md/dm - remove remains of plug_fn callback.

Now that unplugging is done differently, the unplug_fn callback is
never called, so it can be completely discarded.

Signed-off-by: NeilBrown <neilb@suse.de>

1 files changed, 0 insertions, 1 deletions

diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h
index e2768834f39..32a4423710f 100644
--- a/include/linux/device-mapper.h
+++ b/include/linux/device-mapper.h
@@ -197,7 +197,6 @@ struct dm_target {
 struct dm_target_callbacks {
 	struct list_head list;
 	int (*congested_fn) (struct dm_target_callbacks *, int);
-	void (*unplug_fn)(struct dm_target_callbacks *);
 };
 
 int dm_register_target(struct target_type *t);