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, 8 insertions, 0 deletions

diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index a63eb4ba7867..7e54bac8c4b0 100644
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -614,6 +614,14 @@ int sysfs_create_subdir(struct kobject *kobj, const char *name,
                           KOBJ_NS_TYPE_NONE, NULL, name, p_sd);
 }
 
+/**
+ *      sysfs_read_ns_type: return associated ns_type
+ *      @kobj: the kobject being queried
+ *
+ *      Each kobject can be tagged with exactly one namespace type
+ *      (i.e. network or user).  Return the ns_type associated with
+ *      this object if any
+ */
 static enum kobj_ns_type sysfs_read_ns_type(struct kobject *kobj)
 {
         const struct kobj_ns_type_operations *ops;