path: root/sys/kern/vfs_default.c

/*       $OpenBSD: vfs_default.c,v 1.6 2001/06/22 14:14:10 deraadt Exp $  */


/*
 *    Portions of this code are:
 *
 * Copyright (c) 1989, 1993
 *	The Regents of the University of California.  All rights reserved.
 * (c) UNIX System Laboratories, Inc.
 * All or some portions of this file are derived from material licensed
 * to the University of California by American Telephone and Telegraph
 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
 * the permission of UNIX System Laboratories, Inc.
 *
 * 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.
 */


#include <sys/param.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/mount.h>
#include <sys/vnode.h>
#include <sys/namei.h>
#include <sys/malloc.h>
#include <sys/event.h>
#include <miscfs/specfs/specdev.h>


extern struct simplelock spechash_slock;

int filt_generic_readwrite __P((struct knote *kn, long hint));
void filt_generic_detach __P((struct knote *kn));

/*
 * Eliminate all activity associated with  the requested vnode
 * and with all vnodes aliased to the requested vnode.
 */
int
vop_generic_revoke(v)
	void *v;
{
	struct vop_revoke_args /* {
		struct vnode *a_vp;
		int a_flags;
	} */ *ap = v;
	struct vnode *vp, *vq;
	struct proc *p = curproc;

#ifdef DIAGNOSTIC
	if ((ap->a_flags & REVOKEALL) == 0)
		panic("vop_generic_revoke");
#endif

	vp = ap->a_vp;
	simple_lock(&vp->v_interlock);
 
	if (vp->v_flag & VALIASED) {
		/*
		 * If a vgone (or vclean) is already in progress,
		 * wait until it is done and return.
		 */
		if (vp->v_flag & VXLOCK) {
			vp->v_flag |= VXWANT;
			simple_unlock(&vp->v_interlock);
			tsleep((caddr_t)vp, PINOD, "vop_generic_revokeall", 0);
			return(0);
		}
		/*
		 * Ensure that vp will not be vgone'd while we
		 * are eliminating its aliases.
		 */
		vp->v_flag |= VXLOCK;
		simple_unlock(&vp->v_interlock);
		while (vp->v_flag & VALIASED) {
			simple_lock(&spechash_slock);
			for (vq = *vp->v_hashchain; vq; vq = vq->v_specnext) {
				if (vq->v_rdev != vp->v_rdev ||
				    vq->v_type != vp->v_type || vp == vq)
					continue;
				simple_unlock(&spechash_slock);
				vgone(vq);
				break;
			}
			simple_unlock(&spechash_slock);
		}
		/*
		 * Remove the lock so that vgone below will
		 * really eliminate the vnode after which time
		 * vgone will awaken any sleepers.
		 */
		simple_lock(&vp->v_interlock);
		vp->v_flag &= ~VXLOCK;
	}
	vgonel(vp, p);
	return (0);
}


int
vop_generic_bwrite(v)
	void *v;
{
	struct vop_bwrite_args *ap = v;

	return (bwrite(ap->a_bp));
}


int
vop_generic_abortop(v)
	void *v;
{
	struct vop_abortop_args /* {
		struct vnode *a_dvp;
		struct componentname *a_cnp;
	} */ *ap = v;
 
	if ((ap->a_cnp->cn_flags & (HASBUF | SAVESTART)) == HASBUF)
		FREE(ap->a_cnp->cn_pnbuf, M_NAMEI);
	return (0);
}

/*
 * Stubs to use when there is no locking to be done on the underlying object.
 * A minimal shared lock is necessary to ensure that the underlying object
 * is not revoked while an operation is in progress. So, an active shared
 * count is maintained in an auxillary vnode lock structure.
 */
int
vop_generic_lock(v)
	void *v;
{
	struct vop_lock_args /* {
		struct vnode *a_vp;
		int a_flags;
		struct proc *a_p;
	} */ *ap = v;

#ifdef notyet
	/*
	 * This code cannot be used until all the non-locking filesystems
	 * (notably NFS) are converted to properly lock and release nodes.
	 * Also, certain vnode operations change the locking state within
	 * the operation (create, mknod, remove, link, rename, mkdir, rmdir,
	 * and symlink). Ideally these operations should not change the
	 * lock state, but should be changed to let the caller of the
	 * function unlock them. Otherwise all intermediate vnode layers
	 * (such as union, umapfs, etc) must catch these functions to do
	 * the necessary locking at their layer. Note that the inactive
	 * and lookup operations also change their lock state, but this 
	 * cannot be avoided, so these two operations will always need
	 * to be handled in intermediate layers.
	 */
	struct vnode *vp = ap->a_vp;
	int vnflags, flags = ap->a_flags;

	if (vp->v_vnlock == NULL) {
		if ((flags & LK_TYPE_MASK) == LK_DRAIN)
			return (0);
		MALLOC(vp->v_vnlock, struct lock *, sizeof(struct lock),
		    M_VNODE, M_WAITOK);
		lockinit(vp->v_vnlock, PVFS, "vnlock", 0, 0);
	}
	switch (flags & LK_TYPE_MASK) {
	case LK_DRAIN:
		vnflags = LK_DRAIN;
		break;
	case LK_EXCLUSIVE:
	case LK_SHARED:
		vnflags = LK_SHARED;
		break;
	case LK_UPGRADE:
	case LK_EXCLUPGRADE:
	case LK_DOWNGRADE:
		return (0);
	case LK_RELEASE:
	default:
		panic("vop_generic_lock: bad operation %d", flags & LK_TYPE_MASK);
	}
	if (flags & LK_INTERLOCK)
		vnflags |= LK_INTERLOCK;
	return(lockmgr(vp->v_vnlock, vnflags, &vp->v_interlock, ap->a_p));
#else /* for now */
	/*
	 * Since we are not using the lock manager, we must clear
	 * the interlock here.
	 */
	if (ap->a_flags & LK_INTERLOCK)
		simple_unlock(&ap->a_vp->v_interlock);
	return (0);
#endif
}
 
/*
 * Decrement the active use count.
 */

int
vop_generic_unlock(v)
	void *v;
{
	struct vop_unlock_args /* {
		struct vnode *a_vp;
		int a_flags;
		struct proc *a_p;
	} */ *ap = v;

	struct vnode *vp = ap->a_vp;

	if (vp->v_vnlock == NULL)
		return (0);
	return (lockmgr(vp->v_vnlock, LK_RELEASE, NULL, ap->a_p));
}

/*
 * Return whether or not the node is in use.
 */
int
vop_generic_islocked(v)
	void *v;
{
	struct vop_islocked_args /* {
		struct vnode *a_vp;
	} */ *ap = v;

	struct vnode *vp = ap->a_vp;

	if (vp->v_vnlock == NULL)
		return (0);
	return (lockstatus(vp->v_vnlock));
}

struct filterops generic_filtops = 
	{ 1, NULL, filt_generic_detach, filt_generic_readwrite };

int
vop_generic_kqfilter(v)
	void *v;
{
	struct vop_kqfilter_args /* {
		struct vnode *a_vp;
		struct knote *a_kn;
	} */ *ap = v;
	struct knote *kn = ap->a_kn;

	switch (kn->kn_filter) {
	case EVFILT_READ:
	case EVFILT_WRITE:
		kn->kn_fop = &generic_filtops;
		break;
	default:
		return (1);
	}

	return (0);
}

void
filt_generic_detach(struct knote *kn)
{
}

int
filt_generic_readwrite(struct knote *kn, long hint)
{
	/*
	 * filesystem is gone, so set the EOF flag and schedule 
	 * the knote for deletion.
	 */
	if (hint == NOTE_REVOKE) {
		kn->kn_flags |= (EV_EOF | EV_ONESHOT);
		return (1);
	}

        kn->kn_data = 0;
        return (1);
}