sysfs: Comment sysfs directory tagging logic

Add some in-line comments to explain the new infrastructure, which
was introduced to support sysfs directory tagging with namespaces.
I think an overall description someplace might be good too, but it
didn't really seem to fit into Documentation/filesystems/sysfs.txt,
which appears more geared toward users, rather than maintainers, of
sysfs.

(Tejun, please let me know if I can make anything clearer or failed
altogether to comment something that should be commented.)

Signed-off-by: Serge E. Hallyn <serue@us.ibm.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 11 insertions, 0 deletions

diff --git a/include/linux/kobject.h b/include/linux/kobject.h
index d9456f69904f..b60d2dfe4e69 100644
--- a/include/linux/kobject.h
+++ b/include/linux/kobject.h
@@ -136,12 +136,23 @@ struct kobj_attribute {
 
 extern const struct sysfs_ops kobj_sysfs_ops;
 
+/*
+ * Namespace types which are used to tag kobjects and sysfs entries.
+ * Network namespace will likely be the first.
+ */
 enum kobj_ns_type {
 	KOBJ_NS_TYPE_NONE = 0,
 	KOBJ_NS_TYPES
 };
 
 struct sock;
+
+/*
+ * Callbacks so sysfs can determine namespaces
+ *   @current_ns: return calling task's namespace
+ *   @netlink_ns: return namespace to which a sock belongs (right?)
+ *   @initial_ns: return the initial namespace (i.e. init_net_ns)
+ */
 struct kobj_ns_type_operations {
 	enum kobj_ns_type type;
 	const void *(*current_ns)(void);