1 files changed, 47 insertions, 13 deletions

diff --git a/fs/btrfs/async-thread.c b/fs/btrfs/async-thread.c
index 51bfdfc8fcda..502c3d61de62 100644
--- a/fs/btrfs/async-thread.c
+++ b/fs/btrfs/async-thread.c
@@ -25,6 +25,7 @@
 #define WORK_QUEUED_BIT 0
 #define WORK_DONE_BIT 1
 #define WORK_ORDER_DONE_BIT 2
+#define WORK_HIGH_PRIO_BIT 3
 
 /*
  * container for the kthread task pointer and the list of pending work
@@ -36,6 +37,7 @@ struct btrfs_worker_thread {
 
         /* list of struct btrfs_work that are waiting for service */
         struct list_head pending;
+        struct list_head prio_pending;
 
         /* list of worker threads from struct btrfs_workers */
         struct list_head worker_list;
@@ -103,10 +105,16 @@ static noinline int run_ordered_completions(struct btrfs_workers *workers,
 
         spin_lock_irqsave(&workers->lock, flags);
 
-        while (!list_empty(&workers->order_list)) {
-                work = list_entry(workers->order_list.next,
-                                  struct btrfs_work, order_list);
-
+        while (1) {
+                if (!list_empty(&workers->prio_order_list)) {
+                        work = list_entry(workers->prio_order_list.next,
+                                          struct btrfs_work, order_list);
+                } else if (!list_empty(&workers->order_list)) {
+                        work = list_entry(workers->order_list.next,
+                                          struct btrfs_work, order_list);
+                } else {
+                        break;
+                }
                 if (!test_bit(WORK_DONE_BIT, &work->flags))
                         break;
 
@@ -143,8 +151,14 @@ static int worker_loop(void *arg)
         do {
                 spin_lock_irq(&worker->lock);
 again_locked:
-                while (!list_empty(&worker->pending)) {
-                        cur = worker->pending.next;
+                while (1) {
+                        if (!list_empty(&worker->prio_pending))
+                                cur = worker->prio_pending.next;
+                        else if (!list_empty(&worker->pending))
+                                cur = worker->pending.next;
+                        else
+                                break;
+
                         work = list_entry(cur, struct btrfs_work, list);
                         list_del(&work->list);
                         clear_bit(WORK_QUEUED_BIT, &work->flags);
@@ -163,7 +177,6 @@ again_locked:
 
                         spin_lock_irq(&worker->lock);
                         check_idle_worker(worker);
-
                 }
                 if (freezing(current)) {
                         worker->working = 0;
@@ -178,7 +191,8 @@ again_locked:
                                  * jump_in?
                                  */
                                 smp_mb();
-                                if (!list_empty(&worker->pending))
+                                if (!list_empty(&worker->pending) ||
+                                    !list_empty(&worker->prio_pending))
                                         continue;
 
                                 /*
@@ -191,7 +205,8 @@ again_locked:
                                  */
                                 schedule_timeout(1);
                                 smp_mb();
-                                if (!list_empty(&worker->pending))
+                                if (!list_empty(&worker->pending) ||
+                                    !list_empty(&worker->prio_pending))
                                         continue;
 
                                 if (kthread_should_stop())
@@ -200,7 +215,8 @@ again_locked:
                                 /* still no more work?, sleep for real */
                                 spin_lock_irq(&worker->lock);
                                 set_current_state(TASK_INTERRUPTIBLE);
-                                if (!list_empty(&worker->pending))
+                                if (!list_empty(&worker->pending) ||
+                                    !list_empty(&worker->prio_pending))
                                         goto again_locked;
 
                                 /*
@@ -248,6 +264,7 @@ void btrfs_init_workers(struct btrfs_workers *workers, char *name, int max)
         INIT_LIST_HEAD(&workers->worker_list);
         INIT_LIST_HEAD(&workers->idle_list);
         INIT_LIST_HEAD(&workers->order_list);
+        INIT_LIST_HEAD(&workers->prio_order_list);
         spin_lock_init(&workers->lock);
         workers->max_workers = max;
         workers->idle_thresh = 32;
@@ -273,6 +290,7 @@ int btrfs_start_workers(struct btrfs_workers *workers, int num_workers)
                 }
 
                 INIT_LIST_HEAD(&worker->pending);
+                INIT_LIST_HEAD(&worker->prio_pending);
                 INIT_LIST_HEAD(&worker->worker_list);
                 spin_lock_init(&worker->lock);
                 atomic_set(&worker->num_pending, 0);
@@ -396,7 +414,10 @@ int btrfs_requeue_work(struct btrfs_work *work)
                 goto out;
 
         spin_lock_irqsave(&worker->lock, flags);
-        list_add_tail(&work->list, &worker->pending);
+        if (test_bit(WORK_HIGH_PRIO_BIT, &work->flags))
+                list_add_tail(&work->list, &worker->prio_pending);
+        else
+                list_add_tail(&work->list, &worker->pending);
         atomic_inc(&worker->num_pending);
 
         /* by definition we're busy, take ourselves off the idle
@@ -422,6 +443,11 @@ out:
         return 0;
 }
 
+void btrfs_set_work_high_prio(struct btrfs_work *work)
+{
+        set_bit(WORK_HIGH_PRIO_BIT, &work->flags);
+}
+
 /*
  * places a struct btrfs_work into the pending queue of one of the kthreads
  */
@@ -438,7 +464,12 @@ 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);
-                list_add_tail(&work->order_list, &workers->order_list);
+                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);
         } else {
                 INIT_LIST_HEAD(&work->order_list);
@@ -446,7 +477,10 @@ 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);
+        if (test_bit(WORK_HIGH_PRIO_BIT, &work->flags))
+                list_add_tail(&work->list, &worker->prio_pending);
+        else
+                list_add_tail(&work->list, &worker->pending);
         atomic_inc(&worker->num_pending);
         check_busy_worker(worker);