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-rw-r--r--fs/btrfs/async-thread.c50
1 files changed, 44 insertions, 6 deletions
diff --git a/fs/btrfs/async-thread.c b/fs/btrfs/async-thread.c
index f2e80f3768ec..c84ca1f5259a 100644
--- a/fs/btrfs/async-thread.c
+++ b/fs/btrfs/async-thread.c
@@ -19,7 +19,8 @@
#include <linux/kthread.h>
#include <linux/list.h>
#include <linux/spinlock.h>
-# include <linux/freezer.h>
+#include <linux/freezer.h>
+#include <linux/ftrace.h>
#include "async-thread.h"
#define WORK_QUEUED_BIT 0
@@ -142,6 +143,7 @@ static int worker_loop(void *arg)
struct btrfs_work *work;
do {
spin_lock_irq(&worker->lock);
+again_locked:
while (!list_empty(&worker->pending)) {
cur = worker->pending.next;
work = list_entry(cur, struct btrfs_work, list);
@@ -164,14 +166,50 @@ static int worker_loop(void *arg)
check_idle_worker(worker);
}
- worker->working = 0;
if (freezing(current)) {
+ worker->working = 0;
+ spin_unlock_irq(&worker->lock);
refrigerator();
} else {
- set_current_state(TASK_INTERRUPTIBLE);
spin_unlock_irq(&worker->lock);
- if (!kthread_should_stop())
+ if (!kthread_should_stop()) {
+ cpu_relax();
+ /*
+ * we've dropped the lock, did someone else
+ * jump_in?
+ */
+ smp_mb();
+ if (!list_empty(&worker->pending))
+ continue;
+
+ /*
+ * this short schedule allows more work to
+ * come in without the queue functions
+ * needing to go through wake_up_process()
+ *
+ * worker->working is still 1, so nobody
+ * is going to try and wake us up
+ */
+ schedule_timeout(1);
+ smp_mb();
+ if (!list_empty(&worker->pending))
+ continue;
+
+ /* still no more work?, sleep for real */
+ spin_lock_irq(&worker->lock);
+ set_current_state(TASK_INTERRUPTIBLE);
+ if (!list_empty(&worker->pending))
+ goto again_locked;
+
+ /*
+ * this makes sure we get a wakeup when someone
+ * adds something new to the queue
+ */
+ worker->working = 0;
+ spin_unlock_irq(&worker->lock);
+
schedule();
+ }
__set_current_state(TASK_RUNNING);
}
} while (!kthread_should_stop());
@@ -355,8 +393,8 @@ int btrfs_requeue_work(struct btrfs_work *work)
goto out;
spin_lock_irqsave(&worker->lock, flags);
- atomic_inc(&worker->num_pending);
list_add_tail(&work->list, &worker->pending);
+ atomic_inc(&worker->num_pending);
/* by definition we're busy, take ourselves off the idle
* list
@@ -405,9 +443,9 @@ int btrfs_queue_worker(struct btrfs_workers *workers, struct btrfs_work *work)
spin_lock_irqsave(&worker->lock, flags);
+ list_add_tail(&work->list, &worker->pending);
atomic_inc(&worker->num_pending);
check_busy_worker(worker);
- list_add_tail(&work->list, &worker->pending);
/*
* avoid calling into wake_up_process if this thread has already
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