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: Chris Mason <chris.mason@oracle.com>

diff --git a/fs/btrfs/async-thread.c b/fs/btrfs/async-thread.c
index f10c895224aed305cda755bbfb95ee448800e5ef..4b4372df3b6d3b14e813cf1db8b530c94080482a 100644 (file)
--- a/fs/btrfs/async-thread.c
+++ b/fs/btrfs/async-thread.c
@@ -124,14 +124,12 @@ out:
 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 @@ again:
                        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);
        }

diff --git a/fs/btrfs/async-thread.h b/fs/btrfs/async-thread.h
index a562ad8d83aa06f231e28aa9c0e9f1e694bd33e9..fc089b95ec14f24c9a971b44f3718c2029f241ef 100644 (file)
--- a/fs/btrfs/async-thread.h
+++ b/fs/btrfs/async-thread.h
@@ -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;
 };