Introduce GEOM_LABEL class.

This class is used for detecting volume labels on file systems:
UFS, MSDOSFS (FAT12, FAT16, FAT32) and ISO9660.
It also provide native labelization (there is no need for file system).

g_label_ufs.c is based on geom_vol_ffs from Gordon Tetlow.
g_label_msdos.c and g_label_iso9660.c are probably hacks, I just found
where volume labels are stored and I use those offsets here,
but with this class it should be easy to do it as it should be done by
someone who know how.
Implementing volume labels detection for other file systems also should
be trivial.

New providers are created in those directories:
/dev/ufs/ (UFS1, UFS2)
/dev/msdosfs/ (FAT12, FAT16, FAT32)
/dev/iso9660/ (ISO9660)
/dev/label/ (native labels, configured with glabel(8))

Manual page cleanups and some comments inside were submitted by
Simon L. Nielsen, who was, as always, very helpful. Thanks!

10 files changed, 803 insertions, 0 deletions

diff --git a/sys/conf/NOTES b/sys/conf/NOTES
index 2191e57..2607142 100644
--- a/sys/conf/NOTES
+++ b/sys/conf/NOTES
@@ -125,6 +125,7 @@ options 	GEOM_CONCAT		# Disk concatenation.
 options 	GEOM_FOX		# Redundant path mitigation
 options 	GEOM_GATE		# Userland services.
 options 	GEOM_GPT		# GPT partitioning
+options 	GEOM_LABEL		# Providers labelization.
 options 	GEOM_MBR		# DOS/MBR partitioning
 options 	GEOM_NOP		# Test class.
 options 	GEOM_PC98		# NEC PC9800 partitioning
diff --git a/sys/conf/files b/sys/conf/files
index 10c2df7..a25b963 100644
--- a/sys/conf/files
+++ b/sys/conf/files
@@ -940,6 +940,10 @@ crypto/rijndael/rijndael-api-fst.c	optional geom_bde
 crypto/sha2/sha2.c		optional geom_bde
 geom/concat/g_concat.c	optional geom_concat
 geom/gate/g_gate.c	optional geom_gate
+geom/label/g_label.c	optional geom_label
+geom/label/g_label_iso9660.c	optional geom_label
+geom/label/g_label_msdosfs.c	optional geom_label
+geom/label/g_label_ufs.c	optional geom_label
 geom/nop/g_nop.c	optional geom_nop
 geom/stripe/g_stripe.c	optional geom_stripe
 geom/geom_aes.c		optional geom_aes
diff --git a/sys/conf/options b/sys/conf/options
index 1c6c146..d086703 100644
--- a/sys/conf/options
+++ b/sys/conf/options
@@ -71,6 +71,7 @@ GEOM_CONCAT	opt_geom.h
 GEOM_FOX	opt_geom.h
 GEOM_GATE	opt_geom.h
 GEOM_GPT	opt_geom.h
+GEOM_LABEL	opt_geom.h
 GEOM_MBR	opt_geom.h
 GEOM_MIRROR	opt_geom.h
 GEOM_NOP	opt_geom.h
diff --git a/sys/geom/label/g_label.c b/sys/geom/label/g_label.c
new file mode 100644
index 0000000..2aa9754
--- /dev/null
+++ b/sys/geom/label/g_label.c
@@ -0,0 +1,405 @@
+/*-
+ * Copyright (c) 2004 Pawel Jakub Dawidek <pjd@FreeBSD.org>
+ * All rights reserved.
+ *
+ * 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.
+ * 
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHORS 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 AUTHORS 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.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <sys/param.h>
+#include <sys/systm.h>
+#include <sys/kernel.h>
+#include <sys/module.h>
+#include <sys/lock.h>
+#include <sys/mutex.h>
+#include <sys/bio.h>
+#include <sys/sysctl.h>
+#include <sys/malloc.h>
+#include <geom/geom.h>
+#include <geom/geom_slice.h>
+#include <geom/label/g_label.h>
+
+
+SYSCTL_DECL(_kern_geom);
+SYSCTL_NODE(_kern_geom, OID_AUTO, label, CTLFLAG_RW, 0, "GEOM_LABEL stuff");
+u_int g_label_debug = 0;
+SYSCTL_UINT(_kern_geom_label, OID_AUTO, debug, CTLFLAG_RW, &g_label_debug, 0,
+    "Debug level");
+
+static int g_label_destroy(struct g_geom *gp, boolean_t force);
+static struct g_geom *g_label_taste(struct g_class *mp, struct g_provider *pp,
+    int flags __unused);
+static void g_label_config(struct gctl_req *req, struct g_class *mp,
+    const char *verb);
+
+struct g_class g_label_class = {
+	.name = G_LABEL_CLASS_NAME,
+	.ctlreq = g_label_config,
+	.taste = g_label_taste
+};
+
+/*
+ * To add a new file system where you want to look for volume labels,
+ * you have to:
+ * 1. Add a file which implements looking for volume labels.
+ * 2. Add an 'extern const struct g_label_desc g_label_<your file system>;'.
+ * 3. Add an element to the table below '&g_label_<your_file_system>,'.
+ */
+const struct g_label_desc *g_labels[] = {
+	&g_label_ufs,
+	&g_label_iso9660,
+	&g_label_msdosfs,
+	NULL
+};
+
+
+static void
+g_label_orphan(struct g_consumer *cp __unused)
+{
+
+	KASSERT(1 == 0, ("%s called?", __func__));
+}
+
+static void
+g_label_start(struct bio *bp __unused)
+{
+
+	KASSERT(1 == 0, ("%s called?", __func__));
+}
+
+static int
+g_label_access(struct g_provider *pp __unused, int dr __unused, int dw __unused,
+    int de __unused)
+{
+
+	KASSERT(1 == 0, ("%s called", __func__));
+	return (EOPNOTSUPP);
+}
+
+static struct g_geom *
+g_label_create(struct gctl_req *req, struct g_class *mp, struct g_provider *pp,
+    const char *label, const char *dir, off_t mediasize)
+{
+	struct g_geom *gp;
+	struct g_provider *pp2;
+	struct g_consumer *cp;
+	char name[64];
+
+	g_topology_assert();
+
+	gp = NULL;
+	cp = NULL;
+	snprintf(name, sizeof(name), "%s/%s", dir, label);
+	LIST_FOREACH(gp, &mp->geom, geom) {
+		pp2 = LIST_FIRST(&gp->provider);
+		if (pp2 == NULL)
+			continue;
+		if (strcmp(pp2->name, name) == 0) {
+			G_LABEL_DEBUG(1, "Label %s(%s) already exists (%s).",
+			    label, name, pp->name);
+			if (req != NULL) {
+				gctl_error(req, "Provider %s already exists.",
+				    name);
+			}
+			return (NULL);
+		}
+	}
+	gp = g_slice_new(mp, 1, pp, &cp, NULL, 0, NULL);
+	if (gp == NULL) {
+		G_LABEL_DEBUG(0, "Cannot create slice %s.", label);
+		if (req != NULL)
+			gctl_error(req, "Cannot create slice %s.", label);
+		return (NULL);
+	}
+	g_access(cp, -1, 0, 0);
+	g_slice_config(gp, 0, G_SLICE_CONFIG_SET, (off_t)0, mediasize,
+	    pp->sectorsize, name);
+	G_LABEL_DEBUG(0, "Label for provider %s is %s.", pp->name, name);
+	return (gp);
+}
+
+static int
+g_label_destroy(struct g_geom *gp, boolean_t force)
+{
+	struct g_provider *pp;
+
+	g_topology_assert();
+	pp = LIST_FIRST(&gp->provider);
+	if (pp != NULL && (pp->acr != 0 || pp->acw != 0 || pp->ace != 0)) {
+		if (force) {
+			G_LABEL_DEBUG(0, "Provider %s is still open, so it "
+			    "can't be definitely removed.", pp->name);
+		} else {
+			G_LABEL_DEBUG(1,
+			    "Provider %s is still open (r%dw%de%d).", pp->name,
+			    pp->acr, pp->acw, pp->ace);
+			return (EBUSY);
+		}
+	} else {
+		G_LABEL_DEBUG(0, "Label %s removed.",
+		    LIST_FIRST(&gp->provider)->name);
+	}
+	g_slice_spoiled(LIST_FIRST(&gp->consumer));
+	return (0);
+}
+
+static int
+g_label_read_metadata(struct g_consumer *cp, struct g_label_metadata *md)
+{
+	struct g_provider *pp;
+	u_char *buf;
+	int error;
+
+	g_topology_assert();
+
+	pp = cp->provider;
+	g_topology_unlock();
+	buf = g_read_data(cp, pp->mediasize - pp->sectorsize, pp->sectorsize,
+	    &error);
+	g_topology_lock();
+	if (buf == NULL)
+		return (error);
+	/* Decode metadata. */
+	label_metadata_decode(buf, md);
+	g_free(buf);
+
+	return (0);
+}
+
+static struct g_geom *
+g_label_taste(struct g_class *mp, struct g_provider *pp, int flags __unused)
+{
+	struct g_label_metadata md;
+	struct g_consumer *cp;
+	struct g_geom *gp;
+	int error, i;
+
+	g_trace(G_T_TOPOLOGY, "%s(%s, %s)", __func__, mp->name, pp->name);
+	g_topology_assert();
+
+	G_LABEL_DEBUG(3, "Tasting %s.", pp->name);
+
+	if (strcmp(pp->geom->class->name, mp->name) == 0)
+		return (NULL);
+
+	gp = g_new_geomf(mp, "label:taste");
+	gp->start = g_label_start;
+	gp->access = g_label_access;
+	gp->orphan = g_label_orphan;
+	cp = g_new_consumer(gp);
+	g_attach(cp, pp);
+	error = g_access(cp, 1, 0, 0);
+	if (error != 0)
+		return (NULL);
+
+	do {
+		error = g_label_read_metadata(cp, &md);
+		if (error != 0)
+			break;
+		if (strcmp(md.md_magic, G_LABEL_MAGIC) != 0)
+			break;
+		if (md.md_version > G_LABEL_VERSION) {
+			printf("geom_label.ko module is too old to handle %s.\n",
+			    pp->name);
+			break;
+		}
+		g_label_create(NULL, mp, pp, md.md_label, G_LABEL_DIR,
+		    pp->mediasize - pp->sectorsize);
+	} while (0);
+	for (i = 0; g_labels[i] != NULL; i++) {
+		char label[64];
+
+		g_topology_unlock();
+		g_labels[i]->ld_taste(cp, label, sizeof(label));
+		g_topology_lock();
+		if (label[0] == '\0')
+			continue;
+		g_label_create(NULL, mp, pp, label, g_labels[i]->ld_dir,
+		    pp->mediasize);
+	}
+
+	g_access(cp, -1, 0, 0);
+	g_wither_geom(gp, ENXIO);
+
+	return (NULL);
+}
+
+static void
+g_label_ctl_create(struct gctl_req *req, struct g_class *mp)
+{
+	struct g_provider *pp;
+	const char *name;
+	int *nargs;
+
+	g_topology_assert();
+
+	nargs = gctl_get_paraml(req, "nargs", sizeof(*nargs));
+	if (nargs == NULL) {
+		gctl_error(req, "No '%s' argument", "nargs");
+		return;
+	}
+	if (*nargs != 2) {
+		gctl_error(req, "Invalid number of argument.");
+		return;
+	}
+	/*
+	 * arg1 is the name of provider.
+	 */
+	name = gctl_get_asciiparam(req, "arg1"); 
+	if (name == NULL) {
+		gctl_error(req, "No 'arg%d' argument", 1);
+		return;
+	}
+	if (strncmp(name, "/dev/", strlen("/dev/")) == 0)
+		name += strlen("/dev/");
+	pp = g_provider_by_name(name);
+	if (pp == NULL) {
+		G_LABEL_DEBUG(1, "Provider %s is invalid.", name);
+		gctl_error(req, "Provider %s is invalid.", name);
+		return; 
+	}
+	/*
+	 * arg0 is the label.
+	 */
+	name = gctl_get_asciiparam(req, "arg0"); 
+	if (name == NULL) {
+		gctl_error(req, "No 'arg%d' argument", 0);
+		return;
+	}
+	g_label_create(req, mp, pp, name, G_LABEL_DIR, pp->mediasize);
+}
+
+static const char *
+g_label_skip_dir(const char *name)
+{
+	char path[64];
+	u_int i;
+
+	if (strncmp(name, "/dev/", strlen("/dev/")) == 0)
+		name += strlen("/dev/");
+	if (strncmp(name, G_LABEL_DIR "/", strlen(G_LABEL_DIR "/")) == 0)
+		name += strlen(G_LABEL_DIR "/");
+	for (i = 0; g_labels[i] != NULL; i++) {
+		snprintf(path, sizeof(path), "%s/", g_labels[i]->ld_dir);
+		if (strncmp(name, path, strlen(path)) == 0) {
+			name += strlen(path);
+			break;
+		}
+	}
+	return (name);
+}
+
+static struct g_geom *
+g_label_find_geom(struct g_class *mp, const char *name)
+{
+	struct g_geom *gp;
+	struct g_provider *pp;
+	const char *pname;
+
+	name = g_label_skip_dir(name);
+	LIST_FOREACH(gp, &mp->geom, geom) {
+		pp = LIST_FIRST(&gp->provider);
+		pname = g_label_skip_dir(pp->name);
+		if (strcmp(pname, name) == 0)
+			return (gp);
+	}
+	return (NULL);
+}
+
+static void
+g_label_ctl_destroy(struct gctl_req *req, struct g_class *mp)
+{
+	int *nargs, *force, error, i;
+	struct g_geom *gp;
+	const char *name;
+	char param[16];
+
+	g_topology_assert();
+
+	nargs = gctl_get_paraml(req, "nargs", sizeof(*nargs));
+	if (nargs == NULL) {
+		gctl_error(req, "No '%s' argument", "nargs");
+		return;
+	}
+	if (*nargs <= 0) {
+		gctl_error(req, "Missing device(s).");
+		return;
+	}
+	force = gctl_get_paraml(req, "force", sizeof(*force));
+	if (force == NULL) {
+		gctl_error(req, "No 'force' argument");
+		return;
+	}
+
+	for (i = 0; i < *nargs; i++) {
+		snprintf(param, sizeof(param), "arg%d", i);
+		name = gctl_get_asciiparam(req, param); 
+		if (name == NULL) {
+			gctl_error(req, "No 'arg%d' argument", i);
+			return;
+		}
+		gp = g_label_find_geom(mp, name);
+		if (gp == NULL) {
+			G_LABEL_DEBUG(1, "Label %s is invalid.", name);
+			gctl_error(req, "Label %s is invalid.", name);
+			return; 
+		}
+		error = g_label_destroy(gp, *force);
+		if (error != 0) {
+			gctl_error(req, "Cannot destroy label %s (error=%d).",
+			    LIST_FIRST(&gp->provider)->name, error);
+			return;
+		}
+	}
+}
+
+static void
+g_label_config(struct gctl_req *req, struct g_class *mp, const char *verb)
+{
+	uint32_t *version;
+
+	g_topology_assert();
+
+	version = gctl_get_paraml(req, "version", sizeof(*version));
+	if (version == NULL) {
+		gctl_error(req, "No '%s' argument.", "version");
+		return;
+	}
+	if (*version != G_LABEL_VERSION) {
+		gctl_error(req, "Userland and kernel parts are out of sync.");
+		return;
+	}
+
+	if (strcmp(verb, "create") == 0) {
+		g_label_ctl_create(req, mp);
+		return;
+	} else if (strcmp(verb, "destroy") == 0) {
+		g_label_ctl_destroy(req, mp);
+		return;
+	}
+
+	gctl_error(req, "Unknown verb.");
+}
+
+DECLARE_GEOM_CLASS(g_label_class, g_label);
diff --git a/sys/geom/label/g_label.h b/sys/geom/label/g_label.h
new file mode 100644
index 0000000..011cc5e
--- /dev/null
+++ b/sys/geom/label/g_label.h
@@ -0,0 +1,97 @@
+/*-
+ * Copyright (c) 2004 Pawel Jakub Dawidek <pjd@FreeBSD.org>
+ * All rights reserved.
+ *
+ * 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.
+ * 
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHORS 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 AUTHORS 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.
+ *
+ * $FreeBSD$
+ */
+
+#ifndef	_G_LABEL_H_
+#define	_G_LABEL_H_
+
+#include <sys/endian.h>
+
+#define	G_LABEL_CLASS_NAME	"LABEL"
+
+#define	G_LABEL_MAGIC		"GEOM::LABEL"
+#define	G_LABEL_VERSION		0
+#define	G_LABEL_DIR		"label"
+
+#ifdef _KERNEL
+extern u_int g_label_debug;
+
+#define	G_LABEL_DEBUG(lvl, ...)	do {					\
+	if (g_label_debug >= (lvl)) {					\
+		printf("GEOM_LABEL");					\
+		if (g_label_debug > 0)					\
+			printf("[%u]", lvl);				\
+		printf(": ");						\
+		printf(__VA_ARGS__);					\
+		printf("\n");						\
+	}								\
+} while (0)
+#define	G_LABEL_LOGREQ(bp, ...)	do {					\
+	if (g_label_debug >= 2) {					\
+		printf("GEOM_LABEL[2]: ");				\
+		printf(__VA_ARGS__);					\
+		printf(" ");						\
+		g_print_bio(bp);					\
+		printf("\n");						\
+	}								\
+} while (0)
+
+typedef void g_label_taste_t (struct g_consumer *cp, char *label, size_t size);
+
+struct g_label_desc {
+	g_label_taste_t	*ld_taste;
+	char		*ld_dir;
+};
+
+/* Supported labels. */
+extern const struct g_label_desc g_label_ufs;
+extern const struct g_label_desc g_label_iso9660;
+extern const struct g_label_desc g_label_msdosfs;
+#endif	/* _KERNEL */
+
+struct g_label_metadata {
+	char		md_magic[16];	/* Magic value. */
+	uint32_t	md_version;	/* Version number. */
+	char		md_label[16];	/* Label. */
+};
+static __inline void
+label_metadata_encode(const struct g_label_metadata *md, u_char *data)
+{
+
+	bcopy(md->md_magic, data, sizeof(md->md_magic));
+	le32enc(data + 16, md->md_version);
+	bcopy(md->md_label, data + 20, sizeof(md->md_label));
+}
+static __inline void
+label_metadata_decode(const u_char *data, struct g_label_metadata *md)
+{
+
+	bcopy(data, md->md_magic, sizeof(md->md_magic));
+	md->md_version = le32dec(data + 16);
+	bcopy(data + 20, md->md_label, sizeof(md->md_label));
+}
+#endif	/* _G_LABEL_H_ */
diff --git a/sys/geom/label/g_label_iso9660.c b/sys/geom/label/g_label_iso9660.c
new file mode 100644
index 0000000..34d9252
--- /dev/null
+++ b/sys/geom/label/g_label_iso9660.c
@@ -0,0 +1,80 @@
+/*-
+ * Copyright (c) 2004 Pawel Jakub Dawidek <pjd@FreeBSD.org>
+ * All rights reserved.
+ *
+ * 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.
+ * 
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHORS 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 AUTHORS 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.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <sys/param.h>
+#include <sys/systm.h>
+#include <sys/kernel.h>
+#include <sys/malloc.h>
+
+#include <geom/geom.h>
+#include <geom/label/g_label.h>
+
+#define G_LABEL_ISO9660_DIR	"iso9660"
+
+#define	ISO9660_MAGIC	"\x01" "CD001" "\x01\x00"
+#define	VOLUME_LEN	32
+
+
+static void
+g_label_iso9660_taste(struct g_consumer *cp, char *label, size_t size)
+{
+	struct g_provider *pp;
+	char *sector, *volume;
+	int i, error;
+
+	g_topology_assert_not();
+	pp = cp->provider;
+	label[0] = '\0';
+
+	sector = (char *)g_read_data(cp, 0x8000, pp->sectorsize, &error);
+	if (sector == NULL || error != 0)
+		return;
+	if (bcmp(sector, ISO9660_MAGIC, sizeof(ISO9660_MAGIC) - 1) != 0) {
+		g_free(sector);
+		return;
+	}
+	G_LABEL_DEBUG(1, "ISO9660 file system detected on %s.", pp->name);
+	volume = sector + 0x28;
+	bzero(label, size);
+	strlcpy(label, volume, MIN(size, VOLUME_LEN));
+	g_free(sector);
+	for (i = size - 1; i > 0; i--) {
+		if (label[i] == '\0')
+			continue;
+		else if (label[i] == ' ')
+			label[i] = '\0';
+		else
+			break;
+	}
+}
+
+const struct g_label_desc g_label_iso9660 = {
+	.ld_taste = g_label_iso9660_taste,
+	.ld_dir = G_LABEL_ISO9660_DIR
+};
diff --git a/sys/geom/label/g_label_msdosfs.c b/sys/geom/label/g_label_msdosfs.c
new file mode 100644
index 0000000..ff0d7c3
--- /dev/null
+++ b/sys/geom/label/g_label_msdosfs.c
@@ -0,0 +1,101 @@
+/*-
+ * Copyright (c) 2004 Pawel Jakub Dawidek <pjd@FreeBSD.org>
+ * All rights reserved.
+ *
+ * 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.
+ * 
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHORS 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 AUTHORS 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.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <sys/param.h>
+#include <sys/systm.h>
+#include <sys/kernel.h>
+#include <sys/malloc.h>
+
+#include <geom/geom.h>
+#include <geom/label/g_label.h>
+
+#define G_LABEL_MSDOSFS_DIR	"msdosfs"
+
+#define	FAT12	"FAT12   "
+#define	FAT16	"FAT16   "
+#define	FAT32	"FAT32   "
+#define	VOLUME_LEN	11
+#define NO_NAME "NO NAME    "
+
+
+static void
+g_label_msdosfs_taste(struct g_consumer *cp, char *label, size_t size)
+{
+	struct g_provider *pp;
+	char *sector, *volume;
+	int i, error;
+
+	g_topology_assert_not();
+	pp = cp->provider;
+	label[0] = '\0';
+
+	sector = (char *)g_read_data(cp, 0, pp->sectorsize, &error);
+	if (sector == NULL || error != 0)
+		return;
+	if (strncmp(sector + 0x36, FAT12, strlen(FAT12)) == 0) {
+		G_LABEL_DEBUG(1, "MSDOS (FAT12) file system detected on %s.",
+		    pp->name);
+		volume = sector + 0x2b;
+	} else if (strncmp(sector + 0x36, FAT16, strlen(FAT16)) == 0) {
+		G_LABEL_DEBUG(1, "MSDOS (FAT16) file system detected on %s.",
+		    pp->name);
+		volume = sector + 0x2b;
+	} else if (strncmp(sector + 0x52, FAT32, strlen(FAT32)) == 0) {
+		G_LABEL_DEBUG(1, "MSDOS (FAT32) file system detected on %s.",
+		    pp->name);
+		volume = sector + 0x47;
+	} else {
+		g_free(sector);
+		return;
+	}
+	if (strncmp(volume, NO_NAME, VOLUME_LEN) == 0) {
+		g_free(sector);
+		return;
+	}
+	if (volume[0] == '\0') {
+		g_free(sector);
+		return;
+	}
+	bzero(label, size);
+	strlcpy(label, volume, MIN(size, VOLUME_LEN));
+	g_free(sector);
+	for (i = size - 1; i > 0; i--) {
+		if (label[i] == '\0')
+			continue;
+		else if (label[i] == ' ')
+			label[i] = '\0';
+		else
+			break;
+	}
+}
+
+const struct g_label_desc g_label_msdosfs = {
+	.ld_taste = g_label_msdosfs_taste,
+	.ld_dir = G_LABEL_MSDOSFS_DIR
+};
diff --git a/sys/geom/label/g_label_ufs.c b/sys/geom/label/g_label_ufs.c
new file mode 100644
index 0000000..dc188f7
--- /dev/null
+++ b/sys/geom/label/g_label_ufs.c
@@ -0,0 +1,102 @@
+/*-
+ * Copyright (c) 2002, 2003 Gordon Tetlow
+ * All rights reserved.
+ *
+ * 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.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <sys/param.h>
+#include <sys/systm.h>
+#include <sys/kernel.h>
+#include <sys/malloc.h>
+
+#include <ufs/ufs/dinode.h>
+#include <ufs/ffs/fs.h>
+
+#include <geom/geom.h>
+#include <geom/label/g_label.h>
+
+#define G_LABEL_UFS_DIR	"ufs"
+
+static const int superblocks[] = SBLOCKSEARCH;
+
+static void
+g_label_ufs_taste(struct g_consumer *cp, char *label, size_t size)
+{
+	struct g_provider *pp;
+	int error, sb, superblock;
+	struct fs *fs;
+
+	g_topology_assert_not();
+	pp = cp->provider;
+	label[0] = '\0';
+	/*
+	 * Walk through the standard places that superblocks hide and look
+	 * for UFS magic. If we find magic, then check that the size in the
+	 * superblock corresponds to the size of the underlying provider.
+	 * Finally, look for a volume label and create an appropriate 
+	 * provider based on that.
+	 */
+	for (sb = 0; (superblock = superblocks[sb]) != -1; sb++) {
+		fs = (struct fs *)g_read_data(cp, superblock, SBLOCKSIZE,
+		    &error);
+		if (fs == NULL || error != 0)
+			continue;
+		/* Check for magic and make sure things are the right size */
+		if (fs->fs_magic == FS_UFS1_MAGIC) {
+			G_LABEL_DEBUG(1, "UFS1 file system detected on %s.",
+			    pp->name);
+			if (fs->fs_old_size * fs->fs_fsize !=
+			    (int32_t)pp->mediasize) {
+				g_free(fs);
+				continue;
+			}
+		} else if (fs->fs_magic == FS_UFS2_MAGIC) {
+			G_LABEL_DEBUG(1, "UFS2 file system detected on %s.",
+			    pp->name);
+			if (fs->fs_size * fs->fs_fsize !=
+			    (int64_t)pp->mediasize) {
+				g_free(fs);
+				continue;
+			}
+		} else {
+			g_free(fs);
+			continue;
+		}
+		/* Check for volume label */
+		if (fs->fs_volname[0] == '\0') {
+			g_free(fs);
+			continue;
+		}
+		strlcpy(label, fs->fs_volname, size);
+		g_free(fs);
+		break;
+	}
+}
+
+const struct g_label_desc g_label_ufs = {
+	.ld_taste = g_label_ufs_taste,
+	.ld_dir = G_LABEL_UFS_DIR
+};
diff --git a/sys/modules/geom/Makefile b/sys/modules/geom/Makefile
index 039ae29..880c082 100644
--- a/sys/modules/geom/Makefile
+++ b/sys/modules/geom/Makefile
@@ -8,6 +8,7 @@ SUBDIR=	geom_apple \
 	geom_fox \
 	geom_gate \
 	geom_gpt \
+	geom_label \
 	geom_mbr \
 	geom_nop \
 	geom_pc98 \
diff --git a/sys/modules/geom/geom_label/Makefile b/sys/modules/geom/geom_label/Makefile
new file mode 100644
index 0000000..839a48e
--- /dev/null
+++ b/sys/modules/geom/geom_label/Makefile
@@ -0,0 +1,11 @@
+# $FreeBSD$
+
+.PATH: ${.CURDIR}/../../../geom/label
+
+KMOD=	geom_label
+SRCS=	g_label.c
+SRCS+=	g_label_iso9660.c
+SRCS+=	g_label_msdosfs.c
+SRCS+=	g_label_ufs.c
+
+.include <bsd.kmod.mk>