}
 
 #define NUM_FEATURE_BITS 64
-static char btrfs_unknown_feature_names[3][NUM_FEATURE_BITS][13];
-static struct btrfs_feature_attr btrfs_feature_attrs[3][NUM_FEATURE_BITS];
+#define BTRFS_FEATURE_NAME_MAX 13
+static char btrfs_unknown_feature_names[FEAT_MAX][NUM_FEATURE_BITS][BTRFS_FEATURE_NAME_MAX];
+static struct btrfs_feature_attr btrfs_feature_attrs[FEAT_MAX][NUM_FEATURE_BITS];
 
-static const u64 supported_feature_masks[3] = {
+static const u64 supported_feature_masks[FEAT_MAX] = {
        [FEAT_COMPAT]    = BTRFS_FEATURE_COMPAT_SUPP,
        [FEAT_COMPAT_RO] = BTRFS_FEATURE_COMPAT_RO_SUPP,
        [FEAT_INCOMPAT]  = BTRFS_FEATURE_INCOMPAT_SUPP,
        btrfs_sysfs_rm_device_link(fs_info->fs_devices, NULL);
 }
 
-const char * const btrfs_feature_set_names[3] = {
+const char * const btrfs_feature_set_names[FEAT_MAX] = {
        [FEAT_COMPAT]    = "compat",
        [FEAT_COMPAT_RO] = "compat_ro",
        [FEAT_INCOMPAT]  = "incompat",
                        if (fa->kobj_attr.attr.name)
                                continue;
 
-                       snprintf(name, 13, "%s:%u",
+                       snprintf(name, BTRFS_FEATURE_NAME_MAX, "%s:%u",
                                 btrfs_feature_set_names[set], i);
 
                        fa->kobj_attr.attr.name = name;
 
 extern u64 btrfs_debugfs_test;
 
 enum btrfs_feature_set {
-       FEAT_COMPAT,
+       FEAT_COMPAT = 0,
        FEAT_COMPAT_RO,
        FEAT_INCOMPAT,
        FEAT_MAX
 }
 
 char *btrfs_printable_features(enum btrfs_feature_set set, u64 flags);
-extern const char * const btrfs_feature_set_names[3];
+extern const char * const btrfs_feature_set_names[FEAT_MAX];
 extern struct kobj_type space_info_ktype;
 extern struct kobj_type btrfs_raid_ktype;
 int btrfs_sysfs_add_device_link(struct btrfs_fs_devices *fs_devices,