1 files changed, 53 insertions, 8 deletions

diff --git a/fs/btrfs/async-thread.c b/fs/btrfs/async-thread.c
index 8e2fec05dbe0..c84ca1f5259a 100644
--- a/fs/btrfs/async-thread.c
+++ b/fs/btrfs/async-thread.c
@@ -16,11 +16,11 @@
  * Boston, MA 021110-1307, USA.
  */
 
-#include <linux/version.h>
 #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
@@ -143,6 +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);
@@ -165,14 +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());
@@ -350,13 +387,14 @@ int btrfs_requeue_work(struct btrfs_work *work)
 {
         struct btrfs_worker_thread *worker = work->worker;
         unsigned long flags;
+        int wake = 0;
 
         if (test_and_set_bit(WORK_QUEUED_BIT, &work->flags))
                 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
@@ -368,10 +406,16 @@ int btrfs_requeue_work(struct btrfs_work *work)
                                &worker->workers->worker_list);
                 spin_unlock_irqrestore(&worker->workers->lock, flags);
         }
+        if (!worker->working) {
+                wake = 1;
+                worker->working = 1;
+        }
 
         spin_unlock_irqrestore(&worker->lock, flags);
-
+        if (wake)
+                wake_up_process(worker->task);
 out:
+
         return 0;
 }
 
@@ -398,9 +442,10 @@ 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