+static struct mapped_device *dm_find_md(dev_t dev)
+{
+ struct mapped_device *md;
+ unsigned minor = MINOR(dev);
+
+ if (MAJOR(dev) != _major || minor >= (1 << MINORBITS))
+ return NULL;
+
+ mutex_lock(&_minor_lock);
+
+ md = idr_find(&_minor_idr, minor);
+ if (!md || (dm_disk(md)->first_minor != minor))
+ md = NULL;
+
+ mutex_unlock(&_minor_lock);
+
+ return md;
+}
+
+struct mapped_device *dm_get_md(dev_t dev)
+{
+ struct mapped_device *md = dm_find_md(dev);
+
+ if (md)
+ dm_get(md);
+
+ return md;
+}
+
+void *dm_get_mdptr(struct mapped_device *md)
+{
+ return md->interface_ptr;
+}
+
+void dm_set_mdptr(struct mapped_device *md, void *ptr)
+{
+ md->interface_ptr = ptr;
+}
+