diff --git a/include/.symlinks b/include/.symlinks
index 6746e7365..a30c92b2e 100644
--- a/include/.symlinks
+++ b/include/.symlinks
@@ -7,8 +7,9 @@
 ../lib/device/dev-cache.h
 ../lib/device/device.h
 ../lib/display/display.h
-../lib/filters/filter.h
+../lib/filters/filter-persistent.h
 ../lib/filters/filter-regex.h
+../lib/filters/filter.h
 ../lib/format1/format1.h
 ../lib/log/log.h
 ../lib/metadata/metadata.h
diff --git a/lib/Makefile.in b/lib/Makefile.in
index 8fc245d58..58af73cc8 100644
--- a/lib/Makefile.in
+++ b/lib/Makefile.in
@@ -16,9 +16,10 @@ SOURCES=\
 	device/dev-cache.c \
 	device/dev-io.c \
 	device/device.c \
+	filters/filter-persistent.c \
+	filters/filter-regex.c \
 	display/display.c \
 	filters/filter.c \
-	filters/filter-regex.c \
 	format1/disk-rep.c \
 	format1/format1.c \
 	format1/import-export.c \
@@ -28,8 +29,8 @@ SOURCES=\
 	metadata/metadata.c \
 	mm/dbg_malloc.c \
 	mm/pool.c \
-	regex/parse_rx.c \
 	regex/matcher.c \
+	regex/parse_rx.c \
 	regex/ttree.c \
 	uuid/uuid.c
 
diff --git a/lib/datastruct/hash.c b/lib/datastruct/hash.c
index 554b9dd12..002ff7fbb 100644
--- a/lib/datastruct/hash.c
+++ b/lib/datastruct/hash.c
@@ -127,7 +127,7 @@ static inline struct hash_node **_find(struct hash_table *t, const char *key)
 	return c;
 }
 
-char *hash_lookup(struct hash_table *t, const char *key)
+void *hash_lookup(struct hash_table *t, const char *key)
 {
 	struct hash_node **c = _find(t, key);
 	return *c ? (*c)->data : 0;
@@ -181,6 +181,11 @@ void hash_iterate(struct hash_table *t, iterate_fn f)
 			f(c->data);
 }
 
+char *hash_get_key(struct hash_table *t, struct hash_node *n)
+{
+	return n->key;
+}
+
 void *hash_get_data(struct hash_table *t, struct hash_node *n)
 {
 	return n->data;
diff --git a/lib/datastruct/hash.h b/lib/datastruct/hash.h
index 17024afb8..bd0c4eba2 100644
--- a/lib/datastruct/hash.h
+++ b/lib/datastruct/hash.h
@@ -15,13 +15,14 @@ typedef void (*iterate_fn)(void *data);
 struct hash_table *hash_create(unsigned size_hint);
 void hash_destroy(struct hash_table *t);
 
-char *hash_lookup(struct hash_table *t, const char *key);
+void *hash_lookup(struct hash_table *t, const char *key);
 int hash_insert(struct hash_table *t, const char *key, void *data);
 void hash_remove(struct hash_table *t, const char *key);
 
 unsigned hash_get_num_entries(struct hash_table *t);
 void hash_iterate(struct hash_table *t, iterate_fn f);
 
+char *hash_get_key(struct hash_table *t, struct hash_node *n);
 void *hash_get_data(struct hash_table *t, struct hash_node *n);
 struct hash_node *hash_get_first(struct hash_table *t);
 struct hash_node *hash_get_next(struct hash_table *t, struct hash_node *n);
diff --git a/lib/filters/filter-persistent.c b/lib/filters/filter-persistent.c
new file mode 100644
index 000000000..b236e3be9
--- /dev/null
+++ b/lib/filters/filter-persistent.c
@@ -0,0 +1,213 @@
+/*
+ * Copyright (C) 2001 Sistina Software (UK) Limited.
+ *
+ * This file is released under the GPL.
+ */
+
+#include "config.h"
+#include "dev-cache.h"
+#include "hash.h"
+#include "dbg_malloc.h"
+#include "log.h"
+#include "filter-persistent.h"
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
+
+struct pfilter {
+	char *file;
+	struct hash_table *devices;
+};
+
+/*
+ * entries in the table can be in one of these
+ * states.
+ */
+#define PF_UNCHECKED ((void *) 1)
+#define PF_CHECKED ((void *) 2)
+
+int _init_hash(struct pfilter *pf)
+{
+	if (pf->devices)
+		hash_destroy(pf->devices);
+
+	pf->devices = hash_create(128);
+	return pf ? 1 : 0;
+}
+
+int _load(struct pfilter *pf)
+{
+	int r = 0;
+	struct config_file *cf;
+	struct config_node *cn;
+	struct config_value *cv;
+
+	if (!(cf = create_config_file())) {
+		stack;
+		return 0;
+	}
+
+	if (!read_config(cf, pf->file)) {
+		stack;
+		goto out;
+	}
+
+	if (!(cn = find_config_node(cf->root, "/valid_devices", '/'))) {
+		log_info("couldn't find 'valid_devices' array in '%s'",
+			 pf->file);
+		goto out;
+	}
+
+	/*
+	 * iterate through the array, adding
+	 * devices as we go.
+	 */
+	for (cv = cn->v; cv; cv = cv->next) {
+		if (cv->type != CFG_STRING) {
+			log_info("valid_devices array contains a value "
+				 "which is not a string ... ignoring");
+			continue;
+		}
+
+		if (!hash_insert(pf->devices, cv->v.str, PF_UNCHECKED))
+			log_info("couldn't add '%s' to filter ... ignoring",
+				 cv->v.str);
+	}
+	r = 1;
+
+ out:
+	destroy_config_file(cf);
+	return r;
+}
+
+int _dump(struct pfilter *pf)
+{
+	int first = 1;
+	struct hash_node *n;
+	FILE *fp = fopen(pf->file, "w");
+
+	if (!fp) {
+		log_info("Couldn't open '%s' for to hold valid devices.",
+			 pf->file);
+		return 0;
+	}
+
+	fprintf(fp, "# This file is automatically maintained by lvm.\n\n");
+	fprintf(fp, "valid_devices=[\n");
+
+	for (n = hash_get_first(pf->devices); n;
+	     n = hash_get_next(pf->devices, n)) {
+		if (!first)
+			fprintf(fp, ",\n");
+		else
+			first = 0;
+
+		fprintf(fp, "\t\"%s\"", hash_get_key(pf->devices, n));
+	}
+
+	fprintf(fp, "\n]\n");
+	fclose(fp);
+	return 1;
+}
+
+int _check(const char *path)
+{
+	int fd = open(path, O_RDONLY), r = 0;
+
+	if (fd >= 0)
+		r = 1;
+
+	close(fd);
+	return r;
+}
+
+int _init_valid_p(struct dev_filter *f, struct device *dev)
+{
+	struct pfilter *pf = (struct pfilter *) f->private;
+	void *l = hash_lookup(pf->devices, dev->name);
+
+	if (l)
+		return 1;
+
+	if (_check(dev->name)) {
+		hash_insert(pf->devices, dev->name, PF_CHECKED);
+		return 1;
+	}
+
+	return 0;
+}
+
+int _valid_p(struct dev_filter *f, struct device *dev)
+{
+	struct pfilter *pf = (struct pfilter *) f->private;
+	void *l = hash_lookup(pf->devices, dev->name);
+
+	if (!l)
+		return 0;
+
+	if (l == PF_UNCHECKED && !_check(dev->name)) {
+		hash_remove(pf->devices, dev->name);
+		return 0;
+	}
+
+	return 1;
+}
+
+void _destroy(struct dev_filter *f)
+{
+	struct pfilter *pf = (struct pfilter *) f->private;
+
+	_dump(pf);
+	hash_destroy(pf->devices);
+	dbg_free(pf->file);
+	dbg_free(pf);
+	dbg_free(f);
+}
+
+struct dev_filter *persistent_filter_create(const char *file, int init)
+{
+	struct pfilter *pf;
+	struct dev_filter *f = NULL;
+
+	if (!(pf = dbg_malloc(sizeof(*pf)))) {
+		stack;
+		return NULL;
+	}
+	memset(pf, 0, sizeof(*pf));
+
+	if (!(pf->file = dbg_malloc(strlen(file) + 1))) {
+		stack;
+		goto bad;
+	}
+	strcpy(pf->file, file);
+
+	if (!(_init_hash(pf))) {
+		log_err("Couldn't create hash table for persistent filter.");
+		goto bad;
+	}
+
+	if (!init)
+		_load(pf);
+
+	if (!(f = dbg_malloc(sizeof(*f)))) {
+		stack;
+		goto bad;
+	}
+
+	f->passes_filter = init ? _init_valid_p : _valid_p;
+	f->destroy = _destroy;
+	f->private = pf;
+
+	return f;
+
+ bad:
+	dbg_free(pf->file);
+	if (pf->devices)
+		hash_destroy(pf->devices);
+	dbg_free(pf);
+	dbg_free(f);
+	return NULL;
+}
+
diff --git a/lib/filters/filter-persistent.h b/lib/filters/filter-persistent.h
new file mode 100644
index 000000000..8f445762b
--- /dev/null
+++ b/lib/filters/filter-persistent.h
@@ -0,0 +1,14 @@
+/*
+ * Copyright (C) 2001 Sistina Software (UK) Limited.
+ *
+ * This file is released under the GPL.
+ */
+
+#ifndef _LVM_FILTER_PERSISTENT_H
+#define _LVM_FILTER_PERSISTENT_h
+
+#include "dev-cache.h"
+
+struct dev_filter *persistent_filter_create(const char *file, int init);
+
+#endif
diff --git a/old-tests/filters/Makefile.in b/old-tests/filters/Makefile.in
index 35fee47d1..036cb90c6 100644
--- a/old-tests/filters/Makefile.in
+++ b/old-tests/filters/Makefile.in
@@ -9,13 +9,18 @@ top_srcdir = @top_srcdir@
 VPATH = @srcdir@
 
 SOURCES=\
-	rfilter_t.c
+	rfilter_t.c \
+	pfilter_t.c
 
 TARGETS=\
-	rfilter_t
+	rfilter_t \
+	pfilter_t
 
 include ../../make.tmpl
 
 rfilter_t: rfilter_t.o $(top_srcdir)/lib/liblvm.a
 	$(CC) -o rfilter_t rfilter_t.o -L$(top_srcdir)/lib -llvm
 
+pfilter_t: pfilter_t.o $(top_srcdir)/lib/liblvm.a
+	$(CC) -o pfilter_t pfilter_t.o -L$(top_srcdir)/lib -llvm
+
diff --git a/old-tests/filters/pfilter_t.c b/old-tests/filters/pfilter_t.c
new file mode 100644
index 000000000..d03e4f8a4
--- /dev/null
+++ b/old-tests/filters/pfilter_t.c
@@ -0,0 +1,65 @@
+/*
+ * Copyright (C) 2001 Sistina Software (UK) Limited.
+ *
+ * This file is released under the GPL.
+ */
+
+#include "filter-persistent.h"
+#include "log.h"
+#include "dbg_malloc.h"
+
+#include <stdio.h>
+#include <ctype.h>
+#include <string.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <sys/mman.h>
+
+int main(int argc, char **argv)
+{
+	struct dev_filter *filter;
+	struct dev_iter *iter;
+	struct device *dev;
+
+	if (argc > 2) {
+		fprintf(stderr, "Usage : %s <file>\n", argv[0]);
+		exit(1);
+	}
+
+	init_log(stderr);
+	init_debug(_LOG_DEBUG);
+
+	if (!dev_cache_init()) {
+		fprintf(stderr, "couldn't initialise dev_cache_init failed\n");
+		exit(1);
+	}
+
+	if (!dev_cache_add_dir("/dev")) {
+		fprintf(stderr, "couldn't add '/dev' to dev_cache\n");
+		exit(1);
+	}
+
+	if (!(filter = persistent_filter_create("./pfilter.cfg", 1))) {
+		fprintf(stderr, "couldn't build filter\n");
+		exit(1);
+	}
+
+	if (!(iter = dev_iter_create(filter))) {
+		log_err("couldn't create iterator");
+		exit(1);
+	}
+
+	while ((dev = dev_iter_get(iter)))
+		printf("%s\n", dev->name);
+
+	dev_iter_destroy(iter);
+	filter->destroy(filter);
+	dev_cache_exit();
+
+	dump_memory();
+	fin_log();
+	return 0;
+}
+