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Commit 048c9374 authored by NeilBrown's avatar NeilBrown Committed by Jens Axboe
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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: default avatarNeilBrown <neilb@suse.de>
Signed-off-by: default avatarJens Axboe <jaxboe@fusionio.com>
parent a1b49cb7

block/blk-core.c

+20 −0
Original line number Diff line number Diff line
@@ -2638,6 +2638,7 @@ void blk_start_plug(struct blk_plug *plug) 


	plug->magic = PLUG_MAGIC;

	INIT_LIST_HEAD(&plug->list);

	INIT_LIST_HEAD(&plug->cb_list);

	plug->should_sort = 0;



	/*
@@ -2678,6 +2679,24 @@ static void queue_unplugged(struct request_queue *q, unsigned int depth, 
		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 @@ void blk_flush_plug_list(struct blk_plug *plug, bool from_schedule) 


	BUG_ON(plug->magic != PLUG_MAGIC);



	flush_plug_callbacks(plug);

	if (list_empty(&plug->list))

		return;

include/linux/blkdev.h

+6 −1
Original line number Diff line number Diff line
@@ -860,8 +860,13 @@ extern void blk_put_queue(struct request_queue *); 
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 @@ static inline bool blk_needs_flush_plug(struct task_struct *tsk) 
{

	struct blk_plug *plug = tsk->plug;



	return plug && !list_empty(&plug->list);

	return plug && (!list_empty(&plug->list) || !list_empty(&plug->cb_list));

}



/*