From e3c78ca524d230bc145e902625e88c392a58ddf3 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Wed, 19 Oct 2011 14:32:38 +0200 Subject: block: reorganize queue draining Reorganize queue draining related code in preparation of queue exit changes. * Factor out actual draining from elv_quiesce_start() to blk_drain_queue(). * Make elv_quiesce_start/end() responsible for their own locking. * Replace open-coded ELVSWITCH clearing in elevator_switch() with elv_quiesce_end(). This patch doesn't cause any visible functional difference. Signed-off-by: Tejun Heo Signed-off-by: Jens Axboe --- block/elevator.c | 37 +++++++++++-------------------------- 1 file changed, 11 insertions(+), 26 deletions(-) (limited to 'block/elevator.c') diff --git a/block/elevator.c b/block/elevator.c index cb332cb7ac6b..74a277ffed39 100644 --- a/block/elevator.c +++ b/block/elevator.c @@ -31,7 +31,6 @@ #include #include #include -#include #include #include #include @@ -606,43 +605,35 @@ void elv_requeue_request(struct request_queue *q, struct request *rq) void elv_drain_elevator(struct request_queue *q) { static int printed; + + lockdep_assert_held(q->queue_lock); + while (q->elevator->ops->elevator_dispatch_fn(q, 1)) ; - if (q->nr_sorted == 0) - return; - if (printed++ < 10) { + if (q->nr_sorted && printed++ < 10) { printk(KERN_ERR "%s: forced dispatching is broken " "(nr_sorted=%u), please report this\n", q->elevator->elevator_type->elevator_name, q->nr_sorted); } } -/* - * Call with queue lock held, interrupts disabled - */ void elv_quiesce_start(struct request_queue *q) { if (!q->elevator) return; + spin_lock_irq(q->queue_lock); queue_flag_set(QUEUE_FLAG_ELVSWITCH, q); + spin_unlock_irq(q->queue_lock); - /* - * make sure we don't have any requests in flight - */ - elv_drain_elevator(q); - while (q->rq.elvpriv) { - __blk_run_queue(q); - spin_unlock_irq(q->queue_lock); - msleep(10); - spin_lock_irq(q->queue_lock); - elv_drain_elevator(q); - } + blk_drain_queue(q); } void elv_quiesce_end(struct request_queue *q) { + spin_lock_irq(q->queue_lock); queue_flag_clear(QUEUE_FLAG_ELVSWITCH, q); + spin_unlock_irq(q->queue_lock); } void __elv_add_request(struct request_queue *q, struct request *rq, int where) @@ -972,7 +963,6 @@ static int elevator_switch(struct request_queue *q, struct elevator_type *new_e) /* * Turn on BYPASS and drain all requests w/ elevator private data */ - spin_lock_irq(q->queue_lock); elv_quiesce_start(q); /* @@ -983,8 +973,8 @@ static int elevator_switch(struct request_queue *q, struct elevator_type *new_e) /* * attach and start new elevator */ + spin_lock_irq(q->queue_lock); elevator_attach(q, e, data); - spin_unlock_irq(q->queue_lock); if (old_elevator->registered) { @@ -999,9 +989,7 @@ static int elevator_switch(struct request_queue *q, struct elevator_type *new_e) * finally exit old elevator and turn off BYPASS. */ elevator_exit(old_elevator); - spin_lock_irq(q->queue_lock); elv_quiesce_end(q); - spin_unlock_irq(q->queue_lock); blk_add_trace_msg(q, "elv switch: %s", e->elevator_type->elevator_name); @@ -1015,10 +1003,7 @@ fail_register: elevator_exit(e); q->elevator = old_elevator; elv_register_queue(q); - - spin_lock_irq(q->queue_lock); - queue_flag_clear(QUEUE_FLAG_ELVSWITCH, q); - spin_unlock_irq(q->queue_lock); + elv_quiesce_end(q); return err; } -- cgit v1.2.3-59-g8ed1b