On Tue, 10 Jul 2012 17:02:27 -0700 <[email protected]> wrote:
> > The patch below does not apply to the 3.0-stable tree. > If someone wants it applied there, or to any other stable or longterm > tree, then please email the backport, including the original git commit > id to <[email protected]>. > > thanks, > > greg k-h Here it is, against 3.0.36. Thanks, NeilBrown From: Tao Guo <[email protected]> Date: Wed, 13 Jun 2012 21:17:21 +0200 Subject: [PATCH] umem: fix up unplugging commit 32587371ad3db2f9d335de10dbd8cffd4fff5669 upstream Fix a regression introduced by 7eaceaccab5f40 ("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: Tao Guo <[email protected]> Cc: Neil Brown <[email protected]> Cc: Jens Axboe <[email protected]> Cc: Shaohua Li <[email protected]> Cc: <[email protected]> Acked-by: NeilBrown <[email protected]> Signed-off-by: Jens Axboe <[email protected]> diff --git a/drivers/block/umem.c b/drivers/block/umem.c index 031ca72..afa8463 100644 --- a/drivers/block/umem.c +++ b/drivers/block/umem.c @@ -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 int mm_make_request(struct request_queue *q, struct bio *bio) { struct cardinfo *card = q->queuedata; @@ -523,6 +561,8 @@ static int 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 0;
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