[PATCH 2/3] sysfs representation of stacked devices (dm)

[Jun'ichi Nomura]

This patch modifies dm driver to create symlinks to/from
underlying devices.

-- 
Jun'ichi Nomura, NEC Solutions (America), Inc.
Exporting stacked device relationship to sysfs (dm)

Signed-off-by: Jun'ichi Nomura <j-nomura@xxxxxxxxxxxxx>

--- linux-2.6.15.orig/drivers/md/dm.c	2006-01-02 22:21:10.000000000 -0500
+++ linux-2.6.15/drivers/md/dm.c	2006-02-14 12:18:13.000000000 -0500
@@ -853,6 +853,7 @@ static int __bind(struct mapped_device *
 
 	dm_table_get(t);
 	dm_table_event_callback(t, event_callback, md);
+	dm_link_device(md, t);
 
 	write_lock(&md->map_lock);
 	md->map = t;
@@ -873,6 +874,7 @@ static void __unbind(struct mapped_devic
 	write_lock(&md->map_lock);
 	md->map = NULL;
 	write_unlock(&md->map_lock);
+	dm_unlink_device(md, map);
 	dm_table_put(map);
 }
 
--- linux-2.6.15.orig/drivers/md/dm.h	2006-01-02 22:21:10.000000000 -0500
+++ linux-2.6.15/drivers/md/dm.h	2006-02-14 12:21:10.000000000 -0500
@@ -94,6 +94,12 @@ int dm_wait_event(struct mapped_device *
 struct gendisk *dm_disk(struct mapped_device *md);
 int dm_suspended(struct mapped_device *md);
 
+/*
+ * kobject linking functions
+ */
+int dm_link_device(struct mapped_device *md, struct dm_table *t);
+int dm_unlink_device(struct mapped_device *md, struct dm_table *t);
+
 /*-----------------------------------------------------------------
  * Functions for manipulating a table.  Tables are also reference
  * counted.
--- linux-2.6.15.orig/drivers/md/dm-table.c	2006-01-02 22:21:10.000000000 -0500
+++ linux-2.6.15/drivers/md/dm-table.c	2006-02-16 23:25:49.000000000 -0500
@@ -53,6 +53,9 @@ struct dm_table {
 	/* events get handed up using this callback */
 	void (*event_fn)(void *);
 	void *event_context;
+
+	/* sysfs deptree */
+	struct kobject slave_dir;
 };
 
 /*
@@ -945,6 +948,43 @@ int dm_table_flush_all(struct dm_table *
 	return ret;
 }
 
+/* create sysfs symlinks between mapped device and underlying devices */
+int dm_link_device(struct mapped_device *md, struct dm_table *t)
+{
+	struct list_head *d, *devices;
+	struct kobject *md_kobj;
+
+	md_kobj = &dm_disk(md)->kobj;
+	stackdev_init(&t->slave_dir, md_kobj);
+
+	devices = dm_table_get_devices(t);
+	for (d = devices->next; d != devices; d = d->next) {
+		struct dm_dev *dd = list_entry(d, struct dm_dev, list);
+		stackdev_link(dd->bdev, &t->slave_dir, md_kobj);
+	}
+
+	return 0;
+}
+
+/* remove sysfs symlinks between mapped device and underlying devices */
+int dm_unlink_device(struct mapped_device *md, struct dm_table *t)
+{
+	struct list_head *d, *devices;
+	struct kobject *md_kobj;
+
+	md_kobj = &dm_disk(md)->kobj;
+
+	devices = dm_table_get_devices(t);
+	for (d = devices->next; d != devices; d = d->next) {
+		struct dm_dev *dd = list_entry(d, struct dm_dev, list);
+		stackdev_unlink(dd->bdev, &t->slave_dir, md_kobj);
+	}
+
+	stackdev_clear(&t->slave_dir);
+
+	return 0;
+}
+
 EXPORT_SYMBOL(dm_vcalloc);
 EXPORT_SYMBOL(dm_get_device);
 EXPORT_SYMBOL(dm_put_device);