block: Enhance new plugging support to support general callbacks
md/raid requires an unplug callback, but as it does not uses
requests the current code cannot provide one.
So allow arbitrary callbacks to be attached to the blk_plug.
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index ec0357d..f3f7879 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -860,8 +860,13 @@
struct blk_plug {
unsigned long magic;
struct list_head list;
+ struct list_head cb_list;
unsigned int should_sort;
};
+struct blk_plug_cb {
+ struct list_head list;
+ void (*callback)(struct blk_plug_cb *);
+};
extern void blk_start_plug(struct blk_plug *);
extern void blk_finish_plug(struct blk_plug *);
@@ -887,7 +892,7 @@
{
struct blk_plug *plug = tsk->plug;
- return plug && !list_empty(&plug->list);
+ return plug && (!list_empty(&plug->list) || !list_empty(&plug->cb_list));
}
/*