If devstat_new_entry() is passed a unit number of -1 assume that

the devstat is for an "interior" GEOM node and register using the
name argument as a geom identity pointer.  Do not put these devstat
structures on the list returned by the sysctl.

This gives us the ability to tell the two kinds of nodes apart and
leave the current "strictly physical" view of devstat intact without
modifications, yet be able to use devstat for both kinds of devices.

It also saves us bloating struct devstat with another 48 bytes of
space for the name.  At least for now.

Reviewed by:    ken

1 files changed, 12 insertions, 4 deletions

diff --git a/sys/kern/subr_devstat.c b/sys/kern/subr_devstat.c
index 7277dd1..4356020 100644
--- a/sys/kern/subr_devstat.c
+++ b/sys/kern/subr_devstat.c
@@ -80,8 +80,14 @@ devstat_new_entry(const void *dev_name,
 
 	ds = devstat_alloc();
 	mtx_lock(&devstat_mutex);
-	devstat_add_entry(ds, dev_name, unit_number, block_size,
-			  flags, device_type, priority);
+	if (unit_number == -1) {
+		ds->id = dev_name;
+		binuptime(&ds->creation_time);
+		devstat_generation++;
+	} else {
+		devstat_add_entry(ds, dev_name, unit_number, block_size,
+				  flags, device_type, priority);
+	}
 	mtx_unlock(&devstat_mutex);
 	return (ds);
 }
@@ -186,8 +192,10 @@ devstat_remove_entry(struct devstat *ds)
 
 	/* Remove this entry from the devstat queue */
 	atomic_add_acq_int(&ds->sequence1, 1);
-	devstat_num_devs--;
-	STAILQ_REMOVE(devstat_head, ds, devstat, dev_links);
+	if (ds->id == NULL) {
+		devstat_num_devs--;
+		STAILQ_REMOVE(devstat_head, ds, devstat, dev_links);
+	}
 	devstat_free(ds);
 	devstat_generation++;
 	mtx_unlock(&devstat_mutex);