1 files changed, 303 insertions, 0 deletions
diff --git a/sys/fs/nullfs/null_subr.c b/sys/fs/nullfs/null_subr.c
new file mode 100644
index 0000000..603f418
--- /dev/null
+++ b/sys/fs/nullfs/null_subr.c
@@ -0,0 +1,303 @@
+/*
+ * 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	8.7 (Berkeley) 5/14/95
+ *
+ * $Id: null_subr.c,v 1.18 1998/07/15 02:32:18 bde Exp $
+ */
+
+#include "opt_debug_nullfs.h"
+
+#include <sys/param.h>
+#include <sys/systm.h>
+#include <sys/proc.h>
+#include <sys/vnode.h>
+#include <sys/mount.h>
+#include <sys/malloc.h>
+#include <miscfs/nullfs/null.h>
+
+#define LOG2_SIZEVNODE 7		/* log2(sizeof struct vnode) */
+#define	NNULLNODECACHE 16
+
+/*
+ * 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.
+ */
+
+#define	NULL_NHASH(vp) \
+	(&null_node_hashtbl[(((uintptr_t)vp)>>LOG2_SIZEVNODE) & null_node_hash])
+static LIST_HEAD(null_node_hashhead, null_node) *null_node_hashtbl;
+static u_long null_node_hash;
+
+static int	null_node_alloc __P((struct mount *mp, struct vnode *lowervp,
+				     struct vnode **vpp));
+static struct vnode *
+		null_node_find __P((struct mount *mp, struct vnode *lowervp));
+
+/*
+ * Initialise cache headers
+ */
+int
+nullfs_init(vfsp)
+	struct vfsconf *vfsp;
+{
+
+#ifdef NULLFS_DIAGNOSTIC
+	printf("nullfs_init\n");		/* printed during system boot */
+#endif
+	null_node_hashtbl = hashinit(NNULLNODECACHE, M_CACHE, &null_node_hash);
+	return (0);
+}
+
+/*
+ * 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 proc *p = curproc;	/* XXX */
+	struct null_node_hashhead *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_NHASH(lowervp);
+loop:
+	for (a = hd->lh_first; a != 0; a = a->null_hash.le_next) {
+		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, p)) {
+				printf ("null_node_find: vget failed.\n");
+				goto loop;
+			};
+			return (vp);
+		}
+	}
+
+	return NULLVP;
+}
+
+
+/*
+ * 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_hashhead *hd;
+	struct null_node *xp;
+	struct vnode *othervp, *vp;
+	int error;
+
+	/*
+	 * Do the MALLOC before the getnewvnode since doing so afterward
+	 * might cause a bogus v_data pointer to get dereferenced
+	 * elsewhere if MALLOC should block.
+	 */
+	MALLOC(xp, struct null_node *, sizeof(struct null_node), M_TEMP, M_WAITOK);
+
+	error = getnewvnode(VT_NULL, mp, null_vnodeop_p, vpp);
+	if (error) {
+		FREE(xp, M_TEMP);
+		return (error);
+	}
+	vp = *vpp;
+
+	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.)
+	 */
+	othervp = null_node_find(mp, lowervp);
+	if (othervp) {
+		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_NHASH(lowervp);
+	LIST_INSERT_HEAD(hd, xp, null_hash);
+	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;
+
+	aliasvp = null_node_find(mp, lowervp);
+	if (aliasvp) {
+		/*
+		 * null_node_find has taken another reference
+		 * to the alias vnode.
+		 */
+#ifdef NULLFS_DIAGNOSTIC
+		vprint("null_node_create: exists", aliasvp);
+#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.
+		 */
+		error = null_node_alloc(mp, lowervp, &aliasvp);
+		if (error)
+			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 ", aliasvp);
+		vprint ("null_node_create: lower ", lowervp);
+		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
+#include "opt_ddb.h"
+
+#ifdef DDB
+#define	null_checkvp_barrier	1
+#else
+#define	null_checkvp_barrier	0
+#endif
+
+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 == NULLVP) {
+		/* Should never happen */
+		int i; u_long *p;
+		printf("vp = %p, ZERO ptr\n", (void *)vp);
+		for (p = (u_long *) a, i = 0; i < 8; i++)
+			printf(" %lx", 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 = %p, unref'ed lowervp\n", (void *)vp);
+		for (p = (u_long *) a, i = 0; i < 8; i++)
+			printf(" %lx", 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