diff mbox

[CFT,08/10] sysfs: Add support for permanently empty directories to serve as mount points.

Message ID 87fv6xtgr2.fsf_-_@x220.int.ebiederm.org (mailing list archive)
State New, archived
Headers show

Commit Message

Eric W. Biederman May 16, 2015, 2:09 a.m. UTC
Add two functions sysfs_create_mount_point and sysfs_remove_mount_point
that hang a permanently empty directory off of a kobject or remove a
permanently emptpy directory hanging from a kobject.  Export these new
functions so modular filesystems can use them.

Cc: stable@vger.kernel.org
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---
 fs/sysfs/dir.c        | 34 ++++++++++++++++++++++++++++++++++
 include/linux/sysfs.h | 16 ++++++++++++++++
 2 files changed, 50 insertions(+)

Comments

Greg KH May 18, 2015, 1:14 p.m. UTC | #1
On Fri, May 15, 2015 at 09:09:53PM -0500, Eric W. Biederman wrote:
> 
> Add two functions sysfs_create_mount_point and sysfs_remove_mount_point
> that hang a permanently empty directory off of a kobject or remove a
> permanently emptpy directory hanging from a kobject.  Export these new
> functions so modular filesystems can use them.
> 
> Cc: stable@vger.kernel.org
> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
> ---
>  fs/sysfs/dir.c        | 34 ++++++++++++++++++++++++++++++++++
>  include/linux/sysfs.h | 16 ++++++++++++++++
>  2 files changed, 50 insertions(+)

Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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diff mbox

Patch

diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index 0b45ff42f374..94374e435025 100644
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -121,3 +121,37 @@  int sysfs_move_dir_ns(struct kobject *kobj, struct kobject *new_parent_kobj,
 
 	return kernfs_rename_ns(kn, new_parent, kn->name, new_ns);
 }
+
+/**
+ * sysfs_create_mount_point - create an always empty directory
+ * @parent_kobj:  kobject that will contain this always empty directory
+ * @name: The name of the always empty directory to add
+ */
+int sysfs_create_mount_point(struct kobject *parent_kobj, const char *name)
+{
+	struct kernfs_node *kn, *parent = parent_kobj->sd;
+
+	kn = kernfs_create_empty_dir(parent, name);
+	if (IS_ERR(kn)) {
+		if (PTR_ERR(kn) == -EEXIST)
+			sysfs_warn_dup(parent, name);
+		return PTR_ERR(kn);
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(sysfs_create_mount_point);
+
+/**
+ *	sysfs_remove_mount_point - remove an always empty directory.
+ *	@parent_kobj: kobject that will contain this always empty directory
+ *	@name: The name of the always empty directory to remove
+ *
+ */
+void sysfs_remove_mount_point(struct kobject *parent_kobj, const char *name)
+{
+	struct kernfs_node *parent = parent_kobj->sd;
+
+	kernfs_remove_by_name_ns(parent, name, NULL);
+}
+EXPORT_SYMBOL_GPL(sysfs_remove_mount_point);
diff --git a/include/linux/sysfs.h b/include/linux/sysfs.h
index 99382c0df17e..3e7e41acc451 100644
--- a/include/linux/sysfs.h
+++ b/include/linux/sysfs.h
@@ -210,6 +210,10 @@  int __must_check sysfs_rename_dir_ns(struct kobject *kobj, const char *new_name,
 int __must_check sysfs_move_dir_ns(struct kobject *kobj,
 				   struct kobject *new_parent_kobj,
 				   const void *new_ns);
+int __must_check sysfs_create_mount_point(struct kobject *parent_kobj,
+					  const char *name);
+void sysfs_remove_mount_point(struct kobject *parent_kobj,
+			      const char *name);
 
 int __must_check sysfs_create_file_ns(struct kobject *kobj,
 				      const struct attribute *attr,
@@ -298,6 +302,18 @@  static inline int sysfs_move_dir_ns(struct kobject *kobj,
 	return 0;
 }
 
+static inline int sysfs_create_mount_point(struct kobject *parent_kobj,
+					   const char *name)
+{
+	return 0;
+}
+
+static inline void sysfs_remove_mount_point(struct kobject *parent_kobj,
+					    const char *name)
+{
+	return 0;
+}
+
 static inline int sysfs_create_file_ns(struct kobject *kobj,
 				       const struct attribute *attr,
 				       const void *ns)