sysfs, kernfs: introduce kernfs_create_dir[_ns]()

Introduce kernfs interface to manipulate a directory which takes and
returns sysfs_dirents.

create_dir() is renamed to kernfs_create_dir_ns() and its argumantes
and return value are updated.  create_dir() usages are replaced with
kernfs_create_dir_ns() and sysfs_create_subdir() usages are replaced
with kernfs_create_dir().  Dup warnings are handled explicitly by
sysfs users of the kernfs interface.

sysfs_enable_ns() is renamed to kernfs_enable_ns().

This patch doesn't introduce any behavior changes.

v2: Dummy implementation for !CONFIG_SYSFS updated to return -ENOSYS.

v3: kernfs_enable_ns() added.

v4: Refreshed on top of "sysfs: drop kobj_ns_type handling, take #2"
    so that this patch removes sysfs_enable_ns().

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 17 insertions, 0 deletions

diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h
index 8cb673875715..e8b73d4a08d2 100644
--- a/include/linux/kernfs.h
+++ b/include/linux/kernfs.h
@@ -17,6 +17,9 @@ struct sysfs_dirent;
 
 #ifdef CONFIG_SYSFS
 
+struct sysfs_dirent *kernfs_create_dir_ns(struct sysfs_dirent *parent,
+                                          const char *name, void *priv,
+                                          const void *ns);
 struct sysfs_dirent *kernfs_create_link(struct sysfs_dirent *parent,
                                         const char *name,
                                         struct sysfs_dirent *target);
@@ -25,11 +28,17 @@ int kernfs_remove_by_name_ns(struct sysfs_dirent *parent, const char *name,
                              const void *ns);
 int kernfs_rename_ns(struct sysfs_dirent *sd, struct sysfs_dirent *new_parent,
                      const char *new_name, const void *new_ns);
+void kernfs_enable_ns(struct sysfs_dirent *sd);
 int kernfs_setattr(struct sysfs_dirent *sd, const struct iattr *iattr);
 
 #else   /* CONFIG_SYSFS */
 
 static inline struct sysfs_dirent *
+kernfs_create_dir_ns(struct sysfs_dirent *parent, const char *name, void *priv,
+                     const void *ns)
+{ return ERR_PTR(-ENOSYS); }
+
+static inline struct sysfs_dirent *
 kernfs_create_link(struct sysfs_dirent *parent, const char *name,
                    struct sysfs_dirent *target)
 { return ERR_PTR(-ENOSYS); }
@@ -45,12 +54,20 @@ static inline int kernfs_rename_ns(struct sysfs_dirent *sd,
                                    const char *new_name, const void *new_ns)
 { return -ENOSYS; }
 
+static inline void kernfs_enable_ns(struct sysfs_dirent *sd) { }
+
 static inline int kernfs_setattr(struct sysfs_dirent *sd,
                                  const struct iattr *iattr)
 { return -ENOSYS; }
 
 #endif  /* CONFIG_SYSFS */
 
+static inline struct sysfs_dirent *
+kernfs_create_dir(struct sysfs_dirent *parent, const char *name, void *priv)
+{
+        return kernfs_create_dir_ns(parent, name, priv, NULL);
+}
+
 static inline int kernfs_remove_by_name(struct sysfs_dirent *parent,
                                         const char *name)
 {