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Commit 4e3f9c50 authored by Chris Mason's avatar Chris Mason
Browse files

Btrfs: keep irqs on more often in the worker threads 



The btrfs worker thread spinlock was being used both for the
queueing of IO and for the processing of ordered events.

The ordered events never happen from end_io handlers, and so they
don't need to use the _irq version of spinlocks.  This adds a
dedicated lock to the ordered lists so they don't have to run
with irqs off.

Signed-off-by: default avatarChris Mason <chris.mason@oracle.com>
parent 40431d6c

fs/btrfs/async-thread.c

+13 −10
Original line number Diff line number Diff line
@@ -124,14 +124,12 @@ static void check_pending_worker_creates(struct btrfs_worker_thread *worker) 
static noinline int run_ordered_completions(struct btrfs_workers *workers,

					    struct btrfs_work *work)

{

	unsigned long flags;



	if (!workers->ordered)

		return 0;



	set_bit(WORK_DONE_BIT, &work->flags);



	spin_lock_irqsave(&workers->lock, flags);

	spin_lock(&workers->order_lock);



	while (1) {

		if (!list_empty(&workers->prio_order_list)) {
@@ -154,17 +152,17 @@ static noinline int run_ordered_completions(struct btrfs_workers *workers, 
		if (test_and_set_bit(WORK_ORDER_DONE_BIT, &work->flags))

			break;



		spin_unlock_irqrestore(&workers->lock, flags);

		spin_unlock(&workers->order_lock);



		work->ordered_func(work);



		/* now take the lock again and call the freeing code */

		spin_lock_irqsave(&workers->lock, flags);

		spin_lock(&workers->order_lock);

		list_del(&work->order_list);

		work->ordered_free(work);

	}



	spin_unlock_irqrestore(&workers->lock, flags);

	spin_unlock(&workers->order_lock);

	return 0;

}
@@ -345,6 +343,7 @@ void btrfs_init_workers(struct btrfs_workers *workers, char *name, int max) 
	INIT_LIST_HEAD(&workers->order_list);

	INIT_LIST_HEAD(&workers->prio_order_list);

	spin_lock_init(&workers->lock);

	spin_lock_init(&workers->order_lock);

	workers->max_workers = max;

	workers->idle_thresh = 32;

	workers->name = name;
@@ -374,6 +373,7 @@ int btrfs_start_workers(struct btrfs_workers *workers, int num_workers) 
		INIT_LIST_HEAD(&worker->prio_pending);

		INIT_LIST_HEAD(&worker->worker_list);

		spin_lock_init(&worker->lock);



		atomic_set(&worker->num_pending, 0);

		atomic_set(&worker->refs, 1);

		worker->workers = workers;
@@ -453,10 +453,8 @@ static struct btrfs_worker_thread *find_worker(struct btrfs_workers *workers) 
again:

	spin_lock_irqsave(&workers->lock, flags);

	worker = next_worker(workers);

	spin_unlock_irqrestore(&workers->lock, flags);



	if (!worker) {

		spin_lock_irqsave(&workers->lock, flags);

		if (workers->num_workers >= workers->max_workers) {

			goto fallback;

		} else if (workers->atomic_worker_start) {
@@ -469,6 +467,7 @@ static struct btrfs_worker_thread *find_worker(struct btrfs_workers *workers) 
			goto again;

		}

	}

	spin_unlock_irqrestore(&workers->lock, flags);

	return worker;



fallback:
@@ -552,14 +551,18 @@ int btrfs_queue_worker(struct btrfs_workers *workers, struct btrfs_work *work) 


	worker = find_worker(workers);

	if (workers->ordered) {

		spin_lock_irqsave(&workers->lock, flags);

		/*

		 * you're not allowed to do ordered queues from an

		 * interrupt handler

		 */

		spin_lock(&workers->order_lock);

		if (test_bit(WORK_HIGH_PRIO_BIT, &work->flags)) {

			list_add_tail(&work->order_list,

				      &workers->prio_order_list);

		} else {

			list_add_tail(&work->order_list, &workers->order_list);

		}

		spin_unlock_irqrestore(&workers->lock, flags);

		spin_unlock(&workers->order_lock);

	} else {

		INIT_LIST_HEAD(&work->order_list);

	}

fs/btrfs/async-thread.h

+3 −0
Original line number Diff line number Diff line
@@ -99,6 +99,9 @@ struct btrfs_workers { 
	/* lock for finding the next worker thread to queue on */

	spinlock_t lock;



	/* lock for the ordered lists */

	spinlock_t order_lock;



	/* extra name for this worker, used for current->name */

	char *name;

};