blk: centralize non-request unplug handling.

Both md and umem has similar code for getting notified on an
blk_finish_plug event.
Centralize this code in block/ and allow each driver to
provide its distinctive difference.

Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 6 insertions, 2 deletions

diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 3816ce8a08fc..607ca228f47e 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -922,11 +922,15 @@ struct blk_plug {
 };
 #define BLK_MAX_REQUEST_COUNT 16
 
+struct blk_plug_cb;
+typedef void (*blk_plug_cb_fn)(struct blk_plug_cb *);
 struct blk_plug_cb {
         struct list_head list;
-        void (*callback)(struct blk_plug_cb *);
+        blk_plug_cb_fn callback;
+        void *data;
 };
-
+extern struct blk_plug_cb *blk_check_plugged(blk_plug_cb_fn unplug,
+                                             void *data, int size);
 extern void blk_start_plug(struct blk_plug *);
 extern void blk_finish_plug(struct blk_plug *);
 extern void blk_flush_plug_list(struct blk_plug *, bool);