1 files changed, 293 insertions, 0 deletions
diff --git a/sys/miscfs/nullfs/null_subr.c b/sys/miscfs/nullfs/null_subr.c
new file mode 100644
index 000000000000..a31723fe4c22
--- /dev/null
+++ b/sys/miscfs/nullfs/null_subr.c
@@ -0,0 +1,293 @@
+/*
+ * Copyright (c) 1992, 1993
+ *	The Regents of the University of California.  All rights reserved.
+ *
+ * This code is derived from software donated to Berkeley by
+ * Jan-Simon Pendry.
+ *
+ * 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.
+ *
+ *	@(#)null_subr.c	8.4 (Berkeley) 1/21/94
+ *
+ * $Id: lofs_subr.c,v 1.11 1992/05/30 10:05:43 jsp Exp jsp $
+ */
+
+#include <sys/param.h>
+#include <sys/systm.h>
+#include <sys/time.h>
+#include <sys/types.h>
+#include <sys/vnode.h>
+#include <sys/mount.h>
+#include <sys/namei.h>
+#include <sys/malloc.h>
+#include <miscfs/nullfs/null.h>
+
+#define LOG2_SIZEVNODE 7		/* log2(sizeof struct vnode) */
+#define	NNULLNODECACHE 16
+#define	NULL_NHASH(vp) ((((u_long)vp)>>LOG2_SIZEVNODE) & (NNULLNODECACHE-1))
+
+/*
+ * Null layer cache:
+ * Each cache entry holds a reference to the lower vnode
+ * along with a pointer to the alias vnode.  When an
+ * entry is added the lower vnode is VREF'd.  When the
+ * alias is removed the lower vnode is vrele'd.
+ */
+
+/*
+ * Cache head
+ */
+struct null_node_cache {
+	struct null_node	*ac_forw;
+	struct null_node	*ac_back;
+};
+
+static struct null_node_cache null_node_cache[NNULLNODECACHE];
+
+/*
+ * Initialise cache headers
+ */
+nullfs_init()
+{
+	struct null_node_cache *ac;
+#ifdef NULLFS_DIAGNOSTIC
+	printf("nullfs_init\n");		/* printed during system boot */
+#endif
+
+	for (ac = null_node_cache; ac < null_node_cache + NNULLNODECACHE; ac++)
+		ac->ac_forw = ac->ac_back = (struct null_node *) ac;
+}
+
+/*
+ * Compute hash list for given lower vnode
+ */
+static struct null_node_cache *
+null_node_hash(lowervp)
+struct vnode *lowervp;
+{
+
+	return (&null_node_cache[NULL_NHASH(lowervp)]);
+}
+
+/*
+ * Return a VREF'ed alias for lower vnode if already exists, else 0.
+ */
+static struct vnode *
+null_node_find(mp, lowervp)
+	struct mount *mp;
+	struct vnode *lowervp;
+{
+	struct null_node_cache *hd;
+	struct null_node *a;
+	struct vnode *vp;
+
+	/*
+	 * Find hash base, and then search the (two-way) linked
+	 * list looking for a null_node structure which is referencing
+	 * the lower vnode.  If found, the increment the null_node
+	 * reference count (but NOT the lower vnode's VREF counter).
+	 */
+	hd = null_node_hash(lowervp);
+loop:
+	for (a = hd->ac_forw; a != (struct null_node *) hd; a = a->null_forw) {
+		if (a->null_lowervp == lowervp && NULLTOV(a)->v_mount == mp) {
+			vp = NULLTOV(a);
+			/*
+			 * We need vget for the VXLOCK
+			 * stuff, but we don't want to lock
+			 * the lower node.
+			 */
+			if (vget(vp, 0)) {
+				printf ("null_node_find: vget failed.\n");
+				goto loop;
+			};
+			return (vp);
+		}
+	}
+
+	return NULL;
+}
+
+
+/*
+ * Make a new null_node node.
+ * Vp is the alias vnode, lofsvp is the lower vnode.
+ * Maintain a reference to (lowervp).
+ */
+static int
+null_node_alloc(mp, lowervp, vpp)
+	struct mount *mp;
+	struct vnode *lowervp;
+	struct vnode **vpp;
+{
+	struct null_node_cache *hd;
+	struct null_node *xp;
+	struct vnode *othervp, *vp;
+	int error;
+
+	if (error = getnewvnode(VT_NULL, mp, null_vnodeop_p, vpp))
+		return (error);
+	vp = *vpp;
+
+	MALLOC(xp, struct null_node *, sizeof(struct null_node), M_TEMP, M_WAITOK);
+	vp->v_type = lowervp->v_type;
+	xp->null_vnode = vp;
+	vp->v_data = xp;
+	xp->null_lowervp = lowervp;
+	/*
+	 * Before we insert our new node onto the hash chains,
+	 * check to see if someone else has beaten us to it.
+	 * (We could have slept in MALLOC.)
+	 */
+	if (othervp = null_node_find(lowervp)) {
+		FREE(xp, M_TEMP);
+		vp->v_type = VBAD;	/* node is discarded */
+		vp->v_usecount = 0;	/* XXX */
+		*vpp = othervp;
+		return 0;
+	};
+	VREF(lowervp);   /* Extra VREF will be vrele'd in null_node_create */
+	hd = null_node_hash(lowervp);
+	insque(xp, hd);
+	return 0;
+}
+
+
+/*
+ * Try to find an existing null_node vnode refering
+ * to it, otherwise make a new null_node vnode which
+ * contains a reference to the lower vnode.
+ */
+int
+null_node_create(mp, lowervp, newvpp)
+	struct mount *mp;
+	struct vnode *lowervp;
+	struct vnode **newvpp;
+{
+	struct vnode *aliasvp;
+
+	if (aliasvp = null_node_find(mp, lowervp)) {
+		/*
+		 * null_node_find has taken another reference
+		 * to the alias vnode.
+		 */
+#ifdef NULLFS_DIAGNOSTIC
+		vprint("null_node_create: exists", NULLTOV(ap));
+#endif
+		/* VREF(aliasvp); --- done in null_node_find */
+	} else {
+		int error;
+
+		/*
+		 * Get new vnode.
+		 */
+#ifdef NULLFS_DIAGNOSTIC
+		printf("null_node_create: create new alias vnode\n");
+#endif
+
+		/*
+		 * Make new vnode reference the null_node.
+		 */
+		if (error = null_node_alloc(mp, lowervp, &aliasvp))
+			return error;
+
+		/*
+		 * aliasvp is already VREF'd by getnewvnode()
+		 */
+	}
+
+	vrele(lowervp);
+
+#ifdef DIAGNOSTIC
+	if (lowervp->v_usecount < 1) {
+		/* Should never happen... */
+		vprint ("null_node_create: alias ");
+		vprint ("null_node_create: lower ");
+		printf ("null_node_create: lower has 0 usecount.\n");
+		panic ("null_node_create: lower has 0 usecount.");
+	};
+#endif
+
+#ifdef NULLFS_DIAGNOSTIC
+	vprint("null_node_create: alias", aliasvp);
+	vprint("null_node_create: lower", lowervp);
+#endif
+
+	*newvpp = aliasvp;
+	return (0);
+}
+#ifdef NULLFS_DIAGNOSTIC
+struct vnode *
+null_checkvp(vp, fil, lno)
+	struct vnode *vp;
+	char *fil;
+	int lno;
+{
+	struct null_node *a = VTONULL(vp);
+#ifdef notyet
+	/*
+	 * Can't do this check because vop_reclaim runs
+	 * with a funny vop vector.
+	 */
+	if (vp->v_op != null_vnodeop_p) {
+		printf ("null_checkvp: on non-null-node\n");
+		while (null_checkvp_barrier) /*WAIT*/ ;
+		panic("null_checkvp");
+	};
+#endif
+	if (a->null_lowervp == NULL) {
+		/* Should never happen */
+		int i; u_long *p;
+		printf("vp = %x, ZERO ptr\n", vp);
+		for (p = (u_long *) a, i = 0; i < 8; i++)
+			printf(" %x", p[i]);
+		printf("\n");
+		/* wait for debugger */
+		while (null_checkvp_barrier) /*WAIT*/ ;
+		panic("null_checkvp");
+	}
+	if (a->null_lowervp->v_usecount < 1) {
+		int i; u_long *p;
+		printf("vp = %x, unref'ed lowervp\n", vp);
+		for (p = (u_long *) a, i = 0; i < 8; i++)
+			printf(" %x", p[i]);
+		printf("\n");
+		/* wait for debugger */
+		while (null_checkvp_barrier) /*WAIT*/ ;
+		panic ("null with unref'ed lowervp");
+	};
+#ifdef notyet
+	printf("null %x/%d -> %x/%d [%s, %d]\n",
+	        NULLTOV(a), NULLTOV(a)->v_usecount,
+		a->null_lowervp, a->null_lowervp->v_usecount,
+		fil, lno);
+#endif
+	return a->null_lowervp;
+}
+#endif