sysfs: remove ktype->namespace() invocations in directory code

For some unrecognizable reason, namespace information is communicated
to sysfs through ktype->namespace() callback when there's *nothing*
which needs the use of a callback.  The whole sequence of operations
is completely synchronous and sysfs operations simply end up calling
back into the layer which just invoked it in order to find out the
namespace information, which is completely backwards, obfuscates
what's going on and unnecessarily tangles two separate layers.

This patch doesn't remove ktype->namespace() but shifts its handling
to kobject layer.  We probably want to get rid of the callback in the
long term.

This patch adds an explicit param to sysfs_{create|rename|move}_dir()
and renames them to sysfs_{create|rename|move}_dir_ns(), respectively.
ktype->namespace() invocations are moved to the calling sites of the
above functions.  A new helper kboject_namespace() is introduced which
directly tests kobj_ns_type_operations->type which should give the
same result as testing sysfs_fs_type(parent_sd) and returns @kobj's
namespace tag as necessary.  kobject_namespace() is extern as it will
be used from another file in the following patches.

This patch should be an equivalent conversion without any functional
difference.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Kay Sievers <kay@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 24 insertions, 4 deletions

diff --git a/lib/kobject.c b/lib/kobject.c
index 962175134702..85fb3a161b21 100644
--- a/lib/kobject.c
+++ b/lib/kobject.c
@@ -18,6 +18,24 @@
 #include <linux/stat.h>
 #include <linux/slab.h>
 
+/**
+ * kobject_namespace - return @kobj's namespace tag
+ * @kobj: kobject in question
+ *
+ * Returns namespace tag of @kobj if its parent has namespace ops enabled
+ * and thus @kobj should have a namespace tag associated with it.  Returns
+ * %NULL otherwise.
+ */
+const void *kobject_namespace(struct kobject *kobj)
+{
+        const struct kobj_ns_type_operations *ns_ops = kobj_ns_ops(kobj);
+
+        if (!ns_ops || ns_ops->type == KOBJ_NS_TYPE_NONE)
+                return NULL;
+
+        return kobj->ktype->namespace(kobj);
+}
+
 /*
  * populate_dir - populate directory with attributes.
  * @kobj: object we're working on.
@@ -46,8 +64,9 @@ static int populate_dir(struct kobject *kobj)
 
 static int create_dir(struct kobject *kobj)
 {
-        int error = 0;
-        error = sysfs_create_dir(kobj);
+        int error;
+
+        error = sysfs_create_dir_ns(kobj, kobject_namespace(kobj));
         if (!error) {
                 error = populate_dir(kobj);
                 if (error)
@@ -428,7 +447,7 @@ int kobject_rename(struct kobject *kobj, const char *new_name)
                 goto out;
         }
 
-        error = sysfs_rename_dir(kobj, new_name);
+        error = sysfs_rename_dir_ns(kobj, new_name, kobject_namespace(kobj));
         if (error)
                 goto out;
 
@@ -472,6 +491,7 @@ int kobject_move(struct kobject *kobj, struct kobject *new_parent)
                 if (kobj->kset)
                         new_parent = kobject_get(&kobj->kset->kobj);
         }
+
         /* old object path */
         devpath = kobject_get_path(kobj, GFP_KERNEL);
         if (!devpath) {
@@ -486,7 +506,7 @@ int kobject_move(struct kobject *kobj, struct kobject *new_parent)
         sprintf(devpath_string, "DEVPATH_OLD=%s", devpath);
         envp[0] = devpath_string;
         envp[1] = NULL;
-        error = sysfs_move_dir(kobj, new_parent);
+        error = sysfs_move_dir_ns(kobj, new_parent, kobject_namespace(kobj));
         if (error)
                 goto out;
         old_parent = kobj->parent;