sys/kern/vfs_default.c

/*
 * Copyright (c) 1989, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed
 * to Berkeley by John Heidemann of the UCLA Ficus project.
 *
 * Source: * @(#)i405_init.c 2.10 92/04/27 UCLA Ficus project
 *
 * 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/kernel.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/unistd.h>
#include <sys/vnode.h>
#include <sys/poll.h>

static int vop_nostrategy __P((struct vop_strategy_args *));

/*
 * This vnode table stores what we want to do if the filesystem doesn't
 * implement a particular VOP.
 *
 * If there is no specific entry here, we will return EOPNOTSUPP.
 *
 */

vop_t **default_vnodeop_p;
static struct vnodeopv_entry_desc default_vnodeop_entries[] = {
	{ &vop_default_desc,		(vop_t *) vop_eopnotsupp },
	{ &vop_abortop_desc,		(vop_t *) vop_null },
	{ &vop_advlock_desc,		(vop_t *) vop_einval },
	{ &vop_bwrite_desc,		(vop_t *) vop_stdbwrite },
	{ &vop_close_desc,		(vop_t *) vop_null },
	{ &vop_fsync_desc,		(vop_t *) vop_null },
	{ &vop_ioctl_desc,		(vop_t *) vop_enotty },
	{ &vop_islocked_desc,		(vop_t *) vop_noislocked },
	{ &vop_lease_desc,		(vop_t *) vop_null },
	{ &vop_lock_desc,		(vop_t *) vop_nolock },
	{ &vop_mmap_desc,		(vop_t *) vop_einval },
	{ &vop_open_desc,		(vop_t *) vop_null },
	{ &vop_pathconf_desc,		(vop_t *) vop_einval },
	{ &vop_poll_desc,		(vop_t *) vop_nopoll },
	{ &vop_readlink_desc,		(vop_t *) vop_einval },
	{ &vop_reallocblks_desc,	(vop_t *) vop_eopnotsupp },
	{ &vop_revoke_desc,		(vop_t *) vop_revoke },
	{ &vop_strategy_desc,		(vop_t *) vop_nostrategy },
	{ &vop_unlock_desc,		(vop_t *) vop_nounlock },
	{ NULL, NULL }
};

static struct vnodeopv_desc default_vnodeop_opv_desc =
        { &default_vnodeop_p, default_vnodeop_entries };

VNODEOP_SET(default_vnodeop_opv_desc);

int
vop_eopnotsupp(struct vop_generic_args *ap)
{
	/*
	printf("vop_notsupp[%s]\n", ap->a_desc->vdesc_name);
	*/

	return (EOPNOTSUPP);
}

int
vop_ebadf(struct vop_generic_args *ap)
{

	return (EBADF);
}

int
vop_enotty(struct vop_generic_args *ap)
{

	return (ENOTTY);
}

int
vop_einval(struct vop_generic_args *ap)
{

	return (EINVAL);
}

int
vop_null(struct vop_generic_args *ap)
{

	return (0);
}

int
vop_defaultop(struct vop_generic_args *ap)
{

	return (VOCALL(default_vnodeop_p, ap->a_desc->vdesc_offset, ap));
}

int
vop_panic(struct vop_generic_args *ap)
{

	panic("illegal vnode op called");
}

static int
vop_nostrategy (struct vop_strategy_args *ap)
{
	printf("No strategy for buffer at %p\n", ap->a_bp);
	vprint("", ap->a_vp);
	vprint("", ap->a_bp->b_vp);
	ap->a_bp->b_flags |= B_ERROR;
	ap->a_bp->b_error = EOPNOTSUPP;
	biodone(ap->a_bp);
	return (EOPNOTSUPP);
}

int
vop_stdpathconf(ap)
	struct vop_pathconf_args /* {
	struct vnode *a_vp;
	int a_name;
	int *a_retval;
	} */ *ap;
{

	switch (ap->a_name) {
		case _PC_LINK_MAX:
			*ap->a_retval = LINK_MAX;
			return (0);
		case _PC_MAX_CANON:
			*ap->a_retval = MAX_CANON;
			return (0);
		case _PC_MAX_INPUT:
			*ap->a_retval = MAX_INPUT;
			return (0);
		case _PC_PIPE_BUF:
			*ap->a_retval = PIPE_BUF;
			return (0);
		case _PC_CHOWN_RESTRICTED:
			*ap->a_retval = 1;
			return (0);
		case _PC_VDISABLE:
			*ap->a_retval = _POSIX_VDISABLE;
			return (0);
		default:
			return (EINVAL);
	}
	/* NOTREACHED */
}

/*
 * Standard lock, unlock and islocked functions.
 *
 * These depend on the lock structure being the first element in the
 * inode, ie: vp->v_data points to the the lock!
 */
int
vop_stdlock(ap)
	struct vop_lock_args /* {
		struct vnode *a_vp;
		int a_flags;
		struct proc *a_p;
	} */ *ap;
{
	struct lock *l;

	if ((l = (struct lock *)ap->a_vp->v_data) == NULL) {
		if (ap->a_flags & LK_INTERLOCK)
			simple_unlock(&ap->a_vp->v_interlock);
		return 0;
	}

	return (lockmgr(l, ap->a_flags, &ap->a_vp->v_interlock, ap->a_p));
}

int
vop_stdunlock(ap)
	struct vop_unlock_args /* {
		struct vnode *a_vp;
		int a_flags;
		struct proc *a_p;
	} */ *ap;
{
	struct lock *l;

	if ((l = (struct lock *)ap->a_vp->v_data) == NULL) {
		if (ap->a_flags & LK_INTERLOCK)
			simple_unlock(&ap->a_vp->v_interlock);
		return 0;
	}

	return (lockmgr(l, ap->a_flags | LK_RELEASE, &ap->a_vp->v_interlock,
	    ap->a_p));
}

int
vop_stdislocked(ap)
	struct vop_islocked_args /* {
		struct vnode *a_vp;
	} */ *ap;
{
	struct lock *l;

	if ((l = (struct lock *)ap->a_vp->v_data) == NULL)
		return 0;

	return (lockstatus(l));
}

/*
 * Return true for select/poll.
 */
int
vop_nopoll(ap)
	struct vop_poll_args /* {
		struct vnode *a_vp;
		int  a_events;
		struct ucred *a_cred;
		struct proc *a_p;
	} */ *ap;
{
	/*
	 * Return true for read/write.  If the user asked for something
	 * special, return POLLNVAL, so that clients have a way of
	 * determining reliably whether or not the extended
	 * functionality is present without hard-coding knowledge
	 * of specific filesystem implementations.
	 */
	if (ap->a_events & ~POLLSTANDARD)
		return (POLLNVAL);

	return (ap->a_events & (POLLIN | POLLOUT | POLLRDNORM | POLLWRNORM));
}

/*
 * Implement poll for local filesystems that support it.
 */
int
vop_stdpoll(ap)
	struct vop_poll_args /* {
		struct vnode *a_vp;
		int  a_events;
		struct ucred *a_cred;
		struct proc *a_p;
	} */ *ap;
{
	if ((ap->a_events & ~POLLSTANDARD) == 0)
		return (ap->a_events & (POLLRDNORM|POLLWRNORM));
	return (vn_pollrecord(ap->a_vp, ap->a_p, ap->a_events));
}

int
vop_stdbwrite(ap)
	struct vop_bwrite_args *ap;
{
	return (bwrite(ap->a_bp));
}

/*
 * 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_sharedlock(ap)
	struct vop_lock_args /* {
		struct vnode *a_vp;
		int a_flags;
		struct proc *a_p;
	} */ *ap;
{
	/*
	 * 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, LK_NOPAUSE);
	}
	switch (flags & LK_TYPE_MASK) {
	case LK_DRAIN:
		vnflags = LK_DRAIN;
		break;
	case LK_EXCLUSIVE:
#ifdef DEBUG_VFS_LOCKS
		/*
		 * Normally, we use shared locks here, but that confuses
		 * the locking assertions.
		 */
		vnflags = LK_EXCLUSIVE;
		break;
#endif
	case LK_SHARED:
		vnflags = LK_SHARED;
		break;
	case LK_UPGRADE:
	case LK_EXCLUPGRADE:
	case LK_DOWNGRADE:
		return (0);
	case LK_RELEASE:
	default:
		panic("vop_sharedlock: 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));
}

/*
 * 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_nolock(ap)
	struct vop_lock_args /* {
		struct vnode *a_vp;
		int a_flags;
		struct proc *a_p;
	} */ *ap;
{
#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, LK_NOPAUSE);
	}
	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_nolock: 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
}

/*
 * Do the inverse of vop_nolock, handling the interlock in a compatible way.
 */
int
vop_nounlock(ap)
	struct vop_unlock_args /* {
		struct vnode *a_vp;
		int a_flags;
		struct proc *a_p;
	} */ *ap;
{
	struct vnode *vp = ap->a_vp;

	if (vp->v_vnlock == NULL) {
		if (ap->a_flags & LK_INTERLOCK)
			simple_unlock(&ap->a_vp->v_interlock);
		return (0);
	}
	return (lockmgr(vp->v_vnlock, LK_RELEASE | ap->a_flags,
		&ap->a_vp->v_interlock, ap->a_p));
}

/*
 * Return whether or not the node is in use.
 */
int
vop_noislocked(ap)
	struct vop_islocked_args /* {
		struct vnode *a_vp;
	} */ *ap;
{
	struct vnode *vp = ap->a_vp;

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