },
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{ &vop_pathconf_desc, (vop_t *) vop_ebadf }, /* per pathconf(2) */
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{ &vop_poll_desc, (vop_t *) dead_poll },
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{ &vop_print_desc, (vop_t *) dead_print },
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{ &vop_read_desc, (vop_t *) dead_read },
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{ &vop_readdir_desc, (vop_t *) vop_ebadf },
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{ &vop_readlink_desc, (vop_t *) vop_ebadf },
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{ &vop_reclaim_desc, (vop_t *) vop_null },
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{ &vop_remove_desc, (vop_t *) dead_badop },
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{ &vop_rename_desc, (vop_t *) dead_badop },
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{ &vop_rmdir_desc, (vop_t *) dead_badop },
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{ &vop_setattr_desc, (vop_t *) vop_ebadf },
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{ &vop_symlink_desc, (vop_t *) dead_badop },
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{ &vop_write_desc, (vop_t *) dead_write },
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{ NULL, NULL }
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};
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static struct vnodeopv_desc dead_vnodeop_opv_desc =
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{ &dead_vnodeop_p, dead_vnodeop_entries };
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VNODEOP_SET(dead_vnodeop_opv_desc);
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/*
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* Trivial lookup routine that always fails.
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*/
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/* ARGSUSED */
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static int
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dead_lookup(ap)
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struct vop_lookup_args /* {
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struct vnode * a_dvp;
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struct vnode ** a_vpp;
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struct componentname * a_cnp;
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} */ *ap;
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{
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*ap->a_vpp = NULL;
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return (ENOTDIR);
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}
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/*
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* Open always fails as if device did not exist.
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*/
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/* ARGSUSED */
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static int
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dead_open(ap)
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struct vop_open_args /* {
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struct vnode *a_vp;
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int a_mode;
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struct ucred *a_cred;
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struct proc *a_p;
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} */ *ap;
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{
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return (ENXIO);
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}
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/*
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* Vnode op for read
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*/
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/* ARGSUSED */
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static int
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dead_read(ap)
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struct vop_read_args /* {
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struct vnode *a_vp;
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struct uio *a_uio;
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int a_ioflag;
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struct ucred *a_cred;
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} */ *ap;
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{
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if (chkvnlock(ap->a_vp))
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panic("dead_read: lock");
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#if 0
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/* Lite2 behaviour */
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/*
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* Return EOF for tty devices, EIO for others
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*/
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if ((ap->a_vp->v_flag & VISTTY) == 0)
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return (EIO);
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#else
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/*
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* Return EOF for character devices, EIO for others
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*/
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if (ap->a_vp->v_type != VCHR)
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return (EIO);
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#endif
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return (0);
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}
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/*
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* Vnode op for write
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*/
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/* ARGSUSED */
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static int
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dead_write(ap)
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struct vop_write_args /* {
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struct vnode *a_vp;
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struct uio *a_uio;
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int a_ioflag;
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struct ucred *a_cred;
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} */ *ap;
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{
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if (chkvnlock(ap->a_vp))
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panic("dead_write: lock");
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return (EIO);
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}
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/*
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* Device ioctl operation.
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*/
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/* ARGSUSED */
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static int
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dead_ioctl(ap)
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struct vop_ioctl_args /* {
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struct vnode *a_vp;
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int a_command;
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caddr_t a_data;
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int a_fflag;
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struct ucred *a_cred;
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struct proc *a_p;
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} */ *ap;
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{
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if (!chkvnlock(ap->a_vp))
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return (EBADF);
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return (VCALL(ap->a_vp, VOFFSET(vop_ioctl), ap));
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}
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/*
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* Wait until the vnode has finished changing state.
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*/
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static int
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dead_lock(ap)
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struct vop_lock_args /* {
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struct vnode *a_vp;
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int a_flags;
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struct proc *a_p;
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} */ *ap;
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{
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struct vnode *vp = ap->a_vp;
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/*
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* Since we are not using the lock manager, we must clear
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* the interlock here.
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*/
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if (ap->a_flags & LK_INTERLOCK) {
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simple_unlock(&vp->v_interlock);
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ap->a_flags &= ~LK_INTERLOCK;
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}
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if (!chkvnlock(vp))
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return (0);
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return (VCALL(vp, VOFFSET(vop_lock), ap));
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}
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/*
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* Wait until the vnode has finished changing state.
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*/
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static int
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dead_bmap(ap)
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struct vop_bmap_args /* {
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struct vnode *a_vp;
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daddr_t a_bn;
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struct vnode **a_vpp;
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daddr_t *a_bnp;
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int *a_runp;
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int *a_runb;
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} */ *ap;
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{
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if (!chkvnlock(ap->a_vp))
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return (EIO);
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return (VOP_BMAP(ap->a_vp, ap->a_bn, ap->a_vpp, ap->a_bnp, ap->a_runp, ap->a_runb));
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}
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/*
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* Print out the contents of a dead vnode.
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*/
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/* ARGSUSED */
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static int
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dead_print(ap)
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struct vop_print_args /* {
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struct vnode *a_vp;
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} */ *ap;
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{
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printf("tag VT_NON, dead vnode\n");
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return (0);
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}
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/*
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* Empty vnode bad operation
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*/
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static int
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dead_badop()
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{
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panic("dead_badop called");
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/* NOTREACHED */
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}
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/*
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* We have to wait during times when the vnode is
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* in a state of change.
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*/
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int
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chkvnlock(vp)
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register struct vnode *vp;
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{
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int locked = 0;
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while (vp->v_flag & VXLOCK) {
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vp->v_flag |= VXWANT;
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(void) tsleep((caddr_t)vp, PINOD, "ckvnlk", 0);
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locked = 1;
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}
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return (locked);
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}
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/*
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* Trivial poll routine that always returns POLLHUP.
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* This is necessary so that a process which is polling a file
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* gets notified when that file is revoke()d.
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*/
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static int
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dead_poll(ap)
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struct vop_poll_args *ap;
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{
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return (POLLHUP);
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}
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