Provide a set of sysctls and tunables to disable device node creation

for specific "kinds" of disk labels - for example, GPT UUIDs.  Reason
for this is that sometimes, other GEOM classes attach to these device
nodes instead of the proper ones - e.g. they attach to /dev/gptid/XXX
instead of /dev/ada0p2, which is annoying.

Reviewed by:	pjd (earlier version)
MFC after:	1 month

9 files changed, 68 insertions, 29 deletions

diff --git a/sys/geom/label/g_label.c b/sys/geom/label/g_label.c
index e39c233..48329aa 100644
--- a/sys/geom/label/g_label.c
+++ b/sys/geom/label/g_label.c
@@ -34,7 +34,6 @@ __FBSDID("$FreeBSD$");
 #include <sys/lock.h>
 #include <sys/mutex.h>
 #include <sys/bio.h>
-#include <sys/sysctl.h>
 #include <sys/malloc.h>
 #include <sys/libkern.h>
 #include <geom/geom.h>
@@ -316,6 +315,8 @@ g_label_taste(struct g_class *mp, struct g_provider *pp, int flags __unused)
 	for (i = 0; g_labels[i] != NULL; i++) {
 		char label[64];
 
+		if (g_labels[i]->ld_enabled == 0)
+			continue;
 		g_topology_unlock();
 		g_labels[i]->ld_taste(cp, label, sizeof(label));
 		g_topology_lock();
diff --git a/sys/geom/label/g_label.h b/sys/geom/label/g_label.h
index 6e5d8f0..06ba2f5 100644
--- a/sys/geom/label/g_label.h
+++ b/sys/geom/label/g_label.h
@@ -30,6 +30,9 @@
 #define	_G_LABEL_H_
 
 #include <sys/endian.h>
+#ifdef _KERNEL
+#include <sys/sysctl.h>
+#endif
 
 #define	G_LABEL_CLASS_NAME	"LABEL"
 
@@ -56,23 +59,34 @@ extern u_int g_label_debug;
 	}								\
 } while (0)
 
+SYSCTL_DECL(_kern_geom_label);
+
+#define	G_LABEL_INIT(kind, label, descr) 				\
+	SYSCTL_NODE(_kern_geom_label, OID_AUTO, kind, CTLFLAG_RD,	\
+	    NULL, "");							\
+	SYSCTL_INT(_kern_geom_label_##kind, OID_AUTO, enable, 		\
+	    CTLFLAG_RW, &label.ld_enabled, 1, descr);			\
+	TUNABLE_INT("kern.geom.label." __XSTRING(kind) ".enable",	\
+	    &label.ld_enabled)
+
 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;
+	int		 ld_enabled;
 };
 
 /* Supported labels. */
-extern const struct g_label_desc g_label_ufs_id;
-extern const struct g_label_desc g_label_ufs_volume;
-extern const struct g_label_desc g_label_iso9660;
-extern const struct g_label_desc g_label_msdosfs;
-extern const struct g_label_desc g_label_ext2fs;
-extern const struct g_label_desc g_label_reiserfs;
-extern const struct g_label_desc g_label_ntfs;
-extern const struct g_label_desc g_label_gpt;
-extern const struct g_label_desc g_label_gpt_uuid;
+extern struct g_label_desc g_label_ufs_id;
+extern struct g_label_desc g_label_ufs_volume;
+extern struct g_label_desc g_label_iso9660;
+extern struct g_label_desc g_label_msdosfs;
+extern struct g_label_desc g_label_ext2fs;
+extern struct g_label_desc g_label_reiserfs;
+extern struct g_label_desc g_label_ntfs;
+extern struct g_label_desc g_label_gpt;
+extern struct g_label_desc g_label_gpt_uuid;
 #endif	/* _KERNEL */
 
 struct g_label_metadata {
diff --git a/sys/geom/label/g_label_ext2fs.c b/sys/geom/label/g_label_ext2fs.c
index 379785f..2e00493 100644
--- a/sys/geom/label/g_label_ext2fs.c
+++ b/sys/geom/label/g_label_ext2fs.c
@@ -86,7 +86,10 @@ exit_free:
 	g_free(fs);
 }
 
-const struct g_label_desc g_label_ext2fs = {
+struct g_label_desc g_label_ext2fs = {
 	.ld_taste = g_label_ext2fs_taste,
-	.ld_dir = "ext2fs"
+	.ld_dir = "ext2fs",
+	.ld_enabled = 1
 };
+
+G_LABEL_INIT(ext2fs, g_label_ext2fs, "Create device nodes for EXT2FS volumes");
diff --git a/sys/geom/label/g_label_gpt.c b/sys/geom/label/g_label_gpt.c
index b186782..3701495 100644
--- a/sys/geom/label/g_label_gpt.c
+++ b/sys/geom/label/g_label_gpt.c
@@ -153,12 +153,17 @@ g_label_gpt_uuid_taste(struct g_consumer *cp, char *label, size_t size)
 	snprintf_uuid(label, size, &part_gpt_entry->ent.ent_uuid);
 }
 
-const struct g_label_desc g_label_gpt = {
+struct g_label_desc g_label_gpt = {
 	.ld_taste = g_label_gpt_taste,
-	.ld_dir = G_LABEL_GPT_VOLUME_DIR
+	.ld_dir = G_LABEL_GPT_VOLUME_DIR,
+	.ld_enabled = 1
 };
 
-const struct g_label_desc g_label_gpt_uuid = {
+struct g_label_desc g_label_gpt_uuid = {
 	.ld_taste = g_label_gpt_uuid_taste,
-	.ld_dir = G_LABEL_GPT_ID_DIR
+	.ld_dir = G_LABEL_GPT_ID_DIR,
+	.ld_enabled = 1
 };
+
+G_LABEL_INIT(gpt, g_label_gpt, "Create device nodes for GPT labels");
+G_LABEL_INIT(gptid, g_label_gpt_uuid, "Create device nodes for GPT UUIDs");
diff --git a/sys/geom/label/g_label_iso9660.c b/sys/geom/label/g_label_iso9660.c
index 7d29bcd..154cefc 100644
--- a/sys/geom/label/g_label_iso9660.c
+++ b/sys/geom/label/g_label_iso9660.c
@@ -78,7 +78,10 @@ g_label_iso9660_taste(struct g_consumer *cp, char *label, size_t size)
 	}
 }
 
-const struct g_label_desc g_label_iso9660 = {
+struct g_label_desc g_label_iso9660 = {
 	.ld_taste = g_label_iso9660_taste,
-	.ld_dir = G_LABEL_ISO9660_DIR
+	.ld_dir = G_LABEL_ISO9660_DIR,
+	.ld_enabled = 1
 };
+
+G_LABEL_INIT(iso9660, g_label_iso9660, "Create device nodes for ISO9660 volume names");
diff --git a/sys/geom/label/g_label_msdosfs.c b/sys/geom/label/g_label_msdosfs.c
index 94d88d2..5f65a72 100644
--- a/sys/geom/label/g_label_msdosfs.c
+++ b/sys/geom/label/g_label_msdosfs.c
@@ -216,7 +216,10 @@ error:
 		g_free(sector);
 }
 
-const struct g_label_desc g_label_msdosfs = {
+struct g_label_desc g_label_msdosfs = {
 	.ld_taste = g_label_msdosfs_taste,
-	.ld_dir = G_LABEL_MSDOSFS_DIR
+	.ld_dir = G_LABEL_MSDOSFS_DIR,
+	.ld_enabled = 1
 };
+
+G_LABEL_INIT(msdosfs, g_label_msdosfs, "Create device nodes for MSDOSFS volumes");
diff --git a/sys/geom/label/g_label_ntfs.c b/sys/geom/label/g_label_ntfs.c
index 4781d7d..1ee3f79 100644
--- a/sys/geom/label/g_label_ntfs.c
+++ b/sys/geom/label/g_label_ntfs.c
@@ -114,7 +114,10 @@ done:
 		g_free(filerecp);
 }
 
-const struct g_label_desc g_label_ntfs = {
+struct g_label_desc g_label_ntfs = {
 	.ld_taste = g_label_ntfs_taste,
-	.ld_dir = G_LABEL_NTFS_DIR
+	.ld_dir = G_LABEL_NTFS_DIR,
+	.ld_enabled = 1
 };
+
+G_LABEL_INIT(ntfs, g_label_ntfs, "Create device nodes for NTFS volumes");
diff --git a/sys/geom/label/g_label_reiserfs.c b/sys/geom/label/g_label_reiserfs.c
index 18ce1ef..a912e97 100644
--- a/sys/geom/label/g_label_reiserfs.c
+++ b/sys/geom/label/g_label_reiserfs.c
@@ -111,7 +111,10 @@ exit_free:
 	g_free(fs);
 }
 
-const struct g_label_desc g_label_reiserfs = {
+struct g_label_desc g_label_reiserfs = {
 	.ld_taste = g_label_reiserfs_taste,
-	.ld_dir = "reiserfs"
+	.ld_dir = "reiserfs",
+	.ld_enabled = 1
 };
+
+G_LABEL_INIT(reiserfs, g_label_reiserfs, "Create device nodes for REISERFS volumes");
diff --git a/sys/geom/label/g_label_ufs.c b/sys/geom/label/g_label_ufs.c
index 8510fc0..b9b0443 100644
--- a/sys/geom/label/g_label_ufs.c
+++ b/sys/geom/label/g_label_ufs.c
@@ -137,13 +137,17 @@ g_label_ufs_id_taste(struct g_consumer *cp, char *label, size_t size)
 	g_label_ufs_taste_common(cp, label, size, G_LABEL_UFS_ID);
 }
 
-
-const struct g_label_desc g_label_ufs_volume = {
+struct g_label_desc g_label_ufs_volume = {
 	.ld_taste = g_label_ufs_volume_taste,
-	.ld_dir = G_LABEL_UFS_VOLUME_DIR
+	.ld_dir = G_LABEL_UFS_VOLUME_DIR,
+	.ld_enabled = 1
 };
 
-const struct g_label_desc g_label_ufs_id = {
+struct g_label_desc g_label_ufs_id = {
 	.ld_taste = g_label_ufs_id_taste,
-	.ld_dir = G_LABEL_UFS_ID_DIR
+	.ld_dir = G_LABEL_UFS_ID_DIR,
+	.ld_enabled = 1
 };
+
+G_LABEL_INIT(ufsid, g_label_ufs_id, "Create device nodes for UFS file system IDs");
+G_LABEL_INIT(ufs, g_label_ufs_volume, "Create device nodes for UFS volume names");