[Devel] [PATCH 5/5] driver core: Implement shadow directory support for device classes.

[Eric W. Biederman]

This patch enables shadowing on every class directory if struct class
has shadow_ops.

In addition device_del and device_rename were modified to use
sysfs_delete_link and sysfs_rename_link respectively to ensure when
these operations happen in the presence of shadow directories the
work properly.

Signed-off-by: Eric W. Biederman <ebiederm at xmission.com>
---
 drivers/base/class.c   |   30 ++++++++++++++++++++++++++----
 drivers/base/core.c    |   20 +++++++++++---------
 include/linux/device.h |    2 ++
 3 files changed, 39 insertions(+), 13 deletions(-)

diff --git a/drivers/base/class.c b/drivers/base/class.c
index 80bbb20..1ac2b0e 100644
--- a/drivers/base/class.c
+++ b/drivers/base/class.c
@@ -136,6 +136,17 @@ static void remove_class_attrs(struct class * cls)
 	}
 }
 
+static int class_setup_shadowing(struct class *cls)
+{
+	const struct shadow_dir_operations *shadow_ops;
+
+	shadow_ops = cls->shadow_ops;
+	if (!shadow_ops)
+		return 0;
+
+	return sysfs_enable_shadowing(&cls->subsys.kset.kobj, shadow_ops);
+}
+
 int class_register(struct class * cls)
 {
 	int error;
@@ -154,11 +165,22 @@ int class_register(struct class * cls)
 	subsys_set_kset(cls, class_subsys);
 
 	error = subsystem_register(&cls->subsys);
-	if (!error) {
-		error = add_class_attrs(class_get(cls));
-		class_put(cls);
-	}
+	if (error)
+		goto out;
+
+	error = class_setup_shadowing(cls);
+	if (error)
+		goto out_unregister;
+
+	error = add_class_attrs(cls);
+	if (error)
+		goto out_unregister;
+
+out:
 	return error;
+out_unregister:
+	subsystem_unregister(&cls->subsys);
+	goto out;
 }
 
 void class_unregister(struct class * cls)
diff --git a/drivers/base/core.c b/drivers/base/core.c
index 8650401..3d9c5ff 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -519,8 +519,14 @@ static struct kobject * get_device_parent(struct device *dev,
 			return kobj;
 
 		/* or create a new class-directory at the parent device */
-		return kobject_kset_add_dir(&dev->class->class_dirs,
+		kobj = kobject_kset_add_dir(&dev->class->class_dirs,
 					    parent_kobj, dev->class->name);
+
+		/* If we created a new class-directory setup shadowing */
+		if (kobj && dev->class->shadow_ops)
+			sysfs_enable_shadowing(kobj, dev->class->shadow_ops);
+
+		return kobj;
 	}
 
 	if (parent)
@@ -797,8 +803,8 @@ void device_del(struct device * dev)
 		/* If this is not a "fake" compatible device, remove the
 		 * symlink from the class to the device. */
 		if (dev->kobj.parent != &dev->class->subsys.kset.kobj)
-			sysfs_remove_link(&dev->class->subsys.kset.kobj,
-					  dev->bus_id);
+			sysfs_delete_link(&dev->class->subsys.kset.kobj,
+					  &dev->kobj, dev->bus_id);
 		if (parent) {
 #ifdef CONFIG_SYSFS_DEPRECATED
 			char *class_name = make_class_name(dev->class->name,
@@ -1096,6 +1102,8 @@ int device_rename(struct device *dev, char *new_name)
 			goto out_free_old_class;
 		}
 		strlcpy(old_symlink_name, dev->bus_id, BUS_ID_SIZE);
+		sysfs_rename_link(&dev->class->subsys.kset.kobj, &dev->kobj,
+				  old_symlink_name, new_name);
 	}
 
 	strlcpy(dev->bus_id, new_name, BUS_ID_SIZE);
@@ -1113,12 +1121,6 @@ int device_rename(struct device *dev, char *new_name)
 	}
 #endif
 
-	if (dev->class) {
-		sysfs_remove_link(&dev->class->subsys.kset.kobj,
-				  old_symlink_name);
-		sysfs_create_link(&dev->class->subsys.kset.kobj, &dev->kobj,
-				  dev->bus_id);
-	}
 	put_device(dev);
 
 	kfree(new_class_name);
diff --git a/include/linux/device.h b/include/linux/device.h
index de0e73e..8326067 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -199,6 +199,8 @@ struct class {
 
 	int	(*suspend)(struct device *, pm_message_t state);
 	int	(*resume)(struct device *);
+
+	const struct shadow_dir_operations *shadow_ops;
 };
 
 extern int __must_check class_register(struct class *);
-- 
1.5.0.g53756

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