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, 8 insertions, 15 deletions

diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index 834c64cb7f88..878ac3afe1b8 100644
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -730,14 +730,14 @@ static enum kobj_ns_type sysfs_read_ns_type(struct kobject *kobj)
 }
 
 /**
- *      sysfs_create_dir - create a directory for an object.
- *      @kobj:          object we're creating directory for.
+ * sysfs_create_dir_ns - create a directory for an object with a namespace tag
+ * @kobj: object we're creating directory for
+ * @ns: the namespace tag to use
  */
-int sysfs_create_dir(struct kobject *kobj)
+int sysfs_create_dir_ns(struct kobject *kobj, const void *ns)
 {
         enum kobj_ns_type type;
         struct sysfs_dirent *parent_sd, *sd;
-        const void *ns = NULL;
         int error = 0;
 
         BUG_ON(!kobj);
@@ -750,8 +750,6 @@ int sysfs_create_dir(struct kobject *kobj)
         if (!parent_sd)
                 return -ENOENT;
 
-        if (sysfs_ns_type(parent_sd))
-                ns = kobj->ktype->namespace(kobj);
         type = sysfs_read_ns_type(kobj);
 
         error = create_dir(kobj, parent_sd, type, ns, kobject_name(kobj), &sd);
@@ -909,26 +907,21 @@ int sysfs_rename(struct sysfs_dirent *sd,
         return error;
 }
 
-int sysfs_rename_dir(struct kobject *kobj, const char *new_name)
+int sysfs_rename_dir_ns(struct kobject *kobj, const char *new_name,
+                        const void *new_ns)
 {
         struct sysfs_dirent *parent_sd = kobj->sd->s_parent;
-        const void *new_ns = NULL;
-
-        if (sysfs_ns_type(parent_sd))
-                new_ns = kobj->ktype->namespace(kobj);
 
         return sysfs_rename(kobj->sd, parent_sd, new_ns, new_name);
 }
 
-int sysfs_move_dir(struct kobject *kobj, struct kobject *new_parent_kobj)
+int sysfs_move_dir_ns(struct kobject *kobj, struct kobject *new_parent_kobj,
+                      const void *new_ns)
 {
         struct sysfs_dirent *sd = kobj->sd;
         struct sysfs_dirent *new_parent_sd;
-        const void *new_ns = NULL;
 
         BUG_ON(!sd->s_parent);
-        if (sysfs_ns_type(sd->s_parent))
-                new_ns = kobj->ktype->namespace(kobj);
         new_parent_sd = new_parent_kobj && new_parent_kobj->sd ?
                 new_parent_kobj->sd : &sysfs_root;