sysfs: allow attributes to be added to groups

This patch (as860) adds two new sysfs routines:
sysfs_add_file_to_group() and sysfs_remove_file_from_group().
A later patch adds code that uses the new routines.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Cc: Maneesh Soni <maneesh@in.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

fs/sysfs/file.c

@@ -501,6 +501,30 @@ int sysfs_create_file(struct kobject * kobj, const struct attribute * attr)
 }
 
 
+/**
+ * sysfs_add_file_to_group - add an attribute file to a pre-existing group.
+ * @kobj: object we're acting for.
+ * @attr: attribute descriptor.
+ * @group: group name.
+ */
+int sysfs_add_file_to_group(struct kobject *kobj,
+		const struct attribute *attr, const char *group)
+{
+	struct dentry *dir;
+	int error;
+
+	dir = lookup_one_len(group, kobj->dentry, strlen(group));
+	if (IS_ERR(dir))
+		error = PTR_ERR(dir);
+	else {
+		error = sysfs_add_file(dir, attr, SYSFS_KOBJ_ATTR);
+		dput(dir);
+	}
+	return error;
+}
+EXPORT_SYMBOL_GPL(sysfs_add_file_to_group);
+
+
 /**
  * sysfs_update_file - update the modified timestamp on an object attribute.
  * @kobj: object we're acting for.
@@ -586,6 +610,26 @@ void sysfs_remove_file(struct kobject * kobj, const struct attribute * attr)
 }
 
 
+/**
+ * sysfs_remove_file_from_group - remove an attribute file from a group.
+ * @kobj: object we're acting for.
+ * @attr: attribute descriptor.
+ * @group: group name.
+ */
+void sysfs_remove_file_from_group(struct kobject *kobj,
+		const struct attribute *attr, const char *group)
+{
+	struct dentry *dir;
+
+	dir = lookup_one_len(group, kobj->dentry, strlen(group));
+	if (!IS_ERR(dir)) {
+		sysfs_hash_and_remove(dir, attr->name);
+		dput(dir);
+	}
+}
+EXPORT_SYMBOL_GPL(sysfs_remove_file_from_group);
+
+
 EXPORT_SYMBOL_GPL(sysfs_create_file);
 EXPORT_SYMBOL_GPL(sysfs_remove_file);
 EXPORT_SYMBOL_GPL(sysfs_update_file);

include/linux/sysfs.h

@@ -126,6 +126,11 @@ void sysfs_remove_bin_file(struct kobject *kobj, struct bin_attribute *attr);
 int __must_check sysfs_create_group(struct kobject *,
 					const struct attribute_group *);
 void sysfs_remove_group(struct kobject *, const struct attribute_group *);
+int sysfs_add_file_to_group(struct kobject *kobj,
+		const struct attribute *attr, const char *group);
+void sysfs_remove_file_from_group(struct kobject *kobj,
+		const struct attribute *attr, const char *group);
+
 void sysfs_notify(struct kobject * k, char *dir, char *attr);
 
 
@@ -210,6 +215,18 @@ static inline void sysfs_remove_group(struct kobject * k, const struct attribute
 	;
 }
 
+static inline int sysfs_add_file_to_group(struct kobject *kobj,
+		const struct attribute *attr, const char *group)
+{
+	return 0;
+}
+
+static inline void sysfs_remove_file_from_group(struct kobject *kobj,
+		const struct attribute *attr, const char *group);
+{
+	;
+}
+
 static inline void sysfs_notify(struct kobject * k, char *dir, char *attr)
 {
 }