union_vnops.c

来自「早期freebsd实现」· C语言 代码 · 共 1,496 行 · 第 1/3 页

				(void) VOP_OPEN(un->un_uppervp, FREAD, cred, p);
			}
			un->un_openl = 0;

			if (error == 0)
				error = VOP_OPEN(un->un_uppervp, mode, cred, p);
			return (error);
		}

		/*
		 * Just open the lower vnode
		 */
		un->un_openl++;
		VOP_LOCK(tvp);
		error = VOP_OPEN(tvp, mode, cred, p);
		VOP_UNLOCK(tvp);

		return (error);
	}

	FIXUP(un);

	error = VOP_OPEN(tvp, mode, cred, p);

	return (error);
}

int
union_close(ap)
	struct vop_close_args /* {
		struct vnode *a_vp;
		int  a_fflag;
		struct ucred *a_cred;
		struct proc *a_p;
	} */ *ap;
{
	struct union_node *un = VTOUNION(ap->a_vp);
	struct vnode *vp;

	if (un->un_uppervp) {
		vp = un->un_uppervp;
	} else {
#ifdef UNION_DIAGNOSTIC
		if (un->un_openl <= 0)
			panic("union: un_openl cnt");
#endif
		--un->un_openl;
		vp = un->un_lowervp;
	}

	return (VOP_CLOSE(vp, ap->a_fflag, ap->a_cred, ap->a_p));
}

/*
 * Check access permission on the union vnode.
 * The access check being enforced is to check
 * against both the underlying vnode, and any
 * copied vnode.  This ensures that no additional
 * file permissions are given away simply because
 * the user caused an implicit file copy.
 */
int
union_access(ap)
	struct vop_access_args /* {
		struct vnodeop_desc *a_desc;
		struct vnode *a_vp;
		int a_mode;
		struct ucred *a_cred;
		struct proc *a_p;
	} */ *ap;
{
	struct union_node *un = VTOUNION(ap->a_vp);
	int error = EACCES;
	struct vnode *vp;

	if (vp = un->un_uppervp) {
		FIXUP(un);
		return (VOP_ACCESS(vp, ap->a_mode, ap->a_cred, ap->a_p));
	}

	if (vp = un->un_lowervp) {
		VOP_LOCK(vp);
		error = VOP_ACCESS(vp, ap->a_mode, ap->a_cred, ap->a_p);
		if (error == 0) {
			struct union_mount *um = MOUNTTOUNIONMOUNT(vp->v_mount);

			if (um->um_op == UNMNT_BELOW)
				error = VOP_ACCESS(vp, ap->a_mode,
						um->um_cred, ap->a_p);
		}
		VOP_UNLOCK(vp);
		if (error)
			return (error);
	}

	return (error);
}

/*
 *  We handle getattr only to change the fsid.
 */
int
union_getattr(ap)
	struct vop_getattr_args /* {
		struct vnode *a_vp;
		struct vattr *a_vap;
		struct ucred *a_cred;
		struct proc *a_p;
	} */ *ap;
{
	int error;
	struct union_node *un = VTOUNION(ap->a_vp);
	struct vnode *vp = un->un_uppervp;
	struct vattr *vap;
	struct vattr va;


	/*
	 * Some programs walk the filesystem hierarchy by counting
	 * links to directories to avoid stat'ing all the time.
	 * This means the link count on directories needs to be "correct".
	 * The only way to do that is to call getattr on both layers
	 * and fix up the link count.  The link count will not necessarily
	 * be accurate but will be large enough to defeat the tree walkers.
	 */

	vap = ap->a_vap;

	vp = un->un_uppervp;
	if (vp != NULLVP) {
		FIXUP(un);
		error = VOP_GETATTR(vp, vap, ap->a_cred, ap->a_p);
		if (error)
			return (error);
	}

	if (vp == NULLVP) {
		vp = un->un_lowervp;
	} else if (vp->v_type == VDIR) {
		vp = un->un_lowervp;
		vap = &va;
	} else {
		vp = NULLVP;
	}

	if (vp != NULLVP) {
		VOP_LOCK(vp);
		error = VOP_GETATTR(vp, vap, ap->a_cred, ap->a_p);
		VOP_UNLOCK(vp);
		if (error)
			return (error);
	}

	if ((vap != ap->a_vap) && (vap->va_type == VDIR))
		ap->a_vap->va_nlink += vap->va_nlink;

	vap->va_fsid = ap->a_vp->v_mount->mnt_stat.f_fsid.val[0];
	return (0);
}

int
union_setattr(ap)
	struct vop_setattr_args /* {
		struct vnode *a_vp;
		struct vattr *a_vap;
		struct ucred *a_cred;
		struct proc *a_p;
	} */ *ap;
{
	struct union_node *un = VTOUNION(ap->a_vp);
	int error;

	/*
	 * Handle case of truncating lower object to zero size,
	 * by creating a zero length upper object.  This is to
	 * handle the case of open with O_TRUNC and O_CREAT.
	 */
	if ((un->un_uppervp == NULLVP) &&
	    /* assert(un->un_lowervp != NULLVP) */
	    (un->un_lowervp->v_type == VREG) &&
	    (ap->a_vap->va_size == 0)) {
		struct vnode *vp;

		error = union_vn_create(&vp, un, ap->a_p);
		if (error)
			return (error);

		/* at this point, uppervp is locked */
		union_newupper(un, vp);

		VOP_UNLOCK(vp);
		union_vn_close(un->un_uppervp, FWRITE, ap->a_cred, ap->a_p);
		VOP_LOCK(vp);
		un->un_flags |= UN_ULOCK;
	}

	/*
	 * Try to set attributes in upper layer,
	 * otherwise return read-only filesystem error.
	 */
	if (un->un_uppervp != NULLVP) {
		FIXUP(un);
		error = VOP_SETATTR(un->un_uppervp, ap->a_vap,
					ap->a_cred, ap->a_p);
	} else {
		error = EROFS;
	}

	return (error);
}

int
union_read(ap)
	struct vop_read_args /* {
		struct vnode *a_vp;
		struct uio *a_uio;
		int  a_ioflag;
		struct ucred *a_cred;
	} */ *ap;
{
	int error;
	struct vnode *vp = OTHERVP(ap->a_vp);
	int dolock = (vp == LOWERVP(ap->a_vp));

	if (dolock)
		VOP_LOCK(vp);
	else
		FIXUP(VTOUNION(ap->a_vp));
	error = VOP_READ(vp, ap->a_uio, ap->a_ioflag, ap->a_cred);
	if (dolock)
		VOP_UNLOCK(vp);

	return (error);
}

int
union_write(ap)
	struct vop_read_args /* {
		struct vnode *a_vp;
		struct uio *a_uio;
		int  a_ioflag;
		struct ucred *a_cred;
	} */ *ap;
{
	int error;
	struct vnode *vp = OTHERVP(ap->a_vp);
	int dolock = (vp == LOWERVP(ap->a_vp));

	if (dolock)
		VOP_LOCK(vp);
	else
		FIXUP(VTOUNION(ap->a_vp));
	error = VOP_WRITE(vp, ap->a_uio, ap->a_ioflag, ap->a_cred);
	if (dolock)
		VOP_UNLOCK(vp);

	return (error);
}

int
union_ioctl(ap)
	struct vop_ioctl_args /* {
		struct vnode *a_vp;
		int  a_command;
		caddr_t  a_data;
		int  a_fflag;
		struct ucred *a_cred;
		struct proc *a_p;
	} */ *ap;
{

	return (VOP_IOCTL(OTHERVP(ap->a_vp), ap->a_command, ap->a_data,
				ap->a_fflag, ap->a_cred, ap->a_p));
}

int
union_select(ap)
	struct vop_select_args /* {
		struct vnode *a_vp;
		int  a_which;
		int  a_fflags;
		struct ucred *a_cred;
		struct proc *a_p;
	} */ *ap;
{

	return (VOP_SELECT(OTHERVP(ap->a_vp), ap->a_which, ap->a_fflags,
				ap->a_cred, ap->a_p));
}

int
union_mmap(ap)
	struct vop_mmap_args /* {
		struct vnode *a_vp;
		int  a_fflags;
		struct ucred *a_cred;
		struct proc *a_p;
	} */ *ap;
{

	return (VOP_MMAP(OTHERVP(ap->a_vp), ap->a_fflags,
				ap->a_cred, ap->a_p));
}

int
union_fsync(ap)
	struct vop_fsync_args /* {
		struct vnode *a_vp;
		struct ucred *a_cred;
		int  a_waitfor;
		struct proc *a_p;
	} */ *ap;
{
	int error = 0;
	struct vnode *targetvp = OTHERVP(ap->a_vp);

	if (targetvp) {
		int dolock = (targetvp == LOWERVP(ap->a_vp));

		if (dolock)
			VOP_LOCK(targetvp);
		else
			FIXUP(VTOUNION(ap->a_vp));
		error = VOP_FSYNC(targetvp, ap->a_cred,
					ap->a_waitfor, ap->a_p);
		if (dolock)
			VOP_UNLOCK(targetvp);
	}

	return (error);
}

int
union_seek(ap)
	struct vop_seek_args /* {
		struct vnode *a_vp;
		off_t  a_oldoff;
		off_t  a_newoff;
		struct ucred *a_cred;
	} */ *ap;
{

	return (VOP_SEEK(OTHERVP(ap->a_vp), ap->a_oldoff, ap->a_newoff, ap->a_cred));
}

int
union_remove(ap)
	struct vop_remove_args /* {
		struct vnode *a_dvp;
		struct vnode *a_vp;
		struct componentname *a_cnp;
	} */ *ap;
{
	int error;
	struct union_node *dun = VTOUNION(ap->a_dvp);
	struct union_node *un = VTOUNION(ap->a_vp);

	if (dun->un_uppervp && un->un_uppervp) {
		struct vnode *dvp = dun->un_uppervp;
		struct vnode *vp = un->un_uppervp;

		FIXUP(dun);
		VREF(dvp);
		dun->un_flags |= UN_KLOCK;
		vput(ap->a_dvp);
		FIXUP(un);
		VREF(vp);
		un->un_flags |= UN_KLOCK;
		vput(ap->a_vp);

		error = VOP_REMOVE(dvp, vp, ap->a_cnp);
		if (!error)
			union_removed_upper(un);

		/*
		 * XXX: should create a whiteout here
		 */
	} else {
		/*
		 * XXX: should create a whiteout here
		 */
		vput(ap->a_dvp);
		vput(ap->a_vp);
		error = EROFS;
	}

	return (error);
}

int
union_link(ap)
	struct vop_link_args /* {
		struct vnode *a_vp;
		struct vnode *a_tdvp;
		struct componentname *a_cnp;
	} */ *ap;
{
	int error;
	struct union_node *dun = VTOUNION(ap->a_vp);
	struct union_node *un = VTOUNION(ap->a_tdvp);

	if (dun->un_uppervp && un->un_uppervp) {
		struct vnode *dvp = dun->un_uppervp;
		struct vnode *vp = un->un_uppervp;

		FIXUP(dun);
		VREF(dvp);
		dun->un_flags |= UN_KLOCK;
		vput(ap->a_vp);
		FIXUP(un);
		VREF(vp);
		vrele(ap->a_tdvp);

		error = VOP_LINK(dvp, vp, ap->a_cnp);
	} else {
		/*
		 * XXX: need to copy to upper layer
		 * and do the link there.
		 */
		vput(ap->a_vp);
		vrele(ap->a_tdvp);
		error = EROFS;
	}

	return (error);
}

int
union_rename(ap)
	struct vop_rename_args  /* {
		struct vnode *a_fdvp;
		struct vnode *a_fvp;
		struct componentname *a_fcnp;
		struct vnode *a_tdvp;
		struct vnode *a_tvp;
		struct componentname *a_tcnp;
	} */ *ap;
{
	int error;

	struct vnode *fdvp = ap->a_fdvp;
	struct vnode *fvp = ap->a_fvp;
	struct vnode *tdvp = ap->a_tdvp;
	struct vnode *tvp = ap->a_tvp;

	if (fdvp->v_op == union_vnodeop_p) {	/* always true */
		struct union_node *un = VTOUNION(fdvp);
		if (un->un_uppervp == NULLVP) {
			error = EROFS;
			goto bad;
		}

		FIXUP(un);
		fdvp = un->un_uppervp;
		VREF(fdvp);
		vrele(ap->a_fdvp);
	}

	if (fvp->v_op == union_vnodeop_p) {	/* always true */
		struct union_node *un = VTOUNION(fvp);
		if (un->un_uppervp == NULLVP) {
			error = EROFS;
			goto bad;
		}

		FIXUP(un);
		fvp = un->un_uppervp;
		VREF(fvp);
		vrele(ap->a_fvp);
	}

	if (tdvp->v_op == union_vnodeop_p) {
		struct union_node *un = VTOUNION(tdvp);
		if (un->un_uppervp == NULLVP) {
			error = EROFS;
			goto bad;
		}

		tdvp = un->un_uppervp;
		VREF(tdvp);
		un->un_flags |= UN_KLOCK;
		vput(ap->a_tdvp);
	}

	if (tvp && tvp->v_op == union_vnodeop_p) {
		struct union_node *un = VTOUNION(tvp);
		if (un->un_uppervp == NULLVP) {
			error = EROFS;
			goto bad;
		}

		tvp = un->un_uppervp;
		VREF(tvp);
		un->un_flags |= UN_KLOCK;
		vput(ap->a_tvp);
	}

	return (VOP_RENAME(fdvp, fvp, ap->a_fcnp, tdvp, tvp, ap->a_tcnp));