From 4eee8de77cb0ff65f6c3b454e5c7523e489bb586 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Dag-Erling=20Sm=C3=B8rgrav?= <des@FreeBSD.org>
Date: Wed, 31 Jul 2002 12:19:49 +0000
Subject: [PATCH] Introduce struct xvnode, which will be used instead of struct
 vnode for sysctl purposes.  Also add two fields to struct vnode, v_cachedfs
 and v_cachedid, which hold the vnode's device and file id and are filled in
 by vn_open_cred() and vn_stat().

Sponsored by:	DARPA, NAI Labs
---
 sys/kern/vfs_vnops.c |  7 +++++++
 sys/sys/vnode.h      | 32 ++++++++++++++++++++++++++++++++
 2 files changed, 39 insertions(+)

diff --git a/sys/kern/vfs_vnops.c b/sys/kern/vfs_vnops.c
index 218dd723cd3b..c759196196c7 100644
--- a/sys/kern/vfs_vnops.c
+++ b/sys/kern/vfs_vnops.c
@@ -209,6 +209,10 @@ vn_open_cred(ndp, flagp, cmode, cred)
 				goto bad;
 		}
 	}
+	if ((error = VOP_GETATTR(vp, vap, cred, td)) == 0) {
+		vp->v_cachedfs = vap->va_fsid;
+		vp->v_cachedid = vap->va_fileid;
+	}
 	if ((error = VOP_OPEN(vp, fmode, cred, td)) != 0)
 		goto bad;
 	/*
@@ -567,6 +571,9 @@ vn_stat(vp, sb, td)
 	if (error)
 		return (error);
 
+	vp->v_cachedfs = vap->va_fsid;
+	vp->v_cachedid = vap->va_fileid;
+
 	/*
 	 * Zero the spare stat fields
 	 */
diff --git a/sys/sys/vnode.h b/sys/sys/vnode.h
index 6f1857c07d3e..524483625c4c 100644
--- a/sys/sys/vnode.h
+++ b/sys/sys/vnode.h
@@ -146,6 +146,8 @@ struct vnode {
 	const char *filename;			/* Source file doing locking */
 	int line;				/* Line number doing locking */
 #endif
+	udev_t	v_cachedfs;			/* cached fs id */
+	ino_t	v_cachedid;			/* cached file id */
 };
 #define	v_mountedhere	v_un.vu_mountedhere
 #define	v_socket	v_un.vu_socket
@@ -153,6 +155,36 @@ struct vnode {
 #define	v_specnext	v_un.vu_spec.vu_specnext
 #define	v_fifoinfo	v_un.vu_fifoinfo
 
+/*
+ * Userland version of struct vnode, for sysctl.
+ */
+struct xvnode {
+	size_t	xv_size;			/* sizeof(struct xvnode) */
+	void	*xv_vnode;			/* address of real vnode */
+	u_long	xv_flag;			/* vnode flags */
+	int	xv_usecount;			/* reference count of users */
+	int	xv_writecount;			/* reference count of writers */
+	int	xv_holdcnt;			/* page & buffer references */
+	u_long	xv_id;				/* capability identifier */
+	void	*xv_mount;			/* address of parent mount */
+	long	xv_numoutput;			/* num of writes in progress */
+	enum	vtype xv_type;			/* vnode type */
+	union {
+		void	*xvu_socket;		/* socket, if VSOCK */
+		void	*xvu_fifo;		/* fifo, if VFIFO */
+		udev_t	xvu_rdev;		/* maj/min, if VBLK/VCHR */
+		struct {
+			udev_t	xvu_dev;	/* device, if VDIR/VREG/VLNK */
+			ino_t	xvu_ino;	/* id, if VDIR/VREG/VLNK */
+		};
+	} xv_un;
+};
+#define xv_socket	xv_un.xvu_socket
+#define xv_fifo		xv_un.xvu_fifo
+#define xv_rdev		xv_un.xvu_rdev
+#define xv_dev		xv_un.xvu_dev
+#define xv_ino		xv_un.xvu_ino
+
 #define	VN_POLLEVENT(vp, events)				\
 	do {							\
 		if ((vp)->v_pollinfo != NULL && 		\