From b4324feeae304ae39e631a254d238a7d63be004b Mon Sep 17 00:00:00 2001 From: Kiyoshi Ueda Date: Thu, 10 Dec 2009 23:52:16 +0000 Subject: dm: use md pending for in flight IO counting This patch changes the counter for the number of in_flight I/Os to md->pending from q->in_flight in preparation for a later patch. No functional change. Request-based dm used q->in_flight to count the number of in-flight clones assuming the counter is always incremented for an in-flight original request and original:clone is 1:1 relationship. However, it this no longer true for barrier requests. So use md->pending to count the number of in-flight clones. Signed-off-by: Kiyoshi Ueda Signed-off-by: Jun'ichi Nomura Signed-off-by: Alasdair G Kergon --- drivers/md/dm.c | 46 ++++++++++++++++++---------------------------- 1 file changed, 18 insertions(+), 28 deletions(-) (limited to 'drivers/md') diff --git a/drivers/md/dm.c b/drivers/md/dm.c index 634b1da..01d741a 100644 --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -727,23 +727,16 @@ static void end_clone_bio(struct bio *clone, int error) * the md may be freed in dm_put() at the end of this function. * Or do dm_get() before calling this function and dm_put() later. */ -static void rq_completed(struct mapped_device *md, int run_queue) +static void rq_completed(struct mapped_device *md, int rw, int run_queue) { - int wakeup_waiters = 0; - struct request_queue *q = md->queue; - unsigned long flags; - - spin_lock_irqsave(q->queue_lock, flags); - if (!queue_in_flight(q)) - wakeup_waiters = 1; - spin_unlock_irqrestore(q->queue_lock, flags); + atomic_dec(&md->pending[rw]); /* nudge anyone waiting on suspend queue */ - if (wakeup_waiters) + if (!md_in_flight(md)) wake_up(&md->wait); if (run_queue) - blk_run_queue(q); + blk_run_queue(md->queue); /* * dm_put() must be at the end of this function. See the comment above @@ -774,6 +767,7 @@ static void dm_unprep_request(struct request *rq) */ void dm_requeue_unmapped_request(struct request *clone) { + int rw = rq_data_dir(clone); struct dm_rq_target_io *tio = clone->end_io_data; struct mapped_device *md = tio->md; struct request *rq = tio->orig; @@ -788,7 +782,7 @@ void dm_requeue_unmapped_request(struct request *clone) blk_requeue_request(q, rq); spin_unlock_irqrestore(q->queue_lock, flags); - rq_completed(md, 0); + rq_completed(md, rw, 0); } EXPORT_SYMBOL_GPL(dm_requeue_unmapped_request); @@ -827,6 +821,7 @@ static void start_queue(struct request_queue *q) */ static void dm_end_request(struct request *clone, int error) { + int rw = rq_data_dir(clone); struct dm_rq_target_io *tio = clone->end_io_data; struct mapped_device *md = tio->md; struct request *rq = tio->orig; @@ -848,7 +843,7 @@ static void dm_end_request(struct request *clone, int error) blk_end_request_all(rq, error); - rq_completed(md, 1); + rq_completed(md, rw, 1); } /* @@ -1541,12 +1536,13 @@ static void dm_request_fn(struct request_queue *q) struct mapped_device *md = q->queuedata; struct dm_table *map = dm_get_table(md); struct dm_target *ti; - struct request *rq; + struct request *rq, *clone; /* - * For suspend, check blk_queue_stopped() and don't increment - * the number of in-flight I/Os after the queue is stopped - * in dm_suspend(). + * For suspend, check blk_queue_stopped() and increment + * ->pending within a single queue_lock not to increment the + * number of in-flight I/Os after the queue is stopped in + * dm_suspend(). */ while (!blk_queue_plugged(q) && !blk_queue_stopped(q)) { rq = blk_peek_request(q); @@ -1558,8 +1554,11 @@ static void dm_request_fn(struct request_queue *q) goto plug_and_out; blk_start_request(rq); + clone = rq->special; + atomic_inc(&md->pending[rq_data_dir(clone)]); + spin_unlock(q->queue_lock); - map_request(ti, rq->special, md); + map_request(ti, clone, md); spin_lock_irq(q->queue_lock); } @@ -2071,8 +2070,6 @@ static int dm_wait_for_completion(struct mapped_device *md, int interruptible) { int r = 0; DECLARE_WAITQUEUE(wait, current); - struct request_queue *q = md->queue; - unsigned long flags; dm_unplug_all(md->queue); @@ -2082,14 +2079,7 @@ static int dm_wait_for_completion(struct mapped_device *md, int interruptible) set_current_state(interruptible); smp_mb(); - if (dm_request_based(md)) { - spin_lock_irqsave(q->queue_lock, flags); - if (!queue_in_flight(q)) { - spin_unlock_irqrestore(q->queue_lock, flags); - break; - } - spin_unlock_irqrestore(q->queue_lock, flags); - } else if (!md_in_flight(md)) + if (!md_in_flight(md)) break; if (interruptible == TASK_INTERRUPTIBLE && -- cgit v1.1