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/block/blk-core.c b/block/blk-core.c
index 78b7b0c..77edf05 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -2638,6 +2638,7 @@
plug->magic = PLUG_MAGIC;
INIT_LIST_HEAD(&plug->list);
+ INIT_LIST_HEAD(&plug->cb_list);
plug->should_sort = 0;
/*
@@ -2678,6 +2679,24 @@
q->unplugged_fn(q);
}
+static void flush_plug_callbacks(struct blk_plug *plug)
+{
+ LIST_HEAD(callbacks);
+
+ if (list_empty(&plug->cb_list))
+ return;
+
+ list_splice_init(&plug->cb_list, &callbacks);
+
+ while (!list_empty(&callbacks)) {
+ struct blk_plug_cb *cb = list_first_entry(&callbacks,
+ struct blk_plug_cb,
+ list);
+ list_del(&cb->list);
+ cb->callback(cb);
+ }
+}
+
void blk_flush_plug_list(struct blk_plug *plug, bool from_schedule)
{
struct request_queue *q;
@@ -2688,6 +2707,7 @@
BUG_ON(plug->magic != PLUG_MAGIC);
+ flush_plug_callbacks(plug);
if (list_empty(&plug->list))
return;
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));
}
/*