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Commit 32587371 authored by Tao Guo's avatar Tao Guo Committed by Jens Axboe
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umem: fix up unplugging 



Fix a regression introduced by 7eaceacc ("block: remove per-queue
plugging").  In that patch, Jens removed the whole mm_unplug_device()
function, which used to be the trigger to make umem start to work.

We need to implement unplugging to make umem start to work, or I/O will
never be triggered.

Signed-off-by: default avatarTao Guo <Tao.Guo@emc.com>
Cc: Neil Brown <neilb@suse.de>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Shaohua Li <shli@kernel.org>
Cc: <stable@vger.kernel.org>
Acked-by: default avatarNeilBrown <neilb@suse.de>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 047fe360

drivers/block/umem.c

+40 −0
Original line number Diff line number Diff line
@@ -513,6 +513,44 @@ static void process_page(unsigned long data) 
	}

}



struct mm_plug_cb {

	struct blk_plug_cb cb;

	struct cardinfo *card;

};



static void mm_unplug(struct blk_plug_cb *cb)

{

	struct mm_plug_cb *mmcb = container_of(cb, struct mm_plug_cb, cb);



	spin_lock_irq(&mmcb->card->lock);

	activate(mmcb->card);

	spin_unlock_irq(&mmcb->card->lock);

	kfree(mmcb);

}



static int mm_check_plugged(struct cardinfo *card)

{

	struct blk_plug *plug = current->plug;

	struct mm_plug_cb *mmcb;



	if (!plug)

		return 0;



	list_for_each_entry(mmcb, &plug->cb_list, cb.list) {

		if (mmcb->cb.callback == mm_unplug && mmcb->card == card)

			return 1;

	}

	/* Not currently on the callback list */

	mmcb = kmalloc(sizeof(*mmcb), GFP_ATOMIC);

	if (!mmcb)

		return 0;



	mmcb->card = card;

	mmcb->cb.callback = mm_unplug;

	list_add(&mmcb->cb.list, &plug->cb_list);

	return 1;

}



static void mm_make_request(struct request_queue *q, struct bio *bio)

{

	struct cardinfo *card = q->queuedata;
@@ -523,6 +561,8 @@ static void mm_make_request(struct request_queue *q, struct bio *bio) 
	*card->biotail = bio;

	bio->bi_next = NULL;

	card->biotail = &bio->bi_next;

	if (bio->bi_rw & REQ_SYNC || !mm_check_plugged(card))

		activate(card);

	spin_unlock_irq(&card->lock);



	return;